JP6417195B2 - Acrylic sol composition - Google Patents

Description

  The present invention relates to an acrylic sol composition used as a sealing material.

  When a sealing material is used for a steel plate joint of an automobile, a sealing material that can be used without depending on the conditions of the line baking process and that can suppress air bulging is required. Therefore, conventionally, a sealing material capable of fixing a material by curing an ultraviolet resin by ultraviolet irradiation has been proposed (see, for example, Patent Documents 1 and 2). The technique of Patent Document 2 uses a thermal polymerization initiator that reacts with an ultraviolet curable resin by heat in order to cure the UV uncured portion by heat and ensure adhesion to an adherend such as a steel plate.

JP 2011-63637 A JP 2013-223838 A

  The UV curable sealing material is subjected to a baking process after the UV resin is cured by UV irradiation. In general, the baking process of an automobile coating line is appropriately set with baking conditions such as baking temperature, time, and heating rate, depending on the specifications of the coating, the conditions specific to the oven, and the relationship with components other than the sealing material. The

  In some cases, it is necessary to change the sealing material according to each condition, such as changing the composition of the sealing material in accordance with the difference in the baking conditions, and work for adjusting the composition of the sealing material composition has occurred each time.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an acrylic sol composition that can be suitably baked and cured regardless of baking conditions.

In order to solve the above-described problems, the acrylic sol composition according to the present invention includes an acrylic resin, a UV curable resin, a blocked isocyanate resin having a dissociation temperature of 110 to 125 ° C., 60 to 30% by mass, a dissociation temperature. An acrylic sol composition containing a blocked isocyanate resin containing 40 to 70 mass% of a blocked isocyanate resin at 85 to 95 ° C ,
The blocked isocyanate resin has a dissociation temperature of 110 to 125 ° C. with respect to 100 parts by mass of the acrylic resin 100 to 20 parts by mass, and the dissociation temperature of 85 to 95 ° C. with respect to the blocked isocyanate resin with the acrylic. It is an acrylic sol composition containing 20 to 100 parts by mass with respect to 100 parts by mass of the resin.

  The acrylic sol composition according to the present invention can be suitably baked and cured regardless of the baking conditions.

Explanatory drawing of hardening reaction of an acrylic sol composition at the time of making it heat up in 5 minutes until the physical temperature of an acrylic sol composition will be 100 degreeC. Explanatory drawing of hardening reaction of the acrylic sol composition at the time of making it heat up in 15 minutes until the physical temperature of an acrylic sol composition will be 100 degreeC.

  An embodiment of an acrylic sol composition according to the present invention will be described. The acrylic sol composition in the present embodiment is, for example, a sealant for automobile steel plate joints, an undercoat material used for vehicle parts such as floors and wheel houses, rocker panels, door lower parts, fenders and the like. It can be used as a chipping material.

  The acrylic sol composition of the present embodiment contains an acrylic resin, a UV (ultraviolet) curable resin, and a blocked isocyanate resin. The blocked isocyanate resin contains 60 to 30% by mass of a blocked isocyanate resin having a dissociation temperature of 110 to 125 ° C. and 40 to 70% by mass of a blocked isocyanate resin having a dissociation temperature of 85 to 95 ° C.

  As the acrylic resin, for example, a single polymer or copolymer of a monomer selected from an alkyl acrylate ester, an alkyl methacrylate ester, and the like can be used. Specific examples of the monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, ter-butyl acrylate, cyclohexyl acrylate, benzyl acrylate, methyl methacrylate, Ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, ter-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate and the like can be used. Moreover, styrene, (alpha) -methylstyrene, methacrylic acid, acrylic acid, itaconic acid, crotonic acid etc. can be used as a copolymerization component. This type is in the form of fine particles, and it is particularly preferable to use a core-shell type composed of a core part and a shell part. It is preferable to use butyl methacrylate, which is particularly gelled, for the core part.

  When the acrylic sol composition in the present embodiment is used as a sealing material, it is usually used (coated) with a thickness of about 0.5 to 2.5 mm. In order to cure the ultraviolet rays to the deep part of the sealing material, it is necessary to increase the light transmittance. The vinyl chloride resin is inferior in light transmittance to the acrylic resin. For this reason, acrylic resin is used in the present embodiment in order to maintain light transmittance.

  As the UV curable resin, there is a reactive urethane oligomer having a urethane structure obtained by reacting an isocyanate and a polyol, and an oligomer having a radical polymerizable carbon-carbon double bond such as an acryloyl group at the molecular end. Can be used.

As the aliphatic isocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate can be used. .
As aromatic isocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 2, 2′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-biphenylene diisocyanate, 3,3′-dimethoxy-4, 4′-biphenylene diisocyanate, 3,3′-dichloro-4,4′-biphenylene diisocyanate Isosoanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, or the above adduct, nurate, burette and the like can be used.
In addition, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, dimer acid diisocyanate, and the like can be used.

  Typical polyols include polyether polyols and polyester polyols. Examples of the polyether polyol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and glycerin. , Tromethylolethane, trimethylolpropane, sorbitol, sucrose, aconite sugar, trimellitic acid, hemimellitic acid, phosphoric acid, ethylenediamine, diethylenetriamine, triisopropanamine, pyrogallol, dihydroxybenzoic acid, hydroxyphthalic acid, 1,2, One or more of compounds having at least two active hydrogen atoms such as 3-propanetrithiol as initiators for ethylene oxide, propylene oxide, butylene Ring-opening polymerization of one or more monomers such as oxyoxide, styrene oxide, epichlorohydrin, tetrahydrofuran, cyclohexylene, etc. by addition polymerization, or the above monomers as a cationic catalyst, protonic acid, Lewis acid, etc. Can be used.

As the polyester polyol, a condensed polyester polyol, a lactone polyester polyol, a polyester polyol containing a polycarbonate diol, or the like can be used.
In addition, among polybutadiene-based polyols, polyolefin-based polyols, and polyether polyols, acrylonitrile alone or a mixed monomer of acrylonitrile and at least one selected from the group of styrene, acrylamide, acrylate ester, methacrylate ester, and vinyl acetate is polymerized. Or the polymer polyol etc. which carried out the graft polymerization are mention | raise | lifted.

  As the blocked isocyanate resin as the adhesion component, it is preferable to use a blocked isocyanate-containing urethane prepolymer. The blocked isocyanate-containing urethane prepolymer is obtained by blocking residual isocyanate of polyurethane obtained by reacting isocyanate and polyol such as polyether polyol and polyester polyol with a blocking agent.

  The blocked isocyanate-containing urethane prepolymer can be produced according to the following procedure. First, a polyol and an excess polyisocyanate compound are reacted to obtain a terminal NCO-containing urethane prepolymer.

  Typical polyols include polyether polyols and polyester polyols. Examples of the polyether polyol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and glycerin. , Tromethylolethane, trimethylolpropane, sorbitol, sucrose, aconite sugar, trimellitic acid, hemimellitic acid, phosphoric acid, ethylenediamine, diethylenetriamine, triisopropanamine, pyrogallol, dihydroxybenzoic acid, hydroxyphthalic acid, 1,2, One or more of compounds having at least two active hydrogen atoms such as 3-propanetrithiol as initiators for ethylene oxide, propylene oxide, butylene Ring-opening polymerization of one or more monomers such as oxyoxide, styrene oxide, epichlorohydrin, tetrahydrofuran, cyclohexylene, etc. by addition polymerization, or the above monomers as a cationic catalyst, protonic acid, Lewis acid, etc. Can be used.

As the polyester polyol, a condensed polyester polyol, a lactone polyester polyol, a polyester polyol containing a polycarbonate diol, or the like can be used.
In addition, among polybutadiene-based polyols, polyolefin-based polyols, and polyether polyols, acrylonitrile alone or a mixed monomer of acrylonitrile and at least one selected from the group of styrene, acrylamide, acrylate ester, methacrylate ester, and vinyl acetate is polymerized. Alternatively, a polymer polyol obtained by graft polymerization can be used.

  Examples of the polyisocyanate compound include aliphatic isocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and dodecamethylene diisocyanate. 1,3-cyclopentane diisocyanate, 1,6-hexane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate Methyl 2,6-cyclohexane diisocyanate, 1,4-bis (isocyanatomethyl) cyclohexane, 1,3-bis (i Cyanate methyl) cyclohexane, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, crude MDI, 2,4- or 2, 6-tolylene diisocyanate, 4,4′-toluidine diisocyanate, dianidine diisocyanate, 4,4′-diphenyl ether diisocyanate, 1,3- or 1,4-xylylene diisocyanate, ω, ω unit-diisocyanate-1,4- Aromatic isocyanates such as diethylbenzene can be used. In addition, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, dimer acid diisocyanate, and the like can be used.

  Next, by reacting the terminal NCO-containing urethane prepolymer with an appropriate blocking agent to block free NCO, the target blocked isocyanate-containing urethane prepolymer is obtained.

  Examples of the blocking agent include monohydric alcohols such as methanol, ethanol, propanol, butanol, isobutanol, isononyl alcohol, stearyl alcohol or isomers thereof; phenol, cresol, xylol, p-nitrophenol, alkylphenol, and the like. Phenols; active methylene compounds such as methyl malonate, ethyl malonate, dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate and acetylacetone; acid amides such as acetamide, acrylamide and acetanilide; succinimide and malee Acid imides such as acid imides; Imidazoles such as 2-ethylimidazole and 2-ethyl-4-methylimidazole; Lactams such as 2-pyrrolidone and ε-caprolactam Ketones or aldehyde oximes such as acetoxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, cyclohexanone oxime, and acetoaldoxime; glycol derivatives such as methyl glycol, ethyl glycol, ethyl diglycol, and ethyl triglycol; amine compounds such as dicyclohexylamine In addition, ethyleneimine and bisulfite can be used.

  In this embodiment, the blocked isocyanate resin is used by mixing a blocked isocyanate resin having a blocking agent dissociation temperature of about 110 to 125 ° C. and a blocked isocyanate resin having a blocking agent dissociation temperature of about 85 to 95 ° C. Preferably, a block isocyanate resin having a dissociation temperature of about 120 ° C. and a block isocyanate resin having a dissociation temperature of about 90 ° C. are mixed and used. As the blocked isocyanate resin having a dissociation temperature of 110 to 125 ° C., any of aliphatic isocyanates and aromatic isocyanates can be used, and it is not particularly necessary to define them, but hexamethylene diisocyanate and tolylene diisocyanate are particularly preferable. As the blocked isocyanate resin having a dissociation temperature of 85 to 95 ° C., it is preferable to use an aromatic isocyanate, and it is particularly preferable to use tolylene diisocyanate.

  The UV curable resin is preferably contained in an amount of 20 to 300 parts by mass, particularly preferably 50 to 200 parts by mass with respect to 100 parts by mass of the acrylic resin. When the amount is less than 20 parts by mass, curing by ultraviolet rays is insufficient, and when the amount exceeds 300 parts by mass, the molecular weight is higher than that of the monomer, so that the viscosity is high and the coating workability tends to be remarkably deteriorated.

  The blocked isocyanate resin preferably contains 60 to 30% by mass of a blocked isocyanate resin having a dissociation temperature of 110 to 125 ° C. Moreover, it is preferable to contain 40-70 mass% of block isocyanate resins whose dissociation temperature is 85-95 degreeC. This is because if the blocked isocyanate resin having a dissociation temperature of 110 to 125 ° C. is less than 30% by mass or exceeds 60% by mass, the adhesion to the adherend becomes insufficient. This is because if the blocked isocyanate resin having a dissociation temperature of 85 to 95 ° C. is less than 40% by mass or exceeds 70% by mass, the adhesion to the adherend becomes insufficient.

The block isocyanate resin is preferably contained in an amount of 40 to 200 parts by mass, particularly preferably 60 to 120 parts by mass with respect to 100 parts by mass of the acrylic resin. If the amount is less than 40 parts by mass, the adhesion to the adherend is insufficient, and if it exceeds 200 parts by mass, the coating workability tends to be remarkably deteriorated.
In addition, the blocked isocyanate resin having a dissociation temperature of 110 to 125 ° C. is preferably contained in an amount of 100 to 20 parts by mass, particularly preferably 48 to 24 parts by mass with respect to 100 parts by mass of the acrylic resin. The block isocyanate resin having a dissociation temperature of 85 to 95 ° C. is preferably contained in an amount of 20 to 100 parts by mass, particularly preferably 32 to 56 parts by mass with respect to 100 parts by mass of the acrylic resin. This is because if the blocked isocyanate resins having dissociation temperatures of 110 to 125 ° C. and 85 to 95 ° C. are each less than 20 parts by mass with respect to 100 parts by mass of the acrylic resin, the adhesion to the adherend becomes insufficient. . This is because when the block isocyanate resins having dissociation temperatures of 110 to 125 ° C. and 85 to 95 ° C. exceed 100 parts by mass with respect to 100 parts by mass of the acrylic resin, the coating workability (dischargeability from the nozzle) is deteriorated. .

  The acrylic sol composition in the present embodiment contains a plasticizer, a thermal radical generator, a filler, a polymerization initiator, and the like as necessary in addition to the acrylic resin, the UV curable resin, and the blocked isocyanate resin. be able to. The acrylic sol composition also contains a latent curing agent that reacts with the blocked isocyanate resin.

  As the plasticizer, for example, known plasticizers such as phthalic acid ester, phosphoric acid ester, adipic acid ester, sebacic acid ester, and sulfonic acid ester plasticizer can be used. For example, phthalate ester plasticizers include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dihexyl phthalate (DHP), di-2-ethylhexyl phthalate (DOP), diisodecyl phthalate (DIDP) Butylbenzyl phthalate (BBP), diisononyl phthalate (DINP), dinonyl phthalate (DNP), and the like can be used. As the phosphate ester plasticizer, tricresyl phosphate (TCP), trixylylene phosphate (TXP) and the like can be used. Dioctyl adipate (DOA), diisodecyl adipate (DIDA) and the like can be used as the adipate plasticizer. As the sebacate plasticizer, dibutyl sebacate (DBS), dioctyl sebacate (DOS), or the like can be used. As the sulfonic acid ester plasticizer, alkylsulfonic acid phenyl ester or the like can be used. These plasticizers can be used alone or in combination of two or more, but phthalic acid plasticizers are particularly preferred.

  The plasticizer is preferably contained in an amount of 200 to 700 parts by mass with respect to 100 parts by mass of the acrylic resin. If it is less than 200 parts by mass, the viscosity is high and the coating workability tends to be remarkably deteriorated, and the coating film performance, particularly flexibility, is impaired. If the amount exceeds 700 parts by mass, the coating film performance, particularly the strength, is impaired, and the adhesion to the adherend becomes insufficient. Since the plasticizer can be varied by adjusting the viscosity, the amount is not particularly specified. However, if the amount is too small, the elongation is lowered, and if the amount is too large, the paint adhesion may be affected. Usually, the addition amount of the plasticizer is adjusted to about ± 20% with respect to the basic amount of the plasticizer to be added.

  As the thermal radical generator, for example, peroxide can be used. The thermal radical generator is preferably contained in an amount of 0.5 to 5 parts by mass, particularly preferably 1 to 3 parts by mass with respect to 100 parts by mass of the acrylic resin. If the amount is less than 0.5 part by mass, the curing of the UV curable resin becomes insufficient, and there is a concern that the coating film performance may be deteriorated. If the amount exceeds 5 parts by mass, the storage stability may be deteriorated.

  As the filler, for example, inorganic fillers such as calcium carbonate, barium sulfate, clay, diatomaceous earth, silica, and talc can be used. These fillers can be used alone or in combination of two or more. In particular, the combined use with silica having high light transmittance is preferred. Further, if necessary, hollow particles such as a glass balloon, a resin balloon, or a resin balloon that expands when heated can be blended. The filler is preferably contained in an amount of 50 to 800 parts by mass, and particularly preferably 250 to 450 parts by mass with respect to 100 parts by mass of the acrylic resin. When adjusting the viscosity, if it is less than 50 parts by mass, the coating workability tends to be remarkably deteriorated, and if it exceeds 800 parts by mass, the adhesion to the adherend becomes insufficient.

  Examples of the latent curing agent include polyamines and modified products, aromatic amines and modified products, hydrazides, and the like, which are inert at room temperature, but are particularly activated by heating and react with isocyanate. Any can be used. The latent curing agent is preferably contained in an amount of 10 to 80 parts by mass, and particularly preferably 20 to 60 parts by mass with respect to 100 parts by mass of the acrylic resin. If it is less than 10 parts by mass, the adhesion to the adherend will be insufficient, and if it exceeds 80 parts by mass, a large amount of unreacted material will remain and the coating film performance will deteriorate.

  Examples of the ultraviolet polymerization initiator include benzoin-based, alkylphenone-based (benzyldimethyl ketal, α-hydroxyalkylphenone, α-aminoalkylphenone, etc.), acylphosphine oxide-based (monoacylphosphine oxide, bisacylphosphine oxide). Etc.), sulfur compounds such as titanocene, oxime ester, oxyphenylacetate, tetramethylthiuram disulfide and the like can be used.

  Among the polymerization initiators, it is preferable to use an acyl phosphine oxide-based compound because it is necessary to cure to the deep part of the thick film with ultraviolet rays. Moreover, it is preferable to mix an alkylphenone-based α-hydroxyalkylphenone compound with the acylphosphine oxide compound. This is because the polymerization efficiency can be improved and surface hardening can be promoted. In addition, the polymerization initiator may be used in combination of two systems that promote surface curing and cure to the deep part.

  Furthermore, in order to increase the photopolymerization initiation efficiency, a photosensitizer may be used in combination. As the photosensitizer, for example, an aromatic or aliphatic tertiary amine can be used.

The application conditions and curing conditions of the acrylic sol composition of the present invention are not particularly limited, but as an example, the application conditions are a film thickness of about 0.5 mm to 2.5 mm and a room temperature to 40 mm. It is about ℃. UV cure conditions ^{are 50mJ / cm 2 ~2000mJ / cm 2} .

Such an acrylic sol composition in the present embodiment hardly causes interface peeling regardless of baking conditions, and can be suitably baked and cured. The reason will be described below with reference to the drawings.
FIG. 1 is an explanatory diagram of the curing reaction of the acrylic sol composition when the temperature of the acrylic sol composition is raised to 100 ° C. in 5 minutes.
FIG. 2 is an explanatory diagram of the curing reaction of the acrylic sol composition when the temperature of the acrylic sol composition is raised to 100 ° C. in 15 minutes.

  The acrylic sol composition contains an acrylic resin (acrylic resin), a blocked isocyanate resin (adhesion component) having a dissociation temperature of about 120 ° C., a UV curable resin (UV resin), and a latent curing agent (curing agent). . In this acrylic sol composition, the acrylic resin gelation reaction starting from about 80 ° C. of the acrylic sol composition, the cross-linking curing reaction of blocked isocyanate resin starting from about 120 ° C., and from about 100 ° C. Three curing reactions occur with the thermal crosslinking curing reaction of the UV curable resin being initiated.

  Specifically, after the acrylic sol composition is applied to the adherend (electrodeposited surface), the UV curable resin is radically polymerized and cured by UV irradiation to become a UV curable resin having a high polymerization rate. When the temperature of the acrylic sol composition reaches around 80 ° C., the gelation reaction of the acrylic resin proceeds.

  Here, in the case of FIG. 1 where the rate of temperature increase is fast, gelation of the acrylic resin proceeds while being compatible with other resins such as a blocked isocyanate resin as an adhesion component. That is, the acrylic resin absorbs the plasticizer and swells, and the acrylic resin in the same state and another resin overlap each other to form an integrated coating film. Further, the unreacted UV curable resin is cured by baking. When the temperature of the acrylic sol composition is around 110 ° C., the polymerization of the UV curable resin residue and the curing reaction with the adhesive component proceed during the gelation of the acrylic resin. Adhesiveness is ensured by the compatibility between the gelled coating film of the acrylic resin and the other resin and the bonding with the surface functional group of the adhesion component.

  On the other hand, in the case of FIG. 2 where the rate of temperature rise is slow, when the temperature of the acrylic sol composition is around 80 ° C., only the gelation reaction of the acrylic resin proceeds and compatibility with other resins such as adhesion components occurs. Absent. Further, when the temperature of the acrylic sol composition is around 110 ° C., after the gelation reaction of the acrylic resin proceeds, the polymerization of the UV curable resin, the curing reaction of the adhesion component, and the respective reactions are performed stepwise. proceed. For this reason, in particular, the compatibility between the acrylic resin and the other reaction resin becomes insufficient, and it is expected that the acrylic resin will not function for adhesion to the coating film itself, and the interface part will be peeled off. .

  For the above reasons, when the rate of temperature increase is high, the three curing reactions appear almost simultaneously or in close time, and the sealing material can be cured in an intertwined state. However, when the temperature is raised slowly, the three curing reactions progress independently with a time difference, resulting in a decrease in adhesion performance. In order to solve such a problem, in the present embodiment, by using a blocked isocyanate resin in combination with two blocking agents having different dissociation temperatures, a state in which the reaction proceeds independently is prevented, and a baking condition for gradually increasing the temperature Adhesiveness can be secured even underneath.

  Hereinafter, the acrylic sol composition according to the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

[Acrylic sol composition]
In the following examples and comparative examples, the acrylic sol composition comprises an acrylic powder for plastisol containing butyl methacrylate as an acrylic resin (Dainar LP3106 manufactured by Mitsubishi Rayon Co., Ltd.), and a urethane oligomer ( Sartomer, CN9002), a blocked isocyanate-containing urethane prepolymer using hexamethylene diisocyanate as a polyisocyanate compound as a blocked isocyanate resin having a dissociation temperature of about 120 ° C. (Q9402, manufactured by Adeka Co., Ltd.), a dissociation temperature of about 90 Block isocyanate containing urethane prepolymer using tolylene diisocyanate as polyisocyanate compound as block isocyanate resin at 0 ° C. (M70, manufactured by Mitsui Chemicals, Inc.), potential Polyamine curing agent ((Ltd.) ADEKA Corporation, EH3731S) as agent was used.

  Also, phthalate ester (DINP) (manufactured by J-Plus, DINP) and alkyl sulfonic acid phenyl ester plasticizer (manufactured by Bayer, Mezamol) as a plasticizer, peroxide (Nippon Yushi Co., Ltd.) as a thermal radical generator Perbyl O), silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.) as a filler, and phosphine oxide initiator (Irgacure 819 manufactured by BASF Japan Co., Ltd.) as an ultraviolet polymerization initiator were used.

[Test piece]
In the test, a test piece composed of a plate obtained by applying an electrodeposition layer to a steel plate was used. The test piece has a dimension of width 70 mm × depth 150 mm × thickness 0.8 mm, and a special jig is used so that the acrylic sol composition has a width 10 mm × depth 100 × thickness 2.5 mm with respect to this test piece. Applied. The test piece is a tabletop electric furnace in which the time for the material temperature of the acrylic sol composition to be raised to 100 ° C. is set to three times of 5 minutes, 15 minutes, and 60 minutes after ultraviolet irradiation under the condition of 300 mJ / cm ^2. Baking was performed using an oven such as In the baking process, after the temperature of the acrylic sol composition was raised to 100 ° C., the temperature of the acrylic sol composition was maintained at 130 ° C. for 20 minutes.

[Testing and evaluation methods]
The adhesion test was performed on the test piece after baking by a nail peeling test of the acrylic sol composition. The evaluation was made by any one of cohesive failure (Cohesive failure, Cf), interfacial failure (adhesive failure, adhesive failure, Af), and cohesive failure (a mixture of Af and Cf) in which interfacial failure occurred in part. In this example, interfacial fracture and cohesive fracture in which interfacial fracture occurred (those in which interfacial peeling occurred) were evaluated as inappropriate.

  Based on the said conditions, the test piece as Examples 1-6 and Comparative Examples 1-5 was produced as follows. In Examples 1-6 and Comparative Examples 1-5, as an acrylic sol composition, with respect to 100 parts by mass of acrylic resin, 130 parts by mass of UV curable resin, 40 parts by mass of latent curing agent, and plasticizer 450 parts by mass, 1.2 parts by mass of a thermal radical generator, 340 parts by mass of a filler, and 2.4 parts by mass of a polymerization initiator.

  In Examples 1 to 4 and Comparative Examples 1 to 5, the blocked isocyanate resin includes a blocked isocyanate resin having a dissociation temperature of about 120 ° C. and a blocked isocyanate resin having a dissociation temperature of about 90 ° C., respectively, and 100 mass of acrylic resin. The content was changed in the range shown in Table 1 in the range of 0 to 80 parts by mass with respect to parts. On the other hand, in Examples 5 and 6, a blocked isocyanate resin having a dissociation temperature of about 120 ° C. and a blocked isocyanate resin having a dissociation temperature of about 90 ° C. are respectively 20 parts by mass and 100 parts by mass with respect to 100 parts by mass of the acrylic resin. Contained.

  The adhesive evaluation results of Examples 1 to 6 and Comparative Examples 1 to 5 are shown in Table 1.

  From the above, it can be seen that the coating film formed from the acrylic sol composition of this example is excellent in adhesiveness without causing interfacial peeling regardless of the heating rate in the baking step. That is, Examples 1 to 6 containing a blocked isocyanate resin having a dissociation temperature of 60 to 30% by mass of a blocked isocyanate resin having a dissociation temperature of 120 ° C. and a blocked isocyanate resin having a dissociation temperature of 40 to 70% by mass of 90 ° C. Also, no interfacial fracture occurred. From this, the acrylic sol composition in this example uses a blocked isocyanate resin in combination with two blocking agents having different dissociation temperatures, thereby preventing the reaction from proceeding singly and even under baking conditions where the temperature rises slowly. It was found that adhesion can be secured.

Claims (7)

Acrylic resin,
UV curable resin,
A blocked isocyanate resin containing 60 to 30% by mass of a blocked isocyanate resin having a dissociation temperature of 110 to 125 ° C. and 40 to 70% by mass of a blocked isocyanate resin having a dissociation temperature of 85 to 95 ° C. An acrylic sol composition comprising:
The blocked isocyanate resin has a dissociation temperature of 110 to 125 ° C. with respect to 100 parts by mass of the acrylic resin 100 to 20 parts by mass, and the dissociation temperature of 85 to 95 ° C. with respect to the blocked isocyanate resin with the acrylic. An acrylic sol composition containing 20 to 100 parts by mass with respect to 100 parts by mass of the resin.   The blocked isocyanate resin may be a block isocyanate resin having a dissociation temperature of 110 to 125 ° C. and 48 to 24 parts by mass with respect to 100 parts by mass of the acrylic resin, and a block isocyanate resin having a dissociation temperature of 85 to 95 ° C. The acrylic sol composition according to claim 1, which is contained in an amount of 32 to 56 parts by mass with respect to 100 parts by mass of the system resin. The blocked isocyanate resin having a dissociation temperature of 110 to 125 ° C. is a resin obtained using aliphatic isocyanate or aromatic isocyanate,
The acrylic sol composition according to any one of claims 1 to 2, wherein the blocked isocyanate resin having a dissociation temperature of 85 to 95 ° C is a resin obtained using an aromatic isocyanate. The blocked isocyanate resin having a dissociation temperature of 110 to 125 ° C. is a resin obtained using hexamethylene diisocyanate or tolylene diisocyanate,
The acrylic sol composition according to claim 3, wherein the blocked isocyanate resin having a dissociation temperature of 85 to 95 ° C is a resin obtained using tolylene diisocyanate.   The acrylic sol composition according to any one of claims 1 to 4, wherein the blocked isocyanate resin contains a blocked isocyanate resin having a dissociation temperature of 120 ° C and a blocked isocyanate resin having a dissociation temperature of 90 ° C.   20 to 300 parts by mass of the UV curable resin, 40 to 200 parts by mass of the blocked isocyanate resin, and 10 to 80 of a latent curing agent that reacts with the blocked isocyanate resin with respect to 100 parts by mass of the acrylic resin. The acrylic sol composition according to any one of claims 1 to 5, which is contained in parts by mass.   The UV-curable resin is contained in an amount of 50 to 200 parts by mass, the blocked isocyanate resin is contained in an amount of 60 to 120 parts by mass, and the latent curing agent is contained in an amount of 20 to 60 parts by mass with respect to 100 parts by mass of the acrylic resin. 6. The acrylic sol composition according to 6.

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