JP7767804B2 - Low dielectric constant resin forming composition, low dielectric member, and electronic device using same - Google Patents

Description

The present invention relates to a polymerizable compound that can be prepared into a varnish without a solvent, a composition for forming a low dielectric constant resin using the compound, and a low dielectric member using the composition. In particular, the present invention relates to a material for a high-frequency substrate and its peripheral materials, and a low dielectric member and an electronic device using the same.
Furthermore, since the varnish can be prepared without using a solvent, it is also useful as an insulating material for various electronic components, such as a material for printed wiring boards, adhesive films, semiconductor sealants, and conductive adhesives.

In recent years, with the shift to 5G and even beyond 5G and 6G in communication devices, the frequency of electrical signals on electronic boards and the frequency of radio waves transmitted and received by antennas have increased, resulting in problems with signal loss due to signal processing circuit boards and antenna boards. Therefore, resin materials used in boards are required to have low dielectric constants and low dielectric dissipation factors, and resins such as liquid crystal polymers (LCPs), polyphenylene ethers (PPEs), cycloolefin polymers (COPs), and fluororesins (PTFEs) have begun to be used in place of conventional polyimides and epoxy resins.
Low-dielectric substrates have a dielectric constant of 3.0 or less, and those containing high thermal conductive fillers have a dielectric constant of 3.5 or less, and there is a demand for the development of materials with even lower dielectric constants (Non-Patent Document 1).

However, current materials for high-frequency circuit boards are thermoplastic resins, which require high-temperature molding and bonding, and have many difficult-to-use aspects, such as poor adhesion between resins and to the copper foil that serves as the electrodes. Patent Document 1 examines the molecular structure of liquid crystal polymers to further reduce their dielectric constant. However, liquid crystal polymers have a high melting point, requiring processing temperatures of 350°C or higher, making thermal lamination and bonding difficult.

Patent Document 2 examines the possibility of turning PPE resin into a varnish by increasing its solubility in organic solvents. By examining the molecular structure of PPE resin, it became possible to form a film from PPE resin using a coating method, making it suitable for use in insulating varnishes. However, there are many issues, such as the need to use an organic solvent with high dissolving power and the possibility of re-dissolving in the solvent when laminating multiple layers. Therefore, there is a need to develop a low-dielectric-constant resin that can be applied like an insulating coating varnish and cured easily.

Meanwhile, in the field of resin materials for various electronic components, such as printed wiring boards, resist inks, conductive pastes, and underfill agents, which require high fluidity, the development of solvent-free resin compositions and solvent-free varnishes has been active in response to recent environmental issues such as VOC problems. The same is true for low-dielectric components for high-frequency substrates, where, for example, liquid epoxy resins such as low-molecular-weight bisphenol-type epoxy resins and solvent-free varnishes containing epoxy resin curing agents as acid anhydrides are widely used.
Patent Document 3 describes a cured product that exhibits high heat resistance, low dielectric constant, and low dielectric loss tangent, obtained by curing a curable resin composition containing an epoxy resin or the like as a main component without using an organic solvent. However, high-temperature conditions of 100°C or higher are required to cure the epoxy groups in the epoxy resin, and the cured product does not have sufficient low dielectric properties at high frequencies, and because it is an epoxy resin, the transparency of the cured product is low.

Furthermore, the amount of information processed by data processing LSIs is rapidly increasing, resulting in a corresponding increase in the amount of heat generated, and so there is a growing demand for the electronic substrate itself to have better heat dissipation properties. Patent Document 4 states that when highly linear polymerizable liquid crystal compounds are oriented and cured, they have higher thermal conductivity in the orientation direction than ordinary thermosetting resins, and Patent Document 5 states that by combining polymerizable liquid crystal compounds with heat-dissipating fillers, it is possible to form thermosetting resin materials with even higher thermal conductivity. However, these examples focus primarily on high thermal conductivity, and do not consider low dielectric properties.

Japanese Patent Application Laid-Open No. 2019-189734 JP 2009-67894 A JP 2013-166941 A Japanese Patent Application Laid-Open No. 2006-265527 Republished Publication No. 2015/170744

RF World No. 40, pp. 97-111, 2017

The problem to be solved by the present invention is to provide a composition for forming a low dielectric constant resin that exhibits high heat resistance and a low dielectric constant and low dielectric loss tangent in the high frequency range after curing, and a composition for forming a low dielectric constant resin that can be prepared into a varnish-like form using no solvent or a small amount of organic solvent.
Another object of the present invention is to provide a composition for forming a low dielectric constant resin that exhibits high transparency or high heat dissipation in addition to the above properties.
By using the composition for forming a low dielectric constant resin of the present invention, it is possible to provide a material that is suitable for applications such as next-generation communication devices and radars in the high-frequency range, or for applications that require high fluidity and little environmental impact such as VOC issues.

As a result of extensive research to solve the above-mentioned problems, the inventors discovered that a composition containing at least one compound selected from compound (1) having a cis-1,4-cyclohexylene structure and its polymers maintains fluidity in a temperature range centered around room temperature, can be prepared into a varnish-like form without solvent or with the use of a small amount of organic solvent, can be molded by solution processing, and after curing exhibits high heat resistance, a low dielectric constant and low dielectric dissipation factor in the high-frequency range, and high thermal conductivity, thereby achieving the present invention.

[1] A first aspect of the present invention is
A composition for forming a low dielectric constant resin, comprising at least one compound selected from the group consisting of cis-1,4-cyclohexylene structures represented by formula (1) and polymers thereof:

In formula (1),
At least one of A ¹ and A ² is cis-1,4-cyclohexylene;
A ¹ , A ² , and A ³ are independently cis-1,4-cyclohexylene, trans-1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, bicyclo[2.2.2]octo-1,4-diyl, bicyclo[3.1.0]hex-3,6-diyl, or fluorene-2,7-diyl; in these rings, at least one —CH ₂ — may be replaced by —O—, at least one —CH═ may be replaced by —N═, and at least one hydrogen may be a halogen or an alkyl having 1 to 12 carbon atoms in which at least one hydrogen may be replaced by a halogen; in this alkyl, at least one —CH ₂ — may be replaced by —O—, —CO—, —COO—, —OCO—, —C═C—, or —CH═CF—;
Z ¹ , Z ² , Z ³ , and Z ⁴ are independently a single bond or alkylene having 1 to 20 carbon atoms; in this alkylene, at least one —CH ₂ — may be replaced by —O—, —S—, —CO—, —COO—, —OCO—, —SO ₂ —, —CH═CH—, —CF═CF—, —CH═N—, —N═CH—, or —N═N—, and at least one hydrogen may be replaced by halogen;
m1 is 0, 1, or 2;
In the formula, when a plurality of ^A3 or ^Z3 is present, they may be the same or different,
R ^1a and R ^1b are independently a group selected from the polymerizable groups represented by formulae (PG-1) to (PG-6),

In formulas (PG-1) to (PG-6),
R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms;
q is 0 or 1;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.

[2] A second aspect of the present invention is
The composition for forming a low dielectric constant resin according to [1], which contains at least one selected from a trans isomer compound in which all cis-1,4-cyclohexylene structures in formula (1) are replaced with trans-1,4-cyclohexylene structures, and a polymer thereof, and the ratio of cis isomers to the isomer mixture is 50 wt % or more.

[3] A third aspect of the present invention is
The composition for forming a low dielectric constant resin according to [1] or [2], wherein the cured low dielectric constant resin has a relative dielectric constant of less than 3.0 at 10 GHz.

[4] A fourth aspect of the present invention is
The composition for forming a low dielectric constant resin according to any one of [1] to [3], which is solvent-free.

[5] A fifth aspect of the present invention is
The composition for forming a low dielectric constant resin according to any one of [1] to [3], wherein the composition contains 10 wt % or less of an organic solvent.

[6] A sixth aspect of the present invention is
The composition for forming a low dielectric constant resin according to any one of [1] to [5], wherein, in formula (1), R ^1a and R ^1b are independently a polymerizable group represented by formula (PG-1), (PG-5), or (PG-6).

[7] A seventh aspect of the present invention is
The composition for forming a low dielectric constant resin according to [1], wherein the compound of formula (1) is a compound represented by any one of formulas (1-1) to (1-3):

In formulas (1-1) to (1-3),
^A1 is cis-1,4-cyclohexylene;
^A2 and ^A3 are independently cis-1,4-cyclohexylene, trans-1,4-cyclohexylene, 1,4-phenylene in which at least one hydrogen may be replaced by halogen or alkylene having 1 to 10 carbon atoms, bicyclo[2.2.2]octo-1,4-diyl, bicyclo[3.1.0]hex-3,6-diyl, or fluorene-2,7-diyl in which at least one hydrogen may be replaced by halogen or alkylene having 1 to 10 carbon atoms;
Z ¹ , Z ² , Z ³ , and Z ⁴ are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —COO—, —OCO—, —CH═CH—COO—, —OCO—CH═CH—, —(CH ₂ ) _a —COO—, —OCO—(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —OCF ₂ —, or —CF ₂ O—; where a is an integer from 1 to 20;
In the formula, when a plurality of ^A3 or ^Z3 is present, they may be the same or different,
R ^1a and R ^1b are independently a polymerizable group represented by formula (PG-1), (PG-5), or (PG-6),

In formulas (PG-1), (PG-5), and (PG-6),
R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms;
q is 0 or 1;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.

[8] The eighth aspect of the present invention is
The composition for forming a low dielectric constant resin according to [1], wherein the compound of formula (1) is a compound represented by formula (1-1-1) or (1-1-2).

In formulas (1-1-1) to (1-1-2),
^A1 is cis-1,4-cyclohexylene;
The cyclohexane ring represented by the hexagon is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene;
Z ¹ , Z ² and Z ⁴ are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —COO—, —OCO—, —CH═CH—COO—, —OCO—CH═CH—, —(CH ₂ ) _a —COO—, —OCO—(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —OCF ₂ —, or —CF ₂ O—; where a is an integer from 1 to 20;
X is fluorine or methyl;
n is an integer from 0 to 4,
When n is 2 or more, and when there are a plurality of X's in the formula, they may be the same or different,
R ^1a and R ^1b are independently a polymerizable group represented by formula (PG-1), (PG-5), or (PG-6),

In formulas (PG-1), (PG-5), and (PG-6),
R ^b is hydrogen, halogen, —CF3, or alkyl having 1 to 5 carbon atoms;
q is 0 or 1;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.

[9] A ninth aspect of the present invention is
The composition for forming a low dielectric constant resin according to [1], wherein the compound of formula (1) is a compound represented by any one of formulas (1-2-1) to (1-2-4):

In formulas (1-2-1) to (1-2-4),
^A1 is cis-1,4-cyclohexylene;
The cyclohexane ring represented by the hexagon is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene;
Z ¹ , Z ² , Z ³ and Z ⁴ are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —COO—, —OCO—, —CH═CH—COO—, —OCO—CH═CH—, —CH ₂ CH ₂ —COO—, —OCO—CH ₂ CH ₂ —, —SO ₂ —, —CH═CH—, —OCF ₂ —, or —CF ₂ O—; where a is an integer from 1 to 20;
X is fluorine or methyl;
n is an integer from 0 to 4,
When n is 2 or more, and when there are a plurality of X's in the formula, they may be the same or different,
R ^1a and R ^1b are independently a polymerizable group represented by formula (PG-1), (PG-5), or (PG-6),

In formulas (PG-1), (PG-5), and (PG-6),
R ^b is hydrogen, halogen, —CF ₃ or alkyl having 1 to 5 carbon atoms;
q is 0 or 1;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.

[10] A tenth aspect of the present invention is
The composition for forming a low dielectric constant resin according to [1], wherein the compound of formula (1) is a compound represented by any one of formulas (1-3-1) to (1-3-7):

In formulas (1-3-1) to (1-3-7),
^A1 is cis-1,4-cyclohexylene;
The cyclohexane ring represented by the hexagon is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene;
Z ¹ , Z ² , Z ³ and Z ⁴ are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —CH═CH—, —COO—, —OCO—, —CH═CH-COO—, —OCO-CH═CH—, —(CH ₂ ) _a -COO—, —OCO-(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —CH═CH—, —OCF ₂ —, or —CF ₂ O—; where a is an integer of 1 to 20;
In the formula, Z ³ may be the same or different,
X is fluorine or methyl;
n is an integer from 0 to 4,
When n is 2 or more, and when there are a plurality of X's in the formula, they may be the same or different,
R ^1a and R ^1b are independently polymerizable groups represented by formulas (PG-1), (PG-5), and (PG-6),

In formulas (PG-1), (PG-5) and (PG-6),
R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms;
q is 0 or 1;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.

[11] An eleventh aspect of the present invention is
The composition for forming a low dielectric constant resin according to [1], wherein in formula (1), R ^1a and R ^1b are polymerizable groups represented by formula (PG-1).

In formula (PG-1),
R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.

[12] A twelfth aspect of the present invention is
A composition containing at least one compound selected from the group consisting of cis-isomer compounds represented by formula (1-1-1a), (1-1-2a), and formulas (1-2-1a) to (1-2-4a), and polymers thereof,
The composition contains at least one selected from a trans isomer compound in which all cis-1,4-cyclohexylene structures of the cis isomer compound are replaced with trans-1,4-cyclohexylene structures, and a polymer thereof;
The ratio of cis isomers to the isomer mixture is 50 wt % or more,
and a composition for forming a low dielectric constant resin, the low dielectric constant resin being cured and formed has a relative dielectric constant of less than 3.0 at 10 GHz.

In formulas (1-1-1a), (1-1-2a), and (1-2-1a) to (1-2-4a),
^A1 is cis-1,4-cyclohexylene;
The cyclohexane ring represented by the hexagon is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene;
^Z2 and ^Z3 are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —COO—, —OCO—, —CH═CH—COO—, —OCO—CH═CH—, —(CH ₂ ) _a —COO—, —OCO—(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —OCF ₂ —, or —CF ₂ O—; where a is an integer of 1 to 20;
m is an integer from 0 to 20;
M is a single bond or oxygen;
X is fluorine or methyl;
n is an integer from 0 to 4,
When n is 2 or more, and when there are a plurality of X's in the formula, they may be the same or different,
R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms;
When there are a plurality of R ^b , m or M in the formula, they may be the same or different.

[13] A thirteenth aspect of the present invention is
The composition for forming a low dielectric constant resin according to any one of [1] to [12], which contains a non-polymerizable liquid crystal compound.

[14] A fourteenth aspect of the present invention is
The composition for forming a low dielectric constant resin according to any one of [1] to [13], which contains an inorganic filler.

[15] A fifteenth aspect of the present invention is
The composition for forming a low dielectric constant resin according to [14], wherein the inorganic filler is at least one selected from the group consisting of silicon compounds such as spherical silica, pulverized silica, hollow silica, and fumed silica, and metal oxides such as aluminum nitride, boron nitride, silicon nitride, diamond, graphite, silicon carbide, magnesium oxide, aluminum oxide, zinc oxide, titanium oxide, tin oxide, aluminum oxide, and calcium oxide.

[16] A sixteenth aspect of the present invention is
The composition for forming a low dielectric constant resin according to any one of [1] to [15], which contains a fibrous reinforcing material.

[17] A seventeenth aspect of the present invention is
The composition for forming a low dielectric constant resin according to [16], wherein the fibrous reinforcing material is at least one selected from the group consisting of glass cloth, low dielectric glass cloth, carbon fiber, carbon nanotube, polyamide fiber, aramid fiber, polyparaphenylene benzobisoxazole fiber, liquid crystalline polyester fiber, silicate whisker, alumina whisker, magnesium oxide whisker, zinc oxide whisker, and aluminum nitride whisker.

[18] The eighteenth aspect of the present invention is
A low dielectric constant resin insulating film which is a polymer molded product obtained by curing the composition for forming a low dielectric constant resin according to any one of [1] to [17] with heat or ultraviolet light.

[19] A nineteenth aspect of the present invention is
A low dielectric constant resin film or a low dielectric constant resin sheet, which is a polymer molded product obtained by curing the composition for forming a low dielectric constant resin according to any one of [1] to [17] with heat or ultraviolet light.

[20] A twentieth aspect of the present invention is
A low dielectric constant resin part which is a polymer molded product obtained by curing the composition for forming a low dielectric constant resin according to any one of [1] to [17] with heat or ultraviolet light.

[21] A twenty-first aspect of the present invention is
An electronic device using the polymer formed body according to any one of [18] to [20].

The composition of the present invention, which contains at least one compound selected from compounds having a cis-1,4-cyclohexylene structure and polymers thereof, is a composition for forming a low dielectric constant resin that exhibits high heat resistance and a low dielectric constant and low dielectric loss tangent in the high frequency range after curing, and can be prepared into a varnish-like form using no solvent or a small amount of organic solvent.Furthermore, the composition is a composition for forming a low dielectric constant resin that exhibits high transparency or high heat dissipation in addition to the above properties.
The cured product obtained by curing the composition of the present invention has low dielectric properties as well as high heat dissipation and transparency, and excellent properties such as chemical stability, heat resistance, hardness, and mechanical strength, and is therefore suitable for applications such as low dielectric circuit boards, low dielectric antenna substrates, low dielectric coating films, low dielectric adhesives, next-generation communication devices and radars in the high-frequency range, etc. Furthermore, since the composition can be prepared into a varnish-like form using no solvent or no more than 10 wt % of an organic solvent, it can be used as a material suitable for applications requiring low environmental impact such as VOC issues and high fluidity.

The following provides a detailed description of a composition for forming a low-dielectric-constant resin containing at least one selected from the cis-isomer compounds having a cis-1,4-cyclohexane structure of the present invention and polymers thereof; a low-dielectric-constant resin insulating film, a low-dielectric-constant resin sheet, and a low-dielectric-constant resin part, which are polymer molded articles formed by curing the composition with heat or ultraviolet light; and electronic devices using the polymer molded articles.

The terms used in this specification are as follows.
"Compound (1)" means a cis-isomer compound having a cis-1,4-cyclohexane structure represented by the above formula (1), and may also mean at least one type of compound represented by formula (1). The same applies to "compound (1-1)", and compounds (1-1), (1-2), and (1-3) may also be collectively referred to as "compound (1)". When one compound (1) has multiple ^A3s , any two ^A3s may be the same or different. When multiple compounds (1) have ^A3s , any two ^A3s may be the same or different. This rule also applies to other symbols, groups, etc., such as ^Z3 , R ^b , and X.
The term "polymer (1)" refers to at least one polymer obtained by polymerizing compound (1). As with "compound (1)," polymers of compounds (1-1), (1-2), and (1-3) may also be collectively referred to as "polymer (1)."
"Composition (1)" means a composition containing at least one selected from the compound (1) and the polymer (1).

1) Compound (1)
The compound (1) having a cis-1,4-cyclohexylene structure of the present invention combines the characteristics of an aliphatic cyclic structure, such as a high clearing point, an extremely low dielectric constant, low dielectric loss, and low viscosity. In addition, the compound having a cis-1,4-cyclohexylene structure often has a lower melting point and exhibits fluidity around room temperature compared to a compound having a trans-1,4-cyclohexylene structure at the same site. The use of the compound (1) having a cis-1,4-cyclohexylene structure makes it possible to easily prepare a composition (1) that can be applied without solvent or with the use of a small amount of organic solvent. Such a composition can be used as a suitable material for applications requiring high fluidity and low environmental impact, such as VOE issues.
Furthermore, compound (1) of the present invention has a polymerizable group and preferably a rod-shaped mesogenic skeleton, preferably has few conjugated or polar groups, preferably has high molecular linearity and symmetry, high polymerization reactivity, a wide liquid temperature range at room temperature, good miscibility, etc. That is, when compound (1) is mixed with other rod-shaped compounds or polymerizable compounds, it easily becomes homogeneous.
In addition, compounds with high molecular linearity may exhibit liquid crystallinity. "Liquid crystal compound" is a general term for compounds having a liquid crystal phase such as a nematic phase or a smectic phase, and compounds that do not have a liquid crystal phase but have physical properties specific to liquid crystals such as dielectric anisotropy, refractive index anisotropy, and magnetic susceptibility anisotropy, and are useful as components of liquid crystal compositions. When a composition containing compound (1) of the present invention exhibits liquid crystallinity, it becomes easy to perform an orientation treatment within the liquid crystal temperature range, and the molecular orientation can be controlled in the same way as by stretching a thermoplastic resin.
The cis-isomer compound of the present invention having at least one cis-1,4-cyclohexylene structure represented by formula (1) is composed of a ring structure, a bonding group, a terminal group, etc. The ring structure, the bonding group, and the terminal group may be collectively referred to as "ring structure A,""bonding group Z," and the terminal group "R ¹ ," respectively.
The physical properties such as the melting point of compound (1) can be adjusted as desired by appropriately selecting the ring structure A, the bonding group Z, and the terminal group R ^1. The effects of the ring structure, the bonding group, and the terminal group on the physical properties of compound (1), as well as preferred examples thereof, are described below.
The meaning of phrases such as "at least one -CH ₂ - in the alkyl may be replaced with -O-, -CO-, etc." is shown as an example. For example, groups in which at least one -CH ₂ - in C ₄ H ₉ - is replaced with -O- or -CH=CH- include C ₃ H ₇ O-, CH ₃ -O-(CH ₂ ) ₃ -, CH ₃ -O-CH ₂ -O-, H ₂ C=CH-(CH ₂ ) ₃ -, CH ₃ -CH=CH-(CH ₂ ) ₂ -, CH ₃ -CH=CH-CH ₂ -O-, etc. Thus, the word "at least one" means "at least one selected without distinction." In consideration of the stability of the compound, CH ₃ —O—CH ₂ —O—, in which oxygen atoms are not adjacent to each other, is more preferable than CH ₃ —OO—CH ₂ —, in which oxygen atoms are adjacent to each other.

<Ring Structure A: A ¹ , A ² and A ³ >
At least one of the ring structures ^A1 and ^A2 of compound (1) is cis-1,4-cyclohexylene. When at least one ring is cis-1,4-cyclohexylene, as described above, effects such as a high clearing point, a very low dielectric constant, low dielectric loss, and low viscosity can be expected. Furthermore, since the compound often has a low melting point and exhibits fluidity around room temperature, it becomes possible to easily prepare a composition that can be used to form a film by a coating method without using a solvent or a small amount of an organic solvent.

In the compound (1), it is essential that at least one of the ring structures A ¹ and A ² is cis-1,4-cyclohexylene, but the ring structure A can be selected appropriately from various ring structures in addition to cis-1,4-cyclohexylene.
Preferred examples of the ring structure A of the compound (1) include cis-1,4-cyclohexylene, trans-1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2,5-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene, pyridine-2,5-diyl, and 3-fluoropyridine-2,5-diyl. yl, pyrimidine-2,5-diyl, pyridazine-3,6-diyl, naphthalene-2,6-diyl, tetrahydronaphthalene-2,6-diyl, fluorene-2,7-diyl, 9-methylfluorene-2,7-diyl, 9,9-dimethylfluorene-2,7-diyl, 9-ethylfluorene-2,7-diyl, 9-fluorofluorene-2,7-diyl, 9,9-difluorofluorene-2,7-diyl, and the like.
More preferred examples include cis-1,4-cyclohexylene, trans-1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2-methyl-1,4-phenylene, etc. Particularly preferred examples are cis-1,4-cyclohexylene, trans-1,4-cyclohexylene, and 1,4-phenylene.

The configuration of 1,3-dioxane-2,5-diyl or tetrahydronaphthalene-2,6-diyl may be either the cis or trans isomer. The cis isomer has a low melting point, while the trans isomer exhibits high linearity and low dielectric constant. 2-Fluoro-1,4-phenylene and 3-fluoro-1,4-phenylene are structurally identical, so the latter is not exemplified. This rule also applies to the relationship between 2,5-difluoro-1,4-phenylene and 3,6-difluoro-1,4-phenylene, etc.

When at least one ring in the ring structure A is 1,4-phenylene, the orientational order parameter and the magnetic anisotropy are large, and when at least two rings are 1,4-phenylene, the clearing point is high.
Preferred examples of 1,4-phenylene groups in which at least one hydrogen atom on the 1,4-phenylene ring may be replaced include fluorine, alkyl having 1 to 5 carbon atoms, _-CF3 , or _-OCF3 , which lower the melting point and increase the solubility. Furthermore, the molecular polarizability is reduced, resulting in a low relative dielectric constant. Furthermore, the molecular motion is suppressed, resulting in low dielectric loss.
When at least one ring in the ring structure A is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene, the clearing point is high, the dielectric constant is very low, the dielectric loss is low, and the viscosity is small. When at least two rings are cis-1,4-cyclohexylene or trans-1,4-cyclohexylene, the clearing point is high, the dielectric constant is very low, the dielectric loss is low, and the viscosity is small. In the case of cis-1,4-cyclohexylene, the melting point is low, and in the case of trans-1,4-cyclohexylene, the linearity is high and the dielectric constant is low. When at least one ring in the ring structure A is a fused ring such as a naphthalene ring, a decahydronaphthalene ring, or a fluorene ring, the molecular volume is large and the dielectric constant is low.

When the ring structure A of compound (1) has two rings, the viscosity is low, and when it has three or more rings, the clearing point is high. In this specification, six-membered rings and fused rings containing six-membered rings are generally considered to be rings, and single three-, four-, or five-membered rings, for example, are not considered to be rings. Furthermore, fused rings such as a naphthalene ring, decahydronaphthalene ring, and fluorene ring are considered to be single rings.

<Bound Group Z: Z ¹ , Z ² , Z ³ and Z ⁴ >
Preferred examples of the linking group Z in compound (1) are a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —COO—, —OCO—, —CH═CH—COO—, —OCO—CH═CH—, —(CH ₂ ) _a —COO—, —OCO—(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —OCF ₂ —, or —CF ₂ O—, where a is an integer of 1 to 20.
More preferred examples include a single bond, —(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a —, —O(CH ₂ ) _a O—, —COO—, and —OCO—, where a is an integer of 1 to 20.
Particularly preferred examples are a single bond, —(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a —, or —O(CH ₂ ) _a O—, where a is an integer of 1-20.

When the bonding group Z is a single bond, -( _CH2 ) _a- , -( _CH2 ) _aO- , -O( _CH2 ) _a- , -O( _CH2 ) _aO- , _-CF2O- , or _-OCF2- , the viscosity is low. When the bonding group Z is -( _CH2 ) _a- , -( _CH2 ) _aO- , -O(CH2)a-, or -O( _CH2 ) _aO- , where a is about 2 to ₁₂ , _the melting point is low, the solubility in organic solvents is high, and the molecular length is long, so the melting point is low and the dielectric dissipation factor is small.

<Terminal Groups R ¹ : R ^1a and R ^1b >
The terminal group R ¹ of the compound (1) is a polymerizable group represented by any one of formulas (PG-1) to (PG-6).

In formulae (PG-1) to (PG-6), R ^b is hydrogen, halogen, —CF ₃ or alkyl having 1 to 5 carbon atoms, and q is 0 or 1.
When there are a plurality of Rb ^'s , they may be the same or different.

Preferred examples of the terminal group R ¹ of compound (1) include polymerizable groups represented by formulae (PG-1a) to (PG-1d), (PG-2a), (PG-3a), (PG-4a), (PG-5a) to (PG-5d), and (PG-6a) to (PG-6c).

Among these preferred polymerizable groups, (PG-1a) to (PG-1d), (PG-2a), and (PG-4a) have an α,β-unsaturated ketone structure and can be polymerized by various means to produce polymers with higher molecular weights. (PG-3a) has a vinyl group adjacent to an electron-donating group and can be polymerized by various means to produce polymers with higher molecular weights. (PG-5a) to (PG-5d) and (PG-6a) to (PG-6c) have strained cyclic ethers and can be polymerized by various means to produce polymers with higher molecular weights.

The polymerizable groups represented by formulae (PG-1) to (PG-6) can be appropriately selected depending on the production conditions of the low dielectric constant resin. For example, when a low dielectric constant resin film is produced by commonly used photocuring, the acrylic group or methacrylic group represented by formula (PG-1) is preferred from the viewpoints of high curability, solubility in organic solvents, ease of handling, etc.
When a low dielectric constant resin film is produced by heat curing, a maleimide group represented by formula (PG-2a), an epoxy group represented by formula (PG-5a), or an oxetane group represented by formula (PG-5b) is preferred from the viewpoints of heat resistance, thermal conductivity, etc., and a maleimide group is particularly preferred when a low dielectric constant is required.

As described above, a compound having the desired physical properties can be obtained by appropriately selecting the types of ring structure A, bonding group Z, and terminal group ^R1 , the number of rings, etc. Preferred examples of compound (1) include formulas (1-1-1) to (1-1-2), (1-2-1) to (1-2-4), and (1-3-1) to (1-3-7).

In the formulas (1-1-1) to (1-1-2), (1-2-1) to (1-2-4), and (1-3-1) to (1-3-7),
^A1 is cis-1,4-cyclohexylene, and the cyclohexane ring represented by a hexagon is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene;
Z ¹ , Z ² , Z ³ and Z ⁴ are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —CH═CH—, —COO—, —OCO—, —CH═CH-COO—, —OCO-CH═CH—, —(CH ₂ ) _a -COO—, —OCO-(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —CH═CH—, —OCF _{2 —, or —CF 2 O—} , where a is an integer of 1 to 20, and Z ³ in the formula may be the same or different;
X is fluorine or methyl, n is an integer of 0 to 4, including the case where n is 2 or more, and when there are multiple Xs in the formula, they may be the same or different,
R ^1a and R ^1b are independently polymerizable groups represented by formulas (PG-1), (PG-5), and (PG-6),

In formulas (PG-1), (PG-5) and (PG-6), R ^b is hydrogen, halogen, —CF ₃ or alkyl having 1 to 5 carbon atoms, q is 0 or 1, and when there are multiple R ^b's in the formula, they may be the same or different.

More preferred examples of compound (1) are shown below.

In formulas (1-1-1a) to (1-1-2a) and formulas (1-2-1a) to (1-2-4a),
^A1 is cis-1,4-cyclohexylene, and the cyclohexane ring represented by a hexagon is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene;
Z ² and Z ³ are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —COO—, —OCO—, —CH═CH—COO—, —OCO—CH═CH—, —(CH ₂ ) _a —COO—, —OCO—(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —OCF ₂ —, or —CF ₂ O—, where a is an integer of 1 to 20;
m is an integer of 0 to 20, M is a single bond or oxygen, X is fluorine or methyl, n is an integer of 0 to 4, including the case where n is 2 or more, and when there are multiple Xs in the formula, they may be the same or different, and R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms, and when there are multiple R ^{b s} , m s, or M s in the formula, they may be the same or different.

[Method for synthesizing compound (1)]
Compound (1) can be synthesized by combining known techniques in organic synthetic chemistry. Methods for introducing desired terminal groups, ring structures, and bonding groups into starting materials are described in, for example, Houben-Wyle, Methods of Organic Chemistry, Georg Thieme Verlag, Stuttgart, Organic Syntheses, John Wily & Sons, Inc., Organic Reactions, John Wily & Sons, Inc., Comprehensive Organic Synthesis, Pergamon Press, and New Experimental Chemistry Lectures (Maruzen).

Methods for introducing the bonding group Z are explained in the following schemes 1 to 9. In these schemes, MSG ¹ and MSG ² represent monovalent organic groups having at least one ring, and Hal represents a halogen. The multiple MSG ¹ (or MSG ² ) used in the following schemes may be the same or different. Compounds (1A) to (1M) in the following schemes correspond to the above-mentioned compound (1). These methods can be applied to the synthesis of optically active compound (1) and optically inactive compound (1).

(Scheme 1) Compounds in which Z is a Single Bond As shown below, compound (1A) in which a single bond has been introduced between MSG ¹ and MSG ² can be synthesized by reacting arylboronic acid (S1) with compound (S2) synthesized by a known method in the presence of an aqueous carbonate solution and a catalyst such as tetrakis(triphenylphosphine)palladium. This compound (1A) can also be synthesized by reacting compound (S3) synthesized by a known method with n-butyllithium and then zinc chloride, followed by further reaction with compound (S2) in the presence of a catalyst such as dichlorobis(triphenylphosphine)palladium.

(Scheme 2) Compounds where Z is -CH=CH- As shown below, a phosphorus ylide generated by reacting a phosphonium salt (S5), synthesized by a known method, with a base such as potassium t-butoxide is reacted with an aldehyde (S4) to synthesize a compound (1B) in which -CH=CH- is introduced between MSG ¹ and MSG ^2. Depending on the reaction conditions and substrate, a cis isomer may be produced, and the cis isomer can be isomerized to a trans isomer by a known method, as necessary.

(Scheme 3) Compounds where Z is -(CH ₂ ) ₂ - As shown below, compound (1C) having -(CH ₂ ) ₂ - between MSG ¹ and MSG ² can be synthesized by hydrogenating compound (1B) obtained as described above in the presence of a catalyst such as palladium on carbon.

(Scheme 4) Compounds where Z is -(CF ₂ ) _{2 - As shown below, compound (1D) having -(CF 2 ) 2} - between MSG ¹ and MSG ² can be synthesized by fluorinating diketone (S6) with sulfur tetrafluoride in the presence of a hydrogen fluoride catalyst according to the method described in J. Am. Chem. Soc., ₂₀₀₁ , ₁₂₃ , 5414.

(Scheme 5) Compounds where Z is -(CH ₂ ) ₄ - As shown below, a compound having -(CH ₂ ) ₂ -CH=CH- can be synthesized by using phosphonium salt (S7) instead of phosphonium salt (S5) according to the method of Scheme 2, and then catalytically hydrogenating this in the same manner as in Scheme 3 above to synthesize compound (1E) in which -(CH ₂ ) ₄ - is introduced between MSG ¹ and MSG ² .

(Scheme 6) Compounds where Z is -CH ₂ O- or -OCH ₂ - As shown below, compound (S4) is reduced with a reducing agent such as sodium borohydride to obtain compound (S8). This is then halogenated with hydrobromic acid or the like to obtain compound (S9). Compound (S9) is reacted with compound (S10) in the presence of potassium carbonate or the like to synthesize compound (1F), in which -OCH ₂ - (or -CH ₂ O-) is introduced between MSG ¹ and MSG ² .

(Scheme 7) Compounds where Z is -COO- or -OCO- As shown below, compound (S3) is reacted with n-butyllithium and then carbon dioxide to obtain carboxylic acid (S11). Compound (S11) is then subjected to a dehydration reaction with phenol (S10) in the presence of DCC (1,3-dicyclohexylcarbodiimide) and DMAP (4-dimethylaminopyridine), to synthesize compound (1G) in which -COO- (or -OCO-) is introduced between MSG ¹ and MSG ² .

(Scheme 8) Compounds where Z is -CF=CF- As shown below, compound (S3) is treated with n-butyllithium and then reacted with tetrafluoroethylene to obtain compound (S12). Next, compound (S2) is treated with n-butyllithium and then reacted with compound (S12), thereby synthesizing compound (1H) in which -CF=CF- is introduced between MSG ¹ and MSG ^2. By selecting the synthesis conditions, it is also possible to produce a cis-isomer compound.

(Scheme 9) Compounds Where Z is —CF ₂ O— or —OCF ₂ — As shown below, compound (1G), obtained by a method such as Scheme 7 above, is treated with a sulfurizing agent such as Lawesson's reagent to obtain compound (S16). Compound (1M), which has —CF ₂ O— (or —OCF ₂ —) between MSG ¹ and MSG ² , can be synthesized by fluorinating compound (S16) with a hydrogen fluoride-pyridine complex and N-bromosuccinimide (NBS). Compound (1M) can also be synthesized by fluorinating compound (S16) with (diethylamino)sulfur trifluoride (DAST). These bonding groups can also be generated by the method described in P. Kirsch et al., Angew. Chem. Int. Ed. 2001, 40, 1480.

2) Polymer (1)
The compound (1) of the present invention has a polymerizable group (terminal group R ¹ ) and can be easily polymerized. The polymer (1) in the present invention is at least one type of polymer obtained by polymerizing the compound (1).

3) Trans Isomer Compound and Ratio of Cis Isomer to Isomer Mixture The trans isomer compound of the present invention is a compound in which all cis-1,4-cyclohexylene structures of compound (1) are replaced with trans-1,4-cyclohexylene structures.
The composition of the present invention may contain, in addition to compound (1) and polymer (1), at least one selected from the trans isomer compound and its polymer. In this case, the ratio of the cis isomer to the isomer mixture is preferably 50 wt % or more.
When compound (1) or polymer (1) has multiple cyclohexane rings, two or more of the rings may be cis-isomers. When multiple rings have cis isomers, for example, when an isomeric mixture of cis-cis, cis-trans, and trans-trans isomers is present, the ratio of cis isomers to the isomeric mixture is calculated by dividing the total amount of isomers that are cis-isomers at any one position by the total amount of the isomeric mixture.

4) Composition (1)
The composition (1) of the present invention contains at least one compound (1) or polymer (1) and is composed of two or more components. That is, the composition (1) may be composed of two or more compounds (1) or polymers (1), or may be composed of a combination of at least one compound (1) or polymer (1) with at least one other component. Such other components are not particularly limited, but include, for example, polymerizable liquid crystal compounds other than compound (1) (hereinafter also referred to as "other polymerizable liquid crystal compounds"), other polymerizable compounds, polymerization initiators, curing agents, organic solvents, non-polymerizable liquid crystal compounds, inorganic fillers, and fibrous reinforcing materials.

5) Other Polymerizable Liquid Crystal Compounds The composition (1) may contain a polymerizable liquid crystal compound other than the compound (1). From the viewpoints of the development of a liquid crystal phase and compatibility with the compound (1), the compounds represented by formula (M1), (M2), or (M3) are preferred as the polymerizable liquid crystal compound.

In formulas (M1), (M2), and (M3),
A ^M is independently any divalent group selected from 1,4-phenylene, 1,4-cyclohexylene, 1,4-cyclohexenylene, pyridine-2,5-diyl, 1,3-dioxane-2,5-diyl, naphthalene-2,6-diyl, and fluorene-2,7-diyl, in which at least one hydrogen may be replaced by fluorine, chlorine, cyano, hydroxy, formyl, trifluoroacetyl, difluoromethyl, trifluoromethyl, alkyl having 1 to 5 carbon atoms, alkoxy having 1 to 5 carbon atoms, alkoxycarbonyl having 1 to 5 carbon atoms, or alkanoyl having 1 to 5 carbon atoms;
Z ^M is independently a single bond, -OCH ₂ -, -CH ₂ O-, -COO-, -OCO-, -COS-, -SCO-, -OCOO-, -CONH-, -NHCO-, -CF ₂ O-, -OCF ₂ -, -CH ₂ CH ₂ -, -CF ₂ CF ₂ -, -CH=CHCOO-, -OCOCH=CH-, _-CH 2 CH ₂ COO-, -OCOCH ₂ CH ₂ -, -COOCH ₂ CH ₂ -, -CH ₂ CH ₂ OCO-, -CH=CH-, -N=CH-, -CH=N-, -N=C(CH ₃ )-, -C(CH ₃ )=N-, -N=N-, -C≡C-, -CH=N-N=CH-, or -C(CH ₃ )=N-N=C(CH ₃ )-,
X ^M is hydrogen, fluorine, chlorine, trifluoromethyl, trifluoromethoxy, cyano, alkyl having 1 to 20 carbon atoms, alkenyl having 1 to 20 carbon atoms, alkoxy having 1 to 20 carbon atoms, or alkoxycarbonyl having 1 to 20 carbon atoms;
Y and ^M are independently a single bond, —O—, —COO—, —OCO—, or —OCOO—;
^QM is a single bond, —O—, —COO—, or —OCO—;
q is an integer from 1 to 6;
c and d are independently integers of 0 to 3 and satisfy the relationship 1≦c+d≦6, and a is an integer of 0 to 20;
R 1 ^M is hydrogen or methyl.

6) Other Polymerizable Compounds Composition (1) may contain other polymerizable compounds as constituent elements. Such polymerizable compounds are preferably compounds that do not reduce film-forming properties and mechanical strength. These polymerizable compounds are classified into compounds that do not have liquid crystallinity and compounds that have liquid crystallinity. Polymerizable compounds that do not have liquid crystallinity include vinyl derivatives, styrene derivatives, (meth)acrylic acid derivatives, sorbic acid derivatives, fumaric acid derivatives, and itaconic acid derivatives. Preferred examples of these derivatives are shown below.
In the present specification, "(meth)acryloyloxy" means acryloyloxy or methacryloyloxy, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acrylic acid" means acrylic acid or methacrylic acid.

Preferred vinyl derivatives include, for example, vinyl chloride, vinyl fluoride, vinyl acetate, vinyl pivalate, vinyl 2,2-dimethylbutanoate, vinyl 2,2-dimethylpentanoate, vinyl 2-methyl-2-butanoate, vinyl propionate, vinyl stearate, vinyl 2-ethyl-2-methylbutanoate, N-vinylacetamide, vinyl p-t-butylbenzoate, vinyl N,N-dimethylaminobenzoate, vinyl benzoate, ethyl vinyl ether, hydroxybutyl monovinyl ether, t-amyl vinyl ether, cyclohexanedimethanol methyl vinyl ether, α,β-vinylnaphthalene, methyl vinyl ketone, and isobutyl vinyl ketone.

Preferred styrene derivatives include, for example, styrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloromethylstyrene, and α-methylstyrene.

Preferred (meth)acrylic acid derivatives include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, phenyl (meth)acrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, trimethylol EO adduct triacrylate, pentaerythritol triacrylate, trisacryloyloxyethyl phosphate, bisphenol A EO adduct diacrylate, bisphenol A glycidyl diacrylate (trade name: "Biscoat 700" manufactured by Osaka Organic Chemical Industry Co., Ltd.), polyethylene glycol diacrylate dimethyl itaconate, and the like.

Preferred sorbic acid derivatives include, for example, sodium sorbate, potassium sorbate, lithium sorbate, 1-naphthylmethylammonium sorbate, benzylammonium sorbate, dodecylammonium sorbate, octadecylammonium sorbate, methyl sorbate, ethyl sorbate, propyl sorbate, isopropyl sorbate, butyl sorbate, t-butyl sorbate, hexyl sorbate, octyl sorbate, octadecyl sorbate, cyclopentyl sorbate, cyclohexyl sorbate, vinyl sorbate, allyl sorbate, and propargyl sorbate.

Preferred fumaric acid derivatives include, for example, dimethyl fumarate, diethyl fumarate, diisopropyl fumarate, dibutyl fumarate, dicyclopentyl fumarate, and dicyclohexyl fumarate.

Preferred itaconic acid derivatives include, for example, diethyl itaconate, dibutyl itaconate, and diisopropyl itaconate.
In addition to these, many polymerizable compounds such as butadiene, isoprene, and maleimide can also be used.

7) Polymerization Initiator The composition (1) may contain a polymerization initiator as a component. The polymerization initiator may be, for example, a photoradical polymerization initiator, a photocationic polymerization initiator, or a thermal radical polymerization initiator, depending on the curing method of the composition (1).

The photoradical polymerization initiator is not particularly limited, and known initiators can be used.
For example, 4-methoxyphenyl-2,4-bis(trichloromethyl)triazine, 2-(4-butoxystyryl)-5-trichloromethyl-1,3,4-oxadiazole, 9-phenylacridine, 9,10-benzphenazine, benzophenone/Michler's ketone mixture, hexaarylbiimidazole/mercaptobenzimidazole mixture, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, benzyl dimethyl ketal, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2,4-diethylxanthone/methyl p-dimethylaminobenzoate mixture, benzophenone/methyltriethanolamine mixture, and the like can be mentioned. Examples of commercially available products include "Darocur Series 1173, 4265" and "Irgacure Series 184, 369, 500, 651, 784, 819, 907, 1300, 1700, 1800, 1850, 2959" manufactured by Ciba Specialty Co., Ltd.

The photocationic polymerization initiator is not particularly limited, and known initiators can be used, such as "Sylacure UVI-6990, 6974" manufactured by UCC Corporation, "Adeka Optomer SP-150, 152, 170, 172" manufactured by Asahi Denka Corporation, "Photoinitiator 2074" manufactured by Rhodia, "Irgacure 250" manufactured by Ciba Specialty, and "DTS-102" manufactured by Midori Chemical Co., Ltd.

Preferred initiators for thermal radical polymerization include, for example, benzoyl peroxide, diisopropyl peroxydicarbonate, t-butylperoxy-2-ethylhexanoate, t-butylperoxypivalate, di-t-butyl peroxide (DTBPO), t-butylperoxydiisobutyrate, lauroyl peroxide, dimethyl 2,2'-azobisisobutyrate (MAIB), azobisisobutyronitrile (AIBN), azobiscyclohexanecarbonitrile (ACN), and dimethyl 2,2'-azobis(isobutyrate). Commercially available azo polymerization initiators include, for example, Fujifilm Wako Pure Chemical Industries, Ltd.'s "V-40, V-50, V-59, V-65, V-70, V-501, and V-601." In general, azo polymerization initiators can be used not only for thermal radical polymerization but also for photoradical polymerization.

Preferred initiators for anionic polymerization, coordination polymerization and living polymerization include, for example, alkali metal alkyl compounds such as nC ₄ H ₉ Li and tC ₄ H ₉ Li-R ₃ Al, aluminum compounds and transition metal compounds.

8) Curing Agent When the composition (1) contains a compound having a cyclic ether group as a constituent element, it may contain a curing agent as a constituent element. Preferred examples of the curing agent are shown below.

Amine-based curing agents include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, o-xylenediamine, m-xylenediamine, p-xylenediamine, trimethylhexamethylenediamine, 2-methylpentamethylenediamine, diethylaminopropylamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, bis(4-amino-3-methylcyclohexyl)methane, bis(4-aminocyclohexyl)methane, norbornene diamine, 1,2 -diaminocyclohexane, 3,9-dipropanamine-2,4,8,10-tetraoxaspiro[5,5]undecane, 4,4'-diaminodiphenylmethane, 4,4'-diamino-1,2-diphenylethane, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylsulfone, polyoxypropylenediamine, polyoxypropylenetriamine, polycyclohexylpolyamine, N-aminoethylpiperazine, etc.

Acid anhydride curing agents include tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, methylcyclohexenetetracarboxylic dianhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, ethylene glycol bisanhydrotrimethylate, glycerin bis(anhydrotrimellitate) monoacetate, dedecenyl succinic anhydride, and chlorendic anhydride.

Examples of phenol-based curing agents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, m-ethylphenol, p-ethylphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, o-isopropylphenol, p-tert-butylphenol, o-sec-butylphenol, p-octylphenol, 2,6-di-tert-butylphenol, resorcinol, 1-naphthol, 2-naphthol, bisphenol A, phenol novolac, xylylene novolac, and bisphenol A novolac.
In addition to the above, curing agents described in JP-A Nos. 2004-256687 and 2002-226550 can also be used.

The active ester curing agent is not particularly limited, and known agents can be used. Examples include "HPC-8000H-65T" manufactured by DIC Corporation as an active ester compound containing a dicyclopentadiene-type diphenol structure, "EXB-8150-65T" manufactured by DIC Corporation as an active ester compound containing a naphthalene structure, "DC808" manufactured by Mitsubishi Chemical Corporation as an active ester compound containing an acetylated phenol novolac, "YLH1026" manufactured by Mitsubishi Chemical Corporation as an active ester compound containing a benzoylated phenol novolac, "DC808" manufactured by Mitsubishi Chemical Corporation as an active ester curing agent which is an acetylated phenol novolac, and "YLH1026" manufactured by Mitsubishi Chemical Corporation as an active ester curing agent which is a benzoylated phenol novolac.

Cure accelerators include cycloamidine compounds such as 1,8-diazabicyclo[5.4.0]-7-undecene (DBU), 1,5-diazabicyclo[4.3.0]-5-nonene, and 5,6-dibutylamino-1,8-diazabicyclo[5.4.0]-7-undecene; and the cycloamidine compounds may be combined with maleic anhydride, 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, and 2,3-dimethoxy-5-methylbenzoquinone. compounds having intramolecular polarization obtained by adding a compound having a π bond, such as quinone compounds such as 1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, and phenyl-1,4-benzoquinone, diazophenylmethane, and phenol resins; tertiary amine compounds such as benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; derivatives of the tertiary amine compounds; 2-methylimidazole, 2-phenylimidazole, 2-phenylimidazole, and 2-phenyl-1,4-benzoquinone; imidazole compounds such as methyl-4-methylimidazole; derivatives of these imidazole compounds; organic phosphine compounds such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, tris(4-methylphenyl)phosphine, diphenylphosphine, and phenylphosphine; phosphorus compounds with intramolecular polarization obtained by adding compounds with π bonds such as maleic anhydride, the above-mentioned quinone compounds, diazophenylmethane, and phenolic resins to these organic phosphine compounds; tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate, triphenylphosphine tetraphenylborate, 2-ethyl-4-methylimidazole tetraphenylborate, and N-methylmorpholine tetraphenylborate; derivatives of these tetraphenylboron salts; and adducts of these tetraphenylboron salts with phosphine compounds such as triphenylphosphonium-triphenylborane and N-methylmorpholine tetraphenylphosphonium-tetraphenylborate.

9) Organic Solvent The composition (1) may contain an organic solvent. The composition (1) may be cured in an organic solvent or without a solvent. For example, the composition (1) containing an organic solvent may be applied to a substrate by spin coating or the like, and then the organic solvent may be removed before photocuring. After photocuring, the composition may be heated to an appropriate temperature for post-treatment by thermal curing.

Preferred organic solvents include, for example, benzene, toluene, xylene, mesitylene, hexane, heptane, octane, nonane, decane, tetrahydrofuran, γ-butyrolactone, N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, cyclohexane, methylcyclohexane, cyclopentanone, cyclohexanone, PGMEA, etc. The above organic solvents may be used alone or in combination of two or more.
It is not particularly meaningful to limit the proportion of the organic solvent used during curing, and the proportion may be determined for each individual case, taking into consideration the curing efficiency, solvent cost, energy cost, etc.

The composition (1) of the present invention preferably contains 10 wt% or less of an organic solvent based on the total weight, and is particularly preferably a solvent-free composition. A solvent-free composition is a composition that maintains fluidity at room temperature without the use of an organic solvent, or can be prepared into a varnish-like composition that exhibits high fluidity when melted. Using a composition containing 10 wt% or less of an organic solvent based on the total weight, or a solvent-free composition, makes it possible to address environmental issues such as VOC problems, and the high concentration of the cured product allows the function of the cured product to be effectively expressed.
The composition (1) before curing is in a liquid state at around room temperature and retains fluidity, and can be used as a varnish without solvent or containing 10 wt % or less of an organic solvent based on the total weight. In other words, it can be used as is for applications such as coating or adhesion, and does not require a step of volatilizing the solvent at high temperature.
Examples of organic solvents that can be used here include acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N,N-dimethylformamide, methanol, ethanol, etc., which are relatively low in toxicity from the viewpoint of environmental load. Composition (1) of the present invention is capable of forming a resin having high heat resistance and a high low dielectric constant in a non-organic solvent system, and therefore can provide insulating materials for various electronic parts, such as laminates for printed wiring boards, interlayer insulating materials for substrates, adhesive films, semiconductor encapsulants, and conductive adhesives.

10) Non-Polymerizable Liquid Crystalline Compounds Composition (1) may contain a liquid crystal compound without a polymerizable group as a component. Examples of such non-polymerizable liquid crystal compounds are described in LiqCryst (LCI Publisher GmbH, Hamburg, Germany), a database of liquid crystal compounds. By curing composition (1) containing a non-polymerizable liquid crystal compound, composite materials containing a polymer of compound (1) and a liquid crystal compound can be obtained. In such composite materials, the non-polymerizable liquid crystal compound exists in a polymer network, such as a polymer-dispersed liquid crystal.

11) Inorganic Fillers and Fibrous Reinforcing Materials Inorganic fillers can be added to improve thermal conductivity, mechanical strength, adjust viscosity, and the like.
For example, to reduce dielectric loss, silicon compounds such as spherical silica, pulverized silica, hollow silica, and fumed silica, metal oxides such as magnesium oxide, zinc oxide, and titanium oxide, and metal salts such as potassium titanate may be used. Spherical silica, hollow silica, magnesium oxide, and potassium titanate are preferred, and hollow silica is more preferred.
A fibrous reinforcing material can be used as a fibrous or whisker-like filler to increase the strength of a substrate or a resin part. Preferred examples include glass cloth, low-dielectric glass cloth, inorganic fibers such as carbon fibers and carbon nanotubes, and inorganic whiskers such as silicate whiskers, alumina whiskers, magnesium oxide whiskers, zinc oxide whiskers, and aluminum nitride whiskers, with low-dielectric glass cloth, aluminum oxide whiskers, and aluminum nitride whiskers being more preferred.
To increase mechanical strength, it is better to use more filler, but if there is too much, the resin will not be able to fill the gaps in the filler. Also, if there is too much resin, the effect of increasing mechanical strength will not be realized. Furthermore, increasing the filler tends to increase the dielectric constant and decrease the dielectric tangent, so it is preferable to determine the composition while balancing these two factors. In addition to inorganic fibers, organic fibers can also be used. Examples of organic fibers with high mechanical strength include polyamide fibers, aramid fibers, polyparaphenylene benzobisoxazole fibers, and liquid crystalline polyester fibers. Compared to inorganic fibers, organic fibers are lighter and are therefore preferred for substrates of portable devices.
Fillers with high thermal conductivity include powdered metal nitrides such as aluminum nitride, boron nitride, and silicon nitride; carbides such as diamond, graphite, and silicon carbide; metal oxides such as magnesium oxide, aluminum oxide, zinc oxide, silicon oxide, titanium oxide, tin oxide, holmium oxide, and calcium oxide; metal hydroxides such as magnesium hydroxide and aluminum hydroxide; silicate compounds such as cordierite and mullite; and metal fillers such as gold, silver, copper, platinum, iron, tin, lead, nickel, aluminum, magnesium, tungsten, molybdenum, and stainless steel. Boron nitride and silicon oxide, which have low dielectric constants, are preferred, and hexagonal boron nitride (h-BN) is particularly preferred due to its low dielectric constant and high thermal conductivity. The more inorganic filler is used, the higher the thermal conductivity, but inorganic fillers generally have a higher relative dielectric constant and a smaller dielectric dissipation factor than resin components, so increasing the filler amount increases the dielectric constant. Therefore, it is preferable to fill the required amount within a range that does not exceed the desired dielectric constant.
The composition (1) of the present invention has high transparency and not only low dielectric constant but also low refractive index. When used as an optical material, the refractive index can be adjusted by adding powders of hollow silica, spherical silica, titanium oxide, zirconium oxide, etc.

The shape of the filler can be spherical, amorphous, fibrous, whisker-like, cylindrical, or plate-like. The type, shape, size, and amount of filler added can be selected appropriately depending on the purpose. If the resulting polymer molded product requires insulation, conductive fillers can also be used as long as the desired insulation properties, mechanical strength, dielectric constant, and dielectric loss are maintained.

The average particle size of the spherical or irregularly shaped filler is preferably 0.1 to 200 μm. More preferably, it is 1 to 100 μm. If it is 0.1 μm or more, the thermal conductivity is good, and if it is 200 μm or less, the filling rate can be increased. With regard to fibrous fillers, the longer the fiber length, the better the tensile strength, but it becomes difficult to knead or disperse, so it is preferable to select it according to the application. When dispersed, the average particle size of the fibrous filler is preferably 0.01 to 200 μm. More preferably, it is 0.1 to 100 μm. If it is 0.1 μm or more, the thermal conductivity is good, and if it is 200 μm or less, the mechanical strength can be increased.
The amount of filler is preferably 20 to 95 wt % in the polymer molded body after curing. More preferably, it is 50 to 95 wt %. A filler content of 20 wt % or more is preferable because it increases the thermal conductivity. A filler content of 95 wt % or less is preferable because it does not make the polymer molded body brittle.

As fillers, commercially available products that have been surface-treated, such as those for affinity, adhesion, dispersion, or waterproofing, may be used as is, or the surface treatment agents may be removed from such commercially available products. Untreated fillers may also be used after being treated with a silane coupling agent, affinity agent, surface tension adjuster, anti-settling agent, anti-agglomeration agent, etc.

12) Other Additives Because compound (1) and composition (1) have high polymerizability, a stabilizer may be added to facilitate handling. Known stabilizers can be used without limitation as such stabilizers, and examples thereof include hydroquinone, 4-ethoxyphenol, and 3,5-di-t-butyl-4-hydroxytoluene (BHT).
In applications where a low dielectric loss tangent (low tan δ) and a high glass transition temperature are required, it is preferable to add a crosslinking agent. The crosslinking agent is preferably one that chemically bonds with the polymerizable group of the liquid crystal compound having a polymerizable group at its end to form a three-dimensional crosslink.

Other resins or oligomers may be added to composition (1) of the present invention to adjust the properties of the cured product. Examples include polyphenylene ether resin (PPE resin), modified polyphenylene ether oligomer (mPPE), polystyrene resin, polycarbonate resin, polyimide resin, polyamide resin, polyester resin, polybutadiene copolymer, polyvinyl acetal resin, natural rubber, synthetic rubber, synthetic elastomer, epoxy resins with a skeleton different from that of the compound of the present invention, oxetane resin, acrylic resin, methacrylic resin, maleimide resin, oxazine resin, and oxazoline resin. When dielectric properties are particularly important, polyphenylene ether resin (PPE resin), modified polyphenylene ether oligomer (mPPE), polystyrene resin, and polycarbonate resin are preferred.

13) Low Dielectric Constant Resin The low dielectric constant resin, which is another embodiment of the present invention, is a cured product of the composition (1) and therefore has a low dielectric constant, and is also excellent in thermal conductivity, heat resistance, rigidity, elasticity, molding flowability, chemical resistance, dimensional stability, and the like.

When a low-dielectric resin exhibits liquid crystallinity, the molecular orientation can be controlled by an orientation process before curing. The relative dielectric constant and thermal conductivity exhibit anisotropy depending on the molecular orientation direction. For example, when designing the dielectric constant and thermal design of an electronic substrate, more advanced material design becomes possible, such as designing the area directly below the IC that generates heat to have high thermal conductivity in the thickness direction, and orienting the area other than directly below the IC in the horizontal direction to spread the heat over a wide area. The orientation method can be controlled using the following methods.
Methods for controlling the alignment of the mesogenic portion of liquid crystal molecules in a composition for forming a low-dielectric-constant resin include treating the filler surface with a silane coupling agent or alignment agent that has alignment ability, and aligning the liquid crystal molecules using the self-alignment force of the composition itself. These methods may be used alone or in combination. Examples of alignment states controlled by such alignment control methods include homogeneous, twisted, homeotropic, hybrid, bend, and spray alignment, and can be appropriately selected depending on the application and alignment control method. Furthermore, during film formation or molding, physical alignment can also be achieved by applying shear stress to the liquid crystal state before curing.

The orientation temperature is between room temperature and 250°C, preferably between room temperature and 200°C, and more preferably between room temperature and 180°C. The heat treatment time is between 5 seconds and 2 hours, preferably between 10 seconds and 60 minutes, and more preferably between 20 seconds and 30 minutes. If the heat treatment time is shorter than the above range, the temperature of the layer made of composition (1) may not be raised to the specified temperature. If the heat treatment time is longer than the above range, productivity may decrease. Note that the above heat treatment conditions vary depending on the types and compositional ratios of the components used in composition (1), the presence and content of a polymerization initiator, and so are merely approximate ranges. In particular, if the temperature exceeds the polymerization initiation temperature of the polymerizable component used in composition (1), the resin will harden before orientation occurs, making it impossible to obtain a low-dielectric-constant resin with molecular chains oriented in a uniform direction.

Methods for curing composition (1) include, for example, radical polymerization of the polymerizable group (polymerizable component), anionic polymerization, cationic polymerization, and coordination polymerization. However, to fix the molecular alignment or helical structure, thermal polymerization or photopolymerization using light or heat, such as electron beams, ultraviolet rays, visible light, or infrared rays (heat rays), is suitable. Thermal polymerization is preferably carried out in the presence of a radical polymerization initiator, and photopolymerization is preferably carried out in the presence of a photoradical polymerization initiator. For example, a polymer in which the alignment of liquid crystal molecules is fixed can be obtained by polymerization using ultraviolet light or an electron beam in the presence of a photoradical polymerization initiator. The resulting polymer may be a homopolymer, random copolymer, alternating copolymer, block copolymer, or graft copolymer, and the type can be selected appropriately depending on the application.

When the orientation of composition (1) is fixed by photopolymerization, ultraviolet or visible light is typically used. The wavelength of the light used for irradiation is in the range of 150 to 500 nm, preferably 250 to 450 nm, and more preferably 300 to 400 nm. Examples of light sources for irradiation include low-pressure mercury lamps (germicidal lamps, fluorescent chemical lamps, black lights), high-pressure discharge lamps (high-pressure mercury lamps, metal halide lamps), short-arc discharge lamps (ultra-high-pressure mercury lamps, xenon lamps, mercury-xenon lamps), and ultraviolet light-emitting diodes. Of these, metal halide lamps, xenon lamps, ultraviolet light-emitting diodes, and high-pressure mercury lamps are preferred.

The wavelength range of the irradiation light source may be selected by placing a filter or the like between the light source and composition (1) to allow only a specific wavelength range to pass. The amount of light irradiated from the light source is in the range of 2 to 5000 mJ/cm ² , preferably 10 to 3000 mJ/cm ² , and more preferably 100 to 2000 mJ/cm ^2. The temperature conditions during light irradiation are preferably set to the same as the heat treatment temperature described above.

Conditions for fixing the orientation of composition (1) by thermal polymerization include a heat curing temperature in the range of room temperature to 350°C, preferably room temperature to 250°C, and more preferably 50°C to 200°C, and a curing time in the range of 5 seconds to 10 hours, preferably 1 minute to 5 hours, and more preferably 5 minutes to 1 hour. After curing, it is preferable to slowly cool the composition to suppress stress distortion. It is also possible to perform a reheating treatment to relieve distortion.

The orientation-controlled cured product or the composition in the curing process may be further oriented in any direction by a mechanical operation such as stretching.
The isolated polymer (1) may be dissolved in an organic solvent and mixed with other components to prepare a composition, which may then be aligned and cured on an alignment-treated substrate and processed into a film or the like. In this case, two polymers may be mixed and processed, or multiple polymers may be laminated. Examples of suitable organic solvents include N-methyl-2-pyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, N,N-dimethylacetamide dimethyl acetal, tetrahydrofuran, chloroform, 1,4-dioxane, bis(methoxyethyl)ether, γ-butyrolactone, tetramethylurea, trifluoroacetic acid, ethyl trifluoroacetate, hexafluoro-2-propanol, 2-methoxyethyl acetate, methyl ethyl ketone, cyclopentanone, and cyclohexanone. These may be mixed with a small amount of a common organic solvent such as acetone, benzene, toluene, heptane, or methylene chloride.

When a composition for forming a highly linear, low-dielectric resin exhibits a liquid crystal phase over a very narrow range, if the crystallinity is high, it forms domains with axes aligned in a certain direction, resulting in higher thermal conductivity than polymerizable compounds such as bisphenol A structures. Orientation and crystallinity can also be controlled by slowly curing the material from an isotropic liquid state with the surface of a polymer sheet with aligned orientation or crystalline resin filler present as a core for crystal growth. However, if the crystallinity is made too high, flexibility tends to decrease, so it is necessary to use a composition with appropriate crystallinity.

14) Low-Dielectric-Constant Resin Insulating Film, Low-Dielectric-Constant Resin Film, and Low-Dielectric-Constant Resin Sheet The polymer molded article of the present invention is a cured product for forming a low-dielectric-constant resin comprising the composition (1) described above, and can be used as a thin-film low-dielectric-constant resin insulating film, as well as a film-, sheet-, plate-, fiber-, or three-dimensionally shaped part (insulating part of a connector), or can be used as a coating agent, adhesive, or filler as it is.
When used in the form of a thin film, film, sheet, plate, fiber, or three-dimensional molded article, the preferred shapes are films and thin films. Films and thin films can be obtained by curing composition (1) in a state where it is applied to a substrate or a release film, or sandwiched between flat plates such as substrates and molds. Composition (1) containing an organic solvent can also be applied to an orientation-treated substrate and then the organic solvent removed. Furthermore, films can also be obtained by press-molding the cured product. In this specification, the thickness of a sheet is 1 mm or more, the thickness of a film is 5 μm or more, preferably 10 to 500 μm, and more preferably 20 to 300 μm, and the thickness of a thin film is less than 5 μm.

Hereinafter, a method for producing a film as a polymer molded article using the composition (1) containing an organic solvent will be specifically described.
First, composition (1) is applied to a release-treated substrate, and the organic solvent is removed by drying to form a coating layer with a uniform thickness. Examples of the coating method include spin coating, roll coating, caten coating, flow coating, printing, microgravure coating, gravure coating, wire bar coding, dip coating, spray coating, and meniscus coating.

The organic solvent can be removed by drying, for example, air drying at room temperature, drying on a hot plate, drying in a drying oven, or by blowing warm or hot air. The conditions for removing the organic solvent are not particularly limited; drying should be performed until the organic solvent is largely removed and the coating layer loses its fluidity. Depending on the type and composition of the compounds used in composition (1), the liquid crystal molecules in the coating layer may be completely aligned during the drying process. In such cases, the coating layer that has undergone the drying process can be subjected to the polymerization process without undergoing the heat treatment process described above. However, to achieve a more uniform alignment of the liquid crystal molecules in the coating layer, it is preferable to heat the coating layer that has undergone the drying process to a liquid crystal phase expression temperature to align them in the liquid crystal state, and then fix the alignment by photopolymerization or thermal polymerization.

When composition (1) is used as a low-dielectric-constant resin insulating film, it is also preferable to subject the substrate surface to an alignment treatment before application. Alignment treatment methods include, for example, simply forming an alignment film on the substrate, forming an alignment film on the substrate and then rubbing it with a rayon cloth, directly rubbing the substrate with a rayon cloth, oblique vapor deposition of silicon oxide, and rubbing-free alignment using a stretched film, a photoalignment film, or an ion beam. In some cases, the desired alignment state can be achieved without treating the substrate surface. For example, when forming homeotropic alignment, surface treatments such as rubbing are often not performed, but rubbing may be performed to achieve higher alignment.

The alignment film is not particularly limited as long as it can control the alignment of composition (1), and any known alignment film can be used. For example, polyimide, polyamide, polyvinyl alcohol, alkylsilane, alkylamine, or lecithin-based alignment films are suitable. Silane coupling agents are also suitable for vertical alignment.

Any method can be used for the rubbing treatment. Typically, a rubbing cloth made of a material such as rayon, cotton, or polyamide is wrapped around a metal roll, and the roll is rotated and moved while in contact with the substrate or alignment film, or the substrate is moved while the roll is fixed.

In addition, an orientation control additive may be included in composition (1) to obtain more uniform orientation. Examples of such alignment control additives include imidazoline, quaternary ammonium salts, alkylamine oxides, polyamine derivatives, polyoxyethylene-polyoxypropylene condensates, polyethylene glycol and its esters, sodium lauryl sulfate, ammonium lauryl sulfate, lauryl amine sulfates, alkyl-substituted aromatic sulfonates, alkyl phosphates, aliphatic or aromatic sulfonic acid formalin condensates, laurylamidopropyl betaine, laurylaminoacetic acid betaine, polyethylene glycol fatty acid esters, polyoxyethylene alkylamines, perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkylethylene oxide adducts, perfluoroalkyltrimethylammonium salts, oligomers having a perfluoroalkyl group and a hydrophilic group, oligomers having a perfluoroalkyl group and a lipophilic group, urethanes having a perfluoroalkyl group, and organosilicon compounds having a primary amino group (for example, alkoxysilane-type, linear siloxane-type, and three-dimensionally condensed silsesquioxane-type organosilicon compounds).

Examples of the substrate include plastic film substrates and glass-reinforced resin substrates such as polyimide, polyamideimide, polyamide, polyetherimide, polyetheretherketone, polyetherketone, polyketone sulfide, polyethersulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal, polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulose, triacetyl cellulose or its partially saponified products, epoxy resin, phenolic resin, and norbornene resin; glass substrates such as alkali glass, borosilicate glass, and flint glass; metal substrates such as aluminum, iron, and copper; and inorganic substrates such as silicon.

The film substrate may be a uniaxially stretched film or a biaxially stretched film. The film substrate may be subjected to a surface treatment such as saponification, corona treatment, or plasma treatment in advance. A protective layer may be formed on these film substrates to prevent the film from being corroded by the organic solvent contained in composition (1). Examples of materials used for the protective layer include polyvinyl alcohol. Furthermore, an anchor coat layer may be formed to enhance adhesion between the protective layer and the substrate. Such an anchor coat layer may be made of either an inorganic or organic material, as long as it enhances adhesion between the protective layer and the substrate.

15) Low-dielectric-constant resin parts and electronic devices The composition for forming a low-dielectric-constant resin of the present invention can be used as low-dielectric-constant resin parts such as low-dielectric-constant resin insulating films, low-dielectric-constant resin films, low-dielectric-constant resin sheets, etc. Furthermore, it is useful for applications in various electronic devices such as low-dielectric-constant resin substrates, low-dielectric-constant resin coatings, low-dielectric-constant resin adhesives, and low-dielectric-constant resin molded products.

[Manufacturing method]
Hereinafter, a method for producing a composition for forming a low dielectric constant resin and a method for producing a low dielectric constant resin part from the composition will be specifically described.

The composition for forming a low dielectric constant resin of the present invention can be used as is as a liquid resin raw material in a temperature range where a liquid crystal phase or an isotropic phase is expressed, or it can be dissolved in an organic solvent and used. To prepare a solution, the polymerizable liquid crystal composition, the necessary organic solvent, filler, and additives are added, and the mixture is stirred and degassed using a stirrer until the composition is uniform. For example, using a planetary mixer, the mixture is stirred at 2000 rpm for 10 minutes, and then degassed at 2200 rpm for 10 minutes. In addition to planetary mixers, the mixture can also be dispersed using a stirring motor, a crusher, a three-roll mill, a ball mill, a planetary mill, a bead mill, a jet mill, or the like.

Wet coating is preferably used as the application method to coat the composition uniformly. Among wet coating methods, spin coating is preferred when producing small quantities, as it is simple and allows for the formation of uniform films. When productivity is a priority, gravure coating, die coating, bar coating, reverse coating, roll coating, slit coating, dipping, spray coating, kiss coating, reverse kiss coating, air knife coating, curtain coating, inkjet printing, flexographic printing, screen printing, rod coating, and other methods are preferred. The wet coating method can be selected appropriately from these methods depending on the required film thickness, viscosity, curing conditions, and other factors.

When producing sheets, the composition can be coated onto a release-treated substrate using the above-mentioned method or other methods and then peeled off using a casting method. When producing structures, a mold can be used and resin molding methods such as press molding, injection molding, and various 3D printer molding methods (ejection lamination methods) can be used. After molding, the resin can be fully cured either by removing it from the mold or while it is still in the mold.

The present invention will be explained in more detail using examples (including preparation examples of compounds, compositions, polymers, low-dielectric-constant resins, etc.). The present invention is not limited by these examples.

[Synthesis Example of Compound (1)]
Compound (1) was synthesized according to the procedures shown in Examples such as Synthesis Example 1. Unless otherwise specified, the reaction was carried out under a nitrogen atmosphere. The synthesized compound was identified by methods such as NMR analysis. The device characteristics of compound (1), the composition, the polymer, the low dielectric constant resin, etc. were measured by the following methods.

<NMR analysis>
The measurements were performed using a JNM-ECZR manufactured by JEOL. For 1H-NMR measurements, the sample was dissolved in a deuterated solvent such as CDCl3, and measurements were performed at room temperature, 500 MHz, and 16 accumulations. Tetramethylsilane was used as the internal standard. For 19F-NMR measurements, CFCl3 was used as the internal standard, and measurements were performed with 32 accumulations. In describing nuclear magnetic resonance spectra, s means singlet, d means doublet, t means triplet, q means quartet, quin means quintet, sex means sextet, m means multiplet, and br means broad.

<Gas chromatographic analysis>
A Shimadzu GC-2014 gas chromatograph was used for the measurements. The column used was a capillary column DB-1 (30 m or 15 m long, 0.25 mm inner diameter, 0.25 μm film thickness) manufactured by Agilent Technologies Inc. Nitrogen (1 ml/min) was used as the carrier gas. The temperature of the sample vaporizer was set to 300°C, and the temperature of the detector (FID) was set to 300°C. The sample was dissolved in an appropriate solvent such as acetone to prepare a 1 wt% solution, and 1 μl of the resulting solution was injected into the sample vaporizer. A Shimadzu GCSolution system or similar was used as the recorder.

<HPLC analysis>
A Shimadzu Prominence (LC-20AD; SPD-20A) was used for the measurements. A YMC-Pack ODS-A (length 150 mm, inner diameter 4.6 mm, particle size 5 μm) column was used. An appropriate mixture of methanol/water or acetonitrile/water was used as the eluent. A UV detector, RI detector, or CORONA detector was used as the detector. When a UV detector was used, the detection wavelength was 210-254 nm. The sample was dissolved in methanol or acetonitrile to prepare a 0.1 wt% solution, and 1 μL of this solution was introduced into the sample chamber. A Shimadzu C-R7Aplus recorder was used.

<UV-visible spectroscopic analysis>
Measurements were performed using a PharmaSpec UV-1700 manufactured by Shimadzu Corporation. The detection wavelength was 190 nm to 700 nm. The sample was dissolved in acetonitrile to prepare a 0.01 mmol/L solution, which was then placed in a quartz cell (light path length 1 cm) and measured.

<Measurement sample>
When measuring the transition temperature (clearing point, melting point, polymerization initiation temperature, etc.), and when the compound exhibits a liquid crystal phase, the phase structure, the compound itself was used as a sample.

(1) Transition temperature (°C)
Measurements were performed using a high-sensitivity differential scanning calorimeter, X-DSC7000, manufactured by SSI Nanotechnology. The sample was heated and cooled at a rate of 3-5°C/min, and the onset of the endothermic or exothermic peak associated with the phase change of the sample was extrapolated to determine the transition temperature. The melting point and polymerization initiation temperature of the compound were also measured using this device. When a compound exhibits a liquid crystal phase, the temperature at which it transitions from a solid to a liquid crystal phase such as a smectic phase or nematic phase is sometimes abbreviated as the "lower limit temperature of the liquid crystal phase." The temperature at which a compound transitions from a crystal to a liquid is sometimes abbreviated as the "clearing point."

Crystals were represented as C. When the type of crystal could be distinguished, they were represented as C1, C2, etc. When a liquid crystal phase was present, the smectic phase was represented as S and the nematic phase as N. When the smectic phase could be distinguished as smectic A, smectic B, smectic C, or smectic F, they were represented as SA, SB, SC, or SF, respectively. Liquids (isotropic) were represented as I. Transition temperatures were represented, for example, as "C 50.0 N 100.0 I." This indicates that the transition temperature from crystal to nematic phase is 50.0°C, and the transition temperature from nematic phase to liquid is 100.0°C.

(2) Phase Structure When a compound exhibits a liquid crystal phase, a sample was placed on a hot plate (Mettler FP-52 hot stage) of a melting point measuring device equipped with a polarizing microscope. The sample was heated at a rate of 3°C/min, and the phase state and its change were observed under the polarizing microscope to identify the type of phase.

[Synthesis Example 1]
Synthesis of isomer mixture (S01: a mixture of compound (1-1-2a) and its trans isomer; a compound in which both R and ^b are methyl, m=0, and M and ^Z2 are single bonds)

The 4,4'-bicyclohexanediol isomer mixture is commercially available, for example, from Fujifilm Wako Pure Chemical Industries, Ltd. Methanol (600 mL) was added to this compound (200 g, 1.01 mol), and the mixture was heated and stirred at 60°C for 1 hour. The mixture was then cooled to room temperature and allowed to stand at that temperature for 30 minutes. The precipitated crystals were filtered, and the resulting filtrate was concentrated under reduced pressure at 40°C to obtain 100 g (0.505 mol) of 4,4'-bicyclohexanediol (S01-a), an isomer mixture in which the cis isomer ratio to the isomer mixture was 50 wt% or more (cis-cis: 7.0%, cis-trans: 83.9%, trans-trans: 9.1%). This isomer mixture remained in a liquid state at 25°C.

Under a nitrogen atmosphere, a solution of the above 4,4'-bicyclohexanediol isomer mixture (S01-a) (10.0 g, 0.505 mol) and triethylamine (153.0 g, 1.52 mol) in THF (500 mL) was cooled to 10°C, and methacrylic acid chloride (121.3 g, 1.12 mol) was slowly added dropwise. The mixture was stirred at room temperature for 5 hours. The reaction mixture was filtered, the filtrate poured into water, and extracted twice with toluene (1 L). The organic layer was removed and washed once with water, twice with saturated sodium bicarbonate water, and three times with water. The organic layer was then concentrated under reduced pressure at 40°C. The resulting residue was subjected to silica gel column chromatography (solvent: toluene) to isolate the product, which was then concentrated under reduced pressure at 40°C and further dried under reduced pressure to obtain the isomer mixture (S01) (83.0 g, 0.248 mmol). When the isomer ratio of this isomer mixture (S01) was analyzed by HPLC, it was found to be cis-cis: 7.0%, cis-trans: 83.9%, and trans-trans: 9.1%, resulting in a cis isomer ratio of 90.9 wt% relative to the isomer mixture (analysis conditions: detection wavelength: 210 nm, solvent: methanol/water = 90/10 wt%, eluent flow rate: 1.0 mL/s). This isomer mixture (S01) was in a liquid state at room temperature (25°C) and maintained fluidity. The polymerization initiation temperature was 123.0°C.

Meanwhile, when (S01-a), the raw material for isomer mixture (S01), was purified by recrystallization, the remaining trans-trans isomer was used to introduce a methacryl group in the same manner as for isomer mixture (S01). This was designated as trans-trans polymerizable liquid crystal compound (S01-tt).

[Synthesis Example 2]
Synthesis of polymerizable liquid crystal compound (S02) In order to investigate the difference in dielectric properties between cyclohexane rings and benzene rings, and the effect of adding a highly linear compound, we synthesized a polymerizable liquid crystal compound with a linear structure using benzene rings and mixed it with the isomer mixture (S01).

4,4'-Biphenyldiol (S02-a) is commercially available, for example, from Fujifilm Wako Pure Chemical Industries, Ltd.

Under a nitrogen atmosphere, a solution of 4,4'-biphenyldiol (S02-a) (10.0 g, 53.70 mmol), N,N'-dicyclohexylcarbodiimide (DCC) (24.4 g, 118.2 mmol), and 4-dimethylaminopyridine (DMAP) (3.94 g, 32.22 mmol) in dichloromethane (100 mL) was cooled to -10°C and stirred. Methacrylic acid (9.71 g, 112.8 mmol) was added dropwise to the resulting solution, and the temperature was gradually raised to room temperature and stirred for 6 hours. Dichloromethane (100 mL) was added to the reaction solution, which was then filtered and washed three times with water. The organic layer was then concentrated under reduced pressure at 40°C. The resulting residue was subjected to silica gel column chromatography (solvent: toluene/ethyl acetate = 5/1 (volume ratio)) to isolate the product, which was then concentrated under reduced pressure at 40°C. The mixture was then purified by recrystallization filtration (heptane/ethyl acetate = 3/3 v) and further dried under reduced pressure to obtain polymerizable liquid crystal compound (S02) (11.8 g, 36.52 mmol). The transition temperature of this polymerizable liquid crystal compound (S02) was C 150.9 I (°C). The polymerization initiation temperature was 171.9°C.

The ¹ H-NMR signals of the compound were as follows:
δ (ppm; CDCl ₃ ): 7.58-7.56 (d, 4H), 7.19-7.18 (d, 4H), 6.37 (qd, 2H), 6.21 (qd, 2H), 2.07 (dd, 6H)

[Synthesis Example 3]
Synthesis of polymerizable liquid crystal compound (S03) Furthermore, we added an alkyl chain to polymerizable liquid crystal compound (S02) to lengthen the chain, and mixed it with an isomer mixture (S01) to investigate the effect on the dielectric properties and liquid stability.

(1st stage)
Under a nitrogen atmosphere, a solution of 4,4'-biphenyldiol (S02-a) (10.0 g, 53.70 mmol), sodium hydroxide (4.51 g, 112.8 mmol), and 6-bromo-1-hexanol (20.4 g, 112.8 mmol) in N,N-dimethylformamide (100 mL) was heated and stirred at 60°C for 6 hours. The reaction solution was filtered as is, and the crystals were washed three times with ethanol and then dried under reduced pressure to obtain compound (S03-b) (14.0 g, 36.22 mmol).

(Second stage)
A polymerizable liquid crystal compound (S03) (2.90 g, 5.55 mmol) was obtained in the same manner as described in Synthesis Example 1 of Example 1, except that the compound (S03-b) obtained in the previous step was used instead of 4,4'-biphenyldiol (S02-a). The transition point of this polymerizable liquid crystal compound (S03) was C 61.9 I (°C). The polymerization initiation temperature was 163.3°C.

The 1H-NMR signals of the compound were as follows:
δ (ppm; CDCl3): 7.45-7.43 (d, 4H), 6.94-6.91 (d, 4H), 6.09 (qd, 2H), 5.54-5.53 (qd, 2H), 4.17-4.14 (t, 4H), 3.99-3.97 (t, 4H), 1.93 (dd, 6H), 1.84-1.78 (tt, 4H), 1.74-1.68 (tt, 4H), 1.55-1.42 (m, 8H)

[Synthesis Example 4]
Synthesis of isomer mixture (S05: a mixture of compound (1-1-2) and its trans isomer compound; a compound in which R ^1a and R ^1b are formula (PG-6), R ^b is hydrogen, q=0, and Z ¹ , Z ² , and Z ⁴ are all single bonds)

The same 4,4'-dicyclohexanol (S01-a) was used as in Synthesis Example 1.

Under a nitrogen atmosphere, 4,4'-dicyclohexanol (S01-a) (10.0 g, 50.6 mmol) was added to a solution of sodium hydride (55%) (4.85 g, 111.1 mmol) in N,N-dimethylformamide (120 mL) at 10°C. After stirring this solution at 40°C for 30 minutes, epibromohydrin (20.8 g, 151.6 mmol) was added and the mixture was heated and stirred at 40°C for 3 days. The reaction mixture was slowly poured into water and extracted with toluene (500 mL). The organic layer was washed three times with water and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (solvent: toluene/ethyl acetate = 4/1 (volume ratio)) to obtain the isomer mixture (S05) (7.80 g, 25.2 mmol). Analysis of the isomer ratio by HPLC revealed the following: cis-cis: 5.0%, cis-trans: 78.9%, trans-trans: 16.1%, with the ratio of cis isomers to the isomer mixture being 83.9 wt%. This isomer mixture (S05) remained in a liquid state.

[Evaluation of physical properties of dielectric constant and thermal diffusivity]
[Example 1]
<Preparation of sample for measuring relative permittivity>
An oil-soluble azo polymerization initiator V-601 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., diluted to 25 wt% with toluene, was added to the isomer mixture (S01) and mixed so that the initiator concentration was 2 wt%. The composition was then left overnight in a laboratory set to 25°C, and the state of the solution was confirmed. The fluidity was maintained the next day as well.
The resulting mixed solution contained compound (1-1-2a) and 5.7 wt % of an organic solvent (toluene), the ratio of cis-isomer compound to the isomer mixture was 90.9 wt %, and the composition retained fluidity in a liquid state at room temperature (25°C).
The resulting composition was applied to an A4-size polyimide film (Kapton 200H, manufactured by Panac Corporation) to a thickness of approximately 50 μm using a bar coater, placed in a stainless steel container with a quartz glass lid, purged with nitrogen, and then irradiated with 100 mJ of UV light to cure. The thickness of the cured film was determined by measuring the total thickness of the prepared sample with a Mitutoyo Digimatic Micrometer and subtracting the thickness of the polyimide film measured in the same manner. If the liquid isomer mixture (S01) became waxy due to refrigerated storage, it was melted into a liquid by placing it in an incubator set to 60°C for 15 minutes and used.

<Method for evaluating relative permittivity>
Using an AET Corporation cavity resonator (TM mode 10 GHz) connected to a vector network analyzer (Anritsu Corporation MS46522B-043), the resonant frequency shift and attenuation of a measurement sample cut to a size of 3 mm x 80 mm were measured, and the dielectric constant was calculated using the company's software. Furthermore, since the measurements were for a two-layer structure consisting of a polyimide film and a cured film, the dielectric constant of the cured film alone was calculated using the company's spreadsheet. To minimize the influence of moisture content in the strips during data comparison, the strips were shaped the day before the measurements, and the dielectric constant evaluation was initiated after the samples had been left to stand for at least 60 minutes in a laboratory at 20°C and 48% humidity.

<Method for evaluating thermal diffusivity>
The isomer mixture (S01) was poured into a 57 mm diameter aluminum flat dish using a dropper to a thickness of approximately 400 microns, and then thermally cured for 1 hour at 200° C. The cured product was peeled off from the aluminum flat dish, and a flat portion was selected and its thermal diffusivity was measured using an iPhase Mobile Type 1 thermal diffusivity measurement device.
The isomer mixture (S01) of the present invention can be thermally polymerized without an initiator, so no initiator was added. Therefore, no solvent for dissolving the initiator was included. That is, the isomer mixture (S01) used contained compound (1-1-2a), the ratio of cis-isomer compounds to the isomer mixture was 90.9 wt %, and it was a solvent-free composition that maintained liquid fluidity at room temperature (25°C). However, if curing is to be performed at a lower temperature, an initiator, a reaction accelerator, or the like may be added.

[Example 2]
A powder of polyphenylene ether oligomer (mPPE: Noryl 9000 resin manufactured by SABIC) having methacrylic groups introduced at both ends was added to the liquid isomer mixture (S01) so as to be 10 wt %, and dissolved by stirring while heating to 90°C. A polymerization initiator was then added and mixed in the same manner as in Example 1. After this, the state of the solution was checked after leaving it overnight. The fluidity was maintained the next day as well. A sample was prepared by film formation and curing in the same manner as in Example 1, and evaluated.

[Example 3]
mPPE powder was dissolved in the liquid isomer mixture (S01) to a concentration of 20 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. The state of the solution was then checked after leaving it overnight. The fluidity was maintained the next day. A sample was prepared by film formation and curing in the same manner as in Example 1, and evaluated.

[Example 4]
mPPE powder was dissolved in the liquid isomer mixture (S01) to a concentration of 30 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. The state of the solution was then checked after leaving it overnight. The fluidity was maintained the next day as well. A sample was prepared by film formation and curing in the same manner as in Example 1, and evaluated.
In this state, the composition was 4.9% cis-cis isomer, 58.7% cis-trans isomer, 6.4% trans-trans isomer, and 30% mPPE by weight. After this, an attempt was made to increase the amount of mPPE, but even after adding 40% by weight, some mPPE remained undissolved, so film formation was not carried out.

[Example 5]
A powder of a polymerizable liquid crystal compound (S01-tt) in which both cyclohexane rings of (S01) are trans isomers was dissolved in the liquid isomer mixture (S01) to a concentration of 10 wt %, and a polymerization initiator was added and mixed in the same manner as in Example 1. After this, the state of the solution was checked after leaving it overnight. The fluidity was maintained the next day as well. A sample was prepared by film formation and curing in the same manner as in Example 1, and evaluated.

[Example 6]
A powder of the polymerizable liquid crystal compound (S01-tt) was dissolved in the liquid isomer mixture (S01) to a concentration of 20 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. A sample was prepared by film formation and curing in the same manner as in Example 1, and evaluated.

[Example 7]
A powder of the polymerizable liquid crystal compound (S01-tt) was dissolved in the liquid isomer mixture (S01) to a concentration of 30 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. A sample was prepared by film formation and curing in the same manner as in Example 1, and evaluated.

[Example 8]
A powder of the polymerizable liquid crystal compound (S02) was dissolved in the liquid isomer mixture (S01) to a concentration of 10 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. A sample was prepared by film formation and curing in the same manner as in Example 1, and evaluated.

[Example 9]
A powder of the polymerizable liquid crystal compound (S02) was dissolved in the liquid isomer mixture (S01) to a concentration of 20 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. A film was formed and cured in the same manner as in Example 1 to prepare a sample, which was then evaluated.

[Example 10]
A powder of the polymerizable liquid crystal compound (S02) was dissolved in the liquid isomer mixture (S01) to a concentration of 30 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. A film was formed and cured in the same manner as in Example 1 to prepare a sample, which was then evaluated.

[Example 11]
A powder of the polymerizable liquid crystal compound (S03) was dissolved in the liquid isomer mixture (S01) to a concentration of 10 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. A film was formed and cured in the same manner as in Example 1 to prepare a sample, which was then evaluated.

[Example 12]
A powder of the polymerizable liquid crystal compound (S03) was dissolved in the liquid isomer mixture (S01) to a concentration of 20 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. A film was formed and cured in the same manner as in Example 1 to prepare a sample, which was then evaluated.

[Example 13]
A powder of the polymerizable liquid crystal compound (S03) was dissolved in the liquid isomer mixture (S01) to a concentration of 30 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. A film was formed and cured in the same manner as in Example 1 to prepare a sample, which was then evaluated.

[Example 14]
A powder of the polymerizable liquid crystal compound (S03) was dissolved in the liquid isomer mixture (S01) to a concentration of 40 wt %, and then a polymerization initiator was added and mixed in the same manner as in Example 1. A sample was prepared by film formation and curing in the same manner as in Example 1, and evaluated.
In this state, the composition was 4.2% cis-cis isomer, 50.3% cis-trans isomer, 5.5% trans-trans isomer, and 40% (S03) by weight. After this, an attempt was made to further increase the amount of powdered polymerizable liquid crystal compound (S03), but even when 50% by weight was added, some of the compound remained undissolved, so no film was formed.

[Comparative Example 1]
A comparative sample was prepared by mixing 6.92 g of bisphenol F type epoxy (jER807, manufactured by Mitsubishi Chemical Corporation), 3.8 g of 4,4'-diaminodiphenylmethane (98% by Fujifilm Wako Pure Chemical Industries, Ltd.), and 2.0 g of NMP, and then thermally curing the mixture after it became a transparent liquid. The film was then formed and cured in the same manner as in Example 1, and the dielectric constant and thermal diffusivity were evaluated. The curing conditions were that the sample was pre-baked on a hot plate at 120°C for 30 minutes, then the temperature was raised to 200°C, and the sample was cured for 30 minutes.

[Comparative Example 2]
Only the mPPE oligomer was dissolved in toluene to a concentration of 10 wt %, and a sample was prepared and evaluated in the same manner as in Comparative Example 1. However, because the mPPE oligomer used foams at temperatures above 130°C, the sample for measuring thermal diffusivity was formed into a film with a thickness of approximately 100 microns, cured at 220°C for 30 minutes, and the flat fragments were measured.

The compositions prepared by photocuring for dielectric constant measurements in Examples 1 to 14 are shown in Table 1.

When the isomer mixture (S01) was mixed with a compound (mPPE) with a different skeleton, which corresponds to an additive, the low-temperature stability of the solution improved, and transparency was maintained even when the soluble limit was increased. However, the higher the concentration of mPPE, the higher the viscosity, so the concentration must be adjusted depending on the printing or film-forming method. Furthermore, when a polymerizable liquid crystal compound (S03), which has a flexible alkyl group introduced between the highly linear biphenyl skeleton and the methacryl group, was mixed, a similar improvement in low-temperature stability was observed.

Table 2 summarizes some of the dielectric constants and thermal diffusivities measured for the samples in Examples 1 to 14 and Comparative Examples 1 and 2. Note that a low-dielectric-constant resin insulating film of the present invention can be preferably used if the dielectric constant (10 GHz) is 2.6 or less and the dielectric constant (28 GHz) is 2.7 or less. A thermal diffusivity of 1.20× ^10-7 or more is sufficient.

The samples of the examples exhibit good relative dielectric constants and thermal diffusivities, making them suitable for use as low-dielectric-constant resin insulating films. Furthermore, a comparison of Examples 5 and 8 reveals that the thermal diffusivity is higher when using a polymerizable liquid crystal compound with a trans-bicyclohexyl structure (S01-tt) than when using a biphenyl structure (S02).

[Evaluation of thermal conductivity of inorganic filler-containing composition]
[Example 15]
<Preparation of sample for thermal conductivity measurement>
The isomer mixture (S05) and boron nitride filler were combined in a volume ratio of 50:50 to prepare an inorganic filler-containing composition for use in evaluating thermal conductivity. 0.44 g of the isomer mixture (S05) and 0.80 g of boron nitride (PolarTherm PTX-25, manufactured by Momentive Performance Materials Japan, Inc.) were mixed in a mortar and agate.
The resulting composition contained compound (1-1-2) and boron nitride as an inorganic filler, the ratio of cis-isomer compound to isomer mixture was 83.9 wt %, and it was a solvent-free inorganic filler-containing composition that retained fluidity at room temperature (25°C).
The obtained composition is placed on the PTFE sheet of 1 mm thickness of A4 size, and the PTFE sheet (mold) of 0.5 mm thickness, which has a through-hole of predetermined size in the center of the same A4 size, and in consideration of the softening of PTFE, the amount of composition that is 20% more than the amount of composition required to fill the through-hole is placed in the through-hole, and then, while being careful not to scatter the composition due to static electricity, the PTFE sheet of 1 mm thickness of A4 size is placed on top of it.This layered sheet is sandwiched between 5 mm thick aluminum plates, and is set in a mini test press manufactured by Toyo Seiki Co., Ltd., which is set at 190 ℃, and is pressurized to 3 MPa while degassing, and is heated to 210 ℃, and then cured for 30 minutes.The pressure during pressing is set to 3 MPa so as not to crush the PTFE mold.
The through-holes in the PTFE sheet (mold) were sized as a 25 mm diameter x 0.5 mm thick disk (for measuring thermal diffusivity in the planar direction) and a 10 mm x 10 mm x 0.5 mm square (for measuring thermal diffusivity in the thickness direction).

<Thermal conductivity evaluation>
The specific heat (measured with a high-sensitivity differential scanning calorimeter, X-DSC7000, manufactured by SSI NanoTechnology Inc.) and specific gravity (measured with a specific gravity scale type hydrometer DME-220, manufactured by Shinko Denshi Co., Ltd.) of the obtained composition were determined in advance. Furthermore, the thermal conductivity in the planar direction and thickness direction was calculated using the thermal diffusivity determined with a thermal diffusivity measuring device LFA467 manufactured by Netsch Japan Co., Ltd. and its accompanying software, and the above-mentioned specific heat and specific gravity values.

[Comparative Example 3]
0.69 g of jER807 manufactured by Mitsubishi Chemical Corporation, 0.38 g of 4,4'-diamino-1,2-diphenylethane as a curing agent, and 2.50 g of boron nitride were weighed out and mixed well in an aluminum cup to prepare a sample in the same manner as in Example 15, and the thermal conductivity was measured.

The thermal conductivities measured in Example 15 and Comparative Example 3 are summarized in Table 3.

A comparison of Example 15 and Comparative Example 3 shows that the inorganic filler-containing composition using the isomer mixture (S05) of the present invention has a higher thermal conductivity. This is partly because the viscosity of the resin component before curing is lower in the inorganic filler-containing composition of the present invention, making it easier for the resin to be filled between the inorganic fillers, but it is also thought that the high thermal conductivity of the original resin component contributes to this. Therefore, the inorganic filler-containing composition of the present invention is useful not only for low-dielectric-constant resin applications, but also for high-heat-dissipation material applications.

The composition for forming low dielectric constant resins of the present invention can be prepared into a varnish-like form using no solvent or a small amount of organic solvent, and is an ideal material for applications requiring low environmental impact such as VOC issues and high fluidity. Furthermore, the resulting cured product has a low dielectric constant at 10 GHz and 28 GHz and exhibits high thermal diffusivity, making it particularly suitable for use in electronic circuit boards and their peripheral components used in the high-frequency range. Furthermore, since it exhibits high heat dissipation properties in addition to the above properties, it is also useful as a high-heat dissipation material.

Claims (20)

A composition for forming a low dielectric constant resin, comprising at least one compound selected from a cis-isomer compound having at least one cis-1,4-cyclohexylene structure represented by formula (1) and a polymer thereof, and also comprising at least one compound selected from a trans-isomer compound in which all cis-1,4-cyclohexylene structures are replaced with trans-1,4-cyclohexylene structures and a polymer thereof, wherein the ratio of cis-isomers to the isomer mixture is 50 wt % or more.

In formula (1),
At least one of A ¹ and A ² is cis-1,4-cyclohexylene;
A ¹ , A ² , and A ³ are independently cis-1,4-cyclohexylene, trans-1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, bicyclo[2.2.2]octo-1,4-diyl, bicyclo[3.1.0]hex-3,6-diyl, or fluorene-2,7-diyl; in these rings, at least one —CH ₂ — may be replaced by —O—, at least one —CH═ may be replaced by —N═, and at least one hydrogen may be a halogen or an alkyl having 1 to 12 carbon atoms in which at least one hydrogen may be replaced by a halogen; in this alkyl, at least one —CH ₂ — may be replaced by —O—, —CO—, —COO—, —OCO—, —C═C—, or —CH═CF—;
Z ¹ , Z ² , Z ³ , and Z ⁴ are independently a single bond or alkylene having 1 to 20 carbon atoms; in this alkylene, at least one —CH ₂ — may be replaced by —O—, —S—, —CO—, —COO—, —OCO—, —SO ₂ —, —CH═CH—, —CF═CF—, —CH═N—, —N═CH—, or —N═N—, and at least one hydrogen may be replaced by halogen;
m1 is 0, 1, or 2;
In the formula, when a plurality of ^A3 or ^Z3 is present, they may be the same or different,
R ^1a and R ^1b are independently a group selected from the polymerizable groups represented by formulae (PG-1) to (PG-6),
In formulas (PG-1) to (PG-6),
R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms;
q is 0 or 1;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.
Here, the ratio obtained by dividing the total amount of isomers that are cis isomers at even one position by the total amount of the isomer mixture is defined as the ratio of cis isomers to the isomer mixture.
2. The composition for forming a low dielectric constant resin according to claim 1, wherein the cured low dielectric constant resin has a relative dielectric constant of less than 3.0 at 10 GHz.
3. The composition for forming a low dielectric constant resin according to claim 1, which is solvent-free.
3. The composition for forming a low dielectric constant resin according to claim 1, wherein the composition contains 10 wt % or less of an organic solvent.
The composition for forming a low dielectric constant resin according to any one of claims 1 to 4, wherein in formula (1), R ^1a and R ^1b are independently a polymerizable group represented by formula (PG-1), (PG-5), or (PG-6).
2. The composition for forming a low dielectric constant resin according to claim 1, wherein the compound of formula (1) is a compound represented by any one of formulas (1-1) to (1-3):


In formulas (1-1) to (1-3),
^A1 is cis-1,4-cyclohexylene;
^A2 and ^A3 are independently cis-1,4-cyclohexylene, trans-1,4-cyclohexylene, 1,4-phenylene in which at least one hydrogen may be replaced by halogen or alkylene having 1 to 10 carbon atoms, bicyclo[2.2.2]octo-1,4-diyl, bicyclo[3.1.0]hex-3,6-diyl, or fluorene-2,7-diyl in which at least one hydrogen may be replaced by halogen or alkylene having 1 to 10 carbon atoms;
Z ¹ , Z ² , Z ³ , and Z ⁴ are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —COO—, —OCO—, —CH═CH—COO—, —OCO—CH═CH—, —(CH ₂ ) _a —COO—, —OCO—(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —OCF ₂ —, or —CF ₂ O—; where a is an integer from 1 to 20;
In the formula, when a plurality of ^A3 or ^Z3 is present, they may be the same or different,
R ^1a and R ^1b are independently a polymerizable group represented by formula (PG-1), (PG-5), or (PG-6),

In formulas (PG-1), (PG-5), and (PG-6),
R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms;
q is 0 or 1;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.
2. The composition for forming a low dielectric constant resin according to claim 1, wherein the compound of formula (1) is a compound represented by formula (1-1-1) or (1-1-2):


In formulas (1-1-1) to (1-1-2),
^A1 is cis-1,4-cyclohexylene;
The cyclohexane ring represented by the hexagon is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene;
Z ¹ , Z ² and Z ⁴ are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —COO—, —OCO—, —CH═CH—COO—, —OCO—CH═CH—, —(CH ₂ ) _a —COO—, —OCO—(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —OCF ₂ —, or —CF ₂ O—; where a is an integer from 1 to 20;
X is fluorine or methyl;
n is an integer from 0 to 4,
When n is 2 or more, and when there are a plurality of X's in the formula, they may be the same or different,
R ^1a and R ^1b are independently a polymerizable group represented by formula (PG-1), (PG-5), or (PG-6),
In formulas (PG-1), (PG-5), and (PG-6),
R ^b is hydrogen, halogen, —CF3, or alkyl having 1 to 5 carbon atoms;
q is 0 or 1;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.
2. The composition for forming a low dielectric constant resin according to claim 1, wherein the compound of formula (1) is a compound represented by any one of formulas (1-2-1) to (1-2-4):


In formulas (1-2-1) to (1-2-4),
^A1 is cis-1,4-cyclohexylene;
The cyclohexane ring represented by the hexagon is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene;
Z ¹ , Z ² , Z ³ and Z ⁴ are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —COO—, —OCO—, —CH═CH—COO—, —OCO—CH═CH—, —CH ₂ CH ₂ —COO—, —OCO—CH ₂ CH ₂ —, —SO ₂ —, —CH═CH—, —OCF ₂ —, or —CF ₂ O—; where a is an integer from 1 to 20;
X is fluorine or methyl;
n is an integer from 0 to 4,
When n is 2 or more, and when there are a plurality of X's in the formula, they may be the same or different,
R ^1a and R ^1b are independently a polymerizable group represented by formula (PG-1), (PG-5), or (PG-6),
In formulas (PG-1), (PG-5), and (PG-6),
R ^b is hydrogen, halogen, —CF ₃ or alkyl having 1 to 5 carbon atoms;
q is 0 or 1;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.
2. The composition for forming a low dielectric constant resin according to claim 1, wherein the compound of formula (1) is a compound represented by any one of formulas (1-3-1) to (1-3-7):



In formulas (1-3-1) to (1-3-7),
^A1 is cis-1,4-cyclohexylene;
The cyclohexane ring represented by the hexagon is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene;
Z ¹ , Z ² , Z ³ and Z ⁴ are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —CH═CH—, —COO—, —OCO—, —CH═CH-COO—, —OCO-CH═CH—, —(CH ₂ ) _a -COO—, —OCO-(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —CH═CH—, —OCF ₂ —, or —CF ₂ O—; where a is an integer of 1 to 20;
In the formula, Z ³ may be the same or different,
X is fluorine or methyl;
n is an integer from 0 to 4,
When n is 2 or more, and when there are a plurality of X's in the formula, they may be the same or different,
R ^1a and R ^1b are independently polymerizable groups represented by formulas (PG-1), (PG-5), and (PG-6),

In formulas (PG-1), (PG-5) and (PG-6),
R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms;
q is 0 or 1;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.
2. The composition for forming a low dielectric constant resin according to claim 1, wherein in formula (1), R ^1a and R ^1b are polymerizable groups represented by formula (PG-1).

In formula (PG-1),
R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms;
When there are a plurality of Rb ^'s in the formula, they may be the same or different.
A composition containing at least one compound selected from the group consisting of cis-isomer compounds represented by formula (1-1-1a), (1-1-2a), and formulas (1-2-1a) to (1-2-4a), and polymers thereof,
The composition contains at least one selected from a trans isomer compound in which all cis-1,4-cyclohexylene structures of the cis isomer compound are replaced with trans-1,4-cyclohexylene structures, and a polymer thereof;
The ratio of cis isomers to the isomer mixture is 50 wt % or more,
and a composition for forming a low dielectric constant resin, the low dielectric constant resin being cured and formed has a relative dielectric constant of less than 3.0 at 10 GHz.


In formulas (1-1-1a), (1-1-2a), and (1-2-1a) to (1-2-4a),
^A1 is cis-1,4-cyclohexylene;
The cyclohexane ring represented by the hexagon is cis-1,4-cyclohexylene or trans-1,4-cyclohexylene;
^Z2 and ^Z3 are independently a single bond, —(CH ₂ ) _a —, —O(CH ₂ ) _a —, —(CH ₂ ) _a O—, —O(CH ₂ ) _a O—, —COO—, —OCO—, —CH═CH—COO—, —OCO—CH═CH—, —(CH ₂ ) _a —COO—, —OCO—(CH ₂ ) _a —, —CH═CH—, —SO ₂ —, —OCF ₂ —, or —CF ₂ O—; where a is an integer of 1 to 20;
m is an integer from 0 to 20;
M is a single bond or oxygen;
X is fluorine or methyl;
n is an integer from 0 to 4,
When n is 2 or more, and when there are a plurality of X's in the formula, they may be the same or different,
R ^b is hydrogen, halogen, —CF ₃ , or alkyl having 1 to 5 carbon atoms;
When there are a plurality of R ^b , m or M in the formula, they may be the same or different.
Here, the ratio obtained by dividing the total amount of isomers that are cis isomers at even one position by the total amount of the isomer mixture is defined as the ratio of cis isomers to the isomer mixture.
The composition for forming a low dielectric constant resin according to any one of claims 1 to 11, which contains a non-polymerizable liquid crystal compound.
The composition for forming a low dielectric constant resin according to any one of claims 1 to 12, which contains an inorganic filler.
14. The composition for forming a low dielectric constant resin according to claim 13, wherein the inorganic filler is at least one selected from the group consisting of silicon compounds such as spherical silica, pulverized silica, hollow silica, and fumed silica, and metal oxides such as aluminum nitride, boron nitride, silicon nitride, diamond, graphite, silicon carbide, magnesium oxide, aluminum oxide, zinc oxide, titanium oxide, tin oxide, aluminum oxide, and calcium oxide.
The composition for forming a low dielectric constant resin according to any one of claims 1 to 14, which contains a fibrous reinforcing material.
16. The composition for forming a low dielectric constant resin according to claim 15, wherein the fibrous reinforcing material is at least one selected from the group consisting of glass cloth, low dielectric glass cloth, carbon fiber, carbon nanotube, polyamide fiber, aramid fiber, polyparaphenylene benzobisoxazole fiber, liquid crystalline polyester fiber, silicate whisker, alumina whisker, magnesium oxide whisker, zinc oxide whisker, and aluminum nitride whisker.
A low dielectric constant resin insulating film which is a polymer molded product obtained by curing the composition for forming a low dielectric constant resin according to any one of claims 1 to 16 with heat or ultraviolet light.
A low dielectric constant resin film or a low dielectric constant resin sheet, which is a polymer molded product obtained by curing the composition for forming a low dielectric constant resin according to any one of claims 1 to 16 with heat or ultraviolet light.
A low dielectric constant resin part which is a polymer molded article obtained by curing the composition for forming a low dielectric constant resin according to any one of claims 1 to 16 with heat or ultraviolet light.
An electronic device using a polymer molded article obtained by curing the composition for forming a low dielectric constant resin according to any one of claims 1 to 16 with heat or ultraviolet light.