JP3008989B2 - Resin composition for coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for coating. More specifically, the present invention relates to a polyurethane resin-based coating resin composition having excellent light resistance, fingerprint resistance, and thermal stability and providing a tough coating film.

[0002]

2. Description of the Related Art In general, polyurethane resin-based coating agents mainly contain polyurethane obtained by reacting an aliphatic polyester polyol or polyether polyol with an organic polyisocyanate, and generally have a low glass transition temperature. Elongated resin is used.

[0003]

However, in various fields in recent years, there has been a strong demand for coating agents which are excellent in light resistance, stained by human fingerprints and excellent in thermal stability. For example, thermal dye sublimation transfer printers, inkjet printers, dye or pigment image receiving layer used for the image receiving paper of the hot-melt printer, storage stability,
Especially because the image is discolored by light, discoloration, etc., and because it is an application that touches the hand, contamination by fingerprints of the hand, traces, color loss, and blurring of the image after storage at high temperature and high humidity,
There is a need for a coating film that exhibits excellent effects on problems such as discoloration. However, it is difficult to obtain a polyurethane resin-based coating agent excellent in light resistance, fingerprint resistance, heat stability, and the like, using aliphatic polyester polyols and aliphatic polyether polyols that are conventional raw materials for polyurethane resins.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the above problems, and as a result, the specific polyurethane resin of the present invention has improved light resistance, fingerprint resistance and thermal stability. The present inventors have found that an excellent polyurethane-based coating agent can be obtained, and have reached the present invention.

That is, in the present invention, the dicarboxylic acid component is mainly composed of an aromatic dicarboxylic acid, and the glycol component is 20 to 100 mol% of the glycol represented by the general formula (1).
And a polyester polyol (a) composed of 0 to 80 mol% of a glycol having a reduced viscosity of 0.05 or more, an organic diisocyanate compound (b), and a chain extender (c) having an ether group and an active hydrogen group. A coating resin composition containing a polyurethane resin obtained by reacting isocyanate groups in a ratio of> 1.0 (equivalent ratio). General formula (1)

Embedded image (X ₁ and X ₂ are a hydroxyalkylene group having 1 to 10 carbon atoms and / or a group obtained by adding 1 to 10 moles of an alkylene oxide to a hydroxyalkylene group having 1 to 4 carbon atoms.)

The polyurethane resin of the present invention can be obtained by using a polyester polyol (a) and an organic diisocyanate compound (b) and a chain extender (c) having an ether group and active hydrogen. The carboxylic acid component of the polyester polyol (a) used in the present invention includes terephthalic acid, isophthalic acid, orthophthalic acid,
Aromatic dicarboxylic acids such as 2,3-naphthalic acid, 1,1,3-trimethyl-3-phenylindene-4 ′, 5-dicarboxylic acid, 5-sodium sulfoisophthalic acid, p
Aromatic carboxylic acids such as-(hydroxyethoxy) benzoic acid, aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, fumaric acid, maleic acid, tetrahydrophthalic acid, 1,4 -Unsaturated aliphatic and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; tri- and tetracarboxylic acids such as trimellitic acid and pyromellitic acid; Of these acid components, the aromatic dicarboxylic acid is preferably 70 mol% with respect to the total acid component. Desirable dicarboxylic acids include terephthalic acid, isophthalic acid, 1,1,3-trimethyl-3-phenylindene- 4 ', 5-dicarboxylic acid and 5-sodium sulfoisophthalic acid.

The glycol component of the polyester polyol (a) is a glycol represented by the following general formula (1). General formula (1)

Embedded image (X ₁ and X ₂ are a hydroxyalkylene group having 1 to 10 carbon atoms and / or a group obtained by adding 1 to 10 moles of an alkylene oxide to a hydroxyalkylene group having 1 to 4 carbon atoms.)

[0008] Of these, tricyclodecane dimethylol is preferred. Examples of the glycol component that can be used in combination with the tricyclodecane glycol represented by the general formula (1) include, for example, ethylene glycol, propylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, tripropylene glycol, 2,3,4. -Trimethylol-1,3-
Pentanediol, 1,6-hexanediol, 1,4
-Cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, ethylene oxide and / or pyropyrene oxide adduct of hydrogenated bisphenol A, 2,2-diethyl-1,3-propanediol,
2-n-butyl-2-ethyl-1,3-propanediol and the like. Of the above glycol components, glycols having 2 to 50 carbon atoms are preferred. The reduced viscosity of the polyester polyol (a) is 0.05 or more, preferably 0.05 to 0.4, and its glass transition temperature is 35 to
A temperature of 120 ° C. is desirable.

The organic diisocyanate compound (b) used in the present invention includes hexamethylene diisocyanate, tetramethylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate,
-Xylylene diisocyanate, m-xylylene diisocyanate, 1,3-diisocyanate-methylcyclohexane, 1,4-diisocyanatomethylcyclohexane, 4,4′-diisocyanate dicyclohexane,
4,4'-diisocyanate cyclohexylmethane, isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, 2,4-naphthalene diisocyanate, 3,4-naphthalene diisocyanate , 3'-dimethyl-4,
Examples include 4'-biphenylenediisocyanate, 4,4'-diisocyanate diphenyl ether, 1,5'-naphthalenediisocyanate, and the like.

The chain extender (c) having an ether group and an active hydrogen group used in the present invention includes polyethylene glycol, diethylene glycol, spiro glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A ethylene oxide adduct, and tripropylene. Glycols and the like. In the present invention, the number average molecular weight of the polyurethane resin obtained from the polyester polyol (a), the organic diisocyanate compound (b) and the chain extender (c) having an ether group and active hydrogen is 5,000 to 60,000, preferably 6
Glass transition temperature between 40 ° C and 80 ° C at 000-50,000
Less, urethane bond content is 500-4000 equivalent / 1
A resin is 0 ⁶ g. These chain extenders (C) having an ether group and active hydrogen can be used not only alone but also in a mixture of several kinds.

The polyurethane resin used in the present invention is produced in a known manner in a solvent at a reaction temperature of 20 to 150 ° C. in the presence or absence of a catalyst. As the solvent used at this time, for example, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, and esters such as ethyl acetate and butyl acetate can be used. As a catalyst for accelerating the reaction, amines, organotin compounds and the like are used. The coating resin composition of the present invention is generally used in a form in which the polyurethane resin is dissolved in a solvent,
It is customary to use a solid content at a concentration of about 5 to 70% by weight.

[0012] The coating resin composition of the present invention includes:
A known organic polyvalent isocyanate compound, a crosslinked product of an alkyl etherified aminoformaldehyde resin, an epoxy resin and the like can be blended. By blending and crosslinking the above-mentioned crosslinking agent, chemical resistance, solvent resistance and heat resistance can be further improved. Examples of the organic polyisocyanate compound used for such purposes include tetramethylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, alicyclic diisocyanates such as hydrogenated diphenylmethane diisocyanate, tolylene diisocyanate, and the like. Burette or isocyanate or isocyanurate trimer such as known diisocyanate such as aromatic diisocyanate such as xylylene diisocyanate or 4,4'-diphenylmethane diisocyanate, or adduct of 3 mole of diisocyanate compound and 1 mole of trifunctional polyol; Blocked isocyanate compounds in which these isocyanate groups are blocked can be used. As the blocking agent for the isocyanate group, known blocking agents such as phenol, ε-caprolactam, ethyl acetoacetate and methyl ethyl ketoxime can be used. Examples of the alkyl etherified amino formaldehyde resin include, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol and the like, formaldehyde or paraformaldehyde alkyl etherified with an alkyl alcohol having 1 to 4 carbon atoms such as urea, Condensation products with N, N-ethylene urea, dicyandiamide, aminotriazine, etc., specifically, methoxylated methylol urea, methoxylated methylol-N, N-
Ethylene urea, methoxylated methylol melamine, methoxylated methylol benzoguanamine, butoxylated methylol melamine, butoxylated methylol benzoguanamine and the like can be used. As the epoxy resin, for example, a known epoxy resin such as a diglycidyl ether of bisphenol A and a polymer thereof, a phenol or cresol novolak type epoxy resin can be used.

The coating resin composition of the present invention contains, in addition to the crosslinking agent, an extender pigment, a coloring pigment, a thixotropic agent, a surface smoothing agent, an antifoaming agent, a color separation preventing agent, and the like according to the purpose. be able to. In the production of the coating resin composition of the present invention, a method such as a roll coater, a gravure coater spray coating, and a dip coating is appropriately selected as a mixing and dispersing machine such as a roll mill, a blender, and a ball mill.

[0014]

EXAMPLES Hereinafter, the present invention will be described with reference to production examples and examples in order to specifically explain the present invention. In the Production Examples and Examples, “parts” means “parts by weight” and “%” means “% by weight”. The number average molecular weight of the produced polymer was measured by GPC, and the polymer composition was measured by 1 H-NMR. These results are shown in Tables 1 and 2. The measurement methods for light resistance, fingerprint resistance and heat resistance are as shown below, and the evaluation results are shown in Table 3.

(1) Production Example of Polyester Polyol 388 parts of dimethyl terephthalate and 376 parts of dimethyl isophthalate were placed in an autoclave equipped with a thermometer and a stirrer.
Parts, trimellitic anhydride 12 parts, tricyclodecane dimethylol 706 parts, neopentyl glycol 541 parts,
Charge 0.5 part of tetrabutoxytitanate, 150-
The mixture was heated at 220 ° C. for 240 minutes to perform transesterification, and then the temperature of the reaction system was raised to 250 ° C. in 30 minutes, and the pressure of the system was gradually reduced. After 45 minutes, the pressure was reduced to 0.3 mmHg or less. The reaction was continued to obtain a pale yellow transparent polyester polyol A. The number average molecular weight of the obtained resin was 4,000. Table 1 shows polyester polyols B to E obtained by the same production method.

(2) Preparation Example of Polyester Resin After transesterification was carried out with the same charge composition as polyester polyol C shown in Table 1, the reaction was carried out at 260 ° C. and 0.3 mm
A polycondensation reaction was carried out for 120 minutes or less under the condition of Hg or less to obtain a pale yellow transparent polyester resin P. The number average molecular weight of the obtained resin was 17000 and the glass transition temperature was 64.2 ° C.

(3) Production Example of Polyurethane Resin 100 parts of polyester polyol A having a number average molecular weight of 4000 obtained in Production Example of Polyester Polyol was placed in a reactor equipped with a thermometer, a stirrer, and a reflux condenser. After mixing and dissolving with 100 parts of toluene, 30 parts of polyethylene glycol (molecular weight: 400), 20.4 parts of isophorone diisocyanate and 0.02 of dibutyltin laurate were used.
Then, the mixture was reacted at 70 to 100 ° C. for 4 hours. Then, the reaction system was cooled to 70 ° C, and methyl ethyl ketone 17
The reaction was stopped by adding 5 parts and 75 parts of toluene. The number average molecular weight of F of the obtained polyurethane resin was 35,000, and the glass transition temperature was 45 ° C. Table 2 shows polyurethane resins G to L obtained by the same method.

(4) Density Evaluation Method of Printed Image The image receiving sheet and the thermal transfer sheet are overlapped so that the dyeing layer (dye receiving layer) and the color material layer are in contact with each other, and a thermal head is provided from the substrate side of the thermal transfer sheet. Thus, heating was performed at a head output of 0.7 W / dot, a head heating time of 8 ms, and a dot density of 3 dots / mm to transfer the cyan dye in the color material layer to the dye layer. The resulting transferred image density was measured with a reflection densitometer (DM-600, manufactured by Dainippon Screen Co., Ltd.).

(5) Evaluation method of light fastness The energy given by the xenon lamp at 40 ° C. to the image receiving sheet to which the cyan dye has been transferred is 6
Irradiation was performed at 7.0 KJ / m ^2, and the results were shown in terms of dye concentration retention (%) in comparison with the concentration before the light resistance test.
Dye concentration retention rate (%) = (density after light resistance test / density before light resistance test) × 100

(6) Evaluation method of heat resistance (dark discoloration rate) The image receiving body to which the cyan dye has been transferred is left for 168 hours in an environment of 60 ° C. in a dark place, aged, and subjected to aging to determine the density before the heat resistance test. And the dye concentration retention rate (%) in the comparison of.

(7) Evaluation Method of Fingerprint Resistance The thumb is strongly pressed against the surface of the image receiving body onto which the cyan dye has been transferred so that the fingerprint remains on the image surface, and is left under an environment of 40 ° C. for 48 hours. Aggregation, color loss, and fingerprint traces of the cyan dye were observed. After aging, the sample having no color change on the surface of the image receiving layer and having no change in color was evaluated as ○, the sample with no color change but with fingerprint trace remaining was evaluated as △, and the sample in which the dye aggregated on the image surface was evaluated as ×.

Example 1 A polyurethane resin D for a receiving layer was diluted with a mixed solvent of toluene: methyl ethyl ketone = 50: 50,
% Solution. An epoxy-modified silicone oil (KF-102, manufactured by Shin-Etsu Chemical) was added to this solution for 1 part of the above resin.
0% by weight and 4 μm on a 150 μm-thick synthetic paper (manufactured by Oji Yuka: YUPO PPG-150) using a wire bar.
m so as to obtain a dried coating film of m. The sheet was dried in an atmosphere at 120 ° C. for 30 minutes to obtain a dyeing layer (dye receiving layer).

Example 2 Dyeing layers were formed using polyurethane resins E to G in the same manner as in Examples, and Examples 2 to 4 were obtained.

Comparative Example 1 Using a polyurethane resin I, a dyeing layer was provided in the same manner as in Example 1 to obtain Comparative Example 1. Comparative Example 2 Using a polyester resin P containing no urethane group bond,
A dyeing layer was provided in the same manner as in Example 1 to obtain Comparative Example 2. Comparative Example 3 A dyeing layer was provided in the same manner as in Example 1 by using a polyurethane resin H using neopentyl glycol containing no ether group as a chain extender, and Comparative Example 3 was provided.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

According to the present invention, a coating resin composition containing a specific tricyclic glycol represented by the general formula (1) and a specific composition polyurethane resin containing an ether group as a chain extender as a main component is: , A tough coating film can be formed, and the obtained coating film exhibits not only high light resistance, but also excellent characteristics in fingerprint resistance and thermal stability, and is a binder for sublimation type thermosensitive recording paper. It is industrially useful as a coating layer.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-190983 (JP, A) JP-A 64-51474 (JP, A) JP-A 4-153210 (JP, A) JP-A 62-190 109813 (JP, A) JP-A-4-67313 (JP, A) JP-A-4-188428 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 175/04

Claims (1)

(57) [Claims] The reduced viscosity of the dicarboxylic acid component is mainly composed of an aromatic dicarboxylic acid, and the glycol component is composed of 20 to 100 mol% of a glycol represented by the general formula (1) and 0 to 80 mol% of another glycol. The polyester polyol (a), the organic diisocyanate compound (b) and the chain extender (c) having an ether group and an active hydrogen group are reacted at a ratio of active hydrogen group / isocyanate group> 1.0 (equivalent ratio). A coating resin composition comprising the obtained polyurethane resin. General formula (1) (X ₁ and X ₂ are a hydroxyalkylene group having 1 to 10 carbon atoms and / or a group obtained by adding 1 to 10 moles of an alkylene oxide to a hydroxyalkylene group having 1 to 4 carbon atoms.)