JPH0767878B2 - Image transfer paper - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer paper used for transferring an image formed by an electrostatic copying method (including an electrophotographic method) or printing to a transfer object.

[0002]

2. Description of the Related Art Images such as characters and designs formed on a transfer sheet are transferred to a transfer target such as woven cloth, leather, metal plate, wood plate, glass, and paper by electrostatic copying or printing. Various methods and transfer sheets used therefor have been proposed. For example, in JP-A-58-202472, an electrostatic image is formed on a transfer sheet in which a release agent such as a silicone resin is applied on a support material made of paper, synthetic paper, a plastic sheet, etc. A method has been proposed in which a transfer sheet is heated and pressed using a roll or the like to transfer an image on a transfer material and then the support material is peeled off.

Further, JP-A-60-92897 discloses a first transfer paper having a sheet-like support provided with a release layer, and a second transfer paper having a sheet-like support provided with a release layer and an adhesive layer. Prepare a normal image pattern on the peeling layer of the first transfer paper by dry electrostatic copying means or depiction means, then overlay this peeling layer on the adhesive layer of the second transfer paper, peel off both papers after thermocompression bonding, Transferred as a reverse image to the adhesive layer of the second transfer paper, after the reverse image of the second transfer paper is overlaid and pressure-bonded to the transfer target, the second transfer paper support is peeled off, and the normal image pattern is transferred to the transfer target surface. The method of doing is proposed. It is described therein that as the second transfer paper, a sheet coated with low molecular weight polyethylene, EVA or the like or a wet transfer paper for ceramics is used.

Further, in JP-A-62-212187, an image of powder toner is formed on a transfer paper coated with a water-soluble adhesive by using an electrostatic copying machine, and then the image is immersed in an active liquid to activate the toner. A method has been proposed in which a resin contained in a toner is swollen or dissolved to impart adhesiveness, and then an image is transferred to a transfer target.

On the other hand, as a transfer painting method for the surface of the ceramics, a composite paper painting method and a single paper painting method have been known for a long time. The single paper painting method is to apply a water-soluble resin such as starch or polyvinyl alcohol twice on the surface of a water-absorbent paper, and then form a pattern with a ceramic colorant made of a metal compound,
After that, the water-soluble resin layer is activated by water so that it can be peeled off, the pattern is transferred together with the water-soluble resin layer on the surface of the ceramics, and after that, baking is performed at a high temperature for painting. Therefore, it is absolutely necessary that the water-soluble resin layer is decomposed during firing and does not adversely affect the colorant such as turbidity. The transfer paper used for this purpose is Japanese Patent Publication No. 27-19.
No. 59, Japanese Patent Publication No. 29-1307, Japanese Patent Publication No. 44-161
No. 35, Japanese Patent Publication No. 46-30283, Japanese Patent Publication No. 51-33
No. 451, Japanese Patent Publication No. 52-18727, Japanese Patent Publication No. 62-5
There are many proposals such as No. 3360, Japanese Patent Publication No. 1-20080, etc.

[0006]

If these conventionally known transfer papers for ceramics are used for transferring the above-mentioned electrostatically copied images, there are the following problems. Transfer paper for ceramics usually has a basis weight of 150 to 180 g / m ² and a thickness of 160 to 200.
The one with μm is used. When this is used for electrostatic copying type transfer paper, the toner is scraped off by the fixing device of the copying machine (fixing roll temperature is about 180 ° C. and silicone oil is applied), and a good image cannot be obtained. Cause a problem. This problem occurs because the transfer paper is too thick and the linear pressure by the fixing roll is excessively applied to the transfer paper surface. Since the transfer paper for ceramics is rigid, so-called "floating" occurs on the transfer drum, and the toner transferred from the photosensitive drum does not uniformly adhere to the surface of the transfer paper. Also, paper jams easily occur inside the copier.
The water-soluble sizing agent layer is sensitive to changes in humidity and tends to become sticky under high humidity. Therefore, when the transfer papers are stacked and continuous copying is performed, there arises a problem that a plurality of transfer papers are fed at one time. Further, under low humidity, there is a problem that the water-soluble sizing agent layer is dehydrated and the transfer paper is curled and cannot be fed. When immersing the copied transfer paper in the active liquid, the active liquid does not penetrate uniformly from the back side because the transfer paper is too thick.
Therefore, it takes too much time to uniformly activate the toner. When the toner is transferred to the transfer target, the transfer paper is required to have abrasion resistance when wet because it is hydrated from the back surface of the transfer paper with a wet cloth and rubbed while removing bubbles with a squeegee or the like. Transfer paper for ceramics does not have this property.

As described above, it is extremely difficult to transfer an image by the electrostatic copying method using the transfer paper for ceramics. The present invention is particularly applicable to the transfer method as proposed in the above-mentioned JP-A-62-212187, that is, after forming an image of powder toner on a transfer paper by using an electrostatic copying machine, dipping in an active liquid. An object of the present invention is to develop an image transfer paper that can be suitably used in a method of activating toner and then transferring it to a transfer target.

[0008]

The gist of the present invention will be described with reference to the drawings. A water-soluble sizing agent layer 2 having a slow rewet dissolution rate and a water solution having a fast rewet dissolution rate are formed on the surface of a base paper 1. Adhesive layer 3 is sequentially provided, and a curl prevention layer 4 is further provided on the back surface.
To obtain an image transfer paper provided with.

The base paper 1 must be a non-size paper having a wet strength and a weak size paper.
P-, LBKP, NBSP, etc.
600 ml C.I. S. Beat to F and add melamine resin,
Known wet strength agents such as urea resin and epoxy resin,
Add a small amount of sizing agent, filler, etc.
It is necessary to make paper with a thickness of 0 to 120 μm. When the thickness of the base paper is less than 50 μm, curling under low humidity is remarkable, which causes a problem that the paper cannot be supplied.
If it exceeds μm, paper jam inside the copying machine and toner removal may occur.

The water-soluble sizing agent having a slow rewet dissolution rate of the present invention means sizing agent of 1 to 5 g / m on a base paper having a thickness of 50 to 120 μm.
^{2 When} applied and immersed in water,
Means a sizing agent that takes ~ 15 seconds. A water-soluble sizing agent with a slow rewet dissolution rate usually has a high viscosity when dissolved,
It has the advantage that it can be applied even on non-sized base papers for transfer paper, with almost no penetration of the sizing agent. The water-soluble sizing agent with a slow rewet dissolution rate that can be used in the present invention includes potato starch, tapioca starch,
Examples include natural starch such as corn starch, modified starch obtained by oxidation, pre-treatment, etherification and esterification thereof, cellulose derivatives such as carboxymethyl cellulose and methyl cellulose, and polyvinyl alcohol. In particular, potato starch, esterified starch, and polyvinyl alcohol have a high viscosity when re-wet and dissolved, and therefore can be suitably used in the present invention. The water-soluble sizing agent layer 2 having a slow rewet dissolution rate is the base paper 1
The surface is usually coated with 1 to 5 g / m ² .

The water-soluble sizing agent having a high rewetting dissolution rate means that when the sizing agent is coated on the above-mentioned base paper in an amount of 5 to 15 g / m ² and immersed in water, the sizing agent is dissolved in an amount of 1 to 4 Means a sizing agent that takes seconds. Pregelatinized starch, dextrin, gum arabic, gelatin and the like can be preferably used for the water-soluble sizing agent layer 3 having a fast rewet dissolution rate. It is particularly preferable to use dextrin because of its high dissolution rate in cold water and low viscosity during rewet dissolution. The water-soluble sizing agent 3 having a fast re-wetting and dissolution rate is usually applied on the water-soluble sizing agent layer 2 having a slow re-wetting and dissolution rate in an amount of 5 to 15 g / m ² . Coating amount is 5g /
If it is less than m ² , the transfer of the copied image to the transferred material is poor, and if it exceeds 15 g / m ² , the paper tends to curl.
At this time, inorganic fine powder such as clay, calcium carbonate, silica or a water-soluble sizing agent having a slow dissolution rate may be added to the sizing agent for the purpose of improving the transfer of the toner and preventing blocking.

It is preferable to use amorphous silica fine powder, because addition of a small amount of inorganic fine powder can prevent stickiness under high humidity and has a great effect of improving the adhesion of toner during copying. Amorphous silica fine powder is referred to as anhydrous silicic acid produced by a dry method, hydrous silicic acid produced by a wet method, white carbon, or amorphous silica, and has an average particle diameter of 4 μm or less. Average particle size is 4
When it exceeds μm, the fluidity of the coating liquid is deteriorated, it is difficult to obtain a uniform coating surface, and the gloss of the transferred image is lowered.
The optimum amount of addition is 1 to 15 parts by weight with respect to 100 parts by weight of dextrin. If it is 1 part by weight or less, the above-mentioned properties cannot be imparted, and if it is used in an amount of 15 parts by weight or more, the transfer to the transfer target becomes insufficient and the gloss of the transferred image disappears. When mixing a water-soluble sizing agent having a slow dissolution rate, 30 parts of a water-soluble sizing agent having a slower dissolution rate than dextrin is added to 100 parts by weight of dextrin.
Mixing up to 100 parts by weight has a great effect.

In the present invention, it is further necessary to provide the curl prevention layer 4 on the back surface of the base paper 1. For the curl prevention layer, any of the above water-soluble sizing agents can be used, and inorganic fine powder may be added thereto. Anti-curl layer is usually 0.5-3g
/ M ^{2 is} provided. Further, if necessary, super calendering treatment can be performed for the purpose of improving the surface smoothness.

Next, an example of transferring an image by using the image transfer paper of the present invention will be described. First, an electrostatic copy machine is used to form an image with toner (a reverse image is formed)
Is copied onto the water-soluble sizing agent layer 3 having a high rewet dissolution rate on the transfer paper. Next, the transfer paper is immersed in the active liquid. The composition of the active liquid varies depending on the type of resin to be activated, but benzyl alcohol: ethyl alcohol: water = 20: 60: 20.
A mixed solution of is a typical formulation example. In this step, the thermoplastic resin that constitutes the toner swells or dissolves and is activated and becomes adhesive. The transfer paper is taken out, attached to a predetermined position on the transfer target (metal plate, etc.), and the back surface of the transfer paper is rubbed with a squeegee to push out the excess active liquid. The toner image is attached to the surface of the transferred material. After that, water or warm water is dipped in the cloth to wet the back surface of the transfer paper to dissolve the water-soluble sizing agent layer 3 having a fast rewet dissolution rate, and when the transfer paper starts to slide, it is peeled off. Finally, the water-soluble sizing agent around the transferred image (which looks like a normal image from the surface) is washed off with water.

[0015]

【Example】

Example. 1 100 parts of LBKP wood pulp was mixed with 550 ml of C.I. S. After adding 1 part by weight (dry weight part, hereinafter the same) of a wet paper strength enhancer (trade name: Epinox P-130, manufactured by Dick Hercules Co., Ltd.) to the slurry beaten to F, it was used in a Fourdrinier paper machine according to a conventional method. Papermaking was performed to obtain a base paper having a basis weight of 50 g / m ² . Then, using a roll coater, a 3% solution of potato starch was applied at 1 g / m ² (dry weight, the same applies below) to provide a water-soluble paste layer having a slow rewet dissolution rate. Next, dissolve dextrin (manufactured by Matsutani Chemical Co., Ltd.) in water (40% concentration)
Then, while maintaining the liquid temperature at 50 ° C., a coating amount of 5 g / m ^{2 and} a water-soluble sizing agent layer having a fast rewet dissolution rate were provided. Further, a 10% aqueous solution of oxidized starch (same as above) was coated on the back surface of the base paper to provide a curl prevention layer having a coating amount of 0.5 g / m ² . Then a calendar was used to improve the smoothness of the surface. Thus basis weight 5
A transfer paper of 6.5 g / m ² and a thickness of 61 μm was obtained.

Example. 2 A base paper having a basis weight of 70 g / m ² was obtained with the same stock composition as in Example 1. Then, using a roll coater, 3 of potato starch
% Solution was applied at ² g / m ² to provide a water-soluble sizing agent layer having a slow rewet dissolution rate. Then, 12 g / m ^{2 of} a mixed solution (40% concentration) of 50 parts by weight of dextrin (the same as above) and 5 parts by weight of amorphous silica fine powder having an average particle diameter of 2.5 μm (trade name Mizukasil P802, manufactured by Mizusawa Chemical Industry Co., Ltd.). It was provided by coating. Further, a 10% aqueous solution of oxidized starch (same as above) was coated on the back surface of the base paper to provide a curl prevention layer having a coating amount of 1 g / m ² . Then a calendar was used to improve the smoothness of the surface. Thus, a transfer paper having a basis weight of 85 g / m ² and a thickness of 95 μm was obtained.

Example. 3 A transfer paper having the same structure as in Example 2 except that only the water-soluble sizing agent layer having a high rewet dissolution rate was changed was obtained. That is, 50 parts by weight of dextrin (same as above) and oxidized starch (trade name SK-1
00, manufactured by Nihon Cornstarch Co., Ltd.) 50 parts by weight are mixed and dissolved in water (40% concentration), and the coating amount is 12 g / m ^{2 and} the re-wetting dissolution rate is fast while maintaining the liquid temperature at 50 ° C. Layers were provided.

Example. 4 A base paper having a basis weight of 120 g / m ² was obtained with the same stock composition as in Example 1. Then, 5 g / m ² of a 3% solution of potato starch was applied using a roll coater to provide a water-soluble paste layer having a slow rewet dissolution rate. Then, dextrin (same as above) was dissolved in water (40% concentration), and a water-soluble sizing agent layer having a high rewet dissolution rate with a coating amount of 15 g / m ² was provided while maintaining the liquid temperature at 50 ° C. Further, a 10% aqueous solution of oxidized starch (same as above) was coated on the back surface of the base paper to provide a curl prevention layer having a coating amount of 3 g / m ² . Then a calendar was used to improve the smoothness of the surface.
Thus, a transfer paper having a basis weight of 148 g / m ² and a thickness of 158 μm was obtained.

Comparative Example. 1 A base paper having a basis weight of 130 g / m ² was obtained with the same stock material formulation as in Example 1. Then, a roll coater was used to coat a 3% aqueous solution of esterified starch (trade name: Esterin F, manufactured by Matsutani Chemical Industry Co., Ltd.) to provide a lower layer having a coating amount of 3 g / m ² . Furthermore, 22 g / m ^{2 of} dextrin was applied, and the basis weight was 155 g.
A transfer paper for ceramics having a thickness of / m ² and a thickness of 180 μm was obtained. This is a typical construction of transfer paper for ceramics.

Comparative Example. 2 A base paper having a basis weight of 70 g / m ² was obtained with the same paper material prescription as in Example 1. Then, a 3% solution of potato starch was applied at 14 g / m ² to provide only a water-soluble paste layer having a slow rewet dissolution rate.
Further, a 10% aqueous solution of oxidized starch (same as above) was coated on the back surface of the base paper to provide a curl prevention layer having a coating amount of 0.5 g / m ² .

Comparative Example. 3 A base paper having a basis weight of 70 g / m ² was obtained with the same stock material formulation as in Example 1. Next, dissolve the dextrin (same as above) in water (40
%), And coating was performed while maintaining the liquid temperature at 50 ° C., and only a water-soluble sizing agent layer having a high rewetting dissolution rate with a coating amount of 14 g / m ² was provided. Further, a 10% aqueous solution of oxidized starch (same as above) was coated on the back surface of the base paper to provide a curl prevention layer having a coating amount of 0.5 g / m ² .

The transfer paper thus produced was evaluated. Various performances during electrostatic copying were evaluated using a color copying machine (trade name: Pixel PKEL500) manufactured by Canon Inc. This copying machine is of a type that sequentially develops with four color toners of cyan, yellow, magenta, and black. The evaluation results are shown in Table 1. Evaluation was carried out by the 5-point method. Three
The points above are the practical passing points.

[Table 1]

[0023]

The image transfer paper of the present invention is constructed as described above, and has the following remarkable effects. Adhesion of toner is good without paper jams or floating inside the copier. Does not cause stickiness or curl due to changes in humidity. Moreover, a plurality of transfer sheets are not fed at one time. You can activate the toner uniformly in a short time,
Good transferability of toner to transferred material. The strength of the wet paper is strong, and the paper will not be damaged or scraped even if it is rubbed with a squeegee. It can be used not only for transfer of electrostatically copied images but also for transfer of printed images. That is, it can also be suitably used in a method of printing an image on the image transfer paper of the present invention by screen printing or the like, immersing it in an active liquid to activate the resin constituting the ink, and transferring the image to a transfer target.

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view of an image transfer sheet of the present invention.

[Explanation of symbols]

 1 This is the base paper. 2 A water-soluble sizing agent layer having a slow rewet dissolution rate. 3 A water-soluble sizing agent layer having a fast rewet dissolution rate. 4 A curl prevention layer.

Claims (3)

[Claims] 1. A base paper 1 is sequentially provided with a water-soluble sizing agent layer 2 having a slow rewetting and dissolution rate and a water-soluble sizing agent layer 3 having a fast re-wetting and dissolution rate, and a curl prevention layer 4 is further provided on a back surface thereof. A transfer paper for images, which is characterized in that 2. The water-soluble sizing agent layer 3 having a high rewet dissolution rate has 1 to 15 parts by weight of amorphous silica fine powder added to 100 parts by weight of dextrin. Image transfer paper. 3. The water-soluble sizing agent layer 3 having a fast rewetting dissolution rate is a mixture of 30 to 100 parts by weight of a water-soluble sizing agent having a slower dissolution rate than dextrin, relative to 100 parts by weight of dextrin. The image transfer paper according to claim 1.