JPH05117530A - Silicone rubber composition for wiper blade - Google Patents

Abstract

PURPOSE:To obtain the subject silicone rubber composition of good weathering resistance by using an organopolysiloxane green rubber, wet-process silica, kieselguhr, powder of laterally cleaving mineral and organic peroxide. CONSTITUTION:The subject composition free from chattering and squeaking comprises (A) 100 pts.wt. of organopolysiloxane green rubber, (B) 10 to 50 pts.wt. of wet-process silica, (C) 10 to 50 pts.wt. of kieselguhr preferably of 5 to 40mum average particle size, (D) 0 to 50 pts.wt. of a laterally cleaving mineral, preferably a mica powder, (E) 0 to 10 pts.wt. of fluororesin powder such as polytetrafluoroethylene resin powder and (F) an organic peroxide such as benzoyl peroxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone rubber composition for wiper blades, and more particularly to a heat-curable silicone rubber composition most suitable for wiper blades.

[0002]

2. Description of the Related Art Conventionally, wiper blades for vehicles are
Synthetic rubbers such as chloroprene rubber, styrene butadiene rubber and ethylene propylene rubber have been used. However, this type of wiper blade rubber is inferior in weather resistance and abrasion resistance, especially when it is semi-dried or cold and cold, and the adhesion phenomenon occurs between the wiper blade rubber and the glass surface, and the wiper operation stops. The so-called "lock phenomenon" and the self-excited vibration due to the negative characteristic of the speed dependency of the friction coefficient, the so-called "chatter phenomenon" occur, defective wiping, abnormal friction of the blade rubber surface, the life of each part of the wiper system connection. Shortening occurs. In addition, there were problems such as eyesore and ears caused by "chatter phenomenon" and "squeal".

[0003]

DISCLOSURE OF THE INVENTION The present inventors have arrived at the present invention as a result of research to solve such conventional problems. That is, an object of the present invention is to provide a silicone rubber composition for a wiper blade, which has excellent weather resistance and does not particularly cause "chattering" and "squeaking".

[0004]

Means for Solving the Problem and Its Action The present invention comprises: (A) 100 parts by weight of organopolysiloxane raw rubber, (B) 10 to 50 parts by weight of wet silica, (C) 10 to 50 parts by weight of diatomaceous earth, (D) Parallel cleavable mineral powder 0-50 parts by weight, (E) Fluororesin powder 0-10 parts by weight, (F) Organic peroxide 0.1-10 parts by weight Silicone rubber composition for wiper blades ..

Explaining the present invention in detail, the component (A) used in the present invention is an organopolysiloxane raw rubber which is a main raw material of a millable type silicone rubber,
It is a high molecular weight linear or slightly branched chain organopolysiloxane that is gum-like at room temperature. The side chain organic groups include methyl group, ethyl group, vinyl group, phenyl group,
The 3,3,3-trifluoropropyl group is exemplified, but preferably at least 50 mol% is a methyl group. Examples of this include dimethylpolysiloxane raw rubber, and a portion of the methyl group of the raw rubber substituted with a vinyl group, a phenyl group or a 3,3,3-trifluoropropyl group. Examples of the terminal group include hydroxyl group, alkoxy group, methyl group, vinyl group and phenyl group, but are not particularly limited.

The wet process silica used as the component (B) in the present invention is, for example, water glass (sodium silicate) containing hydrochloric acid,
It is a finely divided silica fine powder obtained by reacting a mineral acid such as sulfuric acid with water and salts, and is commercially available under the trademarks Nipseal, Carplex, Toxil, Hi-Sl and the like. The blending amount is 5 to 1 with respect to 100 parts by weight of the component (A).
The amount is 00 parts by weight, preferably 20 to 90 parts by weight.

The diatomaceous earth as the component (C) is a particularly important component for providing the silicone rubber with preferable slipperiness, reduction of chattering and abrasion resistance when used in combination with the wet process silica as the component (B). And is a component that is a feature of the present invention. The diatomaceous earth has an average particle size of 5 to 40.
Those in the μm range are required. Moreover, the compounding quantity is within the range of 10 to 50 parts by weight with respect to 100 parts by weight of the component (A).

The component (D), which is a parallel cleavable mineral powder, is a component which is optionally used in the present invention, and has a function of imparting preferred slipperiness and abrasion resistance to the composition of the present invention. Examples of parallel cleavage mineral powder include ferrosilicate powder and graphite powder. Examples of ferrosilicates include automica, paragonite, biotite, and mica-based minerals such as lepitrite, stilpnomerene, pyrophyllite, talc,
Examples thereof include serpentine, curdstone, planite, clay minerals such as montmorillonite and illite, and gulconite. The component (D) tends to have improved slipperiness at the interface with the glass plate in contact with an increase in the amount of the component added, and therefore "squeaking" generated by friction when the silicone rubber is used in contact with the glass plate.
And the friction tends to decrease. The amount of component (D) added is 0 to 50 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of component (A).

The fluororesin powder as the component (E) is a component that further imparts lubricity to the silicone rubber of the present invention, and is used if necessary. Examples of such fluororesin powder include polytetrafluoroethylene resin powder and the like. The amount of component (F) added is 0 to 50 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of component (A).

The organic peroxide of the component (F) used in the present invention is a conventionally known catalyst used for heat-curing a silicone rubber composition, which includes benzoyl peroxide and t-butyl. Examples include perbenzoate, 2,4-dichlorobenzoyl peroxide, monochlorobenzoyl peroxide, dichloroperoxide, and 2,5-bis (t-butyl-peroxy) -2,5-dimethylhexane.

The silicone rubber composition for wiper blades of the present invention comprises the above-mentioned components (A), (B), (C) and (F).
The component can be obtained by simply blending the component (D) and the component (E), if necessary, and if necessary, a low-polymerization degree polydimethylsiloxane having a terminal hydroxyl group blocked, diphenylsilanediol, diphenylmethylsilanol, etc. It is acceptable to add a low molecular weight organosilicon compound, a low polymerization degree organopolysiloxane having a large vinyl group content, a pigment, a heat resistant agent, an oil resistant agent and other additives. The mixing order of the components (A) to (F) is not particularly limited, but usually, the components (A) and (B) are first mixed under heating and reduced pressure using a kneader mixer or the like. , (C) component, and if necessary, further mix (D) component and (E) component with a kneader mixer or two rolls, and finally
It is advantageous to compound the component (F) by using a two-roll mill. The silicone rubber composition thus prepared is heated to 100 ° C. to 180 ° C. for several minutes to several hours under pressure or non-pressurization, and if necessary post-vulcanized, the composition is cured to be weather resistant and abrasion resistant. A silicone rubber product having excellent properties and suitable for a wiper blade free of chatter.

[0012]

EXAMPLES The present invention will now be described with reference to examples. In the examples,% is weight percent and plasticity is the value at 25 ° C.

[0013]

Example 1 As a component (A), a dimethylsiloxane-methylvinylsiloxane copolymer raw rubber (plasticity 160) having 99.84% of methyl groups and 0.16% of vinyl groups blocked at both terminal vinyl groups, (B) Specific surface area of 240 m ² as a component
/ G of wet process silica, average particle size of 40μ as component (C)
m diatomaceous earth, mica fine powder or graphite powder as the component (D), polytetrafluoroethylene resin powder having an average particle diameter of 40 μm as the component (E), and 2,5-dimethyl-2,5 (di) as the component (F). Each component of a 50% silicone oil paste of -t-butylperoxy) hexane was kneaded in the compounding amounts shown in Table 1 to obtain a silicone rubber composition.
Next, this silicone rubber composition is cured using a hot press at 170 ° C. for 10 minutes, and further 200 ° C.
By post-vulcanizing in the oven under the condition of 4 hours,
A sheet having a thickness of 2 mm was created. About this sheet JIS
Hardness and tensile strength were measured according to K6301. Further, this silicone rubber composition was heat-cured under the same conditions as above using a mold for a wiper blade. The obtained molded product was incorporated into a tester for a wiper blade test, and the surface of the silicone rubber molded product was pressed against a flat glass plate that had been wet with water, and a rocking test was performed for 24 hours. Here, the swing test conditions are a pressing force of 600 g and a swing angle of ± 45.
The stroke was 45 cm and the speed was 50 times / minute. Then, the surface of the flat glass was shaken for 24 hours while dropping 6 cc / min of water. The results of these measurements are shown in Tables 1 and 2.

[Table 1]

[Table 2]

[0014]

The silicone rubber composition for wiper blades of the present invention comprises (A) component, (B) component, (C) component and (F) component, and in particular (B) component wet silica and (C). Since it contains diatomaceous earth as a component), when it is applied to a wiper blade, it has excellent weather resistance, and in particular, it can be a wiper blade in which "chattering phenomenon" and "squeaking" do not occur.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display area C08K 5/14 // (C08L 83/04 27:12)

Claims (3)

[Claims] 1. (A) Organopolysiloxane raw rubber
100 parts by weight, (B) wet silica 10 to 50 parts by weight, (C) diatomaceous earth 10 to 50 parts by weight, (D) parallel cleavable mineral powder 0 to 50 parts by weight, (E) fluororesin powder 0 to 10 A silicone rubber composition for a wiper blade, which comprises 0.1 part by weight and (F) an organic peroxide of 0.1 to 10 parts by weight. 2. The average particle size of diatomaceous earth is 5 to 40 μm.
The silicone rubber composition for a wiper blade according to claim 1. 3. The silicone rubber composition for a wiper blade according to claim 1, wherein the parallel cleavable mineral is mica powder or graphite powder.