JPH0211677A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain a coating composition which is improved in abrasion resistance of coating film and adhesion to substrate by mixing a urethane prepolymer obtained from a polyol, castor oil polyol and a polyisocyanate with a curing agent, a fluorocarbon resin and a silicone resin in a specified ratio. CONSTITUTION:A polyol such as polyoxypropylene glycol is reacted with castor oil polyol and a polyisocyanate such as 2,4-tolylene diisocyanate to obtain an isocyanate urethane prepolymer. A coating composition is obtained by mixing 100 pts.wt. this urethane prepolymer with a hydroxylic curing agent such as ethylene glycol in an amount to give a molar ratio of the isocyanate groups to the hydroxyl groups (-NCO/-OH) of 0.7-1.3, 2-100 pts.wt. fluorocarbon resin such as polytetrafluoroethylene and 3-100 pts.wt. silicone oil such as dimethylsilicone oil. 10-90 pts.wt., solvent such as benzene is optionally added to 100 pts.wt. coating composition in the above mixing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a coating composition suitable for coating rubber products, synthetic resin products, etc.

[Prior art] Conventionally, natural rubber (NR), styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), isobutylene-isoprene copolymer rubber H1R), chloroprene rubber (OR), acrylonitrile-butadiene copolymer rubber ( NBR), isoprene rubber (IR), ethylene-propylene-diene copolymer rubber (EPDM), ethylene-
Synthetic rubber such as propylene copolymer rubber (EPT), cotton,
Surface coatings such as rayon, ABS, PS, etc. are nylon-based,
Epoxy-based, acrylic-based, acrylic-ethylene copolymer-based resin paints, or rubber-based paints such as BR, CR, and SBR are used.

[Problem B to be solved by the invention] The above-mentioned conventional resin-based paints and rubber-based paints have poor adhesion to adherends such as rubber, synthetic resins, and fibers, and the abrasion resistance of the resulting paint films is poor. There was a problem that it was inferior.

An object of the present invention is to solve the above-mentioned problems and provide a coating composition that provides a coating film with excellent abrasion resistance and good adhesion to adherends.

[Means for Solving the Problems] In order to achieve the above object, the coating composition of the present invention contains a hydroxyl group based on 100 parts by weight of a urethane prepolymer comprising a polyol, a castor oil polyol, and a polyisocyanate and having an isocyanate group. The molar ratio of isocyanate groups to hydroxyl groups (-NG
O/-OH) is 0.7 to 1.3, 2 to 100 parts by weight of fluororesin, and 5 to 100 parts by weight of silicone oil.

[Detailed Description of Means] First, the urethane prepolymer used in the present invention will be described.

Examples of polyols include polyoxypropylene glycol (PPG), propylene oxide adduct of glycerin, propylene oxide adduct of trimethylolpropane, propylene oxide adduct of pentaerythritol, triethylene glycol (TG), C! Examples include compounds in which propylene oxide is added to sugar. The above polyoxypropylene glycol has a number average molecular weight of 8
A value in the range of 00 to 6000 is preferred.

Polyisocyanate is a compound having a plurality of isocyanate groups, such as 2,4-1-lylene diisocyanate (TDI), a ratio of 65/35 (2,4-tolylene diisocyanate and 2,6-)lylene diisocyanate, or the following. Similar) Tolylene diisocyanate, 80/
20 Tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), dianisidine diisocyanate, tridene diisocyanate, hexamethylene diisocyanate, metaxylene diisocyanate, 1,5-naphthalene diisocyanate 1- (NDI)
, hydrogenated 4,4'-diphenylmethane diisocyanate,
Hydrogenated xyl diisocyanate, hydrogenated 2,4-)lylene diisocyanate, hydrogenated 65/35 tolylene diisocyanate, hydrogenated 80/20 tolylene diisocyanate,
Isophorone diisocyanate) (IPDI), 4.4
', 4''-triphenylmethane triisocyanate, tris(p-isocyanate phenyl) thiophosphate, etc. are used.

As the silicone oil, dimethyl silicone oil, methyl chloride silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, fluorosilicone oil, etc. are used.

The blending ratio of the silicone oil is 5 to 100 parts by weight based on 100 parts by weight of the urethane prepolymer.

If the amount is less than 5 parts by weight, the wear resistance cannot be improved. Furthermore, even if the amount exceeds 100 parts by weight, the effect of improving wear resistance remains the same, but the adhesion deteriorates on the contrary.

The curing agent has a hydroxyl group and cures the urethane prepolymer, such as ethylene glycol, propylene glycol, butanediol, bentanediol, hexanediol, heptanediol, octanediol, diethylene glycol, triethylene glycol, dithioglycol. , dipropylene glycol, neopentyl glycol, 2-ethyl-2-n-butyl-1,3-propanediol, 2,2.4-1-ramethyl-1,3-bentanediol, triethanolamine, glycerin, triethanolamine Methylolpropane etc. are used. The amount of the curing agent used is such that the molar ratio (-NGO/-OH) of the isocyanate group (-NGO) in the urethane prepolymer to the hydroxyl group (-0) () in the curing agent is 0.
．． The amount is 7 to 1.3. Wear resistance decreases both when the molar ratio is less than 0.7 and when it exceeds 1.3.

As the fluororesin, polytetrafluoroethylene, polychlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, etc. are used. The blending ratio of this fluororesin is in the range of 2 to 100 parts by weight based on 100 parts by weight of the urethane prepolymer. If it is less than 2 parts by weight, the resulting coating film will have poor abrasion resistance, and if it exceeds 100 parts by weight, it will be difficult to apply the coating composition.

Solvents that may be used as desired include benzene, toluene, xylene, ethylbenzene, ethylene chloride, dimethylformamide (DMF3, dimethyl sulfoxide, methyl ethyl ketone, atocene, methyl isopropyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, isopropyl acetate). , n-butyl acetate, isobutyl acetate, anisole, tetrahydrofuran, methylene chloride, 1.1.1-trichloroethane, n-hexane, cyclohexane and the like.

The blending ratio of this solvent is 10 parts by weight in 100 parts by weight of the coating composition.
A range of 90 parts by weight is preferred. If the blending ratio is less than 10 parts by weight, the solid content will be relatively high and the viscosity of the coating composition will increase, making the coating work difficult and likely leading to a decrease in adhesion. On the contrary, the proportion of solids becomes low and the film thickness of the coating composition becomes thin, which is not preferable as a coating material.

The coating composition of the present invention is prepared, for example, as follows. First, the polyol, castor oil polyol, polyisocyanate and necessary solvent are appropriately selected and mixed,
This was heated in dry nitrogen gas at 50-130°C and 60-360°C.
A urethane prepolymer having isocyanate groups is prepared by reacting for minutes.

Next, 2 to 100 parts by weight of fluororesin and 5 to 5 parts by weight of silicone oil are added to 100 parts by weight of this urethane prepolymer.
100 parts by weight, the curing agent is an isocyanate group (-NG
O) and hydroxyl group (-〇H) molar ratio (-NGO/
-OH) in an amount of 0.7 to 1.3, and further add a solvent to adjust the viscosity for coating. In this case, a part of the fluororesin may be replaced with molybdenum disulfide, glass fiber, carbon fiber, polyethylene, silicon oxide, calcium carbonate, magnesium carbonate, clay, or the like.

[Function] By adopting the above means, the coating composition improves the abrasion resistance of the resulting coating film due to the characteristics such as the lubricity of silicone oil and the low coefficient of friction of fluororesin, and also improves the abrasion resistance of the resulting coating film. Adhesion to the coated object is improved due to the characteristics of the polyurethane, which is composed of a polyol and a polyisocyanate, and has a specific structure having isocyanate groups or hydroxyl groups resulting from the reaction between a urethane prepolymer having isocyanate groups and a curing agent.

[Examples 1 to 11 and Comparative Examples 1 to 10] Examples embodying the present invention will be described below in comparison with comparative examples.

First, the object to be coated is the following vulcanizate.

That is, the vulcanizate contained 100 parts by weight of EPDM (hereinafter simply referred to as "parts"), 70 parts of carbon blank, 35 parts of mineral oil, 7 parts of zinc oxide, 2 parts of stearic acid, 2 parts of vulcanization accelerator, and 1 part of sulfur.
, 5 parts was vulcanized at 160°C for 30 minutes.

In addition, the wear resistance test was conducted by the following method, and the wear resistance was evaluated based on the amount of wear loss.

That is, Test machine: Taper type rotary abrader (manufactured by Toyo Seiki Seisakusho Co., Ltd.) Test conditions: Wear wheel: H-22, Load: 1 kg Wear rotation speed: 60 rpm Sample size: 10100 mm x 100 Number of wear: 1000 times (Example 1) First, a urethane prepolymer was produced as follows.

PPG2000 (weight average molecular weight approx. 2000) 100
parts, castor oil polyol (hydroxyl value 80) 100 parts, M
75 parts of D I and 140 parts of trichlorethylene were mixed and reacted in dry nitrogen at 80° C. for 3 hours to obtain a urethane prepolymer.

Next, for 100 parts of this urethane prepolymer, 1.
18 parts of 4-butanediol, 10 parts of fluororesin, dimethyl silicone oil [Kinematic viscosity: 10,000 centistokes (
A coating composition was obtained by mixing 310 parts of Cst).

Applying this coating composition to the vulcanizate as the object to be coated,
It was dried at 80°C for 20 minutes. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

(Example 2) In the above Example 1, the amount of MDI used was 100 parts, and 1,4-butanediol was replaced with 21.6 parts of ethylene glycol. A composition was obtained.

Applying this coating composition to the object to be coated in the same manner as in Example 1,
Dry. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

(Example 3) Same as Example 1 except that the amount of MDI used was 125 parts and 1,6-hexanediol was 47.2 parts instead of 18 parts of 1,4-butanediol. A coating composition was obtained in the same manner.

Applying this coating composition to the object to be coated in the same manner as in Example 1,
Dry. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

(Example 4) In Example 1, 10 parts of dimethyl silicone oil (kinematic viscosity 10,000 centistokes (Cst)) was replaced with dimethyl silicone oil (kinematic viscosity 60,000 Cst).
) A coating composition was obtained in the same manner as in Example 1 except that the amount was changed to 15 parts.

Applying this coating composition to the object to be coated in the same manner as in Example 1,
Dry. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

(Example 5) Same as Example 1 except that 20 parts of dimethyl silicone oil (kinematic viscosity 100,000 Cst) was used instead of 10 parts of dimethyl silicone oil (kinematic viscosity 100,000 Cst) in Example 1. A coating composition was obtained.

Applying this coating composition to the object to be coated in the same manner as in Example 1,
Dry. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

(Example 6) In Example 1, instead of 100 parts of PPG2000 (weight average molecule 9, about 2000) and 100 parts of castor oil polyol (hydroxyl value 80), 50 parts of ppG2000 (weight average molecule 9, about 2000) and castor oil polyol were used. (
A coating composition was obtained in the same manner as in Example 1 except that the hydroxyl value was 80) and 150 parts.

Applying this coating composition to the object to be coated in the same manner as in Example 1,
Dry. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

(Example 7) In Example 1, 150 parts of PPG2000 (weight average molecule 9, approximately 2000) and castor oil polyol (weight average molecule 9, approximately 2000) were used instead of 100 parts PPG2000 (weight average molecule 9, approximately 2000) and 100 parts of castor oil polyol (hydroxyl value 80).
A coating composition was obtained in the same manner as in Example 1 except that the hydroxyl value was 80) and 50 parts.

Applying this coating composition to the object to be coated in the same manner as in Example 1,
Dry. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

(Example 8) In Example 1, castor oil polyol (hydroxyl value 80) was replaced with 100 parts of castor oil polyol (hydroxyl value 80).
IIi86) A coating composition was obtained in the same manner as in Example 1 except that the amount was changed to 80 parts.

Applying this coating composition to the object to be coated in the same manner as in Example 1,
Dry. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

(Example 9) A coating composition was obtained in the same manner as in Example 1, except that 70 parts of castor oil polyol (hydroxyl value 92) was used instead of 100 parts of castor oil polyol (hydroxyl value 80) in Example 1. .

Applying this coating composition to the object to be coated in the same manner as in Example 1,
Dry. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

(Example 10) In Example 1, propylene oxide of glycerin was used instead of 100 parts of PPG2000 (weight average molecular weight: about 2000), 100 parts of castor oil polyol (hydroxyl group (i80)), 75 parts of MD I, and 140 parts of trichlorethylene. Adduct (weight average molecule 9 approx. 3000) 150
part, castor oil polyol (hydroxyl group (i1fi80) 15
A coating composition was obtained in the same manner as in Example 1, except that 0 parts, TD 1104 parts, and trichlorethylene 200 parts were used.

Applying this coating composition to the object to be coated in the same manner as in Example 1,
Dry. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

(Example 11) In Example 1, instead of 100 parts of PPG2000 (weight average molecular weight 2000), 100 parts of castor oil polyol (hydroxyl value 80), 75 parts of MD I, and 140 parts of trichlorethylene, trimethylolpropane was used. Propylene oxide adduct (weight average molecular weight 3000
) 150 parts, castor oil polyol (hydroxyl value 86) 50 parts
A coating composition was obtained in the same manner as in Example 1, except that 1150 parts of MD, 225 parts of trichlorethylene were used.

Applying this coating composition to the object to be coated in the same manner as in Example 1,
Dry. Regarding this, a wear resistance test was conducted. The results are shown in Table 1 below.

In addition, the following coating composition was used as a comparative example.

(Comparative Example 1) 100 parts of liquid polybutadiene (trade name: Idemitsu Seal AB-700W, manufactured by Idemitsu Petrochemical Industries, Ltd.) and parts of MDIIO were mixed to prepare a paint. This paint was applied to the object to be coated and cured at room temperature to prepare a test piece. This test piece was subjected to the abrasion resistance test described above. The results are shown in the table below.
Shown in 2.

(Comparative Example 2) 100 parts of liquid polybutadiene (trade name: Idemitsu Seal AB-100, manufactured by Idemitsu Petrochemical Industries, Ltd.) and part MDIIO were mixed to prepare a paint. This paint was applied to the object to be coated and cured at room temperature to prepare a test piece. This test piece was subjected to the abrasion resistance test described above. The results are shown in Table-2 below.
Shown below.

(Comparative Example 3) A 70% methanol solution of N-methoxymethylated nylon (trade name: Torezin M-20, manufactured by Teikoku Kagaku Sangyo Co., Ltd.) was applied to the coated object and cured at room temperature to prepare a test piece. This test piece was subjected to the abrasion resistance test described above. The results are shown in Table 2 below.

(Comparative Example 4) 100 parts of epoxy resin (trade name: Araldite PZ820, manufactured by Nippon Ciba Geigy Co., Ltd.), polyaminoamide (
Product name Hardener H2) 1 manufactured by Nippon Ciba Geigy Co., Ltd.
00 parts were mixed to prepare a paint. This paint was applied to the object to be coated and cured at room temperature to prepare a test piece. This test piece was subjected to the abrasion resistance test described above. The results are shown in Table 2 below.

(Comparative Example 5) 100 parts of epoxy resin (trade name: Araldite GY250, manufactured by Nippon Ciba Geigy Co., Ltd.), polyaminoamide (
Product name Hardener H2)3 manufactured by Nippon Ciba Geigy Co., Ltd.
0 parts were mixed to prepare a paint. This paint was applied to the object to be coated and cured at room temperature to prepare a test piece. This test piece was subjected to the abrasion resistance test described above. The results are shown in Table 2 below.

(Comparative Example 6) As a paint, a 74% toluene solution of chloroprene rubber (trade name: Bond G2, manufactured by Konishi Co., Ltd.) was applied to the object to be coated, and cured at room temperature to prepare a test piece. This test piece was subjected to the abrasion resistance test described above. The results are shown in Table 2 below.

(Comparative Example 7) SBR (trade name: Diabond 5010, manufactured by Nogawa Chemical Co., Ltd.) was applied to the coated object and cured at room temperature to prepare a test piece. This test piece was subjected to the abrasion resistance test described above. The results are shown in Table 2 below.

(Comparative Example 8) As a paint, an acrylic resin emulsion with a non-volatile content of 70% (trade name Diabond DA manufactured by Nogawa Chemical Co., Ltd.) was used.
-830A) was applied to the object to be coated and cured at room temperature to prepare a test piece. This test piece was subjected to the abrasion resistance test described above. The results are shown in Table 2 below.

(Comparative Example 9) As a paint, an acrylic-ethylene modified emulsion (manufactured by Sunstar Chemical Co., Ltd., trade name: Penguin Cement 13B) with a non-volatile content of 55% was applied to the object to be coated and cured at room temperature to prepare a test piece. .

This test piece was subjected to the abrasion resistance test described above.

The results are shown in Table 2 below.

(Comparative Example 10) As a paint, a polyurethane paint (trade name: Diabond DA700E, manufactured by Nogawa Chemical Co., Ltd.) was applied to the object to be coated and cured at room temperature to prepare a test piece. This test piece was subjected to the abrasion resistance test described above. The results are shown in Table 2 below.

/ Table - As can be seen from Table 1 above, the paints and acid substances of each example showed abrasion loss of 3.0% even after 1000 abrasion tests.
The amount is extremely small, ranging from 1 to 4.2 mg.

The reason why the coating compositions of each example exhibit such excellent abrasion resistance is presumed to be based on the lubricity of the silicone oil, the low coefficient of friction characteristic of the fluorine resin, and the like.

Further, the coating composition of each example contained a predetermined amount of polyol,
Excellent adhesion to vulcanized rubber, which is the object to be coated, due to the properties of polyunokun, which has isocyanate groups or hydroxyl groups, and is obtained by reacting a curing agent with a urethane prepolymer that is made of castor oil polyol and polyisocyanate and has isocyanate groups. demonstrate.

On the other hand, as can be seen from Table 2, the coating compositions of each comparative example had a large abrasion loss of 482 to 2290 mg, and had poor abrasion resistance.

[Effects of the Invention] The coating composition of the present invention has excellent effects in that the resulting coating film has good abrasion resistance and good adhesion to adherends.

Claims (1)

[Claims] 1. For 100 parts by weight of a urethane prepolymer having isocyanate groups, which is made of polyol, castor oil polyol, and polyisocyanate, a curing agent containing hydroxyl groups is added at a molar ratio of isocyanate groups to hydroxyl groups (-NCO/-OH) of 0. 7 to 1.3, 2 to 100 parts by weight of fluororesin, and 5 to 1 part of silicone oil.
A coating composition containing 00 parts by weight.