JPH08164589A - Strongly glossy synthetic paper - Google Patents

Abstract

PURPOSE: To provide strongly glossy synthetic paper having good glossy feeling, printability, strength, etc. CONSTITUTION: A coating layer of an electron beam setting resin composition is formed on a synthetic paper sheet, and a drum cast method or a film cast method is used in setting by electron beam radiation. The image visibility (image clarity) of the coating layer (strongly glossy layer) measured on the basis of JIS K7105 using an optical comb of 1.0mm is 40% or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a recording paper, an adhesive paper base,
The present invention relates to a synthetic paper with high gloss used for packaging materials, printing, etc.

[0002]

2. Description of the Related Art In recent years, synthetic paper has characteristics of plastic film such as good water resistance, dimensional stability, weather resistance, dust resistance, and moisture resistance, and high printing effect and good writability. Since it has the advantages of conventional paper such as adhesive paper (label, sticker), clean room paper (memo,
It is used in many fields such as notebooks, slips, commercial art printing (calendars, posters), packages, envelopes for bags, maps, and supports for electrostatic recording paper for CAD / CAM.

Synthetic paper, for example, has a large number of microvoids (holes) to diffusely reflect light to give white opacity, thereby exhibiting printability and writability, and it has been difficult to provide a glossy surface. . However, in recent years, especially in the field of labels and commercial art printing, synthetic papers with high gloss have been demanded.

However, even if an attempt is made to provide a glossy synthetic paper with an ultraviolet-curable resin layer or a method of applying a water-based paint to give a glossy feeling, satisfactory gloss is not obtained by these methods. Is the current situation.

In order to improve the glossiness of synthetic paper,
Even if the water-based or oil-based thermosetting resin is applied, it is necessary to heat the water and the solvent to evaporate and dry or accelerate the curing, and there is a problem that the heating causes the synthetic paper itself to shrink.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide a synthetic paper having printability and high gloss.

[0007]

The present invention includes the following aspects. [1] An electron beam curable resin-containing layer is provided between the synthetic paper support and a molding surface having a smooth surface, and the layer is cured by electron beam irradiation from the synthetic paper support side or the molding surface side, and the cured layer. A strong gloss synthetic paper having an image sharpness (JIS K7105) of 40% or more measured by peeling the sheet provided on the synthetic paper support from the molding surface and using an optical comb of 1 mm on the surface of the cured layer.

[2] The strong-gloss synthetic paper according to [1], wherein the center line average roughness (JIS B 0601) of the synthetic paper support is 1.0 μm or less.

[3] The strong-gloss synthetic paper according to [2], wherein the center line average roughness (JIS B 0601) of the synthetic paper support is 0.6 μm or less.

[4] The cured layer has a total solid content of 5 to 5.
The strong gloss synthetic paper according to [1], which contains 60% by weight of a pigment.

[5] The high-gloss synthetic paper according to [1], wherein the molding surface is a film or a metal drum.

[6] The high-gloss synthetic paper according to [1], wherein the cured layer contains titanium dioxide.

[0013]

In the present invention, the image sharpness (image clarity) of the layer obtained by curing the electron beam curable resin-containing layer, which is measured by using a 1 mm optical comb according to JIS K7105, is 40% by adjusting each condition. It should be above, preferably 60%
Adjust as above. There is no particular upper limit to the image clarity, but it is up to about 98% in the usual production method. If there is a difference between the measured values of the vertical and horizontal values of the sample, both are preferably 40% or more.

As a result, the smoothness of the surface is excellent, and the glossiness before and after printing is far better than that of ordinary cast coated paper (where a water-based coating layer is provided on the paper support using a high temperature cast drum). Excellent synthetic paper with high gloss can be obtained. The image sharpness is obtained by measuring the light reflected on the sample through a moving optical comb using an image sharpness measuring device and calculating it, and indicates the degree of sharpness of the reflected image.

The high-gloss synthetic paper of the present invention comprises an electron beam-curable resin-containing layer provided on a synthetic paper support. This layer is formed by a film casting method by utilizing the molding surface under electron beam irradiation. Alternatively, it is formed by a drum casting method using a metal drum having a mirror surface.

In order to form a layer obtained by curing the electron beam curable resin-containing layer (hereinafter abbreviated as a strong gloss layer or a cured layer), the center line average roughness (JIS B0601) of the support is 1.0 μm or less. A synthetic paper support is preferable, and more preferably 0.6 μm or less. If this value is large, air may be entrained during casting and a large number of pits may occur.
In order to reduce the number of pits, a large amount of the electron beam curable resin-containing coating liquid to be applied is required, which is very expensive.

There is no particular lower limit to the center line average roughness of the synthetic paper as the support (synthetic paper support or simply abbreviated as synthetic paper), but if it is extremely smooth, it adheres to the molding surface and causes blocking, so the paper is passed. Can be difficult. Therefore, the center line average roughness is more preferably 0.1 μm or more, and most preferably 0.2 μm or more within the above range.

The method for producing the synthetic paper used in the present invention is not particularly limited. For example, as synthetic paper,
Examples thereof include a film method synthetic paper by an internal paper making method (Yupo made by Oji Oka Kasei Synthetic paper), a film method synthetic paper by a surface coating method (Peach coat made by Nisshinbo Co., Ltd.) and the like. The film-type synthetic paper by the surface coating method is one in which a porous surface layer containing a pigment and a filler is formed by coating on the surface of a synthetic resin film of polystyrene, vinyl chloride, polypropylene, polyester or the like.

An example of the film-type synthetic paper by the internal paper-making method is one having a single-layer or multi-layer structure, which usually has a layer containing fine pores. The synthetic paper having a laminated structure is obtained, for example, as follows. First, an inorganic pigment is added to and mixed with a thermoplastic resin, melt-kneaded with an extruder, and then extruded through a die slit to form a film. When this is uniaxially or biaxially stretched, many microvoids (holes) are generated inside.

A large number of microvoids generated in the stretching step diffusely reflect light to make it white and opaque, and impart paper-like characteristics such as printability and writability.

A uniaxially stretched sheet may be laminated on both sides of the biaxially stretched sheet. Examples of the inorganic pigment include calcium carbonate, calcined clay, diatomaceous earth, talc, titanium oxide, barium sulfate, ammonium sulfate, silica and the like.

Examples of the resin include polyolefin, polyamide, polyester and polyvinyl chloride. Polyolefin such as polyethylene, polypropylene, or a copolymer thereof is preferable because of its good film-forming property.
In the present invention, it is preferable to appropriately select the particle size and content of the pigment of the synthetic paper as the support and the resin so that the image clarity is 40% or more.

By the way, when a paper base material such as coated paper, art paper, and high-quality paper is irradiated with an electron beam of about 2 Mrad or more, cellulose is cut and paper strength such as tensile strength and folding endurance is remarkably lowered. Therefore, when the paper provided with the electron beam-cured layer is used as a packaging material, it has a drawback that it is easily broken or broken. However, in the present invention, excellent bending crack resistance and strength are obtained.

In the present invention, the molding surface is used for curing with an electron beam, so that heat is scarcely generated, and the composition is obtained by cooling the molding surface drum itself or the nip roll in the case of film casting. The shrinkage of the paper itself can be prevented.

When forming a cured layer, excellent glossiness can be obtained by utilizing a molding surface such as a film casting method or a drum casting method using a metal drum as described below. (1) A coating solution containing an electron beam curable resin is applied to a synthetic paper support, laminated on the surface of a film or a metal drum, irradiated with an electron beam, cured, and peeled from the molding surface. (2) A coating liquid containing an electron beam curable resin is applied to a film or a metal drum having a molding surface, which is attached to a synthetic paper support, irradiated with an electron beam, cured, and peeled. (3) An electron beam-curable resin-containing coating liquid is applied on a synthetic paper support, while an electron beam-curable resin-containing coating liquid is also applied on the film on the molding surface or the surface of a metal drum, and the substrates are bonded together.
Irradiate with electron beam, cure, and peel. (4) An electron beam-curable resin-containing coating liquid is applied on a synthetic paper support, while an electron beam-curable resin-containing coating liquid is also applied on the film on the molding surface or on the surface of a metal drum, and is irradiated with an electron beam. Then, they are bonded, irradiated with an electron beam by another electron beam irradiation device, cured, and peeled.

In the case of a molded film, the electron beam may be irradiated through the film (irradiation from the molding surface side) or the back surface of the synthetic paper (synthetic paper support). Irradiation from the body side). In the case of a metal drum, the back side of the synthetic paper support is used for irradiation. Although the material shape of the metal drum is not particularly limited, a metal drum having a smooth peripheral surface mirror-finished with stainless steel, copper, chrome or the like is preferable. Further, if necessary, a peeling aid such as silicone oil or wax may be supplied to the surface of the metal cylindrical rotating body in order to facilitate peeling of the cured electron beam curable resin-containing layer (cured layer). it can.

The film used as the material for providing the molding surface is not particularly limited in its material shape, but specifically, a relatively thin film such as paper, plastic, cloth, non-woven fabric, or metal foil such as aluminum foil is preferable. . The thicker it becomes, the less flexible it becomes and the more likely it is to bend during the steps of bonding and peeling. The surface of the sheet material used as the molding surface is preferably a smooth surface. Further, the surface may be supplied with a peeling aid such as silicone or wax in order to facilitate the peeling of the cured resin layer. Furthermore, the film surface may be subjected to an appropriate treatment, for example, a treatment such as a silicon treatment, to facilitate the peeling of the cured resin layer. The film used as the molding surface may be processed into an endless belt and used, or may be used repeatedly.

The surface of the molded film or metal drum is
(JIS B0601 surface roughness) 0.4S or less in the maximum value display of the maximum height (0 μm R _max <= 0.4S <= 0.4 μm
R _max ) is preferable.

The coating amount of the cured layer of the present invention is not particularly limited, but is preferably about 5 to ²⁰ g / m ² . It is more preferably 8 to 15 g / m ² . If the coating amount is small, coating defects may occur, and air may be entrained during casting to cause pits on the surface. Further, if the coating amount is small, the image clarity may decrease. On the other hand, even if the coating amount is extremely large, the values of glossiness and image clarity (image clarity) do not change so much when the amount is a certain amount or more, and there is no merit at all because the cost increases.

In the production method of the present invention, the method for applying the electron beam curable resin-containing coating liquid is not limited, and examples thereof include bar coating method, roll coating method, air doctor coating method, blade coating method, squeeze coating method and air knife. A method such as a coating method, a reverse roll coating method, a gravure coating method, a transfer coating method, a fountain coating method, or a slit die coating method can be used.
Especially when the surface of a metal drum is used as the molding surface, a roll coating method or an offset gravure coating method using a rubber roll is preferable from the viewpoint of not scratching the molding surface, and a non-contact type fountain is also used. A coater or slit die coater method is preferable.

The electron beam irradiation apparatus used in the present invention is not particularly limited in its method, and for example, an electron beam irradiation apparatus such as a van de Graaff scanning method, a double scanning method, and a curtain beam method can be used. Among these, the curtain beam type, which is relatively inexpensive and can obtain a large output, is effectively used. The acceleration voltage at the time of electron beam irradiation is preferably about 100 to 300 KV. The absorbed dose of the electron beam is not particularly limited as long as it can carry out desired curing of the resin, but 0.1
About 6 Mrad is preferable.

The oxygen concentration in the atmosphere during electron beam irradiation is preferably 500 ppm or less. Oxygen concentration is 500ppm
If it exceeds, oxygen acts as an inhibitor of the polymerization reaction and the curing of the resin-containing layer may be insufficient. Further, it is preferable to use an inert gas such as nitrogen gas for the purpose of reducing the oxygen concentration.

Examples of the electron beam curing resin used in the present invention include the following compounds. (1) Aliphatic, alicyclic, and araliphatic acrylate compounds of 1- to 6-valent alcohols and polyalkylene glycols. (2) Acrylic compounds obtained by adding alkylene oxide to aliphatic, alicyclic, and araliphatic mono- to hexavalent alcohols. (3) Polyacryloyl alkyl phosphates. (4) A reaction product of a carboxylic acid, a polyol, and acrylic acid. (5) A reaction product of an isocyanate, a polyol, and acrylic acid. (6) A reaction product of an epoxy compound and acrylic acid. (7) A reaction product of an epoxy compound, a polyol, and acrylic acid. Etc. can be mentioned.

More specifically, as the electron beam curing resin, polyoxyethylene epichlorohydrin-modified bisphenol A diacrylate, dicyclohexyl acrylate, epichlorohydrin-modified polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, hydroxypivalate ester neo. Pentyl glycol diacrylate, nonylphenoxy polyethylene glycol acrylate, ethylene oxide modified phenoxyphosphoric acid acrylate, ethylene oxide modified phthalic acid acrylate, polybutadiene acrylate,
Caprolactan-modified tetrahydrofurfuryl acrylate, tris (acryloxyethyl) isocyanurate,
Trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, polyethylene glycol diacrylate,
Examples thereof include 1,4-butadienediol diacrylate, neopentyl glycol diacrylate, and neopentyl glycol-modified trimethylolpropane diacrylate.

The present invention may use these resins alone or in combination with some of these resins.

The resin-containing layer of the present invention contains an electron beam curable resin (unsaturated organic compound curable by electron beam), preferably for the purpose of improving the writability and whiteness and obtaining further excellent printability. Contains a white pigment. In addition, other additives may be contained if necessary. Examples of white pigments used for the purpose of improving the writability and whiteness of the cured layer of the present invention include titanium dioxide (anatase type, rutile type), zinc oxide, barium sulfate, calcium carbonate, aluminum oxide, and magnesium oxide. It can be illustrated. Among them, titanium dioxide is particularly preferable because it has excellent whiteness.

The particle size of the pigment is preferably about 0.05 to 0.5 μm. The content of the white pigment is preferably 5 to 60% by weight of the total solid content of the cured layer, and the content is 10 to 50%.
More preferably, it is wt%. However, if the content is large, the flexibility of the obtained cured layer is lowered, and film cracking may occur. In addition, the fluidity of the paint may decrease.

In order to disperse the white pigment in the above electron beam curable resin, it is possible to use a three-roll mill, two-roll mill, cowles dissolver, homomixer, sand grinder, ultrasonic disperser and the like. it can.

[0039]

EXAMPLES The present invention will be described in more detail with reference to the following examples. However, these do not limit the scope of the present invention.
In addition, "part" in the examples represents "part by weight" unless otherwise specified.

Example 1 The following components were mixed and dispersed for 1 hour with a paint conditioner to prepare an electron beam curable resin-containing coating liquid. Urethane acrylate oligomer (trademark: Beamset 505B, Arakawa Chemical Industries) 50 parts, EO-modified trimethylolpropane triacrylate (trademark: Sartomer SR-454, Sartomer) 20 parts, morpholine acrylate 30 parts, titanium dioxide (trademark: A220) , Ishihara Sangyo, particle size 0.2 μm) 40 parts.

The above coating solution is a synthetic paper (trade name: YUPO FPG-95, thickness: 95 μm, center line average roughness: 0.519 μm, composed mainly of polypropylene and calcium carbonate, manufactured by Oji Yuka Synthetic Paper. And three layers of paper-like layers on both sides,
The base layer is stretched in both the vertical and horizontal directions, and the paper-like layer is stretched only in the horizontal direction. ) 1 surface after surface activation treatment by corona discharge, coated with a reverse roll coater to 10 g / m ^2, and used as a molding surface. A smooth surface (maximum maximum height 0 1 S) with a thickness of 75μ PET film and a guide roll (nip roll).
Irradiate under the conditions of 00KV and a dose of 3Mrad (that is, electron beam P
Irradiate through the ET film), cure the coating layer,
Then, it peeled through the guide roll (release roll) and the sample was produced. Image clarity, glossiness and pits were evaluated using this sample and are shown in Table 1.

Example 2 A reverse roll coater was coated with the same coating solution containing electron beam curable resin as in Example 1 on a chrome-plated mirror-finished metal drum surface (maximum maximum height 0.2 S). The coating amount was 12 g / m ² and the corona treatment was performed on the drum through the nip roll. Synthetic paper made by Oji Yuka Synthetic Paper (trade name: YUPO FPG-95, thickness 95μm, centerline average roughness 0.519μm) were pasted together and cast, and then an accelerating voltage of 300KV and a dose of 3Mrad by an electron beam irradiation device
Under the conditions of (that is, the electron beam is from the back of the synthetic paper,
(Synthetic paper is passed through for irradiation), the coating layer was cured, and then peeled through a guide roll (release roll) to prepare a sample.

Using this sample, image sharpness, glossiness and pits were evaluated, and the results are shown in Table 1.

Example 3 YUPO luster grade product (trade name: YUPO G
FG-95, thickness 95μm, center line average roughness 0.203μm, YUPO F
An electron beam-curable resin-containing layer was provided on PG-95 (one surface of which was smoothed) in the same manner as in Example 1.

Example 4 45 parts of polypropylene (MI = 2.0) and 55 parts of calcium carbonate (average particle size 1.9 μ) were mixed with a Henschel mixer, melt-kneaded with a Banbury mixer, and extrusion-molded to a thickness of 200 μ. Got a sheet of. This sheet was uniaxially stretched 6 times by a roll stretching method to obtain a porous sheet having a thickness of 90 μm. The center line average roughness of the obtained sheet is 1.18.
μm. A coating liquid containing an electron beam curable resin was applied onto this sheet so as to have a concentration of 10 g / m ² , and the same operation as in Example 1 was performed to prepare a sample.

Using this sample, the image clarity, glossiness and pits were evaluated by the following methods. The evaluation results are shown in Table 1.

Comparative Example 1 The same electron beam curable resin-containing coating solution as in Example 1 was applied to a synthetic paper (trade name: YUPO FPG-95, center line average roughness 0.51).
9 μm) to 15 g / m ^2, and without casting (that is, without passing through the molding surface), electron beam irradiation was performed under the conditions of 175 KV and 3 Mrad to cure, and a sample was prepared.

Using this sample, the image sharpness, glossiness and pits were evaluated by the following methods. The evaluation results are shown in Table 1.

Comparative Example 2 A sample was used as it was without providing the electron beam curable resin-containing layer on the synthetic paper support of Example 1. Using this sample, the image clarity and glossiness were evaluated by the following methods. The evaluation results are shown in Table 1.

Comparative Example 3 Synthetic paper made by Oji Yuka YUPO gloss grade product (trade name: YUPO G
FG-95, thickness 95 μm, center line average roughness 0.203 μm) was used as a sample without providing the electron beam curable resin-containing layer. Using this sample, the image clarity and glossiness were evaluated by the following methods. The evaluation results are shown in Table 1.

Comparative Example 4 An electron beam curable resin-containing layer was provided in the same manner as in Example 2 on woodfree paper (thickness 175 μm, basis weight 180 g / m ² , center line average roughness 1.13 μm). The image clarity and glossiness were evaluated by the following methods, and the results are shown in Table 1.

Centerline average roughness: The surface of the used synthetic paper was measured for centerline average roughness Ra according to JIS B0601 using a surface roughness measuring instrument Surfcorder SE-3AK manufactured by Kosaka Laboratory Ltd. .

Image sharpness (image clarity): An optical comb 1.0 mm with an image sharpness measuring device manufactured by Suga Test Instruments based on JIS K7105.
Was used to measure the image clarity.

Gloss: A 60 degree specular gloss was measured using a Nippon Denshoku gloss meter VGS-1D based on JIS Z8741.

Pit: Stereoscopic microscope (product name: STEREO DYNA SCOP)
E MODEL TS-2: VISION ENGINEERING LTD)
The number of pits per 10 mm ² was evaluated. ◯: Excellent because only 2 or less pits per 10 mm ² were observed. Δ: About 3 to 12 pits are recognized per 10 mm ² . X: There are 13 or more pits per 10 mm ^2, which is a problem in appearance.

Folding resistance: M based on JIS P-8115
The load was measured with an IT type folding endurance tester type A (manufactured by Yoshimitsu Seiki Co., Ltd.) under a load of 1 kg.

[0057]

[Table 1]

[0058]

Industrial Applicability The strong gloss synthetic paper of the present invention is a synthetic paper having excellent printability, a very high glossiness, and excellent strength.

Claims (3)

[Claims] 1. An electron beam curable resin-containing layer is provided between a synthetic paper support and a molding surface having a smooth surface, and the layer is cured by electron beam irradiation from the synthetic paper support side or the molding surface side.
A sheet having the cured layer provided on a synthetic paper support was peeled from the molding surface, and the image clarity (JIS K7105) measured using an optical comb of 1 mm on the surface of the cured layer was 40% or more. paper. 2. A center line average roughness (JIS) of a synthetic paper support.
The high-gloss synthetic paper according to claim 1, wherein B 0601) is 1.0 μm or less. 3. The high gloss synthetic paper according to claim 1, wherein the cured layer contains 5 to 60% by weight of pigment based on the total solid content.