JPS5919814B2 - How to apply paint to vulcanized rubber parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for applying paint (especially polyurethane paint) to vulcanized rubber parts.

There are currently two main methods for applying polyurethane paint5 to vulcanized rubber parts.

In one method, benzophenone is sprayed onto the rubber surface to sensitize the surface, and the sprayed surface is then exposed to ultraviolet light prior to application of a primer. Finally, apply polyurethane paint. The disadvantages of this method are that the coating operation is complex and takes a long time, and that it is expensive because special chemicals and various steps must be used. Another coating method involves resin vulcanization 15 (resin vulcanization) on rubber activated by the addition of halogenated rubber.
ncure).

There is no need for a primer, just apply polyurethane paint to the clean rubber part surface. The disadvantage of this method is
Resin vulcanization is expensive and slow, and steam cannot be used as a heat transfer material. Resin 20 vulcanization is also not compatible with sulfur vulcanization. This makes co-vulcanization of separate parts difficult (for example in the case of gluing side walls to carcass). The present inventors have now discovered a method for applying paint (particularly 25 polyurethane paint) to rubber surfaces, which is simple and does not have the drawbacks of the above two methods. The coating method of the present invention is a method for coating a rubber surface by applying paint to the rubber surface, in which the rubber
Halogenated butyl rubber vulcanized with a metal oxide or halide in the presence of an alkylphenol polysulfide promoter and/or a non-reactive phenolic aldehyde resin per 100 parts by weight of rubber.
It is characterized by having a composition containing ~100 parts by weight (phr). In the present invention, non-reactive means not reacting with any component in the formulation. Rubber compositions containing 3O-100 phr of halogenated butyl rubber can be 100% halogenated butyl rubber (e.g., chlorobutyl rubber) or a blend of halogenated butyl rubber and other rubbers. Examples of other rubbers mentioned above include natural rubber, styrene-butadiene rubber, and ethylene-propylene-diene terpolymer rubber (hereinafter abbreviated as E).
PDM), polyptadiene rubber, acrylonitrile-butadiene rubber, polychloroprene rubber, synthetic polyisoprene rubber or chlorosulfonated polyethylene (
Hypalon).

Butyl rubber contains a large amount (e.g. 85-99.9% by weight, preferably 95-99.5%) of C4-C8 isoolefin (e.g. isobutene) and a small amount (e.g. 0.1-1% by weight)
5% by weight, preferably 0.5-5% by weight) of C4-Cl
4 polyene, preferably a C4-C8 diene (eg butadiene, dimethylbutadiene, piberylene or isoprene). Preferred butyl rubber is 9
5-99.5% by weight isoptylene and 0.5-5% by weight
It is obtained by reacting with isoprene. The halogenated butyl rubber is an unmodified, unvulcanized butyl rubber with a halogen content of 0.5% by weight or more, preferably 1.5% by weight or more.
By halogenating (e.g., chlorination or sulfurization) so that the amount is 0% by weight or more, but not more than 1 atom of chlorine or not more than 3 atoms of sulfur is contained in the polymer per 1 molecule of polyene present. It is manufactured by

Halogenated butyl rubber usually has a viscosity average molecular weight of 1500.
00-1.5 million and contains 0.5-15 mol% unsaturation. Styrene-butadiene rubber (SBR)
is usually produced by copolymerization of butadiene and styrene, for example, 3
It is produced by copolymerizing part by weight of putadiene and 1 part by weight of styrene, in which case these monomers are suspended in the form of a finely dispersed emulsion in a large amount of water in the presence of a surfactant and polymerized. I do.

SBR can also be produced by solution polymerization. Ethylene-propylene-dieneterpolymers are typically prepared by converting a feedstock containing ethylene, propylene and a polymerizable diene into an inert saturated C5-C8 hydrocarbon diluent (e.g. n-pentane, isopentane, n-hexane, isohexane or n- (produced by contacting with a Ziegler catalyst in the presence of an alkane such as octane or a cycloalkane).

This copolymerization is usually carried out under a pressure of 1-5 atmospheres. The third polymerizable diene is usually a C6-Cl6 non-conjugated diene V1 such as 1,5-hexadiene, 1,5-octadiene or 2-alkylnorpornadiene (preferably ethylidene norbornene or methylidene norbornene). An example of a rubber composition containing 30-100 phr of halogenated rubber is 75-85 (e.g. 80) parts by weight of chlorobutyl rubber and 15-25 (e.g. 20) parts by weight of natural rubber: 30-40 (e.g. 35) parts by weight of natural rubber. ) parts by weight of chlorobutyl rubber, 20-30 (e.g. 25) parts by weight of natural rubber, 20-30 (e.g. 25) parts by weight of styrene-ptadiene rubber and 10-20 (e.g. 15) parts by weight of EPDM: There are 60 (eg 50) parts by weight of chlorobutyl rubber and 40-60 (eg 50) parts by weight of EPDM.

To improve the adhesion of paints to halogenated rubber-containing compositions, metal oxides or halides can be used in conjunction with alkylphenol poly6 sulfide promoters and/or in the presence of non-reactive phenolic aldehyde resins. The rubber must be vulcanized.

The metals forming the oxides or halides are preferably metals of Groups B, B, B and Groups of the Periodic Table.

These metal compounds may therefore be oxides, chlorides or sulfides of zinc or tin, with zinc oxide being particularly preferred. The preferred amount of metal oxide or halide used is 3-20 parts by weight per 100 parts by weight of rubber. The use of alkylphenol disulfides is preferred; suitable alkylphenol disulfides are those in which the alkyl group contains 1 to 5 carbon atoms.

A particularly preferred alkylphenol disulfide is that known as Vultac 5. The raw phenol for the non-reactive phenolic aldehyde resin may be mono- or dihydroxybenzene.

Dihydroxybenzene, in which the two hydroxyl groups are in the meta position, is particularly suitable.

Examples of suitable phenols are phenol, cresol, xylenol, trimethylphenol, monochloro- or dichlorophenol, hydroquinone, or resorcinol or its derivatives. Preferred aldehydes from which the non-reactive phenolic aldehyde resin is sourced are formaldehyde or formaldehyde sources such as paraformaldehyde, or acetaldehyde or furfural.

Resins are usually produced by condensation of phenols and aldehydes in the presence of small amounts of acid.

A particularly suitable non-reactive phenolic aldehyde resin is the phenolic formaldehyde resin known as Upper Roll ST-137X. The preferred amount of non-reactive phenolic aldehyde resin used is 0.1-30 parts by weight per 100 parts by weight of rubber. Various fillers and extenders can be used, examples of which include various carbon blacks (e.g. SAF, HAF).
, SRF, FPC), clay, silica, carbonate, oil, resin, and wax. Common vulcanizing agent for halobutyl rubber (
curatives), such as sulfur, sulfenamide derivatives, benzothialyldisulfide (i.e. 2
, 2-dithiobisbenzothiazole) and tetramethylthiuram disulfide can also be used.

Vulcanization is usually carried out at 140°C - 250°C (preferably 150°C -
200° C.) and typically takes 1-150 minutes (e.g. 20-60 minutes). The rubber can be placed in either a conventional heat press or transfer press or injection molding machine and press vulcanized, ie, molded and vulcanized, using a mold. After the rubber is vulcanized, it is painted with the desired paint.

The paint may be a polyurethane paint, or a paint containing a polyurethane resin. Such resins may be diisocyanates (e.g. toluene diisocyanate or
, 4-diphenylmethane diisocyanate) with a polyol (eg glycerin, pentaerythritol, phenol, polyether or polyester).

These are usually packaged as one-part or two-part paint systems. Other paints that can be used include acrylic paints. Preferably, the rubber is cleaned with a hexane solvent, for example, before painting.

The method according to the invention not only provides very good adhesion between rubber and paint, but also completely eliminates the disadvantages of the prior art methods.

That is, it has been found that the method is simple, does not require a lint sensitizer or ultraviolet treatment, is steam vulcanizable, is compatible with sulfur vulcanization, and provides a high vulcanization rate. The properties of the rubber used in the examples below are shown below.

Example 1 A composition containing chlorobutyl rubber was prepared, and after cleaning with a solvent, a polyurethane paint (Quubertein A1 paint) was applied to the surface.

The formulation of the composition is as follows.

Example 2 After a composition based on chlorobutyl and natural rubber was prepared, press cured and coated with paint, tests similar to those in Example 1 were carried out.

Adhesion tests were conducted according to standard paint adhesion methods. (a
) Tape Test - 30 3" x 5" cut tape strips.

G. M. Standard GM4489-PIV8 tape is 3M Scotch NP71O (or equivalent). Standard tensile test pads (sheets with a thickness of 2W1) were molded in the usual manner, except that the rubber surface was protected with a Mylar film to prevent it from being contaminated by mold release agents and dust.

After conditioning for 1-2 days, the Mylar film was removed and the rubber was coated with a suitable polyurethane-based paint (one-part aluminum-containing paint).

After drying for 2-4 days, tape test GM4489-PI was performed.

(b) The above test before aging, after aging in an air dryer (7 days at 60°C) and after soaking in water (7 days at 50°C).

The results were as follows.

These results clearly demonstrate the benefits of using an alkylphenol disulfide promoter (Baltak 5).

In this example as well, the benefits of using Baltac 5 are clear from the above results.

Example 3 EPDM (Vistaron 4608), chlorobutyl HTl
A typical radial tire sidewall composition based on a blend of O-68, natural rubber} and SBRl5OO (styrene butadiene rubber) was prepared and tested in the same manner as in Example 1.

Claims (1)

[Claims] 1. A method of painting a rubber surface by applying a paint to the rubber surface, wherein the rubber is coated with a metal oxide or halide in the presence of one or both of an alkylphenol polysulfide promoter and a non-reactive phenolic aldehyde resin. Vulcanized halogenated butyl rubber is added in an amount of 30 to 100 parts by weight (phr) per 100 parts by weight of rubber.
) The above method, characterized in that it has a composition comprising