JP2014091811A - Curable polysiloxane composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solventless latent, heat-curable polysiloxane composition which realizes a ring-opening polymerization reaction of cyclic polysiloxane in a solventless system and, moreover,having high storage stability; and to provide a method for producing an electronic component using the composition, which has high thermal decomposition resistance.SOLUTION: Provided is a curable polysiloxane composition comprising cyclic polysiloxane, a catalytic amount of tetrabutylammonium difluorotriphenyl silicate (TBAT), and a blocked isocyanate blocked with a hydroxyl group-containing compound in an amount of 0.1 to 3 times th molar amount of the TBAT. Also provided is a method for producing a polysiloxane encapsulated electronic component using the same, obtained by cross-linking and curing only -Si-O- linkages, comprising a process where cyclic polysiloxane is cured by heating to a deblocking temperature of the blocked isocyanate or higher.

Description

  The present invention relates to a curable polysiloxane composition that provides a cured polysiloxane having high heat-decomposability, and in particular, realizes a ring-opening polymerization reaction of a cyclic polysiloxane even in a solvent-free system, and further provides thermal potential to the curing reaction. It relates to the curable polysiloxane composition shown.

  Cyclic polysiloxane cured products are used in various applications including optical applications and electronic component sealing resins. As the curing system, conventionally used is a crosslinking reaction in which a functional group such as an epoxy group or a vinyl group introduced into a cyclic polysiloxane is a crosslinking point. However, since this crosslinked structure itself includes a bond between carbon atoms and a bond that does not have high thermal decomposition resistance such as a bond between a carbon atom and an oxygen atom, the cured product itself despite the high thermal decomposition resistance of the cyclic polysiloxane. The thermal decomposition resistance of is not necessarily high.

  On the other hand, hydrolysis and condensation reactions of alkoxysilane compounds form siloxane bonds, which have higher bond energies compared to bonds between carbon atoms and bonds between carbon atoms and oxygen atoms, and are resistant to thermal decomposition. high. However, as is well known, the condensation reaction system generates a non-negligible amount of low molecular weight desorbing component due to the condensation reaction when the resin composition is cured in bulk or used for resin sealing. Face a problem.

  As a possibility of solving this problem, for example, a method of performing ring-opening polymerization of a cyclic polysiloxane using various catalysts as disclosed in Patent Documents 1 to 4 may be considered. However, these reaction systems have low storage stability and are extremely inconvenient in producing a cured product or a sealed body. It is also known that it may be difficult to cure without solvent.

  Patent Document 5 discloses a thin film curable resin composition comprising a mixture of cyclic polysiloxanes, a halide source and a solvent. However, this resin composition is solvent-based and does not realize a solvent-free system. Moreover, it does not realize a heat latent curable resin composition.

JP 2001-278983 A JP 2007-517103 A JP-A-4-320423 JP 2000-197823 A JP 2009-541519 A

  Therefore, the present invention realizes a ring-opening polymerization reaction of a cyclic polysiloxane even in a solvent-free system, and has a high storage stability and a heat-latent curable polysiloxane composition, and an electronic component having a high thermal decomposition resistance using the composition It aims at providing the manufacturing method of.

The present invention comprises a cyclic polysiloxane, a catalytic amount of tetraalkylammonium difluorotriaryl silicate (a), and a blocked isocyanate blocked with a hydroxyl group-containing compound in an amount of 0.1 to 3 times the molar amount relative to (a). It is a curable polysiloxane composition.
The present invention also includes a step of supplying the curable polysiloxane composition described above to a member or a part, and heating the supplied fluid composition to a temperature equal to or higher than the deblocking temperature of the blocked isocyanate. A step of ring-opening polymerization of siloxane,
Is a method for producing a composite article comprising a polysiloxane crosslinked or polymerized only by —Si—O— bonds and a member or part.

(1) The curable polysiloxane composition of the present invention has a polymerization reaction of a cyclic polysiloxane by a ring-opening polymerization reaction according to the above-described configuration, thereby eliminating a by-product of a curing reaction as in the case of a condensation reaction ( Water, methanol, etc.) are not generated.
(2) The curable polysiloxane composition of the present invention has high thermal decomposition resistance of the cured polysiloxane skeleton because the cyclic polysiloxane is crosslinked or made high in molecular weight only by —Si—O— bonds by the above-described configuration.
(3) The curable polysiloxane composition of the present invention (hereinafter, also referred to as the composition of the present invention) exhibits thermal potential in the ring-opening polymerization reaction of the cyclic polysiloxane and has the activity of the catalyst system. When the temperature is lower than the conversion temperature, stability as an unpolymerized low-viscosity cyclic polysiloxane composition is exhibited, and the polymerization reaction can be performed only when the composition is heated to the activation temperature. It is possible to realize a ring-opening polymerization method of a cyclic polysiloxane that does not undergo ring-opening polymerization at a temperature lower than the depolymerization temperature, for example, 110 ° C., while ring-opening polymerization is performed at or above the deblocking temperature, for example, 150 ° C. Even in a heating environment (for example, an environment of 110 ° C.), the cyclic polysiloxane composition can be advantageously used for use as a curable composition for which low viscosity is desired.
(4) The composition of the present invention can also be configured as a solvent-free system.
(5) The method for producing a composite product of the present invention can provide a composite product having high heat-decomposability, such as a resin-encapsulated electronic component, a fiber-reinforced composite material, etc., with the above-described configuration.

  The composition of the present invention can be cured by ring-opening polymerization of a cyclic polysiloxane. The cyclic polysiloxane may be represented by (SiR3O1 / 2) a (SiR2O2 / 2) b (SiRO3 / 2) c (SiO4 / 2) d. In the formula, a to d are 0 or a natural number, and satisfy the relational expression (a + 2b + 3c + 4d) / (a + b + c + d)> 2. That is, in the silsesquioxane, when the average number of oxygen atoms bonded to silicon atoms in the total number of moles is greater than 1, a curable composition can be provided. In the embodiment, a cyclic polysiloxane having a D unit (that is, —O—Si (—R) 2 —O—) and a T unit (that is, Si (—R) (— O—) 3) as a structural unit is used. Can be mentioned. Examples of the cyclic polysiloxane composed of D units include cyclosiloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and those having a substituent. Examples of the cyclic polysiloxane composed of T units include silsesquioxanes. The silsesquioxane is a polysiloxane having a general formula of (RSiO3 / 2) n generated through a process represented by hydrolysis and condensation reaction of trialkoxysilane, for example. . The silsesquioxane is known to have a saddle type, ladder type, or random type structure. Further, modified silsesquioxanes having various substituents introduced therein are also known as the silsesquioxanes. All of the silsesquioxanes contain a cyclic structure, and the silsesquioxanes can perform a ring-opening polymerization reaction. In the composition of the present invention, the cyclic polysiloxane may be one containing only T units, a mixture of T units and D units, one containing both T units and D units, or the like. However, when the T unit and the D unit are present, it is preferable that the content of the T unit is larger than the D unit. As an aspect of the above-mentioned cyclic polysiloxane, a cage structure composed only of Q units (ie, Si (—O—) 4) and M units (ie, —O—Si (—R) 3) is used. It has been known. Also, by containing M units at the silsesquioxane terminal, the content of terminal silanol (hydroxyl group) in the silsesquioxane is reduced, preferably the content is made substantially zero, and the viscosity of the composition is increased by the hydroxyl group. The risk of a decrease in stability such as reaction can be prevented.

  In the present invention, the tetraalkylammonium difluorotriaryl silicate may be one having no substituent on the benzene ring, or a substituent (for example, an alkyl group having 1 to 6 carbon atoms, an alkenyl group, an alkanoyl group). , An alkoxy group, a nitro group, etc.). Moreover, it can have 1 to 3 substituents on at least one of the three benzene rings. As an alkyl group which concerns on an ammonium group, a C1-C6 alkyl group is mentioned, for example. Specific examples of the tetraalkylammonium difluorotriaryl silicate include tetrabutylammonium difluorotriphenyl silicate (TBAT).

  In the present invention, as the blocked isocyanate blocked with a hydroxyl group-containing compound, an organic isocyanate in which an isocyanate group is blocked using a hydroxyl group-containing compound such as alcohol, oxime, ether, ester or the like as a blocking agent can be used. Examples of the alcohol include methanol, ethanol, n-butanol, propanol, octanol, benzyl alcohol, and phenol. Examples of the oxime include methyl ethyl ketone oxime, acetophenone oxime, cyclohexanone oxime, 4-methyl-2-propanone oxime, and 5-methyl-2-hexanone oxime. Examples of the ether include methyl cellosolve, ethyl cellosolve, and butyl cellosolve. Examples of the ester include lactic acid ester and amyl lactic acid. Of these, the hydroxyl group-containing compound is more preferably an oxime.

  Examples of the organic isocyanate in the blocked isocyanate include monoisocyanate and polyisocyanate. The monoisocyanate is not particularly limited, and examples thereof include aliphatic monoisocyanates such as methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate, hexyl isocyanate, octyl isocyanate, lauryl isocyanate, octadecyl isocyanate, and alicyclic rings such as cyclohexyl isocyanate and isophorone isocyanate. Group monoisocyanates; aromatic isocyanates such as phenyl isocyanate and naphthyl isocyanate.

  The polyisocyanate is not particularly limited, and includes difunctional, trifunctional or higher polyfunctional isocyanates. Specific examples include methylene diisocyanate, isopropylene diisocyanate, butane-1,4-diisocyanate, hexamethylene. Chain aliphatic diisocyanates such as diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate; cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′- Cyclic aliphatic diisocyanates such as diisocyanate, 1,3-di (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate; 4,4′-diphenyldimethylmethane diiso Dialkyldiphenylmethane diisocyanate such as anate, tetraalkyldiphenylmethane diisocyanate such as 4,4′-diphenyltetramethylmethane diisocyanate, 1,5-naphthylene diisocyanate, methylenebis (4,1-phenylene) diisocyanate, 4,4′-diphenyldimethylmethane Aromatic diisocyanates such as diisocyanate, 4,4′-dibenzyl isocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, m-tetramethylxylylene diisocyanate; And the like.

  As a method for obtaining the blocked isocyanate, a known method can be used. For example, the reaction is performed at about 50 to 150 ° C. using a blocking agent equivalent to 1 to 2 times the isocyanate group of the organic isocyanate. Manufactured.

  In the composition of the present invention, a catalytic amount of a tetraalkylammonium difluorotriaryl silicate (a) and a blocked isocyanate blocked with a hydroxyl group-containing compound in an amount of 0.1 to 3 moles relative to the above (a) Containing. The content of (a) is preferably 0.1 to 10 parts by weight and more preferably 0.5 to 3 parts by weight with respect to 100 parts by weight of the cyclic polysiloxane. When (a) is 0.1 to 10 parts by weight, the reactivity is good and it is advantageous.

  Content of the said blocked isocyanate is 0.1-3 times mole amount with respect to said (a), 0.3-2 times mole amount is more preferable, 0.5-1.3 times mole amount Is more preferable. Further, the content of the blocked isocyanate is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the cyclic polysiloxane in terms of the content of the hydroxyl group-containing blocking agent, -3 parts by weight is more preferred.

  If necessary, a deblocking catalyst can be used in the composition of the present invention. Examples of such deblocking catalysts are generally known, for example, zirconium acetylacetone, aluminum trisacetylacetonate, titanium tetrakisacetylacetonate, gallium trisacetylacetonate, indium trisacetylacetonate, and zinc bisacetylacetonate. The catalyst which has been described can be mentioned. Moreover, as the compounding quantity, 0.005-10 weight part is preferable with respect to 100 weight part of blocked isocyanate.

  A filler, an antifoamer, a silane coupling agent, etc. can be added to the composition of this invention as needed. Examples of the filler include silica, boron nitride, alumina, graphite, silicon carbide, and the like. The amount of the filler is preferably 1 to 90% by weight, more preferably 10 to 60% in the composition. % By weight. Examples of the antifoaming agent include a silicone-based antifoaming agent, and the amount of the antifoaming agent is preferably 0.01 to 1% by weight, more preferably 0.01 to 0.1% by weight in the composition. %. Examples of the silane coupling agent include epoxy-based, acrylic-based, and silicone-based silane coupling agents. The amount of the silane coupling agent is preferably 0.01 to 5% by weight, more preferably 0.1%. ~ 2% by weight.

  The composition of the present invention may or may not contain a solvent. In the case of a solventless system, for example, it is preferable when used for forming a cured product using a mold or for bulk curing. In the case of a solvent system, for example, it is preferable when used for thin film curing. Thus, a solvent can be used suitably according to a use. Examples of the solvent include hydroxyl group-free solvents such as ethyl acetate, toluene, xylene, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether. Further, the blending amount is not particularly limited, and can be appropriately determined in order to adjust the viscosity and the like, but generally 0.1 to 100 parts by weight of the non-solvent component in the composition. 200 parts by weight is preferable, and more preferably 50 to 100 parts by weight.

  The method for producing the composition of the present invention is not particularly limited as long as it is a method of mixing the above-described components so as to be uniformly blended in the composition. Preferred embodiments thereof include, for example, the above cyclic polysiloxane, tetraalkylammonium difluorotriaryl silicate, blocked isocyanate, and, if applicable, other such as deblocking catalyst, filler, antifoaming agent, and silane coupling agent. The additives are mixed so that the whole composition is uniform. In that case, a solvent can be used as needed. In the case of using a solvent, for example, each component is dissolved or dispersed in the above solvent to obtain a uniform liquid composition. In the case of a composition containing a solvent, the content may be appropriately adjusted so that the content of the solvent in the liquid composition falls within the above range. When the composition does not contain a solvent, all the solvent may be distilled off from the liquid composition. The solvent can be distilled off by a conventional method, for example, by applying reduced pressure, preferably reduced pressure from room temperature to warming (for example, 20 ° C. or higher and lower than 100 ° C.).

  When using a solvent, a small amount of acid can be contained in the liquid composition together with the solvent. Inclusion of an acid is preferable because it can prevent the composition from increasing in viscosity due to evaporation of the solvent. Examples of the acid include carboxylic acid. Examples of the carboxylic acid include aliphatic carboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, and hexanoic acid, and dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, and adipic acid. Moreover, as a compounding quantity of an acid, 0.01-3 weight part is preferable with respect to 100 weight part of solvents to be used, and 0.1-0.5 weight part is more preferable.

  The composition of the present invention exhibits thermal potential in the ring-opening polymerization of cyclic polysiloxane, and exhibits stability as an unpolymerized low-viscosity cyclic polysiloxane composition below the activation temperature of the catalyst system. It is possible to cause the polymerization reaction only when the composition is heated to the activation temperature of the system. Indication of thermal potential means normal reaction time (eg, several times) below the reaction activation temperature (eg, deblocking temperature if elimination of blocking agent of blocked isocyanate triggers reaction). The reaction does not proceed substantially in minutes to within a few tens of minutes. The molecular weight of the reaction mixture does not increase or does not increase substantially, but it is above the reaction activation temperature (ie above the activation temperature of the catalyst system). ) Means that the reaction proceeds in a normal reaction time and the molecular weight is increased by polymerization.

  The production method of the present invention includes a step of supplying the composition of the present invention to a member or a part at a temperature lower than the deblocking temperature of the blocked isocyanate, and the flowable composition supplied to the member or part. A process comprising a step of ring-opening polymerization of a cyclic polysiloxane by heating to a temperature higher than the deblocking temperature of the blocked isocyanate, and a composite composed of a polysiloxane crosslinked or polymerized only by —Si—O— bonds and a member or component Product manufacturing method. The deblocking temperature of the blocked isocyanate blocked with the hydroxyl group-containing compound varies depending on the blocking agent, but is generally 80 to 200 ° C. The composition of the present invention can be supplied by using a known apparatus for supplying a flowable composition, for example, using a dispenser, and the method is well known to those skilled in the art. The member or component is not particularly limited, and can be applied to a desired member or component to be used in combination with the composition of the present invention. The composite product is not particularly limited. Embodiments in which the composition of the present invention is applied and cured, embodiments in which the composition of the present invention is sealed and cured, embodiments in which the composition of the present invention is impregnated and cured, and embodiments in which the composition of the present invention is adhesively cured be able to. Examples of the production method of the present invention include an embodiment in which an electronic component is sealed and cured with the composition of the present invention. The above-described curable polysiloxane composition is deblocked from the blocked isocyanate. A step of supplying the electronic component at a temperature lower than the temperature, and a step of ring-opening polymerization of the cyclic polysiloxane by heating the supplied fluid composition to a temperature higher than the deblocking temperature of the blocked isocyanate, Is a method for producing an electronic component that is sealed with polysiloxane crosslinked or polymerized only by —Si—O— bonds. In this case, the fluid composition of the present invention is supplied to the electronic component to be sealed with a dispenser onto the substrate surface or the like. Next, ring-opening polymerization is performed on the cyclic polysiloxane dispensed by heating to a temperature higher than the deblocking temperature of the blocked isocyanate. The polymerization reaction can be performed under normal pressure (that is, under atmospheric pressure), for example, 125 to 200 ° C. and several minutes to several tens of minutes. Alternatively, the step of supplying the impregnated curable polysiloxane composition to a member such as a reinforcing fiber at a temperature lower than the deblocking temperature of the blocked isocyanate, and the impregnated fluidity A step of heating the composition to a temperature equal to or higher than the deblocking temperature of the blocked isocyanate to perform ring-opening polymerization of the cyclic polysiloxane. The heat resistance comprising a polysiloxane crosslinked or polymerized only by a Si—O— bond as a matrix. It is a manufacturing method of a composite member.

  Examples of the component include an integrated circuit, a light emitting element, an optical component, a heat resistant substrate, an aerospace component, an automotive component, and a robot arm component. As said member, a reinforced fiber etc. can be mentioned, for example. The reinforcing fiber is not particularly limited, and examples thereof include those made of materials such as glass and carbon used for FRP.

  The production method of the present invention can also be preferably carried out by applying a compression molding method or a transfer molding method. In such a case, the flowable composition of the present invention may be supplied to a mold or a pot, and then subjected to ring-opening polymerization as described above.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, the following description is only for description and the present invention is not limited to these Examples.

The meanings of the abbreviations in the following examples and comparative examples are as follows. In addition, the unit of the compounding quantity in a table | surface is a weight part.
Resin 1: Polyphenylethylsilsesquioxane resin 2: Mixture of polyvinylethylsilsesquioxane and 1,1,3,3-tetramethyldisiloxane TBAT: Tetrabutylammonium difluorotriphenylsilicate TAFF: Tetrabutylammonium fluoride Pt: Platinum-divinyltetramethyldisiloxane Xylene solution TDI: Tolylene diisocyanate (8: 2 mixture of 2,4- / 2,6-)
HDI: hexamethylene diisocyanate MDI: methylene bis (4,1-phenylene) diisocyanate MHO: 5-methyl-2-hexanone oxime BA: benzyl alcohol MEK: methyl ethyl ketone oxime AO: acetophenone oxime TDI-MHO: hydroxyl group of TDI isocyanate and MHO Reacted blocked isocyanate TDI-AO: blocked isocyanate obtained by reacting isocyanate of TDI with hydroxyl group of AO HDI-BA: blocked isocyanate reacted with isocyanate of BA and hydroxyl group of BA MDI-MEK: isocyanate of MDI Blocked isocyanate curing conditions in which the hydroxyl group of MEK was reacted (1): 150 ° C. for 10 hours + 200 ° C. for 5 hours curing condition (2): 150 ° C. for 3 hours curing condition (3 : 100 ℃ 1h + 150 ℃ 3 hours

Examples 1-5, Comparative Examples 1-2
The resin, catalyst, and hydroxyl group-blocked isocyanate described in Tables 1 and 2 were dissolved in a solvent diglyme (also referred to as diethylene glycol dimethyl ether; the same shall apply hereinafter) to be uniform. Next, the solvent was completely distilled off under reduced pressure at 90 ° C. Thereafter, the mold was cast and heat-cured under curing conditions (1).

Comparative Examples 3-4
The resin described in Table 2 was dissolved in the solvent diglyme, and various catalysts described in Table 2 were added. Heat curing was performed under curing conditions (2).

Comparative Example 5
The resin and catalyst described in Table 2 were dissolved in the solvent xylene to make it uniform. Next, the solvent was completely distilled off under reduced pressure at room temperature. Thereafter, casting was performed and heat curing was performed under curing conditions (3).

<Reactivity>
After heating under each predetermined condition, soaking in a THF solution and not dissolving, it can be said that the crosslinking reaction has progressed, `` ○ '', whereas if dissolved, it can be said that the crosslinking reaction has not progressed, `` X '', Each was evaluated.
<Thermal potential>
When heated at 100 ° C. for 1 hour, it was evaluated as “◯” if it did not gel, and “×” if gelled. Moreover, when there was no reactivity, it did not evaluate.
<Thermal aging test>
In a system having reactivity under each curing condition, the weight loss rate of the cured product obtained by using TG-DTA is 30 ° C. to 600 ° C. (temperature increase rate of 10 ° C./min) in an air atmosphere. Measurement. The temperature at which the weight reduction rate reached 10% by weight was noted. Moreover, when there was no reactivity, it did not evaluate.

  From the results of Examples 1 to 5, the reactivity was not shown up to 110 ° C., but the catalyst was activated at the temperature higher than the deblocking temperature of the hydroxyl group-blocked isocyanate, and the reactivity was confirmed. In other words, it showed thermal potential. On the other hand, when each was added alone as in Comparative Examples 1-2, the reactivity was not exhibited, and when the hydroxyl compound was added as it was as in Comparative Examples 3-4 or when TBAF was used as the catalyst, Thermal potential cannot be obtained. Furthermore, regarding heat resistance, Examples 1 to 5 have higher heat resistance than Comparative Example 5 which is generally crosslinked by an ethylene chain called an addition type.

Claims (7)

  A cyclic polysiloxane, a catalytic amount of a tetraalkylammonium difluorotriaryl silicate (a), and a blocked isocyanate blocked with a hydroxyl group-containing compound in an amount of 0.1 to 3 times the molar amount of (a), Curable polysiloxane composition.   The composition of claim 1, wherein the tetraalkylammonium difluorotriaryl silicate is tetrabutylammonium difluorotriphenyl silicate.   The composition according to claim 1 or 2, wherein the hydroxyl group-containing compound is alcohol, oxime, ether or ester.   The composition according to claim 3, wherein the hydroxyl group-containing compound is an oxime. Contains cyclic polysiloxane, catalytic amount of tetraalkylammonium difluorotriaryl silicate (a), and blocked isocyanate blocked with a hydroxyl group-containing compound in an amount of 0.1 to 3 times the amount of (a). Supplying the curable polysiloxane composition to the member or part at a temperature below the deblocking temperature of the blocked isocyanate, and removing the supplied flowable composition from the blocked isocyanate. A step of ring-opening polymerization of the cyclic polysiloxane by heating above the blocking temperature;
And a method for producing a composite product comprising a polysiloxane crosslinked or polymerized only by -Si-O- bonds and a member or a part.   The manufacturing method according to claim 5, wherein an electronic component is used as the component, and a resin-encapsulated electronic component comprising polysiloxane and the electronic component is manufactured as a composite product.   The manufacturing method according to claim 5, wherein a reinforcing fiber is used as a member, and a fiber-reinforced composite material made of polysiloxane and reinforcing fiber is manufactured as a composite product.