JP2000248181A - Curable fluoropolyether rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cured product which is excellent in water repellency, oil repellency, solvent resistance, chemical resistance and weather resistance, and has high tensile strength and tear strength while maintaining high hardness. And a curable fluoropolyether rubber composition. SOLUTION: (A) 100 parts by weight of a linear fluoropolyether compound having at least two alkenyl groups in a molecule and having a perfluoroalkyl ether structure in a main chain, and (B) a specific surface area of 50 m ² / g or more silica-based filler
10-40 parts by weight, (C) fiber diameter 0.2-2μm and fiber length 2-50
2 to 20 parts by weight of whiskers having a fine fiber shape of μm, (D) an organosilicon compound having at least two hydrogen atoms bonded to silicon atoms in the molecule, and (E) a hydrosilylation reaction catalyst. A curable fluoropolyether rubber composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid curable fluoropolyether rubber composition capable of obtaining a cured product having excellent tensile strength and tear strength while maintaining high hardness.

[0002]

2. Description of the Related Art Silica-based fillers such as dry silica (called fumed silica) and wet silica (called precipitated silica) have been used to reinforce silicone rubber and the like. It has been known that, when compounded with a curable fluoropolyether-based rubber composition, the hardness, mechanical strength, heat resistance and the like of the obtained cured product are improved. The fluoropolyether-based rubber composition containing the silica-based filler as described above has appropriate hardness, mechanical strength, heat resistance, etc., as well as the inherent water repellency, oil repellency, chemical resistance, and the like of the fluoropolyether rubber. Since various properties such as solvent resistance and weather resistance are well-balanced, in most applications,
These performances alone are sufficient. On the other hand, in molding applications such as O-rings and diaphragms used for automobiles, aircraft, etc., while maintaining high hardness, mechanical strength,
In particular, a high-strength material excellent in tensile strength and tear strength is required.

[0003]

In the conventional fluoropolyether rubber composition, the hardness and mechanical strength can be improved by increasing the amount of the reinforcing silica filler. There is a limit to the increase in the amount (excessive blending impairs other properties such as water repellency, oil repellency, etc.), and it is difficult to significantly improve the mechanical strength as well as the hardness by using a silica filler alone. As a method for increasing the hardness, it is known to mix a filler such as quartz powder, diatomaceous earth, titanium oxide, and carbon black with a reinforcing fine silica-based filler. In addition, there is a problem that mechanical strength such as tensile strength and tear strength is significantly reduced. Therefore, an object of the present invention is to provide a liquid cured product which is excellent in water repellency, oil repellency, solvent resistance, chemical resistance and weather resistance, and maintains a high hardness while improving a tensile strength and a tear strength. To provide a functional fluoropolyether rubber composition.

[0004]

Means for Solving the Problems The present invention achieves the above object. (A) A straight-chain structure having at least two alkenyl groups in the molecule and having a perfluoroalkyl ether structure in the main chain. 100 parts by weight of a fluoropolyether compound, (B) a silica-based filler having a specific surface area of 50 m ² / g or more 10 to 40 parts by weight, (C) a fine fiber having a fiber diameter of 0.2 to 2 μm and a fiber length of ² to 50 μm Curing comprising 2 to 20 parts by weight of a whisker having a fiber shape, (D) an organosilicon compound having at least two hydrogen atoms bonded to silicon atoms in a molecule, and (E) a hydrosilylation reaction catalyst. Provided is a functional fluoropolyether-based rubber composition.

[0005]

DETAILED DESCRIPTION OF THE INVENTION (A) Linear fluoropolyether compound: The linear fluoropolyether compound of component (A) has at least two alkenyl groups in the molecule and has It has a divalent perfluoroalkyl ether structure and is used as a base polymer of a composition.

The alkenyl group in the linear fluoropolyether compound includes, for example, a group having a CH ₂ ＣＨCH— structure at the terminal such as a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, and a hexenyl group. Particularly, a vinyl group, an allyl group and the like are preferable. The alkenyl groups may be bonded directly to both ends of the backbone of the linear fluoropolyether compound, a divalent linking group, _{e.g., -CH 2 -, - CH 2} O-, or -Y -NR-CO
-(However, Y is -CH ₂ -or

[0007]

Embedded image (O, m or p position), and R is a hydrogen atom, a methyl group,
It is a phenyl group or an allyl group. ) And the like.

The perfluoroalkyl ether structure in the linear fluoropolyether compound may be, for example, a compound represented by the following general formula:-(Rf-O) _q- (wherein Rf has 1 to 6 carbon atoms, preferably A linear or branched perfluoroalkylene group having 1 to 3 atoms, and q is an integer of 1 to 500, preferably 2 to 400, and more preferably 10 to 200.) Can be

The repeating unit represented by-(Rf-O)-includes, for example, -CF ₂ O-, -CF ₂ CF ₂ O
_{-, - CF 2 CF 2 CF} 2 O -, - C (CF 3) FCF 2 O
_{-, - CF 2 CF 2 CF} 2 CF 2 O -, - CF 2 CF 2 CF 2
CF ₂ CF ₂ CF ₂ O—, —C (CF ₃ ) ₂ O—, and the like. Among them, preferred are —CF ₂ O— and —CF ₂ CF _{2.
O -, - CF 2 CF 2} CF 2 O- and -CF (CF ₃₎ CF
₂ O-. The perfluoroalkyl ether structure may be composed of one type of these repeating units represented by-(Rf-O)-or a combination of two or more types. Representative examples of the linear fluoropolyether compound as the component (A) include the following general formula (1):

[0010]

Embedded image [-CH ₂ wherein, X is independently -, - CH ₂ O-, or -Y
-NR-CO- (where, Y is, -CH ₂ - or

[0011]

Embedded image (O, m or p position), and R is a hydrogen atom, a methyl group,
It is a phenyl group or an allyl group. ), P is independently 0 or 1, L is an integer of 2 to 6, and m and n are each an integer of 0 to 200, preferably 5 to 100. And a molecular weight of 400 to 100,000, preferably 1,000 to 50,000. Specific examples of the linear fluoropolyether compound represented by the general formula (1) include those represented by the following formula.

[0012]

Embedded image (Wherein m and n are the same as m and n, respectively, defined in the above general formula (1)) These linear fluoropolyether compounds can be used alone or in combination of two or more.

(B) Silica-based filler: The silica-based filler of the component (B) is used for increasing the hardness and reinforcing the cured product, and has silica particles having a specific surface area of at least 50 m ² / g. It is. Examples of the silica-based filler include fumed silica (dry-process silica) and precipitated silica (wet-process silica), and surface-treated products thereof, for example, those obtained by trimethylsilation of a hydroxyl group bonded to a silicon atom on the surface, Which are subjected to a hydrophobic treatment with dimethylpolysiloxane having a low degree of polymerization. These can be used alone or in combination of two or more. The amount of component (B) is
The amount is 10 to 40 parts by weight, preferably 15 to 30 parts by weight, per 100 parts by weight. If this amount is less than 10 parts by weight, no improvement in mechanical strength is observed, and if it is more than 40 parts by weight, the viscosity increases greatly and it is difficult to mix.

(C) Whisker The whisker of the component (C) is used to improve the tensile strength and the tear strength while controlling the increase in hardness of the cured product due to the component (B). It has a fine fiber shape of 0.2 to 2 μm and a fiber length of 2 to 50 μm. Since each fiber is entangled by this fiber structure, the component (C) can improve the tensile strength and the tear strength while maintaining the high hardness of the elastic body which is a cured product. If the fiber diameter is less than 0.2, there is a concern that the carcinogenicity is high and there is a problem in the work. If it exceeds 2 μm, it is difficult to improve the tensile strength and the tear strength. On the other hand, if the fiber length is less than 2 μm, it is difficult to improve the tear strength, and if it exceeds 50 μm, the compounding becomes difficult. Whiskers having a fine fiber shape include metal whiskers such as chromium, copper, iron, and nickel, silicon carbide (SiC), graphite (C), and silicon nitride (Si ₃
N ₄ ) and other inorganic non-oxide whiskers, and alumina (Al ₂ O
_3), potassium titanate _{(K 2 0 · nTi0 2)} , wollastonite
(CaSi0 _3), aluminum borate _{(9Al 2 O 3 · 2B 2} 0 2), an inorganic oxide whiskers such as zinc oxide (ZnO), although not particularly limited, inorganic oxide in terms of reinforcing Physical whiskers are preferred. The amount of this whisker is (A) component 1
It is 2 to 20 parts by weight, preferably 5 to 15 parts by weight based on 00 parts by weight. If this amount is less than 2 parts by weight, the desired improvement in hardness and tear strength is not recognized, and if it exceeds 20 parts by weight,
This leads to an increase in viscosity, a reduction in elongation and a reduction in tensile strength.

(D) Organosilicon compound containing a hydrogen atom bonded to a silicon atom: The organosilicon compound of the component (D) acts as a crosslinking agent and a chain extender of the component (A). The organosilicon compound of the component (D) has a hydrogen atom bonded to a silicon atom in one molecule, that is, a hydrosilyl group (SiH
It is not particularly limited as long as it has two or more groups, but in consideration of compatibility with component (A), dispersibility and uniformity after curing, one or more 1 Having a monovalent perfluorooxyalkyl group, a monovalent perfluoroalkyl group, a divalent perfluorooxyalkylene group or a divalent perfluoroalkylene group, and having two or more, preferably three or more hydrosilyl groups. Are preferred. The perfluorooxyalkyl group, perfluoroalkyl group, perfluorooxyalkylene group and perfluoroalkylene group include, in particular, rice represented by the following general formula.

<Monovalent perfluoroalkyl group> C _m F _{2m + 1-} (where m is an integer of 1 to 20, preferably 2 to 10) <Divalent perfluoroalkylene group> -C _m F _2m − (where m is an integer of 1 to 20, preferably 2 to 10) <Monovalent perfluorooxyalkyl group>

[0017]

Embedded image (However, n is an integer of 1 to 5.)

[0018]

Embedded image (However, n is an integer of 1 to 5.) <Divalent perfluorooxyalkylene group>

[0019]

Embedded image (Where m is an integer of 1 to 50, n is an integer of 1 to 50, and m
+ N satisfies 2 to 100. )

[0020]

Embedded image (However, m and n are each an integer of 1 to 50.)

The divalent linking group for connecting the perfluoroalkyl group, perfluorooxyalkyl group, perfluoroalkylene group or perfluorooxyalkylene group with the silicon atom includes an alkylene group, an arylene group and a combination thereof. Or a group in which an ether bond oxygen atom, an amide bond, a carbonyl bond, or the like is interposed in these groups. For example, -CH ₂ CH _{2
-, - CH 2 CH 2 CH} 2 -, - CH 2 CH 2 CH 2 OCH 2
_{-, - CH 2 CH 2 CH} 2 -NH-CO -, - CH 2 CH 2
CH ₂ —N (Ph) —CO— [where Ph is a phenyl group. _{], -CH 2 CH 2 CH 2 -N} (CH 3) -CO
_{-, - CH 2 CH 2 CH} 2 -O-CO- or the like, include those having 2 to 12 carbon atoms.

The organosilicon compound (B) contains a monovalent or divalent fluorinated substituent, that is, a perfluoroalkyl group, a perfluorooxyalkyl group, a perfluoroalkylene group or a perfluorooxyalkylene group. Examples of a monovalent substituent other than a monovalent organic group to be bonded to a silicon atom include a methyl group, an ethyl group,
Alkyl groups such as propyl, butyl, hexyl, cyclohexyl, octyl, and decyl; vinyl;
An alkenyl group such as an allyl group; an aryl group such as a phenyl group, a tolyl group or a naphthyl group; an aralkyl group such as a benzyl group or a phenylethyl group; and at least a part of hydrogen atoms of these groups is a chlorine atom, a cyano group, or the like. A substituted or unsubstituted or substituted hydrocarbon group having 1 to 20 carbon atoms such as a chloromethyl group, a chloropropyl group and a cyanoethyl group is exemplified.

The organosilicon compound as the component (D) may be any of a cyclic, chain, three-dimensional network, and a combination thereof. The number of silicon atoms of the organosilicon compound is not particularly limited, but is usually 2 to 60, preferably 3 to 30.
It is about. Examples of such an organosilicon compound include the following compounds. In the following formula, Me represents a methyl group and Ph represents a phenyl group. In addition, these compounds can be used individually by 1 type or in combination of 2 or more types.

[0024]

Embedded image (However, m is an integer of 1 to 20, average 10; n is 1 to 10, average 6
Is an integer. )

[0025]

Embedded image

[0026]

Embedded image

[0027]

Embedded image (However, S is

[0028]

Embedded image And n is an integer of 1 to 30, m is an integer of 1 to 30, and n + m satisfies 2 to 60, and satisfies an average of 2 to 50. ),

[0029]

Embedded image (However, S is

[0030]

Embedded image And n is an integer of 1 to 30, m is an integer of 1 to 30, and n + m satisfies 2 to 60, and satisfies an average of 2 to 50. ),

[0031]

Embedded image (However, n represents an integer of 1 to 60 and an average of 3 to 50.)

[0032]

Embedded image (However, n represents an integer of 1 to 60 and an average of 3 to 50),

[0033]

Embedded image (However, n represents an integer of 1 to 60 and an average of 3 to 50),

The compounding amount of the above component (D) depends on the whole composition, especially
Hydrosilyl group in component (D) is preferably 0.5 to 5 mol, more preferably 0.5 to 5 mol, per mol of alkenyl group such as vinyl group, allyl group and cycloalkenyl group contained in component (A).
The amount is 1 to 2 mol. If the amount of the hydrosilyl group in the component (D) is too small, the degree of crosslinking becomes insufficient.If the amount is too large, the chain length is prioritized and curing becomes insufficient, foaming occurs, heat resistance, and compression set characteristics. Etc. may worsen. The amount of the component (D) is usually the same as the component (A) 10
It may be in the range of 0.1 to 50 parts by weight relative to O parts by weight.

(E) Hydrosilylation reaction catalyst: As the hydrosilylation reaction catalyst of component (E), a transition metal such as Pt,
Examples thereof include platinum group metals such as Rh and Pd, and compounds of these transition metals. These compounds are generally noble metal compounds and are expensive, but platinum compounds are preferred because they are relatively easily available.

Examples of the platinum compound include chloroplatinic acid;
Complexes of chloroplatinic acid with olefins such as ethylene; chloride white
Complex of gold acid and alcohol or vinyl siloxane;
Examples of platinum supported on carriers such as mosquito, alumina, and carbon
But not limited to
No. As platinum group metal compounds other than platinum compounds,
, Ruthenium, iridium and palladium compounds
Object, such as RhCl (PPh_Three) _Three, RhCl (CO) (PPh_Three)_Two, RhCl (C_TwoH_Four)
_Two, Ru_Three(CO)₁₂, IrCl (CO) (PPh_Three)_Two, Pd (PPh_Three)_FourEtc. (upper formula
In the above, Ph represents a phenyl group. ).

The use amount of these catalysts is not particularly limited, and a desired curing rate can be obtained with a so-called catalyst amount. However, in order to obtain an economical viewpoint or a good cured product, the curable composition must be used. 0 in terms of platinum group metal based on the total amount of
It is preferably in the range of about 1 to 1,000 ppm (weight), particularly about 0.1 to 500 ppm (weight). Other components: The composition of the present invention includes the components (A) to (A) described above.
In addition to the component (E), various conventionally known additives can be blended as optional components as long as the effects of the present invention are not impaired. Such components include, for example, 1-ethyl-1-hydroxycyclohexane, 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyne-
3-ol, 3-methyl-1-penten-3-ol,
Acetylene alcohol such as phenylbutynol and 3-
Methyl-3-penten-1-yne, 3,5-dimethyl-
A control agent for a hydrosilylation reaction catalyst such as 3-hexen-1-yne;

[0038]

Embedded image Adhesion-promoting agents such as organosiloxanes having an alkoxy group, an epoxy group and a SiH group in the molecule thereof; coloring agents such as pigments (eg, iron oxide, cerium oxide, carbon black, etc.) and dyes; antioxidants; Can be

Composition of the composition: The composition of the present invention may be constituted as a so-called one-pack type in which all of the essential components (A) to (E) are handled as one composition depending on the use. Or, for example, a part of the component (A);
A part of the component (B), a part of the component (C) and the component (D) constitute one composition, and the balance of the component (A), the balance of the component (B), the balance of the component (C), and (E) ) The component may be constituted as a so-called two-pack type, in which the component is the other composition, and these may be mixed at the time of use. Curing: The composition of the present invention can be easily cured by standing at room temperature or by heating, but is usually heated at room temperature (for example, 10 to 30 ° C.) to 180 ° C. for 5 minutes to 24 hours. It is preferable to cure it.

[0040]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. All parts in the examples represent parts by weight, and Me in the formula represents a methyl group. -Example 1-The following formula (2):

[0041]

Embedded image [However, Rf ¹ is

[0042]

Embedded image (Where x is an integer of 40 to 60, y is an integer of 40 to 60, and x + y is 80 to 120, satisfying an average of 97). ] Linear fluoropolyether compound (viscosity 4.4Pa /
s, average molecular weight 16,500, vinyl group content 0.102 mol / 100g) 100
In the section, trimethylsilylation-treated fumed silica (Musil 130A, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silica-based filler
25 parts were added and mixed and heat-treated at 150 ° C. for 2 hours. Next, 10 parts of potassium titanate whisker (Tismo, manufactured by Otsuka Chemical Co., Ltd.) having a fiber diameter of 0.3 to 0.6 μm and a fiber length of 0 to 20 μm was added to the heat-treated product, and the mixture was placed on a three-roll mill. Mix,
Further, 0.3 part of a 50% toluene solution of ethynylcyclohexanol and chloroplatinic acid were added to the following formula (3):

[0043]

Embedded image 0.2 part of a toluene solution (platinum concentration 0.5% by weight) of a catalyst modified with the compound represented by the following formula (4):

[0044]

Embedded image 3.33 parts of an organosilicon compound containing a SiH group represented by the formula (1) was added and uniformly mixed on the above-mentioned mill to prepare a curable fluoropolyether composition.

From the obtained composition, a 2 mm-thick sheet-shaped cured product was prepared under the conditions of press curing at 150 ° C. for 10 minutes and further oven curing at 200 ° C. for 4 hours.
It was measured according to lSK6301. Table 1 shows the results.

Comparative Example 1 A curable fluoropolyether composition was prepared in the same manner as in Example 1, except that 20 parts of diatomaceous earth (trade name: Radiolite F, manufactured by Showa Chemical Co., Ltd.) was used instead of 10 parts of potassium titanate whiskers. Was prepared. From the obtained composition, a cured sheet having a thickness of 2 mm was prepared under the curing conditions described in Example 1, and its physical properties were measured according to Jls K6301. Table 1 shows the results.

Comparative Example 2 Instead of 10 parts of potassium titanate whiskers, sedimentable silica (Nipsil LP, trade name, manufactured by Nippon Silica Industry Co., Ltd.) 10
A curable fluoropolyether composition was prepared in the same manner as in Example 1 except that parts were used. From the obtained composition, a cured sheet having a thickness of 2 mm was prepared under the curing conditions described in Example 1, and its physical properties were measured according to Jls K6301. Table 1 shows the results.

[0048]

[Table 1] From the results in Table 1, the hardness of the obtained cured products was almost the same in both the examples and comparative examples, but the tensile strength and tear strength of the cured products of the examples were much higher than those of the comparative examples. It turns out that it is excellent.

[0049]

According to the curable fluoropolyether-based rubber composition of the present invention, a cured product (tensile strength: 100 kgf / cm) having improved tensile strength and tear strength while maintaining high hardness (65 degrees or more). ² or more, tear strength: 25 kgf / cm ² or more). Moreover, it has excellent water repellency, oil repellency, solvent resistance, chemical resistance and weather resistance inherent to fluoropolyether rubber.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 CH051 CP042 CP092 DA017 DA077 DA087 DA117 DE107 DE147 DE187 DF017 DJ007 DJ016 DK007 EX048 EZ009 FA067 FB096 FD016 FD149

Claims (2)

[Claims] (A) 100 parts by weight of a linear fluoropolyether compound having at least two alkenyl groups in a molecule and having a perfluoroalkyl ether structure in a main chain, and (B) a specific surface area of 50 m ^{2 to} 20 parts by weight of a whisker having a fine fiber shape with a fiber diameter of 0.2 to 2 μm and a fiber length of 2 to 50 μm, (D) A curable fluoropolyether rubber composition comprising: an organosilicon compound having at least two hydrogen atoms bonded to silicon atoms in a molecule; and (E) a hydrosilylation reaction catalyst. 2. The method of claim 1, wherein the linear fluoropolyether compound is represented by the following general formula (1): [-CH ₂ wherein, X is independently -, - CH ₂ O-, or -Y
—NR—CO— (where Y is —CH ₂ —, or And R is a hydrogen atom, a methyl group, a phenyl group or an allyl group. ), P is independently O or 1, L is 2
And m and n are each an integer of O to 200. The curable fluoropolyether rubber composition according to claim 1, which is a compound represented by the formula: