JP2008074969A - Adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive composition comprising a curable (meth)acrylate modified epoxy resin containing an epoxy resin, a (meth)acrylate compound and a diamine compound as a curing agent or a bis(amino)alkylpiperazine. <P>SOLUTION: The adhesive composition comprising an acrylic resin having a number average molecular weight of 20,000-500,000 having a repeated unit represented by a structural formula:(provided that R represents a 1-4C alkyl group and n represents an integer of 1-10) in a molecule, an epoxy resin and the curing agent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a novel adhesive exhibiting excellent performance in impact resistance, heat resistance, chemical resistance, water resistance and the like.

  Epoxy adhesives have high mechanical strength and are excellent in adhesiveness, heat resistance, and chemical resistance of various substrates, and therefore are widely used from general purpose to structural adhesives. Epoxy adhesives have high heat resistance, chemical resistance, and electrical insulation, and some of them are used as adhesives for electronic materials and as adhesives for optical members.

  Epoxy adhesives can be cured from room temperature curing (used in paints and adhesives) using amino compounds such as N, N-dimethylpropylamine as curing agents, and acid anhydrides such as hexahydrophthalic anhydride as curing agents. It is possible to control a wide range of curing characteristics and various physical properties up to the high-temperature curing type (used in electrical materials), and is characterized by a wide range of applications. Furthermore, the bisphenol A diglycidyl ether type epoxy resin is preferably a cationically cured alicyclic epoxy resin or the like using an acid generator such as an iodonium salt as an initiator, so that the storage stability, pot life adjustment and the like are relatively high. It is applied to paints and adhesives that can be easily cured for a short time.

  Acrylic resins are excellent in weather resistance and transparency, and are relatively easy to adjust their physical properties. Therefore, in recent years, acrylic resins are widely used as adhesives and adhesives for FPDs (for example, as PDP functional filter adhesives). Demand is expected.

  A so-called acrylic-epoxy hybrid adhesive that combines the excellent performance of an epoxy resin as an adhesive and the function of an acrylic resin as a pressure-sensitive adhesive has been proposed (see Patent Document 1). The present proposal provides a curable (meth) acrylate-modified epoxy resin composition containing an epoxy resin, a (meth) acrylate compound and a diamine compound or bis (amino) alkylpiperazine as a curing agent. According to Patent Document 1, the mechanical toughness of the epoxy resin adhesive is improved as it is, and the impact resistance is improved, and it is said that the epoxy resin adhesive is suitable for use as an adhesive for an automobile bumper or the like. The aim of this proposal is (1) diluting high-viscosity epoxy resin with low-viscosity (meth) acrylate and reducing the viscosity to improve the adhesive application workability, (2) epoxy resin in the curing process Is cured with the diamine compound and the like, and the (meth) acrylate is polymerized to form an epoxy-acrylic interpenetrating network structure (hereinafter also referred to as IPN), which is a tough and impact-resistant adhesive. It is considered to be obtained. The aim of Patent Document 1 is very interesting. (1) When the viscosity of the adhesive is simply lowered, the adhesive viscosity becomes Newtonian and the adhesive flows easily. There is a tendency that the thickness cannot be obtained, and there is a concern that the adhesion to the adherend will deteriorate and the adhesive strength will be insufficient. (2) As is well known, bases such as diamine compounds and bis (amino) alkylpiperazines (Meth) acrylate is extremely poorly polymerizable in the presence of a reactive compound (or N-containing atom-containing compound), and the concern remains that (meth) acrylate remains unreacted even if sufficient time is taken for curing. This is not possible, and it is predicted that the adhesive strength will vary significantly. Furthermore, (meth) acrylates are strongly anaerobic, and if deaeration (deoxygenation) is insufficient, there will be similar concerns regarding the development of adhesive strength.

  A curable adhesive containing a polyacrylate component, an epoxy component, and a cationic initiator has been proposed (see Patent Document 2). This proposal is useful for forming structural supports on fragile optical elements. The proposed technique is applied to optical coatings. Therefore, as shown in claim 1 of Patent Document 2, that is, a curable adhesive containing a polyacrylate component, an epoxy component, and a cationic initiator, wherein the uncured adhesive is optically Transparent, the luminous transmittance of the composition is greater than 90%, the haze of the composition is less than 2%, and the opacity of the composition is less than 1%. The adhesive described in Patent Document 2 can form an adhesive containing an interpenetrating polymer network by curing an uncured curable adhesive, and the cured adhesive is aged at 90 ° C. for 500 hours. The cured and aged adhesive has a luminous transmittance greater than 90%, the haze of the cured and aged adhesive is less than 2%, and the opacity of the cured and aged adhesive is less than 1%. Adhesive composition. In the adhesive described in Patent Document 2, transparency of the adhesive is regarded as extremely important.

  However, the transparency of the adhesive greatly depends on the volume of the adhesive solution, the distance through which light passes, the thickness of the adhesive, the shape of the adherend, the material, and the like. In the proposal described in Patent Document 2, There is no detailed description regarding these, for example, the method of measuring luminous transmittance, the thickness of the adhesive, etc., and the transparency as the present proposal says is unclear. Moreover, since transparency is very important for the adhesive described in Patent Document 2, blending of fillers is substantially inappropriate. When a filler is blended, even if the filler size is extremely small at the nano level, it seems difficult to avoid haze and opacity regardless of the blending amount and dispersion method of the filler. It is. As a result, the viscosity of the adhesive (hereinafter also referred to as rheology) cannot be appropriately controlled, and there is a concern that the control of the adhesive film thickness becomes insufficient or the adhesive strength is insufficient.

  In the adhesive described in Patent Document 2, the polyacrylate exists independently without self-crosslinking. Accordingly, the entanglement of the epoxy with the polyacrylate, the restraint of the epoxy, and the binder force of the network structure with the epoxy are limited to some extent, and it is easily predicted that they are not so strong. In other words, it can be inferred that the IPN effect that should be originally expected is diminished only by the movement of the polyacrylate if it is dragged.

The polyacrylate may be bonded with a specific functional group, carboxylic acid, or hydroxyl group that the epoxy and the polyacrylate have. When the functional group possessed by the polyacrylate is a carboxylic acid, a reaction with the epoxy group possessed by the epoxy resin occurs, the gelation that does not depend on the original cationic polymerization reaction of the adhesive proceeds, and the storage stability of the adhesive is improved. In addition to the deterioration, there is a concern that mechanical strength and adhesive strength are lowered because sufficient polymerization is inhibited. When the functional group of the polyacrylate is a hydroxyl group, when the adhesive is cured by cationic polymerization, it acts as a chain transfer agent and the apparent curing rate and cross-linking are promoted, but the degree of polymerization is reduced and the adhesive There is a concern that the material becomes brittle and does not function as a structural adhesive.
JP-A-63-215716 JP-T-2005-508435

  The present invention provides an adhesive composition comprising an acrylic resin having a number average molecular weight that exhibits sufficient mechanical strength, an epoxy resin, and a curing agent.

  The inventors of the present invention are sufficiently mechanical by using an adhesive composition composed of an acrylic resin having a number average molecular weight of 2 to 500,000 having a repeating unit represented by the following structural formula in the molecule, an epoxy resin, and a curing agent. It has been found that it becomes an adhesive exhibiting strength.

(However, R represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 to 10.)

  Adhesives using the adhesive composition of the present invention include metals such as iron, aluminum, copper, magnesium, titanium, and alloys thereof, polyester resins, acrylic resins, polycarbonate resins, polyphenylene sulfide resins, polypropylene alloys, polyethylene, and the like. It can be applied to a wide range of base materials such as plastics, inorganic materials such as glass, mortar and quartz.

  The adhesive using the adhesive composition of the present invention can be suitably applied particularly to plastics reinforced with carbon fiber or glass fiber. Furthermore, when bonding carbon fiber reinforced plastics to metals that are more likely to become ions in the electrolyte solution than carbon fibers, such as bonding carbon fiber reinforced plastics and aluminum alloys, it is natural to show strong adhesion. However, it suppresses the production of batteries and prevents metal corrosion, and maintains and exerts strong adhesion even in an electrolyte solution such as water or salt water.

  Although the adhesive using the composition of the present invention can be used as a two-component mixed type, it is basically a one-component adhesive and achieves both good storage stability and curing characteristics. .

  The present invention is an adhesive composition comprising an acrylic resin having a number average molecular weight of 2 to 500,000 having an repeating unit represented by the following structural formula in the molecule, an epoxy resin, and a curing agent.

(However, R represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 to 10.)
The repeating unit represented by the following structural formula (1) (hereinafter also referred to as VBGE unit)

(However, R represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 to 10.)
In the present invention, a very important and useful function and action are exhibited. That is, the VBGE unit acts as a cross-linking point between acrylic resin chains (hereinafter also referred to as an acrylic polymer network), and the acrylic resin and the epoxy resin form an interpenetrating polymer network structure (hereinafter also referred to as IPN) when cured. In addition, it has a strong tendency to promote the strong entanglement between the acrylic polymer chain and the epoxy polymer chain and improve the mechanical strength, toughness, and impact resistance of the adhesive, and is useful as an adhesive, especially as a structural adhesive. Increase. Furthermore, the VBGE unit acts as a grafting point between the acrylic resin and the epoxy resin when the adhesive is cured, providing moderate compatibility and incompatibility between the acrylic resin and the epoxy resin. Resin and epoxy resin are integrated to provide a structural adhesive with high mechanical strength and adhesive strength. Furthermore, moderate compatibility enhances the transparency of the adhesive and enables applicability to optical coatings.

  Even more surprisingly, the VBGE unit dramatically improves the dispersibility and dispersion stability of the filler, enables nano-dispersion of nano-size functional fillers such as montmorillonite, and the mechanical strength of the adhesive, It has the effect of improving heat resistance, moist heat resistance, water resistance and the like.

  In the present invention, the acrylic resin having a number average molecular weight of 2 to 500,000 having a repeating unit represented by the following structural formula in the molecule,

(However, R represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 to 10.)
Preferably, it can manufacture by radical copolymerizing the monomer shown with the following structural formula with an acrylic monomer.

(However, R represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 to 10.)
Examples of the monomer represented by the above structural formula (hereinafter also referred to as VBGE) include m-vinyl benzyl glycidyl ether, p-vinyl benzyl glycidyl ether, p-vinyl benzyl butyl glycidyl ether, and the like. These monomers may be used alone or as a mixture of two or more.

  The VBGE unit can be preferably introduced by copolymerizing VBGE with an acrylic monomer. In order to introduce the VBGE unit, VBGE is preferably copolymerized in the acrylic resin in an amount of 0.02 to 50% by weight, more preferably 0.2 to 30% by weight, and even more preferably 0.2 to 25% by weight. desirable. When the copolymerization amount of VBGE is less than 0.02% by weight, the network between acrylic polymers and the grafting with the epoxy resin tend to decrease, and the mechanical strength and adhesive strength of the adhesive are slightly insufficient. The case is seen. When VBGE is copolymerized in excess of 50% by weight, there is a tendency that curing strain tends to remain in the adhesive when the adhesive is cured, and cracking or sinking of the adhesive may be observed.

  In the adhesive composition of the present invention, the acrylic resin has a number average molecular weight (hereinafter also referred to as Mn) of 2 to 500,000, preferably 5 to 300,000, more preferably 8 to 250,000, and still more preferably. Is recommended to be 8.5 to 255,000.

  In the present invention, the molecular weight of the acrylic resin is determined by gel permeation chromatography (GPC) (for example, “HLC-8220 GPC” system manufactured by Tosoh Corporation), and a polystyrene standard (for example, GL Science) having a defined molecular weight. Standard POLYSTYRENE) was measured as a molecular weight standard.

  When the number average molecular weight Mn of the acrylic resin is less than 20,000, it is caused by insufficient entanglement of the molecular chain, and for example, a sharp decrease in the adhesive force when used at a relatively high temperature such as 80 ° C. or higher is observed. In addition, mechanical properties such as impact resistance are not sufficiently exhibited, and problems such as deterioration of adhesive strength after an impact test are observed. When the number average molecular weight Mn of the acrylic resin exceeds 500,000, the entropy elasticity of the adhesive becomes too strong, and there is a tendency for the familiarity, adherence, and permeability to adherends to deteriorate, and the adhesive strength Decreases.

  It is extremely important to optimally control the Mn of the acrylic resin, either by blending an acrylic resin whose Mn is not controlled to achieve IPN, or by diluting with an acrylic monomer and then polymerizing the acrylic monomer. Functions and properties that are completely different from those of IPN techniques are expressed.

  In the present invention, the best number average molecular weight Mn range of the acrylic resin is 85 to 225,000. If the number average molecular weight Mn is 2 to 500,000, most preferably 8.5 to 225,000, the optimal entanglement of the acrylic resin is realized, and the rheology of the adhesive is controlled within an appropriate thixotropic range. There is a trend. As a result, not only the application workability of the adhesive but also the wettability and familiarity with the adherend are greatly improved, and the adhesive strength tends to be dramatically improved. In extreme cases, it may be possible to join the adherend surfaces contaminated with oil or water. Moreover, the expression of the optimal entangled structure improves the mechanical strength of the adhesive, making it possible to produce adhesives and adhesive articles that are tough and excellent in impact resistance, water resistance, heat resistance, and the like.

  In the present invention, the acrylic resin imparts appropriate tackiness to the adhesive, changes the adhesion to a stronger one, and imparts impact resistance to the adhesive. ) Is preferably −80 to 50 ° C., more preferably −55 to 40 ° C., and further preferably −55 to 30 ° C.

In the present invention, the glass transition temperature of the acrylic resin is in accordance with the method (p15-p27) described in the book “Mechanical Properties of Polymer” (JENIELSEN, translated by Shigeharu Onoki, Kagaku Dojin (1975)). Calculated. That is,
1 / Tg = Σ (wi / Tgi)
(Here, Tg represents the Tg of the acrylic resin (absolute temperature K), Wi represents the copolymerization amount (weight fraction) of the i monomer, and Tgi represents the glass transition temperature of the homopolymer prepared from the i monomer. .)
Calculated by In addition, the Tg of the homopolymer prepared from the monomer to be copolymerized is the value described in the above-mentioned document “Mechanical properties of polymer” and acrylic monomer manufacturers (for example, Mitsubishi Rayon, Toagosei, The values described in the catalog of Nippon Shokubai Co., Ltd., Nippon Oil & Fats, etc.) were adopted and used.

  In this invention, when Tg of acrylic resin is less than -80 degreeC, the tendency for an adhesive agent to be plasticized too much is seen, and the case where sufficient adhesive strength is not obtained is seen. When the Tg of the acrylic resin exceeds 50 ° C., the viscosity of the acrylic resin increases, so it is necessary to keep the molecular weight of the acrylic resin low from the viewpoint of coating workability. As a result, the impact resistance of the adhesive tends to deteriorate. Is seen.

  In the present invention, as other acrylic monomers constituting the acrylic resin, methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate , Stearyl acrylate, 2,2,2-trifluoroethyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate , Stearyl methacrylate, 2,2,2-trifluoroethyl methacrylate, acrylic acid, methacrylic acid, maleic acid, itaconic acid, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyrate , 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltri Examples include ethoxysilane. These acrylic acid monomers may be used alone or as a mixture of two or more.

  Among acrylic acid monomers, preferably cyclohexyl acrylate, isobornyl acrylate, dicyclopentanyloxy acrylate, dicyclopentanyloxyethyl acrylate, cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentanyloxy methacrylate, di- Cycloalkyl group-containing acrylic monomers such as cyclopentanyloxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxy methacrylate Hydroxyl-containing acrylic monomers such as propyl and 4-hydroxybutyl methacrylate, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysila , Γ-acryloyloxypropyltrimethoxysilane, γ-acryloyloxypropylethyldiethoxysilane and other alkoxysilane group-containing acrylic monomers are used to adhere to various adherends such as polyolefin, nylon, epoxy resin, glass and metal. Recommended for improvement, improvement, and to form an acrylic polymer network to increase the mechanical strength and impact resistance of the adhesive and develop stronger adhesive strength.

  In the adhesive composition of the present invention, the cycloalkyl group-containing acrylic monomer is a useful monomer for improving the adhesion to various adherends. In particular, when the cycloalkyl group-containing acrylic monomer is cyclohexyl acrylate, the adhesiveness of polyolefins such as polypropylene alloy and polyethylene tends to be improved, which is recommended. At the same time, the water resistance and chemical resistance of the adhesive tend to improve and improve. The cycloalkyl group-containing acrylic monomer is preferably copolymerized in the acrylic resin in an amount of preferably 2 to 99.98% by weight, more preferably 5 to 80% by weight, and even more preferably 5 to 60% by weight. When the copolymerization amount of the cycloalkyl group-containing acrylic monomer is less than 2% by weight, the adhesion of polyolefin tends to be slightly deteriorated. When the cycloalkyl group-containing acrylic monomer is copolymerized in an amount exceeding 99.98% by weight, the adhesive tends to become brittle, and the adhesive strength after impact resistance may decrease. is there.

  In the adhesive composition of the present invention, the alkoxysilane group-containing acrylic monomer functions functionally to form an acrylic polymer network. At the same time, since the acrylic polymer network is formed with siloxane bonds with strong bonding strength, the toughness, mechanical strength, heat resistance (maintaining adhesion when used at high temperatures), and chemical stability A trend of dramatic improvement is seen and recommended. The alkoxysilane group-containing acrylic monomer is preferably 0.2 to 20% by weight, more preferably 0.2 to 10% by weight, and still more preferably 0.5 to 8% by weight in the acrylic resin. Is desirable. When the copolymerization amount of the alkoxysilane group-containing acrylic monomer is less than 0.2% by weight, the formation of the acrylic polymer network is insufficient and a loosely crosslinked structure tends to result in a slight deterioration in adhesive strength and heat resistance. It can be seen. When the copolymerization amount of the alkoxysilane group-containing acrylic monomer exceeds 20% by weight, when the adhesive is designed as a one-pack type, the storage stability of the adhesive tends to deteriorate. Also, when alcohol vapors such as methanol and ethanol generated by hydrolysis of alkoxysilane and siloxane cross-linking cause bubbles to be included in the adhesive and the adhesive becomes brittle, or cracks occur in the adhesive layer due to the generated gas Is seen.

  In the adhesive composition of the present invention, the hydroxyl group-containing acrylic monomer can easily and efficiently advance the formation of an acrylic polymer network by further adding a polyisocyanate compound such as hexamethylene diisocyanate or isophorone diisocyanate to the adhesive. be able to. In particular, this is a useful means when the adhesive is used in the form of a scissor sheet in a protective and re-peelable film. The acrylic resin forms an acrylic polymer network at the stage of forming the adhesive film, and changes to a high-strength, reworkable pressure-sensitive adhesive in combination with the high molecular weight of the acrylic resin. By using this adhesive film, it is possible to re-attach (rework) to the adherend, and the epoxy resin is cured by heating or light irradiation, so that a sheet-like adhesive having good workability can be produced. The hydroxyl group-containing acrylic monomer is preferably copolymerized in the acrylic resin, preferably 2 to 20% by weight, more preferably 3 to 18% by weight, and still more preferably 3 to 12% by weight. When the copolymerization amount of the hydroxyl group-containing acrylic monomer is less than 2% by weight, the formation of the acrylic polymer network may be slightly insufficient, and the mechanical strength of the adhesive may be insufficient. When the copolymerization amount of the hydroxyl group-containing acrylic monomer exceeds 20% by weight, the crosslink density of the acrylic resin becomes too high and the adhesive becomes brittle when reacted with an equivalent ratio with the polyisocyanate compound. There is a tendency for the strength to deteriorate. When the blending amount of the polyisocyanate compound is equal to or less than the equivalence ratio, a large number of hydroxyl groups of the acrylic resin remain unreacted, and the water resistance and wet heat resistance of the adhesive tend to deteriorate.

  In the adhesive composition of the present invention, the acrylic resin is preferably produced by radical copolymerization, and is produced by any polymerization method such as bulk polymerization, suspension polymerization, dispersion polymerization, precipitation polymerization, solution polymerization, and emulsion polymerization. Can also achieve the purpose.

  In consideration of the post-process using the produced polymer, it is desirable to carry out in a solvent-free or non-aqueous solvent system such as bulk polymerization, dispersion polymerization, precipitation polymerization, and solution polymerization.

  The acrylic resin is preferably produced in a polymerization system substituted with an inert gas such as nitrogen gas, argon gas or helium gas. At this time, the oxygen concentration of the polymerization system is preferably 5 vol% or less, more preferably 2 vol% or less, and still more preferably 0.5 vol% or less. When the oxygen concentration in the polymerization system exceeds 5 vol%, the radical polymerization reaction is influenced by the oxygen in the system and may not proceed sufficiently. That is, the polymerization rate is remarkably slow, and a polymer having a low degree of polymerization may be generated due to telomerization due to oxygen, and there is a tendency that the acrylic resin is colored or the water resistance of the adhesive is lowered.

  The acrylic resin is preferably produced at a polymerization temperature of preferably 50 to 150 ° C, more preferably 60 to 140 ° C. When the polymerization temperature is less than 50 ° C., the polymerization rate is difficult to increase, and the production may take a very long time. A further concern is that the heat resistance of the produced polymer may be degraded. When the polymerization is carried out at a temperature exceeding 150 ° C., the stability of the polymer terminal radical tends to be lowered, and it may be difficult to produce a polymer having a desired molecular weight and molecular weight distribution.

  Examples of the organic solvent that can be used as a solvent in the solution polymerization include toluene, xylene, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, amyl acetate, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n- Butyl alcohol, t-butyl alcohol, cyclohexanone, cyclohexane, hexane, heptane, methylcyclohexane, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, Examples include tripropylene glycol and 1,4-butanediol. These organic solvents may be used alone or as a mixture of two or more.

  Among these solvents, chain transfer such as ethyl acetate and n-propyl acetate is necessary in order to prevent coloration of the polymer and deterioration of heat resistance, and when solvent removal is required when producing an adhesive. Small constants are recommended.

  In the present invention, the acrylic resin is preferably prepared by radical copolymerization of an acrylic monomer containing VBGE in the presence of a hindered amine compound and an organic peroxide. More preferably, it is preferably produced by radical copolymerization of an acrylic monomer containing VBGE in the presence of a reaction product of a hindered amine compound and an organic peroxide.

  When the acrylic resin produced by this production method is used, the molecular weight distribution of the acrylic resin is narrowed despite the fact that it is produced by radical copolymerization, the rheology control of the adhesive is easy and optimized, and the coating workability is improved. There is a strong tendency not only to improve, but also to improve the wettability and permeability to the adherend and to improve the toughness, mechanical strength, heat resistance and adhesive strength of the adhesive.

  Examples of hindered amine compounds include 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, and bis (1,2,2,6). , 6-pentamethyl-4-piperidyl) sebacate, 3-dodecyl-1- (2,2,6,6-tetramethyl-4-piperidinyl) pyrrolidine-2,5-dione, N-methyl-3-dodecyl-1 -(2,2,6,6-tetramethyl-4-piperidinyl) pyrrolidine-2,5-dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, N-methyl-4-benzoyloxy Examples include -2,2,6,6-tetramethylpiperidine. The hindered amine compound may be used alone or as a mixture of two or more.

  Examples of organic peroxides include benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxybenzoate, cumene hydroperoxide, t-butyl hydroperoxide, and dicumyl peroxide. Is done. The organic peroxide may be used alone or as a mixture of two or more.

The hindered amine compound and the organic peroxide are preferably 1 × 10 ⁻⁴ mol to 2.5 mol, more preferably 5 × 10 ⁻⁴ mol to 2.0 mol per mol of the hindered amine compound. Used in mole ratios.

When the amount of the organic peroxide used is less than 1 × 10 ⁻⁴ mol relative to 1 mol of the hindered amine compound, the polymerization rate is hardly increased, the polymerization efficiency tends to be poor, and only a small molecular weight tends to be produced. is there.

  When the amount of the organic peroxide used exceeds 2.5 moles with respect to 1 mole of the hindered amine compound, the living property of the polymerization is lost, and a low molecular weight polymer tends to be produced in a large proportion. There is a tendency for the molecular weight distribution of the acrylic resin to spread.

  The hindered amine compound is preferably 0.002 to 20.0% by weight, more preferably 0.005 to 15.0% by weight, and still more preferably 0.02 to 100% by weight of the acrylic monomer containing VBGE. It is desirable to use 12.0% by weight.

  When the amount of the hindered amine compound used is less than 0.002% by weight based on 100 parts by weight of the acrylic monomer containing VBGE, the polymerization rate is difficult to increase, and the polymerization requires a long time and the practicality is lost. There is a tendency.

  When the amount of the hindered amine compound used exceeds 20.0% by weight based on 100 parts by weight of the acryl monomer containing VBGE, the polymer may be colored, which is a practical problem. There is a case.

  The reaction product of the hindered amine compound and the organic peroxide is, for example, mixed with the hindered amine compound and the organic peroxide in a container substituted with an inert gas such as nitrogen gas or helium gas, and raised to a predetermined polymerization temperature. It can be manufactured simply by heating.

  Below, an example of the preferable aspect of acrylic resin manufacture is shown. Of course, it goes without saying that the present invention is not limited to this.

  A polymerization solvent (for example, a mixed solvent of ethyl acetate / n-propyl acetate (80/20 weight ratio)) is charged into a flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas is introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask is measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it is confirmed that the oxygen concentration is less than 0.5 vol%.

  While continuing the bubbling of nitrogen gas, a predetermined amount of a hindered amine compound such as 4-benzoyloxy-2,2,6,6-tetramethylpiperidine is charged into a flask and dissolved uniformly. If dissolution is possible, an organic peroxide such as benzoyl peroxide is charged in an equimolar amount with the hindered amine compound and stirring is continued.

  The temperature rise is started, the temperature is raised to 80 ° C. in 30 minutes, and the temperature is kept at 80 ° C. below.

  Monomers such as 2-ethylhexyl methacrylate / n-butyl acrylate / p-vinylbenzylglycidyl ether / γ-methacryloyloxypropyltriethoxysilane / γ-acryloyloxypropyltrimethoxysilane (= 20/78/1 / 0.5) /0.5 weight ratio) of the mixed monomer is dropped into the flask in 2 hours, sampling is performed immediately after completion of the dropping, and the number average molecular weight and the polymerization rate are measured. When the polymerization rate reaches 100%, the polymerization is terminated and cooling is started.

  By the above, the acrylic resin preferably used by this invention can be manufactured.

Examples of the epoxy resin as the second component of the present invention include bisphenol A type epoxy resin, novolak type epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, brominated epoxy resin, aliphatic epoxy resin, etc. Are exemplified by compounds having at least one epoxy group, and these epoxy resins may be used alone or as a mixture of two or more. (Reference: “14705 Chemical Products (issued in 2005)” (Chemical Industry Daily, p1126 to p1135)
In the present invention, among these epoxy resins, aromatic epoxy resins such as bisphenol A type epoxy resins or alicyclic epoxy resins are used in terms of storage stability, curability and adhesive strength of the adhesive. Desirable and recommended. When an aromatic epoxy resin such as a bisphenol A type epoxy resin is used, the curing temperature tends to be slightly higher (approximately 80 to 150 ° C.), and the curing time tends to be slightly longer (approximately 10 to 120 minutes). However, the storage stability of the adhesive is excellent, and it is often possible to design a one-component adhesive. When an alicyclic epoxy resin is used, it is possible to design an adhesive that exhibits fast curability (about 1 minute to 120 minutes) at a relatively low temperature (about 60 to 120 ° C.). (Pot life is about 1 week at 23 ° C./200 g scale of adhesive), it is desirable to design as a two-component type. In any case where an aromatic epoxy resin such as a bisphenol A type epoxy resin or an alicyclic epoxy resin is used, there is little shrinkage (linear expansion coefficient, volume expansion coefficient) when the adhesive is cured. There is a tendency to avoid problems such as adhesion failure to a minimum.

  In the present invention, the total amount of the epoxy resin and the acrylic resin is 100 parts by weight, and the epoxy resin is preferably 5 to 98% by weight, more preferably 10 to 85% by weight, and still more preferably 20 to 80% by weight. Is desirable. When the blending amount of the epoxy resin is less than 5% by weight, there are cases where the crosslinking ratio of the adhesive with the epoxy resin is low, and the adhesive strength and the mechanical properties of the adhesive cannot be obtained. When the amount of the epoxy resin exceeds 98% by weight, the high molecular weight of the acrylic resin, high toughness, and the acrylic polymer network function for IPN are not fully utilized, and the adhesive tends to become brittle. And mechanical strength and adhesive strength may be insufficient.

  In this invention, after mix | blending an acrylic resin and an epoxy resin in a predetermined ratio, the hardening | curing agent for bridge | crosslinking this is mix | blended.

  Curing agents include phenyldimethylurea, diethylene glycol bis (3-aminopropyl) ether, cyanoguanidine, aminoethylpiperazine, N, N-dimethyl-1,3-propanediamine, and tris (N, N-dimethylaminomethyl) phenol. And amines such as hexahydrophthalic anhydride and trimellitic acid, phenols and acid anhydrides. These curing agents may be used alone or as a mixture of two or more.

  In the present invention, an imidazole compound or an aromatic sulfonium salt having a specific structure is preferably recommended as the curing agent.

  Examples of the imidazole compound preferably used as a curing agent in the present invention include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl- Examples include 4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole and the like. These imidazole compounds may be used alone or as a mixture of two or more.

  As a sulfonium salt compound more preferably used as a curing agent in the present invention,

(However, R1, R2, and R3 represent an alkyl group having 1 to 12 carbon atoms.)

(However, R1, R2, and R3 represent an alkyl group having 1 to 12 carbon atoms.),
Examples include hexafluoroantimony salt of p-methylphenyl-dimethyl-sulfonium, hexafluoroantimony salt of p-ethylphenyl-dimethyl-sulfonium, hexafluorophosphate salt of methylphenyl-dimethyl-sulfonium, and the like. These sulfonium salts may be used alone or as a mixture of two or more.

  These curing agents tend to function functionally in balancing the storage stability of the adhesive, pot life and curing properties. As a result, as a one-pack type, it exhibits long-term storage stability in a low to medium temperature range (about -20 to 40 ° C), and exhibits stable and good curing characteristics in a medium to high temperature range (about 80 to 150 ° C). There is a trend.

  These curing agents are preferably added in an amount of 0.2 to 10 phr, more preferably 0.5 to 8 phr, and still more preferably 1 to 6 phr with respect to the total amount of the acrylic resin and the epoxy resin. When the amount of the curing agent is less than 0.2 phr, the storage stability is drastically improved, but the curability tends to be extremely deteriorated, and the mechanical strength and adhesive strength of the adhesive are lowered. The case is seen. When the blending amount of the curing agent exceeds 10 phr, the storage stability tends to deteriorate, and the pot life adjustment may be difficult. Furthermore, since hardening progresses rapidly at the time of hardening, the big distortion is produced in an adhesive agent and the tendency for adhesiveness to deteriorate is seen.

  When a crosslinking reaction is carried out using these curing agents, the epoxy resin in the adhesive composition and the epoxy group mainly form a network with an ether bond, so that it has excellent water resistance and chemical resistance. There is a tendency to become.

  The adhesive composition of the present invention can be produced by mixing an acrylic resin, an epoxy resin, and a curing agent.

  As an example of production, an acrylic resin produced by solution polymerization is charged into a planetary mixer capable of vacuum desolvation, and a predetermined amount of an epoxy resin is charged therein, followed by stirring and mixing. Thereafter, the solvent is removed from the adhesive under vacuum. A predetermined amount of a curing agent is charged into this, and further stirred and mixed to produce an adhesive.

The adhesive composition of the present invention is desirably a thixotropic fluid at a shear rate of 10 ⁰ s ⁻¹ to a shear rate of 10 ³ s ⁻¹ . Here, the thixotropic fluid referred to in the present invention refers to a fluid having a thixotropic flow. The thixotropic flow is described in detail in the book “World of Rheology” (written by Kunihiro Ozaki, Industrial Research Committee (issued in 2004), p114), and refers to a decrease in fluid viscosity due to stirring and vibration. That is, it indicates a decrease in fluid viscosity due to an increase in stirring, vibration, shear rate and the like. When the adhesive has an appropriate thixotropy, when applying the adhesive to an adherend, the dripping and flow of the adhesive can be suppressed, and an appropriate and relatively uniform film thickness can be easily obtained. it can. In addition, moderate thixotropy promotes and improves the smoothness, familiarity, and permeability of the adherend to the adherend, and even if the adherend has a complicated shape, it adheres due to self-structuring. There exists an effect | action which suppresses the space | gap between an agent and a to-be-adhered body to the minimum, and the tendency for the function which improves and improves an adhesive force is expressed.

  The rheological measurement for judging the thixotropy of the adhesive was performed at 25 ° C. using a “VAR-type visco analyzer” manufactured by Jusco International. The measurement conditions are as follows.

[Rheology measurement conditions]
Manual measurement once, measurement interval 2.000E4 + 0 s
Shear rate table Shear rate 1.000E + 0 − 1.000E + 3 1 / s
Delay time 1.015E + 0-1.6000E + 1 s
Integration time 1.030E + 0 − 3.100E + 1 s.

  Strictly specifying the rheology of the adhesive, especially the flow properties, is a very important requirement in designing self-leveling and self-structuring of the adhesive, rather than simply providing thixotropy and ensuring adhesive film thickness. It is.

  As a result of intensive studies, the present inventors have made the adhesive preferably an appropriate thixotropic fluid, so that the adhesive exhibits self-leveling and self-structuring functions, and the base material to which the adhesive is applied is applied. It has been found that it can self-penetrate into scratches, irregularities, etc., and smoothen it to improve the adhesion.

  The rheology of paints, pressure-sensitive adhesives, and adhesives is generally evaluated, considered, and judged by analog based on a graph of measurement results. If this is intentionally digitized, in the present invention, the thixotropic flow of the adhesive can also be expressed by the relationship described below.

That is, if the viscosity when the shear rate is 5.5 ± 0.5 s ⁻¹ is Pa and the viscosity when the shear rate is 550 ± 50 s ⁻¹ is Pb, the relationship between Pa and Pb is Pa The value of / Pb is preferably 1.02 to 10.0, more preferably 1.05 to 8.0, and still more preferably 1.10 to 6.5, and the best relationship between Pa and Pb Is 1.23-6.0. When the value of Pa / Pb is less than 1.005, the self-leveling property of the adhesive and the self-structure forming ability are insufficient, so that an adhesive with high permeability may not be obtained. When it is a kimono, there are cases where a stable adhesive strength cannot be obtained. When the value of Pa / Pb exceeds 10.0, the thixotropy of the adhesive is too strong, and it may be difficult to apply uniformly in the pressure-sensitive adhesive application process. There is a tendency that the film cannot be completely covered, and the adhesive strength is somewhat deteriorated. In particular, in immersion tests such as water resistance, water may enter the gap between the adhesive and the adherend, resulting in adhesion failure.

  In addition to acrylic resin, epoxy resin, and curing agent, the adhesive composition of the present invention includes talc, bentonite, montmorillonite, calcium carbonate, zinc oxide, silica stone powder, glass powder, mica, potassium titanate whisker, glass wool, carbon Reinforcing fibers, fillers, silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 3,4-epoxycyclohexylpropyltriethoxysilane, etc. be able to.

  The adhesive composition of the present invention can be applied to an adherend in a liquid state and cured by heating to obtain an adhesive article. In addition, the adhesive is applied on a peelable protective film, heated at an appropriate temperature, preferably 60 to 120 ° C. for an appropriate time, preferably 30 seconds to 10 minutes, and after passing through the B stage, Can be heat-cured and then bonded to the adherend.

  Adhesives using the adhesive composition of the present invention are used as (structure) adhesives for automobiles, motorcycles and bicycle parts, as leisure adhesives for golf clubs, fishing rods, etc., and as structural adhesives for ships and aircraft. In addition, the present invention is suitably applied to applications requiring chemical strength such as adhesive strength, adhesive mechanical properties, toughness, and water resistance.

  Furthermore, as an adhesive for electronic information equipment such as optical filters for display and flat panel displays (FPD), electromagnetic shielding films, etc., taking advantage of its excellent functions such as high transparency, low haze, and adhesive permeability, Preferably used.

  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. The molecular weight was measured by GPC using standard polystyrene as the molecular weight standard. The heating residue was measured according to JIS K 5400-1997.

  The rheology of the adhesive was measured at 25 ° C. using a “VAR Visco Analyzer” manufactured by Jusco International. The measurement conditions are as follows.

[Rheology measurement conditions]
Manual measurement once, measurement interval 2.000E4 + 0 s
Shear rate table Shear rate 1.000E + 0 − 1.000E + 3 1 / s
Delay time 1.015E + 0-1.6000E + 1 s
Integration time 1.030E + 0 − 3.100E + 1 s.
By this measurement, the viscosity Pa when the shear rate is 5.5 ± 0.5 s ⁻¹ and the viscosity Pb when the shear rate is 550 ± 50 s ⁻¹ were obtained.

  The tensile test of the adhesive was performed according to JIS K 7113-1995 (plastic tensile test method). The pulling speed is 300 mm / min. It was.

  The adhesion test uses an A-2017P aluminum plate (size: length 50 mm, width 25 mm, thickness 2 mm), and conforms to JIS K 6850-1999 (Tensile Shear Adhesive Strength Test Method). went. The pulling speed is 1.0 mm / min. The test temperature was 23 ° C. unless otherwise specified.

[Production example of acrylic resin]
[Manufacture of acrylic resin (1)]
400 g of ethyl acetate / n-propyl acetate (= 50/50) was charged as a polymerization solvent into 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%.

  While the bubbling of nitrogen gas was continued, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was charged to the flask in an amount of 0.4% by weight of the mixed monomer, and dissolved uniformly. If dissolution is possible, benzoyl peroxide is charged in an equimolar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and the temperature rise is started. The temperature was raised to 80 ° C. in 30 minutes, and then the temperature was maintained at 80 ° C.

  400 g of a mixed monomer of 2-ethylhexyl methacrylate / n-butyl acrylate / p-vinylbenzyl glycidyl ether (= 10/85/5) was dropped into the flask in 2 hours, and after polymerization was completed for 2 hours. The acrylic resin (1) was produced by cooling to room temperature. FIG. 1 shows the polymerization behavior of the acrylic resin (1).

  It can be seen that the acrylic resin (1) is produced by living radical polymerization. The heating residue of the acrylic resin (1) was 50.2%, the number average molecular weight was 120,000, the molecular weight distribution was 1.8, and Tg was −48 ° C.

[Manufacture of acrylic resin (2)]
400 g of ethyl acetate / n-propyl acetate (= 50/50) was charged as a polymerization solvent into 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%.

  While the bubbling of nitrogen gas was continued, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was charged to the flask in an amount of 0.4% by weight of the mixed monomer, and dissolved uniformly. If dissolution is possible, benzoyl peroxide is charged in an equimolar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and the temperature rise is started. The temperature was raised to 80 ° C. in 30 minutes, and then the temperature was maintained at 80 ° C.

  After 400 g of a mixed monomer of cyclohexyl acrylate / n-butyl acrylate / p-vinylbenzyl glycidyl ether (= 20/79/1) was dropped into the flask in 2 hours and polymerization was carried out for 1.5 hours after completion of the dropping. The acrylic resin (2) was produced by cooling to room temperature. FIG. 2 shows the polymerization behavior of the acrylic resin (2).

  It can be seen that the acrylic resin (2) is produced by living radical polymerization. The heating residue of the acrylic resin (2) was 50.3%, the number average molecular weight was 140,000, the molecular weight distribution was 1.5, and Tg was -41 ° C.

[Manufacture of acrylic resin (3)]
400 g of ethyl acetate / n-propyl acetate / trimethyl orthoacetate (= 50/49/1) was charged as a polymerization solvent into 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%.

  While the bubbling of nitrogen gas was continued, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was charged to the flask in an amount of 0.4% by weight of the mixed monomer, and dissolved uniformly. If dissolution is possible, benzoyl peroxide is charged in an equimolar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and the temperature rise is started. The temperature was raised to 80 ° C. in 30 minutes, and then the temperature was maintained at 80 ° C.

  400 g of a mixed monomer of cyclohexyl acrylate / acrylic acid n-butyl / p-vinylbenzylglycidyl ether / γ-methacryloyloxypropyltrimethoxysilane (= 20/74/1/5) was dropped into the flask over 2 hours, and dropped. After completion of the polymerization, polymerization was carried out for 1.5 hours, and then cooled to room temperature to produce an acrylic resin (3). FIG. 3 shows the polymerization behavior of the acrylic resin (3).

  It can be seen that the acrylic resin (3) is produced by living radical polymerization. The acrylic resin (3) had a heating residue of 50.1%, a number average molecular weight of 120,000, a molecular weight distribution of 1.5, and a Tg of -43 ° C.

[Manufacture of acrylic resin (4)]
400 g of ethyl acetate / n-propyl acetate (= 50/50) was charged as a polymerization solvent into 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%.

  While the bubbling of nitrogen gas was continued, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was charged to the flask in an amount of 0.2% by weight of the mixed monomer, and dissolved uniformly. If dissolution was possible, benzoyl peroxide was charged in an equimolar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and the temperature was increased. The temperature was raised to 80 ° C. in 30 minutes, and then the temperature was maintained at 80 ° C.

  400 g of a mixed monomer of cyclohexyl acrylate / acrylic acid n-butyl / p-vinylbenzylglycidyl ether / acrylic acid 4-hydroxybutyl (= 20/76/1/3) was dropped into the flask in 2 hours. After carrying out the polymerization for 1.5 hours, the mixture was cooled to room temperature to produce an acrylic resin (4). FIG. 4 shows the polymerization behavior of the acrylic resin (4).

  It can be seen that the acrylic resin (4) is produced by living radical polymerization. The heating residue of the acrylic resin (4) was 50.1%, the number average molecular weight was 220,000, the molecular weight distribution was 1.8, and Tg was −52 ° C.

[Manufacture of acrylic resin (5)]
400 g of ethyl acetate / n-propyl acetate (= 50/50) was charged as a polymerization solvent into 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%.

  While the bubbling of nitrogen gas was continued, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was charged to the flask in an amount of 0.4% by weight of the mixed monomer, and dissolved uniformly. If dissolution is possible, equimolar amounts of benzoyl peroxide and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine are charged, and the temperature rise is started. The temperature was raised to 80 ° C. in 30 minutes, and then the temperature was maintained at 80 ° C.

  400 g of a mixed monomer of 2-ethylhexyl methacrylate / n-butyl acrylate (= 10/90) was dropped into the flask in 2 hours. After completion of the dropping, polymerization was performed for 2 hours, followed by cooling to room temperature and acrylic resin ( 5) was produced. FIG. 5 shows the polymerization behavior of the acrylic resin (5).

  It can be seen that the acrylic resin (5) is produced by living radical polymerization. The heating residue of the acrylic resin (5) was 50.2%, the number average molecular weight was 120,000, the molecular weight distribution was 1.7, and Tg was −45 ° C.

[Example of filler dispersion]
[Production of Dispersion M-1]
A 200 ml glass beaker was charged with 89.5 g of ethyl acetate and 0.5 g of “Disparon DA-7300” (pigment dispersant manufactured by Enomoto Kasei) while stirring at 1000 m ⁻¹ using a disper (beaker inner diameter: stirring blade diameter = 50:40) 10 g of “Kunifil D36” (organized bentonite manufactured by Kunimine Industries) was gradually added. Thereafter, the mixture was stirred for 60 minutes to produce an organophilic montmorillonite dispersion M-1.

[Production of Dispersion M-2]
"Kunipia-F" was prepared by charging 89.5g of ethyl acetate and 0.5g of "Disparon DA-7300" into a 200ml glass beaker while stirring at 1000m ^-1 using a disper (beaker inner diameter: stirring blade diameter = 50:40). 10 g of (fine powder bentonite manufactured by Kunimine Kogyo) was gradually added. Then, it stirred for 60 minutes and manufactured the bentonite dispersion liquid M-2.

Example 1
A 5 L planetary mixer connected to a vacuum line provided with a solvent recovery trap was charged with 1.2 kg of acrylic resin (1) and 400 g of “jER 828” (bisphenol A type epoxy resin from Japan Epoxy Resin) and stirred. . (Acrylic resin / epoxy resin = 60/40) While stirring, the pressure was reduced to 1300 Pa, and the solvent contained in the adhesive was recovered in the trap. The evacuation was stopped when the adhesive in the planetary mixer reached a heating residue of 98% or more. To this was added 1 phr of “Sun Aid 80L” (a sulfonium salt cation curing catalyst manufactured by Sanshin Chemical Co., Ltd.), and stirring was continued for 30 minutes to produce an adhesive (1).

(Rheological evaluation of adhesives)
As a result of measuring the rheology of the adhesive, the viscosity Pa at a shear rate of 5.64 s ⁻¹ was 58 Pa · s, and the viscosity Pb at a shear rate of 549 s ⁻¹ was 55 Pa · s (Pa / Pb = 1.06).

(Adhesive tensile test)
The adhesive (1) was spread out in a sheet shape so as to have a film thickness of 2 mm, and was cured by heating at 120 ° C. for 1 hour. This cured adhesive film was cut with a No. 3 dumbbell and subjected to a tensile test.
The strength at break (hereinafter also referred to as TS) was 35 MPa, the elongation at break (hereinafter also referred to as ES) was 250%, and the adhesive had high toughness.

(Adhesive strength evaluation)
(1) Evaluation of initial adhesive strength Adhesive (1) was evenly applied to an aluminum plate (film thickness 100 μm, application area 25 mm × 25 mm), and another aluminum plate was pressure-bonded to the adhesive surface, and 1 at 120 ° C. Heat cured for hours. Shear adhesive strength (hereinafter also referred to as As) was measured using this test piece. The shear adhesive strength was 32 MPa, which was a sufficiently high value.

(2) Evaluation of adhesive strength after water resistance test The test piece prepared in (1) was immersed in warm water at 80 ° C. for 72 hours. Thereafter, the adhesion test was performed in the same manner as in (1). As a result, the shear adhesive strength was 30 MPa. In the water resistance test, good adhesiveness was exhibited without any decrease in adhesive strength.

Example 2
Adhesives (2) and (3) were produced in the same manner as in Example 1 except that the acrylic resin (1) in Example 1 was changed to acrylic resins (2) and (3), and the same tests were performed. The test results are shown in Table 1.

Example 3
A planetary mixer was charged with 1.6 kg of acrylic resin (4) and 400 g of “jER 828” and stirred. (Acrylic resin / epoxy resin = 80/20) Further, isophorone diisocyanate was added so that the NCO groups of the hydroxyl group / isophorone diisocyanate of the acrylic resin (4) were in an equimolar amount, and stirring was continued. 1 phr of “Sunade 80L” was added thereto, and stirring was further continued for 30 minutes to produce an adhesive (4). The viscosity Pa of the adhesive (4) at a shear rate of 5.64 s ⁻¹ was 14 Pa · s, and the viscosity Pb at a shear rate of 549 s ⁻¹ was 12 Pa · s (Pa / Pb = 1.17).

  The adhesive (4) was applied to a release film “Therapy WD # 50” (release film manufactured by Toray Film Processing Co., Ltd.) so as to have a film thickness of 50 μm, and precured at 100 ° C. for 1 minute. Furthermore, “Therapy WD # 50” was bonded to the adhesive surface to produce a B-staged adhesive film. The adhesive film was cured at 23 ° C. for 1 week.

(Adhesive strength evaluation)
(1) Evaluation of initial adhesive force The release film of the produced adhesive film was peeled off and pressed onto an aluminum plate with a load of 500 g, and the release film on the surface was further peeled off, and the aluminum plate was pressed onto the adhesive surface with a load of 500 g. This was heat-cured at 120 ° C. for 1 hour. Shear adhesive strength (hereinafter also referred to as As) was measured using this test piece. The shear adhesive force was 38 MPa, showing a sufficiently high value.

  (2) Evaluation of adhesive strength after water resistance test The test piece prepared in (1) was immersed in warm water at 80 ° C. for 72 hours. Thereafter, the adhesion test was performed in the same manner as in (1). As a result, the shear adhesive strength was 38 MPa. In the water resistance test, good adhesiveness was exhibited without any decrease in adhesive strength.

Example 4
A 5 L planetary mixer connected to a vacuum line provided with a solvent recovery trap was charged with 1.4 kg of acrylic resin (3) and 300 g of “jER 828” and stirred. (Acrylic resin / epoxy resin = 70/30) While stirring, the pressure was reduced to 1300 Pa, and the solvent contained in the adhesive was recovered in the trap. The evacuation was stopped when the adhesive in the planetary mixer reached a heating residue of 98% or more. To this was added 1.0 phr of “Sunade 80L”, and stirring was further continued for 30 minutes to produce an adhesive (5).

  The adhesive (5) was tested in the same manner as in Example 1. The test results are shown in Table 2.

Example 5
A 5 L planetary mixer connected to a vacuum line provided with a solvent recovery trap was charged with 1.4 kg of acrylic resin (3) and 300 g of “ERL-4221” (an alicyclic epoxy resin manufactured by Union Carbide), and stirred. It was. (Acrylic resin / epoxy resin = 70/30) While stirring, the pressure was reduced to 1300 Pa, and the solvent contained in the adhesive was recovered in the trap. The evacuation was stopped when the adhesive in the planetary mixer reached a heating residue of 98% or more. To this, 1.0 phr of “Sunade 80L” was added, and stirring was further continued for 30 minutes to produce an adhesive (6).

  The test for the adhesive (6) was performed in the same manner as in Example 1 except that the curing of the adhesive was set at 80 ° C. for 60 minutes. The test results are shown in Table 2.

Example 6
A 5 L planetary mixer connected to a vacuum line provided with a solvent recovery trap was charged with 1.4 kg of acrylic resin (3) and 300 g of “jER 828” and stirred. (Acrylic resin / epoxy resin = 70/30) Further, the filler dispersion M-1 was charged so that the filler concentration was 3 phr of the adhesive, and the pressure was reduced to 1300 Pa while stirring, and the solvent contained in the adhesive was removed. It was collected in the trap. The evacuation was stopped when the adhesive in the planetary mixer reached a heating residue of 98% or more. To this was added 3.0 phr of “Curazole 2E4MZ” (an imidazole compound manufactured by Shikoku Kasei), and the mixture was stirred until it was uniformly dissolved, and stirring was further continued for 30 minutes to produce an adhesive (7).

  The adhesive agent (7) was tested in the same manner as in Example 1. The test results are shown in Table 2.

Example 7
A 5 L planetary mixer connected to a vacuum line provided with a solvent recovery trap was charged with 1.4 kg of acrylic resin (3) and 300 g of “jER 828” and stirred. (Acrylic resin / epoxy resin = 70/30) The filler dispersion M-2 was further charged so that the filler concentration was 3 phr of the adhesive, and the pressure was reduced to 1300 Pa while stirring, and the solvent contained in the adhesive was removed. It was collected in the trap. The evacuation was stopped when the adhesive in the planetary mixer reached a heating residue of 98% or more. To this, 1.0 phr of “Sunade 80L” was added, and stirring was further continued for 30 minutes to produce an adhesive (8).

  The adhesive (8) was tested in the same manner as in Example 1. The test results are shown in Table 2.

  Further, the test pieces prepared using the adhesive (5) and the adhesive (7) were stored at 80 ° C. for 72 hours, and then subjected to a shear adhesion test at 23 ° C. and 80 ° C. The results are shown in Table 3.

  Both the adhesive (5) and the adhesive (7) were found to have excellent heat resistance with no decrease in adhesive strength when stored at 80 ° C. In particular, the adhesive (7) containing a small amount of filler (montmorillonite) was extremely excellent in heat resistance and expression of adhesiveness during heating.

Comparative Example 1
A 5 L planetary mixer connected to a vacuum line provided with a solvent recovery trap was charged with 1.2 kg of acrylic resin (5) and 400 g of “jER 828” and stirred. (Acrylic resin / epoxy resin = 60/40) While stirring, the pressure was reduced to 1300 Pa, and the solvent contained in the adhesive was recovered in the trap. The evacuation was stopped when the adhesive in the planetary mixer reached a heating residue of 98% or more. 1 phr of “Sunade 80L” was added thereto, and stirring was further continued for 30 minutes to produce an adhesive (9).

(Rheological evaluation of adhesives)
As a result of measuring the rheology of the adhesive, the viscosity Pa at a shear rate of 5.64 s ⁻¹ was 42 Pa · s, and the viscosity Pb at a shear rate of 549 s ⁻¹ was 40 Pa · s (Pa / Pb = 1.05).

(Adhesive tensile test)
The adhesive (9) was spread out in a sheet shape so as to have a film thickness of 2 mm and cured by heating at 120 ° C. for 1 hour. This cured adhesive film was cut with a No. 3 dumbbell and subjected to a tensile test.
TS was 18 MPa and ES was 350%, which was a flexible adhesive. Compared to Example 1 using the acrylic resin (1) copolymerized with p-vinylbenzylglycidyl ether, the breaking stress was greatly reduced.

(Adhesive strength evaluation)
(1) Evaluation of initial adhesive force Adhesive (9) was uniformly applied to an aluminum plate (film thickness 100 μm, application area 25 mm × 25 mm), and another aluminum plate was pressure-bonded to the adhesive surface, and 1 at 120 ° C. Heat cured for hours. Using this test piece, the shear adhesive strength (As) was measured. The shear adhesive strength (As) was 15 MPa, showing a relatively good value.

(2) Evaluation of adhesive strength after water resistance test The test piece prepared in (1) was immersed in warm water at 80 ° C. for 72 hours. After that, as a result of performing an adhesion test in the same manner as (1), it was found that the shear adhesion strength (As) was 2 MPa, the adhesion strength was greatly reduced in the water resistance test, and lacked practicality. Compared with Example 1 using the acrylic resin (1) copolymerized with p-vinylbenzylglycidyl ether, a decrease in the adhesive strength in the normal state was observed, and in particular, the adhesive strength after water resistance was extremely deteriorated.

Comparative Example 2
1.0 kg of acrylic resin (1) was charged into a 5 L planetary mixer connected to a vacuum line provided with a solvent recovery trap and stirred. (Epoxy resin was not blended) While stirring, the pressure was reduced to 1300 Pa, and the solvent contained in the adhesive was recovered in the trap. When the adhesive in the planetary mixer reached a heating residue of 98% or more, evacuation was stopped, and 1 phr of “Sun Aid 80L” was added, and stirring was continued for 30 minutes to produce an adhesive (10). .

(Rheological evaluation of adhesives)
As a result of measuring the rheology of the adhesive, the viscosity Pa at a shear rate of 5.64 s ⁻¹ was 35 Pa · s, and the viscosity Pb at a shear rate of 549 s ⁻¹ was 32 Pa · s (Pa / Pb = 1.09).

(Adhesive tensile test)
The adhesive (10) was spread in a sheet shape so as to have a film thickness of 2 mm, and was heated and cured at 120 ° C. for 1 hour. This cured adhesive film was cut with a No. 3 dumbbell and subjected to a tensile test.
TS was 12 MPa and ES was 420%, which was a very flexible adhesive. Compared to Example 1, the breaking strength (TS) was reduced to about 1/3, and the breaking elongation (ES) was about 1.7 times. It was very soft and when used in the drive unit, there was concern about power transmission.

(Adhesive strength evaluation)
(1) Evaluation of initial adhesive strength Adhesive (10) was uniformly applied to an aluminum plate (film thickness: 100 μm, application area: 25 mm × 25 mm), and another aluminum plate was pressure-bonded to the adhesive surface, and 1 at 120 ° C. Heat cured for hours. As was measured using this test piece. As was 22 MPa and showed a relatively good value. This is probably because the adhesive used was an acrylic resin (1) copolymerized with p-vinylbenzylglycidyl ether, but the As was reduced to about 70% compared to Example 1, and an impact was applied. As a result, there was a concern about the adhesiveness.

  (2) Evaluation of adhesive strength after water resistance test The test piece prepared in (1) was immersed in warm water at 80 ° C. for 72 hours. Then, as a result of conducting an adhesive test in the same manner as (1), the shear adhesive strength (As) was 15 MPa. Compared to Example 1, the absolute value was reduced to about half, which resulted in somewhat uneasy use for use under high temperature and high humidity.

  As can be seen in the examples and comparative examples, the adhesive composition of the present invention has excellent and balanced performance with respect to numerous requirements such as mechanical properties, adhesive performance, heat resistance, and water resistance of the adhesive. Demonstrate.

FIG. 1 is a diagram showing the polymerization behavior of the acrylic resin (1). FIG. 2 is a diagram showing the polymerization behavior of the acrylic resin (2). FIG. 3 is a diagram showing the polymerization behavior of the acrylic resin (3). FIG. 4 is a diagram showing the polymerization behavior of the acrylic resin (4). FIG. 5 is a diagram showing the polymerization behavior of the acrylic resin (5).

Claims (7)

An adhesive composition comprising an acrylic resin having a number average molecular weight of 2 to 500,000 having a repeating unit represented by the following structural formula in the molecule, an epoxy resin, and a curing agent.

(However, R represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 to 10.) The adhesive composition according to claim 1, wherein the adhesive is a thixotropic fluid at a shear rate of 10 ⁰ s ⁻¹ to a shear rate of 10 ³ s ⁻¹ .   The adhesive composition according to claim 1 or 2, wherein the acrylic resin is a copolymer of a cycloalkyl group-containing acrylic monomer.   The adhesive composition according to claim 3, wherein the cycloalkyl group-containing acrylic monomer is cyclohexyl acrylate.   The adhesive composition according to any one of claims 1 to 4, wherein the acrylic resin is further copolymerized with an alkoxysilane group-containing acrylic monomer or a hydroxyl group-containing acrylic monomer.   The adhesive composition according to claim 1, wherein the curing agent contains an imidazole compound. The adhesive composition according to any one of claims 1 to 5, wherein the curing agent comprises a thermal or photocationic polymerization initiator represented by the following structural formula (2) or (3).

(However, R1, R2, and R3 represent an alkyl group having 1 to 12 carbon atoms.)

(However, R1, R2, and R3 represent an alkyl group having 1 to 12 carbon atoms.)

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