JPH02251536A - Bonding of vulcanized rubber and urethane elastomer - Google Patents

Abstract

PURPOSE:To bond the subject elastomer in a state to be usable under dynamic condition by treating a surface of a vulcanized rubber with a solution of an organic active halogen compound and applying a solution of diphenylmethane diisocyanate to the treated surface. CONSTITUTION:The objective bonded composite is produced by contacting (A) a surface of a vulcanized rubber produced by vulcanizing a natural or synthetic rubber with sulfur, etc., with (B) a solution (preferably a 0.5 to 5wt.% solution, e.g. a benzene solution) of an organic active halogen compound having a group of formula (X is halogen) in the molecule (e.g. N-bromosuccinimide), applying (C) preferably 5 to 20wt.% of a diphenylmethane diisocyanate compound in terms of active isocyanate to the above treated surface preferably in the form of a solution having a concentration of 5 to 20wt.%, casting (D) uncured urethane elastomer precursor to the coated surface and curing the precursor e.g. by thermal curing method.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method of bonding vulcanized rubber and thermosetting urethane elastomer.

<Prior Art> Vulcanized products of natural rubber and synthetic rubber are used for tires, belts, hoses, rolls, etc.

These products have various characteristics depending on the type of raw rubber and the type of compounding agents other than rubber.
When a urethane elastomer is bonded to these to form a composite, various properties can be added.

Although it is generally difficult to bond vulcanized rubber and other materials, the following techniques are known as techniques for bonding vulcanized rubber and other materials.

One of them is to strongly oxidize the surface of the vulcanized rubber using a treatment agent such as concentrated sulfuric acid, potassium permanganate, or potassium dichromate, and after washing with water to remove the treatment agent, the vulcanized rubber is bent. This is a method (Method 1) in which fine cracks are generated on the entire surface.

Other methods include the method of treating the surface of vulcanized rubber with iodized isocyanate (Method 2) disclosed in Japanese Patent Publication No. 31839/1983, and the method of treating the surface of vulcanized rubber with an iodized isocyanate as disclosed in Japanese Patent Publication No. 60-31217. There is a method (Method 3) in which the surface of vulcanized rubber is treated with a dioxime compound.

<Problems to be Solved by the Invention> As mentioned above, techniques for bonding vulcanized rubber and other materials are known.

However, method 1 uses strong acids or strong oxidizing agents, so sufficient care must be taken when handling them.
The adhesive strength is not sufficient, and furthermore, this method is not a preferable method because the vulcanized rubber surface and its vicinity are deteriorated by strong acids or strong oxidizing agents.

Furthermore, the iodinated isocyanate used in method 2 is a special one, requires careful handling, and is not versatile.

Furthermore, in Method 3, the usable time after surface treatment of the vulcanized rubber is short, and the adhesive strength is not sufficient.

As described above, none of the conventionally known adhesive techniques for bonding vulcanized rubber and other materials is satisfactory.

The present invention has been made in view of the above facts, and aims to provide a method for adhering vulcanized rubber and thermosetting urethane elastomer, which has adhesive strength that can withstand dynamic use.

Means for Solving the Problems> The present invention provides a method for treating the surface of a vulcanized rubber with a solution (1) in which a halogen compound is dissolved in a solvent in the molecule, and then the amount of active isocyanate is 5 to 20% by weight. % of a diphenylmethane diisocyanate compound dissolved in a solvent (II).

The diphenylmethane diisocyanate compound is preferably a mixture of diphenylmethane diisocyanate and carbodiimide-modified diphenylmethane diisocyanate, and more preferably the mixture has an average number of active isocyanate groups of 2.3 or more.

Further, the diphenylmethane diisocyanate-based compound is preferably a mixture of diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate, and it is more preferred that the mixture has an average number of active isocyanate groups of 2.3 or more.

The solution (!) preferably further contains 2 to 20% by weight of a hydroxyl group-containing liquid diene polymer.

The present invention will be explained in detail below.

Vulcanized rubber, which is the adherend to which the present invention is applied, is a rubber composition in which a three-dimensional crosslinked structure is introduced between rubber molecules. Therefore - besides the numerical and most important sulfur vulcanization,
Vulcanized by methods such as thiuram vulcanization, peroxide vulcanization, quinoid vulcanization, resin vulcanization, metal salt vulcanization, metal oxide vulcanization, polyamine vulcanization, radiation vulcanization, hexamethylenetetramine vulcanization, etc. Also included are rubber compositions.

Here, rubber refers to natural rubber (NR) (the symbols in parentheses are abbreviations, the same applies hereinafter) and synthetic rubber.

Synthetic rubbers include polyisoprene rubber (IR), polybutadiene rubber (BR), and polychloroprene rubber, which are homopolymers of conjugated diene compounds such as isoprene, butadiene, and chlorobrene, and the above conjugated diene compounds and styrene,
Styrene-butadiene copolymer rubber (SBR), which is a copolymer with vinyl compounds such as acrylonitrile, vinylpyridine, acrylic acid, methacrylic acid, alkyl acrylates, and alkyl methacrylates;
Butadiene/styrene copolymer rubber, acrylonitrile/
Butadiene copolymer rubber, acrylic acid/butadiene copolymer rubber, methacrylic acid/butadiene copolymer rubber, methyl acrylate/butadiene copolymer rubber, methyl methacrylate/butadiene copolymer rubber, etc., and olefins such as ethylene, propylene, and isobutylene and dienes. copolymers such as isobutylene-isoprene copolymer rubber (IIR
), copolymers of olefins and non-conjugated dienes (EPD
M), for example, ethylene/propylene/cyclopentadiene terpolymer, ethylene/propylene/5-ethylidene-2-norbornene terpolymer, ethylene/propylene/1,4-hexadiene terpolymer, Included are polyalkenamers obtained by ring-opening polymerization of cycloolefins, such as polypentenamers, and rubbers obtained by ring-opening polymerization of oxirane rings, such as shrimp chlorohydrin rubber and polypropylene oxide rubber, which can be sulfur-cured.

In addition, halides of the various rubbers mentioned above, such as chlorinated isobutylene/isoprene copolymer rubber (CfL-11R)
, brominated isobutylene/isoprene copolymer rubber (Br-
IIR) etc. are also included.

These rubbers may be used alone or in a blend.

The vulcanizing agent may be any vulcanizing agent used in the above-mentioned vulcanizing method, and may be used alone or in combination of two or more.

In addition to the above-mentioned rubber and vulcanizing agent, the rubber composition also includes fillers such as carbon black, silica, calcium carbonate, and lignin, softeners such as mineral oil, vegetable oil, and synthetic plasticizers, anti-aging agents, It is not a problem to include compounding agents conventionally used in rubber compounding, such as vulcanization accelerators, but it is rather preferable.

Vulcanized rubber, which is the adherend subject to the present invention, is produced by kneading the above-mentioned rubbers, vulcanizing agents, and other compounding agents, and then using leaded vulcanization, direct steam vulcanization, mold molding vulcanization, indirect vulcanization, etc. It is obtained by vulcanization using methods such as sulfurization.

The vulcanized rubber that is the object of the present invention includes vulcanized rubbers of the various rubbers mentioned above, but in particular, natural rubber (NR), styrene rubber, which has been considered to have poor adhesive properties, Butadiene copolymer rubber (SBR) Polybutadiene rubber (BR) Polyisoprene rubber (IR) Isobutylene/isoprene copolymer rubber and its halides (I IR
% C11-11R, Br-11R), a copolymer of olefins and a non-conjugated diene (EPDM), even if the adherend is a vulcanized rubber, it is bonded to the urethane elastomer, which is a feature of the present invention. There is.

Solution (1) for treating the surface of vulcanized rubber is a solution in which an organic active halogen compound is dissolved in a solvent.

Examples of the organic active halogen compound having a succinimide include halogenated succinimides such as N-promsuccinimide, halides of isocyanuric acid such as trichloroisocyanuric acid and dichloroisocyanuric acid, and halogenated hydantoins such as dichloromethylhydantoin. Particularly preferred are halides of isocyanuric acid.

These may be used alone or in combination of two or more.

It is thought that the organic active halogen compound reacts with the unsaturated double bonds of the vulcanized rubber as shown in (X is halogen).

The solvent may be any solvent as long as it does not react with the above organic active halogen compound.

Specifically, aromatic hydrocarbons such as benzene and toluene, ethers such as diethyl ether, dioxane, and tetrahydrofuran, esters such as ethyl acetate, ketones such as methyl ethyl ketone and cyclohexanone, ethane chloride, chloroform, and tetrahydrofuran. Examples include chlorinated hydrocarbons such as carbon chloride, tertiary alcohols such as 311L butyl alcohol, and these are used alone or in combination of two or more.

The concentration of the organic active halogen compound in the solution (1) is not particularly limited, but from the solubility in the solvent and the processing effect, it is 0.
．． It is preferably 5 to 5% by weight. If it is less than 0.5% by weight, the effect is small, and if it is more than 5% by weight, unreacted substances will precipitate on the rubber surface, which is not preferable.

A solution having an adhesive effect (1) is a solution in which a diphenylmethane diisocyanate-based compound is dissolved in a solvent so that the amount of active isocyanate is 5 to 20% by weight.

Here, when converting to the amount of active isocyanate, the solution (
The amount of the diphenylmethane diisocyanate compound contained in II) is expressed as the weight of the active isocyanate group moiety in the diphenylmethane diisocyanate compound.

That is, the active isocyanate group portion in the molecular weight of a certain diphenylmethane diisocyanate compound is 30
If the solution (n) contains 50% by weight of this compound, then this solution (II) contains 15% by weight of the diphenylmethane diisocyanate compound in terms of the amount of active isocyanate.

The diphenylmethane diisocyanate-based compound used in the solution (11) is a compound having a diphenylmethane diisocyanate moiety in its molecule, and examples include diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, and polymeric diphenylmethane diisocyanate.

In the present invention, a mixture of diphenylmethane diisocyanate and carbodiimide-modified diphenylmethane diisocyanate is preferably used, and these compounds are in an equilibrium state as shown in the following formula (I).

Specific examples include Isonate 143L (MD Kasei Co., Ltd.).

Further, in the present invention, preferably, a mixture of diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate as shown in the following formula (II) is used.

(n is O or a positive integer) (II) Specifically, PAPI-135 (MD Kasei Co., Ltd.), PAPI-2
0 (MD Kasei Co., Ltd.), 40V-tO (Sumitomo Bayer Urethane Co., Ltd.), Millionate MR (Nippon Polyurethane Industries Co., Ltd.), MDI-CR (Mitsui Toatsu Chemical Co., Ltd.), and the like.
Among these, Millionate MR is calculated using the above formula (Natsuri de n
The mixture consists mostly of compounds of 5g051.2, but also contains compounds with n greater than 2 in appropriate proportions.

The mixture of diphenylmethane diisocyanate and carbodiimide-modified diphenylmethane diisocyanate and the mixture of diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate preferably have an average number of active isocyanate groups of 2.3 or more.

The diphenylmethane diisocyanate compound is produced by the reaction between the solution (1) and the vulcanized rubber, or reacts with the active groups on the rubber surface or the urethane elastomer to form a network and contribute to adhesion. To form this network, the diphenylmethane diisocyanate compound preferably has an average number of active isocyanate groups of 2.3 or more.

In addition, the concentration of diphenylmethane diisocyanate compound in the solution (!) is 5% in terms of the amount of active isocyanate.
~20% by weight.

If the amount is less than 5ffi, the adhesion effect will be small and 20% by weight.
If it is too thick, wetting with the adherend becomes poor, usable time is shortened, and foaming occurs, which is not preferable.

The solvent may be any solvent as long as it does not react with the diphenylmethane diisocyanate compound, specifically,
Examples of the solvent used in the solution (I) include the same solvents as those exemplified above.

As mentioned above, the solution (11) is a diphenylmethane diisocyanate compound dissolved in a solvent.
The solution may further contain 2 to 20% by weight of a hydroxyl group-containing liquid diene polymer.

Hydroxyl group-containing liquid diene polymers are liquid diene polymers such as liquid polyisoprene, liquid polybutadiene, liquid 1,2-polybutadiene, liquid styrene-butadiene rubber, and liquid acrylonitrile-butadiene rubber, in which hydroxyl groups are introduced at the end of the molecular chain. It is a compound that has been

Note that the liquid diene polymer includes both linear and branched polymers.

In the present invention, in particular, the average molecular weight is 500 to 500.
It is preferable to use a hydroxyl group-containing liquid diene polymer having about 0 and about 2 to 3 hydroxyl groups per molecule.

Those with an average molecular weight of less than 500 are difficult to manufacture industrially, and those with an average molecular weight of more than 5,000 have high viscosity and are difficult to dissolve in solvents.

When the solution (II) contains a hydroxyl group-containing liquid diene polymer, the content thereof is 2 to 20% by weight.

When the solution (!■) contains a hydroxyl group-containing liquid diene polymer, the affinity between the vulcanized rubber and the solution (!■) is further improved, and the wetting of the solution (II) becomes better, but the hydroxyl group-containing liquid diene polymer If the content of the system polymer is less than 2% by weight, this effect will not be exhibited, while if it exceeds 20% by weight, the adhesive strength will decrease.

The other adherend to be bonded to the vulcanized rubber is a thermosetting urethane elastomer.

Urethane elastomers are obtained by further chain-extending and crosslinking prepolymers, etc., which are reaction products of polyester polyols and/or polyether polyols and polyisocyanate compounds.

Before curing, thermosetting urethane elastomers consist of a liquid prepolymer with active isocyanate groups at the end and a diamine or diol, which are reacted to form a very common stable prepolymer that undergoes chain extension and crosslinking. Type: ■ Unstable prepolymer type, in which the starting materials are polyester and polyisocyanate compounds to create an unstable intermediate product, which is then cast and cured by adding a crosslinking agent; There is a type in which two components (polyester and polyisocyanate) are directly measured, mixed, and injected into a mold, and a urethane reaction is performed within the mold, but any type may be used.

Next, the bonding method of the present invention will be explained.

The bonding method of the present invention involves treating the surface of the vulcanized rubber with a solution, then applying the solution, placing it in a mold, and casting an uncured urethane elastomer precursor into the mold. , hardening.

Methods for treating the surface of vulcanized rubber with solution (1) include a method of immersing the vulcanized rubber in solution (I), a method of applying or spraying a solution on the vulcanized rubber, and the latter method is preferred. This method is based on

The contact time between the vulcanized rubber and the liquid (1) during surface treatment of the vulcanized rubber depends on the type of vulcanized rubber, the type of organic active halogen compound or solvent, and the concentration of the solution, but any of the above methods may be used. However, within 5 minutes is sufficient. Thereafter, the solvent may be volatilized at room temperature.

The solution (II) is applied after the solvent in the solution (II) has evaporated. -The application may be carried out by the usual methods such as printing, rolling, and spraying.After application, the solvent is removed at room temperature. Let it evaporate.

The vulcanized rubber whose surface has been treated with solution (II) is placed in a mold, and an uncured urethane elastomer precursor is poured into the mold and cured, forming a composite of the vulcanized rubber and urethane elastomer. can get.

Incidentally, the vulcanized rubber surface-treated with solutions (1) and (II) may be used after being left to stand for about - days.

Further, the urethane elastomer precursor may be cured by a normal heat curing method.

Before carrying out the method of the present invention, the surface of the vulcanized rubber is treated by degreasing with a solvent, puffing (making the surface rough) with a sand vapor grinder, grinding stone, sander, etc. If you leave the new surface of the rubber exposed,
You'll get even better results.

<Example> The present invention will be specifically explained based on examples.

The following experiment is a model experiment, so the vulcanized rubber used is sheet-shaped, but in reality, various shapes,
For example, it can be applied to vulcanized rubber in any shape such as plate, rod, sphere, fiber, etc.

(Example) A rubber composition whose composition is shown in Table 1 was prepared at a temperature of 145°C and a pressure of 5°C.
Press vulcanization was carried out for 30 minutes under the condition of 0 kg/cm" to obtain a 2 mm x 150 mm x 150 mm sheet of vulcanized rubber. This vulcanized rubber was puffed with a sander and further degreased with toluene, and used as an adherend. The surface of this vulcanized rubber sample was subjected to the following surface treatment.

That is, a 2% by weight solution of chlorinated isocyanuric acid in ethyl acetate (solution (I)) was applied to the surface of the sample with a brush, and after waiting for the solvent to evaporate and diffuse, the same operation was repeated a total of two times.

Next, as a solution (11), an ethyl acetate solution of a diphenylmethane diisocyanate compound (invention examples 1 to 6), an ethyl acetate solution of a diphenylmethane diisocyanate compound and a hydroxyl group-containing liquid diene polymer (
Invention Examples 7 to 10) or a methylene chloride solution of a polyisocyanate compound (Comparative Example 2) was applied to the sample surface with a brush, and the solvent was waited for to evaporate and diffuse.
After repeating the same operation twice, the inventive example was left for 4 hours, and the comparative example 2 was left for 2 hours. Moreover, in Comparative Example 1, this operation was not performed.

The vulcanized rubber that has undergone the above treatment is placed in a mold, and then
The thermosetting urethane elastomer precursor whose composition is shown in Table 2 was adjusted to a thickness of 2 mm and cast, and then
It was cured at 0° C. for 16 hours in a hot air circulation drying oven.

From these vulcanized rubber-urethane elastomer composites,
A strip-shaped sample with a width of 25 mm and a length of 150 mm was cut out, and a peel test was conducted in accordance with JIS K 6301. In addition, the peeled surface was observed to check for the presence or absence of foaming.

The results are shown in Table 3.

(Name) Nittle 1500 11AF Carbon Dianab Leaf Oil ^■-20 Shitanol 2181 Tsukurak Hetov 7inchen 3C Tsukushinoh PI CZ Heiblen L-100 Iparakyu 7min MT PAPI-135 PAPI-20 4V-10 Phisonate 14: LL Desho Deal I (Manufacturer) Nippon Zeon Salt Carbon Idemitsu Kosan Hitachi Chemical Ohmukai Shinko Chemical Sumitomo Chemical Industry Sumitomo Chemical Industry Mitsui Toatsu Chemical Ihara Chemical MD Kasei MD Kasei Shutomo Bayer Urethane MD Kasei Bayer [Composition (classification)] Rubber filler Softener Tackifier Anti-aging agent Anti-aging agent Vulcanization accelerator Prepolymer hardener Diphenylmethane diisocyanate compound Diphenylmethane diisocyanate compound Diphenylmethane diisocyanate compound Diphenylmethane diisocyanate compound Description of polyisocyanate compound] (Chemical composition, etc.) BR Carbon black process oil phenol formaldehyde resin 6-nitoxy 2.2.4-trimethyl-1,2-dihydroquinoline N-phenyl-N'-isopropyl-P-
Phenylene diamine N-cyclohexyl-2-benzothiazole sulfenamide Urethane prepolymer having an isocyanate group at the terminal 4-4'-methylene-bis(2-chloroaniline) diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate Mixture (average activity (soc7nate group number 2.7)) Mixture of diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate (average activity ('
/ cyanate group number 3 or more) Mixture of diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate (average number of active isocyanate groups 2.7) Mixture of diphenylmethane diisocyanate and Calko diimide-modified diphenylmethane diisocyanate (average number of active isocyanate groups 2.3) Triphenyl 20% methylene chloride solution of methane triisocyanate Po1y
bd b45) IT Idemitsu Petrochemical Liquid diene polymer containing hydroxyl groups 2.3 hydroxyl groups/molecule, average molecular weight 2800 polybutadiene poly(Sobren) Idemitsu Petrochemical Liquid diene polymer containing hydroxyl groups 2.3 hydroxyl groups/molecule , Polyisoprene with an average molecular weight of 2500 As is clear from Table 3, the method of the present invention (Invention Examples 1 to 2)
When a composite of vulcanized rubber and urethane elastomer is made in step 10), the adhesive (solution (II)) can be used for a long time and is easy to work with. In addition, the vulcanized rubber and the urethane elastomer adhere strongly enough to be used even under dynamic conditions, and no foaming occurs at the adhesive interface between the vulcanized rubber and the urethane elastomer. Contains a hydroxyl group-containing liquid diene polymer (Invention Examples 7 to 10)
and bond even more firmly.

On the other hand, if the diphenylmethane diisocyanate compound solution (solution (II)) is not used, the adhesive strength will be significantly reduced (Comparative Example 1). When using urethane elastomer, the usable time is short, so there is no leeway for work, and in addition, foaming occurs at the adhesive interface between vulcanized rubber and urethane elastomer (
Comparative Example 2).

<Effects of the Invention> The present invention provides a method for adhering a vulcanized rubber and a thermosetting urethane elastomer, which has adhesive strength that can be used in dynamic use.

The present invention is highly practical because it does not use strong special chemicals, does not deteriorate vulcanized rubber, and the adhesive used has a long usable time.

The present invention provides a composite material in which a vulcanized rubber such as NR%SBR, BR, or IR is firmly adhered to a thermosetting urethane elastomer.

Claims (6)

[Claims] (1) After treating the vulcanized rubber surface with a solution (I) in which an organic active halogen compound having a ▲mathematical formula, chemical formula, table, etc. in the molecule (X is a halogen) is dissolved in a solvent, the vulcanized rubber surface is activated. A method for adhering vulcanized rubber and urethane elastomer, comprising a step of applying a solution (II) in which a diphenylmethane diisocyanate compound is dissolved in a solvent so that the amount of isocyanate is 5 to 20% by weight. . (2) The method for bonding vulcanized rubber and urethane elastomer according to claim 1, wherein the diphenylmethane diisocyanate-based compound is a mixture of diphenylmethane diisocyanate and carbodiimide-modified diphenylmethane diisocyanate. (3) The method for bonding vulcanized rubber and urethane elastomer according to claim 2, wherein the mixture of diphenylmethane diisocyanate and carbodiimide-modified diphenylmethane diisocyanate has an average number of active isocyanate groups of 2.3 or more. (4) The method for bonding vulcanized rubber and urethane elastomer according to claim 1, wherein the diphenylmethane diisocyanate-based compound is a mixture of diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate. (5) The method for bonding vulcanized rubber and urethane elastomer according to claim 4, wherein the mixture of diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate has an average number of active isocyanate groups of 2.3 or more. (6) The method for bonding vulcanized rubber and urethane elastomer according to any one of claims 1 to 5, wherein the solution (II) further contains 2 to 20% by weight of a hydroxyl group-containing liquid diene polymer.