JP2864898B2 - Silicone resin molded article and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article of silicone resin having excellent water resistance and mechanical strength, and excellent heat resistance and electrical properties, and a method for producing the same.

[0002]

2. Description of the Related Art
Molded silicone resin articles obtained by heating and molding an inorganic material such as mica foil or glass fiber as a molding auxiliary material and a silicone resin composition have excellent electrical and heat-resistant properties. Used as an electrical insulating material.

[0003] However, the above-mentioned silicone resin molded article has a drawback that water resistance and mechanical strength are inferior to those using an organic resin, and therefore, this aspect has been conventionally improved. Specifically, JP-A-48-24295
JP-A-50-98550 discloses a composition using a combination of a silicone resin and a functional group-containing silicon compound, and JP-A-52-64424 discloses an organic resin having a relatively high heat resistance with a silicone resin. And JP-A-53-80664 proposes a composition in which an inorganic material is previously treated with an organosilicon compound. However, these silicone resin molded articles are insufficiently improved in water resistance and mechanical strength, or have good water resistance and mechanical strength, but have reduced heat resistance to deteriorate smoke emission, workability, and cost. Disadvantageous in terms of
All of them have hardly been said to have satisfactory characteristics.

[0004] Accordingly, development of a molded article of silicone resin having excellent properties has been desired. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a silicone resin molded article having excellent water resistance and mechanical strength, and excellent heat resistance and electrical properties, and a method for producing the same.

[0005]

The present inventors have made intensive studies in view of the above circumstances, and as a result, have found that organopolysiloxane 100 mainly composed of trifunctional siloxane units represented by the following average composition formula (1). Parts (weight parts,
The same applies hereinafter) and 100 parts of a silicone resin composition containing a mixture of 0.1 to 10 parts of an organopolysiloxane represented by the following average composition formula (2) or a co-hydrolysate thereof in the presence or absence of a catalyst. Under a catalyst, a molding auxiliary material selected from inorganic materials, in particular, mica foil, mica powder, silica powder, spraying or impregnating 50 to 2000 parts of an inorganic material such as glass fiber, and then heat molding to form a silicone resin molded article. When obtained, the water resistance and mechanical strength are improved by incorporating the block structure into the silicone resin by using the organopolysiloxane of the formula (1) and the diorganopolysiloxane having both ends reactive at the formula (2) in combination. In addition, it has been found that both the heat resistance and the electrical characteristics are good, and the characteristics are achieved in a well-balanced manner.

[0006]

Embedded image (Where R ¹ is an alkyl group having 1 to 4 carbon atoms or a phenyl group, R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, epoxy Group-containing silyl group, amino group-containing silyl group or carbon number 1
And alkoxysilyl group-containing silyl groups of a to b,
Is a positive number satisfying 0.8 <a <1.1 and 0 <b <2, respectively, and n is an integer of 3 or more and 1000 or less. )

Accordingly, the present invention relates to the above average composition formula (1)
100 parts of an organopolysiloxane mainly composed of a trifunctional siloxane unit represented by the following formula, and 0.1 to 10 of the organopolysiloxane represented by the above average composition formula (2).
After spraying or impregnating 50 to 2000 parts of a molding auxiliary material selected from inorganic materials in the presence of a catalyst or without a catalyst in the presence or absence of a catalyst, The present invention also provides a method for producing a molded article of silicone resin characterized by being subjected to heat molding, and a molded article of silicone resin obtained therefrom.

Hereinafter, the present invention will be described in more detail. The first component of the silicone resin composition used in the production of the molded silicone resin article of the present invention comprises a silanol group represented by the following average composition formula (1) or a hydrolyzable compound. Organopolysiloxanes with possible alkoxy groups.

[0009]

Embedded image (Where R ¹ is an alkyl group having 1 to 4 carbon atoms or a phenyl group, R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and a and b are each 0.8 <a <1. 1, 0 <b
It is a positive number satisfying <2. )

Here, R ¹ in the formula includes, for example, a methyl group, an ethyl group, a phenyl group and the like, and particularly preferably a methyl group mainly from the viewpoint of heat resistance. The number a of R ¹ is 0.8 from the viewpoint of the hardness and strength of the molded article.
<A <1.1, and the organopolysiloxane of the formula (1) is mainly composed of trifunctional siloxane units. When a is 0.8 or less, the cured product becomes hard but brittle, and when 1.1 or more, the hardness as a molded article is insufficient.

R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Therefore, the OR ² group is an alkoxy group such as a silanol group, a methoxy group, an ethoxy group, an isopropoxy group or an isobutoxy group. A methoxy group, an ethoxy group, and an isopropoxy group are preferred from the viewpoint of reactivity, particularly, hydrolyzability. Further, b is a positive number satisfying 0 <b <2, and represents the content of these functional groups. Equation (1)
When b = 0, it is impossible to cure the organopolysiloxane of the present invention into a molded product, and when b is greater than 2, a large amount of alkoxy groups remain even after the molded product is obtained, and sufficient water resistance is obtained. Absent.

The molecular weight of the organopolysiloxane of the above formula (1) is preferably from 1,000 to 100,000 from the viewpoint of workability. If it is less than 1,000, it may volatilize during molding. The strength of the article may decrease.

Next, the organopolysiloxane of the second component is represented by the following average composition formula (2).

[0014]

Embedded image (Wherein, R ¹ is the same as described above, X is a hydrogen atom,
An alkyl group having 1 to 4 carbon atoms, an epoxy group-containing silyl group,
It is an amino group-containing silyl group or an alkoxysilyl group-containing silyl group having 1 to 4 carbon atoms, and n is an integer of 3 or more and 1000 or less. )

The organopolysiloxane of the formula (2) has a linear structure, and has a functional group capable of reacting with the functional group of the organopolysiloxane of the formula (1) at both ends, and has water resistance and It is an important component for improving mechanical strength. That is, the organopolysiloxane of the formula (2)
Since it has two or more functional groups in one molecule, it acts as a crosslinking agent, and its linear structure is introduced into the organopolysiloxane mainly composed of trifunctional siloxane units of the formula (1) to form a block structure. It is expected that, by being partially formed, the brittleness of the molded article is reduced and the strength is improved, and the linear silicone oil-like structure imparts water repellency and improves water resistance. . From this, n in equation (2)
Is an important factor in determining the above effect.

In the above formula (2), R ¹ may be the same as described above, but is preferably a methyl group in view of water resistance, heat resistance and cost. X
Is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a silyl group containing an epoxy group, a silyl group containing an amino group, and a silyl group containing an alkoxysilyl group. These silyl groups include-
SiR ² _m R ³ _3-m (where R ² is an alkyl group, a phenyl group or an alkoxy group, R ³ is an organic group containing an epoxy group, an amino group or an alkoxysilyl group as a substituent, and m = 0 To 3) can be exemplified. Specifically, the following can be exemplified as X.

[0017]

Embedded image

In the formula (2), n is an integer of 3 or more and 1000 or less. If n is less than 3, the linear structure is too short, and the improvement in water resistance is small. The effect as a cross-linking agent is small, and it is difficult to be incorporated into the organopolysiloxane of the formula (1), and an effective block structure cannot be obtained.

The organopolysiloxane of the formula (2) may be used singly or as a mixture of two or more. The compounding amount is 100 parts by weight of the organopolysiloxane of the formula (1). 0.1 to 10 parts, preferably 0.2 to 5 parts. If the compounding amount is less than 0.1 part, the effect of improving water resistance is not so much seen, and even if it exceeds 10 parts, no further effect can be expected, and a decrease in hardness occurs.

The composition of the present invention may contain a co-hydrolyzate of the above-mentioned organopolysiloxane of the formulas (1) and (2). In this case, the alkoxy functional group of the organopolysiloxane is reduced by forming a siloxane bond during heat molding. In some cases, the alkoxy group remains to adversely affect the water resistance, so that it is effective to reduce the alkoxy group content by co-hydrolyzing the organopolysiloxane in advance.

The above-mentioned co-hydrolysis can be carried out by using a general method for producing an organopolysiloxane by hydrolyzing an organoalkoxysilane, for example, when X of the organopolysiloxane of the formula (2) is an alkoxypolysiloxane. In the case of a group-containing silyl group, it can be hydrolyzed with water using an acid such as hydrochloric acid or acetic acid as a catalyst. The amount of water used is 0.5 to 2 of the theoretical amount required for hydrolytic condensation of all the alkoxy groups.
The reaction conditions are 10 to 150 ° C. and 0.5 to
10 hours is preferred. If necessary, solvents such as toluene, xylene, methanol, isopropyl alcohol, isobutanol, acetone, and ethyl acetate can be used. After the reaction, the catalyst is desirably removed by neutralization, washing with water, or the like.

In the present invention, a silicone resin composition containing a mixture of the organopolysiloxanes of the above formulas (1) and (2) or a co-hydrolyzate thereof may be used in the presence or absence of a condensation promoting catalyst for molding. After spraying or impregnating the material, it is molded by heating to form a molded article.

Here, examples of the condensation promoting catalyst include phosphoric acid, phosphoric acid ester, and organic metal salts such as aluminum, zinc, and titanium. Particularly, when mica foil is used as an auxiliary material for molding, phosphoric acid is used. Use of a phosphoric acid ester is preferred from the viewpoint of improving moldability and mechanical properties. The amount of catalyst added can be a normal amount of catalyst.

As an auxiliary material for molding, inorganic materials such as mica foil and glass fiber are preferably used.
Further, the silicone resin composition of the present invention can be sprayed or impregnated with an inorganic filler such as silica powder or mica powder as a molding auxiliary material, and cured by heating, whereby a good molded article can be obtained. Other as auxiliary materials for molding, bengara, talc, alumina, calcium carbonate,
Inorganic powders such as barium sulfate, aluminum hydroxide and zinc carbonate can also be mixed as needed.

The amount of the molding auxiliary material used is 50 to 50 parts per 100 parts of the organopolysiloxane of the formula (1).
Preferably it is 2000 parts.

In the present invention, the method of heat molding may be a method generally used in industry.
For example, the organopolysiloxanes of the formulas (1) and (2) are diluted with a solvent and impregnated with a molding auxiliary material by spraying or doping. In this case, it is preferable to adjust the dilution ratio in advance in consideration of the impregnation amount and workability. Further, after drying at 50 to 100 ° C. for 5 to 20 minutes to remove the solvent, an auxiliary material for molding is laminated to a desired thickness, and the mixture is dried under the conditions of 100 to 200 ° C. and 5 to 50 kg / cm ² . .
The molded article can be obtained by press-curing for 5 to 5 hours.

[0027]

Industrial Applicability The silicone resin molded article of the present invention has excellent water resistance, mechanical strength, heat resistance and electric properties, and can be widely used as an electric insulating material.

[0028]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Examples 1 to 6, Comparative Examples 1 to 4] 400 g of methyltriisopropoxysilane and 200 g of toluene were charged into a 1-liter flask, and 60 g of 10% hydrochloric acid aqueous solution was added dropwise at 25 ° C. with stirring for 30 minutes. Then the temperature rose to 35 ° C. After stirring at this temperature for 1 hour,
200 g of 0% Glauber's salt hot water was added, and after 10 minutes of stirring, the operation of removing the lower aqueous phase was repeated three times to stop the reaction. After adding 20 g of anhydrous sodium sulfate, stirring at 25 ° C. for 5 hours, the mixture was filtered to obtain 330 g of a methylpolysiloxane solution. This solution contains 40% of the resin solid content of the following formula [I], and the content of the functional group with respect to the resin solid content is
% And isopropoxy groups were 3%.

[0030]

Embedded image The above-mentioned methylpolysiloxane solution was used as the organopolysiloxane of the formula (1), and the one shown in Table 1 was used as the organopolysiloxane of the formula (2). Further, 2% orthophosphoric acid based on the weight of the resin was added thereto, and the resin concentration was diluted to 20% with isopropanol.

Next, blown to the liquid resin content to mica foil of 10%, was dried for 10 minutes at 100 ° C., molding pressure 20 kg / cm ² stacked 10 sheets, 1
Press hardening was performed at 80 ° C. to obtain a mica molded product having a thickness of 0.5 mm. Using this as a test piece, mechanical strength (bending strength), water resistance (residual bending strength after boiling water immersion), electrical properties (volume resistivity), and heat resistance (smoke resistance) were evaluated by the following methods. Table 1 shows the results.

Mechanical strength (bending strength): 25 mm × 50 m
m, using a test piece of 0.5 mm thickness, the distance between the fulcrums 40
The bending strength was calculated from the maximum load at the time of breaking under the conditions of 50 mm / min.

Water resistance (residual bending strength after boiling water): 2
Using a test piece of 5 mm x 50 mm and thickness of 0.5 mm,
The bending strength after boiling for 1 hour was measured in the same manner as above,
The flexural strength of the test specimen after boiling / the flexural strength of the test specimen before boiling was evaluated as a residual ratio according to the following criteria. ◎ Residual rate 60% or more ○ Residual rate 30-60% △ Residual rate 30% or less

Electrical properties (volume resistivity): The volume resistivity of the test piece was measured, and a sample having a resistivity of 1 × 10 ¹⁴ Ω · cm or more was evaluated as ○.

Heat resistance (smoke emission): 30 mm × 100 mm
A nichrome wire having a resistance value of 4 Ω / m was wound around the test piece at an equal interval, charged at AC 60 V, observed for smoke generation, and evaluated according to the following criteria. ○ No smoke △ Small amount of smoke

[0036]

[Table 1]

[0037]

Embedded image

Examples 7 to 9 and Comparative Examples 5 and 6 500 g of the compound represented by the following formula and the organopolysiloxane of the formula (2) shown in Table 2 were used and the compounding ratio shown in Table 2 was 1 Liter flask, and then add toluene 20
0 g was added, and 40 g of 10% hydrochloric acid aqueous solution was dropped and mixed with stirring for 30 minutes. The internal temperature rose from 20 ° C to 40 ° C.

[0039]

Embedded image

After stirring at this temperature for 1 hour, 200 g of 10% sodium sulfate was added to stop the reaction. After 10 minutes of stirring, a water washing operation for removing the lower aqueous phase was repeated three times.
After adding 20 g of anhydrous sodium sulfate, stirring at 30 ° C. for 5 hours, the mixture was filtered to obtain an organopolysiloxane solution.

To this organopolysiloxane solution, 2% of orthophosphoric acid was added to 100 parts by weight of the resin solid content, and diluted with isopropanol so that the resin concentration became 20%.

Next, the mica foil was treated in the same manner as in Example 1,
A mica molded product was obtained. Various evaluations were performed using this mica molded product as a test piece. Table 2 shows the results.

[0043]

[Table 2]

[0044]

Embedded image

Examples 10 to 15 and Comparative Examples 7 and 8 250 g of methyltriethoxysilane, 50 g of phenyltrimethoxysilane and 200 g of toluene were charged into a 1-liter flask, and 70 g of 10% aqueous hydrochloric acid was stirred for 30 minutes. The mixture was added dropwise, and the stirring was further continued for 1 hour. The temperature is 20 ° C
To 35 ° C. Next, 200 g of 10% sodium sulfate was added, and after 10 minutes of stirring, a water washing operation for removing a lower aqueous phase was repeated three times to stop the reaction. After adding 20 g of anhydrous sodium sulfate and stirring for 5 hours, the mixture was filtered to obtain a methylphenylpolysiloxane solution. This solution contained 40% of the resin solid content of the following formula [II], and the content of functional groups based on the resin solid content was 5% for silanol groups, 3% for ethoxy groups, and 2% for methoxy groups.

[0046]

Embedded image Using the above methylphenylpolysiloxane as the organopolysiloxane of the formula (1) and the one shown in Table 3 as the organopolysiloxane of the formula (2), in the same manner as in Example 1 except that they are blended in the blending ratio shown in Table 3. A mica molded product was obtained. Various evaluations were performed using this mica molded product as a test piece. Table 3 shows the results.

From the results shown in Tables 1 to 3, it was confirmed that the silicone resin molded article of the present invention was excellent in water resistance, mechanical strength, heat resistance and electric properties.

[0048]

[Table 3]

[0049]

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──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C08L 83/06 C08K 3/00

Claims (3)

(57) [Claims] 1. 100 parts by weight of an organopolysiloxane mainly composed of a trifunctional siloxane unit represented by the following average composition formula (1) and 0.1 to 10 organopolysiloxane represented by the following average composition formula (2): After spraying or impregnating 50 to 2,000 parts by weight of a molding auxiliary material selected from inorganic materials with 100 parts by weight of a silicone resin composition containing a mixture with a part by weight or a co-hydrolyzate thereof, followed by heat molding. A method for producing a molded article of silicone resin, characterized by comprising: Embedded image (Where R ¹ is an alkyl group having 1 to 4 carbon atoms or a phenyl group, R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, a and b are each 0.8 <a <1.1, 0 <b <2
Is a positive number that satisfies ) (Wherein, R ¹ has the same meaning as described above, and X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a silyl group containing an epoxy group, a silyl group containing an amino group, or an alkoxysilyl group having 1 to 4 carbon atoms. A group-containing silyl group, and n is an integer of 3 to 1000.) 2. The method for producing a molded article of silicone resin according to claim 1, wherein the organopolysiloxane of the formula (2) is used in which both ends of a molecular chain are blocked with a di- or trialkoxysilyl group. 3. A molded silicone resin article obtained by the production method according to claim 1.