JPH0361038A - Laminated sheet and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain a laminated sheet excellent in writing properties, printability and low charge properties by forming a synthetic resin layer containing no inorg. filler to a sheet like support as a lower layer and forming the outermost layer composed of a synthetic resin layer containing specific wt.% of an inorg. filler to the upper surface thereof and making the thickness of the outermost layer less than that of the lower layer. CONSTITUTION:As the olefinic thermoplastic resin forming the sinthetic resin layers of both of the outermost layer containing an inorg. filler and a lower layer containing no inorg. filler, an ethylenic resin is used and, as the inorg. filler, for example, 20-80wt.% of titanium dioxide is contained in the resin layer of the outermost layer and a polyolefin resin layer containing no inorg. filler is subjected to extrusion molding by a T-die film forming machine to be applied to one surface of a sheet-like support such as paper or a synthetic resin film and a polyolefin resin layer containing the inorg. filler is applied to the upper surface thereof while subjected to extrusion molding by the T-die film forming machine to laminate and bond all of them. The thickness of the inorg. filler-containing layer of the outermost layer is set to 1-30mum and that of the layer containing no inorg. filler of the lower layer is set to 5-50mum and the outermost layer is formed so as to be thinner than the lower layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laminated sheet that is excellent in water resistance, military record ↑11, printability, low density, and opacity.

(Prior art) A two-layer structure in which a paper sheet is used as a base 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-free structure is formed between the two layers. A support for photographic paper having a three-layer structure with a polyethylene-containing layer interposed therebetween is known.

In these laminated papers, the fact that the resin layer is made opaque by the use of inorganic pigments is sufficient to make them practical. However, for more advanced requirements, it is preferable to use three or more layers with an inorganic pigment-free resin layer interposed between the two layers.

This three-layer laminated paper has an inorganic pigment that makes the resin layer opaque, and a pigment-free resin layer that is interposed to prevent the adhesive strength between the paper base layer surface and the resin layer from decreasing due to the inorganic pigment content. It is said that the problem was solved by doing so. Furthermore, in the above-mentioned support for photographic paper, one in which a polyethylene layer containing no inorganic pigment is provided between the paper base layer and the inorganic pigment-containing polyethylene layer is also known.

(Problems to be Solved by the Invention) In the above-mentioned support for photographic paper, a polyethylene resin layer is laminated on the surface of the paper in order to smooth the surface of the photographic paper for printing fine photographic images. As a result of providing the resin layer, the surface of the support became transparent.

Therefore, pigments are included in the resin layer to create a white background so that clear photographic images can be obtained. In other words, in photographic supports, it is desirable to incorporate inorganic pigments into the polyethylene resin layer on the surface;
On the other hand, the blending of inorganic pigments must not impair the smoothness of the surface of the resin layer. Due to this relationship, the amount of compounding is restricted, and practically 7% by weight.
It is said that there is a limit to the degree.

In contrast, the laminated waterproof paper according to the present invention has excellent printability and
Must be writable.

For this purpose, the surface of the laminated waterproof paper needs to have an appropriate level of roughness, so if the amount is about 7% by weight, as is the case with photographic supports, the surface roughness will be insufficient, and water-based or oil-based It interferes with the fixing and drying of printing ink or water-based ink for writing.

Furthermore, even if one attempts to write with a ballpoint pen or pencil, the problem arises that it is virtually impossible to write on the film, just as with the smooth film itself.

The present inventors previously proposed in Japanese Patent Application No. 63-18374 a laminated sheet containing 20 to 80% by weight of an inorganic pigment in the outermost layer and having good printability and low chargeability. According to this sheet, the high electrostatic properties of the resin can be significantly reduced, so during continuous automatic printing or electrostatic automatic copying of multiple sheets, two or more sheets may remain overlapped due to the mutual attraction force caused by the static electricity between the sheets. Problems such as paper jams that occur when paper is fed in the wrong condition have been resolved.

However, if a large amount of inorganic filler is added to the sheet, the weight of the sheet will increase.
The present invention enables the inorganic filler to maintain its function without losing its function when the amount of inorganic filler used per sheet area is kept constant.
The aim is to provide a means of using inorganic fillers in the most efficient manner.

(Means for Solving the Problems) The present inventors have developed a laminated sheet that is similar to laminated paper, which is an existing support for photographic paper, but has both printability and writability. 20 to 80% by weight, preferably 30 to 7% by weight in the outermost resin layer corresponding to the drawing or writing surface.
It has been found that it is advantageous to contain 0% by weight of an inorganic filler and to make this outermost layer thinner than the underlying synthetic resin layer. 20% by weight or more of an inorganic filler is blended into the resin layer, and the thickness is 10 μm, particularly preferably 5 μm.
In practice, it is not easy to manufacture a thin layer on the order of m.

This is a technique that can be achieved through various trials and errors. The studies by the present inventors have also involved a great deal of effort and repeated experiments. An inorganic filler blended into the laminate of the present invention,
In particular, for modifiers such as calcium carbonate, which have a relatively large specific surface area, the moisture content before blending is important, and it is desirable to regulate this to a specific value or less. Furthermore, it is virtually impossible to bring calcium carbonate, etc. that have already absorbed moisture to a desirable low moisture content by drying.

In addition, the average particle size of the inorganic filler used is usually 0.01 to 10 μm from the viewpoint of dispersibility in the resin layer and the writability and printability that the inorganic filler imparts to the resin layer.
, preferably about 0.1 to 5 μm.

Further, attributes of the inorganic filler include specific surface area and oil absorption. For example, titanium dioxide is of rutile type and has a specific surface area t~50i/g.

Absorbed Mh amount 10-50ml/1. OOg, calcium carbonate has an average particle diameter of 0.5 to 10 μm, a specific surface area of 0.5 to 70 rd/g, preferably t to 30 bo/g (B
ET method), oil absorption 5-100ml/100g.

It is preferably 1.0 to 70 ml/100 g, and it does not matter whether it is heavy or light, but heavy is particularly preferable.

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

In addition, a small amount of organic filler such as carbon black, phenol resin, melamine resin, or urea resin may be mixed in. Furthermore, fatty acid salts, tackifiers, and hydrophilic agents may be used as auxiliary means to improve the dispersibility of the filler. It is also possible to add polyolefin wax or the like as appropriate, or to perform surface treatment of the filler with them.

In order to be able to form a thin film with a thickness of 2011 m or less even though the inorganic filler has a high content of 20% by weight or more in the resin layer, the moisture content of the inorganic filler must be 500 p.
It is preferable to regulate the amount below pm.

In the laminated sheet of the present invention, the olefinic thermoplastic resin forming the outermost layer containing an inorganic filler and the lower synthetic resin layer not containing an inorganic filler is preferably an ethylene resin, a propylene resin, or a polyester resin.

Here, the olefin resin is not limited to a homopolymer of 1-olefins, but also a copolymer of 1-olefins.
A copolymer containing a small amount of other monomers copolymerizable with the olefin, such as vinyl acetate, ethyl acrylate, methyl methacrylate, etc., may also be used. Of course, compositions of different polymers or copolymers are also included.

(1) The ethylene thermoplastic resin has a melt flow rate [MFR (190°C)] of 33 to 20g10
0m1n, melt tension - melt tension, 190°C1
Extruder orifice L/D = 3.8, extrusion speed 15mm
/min, take-up speed 15m/+n1n) 0.3-11
g is preferred.

(2) The propylene thermoplastic resin has a melt flow rate [MFR (230°C) 11.5 to 50 g/
10 m1n, melt tension (230 °C, L/D of extruder orifice = 3.8, extrusion speed 15 mm / l.

It is preferable that the n1 take-up speed is 15 m/min) 0.3 to 3.3.

In the present invention, a synthetic resin layer containing no inorganic filler constitutes the lower layer, and the lower layer allows the thin outermost layer to contain a large amount of inorganic filler.

Therefore, it is necessary to use a resin for the lower layer that has adhesive properties to both the outermost layer and the support. If the outermost layer is a resin that has adhesiveness to the support, it is sufficient to configure the lower layer with the same resin, but if the adhesiveness is insufficient or absent, graft-modified polyolefin, i.e., polyethylene,
A resin in which part or all of a polyolefin such as polypropylene is graft-modified using maleic acid or its derivatives, or a copolymer of ethylene, (meth)acrylic acid, and (meth)acrylic acid ester is used as appropriate. Therefore, it is necessary to improve its adhesion.

A typical manufacturing method for the laminated sheet of the present invention is to extrude a polyolefin resin layer containing no inorganic filler on at least one side of a sheet-like support using a T-die film forming machine, and then separately add While extruding the inorganic filler-containing polyolefin resin layer from a T-die film forming machine, the three components are laminated and bonded.
At that time, they are laminated so that the outermost resin layer is thinner than the lower synthetic resin layer.

Here, the thickness of each resin layer is usually 1 to 30 μm, preferably 2 to 10 μm, most preferably 5 μm in the outermost inorganic filler-containing layer, and usually 5 to 50 μm in the lower inorganic filler-containing layer. Preferably 5~
The outermost layer is formed to have a thickness of 1.5 μm and is thinner than the lower layer. By concentrating the inorganic filler in the thin outermost layer, it is possible to increase the proportion of inorganic filler present near the surface of the laminated sheet, but on the other hand, the strength of the resin layer is insufficient. The points can be compensated for by the lower layers. A portion of the inorganic filler concentrated in the outermost layer may be exposed on the surface of the outermost layer, and has good effects on writability, printability, and chargeability. In particular, this effect becomes more pronounced when the thickness of the outermost layer and the particle size of the inorganic filler are approximated.

In addition, in the present invention, various thin or thick papers, synthetic resin films, metal foils, etc. can be used as the sheet-like support, and the thickness does not matter as long as it is in the form of a sheet. . If these supports are paper, their surfaces should be subjected to flame treatment, corona discharge treatment, and preheating treatment before extrusion coating to improve adhesion with the synthetic resin layer to be laminated. is desirable. In addition to this, it is also possible to perform treatments such as ozone treatment on the surface of the resin layer that should be in contact with the support.
This is effective in imparting adhesion between both layers.

As a result, the resin temperature decreases, and it is possible to reduce the frequency of occurrence of resin stains and to prevent resin deterioration and tear strength reduction.

The surface roughness of a laminated sheet obtained by laminating a resin layer on a sheet-like support can be changed by appropriately selecting the content of inorganic filler, average particle size, and thickness of the outermost layer. However, in addition to this, writing with a pencil can be improved by changing the cooling roll pattern of the laminator to give the surface of the laminated sheet a matte finish.

2. Here, "matte" means that the gloss at an incident angle of 60° is 30% or less. Furthermore, if necessary, an antistatic agent, an ink adhesion improver, an ultraviolet absorber, etc. may be incorporated into at least the lower layer of the resin or coated on the surface of the outermost layer.

In the present invention, by combining specific types of inorganic fillers, writability and printability can be imparted to the resin layer without substantially increasing chargeability.

In particular, the outermost thermoplastic resin layer contains an inorganic filler of 30 to 70%.
% by weight, and the inorganic filler mainly consists of calcium carbonate and titanium dioxide, and the ratio of both is 9.
9:1-55:45, preferably 80:20-60
:40 is most desirable. In such a configuration, the surface resistance value of the outermost layer is 1xto'°~9x10''Ω
Therefore, both the writability and printability are extremely good.

Note that the surface resistance of the laminated sheet of the present invention is 23°C,
This is a value measured at a relative humidity (RH) of 60%. .

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

The following physical properties were measured for the laminated sheets obtained in Examples and Comparative Examples, and the results are shown in Table 1.

1) Thickness: JIS P-8
1,1,82) Density: JIS 3) Writability: A pencil test was conducted under constant pressure using a pencil with a hardness of 2B.

The judgment criteria are as follows.

◎ Can write very well.

○ I can write well.

× I can't write at all.

4) Surface resistance value Model I P-6 manufactured by Nichidenki ■
01.

The measurement was carried out using VE-30 in an atmosphere of 23° C. and 60% RH.

5) Ink fixability: Using a Roland offset printing machine (202B), paper feeding speed 8000 sheets/hour,
Printing was carried out on A3 size paper using printing ink (Toyo Ink Manufacturing ■TK-CCM-KS) in the atmosphere of the printing room at 20°C x 50% RI. ) tape was applied and removed all at once, and the degree of ink removal was examined.

The judgment criteria are as follows.

◎ No peeling at all.

○ Slight peeling.

× Peel off completely.

6) Ink drying properties: Printing was carried out in the same manner as for the ink fixing properties described above, and after a period of time had elapsed from the end of printing, high-quality paper was pressed onto the printed surface, and the amount of ink transferred to the high-quality paper was examined.

The judgment criteria are as follows.

◎ Almost no metastasis.

○ Slight metastasis.

× Severe metastasis.

7) Paper feeding properties: In the above ink fixing property test, the number of paper jams caused by double feeding was investigated when 10,000 sheets of paper were printed under the same conditions.

5 [Example 1-] Polypropylene (MFR 25 g/10 min, density 0, 91
g/cm3, melt tension 0.5g) was brought into a molten state, and 40% by weight of ground calcium carbonate having an average particle size of 1.7 μm was added and mixed thereto.

Separately, prepare a polypropylene that does not contain an inorganic filler as described in 2. This resin that does not contain an inorganic filler is used as the lower layer in contact with the support, and the above resin containing the inorganic filler is used as the outermost layer. A sheet of high-quality paper with a thickness of 60 μm and a width of 500 mm was extruded from a coextrusion T-die at a temperature of 2900 C so that the outermost layer was 5 μm and the lower layer was 10 μm. Both sides were laminated to obtain a laminated sheet. The conditions for the ozone treatment at this time were a molten film stacking speed of 100 m/min, an air gap of 130 mm, an ozone concentration of 40 g/m3, and an ozone flow rate of 2 m3/h.

[Example 2] Low density polyethylene (MFRI Ig/l 0 minutes, density 0.916 g/cm3, melt tension: z1.3g
) 6 70% by weight in a molten state, and add calcium carbonate (
(average particle size: 1.7 μm) and titanium oxide (average particle size: 0.2 μm)
30% by weight of m) was added and mixed in a weight ratio of 60:40. This mixture was extruded and pressure-bonded from a T-die at a temperature of 290° C. onto both sides of the same high-quality paper as in Example 1 so that the outermost layer was 38 ml and the lower layer was 17 μm to obtain a laminated sheet. During coextrusion, the surface of the lower resin layer in contact with the paper was subjected to the same ozone treatment as in Example 1.

[Example 3] 25% by weight of the polypropylene used in Example 1 was melted, and calcium carbonate with an average particle size of 3.5 μm and titanium oxide with an average particle size of 0.2 μm were added in a weight ratio of 95:5. 75% by weight was added and mixed. Separately, prepare the above-mentioned polypropylene that does not contain an inorganic filler, use this inorganic filler-free resin as the lower layer in contact with the support, and use the above inorganic filler-containing resin as the outermost layer.
At a temperature of 290°C from a coextrusion T-die, the outermost layer is 10μ
A laminated sheet was obtained by extrusion and pressure bonding onto both sides of the same high-quality paper as in Example 1 so that the m1 lower layer was 20 μm thick.

[Example 4] Polypropylene (MFR 25 g/l, 0 minutes, density 0, 9
1g/cm3, melt tension 0.5g) 70% by weight
is in a molten state, and calcium carbonate (average particle size 2
．． 0 μm) and titanium oxide (average particle size 02 μm) were added and mixed at a weight ratio of 95:5 in an amount of 30% by weight. Separately, prepare the above-mentioned polypropylene that does not contain an inorganic filler, use this inorganic filler-free resin as a lower layer, and co-extrude it with the inorganic filler-containing resin using a T-die at a temperature of 290°C. A laminated sheet was obtained by extrusion and pressure bonding onto both sides of an OPP (-axially stretched polypropylene) film having a thickness of 60 μm as a support so that the outermost layer was 7 μm and the lower layer was 13 μm. The ozone treatment conditions at this time were: molten film stacking speed 1.00 m/min, air gap ↓ 30 mm, ozone concentration 40 g/m3, and ozone flow rate 2.
m3/h.

[Example 5] 55% by weight of the polypropylene used in Example 4 was melted, and calcium carbonate with an average particle size of 1.7 μm, titanium oxide with an average particle size of 0.2 μm, and titanium oxide with an average particle size of 2 μm were added to it.
45% by weight of silica was added and mixed in a weight ratio of 80+10:10. Separately, the above polypropylene containing no inorganic filler was prepared, and a resin containing no inorganic filler was coextruded on one side of the same OPP film as in Example 4 as a lower layer using a T-die at a temperature of 290°C. Immediately take it out so that the outermost layer is 20 μm and the bottom layer is 25 μm.
A single layered sheet was obtained by pressure bonding.

[Example 6] Thermoplastic polyester (intrinsic viscosity 0.8HI/g) 7
0% by weight was in a molten state, and 30% by weight of talc having an average particle size of 4 μm was added and mixed thereto. Separately, a graft-modified polyolefin was prepared, and this graft-modified polyolefin (manufactured by Mitsui Ishiura Chemical Co., Ltd., trade name: "Atomer A") was prepared.
T499J) as the lower layer, in the same manner as in Example 4,
The aluminum foil was laminated on both sides of a 60 μm thick aluminum foil using a coextrusion T-die so that the outermost layer had a thickness of 10 μm and the lower layer had a thickness of 127 zm.

9 [Comparative Example 1] In Example 2, the layer containing the inorganic filler was 10 μm thick.
A laminated sheet was obtained in the same manner except that the thickness of the layer not containing 1 was 10 μm.

[Comparative Example 2] In Example 4, the layer containing the inorganic filler was 10 μm thick.
A laminated sheet was obtained in the same manner except that the thickness of the layer not containing 1 was 10 μm.

0 margin below (Effect of the invention) The present invention provides a sheet-like support with a synthetic resin layer containing no inorganic filler as the lower layer, and a synthetic resin layer containing 20 to 80% by weight of an inorganic filler on the upper surface. Since the outermost layer is formed to be thinner than the lower layer, there is no problem with the adhesive strength of the inorganic filler-containing layer to the support. A laminated sheet with excellent writability, printability, and low chargeability can be obtained. Since a large amount of inorganic filler is concentrated in the outermost layer, which is thinner than the lower layer, it is possible to reduce the weight of the sheet itself without impairing the above-mentioned performance such as writability.

In addition, since the manufacturing method according to the present invention is coextrusion using a T-die, it is easy to adjust the layer thickness of the outermost layer and the lower layer, and furthermore, the layer thickness of the outermost layer is different from that of the thicker lower layer. By coextruding, it can be formed extremely thin, and the layer thickness can be adjusted to t~5 μm, which significantly exhibits the effect of inorganic filler blending.

hand Continued Supplementary Positive book (spontaneous) June 1990: I-6th

Claims (4)

[Claims] (1) Two or more layers of thermoplastic synthetic resin are laminated on at least one surface of the sheet-like support, and the outermost synthetic resin layer contains an inorganic filler of 20 to 80%.
% by weight, the outermost layer is thinner than the lower synthetic resin layer, and it contains virtually no inorganic filler. Chargeable laminated sheet. (2) Inorganic filler 30~ in the outermost thermoplastic synthetic resin layer
70% by weight, and further characterized in that the inorganic filler mainly consists of calcium carbonate and titanium dioxide, and the ratio of both is 80:20 to 60:40 on a weight basis. laminated sheet. (3) The laminated sheet according to claim 1 or 2, wherein the outermost layer has a thickness of 1 to 5 μm. (4) A molten thermoplastic resin containing 20 to 80% by weight of an inorganic filler and a thermoplastic resin containing no inorganic filler are heated in a T-die so that the former resin is thicker than the latter resin. It is characterized by being thin and laminated so that the latter resin is located on the side in contact with the surface of the sheet-like support, extruding it into a two-layer film form from a T-die, and laminating and adhering it to the surface of the sheet-like support. Method for manufacturing laminated sheets.