JP2000141888A - Carbonless pressure-sensitive copy paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an inexpensive no-carbon pressure-sensitive copying paper of superior safety in the manufacturing process of no-carbon pressure- sensitive copying paper and also as respects use and environment. SOLUTION: Microcapsules, in which a naphthene highly refined base oil having the 30 mm2/sec. or less kinematic viscosity at 40 deg.C or higher, the 120 deg.C or higher flash point and the 75 deg.C or lower aniline point is used as a hydrophobic solvent, and also an aromatic carbonated hydrogen oil having the 10 mm2/sec. or less kinematic viscosity at 40 deg.C and the 120 deg.C or higher flash point and having at least two non-condensation or condensation type aromatic rings is used combinedly therein, are used for a no-carbon pressure-sensitive paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbonless pressure-sensitive copying paper utilizing a color-forming reaction between an electron-donating color former and an electron-accepting color developer. Further, the present invention relates to a carbonless pressure-sensitive copying paper which is excellent in manufacturing stability in a paper manufacturing process, inexpensive and excellent in safety.

[0002]

2. Description of the Related Art Basically, carbonless pressure-sensitive copying paper contains an electron-donating color former (hereinafter, referred to as a color former) dissolved in a high-boiling-point hydrophobic solvent and encapsulated in microcapsules. An upper paper having a coating layer applied on the back surface of the support, and an electron-accepting color developer (hereinafter, referred to as a color developing agent) which reacts with the color forming agent to form a color.
The underlayer coated with a coating layer containing a developer) is superimposed on each other, and the microcapsules are broken by applying pressure, and the color former and the hydrophobic solvent flow out of the microcapsules. The developer is transferred to the lower sheet, and the color developer layer is colored by the reaction between the color developer and the color developer, so that a copy image can be obtained simultaneously with printing under pressure.

[0003] When a large number of copies are desired, the above-described middle paper coated with the colorant-containing layer on the surface of the support and coated with the microcapsule-containing layer containing the color-forming agent on the back side is used as the upper paper and the lower paper. The required number of sheets are inserted and used in between. In addition, a self-coloring type pressure-sensitive copying paper formed on the same surface of the support as a layer or a mixed layer of a microcapsule containing layer containing a color former and a developer containing layer, a microcapsule containing a color former, and a developer containing Plain paper transfer type pressure-sensitive copying paper provided with a coating layer containing microcapsules and wax on the back surface of a support is also known as one form of carbonless pressure-sensitive copying paper.

As a method for producing a microcapsule enclosing a color forming agent, a coacervation method using a polyion complex of gelatin-arabian rubber, an insoluble synthetic resin at an interface between a hydrophilic liquid serving as a dispersion medium and a hydrophobic liquid to be included. An interfacial polymerization method for forming a film, an initial condensate such as a melamine-formaldehyde resin or a urea-formaldehyde resin is added from the side of the hydrophilic liquid serving as a dispersion medium, and then converted into a resin to form an insoluble film.
The tu polymerization method and the like are known, and raw materials are supplied stably at low cost, and a high-concentration microcapsule dispersion can be obtained.
Microcapsules formed by an interfacial polymerization method or an in situ polymerization method are widely used because of their high resistance to organic solvents and heat.

[0005] The coloring agents contained in the microcapsules include triphenylmethanephthalide compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, indolylazaphthalide compounds, leuco-auramine compounds. , Rhodamine lactam compounds, triphenylmethane compounds, spiropyran compounds and the like are known.

Aromatic compounds such as alkylated biphenyls, alkylated terphenyls, alkylated naphthalenes, and diarylalkanes are known as main solvents as the hydrophobic solvent for dissolving the color forming agent. An inexpensive hydrophobic solvent is desired. It is also known to use paraffin oil, naphthenic oil, or the like mixed with these main solvents in order to reduce the price.

Further, from the environmental point of view, it is desired to use an aliphatic or alicyclic hydrophobic solvent which is easily decomposed by microorganisms, instead of an aromatic solvent having low biodegradability.

Japanese Patent Application Laid-Open No. 2-47084 discloses that a temperature of 40 ° C.
The alicyclic hydrocarbon having a viscosity of less than 3 cSt and a boiling point of 150 ° C. or higher at room temperature (hereinafter referred to as naphthenic oil) is 5 to 50% by volume, and a boiling point at normal pressure of 260 ° C. or higher is 40%. Aromatic hydrocarbon having at least two non-condensed or condensed aromatic rings having a viscosity at 3 ° C. of 3 cSt or more and / or a viscosity at 40 ° C. of 3
Although a pressure-sensitive copying material using 50 to 95% by volume of a chlorinated paraffin oil of cSt or more has been disclosed, there are various problems in industrially using this naphthenic oil, and in practice, aliphatic hydrocarbons are used. In fact, paraffin oil is mixed with an aromatic main solvent and used.

What has been considered a problem with conventional naphthenic oils is that low viscosity naphthenic oils of 3 cSt or less have low flash points,
There is a danger of fire when used industrially for microcapsule production, and due to its low density, if the microcapsules are stored for a long time, the microcapsules float on the liquid surface and solidify, forming a film. That was the tendency. In addition, some of the naphthenic oils used as lubricating oils were suspected of being carcinogenic, and were not used.

However, when comparing paraffin oil and naphthenic oil, naphthenic oil is superior in terms of dissolution stability of the color former, and is available at low cost. Therefore, it is desirable that this naphthenic oil can be effectively used. I was

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an inexpensive carbonless pressure-sensitive copying paper which is excellent in safety, in terms of the production process, use and environment of the carbonless pressure-sensitive copying paper. To provide.

[0012]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above, and as a result, the use of a hydrophobic solvent having the following characteristics in a microcapsule has solved the above problems. Copy paper was obtained.

That is, in a carbonless pressure-sensitive copying paper provided with a coating layer containing a microcapsule containing an electron-donating color former and a hydrophobic solvent on a support, the hydrophobic solvent is heated to 40 ° C. A highly refined naphthenic base oil having a kinematic viscosity of 30 mm ² / sec or less, a flash point of 120 ° C. or more and an aniline point of 75 ° C. or less, and more preferably a density of 0 ° C. at 15 ° C. .880 g / cm
^The use of a highly refined naphthenic base oil of ³ or more.

Further, as a hydrophobic solvent other than a naphthene-based highly refined base oil, the kinematic viscosity at 40 ° C. is 10 mm ² /
The above problem could be solved by using an aromatic hydrocarbon oil having a flash point of 120 ° C. or higher and a non-condensed or condensed type aromatic ring at a temperature of 120 ° C. or less.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The carbonless pressure-sensitive copying paper of the present invention will be described in detail below.

The highly purified naphthenic base oil used in the present invention is a highly purified naphthenic base oil obtained by hydrorefining, solvent refining, etc., and is a polycyclic aromatic hydrocarbon which has been pointed out as a carcinogen. DMS based on the IP346 method used in the lubricating oil field
A base oil having an O extract amount of less than 3%.

In the present invention, the naphthenic highly refined base oil of 40
The reason why the kinematic viscosity at 30 ° C. is 30 mm ² / sec or less is due to consideration of coloring properties. If the kinematic viscosity is higher than this, the hydrophobic solvent will not easily flow out when the microcapsules are broken. As a result, the color developability becomes insufficient. In this regard, the kinematic viscosity is preferably smaller, but a solvent having a lower kinematic viscosity is a solvent having a lower molecular weight and a lower flash point. The temperature when dissolving the color former with the hydrophobic solvent is about 100 ° C. under normal pressure, and there is a risk of a flash explosion if the flash point of the hydrophobic solvent is lower than the temperature at the time of dissolving the color former. Therefore, various restrictions are imposed on industrial use.
Therefore, as a highly refined naphthenic base oil, the flash point is 1
It is preferable to use a solvent having a temperature of 20 ° C. or higher for safety.

From the viewpoint of the ability of the hydrophobic solvent to dissolve the color former, it is preferable that the hydrophobic solvent has aromaticity. Since naphthene solvents have an alicyclic structure, they have better dissolving ability than paraffin solvents, but since the dissolving ability decreases as the molecular weight increases, the aniline point is 75 ° C or less from the viewpoint of dissolving ability. It is preferred to use a highly refined naphthenic base oil.

Further, the naphthene-based highly refined base oil at 15 ° C.
Is preferably 0.880 g / cm ³ or more. When using a solvent with a smaller density than this, if the microcapsules are stored for a long time as an aqueous dispersion,
Microcapsules tend to float and solidify on the water surface, forming a film. In particular, this is likely to occur when the particle diameter of the microcapsules is increased in order to make the color development advantageous, which causes a problem in terms of long-term storage stability.

In order to obtain a great economic effect by using an inexpensive hydrophobic solvent and to improve environmental safety by using a hydrophobic solvent having good biodegradability, naphthene is used as a hydrophobic solvent. It is desirable to use a highly refined base oil at the highest possible ratio, but the dissolution stability may be insufficient depending on the type of color former, in which case, by using an aromatic hydrocarbon oil together Thus, microcapsules can be stably manufactured. The ratio of the highly purified naphthenic base oil in the hydrophobic solvent varies depending on the type of the color former, the concentration at which the color former is dissolved, and the like, but is preferably about 10 to 50% by weight.

Non-condensed or condensed aromatic hydrocarbon oils having at least two aromatic rings used as hydrophobic solvents other than naphthene-based highly refined base oils include phenylxylylethane, phenylethylphenylethane, and the like. Examples thereof include diarylalkanes such as phenylcumylethane and phenyl sec-butylphenylmethane, alkylnaphthalenes such as diisopropylnaphthalene, alkylbiphenyls such as sec-butylbiphenyl and isopropylbiphenyl, and partially hydrogenated terphenyl.

The method for producing microcapsules in the present invention is not particularly limited, and known coacervation methods, interfacial polymerization methods, in-situ polymerization methods and the like can be used. From the viewpoint of production cost, microcapsule resistance, etc., interfacial polymerization method,
An in situ polymerization method or the like is particularly preferred.

As the color former used in the present invention, compounds known for conventional carbonless pressure-sensitive copying paper can be used, and typical examples thereof include triphenylmethanephthalide, fluoran, phenothiazine, and the like. Indolyl phthalide, indolyl azaphthalide, leuco auramine, spiropyran, rhodamine lactam,
Triphenylmethane compounds and the like can be mentioned, and as the blue color forming agent, indolyl phthalide compounds and indolyl azaphthalide compounds are particularly preferable from the viewpoint of solubility stability in a solvent.

As the black color-forming agent, a fluoran compound is preferable, and in particular, 3-dimethylamino-7-
(M-trifluoromethylanilino) fluoran, 3-
Fluorane compounds having a trifluoromethylanilino group, such as diethylamino-7- (m-trifluoromethylanilino) fluoran, are preferred from the viewpoint of solubility stability in a solvent.

When a hydrophobic solution in which a color former is dissolved is microencapsulated, an ultraviolet absorber, a light stabilizer, an antioxidant and the like can be dissolved in a hydrophobic solvent and used. The substance is not particularly limited as long as it is a substance used for carbonless pressure-sensitive copying paper.

The size (volume average diameter) of the microcapsules enclosing the color former is preferably in the range of 1 to 20 μm, and particularly preferably in the range of 3 to 10 μm. The coating amount of the coloring agent slightly varies depending on the type of the coloring agent to be selected, and is not particularly limited.
000 mg / m ² , particularly preferably 20-200 mg / m ²
m ² .

An aqueous coating solution is usually used for applying a coating layer containing microcapsules. The color former-containing microcapsule dispersion obtained by the above method, a latex-based binder, if necessary, a water-soluble binder,
Capsule protective agent (stilt), white pigment, surfactant,
Various materials known in the art such as an antifoaming agent, a thickener, a preservative, and a coloring agent are added and adjusted to obtain a coating liquid. The content ratio of the microcapsules during coating is usually adjusted in the range of 5 to 80 parts by weight based on 100 parts by weight (solid part) of the coating liquid.

Specific examples of the latex-based binder include styrene-butadiene-based copolymer latex, acrylonitrile-butadiene-based copolymer latex, vinyl acetate-based latex, and acrylic latex, and alkali-thickened latexes thereof. No. Examples of the water-soluble binder include gelatin, albumin, casein, starch, pregelatinized starch, oxidized starch, etherified starch, esterified starch, sodium alginate, arabia gum, carboxymethyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, and polyacrylamide. And natural or synthetic polymer compounds such as methylcellulose. These can be mixed and used. Usually, the amount of these used is preferably in the range of 5 to 100 solid parts by weight based on 100 parts by dry weight of microcapsules. Particularly preferably, it is in the range of 5 to 50 solid parts by weight.

As the capsule protecting agent (stilt), known ones such as wheat starch granules, corn starch granules, pea starch granules, various plastic pigments and pulp powders are preferable. -10
A range of 0 μm is preferred. Particularly preferably, 5 to 30 μm
The range of m is preferred. When a white pigment is added to the microcapsule coating liquid, for example, calcium carbonate, aluminum hydroxide, zinc oxide, titanium oxide, kaolin,
Talc or the like can be used.

As a coating method, coating and drying are performed using a general coating machine (coater). As a specific coating machine,
Examples include an air knife coater, a blade coater, a rod coater, a bar coater, a roll coater, a size press coater, and a curtain coater.

Further, as a color developer for coloring the color former used in the present invention, those which are conventionally known for carbonless pressure-sensitive copying paper can be used. Organic developers such as inorganic solid acids such as activated clay, novolak-type phenol resins, polyvalent metal salts thereof, salicylic acid derivatives and polyvalent metal salts thereof can be mentioned.

Examples of the salicylic acid derivatives include 3,5-di (α-methylbenzyl) salicylic acid, 3- (α-methylbenzyl) -5- (α, α'-dimethylbenzyl) salicylic acid, and 3,5-di-tert. -Butylsalicylic acid, 3,5
-Di-tert-octylsalicylic acid, 3,5-di (α, α
'-Dimethylbenzyl) salicylic acid, styrenated salicylic acid and the like can be mentioned as typical examples.

[0033]

EXAMPLES Next, the features of the present invention will be described in detail with reference to examples and comparative examples. However, the present invention is not limited to the examples, and the substances used, the manufacturing conditions and the like are not limited to the examples. Is not limited to the description. In Examples and Comparative Examples, it is indicated by dry solid parts by weight unless otherwise specified.

The properties of the naphthenic oil, paraffin oil and aromatic hydrocarbon oil used in the examples and comparative examples are shown in Table 1.
It is as follows. The main component of the aromatic A in the aromatic hydrocarbon oil is phenylxylylethane, and the aromatic B is di-sec-
Butyl biphenyl.

[0035]

[Table 1]

Example 1 <Preparation of microcapsule solution containing color former> As a color former, 3,3-bis- (p-dimethylaminophenyl)-was used.
A hydrophobic solution was prepared by dissolving 4 parts of 6-dimethylaminophthalide in a mixed solvent of 64 parts of aromatic A and 32 parts of naphthenic oil A. Styrene-maleic anhydride copolymer 5%
180 parts of the above-mentioned hydrophobic solution was gradually added to 220 parts of the aqueous solution under vigorous stirring, and the mixture was stirred until the 50% volume average diameter in the Coulter counter became 6 μm to obtain an emulsion. Separately, an aqueous melamine-formaldehyde precondensate solution obtained by heating and dissolving 11 parts of melamine, 21 parts of a 37% aqueous formaldehyde solution and 28 parts of water is added to the emulsion, and the mixture is stirred at a temperature of 70 ° C. for 2 hours. A microcapsule solution containing a color former was obtained.

Example 2 <Preparation of a microcapsule solution containing a coloring agent>
A color former-encapsulated microcapsule solution was obtained in the same manner as in Example 1, except that 6 parts and 10 parts of naphthenic oil A were used.

Example 3 <Preparation of a microcapsule solution containing a color former> 4 parts of 3,3-bis- (p-dimethylaminophenyl) -6-dimethylaminophthalide was added to 3,3-bis- (p-dimethyl 2 parts of aminophenyl) -6-dimethylaminophthalide and 3- (4-diethylamino-2-ethoxyphenyl)-
Color development was carried out in the same manner as in Example 1 except that 2 parts of 3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide was replaced with 50 parts of aromatic A and 46 parts of naphthenic oil A. An agent-encapsulated microcapsule solution was obtained.

Example 4 <Preparation of microcapsule solution containing color former> Naphthenic oil A
In the same manner as in Example 1 except that
A microcapsule solution containing a color former was obtained.

Example 5 <Preparation of microcapsule solution containing color former> Naphthenic oil A
In the same manner as in Example 1 except that
A microcapsule solution containing a color former was obtained.

Example 6 <Preparation of microcapsule solution containing a color former> A microcapsule solution containing a color former was obtained in the same manner as in Example 1 except that aromatic A was replaced with aromatic B.

Comparative Example 1 <Preparation of microcapsule solution containing color former> Naphthenic oil A
Was replaced with naphthenic oil D in the same manner as in Example 1,
A microcapsule solution containing a color former was obtained.

Comparative Example 2 <Preparation of microcapsule solution containing color former> Naphthenic oil A
Was replaced with naphthenic oil E in the same manner as in Example 1,
A microcapsule solution containing a color former was obtained.

Comparative Example 3 <Preparation of microcapsule solution containing color former> Naphthenic oil A
Was replaced with n-paraffin in the same manner as in Example 1 to obtain a color former-containing microcapsule solution.

Table 2 shows the danger of flammable explosion during the preparation of the microcapsules of Examples 1 to 6 and Comparative Examples 1 to 3 determined from the flash point. ○ is less dangerous, △ is more dangerous,
X is a three-stage judgment of danger. The dissolution stability of the color former solution was evaluated on a 5-point scale based on the state of crystal deposition of the color former when the solution in which the color former was dissolved was allowed to stand at room temperature for one day. The higher the rating, the better the dissolution stability, indicating that a rating of 3 or higher is practical. Furthermore, when the obtained microcapsules were allowed to stand at room temperature for one month,
The state of dry film formation on the liquid surface was determined and is shown in Table 2. ○
Indicates that no film was formed, and X indicates that a very hard film was formed, and the liquid did not return to the original liquid state with weak stirring.

<Method of preparing colorant coating liquid and upper paper> 70 parts of wheat starch and styrene-butadiene copolymer were added to 100 parts of the colorant-containing microcapsule solution obtained in Examples 1 to 6 and Comparative Examples 1 to 3. Latex (Nippon Synthetic Rubber) 35
To prepare a colorant coating solution having a basis weight of 50 g / m ^2.
Coated on a high quality paper such that the coating amount is 5 g / m ² ,
Paper on carbonless pressure-sensitive copying paper of Examples 1 to 6 and Comparative Examples 1 to 3 was obtained.

The microcapsule coated surface of the upper paper obtained in each of Examples and Comparative Examples was superimposed on a commercially available carbonless pressure-sensitive copying paper under paper (under Mitsubishi NCR paper N40: Mitsubishi Paper), and printing was performed with a typewriter. The color density immediately after and the color density one day later were observed, and the initial color developability and the color developability over time were determined. The results are shown in Table 2. The evaluation is a five-point scale, the larger the score, the better, and a score of 3 or more is practical.

[0048]

[Table 2]

Table 2 shows the following. That is, by using a naphthene-based highly refined base oil having an aniline point of 75 ° C. or lower, the dissolution stability of the color former is maintained, and by setting the density to 0.880 g / cm ³ or more, long-term storage stability is improved. Microcapsules are obtained. Also, 40
By setting the kinematic viscosity at 30 ° C. to 30 mm ² / sec or less, it is possible to obtain a carbon-free pressure-sensitive copying paper having good temporal coloring without impairing the initial coloring. By setting the kinematic viscosity at 40 ° C. of the aromatic hydrocarbon oil to 10 mm ² / sec or less, it was possible to obtain a carbonless copying paper having good initial color development.

[0050]

As described above, in a carbonless pressure-sensitive copying paper provided with a coating layer containing a microcapsule containing an electron-donating color former and a hydrophobic solvent on a support, the temperature is reduced to 40 ° C. as a hydrophobic solvent. By using a highly refined naphthenic base oil having a kinematic viscosity of 30 mm ² / sec or less, a flash point of 120 ° C. or more, and an aniline point of 75 ° C. or less, the density at 15 ° C. is more preferably 0. By using a naphthene-based highly refined base oil of 880 g / cm ³ or more, as a hydrophobic solvent other than the naphthene-based highly refined base oil, the kinematic viscosity at 40 ° C. is 10 mm ² / sec or less, and the flash point is At 120 ° C. or higher and using an aromatic hydrocarbon oil having at least two non-condensed or condensed aromatic rings, allows the use of a hydrophobic solvent in the microcapsule production stage. Less risk of explosion, good dissolution stability of the color former, long-term storage stability of the resulting microcapsules is good. Further, it is possible to obtain a carbon-free pressure-sensitive copying paper having good color development over time without impairing the initial color development.

Claims (3)

[Claims] 1. A carbon-free pressure-sensitive copying paper provided with a coating layer containing a microcapsule containing an electron-donating color former and a hydrophobic solvent on a support at 40 ° C. as a hydrophobic solvent. A carbonless pressure-sensitive copying paper characterized by using a highly refined naphthenic base oil having a kinematic viscosity of 30 mm ² / sec or less, a flash point of 120 ° C. or more and an aniline point of 75 ° C. or less. 2. The carbonless pressure-sensitive copying paper according to claim 1, wherein the density of the highly refined naphthenic base oil at 15 ° C. is 0.880 g / cm ³ or more. 3. A high-refined naphthene-based base oil together with 40
Kinematic viscosity at 10 ° C. is 10 mm ² / sec or less, flash point is 12
The carbon-free pressure-sensitive copying paper according to claim 1, wherein an aromatic hydrocarbon oil having at least two non-condensed or condensed aromatic rings at 0 ° C or higher is used.