JP3002506B2 - Thermosetting composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is a thermosetting resin having excellent hardness, aesthetic properties, solvent resistance, weather resistance and flexibility, and good acid resistance and abrasion resistance. Composition.

[Conventional technology and its problems] Conventionally, formation of a coating film using a radical polymerizable unsaturated group-containing oligomer requires the use of a photosensitizer and ultraviolet irradiation in combination,
It has been considered that a cured film obtained by heating cannot provide a cured film having good hardness, solvent resistance, weather resistance and the like.

However, we have found that even with heat curing,
If the radical polymerizable oligomer has a specific bond and has a certain molecular weight or more, it can exhibit hardness and weather resistance as seen in an acrylic resin, and has low acid resistance in a melamine crosslinked system. It was also found that good results were obtained with respect to the properties and the scratch resistance.

That is, an object of the present invention is to provide a thermosetting composition having excellent hardness, aesthetic properties, solvent resistance, weather resistance, flexibility, and good acid resistance and scratch resistance. is there.

[Means for Solving the Problems] The gist of the present invention is to provide (a) an aliphatic and / or alicyclic urethane (meth) acrylate containing three or more (meth) acryloyl groups in one molecule. A mixture of a component A having a glass transition temperature of 40 ° C. or lower and a component B having a glass transition temperature of 60 ° C. or higher as determined by dynamic viscoelasticity measurement.
(B) a radical polymerizable compound having a molecular weight of 300 or more, containing three or more (meth) acryloyl groups in one molecule, containing no urethane bond, and having a molecular weight of 300 or more. And (c) 0.1 to 3.0 parts by weight of a radical polymerizable initiator per 100 parts by weight of the total of the components (a) and (b), and an acrylic having a carboxyl group and a hydroxyl group. A thermosetting composition comprising a copolymer (B) and a curing agent (C) selected from an amino resin and a polyisocyanate.

Aliphatic and / or alicyclic urethane (meth) acrylates (a) containing three or more (meth) acryloyl groups in one molecule as the first component of the composition (A) include triisocyanate alone, diisocyanate, It can be synthesized by reacting a polyisocyanate, such as an adduct of triisocyanate with burette, multimer, or polyol, and a hydroxyl group-containing monomer. Glass transition temperature of the urethane (meth) acrylate polymer (hereinafter referred to as Tg)
Can be determined from the dynamic viscoelasticity of a crosslinked cured coating film and the maximum value of the temperature dispersion curve. In the present invention, the Tg obtained by mixing the component A which is a urethane (meth) acrylate having a Tg of 40 ° C. or less and the component B which is a urethane (meth) acrylate having a Tg of 60 ° C. or more is 40 to 100 ° C.
The composition of the composition becomes the composition (a). The glass transition temperature of component A exceeds 40 ° C., or the glass transition temperature of component B is
If the temperature is lower than 60 ° C, the appearance is not sufficient. Component A or component B
Alone results in insufficient flexibility. In addition, it is necessary to adjust the glass transition temperature of the composition (a) in the range of 40 to 100 ° C. If the temperature is lower than 40 ° C, the solvent resistance and the abrasion resistance decrease, and if it exceeds 100 ° C, the weather resistance decreases.
The range of use is 50 to 100 parts by weight, and less than 50 parts by weight is not preferable because the weather resistance is reduced.

Specific examples of the polyisocyanate include ethylene diisocyanate, 1,2-diisocyanatopropane, 1,3-diisocyanatopropane, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, lysine isocyanate, and 4,4′-methylene bis. (Cyclohexyl) isocyanate, methylcyclohexane 2,4-diisocyanate, methylcyclohexane 2,6-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate, trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, dimer acid diisocyanate, etc. Examples thereof include simple substances of diisocyanate and triisocyanate, burettes and multimers thereof, and adducts thereof with polyols. Specific examples of the polyol used for the adduct include ethylene glycol, propylene glycol, butylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene glycol, trimethylolpropane, polytrimethylolpropane, pentaerythritol, and polypentane. Examples include alcohols such as erythritol, sorbitol, mannitol, glycerin, and polyglycerin, polyether polyols, polyester polyols synthesized from polyhydric alcohols and polybasic acids, and polyester polyols such as polycaprolactone polyol.

Examples of the hydroxyl group-containing vinyl monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. , Adducts of 2-hydroxyethyl (meth) acrylate and ethylene oxide, 2-hydroxyethyl (meth)
Examples include adducts of acrylate and propylene oxide, and adducts of 2-hydroxyethyl (meth) acrylate and organic lactones such as adducts of 2-hydroxyethyl (meth) acrylate and ε-caprolactone.

Component A, which is an aliphatic and / or alicyclic urethane (meth) acrylate such that the glass transition temperature of the cured coating film is 40 ° C. or less, includes isophorone diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, and the like. Can be obtained by reacting polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene glycol, polycaprolactone diol, or the like with the above-mentioned hydroxyl-containing vinyl monomer.

Component B which is an aliphatic and / or alicyclic urethane (meth) acrylate having a glass transition temperature of 60 ° C. or higher of the cured coating film is ethylene diisocyanate, 1,2-
Diisocyanatopropane, 1,3-diisocyanatopropane, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, lysine isocyanate,
4,4'-methylenebis (cyclohexyl) isocyanate, methylcyclohexane 2,4-diisocyanate, methylcyclohexane 2,6-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate, trimethylhexamethylene diisocyanate, tetramethylene diisocyanate A diisocyanate such as dimer acid diisocyanate, a triisocyanate simple substance, a burette, a polymer thereof, and the like, by reacting a diol having 4 or less carbon atoms such as ethylene glycol and propylene glycol with the hydroxyl group-containing vinyl monomer. Can be.

The reaction between the polyisocyanate and the hydroxyl group-containing monomer is performed using a tin-based catalyst such as dibutyltin dilaurate so that the isocyanate and the hydroxyl group are substantially equal in amount.
Finish by heating at 70 ° C for several hours.

The radical polymerizable compound (b), which is the second component of the composition (A), has a molecular weight of 300 or more and has no urethane bond, and the component (a) and the ( 0 to 50 parts by weight, preferably 10 to 40 parts by weight, is added to 100 parts by weight of the total amount of the component (b). If it exceeds 50 parts by weight, the weather resistance decreases, which is not preferable. Specifically, phthalic acid, polybasic acids such as adipic acid and ethylene glycol,
Polyester poly (meth) obtained by reaction of polyhydric alcohol such as butanediol and (meth) acrylic acid compound
Acrylate, epoxy poly (meth) acrylate obtained by reaction of epoxy resin with (meth) acrylic acid compound, polysiloxane poly (meth) acrylate obtained by reaction of polysiloxane with (meth) acrylic acid compound, polyamide and ( Polyamide poly (meth) acrylate obtained by reaction with a (meth) acrylic acid compound is exemplified.

The radical polymerization initiator (c) is added in the composition (A) of the present invention in an amount of 0.1 to 3.0 parts by weight based on 100 parts by weight of the total of the components (a) and (b). If the amount is too high, sufficient coating film hardness cannot be obtained, and if it exceeds 3.0 parts by weight, the stability of the coating material is lowered, which is not preferable. Examples of the polymerization initiator used here include benzoyl peroxide, cumene hydroperoxide, di-t-butyl hydroperoxide, dicumyl peroxide, t-butyl peracetate, t-butyl perbenzoate, t-butyl perbenzoate,
Peroxides such as -butylhydroperoxide, azobisisobutyronitrile, 2,2-azobis (2-methylbutyronitrile), 1,1-azobis (cyclohexane-1)
-Carbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), and azo-based compounds such as 2,2-azobis (2-methylpropane) are not particularly limited.

Next, the components (B) and (C) will be described. In the formation of a coating film, the composition (A) alone cannot provide sufficient characteristics such as sag controllability, adhesion to a substrate or a painted surface, and the components (B) and (C) are used in the composition ( This problem can be effectively ameliorated by mixing with A).

The carboxyl group in the acrylic copolymer serving as the component (B) functions as a catalyst, and the hydroxyl group functions as a crosslinking point.
The curing reaction proceeds with the amino resin or polyisocyanate (C) as a crosslinking agent.

As the monomers constituting the acrylic copolymer (B), a carboxyl-containing vinyl monomer and a hydroxyl group-containing vinyl monomer are used, and specific examples of the carboxyl group-containing vinyl monomer include (meth) acrylic acid, itaconic acid,
Fumaric acid, crotonic acid, maleic acid, monomethyl itaconate, monobutyl itaconate, monomethyl maleate,
Monobutyl maleate and the like can be mentioned. Specific examples of the hydroxyl group-containing vinyl monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Alkyl (meth) acrylates, 2
2-hydroxyethyl (adduct of 2-hydroxyethyl (meth) acrylate and ethylene oxide, adduct of 2-hydroxyethyl (meth) acrylate and propylene oxide, adduct of 2-hydroxyethyl (meth) acrylate and ε-caprolactone, etc.) And adducts of (meth) acrylates and organic lactones. Further, other copolymerizable vinyl monomers include styrene, α-methylstyrene, styrene derivatives such as vinyltoluene,
Polymerizable unsaturated nitriles such as (meth) acryloyl nitrile; vinyl esters such as vinyl acetate and vinyl propionate; N-methoxymethyl (meth) acrylamide;
N-alkoxy-substituted amides such as ethoxymethyl (meth) acrylamide and N-butoxymethyl (meth) acrylamide, and epoxy groups such as glycidyl (meth) acrylate, (meth) allyl glycidyl ether, and metaglycidyl (meth) acrylate. Containing monomer,
Basic monomers such as dimethylaminoethyl (meth) acrylic acid and diethylaminoethyl (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate; t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth)
Lauryl acrylate, dodecyl (meth) acrylate,
(Meth) acrylic esters such as stearyl (meth) acrylate are exemplified.

The method for polymerizing the acrylic copolymer (B) in the present invention includes a solution polymerization method, a bulk polymerization method, an emulsion polymerization method,
Any known polymerization method may be used, but a solution polymerization method is particularly desirable. In the case of solution polymerization, the monomer mixture is copolymerized in the presence of an organic solvent and a polymerization initiator.

Specific examples of the amino resin as the component (C) include aminotriazine, urea, dicyandiamide, methylolated N, N-ethylene urea, cyclohexanol or a compound having 1 carbon atom.
And alkyl etherified with up to 6 alkanols, particularly those obtained from aminotriazines,
For example, methyl etherified melamine resin, butyl etherified melamine resin and the like are suitable.

The polyisocyanate compound used as the component (C) is a compound having two or more isocyanate groups in one molecule, and specifically, a di (or tri) isocyanate compound such as tetramethylene diisocyanate , Hexamethylene diisocyanate, decamethylene diisocyanate, ethylene diisocyanate, isophorone diisocyanate, aliphatic isocyanate such as lysine diisocyanate, xylylene diisocyanate, methyl xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, 4,4'-
Aromatic isocyanates such as methylene bis (phenyl isocyanate), 3,3'-diisocyanate 1,4-dimethylbenzene, and triphenylmethane diisocyanate;
And alicyclic isocyanates such as 1-methyl-2,4-diisocyanate cyclohexanone, 4,4-methylenebis (cyclohexyl isocyanate) and cyclohexane diisocyanate, and hexamethylene diisocyanate isocyanurate.

The addition ratio of the components (B) and (C) can be arbitrarily selected according to the purpose and is not particularly limited. However, the weight ratio of (B) / (C) is 10/90 to 95 / 5, especially 60 / 40-90
A range of / 10 is preferred.

As the mixing ratio of the components (A), (B) and (C), A / (B + C) is usually used in a weight ratio of 90/10 to 20/80. In addition, 80/2 in terms of curing speed and coating film performance
0 to 50/50 is preferred. Generally, when it is larger than 90/10, there is a tendency that return to the clear layer of the base layer tends to occur,
On the other hand, when the ratio is less than 20/80, the coating film performance tends to decrease.

The thermosetting composition of the present invention can be realized by curing conditions at 100 ° C. or higher for 15 to 45 minutes. The cured product of the composition of the present invention is excellent in hardness, aesthetics, weather resistance, solvent properties, and has good acid resistance and abrasion resistance. Therefore, the inorganic substance (iron plate, tin plate, galvanized sheet, aluminum plate) It is useful as a paint or coating agent for surfaces of sheets, zinc steel sheets, roof tiles, etc. and organic substances (wood, paper, plastics, coatings of organic paints, etc.).

Further, if necessary, a surface conditioner, a repelling inhibitor, an ultraviolet absorber, an antioxidant, an organic solvent, other additives, and the like can be added.

 Hereinafter, the present invention will be described in detail with reference to Examples.

<Measurement method of glass transition temperature> A dynamic viscoelasticity meter (RHEOVIBRON manufactured by Toyo Baldwin Co., Ltd.) was applied to a coating film having a dry film thickness of 100 μm baked at 140 ° C. for 40 minutes.
The glass transition temperature was determined by reading the temperature at the maximum value of the dynamic viscoelastic temperature dispersion curve using DDV-II-EP).

<Production example of urethane (meth) acrylate (a) -1> 1 mol of hexamethylene diisocyanate buret and 0.002 mol of dibutyltin dilaurate were added to a reaction vessel, and the temperature was raised to 70 ° C.
Mol was added dropwise for 1 hour, and then reacted at the same temperature for 3 hours. Further, 3 mol of pentaerythritol triacrylate was added dropwise for 1 hour. After the addition, the mixture was further reacted for 5 hours. (Meth) acrylate (a) -1 was obtained.

<Production example of urethane (meth) acrylate (a) -2> Instead of hexamethylene diisocyanate buret, isophorone diisocyanate buret and dibutyltin dilaurate are 0.001 mol instead of 0.002 mol,
A urethane (meth) acrylate (a) -2 having a glass transition temperature of 94 ° C. was obtained in the same manner as in Production Example 1 except that 2-hydroxypropyl acrylate was used instead of polybutylene glycol.

<Production example of urethane (meth) acrylate (a) -3> 1 mol of hexamethylene diisocyanate buret and 0.002 mol of dibutyltin dilaurate were added to a reaction vessel, and after heating to 70 ° C, 3 mol of propylene glycol was added for 1 hour. And then reacted at the same temperature for 3 hours.
Further, 3 mol of 2-hydroxypropyl methacrylate was added dropwise over 1 hour, and after the addition, the mixture was allowed to react for another 5 hours to obtain a urethane (meth) acrylate (a) having a glass transition temperature of 62 ° C.
-3 was obtained.

<Production example of urethane (meth) acrylate (a) -4> Dibutyltin dilaurate was added to 0.02 mol instead of 0.002 mol.
Urethane having a glass transition temperature of 56 ° C. in the same manner as in Production Example 1 except that 01 mol and 1 mol of polybutylene glycol are replaced with 3 mol of butylene glycol and 2-hydroxybutyl acrylate instead of pentaerythritol triacrylate. (Meth) acrylate (a)
-4 was obtained.

<Production Example of Urethane (meth) acrylate (a) -5> Production Example-2 except that 3 mol of polyethylene glycol is used instead of 1 mol of polybutylene glycol and 2-hydroxypropyl methacrylate is used instead of 2-hydroxypropyl acrylate. In the same manner as in the above, urethane (meth) acrylate (a) -5 having a glass transition temperature of 49 ° C.
I got

<Production Example of Urethane (meth) acrylate (a) -6> Instead of hexamethylene diisocyanate buret, trimer of hexamethylene diisocyanate, 0.001 mol of dibutyltin dilaurate instead of 0.002 mol, and 1 mol of polybutylene glycol were used. 3 moles instead
A urethane (meth) acrylate (a) -6 having a glass transition temperature of 27 ° C was obtained in the same manner as in Production Example 1 except that 2-hydroxyethyl acrylate was used instead of pentaerythritol triacrylate.

<Production Example of Urethane (meth) acrylate (a) -7> Instead of hexamethylene diisocyanate trimer, 2 mol of hexamethylene diisocyanate and polybutylene glycol are used instead of 3 mol, and 3 mol of 2-hydroxyethyl acrylate are used. A urethane (meth) acrylate (a) -7 having a glass transition temperature of 38 ° C was obtained in the same manner as in Production Example-6 except that 2 mol was used instead.

<Production Example of Acrylic Copolymer (B)> 53.3 parts by weight of Solvesso # 100 was added to a container equipped with a stirrer, a temperature controller, and a condenser. Then, the temperature was increased to 120 ° C. while stirring, and 2 parts by weight of azobisisobutyronitrile and 2 parts by weight of t-butylperoxyisopropyl carbonate were added to 100 parts by weight of the following monomer mixture and mixed for 3 hours. It was dropped. Then
With stirring, 0.1 parts by weight of azobisisobutyronitrile was added four times at 30 minute intervals. Further, after heating and stirring at 120 ° C. for 2 hours to increase the reaction rate, n-butyl acetate was added.
After adding 3.3 parts by weight, the reaction was terminated to obtain an acrylic copolymer (B).

(Monomer mixture) Styrene 26 parts by weight Methacrylic acid 2 parts by weight n-butyl methacrylate 20 parts by weight t-butyl methacrylate 5 parts by weight 2-ethylhexyl methacrylate 29 parts by weight 2-hydroxyethyl methacrylate 18 parts by weight <(B) component and (C) Production Example of Mixture of Components)> The components (B) and (C) were mixed at the following compounding ratio to obtain mixtures (1) and (2).

<Examples 1 to 7, Comparative Examples 1 to 8> After degreasing a steel sheet, the various compositions shown in Table 1 were used.
Each of the steel sheets was coated so as to have a dry film thickness of 35 μm, left at room temperature for 10 minutes, and baked under the curing conditions shown in Table 1. The coating film performance evaluation results of the obtained coating film are as shown in Table 2, and those of the examples were higher in hardness, cosmetics, solvent resistance, weather resistance, flexibility, Both were excellent in acid resistance and scratch resistance.

[Effects of the Invention] As described in detail above, the composition of the present invention can be cured by heat, and the resulting cured coating film has hardness, cosmetic properties, solvent resistance, weather resistance, flexibility, It is excellent in acid resistance and scratch resistance, and its industrial significance is extremely high.

Continuation of the front page (56) References JP-A-55-3488 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 18/62, 18/67 C08L 33/06-33 / 14 C08L 61/20-61/32

Claims (1)

(57) [Claims] (A) An aliphatic and / or alicyclic urethane (meth) acrylate containing at least three (meth) acryloyl groups in one molecule, and a glass transition temperature of a cured coating film by dynamic viscoelasticity measurement. A and 60 ° C so that
50 to 100 parts by weight of a mixture comprising component B as described above and having a glass transition temperature of 40 to 100 ° C., (b) urethane containing three or more (meth) acryloyl groups in one molecule, 0 to 50 parts by weight of a radical polymerizable compound having a molecular weight of 300 or more containing no bond, and (c) a radical polymerizable initiator in an amount of 0.1 to 0.1 parts by weight based on 100 parts by weight of the total amount of the components (a) and (b). A thermosetting composition comprising a composition (A) consisting of at least 3.0 parts by weight, an acrylic copolymer (B) having a carboxyl group and a hydroxyl group, and a curing agent (C) selected from an amino resin and a polyisocyanate. Composition.