JPH07109441A - Method of surface treatment of rubber and rubber article treated thereby - Google Patents

Abstract

PURPOSE:To provide a new method of treatment for forming a film excellent in weatherability and abrasion resistance on the surface of a rubber article and to obtain a rubber article treated by the method. CONSTITUTION:The method comprises applying a composition substantially consisting of 10-90wt.% organopolysiloxane (A) represented by the general formula R<1>aHbSiO(4-a-b)/2 (wherein R<1> is a 1-20C monovalent hydrocarbon group or a halogenated hydrocarbon group; 1<a<2.2; and 0.1<b<1), 0-50wt.% diorganopolysiloxane (B) represented by the general formula HO-(R<2>SiO)m-H (wherein R<2> is a 1-20C monovalent hydrocarbon group or a halogenated hydrocarbon group; and 10<=m<=3,000), 10-90wt.% product (C) of the hydrolysis and condensation of dialkoxysilane represented by the general formula R<3>R<4>N(CH2)p [NR<5>(CH2)q]rSiR<6> (OR<7>)2 (wherein R<3>, R<4> and R<5> are each H, a 1-6C monovalent hydrocarbon group or a halogenated hydrocarbon group; R<6> and R<7> are each a 1-6C monovalent hydrocarbon group or a halogenated hydrocarbon group; 1<=p; q<=6; and 0<=r<=3), and 0.01-20wt.% organometallic salt (D) to a rubber ad curing it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for imparting abrasion resistance to the surface of a rubber article and a rubber article treated by this method. By treating with the surface treatment method of the present invention, a rubber article suitable for a weather strip for automobiles can be obtained.

[0002]

2. Description of the Related Art Conventionally, various rubber materials have been used for weather strips. This weather strip is used for automobile doors, windshields, rear windshields, trunks, etc., but its surface is rubbed by the door, glass, or trunk lid, so that the surface is required to have abrasion resistance. Therefore, various surface treatment methods have been proposed so far. For example, a method of surface treatment with a urethane resin composition (Japanese Patent Laid-Open Nos. 3-20376 and 3-21675).
No. 3, No. 3-21676, No. 3-86774, No. 3-252477, No. 4-8
778, 4-8779, 4-25580, 4-25581, 4
-31474) or a method of surface-treating with a silicone resin composition (Japanese Patent Publication No. 56-47864, Japanese Patent Laid-Open No. 54-9).
No. 0369).

[0003]

However, the urethane resin film has poor weather resistance, and therefore the durability of the film is poor, and although the method using a silicone resin composition can impart some properties, in terms of abrasion resistance, etc. Further quality improvement is desired. The present invention has been made to provide a method for treating the surface of a rubber article with an organopolysiloxane composition which has improved the above problems, and a rubber article treated by this method.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a specific organopolysiloxane having a hydrogen atom directly bonded to a silicon atom,
The organopolysiloxane composition containing a hydrolyzed condensate of a specific dialkoxysilane having an aminoalkyl group and an organic metal salt, and further a diorganopolysiloxane having a terminal hydroxyl group, which is optionally added, is applied to a rubber surface. Then, they found that a film having excellent properties was formed when cured, and thus reached the present invention. The feature of the present invention resides in that the hydrolysis-condensation product of the dialkoxysilane having an aminoalkyl group is blended.

The subject of the present invention is a surface treatment method for a rubber article, which comprises applying an organopolysiloxane composition consisting essentially of the following components (A) to (D) to a rubber surface and curing the composition. is there. (A) The following general formula (1) R ¹ _a H _b SiO _{(4-ab) / 2} (1) (wherein R ¹ is a monovalent hydrocarbon group having 1 to 20 carbon atoms and halogenated carbonization) Organo having one or two or more groups selected from hydrogen groups and having a hydrogen atom directly bonded to a silicon atom represented by 1 <a <2.2 and 0.1 <b <1. Polysiloxane 10 to 90% by weight (B) The following general formula (2) HO- (R ² ₂ SiO) _m -H ... (2) (where R ² is a monovalent group having 1 to 20 carbon atoms). 0 to 50% by weight of diorganopolysiloxane (C), which is one or more groups selected from a hydrocarbon group and a halogenated hydrocarbon group, and 10 ≦ m ≦ 3000. following general formula ^{(3) R 3 R 4 N} (CH 2) p [NR 5 (CH 2) q] r SiR 6 (OR 7) 2 ··· (3) ( wherein, R ^3, R ^4, R ⁵ each represent a hydrogen or monovalent hydrocarbon groups and halogenation hydrocarbon having 1 to 6 carbon atoms More selected the group, R ^6, R ⁷ is a group each being selected from monovalent hydrocarbon radicals and halogenated hydrocarbon group having 1 to 6 carbon atoms, 1 ≦ p ≦ 6,1 ≦ q ≦ 6, 0 ≦ r ≦ 3) 10 to 90% by weight of a hydrolyzed condensate of a dialkoxysilane having an aminoalkyl group represented by the formula (D) 0.01 to 20% by weight. In a rubber article treated by the above method.

The present invention will be described in detail below.
The component (A) is an organopolysiloxane having a hydrogen atom directly bonded to the silicon atom represented by the general formula (1). R ¹ in the formula is one or more groups selected from monovalent hydrocarbon groups having 1 to 20 carbon atoms and halogenated hydrocarbon groups. Examples of R ¹ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group,
Octyl group, decyl group, dodecyl group, tetradecyl group,
Hexadecyl, octadecyl, and other alkyl groups, cyclopentyl, cyclohexyl, and other cycloalkyl groups, phenyl, tolyl, and other aryl groups, trifluoropropyl, chloropropyl, chlorophenyl, nonafluorohexyl, heptadeca Examples thereof include a halogenoalkyl group such as a fluorodecyl group and a halogenophenyl group, and it is particularly desirable that 90 mol% or more of R ¹ is a methyl group.

The values of a and b in the formula are 1 <a <2.2,
0.1 <b <1, but if a is 1 or less, the cured film finally formed will be too hard and will have poor followability to deformation of the rubber substrate, and is 2.2 or more. On the contrary, it becomes too soft and has poor wear resistance.
1 <a <2.2. Preferably 1.1 ≦ a ≦ 1.8. Further, when b is 0.1 or less, the cured film becomes too soft, and when b is 1 or more, it becomes too hard, and for the same reason as above, 0.1 <b <1. Preferably 0.30 ≦ b ≦ 0.
95.

The viscosity of component (A) at 25 ° C. is preferably 10,000 to 10,000 centistokes. When the viscosity is lower than 1 centistokes, the cured film becomes too hard, it is difficult to follow the deformation of the rubber article, and peeling easily occurs. Conversely 1
If it is higher than 10,000 centistokes, the cured film becomes too soft and wear resistance becomes poor. More preferably 10-1000
It is Centistokes.

The component (B) is a diorganopolysiloxane having a terminal hydroxyl group represented by the general formula (2).
R ² in the formula is one or more groups selected from monovalent hydrocarbon groups having 1 to 20 carbon atoms and halogenated hydrocarbon groups. Examples of R ² include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group, cyclopentyl group, cyclohexyl group. Groups such as cycloalkyl groups, phenyl groups, aryl groups such as tolyl groups, trifluoropropyl groups, chloropropyl groups, chlorophenyl groups, nonafluorohexyl groups, halogenoalkyl groups such as heptadecafluorodecyl groups, or halogenophenyl groups. Among them, 90 mol% or more of R ² is particularly preferably a methyl group.

The value of m in the formula is 10≤m≤3000. m is
When it is less than 10, the resulting cured film is too hard to follow the deformation of the rubber article, and peels easily. On the other hand, if it is more than 3000, the cured film is too soft and wear resistance is poor. More preferably, it is 100 or more and 1000 or less.

The component (C) is a hydrolysis-condensation product of a dialkoxysilane having an aminoalkyl group represented by the general formula (3). In the formula, R ³ , R ⁴ , and R ⁵ are each hydrogen or a group selected from a monovalent hydrocarbon group having 1 to 6 carbon atoms and a halogenated hydrocarbon group, and R ⁶ and R ⁷ are each 1 carbon atoms. To 6 monovalent hydrocarbon groups and halogenated hydrocarbon groups. Further, 1 ≦ p ≦ 6, 1 ≦ q ≦ 6, 0 ≦ r ≦
However, when p and q are 0, the desired hydrolyzed condensate cannot be obtained because the Si-N bond undergoes hydrolysis.
A value greater than 6 is a property imparting effect as the component (C),
That is, since the effect of improving the adhesion of the cured film to the rubber substrate is reduced, 1 ≦ p and q ≦ 6. Preferably, p and q = 3. If r is larger than 3, it is industrially difficult to synthesize, and therefore it is set to 3 or less, preferably r =
It is 0 or 1.

When R ³ , R ⁴ and R ⁵ are hydrocarbon groups, examples of these groups include alkyl groups such as methyl group, ethyl group, propyl group, butyl group and hexyl group, cyclopentyl group and cyclohexyl group. And the like, and a halogenoalkyl group such as a phenyl group and a trifluoropropyl group, and the like. In the component (C), the hydrocarbon group is preferably 10 mol% or less and the hydrogen is 90 mol% or more. .
Examples of R ⁶ and R ⁷ include alkyl groups such as methyl group, ethyl group, propyl group, butyl group and hexyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group, halogenoalkyl groups such as phenyl group and trifluoropropyl group. And the like, and particularly preferably a methyl group or an ethyl group.

Examples of such silanes include γ- (N
-Β-aminoethyl) aminopropylmethyldimethoxysilane, γ- (N-β-aminoethyl) aminopropylmethyldiethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane and the like are typical. It is mentioned as a thing.

Hydrolysis of these silanes may be carried out according to a known method. That is, the dealcoholization condensation reaction proceeds easily by adding water to these silanes.
After that, the generated alcohol may be distilled off.

Component (D) is an organometallic salt that can act as a catalyst for curing the composition used in the method of the present invention, and includes, for example, zinc octylate, iron octylate, cobalt octylate, octyl. Examples thereof include organic metal salts such as tin acid and alkyl group-containing tin salts such as dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dioctyltin diacetate, dioctyltin dioctoate and dioctyltin dilaurate.

The blending amounts of these components (A) to (D) are 10 to 90% by weight of the component (A), 0 to 50% by weight of the component (B), 10 to 90% by weight of the component (C), and ( D) component is 0.01 ~
It is set to 20% by weight. Here, when the content of the component (A) is less than 10% by weight, the cured film obtained becomes too soft,
If it is more than 90% by weight, it will be too hard and will be too hard to follow the deformation of the rubber base material, and will be easily peeled from the rubber base material.
Further, the component (B) is added as necessary in order to impart appropriate flexibility to the cured film, but this is 50
If it exceeds 5% by weight, the cured film becomes too soft and wear resistance becomes poor. Further, if the content of the component (C) is less than 10% by weight, the adhesion of the cured film to the rubber substrate becomes insufficient, resulting in poor abrasion resistance, and if it exceeds 90% by weight, the cured film becomes soft. Too much, and the abrasion resistance is also poor. The component (D) serves as a curing reaction catalyst for the present composition, but if it is less than 0.01% by weight, the catalytic action is poor and a sufficient curing reaction does not occur, resulting in a soft coating film, 20% by weight. Not only can it not be expected to accelerate the curing reaction rate even if the amount is increased, but the coating may become softer due to the plasticizing effect. From these facts, the object of the present invention can be achieved by blending within the above range, but a preferred range is 20 to 70% by weight of the component (A),
0 to 30% by weight of component (B), 20 to 70% by weight of component (C)
And the component (D) is 0.1 to 10% by weight.

In order to carry out the surface treatment of the rubber with the mixture of these components (A) to (D), it is preferable to use a treatment liquid which is uniformly dissolved or dispersed in an organic solvent. (A) ~
It is easy to dissolve or disperse the component (D) in an organic solvent. As the organic solvent, toluene, an aromatic solvent such as xylene, trichlene, perkylene, 1,1,1-trichloroethane, a chlorinated hydrocarbon such as methylene chloride, n-
Hexane, cyclohexane, petroleum ether, ligroin, petroleum hydrocarbons such as kerosene, isoparaffins, volatile organopolysiloxanes such as hexamethyldisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane are exemplified. It The total concentration of the components (A) to (D) can be arbitrarily adjusted so as to obtain a desired film thickness, but generally 1 to 50% by weight is preferable.

Examples of rubber materials to which the surface treatment method of the present invention can be applied include natural rubber, EPDM, SBR, chloroprene rubber, isoprene-isobutylene rubber and nitrile rubber. The rubber article made of these rubber materials may have a sponge shape, a solid shape or the like.

As a surface treatment method for a rubber article, the above-mentioned compound or treatment liquid is applied by a method such as brush coating, spray coating, roll coating, dip coating or knife coating, and then the coating is formed at room temperature or by heating and drying. It may be cured. As a result, the intended surface-treated rubber article is obtained.

Incidentally, carbon black, fluororesin powder, melamine resin powder, acrylic resin powder, polycarbonate resin powder, silicone resin powder, nylon resin powder, graphite powder, if necessary, within a range not impairing the effects of the present invention, It is optional to add various organic or inorganic pigments, paraffin wax, polyethylene wax and the like to the above-mentioned compound or treatment liquid.

[0021]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. [Synthesis Example 1] 500 g of γ- (N-β-aminoethyl) aminopropylmethyldimethoxysilane was charged into a 1 L glass flask, and 135 g of deionized water was added dropwise over 30 minutes with stirring at room temperature. After completion of the dropping, the reaction system was depressurized while raising the temperature, and the produced methanol was distilled off. After continuing the depressurization operation at 55-60 ° C for 30 minutes, the reaction was terminated by cooling and returning to normal pressure. The resulting hydrolyzed condensate (designated as C-1) was a pale yellow transparent liquid having a viscosity of 2300 centistokes at 25 ° C.

[Synthesis Example 2] In Synthesis Example 1, γ- (N-
β-Aminoethyl) aminopropylmethyldimethoxysilane (500 g) was changed to γ-aminopropylmethyldimethoxysilane (500 g), and deionized water (135 g) was changed to 170 g. -2) was obtained. This was a pale yellow transparent liquid having a viscosity of 3200 centistokes at 25 ° C.

[Examples 1 to 7] A surface treatment solution was prepared according to the composition shown in Table 1, and EPDM sponge rubber (15
mm × 150mm × thickness 2mm) Apply with a brush on the surface 150
Surface treatment was carried out by leaving it for 10 minutes in a hot air circulation type constant temperature bath adjusted to ℃. The obtained surface-treated sponge rubber was subjected to the following friction test, and the number of times of friction until the sponge rubber substrate was exposed was measured. The results are shown in Table 1.

(Friction test method) See FIG. 1. The friction method is reciprocal friction, and a ground glass cell 2 (line contact, line width 5 mm) is used as a friction cell, a thrust load of 350 g is applied, and a friction speed: 60 reciprocations / min. Friction stroke: The treated surface of the sponge rubber was tested under the condition of 70 mm.

[0025]

[Table 1] The films formed were all non-sticky.

The components in Table 1 are as follows. (A) component A-1:

[Chemical 1] A-2:

[Chemical 2]

Component (B) B-1:

[Chemical 3] B-2:

[Chemical 4]

Component (D) D-1: 30% toluene solution of dibutyltin diacetate Fluorocarbon resin powder Lubron L-2 (trade name, manufactured by Daikin Industries, Ltd.)

[Comparative Examples 1 to 3] A surface treatment solution was prepared with the composition shown in Table 2, the surface treatment was performed on the sponge rubber in the same manner as in the example, and the friction test was conducted in the same manner as the example. It was The same fluororesin powder as in the example was used. The test results are shown in Table 2.

[0030]

[Table 2]

As described above, in the embodiment, the adhesion of the film,
While the abrasion resistance and the dryness are good, in the comparative example where the hydrolysis-condensation product of the component (C) is not added (Comparative Examples 1 and 2),
The coating has poor adhesion and wear resistance, and (D)
When the organometallic salt as a component is not added (Comparative Example 3), the number of times of rubbing is large, but the film is sticky, which is not suitable for practical use.

[0032]

By the surface treatment method of the present invention, it is possible to form a silicone resin film having excellent adhesion and abrasion resistance on a rubber article. The weather strip rubber treated by the surface treatment method of the present invention is suitable for automobiles.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a method of a friction test.

[Explanation of symbols]

 1 Sponge rubber 2 Ground glass cell

Front page continuation (72) Inventor Yoshinori Iguchi 1 Hitomi, Osamu Matsuida-cho, Usui-gun, Gunma 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Inventor Satoshi Kuwata Oita Hitomi, Usui-gun, Gunma Address 1 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (4)

[Claims] 1. A method for treating a surface of a rubber article, which comprises applying an organopolysiloxane composition consisting essentially of the following components (A) to (D) onto a rubber surface and curing the composition. (A) The following general formula (1) R ¹ _a H _b SiO _{(4-ab) / 2} (1) (wherein R ¹ is a monovalent hydrocarbon group having 1 to 20 carbon atoms and halogenated carbonization) Organo having one or two or more groups selected from hydrogen groups and having a hydrogen atom directly bonded to a silicon atom represented by 1 <a <2.2 and 0.1 <b <1. Polysiloxane 10 to 90% by weight (B) The following general formula (2) HO- (R ² ₂ SiO) _m -H ... (2) (where R ² is a monovalent group having 1 to 20 carbon atoms). 0 to 50% by weight of diorganopolysiloxane (C), which is one or more groups selected from a hydrocarbon group and a halogenated hydrocarbon group, and 10 ≦ m ≦ 3000. following general formula ^{(3) R 3 R 4 N} (CH 2) p [NR 5 (CH 2) q] r SiR 6 (OR 7) 2 ··· (3) ( wherein, R ^3, R ^4, R ⁵ each represent a hydrogen or a monovalent hydrocarbon group and halogenation hydrocarbon having 1 to 6 carbon atoms More selected the group, R ^6, R ⁷ is a group each being selected from monovalent hydrocarbon radicals and halogenated hydrocarbon group having 1 to 6 carbon atoms, 1 ≦ p ≦ 6,1 ≦ q ≦ 6, 0 ≦ r ≦ 3) 10 to 90% by weight of a hydrolyzed condensate of a dialkoxysilane having an aminoalkyl group represented by the formula (D) 0.01 to 20% by weight 2. The surface treatment method for a rubber article according to claim ¹ , wherein R ¹ , R ² and R ⁶ in the above formula are methyl groups, and R ³ , R ⁴ and R ⁵ are hydrogen. 3. A rubber article treated by the method of claim 1. 4. A weatherstrip rubber article treated by the method of claim 1.