JPS61139482A - Thermal recording paper - Google Patents

Abstract

PURPOSE:To raise water resistance of a thermal recording paper as well as lessen the occurrence of blocking phenomenon by providing a back coat containing an alkali salt of styrene-maleic acid copolymer and a high polymer latex on the back of a supporter. CONSTITUTION:A thermal recording layer containing a colorless or lightcolor electron donative dye precursor and an electron acceptor substance capable of producing a color upon reaction with the said dye precursor is provided on the surface of a supporter, and a protective layer containing a water-soluble polymer binder and a pigment is laminated on the thermal recording layer. A back coat containing alkali salt of styrene-maleic acid copolymer and a high polymer latex is provided on the back side of the supporter to form a thermal recording material. As the alkali salt of styrene-maleic acid copolymer used in the back coat, sodium salt, ammonium salt, etc., may be cited.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to thermal recording paper, and more particularly, it relates to a thermosensitive recording paper, and more specifically, to a thermosensitive recording paper, and more particularly to a heat-sensitive recording paper, it relates to a normally colorless or light-colored electron-donating dye and an electron-accepting dye that develops color by reacting with the electron-donating dye. The present invention relates to thermal recording paper containing a substance.

(Prior art) A thermosensitive recording paper that produces a recorded image by reacting an electron-donating colorless dye precursor (hereinafter referred to as a color former) and an electron-accepting compound (hereinafter referred to as a color developer) by heating was developed by the Japanese Patent Publication Publication No. 4cj. -/AC
Ojp issue, special public show 1t! -44/40 etc. In recent years, these thermal recording papers have been used for electronic computers, terminal printers for various measuring devices, facsimile storage, and the like.

On the other hand, the drawbacks of heat-sensitive recording paper include the fact that when various chemicals TE are mixed with oil or the like, the recorded image becomes discolored and cools, resulting in fogging. These drawbacks are serious problems in practice, and improvements are desired.

For the purpose of these improvements, a protective layer is provided on the heat-sensitive layer. Sympathetic thermal recording paper provided with a protective layer is disclosed in, for example, JP-A No. 1 Alr-303417 and JP-A No. AY-3.
iri! No. Tokukai Akira! J-/91μθ No., JP-A-Shojμ-
/μ7j No. 1, Tokukai Sho! μ-53 issue, JP-A-Sho tμm
//1lr37, Tokukai Sho z4cmi2r31A,
Japanese Patent Application Publication No.11. -/261ri No. 3, JP-A-Shoj A -'/
No. 72223, JP-A No. 17-10130, JP-A-Shoj
7-22≠ri No. 1, JP-A Show Tough-701322, JP-A Show J7-io'yrra No., JP-A Show 5R-ZJaru No., JP-A Show I! -, , /ri No. 31t, etc.

By providing a puncture coat layer made of a water-soluble polymer binder and an inorganic organic pigment on the back side of the MatS support, running properties on actual machines are improved, sheet curls are corrected, and chemical resistance is imparted from the back side. Therefore, by providing the above-mentioned protective layer, the commercial value of the thermal paper can be improved.

However, conventional backcoat layers have poor water resistance due to the water-soluble polymer binder contained therein, and the backcoat layer swells under high humidity, resulting in poor contact between the front and back surfaces.
However, this method has the disadvantage of causing problems (hereinafter referred to as blocking), which impairs the product value. As a countermeasure against this problem, the use of an alkali salt of an inbutylene-maleic anhydride copolymer has been disclosed (Japanese Patent Application Laid-Open No. 2003-100003), but it is insufficient in terms of water resistance.

(Object of the Invention) The object of the present invention is to improve the above-mentioned drawbacks of the conventional pack layer, and to provide a thermosensitive recording paper which has excellent water resistance, less occurrence of blocking, and improved sheet curling and runnability. That's true.

(Aspects of the Invention) The thermosensitive recording paper according to the present invention provides a thermosensitive recording layer containing a normally colorless or light-colored electron-donating dye precursor and an electron-accepting substance that develops color by reacting with the electron-donating dye precursor. This is a heat-sensitive recording paper which has a protective layer on a support which contains a water-soluble polymer binder and a pigment on the recording layer, and an alkali salt of a styrene-maleic acid copolymer and a polymeric acid copolymer on the back side of the support. This is a heat-sensitive recording paper characterized by having a back coat layer containing molecular latex.

To form the back coat layer of the present invention, a coating layer containing a styrene-maleic acid copolymer alkali salt and a polymer latex is applied to the back surface of the support.

Examples of the styrene-maleic acid copolymer alkali salt used in the back coat layer of the present invention include styrene-maleic acid copolymer sodium salt, styrene-maleic acid copolymer ammonium salt, etc. C. Styrene-maleic acid copolymer ammonium salt It is a copolymer ammonium salt.

The degree of polymerization of the styrene-maleic acid copolymer alkali salt is
100-1000 is preferred, especially l! 00-2100
Preferably, the range is .

Moreover, a part of the ammonium salt may be esterified, and esterification WIrl is preferably 31% to 0%.

However, examples of the polymer latex used in the puncture coat layer according to the present invention include styrene-butadiene copolymer latex, carboxy-modified styrene-7'tadiene copolymer latex, and styrene-butadiene-vinylpyridine ternary copolymer. Latex, acrylic ester copolymerization latex, modified acrylic ester copolymerization latex, child tyrene copolymerization latex, vinyl acetate copolymerization latex,
Vinyl acetate-acrylic acid copolymerization latex, vinyl acetate-ethylene copolymerization latex, acrylic acid-butadiene copolymerization latex, acrylic acid-styrene-butadiene copolymerization latex, etc., preferably styrene-butadiene copolymerization latex, modified acrylic Examples include acid ester copolymer latex.

The mixing ratio of the polymer latex and styrene-maleic acid copolymer alkali salt is 0-1000% by weight, more preferably 10-100% by weight, based on the polymer latex. be.

The back coat layer of the thermosensitive recording paper according to the present invention preferably contains a pigment. Pigments include inorganic pigments such as zinc oxide, calcium carbonate, barium sulfate, titanium oxide, silica, amorphous silica, lithopone, talc, waxite, kaolin, calcined kaolin, aluminum hydroxide, urea-formalin resin, polyethylene, etc. Organic pigments are preferred.

The coating amount (dry weight) of the puncture coat layer is 0°2~j
, Ojl/m preferably 0, 2~j,
It is 097m. The amount of the styrene-maleic acid copolymer alkali salt and polymer latex in the back coat layer is io, 2oo% by weight of the pigment, more preferably -2j~7! Weight%. In order to satisfy the running properties on actual machines, the smoothness of the back coat layer is u30-0.
0 seconds (JIS PitlF)>E-fL<', especially to-tro seconds (JIS Pjj/Iri) is most preferable.

A surfactant may be added to the coating solution for stability and defoaming of the coating solution after dispersion.

In order to form the heat-sensitive coloring layer of the present invention, in addition to the coloring agent (leuco dye) and color developer that are commonly used in this field, thermofusible substances such as organic or organic substances may be used as necessary. : A coating layer containing inorganic pigments, binders, etc. is applied to a paper or composite resin film base.

The color former and the color developer are each separately dispersed in a water-soluble polymer (binder) using a means such as a ball mill. Dispersion is carried out until the volume average particle diameter becomes less than 5 μm, more preferably less than 2 μm. After dispersion, the three components are mixed to form a heat-sensitive coating liquid.

Examples of the coloring agent used in the present invention include triarylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, and spiropyran compounds. Some examples of these include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (i.e. crystal violet lactone), 3
*3-bis(p-dimethylaminophenyl)phthalide,
3-(p-dimethylaminophenyl)-3-(/+3-
Dimethylindol-3-yl)phthalide, 3-(p-
Dimethylaminophenyl)-J-<cometerindol-3-yl)phthalide, etc., and diphenylmethane compounds include μ, tA/-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoolamine, N-2, μs' -) dichlorophenylleucoolamine, etc., and the quinanthene compounds rhodamine (p-nitroanilino) lactam, rhodamine B (p-chloroanilino) lactam, 2-dibenzylamino-6-diethylaminofluoran, λ- Anilino 4-diethylaminofluorane, 2-anilino-3-
Methyl-6-diethylaminofluorane, 2-anilino-3-methyl-A-N-cyclohexyl-N-methylaminofluorane, co-anilino-3-methyl-4-N-
Ethyl-N-yneamylaminofluorane, 2-〇-dichloroanilino-6-dinithylaminofluorane 2-m
-chloroanilino-6-diethylaminofluorane, co('t''-dichloroanilino)-6-diethylaminofluorane, 2-octylamino-6-diethylaminofluorane, 2-dihexylamino-6-diethylaminofluorane, 2- m-trichloromethylanilino-6
-diethylaminofluorane, λ-butylamino-3-
Chloro-6-diethylaminofluoran, 2-ethoxyethylamino-β-chloro-6-diethylaminofluoran, co-anilino 3-chloro-6-dinithylaminofluoran, co-phenylamino-6-diethylaminofluoran, λ-anilino 3-Methyl-6-cyphenylaminofluorane, 2-anilino-3-methyl-chloro-6-diethylaminofluorane, 2-anilino-3-methyl-6-dinithylamino-7-methylfluorane, λ-aniline- 3-Methoxyt-dibutylaminofluorane, λ-0-chloroanilino-6-cyptylaminofluorane, λ-p-chloroanilino-3-ethoxy-6-diethylaminofluorane, 2-phenyl-
4-diethylaminofluorane, 2-o-/chloranilino-4-p-furanilinofluorane, λ-anilino 3-A: ntadecyl-6-diethylaminofluorane, 4-anilino-3-ethyl 6-sil Butylaminofluorane, 2-anilino-3-ethyl-4-N-ethyl-N
-isoamylaminofluorane, co-anilino 3-methyl-N-ethyl-N-r-methoxypropylaminofluoran, co-anilino 3-phenyl-6-dinithylaminofluorane, 2-diethylamino-3-phenyl-6-diethylamino Fluoran, λ-anilino-3-methyl-j-N-ynamyl-N-ethylaminofluoran, etc. Thiazine compounds include benzoylleucomethylene glue, p-nitrobenzylleucomethylene blue, etc. Spiro compounds include is 3-
Methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthohyran, 3,3'-cyclolose-spirodinaphthopyran, 3-spiro-dinaphthopyran, 3
-methylnaf)-(j-methoxy-benzo)-spiropyran, 3-p4-pyl-spiro-dibenzopyran, and the like.

These may be used alone or in combination.

The color developer used in the present invention is 2,2-bis(μ'
-Hydroxyphenyl)propane (bisphenol A)
, 2.2-bis(≠-hydroxyphenyl)pentane,
J, 2-bis(4L/ -hydroxy-31,5/ -
dichlorophenyl)furopane, /, l-bis(μ′-hydroquinphenyl)cyclohexane, core 2-bis(4
c/-hydroxyphenyl)hexane, l,l-bis(μ'-hydroxyphenyl)furopane, /,/-bis(tA/-hydroxyphenyl)butane, l,l-bis(tA/-hydroxyphenyl)pentane, /, l-bis(μ'-hydroxyphenyl)hexane, /, /-bis(hiro'-hydroxyphenyl)hebutane, l,/-bis(@/ -hydroxyphenyl)octane, /, /-
Bis(IA/ -hydroxyphenyl)-comethyl-bentane, l,l-bis(≠-hydroxyphenyl)-
2-ethyl-hexane, /,/-bis(lA'-hydroxyphenyl)dodecane bisphenol, 3,j-di-α-methylbenzylsalicylic acid, 3,j-
Salicylic acids such as di-tert-butylsalicylic acid, 3-α,α-dimethylbenzylsalicylic acid, or polyvalent metal salts thereof (zinc and aluminum are particularly preferred), p-hydroxybenzoic acid R-benzyl ester, p-hydroxybenzoic acid-2 -oxybenzoic acid esters such as ethylhexyl ester, p-phenylphenol, 3.
! - Phenols such as diphenylphenol and cumylphenol are mentioned.

As a binder, for 2j6C water! % or more, and specifically, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starches, gelatin, gum arabic, casein, polyacrylamide, styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride. Examples include acid copolymer hydrolyzate, inbutylene-maleic anhydride copolymer hydrolyzate, polyvinyl alcohol, and carboxy-modified polyvinyl alcohol.

Oil-absorbing pigments include zinc oxide, calcium carbonate, barium sulfate, titanium oxide, lithopone, talc, waxite, kaolin, aluminum hydroxide, calcined kaolin, silica,
Inorganic pigments such as amorphous silica, organic pigments such as urea-formalin resin, polyethylene powder, etc. are used.

As the metal soap, higher fatty acid gold salt is used, and zinc stearate, calcium stearate, aluminum stearate, etc. are used.

As waxes, polyethylene wax, carnauba wax, paraffin wax, microcrystalline wax, fatty acid amide, etc. are used.

Antioxidants, ultraviolet absorbers, image preservation improvers, etc. can be added to this as necessary.

Examples of image preservation improving agents include phenols or derivatives thereof in which one or more of the two or more positions is substituted with an alkyl group, and among these, phenols or derivatives thereof are substituted with an alkyl group at one or more of the four positions. Phenols substituted with cross-alkyl groups or derivatives thereof are preferred. ``Furthermore, those having a plurality of phenol groups in the molecule are preferable, and those having from one to three phenol groups are particularly preferable.

The coating liquid is applied to a support such as neutral paper, high-quality paper, or plastic film and dried. When preparing a coating liquid, all the components may be mixed and pulverized at the same time from the beginning, or they may be combined in appropriate combinations, pulverized and dispersed separately, and then mixed.

To form the protective layer according to the invention, a coating layer consisting of a water-soluble polymeric binder and an inorganic or organic "pigment" is applied onto the thermochromic layer.

Examples of water-soluble polymer binders include polyvinyl alcohol,
Examples include methylcellulose, starch, carboxymethyl ester, styrene-maleic acid copolymer, diisobutylene-maleic acid copolymer, polyamide resin, polyacrylamide resin, and the like.

Pigments include inorganic pigments such as zinc oxide, calcium carbonate, barium sulfate, titanium oxide, lithopone, talc, waxite, kaolin, calcined kaolin, silica, amorphous silica, aluminum hydroxide, urea-formalin resin, polyethylene powder, etc. organic pigments are used.

The coating amount (dry weight) of the protective layer is 0.2 to j-.

Oi/rn 2 preferably rho, t~ip7m
It is 2.

If the amount of coating is too low, the resistance to various chemicals, which is the object of the present invention, will be lowered, and if the amount of fabric is multi-layered, the thermal responsiveness of the heat-sensitive coloring layer will be poor, so the amount of coating is determined depending on the requirements for both performances.

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

Example 1 2-anilino-3-method, which is a coloring agent for adjusting the heat-sensitive recording layer coating solution. Ru+-N-cyclohexyl-N-methylaminofluorane 101,10
% holyhinyl alcohol (saponification degree t%, polymerization degree 1o
oo) Aqueous solution 2177 and water λj77 were dispersed in a ball mill overnight to obtain dispersion liquid A. Similarly, benzyl p-hydroxybenzoate iog, λ, 2'-methylene-
Bis-(IA-Methi-6-Test-Butylphenol>jp, Calcium carbonate (Shiraishi Kogyo, Brilliant lj) izg, to% polyvinyl alcohol (saponified [
yr%, polymerization K"00) aqueous solution 219 was dispersed day and night in a ball mill with 10 I of water to obtain a dispersion (B).

Dispersion liquid (A) and dispersion liquid (B) were mixed at a weight ratio of 1:3, and then 27% zinc stearate dispersion l and I were added to mixed liquid 20077 and sufficiently dispersed to form a heat-sensitive coating liquid. A coating solution was prepared and applied to a base paper having a basis weight of μ7 p/rn with a solid content of j Jil/? F! It was applied and dried at 600C for 7 minutes to explode the base thermal recording paper.

On this heat-sensitive coloring layer, a coating layer coating liquid consisting of the following composition was applied to the KX to obtain a coating amount of 2,1777 m in terms of solid content.
& cloth, dried for 2 minutes at RO 0C, spread the coating layer, calendered, smoothness r 0 seconds (JIS Pl
90 Coating liquid for coating layer 10% polyvinyl alcohol 100f7%'AO% Kaolin (kaobrite) 2t, px water μOI were mixed and dispersed to obtain a coating liquid for coating layer.

On the back side of the thermosensitive recording paper obtained in the above manner, apply a puncture coat layer coating liquid consisting of the following composition at a solid content of 2 rg7m2.
The heat-sensitive recording paper of the present invention was obtained by drying for so 'C, , z minutes to release the back coat layer.

Puncture coat layer coating liquid 2t% styrene maleic anhydride copolymer ammonium salt (manufactured by Arayo Kagaku, Polymaron J lrr, degree of polymerization 2000
)If/%4L! % styrene-butadiene copolymer latex (manufactured by Nippon Zeon, N1polLX r j j )
j, & l, j O% charcoal and sium (Shiraishi Kogyo, brilliant lj) dispersion 12゜j11 water/
4. A mixed dispersion liquid was prepared from RI I.

Example 2 A thermosensitive recording paper was obtained in Example 1 except that the back coat layer was changed as follows.

2t% styrene maleic anhydride copolymer ammonium salt! 11 μO% modified acrylic ester copolymer latex (Nippon Zeon H1Nipol 2!07) 3.3g
,! θ% Calcium carbonate dispersion l Co' Js water/4
．． 2g was used as a mixed dispersion.

Example 8 A thermosensitive recording paper was obtained in Example 1 except that the back coat layer was changed as follows.

2t% styrene maleic anhydride copolymer ammonium salt, '1%''% polystyrene latex (manufactured by Nippon Zeon, N1pol LXJOj)j, tp, to
% calcium carbonate dispersion/2.19. Water l6. A mixed dispersion liquid was obtained.

Example 4 A thermosensitive recording paper was obtained by changing the back coat layer in Example 4 to the following.

Ko! % styrene-maleic anhydride copolymer ammonium salt, zi, ≠0% styrene-butadiene copolymer latex (manufactured by Sumitomo Chemical, l-gatex 5NJO7) A, J
l, 10% calcium carbonate dispersion i-2,6jis water/
Q Comparative Example 1 in which 4.29 was mixed and dispersed
%, polymerization [” ” ) 3011 s ” ' %
Kaolin dispersion (Kaobrite, Shiraishi Kogyo #>10・I
, 32.1% or more of water was mixed to prepare a dispersion t0 Comparative Example 2゜ In Example 1, a thermosensitive recording paper was obtained by changing the back coat layer as shown below.

2j% diisobutylene-maleic acid copolymer ammonium salt (INOPAN o4A, manufactured by Kuraray>izp, !θ% calcium carbonate/2.19.Water 12.19 or more were mixed and dispersed.

Comparative Example 8 A thermosensitive recording paper was obtained in Example 1 except that the back coat layer was changed to the following.

20% starch (eclipse cleft, MS-44400) 10I,
Mix and disperse 10% calcium carbonate TLS water/711 or more.

Comparative Test A comparative experiment of the sympathothermic recording papers obtained in the Examples and Comparative Examples was conducted as follows.

(1) Drop 0.2 μt of water onto the surface of the blocking recording paper, place the base paper on top of it, air dry it for 1 hour, then peel it off and check the strength of the adhesion between the recording paper and the base paper. It is better not to glue.

The evaluation is expressed as good, fair, or poor.

(2) Sheet curl A4C size recording paper at 30°C 10% in a constant temperature and humidity room.
After controlling the humidity for 1 hour at 47% Jt'C%, and then controlling the humidity at 200C and 31% for 1 hour, the heights of the four corners of the recording paper were measured and evaluated as an average. The evaluation was expressed using the following symbols.

11 - 11 --- -←〉 10 Back coat Curl is a little Curl to the surface of the heat-sensitive coloring layer Some curls (3) Traveling heat-sensitive facsimile (Kenshi IJ11.i8, UP-5'z
In step O), the heat-sensitive recording paper obtained as described above is printed and tested for sticking and adhesion to a platen roll.

The results are shown in Table 1, and it can be seen that the thermal recording paper according to the present invention is excellent in terms of sticking, blocking, and sheet curl.

Table 1

Claims (1)

[Claims] A heat-sensitive recording layer containing a normally colorless or light-colored electron-donating dye precursor and an electron-accepting substance that develops color by reacting with the electron-donating dye precursor, and a water-soluble polymer binder on the recording layer. A thermosensitive recording paper having a protective layer containing a pigment on a support, which has a back coat layer containing an alkali salt of a styrene-maleic acid copolymer and a polymer latex on the back side of the support. paper.