JPH0355289A - Thermosensitive recording sheet - Google Patents

Abstract

PURPOSE:To obtain a thermosensitive recording material having good head matching properties and high chemical resistance by containing pigment having a mean particle size of 0.1-1mum in a protective layer in an amount of 0.5-40% on a dry wt. basis. CONSTITUTION:A protective layer containing pigment having a mean particle size of 0.1-1mum in an amount of 0.5-40% on a dry wt. basis is provided on a thermosensitive color developing layer. In case of pigment having the mean particle size smaller than 0.1mum, secondary flocculation is generated and coating surface quality and chemical resistance are deteriorated. In case of pigment having a mean particle size larger than 1mum, unless the protective layer is thickly applied, chemical resistance is deteriorated because of the discontinuity of the interface of the pigment and a binder and that of the upper and lower binder layers of the pigment. However, by thick coating, only thermosensitive paper inferior to color developing properties is obtained. By this method, a thermosensitive recording sheet having good head matching properties and improved in the preservability to the chemicals of a color-undeveloped part and a color-developed part is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Application The present invention relates to a heat-sensitive recording sheet K whose main components are a dye precursor and a color development rule that causes the dye precursor to develop color when heated, and more specifically. This relates to a heat-sensitive recording sheet that has improved head matching properties, system resistance, and image storage stability by providing a protective layer containing a specific IA family on the heat-sensitive sheet.

(B) Conventional technology Two-component color-forming heat-sensitive recording materials consisting of a non-various or light-colored electron-donating dye precursor and an electron-accepting color developer are primary color-forming and D%
It has many advantages such as no post-treatment is required and it is easy to handle, and it occupies the mainstream of heat-sensitive recording materials.

It is widely used in applications such as funakushimiri, recording of measuring instruments, and labels.

The properties required for this oak thermal recording paper include sensitivity suitable for each purpose, whiteness of the background, long-term stability of colored images, and the absence of sludge during recording. Hekudomanodengu properties such as not occurring, being attached to Hekudo*<States King), etc. are 4! Watered. Specific κ heat-sensitive sheet 4C has drawbacks such as the required long-term stability, including multiple inclusions of clay thickening agents and discoloration of the skin.

These phenomena occur either because the lactone ring of the dye precursor is ring-closed by a plasticizer or ethylene glycol in a fluorescent pen, and the color disappears, or when the diazo developer or the solvent in a fluorescent pen dissolves the color developer. It is thought that the skin develops color due to contact with the dye precursor.

Therefore, it has been proposed that an improvement be made by forming a film on the heat-sensitive coloring layer to prevent the penetration of the star-forming agent.

(Unexamined Japanese Patent Publication No. 48-51644, esp.) However, in the past, in order to obtain satisfactory chemical resistance for the coating film of the protective layer, it was necessary to apply a very thick coat. Therefore, the drying time was long. In addition to production problems such as the need to increase the smearing speed, it also caused a decrease in sensitivity and was undesirable.Also, there was a layer of debris on the heel, and there was paper adhesion on the heel. The stay 7 king phenomenon caused by coating also tends to worsen thick coating, and it has been proposed to add pigments with large particle sizes to improve the stay king.
33783) is the opposite of the drug property.

(C) Problems to be Solved by the Invention The object of the present invention is to provide a protective layer containing a specific pigment on a two-component heat-sensitive color forming layer of a dye precursor and a color developer. An object of the present invention is to provide a heat-sensitive recording sheet having good matching properties and strong chemical resistance.

By providing a protective layer containing 0.5 to 40% by dry weight of 1k% pigment, head matching is good, and it may be possible! It is possible to obtain a heat-sensitive recording sheet with strong chemical properties.

Particularly preferably, the protective layer has two or more layers, and the uppermost layer has an average particle diameter of 0.1 to 1 μm (by containing Q pigment,
Head machining properties are good and chemical resistance is further improved.

More preferably, if the pigment is kaolin, the henodomanoting property and chemical resistance are further improved.

In the case of pigments with an average particle diameter as small as 0.1 μm, secondary aggregation occurs, resulting in deterioration of smeared surface quality and deterioration of chemical resistance. If a pigment with an average particle size of 1 μm or more is used, a thermal paper consisting of the pigment and the binder will be produced.

The amount of the pigment used in the protective layer of the present invention is adjusted within the range of 0.5 to 40 parts by weight, preferably 0.5 to 30 parts by weight, based on 100 parts by weight of the solid content of the protective layer. is desirable. If it is less than 0.5 part by weight, the effect of the present invention will not be obtained;
If the amount is too large (0 parts by weight), color development will be poor.

The average particle diameter of the present invention is O. As a pigment of 1-1 μm,
Inorganic pigments such as kaolin, calcinable olin, calcium carbonate, talc, titanium dioxide, zinc oxide, aluminum hydroxide, silicon dioxide, aluminum oxide, colloidal silica, styrene/methacrylic acid copolymer, polystyrene resin, nylon powder, urea resin, etc. Examples include organic pigments.

Next, the materials forming the protective layer of the present invention include polyvinyl alcohol, polyethylene oxide, polyvinyl methyl ether, vinyl methyl 2-temaleic acid copolymer,
Synthetic polymer binders such as polyethyleneimine and polyvinylpyrrolidene, oxidized starch, guxtrin, dialdehyde starch, enzyme-treated starch, aminated starch, phosphate starch, hydroxyethylated starch, carboxymethylated starch, methylcellulose, ethylcellulose, Natural binders such as hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose, gelatin, casein, soy protein, and Bo! , 1 vinegar 9? ', vinyl acetate-acrylic ester copolymer, vinyl acetate-ethylene copolymer, polyacrylic ester, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, butadiene-methyl methacrylate copolymer, etc. Latex D and emulsion fins are used alone or in combinations of 24 or more.

Inorganic peroxides, organosilicon peroxides, organic peroxides, phenolic resins, amino resins, quinones, halogen compounds, incyanate compounds, carboxylic acids and acid anhydrides, which crosslink or cure the above binders; Aldehyde compounds, alcohols, epoxy compounds, boric acid, phosphorus compounds, metal oxides, metal halides, organometallic compounds, metal alkoxides, and silane compounds can be used.Other metal stearates used in heat-sensitive layers, waxes, Wetting agents, ultraviolet absorbers, surfactants, fluorescent dyes, etc. are used.

The thickness of the protective layer in a dry state is 1 to 10 μm, which is good in terms of chemical resistance, color development sensitivity, and printability.

As dye precursors used for thermosensitive coloring, (1) crystal violet lactone (2) 3-indolino-3
-p-dimethylamino-7enyl-6-dimethylaminophthalide (3) a-ethylamino-7-chlorofunoleolane (
4) a-ethylamino-7-cyclohexylaminofluorane 3-diethylamino-5-methyl-7-t-(5) (7) (8) (9) [10 αD a0 Luolan 3-diethylamino-6-methyl- 7-p-Butylanilinofluoran 2-(N-7enyl-N-ethyl)aminofluoran 3-diethylamino-7-dibenzylaminofluoran 3-cyclohexylamino-6-chlorofluoran 3-diethelamino-6-methyl -7-xylidino7luorane2-anilino3-mether-6-(N-ethyl-9-}
3-Virrolidino-6-methyl-7-anilinofluoran α4 3-Virrolidino-7-cyclohexylaminofluorane 09 3-Piperidino-6-methyl-7-toluidinofluorane 11 3-Biberidino-6 -Methynole-7-anilinofluoran un3-(N-methylcyclohexynoleamino)-6-
Methyl-7-anilinofluorane (1lll3-diethylamino-7-(m-}lifluoromethylanilino)fluoran tl'j 3-diethylamino-6-methyl-7-chlorofluoran■ 3-dibutylamino-6- Methyl-7-anilinofluorane Next, representative examples of the phenolic substance or organic acid (color developer) used in the present invention will be shown.

(1) 4,4'-isoglopylidenediphenol (2)
4.4'-isobropylidene bis(2-chlorophenol) (3) 4.4'-isobropylidene bis(2-tertiarybutylphenol) (4) 4.4'-Secondary butylidene diphenol< 5) 4.4'-(1-methylnonolemanoleheki・
diphenol (6) 4-phenylphenol (7) 4-hydroxydiphenoxide (8) Methyl-4-hydroxybenzoate (9) Phyl-4-hydroxybenzoate (10) 4-hydroxyacetate Phenone (6) Salicylic acid anilide (self) 4,4'-cyclohexylitene diphenol (2
)4.4'-Cyclohexylidenebis(2-methylphenol) α4) 4. 4'-benzylidenephenol φ). 4. 4'-thiobis(6-tert-methyl-3-methylphenol) (16) 4. 4'-isopropylidene bis(2
-methylphenol) (f7) 4. 4'-ethylenebis(2-methylphenol) QB) 4. 4'-cyclohexylidene bis(2
1 Soprovir Phenol) (19) 2. 2'-cyhydroxydiphenyl (1) 2.2'-methylenebis(4-chlorophenol) @) 2. 2'-methylenebis(4-methyl-6
(22) 1,1'-bis(4-hydroxyphenol)-cyclohexane (Z3) 2. 2-bis(41-hydroxyphenyl)propane (24) Novolac type phenolic resin (25) Halogenated novolak type phenolic resin (26)
) α-naphthol (27) β-naphthol (2B) 3. 5-di-t-butylsalicylic acid (2
9) 3. 5-di-α-methylbenzylsalicylic acid (3)) 3-Methyl-5-t-butylsalicylic acid (3)
1) Phthalic acid monoanilide paraethoxybenzoic acid (32
) bis(4-hydroxyphenyl)sulfone (3B)
4-Hydroxy-4'-isoprobyloxydiphenyl sulfone (34) C-(3-71J-4-hydroxyphenyl) sulfone (35) Varapendyloxybenzoic acid (36) Parahydroxybenzoic acid pedyl ester The thermal recording paper of the present invention can be obtained by the following method. That is, a phenolic substance or an organic acid, and a dye precursor that develops color with the phenolic substance or organic acid are crushed separately or simultaneously in a crusher into fine particles, mixed with a binder, a pigment, etc., and then crushed as necessary. Apply various additives according to your needs! of! ! I make it.

Examples of the binder include starch, hydroxyethylcellulose, methylenecellulose, boribiyl alcohol, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyacrylamide, carpoquin methylcellulose, gum arabic, casein, etc. A water-soluble binder such as latex such as styrene-butadiene latex can be used.

Examples of the pigment include diatomaceous oxide, Merck, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-ormaline resin, and the like.

In addition, higher fatty acid gold M salts such as zinc stearate and calcium stearate, waxes such as paraffin, paraffin oxide, polyethylene and polyethylene oxide, wetting agents such as dioctyl sulfosuccinate, benzophenone,
Ultraviolet absorbers such as penzot'7zo-k yarn, surfactants, fluorescent dyes, etc. are used.

Paper is mainly used as the support for the heat-sensitive recording sheet according to the present invention.
It is possible to use a sheet of laminated paper, metal foil, etc. alone or in combination.

The mold treatment of the heat-sensitive coloring layer and the protective layer is performed using the equipment and equipment used,
Air-Nai 7 coater, Roll coater Rodco-11
+, force-f coaters, flade coaters, etc. are used.

Furthermore, in order to improve the surface smoothness of the molded material, machine calender, super calender, cross calender, brushing, etc. can be used.

(E) Function Head matching property for states king, dregs, etc. by containing 0.5 to 40% by dry weight of pigment with an average particle size of 0.1 to 1 μm in the protective layer on the heat-sensitive coloring layer. It is possible to obtain a heat-sensitive recording sheet having good chemical resistance and high chemical resistance.

The reason for this effect is that the specific minute pigments are uniformly dispersed in the protective layer such as the constriction wound, resulting in a more uniform film than when using large-particle particles. It is considered to be highly effective in protecting against the penetration of lubricants, oils, etc. Regarding head matching properties, it is expected that in the heated state during color development, the continuous presence of the 11CM material on the surface weakens the close layering between the head and the sheet, leading to better stagnation and debris.

In particular, when the protective layer is 2J or more, the chemical resistance is further improved due to the lower layer's protection, and when combined with the statesking and scum improvement effect of the upper layer containing fine grains, in the case of a single layer protective layer. A better heat-sensitive recording sheet can be obtained. In particular, when kaolin gold is used as the iC material, a thermosensitive recording sheet with good appearance can be obtained.

(F') Examples Although some examples are shown below, the present invention is not limited thereto.

Example 1. Solution A, Solution B, and Bfi were separately dispersed in a sand grinder until the average particle size was approximately 2 μm, and a heat-sensitive I coating solution was prepared using the following formulation.

v41JL armpit 5 0 11/rr? Solid content coating amount s. 6i7rri: Apply so that
After drying, the sheet was calendered to a surface smoothness of 300 to 500 seconds, and a heat-sensitive self-recording paper was prepared.

C liquid Stir and mix the above ingredients.

i)′e. Approximately 10 minutes (100 rprn) using a homogenizer
) to sing in parts.

Add 2 parts of D solution to C tube 50@ to make 1 kE solution.

Ci was coated on the heat-sensitive recording paper in a dry amount of about 2117 cm (first retention layer), and then liquid E was applied on top of the dry weight of about 21/rI? (2) The obtained material was calendered so that the Beck smoothness was 400 seconds or more to obtain a heat-sensitive recording sheet.

Example 2 Microscopic light calcium carbonate (Shiraishi Kogyo: Electrical Product Name: IJIJ Anne) 15 was added to Amazon 88 of Liquid D in Example 1.
, average particle size of 0.15 μ), and 7 heat-sensitive bees were obtained in the same manner except that the second protected pigeon was constructed.

Example 3 In place of Amazon 88 in Solution D of Example 1, 9 was replaced with minute virtual calcium carbonate (Shiraishi Calcium Soup: trade name Softon 220).
A heat-sensitive recording sheet was obtained in the same manner as Sono except that the second protection material was changed to 0.0 μm (average particle size: 1.0 μm) and the second protection layer was changed to 1.0 μm.

Example 4 Instead of Solution D in Example νil1, Iso-style imitated small-scale calcium carbonate (Fuji Riki Orin Ura: trade name Carbital 90, average particle size 0.8μ) prepared to a solid content of 50% was used. ,
A thermosensitive recording sheet was obtained in the same manner except for forming the second protective layer.

Example 5 D71 of Example 1! Instead of Amazon 88, I replaced it with high-white special grade kaolin (Engelno-de*: tm product name Ultra Gloss 90, average particle size 0.4μ), and used the second grade JJill.
t-4
90 Example 6 In Example 1, without providing the first protective layer of liquid C on the thermosensitive fik paper, a dry weight of approximately 41 lwhm of liquid E constituting the second protective layer was applied, and the Bekk smoothness was 400
A heat-sensitive recording sheet was obtained by calendering for a time of at least 1 second.

Example 7 In Example 2, without providing the first protection), the second protection
EXAMPLE 8 A heat-sensitive recording sheet was obtained in a flesh-like manner, except that the dry weight of the protective layer components was coated with a dry weight of about 4,117 d. So, the dry weight is about 4g/rI? A thermosensitive recording sheet was obtained in the same manner except that the first protective layer was not provided in Example 4, but the second protective layer was not provided.
Example 10 A thermosensitive recording sheet yt was obtained in the same manner except that the dry heavy electric current was approximately 41 i/one time with one component. A heat-sensitive recording sheet was obtained in the same manner, except that the drying time was about 417rrt.

Comparative Example 1 Kaolin (
Hee-ba! A=Product name) Hydratex, average particle size 1
．． Example 2 of 0 ratio yield in which a sensitive fP4 recording sheet was obtained in the same manner except that the second protective layer was changed to A heat-sensitive recording sheet was obtained by using the same method except that the product was changed to Escalon 800 (trade name, average particle size: 3 μm) and a second protective layer was formed.

Comparative Example 3 In Comparative Example 1, the dry weight and amount of the second protective layer components were approximately 4F/1r? without providing the first protective layer. A thermosensitive recording sheet was obtained in the same manner except that 'e coating was performed.

Comparative Example 4 A thermosensitive recording sheet was obtained in the same manner as in Comparative Example 2, except that the first protective layer was not provided and the second protective layer was coated with a dry weight of about 4 lart.

Comparative Example 5 In Example 1, Dry$! was prepared using Solution C. 1! After forming the first protective layer with a weight of about 297 d, a second protective layer with a dry weight of about 2117 d was formed using liquid C on top of the first protective layer, and then subjected to κ calendering so that the Beck's average cleanliness was 400 seconds or more. A thermosensitive recording sheet was obtained.

Comparative Example 6 In Example 10EQ, DglO for Ci50s
A Kanran record sheet was obtained in exactly the same manner except for adding a gt-toothed knife.

Let's talk about the evaluation test.

K dynamic color development sensitivity l Thermal paper color development test device TH-PMD (equipped with 1 320Ω head) - Print voltage 24 V, printing pulse fil. o (8) to develop color, and Macpeth densitometer (R
Optical density was measured using D-514)''fc.

The results are shown in Table-1.

Printing was performed using K Stake King I raster coder MS8603 (manufactured by Graphtech), and noise generation, white spots in the printed area, and shrinkage were observed. The results are shown in Table 1.

Immediately after developing with K-resistant diazo aΣ diano developer (manufactured by Kobinika Pd Bunshodo), a photosensitive paper (Kobinika Pd-8A Bunshodo m> was brought into close contact with the printed surface of a thermal diary sheet, and 30 minutes had elapsed. Regarding monokappa, blackening of the background and image deterioration were observed.

The results are shown in Table-1.

K oil-based red ink discoloration test 3 Oil-based red ink Ben (Magic Ink/PQ 7 0 0
), and the degree of blackening was observed by writing 4I letters on the background.

(G) Effects of the Invention The heat-sensitive recording sheet of the present invention has good head matching properties, and the non-colored areas and colored areas have good storage stability against chemicals and the like.

Claims (3)

[Claims] (1) Provide a heat-sensitive coloring layer whose main components are a colorless or light-colored dye precursor and a color developer that reacts with the dye precursor when heated, and further coat the heat-sensitive coloring layer with a water-soluble or water-soluble dye precursor. In a heat-sensitive recording sheet provided with a protective layer containing a dispersible resin, the protective layer has an average particle diameter of 0.1 to 1 μm.
1. A heat-sensitive recording sheet characterized by containing 0.5 to 40% by dry weight of pigment. (2) The heat-sensitive recording sheet according to claim 1, wherein the uppermost layer contains the pigment of the protective layer. (3) The heat-sensitive recording sheet according to claim 1 or 2, wherein kaolin is used as a pigment in the protective layer.