KR19990025895A - Magnetic thermal recording material - Google Patents

Abstract

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a magnetic thermal recording material, and more particularly, to a thermal recording material having excellent printability, excellent glossiness on a printing surface, and particularly excellent environmental compatibility of a printing surface.

In the heat-sensitive recording material in which an under layer is designed with an under coating solution on a support, a heat-sensitive layer and an over layer are designed thereon, and a back liquid is coated on the back side.

20-30 parts by weight of a copolymer (40% liquid) having a hollow ratio of 30% by weight of a pulp having a pH of 3.0 to 3.5 as a support and a composition of the undercoating solution coated on the support, and bis (4-hydroxy- 3,5-dibromophenol) sulfone 0.5 to 1.5 parts by weight, polyvinyl alcohol (10% liquid) 5 to 10% by weight, LATEX (50% liquid) 2-3.5 parts by weight, defoamer 0.005 to 0.015 parts by weight and water It is a thermal recording material, characterized in that composed of 60 to 80 parts by weight.

Description

[Name of invention]

Magnetic thermal recording material

[Brief Description of Drawings]

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

Detailed description of the invention

(Object of invention)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic thermal recording material, which is excellent in printability, excellent in glossiness of a printing surface, and in particular, a thermal recording material having excellent environmental compatibility of a printing surface.

(Conventional technology)

Conventional thermal recording materials have been widely applied to a measurement recorder, a word processor terminal printer, a facsimile, a barcode label, etc. by forming a thermal layer by coating a thermal solution with a pulp as a support. 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, which may include ordinary water-soluble resins and chemically-resistant aqueous emulsions. Patent number 83457). However, this thermal recording material has a weak environmental response, so when printing on the front surface such as a self-heating ticket, the initial print gloss is excellent. This deteriorates, and the binding strength is weak, which causes a serious drop in printing and equity.

(Purpose of invention)

The object of the present invention has been studied to overcome the disadvantages of the prior art, as a result of using the pulp as a support, excellent gloss of printing even when stored for a long period of time, excellent binding force and durability is improved, equity in printing and use It is to provide an excellent thermal recording material that does not occur.

(Point of invention)

The thermal recording material of the present invention has a three-layer structure of an under layer, a thermal layer, and an over layer on a support, and designs a back layer on the back of the support. As a support, pulp having a pH of 3.0 to 3.5 is used, and the under layer is composed of a styrene acrylic copolymer (Styrene / acrylic copolymer, hereinafter referred to as a copolymer) having an air void of 10 to 30%. As the binder, a polyvinyl alcohol (PVA) solution and LATEX (styrene butadiene polymer) are used. However, the pigment and the binder alone has a problem that excessive foaming occurs in the preparation of the preparation solution, to use a defoaming agent to improve this and to improve the color uniformity and uniform printing surface of the heat-sensitive color layer bis (4-hydroxy-3) , 5-dibromo phenol) sulfone [bis (4-hydroxy-3,5-dibromo phenol) sulfone] was designed.

Composition of the Invention

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

The present invention is coated with an undercoating solution on a support having a size diagram (stoecking ht method) of 100 to 300 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 3.5, thereby forming an underlayer. Design the thermal layer and the over layer. Apply BACK liquid on the back.

As the support used in the present invention, it is best to use a pulp having a pH of 3.0 to 3.5, and in the case of a pH of 3.5 to 4.0, the printing characteristics are good at an initial stage. In case of neutral paper with more than 4.0, the initial gloss and the gloss under environmental test, the binding strength of coating liquid and support are relatively weak. In addition, when the pH is lower than 3.0, the strength of the paper decreases, indicating a serious defect.

The composition of the undercoating solution of the present invention is 20 to 30 parts by weight of the copolymer having a hollow ratio of 30% (40% liquid), 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), 2.0 to 3.5 parts by weight of LATEX (50% solution), 0.005 to 0.015 parts by weight of an antifoaming agent, and 60 to 80 parts by weight of water.

The 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

The production method of the present invention is a copolymer, water, bis (4-hydroxy-3,5-dibromophenol) sulfone, polyvinyl alcohol solution, LATEX After mixing and dispersing in order of antifoaming agent, 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 10 to 13%.

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

(Basic Example 1)

Composition of the undercoat solution used in (Examples 1 to 3) and (Comparative Examples 1 to 7)

First, it is dissolved in water so that the polyvinyl alcohol solid content is 10%, and the copolymer and water are first mixed, followed by bis (4-hydroxy-3,5-dibromophenol) sulfone, polyvinyl alcohol solution, LATEX, Into the antifoaming agent in order to mix and disperse. The antifoaming agent is more effective when dissolved in water separately. This dispersion is passed through a milling machine and circulated until the liquid particle size is 1.03 µm or less to 75% or more to obtain an undercoating solution.

(Basic Example 2) Preparation of Thermal Recording Material

The coating solution thus obtained is combined so that the total solid content is 13%, and then coated with a wire bar on the support, followed by hot air drying. The thermal solution and the over liquid are coated thereon, and the back liquid is coated on the back surface to dry the hot air and super calender. A thermal recording material was manufactured by pressing a flatness meter with a smoothness of 800 to 1000 sec.

(Examples 1-3)

Example 1 uses the pulp exhibiting the above pH as a support, and coats the undercoating solution, the thermal solution, and the over liquid according to Basic Examples 1 and 2, and the BACK liquid is coated on the back side of the support to obtain a thermal recording material. . Examples 2 and 3 obtain the thermal recording material in the same manner as in Example 1 using supports of pH 3.25 and 3.5, respectively.

(Comparative Examples 1-4)

In the comparative example, the undercoating solution, the thermal solution, the over liquid, and the BACK liquid on the support were the same as in Example 1, but the pHs of the support were different, and the deposition amount was equal to 2 g / m 2.

(Comparative Examples 5-7)

Comparative Examples 5 to 7 show the same pH of the support as in Comparative Examples 1 to 3, but the undercoating solution was dried in a weight portion of 3.5 g with a wire bar on the support according to Basic Examples 1 and 2 by combining so that the total solid content was 13%. / ㎡ to apply hot air drying, heat-drying with supernatant liquid, over liquid, and BACK liquid on the back, and hot air dried, and pressurized to a smoothness of 800 ~ 1000 sec by using a super-calendar with a royal calorimeter. Got.

(Effect experiment)

The printing state of the thermal recording material prepared in each of the above Examples and Comparative Examples is printed using the printability TESTER (RI PRINTABILITY TESTER).

① A sample for evaluation is produced by printing and drying with blue printing ink (Korea Special Cotton Ink).

② Print with blue U.V printing ink (for U.V ink) and dry with U.V dryer to prepare sample for evaluation.

In the case of environmental experiments, the samples were stored for 15 hours under the conditions of 50 ℃ × 90% RH before printing, and the results were confirmed using the printability tester.

TABLE 1

TABLE 2

(Evaluation method)

Examples 1 to 3 and Comparative Examples 1 to 7 were printed and dried using a blue printing ink (Korea Special Surface Ink and U.V Ink) using a printability TESTER (RI PRINTABILITY TESTER) to prepare a sample for evaluation.

① Printability: Experiment was carried out in three steps using cellophane TAPE as shown in FIG.

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 case of print fixability test, it is judged that the ink does not run out or the ink and the paper peel off at the same time, and the ink desorption occurs when the ink is completely peeled off the sample surface.

② Print Density: Measure 3 places of sample by using blue filter (FILTER) of Mcbeth concentration meter RD-914 and evaluate by average value.

(Effects of the Invention)

Conventionally, a thermal recording material was obtained by coating an undercoating solution, a thermal solution, an over liquid, and a BACK liquid on the back surface of a support, regardless of the pH of the support. However, in this case, there is a problem that the quality of the product is not the same print quality due to the influence of the original pH, the quality does not maintain a certain level. Therefore, the necessity of the experiment to maintain the constant printing quality and to set the pH range without affecting other quality by carrying out experiments for each pH of the original paper, this time the experiment was carried out. As can be seen in Examples 1 to 3 of the present invention, when the pH is 3.0 to 3.5, the initial printing characteristics are excellent and the excellent quality is maintained even after the environmental experiment. However, as can be seen in Comparative Examples 1 to 4, when the pH is out of this range, the print quality changes. Especially, the closer to the neutral paper, the worse the environmental test as well as the initial print quality, so that it is impossible to produce a stable product. In Examples 5 to 7, the amount of undercoating solution was increased to minimize the influence of the base paper, but the expected effect was not obtained.

Therefore, the present invention produces a thermal recording material by regulating the pH of the base paper, especially in the field of magnetic coating such as a magnetic thermal ticket, when printing on a special surface, UV ink, etc. on the thermal surface, Invention useful for producing excellent products with excellent environmental response and constant printing quality by maintaining desorption of thermal coating and no change of quality with time, especially in high temperature and humidity environment You can see that.

Claims (1)

In a thermal recording material having an under layer, a thermal layer, and an over layer on a support, and a back layer on a back side, the composition of the undercoating solution coated on the support using pulp having a pH of 3.0 to 3.5 as a support. 20 to 30 parts by weight of a copolymer (40% liquid) having a silver hollow ratio of 30%, 0.5 to 1.5 parts by weight of bis (4-hydroxy-3,5-dibromophenol) sulfone, and polyvinyl alcohol (10% liquid ) 5 to 10 parts by weight, LATEX (50% liquid) 2 to 3.5 parts by weight, antifoaming agent 0.005 to 0.015 parts by weight and water 60 to 80 parts by weight of the thermal recording material.