JP2008208149A - Method for producing acrylic copolymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a new acrylic copolymer composed exclusively of reactive components, essentially free from volatile components (organic solvent and water) and useful as a coating material, a tacky adhesive agent and an adhesive agent. <P>SOLUTION: The method for producing an acrylic copolymer comprises the radical copolymerization of acrylic monomers containing an acrylic monomer having an alicyclic epoxy group by using an oxetane compound of the structure formula as a polymerization medium and a reactive diluent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a method for producing an acrylic copolymer that is curable by heating and / or irradiation with active energy rays and is useful as an adhesive for flat panel displays (FPD) and an adhesive for metals and plastics. Is.

  Acrylic resins are industrially produced by methods such as bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. (Refer nonpatent literature 1) Except bulk polymerization method, generally, it manufactures in an organic-solvent medium or water as a medium for the purpose of heat removal during polymerization, molecular weight adjustment, and the like. In the case where the organic solvent or water is used as it is for general purposes such as paints and adhesives, it can be produced by solution polymerization using an organic solvent as a polymerization medium and emulsion polymerization using water as a polymerization medium. On the other hand, even if it is a paint or an adhesive, if the surface of the object to be coated or the substrate is rough or uneven, the rough surface and unevenness are smoothed, and there are no defects in the coating film and adhesive. In order to form the surface, it is necessary to remove volatile components (organic solvent, water) from the paint and adhesive. Moreover, when manufacturing a molded object and when using as an adhesive agent, it cannot be overemphasized that it is desirable for a volatile component not to be contained.

An example of producing a solventless acrylic resin (acrylic resin + acrylic monomer) is disclosed. (See Patent Document 1) In this method, radical polymerization by ultraviolet irradiation of an acrylic resin is stopped during the polymerization, and a so-called acrylic syrup in which a high molecular weight acrylic resin is diluted with an acrylic monomer constituting the acrylic resin is produced. Is the method. The composition contains a large amount of acrylic monomer, and not only has a nasty smell peculiar to the acrylic monomer, but there is a considerable concern about the adverse effects on the health and environment at the site where the adhesive is used.
JP-A-2005-23133 "Synthesis / design and application development of acrylic resin" = Comprehensive technical data collection =, Chubu Business Development Center Publishing Department (1985), p11-16

  The present invention relates to a method for producing an acrylic copolymer for providing a paint, a pressure-sensitive adhesive, and an adhesive that have low odor and are environmentally and health-conscious.

  The present invention includes at least one oxetane compound having the following structural formula as a polymerization medium and a reactive diluent,

(However, n represents an integer of 1 to 5)
The present invention relates to a method for producing an acrylic copolymer in which an acrylic monomer containing an alicyclic epoxy group-containing acrylic monomer represented by the following structural formula is radically copolymerized.

(However, R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 1 to 4 carbon atoms.)

  The method for producing an acrylic copolymer of the present invention is a method for producing an acrylic copolymer for providing a coating material, a pressure-sensitive adhesive, and an adhesive that have low odor and are environmentally and health-conscious.

  According to the method for producing an acrylic copolymer of the present invention, it is possible to produce an acrylic copolymer which is substantially free of volatile components (organic solvent and water) and is composed only of a reactive compound.

  The acrylic copolymer produced according to the present invention can be cured by heating and irradiation with active energy rays (preferably visible light and ultraviolet rays), and the cured composition preferably forms a strong three-dimensional network structure. To do.

  The present invention includes at least one oxetane compound having the following structural formula as a polymerization medium and a reactive diluent,

(However, m represents an integer of 1 to 3)

(However, n represents an integer of 1 to 5)
The present invention relates to a method for producing an acrylic copolymer in which an acrylic monomer containing an alicyclic epoxy group-containing acrylic monomer represented by the following structural formula is radically copolymerized.

(However, R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 1 to 4 carbon atoms.)
In general, the polymerization medium is a radical copolymerization reaction in which an acrylic monomer radically copolymerizes with a radical copolymer of an acrylic monomer without causing a radical reaction except for a specific reaction such as a serial transfer reaction. It has no influence on the copolymerization and provides a polymerization field for the acrylic copolymer to form. In general, in the case of solution polymerization in which an acrylic copolymer is formed as a uniform solution, what provides a field for polymerization generated by the acrylic copolymer is called a polymerization solvent or a polymerization solvent. In the case where the polymer precipitates as particles, or in the case of a heterogeneous system that forms as a stable dispersion, the one that provides the polymerization field that the acrylic copolymer forms is said to be the polymerization medium.

  In the method for producing an acrylic copolymer of the present invention, the polymerization medium is an oxetane compound having a specific structure. The oxetane compound having a specific structure used in the present invention does not cause radical copolymerization with an acrylic monomer that is a constituent material of the acrylic copolymer when the acrylic copolymer is produced by a radical copolymerization reaction, Provides a polymerization field for the production of acrylic copolymers.

  That is, the present inventors, in the method for producing an acrylic copolymer of the present invention, the oxetane compound having a specific structure used in the present invention is a good solvent for the produced acrylic copolymer, or the produced acrylic copolymer. The present inventors have found that it becomes a dispersion medium in which a copolymer is uniformly and stably dispersed.

  In the present invention, the oxetane compound having a specific structure not only serves as a polymerization medium in the production of an acrylic copolymer, but also is an acrylic copolymer upon heating or irradiation with active energy rays (preferably, visible light or ultraviolet rays). It reacts with the alicyclic epoxy group possessed by to form a strong three-dimensional network structure and acts as a reactive diluent. In the present invention, the crosslinking reaction with an oxetane compound having a specific structure preferably proceeds by a cationic polymerization mechanism, and achieves a high reaction achievement rate (70%) at a relatively low temperature (150 ° C. or less) and in a short time (within 2 hours). The above can be achieved.

  In the present invention, the oxetane compound represented by the following structural formula is

Chemical name 3-ethyl-3-hydroxymethyloxetane (oxetane alcohol). As an example of the oxetane compound marketed, "Aron oxetane OXT-101" (Oxetane compound of Toagosei Co., Ltd.) etc. are illustrated.

  3-ethyl-3-hydroxymethyloxetane has a boiling point of 105 ° C./7 mmHg and is not volatile at room temperature. In addition, it is a relatively safe oxetane compound with a flash point of 112 ° C. (Cleveland release type) (type 4 and type 3 petroleum water-soluble liquid). Furthermore, unlike many epoxy compounds, it is negative in the Ames test and there is no anxiety about mutagenesis.

  In the present invention, as an oxetane compound represented by the following structural formula,

(However, m represents an integer of 1 to 3)
Examples include 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene (when y = 1). Examples of oxetane compounds on the market include “Aron oxetane OXT-121” (an oxetane compound from Toagosei Co., Ltd.), “ETERNACOLL OXBP” (an oxetane compound from Ube Industries), and the like. These oxetane compounds may be used alone or as a mixture of two or more.

  These oxetane compounds have a very high boiling point (100 ° C. or higher) and are not volatile at room temperature. In addition, it is a relatively safe oxetane compound with a flash point of 220 ° C. (Cleveland release type) (type 4 and type 4 petroleum). Furthermore, unlike many epoxy compounds, it is negative in the Ames test and there is no anxiety about mutagenesis.

  In the present invention, as an oxetane compound represented by the following structural formula,

(However, n represents an integer of 1 to 5)
Phenol novolac oxetane and the like are exemplified. As what can be obtained in the market, Toagosei Co., Ltd. offers a developed product under the name “Aron Oxetane PNOX-1009”. These oxetane compounds may be used alone or as a mixture of two or more.

  These oxetane compounds have a very high boiling point (not measurable) and are not volatile at room temperature. It is also a safe oxetane compound with a flash point of 299 ° C. (Cleveland release type) (non-dangerous). Furthermore, unlike many epoxy compounds, it is negative in the Ames test and there is no anxiety about mutagenesis.

  The oxetane compound used in the present invention does not have radical polymerizability and has good compatibility with the acrylic copolymer, so that it can be used as a radical copolymerization medium for the acrylic copolymer. The inventors of the present invention focused on this point and made the present invention.

  In the present invention, an oxetane compound represented by the following structural formula is recommended as the polymerization medium and the reactive diluent.

  In the present invention, when 3-ethyl-3-hydroxymethyloxetane is used as the radical copolymerization medium for the acrylic copolymer, 3-ethyl-3-hydroxymethyloxetane is widely compatible with the acrylic copolymer. Therefore, it is easy to design the acrylic copolymer composition, and there is a tendency that it is possible to design paints, pressure-sensitive adhesives, and adhesives with better performance in a customer-made manner.

  In the present invention, as the alicyclic epoxy group-containing acrylic monomer represented by the following structural formula,

(However, R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 1 to 4 carbon atoms.)
Examples include 3,4-epoxycyclohexylmethyl acrylate and 3,4-epoxycyclohexylmethyl methacrylate. Examples of commercially available alicyclic epoxy group-containing acrylic monomers include “Cyclomer M-100” and “Cyclomer A-400” (product of Daicel Chemical Industries, Ltd.). These alicyclic epoxy group-containing acrylic monomers may be used alone or as a mixture of two or more.

  In the present invention, the alicyclic epoxy group-containing acrylic monomer is preferably 3 to 98% by weight, more preferably 5%, based on 100 parts by weight of the total amount with other copolymerizable acrylic monomers. It is desirable to copolymerize in an amount of -80% by weight, more preferably 8-60% by weight. In the present invention, when the alicyclic epoxy group-containing acrylic monomer is copolymerized in an amount of 3 to 98% by weight, the performance of the paint, pressure-sensitive adhesive, and adhesive containing the acrylic copolymer produced in the present invention is improved. A trend is seen and recommended.

  Other acrylic monomers that can be used by copolymerizing with an alicyclic epoxy group-containing acrylic monomer in the present invention include methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic I-butyl acid, cyclohexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, i-butyl methacrylate, acrylic Acid, methacrylic acid, polypropylene glycol monoacrylate, polyethylene glycol monoacrylate, polytetramethylene glycol monomethacrylate, etc. Polypropylene glycol having a (meth) acryloyl group at the end of the molecular chain, polyethylene glycol, poly Tiger glycol, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, a hydroxyl group-containing acrylic monomers such as methacrylic acid 4-hydroxybutyl and the like. These acrylic monomers may be used alone or as a mixture of two or more.

  In the present invention, among these acrylic monomers, a hydroxyl group-containing acrylic such as 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, and the like is particularly preferable. The use of monomers is recommended. Hydroxyl group-containing acrylic monomer has an effect of enhancing the curability of paints, pressure-sensitive adhesives, and adhesives containing the acrylic copolymer produced in the present invention, and tends to exhibit good adhesive force even during thin film bonding Is seen. In addition, adhesion to metals such as aluminum alloy and titanium alloy has been dramatically improved, and it is extremely effective to prevent corrosion of metals in electrolyte solutions such as water resistance, salt water resistance, and heat and humidity resistance, and to prevent adhesion failure. Provide effective means.

  The acrylic copolymer produced by the method for producing an acrylic copolymer of the present invention is preferably a hydroxyl group-containing acrylic copolymer.

  The hydroxyl value of the hydroxyl group-containing acrylic copolymer that is preferably produced by the method for producing an acrylic copolymer of the present invention is preferably 10 to 80 mgKOH, more preferably 20 to 70 mgKOH.

Here, in the present invention, the hydroxyl value (mgKOH) is
(Weight% of copolymerized hydroxyl-containing acrylic monomer × 561) / (Molecular weight of copolymerized hydroxyl-containing acrylic monomer)
Calculated by

  When the hydroxyl group value of the hydroxyl group-containing acrylic copolymer preferably produced in the present invention is 10 to 80 mgKOH, the curability of the paint, pressure-sensitive adhesive, adhesive, and various coatings containing the hydroxyl group-containing acrylic copolymer produced in the present invention Adhesiveness and adhesion to coatings and adherends tend to be greatly improved and improved, and are recommended.

  In the method for producing an acrylic copolymer of the present invention, the acrylic copolymer is preferably produced by solution polymerization using an oxetane compound having a specific structure as a polymerization medium and a reactive diluent.

  In the method for producing an acrylic copolymer of the present invention, an acryl monomer containing an alicyclic epoxy group-containing acrylic monomer in an oxetane compound having a specific structure has a polymerization temperature of preferably 30 to 120. The acrylic copolymer can be produced at a temperature of 50 ° C, more preferably 50 to 100 ° C, and still more preferably 60 to 100 ° C.

  Furthermore, in the method for producing an acrylic copolymer of the present invention, in the oxetane compound having a specific structure, an acrylic monomer containing an alicyclic epoxy group-containing acrylic monomer, preferably nitrogen gas, helium gas An acrylic copolymer can be produced under an inert gas atmosphere such as.

  In the method for producing an acrylic copolymer of the present invention, an acryl monomer containing an alicyclic epoxy group-containing acrylic monomer in an oxetane compound having a specific structure is preferably benzoyl peroxide, t -Acrylic copolymer by radical copolymerization using an organic peroxide such as butylperoxy-2-ethylhexanoate and an organic azo compound such as α, α-azobisisobutyronitrile as a polymerization initiator Can be manufactured.

  In the method for producing an acrylic copolymer of the present invention, the concentration of the acrylic copolymer after production is preferably 10 to 95% by weight, more preferably 20 to 85% by weight, and still more preferably 40 to 80% by weight. It is recommended that In the method for producing an acrylic copolymer of the present invention, when the concentration of the acrylic copolymer after production is less than 10% by weight, the production efficiency is poor, and the paint, pressure-sensitive adhesive, and adhesive containing the acrylic copolymer are poor. There are cases where curability, adhesion, and adhesion deteriorate. When the concentration of the acrylic copolymer after production exceeds 95% by weight, stirring during production may not be sufficiently performed, and there may be a case where heat removal is not successful.

  The number average molecular weight of the acrylic copolymer produced in the present invention is preferably 2000 to 200,000, more preferably 3000 to 180,000, and still more preferably 5000 to 150,000. . When the number average molecular weight of the acrylic copolymer is 2000 to 200,000, it tends to be easy to remove the heat of polymerization during production, stir the reaction system, etc., and to carry out the production work safely. Moreover, the tendency which the sclerosis | hardenability, adhesiveness, and adhesiveness of the coating material containing the acrylic copolymer manufactured by this invention, an adhesive, and an adhesive agent becomes favorable is seen.

  Here, in the present invention, the molecular weight of the acrylic resin is “gel permeation chromatography” (GPC) (for example, “HLC-8220” GPC system manufactured by Tosoh Corporation), and “standard polystyrene” (for example, , "POLYSTYREN" manufactured by GL Sciences Inc.).

  Hereinafter, the present invention will be described in detail with examples.

In the examples and comparative examples, the composition ratio represents a weight ratio unless otherwise specified. Various tests and evaluations were performed according to the following.
(1) The number average molecular weight was measured by GPC using standard polystyrene as a molecular weight standard.
(2) The composition ratio between the acrylic copolymer and the oxetane compound was calculated from the acrylic copolymer peak area and the oxetane compound peak area using GPC.
(3) Tensile strength of heat-cured acrylic copolymer a) Preparation of test piece Adhesive containing acrylic copolymer was applied to a Teflon (registered trademark) mold (form No. 3 dumbbell) with a film thickness of 2 mm. Unless otherwise specified, it was heat-cured at 80 ° C. for 1 hour. A tensile test was performed using this test piece.

b) The tensile test of the adhesive was performed in accordance with JIS K 7113 (1995) (plastic tensile test method). The pulling speed is 300 mm / min. And carried out at 23 ° C.
(4) Adhesion test 1) Initial adhesion test a) Preparation of test piece An adhesive containing an acrylic copolymer was uniformly applied to an A-2017P aluminum plate (film thickness 50 μm, application area 25 mm × 25 mm). An aluminum plate was pressure-bonded to the surface of the adhesive, and unless otherwise noted, heat-cured at 80 ° C. for 1 hour. The shear adhesion force was measured using this test piece.

  b) Test method A-2017P aluminum plate (size: length 50 mm, width 25 mm, thickness 2 mm) is used, and conforms to JIS K 6850 (1999) (Test method for tensile shear bond strength of rigid substrates). I went. The pulling speed is 1.0 mm / min. The test temperature was 23 ° C. unless otherwise specified.

  2) Water resistance test (4) -1) The test piece prepared in (a) was immersed in warm water at 80 ° C. for 72 hours. Then, the adhesiveness test was done according to (4) -1) (b).

Example 1
160 g of “Aron oxetane OXT-101” (an oxetane compound of Toagosei Co., Ltd.) was charged as a polymerization medium in a 1-liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  The temperature increase was started and the temperature was increased to 85 ° C. in 30 minutes. Thereafter, this temperature was maintained during production.

  N-butyl acrylate / "Cyclomer M-100" (Daicel Chemical Industries' alicyclic epoxy group-containing acrylic monomer; 3,4-epoxycyclohexylmethyl methacrylate) / 2-hydroxyethyl methacrylate (= 72 / A mixed solution in which 19.2 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved in 640 g of a monomer mixture of 20/8) was dropped into the flask in 3 hours.

  After completion of dropping, 0.6 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added at 1 hour, 2 hours, and 3 hours, and polymerization was continued for 2 hours to obtain an acrylic copolymer ( 1) was produced. The number average molecular weight of the acrylic copolymer (1) was 16,000, the hydroxyl value was 35 mgKOH, and the acrylic copolymer (1) / oxetane compound was 80/20.

  To 100 g of the oxetane compound solution of the acrylic copolymer (1), 2 g of “Sun-Aid SI-60L” (cationic polymerization initiator made by Sanshin Chemical Co., Ltd.) was added, and “Mazerustar KK-100” (made by Kurabo Industries, stirring and defoaming) The adhesive (1) was produced by stirring, mixing, and defoaming in the apparatus.

  A tensile test and an adhesion test were performed using the adhesive (1). The test results are shown in Table 1.

Example 2
320 g of “Aron oxetane OXT-101” (an oxetane compound of Toagosei Co., Ltd.) was charged as a polymerization medium in a 1-liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  The temperature increase was started and the temperature was increased to 85 ° C. in 30 minutes. Thereafter, this temperature was maintained during production.

  N-butyl acrylate / "Cyclomer M-100" (Daicel Chemical Industries' alicyclic epoxy group-containing acrylic monomer; 3,4-epoxycyclohexylmethyl methacrylate) / 2-hydroxyethyl methacrylate (= 72 / 20/8), a mixed solution prepared by dissolving 4.8 g of 2,2′-azobis (2,4-dimethylvaleronitrile) in 480 g of the monomer mixture was dropped into the flask in 3 hours.

  2,2'-azobis (2,4-dimethylvaleronitrile) 0.5 was added at 1 hour, 2 hours, and 3 hours after the completion of the dropwise addition, and polymerization was continued for 2 hours to obtain an acrylic copolymer ( 2) was produced. The number average molecular weight of the acrylic copolymer (2) was 42,000, the hydroxyl value was 35 mgKOH, and the acrylic copolymer (2) / oxetane compound was 60/40.

  To 100 g of the oxetane compound solution of the acrylic copolymer (2), 2 g of “Sun-Aid SI-60L” (cationic polymerization initiator manufactured by Sanshin Chemical Co., Ltd.) was added, and “Mazerustar KK-100” (Kurabo Co., Ltd. stirring and defoaming) The adhesive (2) was produced by stirring, mixing, and defoaming in the apparatus.

  A tensile test and an adhesion test were performed using the adhesive (2). The test results are shown in Table 1.

Example 3
As a polymerization medium, 256 g of “Aron oxetane OXT-101” (an oxetane compound of Toagosei Co., Ltd.), “Aron oxetane OXT-121” ( 64 g of oxetane compound from Toagosei Co., Ltd. was charged. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  The temperature increase was started and the temperature was increased to 85 ° C. in 30 minutes. Thereafter, this temperature was maintained during production.

  N-butyl acrylate / "Cyclomer M-100" (Daicel Chemical Industries' alicyclic epoxy group-containing acrylic monomer; 3,4-epoxycyclohexylmethyl methacrylate) / 2-hydroxyethyl methacrylate (= 72 / A mixed solution prepared by dissolving 14.4 g of 2,2′-azobis (2,4-dimethylvaleronitrile) in 480 g of a monomer mixture of 20/8) was dropped into the flask in 3 hours.

  After completion of dropping, 0.5 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added at 1 hour, 2 hours, 3 hours, and polymerization was continued for 2 hours to obtain an acrylic copolymer ( 3) was produced. The number average molecular weight of the acrylic copolymer (3) was 14,000, the hydroxyl value was 35 mgKOH, and the acrylic copolymer (3) / oxetane compound was 60/40.

  To 100 g of the oxetane compound solution of the acrylic copolymer (3), 2 g of “Sun-Aid SI-60L” (cationic polymerization initiator made by Sanshin Chemical Co., Ltd.) was added, and “Mazerustar KK-100” (made by Kurabo Industries, stirring and defoaming) The adhesive (3) was produced by stirring, mixing, and defoaming in the apparatus.

  A tensile test and an adhesion test were performed using the adhesive (3). The test results are shown in Table 1.

Example 4
As a polymerization medium, 256 g of “Aron oxetane OXT-101” (an oxetane compound from Toagosei Co., Ltd.), “Aron oxetane PNOX-1009” 64 g of oxetane compound from Toagosei Co., Ltd. was charged. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  The temperature increase was started and the temperature was increased to 85 ° C. in 30 minutes. Thereafter, this temperature was maintained during production.

  N-butyl acrylate / "Cyclomer M-100" (Daicel Chemical Industries' alicyclic epoxy group-containing acrylic monomer; 3,4-epoxycyclohexylmethyl methacrylate) / 2-hydroxyethyl methacrylate (= 72 / A mixed solution prepared by dissolving 14.4 g of 2,2′-azobis (2,4-dimethylvaleronitrile) in 480 g of a monomer mixture of 20/8) was dropped into the flask in 3 hours.

  After completion of dropping, 0.5 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added at 1 hour, 2 hours, 3 hours, and polymerization was continued for 2 hours to obtain an acrylic copolymer ( 4) was produced. The number average molecular weight of the acrylic copolymer (4) was 14,000, the hydroxyl value was 35 mgKOH, and the acrylic copolymer (4) / oxetane compound was 60/40.

  To 100 g of the oxetane compound solution of the acrylic copolymer (4), 2 g of “Sun-Aid SI-60L” (cationic polymerization initiator made by Sanshin Chemical Co., Ltd.) was added, and “Mazerustar KK-100” (made by Kurabo Industries, stirring and defoaming) The adhesive (4) was produced by stirring, mixing, and defoaming in the apparatus.

  A tensile test and an adhesion test were performed using the adhesive (4). The test results are shown in Table 1.

All of the adhesives (1) to (4) had good curability, mechanical properties, and adhesive performance.

Comparative Example 1
320 g of “jER828” (bisphenol A type epoxy resin from Japan Epoxy Resin Co., Ltd.) was charged as a polymerization medium in a 1 liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  The temperature increase was started and the temperature was increased to 85 ° C. in 30 minutes. Thereafter, this temperature was maintained during production.

  N-butyl acrylate / "Cyclomer M-100" (Daicel Chemical Industries' alicyclic epoxy group-containing acrylic monomer; 3,4-epoxycyclohexylmethyl methacrylate) / 2-hydroxyethyl methacrylate (= 72 / 20/8), a mixed solution in which 9.6 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved in 480 g of the monomer mixture was dropped into the flask in 3 hours.

  After completion of dropping, 0.5 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added at 1 hour, 2 hours, 3 hours, and polymerization was continued for 2 hours to obtain an acrylic copolymer ( 5) was produced. The number average molecular weight of the acrylic copolymer (5) was 32,000, the hydroxyl value was 35 mgKOH, and the acrylic copolymer (5) / epoxy resin was 60/40. The acrylic copolymer (5) and “jER828” (bisphenol A type epoxy resin of Japan Epoxy Resin Co., Ltd.) were not compatible, and the acrylic copolymer solution was cloudy.

  2 g of “Sun-Aid SI-60L” (cationic polymerization initiator made by Sanshin Chemical Co., Ltd.) is added to 100 g of the epoxy resin solution of the acrylic copolymer (5), and “Mazerustar KK-100” (made by Kurabo Industries, agitation and defoaming) The adhesive (5) was produced by stirring, mixing, and defoaming in the apparatus.

  A tensile test and an adhesion test were performed using the adhesive (5). The test results are shown in Table 2.

Comparative Example 2
320 g of “ERL-4221” (an alicyclic epoxy resin from Union Carbide) was charged as a polymerization medium in a 1-liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  The temperature increase was started and the temperature was increased to 85 ° C. in 30 minutes. Thereafter, this temperature was maintained during production.

  N-butyl acrylate / "Cyclomer M-100" (Daicel Chemical Industries' alicyclic epoxy group-containing acrylic monomer; 3,4-epoxycyclohexylmethyl methacrylate) / 2-hydroxyethyl methacrylate (= 72 / 20/8), a mixed solution in which 9.6 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved in 480 g of the monomer mixture was dropped into the flask in 3 hours.

  After completion of dropping, 0.5 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added at 1 hour, 2 hours, 3 hours, and polymerization was continued for 2 hours to obtain an acrylic copolymer ( 6) was produced. The number average molecular weight of the acrylic copolymer (6) was 28,000, the hydroxyl value was 35 mgKOH, and the acrylic copolymer (6) / alicyclic epoxy resin = 60/40.

  To 100 g of the alicyclic epoxy resin solution of the acrylic copolymer (6), 2 g of “Sun-Aid SI-60L” (cationic polymerization initiator made by Sanshin Chemical Co., Ltd.) was added, and “Mazerustar KK-100” (made by Kurabo Industries, Ltd.) , Defoaming apparatus), stirring, mixing, and defoaming were performed to produce an adhesive (6).

  A tensile test and an adhesion test were performed using the adhesive (6). The test results are shown in Table 2.

  Adhesive (5) had poor compatibility between the acrylic copolymer and the bisphenol A type epoxy resin, and therefore the adhesive was not curable and satisfactory mechanical properties and adhesive strength could not be obtained. The adhesive (6) had a very fast curing reaction rate, but only the surface tended to cure, and satisfactory mechanical properties and adhesive strength could not be obtained.

Claims (4)

As a polymerization medium and a reactive diluent, it contains at least one oxetane compound having the following structural formula,

(However, m represents an integer of 1 to 3)

(However, n represents an integer of 1 to 5)
The manufacturing method of the acrylic copolymer which radically copolymerizes the acrylic monomer containing the alicyclic epoxy group containing acrylic monomer shown by the following structural formula.

(However, R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 1 to 4 carbon atoms.)   The method for producing an acrylic copolymer according to claim 1, wherein the number average molecular weight of the acrylic copolymer is 2000 to 200,000.   The method for producing an acrylic copolymer according to claim 1 or 2, wherein the acrylic copolymer is a hydroxyl group-containing acrylic copolymer, and the hydroxyl value of the hydroxyl group-containing acrylic copolymer is 10 to 80 mgKOH. The method for producing an acrylic copolymer according to any one of claims 1 to 3, wherein the oxetane compound is an oxetane compound represented by the following structural formula.