JPH0463911B2 - - Google Patents

Description

[Detailed description of the invention]

OBJECTS OF THE INVENTION (INDUSTRIAL APPLICATION FIELD) This invention relates to adhesives, in particular to adhesives used in the field of pressure sensitive adhesives. (Prior Art) Coumarone indene resins, terpene resins, hydrogenated rosins, and the like are conventionally known as pressure-sensitive adhesives, particularly pressure-sensitive adhesives. (Problems to be Solved by the Invention) However, among the known adhesives, there are few that exhibit excellent adhesiveness to polymeric materials. In particular, non-polar polymeric materials such as polypropylene, polyethylene, ethylene-propylene-nonconjugated diene terpolymers (EPDM), ethylene-
When it comes to adhesives for pressure-sensitive adhesives used to bond propylene copolymer (EPM) to metals, paints coated on metals, synthetic resins, or rubber, there are very limited types. Even when an adhesive is applied to a non-polar polymer material, the adhesive tends to peel off from the material. This is due to the fact that the non-polar polymer material does not have large polar functional groups in the molecule like acrylonitrile-butadiene-styrene terpolymer (ABS) and acrylonitrile-butadiene rubber (NBR). It is considered that Therefore, the present inventor conducted an intensive search for an adhesive that can be the main component of a pressure-sensitive adhesive that exhibits excellent adhesive strength, especially for non-polar polymeric materials, and
The invention has been completed. Therefore, an object of the present invention is to provide a pressure-sensitive adhesive having excellent adhesiveness. Structure of the Invention (Means for Solving the Problems) The present invention comprises as a main component at least one vinyl compound A selected from acrylic esters or methacrylic esters having 18 or less carbon atoms; 100 parts by weight of a copolymer having active hydrogen derived from at least one other vinyl compound B selected from acrylate, hydroxyalkyl methacrylate, dicarboxylic acid, and dicarboxylic acid anhydride as a copolymerization component; Polymer isocyanate oligomer 0.02 ~
The above-mentioned problem is attempted to be solved by creating an adhesive consisting of a reactive mixture with 16 parts by weight of 16 parts by weight. Furthermore, the configuration of the present invention will be explained in detail. The number of carbon atoms of the vinyl compound A according to the present invention is 18
The following acrylic esters refer to aliphatic alkyl acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, isodecyl acrylate, lauryl acrylate, and stearyl acrylate. Similarly, methacrylic acid esters of vinyl compound A having 18 or less carbon atoms include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, lauryl methacrylate, stearyl methacrylate, etc. Refers to aliphatic alkyl methacrylate. Other vinyl compounds B to be copolymerized with these vinyl compounds A include acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-
hydroxyalkyl acrylates and hydroxyalkyl methacrylates such as hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, and 2-hydroxypropyl methacrylate; dicarboxylic acids and dicarboxylic acid anhydrides such as maleic acid, fumaric acid, citraconic acid, citraconic anhydride, and itaconic acid; Examples include itaconic anhydride. These vinyl compounds B are the vinyl compounds A
copolymerized with and formed as a side chain or terminal chain
H in COOH or OH becomes the active hydrogen referred to in the present invention. When producing a copolymer having active hydrogen using the above-mentioned compounds A and B as starting materials, the above-mentioned two types of vinyl compounds A and B are each converted into 1. A species or two or more species may be copolymerized. However, in order to make a copolymer containing active hydrogen in a predetermined quantitative range, it is necessary to determine the copolymerization ratio between vinyl compound A, which is the main component, and other vinyl compound B, which is copolymerized with the same compound. Good. Polyisocyanates constituting the dimeric to tetrameric isocyanate oligomers to be mixed with this copolymer include tolylene diisocyanate, 4,4
-diphenylmethane diisocyanate, 4,4-
Dicyclohexylmethane diisocyanate, 1,
Diisocyanates such as 5-naphthalene diisocyanate, xylylene diisocyanate, hexahydroxylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, lysine triisocyanate, 1,6,11-
There are triisocyanates such as undecamethylene triisocyanate. The copolymer and the dimeric to tetrameric isocyanate oligomer are mixed in a state in which both are mixed in a solvent. As the solvent, a solvent is selected that can dissolve the above-mentioned polymers and dimeric to tetrameric isocyanate oligomers and is inert to them. Examples of such solvents include saturated hydrocarbons such as n-hexane and cyclohexane, unsaturated hydrocarbons such as benzene, toluene, and xylene, ketones such as methyl ethyl ketone, methyl isopropyl ketone, and methyl isobutyl ketone, ethyl acetate, isopropyl acetate, and isobutyl acetate. There are several fatty acid esters, and these solvents can be used alone or in a mixed state. When using the adhesive according to the present invention for pressure-sensitive adhesive applications, a copolymer mixed in a solvent and a dimeric to tetrameric isocyanate oligomer also mixed in a solvent are mixed. Apply the adhesive to the surface of the object to be adhered. The application method may be any method known per se, such as a dipping method, a spraying method, or a brushing method. When mixing the copolymer solution and the di- to tetramer isocyanate oligomer solution, the amount of the di- to tetramer isocyanate oligomer is 0.02 to 16.00, preferably 0.03 to 16.00, per 100 parts by weight of the copolymer.
Mix in a proportion of 5.00 parts by weight. When the dimeric to tetrameric isocyanate oligomer is less than 0.02 parts by weight, the adhesive strength of the adhesive is weak, and when it exceeds 16.00 parts by weight, the effect is saturated and the adhesive strength of the adhesive does not increase much. The adhesive of the present invention can be applied to any object as long as it exhibits tackiness or adhesion, but it is particularly applicable to non-polar polymeric materials and metals, or to metals coated with acrylic paints. The target surface is the surface that is Such objects to be adhered include the moldings and bodies of automobiles. Note that the pressure-sensitive adhesive of the present invention also exhibits excellent adhesion to objects made of polyvinyl chloride. In order to make the effect of the adhesive according to the present invention more effective, the object to be adhered may be treated with a primer, but it is better to activate the surface by corona discharge or plasma treatment. In particular, the adhesion effect is significantly enhanced when nonpolar polymeric materials are treated with corona discharge or plasma. Corona discharge is carried out using a knife-shaped electrode with a length of 300 mm, with a distance of 1 mm between the electrode and the object to be adhered, and with a power of 1 KW. The adhesive according to the present invention can be obtained by evaporating the solvent from the reactive mixture solution before use, but usually the reactive mixture solution is applied to an object to be adhered and then the solvent is evaporated as is. Then, a pressure sensitive operation is performed on the objects to be adhered to form an adhesive layer between the two objects to be adhered,
If left at room temperature or under slight heating, the reaction between active hydrogen in the adhesive and isocyanate will proceed. The reaction of isocyanate with active hydrogen is relatively fast, and if the copolymer and dimeric to tetrameric isocyanate oligomer are mixed in the presence of a solvent and then the solvent is evaporated, the reaction tends to proceed gradually. However, it has reactivity. In this sense, the adhesive according to the present invention can be said to be a reactive mixture. (Function) By using a dimer to tetramer isocyanate oligomer, this isocyanate oligomer has an isocyanate group (-N=C=O) and a substituted isocyanate group.

[Formula] is present, and these isocyanate groups react with the active hydrogen contained in the acrylic acid copolymer or methacrylic acid copolymer to cause crosslinking in the copolymer, and the bonded material When the isocyanate oligomer has active hydrogen, the dimeric to tetrameric isocyanate oligomer forms a chemical bond with the hydrogen, or forms a physical bond such as Van der Waals force.
(Example) Example 1 n-butyl acrylate and maleic anhydride
Copolymerized at a weight ratio of 100:5. The acrylic acid copolymer was mixed with a mixed solvent containing toluene: cyclohexane: ethyl acetate in a ratio (weight ratio) of 1:1:1 to obtain a solid content concentration of 37% by weight.
A copolymer mixture was prepared. On the other hand, 50 g of tolylene diisocyanate dimer
1155 g of toluene was added to prepare an isocyanate oligomer solution having a concentration of about 4% by weight. and,
A reactive mixture (sample 1) was obtained by adding 2 parts by weight of the isocyanate oligomer solution to 100 parts by weight of the acrylic acid polymer mixture. This reactive mixture was applied to two test pieces made of EPDM, left for 2 minutes under hot air to evaporate the solvent, and then the test pieces were pressed together with a pressure of 5 kg/cm ² for 10 minutes. Then, two test pieces were glued together. The test piece is left at room temperature for 3 days, and the isocyanate oligomer reacts with the active hydrogen of the acrylic acid polymer and crosslinks (actually, the substituted isocyanate group in the dimeric tolylene diisocyanate)

[Formula] also undergoes crosslinking in the same way as the isocyanate group. ) and then measured the adhesion strength of the test piece. The adhesive strength was determined by measuring the shearing force in the adhesive layer interposed between the overlapping ends of the two test pieces. The shear force of the adhesive layer in this example was 750 g/cm ² . The test piece was made of the following composition, vulcanized at 160°C for 30 minutes, and processed into a sheet with a thickness of 2 mm. That is, it contains ethylidene norbornene as the third component, has an iodine value of 15, and a Mooney viscosity of 65.
100 parts by weight of EPDM (100℃), 67.5 parts by weight of carbon black, 35 parts by weight of mineral oil, 5 parts by weight of zinc white, 1 part by weight of stearic acid, 2 parts by weight of vulcanization accelerator, and sulfur. The composition contained 1.5 parts by weight of each. Example 2 Acrylic acid polymer mixture prepared in Example 1
To 100 parts by weight, 3 parts by weight of the isocyanate oligomer solution prepared in Example 1 was added, an increase from that in Example 1, to obtain a reactive mixture solution (Sample 2). Then, when the shear force of the adhesive was measured using a test piece according to Example 1, the value was 880g/
It was warm in ^cm2 . Example 3 In the same manner as in Example 1, 100 parts by weight of the acrylic acid polymer mixture was mixed with 5 parts by weight of the isocyanate oligomer solution to prepare a reactive mixture solution (sample 3).
I got it. The mixture solution was applied to a test piece in the same manner as in Example 1 to form an adhesive layer, and the shear force was measured, and the value was 930 g/cm ² Example 4 Torirange in Example 1 A reactive mixture solution (sample 4) was obtained using the same method and conditions as in Example 1 except that a trimer of the isocyanate was used instead of a dimer of the isocyanate, and the shear force of the adhesive layer was When measured in the same manner as in Example 1, it is
It was 1000g/ ^cm2 . Example 5 A reactive mixture solution (sample 5) was obtained in the same manner and under the same conditions as in Example 1, except that a trimer of hexamethylene diisocyanate was used in place of the dimer of tolylene diisocyanate in Example 1. Then, when the shear force of the adhesive layer was measured in the same manner as in Example 1,
The value was 870g/ ^cm2 . Example 6 An experiment similar to Example 1 was conducted using fumaric acid instead of maleic anhydride in Example 1 to obtain a reactive mixture solution (Sample 6). The shear force of the adhesive layer from this reactive mixture is
It was 810g/ ^cm2 . The acid value of the acrylic acid polymer obtained in this example was 30 to 32. Example 7 Instead of maleic anhydride in Example 1, 2
A reactive mixture solution (Sample 7) was obtained by carrying out an experiment similar to Example 1 using -hydroxyethyl methacrylate. The shear force of the adhesive layer from this reactive mixture was measured to be 830 g/cm ² .
In addition, the acrylic acid polymer obtained in this example
The OH value was 54-58. Example 8 Instead of maleic anhydride in Example 1, 2
An experiment similar to Example 1 was conducted using -hydroxypropyl methyl methacrylate to obtain a reactive mixture solution (Sample 8). This solution was used to form an adhesive layer between two test pieces in the same manner as in Example 1, and the shearing force of the layer was measured, and the shearing force was 780 g/cm ² . Note that the OH of the acrylic acid polymer obtained in this example
The value was 26-30. Example 9 In addition to increasing the amount of isocyanate oligomer solution added in Example 1 to 142.3 parts by weight,
A reactive mixture solution (sample 9) was obtained using the same method and conditions as in Example 1. If we measure the shear force of the adhesive layer from that reactive mixture, it is 1150g/
It was warm in ^cm2 . Comparative Example 1 Copolymer mixture solution in Example 1 (sample
11) was applied to a test piece without mixing an isocyanate oligomer solution to form an adhesive layer, and an attempt was made to measure the shear force, but the shear force was so small that it could not be measured. Comparative Example 2 A reactive mixture solution (sample 12) obtained by experimenting in the same manner and under the same conditions as in Example 1 except that the amount of isocyanate added to the oligomer solution in Example 1 was increased to 213.5 parts by weight. Obtained. Then, an attempt was made to apply the reactive mixture solution to the test piece, but the gelation rate was so high that the reactive mixture solution could not be applied to the test piece. Example 10 Reactive mixture solutions obtained in Examples 1 to 9 and Comparative Examples 1 and 2 (Samples 1 to 9, Samples 11 and 12)
Adhesion experiments were conducted using the pressure-sensitive adhesive used to bond the molding 1 having the cross-sectional shape shown in the figure to the body of an automobile. A polyethylene foam layer 4 was bonded to the back side of the molding 1 used at this time via an adhesive layer 3 whose main component was an epoxy resin with a solid content of 10% by weight. Then, each of the samples 1 to 9 and 12 is applied onto the foam layer 4, and the adhesive layer 5 is formed by volatilizing the solvent from each sample in an atmosphere at 100°C for 25 minutes. was. In addition, instead of the body of an automobile, a steel plate 2 made of the same material as the body was selected, and a steel plate 2 coated with an acrylic resin coating was used. The molding 1 to which the adhesive layer 5 was attached was pressed onto the steel plate 2 to bond them together, and then left as it was at room temperature for 20 days. Then, the isocyanate oligomers in Samples 1 to 9 gradually react with the active hydrogen attached to the side chain or end of the acrylic acid or methacrylic acid polymer chain, resulting in crosslinking, and are also attracted to the polyethylene molecules to form Mole 1. The polyethylene foam layer 4 and the steel plate 2 were joined to each other. It should be noted that Sample 11 had no adhesive strength even after conducting an adhesion experiment. Then, the adhesive layer 5 was
The shear force was measured and the results listed in the table were obtained.

【table】

[Table] Effects of the Invention As described above, the adhesive of the present invention exhibits excellent adhesion to metals, nonpolar polymer materials, and the like.

[Brief explanation of drawings]

The figure is a sectional view showing a molding bonded to the body of an automobile using the adhesive according to the present invention. Molding...1, Steel plate...2, Adhesive layer...5.

Claims (1)

[Scope of Claims] 1 The main component is at least one vinyl compound A selected from acrylic esters or methacrylic esters having 18 or less carbon atoms,
100 parts by weight of a copolymer having active hydrogen derived from at least one other vinyl compound B selected from hydroxyalkyl acrylate, hydroxyalkyl methacrylate, dicarboxylic acid and dicarboxylic anhydride as a copolymerization component; ~Tetrameric isocyanate oligomer 0.02~
An adhesive characterized in that it consists of a reactive mixture with 16 parts by weight. 2. The adhesive according to claim 1, wherein the active hydrogen is H of COOH or H of OH.