JPS6334194B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to an acrylic pressure sensitive adhesive. In recent years, acrylic pressure-sensitive adhesives have become widely used in place of conventional natural rubber-based and synthetic rubber-based pressure-sensitive adhesives due to their excellent adhesive properties and durability.
These acrylic pressure-sensitive adhesives are generally adhesive at room temperature obtained by solution polymerizing acrylic monomers such as acrylic esters and methacrylic esters with monomers such as acrylic acid, maleic acid, acrylamide, styrene, and vinyl acetate. It is mainly composed of an acrylic copolymer with However, this type of copolymer generally has poor cohesive strength, and to avoid this, it is usually necessary to use a crosslinking agent such as a phenol resin, melamine compound, isocyanate compound, epoxy compound, or metal ion to make it three-dimensional by heating. Ta. In this case, depending on the type of crosslinking agent, there is a risk of reducing the moisture and heat resistance of the adhesive, and the reduction in adhesive strength due to improved cohesive force and the thermal energy required for three-dimensionalization may not be ignored. Furthermore, problems in terms of quality and productivity remained, such as the difficulty in selecting the type and amount of crosslinking agent to be used in consideration of these factors. On the other hand, an aqueous emulsion type acrylic pressure-sensitive adhesive obtained by emulsion polymerization of the above-mentioned monomers is also known. This adhesive generally has high cohesiveness because the molecular weight of the polymer is very high, but its anti-surface adhesion,
There are problems with water resistance, etc., and due to this drawback, it has hardly been put into practical use as a permanent adhesive. In light of these circumstances, the inventors have developed a method using general solution polymerization or bulk polymerization, which is advantageous in terms of adhesiveness and water resistance, and without using any or very little crosslinking agent as described above. We have continued research for many years to obtain a new acrylic pressure-sensitive adhesive that can provide high cohesive strength and adhesive strength depending on the amount used. In the course of this research, we developed an acrylic copolymer that was sticky at room temperature and had functional groups in its molecules, which were formed using a conventional method, and a specific modified polymer that had functional groups that were reactive with the above functional groups. Very good results can be obtained in terms of both cohesion and adhesion when a copolymer is used and both copolymers are grafted by reaction between functional groups before or after being applied to the substrate. I found that. This invention was made based on the above findings, and its gist is that the main monomer consisting of an ester of acrylic acid or methacrylic acid and an alcohol having 12 or less carbon atoms and a functional group-containing monomer are essential. Acrylic-based copolymers that are sticky at room temperature and have an average molecular weight of 30,000 to 1 million and an average number of functional groups per molecule of 1 to 2,000 as comonomers, as well as acrylonitrile, methacrylonitrile, vinyl acetate, styrene, and A main monomer consisting of one or more monomers selected from the group of acrylic esters, methacrylic esters, and styrene derivatives whose homopolymer glass transition point can be 273 or higher, and a functional group contained in the acrylic main copolymer. The glass transition point is the essential copolymerization monomer with a functional group-containing monomer that has a functional group that is reactive with
273〓 or more, with an average molecular weight of 2,000 to 100,000, and an average number of functional groups per molecule of 0.5 to 0.95, a non-adhesive or low-adhesive modifying copolymer at room temperature is used, and the functional groups of both copolymers are This is an acrylic pressure-sensitive adhesive whose active adhesive ingredient is a graft polymer formed by mutual reaction. As described above, the acrylic pressure-sensitive adhesive of the present invention contains a graft polymer composed of the above-mentioned acrylic copolymer and a specific modifying copolymer as an adhesive active ingredient, and also contains a partially unreacted acrylic main copolymer or an unreacted acrylic main copolymer. Mainly due to the presence of the above-mentioned graft polymer, the cohesive force can be greatly improved without the need for a conventional crosslinking agent or even with a very small amount used. In this case, the adhesive strength of the main acrylic copolymer before grafting was hardly affected. Note that the reason for this is not necessarily clear. However, if the specific modifying copolymer used in this invention is simply blended with a sticky acrylic-based copolymer having functional groups within the molecule, no significant improvement in cohesive force can be observed. Furthermore, the monomers constituting the specific modifying copolymer used in this invention are polymerized together with the monomers for the polymer synthesis during the synthesis of the acrylic main copolymer having adhesive properties. If it is added to the system and polymerized at the same time, either the adhesive force, adhesive force or cohesive force near room temperature will be extremely impaired. From this fact, it is clear that at least the presence of the graft polymer is greatly involved in greatly improving the cohesive force and maintaining adhesive strength and adhesive strength. The main acrylic copolymer used in this invention, which has a functional group in the molecule and is sticky at room temperature, generally has an ester of acrylic acid or methacrylic acid and an alcohol having 12 carbon atoms or less as a main monomer, and has functional groups in it. The average molecular weight obtained by solution polymerization of the group-containing monomer and, if necessary, other copolymerizable monomers, is usually 30,000 to 30,000.
1 million copolymers are used. Examples of the above-mentioned functional group-containing monomers include monoesters of maleic acid, carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, and itaconic acid, and monomers having an acid anhydride group such as maleic anhydride. , hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxyethyl methacrylate, and secondary amino groups (>NH group) such as N-tert-butylaminoethyl acrylate. Epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate are preferred, and among these monomers, the most preferred monomers are monomers having a carboxyl group or an acid anhydride group. Of course, the carboxyl group, acid anhydride group,
It is also possible to use monomers with functional groups other than hydroxyl groups, secondary amino groups, and epoxy groups, and the key is to use monomers that can interact with the modifying copolymer and that are moisture-absorbing or general-purpose monomers. It can be widely applied as long as it has a functional group that does not react alone under suitable environmental conditions. Furthermore, the type of functional group does not need to be limited to one type, and monomers containing two or more types of functional groups may be used as long as they do not react with each other and exhibit mutual reactivity with the functional groups of the modifying copolymer. May be used. The proportion of these various functional group-containing monomers used is generally such that the proportion of the above-mentioned main monomer and other monomers that can be copolymerized is 0.05 to 20% by weight of the total monomers. It is preferable to set the average number of functional groups per molecule of the obtained acrylic main copolymer to be usually 1 to 2000. The more appropriately the number of functional groups is increased, the better results can be obtained in terms of adhesive properties. In this invention, the modifying copolymer used together with the above-mentioned acrylic main copolymer is a copolymer that has a functional group in its molecule that is reactive with the functional group of the main copolymer and is non-adhesive or has low adhesion at room temperature. Therefore, those having a glass transition point of 273〓 or higher, preferably 300〓 or higher are used. If the glass transition point is lower than 273〓, the cohesive force cannot be sufficiently improved. Such a modifying copolymer is generally obtained by solution polymerization or bulk polymerization of a main monomer whose homopolymer glass transition point can be 273 or higher, a functional group-containing monomer, and, if necessary, other copolymerizable monomers. be able to. The average molecular weight of this modifying copolymer is generally from 2,000 to 100,000, and if the molecular weight is too low, it is unfavorable in terms of cohesion. On the other hand, if it is too high, it is not desirable in terms of adhesiveness or stickiness. When using functional group-containing monomers or copolymerizable monomers whose homopolymer glass transition point is lower than 273, the glass transition point of the copolymer should be determined when determining the monomer composition ratio. Care should be taken to ensure that it is at least 273〓. The main monomer whose homopolymer can have a glass transition point of 273〓 or more is a monomer whose homopolymer can have a glass transition point of 300〓 or more selected from the group of sterene, vinyl acetate, acrylonitrile, and methacrylonitrile ( (hereinafter referred to as group A monomers) or monomers whose homopolymer glass transition point selected from the group of acrylic esters, methacrylic esters, or styrene derivatives can be 273〓 or higher (hereinafter referred to as group B monomers). It is particularly suitable. Group B monomers include cyclohexyl acrylate (289〓), methyl acrylate (279〓), butyl methacrylate (293〓), N,
Dimethylaminoethyl methacrylate (289〓),
Examples include hexadecyl methacrylate (288〓), 2-methoxyethyl methacrylate (286〓), and 4-butylstyrene (279〓). In addition, methacrylic acid 2
-Butyl (318〓), 3,3-dimethylbutyl methacrylate (318〓), 3,3-dimethyl-2-butyl methacrylate (381〓), ethyl methacrylate (338〓), glycidyl methacrylate (319〓)
〓), isoporonyl methacrylate (383〓), isobutyl methacrylate (326〓), isopropyl methacrylate (354〓), methyl methacrylate (378〓), phenyl methacrylate (378〓), n-
Propyl methacrylate (308〓), isopolonyl acrylate (367〓), 4-tert-butylstyrene (403〓), 2,4-diisopropylstyrene (441〓), 2,5-dimethylstyrene (416〓),
Examples include 3,4-diethylstyrene (382〓), 2-hydroxymethylstyrene (433〓), 4-methylstyrene (366〓), and 2-methylstyrene (366〓). In this invention, one or more monomers represented by these group A or group B monomers are used, but other monomers can be copolymerized with this main monomer as necessary for the purpose of improving adhesiveness or tackiness. As a monomer, butyl acrylate,
The glass transition point of its homopolymers such as ethyl acrylate and 2-ethylhexyl acrylate is 273.
It is also possible to use one or more monomers used in general acrylic pressure-sensitive adhesives, such as monomers that lower the adhesive strength. However, if the amount used is too large, the effect of significantly improving cohesive force may be hindered, so the amount should be 50% by weight or less, preferably 30% by weight or less, based on the total monomers. The functional group-containing monomer in the modifying copolymer is used to introduce into the molecules of the modifying copolymer a functional group that is reactive with the functional group of the acrylic main copolymer, which is sticky at room temperature. The type of acrylic copolymer depends solely on the functional groups of the main acrylic copolymer. For example, if the functional group of the main acrylic copolymer is a carboxyl group or an acid anhydride group, a monomer having a secondary amino group, an epoxy group, or a hydroxyl group is used, and if the functional group is a hydroxyl group, a monomer having a carboxyl group or an acid anhydride group is used. In the case of a secondary amino group, a monomer having a carboxyl group, an epoxy group or an acid anhydride group is used, and in the case of an epoxy group, a monomer having a carboxyl group, an acid anhydride group or a secondary amino group is used. . In this case, it is also possible to use two or more kinds of functional group-containing monomers together. As already mentioned, carboxyl groups or acid anhydride groups are preferred as the functional groups in the main acrylic copolymer. Alternatively, monomers having a hydroxyl group may be used, and among these, particularly preferred are those having an epoxy group. On the contrary, it is also a suitable combination when the functional group of the acrylic main copolymer is an epoxy group and a monomer having a carboxyl group or an acid anhydride group is used as the functional group-containing monomer in the modifying copolymer. The specific example of the functional group-containing monomer and the requirement that each functional group itself does not absorb moisture or react alone under normal environmental conditions are the same as in the case of the acrylic-based copolymer. Regarding the proportion of the functional group-containing monomer used, in the total amount of the main monomer and other copolymerizable monomers used in the synthesis of the modifying copolymer,
In other words, the proportion of all monomers is usually 0.02~
The number of functional groups of the resulting modifying copolymer is set to 1.3% by weight, and the average number of functional groups per molecule is 0.5~
It is best to set the number to 0.95. Here, the average number of functional groups per molecule is 0.5 to 0.95.
This means that the number of functional groups is 0 and the number of functional groups is 1 or more, and the average value is within the above range. Good results can be obtained both in greatly improving the cohesive force and maintaining the adhesion and adhesive force. The solution polymerization and bulk polymerization methods employed to obtain the acrylic main copolymer and the modifying copolymer described above use polymerization catalysts such as general peroxides and azo compounds, and also use molecular weight control methods. Therefore, it may be carried out according to a conventional method, using a chain transfer agent as necessary. Examples of peroxides used here include benzoyl peroxide, cumene hydroperoxide, di-tert-butyl peroxide,
tert-butyl peroxybenzoate, lauroyl peroxide, ketone peroxide, tert
-Butylperoxy 2-ethylhexanoate,
Examples include methyl ethyl ketone peroxide and cyclohexanone peroxide. The amount of polymerization catalysts such as organic peroxides and azo compounds used is 0.01 to 5 parts by weight based on 100 parts by weight of total monomers.
Preferably it is about 0.05 to 3 parts by weight. Examples of organic solvents used in solution polymerization include toluene, benzene, xylene, hexane, heptane, n-octane, isooctane, ethyl acetate, acetone, methyl ethyl ketone, methanol, ethanol, and isopropanol. Particularly preferred from the viewpoint of polymerization workability is toluene alone or a mixed solvent containing toluene in an amount of 50% by weight or more. In this invention, the main acrylic copolymer that is tacky at room temperature obtained in this way is mixed with a modifying copolymer that is non-adhesive or has low tackiness at room temperature, and then both copolymers are heated to mutually interact with the functional groups. It is important to react between them to form a graft. That is, in the present invention, a pressure-sensitive adhesive having high cohesiveness and good adhesion or tackiness can only be obtained by using the graft polymer formed by this method as an active adhesive ingredient. The ratio of the main acrylic copolymer and the modifying copolymer in carrying out this grafting reaction varies depending on the desired cohesiveness and adhesiveness, and also depends on the number of functional groups contained in each copolymer. Generally speaking, the amount of the modifying copolymer should be 5 to 200 parts by weight, preferably 10 to 150 parts by weight, based on 100 parts by weight of the main acrylic copolymer. If this amount is too small, the cohesive force cannot be improved much, whereas if this amount is too large, there is a risk that adhesiveness or tackiness may be reduced. In the grafting reaction, an appropriate catalyst is added to the composition as necessary and the adhesive composition, which is generally in a solution state made by mixing each copolymer, is applied to the substrate, and then a heating reaction is carried out. This is done by The heating conditions depend on the mutual reactivity of the functional groups; for example, when either the acrylic main copolymer or the modifying copolymer has an epoxy group as a functional group and the other has a carboxyl group, The reaction may be carried out in the presence of an alkali catalyst at 70 to 150°C for about 10 to 0.2 hours. On the other hand, in cases where the reactivity between the functional groups is relatively high, it is also possible to carry out the grafting reaction after coating the substrate. For example, in the above example of the combination of epoxy group and carboxyl group,
The grafting reaction can also be sufficiently carried out by applying the adhesive composition to a substrate, drying it, and then heating it in a heating chamber at about 50° C. for about 12 to 48 hours. As described above, the acrylic pressure-sensitive adhesive of the present invention containing the graft polymer thus obtained exhibits good adhesion or tackiness as well as high cohesiveness, but if it is desired to further improve this cohesiveness, A general crosslinking agent may be further added to the adhesive composition after the above-mentioned grafting reaction, or in the adhesive composition before application in an embodiment in which the grafting reaction is performed after being applied to a substrate and dried. There is no problem in combining them. Examples of such crosslinking agents include, for example, ethyl etherified methylol melamine, butyl etherified methylol melamine, tolylene diisocyanate, hexamethylene diisocyanate, alkyl phenols, zinc acetate, tin chloride, calcium oxide, benzoyl peroxide, bisphenol A. Examples include diglycidyl ether.
The amount of these components to be blended may be very small, and it is sufficient to add about 0.001 to 1.5 parts by weight based on 100 parts by weight of the main acrylic copolymer that is sticky at room temperature. It is also possible to add known compounding agents such as colorants, fillers, anti-aging agents, and tackifiers at the same stage as above. This invention will be described in more detail below with reference to Examples, but this invention is not limited to these and various modifications can be made without departing from the technical idea of this invention. The adhesive force and holding force below were measured by the following method. Furthermore, the number of functional groups per molecule of the acrylic main copolymer and the modifying copolymer in each of the following examples means the average number of functional groups per molecule. <Adhesive strength> 180° peeling strength according to JISZ-1528 (g/
20mm) was measured. <Holding power> Each adhesive tape is attached to two Bakelite plates 25 x 25
mm, and the time (minutes) required for the Bakelite plate to fall was measured by applying a load of 1 kg at 40°C. Example 1 Octyl acrylate 100g, ethyl acrylate
20 g of acrylic acid, 7 g of acrylic acid, and 300 g of ethyl acetate were put into a three-necked flask, and after stirring for 1 hour in a nitrogen stream, 0.1 g of benzoyl peroxide was added, and the temperature was raised to 70° C. and reacted for 5 hours. The obtained polymer solution A contained a main acrylic copolymer that was sticky at room temperature, and the average molecular weight of this polymer was about 330,000, and the number of functional groups (carboxyl groups) per molecule was about 150. Separately, 28g of methyl methacrylate, 12g of ethyl acrylate, glycidyl ether methacrylate
0.22 g of lauryl mercaptan, 0.4 g of lauryl mercaptan, and 80 g of toluene were placed in a three-necked flask, and after stirring for 1 hour in a nitrogen stream, benzoyl peroxide was added.
0.08g was added, the temperature was raised to 80°C, and the reaction was carried out for 6 hours. The obtained polymer solution B contains a modifying copolymer that is non-tacky at room temperature, and this polymer has an average molecular weight of about 20,000, a number of functional groups (epoxy groups) per molecule of about 0.8, and a glass transition point of 327. 〓It was hot. Next, the above polymer solution A and polymer solution B were mixed, 1/10 equivalent of ammonia was added to the carboxyl group contained in polymer solution A, and the mixture was heated at 80°C for 5 hours with stirring. A graft polymer consisting of an acrylic main copolymer and a modifying copolymer was produced, and this pressure-sensitive adhesive solution was coated on both sides of a 25μ thick polyester film so that the dry thickness was 30μ on one side at 100°C.
A pressure-sensitive adhesive tape was prepared by heating and drying for 3 minutes. Example 2 Polymer solution A and polymer solution B obtained by the method of Example 1 were mixed, and 1/10 equivalent of ammonia was added to the carboxyl group contained in polymer solution A. Adhesive solution 25μ thick
It was coated on both sides of a polyester film with a dry thickness of 30 μm on each side and dried by heating at 100° C. for 3 minutes. Thereafter, it was further left in a heating room at 50° C. for 48 hours to produce a graft polymer consisting of an acrylic main copolymer and a modifying copolymer, thereby forming a pressure-sensitive adhesive tape. Comparative Example 1 A pressure-sensitive adhesive tape was produced in the same manner as in Example 2, except that the heat treatment for producing the graft polymer was not performed after heating and drying. Comparative Example 2 Except that methacrylic acid glycidyl ester was not used in the preparation of polymer solution B, and the heating reaction treatment after mixing polymer solution A and polymer solution B and adding ammonia was not performed.
A pressure sensitive adhesive tape was made in exactly the same manner as in Example 1. Comparative Example 3 A pressure-sensitive adhesive tape was prepared in exactly the same manner as in Example 1, except that 28 g of ethyl acrylate was used in place of methyl methacrylate in preparing polymer solution B. The average molecular weight of the modifying polymer in this example was approximately 30,000, the glass transition point was 249, and the number of functional groups (epoxy groups) per molecule was approximately 0.8. Comparative Example 4 All monomers used in the preparation of polymer solutions A and B of Example 1, i.e. octyl acrylate
100g, ethyl acrylate 32g, acrylic acid 7g,
28 g of methyl methacrylate and 0.22 g of glycidyl methacrylate were placed in a three-necked flask, and 300 g of ethyl acetate and 80 g of toluene were added to the flask.
After stirring for 1 hour in a nitrogen stream, 0.1 g of benzoyl peroxide was added, the temperature was raised to 70°C, and the mixture was reacted for 5 hours. The average molecular weight of the acrylic copolymer in the obtained polymer solution was about 280,000. This polymer solution was coated on both sides of a polyester film with a thickness of 25 μm so that the dry thickness was 30 μm on each side, and the film was heated and dried at 100° C. for 3 minutes to prepare a pressure-sensitive adhesive tape. The adhesive strength and holding power of each of the adhesive tapes of Examples 1 and 2 and Comparative Examples 1 to 4 described above were as shown in the following table.

[Table] Example 3 100 g of n-butyl acrylate, 3 g of N-tert-butylaminoethyl acrylate, and 200 g of a 10:2 mixed solvent of toluene and ethanol were placed in a three-necked flask and stirred for 2 hours in a nitrogen stream. After that, α,α′-azobisisobutyronitrile 0.05g
was added and the temperature was raised to 60°C, followed by reaction at 58°C for 24 hours. The obtained polymer solution C contained a main acrylic copolymer that was sticky at room temperature, and the average molecular weight of this polymer was about 280,000, and the number of functional groups (secondary amino groups) per molecule was about 50. . Separately, 100 g of n-butyl methacrylate, 0.19 g of glycidyl methacrylate, and 500 g of a 10:2 mixed solvent of toluene and ethanol were placed in a three-necked flask, and after stirring for 1 hour in a nitrogen stream,
0.5 g of α,α'-azobisisobutyronitrile was added, the temperature was raised to 80°C, and the mixture was reacted for 5 hours. The resulting polymer solution D contains a modifying copolymer that is non-tacky at room temperature and has an average molecular weight of about 100,000;
The number of functional groups (epoxy groups) per molecule is approximately 0.95
The glass transition point was 293〓. Next, the above polymer solution C and polymer solution D were mixed and reacted by heating at 80°C for 5 hours to produce a graft polymer consisting of an acrylic main copolymer and a modifying copolymer. The mixture was coated on both sides of a polyester film with a thickness of 25 μm so that the dry thickness was 30 μm on each side, and the mixture was heated and dried at 100° C. for 3 minutes to produce a pressure-sensitive adhesive tape. When the adhesive strength and retention strength of this tape were examined, the adhesive strength was 790 g/20 mm, and the retention strength was over 1000 minutes. Example 4 100 g of ethyl acrylate, 100 g of 2-ethylhexyl acrylate, 10 g of acrylic acid, and 490 g of toluene were placed in a three-necked flask, stirred in a nitrogen stream, and then 0.5 g of benzoyl peroxide was added.
was added and reacted at 60°C for 10 hours. The obtained polymer solution E contained an acrylic acid-based copolymer that was sticky at room temperature, and the average molecular weight of this polymer was about 250,000, and the number of functional groups (carboxyl groups) per molecule was about 172. Separately, 100 g of styrene, 0.8 g of hydroxyethyl acrylate, and 230 g of toluene were placed in a three-necked flask, and after stirring in a nitrogen stream, α,
0.5 g of α'-azobisisobutyronitrile was added and reacted at 80°C for 10 hours. The obtained polymer solution F contains a modifying copolymer that is non-tacky at room temperature, and the average molecular weight of this polymer is about 8000, the number of functional groups (hydroxyl groups) per molecule is about 0.8, and the glass transition point is 373〓. It was hot. Next, 100 g of the above polymer solution E and 14.3 g of polymer solution F were mixed, 0.015 g of para-toluenesulfonic acid and 100 g of toluene were added thereto, and the mixture was refluxed for about 20 hours at the boiling point of toluene to cause an esterification reaction. A graft polymer consisting of an acrylic main copolymer and a modifying copolymer is produced,
Then 0.03 g of zinc acetate was added. This pressure-sensitive adhesive solution was coated on both sides of a 25 μm thick polyester film so that the dry thickness was 30 μm on each side, and the film was heated and dried at 100° C. for 3 minutes to produce a pressure-sensitive adhesive tape.
The adhesive strength of this tape is 790g/20mm, and the retention strength is 850
It was hot in minutes. Example 5 100 g of isooctyl acrylate, 2 g of maleic anhydride, and 238 g of benzene were placed in a three-necked flask, stirred in a nitrogen stream, and then 1 g of α,α'-azobisisobutyronitrile was added and heated at 60°C. in 10
Allowed time to react. The obtained polymer solution G contained a main acrylic copolymer that was sticky at room temperature, and the average molecular weight of this polymer was about 350,000, and the number of functional groups (acid anhydride groups) per molecule was about 70. Separately, 100g of methyl methacrylate,
tert-butylaminoethyl methacrylate 1.2g,
2g lauryl mercaptan and 100g benzene
was added to a three-necked flask and stirred in a nitrogen stream, and then α,α′-azobisisobutyronitrile 0.5
g was added thereto, the temperature was raised to 80°C, and the mixture was reacted for 10 hours. The resulting polymer solution H contains a modifying copolymer that is non-tacky at room temperature and has an average molecular weight of about 20,000 and a functional group (secondary amino group) per molecule.
The number was about 0.7, and the glass transition point was 378〓. Next, 100g of the above polymer solution G and 39g of polymer solution H were mixed, 100g of benzene was added thereto, and the mixture was refluxed for about 8 hours at the boiling point of benzene to cause an acylation reaction between the acid anhydride group and the secondary amine. A graft polymer consisting of a system main copolymer and a modifying copolymer was produced, and this pressure-sensitive adhesive solution was coated on both sides of a 25μ thick polyester film so that the dry thickness was 30μ on one side, and heated at 100°C.
A pressure-sensitive adhesive tape was prepared by heating and drying for 3 minutes. This tape had an adhesive strength of 750 g/20 mm and a retention strength of 360 minutes.

Claims (1)

[Claims] 1. Acrylic acid or methacrylic acid and 12 carbon atoms
The main monomer consisting of an ester with the following alcohol and a functional group-containing monomer are essential copolymerized monomers, the average molecular weight is 30,000 to 1,000,000, and the average number of functional groups per molecule is 1 to 2,000. Sticky at room temperature. The glass transition temperature of acrylonitrile, methacrylonitrile, vinyl acetate, styrene, and homopolymers is 273.
〓A main monomer consisting of one or more monomers selected from the group of acrylic esters, methacrylic esters, and styrene derivatives, and a functional group that is reactive with the functional group contained in the acrylic main copolymer. The glass transition point is 273〓 or higher, the average molecular weight is 2,000 to 100,000, and the average number of functional groups per molecule is 0.5.
An acrylic pressure-sensitive adhesive that uses a modifying copolymer with a non-adhesive or low-adhesive property at room temperature of ~0.95, and has a graft polymer formed by the reaction between the functional groups of both copolymers as an active adhesive ingredient. 2. The acrylic-based copolymer according to claim 1, wherein the functional group of the main acrylic copolymer is selected from a carboxyl group, an acid anhydride group, a hydroxyl group, a secondary amino group (>NH), and an epoxy group. Pressure adhesive. 3. The acrylic resin according to claim 1, wherein the functional group of either the main acrylic copolymer or the modifying copolymer is a carboxyl group or an acid anhydride group, and the functional group of the other is an epoxy group. Pressure adhesive. 4. The acrylic pressure-sensitive adhesive according to any one of claims 1 to 3, wherein 5 to 200 parts by weight of the modifying copolymer are used based on 100 parts by weight of the main acrylic copolymer. 5. The acrylic pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the modifying copolymer has a glass transition point of 300 or higher.