JPS6029637B2 - record sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a microphone comprising fine particles of a hydrophobic substance containing an electron-donating organic coloring agent.

The present invention relates to a recording sheet coated with a capsule coating liquid, and particularly to a capsule-coated recording sheet that has improved color staining and scumming during printing. Conventionally, the coacervation method described in US Pat. No. 2,800,457 and US Pat. No. 2,800,458 is well known as a method for manufacturing microcapsules containing fine particles of a hydrophobic substance. Coacervation is generally a general term for the phenomenon of phase separation when organic substances, salts, colloidal substances of opposite charge, etc. are added to a hydrophilic colloidal substance water bath foil. A detailed cuff cell manufacturing process is described. [1} A process of emulsifying an oily substance in an aqueous solution of an ionizable hydrophilic colloid substance - emulsification process.

'2} After mixing an aqueous solution of a hydrophilic colloid substance that can be ionized and has an opposite charge to the above-mentioned hydrophilic colloid substance into the emulsion of m, coacervation is caused by operations such as pH adjustment and dilution, and oil droplets are formed. Step of obtaining coacervate fixed around - coacervation step, 3
A step of cooling the coacervate to gel it - a gelling step; 4. A step of curing the coacervate by adjusting the pH and adding a hardening agent - a curing step. For example, in the case of manufacturing microcapsules for pressure-sensitive copying paper, the following steps are carried out: A fifth step is added.

'5) Finishing process - The process of adding auxiliary agents such as pulp powder, stilt, casein, starch, and hydroxyethyl cellulose to make it suitable for coating, etc., and the purpose of adding color to the coating liquid and improving whiteness. This includes the step of adding fluorescent dyes, organic pigments, dyes such as methyl violet, etc.

Generally, in order to preserve the capsule coating liquid for a long period of time, a bactericide, a preservative, and an antimicrobial agent are added before and after the preparation of the paint is completed. Examples of these include sorbic acid, potassium sorbate, bentachlorphenol, chloramine T, salicylic acid, methylnaphthoquinone, butyl paraoxybenzoate, formaldehyde, glutaraldehyde, and the like. In addition, for the same purpose, it is also effective to maintain the coating liquid at 20 oo or less before and after the coating is certified. The microcapsules obtained as described above are applied to, for example, well-known pressure-sensitive copying paper that utilizes a coloring reaction between an electron-donating organic coloring agent and an electron-accepting coloring agent, to print ruled lines, background patterns, etc. When applying this method, the following drawbacks are recognized and improvements are desired. That is,
In recent years, wind-finished offset printing, especially wet offset printing, has been widely adopted for business form printing on pressure-sensitive copying paper. When printing on so-called middle paper, which is coated with a microcapsule coating liquid and the other side coated with a coating liquid containing an electron-accepting coloring agent, the capsules are destroyed by the printing pressure, causing the oil and coloring in the capsules to be destroyed. Perhaps due to the transfer of the agent, colored stains occur on the entire surface of the rolled and finished inner paper coated with the coloring agent. In addition, when performing wet offset printing on the surface coated with microcapsules, the non-EO printing area may be prone to ink stains, probably because proteins, surfactants, adhesives, and other auxiliary agents in the coating layer affect the plunket surface and plate surface. There is a drawback that so-called background staining occurs. By adding adhesives such as polypinyl alcohol, casein, starch, sodium alginate, hydroxymethylcellulose, hydroxymethylcellulose, and hydroxyethylcellulose to the capsule dispersion after hardening treatment, the pressure resistance of the capsules can be improved. However, it does not bring about any essential improvement for the purpose of preventing color development smudges and background smudges during printing. The main object of the present invention is to provide a capsule-coated recording sheet with improved color development stains and background stains during printing.

Such an object of the present invention is to add {a) a curing agent and [b} at least one or more olefin monomers to a dispersion of microcapsules containing fine particles of a hydrophobic substance and having a gelled hydrophilic colloid material as a wall material. This is achieved by applying a coating liquid containing an alkali salt of a copolymer whose main components are carboxylic acid and at least one acrylic or methacrylic monomer to the surface of the supporting substrate.

The microcapsules of the present invention are disclosed in, for example, US Pat.
No. 457, No. 28004, No. Re 2489y, Special Publication Showa No. 1881, Special Publication No. 2981, Special Publication No. 48-43547, No. 140376 of Sho 50-1,
It is prepared by the usual coacervation method described in Tokukan Kai No. 51-11850, Machigao Kai No. 52-9022, etc.

Examples of hydrophilic colloid substances commonly used in the coacervation method include gelatin, casein, gum arabic, sodium alginate, carboxymethyl cellulose, polypinyl alcohol, and methyl vinyl ether/maleic anhydride copolymer. Natural and synthetic substances are well known, and such natural and synthetic hydrophilic colloid substances are appropriately selected and used in the present invention, but it is more preferable to use at least gelatin because it provides the most stable capsule. Hydrophobic substances contained in the capsule include various oily substances such as natural mineral oil, animal oil, vegetable oil, and synthetic oil. Examples include petroleum, kerosene, paraffin oil, fish oil, soybean oil, castor oil, linseed oil, and biphenyl Examples include derivatives, naphthalene derivatives, cholesterin derivative substances, and tributyl phosphate.

In the case of capsules utilized in pressure-sensitive copying paper, these oils include crystal violet lactone, malachite green lactone, penzoyl leucomethylene blue,
One or more electron-donating organic coloring agents such as rhodamine-B-lactam and fluoran are dissolved and incorporated into the capsule. There are two types of pressure-sensitive copying paper: one in which the capsules and the electron-accepting coloring agent are coated on different sides of the sheet, and the other in the form of a single coloring paper in which the capsules and the electron-accepting coloring agent are coated on the same side of the sheet. Electron-accepting coloring agents used in these pressure-sensitive copying papers include inorganic acidic substances such as activated clay, acid clay, attapulgite, silica, and aluminum silicate, as well as phenolic compounds, phenolic polymers, aromatic carboxylic acids, and Organic acidic substances such as polyvalent metal salts thereof are known (for example, Japanese Patent Publication No. 49-10856, Japanese Patent Publication No. 51-1982).
25174, etc.).

In the present invention, a coacervate film of a hydrophilic colloid substance is formed around fine particles of a hydrophobic substance, and after this coacervate film is cooled and gelled, a curing agent and an alkali salt of a specific copolymer are added. Although it is added,
The curing agent and the alkali salt of the copolymer may be added to the capsule dispersion at the same time, or one may be added in advance and then the other.

In any case, it is necessary to contain the curing agent and the alkali salt of the copolymer in the cooled and gelled capsule dispersion, and in the conventional curing process, free curing agent is still present. Of course, adding an alkali salt of the copolymer is also an effective method in the present invention.
Examples of curing agents effective in the present invention include formaldehyde, glyoxal, glutanolaldehyde, and mukoku. acid, glyceraldehyde, succinic dialdehyde, acrolein, dialdehyde starch, 2-methylglutaraldehyde, crotonaldehyde, tiglinaldehyde, citronellal, cinnamaldehyde, urea formaldehyde resin, melamine formaldehyde resin, polyamide formaldehyde resin, etc. Aldehydes, diketones such as benzoquinone, cyclohexane-1,2-dione, cyclobentane-1,2-dione, diacetyl, 2,3-bentanedione, 2,5-hexanedione, 2,5-hexanedione, ethylene glycol diglycidyl ether , polyethylene glycol glycidyl ether, polyamide epichlorohydrin resin, epoxides such as triglycidyl isocyanurate, 7,8-diphenylbicyclo(2,2,2)-7-octene-2,3,
5,6-tetracarboxylic dianhydride,
Examples include acid anhydrides and acid chlorides such as terephthaloyl chloride and 4,4'-diphenylmethane disulfonyl chloride. In the present invention, one or more types of such curing agents are appropriately selected and used, and aldehydes are more preferably used from the viewpoint of stability of the capsule dispersion. The amount of the curing agent added is not necessarily limited, but is usually adjusted within the range of 1 to 5 parts by weight, more preferably 3 to 3 parts by weight, based on 10 parts by weight of the hydrophilic colloid material.
The alkali salt of the specific copolymer used in the present invention is a copolymer obtained by copolymerizing at least one olefin monocarboxylic acid and at least one acrylic or methacrylic monomer as main monomer components. It is an alkaline salt of

Here, olefin monocarboxylic acid is a monocarboxylic acid having one double bond, such as acrylic acid, methacrylic acid, crotonic acid, incrotonic acid, pinylacetic acid, allyl acetic acid, pyroterebic acid, 8-penzoyl Examples include acrylic acid, and acrylic acid, methacrylic acid, and crotonic acid are particularly preferably used. Acrylic or methacrylic monomers are monomers having acrylo or methacrylo groups other than olefin/carboxylic acids, such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, inbutyl acrylate, octyl acrylate, decyl acrylate, etc. Acrylic acid alkyl ester, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, octyl methacrylate, methacrylic acid alkyl ester such as decyl methacrylate, acrylic acid amide or methacrylic acid amide, N-methylolated acrylamide or N-methylol methacrylamide,
Acri. Examples include nitrile or methacrylonitrile, vinyl phenyl ketone, polyethylene glycol acrylate or polyethylene glycol methacrylate, 6-hydroxypropyl methacrylate, glycidyl methacrylate, etc.; Alkyllester, Acry. Nitrile or methacrylonitrile, acrylic acid amide or methacrylic acid amide,
Vinyl phenyl ketone is more preferably used because it has an excellent ability to retain the oil agent in the capsule, especially in the capsule, and is effective in preventing color development and staining on the entire surface during offset printing. In the copolymer used in the present invention, if the content of olefin monocarboxylic acid is less than 8 mol%, sufficient water bathability cannot be obtained, and if it exceeds 90 mol%, the copolymer's hygroscopic resolubility increases. Therefore, it is desirable that the molar ratio of the olefin monocarboxylic acid is 8 to 90 mol% of the polymer, and the molar ratio of the acrylic or methacrylic monomer is 92 to io mol%. In addition, if necessary, it is also possible to copolymerize at least one vinyl monomer selected from vinyl acetate, ethylene, vinyl chloride, and vinylidene chloride in an amount of 50 mol % or less. The copolymer of the present invention is prepared by mixing the above-mentioned olefin monocarboxylic acid, acrylic or methacrylic monomer, and other vinyl monomer with water, methanol, ethanol, or isoph.

A polymerization initiator such as potassium persulfate, ammonium persulfate, hydrogen peroxide, benzyl peroxide, asobisisobutyronitrile, etc. in a single or mixed solvent such as lopanol, butanol, ethyl acetate, methyl ethyl ketone, toluene, xylene, etc. Copolymerization is carried out by a well-known method using various polymerization aids such as secondary alcohols, polymerization regulators such as mercaptosuccinic acid, and emulsifiers such as sodium lauryl sulfate. The obtained copolymer is further neutralized with amines such as ammonia, ethylamine, propylamine, ethanolamine, and propanolamine, and one or more alkalis such as sodium hydroxide and potassium hydroxide to a concentration of 5 to 5.
5% by weight, pH 3-12, Daisen 5-10000 ps
Used as a water-repellent resin.

When the carboxyl group of the olefin monocarboxylic acid in the polymer is substituted with ammonia and/or amine salt, the strength of the capsule wall and the coated surface of the capsule is increased in the presence of a hardening agent, making it easier to use during offset printing. It is particularly preferred because it has an excellent effect of preventing color development stains on the entire surface.

Furthermore, when 1 to 95% of the carboxyl groups are replaced with sodium or potassium salts, the compatibility with the capsule dispersion is improved and more excellent effects are exhibited. However, if excessively replaced with sodium or potassium salt, there is a risk of background smearing during offset printing, so it is more preferable to replace 5 to 50% of the carboxyl groups with sodium or potassium salt. In the present invention, all of the carboxyl groups in the copolymer do not necessarily need to be neutralized with an alkali, and an alkali salt of the copolymer containing free carboxylic acid is also effective, but it is necessary to obtain sufficient water solubility. Therefore, it is necessary to neutralize the copolymer so that at least 8 mol % or more of the alkali salt of carboxylic acid is present in the copolymer.

Although the amount of the alkali salt added to the copolymer is not necessarily limited, it is usually 10% of the hydrophobic substance in the microcapsules.
0.5 to 5 parts by weight based on broad weight parts, preferably 1 to 3 parts by weight
It is added in an amount of 0 parts by weight.

The capsule dispersion to which a curing agent and an alkali salt of a specific copolymer have been added can be prepared by adding starch, casein, polyvinyl, or A microcapsule solution can be prepared by adding an adhesive such as alcohol, a stilting agent such as bulb powder or raw starch powder, dyes, and other ingredients as needed. The capsule coating solution thus obtained is coated on the surface of a supporting substrate such as paper, synthetic paper, synthetic film, etc. using a conventional coating device and dried. There is no particular limitation on the amount of application, but it is usually 1 to 15 coats/dry weight.
It is preferably applied 2 to 8 days per day. The present invention will be described in detail with reference to Examples below, but it is of course not limited thereto.

Further, in each example, % and parts indicate parts by weight and weight % unless otherwise specified. Example [Production of coloring agent coated paper] 7 parts of zinc salt of 3,5-Q-methylbenzylsalicylic acid and 3 parts of styrene-Q-methylstyrene copolymer were melted in an extruder heated to 15,000 °C. The mixture was mixed, cooled to room temperature, and then ground to obtain a coloring agent.

Water containing 2 parts of this coloring agent, 25 parts of zinc oxide, 3 parts of aluminum hydroxide, 25 parts of activated shiraji, 5 parts of a 20% aqueous solution of sodium polyacrylate, and 2 parts of a 10% aqueous polyvinyl alcohol solution. The mixture was dispersed in 40 anchor portions and further dispersed using a sand grinder. To this system, 4 parts of a 20% oxidized starch aqueous solution and 3 parts of carboxy-modified styrene-butadiene latex (48% concentration) were added to obtain a coloring agent coating liquid. This coloring agent coating liquid was coated on one side of a base paper with a dry weight of 6 days after drying by using an air knife coater and then calendered to obtain a star coloring agent coated paper.

[Production of capsule dispersion A]

Three parts of acid-treated gelatin were added to 27 parts of water and allowed to stand for 1 hour, and then 20 parts of water was added and heated to 6030 °C to obtain an aqueous gelatin solution.

Separately, dissolve 3 parts of crystal violet lactone and 1 part of benzyl leucomethylene flue in 100 parts of diisopropyl naphthalene, add this to the gelatin aqueous solution, and while stirring, form oil droplets with an average grain size of 5R. It was emulsified and dispersed. Next, 10% aqueous solution of gum arabic 300%
After mixing sound B into the above emulsion and adding 20 parts of water, the pH of the system was adjusted to 4.1 with acetic acid to form a coacervate film around the oil droplets, and then the emulsion was strongly poured. After cooling the system temperature to 100C and gelling the coacervate, 5 parts of glutaraldehyde (Nagase Sangyo ■, GA-50) was added and the pH was adjusted to 9.5 with 5% NaOH aqueous solution. After the preparation, a capsule dispersion was obtained. This capsule was mostly mononuclear. [Preparation of capsule dispersion B] Equal dew point 8.0
Add 65 parts of acid-treated gelatin to 585 parts of water and add 1,000 parts of acid-treated gelatin.
After leaving it for 1 hour, it was heated to 6,000 ℃ and dissolved.

Separately, in a mixed oil of 78 parts of kerosene and 182 parts of inpropylnaphthalene, 5.0 parts of crystal violet lactone was added. Dissolve 2.6 parts of group part and penzoylleucomethylenefluor,
6000, this was added to the aqueous gelatin solution and emulsified with a homomixer to obtain oil droplets with an average particle size of 3.0 mm.

Add 130 g of 5yC warm water to this emulsion, and further add carboxymethyl cellulose (average degree of polymerization 160, degree of substitution 0).
．． 6) 5% aqueous solution 13 anchors (weight ratio of gelatin: 10%)
) was added. The pH of the system was adjusted to 5.4 by adding a 10% aqueous solution of caustic soda while stirring continuously. After lowering the liquid temperature to 10°C, the particle size distribution of the capsules was measured using a Coulter counter. The capsules were binuclear capsules with an average particle size of 8.2r. Then set the liquid temperature to 1
The pH of the system was adjusted to 6.0 by adding 13 parts of a 50% aqueous solution of glutaraldehyde and further adding a 10% aqueous solution of caustic soda to obtain a capsule dispersion.

[Preparation of capsule dispersion C]

100 parts of alkyl biphenyl dissolved in 3 parts of crystal violet lactone was emulsified in an aqueous solution (5000) of 25 parts of acid-treated gelatin with an isoelectric point of 8.5 and 25 parts of water to obtain an emulsion with an average particle size of 3A. .

To this emulsion was added and mixed an aqueous solution consisting of 25 parts of gum arabic and 25 parts of water, and then 1770 parts of water and 5% of polyvinyl methyl ether/maleic anhydride copolymer.
Add and mix 14 parts of the aqueous solution and incubate while maintaining the pH at 4500, and adjust the pH of the system to 4.0 while gradually adding 10% acetic acid aqueous solution.
Adjusted to 2. Next, the temperature of the system is cooled to 1000 and 10%
25 parts of formaldehyde aqueous solution was added, and the pH of the system was further adjusted.
was adjusted to 10.0 with a 5% caustic soda aqueous solution to obtain a microcapsule dispersion.

This capsule dispersion was a dispersion of Enoki kernel capsules with an average particle size of 9 mm.

[Manufacture of capsule coated paper]

To each of the capsule dispersions obtained as described above, an alkali salt of the copolymer and various auxiliary agents as shown in the table were added to obtain 16 types of capsule coating liquids.

In Example 5, the alkali salt of the copolymer was added to the capsule dispersion at the same time as the curing agent glutaraldehyde.

In Symmetric Example 1, the dispersibility of the copolymer in the capsule dispersion liquid was extremely poor, and a capsule coating could not be obtained. Furthermore, in Symmetric Example 5, no alkali salt of the copolymer was added. Furthermore,
The capsule dispersion of Symmetric Example 6 was prepared by adding glutaraldehyde and plating in a caustic sorter during the preparation of capsule dispersion B.
Dispersion B', which was obtained in the same manner as Dispersion B except that H adjustment was not performed, was used.

The obtained 1-ball weight capsule paint was applied to the non-applied surface of the star coloring agent sheet obtained above using an air knife coater so that the dry weight was 5 days/day. Obtained. [Evaluation Test] Evaluation tests were conducted on each of the obtained inner sheets according to the following evaluation methods, and the results are also listed in the table.

1 Scratch test Business form printing machine (manufactured by Mei Seisakusho, 178 days taif.

), 1,000 ruled lines were printed on the capsule coated surface using a wet offset printing method under the following conditions, and judgment was made based on the amount of printing (skin) at which the occurrence of scumming became noticeable. Ink: New Champion Red (manufactured by Dainippon Ink - ■) Overflow water: City water Tension: 200 poly/c Printing speed: 100 skin/min. 2 Full color stain test Using a business form printing machine (manufactured by Mei Seisakusho, 17BH type), a pattern was printed using the wet offset printing method on the color agent coated surface under the following conditions, and a roll of 300 m was completed at room temperature and pressure for 48 hours. After aging, the state of dirt on the surface coated with the star coloring agent at a position approximately 100 mm from the core was visually determined.

Judgment criteria are: ◎ No stains observed at all ○ Very slight stains × Colored stains occur.

×× Ink with colored stains on the entire surface: New Champion Red (manufactured by Dainippon Ink ■) Dampening water: 3% aqueous solution of etch liquid EU-1 for Oreban (manufactured by Fuji Photo Film ■) Tension: 400 evening /Printing speed: 100/min. In the table, the neutralization ratio of carboxylic acid is expressed as the ratio of carboxyl groups neutralized with NaOH, KOH, N-ratio OH, and amine (propanolamine) to the total rpoxyl groups in the copolymer.

Claims (1)

[Scope of Claims] 1. Emulsifying a hydrophobic substance containing an electron-donating organic coloring agent with a hydrophilic colloid substance as a core substance to form a coacervate film - microcapsule dispersion after cooling and gelling. (a) a curing agent for curing the coacervate film of the hydrophilic colloid material; and (b) at least one
one or more olefin monocarboxylic acids and at least one
1 to 60% of the alkali salt of a copolymer whose main component is acrylic or methacrylic monomer (excluding olefin monocarboxylic acid) per 100% of the hydrophobic substance.
A recording sheet made by applying a coating liquid containing a weight part to a supporting substrate surface. 2. The recording sheet according to claim 1, wherein gelatin is used as the hydrophilic colloid substance. 3. The recording sheet according to claim 1 or 2, wherein the olefin monocarboxylic acid is at least one selected from acrylic acid, methacrylic acid, and crotonic acid. 4 At least one type selected from acrylic or methacrylic acid alkyl esters or methacrylic acid alkyl esters, acrylonitrile or methacrylonitrile, acrylic acid amide or methacrylic acid amide, and vinyl phenyl ketone, in which the acrylic or methacrylic monomer has an alkyl group having 8 or less carbon atoms. A recording sheet according to claim 1 or 2, characterized in that: 5. The copolymer is an alkali salt of a copolymer consisting of 8 to 90 mol% of at least one olefin monocarboxylic acid and 92 to 10 mol% of at least one acrylic or methacrylic monomer. A recording sheet according to claim 1 or 2.