JP2019167509A - Adhesive composition for methacrylic artificial marble and adhesion method of artificial marble - Google Patents

Abstract

Disclosed is a two-pack curable methacrylic artificial marble adhesive composition in which color change with time of an initiator diluent is effectively suppressed.
The adhesive composition for methacrylic artificial marble of the present invention comprises 75 to 95% by mass of syrup (S) containing methyl methacrylate and a methyl methacrylate polymer (P), and 25 to 5 mass. % Of the main component (I) containing the inorganic filler (F) in an amount of 10%, an epoxidized unsaturated fatty acid alkyl ester (E) having a fatty acid portion of 16 to 18 carbon atoms, an organic peroxide ( O) and an initiator diluent (II) containing 1 part by mass.
[Selection figure] None

Description

  The present invention relates to a two-component curable adhesive composition for methacrylic artificial marble and a method for bonding methacrylic artificial marble using the same.

  Methacrylic resin composition is excellent in transparency, colorability, moldability, weather resistance, surface hardness, etc., taking advantage of those characteristics, as signboards, decoration materials, lighting covers, automobile parts, glazing materials, etc. Widely used in various fields. Furthermore, in recent years, with the expansion of the use of methacrylic resin, it has come to be used in the sanitary field such as a bathtub, a bathroom, and a bathroom, and the kitchen field such as a top plate of a system kitchen.

  Methacrylic artificial marble has been developed that has the same luxury and texture as natural stone, but is easy to maintain and has excellent processability, such as system kitchens, counters, washstands, and table tops. Has been used. For example, in Patent Document 1, 10 to 45 masses of at least one inorganic filler (B) selected from aluminum hydroxide, magnesium hydroxide, calcium carbonate, and silica with respect to 100 mass parts of the methacrylic resin (A). A methacrylic artificial marble containing a portion is disclosed (claim 1).

JP 2005-272175 A Japanese Patent Publication No. 05-053803

In actual construction, a methacrylic artificial marble original plate is cut into a desired size and shape, and a plurality of artificial marble plates obtained are bonded as necessary. Conventionally, as an adhesive for methacrylic artificial marble, a two-component curable adhesive composition comprising a main agent containing methyl methacrylate (MMA) and an initiator diluent containing a solvent (diluent) and a polymerization initiator. The product is preferably used.
Here, since the toning of the adhesive is generally performed with the main agent, the initiator diluent is preferably colorless and transparent. However, in general, in an initiator diluent that contains an organic peroxide such as Aseal as a polymerization initiator, the initiator diluent tends to undergo a color change (specifically, yellowing) over time. The initiator diluent is rarely used immediately after preparation, and is usually stored and transported after preparation and used after a certain amount of time. When using an initiator diluent that has changed color over time after preparation, the color of the seam will be mixed with the cured adhesive and the color of the seam will be different from that of artificial marble. .

  In Patent Document 2, as an initiator diluent for curing a main agent (MMA resin solution) containing one or more monomers containing MMA or a partial polymer thereof, a solvent (diluent) containing dioctyl phthalate is used. Thus, there is disclosed a polymerization curing catalyst composition in which an eals organic peroxide as a polymerization initiator (catalyst) is dissolved (claim 1). Patent Document 2 reports that by using dioctyl phthalate as a solvent (diluent), it is possible to suppress a change in coloring over time of an initiator dilute solution containing an ealce organic peroxide.

  However, as a result of investigation by the present inventor, it was found that when dioctyl phthalate was used, the effect of suppressing the color change over time of the initiator diluent containing an organic peroxide was not necessarily sufficient ( (See Comparative Example 4 in the “Examples” section below). It is preferable that the color change with time of the initiator diluent containing the organic peroxide can be more effectively suppressed.

  The present invention has been made in view of the above circumstances, and provides a two-component curable adhesive composition for methacrylic artificial marble in which the color change with time of the initiator diluent is effectively suppressed. With the goal.

The present invention provides the following two-component curable methacrylic artificial marble adhesive composition and the artificial marble bonding method of [1] to [5] below.
[1] Main agent (I) containing 75 to 95% by mass of syrup (S) containing methyl methacrylate and methyl methacrylate polymer (P) and 25 to 5% by mass of inorganic filler (F). 10 to 20 parts by mass;
Two-component curing comprising an epoxidized unsaturated fatty acid alkyl ester (E) having 16 to 18 carbon atoms in the fatty acid portion and 1 part by weight of an initiator diluent (II) containing an organic peroxide (O) Type adhesive composition for methacrylic artificial marble.

[2] The adhesive composition for methacrylic artificial marble according to [1], wherein the syrup (S) includes 50 to 80% by mass of methyl methacrylate and 50 to 20% by mass of the methyl methacrylate polymer (P). object.
[3] The adhesive composition for methacrylic artificial marble according to [1] or [2], wherein the main agent (I) further contains an amine compound (A).
[4] The content of the inorganic filler (F) in the main agent (I) is 1/5 to 1/2 of the content of the inorganic filler in the artificial marble original plate to be bonded [1] to The adhesive composition for methacrylic artificial marble according to any one of [3].
[5] The main component (I) and the initiator diluent (II) of the adhesive composition for methacrylic artificial marble according to any one of [1] to [4] are mixed,
A method for bonding artificial marble, wherein a plurality of methacrylic artificial marbles are bonded using the obtained mixed solution.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition for methacrylic artificial marble of the two-pack hardening type in which the coloring change with time of an initiator dilution liquid was suppressed effectively can be provided.

[Adhesive composition for methacrylic artificial marble]
The two-component curable methacrylic artificial marble adhesive composition of the present invention comprises one or more monomers (M) containing methyl methacrylate (MMA) and a methyl methacrylate (MMA) polymer (P). And a main agent (I) containing an inorganic filler (F),
Two-component curable adhesive comprising an epoxidized unsaturated fatty acid alkyl ester (E) having 16 to 18 carbon atoms in the fatty acid portion and an initiator diluent (II) containing an organic peroxide (O) It is a composition.

(Main agent (I))
<Syrup (S)>
The syrup (S) is composed of at least one monomer (M) containing methyl methacrylate (MMA) and a methyl methacrylate (MMA) polymer (P) containing methyl methacrylate (MMA) monomer units. MMA-based syrup including One or more monomers (M) may contain a crosslinking agent. One or more types of MMA polymers (P) are non-crosslinked linear MMA polymers.

As a method for preparing syrup (S), a prepolymerization method or a polymer dissolution method is preferred.
The syrup (S) obtained by the former method is an MMA polymer (1) obtained by prepolymerizing one or more monomers (M1) containing MMA to a certain polymerization rate in the presence of a polymerization initiator ( P1) and prepolymerized syrup (S1) containing unreacted monomer (M1). Note that one or more monomers (M1) containing MMA may be further added to the prepolymerized syrup (S1) and diluted to be used as the prepolymerized syrup (S1).
The syrup (S) obtained by the latter method is obtained by using an MMA polymer (P2) polymerized using one or more monomers containing MMA and one or more monomers (M2) containing MMA. It is dissolution syrup (S2) obtained by making it melt | dissolve in.

  The MMA polymer (P) (preferably (P1) or (P2)) is a homopolymer of MMA, a copolymer of MMA and one or more alkyl acrylates, a copolymer of MMA and one or more other copolymers. Any of a copolymer with a polymerizable unsaturated monomer may be used.

As one or more monomers (M) (preferably (M1) or (M2)) containing MMA used as a raw material of the MMA polymer (P) (preferably (P1) or (P2)), MMA and other copolymerizable unsaturated monomers that can be used in combination with MMA.
Other copolymerizable unsaturated monomers that can be used in combination with MMA include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, and cyclohexyl acrylate; Carbon number of alkyl groups such as ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, and cyclohexyl methacrylate 2-12 alkyl methacrylates; hydroxy (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxy-3-chloropropyl (meth) acrylate Alkyl; (meth) ac (Meth) acrylic acid metal salts; vinyl monomers such as vinyl chloride, vinyl acetate, and vinyl toluene; acrylonitrile; acrylamide; styrene monomers such as styrene and α-methylstyrene; maleic anhydride, etc. Is mentioned.
In this specification, (meth) acryl is a general term for “methacryl” and “acryl”. The same applies to “(meth) acryloyl”.

  The concentration of the MMA polymer (P) in the syrup (S) (preferably the prepolymerized syrup (S1) or the dissolved syrup (S2)) is not particularly limited, preferably 5 to 40% by mass, more preferably 5 to 5% by mass. 30% by mass. The weight average molecular weight (Mw) of the MMA polymer (P) is not particularly limited, and is preferably 100,000 to 1,500,000, more preferably 700,000 to 1,200,000 in the case of the prepolymerized syrup (S1). In the case of (S2), it is preferably 50,000 to 150,000. When the weight average molecular weight (Mw) is not less than the above lower limit, durability such as chemical resistance after curing of the adhesive is improved, and when it is not more than the upper limit, the production of syrup (S) is facilitated.

In the present specification, unless otherwise specified, the method for measuring the weight average molecular weight (Mw) is as follows.
A 5 g sample is extracted with 200 ml of chloroform, filtered to collect the filtrate, and methanol is added to form a precipitate. This precipitate is vacuum-dried, and then 0.12 g thereof is dissolved in 20 ml of tetrahydrofuran to obtain a measurement sample. “LC-9A” manufactured by Shimadzu Corporation is used as the molecular weight measuring apparatus, “GPC-802”, “HSG-30” and “HSG-50” manufactured by Shimadzu Corporation and “Shodex A-806” manufactured by Showa Denko KK as the column. Is used to measure the molecular weight by GPC (gel permeation chromatography) method.

  The polymerization rate in the prepolymerized syrup (S1) is not particularly limited, and is preferably 5 to 40%, more preferably 5 to 30%. If the polymerization rate is less than 5%, the viscosity of the adhesive mixture obtained by mixing the main agent (I) and the initiator diluent (II) becomes too low, and the bonding operation may be difficult. When the polymerization rate exceeds 40%, the viscosity of the syrup becomes too high, and it may be difficult to uniformly disperse the inorganic filler (F) and the pigment, and the main agent (I) and the initiator diluent (II). The viscosity of the adhesive mixture obtained by mixing the above and the like may become too high, making the bonding operation difficult. Here, the “polymerization rate” is the ratio of the mass of the monomer used in the polymerization reaction to the mass of the charged monomer.

  The crosslinking agent optionally contained in the one or more monomers (M) is not particularly limited, and a monomer having at least two (meth) acryloyl groups in the molecule is preferably used. For example, ethylene glycol di (meth) acrylate, 1,3-propylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, (1,3-butanediol di (meth) acrylate), 1, 4-butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dimethylolethane Di (meth) acrylate, 1,1-dimethylolpropane di (meth) acrylate, 2,2-dimethylolpropane di (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate Rate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 2,2-bis [4-((meth) acryloxyethoxy) phenyl] propane, 2 , 2-bis [4-((meth) acryloxypentenoxy) phenyl] propane, 1,4-bis ((meth) acryloyloxymethyl) cyclohexane, polyethylene glycol di (meth) acrylate, and the like. When the crosslinking agent is used, the amount of the crosslinking agent in the monomer (M) is preferably 0.5 to 3% by mass.

<Inorganic filler (F)>
As the inorganic filler (F), one kind or two or more kinds similar to those added at the time of producing the original plate in order to give a slightly transparent texture unique to artificial marble can be used. Examples of the inorganic filler (F) include aluminum hydroxide, magnesium hydroxide, calcium carbonate, and silica. From the viewpoints of texture, luxury, and machinability, the artificial marble is preferably added with aluminum hydroxide having a small refractive index difference from the MMA polymer. As an inorganic filler (F), it has a color similar to that of the artificial marble to be bonded, and can form a seam that connects a plurality of artificial marbles continuously without a sense of incongruity. Is particularly preferably aluminum hydroxide.

  The average particle diameter of the inorganic filler (F) is not particularly limited and is preferably at the same level as the inorganic filler preferably added to the artificial marble. The average particle size of the inorganic filler (F) is preferably 10 to 100 μm, more preferably 10 to 50 μm, and particularly preferably 15 to 45 μm because the viscosity of the main agent (I) is suitable for workability. is there. In addition, the average particle diameter in this specification means an arithmetic average particle diameter.

<Colorant>
The main agent (I) preferably contains one or more known colorants such as pigments and dyes exhibiting a color matched to the artificial marble to be bonded. A white pigment or the like is preferably used.

<Optional component>
The main agent (I) can contain one or more optional components other than those described above, if necessary.
Examples of optional components include an amine compound (A), a polymerization inhibitor, a chain transfer agent, an ultraviolet absorber, and a viscosity / fluidity modifier. These optional components may be added during the preparation of syrup (S) or may be added to the prepared syrup (S).
The amine compound (A) can act as a polymerization accelerator when redox polymerization is performed in combination with an organic peroxide initiator, and a tertiary amine compound is preferred. Examples of the amine compound include arylamines, alkylamines, and arylalkylamines. Specific examples include N, N-dimethylaniline, N, N-diethylaniline, N, N-dimethyl-p-toluidine, triethylamine, tri-n-butylamine, and dipropyrol p-toluidine.
Examples of the polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, benzoquinone, and 4-t-butylcatechol.

As chain transfer agents, styrene dimers such as α-methylstyrene dimer; mercaptans such as n-octyl mercaptan, n-dodecyl mercaptan, and hyophenol; thioglycolic acid, ethyl thioglycolate, and butyl thioglycolate, Thioglycolic acid (also referred to as mercaptoacetic acid) such as bis (mercaptoacetic acid) ethylene glycol or esters thereof; β-mercaptopropion such as β-mercaptopropionic acid, methyl β-mercaptopropionate, and octyl β-mercaptopropionate Examples thereof include acids and esters thereof.
Examples of the ultraviolet absorber include benzotriazoles such as 2- (2′-hydroxy-5′-methylphenyl) benzotriazole and triazines.
Examples of the viscosity / fluidity modifier include fine powder silica such as Aerosil.

<Contents of syrup (S) and inorganic filler (F)>
From the viewpoint of the balance between adhesion performance and seam texture, in the main agent (I), the concentration of syrup (S) is 75 to 95% by mass, preferably 80 to 90% by mass, and the concentration of the inorganic filler (F) is It is 25-5 mass%, Preferably it is 20-10 mass%.
If the addition amount of the inorganic filler (F) is 5% by mass or more, the same texture as that of the artificial marble can be effectively imparted to the seam. When the concentration of syrup (S) is 75% by mass or more, an adhesive mixture obtained by mixing the main agent (I) and the initiator diluent (II) can exhibit good adhesion performance.

  The main agent (I) can be prepared by mixing the syrup (S), the inorganic filler (F), and optionally one or more optional components.

(Initiator diluent (II))
<Solvent (Diluent)>
The initiator diluent (II) contains one or more solvents (diluents) containing one or more epoxidized unsaturated fatty acid alkyl esters (E) having 16 to 18 carbon atoms in the fatty acid moiety.
Examples of the unsaturated fatty acid having 16 to 18 carbon atoms used as a raw material for the epoxidized unsaturated fatty acid alkyl ester (E) include oleic acid (C ₁₇ H ₃₃ COOH), linoleic acid (C ₁₇ H ₃₁ COOH), and linolenic acid _{(C 17} H 29 COOH), and the like. These can be used alone or in combination of two or more. A mixture of a plurality of unsaturated fatty acids having 16 to 18 carbon atoms, or a mixture containing one or more unsaturated fatty acids having 16 to 18 carbon atoms and other unsaturated fatty acids and / or saturated fatty acids It may be used. As such a mixture, palmitic acid (C ₁₅ H ₃₁ COOH) 3 to 6% by mass, stearic acid (C ₁₇ H ₃₅ COOH) 1 to 3% by mass, oleic acid (C ₁₇ H ₃₃ COOH) 55 to 59% by mass %, Rapeseed oil containing 21 to 32% by mass of linoleic acid (C ₁₇ H ₃₁ COOH) and 9 to 15% by mass of linolenic acid (C ₁₇ H ₂₉ COOH) is preferred.

Change in color of initiator diluent (II) over time by using epoxidized unsaturated fatty acid alkyl ester (E) as the solvent (diluent) of initiator diluent (II) (specifically yellowing) Can be effectively suppressed.
Since the inhibitory effect of the color change over time of the initiator diluent (II) is increased, the epoxidation rate of the unsaturated bond contained in the unsaturated fatty acid is preferably higher, preferably 90 mol% or more, more preferably Is 98 mol% or more, particularly preferably 100 mol%. The alkyl group constituting the alkyl ester is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 2 to 6 carbon atoms, particularly preferably a butyl group, and most preferably an isobutyl group.
Epoxidized unsaturated fatty acid alkyl ester (E) can be produced by a known method, and a commercially available product may be used.

  As the solvent (diluent) for the initiator diluent (II), one or more other solvents (diluents) other than those described above may be used. Other solvents (diluents) include dimethyl phthalate, dibutyl phthalate, dioctyl phthalate, tributyl acetylcrete, tricresyl phosphate, ethyl acetate, and butyl acetate; benzene, toluene, and xylene Aromatic hydrocarbons such as; methyl ketones such as methyl ethyl ketone and methyl isobutyl ketone; and halogenated hydrocarbons such as dichloroethane.

The total concentration of the solvent (diluent) in the initiator diluent (II) is not particularly limited, and is designed in a suitable range for use as the initiator diluent (II) of the two-part curable adhesive composition, Preferably it is 80-95 mass%, More preferably, it is 85-95 mass%.
Epoxidized unsaturated fatty acid alkyl as a solvent (diluent) for initiator diluent (II) from the viewpoint of effectively suppressing color change (specifically yellowing) over time of initiator diluent (II) It is preferable to use only the ester (E), and when using another solvent (diluent), it is preferable to use a smaller amount.
The concentration of the epoxidized unsaturated fatty acid alkyl ester (E) in the initiator diluent (II) can effectively suppress the color change (specifically yellowing) over time of the initiator diluent (II). Is preferably 70 to 100% by mass, more preferably 90 to 100% by mass.

<Organic peroxide (O)>
The initiator diluent (II) contains one or more organic peroxides (O). The organic peroxide (O) can act as a polymerization initiator, and a known one that is generally used for an initiator diluent of a two-part curable adhesive composition can be used. Organic peroxides (O) include benzoyl peroxide, lauroyl peroxide, isobutyl peroxide, 2,4-dichlorobenzoyl peroxide, o-methylbenzoyl peroxide, and bis-3,5,5-trimethylhexanoyl A peroxide etc. are mentioned, A benzoyl peroxide etc. are preferable.
The concentration of the organic peroxide (O) in the initiator diluent (II) is not particularly limited, and it is designed in a suitable range for use as the initiator diluent (II) of the two-component curable adhesive composition. The amount is preferably 5 to 20% by mass, more preferably 5 to 10% by mass.

<Optional component>
The initiator diluent (II) can contain one or more other optional components other than those described above, if necessary.

  One or more solvents (diluents) containing one or more epoxidized unsaturated fatty acid alkyl esters (E) having a fatty acid moiety of 16 to 18 carbon atoms, an organic peroxide (O), and optionally The initiator diluent (II) can be prepared by mixing one or more optional components.

(Amount ratio of main agent (I) and initiator diluent (II))
In the two-pack curable methacrylic artificial marble adhesive composition of the present invention, the amount of the main agent (I) is 10 to 20 parts by mass with respect to 1 part by mass of the initiator diluent (II). With such a quantity ratio, curing can proceed well at a speed suitable as an adhesive after mixing the two liquids.

[How to bond artificial marble]
In actual construction, a methacrylic artificial marble original plate is cut into a desired size and shape, and a plurality of artificial marble plates obtained by cutting are used for the methacrylic artificial marble adhesive composition of the present invention. Can be glued.
The main agent (I) is preferably one that is toned in the same color tone as the original plate of methacrylic artificial marble using a colorant such as a white pigment.
Adhesion can be performed as follows.
The main component (I) of the adhesive composition for methacrylic artificial marble and the initiator diluent (II) are mixed to obtain an adhesive mixture. A plurality of artificial marble plates are arranged in a plane with a slight gap, and the obtained adhesive mixture is filled in the gap. The adhesive mixture liquid filled in the gap is polymerized and cured in the presence of a polymerization initiator in which the syrup (S) contained in the main agent (I) is contained in the initiator diluent (II).

  In the two-pack curable methacrylic artificial marble adhesive composition of the present invention, at least the epoxidized unsaturated fatty acid alkyl ester (E) is used as a solvent (diluent) for the initiator diluent (II). Change in color of initiator diluent (II) over time by using epoxidized unsaturated fatty acid alkyl ester (E) as the solvent (diluent) of initiator diluent (II) (specifically yellowing) Can be effectively suppressed. Therefore, even if the initiator dilution liquid (II) of the adhesive composition for methacrylic artificial marble used for actual bonding is lapsed after preparation, it has the same color as the original plate. It is possible to form a seam made of a cured product in which discoloration is suppressed.

The seam obtained by using the two-component curable adhesive composition for methacrylic artificial marble of the present invention has no coloring of the initiator diluent (II), and therefore the main agent (I) according to the artificial marble to be bonded. The color of a colorant such as a pigment added to can be exhibited as it is. Furthermore, since the main agent (I) contains the inorganic filler (F), the two-pack curable methacrylic artificial marble adhesive composition of the present invention can form a seam having a texture peculiar to marble.
From the viewpoint of the coating properties of the adhesive mixture, the adhesive strength with the original plate after bonding, and the sense of unity, the content of the inorganic filler (F) in the main agent (I) is the amount of the artificial marble original plate to be bonded. It is preferable that it is 1/5 to 1/2 of the content of the inorganic filler.
In addition, Patent Document 2 cited in the section of “Background Art” does not disclose an aspect of adding an inorganic filler to the main agent, and the adhesive composition described in Patent Document 2 does not provide such effects.

  When adhering a plurality of artificial marbles using the two-component curable adhesive composition for methacrylic artificial marble of the present invention, even if the initiator diluent (II) is a time-lapse product, the artificial marble to be bonded It is possible to form a seam that continuously connects a plurality of artificial marbles without a sense of incongruity, and to achieve excellent adhesion.

As described above, according to the present invention, it is possible to provide a two-component curable methacrylic artificial marble adhesive composition in which color change with time of the initiator diluent is effectively suppressed. .
The adhesive composition for methacrylic artificial marble of the present invention can be preferably used for adhesion of artificial marble used for top plates of system kitchens, counters, washstands, tables and the like.

Examples and comparative examples according to the present invention will be described.
[Evaluation items and evaluation methods]
(Color tone of initiator diluent)
The initiator diluent immediately after preparation or after storage for 3 months was visually observed and judged to be colorless and transparent, good (◯), and yellow transparent and poor (x).
(Yellowness of initiator diluent (YI value))
Into a quartz square cell having a width of 20 mm, a thickness of 10 mm, and a height of 55 mm (inner dimensions), the initiator diluted solution immediately after preparation or after storage for 3 months as a sample solution is 40 to 45 mm in height (two standards). (Between lines). Next, the quartz square cell into which the sample solution was injected was set in a sample chamber for transmitted light measurement of a spectrocolorimeter (manufactured by Nippon Denshoku Industries Co., Ltd., model: SD5000, light source: D65), and the yellowness (YI value) ) In addition, the same measurement was performed using distilled water as a standard sample, and standard matching was performed.

(The color of the cured product)
A cured product is placed on a sample stand with a thickness of 28 mm for measuring reflected light of a spectrocolorimeter (Nippon Denshoku Industries Co., Ltd., model: SD5000, light source: D65) so that the mirror surface is the upper surface. Made the color. In addition, the same measurement was performed using a white standard plate as a standard sample, and standard matching was performed.
Two types of cured products obtained by using the initiator dilution solution prepared on the day and stored for 3 months in Comparative Example 1, and the initiator dilution after 3 months storage in each of Comparative Examples 2 to 4 and Example 1 About the hardened | cured material obtained using the liquid, L value, a value, and b value were measured, respectively. Furthermore, in each of Comparative Examples 2 to 4 and Example 1, the cured product obtained using the initiator diluent after storage for 3 months was obtained in Comparative Example 1 using the initiator diluent prepared on the day. The color difference (E value difference, ΔE value) relative to the cured product was determined.
Two types of cured products obtained by using the initiator dilution solution prepared on the day and stored for 3 months in Comparative Example 1, and the initiator dilution after 3 months storage in each of Comparative Examples 2 to 4 and Example 1 About the hardened | cured material obtained using the liquid, yellowness (YI value) was measured, respectively. Furthermore, in each of Comparative Examples 2 to 4 and Example 1, the cured product obtained using the initiator diluent after storage for 3 months was obtained in Comparative Example 1 using the initiator diluent prepared on the day. The degree of yellowing (difference in YI value, ΔYI value) relative to the cured product was determined.

[Epoxidized fatty acid alkyl ester (E)]
The following materials were prepared as the epoxidized fatty acid alkyl ester (E).
(E-1): “Adekasizer D-55” manufactured by Adeka Corporation [palmitic acid (C ₁₅ H ₃₁ COOH) 3 to 6% by mass, stearic acid (C ₁₇ H ₃₅ COOH) 1 to 3% by mass, oleic acid ( Of rapeseed fatty acid isobutyl ester containing a mixture of 55 to 59% by mass of C ₁₇ H ₃₃ COOH), 21 to 32% by mass of linoleic acid (C ₁₇ H ₃₁ COOH) and 9 to 15% by mass of linolenic acid (C ₁₇ H ₂₉ COOH) Completely epoxidized product].

[Example 1, Comparative Examples 1 to 4]
(Preparation of main agent (Ia) of adhesive)
To a monomer mixture consisting of 595 parts by mass of methyl methacrylate (MMA) and 10 parts by mass of ethylene glycol dimethacrylate (crosslinking agent), 405 parts by mass of polymethyl methacrylate (PMMA) (Parabeads G-1000P manufactured by Kuraray Co., Ltd.) 0.5 parts by mass of paraffin (melting point: 60 to 62 ° C.), 0.01 parts by mass of hydroquinone (polymerization inhibitor), 1 part by mass of 2- (2′-hydroxy-5′-methylphenyl) benzotriazole (ultraviolet absorber) 1 part by mass of bis (mercaptoacetic acid) ethylene glycol (chain transfer agent) and 1.93 parts by mass of dipropyrol p-toluidine (amine compound) were dissolved to obtain dissolved syrup (S2-1) (MMA-containing syrup). Prepared. In 800 parts by mass of this dissolved syrup (S2-1), 200 parts by mass of an aluminum hydroxide inorganic filler (CW-325LV manufactured by Sumitomo Chemical Co., Ltd.), 20 parts by mass of Aerosil, and a white pigment (K-39BFF manufactured by Dainichi Seika Co., Ltd.) ) 1 part by mass was dispersed to obtain an adhesive main agent (Ia).

(Preparation of initiator diluents (III-1) to (III-4) and (II-1))
In Example 1 and Comparative Examples 1 to 4, 7 parts by mass of a benzoyl peroxide stabilized product (pure content 50% by mass) was dissolved in 93 parts by mass of the solvent (diluent) shown in Table 1, and an initiator diluent (III- 1) to (III-4) and (II-1) were obtained. In any of the examples, all the solutions immediately after preparation were colorless and transparent, and the color tone was good. About the initiator dilution liquid (III-1) obtained by the comparative example 1, the yellowness (YI value) immediately after preparation was also evaluated. In other examples, the yellowness (YI value) immediately after preparation was the same level as in Comparative Example 1. The initiator diluent obtained in each example was stored in a container at room temperature of 20 to 25 ° C. for 3 months. About each initiator dilution liquid after storage for 3 months, the color tone and yellowness (YI value) of the solution were evaluated. The evaluation results are shown in Table 1.

(Preparation of cured product)
1 g of the initiator diluent (any one of (III-1) to (III-4) and (II-1)) obtained in each example was added to 15 g of the main agent (I-a). It mixed and the adhesive liquid mixture was obtained. The adhesive mixture obtained was poured into a petri dish container (diameter 50 mm, thickness 7 mm) made of polyethylene, filled, covered with a glass plate, and then the container was turned upside down. After the adhesive mixture in the container was sufficiently cured, a disk-shaped cured product (diameter 50 mm, thickness 7 mm) having a mirror surface on the glass plate side was taken out. In Comparative Example 1, two types of cured products were obtained using the initiator diluent after preparation on the day and storage for 3 months. In another example, a cured product was obtained using an initiator diluent after storage for 3 months. Each cured product was evaluated for color. The evaluation results are shown in Table 2.

(Adhesion of raw artificial marble)
Methacrylic artificial marble plate of 100 mm × 100 mm × 10 mm [Kuraray Nobright KN (brand 400K, aluminum hydroxide (Sumitomo Chemical CW-325LV) 65% by mass), white pigment (Daiichi Seika K-39BFF 2) was prepared. One side of the end of each artificial marble plate was polished smoothly using sandpaper (grain size # 600 to # 1000) to obtain a piece to be bonded.
In each example, an adhesive mixture was prepared using an initiator diluent stored at room temperature for 3 months, and the polished surfaces of the two adhesive test pieces were bonded to each other under the condition of an adhesive layer thickness of 0.5 mm or 2 mm. To obtain an adhesive.
About the adhesive material of 2 mm of adhesive layer thickness obtained in each example, the color difference with the artificial marble board of the adhesive layer after hardening was visually evaluated. Corresponding to the color data in Table 2, in Example 1, no color difference was observed between the adhesive layer and the artificial marble plate, but in Comparative Examples 1 to 4, there was a sense of incongruity due to yellowing of the adhesive layer.
For the adhesive having an adhesive layer thickness of 0.5 mm obtained in Example 1, one week after curing, the distance between fulcrums was 160 mm and the test speed was 5 mm / in accordance with JIS K7171 “Plastic-Bending Properties Test Method”. The three-point bending strength was measured under the conditions of minutes. The bending peel stress was 29 MPa, and the adhesive strength was a practically sufficient level.

[Summary of results]
As shown in Table 1 and Table 2, in Example 1 using an initiator diluent containing an epoxidized unsaturated fatty acid alkyl ester having 16 to 18 carbon atoms in the fatty acid portion and an organic peroxide, a comparative example was used. 1 to 4, the change in color of the initiator diluent over time (specifically, yellowing) is suppressed, and the initiator diluent prepared on the day can be used even if the initiator diluent stored for 3 months is used. A cured product having a desired color tone equivalent to that used was obtained.
Since the cured product obtained in Example 1 was not colored with the initiator diluent, it could exhibit the color of the pigment added to the main agent in accordance with the artificial marble to be bonded. Furthermore, since the cured product obtained in Example 1 contained an inorganic filler, it had a texture peculiar to marble.
When a plurality of artificial marbles are bonded using the two-component curing type methacrylic artificial marble adhesive composition obtained in Example 1, even if the initiator diluent is a time-lapse product, the artificial target to be bonded It has been shown that a seam that has the same color and texture as marble and that connects a plurality of artificial marbles continuously and without any sense of incongruity can be bonded with excellent aesthetics and adhesive strength.

  The present invention is not limited to the above-described embodiments and examples, and appropriate design changes can be made without departing from the spirit of the present invention.

Claims (5)

Main agent (I) 10 to 20 containing 75 to 95% by mass of syrup (S) containing methyl methacrylate and methyl methacrylate polymer (P) and 25 to 5% by mass of inorganic filler (F). Part by mass;
Two-component curing comprising an epoxidized unsaturated fatty acid alkyl ester (E) having 16 to 18 carbon atoms in the fatty acid portion and 1 part by weight of an initiator diluent (II) containing an organic peroxide (O) Type adhesive composition for methacrylic artificial marble.   The adhesive composition for methacrylic artificial marble according to claim 1, wherein the syrup (S) comprises 50 to 80% by mass of methyl methacrylate and 50 to 20% by mass of the methyl methacrylate polymer (P). .   The adhesive composition for methacrylic artificial marble according to claim 1 or 2, wherein the main agent (I) further comprises an amine compound (A).   The content of the inorganic filler (F) in the main agent (I) is 1/5 to 1/2 of the content of the inorganic filler in the artificial marble original plate to be bonded. 2. Adhesive composition for methacrylic artificial marble according to item 1. Mixing the main agent (I) and the initiator diluent (II) of the adhesive composition for methacrylic artificial marble according to any one of claims 1 to 4,
A method for bonding artificial marble, wherein a plurality of methacrylic artificial marbles are bonded using the obtained mixed solution.