JP4772858B2 - Silicone resin composition - Google Patents

Description

  The present invention relates to a silicone resin composition. More specifically, the present invention relates to a silicone resin composition having excellent transparency, high adhesiveness and tensile shear strength, and excellent heat resistance, a method for producing the same, and a transparent pressure-sensitive adhesive sheet of the composition.

  Silicone-based pressure-sensitive adhesives are widely used for electronic parts because they exhibit good moisture resistance and electrical insulation. With the recent miniaturization and increase in capacity of electronic devices, the manufacturing process becomes complicated, and therefore further improvement in the quality of silicone-based pressure-sensitive adhesives is required.

  Conventionally, as the silicone-based adhesive, a tacky addition-crosslinking silicone composition or a silicone elastomer derived therefrom is used. However, since silicone derived from pure siloxane does not have sufficient adhesiveness, a method of organically modifying a resin by introducing a functional group such as an epoxy group, an amino group, or a mercapto group, or an additive having the functional group In general, a method of performing primer treatment using a pesticide is performed (see Patent Document 1).

  Patent Document 2 discloses a silicone composition having a low coefficient of thermal expansion and high adhesion by adding silica particles having a small specific surface area. In patent document 3, adhesiveness is improved by using processing aids, such as a plasticizer.

On the other hand, a silicone adhesive derived from a polyorganosiloxane raw rubber, a crosslinkable polyalkoxysilane, or the like without performing the organic modification as described above has been proposed as an adhesive with improved heat resistance (see Patent Document 4). ).
Japanese Patent Laid-Open No. 2001-200162 JP 2000-265150 A JP 2005-513195 A JP-T-2004-502021

  However, although functional groups such as epoxy groups and amino groups have excellent adhesion to the substrate, their heat resistance is insufficient, and when exposed to a high temperature of 150 ° C or higher for a long time, the adhesive force decreases or discolors. . Moreover, in the method of patent document 2, since the silica particle to add is large and dispersibility is not enough, what is inferior to transparency is obtained. Even when a processing aid is used according to Patent Document 3, it is possible to improve the adhesion, but the heat resistance is not sufficient, and when exposed to a high temperature for a long time, the adhesive force is reduced or discolored. Occurs.

  Moreover, although the silicone adhesive proposed by patent document 4 is excellent in heat resistance, adhesive strength is not yet enough, and the further improvement is calculated | required.

  An object of the present invention is to provide a silicone resin composition having excellent transparency, high adhesion and tensile shear strength, and excellent heat resistance, a method for producing the same, and a transparent pressure-sensitive adhesive sheet of the composition There is to do.

  As a result of repeated studies to solve the above problems, the present inventors have obtained metal oxide fine particles having reactive functional groups on the surface of the fine particles as fillers, and a part of alkoxysilyl groups contained in the silicone resin raw material. By reacting and cross-linking, the fine particles are well dispersed to maintain transparency, while increasing the resin strength, and by using a specific silane derivative as the silicone resin raw material, the polycondensation reaction between the raw materials It has been found that the flexibility of the silicone obtained by the method is improved, the adhesiveness with the base material is improved without introducing an organic functional group, and further the heat resistance is improved, and the present invention has been completed. .

That is, the present invention
[1] A polymer obtained by polymerizing a metal oxide fine particle having a reactive functional group on the surface of a fine particle and a polymethylsilsesquioxane derivative having an alkoxysilyl group at the molecular end is represented by the formula (II):

(Wherein X represents an alkoxy group or a halogen atom)
A silicone resin composition obtained by polymerizing a monofunctional silane derivative represented by
[2] A step of polymerizing a metal oxide fine particle having a reactive functional group on the surface of the fine particle and a polymethylsilsesquioxane derivative having an alkoxysilyl group at the molecular end, and a polymer obtained in the step And formula (II):

(Wherein X represents an alkoxy group or a halogen atom)
And a method for producing a silicone resin composition according to [1] above, and a step of molding the silicone resin composition according to [1]. The present invention relates to a silicone-based transparent pressure-sensitive adhesive sheet.

  The silicone resin composition of the present invention has excellent effects of being excellent in transparency, having high adhesiveness and tensile shear strength, and being excellent in heat resistance.

  The silicone resin composition of the present invention comprises a polymer obtained by polymerizing a metal oxide fine particle having a reactive functional group on the fine particle surface and a polymethylsilsesquioxane derivative having an alkoxysilyl group at the molecular end. (II):

(Wherein X represents an alkoxy group or a halogen atom)
It has the big characteristic in carrying out the polymerization reaction of the specific monofunctional silane derivative represented by these.

  Since the polymethylsilsesquioxane derivative becomes a condensed structure having a high crosslinking density, it is difficult to obtain a polymethylsilsesquioxane derivative having a large molecular weight. In the present invention, a polymethylsilsesquioxane derivative is obtained by polymerizing a metal oxide fine particle having a reactive functional group on the surface of a fine particle with a polymethylsilsesquioxane derivative having a reactive alkoxysilyl group at the molecular end. A part of the alkoxysilyl group and a part of the surface functional group of the metal oxide fine particles are cross-linked by an interaction such as a covalent bond or a hydrogen bond, so that the metal oxide fine particles are well dispersed and have transparency. While maintaining high molecular weight as the whole resin while maintaining, it is possible to have high strength that is excellent in properties such as mechanical strength, toughness, wear resistance, and scratch resistance.

  Furthermore, after the cross-linking reaction between the polymethylsilsesquioxane derivative and the metal oxide fine particles, an unreacted alkoxysilyl group in the polymethylsilsesquioxane derivative is blocked with the specific monofunctional silane derivative, that is, The polymer obtained by the crosslinking reaction and the monofunctional alkoxysilane can be polycondensed to adjust the degree of crosslinking of the resin, so that the heat resistance can be improved and the transparency is excellent. A silicone resin composition having high strength and excellent heat resistance can be obtained. In addition, the composition of the present invention does not have tack (adhesiveness) at room temperature, so that it is excellent in handleability. When heated, the tack develops and exhibits high adhesiveness.

  The polymethylsilsesquioxane derivative is a general term for silicone resins having a ratio of the number of oxygen atoms to the number of silicon atoms of 1.5, and is a polymethylsilsesquioxane derivative having an alkoxysilyl group at the molecular end (hereinafter referred to as the following). As the polymethylsilsesquioxane derivative), for example, the following formula (I):

(In the formula, R ¹ , R ² , R ³ and R ⁴ each independently represents a hydrogen atom, an alkyl group or an aromatic group, and n represents a positive integer, provided that R ¹ , R ² and R ⁴ is not a hydrogen atom, and is not an aromatic group, and n R ^{3 s} may be the same or different.
The compound which has the compound represented by these as a structural unit is mentioned. Note that the structural unit is subjected to condensation polymerization to be a compound having a random structure of a Si—O—Si skeleton, a ladder structure, a cage structure, or the like.

R ¹ , R ² , R ³ and R ^{4 in} formula (I) each independently represent a hydrogen atom, an alkyl group or an aromatic group, provided that R ¹ , R ² and R ⁴ are both hydrogen. It is not an atom and both are not aromatic groups, and n R ^{3 s} may be the same or different. That is, at least one of R ¹ , R ² and R ⁴ is an alkyl group.

The carbon number of the alkyl group of R ¹ , R ² , R ³ and R ^{4 in} the formula (I) is preferably 1 to 4 and more preferably 1 to 2 from the viewpoint of the reactivity on the fine particle surface and the hydrolysis rate. preferable. Specifically, a methyl group, an ethyl group, a propyl group, etc. are illustrated. Of these, a methyl group is preferable, and all of OR ¹ , OR ² , OR ^3, and OR ⁴ are preferably methoxy groups. It is preferable also all the n OR ³ are methoxy group.

  N in the formula (I) represents a positive integer, and is preferably an integer of 1 to 3 from the viewpoint of solubility in a solvent.

Examples of the polymethylsilsesquioxane derivative represented by the formula (I) include a compound having a Si—O—Si skeleton in a random structure (random type), a compound having a ladder structure (ladder type), and a cage structure. Examples include compounds (cage type) and compounds obtained by partial cleavage of the cage type (partially cleaved cage type ) , and these may be used alone or in combination of two or more. Among these, a partial hydrolysis condensate of a polymethylsilsesquioxane derivative in which R ¹ , R ² , R ³ (all n R ^{3 s} ) and R ⁴ are all methyl groups is preferable. In the present specification, the partially hydrolyzed condensate is a product obtained by hydrolyzing and polycondensing a mixture of polymethylsilsesquioxane derivatives having various structures, and the composition is not particularly limited.

  The molecular weight of the polymethylsilsesquioxane derivative in the present invention is preferably 200 to 5000, more preferably 400 to 5000. When two or more types of polymethylsilsesquioxane derivatives are used, the molecular weight of each polymethylsilsesquioxane derivative is preferably within the above range, but some of the polymethylsilsesquioxane derivatives are outside the above range. The weight average molecular weight should just be contained in the said range as molecular weight of the whole polymethylsilsesquioxane derivative. In the present specification, the molecular weight of the silicone derivative is measured by gel filtration chromatography (GPC).

  From the viewpoint of reactivity, the content of the alkoxy group is preferably 10 to 50% by weight, more preferably 20 to 48% by weight, and still more preferably 24 to 46% by weight in one molecule of the polymethylsilsesquioxane derivative. is there. In the present specification, the content of the alkoxy group in one molecule of the polymethylsilsesquioxane derivative can be measured by the method described in Examples described later.

  Further, the silicone resin composition of the present invention has the formula (II): from the viewpoint of developing tack (adhesiveness) under heating.

(Wherein X represents an alkoxy group or a halogen atom)
It is obtained by reacting a monofunctional silane derivative represented by the following (hereinafter also simply referred to as a monofunctional silane derivative).

  X in the formula (II) represents an alkoxy group or a halogen atom, and the number of carbon atoms of the alkyl group in the alkoxy group is preferably 1 to 4 and more preferably 1 to 2 from the viewpoint of reactivity. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group. Specific examples of the halogen atom include fluorine, chlorine, bromine and the like. Of these, chlorine is preferred from the viewpoint of reactivity.

  Examples of the monofunctional silane derivative represented by the formula (II) include methoxytrimethylsilane, chlorotrimethylsilane, and ethoxytrimethylsilane, and these can be used alone or in combination of two or more.

  100-160 are preferable and, as for the molecular weight of the monofunctional silane derivative in this invention, 100-140 are more preferable.

  The content of the polymethylsilsesquioxane derivative having an alkoxysilyl group at the molecular terminal is preferably 60 to 99% by weight, more preferably 70 to 95% by weight, and still more preferably 80 to 90% by weight in the silicone resin composition. %.

  The content of the monofunctional silane derivative represented by the formula (II) is preferably 1 to 40% by weight, more preferably 5 to 30% by weight, and further preferably 10 to 20% by weight in the silicone resin composition. is there.

  The weight ratio of the polymethylsilsesquioxane derivative to the monofunctional silane derivative represented by the formula (II) (polymethylsilsesquioxane / 1 monofunctional silane) is the strength of the molded article. From the viewpoint, 60/40 to 99/1 is preferable, 70/30 to 95/5 is more preferable, and 80/20 to 90/10 is further preferable.

  In the present invention, a silicone derivative other than the polymethylsilsesquioxane derivative and the monofunctional silane derivative may be contained as long as the effects of the present invention are not impaired. Examples of the other silicone derivatives include known silicone derivatives, and the total content of the polymethylsilsesquioxane derivative and monofunctional silane derivative in the silicone derivative is preferably 80% by weight or more, and 90% by weight. Is more preferable, and it is still more preferable that it is substantially 100 weight%.

The metal oxide fine particles having reactive functional groups on the particle surface, titanium oxide, zirconium oxide, barium titanate, zinc oxide, lead titanate, include silicon dioxide, these are alone, or two or more They can be used in combination. Among these, from the viewpoint of high refractive index, at least one selected from the group consisting of titanium oxide, zinc oxide, zirconium oxide, barium titanate, and silicon dioxide is desirable. In addition, as a titanium oxide, you may use any of a rutile type titanium oxide and an anatase type titanium oxide.

Examples of the reactive functional group in the metal oxide fine particle include a hydroxyl group, an isocyanate group, an amino group, a mercapto group, a carboxy group, an epoxy group, a vinyl type unsaturated group, a halogen group, and an isocyanurate group .

  The content of the reactive functional group on the fine particle surface of the metal oxide fine particle can be obtained from the fine particle amount, the surface area of the fine particle, the amount of the surface treatment agent reacted, etc. In the present invention, the reaction amount with the surface treatment agent is Fine particles that are 0.1% by weight or more of the weight of the fine particles are referred to as “metal oxide fine particles having a reactive functional group on the fine particle surface”. Here, the reaction amount is the content of the reactive functional group, and the content in the metal oxide fine particles is not particularly limited as long as it is 0.1% by weight or more. In the present specification, the content of the reactive functional group on the surface of the metal oxide fine particles can be measured by the method of Examples described later, and the “content of the reactive functional group” means the reactive functional group. It means “content” and / or “abundance” of a group.

  In addition, the content of the reactive functional group on the surface of the metal oxide fine particles can be reduced, for example, by reacting the fine particles with a solution obtained by dissolving methyltrimethoxysilane in an organic solvent. Moreover, the amount of reactive functional groups on the surface of the fine particles can be reduced by firing the fine particles at a high temperature.

  As the metal oxide fine particles, those produced by a known method can be used, and among them, hydrothermal synthesis method, sol-gel method, supercritical water from the viewpoint of uniformity of particle size and fine particle formation. Those obtained by at least one production method selected from the group consisting of a thermal synthesis method, a coprecipitation method, and a uniform precipitation method are preferred.

  The average particle diameter of the metal oxide fine particles is preferably 1 to 100 nm, more preferably 1 to 70 nm, and still more preferably 1 to 20 nm, from the viewpoint of transparency when the composition is a molded body. In the present specification, the average particle size of the metal oxide fine particles can be measured by measuring the particle size of the particle dispersion by a dynamic light scattering method or directly observing with a transmission electron microscope.

  The metal oxide fine particles may be prepared in a dispersion from the viewpoint of dispersion stability (also referred to as “metal oxide fine particle dispersion”). Examples of the dispersion medium include water, alcohol, ketone solvents, and acetamide solvents, and it is preferable to use water, methanol, methyl butyl ketone, and dimethylacetamide. The amount (solid content concentration) of the metal oxide fine particles in the dispersion is preferably 10 to 40% by weight, more preferably 15 to 40% by weight, and still more preferably 20 from the viewpoint of efficiently performing the reaction on the surface of the fine particles. ~ 40% by weight. Such metal oxide fine particle dispersions include titanium oxide, NEOSUNVEIL or QUEEN TITANIC series from Catalytic Chemicals, Tynoch from Taki Chemical Co., Ltd., ZSL series from Daiichi Rare Chemicals Co., Ltd. Commercially available products such as the series and the nano-use series of Nissan Chemical Co., Ltd. can be used.

  The content of the metal oxide fine particles is preferably 1 to 80 parts by weight, more preferably 10 parts per 100 parts by weight of the total amount of the polymethylsilsesquioxane derivative and the monofunctional silane derivative represented by the formula (II). It is -70 weight part, More preferably, it is 20-60 weight part.

  In addition to the polymethylsilsesquioxane derivative, the monofunctional silane derivative, and the metal oxide fine particles, the composition for a silicone resin of the present invention includes an antiaging agent and a modifier within the range not impairing the effects of the present invention. In addition, additives such as surfactants, dyes, pigments, anti-discoloring agents, and ultraviolet absorbers may be contained.

  The silicone resin composition of the present invention includes, for example, a monofunctional silane obtained by polymerizing a resin solution containing a polymethylsilsesquioxane derivative with the metal oxide fine particle dispersion at 40 to 80 ° C. It can be prepared by polymerizing the derivative at 40-80 ° C.

  A preferred method for producing the silicone resin composition of the present invention is a step of polymerizing a metal oxide fine particle having a reactive functional group on the surface of the fine particle and a polymethylsilsesquioxane derivative having an alkoxysilyl group at the molecular end [ Step (1)], and a step [step (2)] in which the polymer obtained in step (1) is polymerized with a monofunctional silane derivative represented by formula (II). .

  Specific examples of the step (1) include, for example, a solution obtained by adding an organic solvent such as methanol, ethanol, 2-methoxyethanol, 2-propanol, and tetrahydrofuran to a metal oxide fine particle dispersion and stirring. A resin solution prepared by dissolving a methyl silsesquioxane derivative in an organic solvent such as methanol, ethanol, 2-propanol, tetrahydrofuran or the like to a concentration of preferably 20 to 50% by weight is added dropwise and mixed at 40 to 80 ° C. And a step of reacting for 1 to 3 hours to form a crosslinked structure of the polymethylsilsesquioxane derivative and the metal oxide fine particles. The obtained polymer is subjected to step (2).

  As a specific example of the step (2), for example, the polymer obtained in the step (1) is preferably mixed with a monofunctional silane derivative in an organic solvent such as methanol, ethanol, 2-propanol, tetrahydrofuran, etc. Examples include a step of dropping and mixing a resin solution prepared by dissolving so as to have a concentration of% and reacting at 40 to 80 ° C. for 1 to 3 hours. In addition, the obtained reaction liquid can be used for the process of distilling a solvent off under reduced pressure and concentrating, etc., and can adjust a density | concentration and a viscosity.

  The silicone resin composition thus obtained is applied to an appropriate thickness by a method such as casting, spin coating, roll coating, etc. on a release sheet (for example, a polyethylene substrate) whose surface has been peeled off. Then, it can be formed into a sheet by drying at a temperature at which the solvent can be removed. The temperature at which the resin solution is dried varies depending on the type of resin or solvent and cannot be determined unconditionally, but is preferably 80 to 150 ° C.

  The resin composition of the present invention is highly transparent because of its excellent transparency.For example, when formed into a sheet having a thickness of 10 to 500 μm, the transmittance for incident light having a wavelength of 400 to 700 nm is preferable. Is 80% or more, more preferably 85% or more, and still more preferably 90 to 100%. In the present specification, the light transmittance is measured by the method described in Examples described later.

  In another aspect of the present invention, there is provided a silicone-based pressure-sensitive adhesive sheet which is formed by coating the silicone resin composition of the present invention on a substrate and drying it.

  The silicone-based pressure-sensitive adhesive sheet of the present invention is not particularly limited in form and size, and is suitably used as an interlayer adhesive for substrates, and adhesives for electrical and electronic component materials that require heat resistance and light resistance. be able to.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited at all by these Examples.

[Molecular weight of silicone derivatives]
Obtained in terms of polystyrene by gel filtration chromatography (GPC).

[Alkoxy group content of silicone derivative]
It is calculated from the quantitative value by ¹ H-NMR using an internal standard substance and the weight loss value by differential thermogravimetric analysis.

[Average particle diameter of metal oxide fine particles]
In this specification, the average particle diameter of the metal oxide fine particles means the average particle diameter of the primary particles, and is a volume-median particle calculated by measuring the particle dispersion of the metal oxide fine particles by a dynamic light scattering method. It is the diameter (D ₅₀ ).

[Reactive functional group content on metal oxide fine particle surface]
Add ethyltrimethoxysilane as a surface treating agent to the fine particle dispersion and react, and then coagulate and settle the fine particles by centrifugation or pH fluctuations, collect by filtration, wash and dry, and determine the weight loss by differential thermogravimetric analysis. To calculate the content.

[Light transmittance of silicone resin composition]
Using a spectrophotometer (U-4100, manufactured by Hitachi High-Tech), the transmission spectrum in the visible light region of 400 to 800 nm is measured, and the transmittance at 400 nm is calculated.

Example 1
In a vessel equipped with a stirrer, reflux condenser, and nitrogen introduction tube, an aqueous dispersion of zirconia oxide having a mean particle size of 7 nm as a metal oxide fine particle having a reactive functional group on the fine particle surface (trade name `` NZD-3007 '' , Manufactured by Sumitomo Osaka Cement Co., Ltd., solid content concentration 40% by weight, hydroxyl group as a reactive functional group, reactive functional group content 1.0% by weight or more) 10.0 g (22 parts by weight with respect to 100 parts by weight of silicone derivative) After adding 10.0 g of methanol and 10.0 g of 2-methoxyethanol, the pH of the liquid was adjusted to 2.5 to 3.3 using concentrated hydrochloric acid. There, a polymethylsilsesquioxane derivative having an alkoxysilyl group at the molecular end [trade name “X-40-9225”, manufactured by Shin-Etsu Chemical Co., Ltd., R ¹ , R ² , R ³ and R ^{4 of the} formula (I) Is a methyl group, a molecular weight of 2000 to 3000, a methoxy content of 24% by weight] A solution of 16.0 g dissolved in 16.0 g of 2-propanol was added dropwise using a dropping funnel over 20 minutes and reacted at 60 ° C. for 1 hour. . Thereafter, as a monofunctional silane derivative, methoxytrimethylsilane [trade name “LS-510”, manufactured by Shin-Etsu Chemical Co., Ltd., X in formula (II) is a methoxy group, molecular weight 104.2] 2.5 g [polymethylsilsesquioxane / 1 functional Silane (weight ratio) = 86/14] was added dropwise, reacted at 60 ° C. for 2 hours, and then cooled to room temperature (25 ° C.) to obtain a silicone resin composition of Example 1. The obtained composition was concentrated under reduced pressure by distilling off the solvent, and then applied to a PET substrate having a release treatment with a silicone release agent to a film thickness of 100 μm. By heating for a minute, a silicone-based transparent pressure-sensitive adhesive sheet of the composition of Example 1 was prepared. The obtained adhesive sheet had no tack at room temperature, and was tacky when heated to 60 ° C.

Example 2
In Example 1, instead of using 16.0 g of the polymethylsilsesquioxane derivative (X-40-9225), a polymethylsilsesquioxane derivative [trade name “KR500”, manufactured by Shin-Etsu Chemical Co., Ltd., of formula (I) R ¹ , R ² , R ³ and R ⁴ are methyl groups, molecular weight 1000 to 2000, methoxy content 28% by weight] The silicone resin composition of Example 2 is the same as Example 1 except that 16.0 g is used. And the adhesive sheet was obtained. The obtained adhesive sheet had no tack at room temperature, and was tacky when heated to 60 ° C.

Example 3
In Example 1, instead of using 16.0 g of the polymethylsilsesquioxane derivative (X-40-9225), a polymethylsilsesquioxane derivative [trade name “KC89”, manufactured by Shin-Etsu Chemical Co., Ltd., of formula (I) R ¹ , R ² , R ³ and R ⁴ are methyl groups, molecular weight of about 400, methoxy group content of 46% by weight] The silicone resin composition of Example 3 is the same as Example 1 except that 16.0 g is used. And the adhesive sheet was obtained. The obtained adhesive sheet had no tack at room temperature, and was tacky when heated to 60 ° C.

Example 4
In Example 1, instead of using 2.5 g of monofunctional silane derivative methoxytrimethylsilane (LS-510), chlorotrimethylsilane [trade name “KA31”, manufactured by Shin-Etsu Chemical Co., Ltd., X in formula (II) is chlorine The molecular weight 108.6] The silicone resin composition of Example 4 and its adhesive sheet were obtained in the same manner as in Example 1 except that 2.5 g was used. The obtained adhesive sheet had no tack at room temperature, and was tacky when heated to 60 ° C.

Example 5
In the same apparatus as in Example 1, 25.8 g (silicone derivative) of an aqueous dispersion of silica (trade name “Colloidal Silica O”, manufactured by Nissan Chemical Co., Ltd., solid content concentration 20% by weight, containing a hydroxyl group as a reactive functional group) 22 parts by weight with respect to 100 parts by weight), 20.0 g of methanol and 20.0 g of 2-methoxyethanol were added, and then 20.0 g of polymethylsilsesquioxane derivative (KR500) was added to 24.0 g of 2-propanol. The dissolved solution was dropped using a dropping funnel and reacted at 60 ° C. for 1 hour, and then 3.0 g of methoxytrimethylsilane (LS-510) [polymethylsilsesquioxane / 1 functional silane (weight ratio). ) = 87/13] was dropped using a dropping funnel, reacted at 60 ° C. for 2 hours, and then cooled to room temperature (25 ° C.) to obtain a silicone resin composition of Example 5. The obtained composition was obtained in the same manner as Example 1 to obtain a molded sheet. The obtained adhesive sheet had no tack at room temperature, and was tacky when heated to 60 ° C.

Example 6
In the same apparatus as in Example 1, 25.0 g of an aqueous dispersion of alumina (trade name “Alumina Sol 520”, manufactured by Nissan Chemical Industries, solid content concentration 20% by weight, containing hydroxyl group as a reactive functional group) (100% by weight of silicone derivative) 22 parts by weight), 20.0 g of methanol and 20.0 g of 2-methoxyethanol were added, and then 20.0 g of polymethylsilsesquioxane derivative (X-40-9225) was added to 24.0 of 2-propanol. The solution dissolved in g was dropped using a dropping funnel and reacted at 60 ° C. for 1 hour, and further 2.5 g of methoxytrimethylsilane (LS-510) [polymethylsilsesquioxane / 1-functional silane ( (Weight ratio) = 89/11] was dropped using a dropping funnel, reacted at 60 ° C. for 2 hours, and then cooled to room temperature (25 ° C.) to obtain a silicone resin composition of Example 6. The obtained composition obtained the adhesive sheet like Example 1. FIG. The obtained adhesive sheet had no tack at room temperature, and was tacky when heated to 60 ° C.

Example 7
In Example 1, instead of using 10.0 g of the aqueous dispersion of zirconia oxide (NZD-3007), 15.0 g (32 parts by weight with respect to 100 parts by weight of the silicone derivative) was used. The silicone resin composition of Example 7 and its adhesive sheet were obtained. The obtained adhesive sheet had no tack at room temperature, and was tacky when heated to 60 ° C.

Example 8
In Example 1, instead of using 16.0 g of the polymethylsilsesquioxane derivative (X-40-9225), the polymethylsilsesquioxane derivative [trade name “X-40-9246”, manufactured by Shin-Etsu Chemical Co., Ltd., 2 Silicone resin of Example 8 in the same manner as in Example 1 except that 16.0 g of a partially hydrolyzed condensate of functional alkoxysilane and trifunctional alkoxysilane, molecular weight 3000 to 5000, methoxy content 12% by weight] is used. A composition and its adhesive sheet were obtained. The obtained adhesive sheet had no tack at room temperature, and was tacky when heated to 60 ° C.

Comparative Example 1
In Example 1, a silicone resin composition of Comparative Example 1 and an adhesive sheet thereof were obtained in the same manner as in Example 1 except that the monofunctional silane derivative was not used. The amount of metal oxide fine particles used was 25 parts by weight per 100 parts by weight of the silicone derivative. The obtained adhesive sheet already had tack at room temperature, and the tack became stronger when heated to 60 ° C.

Comparative Example 2
In Example 1, instead of using 2.5 g of methoxytrimethylsilane (LS-510), which is a monofunctional silane derivative, dimethoxydimethylsilane chlorotrimethylsilane (trade name “KBM22”, Shin-Etsu Chemical Co., Ltd.) A silicone resin composition of Comparative Example 2 and an adhesive sheet thereof were obtained in the same manner as in Example 1 except that 2.5 g was used. The obtained adhesive sheet already had tack at room temperature, and the tack became stronger when heated to 60 ° C.

  The properties of the obtained adhesive sheet were examined according to the method of Test Example 1 below. The results are shown in Table 1. The results are also shown for the light transmittance (transmittance%) of the composition. Reference Example 1: Commercially available adhesive (trade name “SD4560”, manufactured by Toray Dow Corning), Reference Example 2: Adhesive (trade name “SE9185”, manufactured by Toray Dow Corning) were also examined in the same manner. It was.

[Test Example 1] (Tensile shear strength)
First, the adhesive sheets (2 cm × 2 cm) of Examples and Comparative Examples were each thermocompression bonded to SUS (BA plate) as an adherend at 100 ° C. with a laminator, and another alumina substrate was laminated on the adhesive sheet. After thermocompression bonding at 100 ° C. with a sheet laminator, a thermosetting reaction was performed by treatment at 150 ° C. for 1 hour to prepare a sample for measuring tensile shear strength.

  Next, using a universal tensile tester (Autograph, manufactured by Shimadzu Corp.), the measurement was performed at a tension rate of 50 mm / min for a bonding area of 2 cm × 2 cm.

  As a result, the composition of the example has high light transmittance, the adhesive sheet of the molded body has high tensile shear strength, and has no tack at room temperature. It can be seen that it is excellent. The compositions of the examples had excellent heat resistance with almost no change in transmittance even when left at 200 ° C. for 500 hours.

  The silicone resin composition of the present invention is suitably used for sealing a semiconductor element such as a backlight of a liquid crystal screen, a traffic light, an outdoor large display or an advertising signboard.

Claims (9)

A polymer obtained by polymerizing a metal oxide fine particle having a reactive functional group on the surface of the fine particle and a polymethylsilsesquioxane derivative having an alkoxysilyl group at the molecular end is represented by the formula (II):

(Wherein X represents an alkoxy group or a halogen atom)
A silicone resin composition obtained by polymerizing a monofunctional silane derivative represented by the formula:   The silicone resin composition according to claim 1, wherein the metal oxide fine particles have an average particle diameter of 1 to 100 nm.   The silicone resin composition according to claim 1 or 2, wherein the metal oxide fine particles are dispersed in water, alcohol, or a mixture thereof.   Silicone resin composition in any one of Claims 1-3 whose content of an alkoxy group is 10 to 50 weight% in 1 molecule of polymethylsilsesquioxane derivatives. The silicone resin composition according to any one of claims 1 to 4, wherein the metal oxide fine particles are at least one selected from the group consisting of titanium oxide, zirconium oxide, barium titanate, zinc oxide, lead titanate, and silicon dioxide. object. The reactive functional group is at least one selected from the group consisting of hydroxyl group, isocyanate group, amino group, mercapto group, carboxy group, epoxy group, vinyl unsaturated group, halogen group, and isocyanurate group. Item 6. The silicone resin composition according to any one of Items 1 to 5. A polymethylsilsesquioxane derivative having an alkoxysilyl group at the molecular end is represented by the formula (I):

(Where R ¹ , R ² , R ^Three And R ^Four Are each independently a hydrogen atom, an alkyl group or an aromatic group, and n represents a positive integer, provided that R represents ¹ , R ² And R ^Four Are not both hydrogen atoms, both aromatic groups, and n R ^Three May be the same or different)
A compound having the Si—O—Si skeleton in a random structure (random type), a compound having a ladder structure (ladder type), a compound having a cage structure (cage type) And the cage resin is at least one selected from the group consisting of partially cleaved compounds (partially cleaved cage). A step of polymerizing a metal oxide fine particle having a reactive functional group on the surface of the fine particle and a polymethylsilsesquioxane derivative having an alkoxysilyl group at the molecular end, and a polymer obtained in the step, (II):

(Wherein X represents an alkoxy group or a halogen atom)
In represented by including a monofunctional silane derivative step of polymerization process of claim 1 to 7 silicone resin composition according to any one. Claim 1-7 is molded of a silicone resin composition according to any one comprising a silicone-based transparent pressure-sensitive adhesive sheet.