JP7513467B2 - Graft-modified polymethylpentene composition, molded article, and copper-clad laminate - Google Patents

Description

The present invention relates to a graft-modified polymethylpentene composition, a molded article and a film made of the graft-modified polymethylpentene composition, and a flexible printed wiring board including a film made of the graft-modified polymethylpentene composition.

In recent years, there has been a demand for communication devices such as smartphones and electronic devices such as next-generation televisions to transmit and receive large volumes of data at high speeds. This has led to the use of higher frequencies for electrical signals. Specifically, in the field of wireless communications, the fifth-generation mobile communications system (5G) is expected to be introduced around 2020. When the fifth-generation mobile communications system is introduced, the use of high-frequency bands of 10 GHz or higher is being considered.

However, as the frequency of the signal used increases, the quality of the output signal decreases, which can lead to erroneous recognition of information, i.e., transmission loss increases. This transmission loss is made up of conductor loss caused by the conductor and dielectric loss caused by the insulating resin that makes up electrical and electronic components such as circuit boards in electronic devices and communications devices. Since conductor loss is proportional to the 0.5th power of the frequency used and dielectric loss is proportional to the 1st power of the frequency, the impact of this dielectric loss becomes extremely large in high frequency bands, especially in the GHz band.

For this reason, in order to reduce transmission loss, there is a demand for low-dielectric materials with low relative permittivity and dielectric dissipation factor, which are factors related to dielectric loss. In light of this, the use of compositions containing polyolefins, which have excellent electrical properties such as low dielectric loss and low dielectric dissipation factor, as low-dielectric materials that can be used in high-frequency bands, is being considered (see Patent Document 1).

JP 2013-245305 A

A preferred application of materials with excellent low dielectric properties is flexible printed wiring boards. In flexible printed wiring boards, materials with low dielectric properties are usually used as films or sheets.

Flexible printed wiring boards are usually copper-clad laminates (CCLs). However, polyolefin compositions such as those described in Patent Document 1 usually do not adhere well to metal foils such as copper foils.

The present invention has been made in consideration of the above problems, and aims to provide a graft-modified polymethylpentene composition that has good formability, such as film formation, and gives a molded product that has excellent adhesion to metal foils such as copper foils, a molded product such as a film made of the graft-modified polymethylpentene composition, and a copper-clad laminate that includes the aforementioned film.

The inventors conducted extensive research to solve the above problems and have now completed the present invention.

That is, the present invention provides the following (1) to (9).
(1) A composition comprising a graft-modified polymethylpentene (A) and a crosslinking agent (B),
A graft-modified polymethylpentene composition, in which a polar group has been introduced into the graft-modified polymethylpentene (A) by graft modification.
(2) The polymethylpentene composition according to (1), wherein the crosslinking agent (B) is at least one member selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, and trimethallyl isocyanurate.
(3) The graft-modified polymethylpentene composition according to (1) or (2), in which the content of the crosslinking agent (B) is 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the graft-modified polymethylpentene (A).
(4) The graft-modified polymethylpentene composition according to any one of (1) to (3), wherein the graft-modified polymethylpentene (A) is graft-modified with glycidyl (meth)acrylate and styrene.
(5) The graft-modified polymethylpentene composition according to any one of (1) to (4), wherein the melting point of the graft-modified polymethylpentene (A) is 200° C. or higher.
(6) A molded article comprising the graft-modified polymethylpentene composition according to any one of (1) to (5).
(7) A molded article, which is obtained by subjecting the molded article according to (6) to a crosslinking treatment using a crosslinking agent (B).
(8) The molded article according to (6) or (7), which is a film.
(9) A copper-clad laminate comprising the film according to (8).

The present invention can provide a graft-modified polymethylpentene composition that has good formability, such as film formation, and that gives a molded product that has excellent adhesion to metal foils such as copper foils, a molded product such as a film made of the graft-modified polymethylpentene composition, and a copper-clad laminate that includes the aforementioned film.

<Graft-modified polymethylpentene composition>
The graft-modified polymethylpentene composition contains a graft-modified polymethylpentene (A) having a polar group and a crosslinking agent (B).
Since the molded article made of the graft-modified polymethylpentene composition contains the crosslinking agent (B), it can be crosslinked, for example, by heating, electron beam irradiation, etc. The crosslinked molded article is endowed with desirable heat resistance and improved mechanical properties for flexible printed wiring board applications.

Below, we will explain the essential and optional components that the graft-modified polymethylpentene composition may contain.

<Graft modified polymethylpentene (A)>

The graft-modified polymethylpentene (A) is a resin in which polymethylpentene has been graft-modified, and is not particularly limited as long as it is a resin having a polar group.

Here, a polar group refers to a polar atomic group, and when this group is present in an organic compound, the compound becomes polar. Specific examples of polar groups that can be introduced into polymethylpentene by grafting include carboxy groups derived from unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, and isocrotonic acid; acid anhydride groups, halocarbonyl groups, carboxylic acid amide groups, imide groups, and carboxylic acid ester groups derived from derivatives of the aforementioned unsaturated carboxylic acids, such as acid anhydrides, acid halides, amides, imides, and esters; glycidyl methacrylate, glycidyl acrylate, maleic acid, and glycidyl methacrylate; Examples of the polar groups include monoglycidyl phosphate, diglycidyl maleate, monoglycidyl itaconate, diglycidyl itaconate, monoglycidyl allyl succinate, diglycidyl allyl succinate, glycidyl p-styrene carboxylate, allyl glycidyl ether, methacryl glycidyl ether, styrene-p-glycidyl ether, p-glycidyl styrene, 3,4-epoxy-1-butene, 3,4-epoxy-3-methyl-1-butene, and epoxy groups derived from epoxy group-containing vinyl monomers such as vinylcyclohexene monoxide. Among these polar groups, the epoxy group is preferred because it provides good adhesion between a molded article made of the graft-modified polymethylpentene composition and a metal foil such as a copper foil, and provides good crosslinking reactivity between the graft-modified polymethylpentene (A) and the crosslinking agent (B).

Typically, graft-modified polymethylpentene (A) is a resin in which polymethylpentene is graft-modified with a vinyl monomer having a polar group in the presence of a radical polymerization initiator.

The graft-modified polymethylpentene (A) is preferably polymethylpentene graft-modified with a vinyl monomer having a polar group and an aromatic vinyl monomer, and more preferably polymethylpentene graft-modified with glycidyl (meth)acrylate and styrene.

Examples of radical polymerization initiators that can be used when graft-modifying polymethylpentene include ketone peroxides such as methyl ethyl ketone peroxide and methyl acetoacetate peroxide; peroxyketals such as 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, and 2,2-bis(tert-butylperoxy)butane; hydroperoxides such as permethane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, diisopropylbenzene hydroperoxide, and cumene hydroperoxide; dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, α,α'-bis(tert-butylperoxy-m-isopropyl)benzene, t Examples of the peroxyester include dialkyl peroxides such as tert-butylcumyl peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3; diacyl peroxides such as benzoyl peroxide; peroxydicarbonates such as di(3-methyl-3-methoxybutyl)peroxydicarbonate and di-2-methoxybutylperoxydicarbonate; and peroxyesters such as tert-butylperoxyoctate, tert-butylperoxyisobutyrate, tert-butylperoxylaurate, tert-butylperoxy-3,5,5-trimethylhexanoate, tert-butylperoxyisopropylcarbonate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butylperoxyacetate, tert-butylperoxybenzoate, and di-tert-butylperoxyisophthalate. The above radical polymerization initiators can be used alone or in combination of two or more.

The amount of radical polymerization initiator used is not particularly limited as long as the graft modification reaction proceeds well. The amount of radical polymerization initiator used is preferably 0.01 parts by mass or more and 10 parts by mass or less, and more preferably 0.2 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of polymethylpentene.

Examples of vinyl monomers having a polar group that can be used for graft modification include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, and isocrotonic acid; derivatives of these unsaturated carboxylic acids such as acid anhydrides, acid halides, amides, imides, and esters; and epoxy group-containing vinyl monomers such as glycidyl methacrylate, glycidyl acrylate, monoglycidyl maleate, diglycidyl maleate, monoglycidyl itaconate, diglycidyl itaconate, monoglycidyl allyl succinate, diglycidyl allyl succinate, glycidyl p-styrene carboxylate, allyl glycidyl ether, methacrylic glycidyl ether, styrene-p-glycidyl ether, p-glycidyl styrene, 3,4-epoxy-1-butene, 3,4-epoxy-3-methyl-1-butene, and vinylcyclohexene monoxide.

Among these, epoxy group-containing vinyl monomers are preferred, with glycidyl methacrylate and glycidyl acrylate being more preferred, and glycidyl methacrylate being particularly preferred.

The above vinyl monomers having polar groups can be used alone or in combination of two or more.

The amount of the vinyl monomer having a polar group used for graft modification of polymethylpentene is preferably 0.1 parts by mass or more and 12 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, and particularly preferably 1 part by mass or more and 8 parts by mass or less, per 100 parts by mass of polymethylpentene.

By using polymethylpentene modified with a vinyl monomer having a polar group in an amount within this range, it is easy to obtain graft-modified polymethylpentene that gives a molded product that adheres well to metal foil such as copper foil.

As mentioned above, the graft-modified polymethylpentene (A) is preferably polymethylpentene graft-modified with a vinyl monomer having a polar group and an aromatic vinyl monomer.

By using a vinyl monomer having a polar group in combination with an aromatic vinyl monomer, the grafting reaction is stabilized, making it easier to graft the desired amount of vinyl monomer having a polar group.

Specific examples of aromatic vinyl monomers include styrene; alkylstyrenes such as o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, β-methylstyrene, dimethylstyrene, and trimethylstyrene; chlorostyrenes such as o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, α-chlorostyrene, β-chlorostyrene, dichlorostyrene, and trichlorostyrene; bromostyrenes such as o-bromostyrene, m-bromostyrene, p-bromostyrene, dibromostyrene, and tribromostyrene; o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, fluorostyrenes such as o-nitrostyrene, m-nitrostyrene, p-nitrostyrene, dinitrostyrene, and trinitrostyrene; nitrostyrenes such as o-nitrostyrene, m-nitrostyrene, p-nitrostyrene, dinitrostyrene, and trinitrostyrene; hydroxystyrenes such as o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, dihydroxystyrene, and trihydroxystyrene; and dialkenylbenzenes such as o-divinylbenzene, m-divinylbenzene, p-divinylbenzene, o-diisopropenylbenzene, m-diisopropenylbenzene, and p-diisopropenylbenzene.

Among these aromatic vinyl monomers, styrene, α-methylstyrene, p-methylstyrene, o-divinylbenzene, m-divinylbenzene, p-divinylbenzene, or a mixture of divinylbenzene isomers is preferred because of its low cost, with styrene being particularly preferred.

Aromatic vinyl monomers can be used alone or in combination of two or more.

The amount of aromatic vinyl monomer having a polar group used for graft modification of polymethylpentene is preferably 0.1 parts by mass or more and 12 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, and particularly preferably 1 part by mass or more and 8 parts by mass or less, per 100 parts by mass of polymethylpentene.

The melting point of the graft-modified polymethylpentene (A) is not particularly limited. The melting point of the graft-modified polymethylpentene (A) is preferably 80° C. or higher, more preferably 100° C. or higher, and even more preferably 120° C. or higher and 240° C. or lower.
From the viewpoint of heat resistance of the molded product, the melting point of the graft-modified polymethylpentene (A) is preferably 200° C. or higher.
When the melting point of the graft-modified polymethylpentene (A) is within the above range, good heat resistance can be imparted to a molded article made of the graft-modified polymethylpentene composition.
In addition, when the melting point of the graft-modified polymethylpentene (A) is 240° C. or lower, decomposition or sublimation of the crosslinking agent (B) can be easily suppressed during preparation or use of the graft-modified polymethylpentene composition.

<Crosslinking Agent (B)>
The graft-modified polymethylpentene composition contains a crosslinking aid (B). The crosslinking aid (B) crosslinks the graft-modified polymethylpentene (A), thereby contributing to improving the heat resistance and mechanical properties of a molded article made of the graft-modified polymethylpentene composition.

The crosslinking agent (B) crosslinks the graft-modified polymethylpentene (A) with each other through a crosslinking treatment such as heating or electron beam irradiation, which is selected according to the type of reactive functional group possessed by the crosslinking agent (B) (described later).

The crosslinking agent (B) is a compound having two or more reactive functional groups in the same molecule. In a molded article made of a graft-modified polymethylpentene composition, it is easy to obtain a molded article having excellent heat resistance by generating molecular crosslinks using the crosslinking agent (B).

Examples of the reactive functional group of the crosslinking agent (B) include a carbon-carbon double bond-containing group, a halogen atom, a dicarboxylic anhydride group, a carboxy group, an amino group, a cyano group, and a hydroxyl group. The reactive functional groups present in the same molecule of the crosslinking agent may be the same or different.
Among the above reactive functional groups, a carbon-carbon double bond-containing group is preferred because it has excellent crosslinking reactivity and the stability of the crosslinked structure after crosslinking.
Examples of the carbon-carbon double bond-containing group include alkenyl groups such as vinyl, allyl, and methallyl groups, unsaturated acyl groups such as acryloyl and methacryloyl groups, maleimide groups, etc. The carbon-carbon double bond-containing group is preferably an alkenyl group having 2 to 4 carbon atoms, and particularly preferably an allyl group.

Specific examples of suitable crosslinking agents (B) include triallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, trimethylolpropane tri(meth)acrylate, 1,3,5-triacryloylhexahydro-1,3,5-triazine, triallyl trimellitate, m-phenylenediamine bismaleimide, p-quinone dioxime, p,p'-dibenzoylquinone dioxime, dipropargyl terephthalate, diallyl phthalate, N,N',N'',N'''-tetraallyl terephthalamide, and vinyl group-containing polysiloxanes such as polymethylvinylsiloxane and polymethylphenylvinylsiloxane. Note that "(meth)acrylate" refers to both acrylate and methacrylate.

Among these, one or more selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, and trimethylolpropane tri(meth)acrylate are more preferred. In particular, in terms of crosslinking reactivity, it is preferred that the crosslinking agent (B) contains triallyl isocyanurate (TAIC) and/or trimethylolpropane tri(meth)acrylate (TMPTMA), and it is particularly preferred that the crosslinking agent (B) is TAIC.

The amount of crosslinking agent (B) used is not particularly limited as long as it does not impair the object of the present invention. The amount of crosslinking agent (B) used in the graft-modified polymethylpentene composition is, for example, preferably 1 part by mass or more and 100 parts by mass or less, more preferably 3 parts by mass or more and 50 parts by mass or less, and even more preferably 5 parts by mass or more and 30 parts by mass or less, per 100 parts by mass of the graft-modified polymethylpentene.

The graft-modified polymethylpentene composition may contain other resins besides the graft-modified polymethylpentene (A) to the extent that the object of the present invention is not impaired. The ratio of the mass of the graft-modified polymethylpentene (A) to the total mass of the resin components contained in the graft-modified polymethylpentene composition is typically preferably 80 mass%, more preferably 90 mass% or more, even more preferably 95 mass% or more, and particularly preferably 100 mass%.

Examples of other resins include non-graft-modified polyolefins, graft-modified polyolefins other than graft-modified polymethylpentene, non-liquid crystal polyesters such as polyethylene terephthalate and polybutylene terephthalate, liquid crystal polyesters, polyamides, polyesteramides, polyimides, polyamideimides, polycarbonates, polyacetals, polyphenylene sulfides, polyphenylene ethers, polysulfones, polyethersulfones, polyetherimides, silicone resins, and fluororesins.

The graft-modified polymethylpentene composition can be blended with an inorganic filler as necessary. Examples of inorganic fillers include calcium carbonate, talc, clay, silica, magnesium carbonate, barium sulfate, titanium oxide, alumina, montmorillonite, gypsum, glass flakes, glass fiber, milled glass fiber, carbon fiber, alumina fiber, silica alumina fiber, aluminum borate whisker, and potassium titanate fiber. The inorganic fillers may be used alone or in combination of two or more.

The amount of these inorganic fillers used is determined appropriately according to the application of the graft-modified polymethylpentene composition, so long as the low dielectric properties of the graft-modified polymethylpentene composition are not impaired. For example, when a film is formed using the graft-modified polymethylpentene composition, the upper limit of the amount of inorganic fillers used is determined so long as the mechanical strength of the film is not significantly impaired.

The graft-modified polymethylpentene composition can further contain various additives, such as organic fillers, antioxidants, heat stabilizers, light stabilizers, flame retardants, lubricants, antistatic agents, colorants, rust inhibitors, crosslinking agents, foaming agents, fluorescent agents, surface smoothing agents, surface gloss improvers, and release improvers, as necessary.

These additives may be used alone or in combination of two or more.

The form of the graft-modified polymethylpentene composition is not particularly limited. The graft olefin composition may be, for example, a composition in which the crosslinking agent (B) is dispersed in solid graft-modified polymethylpentene (A), or a powdered composition in which powdered graft-modified polymethylpentene (A) and powdered crosslinking agent (B) are mixed. As the graft-modified polymethylpentene composition, a composition in which the crosslinking agent (B) is dispersed in solid graft-modified polymethylpentene (A) is preferred.

The dielectric loss tangent at 10 GHz of the graft-modified polymethylpentene composition is preferably 0.0025 or less.
The graft-modified polymethylpentene composition preferably has a relative dielectric constant of 2.8 or less at a frequency of 10 GHz.

The above-mentioned graft-modified polymethylpentene composition takes advantage of its low dielectric properties and is suitable for use in electrical and electronic components, information and communication devices, and parts for such information and communication devices that are used in the high frequency band.

The method for producing the graft-modified polymethylpentene composition is not particularly limited. The graft-modified polymethylpentene composition can be produced by mixing the graft-modified polymethylpentene (A) and the crosslinking agent (B).
The method for mixing the graft-modified polymethylpentene (A) and the crosslinking agent (B) is not particularly limited, but a preferred mixing method is a method using a melt kneading device such as a single-screw extruder or a twin-screw extruder.

The mixing conditions are not particularly limited as long as the graft-modified polymethylpentene (A) and the crosslinking agent (B) can be mixed uniformly and each component does not undergo excessive thermal decomposition or sublimation. When a melt kneading device is used, for example, the melt kneading is performed at a temperature that is preferably 5°C to 100°C higher, more preferably 10°C to 50°C higher than the melting point of the graft-modified polymethylpentene (A).

It is preferable that a molded article made of the graft-modified polymethylpentene composition is subjected to a crosslinking treatment with a crosslinking agent (B). The method of crosslinking is not particularly limited and is appropriately selected depending on the type of reactive functional group possessed by the crosslinking agent (B). Examples of the method of crosslinking include electron beam irradiation, heating, and light irradiation.
Electron beam irradiation is preferred because it is possible to form a crosslinked structure after film formation. When electron beam irradiation is performed, the dose of the electron beam is preferably from 100 kGy to 1,200 kGy, and more preferably from 200 kGy to 800 kGy.
In the method of crosslinking by heating, if the crosslinking temperature is too high, the molded article may be thermally deteriorated or deformed when crosslinking the molded article. Conversely, if the crosslinking temperature is too low, the graft-modified polymethylpentene composition may be crosslinked in the extruder. In this case, the liquid graft-modified polymethylpentene composition is likely to thicken in the extruder, resulting in poor appearance of the molded article, making it difficult to apply a melt molding method as a molding method for the graft-modified polymethylpentene composition. In the method by light irradiation, except in special cases, it is necessary to add an initiator such as a photoacid generator to the graft-modified polymethylpentene composition. However, such an initiator is easily decomposed in a high-temperature extruder. In consideration of the above points, electron beam irradiation is preferable in that it is possible to easily form a crosslinked structure in a molded article such as a film without causing various problems.
That is, the method for producing a molded product crosslinked with the crosslinking agent (B) is as follows:
The graft-modified polymethylpentene composition is molded by the above-mentioned method or the like to obtain a molded article;
and irradiating the obtained molded article with an electron beam to crosslink the molded article with the crosslinking agent (B).

The graft-modified polymethylpentene composition described above has low dielectric properties in the high frequency band and excellent melt processability when processing films, etc., so it is preferably processed into a film, and the film is used to manufacture a copper-clad laminate in which the copper foil is well adhered to the film.

In addition, by subjecting a molded article made of the graft-modified polymethylpentene composition to a crosslinking treatment using a crosslinking agent (B), a molded article such as a film or sheet having heat resistance suitable for a flexible printed wiring board, or a copper-clad laminate using the molded article, can be obtained.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[Production Example 1]
(Production of modified polymethylpentene 1 (mTPX))
(a1) 100 parts by mass of polymethylpentene (Mitsui Chemicals, TPX grade MX002) and (b1) 0.5 parts by mass of 1,3-di(tert-butylperoxyisopropyl)benzene (NOF Corp.: Perbutyl P) were fed from a hopper port to a twin-screw extruder (46 mmφ, L/D=63, Kobe Steel, Ltd.) set at a cylinder temperature of 230° C. and a screw rotation speed of 150 rpm, and melt-kneaded. (c1) 1 part by mass of styrene and (d1) 1 part by mass of glycidyl methacrylate were then added midway through the cylinder. Thereafter, pellets of modified polyolefin resin were obtained by vacuum devolatilization from a vent port.

The obtained resin pellets were dissolved in xylene at 130°C, and then cooled to room temperature again to precipitate a recrystallized resin. The amount of glycidyl methacrylate modification was measured using an automatic potentiometric titrator (AT700 manufactured by Kyoto Electronics Manufacturing Co., Ltd.) in accordance with JIS K7236. The amount of glycidyl methacrylate modification in modified polyolefin 1 (mTPX) was 0.75% by mass.

[Production Example 2]
(Production of Modified Polypropylene 2 (mPP))
(a1) 100 parts by mass of polypropylene (Prime Polymer polypropylene grade J106G) and (b1) 0.25 parts by mass of 1,3-di(tert-butylperoxyisopropyl)benzene (NOF: Perbutyl P) were fed from the hopper port to the same twin-screw extruder as in Production Example 1, with the cylinder temperature set at 200 ° C. and the screw rotation speed set at 150 rpm, and melt-kneaded. (c1) 2.5 parts by mass of styrene and (d1) 2.5 parts by mass of glycidyl methacrylate were added from the middle of the cylinder. Thereafter, pellets of modified polyolefin resin were obtained by vacuum devolatilization from the vent port. The amount of modification was measured in the same manner as in Production Example 1, and the amount of glycidyl methacrylate modification of the modified polypropylene (mPP) was 1.25% by mass.

[Examples 1 to 5 and Comparative Examples 1 to 13]
100 parts by mass of a polyolefin of the type shown in Table 1 and a crosslinking agent of the type and amount shown in Table 1 were fed from a hopper port to a twin-screw extruder (25 mmφ, L/D=40, manufactured by Technobel) set at a cylinder temperature of 230° C. and a screw rotation speed of 150 rpm, and melt-kneaded to obtain a composition containing a polyolefin and a crosslinking agent.

The composition obtained as described above was melted at 230°C, and the molten composition was extruded through a 140 mm wide T-die to a thickness of approximately 100 μm to obtain a film.

The resulting film was irradiated with an electron beam at an acceleration voltage of 200 kV and an absorbed dose of 400 kGy to crosslink the film with the crosslinking agent.

The crosslinked film was evaluated for dielectric properties (Dk (dielectric constant), Df (dielectric loss tangent)) and reflow heat resistance according to the following methods. The evaluation results are shown in Table 1.
When a film could not be produced or the strength of the film was extremely low, the dielectric properties were not evaluated.

[Dielectric properties (Dk (dielectric constant), Df (dielectric tangent)]
The relative dielectric constant and dielectric loss tangent of the obtained composition were measured at the following frequencies using a cavity resonator perturbation method complex dielectric constant evaluation device.
Measurement frequency: 10 GHz
Measurement conditions: Temperature 22°C to 24°C, humidity 45% to 55%
Measurement sample: A sample that had been left to stand for 24 hours under the above measurement conditions was used.

[Reflow heat resistance test]
In order to evaluate the heat resistance of the copper-clad laminate, a reflow heat resistance test was carried out.
Both sides of the film sample were sandwiched between electrolytic copper foils (CF-T49A-DS-HD2-12 (manufactured by Fukuda Metal Foil and Powder Co., Ltd.)) and vacuum pressed at 180° C. to prepare a simulated copper-clad laminate (CCL).
The obtained CCL was passed through a high-temperature reflow furnace (UNI6116S, Antom) under conditions assuming the use of lead-free solder, and the CCL sample after passing through the high-temperature reflow furnace was observed. The conditions for passing through the high-temperature reflow furnace were a peak temperature of 288±3°C, a passing time of 60 seconds, and three passing cycles.
Based on the observation results, the reflow heat resistance was evaluated according to the following criteria. If the reflow heat resistance could not be evaluated, it was rated C or D. The acceptable range for passing the reflow heat resistance is the following A rating.
A: The copper foil did not peel off or peeled off slightly, and the film shape was maintained.
B: The copper foil was significantly peeled off, the copper foil surface was uneven, and voids were generated in the film.
C: The copper foil did not adhere or the strength of the film was too low to produce a CCL.
D: A film sample could not be molded.

The abbreviations in Table 1 are as follows.
mTPX: Graft-modified polymethylpentene obtained in Production Example 1 mPP: Graft-modified polypropylene obtained in Production Example 2 TPX: Unmodified polymethylpentene (TPX grade MX002, manufactured by Mitsui Chemicals)
PP: Unmodified polypropylene (Prime Polymer polypropylene grade J108M)
TAIC: Triallyl isocyanurate TMPTMA: Trimethylolpropane trimethacrylate

It is seen from Examples 1 to 5 that the graft-modified polymethylpentene composition containing the graft-modified polyolefin (A) having a polar group and the crosslinking agent (B) can be satisfactorily formed into a film. It is also seen that by crosslinking the film made of the graft-modified polymethylpentene composition containing the graft-modified polyolefin (A) having a polar group and the crosslinking agent (B) obtained in Examples 1 to 5, a copper-clad laminate (CCL) having excellent reflow heat resistance and including a film having excellent low dielectric properties can be produced.
On the other hand, according to Comparative Examples 1 to 13, when an unmodified polyolefin or a graft-modified product of a polyolefin other than polymethylpentene is used, it is difficult to obtain a composition having good film-forming properties, and it is difficult to produce a copper-clad laminate (CCL) having excellent reflow heat resistance.

Claims (8)

A graft-modified polymethylpentene composition comprising a graft-modified polymethylpentene (A) and a crosslinking agent (B),
the graft-modified polymethylpentene (A) has a polar group introduced therein by graft modification,
The crosslinking agent (B) is at least one selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, and trimethylolpropane tri(meth)acrylate,
the content of the crosslinking agent (B) is 1 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the graft-modified polymethylpentene (A),
A graft-modified polymethylpentene composition, in which the proportion of the mass of the graft-modified polymethylpentene (A) relative to the total mass of resin components contained in the graft-modified polymethylpentene composition is 80 mass% or more. The graft-modified polymethylpentene composition according to claim 1 , wherein the content of the crosslinking agent (B) is 3 parts by mass or more and 20 parts by mass or less based on 100 parts by mass of the graft-modified polymethylpentene (A). The graft-modified polymethylpentene composition according to claim 1 or 2 , wherein the graft-modified polymethylpentene (A) is graft-modified with glycidyl (meth)acrylate and styrene. The graft-modified polymethylpentene composition according to any one of claims 1 to 3 , wherein the melting point of the graft-modified polymethylpentene (A) is 200°C or higher. A molded article comprising the graft-modified polymethylpentene composition according to any one of claims 1 to 4 . A molded article, comprising the molded article according to claim 5 , which is subjected to a crosslinking treatment with the crosslinking agent (B). The molded article according to claim 5 or 6 , which is a film. A copper clad laminate comprising the molded article of claim 7 which is a film.