KR100307513B1 - Process For Preparing Blend-typed Polychloroprene Adhesives with Enhanced Adhesive strength - Google Patents

Abstract

The present invention is a method for producing a blended chloroprene-based rubber adhesive, in particular, graft copolymerized chloroprene-based rubber with monomers that give hardness and monomers that give softness when converted to resin, respectively, The present invention relates to a method of preparing a rubber adhesive that improves adhesive strength as well as controlling hardness and flexibility by blending a copolymer obtained by graft copolymering heterogeneous monomers.

Description

Process for preparing blend-typed polychloroprene adhesives with enhanced adhesive strength

The present invention provides a method for producing a blended chloroprene rubber adhesive, in particular, a graft copolymer of chloroprene rubber with monomers giving hardness and monomers giving softness when converted into a resin. In order to commercialize these heterogeneous graft copolymers, a polymer prepared by graft copolymerizing the monomers together is blended to provide a method for preparing a rubber adhesive that simultaneously improves hard / soft physical properties and adhesive strength. will be.

In general, chloroprene rubber has high polarity and crystallinity, and thus has high cohesiveness and initial adhesive strength, and relatively good heat resistance, water resistance, and aging resistance, and thus is a rubber-based adhesive and hard materials such as metal, wood (plywood), hard fiber board, and glass. It is widely used from the adhesion of soft materials such as natural or synthetic rubber, fiber, leather, vinyl leather, fiber cloth, urethane foam and the like.

Until now, adhesives made of chloroprene-based rubber have sufficient flexibility and elasticity to have high impact resistance, but problems with adhesive strength, heat resistance, and creep resistance when high loads are applied (Ency. Polym. Sci. & Eng., Vol 3, 1985, p. 451). In order to remedy this disadvantage, chlorinated polypropylene (see US Pat. No. 5,753,727) or phenolic resins (see Japanese Patent Application Laid-Open Nos. 3-17,140 and 3-177,475, and Eur. Pat. Appl. EP 441480). In addition, the bond strength was increased by crosslinking by metal oxides (see Japanese Patent Application Laid-Open Nos. 4-309,586 and 7-126,593, and Ger. Offen. 2,356,656), but the crosslinking reaction rate was very high at room temperature. It was slow and required a high temperature of 90 ° C. or higher even when using a crosslinking accelerator.

Recently, silanol structures have been introduced into chloroprene rubbers (see Japanese Patent Laid-Open Nos. 62-57,474 (1987) and 1-301,776) to cause crosslinking by moisture in the air, and chloroprene obtained from the monomers. After obtaining an emulsion type copolymer such as / acrylate or chloroprene / methacrylate, the adhesive strength to the vinyl chloride resin was increased through the blending process (see US Patent No. 5,407,993).

In addition, by using chloroprene rubber containing carboxyl groups as a raw material, metal oxides such as MgO and ZnO (see Japanese Patent Application Laid-Open Nos. 4-309586, 5-179216 and 5-295,336) as crosslinking agents in a short time. Cohesion was improved by thermal crosslinking. In this case, since the reaction between the carboxyl group and the metal oxide proceeds in the solution and the viscosity is increased, it is inconvenient to adjust the viscosity by adding alcohols.

In addition, conventionally, methyl methacrylate or styrene (see US Pat. No. 4,366,289) and cyclohexyl methacrylate [J. Appl.Polym. Sci., 64, 1973 (1977)], graft copolymerization reactions with only monomers which become hard components upon conversion to resins such as methyl methacrylate or acrylonitrile (see Japanese Patent Application Laid-Open No. 5-86,347). In most cases, there was a limit in improving the adhesive strength by increasing the hardness of the adhesive itself. In other words, chloroprene rubber has improved adhesive properties such as graft copolymerization of hard monomers when converting to resin to increase cohesiveness. In this case, cohesion is compensated and adhesive strength increases. After that, the adhesive strength was reduced.

As described above, the conventional techniques used a method of physicochemically blending another hard resin-based material or a method of crosslinking with a metal oxide as a main method to compensate for the shortcomings of the chloroprene rubber adhesive. Since it has its own problems, it was intended to develop a blended chloroprene-based rubber adhesive that blends heterogeneous graft copolymers with commercially available graft copolymers to improve hard and soft physical properties as well as adhesive strength.

The present inventors 1) graft copolymerized monomer ('hard monomer') having high glass transition temperature (T _g ) to chloroprene rubber to give hardness upon conversion to resin ('hard graft copolymer). 2) graft copolymers of chloroprene rubber with low glass transition monomers ('soft monomers') that give flexibility and adhesion when converted to resins. To the chloroprene rubber together with the monomer which gives hardness and the monomer which gives softness when converting into the resin so that the soft graft copolymer and the hard graft copolymer can be commercialized. Graft copolymerization produces polymers ('commercial graft copolymers') and blends these three copolymers to improve cohesion and adhesion while improving adhesion strength Find out that they can kill and completed the present invention.

The method for producing a blended chloroprene rubber adhesive according to the present invention comprises (a) dissolving chloroprene rubber in 6 to 18 parts by weight of an organic solvent to form a chloroprene rubber solution, and then (b) converting to a resin at 100 to 105 ° C. A monomer ('hard monomer') having a glass transition temperature within a range and giving a hard component is mixed with a polymerization initiator in the chloroprene rubber solution at 0.1 to 1.5 parts by weight with respect to the chloroprene rubber and graft copolymerized to give a polymer ('hard graphene'). To the chloroprene rubber), and (c) a monomer ('soft monomer') having a glass transition temperature in the range of -22 to -85 ° C to give a soft component when converted to a resin (c). In addition, the chloroprene rubber solution is mixed with a polymerization initiator to be graft copolymerized to form a polymer ('soft graft copolymer'), and (d) A monomer which gives a softer and a softness is mixed, but is mixed with a polymerization initiator in the chloroprene rubber solution at 0.1 to 1.5 parts by weight with respect to the chloroprene rubber to obtain a polymer ('commercial graft copolymer') (e) ) Blending the hard graft copolymer and the soft graft copolymer with a graft copolymer for commercialization. Preferably, after each graft copolymerization reaction is completed or in the blending step, a polymerization inhibitor and / or a tackifier resin may be added.

The chloroprene rubber includes all kinds that can be generally included in chloroprene rubber, such as polychloroprene, carboxy modified polychloroprene, copolymers thereof, and blends thereof.

In the present invention, one or two or more selected from methyl methacrylate, acrylonitrile, and styrene are selected as the monomer which gives the hardness to give a hardness when the resin is converted into a hard component. As a monomer to give flexibility as a component, one or two or more selected from ethyl acrylate, butyl acrylate, lauryl methacrylate and 2-ethylhexyl acrylate are selected, and these are graft copolymerized with chloroprene rubber, respectively. By making a polymer, and blending these different monomers graft copolymer with chloroprene rubber using a compatibilizer as a compatibilizer, it is possible to obtain a blended rubber adhesive that can control the hardness and flexibility and improve the adhesive strength . At this time, in order to control the physical properties of the adhesive, the graft copolymers are prepared by adjusting the ratio of monomers according to the expected physical properties between the grafted components of the polymers that become hard or soft upon conversion to the resin.

Therefore, after completely dissolving the chloroprene rubber in the organic solvent, the methyl methacrylate (T _g : 105 ℃), acryl with high glass transition temperature (T _g ) at the time of conversion to the copolymer resin can impart hardness Hard components such as nitrile (T _g : 100 ° C.) and styrene (T _g : 100 ° C.) and ethyl acrylate (T _g : -22 ° C.) that can give flexibility with low T _g when converted to copolymer resin ), Butyl acrylate (T _g : -54 ° C), lauryl methacrylate (T _g : -65 ° C) and 2-ethylhexyl acrylate (T _g : -85 ° C), etc. By graft copolymerization reaction by the polymerization initiator separately in the organic solution of the chloroprene rubber by the appropriate control according to the above, to produce a graft copolymer having both the hard and soft components to commercialize these copolymers By blending together, It is possible to obtain a blended chloroprene-based rubber adhesive, which not only adjusts the physical properties of the flexibility but also improves the adhesive strength.

In the present invention, the ratio of the monomer giving hardness when converting to the resin by graft copolymerization to chloroprene rubber, the monomer giving softness, and the monomers giving hardness and softness is 0.1 to 1.5 parts by weight relative to chloroprene rubber.

The hard monomer has a glass transition temperature of 100 to 105 ° C., and becomes a part to impart hardness upon conversion to the copolymer resin, and an appropriate amount of the hard monomers is 55 to 95 to the total amount of the monomer. Weight percent. If the amount used is less than 55% by weight, the cohesive force of the rubber adhesive is insufficient, and if more than 95% by weight, the flexibility of the rubber adhesive is lowered.

On the other hand, the monomer giving the softness has a low T _g of -22 to -85 ° C., and becomes a part to give softness at the time of conversion to the copolymer resin, and the appropriate amount of the monomers giving the softness is based on the total amount of the monomers. 5 to 45% by weight. If the amount is less than 5% by weight, the flexibility is insufficient, and if the amount is more than 45% by weight, the adhesive strength is lowered.

Organic solvents according to the present invention include benzene, toluene, xylene, methyl ethyl ketone, isobutyl methyl ketone, ethyl acetate, butyl acetate, n-pentane, n-hexane, cyclohexane, methylcyclohexane, dichloromethane and trichloroethylene One or more selected solvents were used. The appropriate amount of the solvent is chloroprene rubber It is 6-18 weight part. If the amount is less than 6 parts by weight, the viscosity of the solution in which the chloroprene rubber is dissolved is too great to interfere with the reactor agitation. If the amount is more than the weight part, the collision frequency between the chloroprene rubber and the monomers is small, so the graft efficiency is poor.

In the present invention, the graft copolymerization reaction is carried out at 50 to 90 ° C. under a nitrogen stream, so that the graft efficiency is poor in a reaction of 50 ° C. or lower, and in the reaction at 90 ° C. or more, the organic solvent is partially refluxed in the cooler to thereby concentrate the reaction solution. Since it becomes impossible to make uniform the copolymerization reactant of a uniform solution is not obtained.

As the graft copolymerization initiator in the present invention, benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, di-t-butyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, 2,5 One or two or more catalysts selected from radical polymerization catalysts such as -dimethylhexyl dihydroperoxide, diisopropylbenzene peroxide, t-butylhydrobenzoate and t-butylperoxyacetate are used. The proper amount of the catalyst is 0.5 to 5% by weight based on the total amount of the monomers used. When the amount of the catalyst used is less than 0.5% by weight, the reaction time becomes very long, and when the amount of the catalyst is used more than 5% by weight, the solution viscosity is rapidly increased as partial crosslinking occurs during storage.

In the present invention, after terminating the graft copolymerization of the monomers to the chloroprene rubber, in order to prevent another side reaction such as crosslinking reaction by the radical initiator remaining without participating in the reaction, Phenothiazine, hydroquinone, hydroquinone methyl ether, 4-t-butylcatechol, N, N'-diethylhydroxyamine, 2,4-dinitrophenol, and the like as a polymerization inhibitor soluble in the reacted organic solvent. It can also be used in a ratio of 0.03 to 3% by weight based on the total solids. In this case, when the amount is less than 0.03% by weight, the polymerization inhibitory effect on the long-term storage of the rubber adhesive is less, and when more than 3% by weight, the adhesive strength decreases little by little.

In the present invention, in order to improve the adhesion to the chloroprene rubber adhesive solution after the graft copolymerization reaction or before blending or after blending, petroleum resin, alkylphenol resin, phenylphenol resin, terpene phenol resin, rosin phenol resin, rosin ester resin And tackifying resins such as coumarone indene resin and the like may be added in a proportion of 0.1 to 7% by weight based on the total solids of the rubber adhesive solution. In this case, when the amount of the tackifier resin is less than 0.1% by weight, there is no improvement in adhesive strength, and when it is 7% by weight or more, the adhesive strength is lowered.

As described above, the blend-type chloroprene-based rubber adhesive in the present invention, unlike the conventional manufacturing method, chloroprene monomers such as methyl methacrylate, acrylonitrile, styrene, etc., which becomes a hard component when the monomer is converted into a resin Graft copolymerization is performed on the rubber to obtain a hard graft copolymer, and ethyl acrylate, butyl acrylate, and la as a soft component when the resin is converted to improve the adhesive strength while maintaining the flexibility of the rubber. Graft copolymerization of monomers such as uryl methacrylate and 2-ethylhexyl acrylate to obtain a soft graft copolymer, so that the hard polymer and the soft polymer can be easily mixed with each other, the heterogeneous monomer Hard polymerization using a copolymer obtained by graft copolymerization together as a compatibilizer By blending with a soft polymer, wherein the rigid graft copolymer and softness graft copolymer is obtained a blend type chloroprene rubber-based adhesive which is further improved flexibility and bond strength than when used alone.

The present invention also relates to blended rubber adhesives produced by these methods.

Specifically, 1) a polymer obtained by graft copolymerization of a monomer having a high glass transition temperature ('hard monomer') to chloroprene rubber ('hard graft copolymer'), which can give hardness when converted to a resin, 2) a polymer obtained by graft copolymerization of a monomer having a low glass transition temperature ('soft monomer') to chloroprene rubber ('soft graft copolymer') that can give flexibility and adhesion when converted to a resin and 3 ) relates to the beulraen de-type rubber adhesive prepared by blending the polymer ( "compatibilizing graft copolymer") in which the graft copolymer in a chloroprene rubber with the said hard monomer and soft monomer.

Preferably, the polymerization inhibitor and the tackifier resin may be further added during or after the preparation of the blended rubber gluing body.

Example

Although the present invention is described in more detail in the following Examples, the present invention is not limited by the Examples.

Preparation of Hard Component Graft Copolymer

(Examples 1 to 3, 7 to 9 and 14 to 15)

Example 1: In a reactor equipped with a cooler and a stirrer, 6 g of chloroprene rubber was dissolved in 80 g of toluene, 8 g of acrylonitrile was used as a monomer, and 0.01 g of benzoyl peroxide (1.5 wt% based on the total amount of monomers) was added as a polymerization initiator. It melt | dissolved completely and graft-copolymerized at 80 degreeC for 6 hours, and obtained the solution of 8.8 g of solid content. After the polymerization was completed, a rubber adhesive containing hard graft copolymer as a main component was prepared by mixing 0.2 g of hydroquinone (2.0 wt% based on the total amount of monomers) as a polymerization inhibitor and 0.05 g of terpene phenol resin as a tackifying resin. It was.

Other examples were carried out in the same manner as in Example 1 except for the type and use of each component, the experimental conditions are listed in Table 1.

Preparation of Soft Graft Copolymers

(Examples 4-6, 10-13 and 17-20)

Experiments on the preparation of the rubber adhesive based on the soft graft copolymer were also performed in the same manner as in Example 1, and the experimental conditions are shown in Table 1.

Except when the other conditions attached to the physical properties of the solution adhesive obtained in Examples 1 to 20 of Table 1 and Examples and Comparative Examples of Tables 2 to 4 to be described below were obtained as follows.

1) The weight of solids is measured by drying until no further weight loss in 80 ℃ oven,

2) Glass transition temperature (T _g ) is the value measured on the basis of solid content,

3) Adhesion strength is uniformly ground the surface of nylon cloth reinforced with chlorosulfonated polyethylene sheet by hand grinder (size: 100), cut the sheet into pieces (2.5cm ?? 15.2cm), On each side, apply the two kinds of adhesive solution made above with a brush and leave it for about 20 minutes, and then press and apply both sides of the applied surfaces while pressing them back and forth about 4-5 times using a steel roller for 3 days. Measured at room temperature and pulled at 300 mm / min (T-peel)

4) The uniformity of the adhesive is evaluated to see if there is agglomeration of some resins in the adhesive solution. There is no cohesion of '○' (uniform) and the agglomeration of 'X' (nonuniform).

In Table 1 above,

CR: Chloroprene Rubber (A90, Japan Electrochemical)

MMA: Methyl methacrylate

AN: Acrylonitrile

ST: Styrene

EA: ethyl acrylate

BA: Butylacrylate

LMA: lauryl methacrylate

EHA: 2-ethylhexyl acrylate

TP: Tefrenphenol Resin (SP560, Schenectady, USA)

RET: rosinglycerol ester (WI-200, Wooin Chemical)

Tg is the glass transition temperature and is calculated based on the content of solids except for the tackifier resin.

Preparation of Commercial Graft Copolymers (Examples 21-31)

Example 21: Methyl methacrylate 5.0 as a monomer giving hardness upon conversion to a resin in order to prepare a graft copolymer for commercialization which can be used as a compatibilizer of the hard graft copolymer and the soft graft copolymer. Except for graft copolymerization of 2.0 g of ethyl acrylate and 3.0 g of butyl acrylate as g monomers giving softness to g, the graft copolymerization reaction was carried out to the chloroprene rubber. Indicated.

Other Examples 22 to 31 were carried out in the same manner as in Example 21, and experimental conditions are shown in Table 2.

In Table 2, CR, MMA, AN, ST, EA, BA, LMA, EHA, TP, RET and Tg are the same as in Table 1.

Preparation of Blended Rubber Adhesives (Examples 32 to 43)

Example 32: Blend 1.75 g of hard graft rubber adhesive from Example 1 with 0.34 g of soft graft rubber adhesive from Example 4 and 0.08 g of compatibilizer from Example 21 to blend 8.17 g of solids Rubber adhesives were prepared.

Other Examples 33 to 43 were also performed in the same manner as in Example 32, and the experimental conditions are shown in Table 3 below.

In Table 3, CR is the same as in Table 1, the amount of solids of the adhesive does not include the amount of use of the tackifier resins, T _g of the adhesive on the basis of elemental analysis of solids excluding the tackifier resins and compatibilizers The calculated value.

Comparative Example 1

In a reactor equipped with a cooler and a stirrer, 8 g of chloroprene rubber was dissolved in 90 g of toluene, 10 g of methyl methacrylate as a monomer and 0.07 g of benzoyl peroxide as a polymerization initiator were completely dissolved, and the graft copolymerization reaction was carried out at 80 ° C. for 6 hours. After the polymerization was completed, 0.02 g of hydroquinone methyl ether as a polymerization inhibitor and 0.11 g of terpene phenol resin as a tackifying resin were added to this solution to prepare a rubber adhesive.

Comparative Examples 2-16

In Comparative Example 1, the amount of chloroprene rubber, the type of monomer and its amount, the amount of polymerization initiator, the type and amount of the tackifying resin and the amount of the polymerization inhibitor were used as shown in Table 4. It was carried out in the same manner as. Solid content and physical property of the adhesive obtained by each comparative example are shown in Table 4.

In Table 4, the contents of CR, MMA, AN, BA, EHA, TP, RET and T _g are the same as in Table 1.

Blended chloroprene-based rubber adhesive prepared by the production method of the present invention can easily control the hardness and softness, thereby exhibiting the effect of improving the excellent adhesive strength while maintaining flexibility.

The excellence of such an effect is that the physical properties of Examples 1 to 20 of Table 1 for the case where the rubber adhesives obtained by the polymerization reaction with only monomers giving rigidity or monomers giving softness at the time of conversion to resin are used alone, It can be confirmed from the fact that these two components are inferior to the physical properties of Examples 21 to 31 in Table 2 when used in combination.

In addition, looking at the superiority of the setting of the reaction conditions in the present invention through Table 4, 1) when the graft copolymerization reaction with only a monomer that is converted to the resin to give a rigidity (Comparative Examples 1 to 5), 2) When the monomers giving hard or soft components when converting to resin are somewhat more or less than appropriate amounts (Comparative Examples 3 to 7), 3) When only solvents having a large chain transfer effect are used (Comparative Example 8), 4 6) When the dilution solvent used is more or less than the proper amount (Comparative Examples 9 to 10), 5) When the amount of the initiator used is more or less than the proper amount (Comparative Examples 11 to 12), 6) The polymerization inhibitor used Experimental fact that the rubber adhesive bond strength was lowered when the amount of was greater or less than the appropriate amount (Comparative Examples 13-14) and 7) When the amount of the tackifying resin used was greater or less than the appropriate amount (Comparative Examples 15-16). Confirmed in.

Claims (8)

(a) dissolving chloroprene rubber in 6 to 18 parts by weight of an organic solvent to form a chloroprene rubber solution, and (b) a monomer having a glass transition temperature in the range of 100 to 105 ° C. to become a hard component upon conversion to a resin ('hard To the chloroprene rubber in an amount of 0.1 to 1.5 parts by weight with respect to the chloroprene rubber solution is mixed with a polymerization initiator to graft copolymerization to form a polymer ('hard graft copolymer'), (c) -22 ~ Graft copolymerization is carried out by mixing a monomer having a glass transition temperature in the range of -85 ° C and becoming a soft component ('soft monomer') at 0.1 to 1.5 parts by weight based on chloroprene rubber with a polymerization initiator in a chloroprene rubber solution. To form a polymer ('soft graft copolymer'), and (d) converting the monomer to the chloroprene rubber together 0.1 to 1.5 parts by weight of the chloroprene rubber solution is mixed with a polymerization initiator to graft copolymerization to produce a polymer ('commercial graft copolymer'), and (e) the hard graft copolymer and soft graft air. Method for producing a blended rubber adhesive comprising the step of blending the copolymer with the graft copolymer for commercialization. The method according to claim 1, comprising adding a polymerization inhibitor and / or a tackifier after each graft copolymerization reaction is completed or in a blending step. The method according to claim 1 or 2, wherein the amount of the hard monomer giving 55 to 95% by weight of the total amount of the monomer. The organic solvent according to claim 1 or 2, wherein the organic solvent is benzene, toluene, xylene, methyl ethyl ketone, isobutyl methyl ketone, ethyl acetate, butyl acetate, n-pentane, n-hexane, cyclohexane, methylcyclohexane, 1 or 2 or more types selected from dichloromethane and trichloroethylene; The hard monomer is one or a mixture of two or more selected from methyl methacrylate, acrylonitrile and styrene; The method of producing the soft monomer is one or a mixture of two or more selected from ethyl acrylate, butyl acrylate, lauryl methacrylate and 2-ethylhexyl acrylate. The method of claim 1, wherein the polymerization initiator is benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, di-t- butyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, 2,5-dimethyl Hexyldihydroperoxide, diisopropylbenzeneperoxide, t-butylhydrobenzoate and t-butylperoxyacetate selected from the group consisting of one or two or more, and the amount of the polymerization initiator is from 0.5 to the total amount of the monomers used. 5% by weight of the preparation method. 3. The tackifying resin according to claim 2, wherein the tackifying resin is one or a mixture of two or more selected from petroleum resins, alkylphenol resins, phenylphenol resins, terpene phenol resins, rosin phenol resins, rosin ester resins and guaron indene resins. The amount of the imparting resin is 0.1 to 7% by weight based on the solids produced after the copolymerization reaction; The polymerization inhibitor is one or a mixture of two or more selected from phenothiazine, hydroquinone, hydroquinone methyl ether, 4-t-butylcatechol, N, N'-diethylhydroxyamine, and 2,4-dinitrophenol; , The amount of the polymerization inhibitor is 0.03 to 3% by weight based on the total solids. 1) A polymer obtained by graft copolymerization of a monomer having a high glass transition temperature ('hard monomer') to chloroprene rubber when converted to a resin ('hard graft copolymer'), 2) the monomers ( "soft monomer"), a graft copolymer in which a polymer ( "softness graft copolymer") in a chloroprene rubber, and 3) obtain the low glass transition temperature at the time of switching of a resin can give a flexibility and adhesion A blend-type rubber adhesive prepared by blending a polymer ('commercial graft copolymer') obtained by graft copolymerization of the hard monomer and the soft monomer to a chloroprene rubber upon conversion to a resin. 8. The blended rubber adhesive according to claim 7, wherein a polymerization inhibitor and a tackifying resin are added.