JPS62105686A - Pressure sensitive recording sheet - Google Patents

Abstract

PURPOSE:To improve coloring performance and to reduce pressure fogging at processing time by obtaining a coloring image by the reaction of an electron imparting colorant contained in a microcapsule having specific material, particle diameter and film thickness with an electron receiving developer. CONSTITUTION:Oily solution dissolved with polyvalenty isocyanate compound or prepolymer thereof and polyvalenty hydroxy compound together with an electron imparting colorant is emulsified and dispersed in polarizing solution for forming continuous phases. This solution is heated to form polyurethane urea resin in the oily solution or on the surface of oil droplet, thereby manufacturing a colorant-containing microcapsule. The diameter of the particle and the film thickness of the wall can be controlled by regulating the weight ratio of the resin material and colorant-containing oil and selecting the size of oil droplet at emulsifying and dispersing time. The mean diameter of the particles of the microcapsule is 6.0-12mum, and the mean film thickness of the wall is 0.10-0.40mum.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to pressure sensitive recording sheets. More specifically, the present invention relates to a pressure-sensitive recording sheet that produces a colored image by a reaction between an electron-donating color former and an electron-accepting color developer.

(Prior art) A pressure-sensitive recording sheet is made by dissolving a colorless electron-donating coloring agent in a suitable solvent and applying a microcapsule layer containing microcapsules containing oil droplets on a support. Upper paper, lower paper with a color developer layer containing an electron-accepting color developer coated on another support, and in some cases, a microcapsule layer on one side of the support and a blood color layer on the other side. It consists of a combination of inner paper coated with an agent layer, or it contains the capsules and the color developer on the same side of the support, or it contains either the capsules or the developer in the support. , and one coated with the other.

These pressure-sensitive recording sheets are disclosed in, for example, U.S. Pat.
,! TO! r, No. 970, same, 30! , &♂9
No. 2, j60.927, No. 2, 730.
No. 952, No. 3, 4t/r, No. 260, etc.

However, these pressure-sensitive recording sheets do not necessarily have satisfactory performance; for example, in order to obtain sufficient color density for typewriter printing or ball-print printing, it is necessary to However, it still has the disadvantage that the pressure fog during cutting (cutting, etc.) is still high.

(Objective of the Invention) The object of the present invention is to provide a pressure-sensitive recording material which has practically sufficient coloring performance and which significantly improves pressure fog during processing.
The aim is to provide the following benefits.

(Structure of the Invention) An object of the present invention is that the walls of the microcapsules containing a coloring agent are made of polyurethane urea resin, and the average particle diameter of the microcapsules is 6.5 mm. It is within the range of θ to 72μ, and the average thickness of the wall is θ, 10 to θ.

This was achieved using a pressure-sensitive recording sheet characterized by a pressure within the range of 90μ.

The polyurethane urea resin constituting the wall of the microcapsules according to the present invention is a polymer having a large amount in the urethane-bonded molecular chain, and polyhydric incyanate or a prepolymer thereof forms a polyhydric hydroxy compound or a polar polymer that forms a continuous phase. Refers to the resin obtained by reacting with a liquid.

Examples of the polyvalent incyanate or prepolymer used in the present invention include m-phenylene diisocyanate, b-phenylene diisocyanate, -"1'4'-)lylene diisocyanate, Nath,
214 to one tolylene diisocyanate, naphthalene/
, 4t-diisocyanate, diphenylmethane-g,
4t'-diisocyanate, 3.3'-dimethoxy-9,q'-biphenyl-diisocyanate6. ? ,,
? '-dimethyldiphenylmethane-a, 4t'-diincyanate, xylylene-/, kudiisocyanate, xylylene-/, 3-diisocyanate, g, g'
- Schiffer propane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate,
Propylene-/, 2-diisocyanate, butylene-/
, 2-diisocyanate, ethyridine diisocyanate, cyclohexylene-/, 2-diisocyanate, cyclohexylene-/, 4t-diisocyanate, etc. diincyana-1', "+" +y //),
Riphenylmethane triisocyanate, toluene-2
, &, triiso7anate such as j-triisocyanate, polymethylene polyphenylinocyanate, tt,
tx'-dimethyldiphenylmethane, 2. ．． 2', evening
Tetraisocyanate monomers such as 61-tetraisocyanate or these polyvalent incyanates are added to compounds such as polyvalent amines, polyvalent carboxylic acids, polyvalent thiols, polyvalent hydroxy compounds, epoxy compounds, etc.
Isocyanate foundations/Isocyanate groups with 23 or more remaining in the molecule are mentioned.

Examples of polyhydric hydroxy compounds include aliphatic compounds with L<[F
Examples include aromatic polyhydric alcohols, hydroxypolyesters, hydroxypolyalkylene ethers, alkylene oxide adducts of polyhydric amines, and the like. For example, catechol, resorcinol, hydroquinone, /, cone-hydroxy-methylbenzene, /, 3-dihydroxy-y-methylbenzene, 3. Goojihydrox/-7-methylbenzene, 3. j-dihydroxy-/-methylbenzene, i,4t-dihydroxyethylbenzene, /, 3
-naphthalenediol, /, J--naphthalenediol, co, 2-naphthalenediol, 2.3-naphthalenediol, o, o' -biphenol, p, p'
-biphenol, /l/'-biconaphthol, bisphenol A, J,, 2'-bis-(4t-hydroxyphenyl)butane 6.21λ'-bis-(4t-hydroxyphenyl)-iso, methane, /, /'-bisou (q
-hydroxyphenyl)-cyclopentane, /, /'-
Bis(couhydroxyphenyl)-cyclohexane,
2,-'-bis-(q-hydroxy-3-methylphenyl)-furo/l, bis-(,2-hydroxyphenyl)-methane, xylylene diol, ethylene glycol, /, 3--10 pyrene glycol, /, 4t-7' ethylene glycol, /, J"--<methanediol, /,
6-hebutanediol, /, 2-hebutanediol, /
I♂l otanediol, /, /, /-) IJ methylol proagne, hexa/triol, pentanerythritol, glycerin and sorbitol, aromatic or aliphatic polyhydric alcohols, etc. are used.

The hydroxy polyesters used are, for example, those obtained from polycarboxylic acids and polyhydric alcohols. Examples of polycarboxylic acids for producing hydroxy polyesters include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, isophthalic acid, terephthalic acid, gluconic acid, and the like. As the polyhydric alcohol, those mentioned above can be used.

Hydroxy polyalkylene ethers are, for example, condensation products of alkylene oxides and polyhydric alcohols. As the alkylene oxide, butylene oxide or allene oxide used to produce the hydroxy polyalkylene ether, and as the polyhydric alcohol, the compounds mentioned above are used.

The alkylene oxide adduct of a polyvalent amine refers to a compound in which seven or more hydrogen atoms in the amine group of a polyvalent amine are replaced with alkylene oxide. Examples of polyvalent amines for producing alkylene oxide adducts of polyvalent amines include aromatic polyvalent amines such as 0-phenylenediamine, b-7 2-diamine, diaminonaphthalene, ethylenediamine, 3- -! There are aliphatic polyvalent amines such as robylene diamine, diethylene triamine, and o-hexamethylene diamine. Examples of alkylene oxide adducts include ethylene oxide, propylene oxide, and butylene oxide.

The most typical polar liquid that forms the continuous phase is water, but equivalents thereof, such as ethylene glycol, glycerin, butyl alcohol, octyl alcohol, etc., can also be used.

A protective colloid or a surfactant may be used to emulsify and disperse the oily liquid in the polar liquid. Examples of protective colloids include hydrophilic polymeric substances such as gelatin, gum arabic, casein, carboxymethyl cellulose, starch, and polyvinyl alcohol. Examples of surfactants include ionic ones such as alkylbenzenesulfonic acids, polyoxyethylene sulfates, funnel oil, etc.
There are nonionic ones such as polyoxyethylene alkyl ether, polyoxyethylene, and sorbitan fatty acid ester.

The microcapsules according to the present invention are manufactured by the following method. An oily liquid in which the polyvalent isocyanate compound or a prepolymer thereof and the polyvalent hydroxy compound are dissolved together with an electron-donating coloring agent is placed in a polar liquid (containing a protective colloid and a surfactant) forming a continuous phase. Emulsify and disperse at room temperature.

This emulsified dispersion is heated to form a polyurethane urea resin from inside the oil liquid or on the surface of the oil droplets, thereby producing color former-containing microcapsules.

The average particle diameter and average wall thickness of the microcapsules are determined by adjusting the weight ratio of the polyurethane urea resin raw material used and the coloring agent-containing oil that is the core material of the capsules, and by adjusting the size of the oil droplets during emulsification and dispersion. You can control it by choosing. According to the present invention, microcapsules having a specific capsule wall material, specific particle diameter, and wall thickness can be obtained in this manner.

The average particle diameter of the microcapsules according to the present invention is 6.0
~72μ, more preferably 7°θ~ri, θμ
, more preferably 2. ! ~T,! μ.

In addition, the average thickness of the wall of the microcapsule is 0°1o-o
, 4toμ, more preferably 0゜-〇~0.3
0μ, more preferably 0.2~0°21μ.

In this specification, the average particle diameter d of the microcapsules
and the average film thickness δ of the microcapsule wall are values determined by the following method.

A. Method for measuring the average particle diameter d of microcapsules The microcapsule liquid was coated with a binder (PVA) on a surface-treated PET film base, and after platinum-palladium vapor deposition, a 5-tZo type scanning electron beam manufactured by Hitachi, Ltd. Magnification using a microscope! 1,000 to 70,000 times, acceleration voltage 2θKV
The particles were photographed using a film (Polaroid Corporation's Borano Gun GXJ Land Film!, 2), the particle size was measured from the photograph, and the average particle diameter d (μ) was calculated by averaging.

B, −, d11 of the average thickness δ of the wall of the microcapsule
] 6. Remove the surface treatment of Kurocapsule 0 using the standard method. The microcapsules were coated on a PET film base, embedded in epoxy resin, left to solidify overnight at a temperature of 0°C, and cut into exactly half using an ultramicrotome (Portaplum Co., Ltd., MT-[type]). An ultra-thin section was prepared using a transmission electron microscope, a new model HU-12A manufactured by Hitachi, at a magnification of approximately 70,000 to 0,000 times and an accelerating voltage of θθ.
The film was photographed using a KV film (Fuji Photo Film Co., Ltd., Fuji Electron Microscope FG Film), the film thickness was measured from the photograph, and the average film thickness δ(μ)'5I was calculated.

In the present invention, since the microcapsule coating solution is usually a capsule dispersion, it may be coated directly onto the support. It is also possible to use binders such as latex (with or without separating the microcapsules from the capsule dispersion).
Styrene-butadienol rubber latex, etc.), water-soluble polymer substances (starch, carboxymethylcellulose,
Polyvinyl alcohol, gum arabic, casein, gelatin, etc.) can also be added to the coating. At this time, the amount of binder is adjusted to improve the balance between color density and pressure blur.
The amount is preferably 30 parts or less (parts by weight) based on part ', more preferably 20 parts or less above y part, and most preferably 20 parts or less above part y and below part lf.

Furthermore, the capsule coating liquid fc contains a capsule reinforcing agent such as fine cellulose powder (U.S. Pat. No. 2,7/7) in the capsule layer.
/, 376), polymer fine powder (U.S. Pat. No. J, 62)
J′,? ,,? No. J), fine starch powder (British Patent No. 6)
．． It is also possible to add microcapsules containing no coloring agent (UK Patent No. 6.-j!, No. 99/). It is preferred that the capsule reinforcing agent is not present in a layer, but rather is dispersed in or on the capsule layer.

The present invention does not limit the oily liquid for dissolving the borium 1/tan urea resin raw material and coloring agent in the microcapsules, and any conventionally known solvent can be used.

Examples include aromatic compounds such as alkylated naphthalene, algylated biphenyl, hydrogenated terphenyl, and alkylated diphenylmethane (the number of carbon atoms in the alkyl group is approximately /-!, and the number of alkyl groups is /~g). synthetic oil, black 7/
, naphtha, petroleum distillates such as paraffin oil, chlorinated, aliphatic synthetic oils such as e-roughin, vegetable oils such as cottonseed oil, soybean oil, linseed oil, or mixtures thereof. The concentration of the coloring solvent solution is not particularly limited.

The color former in the present invention is a colorless compound that develops color when it comes into contact with a solid acid, and can also be defined as an electron-donating colorless organic compound.

In the present invention, the type, properties, etc. of the coloring agent do not substantially affect the present invention. Therefore, all kinds of color formers can be used. Examples include 1-IJ arylmethane compounds, diarylmethane compounds, hexa/thene compounds, thiazine compounds, and spiropyran compounds.

Examples of color developers that react with the color forming agent used in the recording notebook of the present invention include acid clay, activated clay, attapulgite, theolite, bentonite, clay materials such as kaolin, metal salts of aromatic carboxylic acids, and phenolic resins. can give.

These color developers are applied to a support such as paper along with a binder such as styrene butadiene latex.

The performance of the microcapsule sheet for pressure-sensitive recording of the present invention was tested using the following color developer sheet.

[Preparation of color developer sheet]

20 parts of water, 2 parts of zinc oxide, 72 parts of calcium carbonate, and 3 parts
1! -G 7 parts of zinc α-methylbenzylsalicylate were added and mixed 2, and then dispersed for 30 minutes using an attritor, and carboxy-modified SBR latex was added at a solid content of 2
．． ! part and 70% PVA (degree of saponification 9 degrees of polymerization/θθ0
) Add 7.2 parts of the aqueous solution and stir evenly to combine with the coating solution (
~Ta. This coating liquid! Dag on the base paper of θg/m2, /
A developer sheet was obtained by coating and drying using an air knife cleaning machine capable of coating a solid content of m 2 .

How the pressure recording sheet according to the present invention provides useful practical effects will be explained in more detail with reference to the following examples, but the present invention is of course not limited to the examples.

Example: A polyvalent incyanate compound (tolylene diisocyanate 37) was added as a wall film-forming substance to an aromatic oil-based liquid in which 30 g of diisopropylnaphthalene, 2 g of crystal violet lactone, 3 g of penzoyl leucomethyl blue θ, and 3 g of a coloring agent were dissolved. A seventh solution was prepared by mixing 7 g of a polyhydric hydroxy compound (ethylenediamine-propylene oxide adduct) at a temperature of 200C or less.

Next, add 3 g of polyvinyl alcohol and 5 g of sodium salt of U carboxymethyl cellulose to water at 20°C.
was dissolved. Furthermore, 7 g of funnel oil (emulsifier) was added to prepare a secondary solution.

While vigorously stirring the secondary solution, the seventh solution was poured to form an oil-in-water emulsion. When the size of the oil droplets reached θμ, the stirring was weakened, and then 100g of 100C water was added to the emulsion.
The temperature of the system was gradually raised to 250C, and at this temperature 6
I kept it for 0 minutes.

To the capsule liquid obtained in this way, a /j% aqueous solution of polyvinyl alcohol and carboxy-modified SBR latex were added to the solid content of 12g x starch particles (average particle size /!
μ) 2 og was added.

Then, water was added to adjust the solid content concentration to 10% to prepare a coating solution.

This coating solution was coated onto a 4tOg/rn2 base paper using an air knife coating machine and dried so that the dry weight was <t and 0g7m2 to obtain a microcapsule sheet.

The average particle diameter d and average wall thickness δ of this microcapsule are d=a, /μ, δ=0. /
It was ♂μ.

Example 2 The same formulation as in Example 2 was used, and by controlling the size of oil droplets during emulsification and dispersion, the average particle diameter of the microcapsules was d = ♂, /μ, and the average wall thickness was δ = 0.
．． A 27μ microcapsule sheet was obtained.

Example 3 The same procedure as in Example 3 was carried out except that the type of coloring agent used was changed. That is, 30g of diisopropylnaphthalene
, 32,4-bis-diphenylaminofluorane/
, &g was used. Otherwise, the average particle diameter of microcapsules was d = ♂ by controlling the size of oil droplets during emulsification dispersion in the same manner as in Example
θμ, average wall thickness δ=0.2! A microcapsule sheet of Fμ was obtained.

Example Z The same procedure as in Example 2 was carried out except that the type of polyvalent incyanate compound used as the wall film-forming substance was changed. That is, a 371 mol hexamethylene diincyanate/trimethylolpro adduct was used as the polyvalent incyanate compound. The rest is the same as in Example/1, by controlling the size of oil droplets during emulsification dispersion, the average particle diameter of the microcapsules is d = J', tμ, and the average wall thickness is δ = 0.27μ. Seatra'1
7'c.

Example! By using the same formulation as in Example 1 and controlling the size of oil droplets during emulsification and dispersion, the average particle diameter of the microcapsules was d = io, /μ, and the average wall thickness was 0.
A microcapsule notebook of 3'lμ was obtained.

Comparative Example/Example/The same procedure was carried out by changing the amount of wall film forming substance used. That is, the polyvalent isoneanate compound was J, 7 g, and the polyvalent hydroxy compound was 0.3 g. Otherwise, the average particle diameter of the microcapsules d=! by controlling the size of the oil droplets during emulsification and dispersion in the same manner as in Example/. , 2μ, average wall thickness δ-0,0rμ
A microcapsule sheet was obtained.

Comparative Example 2 The same procedure as in Example 2 was carried out except that the wall film-forming substance used was changed. That is, 76 g of the polyvalent iso/anate compound was 1 g of the polyvalent hydroxy compound. Otherwise, the average particle diameter of the microcapsules was d=a by controlling the size of the oil droplets during emulsification and dispersion in the same manner as in Example.

A microcapsule sheet with an average wall thickness of δ = 0.2j'μ was obtained.

Comparative Example 3 The same procedure as in Example 3 was carried out except that the amount of the wall film-forming substance used was changed. That is, the polyvalent incyanate compound is ag, and the polyvalent hydroxy compound is 0°! It was set as g. The rest was the same as in Example/1, and the average particle diameter of the microcapsules was set to d=Q by controlling the size of the emulsified oil droplets.

A microcapsule sheet with θμ and average wall thickness δ=0.07μ was obtained.

Comparative Example q The same formulation as in Example 1 was used, and by controlling the size of oil droplets during emulsification and dispersion, the average particle diameter of the microcapsules was 73.2 μ, and the average wall thickness was δ =
0.4t! A microcapsule sheet of μ was obtained.

The above-mentioned microcapsules 7-t and color developer 7-t were combined to perform an evaluation test as a pressure-sensitive recording sheet, and the results are listed in Table 7. The evaluation test was conducted using the following method.

(1) Color development test The surface of a microcapsule sheet containing a color former was layered on a color developer sheet, and pressure printing was performed using a typewriter to develop color on the surface of the color developer sheet. After 7 days had elapsed after color development, the density of the coloring material ≦/θnrn was measured using a Hitachi Color Analyzer Model 3θ7, and this was designated as Dtype.

(2) Pressure Resistance (Pressure Fog) Test The surface of the microcapsule sheet containing a color former was placed on a developer sheet and a load of θKg/cm2 was applied to cause fog to develop on the surface of the developer sheet. After 3 days had elapsed after color development, the density of the chromophore at 67θnm (D/θ) was measured in the same manner as in the color development test. From this value, the fresh yield before coloring iD f r
e sh l Subtract this as a reference and add this to D.
fog (Dfog=D 610-D f res
h). (However, in the above evaluations (1) and (2),
Regarding Example 3, from the value of the max loss of the coloring body!
The study was conducted at a wavelength of 9θnm. ) The normally required color density and fog density are each 0.3o≦Dtyp.
e≦θ, <10 and Dfog≦0.02. This was used as the criterion. Therefore, the larger the value of the ratio Dtype/Dfog of color density to fog density, the better the performance, and a value of λo or more was considered good performance.

As shown in Table 1, the microcapsule sheet of the present invention has a much larger ratio of color density (Dtype) to pressure fog (IDfog) than the comparative microcapsule sheet. It can be seen that the Capri value itself is within the standard, which indicates that it is extremely excellent.

Claims (1)

[Claims] In a pressure-sensitive recording sheet that obtains a colored image by a reaction between an electron-donating color former and an electron-accepting color developer, the electron-donating color former has a polyurethane urea resin wall and has an average particle diameter of 6.0 to 12 μm. 1. A pressure-sensitive recording sheet, characterized in that the pressure-sensitive recording sheet is contained in microcapsules having an average wall thickness of 0.10 to 0.40μ.