JPH0633019A - Adhesive composition - Google Patents

Abstract

PURPOSE:To provide a two-pack adhesive composition having excellent storage stability. CONSTITUTION:This two-pack adhesive composition is composed of a liquid A containing an acrylic monomer and/or methacrylic monomer, an organic peroxide and a polymerization inhibitor and a liquid B containing the monomer and a cure accelerator, and further, a condensed phosphoric acid salt as a stabilizer for the liquid A is added thereto. An adhesive composition having quick curability, high adhesive strength and excellent long-term storage stability can be produced by this process.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a modified acrylic adhesive,
In particular, the present invention relates to a two-component adhesive composition having both fast curing property and good storage stability.

[0002]

2. Description of the Related Art In recent years, two-pack type modified acrylic adhesives which are widely used as structural adhesives are basically acrylic monomers and / or methacrylic monomers (hereinafter collectively referred to as (meth) acrylic monomers). Is a non-mixing type composition composed of two liquids, a liquid A containing a polymerization initiator such as an organic peroxide and a liquid B containing a curing accelerator. The solution A is applied to one side and the solution B is applied to the other side and pressure-bonded to adhere them. This kind of adhesive quickly cures at room temperature to obtain excellent adhesive strength,
There are advantages such as good workability, good economic efficiency, and wide range of use without the need for prior mixing work. On the other hand, there is a problem with storage stability during storage, and especially A containing organic peroxide
With the liquid, thickening and gelation over time are obstacles to use.

For the purpose of improving the storage stability of the conventional liquid A,
Polymerization inhibitors such as hydroquinone are used, but these inevitably affect the polymerization reaction of the (meth) acrylic monomer, resulting in a delay in the curing speed at the time of adhesion and a decrease in adhesive strength, It acts to reduce the original characteristics of the two-component adhesive. When the amount of the polymerization inhibitor added is small, the effect on the curing speed and the adhesive strength is relatively small, but on the other hand, sufficient storage stability cannot be obtained. If it is too large, the curing speed will be reduced and the adhesiveness will be poor. Therefore, the conventional stabilization method using a polymerization inhibitor has drawbacks in that storage stability, rapid hardening and adhesive strength cannot be sufficiently satisfied.

Two-component adhesives have low viscosity and tend to drop from the surface to be adhered or to cause unnecessary diffusion or infiltration, and a thixotropic agent is often added for the purpose of preventing this. In many formulations, thixotropic agents often significantly reduce storage stability, further reducing shelf life. In addition to the polymerization inhibitor, a method of using an ammonium salt of an organic acid or an inorganic acid as a stabilizer (JP-A-58-27765), a method of adding a metal salt of an organic acid (JP-A-58-23866), etc. Although proposed, the storage stability and the curing speed are still not sufficiently satisfactory. Therefore, in the modified acrylic adhesive,
What can be stably stored without gelation for a long period of time while maintaining fast curing property and adhesive property is required.

[0005]

SUMMARY OF THE INVENTION The present invention provides a two-part adhesive which has the inherent fast curing property of a modified acrylic adhesive and improved stability which allows it to be stored for a long period of time without gelation. This is an issue.

[0006]

Means for Solving the Problems As a result of research, the inventors have found that when a polymerization inhibitor is used in combination with a kind of condensed phosphate, the storage stability of solution A is reduced even if the amount of the inhibitor added is small. Without the need to obtain a two-component adhesive composition which is fast-curing and has good adhesiveness, and a composition containing a thixotropic agent contains a combination of a condensed phosphate, an aminopolycarboxylic acid, and an epoxy resin. The present invention has been reached by discovering that it is extremely effective. That is,
The present invention relates to (meth) acrylic monomers, organic peroxides,
And a solution B containing a polymerization inhibitor and a solution B containing a (meth) acrylic monomer and a curing accelerator, and as a stabilizer of the solution A, an alkali metal salt, an ammonium salt, or an alkaline earth alkaline earth salt of condensed phosphoric acid. A two-pack type adhesive characterized by containing a condensed phosphate selected from metal salts, and a condensed liquid containing the above-mentioned condensed phosphate, an aminopolycarboxylic acid and an epoxy resin as a stabilizer for solution A. The two-component adhesive composition is used as the gist.

In the present invention, the (meth) acrylic monomer constituting the liquids A and B is methyl (meth)
Acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, t-butyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, alkyl (meth) acrylate such as lauryl (meth) acrylate, cyclohexyl (Meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2
-Acetoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 2-hydroxyethyl (meth)
Mono (meth) acrylates such as acrylate, diethylene glycol mono (meth) acrylate, 2- (dimethylamino) ethyl (meth) acrylate, 2- (meth) acryloyloxyethyl acid succinate, mono (meth) acryloxyethyl phosphate, etc. Ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, bisphenol A di (meth) acrylate, 1,1,1-tri Polyhydric (meth) acrylates such as methylolpropane tri (meth) acrylate, epoxy poly (meth) acrylates obtained by reaction of (meth) acrylic acid with epoxy compounds,
Representative examples include urethane poly (meth) acrylate obtained by the reaction of hydroxyalkyl (meth) acrylate with an isocyanate compound, polyester (meth) acrylate obtained by the reaction of (meth) acrylic acid with glycols and polybasic acids. However, the present invention is not limited to these. These monomers can be used alone or in combination of two or more.

Examples of the organic peroxide in the liquid A include hydroperoxides such as t-butyl hydroperoxide, di-t-butyl hydroperoxide, cumene hydroperoxide and diisopropylbenzene hydroperoxide, and di-t. -Butyl hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dialkyl peroxides such as dicumyl peroxide, lauroyl peroxide, benzoyl peroxide, acetyl peroxide, etc. Compounds represented by ketone peroxides such as diacyl peroxides, methyl ethyl ketone peroxide, and cyclohexanone peroxide can be used.

The addition amount of these organic peroxides is (meth)
The amount is 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the acrylic monomer. If the amount is less than 0.1 parts by weight, curing will be insufficient and the adhesive strength will be low, and if it exceeds 20 parts by weight, the storage stability will be poor. As the polymerization inhibitor, known inhibitors such as hydroquinone, cumene hydroquinone, methylhydroquinone, p-benzoquinone, t-butylhydroquinone, 2-butyl-4-hydroxyanisole, dinitrotoluene, picric acid and phenothiazine can be used. it can.

The amount of the polymerization inhibitor added is 0.001 to 3 parts by weight, preferably 0.01 to 1 part by weight, based on 100 parts by weight of the (meth) acrylic monomer. If the amount is less than 0.001 part by weight, sufficient storage stability cannot be obtained even when the condensed phosphate is used together, and if it exceeds 3 parts by weight, the synergistic effect of the condensed phosphate is diminished and the curing rate is delayed, It will not be possible to obtain good adhesive strength. Condensed phosphates, which have synergistic stabilizing effects when used in combination with a polymerization inhibitor, are chain- or cyclic-chain condensed phosphates having a degree of condensation of 2 or more, such as alkali metal salts, ammonium salts, alkaline earth metal salts and alkalis. -Alkaline earth metal salts, specifically pyrophosphoric acid, tripolyphosphoric acid,
Examples include straight chain polyphosphoric acids such as tetrapolyphosphoric acid and cyclic metaphosphoric acids such as sodium salt, potassium salt, lithium salt, ammonium, calcium salt, magnesium salt, sodium / calcium salt, sodium / magnesium salt, etc., which have a high degree of condensation. Things are more effective.

These condensed phosphates do not necessarily have to be dissolved in the adhesive composition and may be dispersed in the form of fine powder. The amount of the condensed phosphate added is 0.01 to 20 parts by weight based on 100 parts by weight of the (meth) acrylic monomer,
It is preferably 0.1 to 10 parts by weight. If the amount is less than 0.01 parts by weight, the synergistic effect with the polymerization inhibitor is unlikely to appear.
Addition by weight or more causes adverse effects such as a decrease in adhesive strength.

In the present invention, a polymer or elastomer soluble in the (meth) acrylic monomer can be added for the purpose of adjusting the viscosity and improving the performance of the adhesive such as the adhesive strength. As typical examples, polymethylmethacrylate homopolymers or copolymers, polyethylacrylate homopolymers or copolymers, acrylonitrile-butadiene-styrene copolymers, styrene-based polymers such as acrylonitrile-styrene copolymers, polyvinyl chloride,
Polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl-based polymers such as polyvinylidene chloride, acrylonitrile-butadiene-isoprene copolymer, acrylonitrile-based polymers such as acrylonitrile-butadiene rubber, styrene-butadiene-styrene block copolymer Examples thereof include rubbers and block copolymers such as styrene-isoprene-styrene block copolymer rubbers, and acrylonitrile-butadiene-styrene copolymers, styrene-butadiene rubbers, and acrylonitrile-butadiene rubbers are particularly preferable.

The polymer or elastomer is added in an amount of 5 to 150 parts by weight based on 100 parts by weight of the (meth) acrylic monomer. Furthermore, in the modified acrylic adhesive, it is desirable to add a thixotropic agent for the purpose of improving the use characteristics, but the present invention imparts excellent storage stability even to a formulation containing the thixotropic agent. can do. As the thixotropic agent, known ones such as fumed silica and montmorillonite fine particles can be used. In the present invention, in addition to these, a surface hardening accelerator such as wax, a filler, a plasticizer, an antiaging agent, a pigment and the like can be added if necessary.

The liquid B of the present invention comprises the above-mentioned (meth) acrylic monomer and a curing accelerator. As the curing accelerator, ethylenethiourea, benzoylthiourea, acetylthiourea, L-ascorbic acid, thiosalicylic acid, vanadylacetyl are used. Acetonate, manganese naphthenate, cobalt naphthenate, copper naphthenate, ferrocene, N, N-
One or more known compounds capable of decomposing an organic peroxide by a redox reaction such as dimethylaniline, diethylenetriamine and o-sulfobenzimide can be used. Liquid B is relatively stable because it contains no organic peroxide, but for the purpose of suppressing the action of the curing accelerator,
It is preferable to add a small amount of a polymerization inhibitor.

Tables 1 and 2 show the relationship between the amount of the polymerization inhibitor added and the stability, curability and adhesiveness of a typical adhesive composition comprising a methacrylic monomer, an organic peroxide and a polymerization inhibitor. The results of measuring the effect of addition of condensed phosphate on these are shown. From the data in Tables 1 and 2, it is clear that the combined use of the condensed phosphate with the polymerization inhibitor has a synergistic stabilizing effect, and the amount of the inhibitor used can be reduced, so that the modified acrylic It is understood that good storage stability can be achieved over a long period of time without impairing the fast curing property inherent in the system adhesive.

On the other hand, when a thixotropic agent such as Aerosil is blended in order to improve the use characteristics, the stabilizing effect of the condensed phosphate is retarded, and a decrease in storage stability is recognized as compared with that containing no thixotropic agent. However, as a result of further research on this point, it was found that the effect of the thixotropic agent can be completely removed by adding the aminopolycarboxylic acid compound and the epoxy compound together with the condensed phosphate. Also in this case, it was confirmed that the fast curing property and the adhesive property were hardly affected and the storage stability was maintained well. Examples of aminopolycarboxylic acid compounds that can be used in the present invention include ethylenediaminetetraacetic acid, N- (2-hydroxyethyl) ethylenediamine N, N ′, N′-triacetic acid, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, and triethylenetetraminehexaacetic acid. It is suitable, and 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, is added to 100 parts by weight of the (meth) acrylic monomer.

The epoxy compound used in the present invention includes polyglycidyl ether, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, trimethylolpropane triglycidyl ether,
1,6 hexanediol diglycidyl ether, propylene glycol diglycidyl ether, phenol novolac polyglycidyl ether, tetraphenyl glycidyl ether ethane, n-butyl glycidyl ether,
Polyglycidyl ether such as styrene oxide, diglycidyl phthalate, dimethylglycidyl phthalate,
Polyglycidyl esters such as diglycidyl hexahydrophthalate and diglycidyl tetrahydrophthalate,
Typical examples are alicyclic epoxy compounds such as 3,4-epoxy-6-methylcyclohexylmethylcarboxylate and glycidyl (meth) acrylate, and the addition amount is 0 based on 100 parts by weight of the (meth) acrylic monomer. 0.01 to 20 parts by weight, preferably 1 to 10 parts by weight. If it is less than 0.01 parts by weight, a sufficient stabilizing effect cannot be obtained, and if it exceeds 20 parts by weight, the adhesive strength is lowered, which is not preferable.

[0018]

EXAMPLES The present invention will be described in more detail below with reference to examples. All numerical values representing the composition represent parts by weight. Examples 1 to 5 Storage stability and curing time of an adhesive composition A liquid prepared by adding the hydroquinone and the condensed phosphate stabilizer shown in Table 1 to the composition 100 of the following formulation a) and The adhesive strength was measured and the results are shown in Table 1. Comparative Examples 1 to 4 Only the hydroquinone described in Table 1 was added to the composition of Formula A), and stability, curability and adhesiveness were measured in the same manner as in Examples 1 to 5, and the results are shown in Table 1. .

[0019]

[Table 1]

Prescription a) 2-hydroxymethyl methacrylate ¹⁾ 70 oligoester acrylate ²⁾ 6.5 tetramethylol methane tetraacrylate ³⁾ 12.5 ABS resin ⁴⁾ 11 cumene hydroperoxide ⁵⁾ 5 1) Kyoeisha Oil and Fat Chemical Industry Light ester HO 2 manufactured by Toa Gosei Kagaku Kogyo Co., Ltd. Aronix M-640
03) Shin-Nakamura Chemical Co., Ltd. NK Ester A-TMMT 4) Asahi Kasei Co., Ltd. Stylak 301 5) Kayaku Akzo Co., Ltd.

Test Method (Storage Stability) 90 g of each of the compositions of Examples or Comparative Examples was placed in a 100 ml brown polyethylene container and the container was tightly capped.
It was left to stand in a dryer at 0 ° C. and the time until a gel-like product was formed was measured. (Curability) 0.5 ml each of solution A (composition of the example or comparative example) and solution B having the following composition was weighed on a glass plate in a thermostatic chamber at 25 ° C., and slowly mixed and stirred with a glass rod,
The time from the start of stirring until the adhesive did not flow was measured.

Liquid B 2-hydroxymethyl methacrylate 70 oligoester acrylate 6.5 tetramethylolmethane tetraacrylate 12.5 ferrocene 0.5 o-sulfobenzimide 1.0 hydroquinone 0.05 ABS resin 11 (adhesive) sandpaper Solution A (composition of Example or Comparative Example) and solution B (above) were applied to a cold rolled steel sheet having a thickness of 1.6 mm which was degreased with trichlene after polishing with JIS, and JIS K68 was used.
According to 50, the tensile shear strength was measured. The curing condition is 2
The pulling speed was 10 mm / min at 5 ° C. for 24 hours.

Examples 6 to 12 Adhesive compositions prepared by adding 0.5 of hydroquinone and 0.5 of the condensed phosphate stabilizer shown in Table 2 to the composition 100 of formulation a) and the above examples and Similarly, stability, curability and adhesiveness were measured. The results are shown in Table 2. Comparative Examples 5 to 7 Hydroquinone 0.5 and ammonium triphosphate or sodium triphosphate 0.5 were added to the composition 100 of formulation a).
Was added, and the stability, curability and adhesiveness of the resulting adhesive composition were measured, and the results are shown in Table 2.

[0024]

[Table 2]

Examples 13 to 19 In the same manner as described above, the stability, curability, and adhesiveness of the adhesive compositions obtained by adding the stabilizers shown in Table 3 to the composition 100 of formulation B) were obtained. It was measured. The results are shown in Table 3. Comparative Examples 7 to 8 Stability, curability and adhesiveness of the compositions obtained by adding 0.5 of hydroquinone and the stabilizers shown in Table 3 to the composition 100 of formulation B) were measured in the same manner as above. . The results are shown in Table 3.

[0026]

[Table 3]

Prescription b) 2-hydroxymethyl methacrylate 35 tetraethylene glycol dimethacrylate ⁶⁾ 35 oligoester acrylate 6.5 tetramethylol methane tetraacrylate 12.5 thixotropic agent ⁷⁾ 4.5 cumene hydroperoxide 5.0 hydroquinone 0.5 ABS resin 11 6) Light ester 4EG manufactured by Kyoeisha Oil & Fat Chemical Co., Ltd. 7) Aerosil R-812 manufactured by Degussa

[0028]

EFFECTS OF THE INVENTION The present invention is characterized in that a polymerization inhibitor and a condensed phosphate are used in combination as a gelation preventing stabilizer for a modified acrylic two-pack type adhesive. The amount of polymerization inhibitor added can be reduced by this, and as a result, the adverse effects on the curing reaction and adhesive strength due to the polymerization inhibitor are suppressed, and gelation is prevented for a long period of time, so storage stability and fast curing are achieved. And an excellent two-component adhesive composition having excellent adhesive strength can be obtained.

Claims (2)

[Claims] 1. An A containing an acrylic monomer and / or a methacrylic monomer, an organic peroxide, and a polymerization inhibitor.
A two-component adhesive composition comprising a liquid and a liquid B containing an acrylic monomer and / or a methacrylic monomer and a curing accelerator, wherein an alkali metal salt, ammonium salt, or alkaline earth salt of condensed phosphoric acid is used as a stabilizer for the liquid A. A two-part adhesive composition comprising a metal salt or a polyphosphate selected from alkali / alkaline earth metal salts. 2. A polyphosphate selected from alkali metal salts, ammonium salts, alkaline earth metal salts and alkali / alkaline earth metal salts of polyphosphoric acid as a stabilizer of the liquid A.
The two-component adhesive composition according to claim 1, which contains an aminopolycarboxylic acid and an epoxy compound.