JP2001011193A - Production of curable fluoropolyether-based rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having a sufficiently low viscosity and excellent processability by mixing a specific fluoropolyether compound with a specified silica-based filler in a specific ratio, kneading the mixture, compounding the mixture with a polyether compound so as to have a specific compounding ratio and diluting the mixture. SOLUTION: (A) A straight-chain fluoropolyether compound having 0.1-50 Pa.s viscosity at 25 deg.C and containing at least two alkenyl groups in the molecule and a perfluoroalkyl ether structure in the main chain (e.g. a compound of the formula) in an amount of 100 pts.wt. is compounded with (B) 25-60 pts.wt. of a silica-based filler having >=50 m2/g specific surface area. The mixture is kneaded preferably for >=1 hour and further mixed with the component A so as to have a prescribed compounding ratio and diluted to give the objective composition. Fumed silica, and the like, are used as the component B. The fumed silica, and the like, may be treated with a cyclic silazane compound, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to water repellency, oil repellency,
Excellent in solvent resistance, chemical resistance, weather resistance and strength characteristics, LI
The present invention relates to a method for producing a liquid curable fluoropolyether-based rubber composition capable of obtaining a composition having improved processability such as MS moldability.

[0002]

BACKGROUND OF THE INVENTION Problems to be Solved by the Invention
Fumed silica used for reinforcing rubber
Called dry process silica, called precipitated silica
50m specific surface area of wet process silica etc. ^Two/ G or more
Liquid silica-based filler is curable liquid fluoropolyether
The compound of the cured product obtained by blending it with the rubber composition
It is known that mechanical properties can be dramatically improved
You.

[0003] Thus, heat resistance, chemical resistance, solvent resistance,
It is possible to obtain a fluoropolyether rubber excellent in properties such as water repellency, oil repellency, and weather resistance in a well-balanced manner, and this has sufficient performance in most uses.

However, when the above-mentioned silica-based filler is blended with the curable liquid fluoropolyether-based rubber composition, the viscosity sharply increases. The amount was limited.

The present invention has been made in view of the above circumstances, and a curable liquid fluoropolymer capable of obtaining a sufficiently low-viscosity composition even when a silica-based filler having a specific surface area of 50 m ² / g or more is blended. An object of the present invention is to provide a method for producing a polyether-based rubber composition.

[0006]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies to achieve the above object. As a result, (A) the viscosity at 25 ° C. is 0.1 to 50 Pa · s. A linear fluoropolyether compound having at least two alkenyl groups in the molecule and having a perfluoroalkyl ether structure in the main chain. (B) A silica-based filler having a specific surface area of 50 m ² / g or more. In producing the curable liquid fluoropolyether rubber composition as an essential component, the component (B) is blended in the range of 25 to 60 parts by weight with respect to 100 parts by weight of the component (A) and kneading is performed. After that, the above-mentioned component (A) is further blended and subjected to post-dilution so as to have a predetermined blending ratio, whereby the silica-based filler having a specific surface area of 50 m ² / g or more is blended as described above. Also the resulting liquid And it found that the viscosity of the scan is low, leading to completion of the present invention.

Hereinafter, the present invention will be described in more detail.
The method for producing the curable liquid fluoropolyether rubber composition of the present invention comprises: (A) a viscosity at 25 ° C. of 0.1 to 50 Pa · s, having at least two alkenyl groups in a molecule, and Linear fluoropolyether compound having a perfluoroalkyl ether structure in the main chain (B) A silica-based filler having a specific surface area of 50 m ² / g or more is required as an essential component. A method for obtaining the above composition comprising an organosilicon compound having at least two hydrogen atoms bonded to atoms and (D) a hydrosilylation reaction catalyst, wherein the component (A)
After blending the component (B) in the range of 25 to 60 parts by weight with respect to 00 parts by weight and kneading, the component (A) is further blended and post-diluted so as to have a predetermined blending ratio. And obtaining a liquid base.

Here, the components (A) to (D) will be described in detail. (A) Linear fluoropolyether compound The linear fluoropolyether compound used in the present invention comprises:
It has at least two alkenyl groups in the molecule and has a divalent perfluoroalkyl ether structure in the main chain.
As the perfluoroalkyl ether structure, for example, the following general formula-(Rf-O) _q- (wherein, Rf is a straight-chain or branched-chain having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms) And q is an integer of 1 to 500, preferably 2 to 400, and more preferably 10 to 200.).

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 -, - CF (CF 3) CF 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 are preferable. Among them, preferred are —CF ₂ O— and —CF ₂ CF.
_{2 O -, - CF 2 CF} 2 CF 2 O -, - 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 may be a combination of two or more types.

The alkenyl group contained in the linear fluoropolyether compound as the component (A) includes, for example, vinyl group, allyl group, propenyl group, isopropenyl group,
CH ₂ ＣＨCH— at the terminal such as a butenyl group or a hexenyl group
Those having a structure, particularly, a vinyl group, an allyl group and the like are preferable. This alkenyl group may be directly bonded to both ends of the main chain of the linear fluoropolyether compound,
Valent linking group, _{e.g., -CH 2 -, - CH 2} O-, or -
Y-NR-CO- (where, Y is -CH ₂ - group represented by or the following formula, R represents a hydrogen atom, a methyl group, a phenyl group, or an allyl group) bonded through a like Is also good.

[0011]

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Typical examples of the linear fluoropolyether compound used in the present invention include those having a molecular weight of 400 to 100,000, preferably 1,000 to 50,000, represented by the following general formula (1). No.

[0013]

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Specific examples of the fluoropolyether compound represented by the general formula (1) include, for example, those represented by the following formula.

[0015]

Embedded image (However, in the formula, m and n are the same as the above formula (1).)

As the component (A), those having a viscosity at 25 ° C. of 0.1 to 50 Pa · s, particularly 1 to 20 Pa · s are used.

(B) The specific surface area is 50 m ² / g or more.
Silica-based filler Next, the component (B) is used for reinforcing a fluoropolyether-based rubber composition, and the silica-based filler has a specific surface area of at least 50 m ² / g, preferably 100 m ² / g. ² / g or more, more preferably 150 m ² / g or more. The upper limit of the specific surface area is preferably 350 m ² / g or less.
The silica-based filler may be either dry-process silica called fumed silica or wet-process silica called precipitable silica, and the hydroxyl groups bonded to silicon atoms on the surface of the silica-based filler are organochlorosilane. And those treated with a silazane compound or a cyclic silazane compound, or those whose surfaces have been subjected to hydrophobic treatment with dimethylpolysiloxane having a low degree of polymerization.

The amount of the silica filler is 10 to 50 parts by weight, more preferably 15 to 30 parts by weight, per 100 parts by weight of the component (A). (A) Component 100
If the amount is less than 10 parts by weight, the strength is not improved because the amount is too small, and if the amount is more than 50 parts by weight, the increase in viscosity is large and the compounding is difficult.

(C) Hydrogen bonded to a silicon atom in the molecule
Organosilicon Compound Having at least Two Atoms Next, the component (C) of the present invention is an organosilicon compound and acts as a crosslinking agent and a chain extender of the component (A). The organosilicon compound of the component (C) is not particularly limited as long as it has two or more hydrosilyl groups (SiH groups) in one molecule, but the compatibility and dispersibility with the component (A) are not limited. Considering the uniformity after curing, one or more monovalent perfluorooxyalkyl groups in one molecule,
Those having a valent perfluoroalkyl group, a divalent perfluorooxyalkylene group or a divalent perfluoroalkylene group, and having two or more, preferably three or more hydrosilyl groups, that is, SiH groups are preferred. This perfluorooxyalkyl group, perfluoroalkyl group,
As the perfluorooxyalkylene group and the perfluoroalkylene group, those represented by the following general formula can be particularly mentioned.

[0020]

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The divalent linking group for connecting the perfluoro (oxy) alkyl group or perfluoro (oxy) alkylene group to the silicon atom includes an alkylene group,
An arylene group, a combination thereof, or an ether bond oxygen atom, an amide bond, a carbonyl bond, or the like may be interposed therebetween, 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, P
h is a phenyl group. The same applies hereinafter. _{) -CH 2 CH 2 CH 2 -N} (CH 3) -CO -, - CH 2 C
Include those of H ₂ CH ₂ -O-CO- carbon atoms, such as 2 to 12.

The organosilicon compound of component (C) contains a monovalent or divalent fluorine-containing substituent, ie, a perfluoroalkyl group, a perfluorooxyalkyl group, a perfluorooxyalkylene group or a perfluoroalkylene group. Examples of the monovalent organic group bonded to a silicon atom other than the monovalent organic group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a cyclohexyl group, an octyl group, and a decyl group. An alkenyl group such as a vinyl group and an allyl group; an aryl group such as a phenyl group, a tolyl group, and a naphthyl group; an aralkyl group such as a benzyl group and a phenylethyl group; Substituted with a group or the like, for example, a chloromethyl group, a chloropropyl group, a Unsubstituted or substituted hydrocarbon group of 0 and the like.

The organosilicon compound may be cyclic or chain, and may be three-dimensional network. The number of silicon atoms in the molecule of the organosilicon compound is not limited to this, but is usually 2 to 60, preferably 3 to 3
About 0 is mentioned.

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. These compounds may be used alone or in combination.

[0025]

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[0026]

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[0027]

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The compounding amount of the component (C) is determined based on the total amount of the composition,
In particular, the hydrosilyl group in the component (C), that is, the SiH group is preferably 0.1 to 1 mol per alkenyl group such as a vinyl group, an allyl group and a cycloalkenyl group contained in the component (A).
The amount is 5 to 5 mol, more preferably 1 to 2 mol. If the amount is less than 0.5 mol, the degree of crosslinking becomes insufficient, and 5
If the molar ratio is exceeded, the elongation of the chain is prioritized, and curing may be insufficient, foaming may occur, and heat resistance, compression set characteristics and the like may be deteriorated. The amount of the component (C) to be added to the component (A) can usually be in the range of 0.1 to 50 parts by weight based on 100 parts by weight of the component (A).

(D) Hydrosilylation Reaction Catalyst The catalyst of the component (D) used in the present invention includes transition metals, for example, platinum group metals such as Pt, Rh, and Pd, and compounds of these transition metals.

These compounds are generally compounds of noble metals and are expensive, so that platinum group compounds which are relatively easily available are used.

Examples of the platinum compound include chloroplatinic acid or a complex of chloroplatinic acid with an olefin such as ethylene, a complex of alcohol or vinyl siloxane, platinum / silica, alumina or carbon. However, the present invention is not limited to this. As platinum group metal compounds other than platinum compounds, rhodium, ruthenium, iridium and palladium compounds are also known, for example, Rh
Cl (PPh ₃ ) ₃ , RhCl (CO) (PPh ₃ ) ₂ , R
hCl (C ₂ H ₄ ) ₂ , Ru ₃ (CO) ₁₂ , IrCl (C
O) (PPh ₃ ) ₂ , Pd (PPh ₃ ) _{4 and the} like.

The amount of the catalyst used is not particularly limited, and the desired curing rate can be obtained with the amount of the catalyst. However, in order to obtain an economical viewpoint or a good cured product, the curable 0.1 to 1,000 pp based on the total amount of the composition
m (in terms of platinum group metal), more preferably 0.1 to 500
It is good to be in the range of about ppm (same as above).

Other Ingredients In the composition of the present invention, besides the above-mentioned components (A) to (D), various conventionally known fillers and additives are blended within a range not to impair the effects of the present invention. Is optional.

Examples of such a filler include fillers such as diatomaceous earth, quartz powder, titanium oxide, and carbon black. Also, as such additives,
For example, 1-ethyl-1-hydroxycyclohexane,
Acetylene alcohols such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-penten-3-ol, phenylbutynol, and 3-methyl For controlling hydrosilylation reaction catalysts such as -3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; an alkoxy group, an epoxy group and SiH in a molecule of a compound represented by the following formula: Examples thereof include an adhesion-imparting agent such as an organosiloxane having a group, a pigment such as iron oxide, cerium oxide, and carbon black, a coloring agent, a dye, and an antioxidant.

[0035]

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The process for producing a curable liquid fluoropolyether-based rubber composition containing the above-mentioned components according to the present invention comprises: (A) a component having at least two alkenyl groups in its molecule and having 100 parts by weight of a linear fluoropolyether compound having a perfluoroalkyl ether structure is blended with 25 to 60 parts by weight of a silica filler having a specific surface area of the component (B) of 50 m ² / g or more.・ After kneading, (A)
The component is post-diluted, whereby the viscosity of the curable liquid fluoropolyether-based rubber composition can be reduced.

The mixing and kneading of the components (A) and (B) are performed to reduce the viscosity of the rubber composition, and a predetermined amount is kneaded with a kneading device such as a planetary mixer, a gate mixer, and a kneader. Can be done with The mixing ratio of the component (A) and the component (B) is such that the specific surface area of the component (B) is 50 m.
² / g or more, depending on the type of silica-based filler, component (A) 100 parts by weight, component (B) component 25 to
It is necessary to be 60 parts by weight, and if it is less than 25 parts by weight, it is difficult to reduce the viscosity of the final blended composition, and the viscosity becomes extremely high. On the other hand, when the amount exceeds 60 parts by weight, heat generation during kneading becomes severe, and the mechanical properties of the composition are reduced, and it is difficult to mix the powder with a machine.

The mixing / kneading time is not particularly limited, but is preferably 1 hour or more to uniformly knead.

After blending and kneading, a heat treatment may be performed if necessary. This heat treatment is performed to stabilize the physical properties such as the mechanical properties of the rubber composition. Regarding the heat treatment temperature and time, it is preferable that the temperature is 120 to 180 ° C. and the time is one hour or more.

(A) and (B) obtained as described above.
A curable liquid fluoropolyether rubber composition can be obtained by blending the above components (C) and (D) with a liquid base composed of the components. In this case, the form of the composition is not particularly limited, but includes a one-liquid type and a two-liquid type. In the case of a two-liquid type, the liquid base is divided into two parts, and the component (C) On the other hand, it can be prepared by blending the component (D). In addition,
Components other than the components (A) to (D) are preliminarily (A) and (B)
It may be blended together with the components or may be blended in a liquid base.

The composition of the present invention is particularly effective for the LIMS molding method. In this case, considering the moldability, L
It is preferable to use a two-liquid type that can be molded by an IMS machine. Further, in order to mold with a LIMS machine, the viscosity of the liquid A and the liquid B is 2,000 Pa · s, which can be filled by a machine.
In the following, it is preferable to reduce the difference in viscosity in order to suppress the variation in the amounts of the A liquid and the B liquid.

[0042]

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. In the following examples, parts are parts by weight.

[Embodiment] In this embodiment, LIMS molding
In order to perform the above, the rubber composition is a two-part type, and
Manufactured. Polymer represented by the following formula (2) (viscosity
4.4 Pa · s, average molecular weight 16,500, vinyl group content
0.012 mol / 100g) 100 parts, silica-based filling
Aerosil 300 (made by Nippon Aerosil Co., Ltd.) is annular
Silazane (hexamethylcyclotrisilazane (Shin-Etsu Chemical
Treated silica (specific surface area 190 m)
^Two/ G) in a kneader at a mixing ratio of 30, 40, 50 parts
After mixing, kneading was performed for 1 hour. After kneading, 1
Mixed heat treatment at 70 ° C for 2 hours, each with base (1)
did. This base is combined with a polymer represented by the following formula (2).
The blending ratio (weight ratio) of the treated silica will be 100/20
Formula (2) shown below using a planetary mixer
After diluting and mixing with the polymer, mix with three rolls,
Each was designated as base (2).

(Adjustment of A side) A toluene solution of a catalyst obtained by modifying chloroplatinic acid with a compound represented by the following formula (3) to 100 parts of the base (2) (platinum concentration: 0.5% by weight)
0.4 parts were added and mixed uniformly. (Adjustment of B side) To 100 parts of the base (2), 0.4 part of a 50% toluene solution of ethynylcyclohexanol and 3.33 parts of an organosilicon compound having a SiH group represented by the following formula (4) were added. , Mixed uniformly.

[0045]

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The viscosity characteristics of the obtained liquid fluoropolyether rubber composition were measured in accordance with JIS K 7117. Table 1 shows the results.

[0047]

[Table 1]

Comparative Example 100 parts of a polymer represented by the formula (2) (viscosity: 4.4 Pa · s, average molecular weight: 16,500, vinyl group content: 0.012 mol / 100 g) were mixed with silica-based filler Aerosil 300 (Japan). Aerosil Co., Ltd.)
Treated with a cyclic silazane (hexamethylcyclotrisilazane (Shin-Etsu Chemical Co., Ltd.))
90 m ² / g) in a kneader at a mixing ratio of 20 parts, and kneading was performed for 1 hour. 170 ° C after kneading
For 2 hours, and mixed with three rolls to obtain a base (3).

The adjustment of the A side and the B side was performed in the same manner as in the case of using the base (2) of the example.

The viscosity characteristics of the obtained liquid fluoropolyether rubber composition were measured in accordance with JIS K 7117. Table 2 shows the results.

[0051]

[Table 2]

[0052]

According to the present invention, the silica filler of the component (B) is blended in an amount of 25 to 60 parts by weight with respect to 100 parts by weight of the linear fluoropolyether compound of the component (A). After kneading, the viscosity is reduced by post-dilution with the component (A) so as to have a predetermined compounding ratio, and the LI
When molding such as MS molding, a composition having excellent workability can be obtained.

Continued on the front page F term (reference) 4F070 AA52 AB16 AB24 AC23 AC25 AC52 AE08 FA05 FB07 FC02 4J002 CH001 DA118 DJ016 EX007 FD016 GT00

Claims (5)

[Claims] (A) A viscosity at 25 ° C. of 0.1 to 50 Pa
A linear fluoropolyether compound having at least two alkenyl groups in the molecule and having a perfluoroalkyl ether structure in the main chain (B) silica having a specific surface area of 50 m ² / g or more When producing a curable liquid fluoropolyether rubber composition containing a system filler as an essential component, the component (B) is blended in an amount of 25 to 60 parts by weight with respect to 100 parts by weight of the component (A). After kneading, the curable liquid fluoropolyether-based rubber composition is further obtained by mixing the above component (A) and performing post-dilution so as to have a predetermined mixing ratio to obtain a liquid base. Manufacturing method. 2. The liquid base according to claim 1, wherein (C) an organosilicon compound having at least two hydrogen atoms bonded to a silicon atom in a molecule, and (D) a hydrosilylation reaction catalyst. Manufacturing method. 3. The liquid base is divided into two parts, one of which is (C)
Ingredient 2 is blended with component (D)
3. The production method according to claim 2, wherein the production method is a liquid type. 4. The component (A) is represented by the following general formula (1): The method according to any one of claims 1 to 3, which is a compound represented by the formula: 5. The method according to claim 1, wherein the composition is for LIMS molding.