US-12617941-B2 - Heat-curable resin composition

Abstract

Provided is a heat-curable resin composition capable of lowering the elastic modulus of a cured product obtained even when a heat-curable resin component in the composition contains an organic solvent or has a high curing temperature. The heat-curable resin composition contains: (A) a heat-curable resin; and (B) spherical polymethylphenyl silsesquioxane particles that have a volume average particle size of 0.1 to 30 μm, and are in an amount of 1 to 35 parts by mass per 100 parts by mass of the component (A), wherein a molar ratio between units represented by CH 3 SiO 3/2 and units represented by C 6 H 5 SiO 3/2 (CH 3 SiO 3/2 units:C 6 H 5 SiO 3/2 units) in the polymethylphenyl silsesquioxane particles is 95:5 to 55:45.

Inventors

• Yoshinori Inokuchi

Assignees

• SHIN-ETSU CHEMICAL CO., LTD.

Dates

Publication Date

20260505

Application Date

20211119

Priority Date

20201127

Claims (9)

1. 1 . A heat-curable resin composition comprising: (A) a heat-curable resin; and (B) spherical polymethylphenyl silsesquioxane particles that have a volume average particle size of 0.1 to 30 μm, and are in an amount of 1 to 35 parts by mass per 100 parts by mass of the component (A), wherein a molar ratio between units represented by CH 3 SiO 3/2 and units represented by C 6 H 5 SiO 3/2 (CH 3 SiO 3/2 units:C 6 H 5 SiO 3/2 units) in the polymethylphenyl silsesquioxane particles is 95:5 to 55:45, the heat-curable resin as the component (A) is at least one selected from an epoxy resin, a phenolic resin, a cyanate resin and a maleimide resin, and the component (B) causes a cured product of the heat-curable resin composition to lower the elastic modulus of the cured product.
2. 2 . The heat-curable resin composition according to claim 1 , wherein the component (B) consists of the units represented by CH 3 SiO 3/2 and the units represented by C 6 H 5 SiO 3/2 .
3. 3 . The heat-curable resin composition according to claim 1 , wherein the spherical polymethylphenyl silsesquioxane particles as the component (B) have a thermal decomposition temperature of not lower than 400° C. when measured by a thermogravimetric measurement device under an air atmosphere and at a temperature rising rate of 10° C./min.
4. 4 . A cured product of the heat-curable resin composition according to claim 1 .
5. 5 . A method for lowering an elastic modulus of a cured product, comprising curing the heat-curable resin composition according to claim 1 , and thereby lowering the elastic modulus of the cured product by the component (B).
6. 6 . A cured product of the heat-curable resin composition according to claim 2 .
7. 7 . A method for lowering an elastic modulus of a cured product, comprising curing the heat-curable resin composition according to claim 2 , and thereby lowering the elastic modulus of the cured product by the component (B).
8. 8 . A cured product of the heat-curable resin composition according to claim 3 .
9. 9 . A method for lowering an elastic modulus of a cured product, comprising curing the heat-curable resin composition according to claim 3 , and thereby lowering the elastic modulus of the cured product by the component (B).

Description

TECHNICAL FIELD The present invention relates to a heat-curable resin composition, particularly to a heat-curable resin composition that is suitable for use in a packaging agent for an electronic or electric part and in a printed-wiring board. BACKGROUND ART In recent years, electronic devices such as cell phones, smartphones, ultrathin liquid crystal TVs and light-weight laptop computers are becoming smaller. In this regard, the electronic parts used in these devices are now, for example, integrated and packaged at higher densities. Further, a resin material used in these electronic parts is required to possess a lower elastic modulus so that breakage shall not occur due to a stress caused by thermal expansion of the electronic parts. Also, in the case of a printed-wiring board used in mobile devices, it is required that the resin material be one having a low elastic modulus so that breakage shall not occur due to a dropping impact. It has been disclosed that by adding silicone rubber particles to an epoxy resin composition, the elastic modulus of a cured product of such composition can be lowered, and the stress thereof can thus be lowered as well (Patent document 1). However, if a heat-curable resin component therein contains an organic solvent, there is a problem that an unfavorable moldability will be observed as the silicone rubber particles shall swell due to the organic solvent. Further, it is not feasible when the curing temperature of the heat-curable resin component is higher than the decomposition temperature of the silicone rubber particles. Meanwhile, there is disclosed an epoxy resin composition containing polyorganosilsesquioxane particles whose structural formula is expressed as RSiO3/2 (R is an organic substituent group) (Patent document 2). The polymethyl silsesquioxane particles exemplified in Patent document 2 and whose structural formula is expressed as CH3SiO3/2 do not swell due to an organic solvent and have a decomposition temperature higher than that of silicone rubber particles; however, such polymethyl silsesquioxane particles have a low performance for reducing the stress of a resin. The polyphenyl silsesquioxane particles exemplified in Patent document 2 and whose structural formula is expressed as C6H5SiO3/2 have a decomposition temperature higher than that of silicone rubber particles, but are soluble in an organic solvent. The polymethylphenyl silsesquioxane particles that are exemplified in Patent document 2 and are composed of units represented by CH3SiO3/2 and units represented by C6H5SiO3/2 with a molar ratio between the CH3SiO3/2 and C6H5SiO3/2 units being 1:1, do not swell due to an organic solvent, have a decomposition temperature higher than that of silicone rubber particles, and exhibit a performance for reducing the stress of a resin. However, due to a high agglomeration property thereof, such particles have, for example, a problem that they will adhere to the wall of a production device by a large amount; and a problem that they have a poor dispersibility in a resin. PRIOR ART DOCUMENTS Patent Documents Patent document 1: JP-A-2013-104029Patent document 2: JP-A-Sho 61-160955 SUMMARY OF THE INVENTION Problems to be Solved by the Invention Thus, it is an object of the present invention to provide a heat-curable resin composition capable of lowering the elastic modulus of a cured product obtained even when a heat-curable resin component in the composition contains an organic solvent or has a high curing temperature. Means to Solve the Problems The inventor of the present invention diligently conducted a series of studies to achieve the above object, and completed the invention as follows. That is, the inventor found that the heat-curable resin composition shown below was able to achieve the above object when using particular polymethylphenyl silsesquioxane particles having a low agglomeration property. [1] A heat-curable resin composition comprising: (A) a heat-curable resin; and(B) spherical polymethylphenyl silsesquioxane particles that have a volume average particle size of 0.1 to 30 μm, and are in an amount of 1 to 35 parts by mass per 100 parts by mass of the component (A),wherein a molar ratio between units represented by CH3SiO3/2 and units represented by C6H5SiO3/2 (CH3SiO3/2 units:C6H5SiO3/2 units) in the polymethylphenyl silsesquioxane particles is 95:5 to 55:45. [2] The heat-curable resin composition according to [1], comprising: (A) the heat-curable resin; and(B) the spherical polymethylphenyl silsesquioxane particles that have the volume average particle size of 0.1 to 30 μm, and are in the amount of 1 to 35 parts by mass per 100 parts by mass of the component (A),wherein the polymethylphenyl silsesquioxane particles are composed of the units represented by CH3SiO3/2 and the units represented by C6H5SiO3/2, and the molar ratio between the CH3SiO3/2 units and the C6H5SiO3/2 units (CH3SiO3/2 units:C6H5SiO3/2 units) is 95:5 to 55:45. [3] The heat-curable