JPS6064889A - Thermosensitive recording material - Google Patents

Abstract

PURPOSE:To improve frictional fog while maintaining various properties of printing density in a thermosensitive recording material formed with a thermosensitive recording layer containing an electron imparting colorless dye and electron receiving compound provided on a support by containing low density polyethylene particles of particle size of special range in the thermosensitive layer. CONSTITUTION:Low density polyethylene contains 0.94g/cm<3> or less, and if high density polyethylene provides less frictional fog preventing effect. The low density polyethylene particles is preferably contained by 5-50wt% and preferably 5- 15wt% of coating amount of the thermosensitive recording layer. If less than 5wt%, the frictional fog improving effect is less, while if more than 50wt%, a defect of a decrease in the sensitivity occurs. Further, mean particle diameter (volumetric mean particle size) is preferably 0.03 to 16 microns, and if less than 0.03 microns, the adding effect is less, while if more than 16 microns, the flatness of the thermosensitive coloring layer is deteriorated. Further, preferably 0.5 to 5 microns.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a heat-sensitive recording material, and more specifically, a heat-sensitive recording layer containing an electron-donating colorless dye and an electron-accepting compound is formed on a support. The present invention relates to a heat-sensitive recording material provided in a heat-sensitive recording material.

(Prior art) Heat-sensitive recording materials using electron-donating colorless dyes and electron-accepting compounds are disclosed in Tokuko Sho≠j-/Hiroshi No. 032 and Tokko Sho≠3-
It is disclosed in Hiroshi/No. 40, etc. This heel strength iF'饅廿下H is used for printing out stains + 1-arm half-needle counters, etc., and has the advantage of requiring no maintenance.However, it does not require scratches from nails, etc. It also has the disadvantage of producing color and staining the recording surface. In other words, friction fog occurs.

Known methods for improving friction fog on heat-sensitive recording materials are roughly classified into the following three types.

That is, a method is disclosed in which waxes are first added to the coating liquid to increase the slipperiness of the surface, suppress the generation of frictional heat, and absorb the generated heat by softening the wax.
Polyethylene wax is mentioned as an example of wax. (Tokuko Showa SO-/Ko 33/No.) Second, fine powder of starch or starch derivatives is added to the heat-sensitive layer to suppress frictional fogging by preventing frictional heat from being generated near the color-forming components. Method. (Special Publication Shoj/-42t No. 7) Thirdly, by applying material particles coated with a polymeric material that have a decoloring effect on the coloring component used to the heat-sensitive layer, the color-depleting effect is achieved when rubbed. A method to suppress the oozing of substances and color development. (IVf KaishojtG-11tTtt No.) However, these methods cannot be said to be suitable for heat-sensitive recording materials, and the effect of preventing friction fogging cannot necessarily be said to be sufficient.

(Purpose of the invention) The purpose of the present invention is to maintain various performances of printing density ratio.

It is an object of the present invention to provide a heat-sensitive recording material which is free from friction fog.

(Structure of the Invention) The object of the present invention is to provide a heat-sensitive recording material in which a heat-sensitive recording layer containing an electron-donating colorless dye and an electron-accepting compound is provided on a support, with an average particle size of 0.03 microns to 0.03 microns. This was achieved using a heat-sensitive recording material characterized by containing 10% by weight of low-density polyethylene particles with a diameter of 1/2 microns based on the total weight of the heat-sensitive layer components.

The polyethylene used in the present invention is in the form of particles, and low-density polyethylene having a particle size within a certain range has a remarkable anti-friction fogging effect and is therefore suitable for the purpose of the present invention.

On the other hand, when high-density polyethylene is used, the effect of preventing friction fogging is small.

The low density polyethylene used in the present invention has a density of ≠
E/cIrL The following are preferred.

The low-density polyethylene particles have a coating amount of j-7 of the heat-sensitive recording layer.
0% by weight, preferably t-/j% by weight. If it is less than 5% by weight, the effect of improving friction fog will be small, and if it exceeds 10% by weight, problems such as a decrease in sensitivity will be observed. Further, the average particle size (volume average particle size) is preferably 0603 microns to 71 microns, and if it is less than O, O3 micron, the addition effect will be small, and if it exceeds it micron, there will be disadvantages such as deterioration of the flatness of the heat-sensitive coloring layer. . More preferably, it is from 0.005 microns to 5 microns.

Examples of the electron-donating colorless dye used in the present invention include triarylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, and spiropyran compounds. Some examples of these are triarylmethane compounds such as 3,3-bis(p-dimethylaminophenyl)-+-dimethylaminophthalide (i.e., crystal violet lactone), 3,3-bis(p- dimethylaminophenyl) phthalide, j-(p-dimethylaminophenyl)-3(/,
3-dimethylindol-3-yl)phthalide, J-(
Examples include p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, and examples of diphenylmethane thread include Hiromu.

≠'-Histodimethylaminobenzhydrin benzyl ether, N-halophenyl-leuco-orami 7N-,
2, ψ, j −) IJ 70 Lophenyl leuko auramine, etc., and xanthine compounds include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine B (p-chloroanilino)lactam, λ -rebenzylamino-6-diethylaminofluorane λ-anilino-t-diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-cyclohexylmethylaminofluorane, -10-chloroanilino-t-diethylaminofluorane, 2-m-chloroanilino-t-diethylaminofluorane, λ-(
3,≠-dichloroanilino)-6-diethylaminofluorane, λ-octylamino-6-dinithylaminofluorane, Korghexylamino-6-diethylaminofluorane, J-m-trifluoromethylanilino-A -diethylaminofluorane, λ-butylamino-3-chloro-6-diethylaminofluorane 1,2-1. ) xyethylamino-lower 6-diethylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, λ-rephenylamino-6-ethylaminofluoran λ-anilino-3-methyl-6-Schiff enylaminofluorane, etc.; thiazine compounds include nizoyl leucomethylene blue, nitropenzyl leucomethylene blue, etc.; spiro compounds include 3-ethyl-birose nanotopyran, 3-benzyl spiro- dinaphthopyran, 3-methyl-naphtho-
(3-methoxy-benzo)spiropyran, 3-propyl-spiro-dibenzopyran, and the like. These may be used alone or in combination.

Examples of electron-accepting compounds include phenolic compounds,
These include organic acids or their metal salts, oxybenzoic acid esters, etc. Phenol compounds are particularly preferred because their melting points are close to the desired recording temperature and there is no need to use low melting point compounds or they can be used in small amounts. Used, for example, Tokukosho≠! -/1AO No. 39, Tokko Akira! /-2YI3
It is described in detail in No. 0, etc. Specifically, Hiro-Tasha IJ methylphenol, Hiro-phenylphenol,
Hiro-Hydroxydiphenoxide, α-naphthol, β-
Naphthol, methyl-Hiro-hydroxybenzoate, co9.2'-dihydroxybiphenyl, +2. +2-bis(≠-hydroxyphenyl)propane (bisphenol A)≠, μl-inpropylidene bis(2-methylphenol L/, /-bis-(≠-hydroxyphenyl)
Cyclohexane, /,/-his-(3-chloro-ψ-hydroxyphenyl)-2-ethylbutane, ≠′-secondary imbutyltin diphenol, benzyl hydroxybenzoate, ≠-octyl hydroxybenzoate, 3. ! - tertiary butylsalicylic acid, 3. j-
Examples include di(-α-methylbenzyl)salicylic acid.

Next, a specific example of the method for producing a heat-sensitive recording material according to the present invention will be shown. The most common method for producing heat-sensitive recording materials is to prepare an electron-donating colorless dye and an electron-accepting compound separately in a water-soluble polymer solution of -10% by weight. - Disperse by means such as lumill, sand mill, etc.
After mixing, it is created by adding inorganic pigments such as kaolin, talc, and calcium carbonate. Low-density polyethylene may be mixed with this, and further a thermofusible compound, gold-plated soap, etc. may be added as necessary.

Coating liquids are generally applied onto base paper.

Generally, the coating amount is λ~/09/m2 as solid content
The lower limit is determined by the density at the time of color development by heating, and the upper limit is determined mainly by economic constraints.

(Examples of the Invention) Examples are shown below, but the present invention is not limited only to these examples.

Examples 1 to 4 Electron-donating colorless dyes shown in Table 1! y was dispersed in a ball mill overnight with an aqueous solution of 5% polyvinyl alcohol (Saponity: Tata% Polymerization: 1000) in a ball mill. Meanwhile, add j% of the electron-accepting compound λOII shown in Table 1.
The mixture was dispersed with 200 g of a polyvinyl alcohol aqueous solution for one day. After mixing the dispersions of these lambda foods, 20 g of calcium carbonate was added to ensure good dispersion, and low density polyethylene (Minarin manufactured by Mitsui Polychemicals) was added with an average particle size of 0.
, Ok-/J tlm) was added to prepare a coating liquid.

1-11ffl of the 1021m2 double tatami mat on the right
Apply it so that the coating amount is 79/m 2 for the field shape,
A coated paper was obtained by calendering.

Comparative Example 1 In Example 1, a coated paper was prepared using the low density polyethylene added having an average particle size of 0.02 μm separately.

Comparative Example 2 In Example 1, a coated paper was prepared using the low density polyethylene added having an average particle size of 23 μm separately.

Comparative Example 3 In Example 1, a coated paper was prepared by adding the low density polyethylene particles to 60% by weight of the total solid content of the coating liquid.

Comparative Example 4 In Example 1, a coated paper was prepared by changing the amount of low density polyethylene particles added to 2.5% by weight of the total solid content of the coating liquid.

Comparative Example 5 In Example 1, high-density polyethylene particles (density O0 69/cm, average particle diameter j, 2 μm) were added in place of the low-density polyethylene particles to prepare a coated paper.

Comparative Example 6 In Example 1, coated paper was prepared using a coating liquid to which no low-density polyethylene particles were added.

The heat-sensitive recording material prepared as described above was tested for friction fog resistance.

Furthermore, the print color was developed and the sensitivity and color image storage stability were measured.

Evaluation was performed based on the following criteria.

Friction fog ◎Even if a thermal paper sample is rubbed on a hard object such as a glass plate, almost no color develops.

○Slight amount when rubbed on a glass plate, etc. The color develops on soft paper such as cardboard. Most of the color comes out when you rub it on something. do not.

△Slightly rubbed on cardboard, etc. Develops color.

×Color develops by rubbing it on cardboard, etc.

Sensitivity ○ Sensitivity decrease is less than j% compared to when no additives are added.

△Compared to when no additives are added Sensitivity decrease is 5% or more and less than 10%.

×Compared with the case without additives Sensitivity decrease is 10% or more.

Preservability ○The afterimage rate after storing the printed part for 60002 hours and ≠o 'C O%RHs for 2≠ hours is 5% or more.

△ Printing part for 1,00C2≠ hours and ≠ o’C %RH, 2≠ Time preservation The afterimage rate is more than 0% but less than 0%. Full.

×Print part 1. O0C2≠time and≠ o’CriQ%RHX　2≠Time preservation The afterimage rate is less than to%.

From the results in Table 1, it can be seen that the heat-sensitive recording material using the low density polyethylene particles according to the present invention has an extremely excellent anti-friction fog effect.

Claims (1)

[Claims] In a heat-sensitive recording material in which a heat-sensitive recording layer containing an electron-donating colorless dye and an electron-accepting compound is provided on a support, low-density polyethylene particles with an average particle size of 0.0.3 microns to 14 microns are used as a heat-sensitive layer component. j~1 for the total weight of
．． A heat-sensitive recording material characterized by containing 0% by weight.