JPH0257109B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a novel acrylic pressure-sensitive adhesive composition. More specifically, the present invention relates to an acrylic pressure-sensitive adhesive composition that has improved tack, especially tack and polyolefin adhesion at low temperatures. [Prior Art] Adhesives are also called pressure-sensitive adhesives, and have the property of easily adhering to the surface of an object with a small amount of pressure, such as pressing with a fingertip. Examples of uses for adhesives include cellophane tapes, electrically insulating vinyl tapes, masking tapes, adhesive sheets, and adhesive labels. Adhesives are required to have various properties, but the following three properties are particularly important. Adhesive strength (The force required to attach an adhesive product such as tape to an adhesive surface and then peel it off from the adhesive surface after applying sufficient pressure and time. It depends on the application, but the higher the strength, the better.) Degree of stickiness. This is a measure of the ease with which it sticks to the adherend. Normally, the larger the better.) Holding power (creep resistance. When a force parallel to the adhesive surface is applied to the base material, the difference between the base material and the adherend (The size of the deviation in relative position to the object. The smaller the deviation, the better.) Traditionally, adhesives have been mainly made of natural rubber or synthetic rubber, and have been mixed with tackifying resins, softeners, fillers, etc. and acrylic adhesives, which are obtained by copolymerizing acrylic acid ester as a main monomer with polar monomers such as acrylic acid and vinyl acetate, are widely used. Rubber adhesives have relatively good tack and adhesion, and also have relatively good adhesion to adherends that are difficult to adhere to, such as polyolefins such as polyethylene and polypropylene (hereinafter referred to as polyolefin adhesion). Durability such as heat resistance and weather resistance is insufficient. On the other hand, although acrylic pressure-sensitive adhesives have good durability, they have the disadvantage of lacking tack and olefin adhesion. In order to solve this drawback of acrylic adhesives, it is known to add a tackifying resin to acrylic adhesives, but although this improves polyolefin adhesion, the tack is further reduced, especially at low temperatures. There is a problem in that the tack that can be achieved is reduced. [Problems to be Solved by the Invention] The present invention solves the drawbacks of conventional acrylic pressure-sensitive adhesives. It was made for the purpose of obtaining a pressure-sensitive adhesive composition. [Means for Solving the Problems] As a result of intensive studies to solve these problems, the present inventors found that (A) an alkyl ester of acrylic acid whose alkyl group has 2 to 14 carbon atoms is the main component; 100 parts by weight of an acrylic polymer obtained by polymerizing monomers (B) 1 to 70 parts by weight of a polyether having at least one reactive silicon group in one molecule, and (C) a curing catalyst The present invention was completed based on the discovery that the above object can be achieved by an acrylic pressure-sensitive adhesive composition containing 0.1 to 10 parts by weight. [Example] The acrylic polymer used as component (A) in the present invention is a polymer obtained by polymerizing monomers mainly composed of alkyl esters of acrylic acid in which the alkyl group has 2 to 14 carbon atoms. It is. Specific monomers forming such acrylic polymers include ethyl, propyl, n-butyl, isobutyl, 1-ethylpropyl, 1-methylpentyl, 2-methylpentyl, and 3-acrylic acid. Methylpentyl, 1-ethylbutyl, 2
Examples include esters such as -ethylbutyry, 3-ethylbutyl, 2-ethylhexyl, 3,5,5-trimethylhexyl, decyl, and dodecyl.
These may be used alone or in combination of two or more. The acrylic polymer used in the present invention may also contain a relatively small amount of other copolymerizable monomers by copolymerization. Specific examples of these monomers include ethylene, propylene, vinyl chloride, acrylonitrile, methacrylic acid alkyl ester, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, glycidyl methacrylate, and N-methylol. Examples include acrylamide, N-butoxymethylacrylamide, N-methylolacrylamide, trimethoxysilylpropyl methacrylate, but are not limited to these. These may be used alone,
Two or more types may be used in combination. The amount of these copolymerizable monomers used is preferably 0.5 to 50% by weight, more preferably 1 to 20% by weight, based on the total amount of monomers. Polymerization methods for the acrylic polymer (A) include solution polymerization, which involves polymerization in an organic solvent such as ethyl acetate or toluene, and emulsion polymerization, which involves emulsifying monomers in water or an organic solvent using an emulsifier. A suspension polymerization method in which monomers are dispersed in water using a suspending agent and polymerized can be used. There is no particular limitation on the molecular weight of component (A), but a molecular weight of tens of thousands to several million is preferably used. Also, (A)
The acid value (KOHmg/g) of the component is preferably greater than 10. If it is less than 10, curing will be slow and the holding power will be unstable. The polyether component (B) must have a reactive silicon group. Reactive silicon groups are those that condense and react with moisture and additives, such as hydrolyzable groups and silanol groups bonded to silicon atoms, and are typically represented by the general formula (1): (In the formula, R〓 is the same or different carbon number 1 to 20
monovalent hydrocarbon group or triorganosiloxy group, a is 0, 1, 2 or 3, b is 0, 1 or 2, provided that 1≦a+b≦4, X is selected from a silanol group or a hydrolyzable group (where m is an integer selected from 0 to 18). A polyether having such a reactive silicon group has, for example, the general formula (2): A silicon hydride compound represented by and general formula (3): (In the formula, R〓 is a divalent organic group having 1 to 20 carbon atoms, R〓
is hydrogen or a monovalent organic group having 1 to 20 carbon atoms, and C is an integer of 0 or 1). , a platinum aldehyde complex, a platinum ketone complex, and the like by addition reaction using a platinum-based compound as a catalyst. In general formula (1) or general formula (2), R〓 is the same or different monovalent hydrocarbon group having 1 to 20 carbon atoms, such as an alkyl group such as methyl or ethyl;
selected from cycloalkyl groups such as cyclohexyl, aryl groups such as phenyl groups, aralkyl groups such as benzyl groups, and furthermore, those with the general formula (R′) ₃ SiO−
(R' represents the same or different monovalent hydrocarbon groups having 1 to 20 carbon atoms) may be a triorganosiloxy group. General formula (1) or general formula (2)
In, X represents a silanol group or a different or similar hydrolyzable group, examples of which include a halogen group, a hydride group, an alkoxy group,
Acyloxy group, ketoximate group, amino group,
Examples include amide group, aminooxy group, mercapto group, and alkenyloxy group. Examples of the silicon hydride compound represented by the general formula (2) include halogenated silanes such as trichlorosilane, methyldichlorosilane, dimethylchlorosilane, and trimethylsiloxydichlorosilane; trimethoxysilane, triethoxysilane,
Alkoxysilanes such as methyldimethoxysilane, phenyldimethoxysilane, 1,3,3,5,5,7,7-heptamethyl-1,1-dimethoxytetrasiloxane; methyldiacetoxysilane, trimethylsiloxymethylacetoxysilane, etc. Acyloxysilanes; Ketoximate silanes such as bis(dimethylketoximate)methylsilane, bis(cyclohexylketoximate)methylsilane, bis(diethylketoximate)trimethylsiloxysilane; dimethylsilane,
Examples include hydrosilanes such as trimethylsiloxymethylsilane and 1,1-dimethyl-2,2-dimethyldisiloxane; alkenyloxysilanes such as methyltri(isopropenyloxy)silane, but are not limited to these. do not have. In this method, after reacting the silicon hydride compound of general formula (2) with the polyether having an olefin group of general formula (3), some or all of the X groups are further replaced with other hydrolyzable groups. Alternatively, it can be converted to a hydroxyl group. For example, when the X group is a halogen group or a hydride group, it is preferable to use it after converting it to an alkoxy group, an acyloxy group, an aminooxy group, an alkenyloxy group, a hydroxyl group, or the like. In general formula (3), R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, preferably a hydrogen atom or a hydrocarbon group, and particularly preferably a hydrogen atom. R〓 is the same or different carbon number 1~
Of the 20 divalent organic groups, hydrocarbon groups and hydrocarbon groups containing ether bonds, ester bonds, urethane bonds, and carbonate bonds are preferred, and methylene groups are particularly preferred. A specific method for producing polyether having an olefin group represented by general formula (3) is the method already disclosed by the present inventors in JP-A-54-6097, etc., or the method using ethylene oxide, propylene oxide, etc. It can be produced by a method in which an olefin group-containing epoxy compound such as allyl glycidyl ether is added during polymerization of an epoxy compound and copolymerized to introduce an olefin group into the side chain. The main chain of the polyether (B) used in the present invention essentially has the general formula -R〓-O- (R〓 is a divalent organic group, most of which is a carbonized group having 1 to 4 carbon atoms. It is most effective when it is a hydrogen group). R〓
Specifically, −CH ₂ −, −CH ₂ CH ₂ −,

【formula】 【formula】

[Formula] -CH ₂ CH ₂ CH ₂ CH ₂ -, etc. Polyethers may consist of only one type of repeating unit, or polyethers consisting of two or more types of repeating units are also effectively used, especially

[Formula] is preferred. Polyethers having a molecular weight of 500 to 15,000 can be effectively used, but preferably polyethers have a molecular weight of 3,000 to 12,000. Such polyethers are disclosed in JP-A-53-129247 and JP-A-54-129247.
It can be manufactured by the method disclosed in Japanese Patent No. 6097 and the like. The mixing ratio of polyether (B) to 100 parts by weight of acrylic polymer (A) can be arbitrarily selected within the range of 1 to 70 parts by weight, preferably 3 to 50 parts by weight.
If component (B) is less than 1 part by weight, it is difficult to obtain a mixing effect, and if it exceeds 70 parts by weight, it is difficult to obtain adhesive strength. The method of mixing component (A) and component (B) is, if component (A) is obtained by solution polymerization, simply mixing the solution and component (B) and dissolving it uniformly. You can get it just by doing it. On the other hand, if component (A) is aqueous such as an emulsion, a method may be adopted in which component (B) is once emulsionized and then mixed. In curing the acrylic adhesive composition of the present invention, a curing catalyst (silanol condensation catalyst) (C) is used, and examples of such curing catalysts include dibutyltin laurate and Carboxylic acid salts such as dibutyltin maleate and dibutyltin phthalate, chelate compounds such as dibutyltin bisacetylatonate and dibutyltin bisethyl acetoacetate, organotin compounds such as reaction products of dibutyltin oxide and ester compounds, butylamine, Laurylamine, monoethalamine, triethylenetetramine, piperidine, guanidine, 2-ethyl-4-methylimidazole, 1,3-diazabicyclo(5,4,6)
Amine compounds such as undecene-7-(DBU) or their carboxylates,

【formula】

【formula】

Examples include organic acidic phosphoric acid compounds such as [Formula], mixtures of organic acidic phosphoric acid compounds and amine compounds, and the like. Among these, acidic compounds and/or basic compounds are preferable from the viewpoint of workability, and in particular, it is preferable to use a mixture of an organic acidic phosphoric acid compound having a P-OT bond and an amine compound when adding a catalyst. It is preferable because it causes less viscosity increase, has a long pot life, and cures quickly. The amount of curing catalyst (C) used is 0.1 to 10 parts by weight per 100 parts by weight of component (A). If the number of parts used is less than or exceeds the above range, curing workability or cured physical properties will be adversely affected. The composition of the present invention can be used in combination with various compounds to adjust the adhesive properties. Examples of such compounds include various tackifying resins, various crosslinking agents for acrylic adhesives, various silane compounds, antioxidants, ultraviolet absorbers, plasticizers, fillers, pigments, surfactants, etc. It is not limited to these. There are no particular limitations on the tackifier resin, and examples include resins with polar groups such as rosin ester resins, phenol resins, xylene resins, xylene phenol resins, and terpene phenol resins, aromatic systems with relatively low polarity, and aliphatic-aromatic resins. Various petroleum resins such as group copolymer-based or alicyclic-based resins, or conventional tackifying resins such as coumaron resins, low molecular weight styrene resins, and terpene resins can be used. Specific examples of these resins include Petrozine 80 (manufactured by Mitsui Petrochemical Co., Ltd.), Neopolymer S
(manufactured by Nippon Petrochemicals Co., Ltd.), Tatsuku Ace A100 (manufactured by Mitsui Petrochemicals Co., Ltd.), Quinton 1500 (manufactured by Nippon Zeon Co., Ltd.)
,
FTR6100 (manufactured by Mitsui Petrochemicals Co., Ltd.), Vicolastic
A75 (manufactured by Hercules Co., Ltd.), Croman G-90 (manufactured by Nippon Steel Chemical Co., Ltd.), YS Polyster T-115, YS Polyster S-145 (manufactured by Yasushi Oil Co., Ltd.), Stevelite Ester 7, Fuoral 85 , Fuoral 105 (manufactured by Hercules Co., Ltd.), Neopolymer E-100 (manufactured by Nippon Petrochemical Co., Ltd.) and other resins having polar groups, but are not limited to these. There are no particular limitations on the crosslinking agent for acrylic adhesives, but examples include polyisocyanate compounds,
Examples include polyglycidyl compounds, melamine resins, urea resins, polyvalent metal salts, etherified amino resins, acids, acid anhydrides, amines, and polymers containing carboxyl groups. Examples of various silane compounds include various silane coupling agents, such as alkyl alkoxysilanes such as methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, and n-propyltrimethoxysilane; dimethyldiisopropenoxysilane, methyltrimethoxysilane, etc. Alkylisopropenoxysilanes such as isopropenoxysilane, γ-glycidoxypropylmethyldiisopropenoxysilane; γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane , vinyldimethylmethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, etc. Silanes;
Silicone varnishes; polysiloxanes; silanol compounds such as trimethylsilanol, triethylsilanol, triphenylsilanol, diphenylmethylsilanol, phenyldimethylsilanol, and diphenylsilanediol; hexamethyldisilazane; ethylsilicate, and the like. The acrylic pressure-sensitive adhesive composition of the present invention can be used as a pressure-sensitive adhesive, for example, in tapes, sheets, labels, foils, and the like. i.e. by applying it to substrates such as, for example, films made of synthetic resins or modified natural products, paper, fabrics of all kinds, metal foils, metallized plastic foils, asbestos or glass fiber cloth, and drying and curing by heating. , adhesive sheets, tapes, labels, etc. Hereinafter, the acrylic pressure-sensitive adhesive composition of the present invention will be explained in more detail with reference to Examples. Synthesis Example 1 800 g of polypropylene oxide with an average molecular weight of 8000 having allyl ether groups at the ends at a ratio of 98% of all the ends (manufactured by introducing allyl ether groups at the ends using polypropylene glycol as a starting material) was placed in a stirrer. Place it in a pressure-resistant reaction vessel with a lid, add 20g of methyldimethoxysilane,
Subsequently, a catalyst solution of chloroplatinic acid (H ₂ PtCl ₆
A solution of 8.9 g of 6H ₂ O dissolved in 18 ml of isopropyl alcohol and 160 ml of tetrahydrofuran) 0.34
ml, and the mixture was reacted at 80°C for 6 hours. In order to determine the reaction rate, we quantified the amount of unreacted silane groups using gas chromatography and infrared analysis, and found that 84% of the terminals had reacted. A polyether terminated with groups was obtained. Synthesis Example 2 The monomer mixture shown in the table below, 150 g of toluene, and benzoyl peroxide as an initiator were placed in a reaction vessel and reacted at 80°C for 8 hours until the solid content concentration was approximately 40.
% and a viscosity of 20 to 130 poise (25 DEG C.), four types of acrylic polymers A, B, C and D were obtained. These properties are shown in the table below.

[Table] * Example of numerical synthesis of acid value per solid content 3

A curing catalyst was prepared by mixing 3.0 g of [Formula] and 1.9 g of (CH ₃ ) ₂ N(CH ₂ ) ₁₁ CH ₃ in 4.9 g of toluene. (Test method) (i) Tack: Measured using the J.Dow rolling ball method at measurement temperatures of 23°C and 5°C. (ii) Adhesive strength: Attach the adhesive tape to a stainless steel plate or polyethylene plate, leave it for 60 minutes, and then heat it to 300mm/300mm at 23°C.
Perform 180° peeling at a peeling speed of 10 minutes and measure the force required for peeling. (iii) Holding power: Adhesive tape was pasted on a stainless steel plate in an area of 25 mm x 25 mm, and the displacement distance was measured after 60 minutes at a static load of 1 kg and a temperature of 80°C. Examples 1 to 5 Synthesis Example 1 was applied to acrylic polymer A obtained in Synthesis Example 2.
A predetermined amount of the resulting polyether was added and mixed uniformly. A predetermined amount of the curing catalyst prepared in Synthesis Example 3 was added to this and mixed uniformly to prepare an adhesive composition solution. The resulting solution was applied to a 25μ thick polyester film so that the glue thickness after drying was 20μ.
It was dried and cured at 120°C for 3 minutes. Table 1 shows the results of measuring the adhesive properties of the adhesive sheet thus obtained. As is clear from Table 1, the compositions of the present invention exhibited excellent adhesive properties.

[Table] Comparative Example 1 The same operation as in Example 1 was carried out using only acrylic polymer A obtained in Synthesis Example 2 without using polyether or curing catalyst. The results are shown in Table 1. Examples 6 to 12 A predetermined amount of the polyether prepared in Synthesis Example 1 was added to the acrylic polymers B to D obtained in Synthesis Example 2 and mixed uniformly. To this, a predetermined amount of the curing catalyst prepared in Synthesis Example 3 and Fural 105 as a tackifying resin were added.
The solution shown in Table 2 was added in the amount shown in Table 2 and mixed uniformly to prepare an adhesive composition solution. The resulting solution was applied to a 25μ thick polystyrene film so that the glue thickness after drying was approximately 35μ.
After drying at 80°C for 2 minutes, it was aged at 40°C for 7 days, and the adhesive properties were measured. The results are shown in Table 2. In Examples 11 and 12, Coronate L (polyisocyanate compound) was added as a crosslinking agent for the acrylic polymer. Comparative Examples 2 to 6 Adhesive composition solutions having the compositions shown in Table 2 were prepared without using the polyether of Synthesis Example 1 and the curing catalyst of Synthesis Example 3. The obtained solution was made into a 25μ thick film in the same manner as in Examples 6 to 12.
The thickness of the glue after drying on the polyester film is approximately 35μ.
After drying at 80°C for 2 minutes and aging at 40°C for 7 days, the adhesion properties were measured. The results are shown in Table 2.

【table】

[Table] Conventional acrylic adhesive composition is usually Comparative Example 5
and 6, crosslinked acrylic polymer is used. Therefore, when Comparative Example 5 and Example 8 were compared, and when Comparative Example 6 and Example 10 were compared, it was found that the composition of the present invention had improved polyolefin adhesion and tack, especially tack at low temperatures. It can be seen that this is superior to conventional acrylic pressure-sensitive adhesive compositions.
Of course, it is also clear that the adhesive compositions of the present invention (Examples 6, 8, and 10) are superior to adhesive compositions in which the acrylic polymer is not crosslinked (Comparative Examples 2, 3, and 4). be. [Effects of the Invention] The acrylic pressure-sensitive adhesive composition of the present invention has excellent polyolefin adhesion and tack, especially tack at low temperatures.

Claims (1)

[Scope of Claims] 1 (A) 100 parts by weight of an acrylic polymer obtained by polymerizing a monomer mainly consisting of an alkyl ester of acrylic acid whose alkyl group has 2 to 14 carbon atoms (B) 1 molecule An acrylic pressure-sensitive adhesive composition containing 1 to 70 parts by weight of a polyether having at least one reactive silicon group, and (C) 0.1 to 10 parts by weight of a curing catalyst. 2. The acrylic polymer (A) is a monomer copolymerizable with 50 to 99.5% by weight of an alkyl ester of acrylic acid whose alkyl group has 2 to 14 carbon atoms and 0.5 to 50% by weight of the acrylic acid ester. The acrylic pressure-sensitive adhesive composition according to claim 1, which is a copolymer obtained by polymerizing a mixture with. 3 Claim 1 in which the reactive silicon group of polyether (B) is a silicon atom bonded to a hydrolyzable group
The acrylic adhesive composition described in . 4. The acrylic pressure-sensitive adhesive composition according to claim 1, wherein the polyether (B) is substantially an alkylene oxide polymer having 1 to 4 carbon atoms. 5. The acrylic pressure-sensitive adhesive composition according to claim 1 or 4, wherein the polyether (B) has a molecular weight of 500 to 15,000. 6 The curing catalyst (C) is an acidic compound and/or
The acrylic adhesive composition according to claim 1, which is a basic compound. 7. The acrylic pressure-sensitive adhesive composition according to claim 1, wherein the curing catalyst (C) is a mixture of an organic acidic phosphoric acid compound having a P-OH bond and an amine compound. 8 Acrylic polymer (A) has an acid value (KOHmg/g)
10. The acrylic pressure-sensitive adhesive composition according to claim 1, which is a polymer of more than 10%.