JPH06100781A - Silicone resin molded part and its production - Google Patents

Abstract

PURPOSE:To obtain the subject molded part excellent in water resistance, heat resistance, and electric characteristics and useful for electric insulating materials, etc., by heating and molding a specific silicone resin composition together with a molding auxiliary material. CONSTITUTION:A silicone resin composition containing the mixture of 100 pts.wt. of an organopolysuloxane of formula I (R<1> is 1-4C alkyl, phenyl; R<2> is H, 1-4C alkyl; (a) is 0.8-1.1; (b) is 0-2) with 0.1-10 pts.wt. of an organopolysiloxane of formula II (X is H, 1-4C alkyl, epoxy group-containing silyl, amino group-containing silyl, 1-4C alkoxysilyl group-containing silyl; (n) is 3-1000) or its cohydrolysate is heated and molded together with a molding auxiliary material such as mica flakes and glass fibers preferably in an amount of 50-2000 pts.wt. (based on 100 pts.wt. of the component A) to obtain the objective molded part.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
An inorganic material such as mica foil or glass fiber is used as a molding auxiliary material, and a silicone resin molded article obtained by heat molding this and a silicone resin composition has excellent electric characteristics and heat resistance characteristics. It is used as an electrical insulation material.

However, the above-mentioned silicone resin molded article has a drawback that it is inferior in water resistance and mechanical strength to those using an organic resin, and therefore this aspect has been conventionally improved. Specifically, JP-A-48-24295
No. 50-98550 and JP-A No. 50-98550 each use a composition in which a silicone resin is used in combination with a functional group-containing silicon compound, and JP-A No. 52-64424 discloses a silicone resin and an organic resin having relatively good heat resistance. Japanese Patent Application Laid-Open No. 53-80664 proposes a composition in which the above-mentioned compounds are used in combination, and an inorganic material previously treated with an organosilicon compound. However, these silicone resin molded articles have insufficient improvements in water resistance and mechanical strength, or have good water resistance and mechanical strength, but have reduced heat resistance and deteriorated smoke emission, workability, and cost. Is disadvantageous in terms of
It was hard to say that all of them had satisfactory characteristics.

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

[0005]

Means for Solving the Problems The present inventor has conducted extensive studies in view of the above circumstances, and as a result, 100 parts (parts by weight, hereinafter the same) of organopolysiloxane represented by the following average composition formula (1) and A silicone resin composition containing a mixture with 0.1 to 10 parts of the organopolysiloxane represented by the average composition formula (2) or a cohydrolyzate thereof in the presence or absence of a catalyst and a molding auxiliary material. In particular, when a silicone resin molded article is obtained by heat molding together with an inorganic material such as mica foil, mica powder, silica powder, glass fiber, etc., the organopolysiloxane of formula (1) and the reactive diamine at both ends of formula (2) are used. By incorporating a block structure into the silicone resin by using the organopolysiloxane together, the water resistance and mechanical strength are improved, and both heat resistance and electrical characteristics are good. Gender was found to be achieved in good balance.

[0006]

[Chemical 2] (Wherein 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, carbon number 1 to
4 is an alkoxysilyl group-containing silyl group, a and b are positive numbers satisfying 0.8 <a <1.1 and 0 <b <2, respectively, and n is an integer of 3 or more and 1000 or less. )

Therefore, the present invention is based on the above average composition formula (1).
And 100 parts of the organopolysiloxane represented by the above formula and 0.1 of the organopolysiloxane represented by the above average composition formula (2).
A method for producing a molded silicone resin article, which comprises heat-molding a silicone resin composition containing a mixture with 10 parts by weight or a cohydrolyzate thereof together with a molding auxiliary material in the presence of a catalyst or without a catalyst. And a silicone resin molded article obtained therefrom.

The present invention will be described in more detail below. 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 compositional formula (1) or a hydrolyzed group. It is an organopolysiloxane having possible alkoxy groups.

[0009]

[Chemical 3] (However, in the formula, 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 0.8 <a <1. 1,0 <b
It is a positive number that satisfies <2. )

Here, as R ¹ in the formula, for example, a methyl group, an ethyl group, a phenyl group and the like can be mentioned. Particularly, from the viewpoint of heat resistance, the methyl group is preferable. The number a of R ¹ is 0.8 from the viewpoint of 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, it becomes a hard but brittle cured product, and when a is 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, and thus the OR ² group is a silanol group, a methoxy group, an ethoxy group, an isopropoxy group, an isobutoxy group or another alkoxy group, A methoxy group, an ethoxy group, and an isopropoxy group are preferable from the viewpoint of reactivity, particularly hydrolyzability. Furthermore, b is a positive number that satisfies 0 <b <2, and represents the content rate of these functional groups. Formula (1)
It is impossible for b = 0 to cure the organopolysiloxane of 2 above to form a molded product. If b is larger than 2, a large amount of alkoxy groups remain after the molded product is formed, and sufficient water resistance can be obtained. Absent.

The molecular weight of the organopolysiloxane of the above formula (1) is preferably 1000 to 100,000 from the viewpoint of workability. If it is less than 1000, it may volatilize during molding, and if it exceeds 100,000. The strength of the article may decrease.

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

[0014]

[Chemical 4] (However, in the formula, R ¹ is the same as above, X is a hydrogen atom,
An alkyl group having 1 to 4 carbon atoms, an epoxy group-containing silyl group,
An amino group-containing silyl group and 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 functional groups capable of reacting with the functional groups of the organopolysiloxane of the formula (1) at both ends thereof. It is an important component for improving mechanical strength. That is, the organopolysiloxane of formula (2) is
Since it has two or more functional groups in one molecule, it acts as a crosslinking agent, and its linear structure is introduced into an organopolysiloxane mainly composed of trifunctional siloxane units of the formula (1) to form a block structure. It is expected that the partial formation will reduce the brittleness of the molded article and improve the strength, and the linear silicone oil-like structure imparts water repellency and improves water resistance. . Therefore, 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 mentioned above, but is preferably a methyl group from the viewpoint of water resistance, heat resistance and cost. X
Is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an epoxy group-containing silyl group, an amino group-containing silyl group, or an alkoxysilyl group-containing silyl group.
SiR ² _m R ³ _3-m (wherein 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. .About.3). Specifically, the following can be exemplified as X.

[0017]

[Chemical 5]

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

The organopolysiloxane of the above formula (2) may be used alone or in combination of two or more, and the compounding amount thereof is 100 parts of the organopolysiloxane of the formula (1). With respect to 0.1 to 10 parts, preferably 0.2 to 5 parts. If the blending amount is less than 0.1 part, the water resistance improving effect is not so remarkable, and if it is added in excess of 10 parts, no further effect can be expected and hardness is lowered.

The composition of the present invention may contain a cohydrolyzate of the above-mentioned organopolysiloxanes of the formulas (1) and (2). In this case, the alkoxy functional groups possessed by the organopolysiloxane are those that form and reduce siloxane bonds during heat molding, and when the organopolysiloxane contains a large number of alkoxy groups, even if heat molding is performed to some extent. Since the alkoxy group may remain and adversely affect the water resistance, it is effective to reduce the content of the alkoxy group by co-hydrolyzing the organopolysiloxane in advance.

The above-mentioned co-hydrolysis can be carried out by using a general method of hydrolyzing an organoalkoxysilane to produce an organopolysiloxane, for example, X in the organopolysiloxane of the formula (2) is alkoxy. 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 which is the theoretical amount necessary for hydrolytically condensing all alkoxy groups.
Is suitable, and the reaction conditions are 10 to 150 ° C. and 0.5 to
10 hours is preferred. If necessary, a solvent such as toluene, xylene, methanol, isopropyl alcohol, isobutanol, acetone or ethyl acetate can be used. After the reaction, it is desirable to remove the catalyst by neutralization, washing with water or the like.

In the present invention, a silicone composition containing a mixture of the organopolysiloxanes of the above formulas (1) and (2) or a cohydrolyzate thereof is used as a molding auxiliary material in the presence or absence of a condensation accelerating catalyst. It is heat-molded together with it to obtain a molded article.

Examples of the condensation accelerating catalyst include phosphoric acid, phosphoric acid esters, organic metal salts of aluminum, zinc, titanium and the like. Particularly, when mica foil is used as a molding auxiliary material, phosphoric acid is used. It is preferable to use a phosphoric acid ester in order to improve moldability and mechanical properties. The amount of catalyst added may be a normal amount.

As the auxiliary molding material, for example, an inorganic material such as mica foil or glass fiber is preferably used.
Further, as a molding auxiliary material, an inorganic filler such as silica powder or mica powder can be added to the silicone composition of the present invention, mixed, cast, and heat-cured, whereby a good molded article can be obtained. . Others as auxiliary material for molding,
Inorganic powders such as red iron oxide, talc, alumina, calcium carbonate, barium sulfate, aluminum hydroxide and zinc carbonate can also be mixed if necessary.

The amount of these auxiliary molding materials used is 50 to 100 parts of the organopolysiloxane of the formula (1).
It is preferably 2000 parts.

In the present invention, the heat molding method may be a method generally used in industry.
For example, the organopolysiloxane of the formulas (1) and (2) is diluted with a solvent, and this is impregnated with a molding auxiliary material by spraying or dobbing. In this case, it is preferable to adjust the dilution rate in advance in consideration of the amount of impregnation and workability. Further, in order to remove the solvent, it is dried at 50 to 100 ° C. for 5 to 20 minutes, and then a molding auxiliary material is layered so as to have a desired thickness, and the condition is 100 to 200 ° C. and 5 to 50 kg / cm ² . ．
A molded product can be obtained by press-curing for 5 to 5 hours.

[0027]

The molded silicone article of the present invention has excellent water resistance and mechanical strength, as well as excellent heat resistance and electrical characteristics, and can be widely used as an electrical insulating material.

[0028]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 6 and 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 water was added dropwise at 25 ° C. with stirring for 30 minutes. Then, the temperature rose to 35 ° C. After stirring for 1 hour at this temperature, 1
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 3 times to stop the reaction. 20 g of anhydrous sodium sulfate was added, and the mixture was stirred at 25 ° C. for 5 hours and then filtered to obtain 330 g of a methylpolysiloxane solution. This solution contains 40% of resin solid content of the following formula [I], and the functional group content based on the resin solid content is silanol group 4
% And an isopropoxy group was 3%.

[0030]

[Chemical 6] The above-mentioned methyl polysiloxane solution was used as the organopolysiloxane of the formula (1), and those shown in Table 1 were used as the organopolysiloxane of the formula (2) and mixed at the compounding ratio shown in Table 1. Furthermore, 2% of orthophosphoric acid was added to the resin weight, and the resin concentration was diluted to 20% with isopropanol.

Next, this liquid was sprayed onto the mica foil so that the resin content was 10%, dried at 100 ° C. for 10 minutes, and then 10 sheets were stacked to form a molding pressure of 20 kg / cm ² , 1
It was press-cured under the condition of 80 ° C. to obtain a mica molded product having a thickness of 0.5 mm. Using this as a test piece, mechanical strength (flexural strength), water resistance (flexural strength residual rate after boiling and immersion), electrical characteristics (volume resistivity), and heat resistance (smoke resistance) were evaluated by the following methods. The results are shown in Table 1.

Mechanical strength (bending strength): 25 mm × 50 m
m, 0.5 mm thick test piece is used, distance between fulcrums is 40
The bending strength was calculated from the maximum load at the time of breaking under the conditions of mm and the setting speed of 50 mm / min.

Water resistance (bending strength residual ratio after boiling and immersion): 2
Using a test piece of 5 mm x 50 mm and a thickness of 0.5 mm,
Bending strength after boiling for 1 hour is measured by the same method as above,
The flexural strength of the test piece after boiling / the flexural strength of the test piece before boiling were evaluated as the residual rate according to the following criteria. ◎ Remaining rate of 60% or more ○ Remaining rate of 30 to 60% △ Remaining rate of 30% or less

Electrical Properties (Volume Resistivity): The volume resistivity of the test piece was measured, and one having a volume resistance 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 of No. 1 at equal intervals, charged with AC60V, and the smoke generation state was observed, and evaluated according to the following criteria. ○ No smoke △ Slight smoke

[0036]

[Table 1]

[0037]

[Chemical 7]

[Examples 7 to 9 and Comparative Examples 5 and 6] 500 g of the compound represented by the following formula, and the compound shown in Table 2 was used as the organopolysiloxane of the formula (2). Charge to a liter flask and add 20 more toluene.
0 g was added, and 40 g of 10% hydrochloric acid water was added dropwise while stirring for 30 minutes. The internal temperature rose from 20 ° C to 40 ° C.

[0039]

[Chemical 8]

After stirring at this temperature for 1 hour, 200 g of 10% Glauber's salt hot water was added to stop the reaction. After 10 minutes of stirring, the washing operation for removing the lower aqueous phase was repeated 3 times.
20 g of anhydrous sodium sulfate was added, and the mixture was stirred at 30 ° C. for 5 hours and then filtered to obtain an organopolysiloxane solution.

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

Then, the mica foil was treated in the same manner as in Example 1,
I got a mica molding. Various evaluations were performed using this mica molded product as a test piece. The results are shown in Table 2.

[0043]

[Table 2]

[0044]

[Chemical 9]

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% hydrochloric acid water was stirred for 30 minutes. The mixture was added dropwise, and stirring was continued for another hour. The temperature is 20 ℃
To 35 ° C. Next, 200 g of 10% Glauber's salt hot water was added, and after 10 minutes of stirring, the washing operation of removing the lower aqueous phase was repeated 3 times to stop the reaction. 20 g of anhydrous sodium sulfate was added, and the mixture was stirred for 5 hours and then filtered to obtain a methylphenylpolysiloxane solution. This solution contained 40% of resin solid content of the following formula [II], and the functional group content was 5% silanol group, 3% ethoxy group, and 2% methoxy group based on the resin solid content.

[0046]

[Chemical 10] The same procedure as in Example 1 was carried out except that the above-mentioned methylphenylpolysiloxane was used as the organopolysiloxane of the formula (1), the one shown in Table 3 was used as the organopolysiloxane of the formula (2), and the compounding ratio of Table 3 was used. I got a mica molding. Various evaluations were performed using this mica molded product as a test piece. The results are shown in Table 3.

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

[0048]

[Table 3]

[0049]

[Chemical 11]

Claims (3)

[Claims] 1. 100 parts by weight of an organopolysiloxane represented by the following average composition formula (1) and the following average composition formula (2):
Of 0.1 to 10 parts by weight of organopolysiloxane or a silicone resin composition containing a co-hydrolyzate thereof is heat-molded together with a molding auxiliary material. Production method. [Chemical 1] 2. The method for producing a silicone molded article according to claim 1, wherein the organopolysiloxane of the formula (2) has a molecular chain whose both ends are blocked with di- or trialkoxysilyl groups. 3. A silicone molded article obtained by the method according to claim 1 or 2.