JPH04153394A - Production of coated paper - Google Patents

Abstract

PURPOSE:To obtain coated paper having excellent bond strength by forming a specific coated layer on the surface of a carrier film, bonding paper to the coated layer under pressure and irradiating the bonded material with ionizing radiation while rewinding the material from a winding roll. CONSTITUTION:A coated layer comprising a coating agent composed of a reactive monomer solution containing an ionizing radiation curing resin is formed on the surface of a carrier film. Then paper is bonded to the face of the coated layer, the prepared bonded material consisting of the carrier film and the paper is wound on a winding roll, then the bonded material is irradiated with ionizing radiation while rewinding the bonded material from the winding roll and further the carrier film is released and removed to give the objective coated paper.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing coated paper having a coating layer made of an ionizing radiation-curable resin, and the present invention relates to a method for producing coated paper having a coating layer made of an ionizing radiation-curable resin, and the present invention relates to a method for producing coated paper having a coating layer made of an ionizing radiation-curable resin. A coated paper having a coating layer made of an ionizing radiation-curable resin that faithfully reproduces the state of the coating layer on the surface of the coating layer, and which also has excellent adhesive strength between the paper surface and the coating layer. To provide a method that can be obtained easily and reliably.

[Prior Art] It is widely practiced to form a glossy resin layer on the surface of paper mainly for the purpose of protecting the printed surface or giving a decorative finish.For example, 1) forming a resin layer with a nitrocellulose coating liquid Method of forming a coating layer on the paper surface 2) A method of pasting a transparent film on the paper surface using an adhesive 3) A method of forming a coating layer on the paper surface using a coating agent made of synthetic resin methods, etc. are used.

[Problems to be Solved by the Invention] By the way, in the conventional method for forming a resin coating layer described above, for example, the adhesive strength between the paper surface and the coating layer is insufficient, or the coating layer is It has drawbacks such as insufficient surface smoothness and, furthermore, the need for a long aging process after application of the coating agent, making it impossible to meet quick delivery deadlines.

For this reason, in recent years, a coated paper production method using a coating agent made of an ionizing radiation-curable resin has begun to be used as a method for producing coated paper in which the coating layer is instantly cured by irradiation with ultraviolet rays or electron beams.

This method of manufacturing coated paper using a coating agent made of ionizing radiation-curable resin instantly cures the coating layer by irradiation with ultraviolet rays or electron beams, so it is possible to meet quick delivery times. , because there is no opportunity to bleed the air trapped between the coating agent and the paper, or to improve the wetting between the coating agent and the paper, the coating layer may be insufficiently vented. Poor surface appearance and poor adhesive strength between the coating layer and the paper due to insufficient wetting of the coating agent to the paper occur.

In contrast, the method of the present invention is a method for producing coated paper in which a coating layer is formed using a coating agent made of a curable resin, and there is no need for a long-term curing step of aging. In addition, there is a method for producing coated paper that does not cause problems due to trapped air between the coating layer and the paper, and furthermore, does not cause insufficient wetting between the coating agent and the paper. It provides:

[Means for Solving the Problems] The method for producing coated paper according to the invention in Section 1 includes forming a coating layer on the surface of a carrier film with a coating agent made of a reactive monomer solution containing an ionizing radiation-curable resin. a step of press-bonding paper to the surface of the coating layer; a step of winding up the obtained press-bonded body of the carrier film and paper onto a take-up roll; The method consists of a step of irradiating the crimped body with ionizing radiation, and a step of peeling and removing the carrier film from the irradiated crimped body to obtain coated paper.

The method for producing coated paper according to the invention in Section 2 is the method for producing coated paper according to the invention in Section 1, in which the ionizing radiation-curable resin in the coating agent is composed of a reactive monomer solution containing the ionizing radiation-curable resin. , a polyether polyurethane resin or a polyester polyurethane resin having an acroyl group or a metaacroyl group.

In addition, the method for producing coated paper of the invention of Section 3 is based on the method of producing coated paper of the invention of Section 1 or the second invention, in which a coating agent comprising a reactive monomer solution containing an ionizing radiation curable resin is used. The reactive monomer in is composed of monofunctional or polyfunctional acrylate such as 2-ethylhexyl acrylate, diethyl glycol diacrylate, and trimethylolpropane triacrylate.

Furthermore, the method for producing coated paper according to the invention of Section 4 of the present invention is applicable to the method described in Section 1 of the present invention. Second. Alternatively, in the method for producing coated paper according to the third invention, the coating agent made of a reactive monomer solution containing an ionizing radiation-curable resin may be acetophenone such as jetoxyacetophenone, benzoin alkyl ether such as benzoin isobutyl ether, It contains a photopolymerization initiator selected from benzyl ketals such as benzyl dimethyl ketal, or ketones such as pentuphenone and 2-chlorothioxanthone, and when the ionizing radiation is irradiated with ultraviolet rays, This is done by irradiating from the surface of the carrier film.

Furthermore, the method for manufacturing coated paper according to the invention of Section 5 is the method described in Section 1 of the present invention. Second. Third. Alternatively, in the method for producing coated paper according to the fourth invention, the carrier film to which the coating agent is applied is a biaxially oriented polypropylene film,
It consists of a biaxially stretched polyester film or a biaxially stretched polyamide film.

The method for manufacturing coated paper according to the invention of Section 6 includes, as the carrier film to which the coating agent is applied, in the method for manufacturing coated paper according to the invention of Section 4 or 5 above.
A film having a transmittance of ultraviolet rays of 250 to 400 nm of 20% or more is used.

In the method for producing coated paper of the actual invention having the above configuration, the coach ink agent consisting of a reactive monomer solution containing an ionizing radiation-curable resin that is cured by irradiation with ultraviolet rays or electron beams contains two or more as a resin component. It contains an oligomer having two or more polymerizable functional groups and a reactive monomer, and usually contains 5 to 95% by weight of an oligomer having two or more polymerizable functional groups and 95 to 5% by weight of a reactive monomer. A mixture of is used.

Specific examples of the oligomer having two or more polymerizable functional groups include one type or a mixture of two or more types of oligomers having a (meth)acrylic double bond, such as epoxy (meth)acrylate, polyurethane (meth)acrylate, polyolefin glycol (meth)acrylate 1 polyester (meth)acrylate, etc. are oligomers having a molecular weight of 300 to 6000, preferably 1000 to 3000, and specific examples of reactive monomers include:
These include monofunctional acrylates such as 2-ethylhexyl acrylate and 2-hydroxylpropyl acrylate, and polyfunctional acrylates such as diethylene glycol diacrylate and trimethylolpropane triacrylate-1-.

The epoxy (meth)acrylate includes a reaction product of an epoxy resin having a glycidyl group at the end and (meth)acrylic acid, such as bisphenol-A type epoxy acrylate, and polyurethane (meth)acrylate.
Acrylate is a reaction product of a polyurethane resin having an isocyanate group at the end and a compound having a vinyl group and a hydroxyl group in the molecule, for example, 2-hydroxyethyl (meth)acrylate, and a polyolefin glycol (meth)acrylate. ) For acrylate, for example, di(meth)acrylic acid ester of polyethylene glycol is used, and for polyester (meth)acrylate, phthalic anhydride and diethylene glycol are used. products etc. are used.

Furthermore, it goes without saying that the above-mentioned (meth)acrylic-modified oligomers may be a mixture thereof.

Furthermore, when the curable resin in the coating agent is cured by irradiation with ultraviolet rays, the coating agent usually further contains a general-purpose photopolymerization initiator such as benzoin alkyl ether benzophenone or benzine. 0.2 to 1 per 100 parts by weight of ingredients
Of course, it is added in an amount of 0 parts by weight.

As the photopolymerization initiator, for example, a thioxanthone compound such as 2゜4-diethylthioxanthone, 33
- When a hydrogen abstraction type photopolymerization initiator using a benzophenone compound such as dimethyl-4-methoxy-benzophenone is used, for example, self-cleavage using 1-hydroxycyclohexylphenyl ketone, benzyl dimethyl ketal, etc. When using a type photopolymerization initiator, there is no generation of decomposition products of the photopolymerization initiator, such as cyclohexanone, benzaldehyde, methyl benzoate, etc., which are generated by irradiation with ultraviolet rays, so the generation of odor due to the decomposition products is suppressed. This eliminates the problem of odor generation.

Note that for the photopolymerization initiator, a photosensitizer such as dimethylaminoethanol, triphenylphosphine, N,N-dimethylaniline, dimethylaminobenzoic acid ester, etc. may be used in combination, if necessary. Of course.

The application of the coating agent to the carrier film is
For example, depending on the coating method such as gravure coating, direct coating, reverse roll coating, etc., it is usually 0.5~
It is coated at approximately 30g (resin component)/m2.

For the carrier film in the method for producing coated paper of the present invention, for example, a single layer film or a laminated film made of a biaxially oriented polypropylene film, a biaxially oriented polyester film, a biaxially oriented polyamide film, etc. is used, and the coating in the carrier film is When the coating surface of the coating agent has a mirror surface, a coated paper in which the surface of the coating layer is in a glossy state can be obtained, and the coating surface of the coating agent in the carrier film can be coated with sandblasting, for example.

In the case of a finely uneven surface such as a satin finish, a coated paper exhibiting a matte state can be obtained.

In addition, when the resin component in the coating agent applied to the carrier film is cured by irradiation with ultraviolet rays in a subsequent step, the irradiation with ultraviolet rays must be performed from the surface of the carrier film. In this case, it is preferable to use a carrier film having a UV transmittance of 20% or more in the range of 250 to 400 nm.

The method for producing coated paper of the present invention includes forming an uncured coating layer of the above-mentioned coating agent on the surface of the carrier film, and bringing paper into close contact with the surface of the resulting coating layer. , A crimped body made of carrier film/uncured coated layer 7 paper is formed, and after this is continuously wound up with a take-up roll, the crimped body is unwound from the wind-up roll and the crimped body is The coating layer is cured by irradiating ionizing radiation. In addition, in the coating layer curing process, the type of ionizing radiation corresponding to the composition of the coating agent used to form the coating layer is irradiated. Of course.

When irradiating with ionizing radiation by irradiating ultraviolet rays, it is usually carried out using a high-pressure mercury lamp, a metal halide lamp, or the like.

In this ultraviolet irradiation process, if the ultraviolet ray irradiation rate is too fast, the irradiation dose will be insufficient, resulting in insufficient curing of the coating layer, and if the irradiation rate is too slow, the UV lamp will The heat and ultraviolet rays cause the carrier film to curl due to shrinkage of the film.
It is preferable to irradiate the ultraviolet rays at a rate of about /min.

In addition, when irradiating with ionizing radiation by electron beam irradiation, if the energy dose is too large, the carrier film will deteriorate and coated paper with a homogeneous coating layer cannot be obtained, so the irradiation dose should be 5 Mrad or less. It is better to carry out the

[Example] Hereinafter, the specific structure of the method for producing coated paper of the present invention will be explained with reference to Examples.

Example 1 5 g (resin) of an ultraviolet curable coating agent having the following composition was applied to the specular side of a carrier film made of a biaxially stretched polypropylene film with a thickness of 20 μm and having a specular surface by a gravure roll coating method. Component) The coating was applied to an area of 7 m2 to form a coating layer of ultraviolet curable resin.

UNINITAE" - UV curable resin [polyether-based polyurethane diacrylate prepared by treating the reaction product of polyethylene glycol and 1-lylene diisocyanate with hydroxyethyl acrylate: average molecular weight 3000] ...100 parts by weight of reactive polymer [polyethylene glycol dimethacrylate] 100 parts by weight of photopolymerization initiator [penzoin isopropyl ether] 1 part by weight of photosensitizer [ethyl p-dimethylaminobenzoate] Next, 1 part by weight of Nystert, which has a basis weight of 400
g/m2 of paperboard were brought into contact and brought into close contact, and then crimped with nip rolls, and the resulting crimped body was wound up with a take-up roll.

After completing the winding process of the 2000 m long crimped body using the aforementioned take-up roll, the crimped body was unwound from the take-up roll while being heated with a high-pressure mercury lamp [80w/
cm, lamp length 90 cm, Nippon Battery Co., Ltd.], the distance to the carrier film was 100 cm, and the irradiation rate (line speed during irradiation) l Om/min was used to perform ultraviolet irradiation treatment from the carrier film surface, A laminated sheet of carrier film and paperboard was obtained.

Subsequently, when the carrier film was peeled and removed from the obtained laminated sheet, the carrier film was removed smoothly and a coated paper having a coated layer with excellent gloss was obtained.

Moreover, the adhesive strength between the coating layer and the paperboard in the obtained coated paper was also good.

Example 2 5 g of an electron beam curable coating agent having the composition shown below was applied to the mirror surface side of a carrier film made of a biaxially stretched polypropylene film with a thickness of 20 μm and exhibiting a mirror surface state by a gravure roll coating method. (resin component) was coated at a ratio of 7 m2 to form a coating layer of electron beam curable resin.

U: Electron beam curable resin [Polyether prepared by treating the reaction product of polyethylene glycol and tolylene diisocyanate with hydroxyethyl acrylate. [Cryreto, average molecular weight 3000]...100 parts by weight Reactive monomer [polyethylene glycol dimethacrylate]...100 parts by weight Next, on the surface of the coating layer of the coating agent,
The paperboard of g/m2 was brought into contact and brought into close contact, and then crimped with a counterfeit and nip roll, and the resulting crimped body was wound up with a winding roll.

After the winding process of the 2000 m long crimped body is completed using the aforementioned winding roll, the crimped body is unwound from the winding roll and is exposed to an electron beam irradiation device [200 KV, pilot machine]. , Manufactured by ESI Co., Ltd. Distance from the top to the gear film: 10 cm,
pM firing speed (line speed during irradiation): 100 m
An electron beam irradiation treatment was carried out at an irradiation dose of +21 Jrad/min to obtain a laminated sheet of a carrier film and paperboard.

Subsequently, when the carrier film was peeled and removed from the obtained laminated sheet, the carrier film was removed smoothly and a coated paper having a coated layer with excellent gloss was obtained.

Moreover, the adhesive strength between the coating layer and the paperboard in the obtained coated paper was also good.

Example 3 A coated paper, which is the object product of the present invention, was produced by using a carrier film made of a biaxially stretched polyethylene terephthalate film having a thickness of 25 μm and carrying out the same steps as those in Example 1. Obtained.

When peeling and removing the carrier film from the laminated sheet during the manufacturing process of this coated paper, the carrier film was removed smoothly.

Furthermore, the coating layer of the obtained coated paper had excellent gloss and the adhesive strength between the coating layer and the 41fJ paper was also good.

Comparative Example 1 A paperboard with a basis weight of 400 g/m2 was coated with 5 g (resin component) of the same coating agent as that used in the manufacturing process of the laminate in Example 1 directly by gravure roll coating. It was applied to an area of 7m2, and then a high-pressure mercury lamp [80w/cm, lamp length: 90cm
, Nippon Battery Co., Ltd. 1, the distance to the coating layer surface +
10cm, irradiation speed (line speed during irradiation)・l Q
Coated paper for comparison was obtained by irradiating ultraviolet rays at Q m/min from the surface side of the coating layer.

The coating layer in the obtained coated paper did not have sufficient surface smoothness.

Comparative Example 2 In the coated paper manufacturing process of Example 1, a crimped body of the carrier film and paperboard is obtained by applying pressure and crimping with a nip roll, and then the obtained crimped body is wound onto a take-up roll. Immediately, UV irradiation was performed under the same conditions as the UV irradiation conditions used in Example 1, and then,
A coated paper for comparison was obtained by peeling and removing the carrier film from the obtained laminated sheet.

The resulting coated paper had insufficient gloss and smoothness on the surface of the coating layer due to air entrapment between the carrier film and the coating agent.

[Operations and Effects of the Invention] The method for producing coated paper of the present invention involves forming a coating layer on the surface of a carrier film using a coating agent made of a reactive monomer solution containing an ionizing radiation-curable resin, and then , Press paper onto the surface of the coating layer, take up the obtained crimped body of gear film and paper on a winding spout, and then, while unwinding the crimped body from the winding roll, roll the crimped body onto the crimped body. The desired coated paper is obtained by irradiating ionizing radiation and then peeling and removing the carrier film.

Therefore, in the method for producing coated paper of the present invention, prior to the curing process of the coating layer of the coating agent made of the reactive monomer solution, the carrier film having the coating layer is brought into contact with the surface of the coating layer. The coating layer is cured by irradiating the crimped body with ionizing radiation while unwinding the crimped body with the paper that is being rolled up with a take-up roll. The air previously trapped between the paper and the coating layer is sufficiently vented, and at the same time the wetting between the coating agent and the carrier film is complete.

This eliminates the occurrence of roughness on the surface of the coating layer due to the presence of trapped air between the carrier film and the coating layer, or insufficient wetting of the coating agent to the carrier film. A coated paper is obtained which has a coating layer of good quality in which the state of the surface of the carrier film to which the coating agent is applied is faithfully transferred to the surface.

In addition, the method for producing coated paper of the present invention includes, for example, an icing process in which a coating layer is formed using a coating agent made of a two-component curable resin, or a process in which a transparent film is attached to the paper surface. Since there is no need to go through the process of drying or aging the adhesive, the manufacturing process can be extremely shortened and delivery can be completed within a short period of time.

Furthermore, in the method of the present invention, the coated paper obtained does not have the problem of odor caused by residual solvent, and the viscosity of the coating agent applied to the carrier film can be easily adjusted. Ru.

Claims (1)

[Claims] 1. Forming a coating layer on the surface of the carrier film with a coating agent made of a reactive monomer solution containing an ionizing radiation-curable resin, and then press-bonding paper to the surface of the coating layer, The obtained crimped body of the carrier film and paper is wound up on a take-up roll, and then, while unwinding the crimped body from the take-up roll, the crimped body is irradiated with ionizing radiation, and the carrier film is peeled off. , a method for producing coated paper characterized by removing. 2. The method for producing coated paper according to claim 1, wherein the ionizing radiation-curable resin is a polyether polyurethane resin or a polyester polyurethane resin having an acroyl group or a metaacroyl group. 3. Production of coated paper according to claim 1 or 2, wherein the reactive monomer is a monofunctional or polyfunctional acrylate such as 2-ethylhexyl acrylate, diethylene glycol diacrylate, and trimethylolpropane triacrylate. Method. 4. The coating agent contains a photopolymerization initiator selected from acetophenones, benzoin alkyl ethers, benzyl ketals, or ketones, and the ionizing radiation irradiation step is performed from the carrier film surface. The method for producing coated paper according to claim 1, 2, or 3, which comprises irradiating with ultraviolet rays. 5. The coating according to claim 1, 2, 3, or 4, wherein the carrier film is a biaxially oriented polypropylene film, a biaxially oriented polyester film, or a biaxially oriented polyamide film. Paper manufacturing method. 6. The method for producing coated paper according to claim 4 or 5, wherein the carrier film has an ultraviolet transmittance of 20% or more in the wavelength range of 250 to 400 nm.