JPS6228000B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to pressure-sensitive copying paper, and more particularly to a method for producing pressure-sensitive copying paper coated with microcapsules.

Pressure-sensitive copying paper that utilizes a color-forming reaction between an electron-donating color former and an electron-accepting color developer is widely known.
For example, US Patent No. 2711375, US Patent No. 2712507, US Patent No.
No. 2730456, No. 2730457, No. 3617334, Special Publications
Examples of this can be found in No. 38-18317, No. 47-1178, No. 47-20972, etc.

The most typical forms of pressure-sensitive copying paper are as follows. That is, a suitable electron-donating coloring agent is dissolved in a suitable solvent, contained in microcapsules, and applied onto a sheet (this sheet is generally often referred to as a top paper). On the other hand, a suitable electron-accepting color developer is applied onto another sheet (this sheet is generally often referred to as the bottom sheet). Place the microcapsule-coated side of the top paper and the color developer-coated side of the bottom paper on a hard surface, etc., and apply pressure by applying pen pressure from the top.The microcapsules will break and contain the color developer. The solvent comes into contact with the color developer, and the color former and developer react to produce a colored image. There is also a sheet (often referred to as inner paper) in which microcapsules containing a solvent containing an electron-donating color former are coated on one side and an electron-accepting color developer is coated on the other side. Often used, this is done by placing multiple sheets facing each other in the direction of the microcapsule-coated surface of the top paper and the developer-coated surface of the middle paper, and the microcapsule-coated surface of the middle paper and the developer-coated surface of the middle paper or bottom paper. It is used to obtain colored images.

Pressure-sensitive copying paper of this type is widely used as various types of office paper, such as slips and computer paper, and is extremely useful, so various demands have been made regarding its quality. . In other words, in pressure-sensitive copying paper that utilizes the property of microcapsules being destroyed by pressure, the microcapsules may be destroyed during handling during the pressure-sensitive copying paper manufacturing process, printing process, form creation process, etc., resulting in abnormalities. Since it has the disadvantage of causing a strong color development, there has been a demand for countermeasures for this problem from an early stage. In order to overcome these drawbacks, microcapsule protective materials have traditionally been used, including fine cellulose powder (U.S. Patent No. 2711375) and starch particles (British Patent No. 1232347, Japanese Patent Publication No. 1178-1178,
−33204), glass beads (US Patent No. 2655453),
A method has been introduced in which thermally expandable polymer particles (microspheres) (Japanese Patent Application Laid-Open No. 48-32013) are mixed with microcapsules and coated on paper. It is possible to use these microcapsule protective materials as long as they have a larger particle size than microcapsules, but if the difference in specific gravity is too large or the particle size is uneven compared to microcapsules, use a coating liquid. During the process of applying the product to a sheet, the microcapsules and the protective material tend to gradually separate, making it difficult to maintain stable quality. On the other hand, some microspheres and polyolefin particles meet these requirements in terms of specific gravity and particle size, but they lack strength as a protective material and lack uniform particle size. The use of particles poses various problems, including an extremely high cost.

The inventor of the present invention has solved all of these problems regarding microcapsule application using the following method.

That is, the main point of the present invention is to first coat a sheet on which microcapsules are coated or printed with a protective material for the microcapsules, and then coat a coating liquid containing microcapsules to produce pressure-sensitive copying paper. shall be.

The electron-donating organic coloring agent that can be used in the present invention is not particularly limited as long as it develops color by reacting with a suitable electron-accepting coloring developer. ,3-
Bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (commonly called crystal violet lactone), 3,3-bis(p-dimethylaminophenyl) phthalide, 3-(p-dimethylaminophenyl) -3-(1,2-dimethylindol-3-yl)phthalide, 3-(p-
dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-phenylindol-3-yl)phthalide, 3,3- Screw (9
-ethylcarbazol-3-yl)-5-dimethylaminophthalide, etc., and dimethylmethane-based organic coloring agents such as 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halofenyl-leucoauramine, N-2,4,5-trichlorophenylleucoolamine, etc., rhodamine B-anilinolactam, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6,8-dimethylfluorane, 3-diethylamino-7-methylaminofluorane, 3,7-diethylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-chloroethylmethyl Aminofluorane, etc., thiazine-based organic coloring agents such as benzoyl leucomethylene blue, p-
Nitrobenzylleucomethylene blue, etc., spiro-based organic color formers such as 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichlorospiro-dinaphthopyran, 3-propyl-spiro dibenzopyran, etc. Many color formers are known and these may be used alone or in combination. In addition, inorganic acidic substances such as acid clay, activated clay, attapulgide, kaolin, and aluminum silicate may be used as electron-accepting color developers that react with these coloring agents to develop color, and various alkyl-substituted phenols and phenolic color developers may be used as phenolic color developers. ，
4′-(1-methylethylidene)bisphenol,
Phenolaldehyde polymer, etc., aromatic carboxylic acid color developer such as benzoic acid, chlorobenzoic acid, toluic acid, salicylic acid, 5-tert-butylsalicylic acid, 3,5-di-tert-butylsalicylic acid,
Copper, lead, magnesium, calcium, zinc, aluminum, such as the aromatic carboxylic acid color developer mentioned above as an aromatic carboxylic acid metal salt color developer such as 3,5-di-(α-methylbenzyl)salicylic acid, Metal salts such as tin and nickel are known, and these may be used alone or in combination. When these electron-donating organic color formers and electron-accepting color developers are microencapsulated, they are generally dissolved in an appropriate solvent and then encapsulated together with the solvent in microcapsules. Any solvent that dissolves the coloring agent or color developer may be used. Mineral oils include kerosene, paraffin oil, etc., animal oils include fish oil,
Lard oil, vegetable oils such as peanut oil, linseed oil, soybean oil, and castor oil; synthetic oils such as alkylnaphthalenes, diallylakanes, alkylbiphenyls, hydrogenated terphenyls, triallyldimethanes, phenylene oxides, and alkylbenzenes. , benzylnaphthalene type, diallylalkylene type, allyl indane type, dibasic fatty acid ester, etc. are known and can be used. In addition, many methods for encapsulating these are known, including the coacervation method (US Pat. No. 2,800,457,
2800458, 3041288, Special Publication No. 39-27227, No. 48-
43547, etc.), interfacial polymerization method (British patent 950443, US patent 3208951, Japanese Patent Publication No. 43-23709, No. 44-11772, etc.),
In situ method (Special Publications No. 37-12380, No. 46-30282, etc.)
Although these methods are prominent, other methods can be used as long as the microcapsules have an appropriate particle size and strength and encapsulate the above-mentioned solvent. As mentioned above, protective materials for these microcapsules include cellulose fine powder, starch particles, glass beads, microfeathers, and polymer particles such as polyolefin particles, nylon particles, etc.
Vinyl chloride particles, methyl methacrylate polymer particles, tetrafluoroethylene-hexafluoropropylene copolymer particles, etc. Mineral particles include aluminum granulated powder, zinc powder, sprayed copper-lead alloy powder, sprayed bronze powder, titanium powder, White carbon, calcium carbonate, calcium tungstate, zinc sulfide, and other materials having a particle size larger than that of the microcapsules can be used, but relatively spherical particles and colorless particles are preferable.

Furthermore, as a method of separately applying the microcapsules and the microcapsule protective material as in the present invention, there is a method of applying the microcapsules first and then applying the capsule protective agent as in Japanese Patent Application Laid-Open No. 15709-1982. In addition to having more smeared prints than the method of the present invention, another feature of the present invention is that when printing partially with a coating liquid containing microcapsules, the method of the present invention provides a relatively uniform thickness. Compared to the method of partially printing by mixing microcapsules and microcapsule protectant, or the method of partially printing microcapsules and then applying capsule protectant, only the printed part of the microcapsules becomes thicker. The profile of the paper deteriorates, abnormal color development tends to occur, and the paper is not easy to handle.
The reason why the paper on which the microcapsule liquid is partially printed by the method of the present invention becomes relatively uniform is that even if the capsules are partially printed, it penetrates between the capsule protectants previously applied. It will be done.

These protective agents can be applied by adding a necessary amount of an appropriate adhesive to the protective agent, and if necessary, adding other additives, and then applying the protective agent to the paper using an appropriate method. Generally, blade coating, air knife coating, etc. are often used for productivity and other reasons.
Conventionally known coating methods such as bar coating, rod coating, roller coating, fountain coating, gravure coating, spray coating, dip coating, and extrusion coating can be used. Further, as a method for coating the microcapsules, it is sufficient to add a required amount of an appropriate adhesive to the microcapsules, and if necessary, add other additives, and then coat the paper onto the paper using an appropriate method. As with capsule protectants, blade coating and air knife coating are often used, but conventionally known coating methods such as bar coating, rod coating, roller coating, fountain coating, gravure coating, spray coating, dip coating, extrusion coating, etc. is available. Furthermore, it is also possible to perform partial printing using an appropriate printing method or coating method.

When manufacturing pressure-sensitive copying paper using the method described above,
The sheet can be used as a top paper, or it can be used as a self-coloring pressure-sensitive copying paper that has an electron-donating organic color former, an electron-accepting color developer, and an organic solvent all on the same surface. Although it is not the main purpose, it can also be used as a base paper. When the microcapsules used in the present invention contain almost only an organic solvent, an electron-donating organic coloring agent and an electron-accepting color developer are applied to one side of the bottom paper or middle paper, and the top paper coated with the microcapsules is applied. Alternatively, use inner paper to stack the microcapsule coated side and the color former and color developer coated side facing each other, or apply the organic solvent-containing microcapsule color former and color developer on the same side for self-coloring. There is a method of using it as pressure-sensitive copy paper. When using these methods, at least one of the color former and the color developer may be contained in the sheet to which the microcapsule protectant is applied,
It may also be applied together with a microcapsule protectant. In this type of color development, it takes a long time to reach the maximum color density, and the maximum color density tends to be slightly low. In addition, when the microcapsules used in the present invention contain only an organic solvent in which an electron-donating organic coloring agent is dissolved, an electron-accepting color developer is coated on one side of the bottom paper or inner paper to form the microcapsules. Use the coated top paper or inner paper to stack the microcapsule-coated side and developer-coated side facing each other, or coat microcapsules and developer on the same side and use it as self-coloring pressure-sensitive copying paper. There is a way to use it. In the case of these methods, the color developer may be contained in the sheet to which the microcapsule protecting agent is applied, or may be applied together with the microcapsule protecting agent. In this type of color development, the time required to reach the maximum color density is relatively short, and the maximum color density tends to be high. Furthermore, when the microcapsules used in the present invention mostly contain only an organic solvent in which an electron-accepting color developer is dissolved, an electron-donating color former can be coated on one side of the bottom paper or inner paper to form the microcapsules. Use coated top paper or inner paper to stack the microcapsule-coated side and color former coated side facing each other, or apply microcapsules and color former to the same side and use it as self-coloring pressure-sensitive copying paper. There is a way. In the case of these methods, the color former may be contained in the sheet to which the microcapsule protectant is applied, or may be applied together with the microcapsule protectant. Color development in this manner tends to take a relatively short time to reach the maximum color density. As an application of these,
When the microcapsules used are of two types: those containing only an organic solvent in which an electron-donating color former is dissolved, and those containing only an organic solvent in which an electron-accepting color former is dissolved. Mix two types of microcapsules with or without applying an electron-accepting coloring agent to one side of the bottom paper or inner paper, or use two types of microcapsules by stacking the coated sides facing each other. There is a method of mixing them or applying them in layers and using them as self-coloring pressure-sensitive copying paper. There are many other combinations that produce colored images, but they do not depart from the spirit of the present invention as long as a protective agent for the microcapsules is applied before coating or printing the microcapsules.

The present invention will be explained below with reference to Examples, but these Examples are provided to aid understanding of the present invention and are not intended to limit the scope of the present invention.

Example 1 3,3 by the method described in JP-A-51-9079
-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (i.e., crystal violet lactone) dissolved at 2% by weight 1
A microcapsule solution with an average particle size of 3.7 nm containing a -phenyl-1-xylylethane solution was fabricated. The concentration of this solution was 43%.

On the other hand, polyvinyl alcohol (manufactured by Kurashiki Rayon)
Mix 10 parts (by weight) of an aqueous solution containing 10% PVA-117) dissolved in water, 10 parts of wheat starch as a microcapsule protectant, and 60 parts of water, and use a coating rod (Mayer bar) at 1 g/m ² (105℃2
After drying for 1 minute), it was applied to the paper surface so that it would look like this.

Next, 10 parts of the aforementioned microcapsule liquid (in terms of solid content of microcapsules) and 10 parts of an aqueous solution containing 10% polyvinyl alcohol dissolved by weight were mixed and mixed with a coating rod at 3 g/m ² (105°C for 2 minutes). After drying, it was coated on top of the wheat starch so that it would look like this (after drying). Dry the coated paper at 105°C for 2 minutes, layer it on top of a commercially available pressure-sensitive bottom paper (containing p-phenylphenol resin), and use a ballpoint pen from above. When I wrote strongly, I was able to print clearly.

The upper paper produced in the same manner was placed on a flat desk with the capsule-coated side facing up, and was stacked on top of the commercially available lower paper with the coated side facing down. Place a metal weight with a base area of 10 cm ² and a weight of 300 g on top of the bottom paper, fix the top paper so that it does not move, and then move the bottom paper 50 cm with the weight placed on the bottom paper to remove the weight. The color density of the coated surface of the bottom paper was measured with a color difference meter (manufactured by Nippon Denshoku Kogyo) and was found to be 75.5.

Note: The color difference meter reads from 0 to 100, and the lower the number, the darker the color density. (The same applies hereinafter) Comparative Example 1 This comparative example was carried out to show that the effect of the microcapsule protecting agent was improved by Example 1.

Example 1 except applying wheat starch
The upper paper was produced in exactly the same manner as above. Place the upper paper on a flat desk with the capsule coated side facing up.
The microcapsule protective agent applied in Example 1 was extremely effective when a weight was placed on it in the same manner as in Example 1, the color was developed, and the color density was measured using a color difference meter. It was shown that Comparative Example 1 had a small amount, and Comparative Example 1 had a large amount.

Example 2 This example was conducted to demonstrate that a sheet coated with a microcapsule protectant has a relatively good paper profile when partially printed with microcapsules.

A microcapsule solution prepared in the same manner as in Example 1 was spray-dried to form a powder. 50 parts of this microcapsule, ethylcellulose in weight percentage
A solution was prepared by mixing 45 parts of a 12% ethanol solution and 5 parts of an ethanol solution.

Next, a paper surface coated with wheat starch in the same manner as in Example 1 was prepared, and the microcapsule solution was printed on the right half thereof using a rubber plate. We made 20 similar sheets, layered them so that the microcapsule printed parts overlapped, and measured the thickness with a micrometer.The thickness of the part where the microcapsules were not printed was 1264 nm, indicating that the microcapsules were printed. The thickness of the part is 1.280mm,
It was shown that there was no significant difference in thickness.

If a microcapsule protectant is added to the microcapsule solution used for printing, a clearer image with less staining on the coloring surface can be obtained in actual use.

Comparative Example 2 This comparative example was conducted to demonstrate that the precoating of the microcapsule protectant according to Example 2 provides a good paper profile even when the microcapsules are partially printed.

Capsule powder obtained in the same manner as in Example 2
A solution was prepared by mixing 40 parts of wheat starch, 12 parts of wheat starch, and 48 parts of an ethanol solution in which ethyl cellulose was dissolved at a weight percentage of 12%. This capsule solution was printed on the right half of the same paper used in Example 2 using a rubber plate. When we stacked 20 sheets of this so that the microcapsule printed parts overlapped and measured the thickness with a micrometer, the thickness of the part without microcapsules printed was 1.183 mm, and the thickness of the part printed with microcapsules was 1.274 mm. It was hot. This indicates that by applying a protective agent for the microcapsules in advance and then applying or printing the microcapsules, the profile when partially printed with the microcapsules can be improved.

Example 3 This example was designed to show that when the microcapsules and the microcapsule protective agent are applied separately, the printing performance is good even if the microcapsule protective agent is applied in advance.

First, the upper paper produced in Example 1 and the microcapsule coating liquid used in Example 1 were mixed at 3 g/m ²
(After drying at 105℃ for 2 minutes), and then applying wheat starch coating liquid at a coating weight of 1 g/m ² (after drying at 105℃ for 2 minutes). The coated paper, 10 parts of the microcapsule coating liquid used in Example 1, and 8 parts of the wheat starch coating liquid were mixed and coated with a coating rod at a coating weight of 4 g/m ² (after drying at 105°C for 2 minutes). I made the top paper.

These three types of top paper and commercially available bottom paper (containing p-phenylphenol resin) were layered one on top of the other, and an IBM 895 typewriter was used to set the strength to 5 and color the entire surface using printing type. , the concentration was measured in the same manner as in Example 1.
315, was 38.3, and was 32.6. Also, when I printed the elite type W on the same typewriter,
, had less smearing of the characters, while , the smeared characters were a little larger, making the characters appear crushed.

Based on the above, it is considered that printing performance is good if the microcapsule protective agent is applied in advance.

Example 4 This example is an example of a pressure sensitive copying paper coated with an electron-accepting color developer together with a microcapsule protectant.

10 parts aluminum hydroxide, 40 parts wheat starch,
Mix 10 parts of p-phenylphenol resin (formalin condensation product of p-phenylphenol) dispersion (solid content equivalent), 50 parts of a 10% aqueous solution of polyvinyl alcohol (PVA-117 manufactured by Kurashiki Rayon), and 50 parts of water. Coat it on paper with a coating rod at a concentration of 8 g/m ² (after drying at 105°C for 2 minutes), and apply Example 1 on top of it.
The microcapsule solution (mixture with polyvinyl alcohol solution) used in 1 was applied at a concentration of 2 g/m ² (after drying at 105°C for 2 minutes).

This self-coloring pressure-sensitive paper was colored using an IBM 895 typewriter with full color printing type at an intensity of 5, and the density was measured to be 35.1.

In addition, the color development due to "smearing" as in Example 1 was observed, and the concentration was 81.5, indicating that the microcapsule protectant was highly effective.

Claims (1)

[Scope of Claims] 1. In pressure-sensitive copying paper that utilizes the reaction of an electron-donating organic color former and an electron-accepting color developer, an electron-donating organic color former, an electron-accepting developer, and an organic solvent When pressure-sensitive copying paper is produced by coating or printing microcapsules containing at least one microcapsule, the sheet on which the microcapsules are coated or printed is coated with a protective agent for the microcapsules in advance. Method for manufacturing pressure copying paper. 2. The method of item 1, wherein the sheet to which the microcapsule protectant is applied contains at least one of an electron-donating organic color former and an electron-accepting color developer. 3. The method according to item 1 or 2, characterized in that when applying the microcapsule protective agent, at least one of an electron-donating organic color former and an electron-accepting color developer is applied together with the microcapsule protective agent. Method.