JP2798268B2 - Laminated waterproof paper and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is a laminated water resistant film having excellent water resistance, writability, printability, low chargeability, weather resistance, tear strength, dimensional stability, adhesiveness and opacity. About paper.

[Conventional technology]

A two-layer structure in which a paper sheet is used as a base material layer and this surface is coated with polyethylene containing an inorganic pigment such as titanium dioxide, zinc oxide or zinc sulfide, or an inorganic pigment-free polyethylene layer is interposed between the two layers. A photographic paper support having a three-layer structure is known. (Japanese Patent Publication No. 49-30446) In these laminated papers, the practicality is sufficiently imparted even when the opacity of the resin layer is realized by the inorganic pigment. However, for higher requirements, it is preferable to use three or more layers with a resin layer containing no inorganic pigment interposed between the two layers.

This three-layer laminated paper makes the resin layer opaque due to the inclusion of the inorganic pigment, and interposes a pigment-free resin layer to prevent the adhesive strength between the surface of the paper base layer and the resin layer from being reduced due to the inclusion of the inorganic pigment. Let me. Further, it is known that a sheet formed by co-extruding a composition of polypropylene and maleic anhydride-grafted modified polypropylene with polypropylene has insufficient printability and antistatic properties.
(Problems to be Solved by the Invention) In the above-described photographic paper support, polyethylene is applied to the surface of the paper in order to smooth the surface of the photographic paper for printing fine photographic images. Although the resin layer is laminated, as a result of providing the resin layer,
The surface of the support became transparent. Therefore, a white background is formed by incorporating a pigment in the resin layer so that a clear photographic image can be obtained. That is, in the photographic support, it is desirable to mix the inorganic pigment in the polyethylene resin layer on the surface, but on the other hand, the mixing of the inorganic pigment should not impair the smoothness of the resin layer surface. . From this relationship, the compounding amount is restricted, and practically, the limit is about 7% by weight.

On the other hand, the laminated waterproof paper according to the present invention needs to have printability and writability. For this purpose, the surface of the laminated water-resistant paper must have an appropriate roughness, so that the amount of the inorganic pigment, such as a photographic support, of about 7% by weight results in insufficient surface roughness, Oil-based printing inks,
Or, it hinders fixing and drying of the aqueous ink for writing. Further, even when writing with a ballpoint pen or pencil is attempted, there is a disadvantage that writing is substantially impossible as in the case of the smooth film itself.

For this reason, the present applicant has not only provided means for solving the above-mentioned problems in the prior art, but also incorporated a large amount of titanium dioxide or zinc oxide used for opacity in a photographic paper support into a resin layer. The disadvantages that arise from the inability to reduce the high chargeability of the resin layer, even if continuous automatic printing or electrostatic copying is performed using a large number of sheets while maintaining such high chargeability, By means of mutual attraction caused by static electricity between the sheets, two or more sheets are fed in a stacked state to provide a means for solving a problem causing a trouble such as a paper jam (Japanese Patent Application No. 63-18374). Japanese Patent Application Laid-Open No. 2-333, which is a publication of Japanese Patent Application No. 1-20300, which is a priority application.
No. 99). However, printing paper for book covers and packaging is often required to be free from ink peeling due to friction or scratching of the ink printing area after printing, but there is still an appropriate improvement method for this point. Not found.

[Means for solving the problem]

An object of the present invention is to provide a laminated waterproof paper having printability, writability, and adhesiveness different from those of existing photographic paper supports.

According to the present invention, paper is used as a base material layer, and at least one polyolefin resin layer containing no inorganic filler is provided on the surface thereof.
The polyolefin resin layer further contains maleic acid and / or a derivative thereof graft-modified polyolefin or a blend of the modified polyolefin and polyolefin on the surface of the polyolefin resin layer.
There is provided a laminated waterproof paper in which at least one thermoplastic synthetic resin layer containing 〜80% by weight is laminated.

The graft-modified polyolefin used in the present invention is
Polyethylene, a part or all of polyolefin such as polypropylene is graft-modified,
The monomer to be grafted (hereinafter, referred to as a graft monomer) is maleic acid or a derivative thereof. Derivatives are acid anhydrides, esters, amides, imides, metal salts and the like, for example, maleic anhydride, maleic acid monoethyl ester, maleic acid diethyl ester, maleic acid monoamide, maleic diamide, maleic acid-N-monoethylamide , Maleic acid-N, N-diethylamide, maleic acid-N-monobutylamide, maleic acid-N, N-dibutylamide, maleimide, N-butylmaleimide, N-
Phenylmaleimide, and the like. Of these, maleic anhydride is most preferred.

The grafting amount of the graft monomer to the polyolefin (hereinafter referred to as grafting ratio) is 10 ^-4 to 3% by weight.
It is preferable to prepare it so that it is within the range. The crystalline polyolefin may be partially grafted or entirely grafted, but from industrial production, a modified polyolefin having a graft ratio of 10 ^-2 to 6% by weight is prepared in advance. It is preferable to mix the modified polyolefin with the unmodified polyolefin because the concentration of the graft monomer in the composition can be appropriately adjusted.

As the thermoplastic resin of the present invention, a polyethylene resin and a polypropylene resin are preferable.

Here, the polyolefin is not limited to a homopolymer of 1-olefin, but also a copolymer of 1-olefins, and
It means a composition comprising these homopolymers and / or copolymers.

(1) As the polyethylene resin, a melt flow rate [MFR (190 ° C.)] of 3 to 20 g / 10 min, a melt tension (= melt tension, 190 ° C., L / D of an extruder orifice = 3.
8, extrusion speed 15 mm / min, take-off speed 15 m / min) 0.3 to 11 g are preferred.

(2) As the polypropylene resin, a melt flow rate [MFR (230 ° C.)] of 15 to 50 g / 10 min, a melt tension (230
° C, L / D of extruder orifice = 3.8, extrusion speed 15mm / min,
A take-up speed of 15 m / min) 0.3 to 3.3 is preferred.

The average particle size of the inorganic filler used is generally 0.01 to 10 μm, preferably from the viewpoint of the dispersibility in the resin layer and the writeability and printability of the inorganic filler imparted to the resin layer.
It is about 0.1 to 5 μm.

The content of the inorganic filler in the thermoplastic resin layer containing the inorganic filler is 20 to 80% by weight, preferably 30 to 50% by weight.

Furthermore, specific attributes of the inorganic filler include specific surface area and oil absorption. For example, titanium dioxide is a rutile type having a specific surface area of 1 to 50 m ² / g and an oil absorption of 10 to 50 ml / 100.
g, in calcium carbonate, average particle size 0.5 to 10 μm,
Specific surface area 0.5 to 70 m ² / g, preferably 1 to 30 m ² / g (BET
Method), oil absorption 5-100ml / 100g, preferably 10-70ml / 100
g, preferably heavy.

Other effective inorganic fillers include talc, clay, kaolin, barium sulfate, calcium carbonate, calcium silicate, magnesium carbonate, titanium oxide, zinc oxide, magnesium oxide, silicon oxide, diatomaceous earth, magnetic iron oxide, and the like. , And mixtures thereof.

In addition, a small amount of organic filler such as carbon black, phenol resin, melamine resin, and urea resin may be mixed,
Further, as an auxiliary means for improving the dispersibility of the inorganic filler, a fatty acid salt, a tackifier, a hydrophilized polyolefin wax or the like may be appropriately added, or the inorganic filler may be subjected to a surface treatment.

In order to form a thin film having a thickness of 20 μm or less while having a high content of the inorganic filler in the resin layer of 20% by weight or more, it is preferable to regulate the water content of the inorganic filler to 500 ppm or less.

As a method for producing the laminated paper of the present invention, a polyolefin layer containing no inorganic filler is extruded on at least one surface of a paper base material layer from a T-die film forming machine, and further containing an inorganic filler separately on the upper surface thereof. A method of laminating and bonding three members while extruding a graft-modified polyolefin layer (hereinafter simply referred to as an inorganic filler-containing layer) from a T-die film forming machine is preferable.

Here, the thickness of each resin layer is usually 3 to 20 μm, preferably 5 to 10 μm in the inorganic filler-containing layer, and usually 3 to 25 μm, preferably 5 to 20 μm in the layer in contact with the paper substrate.

The layer thickness of the inorganic filler-containing layer may be larger or smaller than the non-containing layer. For example, the containing layer can be 3 μm, and the non-containing layer can be 17 μm.

The method for producing a laminated paper of the present invention includes a polyolefin resin containing no inorganic filler and an inorganic filler so that the layer of the polyolefin resin containing no inorganic filler is in contact with the surface of the paper base material layer, and The maleic acid and / or its derivative graft-modified polyolefin or a thermoplastic resin containing a blend of the modified polyolefin and the polyolefin is simultaneously extruded from a T-die film forming machine into a two-layer film, and is extruded onto the surface of the paper base material layer. Lamination bonding is also possible. According to this method, even if the inorganic filler layer is thinned, it is easier to perform stable molding while suppressing the occurrence of film breakage and the like. Of course, after laminating a polyolefin resin layer containing no inorganic filler on both sides of the paper base material layer, an inorganic filler-containing resin layer may be further laminated and adhered to the surface of the resin layer.

Furthermore, in order to enhance the adhesion to paper, the surface of the paper base layer before extrusion coating is subjected to a flame (flame) treatment, corona discharge treatment and pre-heat treatment, or is brought into contact with the paper of the resin layer to be laminated. It is desirable to apply a treatment such as ozone treatment to the surface to be treated. As a result, the low-temperature adhesiveness is improved, and it is possible to realize a reduction in the frequency of occurrence of eye burrs from the resin and prevention of deterioration of the resin and a decrease in tear strength.

The surface roughness of the water-resistant paper obtained by laminating the resin layer on the paper base material layer can be changed by appropriately selecting the content of the inorganic filler, the average particle size, and the film thickness of the outermost layer. However, by changing the cooling roll pattern of the laminator and finishing the surface of the product in a matte tone, the pencil writing performance can be improved. Here, “matt tone” means that the gloss at an incident angle of 60 ° is 30% or less. Further, if necessary, an antistatic agent, an ink adhesion improver, an ultraviolet absorber and the like may be blended in at least one resin layer or applied to the outermost layer surface.

In the present invention, by combining specific types of inorganic fillers, it is possible to impart adhesiveness, writability and printability to the resin layer without substantially increasing the chargeability.

In particular, the outermost layer contains 30 to 50% by weight of an inorganic filler,
Further, the inorganic filler is mainly composed of calcium carbonate and titanium dioxide, and it is most desirable that the weight ratio of both is 99: 1 to 55:45, preferably 80:20 to 60:40. In such a configuration, the surface resistance of the outermost layer is 1 × 10 ^{10 to} 9
× 10 ¹⁵ Ω, and both writing properties and printability are extremely good.

The surface resistance of the laminate of the present invention is a value measured at 23 ° C. and 60% relative humidity (RH).

In printing papers for book covers and packaging, it is often required that there be no peeling of the ink when the ink is printed on the ink printing section. The present invention provides a means for improving the chemical adhesion and solving such a problem by blending the graft-modified polyolefin into the resin layer portion.

〔Example〕

 Hereinafter, examples of the present invention and comparative examples are shown.

In addition, the following physical properties were measured for the laminated waterproof papers obtained in the examples and comparative examples, and the results are shown in Table 1.

[Measurement properties] [Measurement method] 1) Thickness: JIS P-8118 2) Writability: A pencil test was performed under a constant pressure using a pencil having a hardness of 2B.

 The criteria are as follows.

 ◎ Can write very well.

 ○ Can write well.

 × I can't write at all.

3) Surface resistance value: Model P-601, VE manufactured by Kawaguchi Electric Co., Ltd.
The measurement was performed in an atmosphere of 23 ° C. × 60% RH using −30.

4) Printability: Roland offset lithographic printing press (202B) was used. The size of the printing paper is 297 x 420mm (A
3) The paper feed speed is 8000 sheets / hour and the atmosphere in the printing room is 2
It was 0 ° C. × 50% RH. The ink used was POP-S from Dainippon Ink and Chemicals, Inc.

5) Adhesion of ink: 24 hours after printing, 24 width
Stick a cellophane tape of mm (made by Nichiban) firmly on the surface on which the ink was printed, and peel off vigorously at once.

At this time, if there is no ink on the cellophane ◎ Somewhat や ○ If it is taken × 6) Drying of the ink: 1 hour after printing, lightly touch the printed surface with your finger and if the ink does not stick to your finger at all ◎ ば Slightly attached ○ 〃 Satisfied × (Example 1) 25% by weight of maleic anhydride graft-modified polyethylene (maleic anhydride content 0.03% by weight, MFR8, density 0.931) 25% by weight
In a molten state, and 75% by weight of calcium carbonate and titanium oxide are added and mixed at a weight ratio of 60:40.
Separately, a low-density polyethylene (MFR 11 g / 10 min, density 0.916 g / cm ³ , melt tension 1.3 g) that does not contain an inorganic filler is prepared, and the resin not containing the inorganic filler is brought into contact with paper. As a lower layer, the above-mentioned resin containing an inorganic filler is used as an outermost layer, and is extruded from both sides of water-resistant copy paper at a temperature of 290 ° C. from a co-extruded T-die and pressed to obtain a laminated water-resistant paper. The water-resistant copy paper used here has a basis weight of 48 g / m ²
Starch / polyvinyl alcohol = high quality paper as base paper
This is a water-resistant copy paper which is a Xerograph copy paper of 30 seconds in Stighit sizing degree obtained by applying a 80/20 coating liquid at a coating amount of 1 to ² g / m ² and size press. Table 1 shows the results.

Example 2 Maleic anhydride graft-modified polypropylene (maleic anhydride content 3.0% by weight, MFR25, density 0.90) 10 parts by weight and polypropylene (MFR 25 g / 10 min, density 0.91 g / cm ³ , melt tension 0.5 g) 90 65 parts by weight of a blend of 65 parts by weight are melted, and calcium carbonate and titanium oxide are added and mixed with 35% by weight at a weight ratio of 100: 0. Separately, a resin not containing the above-mentioned inorganic filler of polypropylene was prepared, and the resin containing no inorganic filler was used as a lower layer in contact with paper, and the above-mentioned resin containing an inorganic filler was used as an outermost layer. Example 1 at a temperature of 290 ° C. from the extruded T-die
Extruded and pressed on both sides of the same water-resistant copy paper as above to obtain a laminated water-resistant paper. At the time of co-extrusion, the lower layer of the molten resin film in contact with the paper, which is to be bonded to the paper, has a laminating speed of 100 m / min, an air gap of 130 mm, an ozone concentration of 40 g / m ³ , and an ozone flow rate of 2 m ³ / m. Ozone treatment is performed under the condition of h.

(Example 3) In Example 2, titanium oxide and silica were added in addition to calcium carbonate, the mixing ratio was 70:20:10, and high-quality paper (basis weight 70 g / m ³ ) was used as a paper base layer. Except for the above, a laminated waterproof paper is obtained in the same manner.

(Example 4) Example 2 was repeated, except that the ratio of calcium carbonate and titanium oxide was set to 95: 5 and co-extrusion and pressure-bonding were performed on only one side of the water-resistant copy paper, not on both sides. Obtain waterproof paper.

(Examples 5 and 6) A laminated waterproof paper is obtained by changing the mixing ratio of calcium carbonate and titanium oxide used as the inorganic filler and the film thickness in Example 2 as shown in Table 1.

────────────────────────────────────────────────── ─── Continuing from the front page (72) Michio Takano 3rd Chigusa Coast, Ichihara-shi, Chiba Mitsui Oil Chemical Industry Co., Ltd. (56) References JP-A-1-181570 (JP, A) 2800 (JP, U) (58) Fields studied (Int. Cl. ⁶ , DB name) D21H 1/02 D21H 21/00-21/42

Claims (6)

(57) [Claims] 1. A paper as a base layer, on the surface of which at least one polyolefin resin layer containing no inorganic filler is laminated, and on the surface of the polyolefin resin layer, maleic acid and / or its derivative graft-modified polyolefin or A laminated waterproof paper comprising at least one thermoplastic synthetic resin layer containing the blend of the modified polyolefin and the polyolefin and containing 20 to 80% by weight of an inorganic filler with respect to the resin. 2. The method according to claim 1, wherein at least the outermost layer of the resin is an inorganic filler
2. The composition according to claim 1, wherein the inorganic filler is mainly composed of calcium carbonate and titanium dioxide, and the ratio of both is 80:20 to 60:40 on a weight basis. Laminated waterproof paper. 3. Maleic acid and / or a derivative thereof graft-modified polyolefin or maleic acid and / or a derivative thereof in a blend of polyolefin and polyolefin.
3. The laminated waterproof paper according to claim 1, wherein the derivative unit content is 10 ^{-4 to} 3% by weight. 4. The laminated waterproof paper according to claim 1, wherein the maleic acid and / or its derivative-modified polyolefin is maleic anhydride-grafted polyethylene or polypropylene. 5. A thermoplastic resin containing maleic acid and / or its derivative graft-modified polyolefin or a blend of the modified polyolefin and polyolefin in a molten state containing 20 to 80% by weight of an inorganic filler, and an inorganic filler. Extruded from the T-die into a two-layer film while laminating a polyolefin resin that does not exist in the T-die so that the latter resin is located on the side in contact with the surface of the paper base material layer, and laminating and bonding to the surface of the paper base material A method for producing a laminated waterproof paper. 6. A paper base layer, wherein at least one layer of a polyolefin resin layer containing no inorganic filler is extruded and laminated in a molten state on the surface thereof, and then the surface of the resin layer is mainly composed of calcium carbonate and titanium oxide. And 20 to 80% by weight of an inorganic filler based on the weight of the resin, the ratio of both being 99: 1 to 55:45 on a weight basis, and maleic acid and / or its derivative graft-modified polyolefin or the modified polyolefin and polyolefin And extruding and laminating in a molten state at least one thermoplastic resin layer containing a blend with the above.