JP7207281B2 - UV curable silicone composition and its cured product - Google Patents

Description

The present invention relates to an ultraviolet curable silicone composition and its cured product.

Silicone rubber has excellent heat resistance, cold resistance, and electrical insulation properties, and is widely used in various industries such as electrical/electronics, automobiles, and construction.
Among them, liquid silicone rubber compositions have good fluidity and can be reversed with good dimensional reproducibility from a master mold having a fine pattern, so they have been attracting attention as mold materials for nanoimprints.
Addition reaction curing type liquid silicone rubber compositions are mainly used as silicone mold materials for nanoimprints. There is a problem such that the dimension of the predetermined pattern cannot be transferred or printed with high precision due to expansion or contraction due to the pressure.

In this regard, in order to suppress expansion and contraction due to heating and cooling, a material has been proposed that initiates an addition reaction at room temperature without being heated by irradiation with ultraviolet rays (Patent Document 1).
However, the UV addition curable material requires a long time for complete curing, which results in a long processing time, which poses a problem in terms of mass productivity. Therefore, it is desired to develop a silicone molding material that cures rapidly at room temperature.

Also, the silicone rubber composition is generally supplied in the form of a composition containing a highly polymerized organopolysiloxane and a reinforcing resin.
This composition is prepared by mixing a raw material polymer with a reinforcing resin and various dispersants using a mixing device such as a universal mixer or kneader. Organopolysiloxanes and reinforcing resins usually have a methyl group as a side chain group of the siloxane skeleton, and the silicone rubber composition obtained by blending them and the cured silicone rubber thereof are photocurable. It has the property of swelling with solvents contained in resins, inks, and the like. In reversal of a fine pattern during nanoimprinting using a photocurable resin, there is a problem that a pattern of a predetermined size cannot be transferred or printed due to this swelling.

As a means of suppressing the solvent swelling of silicone rubber, the use of fluorosilicone rubber has been proposed (Patent Document 2). The problem is that it cannot be used.
Therefore, there is a strong demand for the development of a silicone molding material that cures quickly at room temperature, has sufficient strength to be used alone, and suppresses solvent swelling.

Japanese Patent No. 6020740 Japanese Unexamined Patent Application Publication No. 2011-042068

The present invention has been made in view of the above circumstances, and provides a UV-curable silicone composition that cures rapidly at room temperature when exposed to UV light, that the cured product has sufficient strength, and that swells less with organic solvents. The purpose is to provide goods.

As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors have found that certain organopolysiloxanes having reactive double bonds such as silicone acryloyloxyalkyl groups in side chains, certain silicones having reactive double bonds, It was found that a composition containing a resin and a photoinitiator cures rapidly at room temperature when irradiated with ultraviolet rays, and that the cured product has sufficient strength and is less likely to swell due to organic solvents. completed.

（式中、Ｒ¹およびＲ²は、それぞれ独立して、炭素原子数１～１０のアルキル基、炭素原子数２～１０のアルケニル基、炭素原子数６～１０のアリール基、アクリロイルオキシ基、メタクリロイルオキシ基、アクリロイルオキシアルキル基、メタクリロイルオキシアルキル基、アクリロイルオキシアルキルオキシ基、またはメタクリロイルオキシアルキルオキシ基を表すが、Ｒ¹の少なくとも１つはアクリロイルオキシ基、メタクリロイルオキシ基、アクリロイルオキシアルキル基、メタクリロイルオキシアルキル基、アクリロイルオキシアルキルオキシ基、およびメタクリロイルオキシアルキルオキシ基より選ばれる基であり、ｍは、１≦ｍ≦１，０００を満たす数を表す。）
（Ｂ）（ａ）下記一般式（２）で示される単位、（ｂ）Ｒ² ₃ＳｉＯ_1/2単位、（ｃ）ＳｉＯ_4/2単位からなり、（ｃ）単位に対する（ａ）単位および（ｂ）単位の合計のモル比が０．４～１．２：１の範囲にあるシリコーンレジン：１～１，０００質量部、および

（式中、Ｒ²は、前記と同じ意味を表す。Ｒ³は、それぞれ独立して、アクリロイルオキシアルキル基、メタクリロイルオキシアルキル基、アクリロイルオキシアルキルオキシ基、またはメタクリロイルオキシアルキルオキシ基を表し、Ｒ⁴は、酸素原子、炭素原子数１～１０のアルキレン基または炭素原子数６～１０のアリーレン基を表し、ｐは、０≦ｐ≦１０を満たす数を表し、ａは、１≦ａ≦３を満たす数を表す。）
（Ｃ）光重合開始剤：０．０１～２０質量部
を含有することを特徴とする紫外線硬化性シリコーン組成物、
２． 前記ｍが、１０≦ｍ≦５００を満たす数である１の紫外線硬化性シリコーン組成物、
３． 前記Ｒ²が、炭素原子数１～１０のアルキル基である１または２の紫外線硬化性シリコーン組成物、
４． １～３のいずれかの紫外線硬化型シリコーン組成物の硬化物、
５． 硬さがＴｙｐｅＤで５５以上であり、かつ、引張強さが４．０ＭＰａ以上である４の硬化物、
６． 有機溶剤に５分間浸漬した際の重量増加率が２．０％以下である４または５の硬化物
を提供する。 That is, the present invention
1. (A) organopolysiloxane represented by the following general formula (1): 100 parts by mass;

(wherein R ¹ and R ² are each independently an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an acryloyloxy group, represents a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group, an acryloyloxyalkyloxy group, or a methacryloyloxyalkyloxy group, but at least one of R ¹ is an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, A group selected from a methacryloyloxyalkyl group, an acryloyloxyalkyloxy group, and a methacryloyloxyalkyloxy group, and m represents a number that satisfies 1≤m≤1,000.)
(B) consists of (a) units represented by the following general formula (2), (b) R ² ₃ SiO _1/2 units, and (c) SiO _4/2 units, and (a) units for (c) units and (b) 1 to 1,000 parts by mass of a silicone resin having a total molar ratio of units in the range of 0.4 to 1.2:1, and

(In the formula, R ² has the same meaning as above. R ³ each independently represents an acryloyloxyalkyl group, a methacryloyloxyalkyl group, an acryloyloxyalkyloxy group, or a methacryloyloxyalkyloxy group, and R ⁴ represents an oxygen atom, an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, p represents a number satisfying 0≦p≦10, and a represents 1≦a≦3 represents a number that satisfies
(C) a photopolymerization initiator: an ultraviolet curable silicone composition characterized by containing 0.01 to 20 parts by mass;
2. 1. The UV-curable silicone composition of 1, wherein m is a number that satisfies 10≦m≦500;
3. 1 or 2 UV-curable silicone compositions, wherein R ² is an alkyl group having 1 to 10 carbon atoms;
4. A cured product of the ultraviolet curable silicone composition according to any one of 1 to 3,
5. Cured product of 4 having a hardness of 55 or more in Type D and a tensile strength of 4.0 MPa or more,
6. Provided is a cured product of 4 or 5 having a weight increase rate of 2.0% or less when immersed in an organic solvent for 5 minutes.

The UV-curable silicone composition of the present invention has curability that cures rapidly at room temperature, and the cured product thereof has sufficient strength as a molding material, and swellability with organic solvents is suppressed.
The UV-curable silicone composition of the present invention having such properties is particularly suitable as a silicone mold material for nanoimprints.

The present invention will be specifically described below.
The UV-curable silicone composition according to the present invention contains the following components (A) to (C).

[1] Component (A) Component (A) in the ultraviolet-curable silicone composition of the present invention is an organopolysiloxane represented by the following general formula (1).

In formula (1), R ¹ and R ² each independently represent an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, acryloyloxy methacryloyloxy, acryloyloxyalkyl, methacryloyloxyalkyl, acryloyloxyalkyloxy, or methacryloyloxyalkyloxy, wherein at least one of R ¹ is acryloyloxy, methacryloyloxy, acryloyloxyalkyl represents a polymerizable group selected from a group, a methacryloyloxyalkyl group, an acryloyloxyalkyloxy group, and a methacryloyloxyalkyloxy group.

The alkyl group having 1 to 10 carbon atoms for R ¹ and R ² may be linear, branched or cyclic, and specific examples thereof include methyl, ethyl, n-propyl, n-butyl and n-pentyl. , n-hexyl and n-octyl groups.
The alkenyl group having 2 to 10 carbon atoms may be linear, branched or cyclic, and specific examples thereof include vinyl, allyl (2-propenyl), 1-butenyl and 1-octenyl groups.
Specific examples of aryl groups having 6 to 10 carbon atoms include phenyl and naphthyl groups.
Some or all of the hydrogen atoms in these groups may be substituted with halogen atoms (eg, chlorine, bromine, and fluorine atoms).

The alkyl (alkylene) group in the acryloyloxyalkyl group, methacryloyloxyalkyl group, acryloyloxyalkyloxy group, and methacryloyloxyalkyloxy group of R ¹ is not particularly limited, but methylene, ethylene, trimethylene, Alkylene having 1 to 10 carbon atoms such as propylene, tetramethylene, pentamethylene, hexamethylene is preferred, alkylene having 1 to 5 carbon atoms is more preferred, and ethylene or trimethylene is even more preferred.

Among these, R ¹ is preferably an alkyl group having 1 to 10 carbon atoms or the above polymerizable group, more preferably an alkyl group having 1 to 5 carbon atoms or the above polymerizable group, a methyl group, an acryloyloxyalkyl group , or methacryloyloxyalkyl groups are even more preferred.
R ² is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and even more preferably a methyl group.

m is a number that satisfies 1≦m≦1,000, preferably 5≦m≦800, and more preferably a number that satisfies 10≦m≦500. If m is less than 1, the organopolysiloxane is likely to volatilize, and if m is greater than 1,000, the viscosity of the composition increases, resulting in poor handleability.

Specific examples of the (A) component organopolysiloxane include the following compounds, but are not limited thereto. In the following formula, Me represents a methyl group (same below).

（式中、括弧が付されたシロキサン単位の配列は任意である。）

(In the formula, the arrangement of the bracketed siloxane units is arbitrary.)

Such an organopolysiloxane can be obtained, for example, by a hydrosilylation reaction between an Si—H group of a trimethylsilyl-terminated dimethylsiloxane/methylhydrogensiloxane copolymer and an allyl group of allyl (meth)acrylate.
The organopolysiloxane of component (A) may be used alone or in combination of two or more.

[2] Component (B) The silicone resin as component (B) consists of (a) units represented by the following general formula (2) (MA units), (b) R ² ₃ SiO _1/2 units (M units), (c) A silicone resin containing (meth)acryloyloxy-containing groups consisting of SiO _4/2 units (Q units) as structural units.

In formula (2), R ² has the same meaning as above, but is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and even more preferably a methyl group.
Each R ³ independently represents an acryloyloxyalkyl group, a methacryloyloxyalkyl group, an acryloyloxyalkyloxy group, or a methacryloyloxyalkyloxy group.

R ⁴ represents an oxygen atom, an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms.
The alkylene group having 1 to 10 carbon atoms for R ⁴ may be linear, branched, or cyclic, and specific examples include methylene, ethylene, trimethylene, hexamethylene, cyclohexylene, octamethylene groups, and the like. .
Specific examples of arylene groups having 6 to 10 carbon atoms include 1,2-phenylene, 1,3-phenylene, 1,4-phenylene and naphthylene groups.
Among these, R ⁴ is preferably an oxygen atom, an ethylene group, a trimethylene group, or a 1,4-phenylene group.
p represents a number that satisfies 0≦p≦10, and a represents a number that satisfies 1≦a≦3.

In component (B), (a) units represented by the general formula ( _{2) (MA units), (b) R 13 SiO 1/2} ^units ₍ M units), and (c) SiO _4/2 The molar ratio of units (Q units) is [MA units+M units]/[Q units]=0.4 to 1.2. When this molar ratio is less than 0.4, the viscosity of the composition becomes very high, and when it exceeds 1.2, the mechanical properties of the cured product may deteriorate.
Considering the viscosity of the composition and the mechanical properties of the cured product in a more appropriate range, the molar ratio of [MA units+M units]/[Q units] is preferably 0.6 to 1.2.
Also, the rubber physical properties of the cured product can be adjusted by the molar ratio of MA units and M units. Considering the strength of the material, the MA unit:M unit ratio is preferably 0.01 to 1:1, more preferably 0.05 to 0.5:1.
Furthermore, the content of (c) SiO _4/2 (Q units) is preferably 5 mol % or more, more preferably 10 to 95 mol %, and even more preferably 10 to 95 mol % of the total siloxane units in the silicone resin of component (B). is 20 to 60 mol %.

Component (B) preferably has a weight average molecular weight in the range of 500 to 100,000 from the standpoint of isolation and purification. The weight average molecular weight is a polystyrene-equivalent value obtained by gel permeation chromatography (solvent THF).
Such a silicone resin can be produced by a known method. For example, alkoxysilane compounds serving as respective unit sources are combined so that the resulting units are in a required ratio, and (co)polymerized in the presence of an acid. It can be produced by hydrolytic condensation.

Specific examples of component (B) include siloxane units represented by the following formula: Me ₂ ViSiO _1/2 units (Vi represents a vinyl group; the same shall apply hereinafter): Me ₃ SiO _1/2 units: SiO ₂ units and a silicone resin having a molar ratio of 0.14:0.03:0.67:1.00.

Component (B) is added in an amount of 1 to 1,000 parts by mass, preferably 5 to 500 parts by mass, more preferably 10 to 200 parts by mass, per 100 parts by mass of component (A). If the amount of component (B) is less than 1 part by mass, the desired curability may not be obtained. Difficult to handle.
In addition, (B) component may be used individually by 1 type, or may use 2 or more types together.

[3] Component (C) Specific examples of the photopolymerization initiator of component (C) include 2,2-diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one (IGM Resins B V., Omnirad 651), 1-hydroxy-cyclohexyl-phenyl-ketone (IGM Resins B.V., Omnirad 184), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (IGM Resins B.V., Omnirad 1173), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propane- 1-one (IGM Resins B.V., Omnirad 127), phenylglyoxylic acid methyl ester (IGM Resins B.V., Omnirad MBF), 2-methyl-1-[4-(methylthio) Phenyl]-2-morpholinopropan-1-one (IGM Resins B.V., Omnirad 907), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone (IGM Resins B.V., Omnirad 369), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (IGM Resins B.V., Omnirad 819), 2,4,6-trimethylbenzoyl -diphenyl-phosphine oxide (OMNIRAD TPO, manufactured by IGM Resins B.V.) and the like, and these may be used alone or in combination of two or more.

Among these, from the viewpoint of compatibility with component (A), 2,2-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, bis(2,4,6- trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide are preferred.

The amount of the photopolymerization initiator added is in the range of 0.01 to 20 parts by weight per 100 parts by weight of component (A). If it is less than 0.01 parts by mass, the curability will be insufficient, and if it exceeds 20 parts by mass, the deep part curability will deteriorate.

[4] Other Components The UV-curable silicone composition of the present invention contains, in addition to the above essential components (A) to (C), reinforcement, viscosity adjustment, improved heat resistance, improved flame retardancy, etc., as necessary. Fillers such as titanium oxide, iron oxide, aluminum oxide, calcium carbonate, and magnesium carbonate for the purpose; Additives such as silane coupling agents, polymerization inhibitors, antioxidants, and light stabilizers can be added. . The composition of the present invention can also be used by appropriately mixing with other resin compositions.

The UV-curable silicone composition of the present invention can be produced by mixing and stirring the above components (A) to (C) and other optional components.
The device used for the operation such as stirring is not particularly limited, but a grinder, three rolls, a ball mill, a planetary mixer and the like can be used. Also, these devices may be combined as appropriate.

The UV-curable silicone composition of the present invention cures rapidly when exposed to UV rays. In this case, the ultraviolet light source for irradiation includes, for example, a UVLED lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, a carbon arc lamp, and a xenon lamp.
The irradiation dose (accumulated light dose) of ultraviolet rays is, for example, preferably 1 to 10,000 mJ/cm ² , more preferably 10 to 10,000 mJ/cm 2 with respect to a sheet formed by molding the composition of the present invention to a thickness of about 2.0 mm. 6,000 mJ/cm ² . That is, when ultraviolet rays with an illuminance of 100 mW/cm ² are used, the ultraviolet rays may be irradiated for about 0.01 to 100 seconds.

The Type D hardness of the cured product made from the ultraviolet-curable silicone composition of the present invention is preferably 50 or higher, more preferably 55 or higher.
Furthermore, the tensile strength of the cured product is preferably 3.0 MPa or more, more preferably 4.0 MPa or more.

Further, the weight increase rate when the cured product of the present invention molded with a thickness of 1 mm is immersed in an organic solvent is preferably 2.0% or less, more preferably 1.5% or less.
Here, the organic solvent includes hydrocarbon-based solvents such as hexane and heptane; aromatic hydrocarbon-based solvents such as toluene and xylene; and acetic ester-based solvents such as ethyl acetate and propylene glycol monomethyl ether acetate (hereinafter referred to as PGMEA). is mentioned.
In particular, it is preferable that the weight increase is suppressed when immersed in PGMEA, which is often used as a solvent for photocurable resins and inks.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
In the following, Vi represents a vinyl group, Me represents a methyl group, and Ph represents a phenyl group.

[1] Production of UV-curable silicone composition [Examples 1-3, Comparative Examples 1-2]
The above components (A) and (B) were mixed with the composition shown in Table 1 (the numerical values represent parts by mass), and toluene was distilled off at 100°C under reduced pressure. A curable silicone composition was prepared.

（式中、括弧が付されたシロキサン単位の配列は任意である。） (A) Component (A-1): Organopolysiloxane represented by the following formula

(In the formula, the arrangement of the bracketed siloxane units is arbitrary.)

（式中、括弧が付されたシロキサン単位の配列は任意である。） (A-2): Organopolysiloxane represented by the following formula

(In the formula, the arrangement of the bracketed siloxane units is arbitrary.)

（式中、Ｐｈはフェニル基を表し、括弧が付されたシロキサン単位の配列は任意である。） (A-3): Organopolysiloxane represented by the following formula

(In the formula, Ph represents a phenyl group, and the arrangement of parenthesized siloxane units is arbitrary.)

(A-4): Organopolysiloxane represented by the following formula

Component (B) (B-1) The molar ratio of siloxane units represented by the following formula: Me ₂ ViSiO _1/2 units: Me ₃ SiO _1/2 units: SiO ₂ units is 0.14:0.03:0. .67:1.00 silicone resin (number average molecular weight 5,700) in 50 wt% xylene solution

(C) Component (C-1) 2-hydroxy-2-methyl-1-phenyl-propan-1-one (manufactured by IGM Resins B.V., Omnirad 1173)

The viscosity at 23° C. of each composition prepared in Examples 1-3 and Comparative Examples 1-2 was measured with a rotational viscometer.
Further, each of the above compositions was poured into a frame, molded into a sheet with a thickness of 2.0 mm, and using an eye UV electronic control device (model UBX0601-01) manufactured by Eye Graphic Co., Ltd., under a nitrogen atmosphere at 25 ° C. , UV light having a wavelength of 365 nm was applied at an irradiation intensity of 100 mW/cm ² for 40 seconds, ie, the cumulative amount of light was 4,000 mJ/cm ² for curing.
The hardness, tensile strength, and density of the obtained 2.0 mm thick cured product were measured according to JIS K 6251:2010.
Furthermore, the weight increase rate after immersion in an organic solvent was measured by the following method for a 1 mm-thick cured product prepared in the same manner.
The cured product was immersed in PGMEA for 5 minutes, then naturally dried at 23° C. for 5 minutes, and the weight increase rate before and after immersion in PGMEA was determined. These results are shown in Table 2.

As shown in Table 2, the UV-curable silicone compositions prepared in Examples 1 to 3 can be rapidly cured at room temperature by UV irradiation to give cured products having a tensile strength of 4.0 MPa or more. Understand. In addition, it can be seen that the weight change rate is small when the cured product is immersed in an organic solvent.
On the other hand, it can be seen that the compositions prepared in Comparative Examples 1 and 2 have weak tensile strength and undergo large weight changes due to the solvent.

Claims (6)

(A) organopolysiloxane represented by the following general formula (1): 100 parts by mass;

(wherein R ¹ and R ² are each independently an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an acryloyloxy group, represents a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group, an acryloyloxyalkyloxy group, or a methacryloyloxyalkyloxy group, but at least one of R ¹ is an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, A group selected from a methacryloyloxyalkyl group, an acryloyloxyalkyloxy group, and a methacryloyloxyalkyloxy group, and m represents a number that satisfies 1≤m≤1,000.)
(B) consists of (a) units represented by the following general formula (2), (b) R ² ₃ SiO _1/2 units, and (c) SiO _4/2 units, and (a) units for (c) units and (b) 1 to 1,000 parts by mass of a silicone resin having a total molar ratio of units in the range of 0.4 to 1.2:1, and

(In the formula, R ² has the same meaning as above. R ³ each independently represents an acryloyloxyalkyl group, a methacryloyloxyalkyl group, an acryloyloxyalkyloxy group, or a methacryloyloxyalkyloxy group, and R ⁴ represents an oxygen atom, an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, p represents a number satisfying 0≦p≦10, and a represents 1≦a≦3 represents a number that satisfies
(C) Photopolymerization initiator: An ultraviolet curable silicone composition characterized by containing 0.01 to 20 parts by mass. 2. The UV-curable silicone composition according to claim 1, wherein m is a number satisfying 10≤m≤500. 3. The UV-curable silicone composition according to claim 1, wherein R ² is an alkyl group having 1 to 10 carbon atoms. A cured product of the ultraviolet curable silicone composition according to any one of claims 1 to 3. 5. The cured product according to claim 4, which has a Type D hardness of 55 or more and a tensile strength of 4.0 MPa or more. 6. The cured product according to claim 4 or 5, which has a weight increase rate of 2.0% or less when immersed in propylene glycol monomethyl ether acetate for 5 minutes.