JP2763011B2 - Water resistant paper and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laminated waterproof paper excellent in water resistance, writability, printability, low chargeability, weather resistance, tear strength, dimensional stability, and opacity. .

(Prior Art) A two-layer structure in which a paper sheet is used as a base material layer and the surface thereof is coated with polyethylene containing an inorganic pigment such as titanium dioxide, zinc oxide or zinc sulfide, or an inorganic pigment is not provided between the two layers. A photographic paper support having a three-layer structure in which a polyethylene-containing layer is interposed is known.

In these laminated papers, practicality has been sufficiently imparted even when the resin layer is made opaque 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. It is said that this was solved by having Further, in the above-mentioned photographic paper support, there is also known a support in which a polyethylene layer containing no inorganic pigment is provided between a paper base layer and an inorganic pigment-containing polyethylene layer.

(Problems to be Solved by the Invention) In the above-described photographic paper support, a polyethylene resin layer is laminated on the surface of the paper in order to smooth the photographic paper surface for printing a fine photographic image. As a result of providing the resin layer,
The surface of the support became transparent. Therefore, a white background is formed by including 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. Therefore, the surface roughness is insufficient at a blending amount of about 7% by weight as in a photographic support, and the water-based or oil-based It hinders fixing and drying of printing ink or water-based 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.

The present invention provides, as a first object, a means for solving the above-mentioned problems in the prior art, and, as a second object, titanium dioxide or zinc oxide which is used for opacity in a photographic paper support. Drawback that the high chargeability of the resin layer cannot be reduced even if it is blended in a large amount, that is, continuous automatic printing or static automatic use using many sheets while maintaining such high chargeability. An object of the present invention is to provide a means for solving the problem that, when copying is performed, two or more sheets are fed in a stacked state by a mutual attraction force due to static electricity between the sheets to cause a trouble such as a paper jam. .

(Means for Solving the Problems) As a result of the present inventors' development of a laminated waterproof paper having similar printability and writability while being similar to a laminated paper as an existing photographic paper support, Paper is used as a base layer, and at least one layer of a thermoplastic synthetic resin layer containing no inorganic filler is laminated on the surface thereof, and 20 to 80% by weight is preferably contained in the outermost resin layer corresponding to a printed image or a writing surface. Has found it beneficial to include 30-50% by weight of inorganic filler.

It is practically not easy to mix a resin filler with an inorganic filler in an amount of 20% by weight or more to produce a thin layer having a thickness of about 10 μm. This is a technology that can be reached by trial and error. The study by the present inventors has been carried out by repeating a great deal of labor and experiments. In the case of the inorganic filler to be blended in the laminate of the present invention, particularly an improving agent such as calcium carbonate belonging to a relatively large class of the specific surface area, the moisture content before blending is important, and it is possible to regulate this to a specific value or less. desired. Moreover, it is practically almost impossible to shift the once absorbed calcium carbonate or the like to a desirable low moisture content by drying.

In addition, the average particle size of the inorganic additive used is generally 0.01 to 10 μm, preferably 0.1 to 10 μm, from the viewpoint of dispersibility in the resin layer and writability and printability that the inorganic additive imparts to the resin layer. ５5 μm.

In addition, specific attributes of the inorganic additive 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, 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 5-50ml / 100g, preferably 10-40ml / 100g
And it is preferably heavy.

Also, as other effective inorganic fillers, talc, clay, kaolin, barium sulfate, calcium carbonate, calcium silicate, magnesium carbonate, titanium oxide, zinc oxide, magnesium oxide, silicon oxide, diatomaceous earth, magnetic iron oxide, etc. And mixtures thereof.

In addition, a small amount of an 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 filler, a fatty acid salt, a tackifier, a hydrophilized polyolefin wax, or the like is used. It is also possible to add as appropriate or to perform surface treatment of the filler with them.

In order that the inorganic additive can be formed into a thin film having a thickness of 20 μm or less while having a high blending of 20% by weight or more in the resin layer, it is preferable to regulate the moisture content of the inorganic additive to 500 ppm or less.

As the olefin-based thermoplastic resin forming the resin layer for producing the laminated paper of the present invention, an ethylene-based resin, a propylene-based resin, and a polyester resin are preferable.

Here, the olefin-based resin is not limited to a 1-olefin homopolymer, but may be a 1-olefin copolymer.
-A copolymer containing a small amount of another monomer copolymerizable with an olefin, for example, vinyl acetate, ethyl acrylate, methyl methacrylate, or the like may be used. Of course, compositions of different polymers or copolymers are also included.

(1) As the ethylene-based thermoplastic 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 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 propylene-based thermoplastic resin, the melt ± flow rate [MFR (230 ° C.)] is 15 to 50 g / 10 min, and the melt tension (2
30 ° C, extruder orifice L / D = 3.8, extrusion speed 15mm / mi
(n, take-off speed 15 m / min) It is preferably 0.3 to 3.3 g.

As a method for producing the laminated paper of the present invention, a polyolefin resin layer containing no inorganic additive is extruded on at least one surface of a paper base material layer from a T-die film forming machine, and an inorganic additive is additionally formed on the upper surface thereof. A method of laminating and joining three members while extruding the containing polyolefin resin layer from a T-die film forming machine is preferable.

Here, the thickness of each resin layer is usually 3 μm or more, preferably 5 to 10 μm in terms of the content of the inorganic additive, and usually 5 μm or more, preferably 5 to 15 μm in the layer in contact with the paper substrate.

The outermost layer and the resin layer in contact with the paper are materials of the same kind, for example, a combination of low-density ethylene-based resins, high-density ethylene-based resins, propylene-based polymers, and 1-butene-based polymers. Is preferred. Even when these polymers are composed of a composition of two or more kinds of polymers, the composition of the constituent polymers of each layer and the composition ratio of both are the same in both layers.

The laminated waterproof paper of the present invention contains 20 to 80% by weight of an inorganic filler.
Two layers from the T-die while laminating a thermoplastic resin containing a molten state and a thermoplastic resin containing no inorganic filler so that the latter resin is located on the side in contact with the surface of the paper base layer in the T-die. And extruded into a film shape and laminated and bonded to the surface of a paper substrate. Further, paper is used as a base material layer, and at least one layer of an olefin-based resin layer containing no inorganic filler is extruded and laminated in a molten state on the surface thereof, and then 20 to 80% by weight based on the composition on the surface of the resin layer. Moreover, 99-55% by weight of calcium carbonate and titanium oxide 1
A laminated waterproof paper can be manufactured by extruding and laminating at least one layer of an olefin-based resin layer containing an inorganic filler mainly consisting of from about 45% by weight to about 45% by weight in a molten state.

Furthermore, in order to enhance the adhesiveness with 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 to a surface of the resin layer to be laminated which is to be in contact with the paper. When a treatment such as an ozone treatment is performed, it is desirable to impart adhesion between both layers at a low temperature. As a result, it is possible to reduce the frequency of occurrence of eye burrs from the resin, and to prevent deterioration of the resin and reduction in tear strength.

The surface roughness of the waterproof paper obtained by laminating the resin layer on the paper base layer can be changed by appropriately selecting the content of the inorganic additive, the average particle size, and the 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 a 60 ° incident angle 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 additives, writability and printability can be imparted to the resin layer without substantially increasing the chargeability.

In particular, the outermost thermoplastic resin layer contains 30 to 50% by weight of an inorganic filler, and the inorganic filler is mainly composed of calcium carbonate and titanium dioxide, and the ratio of both is 99: 1.
Most desirably, it is about 55:45, preferably 80:20 to 60:40. In the case of such a configuration, the surface resistance value of the outermost layer is 1 × 10 ^{10 to} 9 × 10 ¹⁵ Ω, and both the writability and the 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).

(Examples) Examples of the present invention and comparative examples are shown below.

In addition, about the laminated waterproof paper obtained by the Example and the comparative example, the following physical properties were measured and the result was shown to Tables 1-2.

[Measurement properties] [Measurement method] 1) Thickness: JIS P-8118 2) Opacity: JIS P-8138 3) Water penetration elongation: J.TAPPI No.27 4) Moisture resistance surface wear: JIS P-8136 5) Writing Properties: 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.

6) 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.

7) 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.

(Example 1) Low density polyethylene (MFR 11 g / 10 min, density 0.916 g / c
m ³ , melt tension 1.3 g) 25% by weight in a molten state, and calcium carbonate and titanium oxide in a weight ratio of 60: 4
75% by weight was added and mixed at a ratio of 0. Aside from this,
A low-density polyethylene containing no inorganic filler was prepared, and the resin containing no inorganic filler was used as the lower layer in contact with the paper, and the resin containing the inorganic filler was used as the outermost layer. At a temperature of ℃, thickness 6
Extruded and pressed on both sides of water-resistant copy paper of 0 μm, 500 mm width,
A laminated waterproof paper was obtained.

The water-resistant copy paper used in this example had a basis weight of 48 g /
The high quality paper as the base paper of m ^3, starch / polyvinyl alcohol = 80/20 coating solution of the coating amount 1 to 2 g / m ³ Stöckigt sizing degree of 30 seconds was applied size press in, is a xerographic copy paper .

(Example 2) Polypropylene (MFR25g / 10 min, density 0.91 g / cm ^3, a melt tension 0.5g) as a molten 65% by weight, to which calcium carbonate and titanium oxide in a weight ratio of 95: a ratio of 5 Ide
35% by weight was added and mixed. Separately from this, copolyextrusion T was prepared by preparing a material not containing the above-mentioned inorganic filler of polypropylene, using the resin not containing the inorganic filler as the lower layer in contact with paper, and using the resin containing the inorganic filler as the outermost layer. At the temperature of 290 ° C. from the die, both sides of the same water-resistant copy paper as in Example 1 were extruded and pressed to obtain a laminated water-resistant paper. At the time of co-extrusion, the laminating speed of the molten film is 100 m /
The ozone treatment was performed at an air gap of 130 mm, an ozone concentration of 40 g / m ³ , and an ozone flow rate of 2 m ³ / h.

(Example 3) In Example 2, silica was added in addition to calcium carbonate and titanium oxide, the mixing ratio was 80:10:10, and the content of these inorganic fillers was 45% by weight with respect to 55% by weight of polypropylene. %, And a laminated water-resistant paper was obtained in the same manner except that high-quality paper (basis weight 70 g / m ³ ) was used as the paper base layer.

(Example 4) In Example 3, using calcium carbonate as an inorganic filler, 30% by weight with respect to 70% by weight of polypropylene.
A laminated waterproof paper was obtained in the same manner except that it was blended.

(Comparative Example 1) Low density polyethylene (MFR 11 g / 10 min, density 0.916 g / c
m ^3, laminating a melt tension 1.3 g) extruded at a temperature of 290 ° C. from a T-die, while blowing ozone-containing air to the surface to be bonded to the paper of the molten film, a thickness of 60 [mu] m, on both sides of the waterproof copying paper width 500mm Then, a laminated waterproof paper was obtained. At this time, the conditions for the ozone treatment were as follows: the lamination speed of the molten film was 100 m / min;
The ozone concentration was 30 mm, the ozone concentration was 40 g / m ³ , and the ozone flow rate was 2 m ³ / h.
The water-resistant copy paper used in this example was a high quality paper having a basis weight of 48 g / m ³ as a base paper, and starch / polyvinyl alcohol = 80/2.
This is a xerographic copy paper having a Steckigt sizing degree of 30 seconds in which a coating solution of 0 is applied by size press at an application amount of 1 to 2 g / m ³ .

(Comparative Example 2) Polypropylene (MFR 25 g / 10 min, density 0.91 g / cm ³ , melt tension 0.5 g) was extruded from a T-die at a temperature of 290 ° C, and laminated on both sides of high quality paper while performing ozone treatment.
A laminated waterproof paper was obtained.

(Comparative Examples 3 and 4) The water-resistant copy paper and high-quality paper used in the above examples were used as they were.

(Examples 5, 6, and 7) In Example 2, the mixing ratio of calcium carbonate and titanium oxide used as the inorganic filler was changed variously as shown in Table 2, to obtain water-resistant copy paper.

(Examples 8, 9, 10 and Comparative Examples 5 and 6) In Example 1, the amount of the inorganic filler relative to the low-density polyethylene was varied as shown in Table 2 to obtain water-resistant copy paper.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Mitsuru Konno 5-21-1, Oji, Kita-ku, Tokyo Jujo Paper Co., Ltd. Central Research Laboratory (72) Inventor Michio Takano 2-chome Ariakidai Nishi, Ichihara-shi, Chiba No. 4-1 (56) References JP-A-62-2800 (JP, U) JP-B-49-30446 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) D21H 11 / 00-27/42

Claims (6)

(57) [Claims] 1. A paper base layer, at least one thermoplastic synthetic resin layer containing no inorganic filler is laminated on the surface thereof, and 20 to 80% by weight of an inorganic filler is further added to the surface of the synthetic resin layer. A laminated printable water-resistant paper having good printability and low charge, wherein at least one thermoplastic synthetic resin layer is laminated. 2. An inorganic filler of at least 30 to 50% by weight is contained in at least the outermost thermoplastic synthetic resin layer, and the inorganic filler is mainly composed of calcium carbonate and titanium dioxide. 2. The laminated waterproof paper according to claim 1, wherein the ratio is 80:20 to 60:40. 3. The thermoplastic synthetic resin is a polypropylene resin and has a melt flow rate [MFR (230 ° C.)] of 15 to 50 g / 10 mi.
n, melt tension [230 ℃, L / D = 3.8, extrusion speed 15mm / min,
3. The laminated waterproof paper according to claim 1, wherein a take-up speed is 15 m / min]. 4. The thermoplastic synthetic resin is a polyethylene resin and has a melt flow rate [MFR (190 ° C.)] of 3 to 20 g / 10 mi.
n, melt tension [190 ° C, L / D = 3.8, extrusion speed 15mm / min,
The take-up speed of 15 m / min] is 0.3 to 11 g, and the laminated waterproof paper according to any one of claims 1 to 3 is characterized in that: 5. A molten thermoplastic resin containing 20 to 80% by weight of an inorganic filler and a thermoplastic resin not containing an inorganic filler are mixed in a T-die with the latter resin on the surface of the paper base layer. A method for producing a laminated waterproof paper, comprising: extruding a two-layered film from a T-die while laminating so as to be located on the side to be contacted; 6. A paper base layer, wherein at least one olefin-based resin layer containing no inorganic filler is extruded and laminated in a molten state on the surface thereof, and then the resin layer has a surface of 20 to 80 parts by weight based on the composition. At least one layer of an olefin-based resin layer containing 99 to 55% by weight of calcium carbonate and 1 to 45% by weight of titanium oxide and containing an inorganic filler mainly in a molten state. Paper manufacturing method.