JPH07257055A - Resin composition for image recording medium - Google Patents

Abstract

PURPOSE:To provide a resin composition for image recording medium of superior resistance to light and resistance to heat stability. CONSTITUTION:A composition contains a polyurethane resin prepared by reacting one polyester polyol (A) having the number average molecular weight of 500-8000 and the glass transition temperature of 15 deg.C or over, an organic isocyanate (B) and a chain extender (C) having an active hydrogen under the condition of active hydrogen/isocyanate > 1.0 (equivalent ratio). A dicarbonic acid component of the polyester polyol (A) is composed mainly of an alicyclic dicarboxylic acid, and a glycol component is at least one kind of glycol elected from the group consisting of alkylene glycol o 1-10C and alicyclic glycol.

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 an image recording medium used to obtain a printed image formed on a substrate made of plastic, paper, metal, glass, cloth, etc. Specifically, the present invention relates to a resin composition for an image recording medium, which has excellent light resistance and heat resistance stability.

[0002]

2. Description of the Related Art Conventional color hard copy recording systems include sublimation transfer systems, solvent transfer systems, ink jet systems and electronic transfer systems. Image recording media used for these color hard copy recordings have a dyeing layer made of a dyeing resin formed on a substrate. Image recording can be performed by transferring ink for recording an image to the dyeing layer.

The light fastness of an image obtained by color hard copy is considered to be related to the light fastness of the dyes and pigments contained in the ink used for image recording, but also depends on the surrounding environment of the dye. Characteristics of the dyeing resin used as the dyeing layer of the image recording medium,
That is, properties such as dispersibility, dyeability, and affinity of dyes and pigments with respect to the dyeable resin have become quite important. From this point of view, the polyurethane resin is used as a dyeing resin forming the dyeing layer of the image recording medium used in the above various systems.

However, aliphatic polyester polyols, aromatic polyester polyols, aliphatic polyether polyols, which are raw materials for conventional polyurethane resins,
With an aromatic polyether polyol, it is difficult to produce a polyurethane resin having excellent light resistance and heat stability of an image.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and an object of the present invention is to print on a substrate made of plastic, paper, metal, glass, cloth or the like. An object of the present invention is to provide a resin composition for an image recording medium used for obtaining an image, which is excellent in light resistance and heat stability.

[0006]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that when a composition containing a specific polyurethane resin is used as a dyeing layer of an image recording medium, It was found that the heat resistance and heat resistance are excellent, and the present invention has been completed.

The resin composition for an image recording medium of the present invention comprises a polyester polyol (A) having a number average molecular weight of 500 to 8000, a glass transition temperature of 15 ° C. or higher, an organic diisocyanate (B) and a chain extender having an active hydrogen group ( C)
Is an active hydrogen group / isocyanate group> 1.0 (equivalent ratio)
In the polyester polyol (A), the dicarboxylic acid component of the polyester polyol (A) is mainly an alicyclic dicarboxylic acid, and the glycol component is a group consisting of an alkylene glycol having 1 to 10 carbon atoms and an alicyclic glycol. It is at least one glycol selected from the above, by which the above object is achieved.

In a preferred embodiment, the polyurethane resin has a number average molecular weight of 5,000 to 60,000.

In a preferred embodiment, the polyurethane resin has a glass transition temperature of 40 ° C. to 80 ° C. and a urethane bond content of 500 to 4000 equivalents / 10 ⁶ g.

The present invention will be described in detail below.

The polyurethane resin used in the present invention is
It can be obtained by using the polyester polyol (A), the organic diisocyanate (B) and the chain extender (C) having an active hydrogen group.

Examples of the alicyclic dicarboxylic acid component which is the main component of the dicarboxylic acid component of the polyester polyol (A) include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexane. Examples include monocyclodicarboxylic acids such as dicarboxylic acids, and polycyclodicarboxylic acids. The proportion of the alicyclic dicarboxylic acid in all the dicarboxylic acid components is preferably 60 mol% or more, more preferably 70 mol% or more. If the proportion of the alicyclic dicarboxylic acid in all the dicarboxylic acid components is less than 60 mol%, the light resistance of the image is lowered and the dye may be discolored or faded.

The glycol component of the polyester polyol (A) is an alkylene glycol having 1 to 10 carbon atoms and / or an alicyclic glycol, for example, ethylene glycol, propylene glycol, neopentyl glycol, diethylene glycol, 1,4-. Butanediol, 1,6-hexanediol, 1,5-pentanediol, 1,4-cyclohexanedimethanol,
1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, tricyclodecanedimethylol, hydrogenated bisphenol A, hydrogenation Examples thereof include ethylene oxide and / or propylene oxide adducts of bisphenol A. Of the above glycol components, it is essential that the alkylene glycol has 1 to 10 carbon atoms, and if it exceeds this, the glass transition temperature of the polyester polyol will decrease, which is not preferable.

The polyester polyol (A) must have a number average molecular weight of 500 to 8,000. If the number average molecular weight is less than 500, the concentration of urethane groups will be high and the coating suitability will be inferior.
When it exceeds 0, the concentration of the urethane group becomes low and the light resistance and heat stability which are the original properties of the polyurethane resin cannot be obtained. The glass transition temperature of the polyester polyol (A) is 15 ° C. or higher, preferably 20 ° C. or higher. When the glass transition temperature is lower than 15 ° C., the heat resistance and blocking resistance of the obtained image are remarkably reduced, and the storage stability of the obtained color hard copy is poor.

Examples of the organic diisocyanate compound (B) include hexamethylene diisocyanate, tetramethylene diisocyanate, 3,3'-dimethoxy-4,
4'-biphenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate,
1,3-diisocyanate-methylcyclohexane,
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, 3,3 ' -Dimethyl-4,
4'-biphenylene diisocyanate, 4,4'-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate and the like can be mentioned, and hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate and diphenylmethane diisocyanate are preferable.

Examples of the chain extender (C) having an active hydrogen group include ethylene glycol, propylene glycol, neopentyl glycol and 2,2-diethyl-
1,3-propanediol, polyethylene glycol,
Diethylene glycol, tricyclodecane dimethylol, 1,4-cyclohexane dimethanol, 1,4-cyclohexane diol, etc. are mentioned.

The polyurethane resin contained in the resin composition for an image recording medium of the present invention comprises the polyester polyol (A), the organic diisocyanate compound (B), and the chain extender (C) having an active hydrogen group. It is obtained by reacting active hydrogen groups / isocyanate groups> 1.0 (equivalent ratio). When the equivalent ratio of active hydrogen group / isocyanate group is 1.0 or less, the light resistance and heat stability of the resulting resin composition for an image recording medium are insufficient.

The above polyurethane resin can be produced by a known method at a reaction temperature of 20 ° C. to 150 ° C. in the presence of a catalyst or without a catalyst. Examples of the solvent that can be used include 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. As the above catalyst,
Amines, organotin compounds and the like can be used.

The number average molecular weight of the polyurethane resin is
5000 to 60,000 is preferable, and 6000 to 5000
0 is more preferable. Further, the glass transition temperature of this polyurethane resin is preferably 40 ° C. to 80 ° C., and the urethane bond content is preferably 500 to 4000 equivalents / 10 ⁶ g. When the glass transition temperature and the urethane bond content of the polyurethane resin are within the above ranges, the resulting resin composition for an image recording medium of the present invention has good light resistance and heat stability.

The resin composition for an image recording medium of the present invention comprises
A known crosslinking agent such as an organic polyvalent isocyanate compound, an alkyl etherified amino formaldehyde resin, an epoxy resin or the like can be further added. By blending and crosslinking the above-mentioned crosslinking agent, the light resistance and heat stability of the obtained resin composition for an image recording medium can be improved.

Examples of the organic polyvalent isocyanate compound include alicyclic diisocyanates (eg, tetramethylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate), aromatic diisocyanates (eg tolylene diisocyanate). Islet, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate) and other known diisocyanate burette, trimer of isocyanate or isocyanurate, adduct of 3 mol of diisocyanate compound and 1 mol of trifunctional polyol, and isocyanates thereof Examples thereof include blocked isocyanate compounds in which groups are blocked. As the isocyanate group blocking agent, known blocking agents such as phenol, ε-caprolactam, ethyl acetoacetate, and methylethylketoxime can be used.

The above-mentioned alkyl etherified aminoformaldehyde resin is, for example, formaldehyde or paraformaldehyde alkyl etherified with an alkyl alcohol having 1 to 4 carbon atoms (for example, methanol, ethanol, n-propanol, isopropanol, n-butanol). And the like, and a condensation product of urea, N, N-ethylene urea, dicyandiamide, aminotriazine and the like. Specific examples of such condensation products include methoxylated methylolurea, methoxylated methylol-N, N-ethyleneurea, methoxylated methylolmelamine, methoxylated methylolbenzoguanamine, butoxylated methylolmelamine, butoxylated methylolbenzoguanamine. Is mentioned.

Examples of the epoxy resin include known epoxy resins such as diglycidyl ether of bisphenol A and its multimers, and phenol or cresol novolac type epoxy resin.

In addition to the method of blending the above-mentioned crosslinking agent, crosslinking may be carried out using a method such as ionic crosslinking, electron beam crosslinking or photocrosslinking.

The resin composition for an image recording medium of the present invention comprises
Resins other than the polyurethane resin can be mixed and / or reacted. Examples of such resins include polyvinyl resins, polycarbonate resins, polyacrylic acid resins, polymethacrylic acid resins, polyolefin resins, cellulose derivative resins, polyether resins, polyester resins and the like.

The resin composition for an image recording medium of the present invention comprises
Depending on the purpose, an extender pigment, a coloring pigment, a thixotropic agent, a defoaming agent, a color separation preventing agent and the like can be added.

The resin composition for an image recording medium of the present invention comprises
Further, various lubricants can be blended for the purpose of improving the releasability. Examples of the slippery substance include fluorine-based resins, silicon-based resins, organic sulfonated compounds,
Interface lubricants such as organic phosphate compounds and organic carboxylate compounds may be mentioned.

The resin composition for an image recording medium of the present invention may contain an ultraviolet absorber, an antioxidant and the like for the purpose of improving the light resistance of a recorded image.

The resin composition for an image recording medium of the present invention comprises
Generally, the polyurethane resin is contained in a form dissolved in the solvent, and if necessary, the crosslinking agent, a resin other than polyurethane, an additive such as a pigment or a lubricant is also contained, and the solid content is usually 5 or less. It is about 70% by weight.

The base material of the image recording medium is not particularly limited, but various films or sheets made of plastic, paper, synthetic paper, metal, glass or the like can be used.

The image recording medium can be obtained by applying the resin composition for an image recording medium of the present invention onto the above-mentioned substrate by an appropriate method and drying it to form a dyeing layer.

[0032]

EXAMPLES The present invention will be specifically described below with reference to production examples and examples. 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. The glass transition temperature (Tg) was measured by DSC.

Production examples of polyester polyol and polyurethane resin, and evaluation methods for dyeing density, light resistance and heat stability are shown below.

(1) Production Example of Polyester Polyols a to d 1,4 in an autoclave equipped with a thermometer and a stirrer.
-430 parts of cyclohexanedicarboxylic acid, 232 parts of 1,4-cyclohexanediol, 21 ethylene glycol
7 parts and 0.5 parts of tetrabutoxytitanate are charged and heated at 150 to 220 ° C. for 240 minutes for esterification, then the reaction system is heated to 250 ° C. for 30 minutes and the system pressure is gradually reduced. After 45 minutes, 0.3 mmHg
Below, the reaction was continued for another 60 minutes under these conditions to obtain a pale yellow transparent polyester polyol a. The number average molecular weight of the obtained resin was 2,500. Table 1 shows the types and molar ratios of the dicarboxylic acid component and the glycol component used. Further, polyester polyols b, c and d were obtained by using the dicarboxylic acid component and the glycol component of the types and molar ratios shown in Table 1 by the same production method as for the polyester a. Table 1 also shows the glass transition temperatures (Tg) and number average molecular weights of the obtained polyester polyols a to d.

(2) Production Example of Polyester Polyol e After transesterification with the same composition as the polyester polyol c shown in Table 1, 260 ° C., 0.3 mm
Polycondensation reaction was performed for 120 minutes under the condition of Hg or less to obtain a pale yellow transparent polyester polyol e. The obtained resin has a number average molecular weight of 17,000 and a glass transition temperature of 65 ° C.
Met.

[0037]

[Table 1]

(3) Production Example of Polyurethane Resins I to VI In a reactor equipped with 100 parts of the above polyester polyol a, a thermometer, a stirrer and a reflux condenser, 98 parts of toluene was charged and dissolved, and then 10 parts of neopentyl glycol was added. ,
Charge 27.3 parts of isophorone diisocyanate and 0.02 part of dibutyltin laurate and charge at 70 ° C to 100 ° C for 4 hours.
Reacted for hours. Then, the reaction system is cooled to 70 ° C.,
The reaction was stopped by adding 97 parts of methyl ethyl ketone. The number average molecular weight of the obtained polyurethane resin I is 18,000.
The glass transition temperature was 50 ° C. Further, polyurethane resins II to VI were obtained in the same manner as the polyurethane resin I except that the types of polyester polyol and the amounts of neopentyl glycol and isophorone diisocyanate used were changed as shown in Table 2.

[0039]

[Table 2]

(4) Method for evaluating the dyeing density of a printed image The image receptor (image recording medium) sheet and the thermal transfer sheet are superposed so that the dyeing layer (dye receiving layer) and the color material layer are in contact with each other, and the thermal transfer is performed. From the substrate side of the sheet, a thermal head was used to heat the head output at 0.7 W / dot, the head heating time at 8 mS, and the dot density at 3 dots / mm to transfer the cyan dye in the coloring material layer to the dyeing layer. . The obtained transfer image density was measured by a reflection densitometer (DM-
600).

(5) Method of evaluating light resistance: An image receiving sheet on which a cyan dye is transferred has an energy of 6 given by a xenon lamp at 40 ° C.
Irradiation was carried out at 7.0 kJ / m ^2, and the dye density retention rate (%) in comparison with the density before irradiation was represented by the following formula.

[0042]

[Equation 1]

(6) Evaluation method of heat resistance stability (dark fading rate) The image receptor on which the cyan dye is transferred is allowed to stand for 168 hours in an environment of 60 ° C. in the dark, aged, and expressed by the following formula. The dye density retention rate (%) is shown in comparison with the density before aging.

[0044]

[Equation 2]

Example 1 The above polyurethane resin I was
A 20% solution was prepared by diluting with a mixed solvent of toluene: methyl ethyl ketone = 50: 50. Epoxy-modified silicone oil (KF-102, manufactured by Shin-Etsu Chemical) is added to this solution.
Was added to the above resin in an amount of 10% by weight, and the thickness was
Was applied to a synthetic paper (No. 0, manufactured by Oji Oil Chemical Co., Ltd .: YUPO PPG-150) using a wire bar so as to obtain a dry coating film of 4 μm. The above sheet was dried in an atmosphere of 120 ° C. for 30 minutes to obtain an image recording medium having a dyeing layer (dye receiving layer). Using the obtained image recording medium, by the above method,
The dyeing density, light resistance and heat stability were evaluated. The results obtained are shown in Table 3. The results for Examples 2 to 4 and Comparative Examples 1 to 3 below are also shown in Table 3.

Example 2 An image recording medium was obtained in the same manner as in Example 1 except that polyurethane resin II was used instead of polyurethane resin I.

Example 3 Example 1 was repeated except that polyurethane resin III was used instead of polyurethane resin I.
An image recording medium was obtained in the same manner as.

Example 4 An image recording medium was obtained in the same manner as in Example 1 except that polyurethane resin IV was used instead of polyurethane resin I.

Comparative Example 1 An image recording medium was obtained in the same manner as in Example 1 except that polyurethane resin V was used instead of polyurethane resin I.

(Comparative Example 2) An image recording medium was obtained in the same manner as in Example 1 except that polyurethane resin VI was used instead of polyurethane resin I.

(Comparative Example 3) An image recording medium was obtained in the same manner as in Example 1 except that the polyester polyol e was used instead of the polyurethane resin I.

[0052]

[Table 3]

From Table 3, the dyeing layers of Examples 1 to 4 obtained by using the resin composition for an image recording medium of the present invention are more dyeable than the dyeing layers of Comparative Examples 1 to 3. It can be seen that the light resistance and the heat resistance stability are both excellent.

[0054]

INDUSTRIAL APPLICABILITY A resin composition for an image recording medium containing a polyurethane resin containing an alicyclic component as a main component according to the present invention has excellent light resistance of a dye, and the obtained image has excellent heat stability. And is industrially useful.

The resin composition for an image recording medium of the present invention is used for forming a dyeing layer of an image recording medium for a color hard copy recording system such as a sublimation transfer system, a solvent transfer system, an ink jet system and an electronic transfer system. It is useful.

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Claims (3)

[Claims] 1. A polyester polyol (A) having a number average molecular weight of 500 to 8000 and a glass transition temperature of 15 ° C. or higher,
The organic diisocyanate (B) and the chain extender (C) having an active hydrogen group are combined with active hydrogen group / isocyanate group>
A resin composition for an image recording medium, comprising a polyurethane resin obtained by reacting at 1.0 (equivalent ratio), wherein the dicarboxylic acid component of the polyester polyol (A) is mainly an alicyclic dicarboxylic acid, and a glycol. An image recording medium composition, wherein the component is at least one glycol selected from the group consisting of alkylene glycols having 1 to 10 carbon atoms and alicyclic glycols. 2. The composition for an image recording medium according to claim 1, wherein the polyurethane resin has a number average molecular weight of 5,000 to 60,000. 3. The composition for an image recording medium according to claim 1, wherein the polyurethane resin has a glass transition temperature of 40 ° C. to 80 ° C., and a urethane bond content of 500 to 4000 equivalents / 10 ⁶ g. object.