JP2000080327A - Polyurethane resin for coating agent and coating agent composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane resin for a coating agent and a coating composition excellent in various properties such as adhesion, scratch-resistance, blocking resistance, flexibility resistance, etc., at all base materials including a polyolefinic base material, without using halogenic materials considering recent environmental problems and giving damage to workability such as a bad smell and to aspect of environment. SOLUTION: This polyurethane resin for a coating agent comprises polyurethane wherein a part or all of the resin used in a coating agent is obtained by reacting the following (A) to (D) and the glass transition temperature is 20-70 deg.C: (A) a long-chained polyol having a number-average molecular weight of 500-3,000, (B) an acrylic polyol having a number-average molecular weight of 5,000-30,000, (C) a chain extender not more than 20 of carbon numbers, and (D) an organic diisocyanate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane resin for a coating agent and a coating composition applicable to films of various materials. More specifically, plastic substrates used for plastic containers and building materials are being converted from polyvinyl chloride to polyolefins such as polypropylene and polyethylene due to environmental problems such as acid rain and global warming. ,
In other words, the present invention relates to a polyurethane resin for a coating agent and a coating agent composition for covering the abrasion resistance, which is an environment-friendly method which is compatible with PVC and covers the weakness of polyolefin.

[0002]

2. Description of the Related Art Polyolefin resins such as polypropylene and polyethylene have inferior abrasion resistance as compared with polyvinyl chloride. In order to improve this, it has been proposed to coat the surface of a polyolefin resin with an acrylic resin or the like as a protective layer. For example, JP-A-4-29
No. 4141 discloses a weight-average molecular weight of 1,000-1.
A technique is described in which after coating a coating agent obtained by mixing a 000 urethane acrylate prepolymer in a monofunctional acrylic monomer, the coating agent is cured by an electron beam to form a surface protective layer. .

However, the acrylic-urethane coating agent described in JP-A-4-294141 has excellent weather resistance, but does not have satisfactory scratch resistance. In addition, acrylic resins of the type cured by electron beams or ultraviolet rays have the advantage that raw materials are inexpensive, but electron beam irradiation equipment and ultraviolet irradiation equipment are indispensable conditions, and there are odor problems of acrylic monomers, etc. The workability and environmental aspects were not satisfactory either. An acrylic resin having two or more reactive functional groups in one molecule is cured with a polyisocyanate curing agent, so there is no problem in terms of odor, but there is a problem of compatibility with urethane resin, and a pot life. Had the disadvantage of being short.

[0004]

DISCLOSURE OF THE INVENTION The present invention does not use halogen-based raw materials in consideration of recent environmental problems, does not impair workability such as odor, and environmental aspects. It is an object of the present invention to provide a polyurethane resin for a coating agent and a composition for a coating agent, which are excellent in various physical properties such as adhesion to any base material, including scratch resistance, blocking resistance, and bending resistance.

[0005]

In view of the above circumstances, the present inventors have sufficiently satisfied the adhesion to general-purpose plastic films, especially polyolefin-based films, and
As a result of intensive studies on a polyurethane resin for a coating agent which is excellent in various physical properties such as abrasion resistance, blocking resistance, bending resistance, etc., and which is friendly to workability and environment, the present invention has been completed.

That is, the present invention provides the following (1) to (2)
It is. (1) Part or all of a resin used as a coating agent is obtained by reacting the following (A) to (D),
A polyurethane resin for a coating agent, which is a polyurethane resin having a glass transition temperature of 20 to 70 ° C. (A) a long-chain polyol having a number average molecular weight of 500 to 3,000. (B) Acrylic polyol having a number average molecular weight of 5,000 to 30,000. (C) a chain extender having 20 or less carbon atoms. (D) an organic diisocyanate.

(2) A coating composition comprising 100 parts by mass of the polyurethane resin for a coating agent of (1) and 1 to 20 parts by mass of a polyisocyanate curing agent.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The polyurethane resin used as the coating agent of the present invention has a glass transition temperature of 20.
To 70 ° C, preferably 30 to 60 ° C. When the glass transition temperature is lower than the lower limit, the blocking resistance is insufficient. If it exceeds the upper limit, the adhesion will be insufficient. In the application step, the anti-blocking property is one of the important properties of the resin for a coating agent, since the long material may be applied and then wound up.

The glass transition temperature of the polyurethane resin for a coating agent according to the present invention is a temperature at which E ″ (loss modulus) in dynamic viscoelasticity is maximized. : 35 Hz, heating rate: 2 ° C per minute.

The number average molecular weight of the polyurethane resin for a coating agent of the present invention is measured by a gel permeation chromatography (GPC) method using a polystyrene calibration curve, preferably from 5,000 to 100,0.
00, and particularly preferably 8,000 to 50,000. When the number average molecular weight is less than 5,000, the durability is reduced. When the number average molecular weight exceeds 100,000, workability such as fluidity is poor.

Next, the raw materials (A) to (D) of the polyurethane resin for a coating agent of the present invention will be described.
The long-chain polyol (A) used in the present invention has a number average molecular weight of 500 to 10,000, preferably 800 to 5,
000 polyester polyols, polyamide ester polyols, polycarbonate polyols, polyether polyols, polyether ester polyols, polyolefin polyols, animal and plant polyols, and the like. When the number average molecular weight of (A) the long-chain polyol is less than the lower limit, the solution viscosity of the obtained polyurethane resin becomes too high, and the workability tends to deteriorate. On the other hand, if it is less than the lower limit, the blocking resistance tends to deteriorate. In the present invention, a polyester polyol is preferred when adhesion is important, and a polycarbonate polyol is preferred when durability is important.

Examples of the polyester polyol include known phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, curtaconic acid, Azelaic acid, sebacic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, 1,4-
Cyclohexyldicarboxylic acid, α-hydromuconic acid,
one or more kinds of dicarboxylic acids or anhydrides such as β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α, β-diethylsuccinic acid, maleic acid, and fumaric acid; ethylene glycol; Propanediol, 1,3
-Propanediol, 1,2-butanediol, 1,3
-Butanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,8
-Octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, cyclohexane-1, 4
-Diol, cyclohexane-1,4-dimethanol,
Polycondensation with one or more low molecular polyols such as dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, trimethylolpropane, and pentaerythritol. Obtained from the reaction. Further, there are lactone-based polyester polyols obtained by ring-opening polymerization of cyclic ester (so-called lactone) monomers such as ε-caprolactone, alkyl-substituted ε-caprolactone, δ-valerolactone, and alkyl-substituted δ-valerolactone. Further, a part of the low molecular polyol may be a low molecular polyamine such as hexamethylenediamine, isophoronediamine, monoethanolamine, or a low molecular amino alcohol. In this case, a polyester-amide polyol is obtained. In the present invention, preferred polyester polyols are polyester polyols obtained from dicarboxylic acids having 2 to 10 carbon atoms and low molecular weight diols having 2 to 8 carbon atoms.

The polycarbonate polyol is obtained by a dealcoholation reaction or a dephenolization reaction of at least one of the above-mentioned low molecular weight diols and low molecular weight triols of the polyester polyol with ethylene carbonate, diethyl carbonate and diphenyl carbonate. In the present invention, a preferred polycarbonate polyol is a polycarbonate polyol obtained from a low molecular weight diol having 2 to 8 carbon atoms.

Examples of the polyether polyol include homopolymers and copolymers of epoxides such as ethylene oxide, propylene oxide, and tetrahydrofuran, and cyclic ethers.

The polyetherester polyol includes a copolyol obtained from the above-mentioned polyether polyol and the above-mentioned dicarboxylic acid. In addition, there are those obtained by the reaction of the above-mentioned polyester or polycarbonate with epoxide or cyclic ether.

Examples of the polyolefin polyol include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene.

The animal and plant polyols include castor oil polyols and silk fibroin.

The number average molecular weight is from 500 to 10,000.
0 and an average of at least one active hydrogen group in one molecule, epoxy resin, polyamide resin, polyester resin, acrylic resin, rosin in addition to dimer acid polyol and hydrogenated dimer acid polyol. resin,
Active hydrogen group-containing resins such as urea resins, melamine resins, phenol resins, coumarone resins, and polyvinyl alcohol can also be used.

The acrylic polyol (B) used in the present invention preferably has a number average molecular weight of 5,000 to 30,000, more preferably 8,000 to 28,000. The hydroxyl value is preferably 3 to 12 KOHmg / g, and further,
3.5 to 11.5 KOHmg / g. The average number of functional groups is preferably from 1 to 2.2, and more preferably from 1.5 to 2. When the number average molecular weight of the (B) acrylic polyol exceeds the upper limit, the obtained polyurethane resin is too hard, and the adhesion tends to be reduced. On the other hand, if it is less than the lower limit, the obtained polyurethane resin tends to have low blocking resistance. When the average number of functional groups is less than the lower limit, the molecular weight of the obtained polyurethane resin tends to be small, and the scratch resistance tends to be low. If the upper limit is exceeded, gelation is likely to occur during the production of the polyurethane resin.

(B) The acrylic polyol is obtained by a polymerization reaction of an unsaturated double bond-containing compound (acrylic monomer). Examples of the acrylic monomer include acrylates such as alkyl acrylate, cycloalkyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate, alkyl methacrylate, cycloalkyl methacrylate, phenyl methacrylate, and methacrylate. Benzyl acrylate, methacrylates such as glycidyl methacrylate, vinyl acetate, vinyl ester compounds such as vinyl propionate, vinyl alkyl ethers such as vinyl methyl ether, vinyl cyclohexyl ether, vinyl phenyl ether, vinyl benzyl ether, Vinyl ether compounds such as vinyl glycidyl ether, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, styrene, vinyl toluene, α-methylstyrene Aromatic compounds containing an ethylenically unsaturated double bond, maleic diesters such as dialkyl maleate, fumaric diesters such as dialkyl fumarate, itaconic diesters such as dimethyl itaconate, N, N-dimethylacrylamide Dialkyl acrylamides such as N-vinylpyrrolidone,
Heterocyclic vinyl compounds such as 2-vinylpyridine;
Hydroxyethyl acrylate, hydroxypropyl acrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, 2-
Ε-caprolactone adduct of hydroxyethyl acrylate, β-methyl-valerolactone adduct of 2-hydroxyethyl methacrylate, glycerol monoacrylate, acrylates such as glycerol diacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, Polyethylene glycol monoacrylate, polypropylene glycol monomethacrylate, ε of 2-hydroxyethyl methacrylate
-Caprolactone adducts, β-methyl-valerolactone adducts of 2-hydroxyethyl methacrylate, glycerol monomethacrylate, methacrylates such as glycerol dimethacrylate, allyl alcohol, glycerol monoallyl ether, allyl compounds such as glycerol diallyl ether, etc. No. Among these, preferred are 2-hydroxyethyl acrylate, ε-caprolactone adduct of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and β-methyl-valerolactone adduct of 2-hydroxyethyl methacrylate. Hydrogen group-containing ethylenically unsaturated monomers are mentioned. The acrylic polyol used in the present invention comprises two groups of acrylic monomers, an acrylic monomer selected from 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate, and an acrylic monomer selected from methyl acrylate and methyl methacrylate. Are preferred.

The content of the acrylic polyol (B) used in the present invention in the urethane resin is preferably 5 to 70%, more preferably 10 to 65%. If it is less than the lower limit, the resulting polyurethane resin has poor blocking resistance and scratch resistance. If the upper limit is exceeded, the glass transition point of the polyurethane resin becomes unnecessarily high, and cracks tend to occur in the coating film due to bending or the like.

The chain extender (C) used in the present invention has 20 or less carbon atoms and has two or more active hydrogen groups in one molecule. Specifically, low-molecular-weight polyols used for the above-mentioned polyester polyols, N-alkyldialkanolamines such as N-methyldiethanolamine, N-methyldipropanolamine, N-ethyldiethanolamine, N-phenyldiethanolamine, N-phenyl N-aryldialkanolamines such as dipropanolamine, N-alkyldialkanolamines such as N-methyldiethanolamine, N-methyldipropanolamine, N-ethyldiethanolamine, N-phenyldiethanolamine, N-phenyldipropanolamine And low-molecular-weight polyamines such as N-aryl dialkanolamines, and low-molecular-weight amino alcohols. These can be used as one kind or as a mixture of two or more kinds. Preferred chain extenders in the present invention are
An alicyclic diol and / or an alicyclic diamine having good solubility and capable of imparting durability, specifically, cyclohexane-1,4-diol and cyclohexane-
1,4-dimethanol, isophoronediamine, hydrogenated methylenebisaniline, hydrogenated xylylenediamine and the like, particularly cyclohexane-1,4-dimethanol,
Isophorone diamine is preferred.

The organic diisocyanate (D) used in the present invention includes 2,4-tolylene diisocyanate,
2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, 1,4-naphthylene diisocyanate, p- Phenylene diisocyanate, m-phenylene diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate,
Tetramethylxylylene diisocyanate, 4,4'-
Diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,
Aromatic diisocyanates such as 3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate; 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate,
Aliphatic diisocyanates such as lysine diisocyanate,
Alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tetramethyl xylylene diisocyanate, cyclohexyl diisocyanate, and mixtures of two or more of these, and organic diisocyanates thereof Any known organic diisocyanate, such as a urethane-modified, allophanate-modified, urea-modified, biuret-modified, uretdione-modified, uretoimine-modified, isocyanurate-modified, carbodiimide-modified, or the like may be used.

In the present invention, the isocyanate component preferably contains an aliphatic diisocyanate and / or an alicyclic diisocyanate in an amount of 50 to 100 mol%, particularly preferably 80 to 100 mol%. When the amount of the aliphatic diisocyanate and / or the alicyclic diisocyanate is less than the lower limit, the coating film is liable to yellow and the adhesion is reduced. Among the above organic diisocyanates, isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate are preferred.

Incidentally, a reaction terminator may be used if necessary. Examples of the reaction terminator include monoalcohols such as methanol and ethanol; monoamines such as ethylamine, propylamine and dibutylamine; aminoalcohols such as monoethanolamine, diethanolamine, N-methyldiethanolamine and N-phenyldipropanolamine. There is. In some cases, low-molecular polyols and low-molecular polyamines used for the above-mentioned polyester polyol and polyester-amide polyol can also be used.

As a reaction catalyst for synthesizing the polyurethane resin for a coating agent in the present invention, a known so-called urethanization catalyst can be used. Specific examples include organic metal compounds such as dibutyltin dilaurate and dioctyltin dilaurate; organic amines such as triethylenediamine and triethylamine; and salts thereof.

A known method is used for synthesizing the polyurethane resin for a coating agent of the present invention. That is, (1) an active hydrogen group component and an organic diisocyanate are
A method of reacting under a condition of an excess of active hydrogen groups until a predetermined molecular weight is reached (one-shot method); (2) a polyol component and an organic diisocyanate are reacted under a condition of an excess of isocyanate groups to obtain an isocyanate group-containing prepolymer; Next, there is a method (prepolymer method) of extending the chain of the prepolymer with a low molecular weight glycol or a low molecular weight diamine and reacting it until a predetermined molecular weight is reached.

An organic solvent can be used if necessary. This organic solvent is an aromatic hydrocarbon-based solvent such as toluene, xylene, pentane, hexane, an aliphatic hydrocarbon-based solvent such as octane, cyclopentane, cyclohexane, an alicyclic hydrocarbon-based solvent such as methylcyclohexane, acetone, Ketone solvents such as methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, methyl cyclohexanone, ether solvents such as diethyl ether, 1,4-dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether acetate, propylene Cellosolve solvents such as glycol dimethyl ether and propylene glycol monomethyl ether acetate; monobasic ester solvents such as ethyl acetate and butyl acetate; Phosphate, dimethyl succinate, dibasic esters such as dioctyl phthalate, dimethyl formamide, dimethyl acetamide, N
There is no particular limitation as long as it is inert to isocyanate groups such as -methylpyrrolidone. Depending on the conditions, an alcoholic solvent such as isopropanol can be used.

The reaction apparatus of the polyurethane resin for a coating agent of the present invention may be any apparatus as long as the above-mentioned reaction can be achieved. Examples thereof include a reaction vessel equipped with a stirrer, a kneader, and a single-screw or multi-screw extrusion reaction apparatus. A mixing and kneading apparatus is exemplified. A preferred method for synthesizing the polyurethane resin for a coating agent of the present invention is a prepolymer method in a solution.

The prepolymer method in a solution will be described in more detail. In producing the polyurethane resin for a coating agent, first, a raw material having an active hydrogen group is mixed, and if necessary, appropriately diluted with a ketone or ester having no active hydrogen group, a hydrocarbon solvent, or the like.

After adding an organic diisocyanate to the mixture of active hydrogen group components and, if necessary, a urethanation catalyst, the reaction temperature is increased to 30 to 100 ° C., preferably 50 to 100 ° C.
The reaction is carried out at 80 ° C. for several hours to synthesize an isocyanate group-containing urethane prepolymer solution. At this time, the molar ratio (R value) of isocyanate group / hydroxyl group is 1.1 to 2.5.
Is particularly preferable, and 1.1 to 2 are particularly preferable.

When the R value is less than 1.1, the durability and blocking resistance of the finally obtained polyurethane resin for a coating agent are reduced. When the R value exceeds 2.5, the solubility and adhesion of the finally obtained polyurethane resin for a coating agent in a solvent are reduced.

To the isocyanate group-containing urethane prepolymer solution thus obtained, a chain extender such as a low molecular weight glycol or a low molecular weight diamine and, if necessary, a reaction terminator are added, and the reaction temperature is raised to 30 to 80 ° C. The desired polyurethane resin for a coating agent is obtained by conducting a chain extension reaction at preferably 30 to 50 ° C. until the isocyanate group disappears.

The coating composition of the present invention is obtained by adding a pigment, a dye, a solvent, a thixotropic agent, an antioxidant, an ultraviolet absorber, an antifoaming agent, a thickener, a dispersant, Surfactants, fungicides, antibacterials, preservatives,
Additives such as catalysts and fillers, and auxiliary binders such as nitrified cotton are added, kneaded and dispersed, and a polyisocyanate curing agent is blended.

The amount of the polyisocyanate curing agent is 1 to 20 parts by mass based on 100 parts by mass of the polyurethane resin for a coating agent. As the polyisocyanate curing agent (in terms of each solid content), for example, products of Nippon Polyurethane Industry Co., Ltd., hexamethylene diisocyanate-modified coronate HX, coronate HL, tolylene diisocyanate-modified coronate L, coronate 2030, coronate 2031 and the like, and these may be used alone or as a mixture.

The coating composition of the present invention does not cause blocking even when wound up after being applied to a film or sheet, so that it can be stored in the form of a take-up roll, is excellent in workability, and has a good workability. Compared to the polyurethane resin coating agent, it was excellent in scratch resistance, bending resistance, and weather resistance, and was excellent in adhesion to all kinds of plastic films and sheets including polyolefin.

[0037]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In addition,
In the examples, "parts" indicates parts by mass, and "%" indicates% by mass.

Example 1 118 parts of polyol A, 89.5 parts of acrylic polyol, 34.4 parts of CHDM, 34.4 parts of MEK, and a reactor equipped with a stirrer, a thermometer, an Aline cooling tube, and a nitrogen gas introducing tube.
Was charged and stirred uniformly. 46.6 parts of IPDI, 55.0 parts of H ₁₂ MDI, and 0.06 parts of DBTDL were charged into the polyol solution, and reacted at 70 ° C. for 3 hours to obtain an isocyanate group-containing urethane prepolymer solution. Add MEK to this prepolymer solution
After adding 00 parts and making uniform, MEK was added to 246 parts and IPDA.
And 9.1 parts of MEA and 0.7 parts of MEA were added at once, and the mixture was reacted at 40 ° C. until the isocyanate group peak by FT-IR disappeared. I got PU-1 has a solid content of 30% and a viscosity at 25 ° C. of 2,200 mPa · s,
Number average molecular weight is 28,000, glass transition temperature is 30 ° C
Met.

Examples 2 to 6, Comparative Examples 1 to 4 Using the same apparatus and reaction method as in Example 1, using the raw material amounts shown in Tables 1 and 2, the polyurethane resin PU-2 to 6 for coating agent was used. , 7-10.

[0040]

[Table 1]

[0041]

[Table 2]

Examples 1-6, Comparative Examples 1-4, and Table 1,
The raw materials in 2 are shown below. Polyol A: Polyester diol composed of adipic acid and 3-methyl-1,5-pentanediol Number average molecular weight = 1,000 Polyol B: Polyester diol composed of adipic acid and 1,6-hexanediol Number average molecular weight = 1 Polyol C: Polycarbonate diol composed of 1,6-hexanediol and diphenyl carbonate Number average molecular weight = 2,000 MA-01: Methyl methacrylate / 2-hydroxyethyl acrylate acrylic polyol Number average molecular weight = 20,000 average Functional group number = 1.98 Toluene solution with a solid content of 40% CHDM: cyclohexane-1,4-dimethanol IPDI: isophorone diisocyanate H ₁₂ MDI: hydrogenated diphenylmethane diisocyanate IPDA: isophorone diamine MEA: Monoethanolamine DBTDL: Dibutyltin dilaurate MEK: Methyl ethyl ketone Number average molecular weight measurement method: Gel permeation chromatography method using a polystyrene calibration curve Glass transition temperature measurement method: Temperature at which E ″ in dynamic viscoelasticity is maximized Measurement conditions Frequency: 35 Hz Heating rate: 2 ° C. per minute Acrylic polyol content: Calculated from the charged amount.

[Evaluation of Coating Agent] Example 7 PU-1 was mixed in a container at a ratio shown below to obtain a coating agent A. The coating agent was evaluated for adhesion, blocking resistance, scratch resistance, weather resistance, and bending resistance. Coronate HL: Nippon Polyurethane Industry Co., Ltd. Adduct-modified polyisocyanate of hexamethylene diisocyanate

(1) Adhesion The coating agent A was printed at a printing speed of 20 with a gravure printing machine.
m / min, 15 μm thick so that the coating thickness after drying is 1 μm
Discharge treated surface of corona discharge treated stretched polypropylene (hereinafter abbreviated as OPP) film of m, corona discharge treated polyethylene terephthalate film of 15 μm thickness, corona discharge treated nylon film of 15 μm thickness Then, after aging at 40 ° C. for 7 days, a cellophane tape was stuck on the coated surface, and this was rapidly peeled off. Coating amount: 3 g / m ² evaluation by dry A: No coating film was peeled off. Good: 80% to 100% of the coating film remained. Δ: 50% to 80% of the coating film remained. X: Only 50% or less of the coating film remained.

(2) Blocking resistance The coating agent A was applied to the discharge-treated surface of the OPP film in the same manner as described above, and aged at 40 ° C. for 7 days. 24 hours,
Apply a load of 0.5 MPa with a blocking tester,
The blocking resistance was evaluated. Evaluation ：: Peeled off without any resistance when peeled off, and the coating surface did not fall off. Δ: The resistance when peeling was slightly large, and some of the coating surface dropped off. X: The resistance at the time of peeling is large, and the coating surface has fallen off.

(3) Scratch resistance The coating agent A was applied to the discharge-treated surface of the OPP film in the same manner as described above, and aged at 40 ° C. for 7 days.
After applying a load and sliding at a speed of 100 mm per minute, the surface roughness profile measuring machine Surfcom 570A manufactured by Tokyo Seimitsu Co., Ltd.
The abrasion resistance was evaluated.

(4) Weather Resistance The coating agent A was applied to the discharge-treated surface of the OPP film in the same manner as described above, aged at 40 ° C. for 7 days, allowed to stand at room temperature for 1 day, and After setting the panel in a QUV tester manufactured by PANEL and repeating the following cycle 10 times, a cellophane tape was stuck to the coated surface and this was rapidly peeled off. Condition of one cycle by QUV tester: 70 ° C. × 8 hours (Dry) + 50 ° C. × 4 hours (Wet) Coating amount: 3 g / m ² evaluation by dry ○: 80% to 100% of coating film remained. Δ: 50% to 80% of the coating film remained. X: Only 50% or less of the coating film remained.

(5) Flex resistance The coating agent A was applied to the discharge-treated surface of the OPP film in the same manner as described above, aged at 40 ° C. for 7 days, and allowed to stand at room temperature for 1 day. Was bent at 90 °, and the edge portion was evaluated with a microscope.

Examples 8 to 12 and Comparative Examples 5 to 8 Coating agents were prepared in the same manner as in Example 7 except that PU-1 in Example 7 was replaced with PU-2 to 10, and evaluation was performed in the same manner. did. The evaluation results of adhesion, blocking resistance, scratch resistance, weather resistance, and bending resistance are shown in Tables 3 and 4.
Shown in

[0050]

[Table 3]

[0051]

[Table 4]

In Tables 3 and 4, OPP: 15 μm thick corona discharge treated stretched polypropylene PET: 15 μm thick corona discharge treated polyethylene terephthalate NY: 15 μm thick corona discharge treated nylon

[0053]

As described above, the polyurethane resin for a coating agent of the present invention exhibits good adhesion to all kinds of plastic films, especially polyolefin films, and has good resistance after winding after film application. It was found to be excellent in blocking properties, scratch resistance when used as a building material, weather resistance, bending resistance, and the like.

Continued on the front page F term (reference) 4J034 BA07 BA08 CA03 CA04 CA05 CB03 CB04 CB05 CB07 CC03 CC08 CC12 CC23 CC26 CC45 CC52 CC61 CC62 CC65 CC67 CD01 CD04 DA01 DB03 DB07 DF02 DF11 DF12 DF16 DF17 DF20 DF21 DG29 DG29 DG29 DH02 DH06 DH10 DJ08 DJ09 DK00 DL01 DL09 DP13 DP17 DP18 EA12 EA14 EA18 GA05 GA06 GA23 GA33 GA55 HA01 HA02 HA07 HB06 HB07 HB08 HB09 HB11 HB12 HC03 HC09 HC12 JA13 HC17 HC22 HC25 HC26 HC34 HC35 HC44 HC46 HC52 HC61 KA01 KB02 KC17 KD02 KD12 KE02 PA03 QA05 QB03 RA07 4J038 DG051 DG052 DG061 DG062 DG101 DG102 DG111 DG112 DG121 DG122 DG131 DG132 DG161 DG162 DG171 DG172 DG191 DG192 J04 DG261

Claims (2)

[Claims] 1. A polyurethane resin which is obtained by reacting the following (A) to (D) and has a glass transition temperature of 20 to 70 ° C., wherein a part or all of the resin used as a coating agent is obtained. A polyurethane resin for a coating agent, which is characterized in that: (A) a long-chain polyol having a number average molecular weight of 500 to 3,000. (B) Acrylic polyol having a number average molecular weight of 5,000 to 30,000. (C) a chain extender having 20 or less carbon atoms. (D) an organic diisocyanate. 2. A coating composition comprising 100 parts by mass of the polyurethane resin for a coating agent according to claim 1 and 1 to 20 parts by mass of a polyisocyanate curing agent.