JP2003183997A - Transparent coated paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a transparent coated paper having high transparency, keeping the transparency for a long period, and hardly emitting smell, and further to provide the transparent coated paper coated hardly causing blotting. <P>SOLUTION: This method for producing the transparent processed paper comprises coating varnish in the whole or partial surface of an absorptive paper to impregnate the paper therewith, and curing and drying the varnish. The varnish to be coated is a non-solvent type ultraviolet-curable composition containing a photopolymerizable vinyl oligomer and a photopolymerizable vinyl monomer, and has 100-500 mPa-s viscosity (at 25°C). The paper impregnated with the varnish is irradiated with far infrared rays after the impregnation and before the irradiation with ultraviolet rays. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a transparent processed paper, particularly a transparent processed paper suitable for a gravure printing method, a flexo printing method, a roll coater printing method and a curtain spray method, and a method for manufacturing the same. Transparent processed paper.

[0002]

2. Description of the Related Art Conventionally, as a method for transparently processing paper,
For example, (1) a method in which an opening corresponding to a window is provided in a part of paper to form an envelope, and a transparent film is attached to the opening, (2)
A mixture of a heat-melting wax and a thermoplastic resin melted in an organic solvent such as toluene was applied to the entire surface or a part of the absorbent paper, and heat treatment was performed to evaporate the organic solvent. A method of solidifying the mixture later, (3)
Instead of the mixture of the heat-fusible waxes and the thermoplastic resin, an ultraviolet curable resin composition is applied to absorbent paper,
After permeating, a method of irradiating with ultraviolet rays and curing to make transparent paper (Japanese Patent Publication No. 50-21561, JP-A-51)
No. 23314, Japanese Patent Laid-Open No. 3-8898, etc.)
Etc. are known.

However, the method (1) has a problem that it takes time to bond the paper and the transparent film together.
Further, when the contents are sealed in the envelope by using the automatic sealing machine, there is a problem that the contents are caught and an accident occurs because there is a step between the film and the paper.

In the method (2), the mixture of the heat-meltable wax and the thermoplastic resin is often solid at room temperature, and it is necessary to melt the mixture before use.
Therefore, the tank containing the mixture and the coating roll have to be heated before coating, and there is a problem that appropriate temperature conditions and coating conditions must be selected. Moreover, when removing the organic solvent, the organic solvent is scattered into the atmosphere. Therefore, a facility for collecting the scattered solvent is required. Also,
After applying the above mixture, at a high temperature (200 ° C.) in order to evaporate the solvent and to melt and solidify the waxes.
(~ 220 ° C) heating furnace is required. Therefore, a long heating furnace and a large amount of heat are required, and the odor of the evaporated solvent becomes a problem. Further, the transparent paper obtained by the method (2) is liable to be broken due to a decrease in transparency with time, yellowing of the paper, and a small elasticity of the paper, and the transparency is deteriorated when broken. There is also the problem of poor quality.

Further, in the method (3), the ultraviolet-curable resin composition used is often liquid. Therefore, it is not necessary to apply the composition by heating. However, in order to penetrate the above composition into paper, toluene,
It is generally used by diluting with a low boiling point organic solvent such as xylene or methyl ethyl ketone to reduce the viscosity. Therefore, it is necessary to remove the organic solvent after permeating the composition with paper. The organic solvent is removed by heating the paper with a heating device such as an infrared heater before irradiating with ultraviolet rays. The heating device in this case does not need to be as large as the heating furnace used in the method (2). However, the scattering of the organic solvent causes problems of air pollution and odor. That is, there is a problem that the advantage of the ultraviolet curable resin composition, which originally does not require the use of a solvent, cannot be utilized.

On the other hand, when the ultraviolet curable resin composition is used, the transparency of the transparent processed paper does not decrease with time. Also,
By selecting an appropriate composition, the yellowing and fragility of the paper can be greatly reduced. Furthermore, by selecting an appropriate polymerization initiator, it is possible to suppress the odor generated during curing. However, when the ultraviolet curable resin is used without using an organic solvent (JP-A-52-512).
79, JP 61-41397, JP 6
No. 3-126997), there is a limit to the ultraviolet curable resin used to reduce the viscosity, and there is a problem that the permeability to paper is poor when the viscosity is high. On the other hand, when the ultraviolet curable resin is used as an aqueous solution (Japanese Patent Laid-Open No. 3-1
46798 gazette) has a problem that the paper is curled, the transparency is lowered, or a heating process is required to evaporate water from the paper.

In order to solve the above problems, the present inventors have proposed an anhydrous composition containing a photopolymerizable vinyl oligomer, a photopolymerizable vinyl monomer, a photopolymerization initiator, a penetrant and a polymerization inhibitor. The water-soluble component in the whole composition is in the range of 50 to 100% and the viscosity is 100 mP.
We have developed a water-soluble UV-curable varnish in the range of a · s (25 ° C) or less. However, in order to identify the customer code through the transparent portion, transparent processed paper having higher transparency is required.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object thereof is a method for producing a transparent processed paper having high transparency, capable of maintaining transparency for a long period of time, and producing no odor, and a method thereof. It is to provide a transparent processed paper manufactured by the manufacturing method. Another object of the present invention is to
It is to provide a transparent processed paper with little bleeding.

[0009]

In order to solve the above-mentioned problems, the method for producing a transparent processed paper of the present invention is such that the varnish is applied to the whole or a part of the absorptive paper, the varnish is permeated and then cured and dried. A method for producing a transparent processed paper obtained by the method, wherein the varnish to be applied is a solventless UV-curable composition containing a photopolymerizable vinyl oligomer and a photopolymerizable vinyl monomer, and has a viscosity. 100 mPa · s (2
Greater than 5 ° C. and less than or equal to 500 mPa · s (25 ° C.) and irradiating the varnish with far infrared rays after immersing the varnish in the paper and before irradiating with ultraviolet rays. Is characterized by.

According to the above-mentioned constitution, since it is a solventless UV-curable composition containing a photopolymerizable vinyl oligomer and a photopolymerizable vinyl monomer, a heating step for removing the solvent is not required.

Conventionally, the viscosity of the composition has been reduced to improve the penetration of the varnish into the paper. Therefore, in a solventless UV-curable composition containing a photopolymerizable vinyl oligomer and a photopolymerizable vinyl monomer, the content of the photopolymerizable vinyl monomer is increased to increase the viscosity to 100 m.
It was set to Pa · s (25 ° C.) or less. However, when the content of the photopolymerizable vinyl monomer is increased, the curing and drying time when the composition is irradiated with ultraviolet rays to be cured and dried becomes longer. Therefore, bleeding occurs at the edge of the area where the composition is applied to the paper, and the boundary between the transparent portion and the opaque portion of the paper is not sharp. On the other hand, if the viscosity is too low, the effect of winding up the varnish between the rolls from the varnish tank to the plate decreases when the varnish is applied by flexographic printing or gravure printing, and the desired film thickness (30 μm) is reduced.
m-40 μm) cannot be obtained. Therefore, a sufficient amount of varnish cannot be applied to the paper and sufficient transparency cannot be obtained.

The present inventors have proposed a solvent-free UV-curable composition containing a photopolymerizable vinyl oligomer and a photopolymerizable vinyl monomer and having a viscosity of 100 mPa · s.
It has been found that a varnish having a desired film thickness can be applied by using a varnish in the range of more than (25 ° C) and 500 mPa · s (25 ° C) or less. Further, when the viscosity is in the above range, the penetrability of the varnish into paper decreases. Therefore,
Far-infrared rays are irradiated before irradiating with ultraviolet rays to improve penetration of the varnish into paper. As a result, it is possible to obtain a transparent processed paper having a transparency of 80% or more (opacity of 20% or less), which allows the customer barcode to be identified through the transparent portion. According to the configuration of the present invention, a transparent paper having high transparency can be manufactured without considering the beating degree of the paper.

When the far infrared rays are irradiated, the paper surface temperature is 10
It may be 0 ° C to 160 ° C.

Further, at the above paper surface temperature, the far infrared irradiation time may be 1 to 3 seconds.

The irradiation of far infrared rays may be performed on the surface coated with varnish, or on both the surface coated with varnish and the opposite surface.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The varnish used in the method for producing transparent processed paper according to the present invention is (1) a photopolymerizable vinyl oligomer which is cured by irradiation with ultraviolet rays, and (2) is cured by irradiation with ultraviolet rays. A composition containing a photopolymerizable vinyl monomer, (3) a photopolymerization initiator, (4) a penetrant, and (5) a polymerization inhibitor. In addition to the above composition, it may further contain a photosensitizer, a gelling agent, and the like.

The photopolymerizable vinyl oligomer used is not particularly limited, and known oligoacrylates can be used. Specific examples include epoxy acrylate, epoxidized oil acrylate, urethane acrylate, polyester acrylate, polyether acrylate, and diallyl phthalate resin. Among these oligo acrylates, the viscosity is 1500 mPa · s (25
℃) or less oligo acrylate is preferred, the viscosity is 10
Oligoacrylates of 00 mPa · s (25 ° C.) or less are particularly preferable.

The photopolymerizable vinyl monomer used is not particularly limited, and known photopolymerizable vinyl monomers can be used. Specifically, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate,
Polyethylene glycol # 300 diacrylate, butanediol monoacrylate, morpholine acrylate, N-vinylformamide, nonylphenoxy polyethylene glycol acrylate, tetrahydrofurfuryl methacrylate, lauryl acrylate, stearyl acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate Acrylate, EO-modified trimethylolpropane triacrylate, tripropylene glycol diacrylate and the like can be mentioned. Among these vinyl monomers, the viscosity is 1500 mPa
A vinyl monomer having a viscosity of s (25 ° C) or less is preferable, and a vinyl monomer having a viscosity of 1000 mPa · s (25 ° C) or less is particularly preferable.

The photopolymerization initiator used is not particularly limited, and known photopolymerization initiators can be used. Specifically, acetophenone-based photopolymerization initiators such as diethoxyacetophenone, hydroxyacetophenone and α-aminoacetophenone, benzoisoethyl ether, benzophenone-based photopolymerization initiators such as benzyldimethylketal, and benzophenone-based photopolymerization initiators such as benzophenone. Agents, thioxanthone photopolymerization initiators such as 2,4-diethylthioxanthone, methylphenylglyoxylate, and acylphosphine oxide. These photopolymerization initiators may be used alone or in combination of two or more kinds. The preferred photopolymerization initiator has good compatibility with the photopolymerizable vinyl oligomer and the photopolymerizable vinyl monomer. Hydroxyacetophenone that is liquid at room temperature and acylphosphine oxide melted at 50 ° C. to 60 ° C. is preferable because it has less odor and does not easily turn yellow.

The penetrant used is not particularly limited, and known penetrants can be used. Specifically, polyethylene glycol alkyl ethers such as polyethylene glycol lauryl ether, polyethylene glycol alkyl allyl ethers such as polyethylene glycol octyl phenyl ether, sodium alkylsulfosuccinates such as sodium dioctylsulfosuccinate, perfluoroalkyl EO adducts, etc. Is mentioned.
As these penetrants, those having an excellent ability to lower the surface tension and those having less foaming are preferable.

The polymerization inhibitor is not particularly limited and known ones can be used, and specific examples thereof include hydroquinone, hydroquinone monomethyl ether, mono-t-butylhydroquinone, phenothiazine and catechol.

The amount of each of the above substances in the varnish used for producing the transparent processed paper of the present invention is not particularly limited. However, if the viscosity is higher than 100 mPa · s (25 ° C), 5
From the necessity of not more than 00 mPa · s (25 ° C.), if the proportion of the photopolymerizable vinyl monomer in the varnish is 5% by weight to 60% by weight, more preferably 10% by weight to 50% by weight. Good. When the content of the photopolymerizable vinyl monomer is 5% by weight or less, the penetrability into paper is poor,
The viscosity of the varnish cannot be reduced to 500 mPa · s (25 ° C.) or less. On the other hand, when the content of the photopolymerizable vinyl monomer is 60% by weight or more, the viscosity of the varnish becomes 100%.
Since it cannot be larger than mPa · s (25 ° C.), bleeding occurs in the portion coated with the varnish, which is not preferable. The proportion of the photopolymerizable vinyl oligomer in the varnish may be 40% by weight to 95% by weight, and more preferably 60% by weight to 90% by weight. If the compounding amount of the photopolymerizable vinyl oligomer is 40% by weight or less, the viscosity of the varnish cannot be made higher than 100 mPa · s (25 ° C.), so that bleeding occurs in the portion coated with the varnish.
Not preferable. If the blending amount of the photopolymerizable vinyl oligomer is 95% by weight or more, the penetrability into paper decreases, which is not preferable.

The proportion of the penetrant in the varnish is 0.5.
It may be in the range of 5% by weight to 5% by weight, and in the gravure printing method and the flexographic printing method, 1% by weight to obtain the effect of winding between rolls from the varnish tank to the plate.
More preferably, it is in the range of 3% by weight. The proportion of the photopolymerization initiator in the varnish is 10% by weight or less, and the photopolymerizable oligomer and photopolymerizable monomer to be used may be used in an amount sufficient for curing. The proportion of the polymerization inhibitor in the varnish is in the range of 0.01% by weight to 0.1% by weight with respect to the photopolymerizable oligomer and the photopolymerizable monomer used in consideration of the storage stability of the varnish. I wish I had it. As the photosensitizer, N, N-dimethylethanolamine, methyldiethanolamine, triethanolamine and the like may be used, and as the gelling agent, known materials such as metal chelate, metal soap and organic bentonite may be appropriately used.

The varnish is liquid at room temperature. Therefore, it is not necessary to heat the varnish tank and the application roll before applying the varnish.

The above varnish has a viscosity of 100 mPas.
・ 500 mPa ・ s (25 ° C)
℃) or less. Therefore, the varnish can be applied with a film thickness of 30 μm to 40 μm required for the paper to have sufficient transparency.

Far infrared rays are irradiated on the paper coated with the varnish. Far infrared rays are not used to disperse organic solvents or water. First, by irradiating with far infrared rays, the viscosity of the varnish applied by heat is reduced. As a result, the varnish penetrates deeper into the paper from the coated surface, and transparent processed paper with high transparency is obtained. Further, the far-infrared furnace has a relatively low furnace atmosphere temperature of about 200 ° C. at the maximum, and temperature control is easy. From the viewpoint of reducing the viscosity of the varnish, a general heat treatment method such as a hot-air oven or a near-infrared oven can be used. However, in the hot air oven, there is a problem that the oven length becomes long in order to obtain a desired paper surface temperature of 100 ° C to 160 ° C. On the other hand, in the near infrared furnace, the furnace length becomes short. However, when the temperature of the atmosphere in the furnace becomes 300 ° C. or higher, there is a risk that the paper quality will deteriorate and the paper will burn.

By irradiating far infrared rays, another effect can be obtained. That is, far infrared rays are electromagnetic waves similar to near infrared rays. However, the wavelength of far infrared rays is longer than 4 μm and usually 5 μm or more. The penetration power of far infrared rays increases as the wavelength increases. Theoretically, the penetration force is proportional to the 1/2 power of the wavelength. By irradiating the far infrared rays, the far infrared rays can reach the back of the paper surface, so that the varnish can penetrate deeper into the paper. Therefore, a transparent processed paper having high transparency can be obtained.

As the far infrared furnace used in the method for producing transparent processed paper of the present invention, a known far infrared generator can be used. The paper surface temperature may be in the range of 100 ° C to 160 ° C. The preferred temperature range is workability (irradiation time) depending on paper quality, transparency, and printing speed.
Considering the above, it is preferably in the range of 120 ° C to 140 ° C. The irradiation time is 1 to 3 seconds if the paper surface temperature is within the above range. This is because if the irradiation time is less than 1 second, the desired transparency cannot be obtained, and if it is longer than 3 seconds, the paper deteriorates.

The distance between the far infrared ray generating surface of the far infrared ray generating device and the paper surface may be set so that the paper surface temperature is within the above temperature range. Considering the dance and meandering caused by running the paper, it is about 5 cm.

The far-infrared ray generators may be used alone or in combination of two or more. When two or more units are used in combination, they may be installed in series with respect to the running paper surface and irradiate far infrared rays on the same surface. In this case, the furnace length becomes long. On the other hand, far infrared rays may be emitted from both sides of the paper. Sufficient irradiation can be performed without increasing the furnace length.

FIG. 1 is a diagram for explaining an example of the method for producing transparent processed paper according to the present invention. The absorbent wrapping paper 1 is pulled out by a roll 2. Next, the wrapping paper 1 passes between the ground pattern printing printing plate 4 and the impression cylinder roll 3, and the flexo ink supplied from the flexo ink tank 5 is transferred onto the wrapping paper 1 via the ground pattern printing printing plate 4. Then, the background pattern of the envelope and the window frame of the envelope window are flexographically printed. Next, the wrapping paper 1 passes between the Pramad type printing plate 6 and the impression cylinder roll 13, and the varnish supplied from the varnish tank 7 is flexographically printed in the window frame through the printing plate 6. In addition, in this example, the example of the wrapping paper is shown, but the flexographic printing may be applied to the sheet of paper.

Next, the wrapping paper 1 on which the above varnish is printed is
It is sent to the far-infrared furnace 8 and is irradiated with far-infrared rays by a far-infrared ray irradiation device 9. By irradiating with far infrared rays, the varnish penetrates deeply into the paper. Next, this wrapping paper 1
Is guided to the ultraviolet irradiation device 11 by the roll 10 and irradiated with ultraviolet rays to dry and solidify the varnish to obtain a transparent processed paper. The wrapping paper 1 on which the varnish is dried and solidified is a roll 12
Thus, the envelope is guided to a bag-making machine and an envelope with a transparent window is obtained. Further, not only the flexographic printing method but also the gravure printing method, the roll coater printing method, and the curtain spray printing method can be used to manufacture the transparent processed paper.

The transparent processed paper obtained by the production method of the present invention has excellent transparency. Specifically, it is a transparent processed paper having a transparency of 80% or more. The transparency referred to in the present invention is J
It is obtained from the opacity (%) obtained according to ISP-8138 using the following formula. Transparency (%) = 100% -Opacity (%)

[0034]

EXAMPLES The contents of the present invention will be specifically described below based on examples. The invention is not limited to these examples. In addition, when referring to a part in the following examples,
Means parts by weight. [Varnish (A)] Aliphatic epoxy acrylate 80 parts (manufactured by BASF Ltd., Laromer LR8765) 12 parts tripropylene glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester, APG-200) Irgacure 4265 5 parts ( Ciba-Geigy Co., Ltd., photo-polymerization initiator Irgacure 907 2 parts (Ciba-Geigy Co., Ltd., photo-polymerization initiator) Hydroquinone monomethyl ether 0.05 part (Seiko Chemical Co., Ltd., polymerization inhibitor) Sanmorin OT-70 (Sanyo Kasei Co., Ltd., penetrant) Part 1 Polyflow No. 75 (Kyoeisha Chemical Co., Ltd., wetting agent) 0.25 parts Total 100.3 parts The above-mentioned composition was added to a separable flask at 60 ° C.,
The mixture was kept warm for 30 minutes and stirred to obtain a varnish A of 400 mPa · s (25 ° C.).

[Varnish (B)] Aliphatic epoxy acrylate 50 parts (manufactured by BASF Ltd., Laromer LR8765) Tripropylene glycol diacrylate 41 parts (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester, APG-200) Irgacure 4265 5 parts (manufactured by Ciba Geigy Co., Ltd., photopolymerization initiator) Irgacure 907 3 parts (manufactured by Ciba Geigy Co., Ltd., photopolymerization initiator) Hydroquinone monomethyl ether 0.05 part (manufactured by Seiko Chemical Co., Ltd., polymerization inhibitor) Sanmorin OT-70 (manufactured by Sanyo Kasei Co., Ltd., penetrant) 1 part Polyflow No. 75 (Kyoeisha Chemical Co., Ltd., wetting agent) 0.25 parts Total 100.3 parts The above-mentioned composition was added to a separable flask at 60 ° C.,
After keeping the temperature for 30 minutes and stirring, 103 mPa · s (25 ° C.) of varnish B was obtained.

Example 1 Absorbent paper (recycled paper, manufactured by Chuetsu Pulp Co., Ltd., <62.
5)) was printed with Varnish A at a printing speed of 30 rpm.
Next, a far-infrared irradiation device (ceramic heater, 2 kw, effective length 0.4 m) was placed in series and placed at a distance of 5 cm from the traveling paper surface. Using this apparatus, far infrared rays were irradiated at a paper surface temperature of 140 ° C. and a far infrared irradiation time of 2.9 seconds at the envelope window. Next, ultraviolet irradiation device (high pressure mercury lamp, 6 kW,
120w / cm) 2 units, 1 from both sides of the running paper surface
The varnish A was set at 0 cm, cured and dried, and sent to a bag-making machine to obtain an envelope paper with a window of Example 1.

Example 2 An envelope with a window of Example 2 was obtained in the same manner as in Example 1 except that the printing speed was 45 rpm. The far infrared ray was irradiated at a paper surface temperature of 124 ° C. and the far infrared ray irradiation time of the envelope window portion of 1.94 seconds.

(Example 3) An envelope with a window of Example 3 was obtained in the same manner as in Example 1 except that the printing speed was 50 rpm. The far infrared ray was irradiated at a paper surface temperature of 130 ° C. and a far infrared ray irradiation time of the envelope window portion of 1.75 seconds.

Example 4 An envelope with a window of Example 4 was obtained in the same manner as in Example 1 except that the varnish B was used instead of the varnish A.

(Example 5) Four far infrared ray irradiation devices were used. An envelope with a window of Example 5 was obtained in the same manner as in Example 1 except that two far infrared ray irradiation devices were arranged in parallel on both sides of the paper surface. The far infrared ray was irradiated at a paper surface temperature of 135 ° C. and a far infrared ray irradiation time of 1.03 seconds at the envelope window.

Comparative Example 1 An envelope with a window was prepared under the same conditions as in Example 3 except that the far-infrared ray was not irradiated, and the envelope with a window of Comparative Example 1 was obtained.

Comparative Example 2 An envelope with a window was prepared under the same conditions as in Example 5 except that the printing speed was 180 rpm, and the envelope with a window in Comparative Example 2 was obtained. Note that the paper surface temperature is 120
Far-infrared rays were irradiated at a temperature of 0.48 seconds for irradiation of the envelope window with far-infrared rays.

The envelopes with windows of Examples 1 to 5 and the envelopes with windows of Comparative Examples 1 and 2 were evaluated by the following method.

[Evaluation of Transparency] Opacity (%) was measured by a Hunter reflectometer (opacity meter) according to JIS P-8138. Calculation formula, transparency (%) = 1
The transparency was calculated from 00% -opacity (%).

[Evaluation of yellowing] Transparent paper was irradiated with ultraviolet rays for 40 hours using an Atlas-type fade meter, judged on a blue scale, and classified into 8 levels. 8 is the least yellowing.

Regarding the sharpness of the edge, bleeding within 3 mm from the edge of the area coated with varnish was considered good.

An envelope sheet with a transparent window manufactured by the method of the above-mentioned conventional technique (2) was used as Reference Example 1.

The results are shown in Table 1.

[0049]

[Table 1]

As is clear from Table 1, the envelope with a window produced by the production method of the present invention was excellent in transparency, and the transparency was stably maintained for a long period of time. Moreover, since an ultraviolet curable resin is used, it is difficult to turn yellow. Further, since no solvent was used, the generation of odor was small. In addition, transparent processed paper with little bleeding was obtained.

[0051]

As described above, according to the present invention, there is provided a method for producing a transparent processed paper having high transparency, capable of maintaining transparency for a long period of time, and producing no odor, and a transparent processed paper produced by the manufacturing method. Can be provided. Also,
A transparent processed paper with less bleeding can be provided.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an example of a method for manufacturing transparent processed paper according to the present invention.

[Explanation of symbols]

1 wrapping paper 2, 10, 12 rolls 3,13 impression cylinder roll 4 Printing plate for pattern printing 5 flexo ink tank 6 Pramad type stamp 7 Varnish tank 8 Far infrared furnace 9 Far infrared irradiation device 11 UV irradiation device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ken Tamura             2-831 Kaminishi, Hirano-ku, Osaka-shi, Osaka               Within Osaka Printing Ink Manufacturing Co., Ltd. F-term (reference) 4L055 AG34 AG71 AH50 BE10 EA11                       EA20 EA25 FA12 FA30 GA41

Claims (5)

[Claims] 1. A method for producing a transparent processed paper obtained by applying a varnish to the whole or part of an absorbent paper, allowing the varnish to penetrate, and then curing and drying the varnish, wherein the varnish to be applied is a photopolymerization. Of a solvent-free UV-curable composition containing a polymerizable vinyl oligomer and a photopolymerizable vinyl monomer, and having a viscosity of 100 mPa · s (2
Greater than 5 ° C. and less than or equal to 500 mPa · s (25 ° C.), and irradiating the varnish with far infrared rays after immersing the varnish in the paper and before irradiating with ultraviolet rays. A method for producing transparent processed paper, characterized by: 2. The paper surface temperature at the time of irradiating the far infrared rays is
The method for producing a transparent processed paper according to claim 1, wherein the temperature is 100 ° C to 160 ° C. 3. The method for producing a transparent processed paper according to claim 1, wherein the irradiation with the far infrared rays is performed on the surface coated with the varnish or on both the surface coated with the varnish and the surface opposite to the surface coated with the varnish. 4. The method for producing a transparent processed paper according to claim 1, wherein a heat treatment is not required at the time of coating. 5. A transparent processed paper obtained by applying a varnish to the whole or part of an absorbent paper, allowing it to penetrate, and then curing and drying the varnish, wherein the varnish to be applied is a photopolymerizable vinyl oligomer. And a photopolymerizable vinyl monomer, and a solventless UV-curable composition having a viscosity of 100 mPa · s (2
It is in the range of more than 5 ° C. and less than 500 mPa · s (25 ° C.), and the transparency of the transparent processed paper is 80% or more.