JPH035432B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to an improved adhesive composition that can cure rapidly even in contact with air and has excellent durability. The demand for adhesives that harden at room temperature and in a short time is increasing year by year, as labor-saving, resource-saving, and energy-saving are being called for. started to attract attention. Conventionally, as adhesives using acrylic monomers, anaerobic adhesives using polyacrylic monomers and anaerobic monomers are known. Anaerobic adhesives are made by adding a polymerization initiator such as peroxide to monomers that are susceptible to polymerization inhibition by oxygen in the air. It is cured by blocking air or by coming into contact with an adhesive surface coated with a curing accelerator. In either case, the part of the adhesive that comes into contact with the air does not harden, so it is necessary to perform tedious work such as wiping the part of the adhesive with a solvent. Adhesion of adhesive or dust may cause problems in terms of product appearance or environmental hygiene. Also, depending on the adherend material, if it is easily exposed to air, for example if the adhesive gap is wide, it may not harden or the adhesive strength may significantly decrease when adhering to porous materials such as paper, cloth, or cross sections of wood. Since it has drawbacks such as poor adhesion, it has the disadvantage that the range of adherends is limited. Another known adhesive is a combination of an acrylic monomer that is not strongly anaerobic and an elastomer to obtain the necessary impact strength. For example, in the case of US Pat. No. 2,981,650, a solution of polychloroprene and a liquid monomer containing an unsaturated double bond, to which the reducing component of a redox catalyst is added, is cured by mixing it with the oxidizing component of a redox catalyst immediately before use. In the case of U.S. Patent No. 3,333,025, a system in which a reducing component of a redox catalyst is added to a syrup obtained by partially polymerizing a liquid monomer containing unsaturated bonds in the presence of polychloroprene, etc. is cured by adding peroxide immediately before use. . However, the above compositions have the disadvantage that it takes a long time for the adhesive to harden, making it difficult to speed up the bonding work line and to adapt it to automation. It is known to add methacrylic acid to polychloroprene-vinyl monomer systems for the purpose of increasing the curing rate, as seen in U.S. Pat. No. 3,725,504; Therefore, impact strength is low. Furthermore, according to the invention described in U.S. Pat. No. 3,832,274, instead of polychloroprene, an adhesive composition consisting of an elastomer containing butadiene, a methacrylic acid ester monomer, methacrylic acid and a reducing component of a redox catalyst is brought into contact with a peroxide. Adhesives that are cured by drying are known. On the other hand, as a method of adding an oxidizing component of a redox catalyst to a methacrylic monomer solution that is not strongly anaerobic and curing the solution by bringing it into contact with a reducing component of the redox catalyst immediately before use, there is an invention described in JP-A-49-132119. According to this, a composition consisting of chlorosulfonated polyethylene or a mixture of sulfonyl chloride and chlorinated polyethylene, and a polymerization catalyst such as a vinyl monomer and an organic peroxide is cured by bringing it into contact with a reducing component of a redox catalyst immediately before use. Fast-curing adhesives are known. However, as in the inventions of US Pat. No. 3,725,504 and US Pat. No. 3,832,274, methacrylic acid is
% to 20% has the drawback of causing metal corrosion. Methacrylic acid tends to cause corrosion when it adheres to metal surfaces or due to the generated steam, and it particularly corrodes copper materials used in electrical equipment, which may lead to breakage of copper wires and the like, resulting in serious defects. Japanese Patent Application Publication 1973-
97051 suggests that the presence of unsaturated organic acids results in rapid degradation when exposed to harsh environmental conditions after bonding. Furthermore, the composition disclosed in JP-A-49-132119 is
Even when exposed to high temperature and high humidity or low humidity
If exposed to a high temperature atmosphere of 120°C or higher, the cured product will deteriorate significantly, and if a metal that is prone to rust, such as iron, is used as the adherend, the adhered surface will rust, resulting in a decrease in strength, etc. Due to these drawbacks, it is difficult to use it in products that are exposed to harsh environmental conditions, such as outdoors and high temperatures, after bonding. The present invention improves the various drawbacks of the known techniques mentioned above, and achieves high impact strength, high peel strength, low metal corrosion, low strength loss even when exposed to harsh environmental conditions, and strength that can be handled. It provides an adhesive that takes only a few minutes to several tens of minutes to achieve. In accordance with the present invention, (A) (i) a copolymer elastomer of butadiene and acrylonitrile, (ii) a copolymer elastomer of butadiene and acrylonitrile and up to 5% of a functional monomer, and (iii) butadiene is essential. per 100 parts by weight of the composition, an elastomer or graft copolymer selected from the group consisting of a graft copolymer consisting of the same and one or more monomers selected from the group consisting of acrylonitrile, styrene, and methacrylic acid ester. ~
30 parts by weight; (B) 2-hydroxyethyl methacrylate and/or
or 10 to 60 parts by weight of 2-hydroxypropyl methacrylate per 100 parts by weight of the total amount of compounds containing unsaturated double bonds used in the composition; (C) methacrylic acid having an alkyl group having 1 to 4 carbon atoms; 20 to 80 parts by weight of the alkyl ester per 100 parts by weight of the total amount of compounds containing unsaturated double bonds used in the composition; (D) General formula (In the formula, R represents a hydrogen atom or a methyl group,
n is an integer and is 0 or 1. ) 10 to 70 parts by weight of the monomer represented by (E) per 100 parts by weight of the total amount of the compound containing an unsaturated double bond used in the composition; and (E) a hydroperoxide used in the composition. Total amount of compounds containing unsaturated double bonds100
0.1 to 10 parts by weight per part by weight; Preferably, paraffin wax is added, and in the presence of the reducing component of the polymerization initiator, the parts including the parts in contact with air are rapidly cured at room temperature. Provided is an acrylic adhesive composition that is highly durable and has excellent environmental resistance. According to the present invention, by using 2-hydroxyethyl methacrylate (2HEMA) or 2-hydroxypropyl methacrylate (2HPMA), which are conventionally known as anaerobic monomers, methacrylic acid alkyl ester (2HEMA), which is a monomer that does not exhibit strong anaerobic properties, is used. By using a predetermined amount of a (meth)acrylic monomer having an alkyl group having 1 to 4 carbon atoms and a dicyclopentene ring represented by formula (I), it can be cured quickly, including the parts that are in contact with air. An adhesive composition is obtained. In addition, it simultaneously solves the drawbacks of anaerobic adhesives and non-anaerobic adhesives known in the prior art, and also provides an adhesive composed of an elastomer and a methacrylic acid ester or other unsaturated vinyl compound according to the prior art. An adhesive with high impact strength and peel strength that cannot be obtained with other methods can be obtained. Further, the adhesive composition of the present invention exhibits extremely little decrease in strength even when exposed to harsh environmental conditions after adhesion, and has excellent environmental resistance, particularly moisture resistance and water resistance. The A component used in the adhesive composition of the present invention includes a copolymer elastomer of butadiene and acrylonitrile (AN), a copolymer elastomer composed of butadiene, AN, and 5% or less of a functional monomer, and a graft copolymer. An elastomer or polymer selected from the group consisting of: Examples of functional monomers include methacrylic acid, acrylic acid, maleic anhydride, etc.
Examples include itaconic acid. butadiene homopolymer and copolymer elastomer of butadiene and styrene (ST),
Chlorosulfonated polyethylene and the like are not preferred in the composition of the compound containing an unsaturated double bond of the present invention because of their solubility or viscosity stability after dissolution. Furthermore, when polychloroprene is used as the elastomer, if it coexists with the unsaturated double bond-containing compound used in the present invention and the hydroperoxide, the storage stability of the composition will be extremely poor, and it will not last for several days at room temperature. This is not preferable because it hardens. In addition, the graft copolymers used include:
AN, ST, containing butadiene as an essential component
A graft polymer consisting of one or more monomers of methacrylic acid ester, such as butadiene homopolymer, or butadiene and AN, ST,
Copolymer with one or more methacrylic esters This is a copolymer obtained by grafting an elastomer with one or more monomers of AN, ST, and methacrylic ester. Typical graft copolymers used in the present invention include ABC grafts made from butadiene, AN, and ST, and MBS or MBAS grafts made from butadiene, AN, ST, and methacrylic acid esters. Any of the ABS, MBS or MBAS grafts improves the impact and peel strength, which is the object of the present invention, and also has a thickening effect to provide a preferable handling viscosity as an adhesive, and when a graft is used, the elastomer Unlike when using adhesives, it exhibits strong structural viscosity (thixotropy), which reduces stringiness and dripping of adhesive during bonding work and improves work efficiency. The elastomer and graft copolymer described above do not need to be completely dissolved in the acrylic monomer used, but they do need to be sufficiently dispersed microscopically. The above elastomer and graft copolymer are used in an amount of 5 to 30 parts by weight per 100 parts by weight of the adhesive composition. If the amount is less than 5 parts by weight, the viscosity becomes low, which is undesirable for adhesive application work, and high impact or peel strength cannot be obtained. If it exceeds 30 parts by weight, the viscosity of the resulting adhesive composition will be extremely high, which is unfavorable for adhesive application work. As the hydroxyl group-containing methacrylic acid ester of component B, 2HEMA and/or 2HPMA are used. The amount of 2HEMA and/or 2HPMA is in the range of 10 to 60 parts by weight based on 100 parts by weight of the total amount of compounds containing unsaturated double bonds used in the composition, and if it is less than 10 parts by weight, the curing rate will be reduced. It is too small to be practical, and if it exceeds 60 parts by weight, it is undesirable because it lowers the environmental resistance, which is one of the objectives of the present invention, such as moisture resistance and water resistance. The methacrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms used as component C is in the range of 20 to 80 parts by weight based on 100 parts by weight of the total amount of the compound containing an unsaturated double bond contained in the composition. be. Adding more than 80 parts by weight means B, D
The lower limit of any of the components falls outside the scope of the present invention. If it is less than 20 parts by weight, the curing of the portion in contact with air will be insufficient, which is not preferable. In order to more completely cure the parts that are in contact with the air, it is preferable to add paraffin wax.The paraffin wax used is
A mixture of hydrocarbons represented by CnH ₂ n+ ₂ (n is an integer of 15 to 50) with a wide carbon number distribution of 20 or more is preferred. The amount used is 0.01 to 2% by weight based on the entire composition, and if it is less than 0.01%, curing will be slow in the parts in contact with air.
If it exceeds 2%, the adhesive strength may decrease. D The acrylic acid or methacrylic ester having a dicyclopentene ring represented by structural formula I is used in an amount of 10 to 70 parts by weight based on 100 parts by weight of the total amount of compounds containing unsaturated double bonds contained in the composition. . Specific examples of the compound of structural formula I include dicyclopentenyl acrylate, dicyclopentenyl methacrylate, dicyclopentenyloxyethyl acrylate, and dicyclopentenyloxyethyl methacrylate. If it is less than 10 parts by weight, the moisture resistance and water resistance of the environmental resistance, which is the objective of the present invention, will be reduced, which is undesirable. If it is more than 70 parts by weight, the lower limit of either component B) or C) will be This is outside the scope of the present invention and is not preferred. In addition to components B), C) and D) used in the present invention, 5% or less, preferably 3%
% or less of methacrylic acid can be added.
If it is more than 5%, it is unfavorable from a sanitary point of view, such as metal corrosion, reduced moisture resistance, and even rash when it comes into contact with the skin. When the amount of B) hydroxyl group-containing methacrylic ester used is small, it is preferable to add methacrylic acid. Examples of hydroperoxides used as component E include monohydroperoxides such as tertiary butyl, pinene, paramenthane, diisopropylbenzene, and kyumene, and dihydroperoxide diisopropylbenzene. Although it is possible to use an organic peroxide different from hydroperoxide, hydroperoxide is superior due to its high impact strength after curing and less curing unevenness, so hydroperoxide is an essential ingredient. used as The amount used is the total amount of the compound having unsaturated double bonds in the adhesive composition.
0.1 to 10 parts by weight per 100 parts by weight, and 0.1
If it is less than 10 parts by weight, curing will be insufficient or the curing rate will be extremely slow, making it impractical, and if it exceeds 10 parts by weight, storage stability will decrease. In order to improve the storage stability of the composition, it is common practice to add a small amount of a polymerization inhibitor. These inhibitors include hydroquinone, catechol, methylhydroquinone, hydroquinonequinone monomethyl ether, P-benzoquinone, phenothiazine, butylcatechol, 2-butyl-4-hydroxyanisole, 2,6-ditertiallybutyl-P-cresol, etc. It is possible to use commonly known polymerization inhibitors.
The appropriate amount of these polymerization inhibitors to be used is 0.001 to 3%, preferably 0.01 to 1%, based on the total amount of the compound containing an unsaturated double bond. If the concentration is low, the storage stability will be poor, and if the concentration is too high, the adhesive strength will be reduced. In the case of the present invention, in order to accelerate the decomposition of hydroperoxide and facilitate the generation of radicals, a reducing agent of a redox catalyst is used as a curing accelerator and brought into contact with the above-mentioned adhesive composition containing peroxide immediately before bonding. Let it harden. In the case of the present invention, the use of the curing accelerator is, for example, as follows. (b) The accelerator can be used as is or dissolved in various solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, toluene, methanol, ethanol, dioctyl phthalate, dibutyl phthalate, or a plasticizer, and applied as a primer before use. Use as a coating. (b) One of the compositions, in which a curing accelerator has been previously dissolved or dispersed in a liquid monomer having an unsaturated double bond, is brought into contact with the composition containing a peroxide and cured. In the above method (b), one of the compositions containing a curing accelerator is a liquid monomer and an elastomer having an unsaturated double bond, as described in A) above,
Each component of B), C), and D can be contained.
In this case, it is sufficient that the total amount of each component used in the composition containing the organic peroxide and the composition containing the reducing agent is within the range specified above. Therefore, in this case, the oxidizing composition The selection of the components in the and reducing composition is extremely free, and it is possible for the two to contain different viscosities, composition ratios, and components, making it possible to create adhesives that are more suited to the type of adherend. , has a wide range of applications. In addition, in the case of the two-component base type in the method (b) above, since it does not contain a solvent, there are no disadvantages in the process such as drying after applying the accelerator, preventing environmental pollution caused by solvents and reducing wasteful use of solvents. It can be omitted and is preferable. The types of reducing agents used include naphthenic acid, octylic acid, pivalic acid, neodecanoic acid, stearic acid, heavy metal salts of organic acids, and diethyl-P.
Examples include, but are not limited to, aromatic amines such as -toluidine, diisopropanol-P-toluidine, and thioamide compounds such as thiourea, acetylthiourea, tetramethylthiourea, ethylenethiourea, and mercaptobenzimidazole. The present invention will be explained below with reference to Examples, and all parts and percentages in the specification are expressed on a weight basis. Example 1 In this example, 2-HEMA, methyl methacrylate (MMA), and dicyclopentenyloxyethyl methacrylate (abbreviated as DICPEA) were selected from monomers B), C), and D), and the first A composition containing the hydroperoxide shown in the table (Sample Nos. A-1 to A-6) and a composition containing the redox catalyst reducing agent shown in Table 2 (B-1 to B-6) were created, The curing rate when the oxidizing composition and the reducing composition of the redox catalyst were brought into contact and cured was measured by the method described below. The adhesive composition is manufactured by adding a predetermined amount of the above monomer and butadiene-acrylonitrile copolymer elastomer (NBR) to a glass flask, stirring at room temperature for 40 hours to create a uniform translucent viscous liquid, and then A catalyst, additives, etc. were added, and the mixture was further stirred for 1 hour.

【table】

【table】

[Table] Size 100 x 25 x 16 as a method of measuring curing speed
Adhesion area of two sandblasted mild steel plates of mm 25
After applying the oxidizing composition and the reducing composition to a 125 mm x 125 mm area and bonding them together, the steel plate was pulled by hand in the shear direction, and the time until the steel plate stopped moving was measured, which was defined as the adhesion time. The atmospheric conditions were 23°C x 50% RH. *Paraffin wax: has a peak at carbon number 26 and has a carbon number distribution width of 36 (maximum) - 16 (minimum) = 20.

【table】

Table 3-1 shows that as the amount of 2HEMA increases, the fixation time becomes shorter and the curing rate increases. Further, if the amount of 2HEMA is 5 parts by weight, the curing speed is extremely low and the object of the present invention cannot be achieved. The reason why the hardening of the protruding portion in contact with air is poor in the A-6/B-6 combination is thought to be due to the amount of MMA being outside the range of the present invention, as shown by the experiments in Example 2 and below. Comparative Example 1 The paraffin wax in the composition of Example-1 was replaced with one having a peak at carbon number 26 and a carbon number distribution width of 31 (maximum) - 21 (minimum) = 10, and the other components were Same composition (sample numbers are A'-
1 to A'-6 and B'-1 to B'-6),
The same test as in Example-1 was conducted. 3rd result
It is shown in the table.

[Table] From the results in the table above, it can be seen that even if the width of the carbon number distribution of paraffin wax is narrowed, there is no change in the fixation time.
It can be seen that the curability of the portion in contact with air deteriorates depending on the monomer composition. Example 2 Compositions shown in Tables 4 and 5 were prepared in the same manner as in Example 1, and their curing rates were measured.
The measurement method was in accordance with Example-1. The results are shown in Table 6.

【table】

【table】

[Table] From the results in the above table, it can be seen that when the amount of MMA is less than the lower limit of the range of the present invention, curing of the portion in contact with air becomes insufficient. Example 3 Using the samples used in Example-1 and Example-2, the tensile shear strength after curing at room temperature for one day (tensile speed 10 mm/min) using sandblasted steel plates and steel pieces as adherends. , and after curing for 1 day, 60℃ x 90%
Table 7 shows the results of measuring the tensile shear strength in accordance with ASTM after being exposed to a high temperature and high humidity atmosphere of RH for 15 days. Also, the IZOD impact strength and T-type peel strength were measured in accordance with ASTM. The results are shown in Table 8.

【table】

[Table] The results in Table 7 show that when the amount of 2HEMA exceeds the upper limit of the range of the present invention, or when the amount of DICPEA falls below the range of the present invention, the moisture resistance decreases rapidly. There is. The results in Table 8 show that all samples exhibit high impact and peel strengths, which are the objectives of the present invention. Example 4 Next, the curing speed when a redox catalyst reducing agent is used as an undercoat is shown. As a reducing agent composition for the redox catalyst, a solution (P-1) was prepared by dissolving 12 parts of tetramethylthiourea in 100 parts of ethanol, and this was applied onto a sandblasted steel plate and dried. The adhesion time was measured in combination with an adhesive composition containing hydroperoxide.

[Table] remains sticky.
As described above, the same results as in Example 1 were obtained when the redox reducing agent was used as the undercoat. Example 5 Sample No. A-3 of Example-1, 2- of B-3
A composition was prepared in which the HEMA part was replaced with 2HPMA, and the other components were exactly the same as in Example-1. This adhesive composition has a fixing time of 18 minutes, a tensile shear strength after 1 day of 196 Kg/cm ² , an IZOD impact strength of 19.6 Kgcm/cm ² , a T-peel strength of 10.5 Kg/25 mm,
Tensile shear strength after exposure at 60℃ x 90%RH x 15 days:
It showed 190Kg/cm ² (strength retention rate: 97.0%), and the hardening of the protruding part was also good. Example 6 The measurement results of various physical properties when ethyl methacrylate (EMA) and n-butyl methacrylate (BMA) were used as methacrylic acid alkyl esters having an alkyl group having 1 to 4 carbon atoms were
Shown in Table 10. The composition is sample No.A-4, B-4.
The MMA part of was replaced with EMA and BMA, respectively, and the other formulations were the same as A-4 and B-4.

[Table] The results are as described above, and the hardening of the protruding portion was sufficient, achieving the purpose of the present invention. In addition to methacrylic acid esters, compounds in which the alkyl group has more than 4 carbon atoms, such as 2-ethylhexyl, lauryl, tridel, and stearyl methacrylates, have a significantly slow curing rate;
Furthermore, the impact and peel strengths were low, and the object of the present invention could not be achieved. Example 6 The elastomer or polymer shown in Table 11 was used instead of NBR, which is the elastomer component of Sample Nos. A-4 and B-4 of Example-1, and the other components were A-4.
Table 11 shows the measurement results of various physical properties when the properties were the same as those of -4 and B-4.

【table】

Claims (1)

[Scope of Claims] 1 (A) (i) A copolymer elastomer of butadiene and acrylonitrile, (ii) a copolymer elastomer of butadiene and acrylonitrile and 5% or less of a functional monomer, and (iii) butadiene. Per 100 parts by weight of the composition, an elastomer or graft copolymer selected from the group consisting of an essential component and a graft copolymer consisting of the same and one or more monomers selected from the group consisting of acrylonitrile, styrene, and methacrylic acid ester. 5 to 30 parts by weight; (B) 2-hydroxyethyl methacrylate and/or
or 10 to 60 parts by weight of 2-hydroxypropyl methacrylate per 100 parts by weight of the total amount of compounds containing unsaturated double bonds used in the composition; (C) methacrylic acid having an alkyl group having 1 to 4 carbon atoms; 20 to 80 parts by weight of alkyl ester per 100 parts by weight of the total amount of compounds containing unsaturated double bonds used in the composition: (D) General formula (In the formula, R represents a hydrogen atom or a methyl group,
n is an integer and is 0 or 1) 10 to 70 parts by weight per 100 parts by weight of the total amount of the compound containing an unsaturated double bond used in the composition; - the total amount of the compound containing unsaturated double bonds used in the composition 100%
An adhesive containing 0.1 to 10 parts by weight as an essential component, which can be rapidly cured at room temperature in the presence of the reducing component of the polymerization initiator, including the part in contact with air, and has excellent environmental resistance. agent composition.