KR19990011385A - Thermal 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 to 30 parts by weight of this 20% copolymer (40% liquid), 0.5 to 1.5 parts by weight of bis (4-hydroxy-3,5-dibromophenol) sulfone, and 5 to 10 polyvinyl alcohol (10% liquid) A heat-sensitive recording material comprising a weight part, latex (LATEX) (50% liquid) 2 to 4 parts by weight, an antifoaming agent 0.005 to 0.015 parts by weight, and water 60 to 80 parts by weight. When printing by special surface, UV ink, etc., 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 desorption step of the cellophane tape in the experiment on the print fixing property.

Subject 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.

Prior art.

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. Here, an under layer is designed between the support and the heat-sensitive layer to prevent color development of the non-image portion and discoloration of the image portion. The under layer includes a conventional water-soluble resin and a chemical-resistant aqueous emulsion (patent registration). No. 83457).

In order to increase the sensitivity, prevent sticking, reduce gas adhesion, and maintain good coating strength, a thermal coating solution containing a pigment, a lubricant, a crosslinking agent, and other auxiliary chemicals is applied to the under layer 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 degraded, the binding force of the under layer is weakened, so that the equity is seriously generated during printing and color development, and the viscosity of the coating solution is high, resulting in a problem of low productivity.

Purpose of the invention.

The present invention provides a heat-sensitive recording material for producing a magnetic thermal recording material for coating a magnetic coating on the back surface in order to overcome the conventional problems as described above, the gloss of the front printing is maintained well even when stored for a long time, 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.

Key points of the 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 copolymer) having an air void of 10 to 30%. The main component is a "copolymer" and a polyvinyl alcohol (PVA) solution and LATEX (thrylene butadiene polymer) are used as a binder.

Furthermore, there is a problem that excessive foaming occurs in the preparation of the preparation liquid with only the foreign material pigment and the binder. In order to improve this, antifoaming agent is used, and bis (4-hydroxy-) is used to secure the color uniformity and uniform printing surface of the thermochromic layer. 3,5-dibromo phenol) sulfone [bis (4-hydroxy-3,5-dibromophenol) sulfone] was designed.

Configuration of the 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 to 30 parts by weight of a copolymer having a hollow ratio of 20% (20% by weight) and 0.5 to 1.5 parts by weight of bis (4-hydroxy-3,5-dibromophenol) sulfone 5 to 10 parts by weight of polyvinyl alcohol (10% solution), 2 to 4 parts by weight of latex (LATEX) (50% solution), 0.005 to 0.015 parts by weight of an antifoaming agent and 60 to 80 parts by weight of water.

If the copolymer is added more than 30 parts by weight, the binding strength of the undercoating solution and the support is weakened, so that a large amount of fingerprints are generated during printing and use, and if the amount is less than 20 parts by weight, the uniformity of the undercoating layer is significantly worsened. The uniformity of 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 an undercoating solution on a support having a size of 200 to 400 seconds, a basis weight of 200 to 260 g / m2, a smoothness of 30 to 80 sec, and a surface pH of 3.0 to 4.5. Design the thermal and overlayers.

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

When the undercoating solution used in the present invention is prepared, the proportion of the copolymer is 70 to 80 parts by weight as the dry part by weight, and exhibits 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, but the binding strength is lowered. 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 when the ratio of the copolymer is increased, the binding strength is also lowered, and when the ratio of the binder is increased, the uniformity of the printing surface is deteriorated.

In the production method of the present invention, a raw material composed of the above composition is measured, followed by copolymerization, water, bis (4-hydroxy-3,5-dibromophenol) sulfone, polyvinyl alcohol solution, latex (LATEX), Into the antifoaming agent, the GHS-dispersed mixed dispersion was passed through a milling machine, and circulated until the liquid particle diameter was 1.03 μm or less to 75% or more to obtain an undercoating solution.

The coating liquid thus obtained is combined so that the total solid content is 10 to 13%.

In general, the dry adhesion amount of the undercoating solution is 1.0 to 3.0 g / m 2.

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

[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, water polyvinyl alcohol solution, Latex (LATEX), defoaming in order to mix and 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. The 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: 1.8.

[Examples 4 to 6]

Example 4 is a case where the ratio of polyvinyl alcohol and latex (LATEX) of the binder is 1: 2.2, Example 5 is a case where the ratio of the copolymer and the binder is 4.5: 1, and Example 6 is the binder and 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 to 4]

EXAMPLES 5-7

Comparative Example 1 is a conventional technique, in which the ratio of the copolymer and the binder is 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% (Comparative Example 3) larger than 80%. Comparative Example 4 shows a case where the ratio of polyvinyl alcohol and latex (LATEX) is 1: 1.

Comparative Example 5 is a case where the ratio of polyvinyl alcohol and latex (LATEX) of the binder is 1: 3, Comparative Example 5 is a case where the ratio of the copolymer and the binder is 3: 1, and Comparative Example 7 is a binder and the copolymer The ratio of the ratio is 7: 1. The coating liquids thus obtained for each comparative example were combined so that the total solid content was 13%, and applied to a wire bar dry weight part of 2 g / m 2 on the support, followed by hot air drying, and coating the thermal liquid and the over liquid thereon to dry the hot air. Then, a thermal recording material was obtained by pressing a super smooth calendar with a smooth 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.

[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 printability TESTER (RI PRINTABLITY TESTER).

Printability: Experiment was performed in three steps using cellophane TAPE as shown below (see FIG. 1).

In the printability test, the cellophane tape was completely peeled off from the top to the rear in the direction of about 180 °, the next two steps were completely peeled off in the upper 90 ° direction, and the third step was quickly removed 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. If the ink is completely peeled off from the spring water, the ink is desorbed.

Color uniformity: Dynamic color developing device (TH-M2, (日) ) And print out the average resistance value 1666Ω at 24V.

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). However, since the printing fixability is poor, when the magnetic coding or the like is applied, the coating solution is dropped on the print yarn, resulting in poor quality and poor color development. The combination of LATEX) increases the overall binding power and improves the color uniformity.

In Examples 1 and 2 and Comparative Examples 3 and 4, when the undercoating solution was prepared, the ratio of the copolymer was 70 parts by weight to 80 parts by weight of dry weight parts excluding water, showing the best binding and printing characteristics, and more than 80 parts by weight (compared to 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 (Comparative Example 2) has a disadvantage that the uniformity of the printing surface is significantly lowered and the color development concentration is lowered.

In addition, the ratio of polyvinyl alcohol and latex (LATEX) should be maintained at 1: 1.5 to 2.5 (Examples 3 and 4). If the ratio of latex (LATEX) is increased (Comparative Example 5), the viscosity is low and productivity is improved, but the binding force is increased. 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 significantly worsened.

In addition, the ratio of the copolymer to the binder should be maintained at 4.5 to 6.5 to 1 (Examples 5 and 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) Although the binding force is excellent, the uniformity of the printing surface is poor.

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 to produce a product having excellent printing characteristics without the desorption of the printing surface and the thermal coating, especially when printing with special surface, U. V ink, etc. on the thermal surface with magnetic coating. It is a useful invention.

Claims (3)

The composition of the undercoating solution coated on the support is 20 to 30 parts by weight of a copolymer having a void ratio of 20% and bis (4-hydroxy-3,5-dibromophenol) sulfone 0.5 to 1.5. A heat-sensitive recording material consisting of 5 parts by weight of polyvinyl alcohol (10% solution), 2-4 parts by weight of latex (LATEX) (50% solution), 0.005 to 0.015 parts by weight of antifoaming agent and 60 to 80 parts by weight of water. . 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.