JPS5850543A - Transfer paper for wet electrophotography - Google Patents

Abstract

PURPOSE:To obtain transfer paper with superior image clearness and toner fixability by coating base paper with a coating prepared by adding an adhesive contg. a vinyl acetate resin emulsion to a pigment contg. nonplaty crystals. CONSTITUTION:Base paper is coated with a coating prepared by adding 25- 75wt% adhesive consisting of a polyvinyl acetate resin emulsion and a water soluble high molecular adhesive in 100:0-55:45 mixing ratio to a pigment contg. >=50wt% nonplaty crystals and having 0.5-10mum average particle size. The nonplaty crystal content is adjusted to >=50wt% to allow a toner to show an anchoring effect on the pigment. As the pigment calcium carbonate, titanium white, barium sulfate or the like is used. When the average particle size of the pigment is <0.5mum, the anchoring effect on the pigment is not shown, and when the average particle size exceeds 10mum, image clearness and suitability to coating are not obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer paper for developing a static latent image on an insulating layer with liquid Ill and transferring the developed image. The present invention provides a transfer paper with excellent fixing properties.

In general, the quality characteristics required for wet-type electrophotographic transfer paper are I
! The basis of this is image clarity (image density and sharpness) and toner fixability. It is quite difficult to simultaneously satisfy these image quality characteristics. In other words, if you improve the clarity of an image, the toner fixation will decrease, and if you improve the toner fixation, the image will lack clarity.Therefore, conventional transfer paper has been used to improve the image clarity. Currently, images are created with emphasis on ensuring clarity. However, for important documents such as securities, invoices, and receipts that require tamper-proofing, in addition to the clearness of the image, the image must not be easily erased with an eraser (hereinafter referred to as F). The toner is required to have good fixing properties (hereinafter referred to as "water resistance"), and the image will not be disturbed or smudged even if it is rubbed in water (hereinafter referred to as "water resistance").

Possible methods for obtaining such toner fixing properties include a method in which the toner itself has fixing properties, a method in which the toner is subjected to IUM using heat, a solvent, or the like. However, in any case, the current situation is that it is difficult to put it into practical use because of problems such as aging of the current device or complication of the device.

1. In order to improve the erasability and water resistance as described above, a method using polyvinyl alcohol as an adhesive and a water resistance agent such as melamine-polmaldehyde resin, glyoxal, difludehyde starch (Unexamined Japanese Patent Publication No. Showa 56
-Rf't8fi No. 5) is also known, but according to the findings of the present inventors, the sharpness of the image and the erasure resistance can be improved by using polyvinyl alcohol which is oil resistant and has high adhesive strength. However, even if such a water-resistant agent is used in combination, it still has the basic disadvantages of paper, such as letters written with stamps, water-based pens, fountain pens, etc. becoming unclear due to bleeding phenomenon. I understand.

In view of this current situation, the inventors of the present invention have developed a method that does not impair the sharpness of the image, and that even if the image is rubbed with an eraser or the like or wet with water, the image will not be erased, disturbed, or smudged. Regarding wet-type electrophotographic transfer paper that does not bleed characters such as stamp ink and water-based pens,
In particular, the present invention was completed by Kei Sung, who conducted intensive research on the composition of the paint.

In the present invention, the mixing ratio of a vinyl acetate resin emulsion and/or a soluble polymer adhesive is 10 to 50% by weight or more of a pigment having non-plate crystals and an average particle size of O55 to lOμ.
25-75% by weight of adhesive consisting of 0:0-55:45
This is a wet-type electrophotographic transfer paper coated with the used paint.

In the above structure, the non-plate crystal pigment is 50% by weight or more.
The reason why it is essential that the toner be occupied by the toner is to exhibit the anchoring effect of the toner to the pigment. If plate-like pigments (aluminum hydroxide, kaolin, Merck, etc.)
If it accounts for more than % heavy weight, the image will be clear, but on the other hand, the coating layer will become dense and the anchoring effect of the toner to the pigment will not be exerted, and the fixation of the toner will deteriorate. This means that the quality will not match the standard.

For this reason, it is essential that the non-plate crystal pigment accounts for 50'ffi% or more, and preferably 70% or more by weight, which further improves the fixing properties of the toner. Such non-plate crystal pigments include calcium carbonate 1. Examples include titanium white, sachin white, barium sulfate, waxite clay, and silica.

However, as a condition for these pigments to be used in the structure of the present invention, the average particle diameter of the pigments must be within the range of 0.5 to 10μ. If the average particle size is 0.5μ
If smaller particles are used, the coating layer will be dense even with non-plate crystal pigments, and the image clarity will be good, but on the other hand, the anchoring effect of the toner to the pigment will not be exerted, and the fixation of the toner will be poor. Since the paper becomes raccoon-like, it does not meet the quality of the intended transfer paper. In addition, if the particle size of the pigment exceeds 1Oμ, although the anchoring effect of the toner to the pigment can be exerted, the smoothness of the surface of the applied transfer paper decreases, resulting in a lack of sharpness of the image and the coating suitability of the paint. A problem arises in that it is also missing.

For this reason, the most preferable range for the pigment particle diameter is 1 to 6 microns.

In the present invention, the mixing ratio (solid content) of vinyl acetate II fat emulsion and water-soluble polymer adhesive is 100:
An adhesive consisting of 0 to 55:45 is used in an amount of 25 to 75% by weight based on the pigment as described above.

It was generally thought that when a thermoplastic resin is used as an adhesive for transfer paper, the resin softens due to the heat of friction with the eraser, reducing erasure resistance. However, thermoplastic resin emulsions have excellent water resistance, and as a result of various studies conducted by the present inventors, vinyl acetate resin emulsions among thermoplastic resin emulsions have not only improved water resistance, but also improved erasure resistance. They discovered that it has excellent properties.

Vinyl acetate resin emulsions used in the present invention include unplasticized tie 7°, externally plasticized type plasticized by adding a plasticizer, methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, maleic unsaturated carboxylic acid esters such as butyl acid, unsaturated carboxylic acid amides such as acrylamide and methacrylamide,
Monomers such as unsaturated nitriles such as acrylonitrile, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, hydrocarbons such as ethylene, styrene, and butatsuene, and vinyl esters such as Xi tertiary vinyl ester (VeoVa) and vinyl stearate. Examples include internally plasticized types that are plasticized by copolymerization. Among these vinyl acetate resin emulsions, the minimum forming temperature (hereinafter abbreviated as MFT) is 5 to 15°C, and the JI
8 Those with aqueous solubility specified in 4.10.3 (water bottle solubility test) of K6828 (vinyl acetate resin emulsion test method) of 10% or less, preferably 5% or less, have poor obliteration resistance and water resistance. It is preferably used because of its excellent properties.

Furthermore, the vinyl acetate f1%j fat x mal)ion, which has an MFT of 5 to 15°C and an aqueous solubility of 10% or less, preferably 5% or less, and which is internally plasticized, has an anti-obliteration property. It is more preferably used because it improves the three properties of hardness, water resistance, and oil resistance in a well-balanced manner.

In the present invention, as the water-soluble polymer adhesive 1 in which the adhesive is t'i4'IfE together with the above-mentioned vinyl acetate resin emulsion, natural polymer compounds such as starch, cahin, gelatin, cellulose derivatives, acrylic acid, etc. Synthetic polymer compounds such as ester/acrylamide copolymer, styrene/maleic acid silica (alpha form), etc. can be exemplified.In addition, when these water bath polymer adhesives are used together, vinyl acetate resin emulsion alone can be used. Another effect is that the printability of the transfer paper is improved compared to the above.

As mentioned above, such a water-soluble polymer adhesive is used in combination at a solid content of 45% or less with respect to the vinyl acetate resin emulsion, and beyond that, the use of -F in combination is not for the purpose of the present invention. This is undesirable because it impairs water resistance.

In addition, the vinyl acetate resin emulsion and the water-soluble polymer adhesive used in the present invention may be used in combination of two or more substances.

In the present invention, the adhesive as described above has a
It is used in a range of 5 to 75% by weight, for example, 25% by weight1. If the amount is less than 75% by weight, the toner fixing property deteriorates and only a transfer paper with poor erasure resistance is obtained if the amount exceeds 75% by weight. In particular, when using an adhesive of 30 to 60% by weight based on the pigment, it is possible to maintain appropriate oil resistance and also exhibit good obliteration resistance and water resistance, so it is preferably used. It is something.

In addition, various auxiliary agents such as dispersants such as sodium polyacrylate and polyphosphates, lubricants such as calcium stearate, and antifoaming agents may be appropriately added to the coating composition as long as they do not impede the effects of the present invention. Can be added.

Note that any method such as an air knife coater, roll coater, bar coater, blade coater, etc. may be used to apply the paint to the base paper, but among these, the grade coater has excellent surface smoothness. This is the most preferable coating method in that it is possible to obtain a smooth surface.

Coat 1 #1 is about 3 to 10 f//77/n, preferably 5 to lOf/n? It is.

Incidentally, below 3 f/d, the anchoring effect of the toner to the pigment is insufficient, resulting in poor fixing properties, and above 10 f/d, the quality characteristics are the same, and there is no need to apply a large amount. It's for a reason.

EXAMPLES Below, Examples and Comparative Examples are given to further enhance the effects of the present invention, but the present invention is not limited thereto. In addition, % and parts in the examples represent weight % and parts unless otherwise specified.

Example 1 100 parts of modified calcium carbonate having an average particle size of 7.1μ was dispersed in 0.05 parts of solid content of a dispersant (sodium polyacrylate) dissolved in 50 parts of water. Emulsion (Movinyl DC, manufactured by Hoechst Synthesis) and externally plasticized acetic acid? ``=l:l mixed emulsion with Le Emulsion (Movinyl DC-02, manufactured by Hoechst Synthesis)''
Shore (a degree' 58%, MFT:
6°C, water soluble content: 5%) was added and mixed, then 01 part of lubricant and 0.2 part of antifoaming agent were added, and water was further added to prepare a paint with a solid content concentration of 60%. .

This paint was applied onto the base paper using a blade coater so that it had a dry softness of 7'i/d, and after drying, it was applied with a super calender so that the surface smoothness (Beck) was 100 seconds/l0CC, and wet W was applied. Transfer paper for child photographs was obtained.

Example 2 In a solution of 0.005 parts of a dispersant (diphosphate) in 150 parts of water, 70 parts of heavy calcium carbonate with an average particle size of 4.2 μm and 30 parts of heavy calcium carbonate with an average particle size of 1.8 μm were dissolved. After dispersing, 25% of a 20% aqueous solution of styrene-maleic acid copolymer (Polymalon 35lS, manufactured by Arakawa Chemical Co., Ltd.)
and 50% #acid vinyl emulsion (Movinyl 5
0M, manufactured by Hoechst Synthesis Co., Ltd., MFT: 15°C, 15%, aqueous solution: 5%) were sequentially added and mixed, and then 0.1 part of lubricant, 0.2 part of antifoaming agent, and water were added. plus 25
% concentration paints were prepared.

This paint was coated onto a base paper using a bar coater to a dry weight of 117 m'', and then subjected to super calendering in the same manner as in Example 1 to obtain a transfer paper for wet electrophotography.

Example 3 0.05 part of a dispersant (diphosphate) was dissolved in 150 parts of water, and 1 part of heavy calcium carbonate with an average particle size of 4.2μ was dissolved in this.
After dispersing 00 parts, 130 parts of a 15% oxidized starch aqueous solution and a vinyl acetate/acrylic acid ester copolymer emulsion with a solid content concentration of 46% (Movinyl 780, manufactured by Hoechst Synthesis, MFT: 9°C, aqueous solution) were added. 110 parts of lubricant, then 0.1 part of lubricant and 0 part of antifoaming agent.
．． A 30% strength paint was prepared by adding 2 parts and water.

This paint was applied to base paper using an air knife coater so that the dry weight was 'IQ.

Example 4 80 parts of heavy calcium carbonate with an average particle size of 4° 2μ and an average particle size of 1 were added to a solution of 0.05 parts of solid content of a dispersant (sodium polyacrylate) dissolved in 100 parts of water.
After dispersing 75 parts of a 20% aqueous solution of enzyme-modified starch with 20 parts of kaolin, a non-plastic vinyl acetate emulsion (Movinyl DC, manufactured by Hoechst Synthesis Co., Ltd., MFT: 15°C, aqueous solution) with a solid content concentration of 56% was dispersed. 0.1 part of a lubricant, 0.2 part of an antifoaming agent, and water were added to prepare a paint having a solid content of 40%.

This paint was applied to base paper using a roll coater so that the dry coating hL was 71/771, and then subjected to super calendering in the same manner as in Example 1 to obtain a wet electrophotographic transfer paper.

Example 5 Instead of the heavy calcium carbonate and kaolin used in Example 4, heavy calcium carbonate 1 with an average particle size α8μ
A wet electrophotographic transfer paper was obtained in the same manner as in Example 4 except that 00 parts were used.

Example 6 After dispersing 100 parts of heavy calcium carbonate with an average particle size of 4.2μ in 150 parts of water and 0.05 parts of a dispersant (diphosphoric acid JfA), 70 parts of a 15% oxidized starch aqueous solution was prepared.
Vinyl acetate/acrylic acid ester copolymer emulsion with a solid content of 50% (Movinyl 630I Hekinuto Synthesis Co., Ltd., MFT: 19°C, aqueous solution: 5%) 80
0.1 part of a lubricant, 0.2 part of an antifoaming agent, and water were then added to prepare a 35% concentration paint. This paint was applied onto base paper using an air knife coater to give a dry weight of 7 f/d, and then dried, followed by super calendering in the same manner as in Example 1 to obtain a wet electrophotographic transfer paper.

Example 7 '8 In Example 6, instead of the vinyl acetate/acrylic acid ester copolymer emulsion, a vinyl acetate/ethylene copolymer emulsion (Panflex 0M-4) 000° manufactured by Kuraray Co., Ltd. with a solid content concentration of 56% was used. A wet electrophotographic transfer paper was obtained in exactly the same manner as in Example 6, except that 70 parts of M F T knee B°C (water soluble content: 2%) was used.

Example 8 In place of the vinyl acetate/acrylic ester copolymer emulsion used in Example 6, a vinyl acetate/acrylic ester copolymer emulsion with a solid content concentration of 43% (Movinyl 77111, Hoechst Synthesis Co., Ltd. 1.MFT) was used.
: 10-11 DEG C., Water Bottle Solubility = 20%) The procedure was repeated in the same manner as in Example 6, except that 90 parts of the wet-type transfer paper for photographic printing was obtained.

Comparative Example 1 Water 150. 0.05 parts of solid content of a dispersant (sodium polyacrylate) was dissolved in a solution containing an average particle size of 42 parts.
μ heavy calcium carbonate 80 parts and average particle size 1.0
20 parts of kaolin of μ is dispersed, and further 67 parts of a 15% oxidized starch aqueous solution and 80 parts of styrene-butadiene copolymer latex (SN-307, manufactured by Sumitomo Naugatuck) with a solid content concentration of 48% are added and mixed. Next, 01 part of a lubricant, 02 parts of an antifoaming agent, and water were added to prepare a paint having a solid content concentration of 25%. Apply this paint on the base paper in a dry coating amount of 7 da/
After applying it with air knife caulk so that it looks like I,
A wet electrophotographic transfer paper was obtained using a super calender in the same manner as in Example 1.

Comparative Example 2 In 100 parts of water and 0.05 part of solid content of a dispersant (sodium/lium polyacrylate) was dissolved, an average particle size of 71.
After dispersing 100 parts of heavy calcium carbonate of μ, 1 part of polyvinyl alcohol (PVA-117, manufactured by Kuraray Co., Ltd.)
250 parts of 5% aqueous solution, 50 parts of 15% oxidized starch aqueous solution and 1 part of 20% aqueous solution of melamine formaldehyde resin (Numiresotsu 613, manufactured by Sumitomo Chemical Co., Ltd.)
After sequentially adding and mixing 5 parts, water was added to make the solid content concentration 2.
A 0% paint was prepared. Dry application of this paint on the base paper 1
After coating with a bar coater to give qy/nr at 1 t, the coating was applied with a super calender in the same manner as in Example 1 to obtain a transfer paper for wet electrophotography.

Comparative Example 3 Same as Example 4 except that the composition ratio of heavy calcium carbonate with an average particle size of 4.2μ used in Example 4 and kaolin with a 1μ average particle size of 1.0μ was used as 40 parts = 60 parts. A wet electrophotographic transfer paper was obtained.

Comparative Example 4 100 parts of heavy calcium carbonate with an average particle size of 12μ was used instead of the heavy calcium carbonate with an average particle size of 4.2μ and kaolin with an average particle size of 1.0μ used in Example 4. A wet electrophotographic transfer paper was obtained in the same manner as in Example 4.

Comparative Example 5 A wet electrophotographic transfer paper was prepared in the same manner as in Example 4, except that 100 parts of light calcium carbonate with an average particle size of 0.2 μm was used in place of the heavy calcium carbonate and kaolin used in Example 4. Obtained.

Comparative Example 6 Wet electrophotography was carried out in the same manner as in Example 4, except that the amounts of enzyme-modified starch aqueous solution and non-plastic vinyl acetate emulsion (Movinyl 1) C) were changed to 100 parts and 35 parts, respectively. A transfer paper was obtained.

Comparative Example 7 100 parts of heavy V-sium carbonate having an average particle size of 42 μm was dispersed in 150 parts of water and 0.005 parts of a dispersant (diphosphate), and then 200 parts of a 15% oxidation-modified helium powder aqueous solution was prepared. and solid content concentration 46% (add and mix 109 parts of rattl hinyl acrylic acid ester emulsion (Movinyl 780), then add 01 part lubricant, 0.2 part antifoaming agent and water to make solid content concentration 30%) A paint was prepared.

Example 1: This paint was dried and applied to the base paper using an air knife coater so that h) [ was Tf/nf.
In the same way as above, I used a super calender to obtain transfer paper for wet type Ichiko photography.

Evaluation test (1) Printability (image sharpness) 11 types of wet electrophotographic transfer paper were printed in Examples and Comparative Examples using a liquid dry plain paper copying machine (NFL7-b,
Image density (Macbeth densitometer) and sharpness (QO times V
- Enlarged image by Beni et al.) was evaluated. The results are shown in Table 1.

(2) Erasing resistance The printed matter obtained in (1) above was erased using two types of commercially available plastic erasers (NIIOIO, Fubino 1 Co., Ltd. and Lion PL-500.7 Kui Co., Ltd.).
The erasing state of the print after rubbing twice and 50 times was evaluated using the outer corner of the eye. The results are shown in Table 1.

(3) Using water-resistant gauze or a fingertip, rub the printed matter obtained in (1) above with water, rub it 20 times, and then visually evaluate the state of the printed matter and dirt. listed in the table.

(4) Stamp ink bleeding Stan 7” ink (Sol stamp red, manufactured by Shachihata)
Evaluate the degree of blurring of the stamped characters using the
The results are shown in Table 1.

As is clear from the results in Table 1, the wet electrophotographic transfer paper obtained by the present invention not only has excellent image clarity, but also has excellent erasure resistance and water resistance, and is free from ink bleeding. It was a transfer paper that could be used with confidence, especially for Important Class S documents such as securities that require tamper-proofing.

Patent applicant: Kami 11ki Paper Co., Ltd.

Claims (1)

[Claims] 50% by weight or more are non-plate crystals, and the average particle size is 0.
For a pigment of 5 to 10μ, a mixture of a vinyl acetate resin emulsion and a water-soluble polymer liquid>i'#t'i11 with a mixing ratio of 1'00:O to 55:45 is mixed with 2
A transfer paper for wet type electrophotography characterized by being coated with a paint containing 11% of 5 to 75 h.