JPH05339505A - Curable silicone composition and cured product thereof - Google Patents

Abstract

PURPOSE:To obtain the title composition which gives a cured product having excellent solvent and moisture resistance and a low surface energy by mixing a specific organopolysiloxane with an organohydrogenpolysiloxane and a catalyst comprising a platinumgroup metal. CONSTITUTION:An organopolysiloxane having, per molecule, 2 or more Si- bonded alkenyl groups, 1 or more Si-bonded fluorinated substituents selected from among the groups represented by formulae I and II (wherein m is 1-4 and n is 1-6), and 1 or more Si-bonded fluorinated substituents selected from among the groups represented by formula III (wherein j is l-12 and k is 1-4) is mixed with an organohydrogenpolysiloxane having 2 or more Si-bonded hydrogen atoms per molecule and with a catalyst comprising a platinumgroup metal to thereby obtain the title composition. It gives a cured product having excellent solvent and moisture resistance and a low surface energy and is useful for producing an oil seal, O-ring, packing, mold release, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable silicone composition having excellent solvent resistance, low moisture permeability, excellent moisture resistance and capable of forming a cured coating having a small surface energy, and a cured product thereof.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Curable silicone compositions are widely used as packings for electronic parts, mold release agents and the like.

However, the conventional curable silicone composition has a main chain of dimethylpolysiloxane and is inferior in solvent resistance and high in water permeability. Therefore, a polymer having a trifluoropropyl group in its side chain has been proposed and is used for various purposes as a polymer having excellent solvent resistance under the name of fluorosilicone. However, this cured product of fluorosilicone has a problem that the surface energy thereof is higher than that of the cured product of dimethylpolysiloxane and the mold releasability is inferior, and improvement of these problems has been desired.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a curable silicone composition which is excellent in solvent resistance and moisture resistance and gives a cured film having a low surface energy, and a cured product thereof.

[0005]

Means and Actions for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventor has at least two alkenyl groups bonded to a silicon atom in one molecule and has one molecule. The following formula (I) bonded to a silicon atom in
And an organopolysiloxane having at least one fluorine-containing substituent selected from the groups represented by (II) and at least one fluorine-containing substituent represented by the following formula (III):
An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule,
By blending with a platinum group metal-based catalyst, it is excellent in solvent resistance with less volume swelling even when immersed in various solvents.
The inventors have found that a curable silicone composition having low moisture permeability, excellent moisture resistance, and capable of forming a cured coating having a small surface energy can be obtained, and thus the present invention has been accomplished.

[0006]

[Chemical 2] (However, in the formula, m is an integer of 1 to 4, n is an integer of 1 to 6, j
Is an integer of 1 to 12, and k is an integer of 1 to 4. )

Therefore, the present invention (1) has at least two alkenyl groups bonded to a silicon atom in one molecule,
And each has at least one fluorine-containing substituent selected from the groups represented by formulas (I) and (II) bonded to a silicon atom and one fluorine-containing substituent represented by formula (III) in one molecule. Organopolysiloxane, (2)
Organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule,
(3) A curable silicone composition containing a platinum group metal-based catalyst and a cured product thereof.

The present invention will be described in more detail below. The organopolysiloxane as the first component of the curable silicone composition of the present invention has at least two alkenyl groups bonded to silicon atoms in one molecule, and A fluorine-containing substituent (hereinafter referred to as Rf ¹ ) selected from groups represented by the following formulas (I) and (II) bonded to a silicon atom in one molecule, and a fluorine-containing substituent represented by the following formula (III) (Hereinafter, Rf
² )) and at least one each.

[0009]

[Chemical 3] (However, in the formula, m is an integer of 1 to 4, n is an integer of 1 to 6, j
Is an integer of 1 to 12, and k is an integer of 1 to 4. )

Here, examples of the alkenyl group include a vinyl group, an allyl group, a cyclohexyl group, and the like, and a vinyl group and an allyl group are preferable in terms of practical use.

In the above organopolysiloxane, the content of the fluorine-containing substituents Rf ¹ and Rf ² is usually 5 mol% or more, particularly 10 to 50 mol% of the total organic groups bonded to silicon atoms. Such an amount is preferable.
If the total content of Rf ¹ and Rf ² is less than 5 mol%, the water permeability of the resulting composition may not be sufficiently lowered, and the solvent resistance and releasability may not be sufficiently exhibited.

Specific examples of the organopolysiloxane of the above formula (I) include those represented by the following formula (IV).

[0013]

[Chemical 4] (Here, R ¹ may be the same or different and is an alkenyl group such as vinyl and allyl; R ² may be the same and different and has 1 to 8 carbon atoms such as methyl, ethyl, propyl and butyl. Is an alkyl group or an aryl group such as a phenyl group, Rf ¹ and Rf ² are as defined above, and n, w, x, y and z are each 0 ≦ n <≦ 3.
It is an integer of w ≧ 0, x ≧ 1, y ≧ 1, z ≧ 0. )

Further, among the organopolysiloxanes of the above formula (IV), those of which the both ends shown by the following formula (V) are terminated by vinyl groups are highly practical and are preferably used.

[0015]

[Chemical 5] (Where R ² , Rf ¹ and Rf ² and w, x, y and z
Is as defined in the above formula (IV). )

The organopolysiloxane of the above formula (V) is, for example, an organocyclotrisiloxane having a fluorine-containing substituent represented by the following general formula (VI) and a terminal vinyl group-terminated organopolysiloxane represented by the following general formula (VII). Siloxane and, if necessary, organocyclotrisiloxane represented by the following general formulas (VIII) and (IX) are polymerized by a known equilibration reaction using an acid or an alkali as a catalyst at an appropriate ratio according to the purpose. It can be manufactured.

[0017]

[Chemical 6](However, in the formula R², Rf Are as described above,
Vi is a vinyl group, and m is an integer of 1 or more. )

In the above-mentioned polymerization reaction, a ring-opening polymerization catalyst such as a lithium catalyst or a pentacoordinate silicon catalyst represented by the following formula (X) is used as a polymerization catalyst, and the end of the polymer obtained after the polymerization is By treating with the organosilicon compound represented by the general formula (XI), a polymer having a very low content of low molecular siloxane can be produced.

[0019]

[Chemical 7]

It should be noted that the formula (V
The organocyclotrisiloxane having a fluorine-containing substituent of I) is, for example, a disiloxanediol represented by the following general formula (XII) and a dichlorosilane represented by the following general formula (XIII) in the presence of a tertiary amine such as triethylamine. It can be synthesized by reacting below (see Japanese Examined Patent Publication No. 3-7558).

[0021]

[Chemical 8] (Here, R ² and Rf are as described above.)

The second component of the composition of the present invention, organohydrogenpolysiloxane, contains at least two hydrogen atoms bonded to silicon atoms in one molecule.

Specific examples of the above organohydrogenpolysiloxane include R ² HSiO units and HSiO _1.5.
Unit, (R ² ) ₂ SiO unit, R ² SiO _1.5 unit,
(R ² ) ₂ HSiO _0.5 unit, (R ² ) ₃ SiO _0.5 unit, R
Examples of the polymer include ² RfSiO units and RfSiO _1.5 units (wherein R ² is as described above and Rf is Rf ¹ or Rf ^{2 as} described above), which may be linear, branched or cyclic. It may be one. Among these, those represented by the following general formula (XIV) or (XV) are suitable for practical use.

[0024]

[Chemical 9] (However, R ³ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a phenyl group, and R ⁴ may be the same or different, and is an alkyl group having 1 to 8 carbon atoms, a phenyl group or the above formula. It is at least one selected from the fluorine-containing substituents represented by (I) to (III), p and q are integers of p ≧ 1 and q ≧ 0, respectively, provided that p is silicon in one molecule. The number of hydrogen atoms bonded to an atom is 3 or more.)

[0025]

[Chemical 10] (However, R ⁴ is the same as above, Rf ³ is a divalent perfluoroalkylene group or a divalent perfluoropolyether group, n
Is an integer of 1 to 3. )

The divalent perfluoroalkylene group and the perfluoropolyether group are exemplified below.

[0027]

[Chemical 11]

The mixing ratio of the first component and the second component in the composition of the present invention is such that one alkenyl group bonded to the silicon atom in the first component is the hydrogen atom bonded to the silicon atom in the second component. Is at least 0.5, and in particular, the ratio of alkenyl groups bonded to silicon atoms in the first component to hydrogen atoms bonded to silicon atoms in the second component is 1: 0.5.
It is preferable that the ratio is ˜1: 10, particularly 1: 1 to 1: 5.

The composition of the present invention contains a platinum group metal-based catalyst as a third component for the addition reaction of the first component and the second component. Examples of the platinum group metal-based catalyst include platinum, rhodium, platinum group metals such as iridium and compounds thereof, preferably chloroplatinic acid, various olefins with chloroplatinic acid and complex salts with vinylsiloxane, platinum black, Examples include various carriers carrying platinum.

The addition amount of the platinum group metal catalyst of the third component is usually the amount used in a curable silicone composition utilizing this type of addition reaction, that is, the total weight of the first component and the second component. The amount of platinum is preferably in the range of 1 to 1,000 ppm.

The composition of the present invention can be obtained by blending the predetermined amounts of the above-mentioned first to third components, but various organic nitrogens for the purpose of suppressing the activity of the platinum group metal catalyst of the third component. A compound, an organic phosphorus compound, an acetylene-based compound, an oxime compound, an organic chloro compound, and the like may be added as necessary as an activity inhibitor.

Furthermore, the composition of the present invention has a reduction in heat shrinkage during curing, a decrease in thermal expansion coefficient of the obtained cured elastic body, thermal stability, weather resistance, chemical resistance, flame retardancy or mechanical strength. Other fillers may be added for the purpose of improving the gas permeability and decreasing the gas permeability. As this filler,
Examples thereof include fumed silica, quartz powder, glass fiber, carbon, metal oxides such as iron oxide, titanium oxide and cerium oxide, and metal carbonates such as calcium carbonate and magnesium carbonate. If necessary, it is possible to add an appropriate pigment, dye or antioxidant.

The composition of the present invention thus obtained is poured into a molding die or the like and subjected to known techniques such as room temperature curing, heat curing, and ultraviolet curing, preferably at 25 ° C. for 24 hours or more or at 100 ° C. for example. A rubber-like elastic body can be obtained by curing it by heat treatment for 30 seconds or more.

The composition of the present invention may be diluted with an appropriate organic solvent such as chlorofluorocarbon, xylene hexafluoride, perfluorooctane, benzotrifluoride, methyl ethyl ketone, etc., depending on the workability during use. Good.

The curable silicone composition of the present invention thus obtained gives a cured product excellent in solvent resistance, low hygroscopicity and releasability, and therefore, for example, for oil seals, O-rings and electronic parts. It can be used as various release agents such as packing, release paper, and molding material.

[0036]

The curable silicone composition of the present invention provides a cured product having excellent solvent resistance and moisture resistance and a small surface energy, and is useful as an oil seal, an O-ring, a packing, a mold release material and the like. is there.

[0037]

EXAMPLES The present invention will be specifically described below with reference to synthesis examples, examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, all parts are parts by weight.

[Synthesis Example] Cyclotrisiloxane having a fluorine-containing substituent represented by the following general formula (i) and cyclotrisiloxane represented by the following general formula (ii) are mixed at a molar ratio of 50:50. did.

[0039]

[Chemical formula 12]

Next, 0.1 part of tetraglyme, 0.1 part of water and 0.1 part of lithium siliconate represented by the following formula were added to 100 parts of the obtained mixture, and the mixture was stirred at 100 ° C. for 3 hours. After addition of lithium siliconate, the viscosity increased in about 30 minutes and became a viscous liquid in 3 hours.

[0041]

[Chemical 13]

To this viscous liquid was added tetrachloroethane 0.3
g was added, and the mixture was stirred at 100 ° C. for 3 hours, filtered, and stripped to obtain a polymer having a viscosity of 6820 cs (25 ° C.) and having the following structural formula.

[0043]

[Chemical 14]

Further, 4.5 parts of silylketene acetal having the following structural formula was added to 100 parts of the above polymer, and the mixture was heated at 70 ° C. for 4 hours.
After reacting for a period of time, the ethyl acetate produced by condensation was distilled off to obtain a vinyl group-containing organopolysiloxane represented by the following structural formula (iii) having a viscosity of 6540 cs (25 ° C.).

[0045]

[Chemical 15]

[0046]

[Chemical 16]

In the same manner as above, organopolysiloxanes having Rf ¹ , Rf ² , X and Y in the following structural formula (A) as shown in Tables 1 and 2 were synthesized.

[0048]

[Chemical 17]

[0049]

[Table 1]

[0050]

[Table 2]

Examples 1 to 10 and Comparative Example 1 100 parts of vinyl group-containing organopolysiloxanes (1) to (10) or organopolysiloxane (11) obtained by a synthesis example as shown in Table 3, surface 15 parts of fumed silica having a specific surface area of 200 m ² / g treated with trimethylsiloxy was heated and mixed with a kneader at 150 ° C. for 2 hours. This mixture was passed through a triple roll once to form a base. This base 1
In 000 parts, 4.8 parts of hydrogen siloxane represented by the following formula and chloroplatinic acid were added as CH ₂ = CHSi (CH ₃ ) ₂ OSi (CH ₃ ).
0.2 parts of a toluene solution of a catalyst modified with ₂ CH = CH ₂ (platinum concentration 1.0% by weight) and 0.3 parts of 2-ethynylisopropanol were added and mixed.

[0052]

[Chemical 18] (In the above formula, Rf ¹ is the same as described above.)

This was degassed under reduced pressure, placed in a rectangular frame having a thickness of 2 mm, and evacuated again to 100 kg / cm ² ,
It was press-cured at 150 ° C. for 15 minutes. The test piece was cut from the cured sample, and the rubber physical properties were measured according to JIS K6301 "Vulcanized rubber physical test method".

Further, the water vapor permeability was measured according to JIS Z 0208 "Moisture Permeability Test Method for Moisture-Proof Packing Material", and the solvent swellability was immersed in a solvent at 25 ° C for 48 hours,
The volume change rate before and after immersion was measured.

Next, the surface contact angle on this sheet was measured with pure water and silicone oil (viscosity 10 cs).
The above results are shown in Tables 3-5.

[0056]

[Table 3]

[0057]

[Table 4]

[0058]

[Table 5]

From the results in Table 3, the silicone composition of the present invention has a lower moisture permeability than the comparative composition, and from the results in Table 4, the comparative composition has a swelling ratio in acetone and ethyl acetate. On the other hand, it was found that the composition of the present invention had a low swelling rate and was excellent in solvent resistance, while it was high.

Further, from the results shown in Table 5, the comparative composition has a contact angle of 0 ° with respect to silicone oil (10 cs), whereas the composition of the present invention has a contact angle of 10 ° or more, and thus the surface energy is small. I understood it.

Example 11 All of Examples 1 to 10 except that the vinyl group-containing organopolysiloxane (1) obtained in the synthesis example was used and 5.2 parts of the hydrogen siloxane represented by the following formula was used. Compounding and preparation of test pieces were carried out in the same manner as in, and the physical properties were measured. The results shown in Table 6 were obtained.

[0062]

[Chemical 19]

[0063]

[Table 6]

From the results shown in Table 6, the composition of the present invention (Example 1)
It was confirmed that 1) had low water vapor transmission rate, low solvent swelling rate, and low surface energy.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Yamaguchi Izumi Hitomi, Matsuida Town, Usui District, Gunma Prefecture 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (2)

[Claims] 1. A group represented by the following formulas (I) and (II) having at least two alkenyl groups bonded to a silicon atom in one molecule and having a silicon atom bonded in one molecule: An organopolysiloxane having at least one fluorine-containing substituent selected and at least one fluorine-containing substituent represented by the following formula (III): (However, in the formula, m is an integer of 1 to 4, n is an integer of 1 to 6, j
Is an integer of 1 to 12, and k is an integer of 1 to 4. (2) A curable silicone composition comprising an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule, and (3) a platinum group metal-based catalyst. 2. A cured product obtained by curing the silicone composition according to claim 1.