KR100240475B1 - Thermosensitive recording material - Google Patents

Abstract

The present invention provides a heat-sensitive recording material for producing a magnetic thermal recording material for coating a magnetic coating on the back side, wherein the support body has a basic structure of a three-layer structure of an under layer, a thermal layer, and an over layer, wherein the composition of the under layer has a hollow ratio. 20-30 weight part of styrene acrylic copolymers (40% liquid) and 10-30% of (air void) bis (4-hydroxy-3,5-dibromophenol) chiffon 0.5-1.5 weight part polyvinyl A thermal recording material comprising 5 to 10 parts by weight of alcohol (10% liquid), 2 to 4 parts by weight of latex (LATEX) (0.00% to 0.015 parts by weight of antifoaming agent and 60 to 80 parts by weight of water). In the case of printing with special surface, UV ink, etc. on the thermal surface along with magnetic coating, there is a merit that a thermal recording material having excellent printing characteristics without desorption of printing surface and thermal coating can be obtained.

Description

Thermal recording material

1 is a diagram of desorption relationship of cellophane tape in an experiment on printability.

[Object of invention]

The present invention relates to a thermal recording material having excellent printability and excellent binding force for producing a magnetic thermal recording material by coating a magnetic paint on the back surface.

[Private Technology]

Conventional thermal recording materials have been widely applied to measurement recorders, word printer terminal printers, facsimiles, barcode labels, etc. by coating a thermal solution on a sheet of paper to form a thermal layer. An under layer is designed between the support and the heat-sensitive layer to prevent color development of the non-image part and discoloration of the image part. The under layer includes ordinary water-soluble resins and chemically-resistant aqueous emulsions (patent registration). No. 83457). In order to increase the sensitivity, prevent sticking, reduce gas adhesion, and maintain good coating strength, the thermal coating liquid containing pigments, lubricants, crosslinking agents and other auxiliary chemicals is applied to the underlayer to form a heat-sensitive layer. However, in the case of manufacturing the magnetic thermal recording material such as a subway ticket or parking ticket by applying magnetic coating on the back of the thermal recording paper, the characteristics of the thermal recording paper are changed by the magnetic paint, so that the magnetic thermal recording material is stored for a long time. The glossiness of the front printing is remarkably decreased, the binding force of the under layer is weakened, so that the stake in printing and color development is severely generated, and the viscosity of the coating solution is high, resulting in a problem of low productivity.

[Purpose of invention]

The present invention provides a heat-sensitive recording material for manufacturing a magnetic thermal recording material for coating a magnetic coating on the back surface to overcome the conventional problems as described above. The purpose of the present invention is to provide a heat-sensitive recording material which is excellent in binding strength and improves durability, and prevents occurrence of equity when printing and using (coloring) a product coated with a magnetic coating.

[Point of invention]

The present invention is based on a three-layer structure of an under layer, a thermal layer, and an over layer on a support, and the under layer has a styrene acrylic copolymer (Styrene / acrylic copclymer) having an air void of 10 to 30%. Polyvinyl alcohol (PV A) solution and latex (LATEX) (styrene butadiene polymer) are used as a binder based on "copolymer"). Furthermore, these pigments and binders alone have a problem that excessive foaming occurs in the preparation of the preparation solution. To solve this problem, antifoaming agents are used, and bis (4-hydroxy-) is used to secure uniform color and uniform printing surface of the thermochromic layer. 3,5-dibromo phenol) sulfone [bis (4-hydroxy-3,5-dibro mophenol) sulfone] was designed.

[Configuration of Invention]

In order to realize the object of the present invention, the present invention is next embodied.

The present invention uses a base paper as a support, and is composed of an undercoating layer, a thermal coating layer, an overcoating layer on the front surface.

The composition of the undercoating solution of the present invention is 20-30 parts by weight of a styrene acrylic copolymer (40% liquid) having an air void of 10-30%, and bis (4-hydroxy-3,5-dibro Mophenol) sulfone 0.5 to 1.5 parts by weight, polyvinyl alcohol (10% solution) 5 to 10 parts by weight, latex (LATEX) (50% solution) 2 to 4 parts by weight, antifoaming agent 0.005 to 0.015 parts by weight and water 60 to 80 It is composed of parts by weight. In this case, when the TiO ₂ having no hollow is used as the copolymer, it is preferable to use a polymer having an air void in order to prevent the magnetic mixed solvent from being transferred to the heat-sensitive surface. If it is high as 50%, the volume is too large and the density is too low, so the harmony with the additives of the other undercoat solution is low, and the quality is deteriorated. When the amount used is more than 30 parts by weight, the binding capacity of the undercoat solution and the support is reduced. It becomes weak, so that a large amount of equity occurs during printing and use, and when less than 20 parts by weight, the uniformity of the undercoating layer is significantly worsened, and the uniformity of the printing surface during printing is also worsened. In addition, if the weight of latex (LATEX) is greater than 4, the adhesion between the undercoating solution and the support is weakened, so that desorption occurs during printing, and if the weight of the latex (LATEX) is less than 2, the viscosity of the undercoating solution as a whole increases productivity. There will be no.

The support is coated with undercoating solution on the support with 200 ~ 400 seconds in size (stoeckight method), 200 ~ 260g / m2 in basis weight, 30 ~ 80sec in smoothness and 3.0 ~ 4.5 in surface pH, Design the thermal and overlayers on top.

Antifoaming agent in the above configuration of the present invention is 2, 4, 7, 9 tetramethyl-5-decine-4, 7-diol (2,4,7,9-tetramethy1-5-decyne-4,7-diol) use.

When the undercoating solution used in the present invention is prepared, the proportion of the copolymer is 70 parts by weight to 80 parts by weight with the best binding and printing properties. It occurs a lot, and the gloss of printing is significantly worse, especially when printing after environmental experiments. In addition, when less than 70 parts by weight, there is a disadvantage that the uniformity of the printing surface is significantly lowered and the color density is lowered. In addition, the ratio of polyvinyl alcohol and latex (LATEX) should be maintained at 1: 1.5 to 2.5. When the ratio of latex (LATEX) is increased, the viscosity is low and productivity is improved. Although the binding force is excellent, the viscosity is high and the productivity and uniformity of the printing surface are significantly worse. In addition, the ratio of the copolymer and the binder should be maintained at 4.5 to 6.5 to 1, but the ratio of the copolymer increases, the binding strength also decreases, and the ratio of the binder increases, but the uniformity of the printing surface becomes poor.

In the production method of the present invention, a styrene acrylic copolymer (40% liquid) having 10-30% of air voids, water, and bis (4-hydroxy-3,5- Dibromophenol) sulfone, polyvinyl alcohol solution, latex (LATEX), antifoaming agent, and then mixed and dispersed. The dispersion is passed through a milling machine so that the liquid particle size is 1.03㎛ or less and 75% or more. Circulate until to obtain undercoat. The coating solution thus obtained is combined so that the total solid content is 10 to 13%. Approximately, the dry adhesion amount of an undercoat liquid becomes 1.0-3.0 g / m <2>.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

In the examples and comparative examples, "copolymer" means a styrene acrylic copolymer (40% liquid) having an air void of 10-30%.

[Examples 1-3]

Each embodiment is prepared as follows.

First, the polyvinyl alcohol is dissolved in water to have a solid content of 10%, and the copolymer and water are first mixed, followed by bis (4-hydroxy-3,5-dibromophenol) sulfone, polyvinyl alcohol solution, Latex (LATEX), antifoaming agent added in order to disperse. The antifoaming agent is more effective when dissolved in water separately. The dispersion is passed through a milling machine and circulated until the liquid particle diameter is 1.03 µm or less to 75% or more to obtain an undercoating solution. The coating solution thus obtained is combined so that the total solid content is 13%, and applied on a support to a dry weight part of 2 g / m 2 with a wire bar, followed by hot air drying. A thermal recording material was manufactured by pressing a flat smooth meter with a smoothness of 800 to 1000 sec. Example 1 is the case where the solid content of the copolymer is 70% of the total, Example 2 is the case where the solid content of the copolymer is 79% of the total, Example 3 is the ratio of polyvinyl alcohol and latex (LATEX) 1: 1: 1.8.

EXAMPLES 4-6

Example 4 is a case where the ratio of polyvinyl alkoxy and latex (LATEX) of the binder is 1: 2.2, Example 5 is a case where the ratio of the binder of the copolymer is 4.5: 1, Example 6 is a binder with the copolymer The ratio is 6.5: 1. The preparation method was carried out in the same manner as in Example 1-3.

[Comparative Examples 1-4]

[Comparative Examples 5-7]

Comparative Example 1 is a conventional technique combining the ratio of the copolymer to the binder 22: 1 except for latex (LATEX) in the binder. Comparative Examples 2 and 3 are comparative examples of Examples 1 and 2, respectively, in the case of 60% (Comparative Example 2) having a solid content ratio of the copolymer less than 70% or 85% 9 Comparative Example 3) larger than 80%. Comparative Example 4 shows a case where the ratio of polyvinyl alkoxy and latex (LATEX) is 1: 1.

Comparative Example 5 is a case where the ratio of polyvinyl alkoxy to latex (LATEX) of the binder is 1: 3, Comparative Example 6 is a case where the ratio of the copolymer and the binder is 3: 1, and Comparative Example 7 is a binder with the copolymer The case where the ratio is 7: 1 is shown. The coating liquids thus obtained in each comparative example were combined so that the total solid content was 13%, and applied to a dry bar by weight of 2 g / m 2 with a wire bar on the support, followed by hot air drying, and coating the thermal solution and the over liquid thereon to dry the hot air. Then, a thermal recording material was obtained by pressing a super-calendar and using a royal type smoothness meter to obtain a smoothness of 800 to 1000 sec.

[Effect Experiment]

Samples for evaluation were prepared by printing and drying the blue printing ink (Korea Special Surface Ink) using the printability TESTER (RIPRINTABILITY TESTER) in the printing state of the thermal recording material prepared in each of the above Examples and Comparative Examples. After the thermal recording material was stored for 15 hours under an environmental test (50 ° C. × 90% RH), the printing status was confirmed using the printability TESTER.

TABLE 1

◎: Very good ○: Good △: Normal ×: Poor

[Evaluation method]

Samples for evaluation were prepared by printing and drying the blue printing ink (Korea Special Surface Ink) on the thermal recording materials of Examples 1 to 6 and Comparative Examples 1 to 7 using the printability TESTER (RI PRINTABILITY TESTER).

Printability: Experiment was carried out in three steps using cellophane TAPE as follows (see Fig. 1).

In the printability test, the cellophane tape was slowly peeled off from the top to the rear in the direction of about 180 °, the second step was slowly peeled off in the upward 90 ° direction, and the third step was quickly peeled off in the rear 45 ° direction. In the printability test, it is judged that the ink does not run out or the ink and the paper are peeled off at the same time.

Color uniformity: Print out the average resistance value of 1666Ω at 24V by using a dynamic color device (TH-M2, Japan). The printing energy at that time is evaluated for the thin wire of the part printed with an average of 0.30 mJ / dot.

Viscosity: The result of the measurement solution temperature is 21 ℃ using the Brookfield viscometer. Based on the comparative example 1 which is a prior art, when a measured value is lower than this, it divides into very good, same good, and high.

[Effects of the Invention]

Conventionally, only polyvinyl alcohol is used as a binder (Comparative Example 1), which causes poor printing fixability, resulting in poor coating quality during printing, deterioration in quality, and poor color development. In contrast, the embodiment is mixed with latex (LATEX) to increase the overall binding force, resulting in improved color uniformity. In Examples 1 and 2 and Comparative Examples 3 and 4, when the undercoating solution was prepared, the proportion of the copolymer was 70 parts by weight to 80 parts by weight of the dry weight part except water, and showed the best binding and printing characteristics. In the case of Example 3), the printing binding strength is weakened, so that a large amount of equity is generated when printing and using, especially after printing, the printing gloss is significantly worse. In addition, less than 70 parts by weight of polyvinyl alkoxy and latex (LATEX) must maintain a ratio of 1: 1.5 ~ 2.5 (Examples 3 and 4) When the ratio of latex (LATEX) is increased (Comparative Example 5) Is improved, but the binding strength is lowered and, on the contrary, when the ratio of polyvinyl alcohol is increased (Comparative Example 4), the binding strength is excellent, but the viscosity is high, so that the productivity and the uniformity of the printing surface are remarkably deteriorated. In addition, the ratio of the copolymer and the binder should be maintained at 4.5 to 6.5 (Example 5.6), but when the ratio of the copolymer is increased (Comparative Example 7), the binding force is also lowered and the ratio of the binder is increased (Comparative Example). 6) Excellent binding but poor printing uniformity.

As a binder, polyvinyl alcohol and latex (LATEX) should be used at a constant ratio, the total ratio of the copolymer should be kept constant, and the ratio of copolymer and binder should be kept constant.

Therefore, the present invention is useful for producing a product having excellent printing characteristics without desorption of printing surface and desorption of thermal coating, especially when printing with special surface, UV ink, etc. on thermal surface with magnetic coating. to be.

Claims (3)

The composition of the undercoating solution coated on the support is 20-30 parts by weight of a styrene acrylic copolymer (40% liquid) having an air void of 10-30%, and bis (4-hydroxy-3,5- Dibromophenol) sulfone 0.5 to 1.5 parts by weight, polyvinyl alcohol (10% solution) 5 to 10 parts by weight, latex (LATEX) (50% solution) 2 to 4 parts by weight, antifoaming agent 0.005 to 0.015 parts by weight and water 60 A thermal recording material composed of ~ 80 parts by weight. The total ratio of the copolymer is 70 to 80% by weight of the dry weight part, the ratio of polyvinyl alcohol and latex (LATEX) of the binder is 1: 1.5 to 2.5, the ratio of the copolymer and the binder The thermal recording material which keeps 4.5-6.5: 1. The thermally sensitive recording material according to claim 1, wherein the dry adhesion amount of the undercoating solution is 1.0 to 3.0 g / m 2.

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