JPH0124300B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a transfer paper for developing an electrostatic latent image on an insulating layer with a liquid developer and transferring the developed image, and particularly provides a transfer paper with excellent image clarity and toner fixability. It is something to do. In general, the quality characteristics required for wet-type electrophotographic transfer paper include image clarity (image density and sharpness) and toner fixability. It is quite difficult to satisfy both of these quality characteristics at the same time. That is, if the sharpness of the image is improved, the fixability of the toner decreases, and if the fixability of the toner is improved, the sharpness of the image becomes lacking. Therefore, the current state of the art is that transfer paper has been manufactured with emphasis placed on ensuring the clarity of images. However, when used for important documents such as securities, invoices, and receipts that require tamper-proofing, in addition to the clarity of the image, good toner fixation is required so that the image cannot be easily erased with an eraser, etc. It is required. 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 fixed using heat, a solvent, etc. However, in any case, there are problems such as aging of the developer and complexity of the device, so it is difficult to put them into practical use at present. The inventors of the present invention have conducted intensive research to develop a transfer paper with excellent fixing properties that does not impair the clarity of the image and also prevents the image from being erased with an eraser. It has been experimentally confirmed that the above properties can be satisfied depending on the relationship between the fixing agent of the toner and the pigment, the average particle diameter of the pigment, the type of adhesive, the amount of adhesive used for the pigment, etc. I was able to do it. This satisfactory condition means that the mixing ratio (solid content) of water-soluble polymer adhesive and resin emulsion is 50% or more by weight of non-plate crystals, and the average particle size is 2 to 10μ. It involves applying a paint containing 4 to 50% by weight of an adhesive of 100:0 to 50:50 to the base paper. In the above configuration, the non-plate crystal pigment must account for 50% by weight or more in order to exhibit the anchoring effect of the toner to the pigment.
If plate-like crystal pigments (aluminum hydroxide, kaolin, talc, etc.) account for 50% or more by weight, the image will be clear, but the coating layer will be dense and the anchoring effect of the toner to the pigment will not be achieved. As a result, the toner fixability deteriorates, and the quality of the intended transfer paper is not met.
For this reason, non-plate crystal pigments are 50% by weight.
It is essential that the content is above 70% by weight, and preferably 70% by weight or more improves the fixing properties of the toner. Non-plate crystal pigments include calcium carbonate,
Examples include titanium white, sachin white, barium sulfate, waxite clay, and silica. However, the conditions for these pigments to be used in the composition of the present invention are that the average particle diameter of the pigment is 2 to 10 μm.
must be within the range. If you use a pigment with an average particle size of 2μ or less, the coating layer will be dense even if it is a non-plate crystal pigment.
Although the image clarity is good, on the other hand, the anchoring effect of the toner to the pigment is not exhibited, and the toner fixability is deteriorated, so that the quality as a transfer paper is not met. In addition, if the particle size of the pigment exceeds 10μ, even if the anchoring effect of the toner to the pigment can be achieved, the smoothness of the surface of the applied transfer paper will decrease, 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 3 to 6 microns. When applying such a pigment to base paper, it is first prepared into a paint. When preparing this paint, it is essential to use an adhesive with a mixing ratio (solid content) of water-soluble polymer adhesive and resin emulsion of 100:0 to 50:50 in an amount of 4 to 50% by weight based on the pigment. It is something to do. Conventional transfer paper mainly uses resin emulsion as an adhesive for pigments. This is to prevent the solvent of the liquid developer from penetrating (to provide oil resistance), but since resin emulsion has film-forming properties, the image clarity and printability are good when used, but the toner fixation is It is unfavorable in terms of performance, and if a large amount is used, there is a problem that the image can be easily erased with an eraser. From these results, it has become clear that toner fixability is also affected by the type of adhesive. Experimental confirmation has revealed that natural and/or synthetic water-soluble polymer adhesives are suitable as adhesives for the pigment. Since these water-soluble polymer adhesives have weaker film-forming properties than resin emulsions, they do not inhibit the anchoring effect of the toner onto the pigment. However, when resin emulsion is used as an adhesive for pigments, it is more effective than water-soluble polymer adhesives in terms of printability, and it can be used in combination with water-soluble polymer adhesives within a specified amount. As long as the toner fixing properties are inhibited, there is no problem in using the water-soluble polymer adhesive and resin emulsion together as long as the mixing ratio (solid content) is within the range of 100:0 to 50:50. . Water-soluble polymer adhesives include natural ones such as starch, casein, and gelatin, and synthetic ones such as polyvinyl alcohol, carboxy-modified polyvinyl alcohol, cellulose derivatives,
Acrylic acid ester-acrylamide copolymer,
Examples include styrene/maleic acid copolymer. As the resin emulsion, conjugated diene polymer latex such as styrene/butadiene copolymer, methyl methacrylate/butadiene copolymer, acrylic polymer such as a polymer or copolymer of acrylic acid ester and/or methacrylic acid ester latex, vinyl polymer latex such as ethylene/vinyl acetate copolymer, or alkali-soluble or alkali-insoluble polymers obtained by functionally modifying these various polymers with monomers containing functional groups such as carboxyl groups. There are latex etc. In the structure of the present invention, it is essential to use the above-mentioned adhesive in an amount of 4 to 50% by weight based on the pigment. Incidentally, if it is less than 4% by weight, the oil resistance of the applied transfer paper will be poor and clear images will not be obtained, and the paint will not be suitable for coating, and if it is more than 50% by weight, the clarity of the image on the applied transfer paper will be poor. Although it is good, the toner fixability is poor and the image is easily erased with an eraser. For this reason, the most preferred quantitative range of adhesive to pigment is 10 to 35% by weight. 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 blade coater has excellent surface smoothness. This is the most preferred coating method in terms of the ability to obtain a uniform surface. The coating amount is about 3 to 10 g/m ² , preferably 5 to 10 g/m ² . Incidentally, if it is ^less than 3g/m2, the anchoring effect of the toner to the pigment is insufficient, and the fixing property is poor.
Above g/ ^m2 , the quality characteristics are almost the same;
This is because there is no need to apply a large amount. Transfer paper with the above structure is different from conventional transfer paper, which prioritizes image clarity and is complacent about poor toner fixation, and can satisfy both quality characteristics at the same time, and is required to be tamper-proof. It has excellent properties that allow it to be safely used for important documents such as securities, bills, and receipts. Examples are described below to help understand the present invention. However, it goes without saying that the present invention is not limited only to these examples. Example 1 After dispersing 100 parts by weight of heavy calcium carbonate with an average particle size of 7.1μ in 0.05 parts by weight of a dispersant (polyphosphate) dissolved in 100 parts by weight of water, 50 parts by weight of a 10% oxidized starch solution was added. and 67 parts by weight of a 15% polyvinyl alcohol (PVA-117, manufactured by Kuraray Co., Ltd.) aqueous solution were sequentially added and mixed, and then 0.3 parts by weight of an antifoaming agent was added until the concentration of the system was 30%. A paint was prepared by adding 67 parts by weight of water. This paint was applied to base paper with a blade coater to a dry weight of 8g/ ^m2 , and the surface smoothness (Beck) was 150.
A transfer paper for wet electrophotography was prepared by supercalendering at a speed of 10 c.c./sec. The clarity of the transferred image and the toner fixability of this transfer paper were as shown in the attached table. Example 2 80 parts by weight of heavy calcium carbonate with an average particle size of 7.1μ and 20 parts by weight of kaolin with an average particle size of 0.7μ were dispersed in 0.05 parts by weight of a dispersant (polyphosphate) dissolved in 77 parts by weight of water. After that, 200 parts by weight of 10% oxidized starch solution,
67 parts by weight of a 15% polyvinyl alcohol (PVA-117, manufactured by Kuraray Co., Ltd.) aqueous solution and 16 parts by weight of 48% styrene-putadiene copolymer latex were sequentially added and mixed, and then 0.3 parts by weight of an antifoaming agent was added. A paint with a concentration of 30% was prepared. After applying this paint to base paper with a blade coater to a dry weight of 8 g/m ² , the surface smoothness (Beck) was 150 seconds/m2.
A wet electrophotographic transfer paper was created by applying a super calender to a thickness of 10c.c. The clarity of the transferred image and the toner fixability of this transfer paper were as shown in the attached table. Example 3 After dispersing 100 parts by weight of heavy calcium carbonate with an average particle size of 4.2μ in 0.05 parts by weight of a dispersant (polyphosphate) dissolved in 100 parts by weight of water, a 10% oxidized starch aqueous solution of 70 parts by weight was prepared. Parts by weight, 93 parts by weight of 15% polyvinyl alcohol (PVA-117, manufactured by Kuraray Co., Ltd.) aqueous solution and
48% styrene-butadiene copolymer latex 6
Add and mix 0.4 parts by weight sequentially, then 0.4 parts by weight of antifoaming agent.
After adding 127 parts by weight of water, a paint was prepared by adding 127 parts by weight of water so that the concentration of the system was 25%. This paint is applied to base paper using an air knife coater to give a dry weight of 8 g/ ^m2 , and then supercalendered to a surface smoothness of 150 seconds/10 c.c. for wet electrophotography. I created a transfer paper. The clarity and fixability of the transferred image on this transfer paper were as shown in the attached table. Example 4 After dispersing 100 parts by weight of heavy calcium carbonate with an average particle size of 3.0μ in 0.05 parts by weight of a dispersant (polyphosphate) dissolved in 100 parts by weight of water, 40 parts by weight of a 5% carboxymethylcellulose aqueous solution was prepared. 50 parts by weight of 10% oxidized starch aqueous solution, 100 parts by weight of 15% polyvinyl alcohol (PVA-117, manufactured by Kuraray Co., Ltd.) aqueous solution, and 10 parts by weight of 48% styrene-butadiene copolymer latex were sequentially added and mixed. then antifoaming agent
After adding 0.4 parts by weight, a paint was prepared by adding 30 parts by weight of water so that the concentration of the system was 30%. This paint was applied to the base paper using a blade coater to give a dry weight of 8 g/m ² , and then supercalendered to a smoothness of 150 seconds/10 c.c. for wet electrophotographic transfer. Created a paper. The clarity and fixability of the transferred image on this transfer paper were as shown in the attached table. Example 5 70 parts by weight of heavy calcium carbonate with an average particle size of 4.2μ and 30 parts by weight of kaolin with an average particle size of 0.7μ were dispersed in 0.05 parts by weight of a dispersant (polyphosphate) dissolved in 100 parts by weight of water. After that, 50 parts by weight of 10% oxidized starch aqueous solution, 15% polyvinyl alcohol (PVA-117,
A paint was prepared by sequentially adding and mixing 100 parts by weight of an aqueous solution (manufactured by Kuraray Co., Ltd.), then adding 0.5 parts by weight of an antifoaming agent, and then adding 51 parts by weight of water so that the concentration of the system was 30%. did. Apply this paint to base paper with a dry weight of 8
A wet electrophotographic transfer paper was prepared by applying the coating using a blade coater to give a smoothness of 150 seconds/10 ^c.c. using a super calender. The clarity and fixability of the transferred image on this transfer paper were as shown in the attached table. Example 6 80 parts by weight of heavy calcium carbonate with an average particle size of 4.7μ and 20 parts by weight of talc with an average particle size of 13μ were dispersed in 0.05 parts by weight of a dispersant (polyphosphate) dissolved in 100 parts by weight of water. After that, 50 parts by weight of 10% oxidized starch aqueous solution, 15% polyvinyl alcohol (PVA-117,
67 parts by weight of an aqueous solution (manufactured by Kuraray Co., Ltd.) and 30 parts by weight of a 10% styrene-maleic acid copolymer were sequentially added and mixed, and then 0.3 parts by weight of an antifoaming agent was added.
A paint was prepared by adding 47 parts by weight of water so that the concentration of the system was 30%. This paint is applied to base paper using a blade coater to give a dry weight of 8 g/m ² , and then supercalendered to a smoothness of 150 seconds/10 c.c. to transfer paper for wet electrophotography. It was created. The clarity and fixability of the transferred image on this transfer paper were as shown in the attached table. Example 7 90 parts by weight of heavy calcium carbonate with an average particle size of 7.1μ and 10 parts by weight of kaolin with an average particle size of 0.7μ were dispersed in 0.05 parts by weight of a dispersant (polyphosphate) dissolved in 100 parts by weight of water. After that, 50 parts by weight of 10% oxidized starch aqueous solution, 15% polyvinyl alcohol (PVA-117,
100 parts by weight of an aqueous solution (manufactured by Kuraray Co., Ltd.) and 31 parts by weight of a 48% styrene-butadiene copolymer latex were sequentially added and mixed, and then 0.5 parts by weight of an antifoaming agent was added, until the concentration of the system reached 25%. A paint was prepared by adding 160 parts by weight of water. This paint was applied to the base paper using an air knife coater to give a dry weight of 8 g/ ^m2 , and the smoothness (Beck) was 150.
Transfer paper for wet electrophotography was prepared by supercalendering at a rate of 10 c.c./sec. The clarity and fixability of the transferred image on this transfer paper were as shown in the attached table. Comparative Example 1 80 parts by weight of heavy calcium carbonate with an average particle size of 1.8μ and 20 parts by weight of kaolin with an average particle size of 0.7μ are dispersed in 0.05 parts by weight of a dispersant (polyphosphate) dissolved in 100 parts by weight of water. After that, 100 parts by weight of 10% oxidized starch aqueous solution and 83 parts by weight of 48% styrene-butadiene copolymer latex were sequentially added and mixed, and then an antifoaming agent was added.
After adding 0.5 parts by weight, a paint was prepared by adding 216 parts by weight of water so that the concentration of the system was 25%. This paint was applied to base paper using an air knife coater to give a dry weight of 8 g/ ^m2 , and then supercalendered to give a smoothness of 150 seconds/10 c.c. for wet electrophotographic transfer. Created a paper. The clarity and fixability of the transferred image on this transfer paper were as shown in the attached table. Comparative Example 2 After dispersing 100 parts by weight of kaolin with an average particle size of 0.7 μ in 0.05 parts by weight of a dispersant (polyphosphate) dissolved in 100 parts by weight of water, 50 parts by weight of a 10% oxidized starch aqueous solution, 15 % polyvinyl alcohol (PVA−
117. Manufactured by Kuraray Co., Ltd.) 67 parts by weight of aqueous solution were added sequentially.
After mixing and then adding 0.5 parts by weight of antifoaming agent,
A paint was prepared by adding 67 parts by weight of water so that the concentration of the system was 30%. Apply this paint to base paper with a dry weight of 8
A wet electrophotographic transfer paper was prepared by applying the coating using a blade coater to give a smoothness of 150 seconds/10 ^c.c. using a super calender. The clarity of the transferred image and the toner fixability of this transfer paper were as shown in the attached table. Comparative Example 3 Average particle diameter
After dispersing 100 parts by weight of 1.0μ heavy calcium carbonate, 15% polyvinyl alcohol (PVA-
110 (manufactured by Kuraray Co., Ltd.) 40 parts by weight of aqueous solution, 120 parts by weight of 10% styrene/maleic acid copolymer, 60 parts by weight of 20% acrylic ester/acrylamide copolymer, and 48% styrene/butadiene copolymer. After sequentially adding and mixing 71 parts by weight of polymerized latex and then adding 0.3 parts by weight of antifoaming agent, the concentration of the system was 25%.
A paint was prepared by adding 167 parts by weight of water. This paint was applied to base paper using an air knife coater to give a dry weight of 8 g/ ^m2 , and then supercalendered to give a smoothness of 150 seconds/10 c.c. for wet electrophotographic transfer. Created a paper. The clarity of the transferred image and the toner fixability of this transfer paper were as shown in the attached table. Comparative Example 4 After dispersing 100 parts by weight of heavy calcium carbonate with an average particle size of 12μ in 0.05 parts by weight of a dispersant (polyphosphate) dissolved in 100 parts by weight of water, 50 parts by weight of a 10% oxidized starch aqueous solution was added. , 67 parts by weight of a 15% polyvinyl alcohol (PVA-117, manufactured by Kuraray Co., Ltd.) aqueous solution, and 21 parts by weight of styrene-butadiene copolymer latex were sequentially added and mixed, and then 0.3 parts by weight of an antifoaming agent was added. , water so that the concentration of the system is 30%.
A paint was prepared by adding 80 parts by weight. This paint was applied to base paper with a blade coater to a dry weight of 8g/ ^m2 , and the smoothness was 150.
Transfer paper for wet electrophotography was prepared by supercalendering at a speed of 10 c.c./sec. The clarity of the transferred image and the toner fixability of this transfer paper were as shown in the attached table.

【table】

[Table] (Note) ◎ is excellent, ◎' is good, ○ is acceptable, × is not possible. Transfer the electrophotography society test chart No. 1-R1975 using a plain paper copying machine (NP-L7b manufactured by Canon Inc.), and check the sharpness of the image by measuring the image density (Macbeth densitometer).
The fixability of the toner was evaluated using a magnified image using a 20x magnifying glass.
This is an evaluation of the erased state after rubbing several times.

Claims (1)

[Claims] 1 The mixing ratio (solid content) of water-soluble polymer adhesive and resin emulsion is
4-50% by weight of adhesive consisting of 100:0-50:50
Wet-type electrophotographic transfer paper coated with the used paint.