JPH0670210B2 - Pressure sensitive adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel pressure sensitive adhesive composition. More specifically, it relates to a silane crosslinkable curable composition, particularly a curable composition useful as a pressure-sensitive adhesive.

Various cross-linking methods have been proposed as one of the methods for increasing the cohesive force of pressure-sensitive adhesives. Among them, the urethane cross-linking method in which a polymer having a carboxyl group or a hydroxyl group is combined with a polyisocyanate cross-linking agent is generally used. Is. However, in the case of the urethane crosslinking method, the polyisocyanate crosslinking agent is very sensitive to moisture, active hydrogen groups such as carboxyl groups and hydroxyl groups present in the tackifying resin, and alcohol present in the solvent. Since it reacts, it has a drawback that it tends to hinder the intended crosslinking between the polymers. In addition to the above-mentioned drawbacks, there is also a problem that post-treatment such as aging or water treatment is required after coating and drying the base material in consideration of the curing speed, pot life or adhesive property.

As a result of intensive studies to solve the problems of the urethane cross-linking method as described above, the inventors of the present invention polymerized mainly using an alkyl (meth) acrylic acid alkyl ester having 4 to 14 carbon atoms in the alkyl group. The resulting acrylic polymer having the general formula (1) at the terminal and / or side chain of the molecule: (In the formula, R ¹ is a substituted or unsubstituted monovalent organic group, X is an alkoxy group, Y is a hydrogen atom or a monovalent organic group having a group selected from the group consisting of an epoxy group, a mercapto group and an amino group. Group, n represents 0, 1 or 2), and the silicon compound (A) is reacted with an acrylic polymer (B) having a functional group capable of reacting with the Y group of the silicon compound (A). It has been found that the above problems can be solved by using a pressure-sensitive adhesive composition containing the obtained polymer (C), and the present invention has been completed.

That is, in the present invention, since the alkoxy group-containing silicon functional group is introduced at the terminal and / or side chain of the molecule of the polymer (C), sufficient pot life at room temperature and quick curing characteristics at the time of heating can be obtained. In addition, since the alkoxy group-containing silicon functional group does not have high reactivity with active hydrogen compounds such as those found in isocyanates, it can be escaped from the restrictions on the type and blending amount of tackifying resin, and has a wide range of adhesive properties. It becomes possible to adjust it by blending the applied resin. Further, even if the composition of the present invention contains a solvent having an active hydrogen group such as alcohol, there is an advantage that the adhesive property is not deteriorated.

The silicon compound (A) represented by the general formula (1) used in the present invention is used for producing the polymer (C) used in the present invention by reacting with the polymer (B). Among the hydrolyzable groups, X in the general formula (1) is an alkoxy group such as a methoxy group or an ethoxy group from the viewpoint of easy handling. As the Y group in the general formula (1), a monovalent organic group having a group selected from the group consisting of an epoxy group, a mercapto group and an amino group or a hydrogen atom is selected from the viewpoint of easy handling. . R ¹ in the general formula (1) is a substituted or unsubstituted monovalent organic group, and is preferably a monovalent hydrocarbon group having 1 to 12 carbon atoms selected from an alkyl group and an aryl group. Specific examples of the silicon compound (A) represented by the general formula (1) include γ-glycidoxypropyltrimethoxysilane,
γ-glycidoxypropylmethyldimethoxysilane,
β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-
Aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-
(2-aminoethyl) aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane,
Examples thereof include methyldimethoxyhydrosilane, trimethoxyhydrosilane, and methyldiethoxyhydrosilane.

The polymer (B) used in the present invention has a functional group capable of reacting with the Y group of the silicon compound (A) represented by the general formula (1) at the terminal and / or side chain in the molecule, and is pressure sensitive. An acrylic polymer obtained by polymerizing a (meth) acrylic acid alkyl ester monomer having an alkyl group having 4 to 14 carbon atoms as a main component, which is particularly useful as a polymer used for an adhesive. Or) An acrylic polymer having a carboxyl group, a hydroxyl group, an isocyanate group, an epoxy group, an amino group, a halogen group or an unsaturated group such as a vinyl group or an allyl group in its side chain.

The acrylic polymer contains, for example, a (meth) acrylic acid alkyl ester monomer having an alkyl group with 4 to 14 carbon atoms as a main component, that is, contains 50 mol% or more of all monomers, and is copolymerized therewith. It can be easily obtained by a method such as copolymerizing the above-mentioned monomer with a monomer containing a functional monomer having a functional group capable of reacting with the Y group of the silicon compound (A). Examples of the (meth) acrylic acid alkyl ester having an alkyl group of 4 to 14 carbon atoms, which is the main component monomer of the acrylic polymer (B), include n-butyl (meth) acrylate and isobutyl (meth) acrylate. ,
2-Methylpentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate and the like can be mentioned. When the alkyl group has less than 4 carbon atoms or more than 14, or when the ratio of the alkyl group (meth) acrylic acid alkyl ester having 4 to 14 carbon atoms in the polymer (B) is less than 50 mol%. Unfortunately, the polymer becomes too hard, which is not preferable. Examples of the monomer copolymerized with the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, ethylene, acrylonitrile, vinyl acetate, isobutyl vinyl ether, styrene, acrylic acid amide, N, N. -Dimethylaminoethyl acrylate and the like.

Examples of the functional monomer having a functional group capable of reacting with the Y group of the silicon compound (A) contained in the polymer (B) include (meth) acrylic acid, itaconic acid, hydroxyethyl (meth) acrylate, and anhydrous. Specific examples include maleic acid, hydroxypropyl (meth) acrylate, N-methylolacrylamide, glycidyl (meth) acrylate, allyl (meth) acrylate and the like.

A polymerization initiator or the like may be used in copolymerizing these monomers. Examples of such a polymerization initiator include azobisisobutyronitrile, benzoyl peroxide, di-t-
In addition to usual polymerization initiators such as butyl peroxide and lauroyl peroxide, bisazodicyanovaleric acid, azobiscyanopental, oxalic acid peroxide, 2,2-azobis (2
A compound having a functional group capable of reacting with the organosilicon compound (A) such as -aminopropane) hydrochloride may be used.

When the monomer is polymerized, the molecular weight may be adjusted by the amount of the polymerization initiator or the chain transfer agent. As the chain transfer agent, lauryl mercaptan,
In addition to commonly used compounds such as dodecyl mercaptan and halogen-containing compounds, silicon compounds such as 2-mercaptoethanol, 2-aminoethanethiol, 2-mercaptoacetic acid, 2-mercaptoacetic acid glycidyl ester and trichloroacetic acid (A A compound having a functional group capable of reacting with) can be used.

As the polymerization initiator and the chain transfer agent, a compound containing an alkoxy group-containing silicon functional group is also known in advance, and as such a compound, Examples thereof include chain transfer agents. It contains such an alkoxy group-containing silicon functional group or a silicon compound (A)
By using a polymerization initiator or a chain transfer agent having a functional group capable of reacting with, it is possible to introduce an alkoxy group-containing silicon functional group at the end of the obtained polymer molecule, and particularly to obtain a polymer having a relatively low degree of polymerization. In some cases, the adhesive properties can have more favorable results.

As the solvent used for producing the polymer (B), known solvents such as benzene, toluene, xylene, hexane, cyclohexane, ethyl acetate and methanol can be used alone or in combination of two or more kinds. The amount of the solvent used may be adjusted according to the molecular weight of the target polymer. The polymerization temperature is usually in the range of 50 to 150 ° C, though it depends on the kind of the polymerization initiator used.

The molecular weight of the acrylic polymer obtained as described above is usually about 1000 to 1,000,000 and can be used in the present invention. The polymer having a molecular weight of 1,000 to tens of thousands can be handled in a high solid state with no solvent or a slight amount of solvent added, but in the case of about 100,000 to 1 million, a solvent type or It is better to handle in a water-dispersed state. If necessary, a tackifying resin may be blended with the polymer before use.

The polymer (B) referred to in the present invention is a polymer (a) obtained by one-step polymerization so that it can be used as it is by reacting with the Y group of the silicon compound (A), and (b) Y of the silicon compound (A).
Those having a functional group capable of reacting with the Y group of the silicon compound (A) by being pretreated with a pretreatment agent having a functional group capable of reacting with a group, (c) (a) or (b) It is a concept including those treated with a compound capable of reacting with both the Y group of the silicon compound (A).

The polymer obtained by using the pretreatment agent is pretreated with a polyisocyanate such as tolylene diisocyanate, hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and has a terminal and / or side chain. Pre-treated with an acrylic polymer having an isocyanate group in the chain or an acid halide such as (meth) acrylic acid chloride or (meth) acrylic acid bromide, and having an unsaturated group at the terminal and / or side chain Examples include polymers.

When the polymer (B) thus obtained is reacted with the silicon compound (A) to obtain the polymer (C) having an alkoxy group-containing silicon group, the reaction conditions are adjusted depending on the type of reaction by both. Although it is necessary, the copolymer (B) is usually placed in a container and brought to room temperature or a heated state, and a reaction accelerator is used if necessary, and the above silicon compound (A) is added to the polymer (B). It can be easily obtained by adding 0.1 to 1.2 times mol to the functional group and stirring and mixing to complete the reaction.

Examples of the reaction between the functional group in the polymer (B) and the functional group in the silicon compound (A) include the following examples, but the reaction is not limited thereto.

In the present invention, a tackifying resin can be blended, if necessary, for the purpose of adjusting the tackiness property. Many known tackifiers can be used, for example, rosin resin, modified rosin resin, rosin ester resin, terpene resin, terpene-phenol resin, phenol resin,
Examples include petroleum resin, coumarone resin, and xylene resin. If necessary, a filler, a softening agent, an ultraviolet absorber,
You may mix | blend antioxidant, a coloring agent, etc.

In the present invention, a curing catalyst can be used if necessary for the purpose of promoting curing. As a curing catalyst, titanic acid esters such as tetrabutyl titanate and tetrapropyl titanate; organic tin compounds such as dibutyltin dilaurate, dibutyltin maleate, dibutyltin diacetate, tin octylate and tin naphthenate; lead octylate;
Butylamine, octylamine, dibutylamine, monoethanolamine, diethanolamine, triethanolamine, diethylenetriamine, triethylenetetramine, oleylamine, octylamine, cyclohexylamine, benzylamine, diethylaminopropylamine, xylylenediamine, triethylenediamine, guanidine, diphenylguanidine. , 2,4,6-Tris (dimethylaminomethyl) phenol, morpholine, N-methylmorpholine, 1,8-diazabicyclo (5,4,0) undecene-7 (DBU) and other amine compounds or their carboxylic acids A salt such as; a low molecular weight polyamide resin obtained from excess polyamine and polybasic acid; a reaction product of excess polyamine and epoxy compound; a silane coupling agent having an amino group, For example, one or more known silanol condensation catalysts such as γ-aminopropyltrimethoxysilane and N- (β-aminoethyl) aminopropylmethyldimethoxysilane may be used as necessary.

The pressure-sensitive adhesive composition of the present invention thus obtained is different from the conventional urethane cross-linking type pressure-sensitive adhesive because it has an alkoxy group-containing silicon group introduced into its side chain and / or terminal. Long pot life at room temperature and fast curing when heated (that is, aging is not required) due to the use of appropriate curing catalysts and additives that are used according to It has a remarkable feature that there is no problem such as corrosion on the metal surface or corrosion.

The pressure-sensitive adhesive composition of the present invention can be applied to paper, release paper, cloth, non-woven fabric, plastic film, metal foil and the like and dried to obtain products such as pressure-sensitive adhesive tapes, sheets and labels. Hereinafter, the composition of the present invention will be described in more detail with reference to Examples. The present invention is not limited to the following examples.

Example 1 70 parts of butyl acrylate (parts by weight, the same applies hereinafter), 20 parts of 2-ethylhexyl acrylate, 8 parts of vinyl acetate, 2 parts of acrylic acid, 200 parts of toluene and 0.2 part of benzoyl peroxide were placed in a four-necked flask. , Stirred under nitrogen atmosphere, 75 ℃
It was polymerized for 8 hours. After adding 0.1 part of hydroquinone to this to terminate the polymerization, a mixed solution of 6.2 parts of γ-glycidoxypropylmethyldimethoxysilane, 0.2 part of benzyltrimethylammonium chloride and 10 parts of methanol was added, and the temperature was further raised to 100 ° C. After stirring for 22 hours, an acrylic polymer having a silyl group introduced was obtained.

To the obtained polymer was added 5 parts of an equimolar reaction product of dibutyltin oxide and dioctyl phthalate, and the mixture was coated on a polyester film having a thickness of 25 μm so that the paste thickness after drying would be 25 to 50 μm, and at 120 ° C. 3 After heating for a minute, an adhesive tape was obtained.

The obtained adhesive tape was attached to a stainless steel plate with a width of 2.5 cm, and the adhesive strength by 180 ° peeling at 23 ° C and 300 mm / min was measured. Also, glue the adhesive tape on a copper plate,
After curing for 7 days in an atmosphere of 80% humidity, the tape was peeled off and the presence or absence of corrosion on the copper surface was visually observed to measure metal corrosion. The results are shown in Table 1.

The obtained adhesive tape did not require so-called aging (aging at room temperature or 50 to 60 ° C. for several hours or several days) after drying at 120 ° C. for 3 minutes.

Also, put about 30 g of the obtained adhesive in an open container (100 cc polyethylene cup) and leave it at 23 ° C with occasional stirring, observe the condition, and apply until the coater does not evenly coat the film. Time, i.e. pot life, was measured. The results are shown in Table 1.

Example 2 92 parts of 2-ethylhexyl acrylate, 5 parts of vinyl acetate,
Glycidyl methacrylate (3 parts), toluene (180 parts), methanol (20 parts) and benzoyl peroxide (0.2 parts) were placed in a four-necked flask, and the mixture was stirred under a nitrogen atmosphere and polymerized at 75 ° C. for 8 hours. After adding 0.1 part of hydroquinone to this and stopping the polymerization, 0.1 part of 2,4,6-tris (dimethylaminomethyl) phenol was added, and after heating to 110 ° C., 3.8 parts of γ-mercaptopropylmethyldimethoxysilane. Was gradually added dropwise over 2 hours, and the mixture was further stirred for 2 hours to obtain an acrylic polymer having a silyl group introduced therein.

An adhesive tape was produced using the obtained polymer in the same manner as in Example 1, and the adhesive force and the metal corrosion property were measured. The pot life was measured in the same manner as in Example 1. The results are shown in Table 1.

Example 3 93 parts of butyl acrylate, 5 parts of vinyl acetate, 2 parts of allyl methacrylate, 180 parts of toluene, 20 parts of methanol, 0.2 part of benzoyl peroxide and 0.8 part of γ-mercaptopropylmethyldimethoxysilane were placed in a four-necked flask. In a nitrogen atmosphere, the mixture was stirred and polymerized at 75 ° C. for 6 hours. 0.1 part of a 10% isopropanol solution of chloroplatinic acid and 1.7 parts of methyldimethoxyhydrosilane were added to this, and the temperature was raised to 90 ° C, and 4
The mixture was stirred for reaction to obtain an silyl group-introduced acrylic polymer.

An adhesive tape was produced using the obtained polymer in the same manner as in Example 1, and the adhesive force and the metal corrosion property were measured. The pot life was measured in the same manner as in Example 1. The results are shown in Table 1.

Example 4 90 parts of 2-ethylhexyl acrylate, 3 parts of 2-hydroxyethyl acrylate, 7 parts of vinyl acetate, 0.2 parts of benzoyl peroxide and 200 parts of toluene were placed in a four-neck flask at 75 ° C. under a nitrogen atmosphere. Polymerization was carried out by stirring for 8 hours. on the other hand,
To another well-dried four-necked flask, 4.5 parts of tolylene diisocyanate, 0.1 part of dibutyltin dilaurate and 50 parts of toluene were added, and 300 parts of the above-mentioned polymer solution was added dropwise while heating and stirring at 80 ° C. to obtain an isocyanate group. An acrylic copolymer having This was cooled to room temperature, 4.2 parts of γ-aminopropylmethyldimethoxysilane was slowly added dropwise,
After stirring at room temperature for 4 hours, an acrylic polymer having a silyl group introduced was obtained.

An adhesive tape was produced using the obtained polymer in the same manner as in Example 1, and the adhesive force and the metal corrosion property were measured. The pot life was measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 To 300 parts of the acrylic polymer solution prepared in Example 1, 0.5 parts of polyisocyanate (Sumitomo Bayer Urethane Co., Ltd., trade name Sumidule L) was added as a cross-linking agent without treatment with a silicon compound. It was applied to a 25 μm thick polyester film so that the adhesive thickness after drying would be 25 to 50 μm, heated at 120 ° C. for 3 minutes and dried, and then left at room temperature for 3 days (aging) to obtain an adhesive tape. .

The obtained adhesive tape was used to measure the adhesive force and the metal corrosion property in the same manner as in Example 1. The pot life was measured in the same manner as in Example 1. The results are shown in Table 1.

Example 5 97 parts of butyl acrylate, 3 parts of acrylic acid, 3.5 parts of 2-mercaptoacetic acid, 0.5 part of azobisisobutyronitrile, and 20 parts of ethyl acetate were placed in a four-necked flask and placed under a nitrogen atmosphere at 70
The mixture was heated to 0 ° C., stirred for 6 hours, and polymerized to obtain an acrylic polymer having a carboxyl group at the terminal or side chain. To this
-9.3 parts of glycidoxypropyltrimethoxysilane,
A mixed solution of 0.2 part of benzyltrimethylammonium chloride and 10 parts of methanol was added, and the mixture was heated to 100 ° C. and stirred for 22 hours to obtain a low molecular weight acrylic polymer having a silyl group introduced at the terminal or side chain.

An adhesive tape was produced using the obtained polymer in the same manner as in Example 1, and the adhesive force and the metal corrosion property were measured. The pot life was measured in the same manner as in Example 1. The results are shown in Table 1.

Example 6 95 parts of 2-ethylhexyl acrylate, 2-acrylic acid
Hydroxyethyl 4.8 parts, 2-mercaptoethanol 3.5
Part, azobiscyanopentanol 0.5 part, ethyl acetate 10
Parts were placed in a four-necked flask and gradually heated to 70 ° C. under a nitrogen atmosphere condition and stirred for 6 hours to polymerize. On the other hand, another well-dried 4-neck flask was charged with 7.2 parts of tolylene diisocyanate, 0.05 part of tin octylate, and 10 parts of ethyl acetate, and the whole amount of the above-mentioned polymer was added dropwise while stirring with heating at 80 ° C. (Or) A low molecular weight acrylic polymer having an isocyanate group in the side chain was obtained. After cooling to room temperature, 0.05 part of tin octylate was further added, and 8.1 parts of γ-mercaptopropyltrimethoxysilane was gradually added dropwise to generate heat, but the reaction was completed after about 2 hours, and the end of the molecule and ( Or) A low molecular weight acrylic polymer having a silyl group in the side chain was obtained.

An adhesive tape was produced using the obtained polymer in the same manner as in Example 1, and the adhesive force and the metal corrosion property were measured. The pot life was measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 To 100 parts of the low-molecular-weight acrylic polymer having a carboxyl group at the terminal or side chain produced in Example 5, 3.0 parts of tolylene diisocyanate was added as a cross-linking agent without treatment with a silicon compound, and a thickness of 25 μm was obtained. Apply to the polyester film so that the glue thickness after drying will be 25-50 μm,
Heat at 120 ° C for 3 minutes to dry, and then at room temperature for 3 minutes.
I left it for a day and got an adhesive tape.

The obtained adhesive tape was used to measure the adhesive force and the metal corrosion property in the same manner as in Example 1. The pot life was measured in the same manner as in Example 1. The results are shown in Table 1.

Claims (1)

[Claims] 1. An acrylic polymer obtained by polymerizing a (meth) acrylic acid alkyl ester monomer having an alkyl group having 4 to 14 carbon atoms as a main component, wherein the terminal and / or the side of the molecule. General formula (1) in the chain: (In the formula, R ¹ is a substituted or unsubstituted monovalent organic group, X is an alkoxy group, Y is a hydrogen atom or a monovalent organic group having a group selected from the group consisting of an epoxy group, a mercapto group and an amino group. Group, n represents 0, 1 or 2), and the silicon compound (A) is reacted with an acrylic polymer (B) having a functional group capable of reacting with the Y group of the silicon compound (A). A pressure-sensitive adhesive composition containing the obtained polymer (C).