JP3036042B2 - Polyurethane resin - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyurethane resin. More specifically, the present invention relates to a polyurethane resin which is excellent as a coating agent which is excellent in heat resistance and light resistance and gives a tough coating film.

(Prior art) Generally, polyurethane resin-based coating agents are mainly composed mainly of 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.

(Problems to be Solved by the Present Invention) However, in recent years, in various fields, a coating agent having a high glass transition temperature and providing a tough coating film has been strongly demanded.

For example, the glass transition temperature is high with respect to the back coat layer of thermal ribbon tape used for computers, word processors, etc., the binder of sublimation type thermosensitive recording paper used for video color printers, or the back coat layer of magnetic tape, etc. An excellent coating film is required.

However, it is difficult to produce a polyurethane having a high glass transition temperature with an aliphatic polyester polyol or an aliphatic polyether polyol which is a raw material of a conventional polyurethane resin.

(Means for Solving the Problems) In view of the above problems, the present inventors have conducted intensive studies, and as a result, the dicarboxylic acid component is mainly composed of an aromatic dicarboxylic acid, and the glycol component is represented by the following general formula (I). 30 to 100 mol% of glycol and 70 to 0 of other glycol
The present inventors have found that a polyurethane resin-based coating agent having a high glass transition temperature can be obtained by using a polyester polyol consisting of mol%, 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 composed of 30 to 100 mol% of a glycol represented by the general formula (I) and 70 to 0 mol% of other glycols. The polyester polyol (a), the organic diisocyanate compound (b) and, if necessary, a chain extender (c) having an active hydrogen group are combined with (a) + (c) active hydrogen groups / isocyanate groups> 1.0 (equivalent ratio) Is a polyurethane resin obtained by reacting at a compounding ratio of

The carboxylic acid component of the polyester polyol (a) used in the present invention includes terephthalic acid, isophthalic acid,
Orthophthalic acid, 2,6-naphthalic acid, 1,1,3-trimethyl-3-phenylindene-4 ', 5-dicarboxylic acid, 5-
Aromatic dicarboxylic acids such as sodium sulfoisophthalic acid; aromatic oxycarboxylic acids such as p- (hydroxyethoxy) benzoic acid; aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid and dodecanedicarboxylic acid; Fumaric acid, maleic acid, tetrahydrophthalic acid, unsaturated aliphatic and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, trimellitic acid,
Examples thereof include tri- and tetracarboxylic acids such as pyromellitic acid.

Of these acid components, the aromatic dicarboxylic acid is preferably 70 mol% based on the total acid components. Desirable carboxylic acids include terephthalic acid, isophthalic acid, 1,1,3
-Trimethyl-3-phenylindene-4'5-dicarboxylic acid.

The glycol component of the polyester polyol (a) is represented by the following general formula (I) Among the glycols of the general formula (I), a hydroxyalkylene group having 1 carbon atom is most preferred from the viewpoint of heat resistance and light resistance.

That is, it is most preferred that it is composed of 30 to 100 mol% of tricyclodecane dimethylol and 0 to 70 mol% of another glycol.

Examples of the glycol component that can be used in combination with the tricyclodecane dimethylol represented by the general formula (I) include, for example, ethylene glycol, propylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,3,4-trimethyl-1,3. -Pentanediol, 1,
6-hexanediol, 1,4-cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, ethylene oxide and / or propylene oxide adduct of hydrogenated bisphenol A, 2,2-diethyl-1,3-propanediol, 2-n -Butyl-2-ethyl-1,3-propanediol, spiro glycol, polytetramethylene glycol and the like. The reduced viscosity of the polyester polyol (a) needs to be 0.15 or more, preferably 0.15 to 0.4, and its glass transition temperature is 50 ° C to 12 ° C.
The temperature is preferably 0 ° C, and more preferably 70 to 120 ° C from the viewpoint of blocking resistance.

Since the polyester polyol (a) used in the present invention uses the compound of the general formula (I) as a glycol component, the polyester polyol (a) has a higher glass transition temperature and is superior in light resistance as compared with the case where another glycol is used. . When the proportion of the compound of the formula (I) in the total glycol component is less than 30 mol%, the effect is small.

Examples of the organic diisocyanate compound (b) used in the present invention include hexamethylene diisocyanate, tetramethylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 3-diisocyanate-methylcyclohexane, 4,4'-diisocyanatedicyclohexane, 4,4'-diisocyanatecyclohexylmethane, isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-phenylene diisocyanate, diphenylmethane Diisocyanate, m-phenylene diisocyanate, 2,4-naphthalene diisocyanate, 3,
3'-dimethyl-4,4'-biphenylene diisocyanate, 4,4'-diisocyanate diphenyl ether, 1,
5'-naphthalenediisocyanate and the like.

In the present invention, examples of the chain extender (c) having an active hydrogen group used as necessary include ethylene glycol, propylene glycol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, diethylene glycol, Glycols such as spiro glycol and polyethylene glycol, and amines such as ethylene diamine, propylene diamine, and hexamethylene diamine.

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 active hydrogen group used as required is 5,000 to 60,000, preferably 6,000-50,000, glass transition temperature 80-150 ℃,
The resin has a urethane bond content of 500 to 4,000 equivalents / 10 ⁶ g.

The polyurethane resin of the present invention is a known method in a solvent.
It is produced in the presence or absence of a catalyst at a reaction temperature of 20 ° C to 150 ° C. 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.

When the polyurethane resin of the present invention is used as a coating agent, it is generally used in a form in which the above polyurethane resin is dissolved in a solvent.
It is customary to use it in the order of% by weight.

The coating agent may be mixed with a known crosslinking agent such as an organic polyisocyanate compound, an alkyl etherified aminoformaldehyde resin, or an epoxy resin.
Chemical resistance by blending the above crosslinking agent and crosslinking,
Solvent resistance and heat resistance can be further improved. Examples of the organic polyvalent isocyanate compound used for such purposes include, for example, alicyclic diisocyanates such as tetramethylene diisocyanate, water-flowed tolylene diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate; Burette or isocyanurate trimer such as known diisocyanate such as aromatic diisocyanate such as diisocyanate and 4,4'-diphenylmethane diisocyanate, or adduct of 3 mole of diisocyanate compound and 1 mole of trifunctional polyol and isocyanate thereof A blocked isocyanate compound in which a group is blocked can be given. As the blocking agent for the isocyanate group, a known blocking agent such as phenol, ε-caprolactam, ethyl acetoacetate and methyl ethyl ketoxime is used. Examples of the alkyl etherified aminoformaldehyde resin include, for example, those having 1 to 4 carbon atoms such as methanol, ethanol, n-propanol, isopropanol, and n-butanol.
Is a condensation product of formaldehyde or paraformaldehyde, which is alkyl etherified with an alkyl alcohol, with urea, N, N-ethylene urea, dicyandiamide, aminotriazine, etc., specifically, methoxylated methylol urea, methoxylated methylol −N,
N-ethylene urea, methoxylated methylol dicyandiamide, methoxylated methylol melamine, methoxylated methylol benzoguanamine, butoxylated methylol melamine, 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 diglycidyl ether of bisphenol A and a polymer thereof, and a phenol or cresol novolak type epoxy resin can be used.

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 can be added to the coating agent according to the intended use.

In producing the coating agent, a method such as a roll coater, a gravure-coater spray coating, a dip coating, or the like is appropriately selected for a mixing and dispersing machine such as a roll mill, a blender, and a ball mill.

(Example) Hereinafter, in order to specifically describe the present invention, a description will be given using a production example and an example. In the Production Examples and Examples, “parts” means “parts by weight” and “%” means “% by weight”.

The number average molecular weight of the produced weight was measured by GPC,
The polymer composition was measured by ¹ H-NMR.

 These results are shown in Tables 1 and 2.

The measurement methods for light resistance and heat resistance are as described below, and the evaluation results are shown in Table 3.

(1) Production example of polyester polyol In an autoclave equipped with a thermometer and a stirrer, 388 parts of dimethyl terephthalate, 376 parts of dimethyl isophthalate, 12 parts of trimellitic anhydride, and tricyclodecane dimethylol
706 parts, 541 parts of neopentyl glycol and 0.5 part of tetrabutoxytitanate were charged and heated at 150 to 220 ° C. for 240 minutes to perform transesterification, and then the reaction system was heated to 250 for 30 minutes.
℃, gradually reduce the pressure of the system, after 45 minutes 0.3mmH
The reaction was continued for further 60 minutes under these conditions 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) Production example of polyester resin After transesterification was carried out with the same charge composition as polyester polyol C shown in Table 1, a polycondensation reaction was carried out at 260 ° C. and 0.3 mmHg or less for 120 minutes to obtain a pale yellow transparent polyester. Resin P was obtained. The number average molecular weight of the obtained resin is
17,000 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 4,000 obtained in Production Example of Polyester Polyol and 100 parts of toene in a reactor equipped with a thermometer, a stirrer, and a reflux condenser were dissolved. 9 parts of neopentyl glycol, 22.3 parts of isophorone diisocyanate and 0.02 part of dibutyltin laurate were charged and reacted at 70 to 100 ° C. for 4 hours.
Then, the reaction system was cooled to 70 ° C, and methyl ethyl ketone 15
The reaction was stopped by adding 3.2 parts and 53.2 parts of toluene.

The number average molecular weight of the obtained polyurethane resin F is 18,000
And the glass transition temperature was 98 ° C. Table 2 shows polyurethane resins GL obtained by the same method.

(4) Density evaluation method of printed image The image receiving sheet and the thermal transfer sheet are overlapped with each other so that the dyeing layer (dye receiving layer) and the color material layer are in contact with each other. Heating was performed at an output of 0.7 W / dot, a head heating time of 8 ms, and a dot density of 3 dots / mm, and the cyan and magenta dyes in the color material layer were transferred to the dyeing layer. The obtained transferred image density was measured with a reflection densitometer (DM-600 manufactured by Dainippon Screen Co., Ltd.).

(5) Evaluation method of light fastness The image receiving sheet to which the cyan and magenta dyes have been transferred is irradiated at 40 ° C. so that the energy given by a xenon lamp is 67.0 KJ / m ² before the light fastness test. And the dye concentration retention rate (%) in comparison with the concentration of the dye.

(6) Evaluation method of blocking resistance The image-receiving layer and the base paper are overlapped, and the pressure is 5 ° C / cm ^{2 and} the pressure is 60 ° C.
After 24 hours, the blocking phenomenon was observed. When the surface of the image receiving layer after peeling had no change, the film was easily peeled off, and when the film was blocked and difficult to peel off, it was marked X.

(7) Evaluation method of heat resistance (dark fading rate) The image receiving body to which the cyan and magenta dyes were transferred was left in an environment of 60 ° C. in a dark place for 168 hours, and aged.
The results are shown in terms of dye concentration retention (%) in comparison with the concentration before the heat resistance test.

Example 1 A polyurethane resin F for a receiving layer was diluted with a mixed solvent of toluene: methyl ethyl ketone = 50: 50 to obtain a 20% solution. An epoxy-modified silicone oil (Shin-Etsu Chemical: KF-102) was added to this solution in an amount of 10% by weight based on the above resin, and a synthetic paper having a thickness of 150 μm (Oji Yuka: Yupo PPG-15) was added.
0) was applied using a wire bar so that a dry coating film of 4 μm was obtained. Place the above sheet in an atmosphere at 120 ° C for 30
After drying for a minute, a dyeing layer (dye receiving layer) was obtained.

Example 2 Dyeing layers were provided in the same manner as in Example 1 using polyurethane resins G to K, and Examples 2 to 6 were respectively obtained.

Comparative Example 1 Using a polyurethane resin L, a dyeing layer was provided in the same manner as in Example 1 to obtain Comparative Example 1.

Comparative Example 2 A dyeing layer was provided in the same manner as in Example 1 using a polyester resin P containing no urethane group, and Comparative Example 2 was obtained.

As is clear from Table 3, the polyurethane resin of the present invention has remarkably good light resistance and heat resistance.

(Effect of the Invention) The resin composition for coating mainly containing a polyurethane resin of a specific composition containing a specific tricyclic glycol represented by the general formula (I) according to the present invention has a high glass transition temperature. , A tough coating film can be formed, and the obtained coating film exhibits not only high heat resistance but also excellent properties in light resistance, and a binder of a sublimation type thermosensitive recording paper,
It is industrially useful as a back coat layer of a heat-sensitive ribbon tape, a back coat layer of a magnetic recording medium, and the like.

Claims (1)

(57) [Claims] 1. The dicarboxylic acid component is mainly composed of an aromatic dicarboxylic acid, and the glycol component is 30 to 100 mol% of crycol represented by the general formula (I) and other glycol 0
A polyester polyol having a reduced viscosity of 0.15 or more (a), an organic diisocyanate compound (b) and a chain extender (c) having an active hydrogen group, if necessary, of (a) + (c). Hydrogen group / isocyanate group> 1.
A polyurethane resin obtained by reacting at a mixing ratio of 0 (equivalent ratio).