JP3518664B2 - Primer resin for thermal transfer ink ribbon tape - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a primer resin composition for a thermal transfer ink ribbon tape excellent in carbon black dispersibility and adhesion to a base film. . 2. Description of the Related Art Printing by a fusion heat transfer method is performed by heating a heat-resistant coat layer on the back of an ink ribbon by a thermal head of a printer and transferring the ink layer to the surface of an image receiving paper. The same information as the printed content on the image receiving paper remains in the negative state on the printed ink ribbon. The intermediate layer provided on the thermal transfer ink ribbon tape is a black layer in which carbon black is dispersed between the ink layer and the base film so that printed matter remaining in the used ink ribbon tape in a negative state cannot be easily read. is there. [0003] The properties required for the primer resin for a thermal transfer ink ribbon tape include the dispersibility of carbon black and the adhesion to a base film. This is a very important performance factor that affects the viscosity of Conventionally used primer resins include polyester resins, acrylic resins, phenol resins, fluororesins, polyimide resins, vinylidene fluoride resins, vinyl chloride vinyl chloride resins, and the like. [0005] Among these resins, polyester resins have been mainly used because of their excellent dispersibility of carbon black and their excellent adhesion to a base film.
For example, Japanese Patent Application Laid-Open No. 61-293896 discloses a blend of a polyester resin and a polyvinyl chloride resin as a resin constituting an intermediate layer of a thermal transfer ink ribbon tape. [0006] Conventionally, the performance of the intermediate layer of the thermal transfer ink ribbon tape such as adhesion to a base film as a binder resin and blackness has been obtained, but carbon dispersion is not sufficient. The viscosity of the paint was high, and the workability in the paint preparation step and the step of coating the base film was poor. Specifically, when preparing a carbon-dispersed coating material, there were problems such as that the solid content ratio could not be increased, a large amount of diluting solvent was required, and the application line speed could not be improved. [0007] In order to solve the above-mentioned problems, the present invention provides a support, a transfer ink layer provided on the support via an intermediate layer, and a heat-resistant coat provided on the back surface of the support. A resin composition used for forming the intermediate layer in the thermal transfer ink ribbon tape composed of a plurality of layers, wherein the molar ratio of aromatic dibasic acid to aliphatic dibasic acid in the acid component is 8
0:20 to 98: 2, with a glass transition temperature of 4
A primer resin for a thermal transfer ink ribbon tape , comprising a polyester resin having a number average molecular weight in the range of 4000 to 20,000 at 5 ° C. or more and carbon black.
It provides a composition . DETAILED DESCRIPTION OF THE INVENTION As the aromatic dibasic acid of the polyester resin in the present invention, terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalic acid and the like can be mentioned. Preferably, terephthalic acid, isophthalic acid and the like are used. Is an acid. Examples of the aliphatic dibasic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, dodecinyl succinic acid, and preferably sebacic acid. The glycol components of the polyester resin include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 2,2-dimethyl-1,3-propanediol , 3-methyl-1,5-pentanediol, 2,2-dimethyl-3-hydroxypropyl-2 ', 2'-
Dimethyl-3-hydroxypropanate, 2,2-diethyl-
Aliphatic glycols such as 1,3-propanediol,
Bis (hydroxymethyl) cyclohexane, 1,4-bis (hydroxymethyl) cyclohexane, 1,4-bis (hydroxyethyl) cyclohexane, 1,4-bis (hydroxypropyl) cyclohexane, 1,4-bis (hydroxymethoxy) cyclohexane 1,4-bis (hydroxyethoxy) cyclohexane, 2,2 bis (4-hydroxymethoxycyclohexyl) propane, 2,2-bis (4hydroxyethoxycyclohexyl) propane, bis (4-hydroxycyclohexyl) methane, 2,2 -Bis (4-hydroxycyclohexyl) propane, 3 (4), 8 (9) -tricyclo [5.2.1.
0] alicyclic glycols such as 2,6-decanedimethanol. Among these, especially ethylene glycol,
2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 2,2-dimethyl-3-hydroxypropyl-2 ', 2'-dimethyl-3-hydroxypropanate, 1,6-hexane Diols are preferred. Also, a tri- or higher-functional compound such as trimellitic anhydride, glycerin, trimethylolpropane, or pentaerythritol may be used as a part of the raw material in a range that does not impair the properties of the polyester resin such as organic solvent solubility and coating workability. Good. In the polyester resin of the present invention, the molar ratio of the aromatic dibasic acid to the aliphatic dibasic acid in the acid component is 80: 2.
It is in the range of 0 to 98: 2. When the molar ratio of the aromatic dibasic acid is less than 80%, the glass transition temperature of the obtained polyester resin becomes low, a blocking phenomenon occurs during storage of the resin, and the handling workability deteriorates. In addition, the primer layer after application and drying has tackiness, which makes winding and storage difficult. A similar problem occurs when the glass transition temperature is lower than 45 ° C. On the other hand, the molar ratio of the aliphatic dibasic acid is 2%.
If it is less than 1, the dispersibility of the carbon black particles becomes poor, and the viscosity of the dispersed paint increases. Further, the polyester resin of the present invention has a number average molecular weight in the range of 4,000 to 20,000. Preferably 5000 to 15000, more preferably 6000 to 1
4000. When the number average molecular weight is less than 4000,
The adhesion between the obtained intermediate layer and the surface of the base film is insufficient, and at the time of printing, it is transferred to the image receiving paper together with the ink layer. When the number average molecular weight exceeds 20,000, the paint viscosity of the carbon black-dispersed paint becomes high, and the preparation and application workability of the paint become poor. The polyester resin of the present invention may be optionally
It can be blended with vinyl chloride vinyl chloride resin, acrylic resin, phenolic resin, fluorine resin, polyimide resin, etc. If necessary, a curing agent such as polyisocyanate or epoxy may be added. The polyester resin of the present invention has a number average molecular weight in a specific range, and the molar ratio of aromatic dibasic acid to aliphatic dibasic acid in the acid component is in a specific range. This improves the dispersibility and keeps the paint viscosity low. The present invention will be specifically illustrated by the following examples. In the examples, “parts” means “parts by weight”. Tables 1 and 2 show the compositions and other characteristics of the polyester resins synthesized in the following synthesis examples and comparative examples. The abbreviations in the table are as follows. TPA: terephthalic acid IPA: isophthalic acid SA: sebacic acid EG: ethylene glycol NPG: 2,2-dimethyl-1,3-propanediol HD: 1,6-hexanediol PG: 1,2-propylene glycol 2MG: 2- Methyl-1,3-propanediol CHDM: 1,4-bis (hydroxymethyl) cyclohexane EG: ethylene glycol The glass transition temperature of the polyester resin is measured by a differential scanning calorimeter (DSC), and the molecular weight is gel permeation. It was measured by chromatography (GPC). Details are shown below. The composition of the obtained polyester resin was analyzed by H ¹ -NMR. (Glass transition point temperature) Measured by a differential scanning calorimeter (manufactured by Shimadzu Corporation) at a heating rate of 10 ° C./min in a nitrogen atmosphere. 10 mg of a measurement sample is placed in an aluminum pan, sealed by pressing the lid, cooled to −50 ° C. using liquid nitrogen, and then heated to 150 ° C. at 10 ° C./min. In the endothermic curve obtained in the process (the temperature is plotted on the horizontal axis and the amount of heat per unit time is plotted on the vertical axis), the temperature at the intersection of the baseline before the endothermic peak appears and the tangent to the endothermic peak is calculated as The glass transition temperature Tg of the invention was defined. (Number average molecular weight) Gel permeation chromatography (Model 150-C, hereinafter abbreviated as GPC) manufactured by Waters.
Was used to measure polystyrene as a standard substance. GP
The measurement conditions for C are as follows. Column: KF-802 manufactured by Showa Denko KK Solvent: tetrahydrofuran Solvent flow rate: 1 ml / min Temperature: 30 ° C. Sample concentration: 3 mg / ml Sample injection amount: 100 μl Detector: RI Synthesis Example 1 of polyester resin Thermometer A reaction vessel equipped with a stirrer and a Liebig condenser was charged with 485 parts of dimethyl terephthalic acid, 436 parts of dimethyl isophthalic acid, 403 parts of ethylene glycol, 364 parts of neopentyl glycol and 0.68 part of tetrabutoxy titanate. For 5 minutes, transesterification was performed, and then sebacic acid
The reaction was further carried out at 220 to 230 ° C. for 1 hour. Then, the temperature of the reaction system was raised to 250 ° C. in 30 minutes, and the system was gradually decompressed, and the pressure was reduced to 0.3 mmHg or less after 10 minutes. The reaction was continued for further 30 minutes under these conditions to obtain a light yellow transparent copolyester resin A. The molecular weight of the obtained resin was 6,800 and Tg was 51 ° C. Synthetic Examples 2 to 4 and Comparative Synthetic Examples 5 of Polyester Resin Copolyester resins B to H obtained by the same method as in Synthetic Example 1 are shown in Table 1. [Table 1] Method for Measuring Paint Viscosity of Carbon Black Dispersion Paint The viscosity at 25 ° C. at a rotational speed of 5.0 rpm of an E-type viscometer (manufactured by Toki Sangyo Co., Ltd .; RE80, rotor W3 × R14) was measured. A method for measuring the adhesive strength of the base film A cellophane tape (manufactured by Nichiban Co., Ltd.) having a tape width of 18 mm was adhered to the carbon black coated surface, and the 180 ° peel strength when peeled off was measured by a tensile tester (Toyo Baldwin Co., Ltd.) At 25 ° C. and a pulling speed of 100 mm
/ Min. Was measured. Evaluation Method of Blocking Resistance The polyester resin (flakes) produced as a trial was placed in a glass sample bottle, and 180 g / c was measured from above the sample resin.
m ² , and left at 35 ° C. for 200 hours. After standing, remove the resin from the sample bottle and observe the blocking state.
When it was recognized, it was evaluated as x. Example 1 A 40% solution of polyester resin A in MEK / toluene (50/50 mixed solvent) and carbon black (Raven 1255;
(Columbia Carbon Co., Ltd.) was mixed at a weight ratio of 10/25, and diluted with a mixed solvent having the same composition to give a total weight concentration of the resin and carbon black of 40 wt%. The mixture was dispersed for 5 hours using a glass bead (2 mm diameter) with a paint shaker to prepare a carbon black-dispersed paint. The obtained paint was applied on a PET film having a thickness of 15 μm using an applicator having a gap of 20 μm, and dried at 70 ° C. for 15 minutes. Examples 2 to 5 Using the polyester resins B to E, carbon black-dispersed paints were prepared in the same manner as in Example 1 and applied to PET films. Comparative Example 1 Using a polyester resin F, a carbon black-dispersed coating material was prepared in the same manner as in Example 1, and used as a comparative example in which the molecular weight of the primer resin was lower than the range described in the claims. Comparative Example 2 A carbon black-dispersed coating material was prepared by using the polyester resin G in the same manner as in Example 1, and was used as a comparative example in which the molecular weight of the primer resin was higher than the claimed range. COMPARATIVE EXAMPLES 3, 4 A carbon black-dispersed coating material was prepared in the same manner as in Example 1 using polyester resins H and I, and a comparative example in which the resin composition of the primer resin was outside the scope of the claims. And Comparative Example 5 A carbon black-dispersed coating material was prepared in the same manner as in Example 1 using polyester resin J, and used as a comparative example in which the glass transition temperature of the primer resin was lower than the range described in the claims. [Table 2] As is clear from Table 2, when the polyester resin of the present invention is used as a primer resin, the dispersibility of carbon black particles is improved, and a low-viscosity dispersed paint can be obtained. The intermediate layer obtained by coating has sufficient adhesive strength to the base film surface. Further, the polyester resin of the present invention has a sufficient performance with respect to blocking resistance during storage.

Claims (1)

(57) Claims: A thermal transfer ink comprising a support, a transfer ink layer provided on the support with an intermediate layer interposed therebetween, and a heat-resistant coat layer provided on the back surface of the support. A resin composition used for forming the intermediate layer in a ribbon tape, wherein the molar ratio of aromatic dibasic acid to aliphatic dibasic acid in the acid component is in the range of 85:15 to 98: 2, and the glass transition Temperature of 45 ° C. or higher and number average molecular weight of 4000 to 20,000
Contains polyester resin and carbon black in the range
No thermal transfer ink ribbon tape primer resin composition.