JPWO2000077110A1 - Anaerobic curing composition - Google Patents

Abstract

(57) [Abstract] An anaerobic curing composition comprising (a) a polymerizable monomer having a functional group represented by the general formula _H2C =C(R)- (R is hydrogen or a methyl group) at the molecular terminal, (b) an organic peroxide, (c) o-benzoix sulfimide, and (d) a salt selected from sodium, potassium, and calcium salts of a weakly acidic substance, has high storage stability, yet has a fast curing rate and high adhesive strength. In particular, it can rapidly bond adherends that are difficult to cure with conventional anaerobic curing compositions, such as inert metals and plastics.

Description

Detailed Description of the Invention Technical Field The present invention relates to an anaerobic composition that remains stable in a liquid state without gelling for a long period of time while in contact with air or oxygen, and that hardens rapidly when isolated from air or oxygen.

BACKGROUND ART Anaerobic compositions contain (meth)acrylic acid ester monomers as their main component and have the property of remaining stable in a liquid state without gelling for a long period of time while in contact with air or oxygen, and of rapidly curing when the air or oxygen is blocked or removed.
Taking advantage of these properties, the composition is used for bonding and fastening screws, bolts, etc., fixing mating parts, bonding between flange surfaces, sealing, filling porosity that occurs in cast parts, etc.

In recent years, there has been a demand for the development of anaerobic compositions with extremely fast polymerization rates in order to respond to the increasing speed of production lines for manufacturing industrial products. To achieve this, conventional anaerobic curable compositions have been formulated to contain a polymerization accelerator such as a sulfimide, a mercaptan, or an amine, and a polymerization initiator in the resin component.

However, the use of conventional polymerization accelerators impairs the storage stability of the anaerobic curable composition, and it is extremely difficult to adjust the amount of polymerization initiator added so as not to reduce the storage stability. Therefore, an anaerobic curable composition that is sufficiently adaptable to production lines, etc. has not yet been obtained.

Basically, anaerobic curing compositions are achieved by the coexistence of a component that polymerizes a radically polymerizable monomer and a component that inhibits the polymerization of the radically polymerizable monomer, and by achieving an appropriate balance between these two components. In reality, when selling a product, storage stability must be determined assuming various factors such as exposure to high temperatures in a vehicle during transportation and exposure to direct sunlight during storage, and sufficient storage stability must be achieved even at the expense of curing ability, making it impossible to extremely increase polymerization curing properties.

Furthermore, conventional anaerobic curing compositions do not achieve sufficient curing performance simply by being shielded from air or oxygen. In other words, they rely on metal atoms, metal molecules, metal ions, etc. contained in the adherend to act as a polymerization catalyst, and in order to achieve sufficient adhesive strength, the adherend must be metal. When used on inert metals such as plastics or plated surfaces, there are problems such as poor curing or insufficient adhesive strength even after curing.

The present invention overcomes the above-mentioned conventional problems, and an object of the present invention is to provide an anaerobic curing composition having improved adhesiveness without impairing storage stability. Another object of the present invention is to provide an anaerobic curing composition that can be effectively used for bonding to inert metals and plastics that have been difficult to bond with conventional anaerobic curing compositions.

Disclosure of the Invention The above-mentioned objects of the present invention are achieved by the following anaerobic curable composition.

(1) An anaerobic curing composition comprising: (a) a polymerizable monomer having a functional group represented by the general formula _H2C =C(R)- (R is hydrogen or a methyl group) at the end of the molecule; (b) an organic peroxide; (c) o-benzoic sulfimide; and (d) a salt selected from sodium salts, potassium salts, and calcium salts of a weakly acidic substance.

(2) The anaerobic curable composition according to (1) above, wherein the component (a) comprises at least a hydroxyl group-containing (meth)acrylate.

(3) The anaerobic curing composition according to (2) above, wherein the anaerobic curing composition is obtained by mixing the component (d) and a hydroxyl group-containing (meth)acrylate to form a compatible solution, and then mixing the resulting solution with other components.

(4) The anaerobic curable composition according to (1) above, wherein the weak acidic substance is selected from carbonic acid, boric acid, phosphoric acid, nitrous acid, hypochlorous acid, formic acid, acetic acid, propionic acid, caproic acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, citric acid, gluconic acid, succinic acid, tartaric acid, lactic acid, fumaric acid, malic acid, lactic acid, and o-benzoixulfimide.

BEST MODE FOR CARRYING OUT THE INVENTION The polymerizable monomer (a) having a functional group represented by _H2C =C(R)- (R is hydrogen or a methyl group) used in the present invention includes compounds having a vinyl group at the molecular end, such as acrylic acid and methacrylic acid, or derivatives thereof. More specific examples of this polymerizable monomer include monoesters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, phenyl (meth)acrylate, and benzyl (meth)acrylate; hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; ethylene glycol diacrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylene glycol di(meth)acrylate, and the like. polyvalent esters such as tyrolpropane tri(meth)acrylate and pentaerythritol tetraacrylate; (meth)acrylonitrile, (meth)acrylamide, N-substituted (meth)acrylamide; vinyl esters such as vinyl acrylate, vinyl acetate, vinyl propionate and vinyl succinate; vinyl ethers, styrene, halogenated styrenes, divinylbenzene, vinylnaphthalene, N-vinylpyrrolidone, diallyl phthalate, diallyl maleate, triallyl isocyanate and triallyl phosphate;
These polymerizable monomers can be used alone or in combination of two or more.

The polymerizable monomer may contain a polymerizable oligomer for the purpose of adjusting the viscosity of the anaerobic curable composition or the properties of the cured product. Examples of the polymerizable oligomer include a maleate group, a fumarate group, an allyl group, a (meth)
Curable resin having acrylate groups, isocyanate-modified acrylic oligomer,
Examples include epoxy-modified acrylic oligomers, polyester acrylic oligomers, polyether acrylic oligomers, etc., and these oligomers can be used alone or as a mixture of two or more kinds.

The polymerizable monomer may also contain polymerizable unsaturated polymers such as unsaturated polyester resins and unsaturated acrylic resins for the same purpose as the above polymerizable oligomers.

The organic peroxide (b) used in the present invention is one that has conventionally been used in anaerobic curable compositions, and is not particularly limited. Examples thereof include hydroperoxides such as cumene hydroperoxide, t-butyl hydroperoxide, p-menthane hydroperoxide, methyl ethyl ketone peroxide, cyclohexane peroxide, dicumyl peroxide, and diisopropylbenzene hydroperoxide, as well as other organic peroxides such as ketone peroxides, diallyl peroxides, and peroxy esters.

These organic peroxides can be used alone or as a mixture of two or more. The amount of component (b) is 0.1 to 5 parts by weight per 100 parts by weight of the total weight of the polymerizable monomer and polymerizable oligomer. If the amount is less than 0.1 part by weight, the polymerization reaction may not occur sufficiently, and if the amount is more than 5 parts by weight, the stability of the anaerobic curable composition tends to decrease.

The component (c) used in the present invention is o-benzoic sulfimide, a component commonly used in anaerobic compositions. o-benzoic sulfimide is a type of saccharin, and the amount of component (c) added is 0.5 to 5 parts by weight per 100 parts by weight of component (a).

The weakly acidic substance in component (d) used in the present invention has an ionization constant Ka of 1×1
Examples of these include carbonic ^acid , ^boric acid, phosphoric acid, nitrous acid, hypochlorous acid, formic acid, acetic acid, propionic acid, caproic acid, lauric acid,
Examples of the acid include myristic acid, palmitic acid, oleic acid, stearic acid, citric acid, gluconic acid, succinic acid, tartaric acid, lactic acid, fumaric acid, malic acid, lactic acid, and o-benzoic sulfimide.

Although component (d) is a known substance, it has never been added to an anaerobic composition. In particular, it was unexpected that a mixture of o-benzoix sulfimide and component (d) would improve the polymerizability of an anaerobic curable composition. Since component (d) is a water-soluble substance and is poorly compatible with component (a), it is preferable to mix it with a hydroxyl group-containing monomer, particularly a hydroxyl group-containing (meth)acrylate, to achieve sufficient compatibility, and then mix it with component (a).

The amount of component (d) of the present invention is preferably 0.005 to 1 part by weight per 100 parts by weight of component (a). If the amount is less than 0.005 part by weight, the polymerization-accelerating effect may not be obtained, and if the amount is more than 1 part by weight, the component (d) may not be completely dissolved in the composition, causing solids to float in the composition.

In addition to the above components, a small amount of a component that promotes polymerization can be added to the present composition.
Examples of the polymerization accelerator include amine compounds and mercaptan compounds.
The amine compounds include heterocyclic secondary amines such as 1,2,3,4-tetrahydroquinoline and 1,2,3,4-tetrahydroquinaldine, heterocyclic tertiary amines such as quinoline, methylquinoline, quinaldine and quinoxalinephenazine, N,N-dimethyl-
aromatic tertiary amines such as anisidine and N,N-dimethylaniline;
Examples of the mercaptan compounds include linear mercaptans such as n-dodecyl mercaptan, ethyl mercaptan, and butyl mercaptan.

The blending ratio of these polymerization accelerators is 0 to 1 part by weight, preferably 0.1 to 0.5 parts by weight, per 100 parts by weight of the polymerizable monomer or the mixture of the polymerizable monomer and the oligomer and/or polymerizable unsaturated polymer. If the blending ratio of the polymerization accelerator is less than 0.1 part by weight, it will not be effective as a polymerization accelerator, and if the blending ratio is less than 0.
If the amount exceeds 5 parts by weight, the storage stability of the anaerobic composition will be deteriorated.

The present invention can further use various additives. For example, in order to obtain storage stability, radical absorbers such as benzoquinone, hydroquinone, and hydroquinone monomethyl ether, and metal chelating agents such as ethylenediaminetetraacetic acid or its di-sodium salt, oxalic acid, acetylacetone, and o-aminophenol can be added.

Furthermore, in order to adjust the properties of the anaerobic curable resin and the properties of the cured product, thickeners, fillers, plasticizers, colorants, etc. may be used as needed.

The anaerobic composition of the present invention can be obtained by mixing and stirring the components.
However, it is preferable to add component (b) last, since there is a risk that it may be decomposed by stirring. The stirring time may be such that each component becomes uniform.

Specifically, components (a), (c), (d) and other additives are weighed and poured into a container and stirred with a stirrer.
It is preferable to heat to about 0°C. The stirring time is about 10 hours when heated to 50°C. After that, the mixture is cooled to room temperature, and component (b) is weighed and added, followed by stirring for another hour or so. There is no need to apply pressure, reduce pressure, or seal the container during stirring, but it is preferable to seal the container during heating.

In addition, when the component (a) contains a hydroxyl group-containing (meth)acrylate, it is preferable to mix and stir the hydroxyl group-containing (meth)acrylate, which is a part of the component (a), with the component (d) in a separate step. That is, the component (d) is added to the hydroxyl group-containing (meth)acrylate in advance, and the mixture is stirred at 50°C for about 5 hours, and then the mixture is mixed with the (
d) Add as a component.

In the present invention, the curing rate can be improved by adding a weakly acidic sodium, potassium, or calcium salt to o-benzoix sulfimide, which is normally used in anaerobic curing compositions, and surprisingly, it can be cured quickly even when used on adherends other than active metals, and it is also possible to achieve strong adhesion. Furthermore, despite the improved curing rate, storage stability is not reduced, so it can be stored at room temperature.

The present invention will be described in more detail below with reference to the following examples, in which all the amounts blended in the tables are expressed in parts by weight.

In Examples 1 to 7 and Comparative Examples 1 to 5, the compounds listed in Tables 1 and 2 were blended to obtain compositions. However, the urethane acrylate used was GMN-U from Kyoei Yushi Co., Ltd. The solution of OSBI sodium salt in the tables is a solution obtained by mixing 1 g of o-benzoixulfimide sodium salt with 99 g of hydroxyethyl methacrylate and stirring thoroughly. That is,
Addition of 1 part by weight of this solution results in 0.0% of the sodium salt of o-benzoic sulfimide.
This corresponds to the addition of 1 part by weight. OSBI·STQ salt is a 1,2,3,4-tetrahydroquinoline salt of o-benzoic sulfimide.

(Storage Stability Test) 50 g of each composition obtained above was placed in a 100 ml test tube made of low-density polyethylene and stored uncovered for 10 days in an atmosphere at 50° C. Those that gelled in the test tube were marked with ×, and those that did not gel or increase in viscosity were marked with ○.

(Curing property (curing speed) test) Each composition obtained above was applied to a test piece (100 mm x 2
Two pieces of the tape (5 mm thick) were glued together in a cross shape and fixed with a 10 g weight. The time until it stopped moving by hand (set time) was measured. The temperature during measurement was 25
The unit in the table is minutes. Those that did not cure within 360 minutes are indicated by "-".

The results are shown in Tables 1 and 2.

Examples 8 to 25 and Comparative Examples 6 to 18: 400 parts of 2-hydroxyethyl methacrylate was added to 600 parts of BPE100 (manufactured by Shin-Nakamura Chemical Co., Ltd.), a bisphenol A-based epoxy acrylate, and 10 parts of cumene hydroperoxide and 15 parts of o-benzoix sulfimide were added and thoroughly mixed to prepare a base resin. To this base resin, salts listed in Tables 3 to 5 were added. However, for each salt, 1 part of the salt was added to 99 parts of a different 2-hydroxyethyl methacrylate, thoroughly stirred, and a salt solution was obtained. This solution was then added in the amount listed in Tables 3 to 5. In other words, the actual amount of each salt added was 1/100 of the amount listed in Tables 3 to 5.

Using each of the compositions obtained above, the adhesive strength and adhesive rate were measured, and a storage stability test similar to that in Example 1 was carried out.

Adhesion Strength Measurement: An M10, P1.5 x 20 mm JIS Class 2 hexagonal bolt and an M10, P=1.5 hexagonal nut were used, the surface of which was zinc chromate plated. Each of the compositions described above was evenly applied to approximately 10 mm of the tip of the male thread of the bolt, without dripping all around, and the bolt was inserted into the nut. After the bolt was screwed in two threads, two drops of each composition were further applied to the nut threads with the nut side facing up, and the bolt was immediately screwed in until the tip of about three threads protruded. The bolt was not tightened all the way.

The composition was left as it was for 2 hours at 25° C. to harden. The head of the hardened bolt was fixed in a vice, and the nut was rotated with a torque wrench to measure the torque when the nut first began to move.

Adhesion speed test: The same bolts and nuts as above were used, and each composition was applied in the same manner as above, and the bolts and nuts were set. A number of such tests were made. After the bolts and nuts were set, the bolts and nuts were allowed to stand for a predetermined time period of 2
The bolt was left at 5°C, and then rotated with a torque wrench. This test was repeated until the torque reached 0.5 N m when the bolt first began to move. The specified time was extended in 10-minute intervals, and the time when the torque reached the above value was recorded as the curing time. However, samples that did not cure after 360 minutes are marked with a "-".

The results are shown in Tables 3 to 5.

Examples 26-28 and Comparative Examples 19-23: Each composition prepared in the same manner as in Example 8 using the blending amounts shown in Table 6 was applied to the edges of two 100 mm x 25 mm polycarbonate test pieces, which were then bonded together with a 20 mm width alternately. A 100 g weight was placed on the bonded surfaces and the pieces were held in place at 25°C for 2 hours. The edges of the test pieces were pulled using a tensile shear tester, and the adhesive strength (tensile shear strength) was measured. The above tensile shear adhesive strength test was conducted in accordance with JIS K6850 (1994), except that the bond width in the longitudinal direction of the test pieces was changed from 12.5±0.5 mm to 20 mm. The results are shown in Table 6.

Examples 29 to 34 Compositions were prepared by directly adding sodium acetate powder and potassium acetate powder in the amounts shown in Table 7 to the base resin used in Example 8 and thoroughly stirring. These compositions were used to carry out various tests in the same manner as in Example 8. The results are shown in Table 7.

The anaerobic curing composition of the present invention has high storage stability, yet has a fast curing rate and high adhesive strength. In particular, the present composition can bond adherends such as passivated metals, inert metals such as zinc chromate-plated and unichromate-plated metals, and plastics, which have been difficult to bond with conventional anaerobic curing compositions.

────────────────────────────────────────────────── Continued from front page (51) Int.Cl. ⁷ Identification code FI C09K 3/10 C09K 3/10 E (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, MZ, SD, SL, SZ, TZ, UG , ZW), UA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, DZ , EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, K G, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, RU, S D, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (Note) This publication is based on the gazette published internationally by the International Bureau of Patents (WIPO). The effect of the international publication of the Japanese patent application (Japanese utility model registration application) related to this publication arises pursuant to Article 184-10, Paragraph 1 of the Patent Act (Article 48-13, Paragraph 2 of the Utility Model Act), and is unrelated to this publication.

Claims (4)

[Claims] [Claim 1] An anaerobic curing composition comprising: (a) a polymerizable monomer having a functional group represented by the general formula _H2C =C(R)- (R is hydrogen or a methyl group) at the end of the molecule; (b) an organic peroxide; (c) o-benzoic sulfimide; and (d) a salt selected from the group consisting of sodium salts, potassium salts, and calcium salts of a weakly acidic substance. 2. The anaerobic curable composition according to claim 1, wherein said component (a) comprises at least a hydroxyl group-containing (meth)acrylate. [Claim 3] The anaerobic curing composition described in Claim 2, which is obtained by mixing and dissolving component (d) and a hydroxyl group-containing (meth)acrylate, and then mixing the resulting mixture with other components. 4. The anaerobic curable composition according to claim 1, wherein the weak acidic substance is selected from the group consisting of carbonic acid, boric acid, phosphoric acid, nitrous acid, hypochlorous acid, formic acid, acetic acid, propionic acid, caproic acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, citric acid, gluconic acid, succinic acid, tartaric acid, lactic acid, fumaric acid, malic acid, lactic acid, and o-benzoixulfimide.