JP2000296588A - Composite separate sheet and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite separate sheet constituted of a paper base sheet and a polyolefinic resin layer and reduced in the lowering of the peel strength of both of them even if receiving mechanical stress such as bending and a method for producing the same. SOLUTION: In a composite sheet wherein a polyolefinic resin layer with a thickness of 10-50 μm comprising one of polypropylene with a melt index of 18-32 g/10 min and polyethylene with a melt index of 7-15 g/10 min is formed on both surfaces of a paper base sheet with a thickness of 0.5-5 mm, the holding ratio of the min. value of the peel strength of the base sheet and the polyolefinic resin layer after bending treatment is at least 50%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a separate sheet and a method for producing the same. More specifically, the present invention relates to a separate sheet used for bulk packaging of containers such as glass bottles, plastic bottles, and metal cans, and a method for producing the same.

[0002]

2. Description of the Related Art Containers such as glass bottles, plastic bottles, and metal cans are used for storing, transporting, and packaging products, commodities, and the like. Usually, these containers are handled in a state of being stored in a carton, a wooden box, a plastic case, or the like. In recent years, bulk packaging has been performed from the viewpoint of streamlining these packaging. Here, the bulk packaging is, for example, as follows. Spread a separate sheet over the entire surface of the pallet. The first stage of the container such as the above-mentioned glass bottle, can, or PET bottle is placed on the separate sheet. Sequentially, multiple layers are stacked via a separate sheet. Put the separate sheet and top frame on the top. Tighten with a band or the like as necessary, and package the whole with a shrink film or stretch film.

Conventionally, water-resistant paperboard has been mainly used as a separate sheet used for bulk packaging as described above. The paperboard product has the advantage that it is inexpensive and lightweight, and has an appropriate restoring force against rubbing caused by bending or pressing force. However, even if it is waterproof paper, it is weak to water and moisture, and in the humid period, because the mechanical strength of the sheet decreases,
There was a problem that the number of times of use was small. Further, there is a problem that when oil or the like adheres, the oil soaks and becomes unusable.

[0004] In addition, the paperboard separate sheet tends to be a hotbed of various bacteria and fungi because it easily absorbs moisture, and has a problem in hygiene. In addition, there is a problem that moths and the like lay eggs when the bonded portions at the corners of the separate sheet are scattered, and the eggs are evolved when the eggs are packaged in bulk. In addition, since the base material is paper,
Generation of paper dust and fiber waste is inevitable. For this reason, there are problems such as the generation of mold after filling the contents and the necessity of extra washing and sterilization before filling the contents by mixing the waste into the empty bottles and cans. In recent years, freshness and taste retention,
For the purpose of simplifying the process, a filling method called aseptic filling, which is a simplified sterilization step, has been adopted, and the demand for hygiene has been increasing.

To solve these problems, Japanese Utility Model Laid-Open Publication No. Sho 61-30652 discloses a method of covering each of paperboards with a shrink film to prevent moisture. However, the film may be easily torn by rubbing, and the moisture-proof property may be impaired. Further, there is a problem that the film is easily peeled off from the paperboard when the sheet is sucked and transported. Further, Japanese Patent Application Laid-Open No. 4-294755 discloses a technique of applying a curable resin on a paperboard and curing the same to obtain a cured film obtained by curing the resin. However, when the sheet is bent, there is a problem that the cured film is cracked and moisture resistance is impaired.

[0006] On the other hand, there is also known a method of forming the entire separate sheet from resin without using paperboard. However, the resin-made one does not cause a decrease in strength due to moisture absorption, but is excessively heavy as compared with paperboard. In addition, when an additive such as an antibacterial agent or an antistatic agent is added to the surface portion of the sheet, the additive is added to the entire resin constituting the sheet. there were. In addition, the separate sheet made entirely of resin has a problem that the bottles and cans placed on the sheet are easily moved by vibration during transportation, often leading to collapse of the load.

Further, as disclosed in Japanese Patent Application Laid-Open No. 7-52302, there is a method in which a resin sheet is formed into a multilayer structure and the above-mentioned additives are added only to a layer near the surface, but the weight is excessive. And the problem of ease of collapse has not been solved. Further, as disclosed in JP-A-7-89017, there is also disclosed a method of forming a curable resin layer on a thermoplastic resin and bonding the resin layer to paperboard to obtain moisture-proof properties. According to this method, the above problem can be solved when the sheet is left standing. However, in actual use, the separate sheet is subjected to various mechanical stresses such as bending of the sheet due to press-fitting of a bottle mouth, winding of a stretch film, impact upon unloading and unloading, and vibration during transportation. In this method, the adhesion between the thermoplastic resin layer and the paperboard is still insufficient. Therefore, when the mechanical stress is applied, a portion where the peel strength of the thermoplastic resin layer is reduced is generated. Then, the thermoplastic resin layer peels off or floats from the portion, so that the moisture resistance is impaired and the intended purpose is not achieved.

[0008]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a base material having a small decrease in peel strength between a paper base sheet and a resin layer even when subjected to mechanical stress such as bending. An object of the present invention is to provide a composite separate sheet composed of a paper sheet and a polyolefin-based resin layer, and a method for producing the same.

[0009]

Means for Solving the Problems As a result of extensive studies to solve the above problems, the present inventors have found that a polyolefin resin having a specific melt index on both sides of a paper base sheet by an extrusion lamination method. The inventors have found that the above problems can be solved by forming a layer, and have finally reached the present invention.

[0010] That is, the present invention provides a thickness of 0.5 to 5 mm.
The melt index is 18 on both sides of the paper base sheet
A composite separator sheet formed with at least one polyolefin-based resin layer having a thickness of 10 to 50 μm, which is selected from polypropylene having a melt index of 7 to 15 g / 10 minutes and polypropylene having a melt index of 7 to 15 g / 10 minutes. And a composite sheet having a minimum peel strength of the peel strength between the paper base sheet and the polyolefin resin layer after the bending treatment of at least 50%.

Another invention according to the present invention relates to a method for producing a composite separate sheet in which a polyolefin-based resin layer is formed on both sides of a paper base sheet (S), wherein the extruder is provided with a T die. At 200 to 330 ° C. using a polypropylene having a melt index of 18 to 32 g / 10 minutes and a melt index of 7 to 15
g / 10 minutes, at least one type of polyolefin resin selected from polyethylene is melt-extruded and has a thickness of 0.5
10-50 μm thick on both sides of a paper base sheet of 〜5 mm
Wherein the polyolefin resin layer is formed by an extrusion lamination method.

In a preferred embodiment of the composite separate sheet according to the present invention, the bending strength and the humidification treatment have a retention of bending strength of at least 70% and a thickness of 0.5 to 5%.
mm.
The composite separate sheet according to the present invention is formed from a paper base sheet and a polyolefin-based resin layer. The feature of the manufacturing method is that the lamination of the paper base sheet and the polyolefin-based resin layer is performed by an extrusion lamination method. Therefore, the adhesiveness between the paper base sheet and the polyolefin-based resin layer is excellent, and the paper base sheet and the polyolefin-based resin layer are hard to peel off even when subjected to bending stress. In addition, it has excellent moisture resistance and durability. Therefore, the service life is long. Therefore, the composite separate sheet of the present invention is extremely useful as a bulk packaging material in the field of physical distribution.

In the present invention, the peel strength between the base sheet and the polyolefin resin layer, the retention rate of the minimum peel strength after the bending treatment, the bending strength, and the bending strength after the bending treatment and the humidification treatment. Is a value measured by a method described in Examples described later.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The basic structure of the composite separate sheet of the present invention is a laminate in which a polyolefin-based resin layer having a specific melt index (hereinafter, referred to as MI) is formed on both sides of a paper base sheet. The feature of the production method is that polyolefin-based resin layers are formed on both surfaces of a paper base sheet by extrusion lamination.

The paper base sheet used in the present invention includes:
A paperboard such as a manila ball, a white ball, a yellow ball, a paper tube base paper, a cardboard base paper, or a laminate thereof is preferably used. Also, used paper may be used in combination with pulp. The thickness is determined by the type and weight of the container to be bulk-packaged. Usually 0.5-5m
m. 0.7-4 mm is more preferable. The thickness is 0.
If it is less than 5 mm, the strength is insufficient, and the sheet cannot be used as a separate sheet. On the other hand, if the thickness exceeds 5 mm, the weight becomes excessively large and the merit of using paper as the base sheet is reduced. Before extrusion lamination of the polyolefin resin layer on the surface of the base sheet, if necessary, corona discharge treatment, primer discharge treatment on the surface of the base sheet,
Surface treatment such as chemical application and spraying may be performed. Also, depending on the application, sizing agents such as saponified natural rosin, fortified rosin, alkyl ketene dimer, alkenyl succinic anhydride, stearic anhydride, etc., dry paper strength of cationized starch, polyacrylamide, dialdehyde starch, vegetable gum, etc. Enhancer, urea formaldehyde resin, melamine formaldehyde resin, polyamide polyamine epichlorohydrin, wet paper strength enhancer such as glyoxal-modified polyacrylamide, clay, talc, kaolin, calcium carbonate,
A known paper additive such as the amount of white carbon or urea resin may be added as needed.

As the polyolefin resin, polyethylene and polypropylene are preferably used. Particularly preferred is polypropylene. MI of these polyolefin resins is 1 in polypropylene.
8 to 32 g / 10 minutes, 7 to 15 for polyethylene
It is important that g / 10 minutes. When the MI is less than these ranges, the adhesion of the polyolefin-based resin layer to the base sheet is poor, and a composite-type separate sheet that is strong in bending cannot be obtained. If the MI exceeds these ranges, the strength of the polyolefin-based resin layer is reduced, and the desired water resistance may not be obtained. Here, the MI of the polyolefin-based resin is defined by ASTM-D1238. The measurement temperature is 230 ° C. for polypropylene and 190 ° C. for polyethylene. As a typical commercial product of polypropylene that can be used in the present invention, Grand Polymer Co., Ltd., trade name: F569
R, F769, manufactured by Mitsubishi Chemical Corporation, trade name: F25T,
FL25R and the like. Also, as polyethylene, trade name: Ultzex 208 manufactured by Mitsui Chemicals, Inc.
1C, 15100C, manufactured by Idemitsu Petrochemical Co., Ltd., trade name:
1014D, 1044D and the like.

The thickness of the polyolefin resin layer is 1
It is 0 to 50 μm, preferably 20 to 40 μm. When the thickness of the resin layer is less than 10 μm, moisture and various bacteria may enter through pinholes and the like of the resin layer, and a desired composite separate sheet excellent in water resistance and hygiene cannot be obtained. On the other hand, if the thickness of the resin layer exceeds 50 μm, the resin layer has poor followability at the time of bending and is easily peeled.

It is preferable to add an antibacterial agent, an antifungal agent and the like to the polyolefin resin layer in order to suppress the generation of various bacteria and fungi and to further improve hygiene. As the antibacterial and antifungal agent,
Organic antibacterial agents and inorganic antibacterial agents are exemplified. Examples of the organic antibacterial and antifungal agents include organic tin compounds, diphenyl ether compounds, chlorhexidine compounds, and the like. In addition, as inorganic antibacterial agents and antifungal agents, cuprous oxide,
Examples thereof include copper rhodanide, zeolite containing a metal ion having an antibacterial action, zirconium phosphate, soluble glass, and silica gel. Here, examples of the metal ion having an antibacterial action include silver, copper, lead, tin, chromium, cadmium, zinc, bismuth, and thallium. Among these, inorganic antibacterial agents such as zeolite containing silver ions or copper ions having a bactericidal action, zirconium phosphate, soluble glass and silica gel are preferably used from the viewpoint of the persistence of antibacterial performance and toxicity to the human body. Can be The antibacterial agent and the antifungal agent are added in an amount of 0.1 to the polyolefin resin layer.
The content is preferably 10 to 10% by weight, more preferably 0.1 to 5% by weight. If the amount is less than 0.1% by weight, the effect of improving the antibacterial and antifungal properties is not recognized, and even if the amount exceeds 10% by weight, no significant difference is observed in the effect, and it is not economical.

In the polyolefin resin layer, an antistatic agent, conductive filler, heat stabilizer, weather stabilizer, plasticizer, lubricant, slip agent, charge transfer polymer, nucleating agent, pigment, dye, inorganic filler And an organic filler can be blended according to the purpose.

The composite separate sheet of the present invention can be produced, for example, as follows. That is,
Using an extruder equipped with a T-die, melt-extruding and laminating a polyolefin-based resin having the above-mentioned specific MI value on both sides of a paper base sheet (hereinafter referred to as S) by a known extrusion lamination method, A method of forming a polyolefin-based resin layer by cooling and solidifying. A polyolefin-based resin layer is laminated on one surface of each of the two paper base sheets (S1) and (S2) by the same method as described above to form laminates (A1) and (A2). A method of forming a paper base sheet layer (S) by bonding (S1) of the laminate (A1) and (S2) of the laminate (A2) using an adhesive. In the above method, the laminate (A
A paper base sheet layer (S3), in which 1 to 5 layers of paper are joined by an adhesive, is attached between the (S1) of 1) and the (S2) of the laminate (A2) using an adhesive. A method of forming a paper base sheet layer (S) together. Finally, the composite sheet is cut to a required size to produce a composite separate sheet.

Known adhesives such as organic solvent-based adhesives, water-soluble adhesives, aqueous dispersible adhesives, hot-melt adhesives, solvent-free adhesives, and heat-sensitive adhesives can be used as the adhesive in the above methods. No. Preferred are a water-soluble adhesive such as starch paste and synthetic paste and an aqueous dispersible adhesive. Typical examples of these commercially available products include High Pressure Gas Co., Ltd., trade names: Pegal 61LR, HA-61, Nippon Carbide Industry Co., Ltd., trade names: Nicazole H-21, G-05, etc. Can be The application amount of the adhesive is 10 to 50 g / m ² , preferably 20 to 30 g / m ² per surface area of the base sheet.
The range of m ² is preferable from the viewpoint of adhesiveness of the paste. The composite separate sheet of the present invention can be bonded by a known bonding machine. The thickness of the paper (one sheet) used as the (C3) layer used in the above method is about 0.1 to 5 mm. The total thickness of a state in which 1 to 5 sheets of these papers are joined is about 0.5 to 5 mm.

The melt extrusion temperature in the extrusion lamination method can be arbitrarily set in accordance with the physical properties of the polyolefin resin to be used, but is preferably not less than the melting point of the polyolefin resin and less than 350 ° C, more preferably 200 to 330 ° C. . In the extrusion lamination method, the polyolefin resin is melt-extruded on both sides of a paper base sheet using an extruder equipped with a T-die, and the molten resin side is immediately adhered to a casting roll, cooled, and cooled. This is a method of forming resin layers on both surfaces of a material sheet. Since the method causes the resin to adhere to the surface of the paper base sheet in a molten state,
The resin penetrates well into the paper fibers of the base sheet. In addition, in the method, by employing a polyolefin resin having a specific MI, the melt viscosity of the resin can be controlled to a specific range, and the molten resin can be well penetrated between paper fibers. Therefore, the composite separate sheet of the present invention has extremely good adhesion between the paper base sheet and the polyolefin resin layer.

On the other hand, a so-called laminating method in which a polyolefin-based resin film is prepared in advance, the film is laminated on a paper base sheet, and heated and pressed with a hot roll to form a polyolefin-based resin layer. Is that the polyolefin resin film is easy to stick to the heat roll,
Therefore, there is a restriction that the roll temperature cannot be set high. Therefore, it is difficult to sufficiently infiltrate the film resin into the fibers of the base sheet. In order to compensate for these drawbacks, there is an adhesive laminating method, that is, a method of applying an adhesive or sandwiching a film equivalent to the adhesive, followed by heating and pressing. Alternatively, there is a method of laminating a resin having a melting point higher than the temperature of the roll on the polyolefin-based resin film, followed by thermocompression bonding. However, the permeation of the polyolefin-based resin into the base sheet fiber in these methods is lower than that of the polyolefin-based resin having an appropriate MI value by the extrusion lamination method. In addition, a further extra step of lamination before thermocompression bonding is required, which is economically poor.

The composite separate sheet according to the present invention produced by the above method has extremely excellent adhesion between the base material sheet and the resin layer even after being subjected to mechanical stress such as bending. Specifically, the peel strength between the paper base sheet and the polyolefin-based resin layer is 80 to 200 g / 10
cm. Even after the bending treatment, the decrease in the peel strength is small, and the retention of the minimum value is at least 50%. The reason that the holding ratio is less than 50% is that the resin layer is easily peeled off from the base sheet and lifted up by the bending treatment.
Or, it means that the resin layer is split, and under conditions where realistic mechanical stress is applied, moisture and various bacteria enter, and although it is a composite sheet excellent in water resistance and hygiene Absent. Here, the peel strength between the paper-made base sheet and the polyolefin-based resin layer and the minimum value of the peel strength after the bending treatment are the values measured by the method described in Examples.

Further, the composite separate sheet according to the present invention has a bending strength of 50 to 500 k when the thickness is 2 mm.
g / cm ² . Even if the bending treatment and the humidification treatment are performed, a decrease in bending strength is small. Specifically, the retention of bending strength after bending and humidification is at least 70%.
%. The thickness of the composite separate sheet according to the present invention is not particularly limited, but is usually 0.5 to 5 mm.

[0026]

The present invention will be described below in detail with reference to examples. The present invention is not limited by this. The evaluation method of the performance of the separate sheet obtained in the example is shown below.

(1) Peeling strength (g / 10 mm) between the base material sheet and the resin layer after the bending treatment, and retention rate (%) of the minimum value of the peeling strength a) Bending treatment: stipulated in JIS-K6911 The test is carried out under the same conditions as in the measurement of bending strength. That is, with respect to a sample having a width of 63 mm and a length of 100 mm, a testing machine used for measuring bending strength specified in JIS-K6911, a radius of 5 mm at the tip
Using a rounded pressure wedge and a fulcrum with a radius of 2 mm at the tip, bend back to 15 °,
After inverting the sample, a bending process is performed by bending the same place again in the opposite direction. b) The sample subjected to the bending treatment by the method described in the preceding paragraph was cut into a 10 mm width, and the peel strength of the polyolefin-based resin layer from the base material sheet was increased according to the 90-degree peeling method specified in JIS-Z0237. Measurement in the vertical direction. At that time, the peeling speed was 300 mm / min, and the length was 100 mm.
Is recorded on a chart, the minimum value is used as the minimum value of the peeling strength, and the average value is used as the peeling strength. However, the measured values for 2 seconds immediately after the start of peeling and for 2 seconds immediately before the end of peeling are excluded. c) For the same sample without bending treatment, b)
The minimum value of the peel strength is measured in the same manner as in the item. d) Percentage obtained by dividing the minimum value of the peel strength of the sample with the bending treatment by the minimum value of the peel strength of the sample without the bending treatment is defined as the retention rate of the minimum value of the peel strength after the bending treatment.

2) Retention rate of bending strength after bending treatment and humidification treatment (%) A square sample having a side of 100 mm subjected to the bending treatment is subjected to an environment at a temperature of 30 ° C. and a relative humidity of 90%.
The humidification treatment is carried out by leaving it for a time. The bending strength is measured in a direction perpendicular to the direction in which the bending process was performed, according to a method specified in JIS-K6911. The bending strength of the sample not subjected to the bending treatment is measured in the same manner. The percentage obtained by dividing the latter by the former is defined as the retention (%) of the bending strength after the bending treatment and the humidification treatment in the present invention.

3) Viable Bacteria Rate (%) in Antibacterial and Antifungal Performance Test The antifungal property of the sample, the bacterium and the mold was evaluated by a film adhesion method. That is, a bacterial solution of Staphylococcus aureus and blue mold prepared with a phosphate buffer (1/15 M, pH 7.2) is dropped on the sample surface. Then, the bacterial solution is evenly brought into close contact with the sample surface with a sterilized film, placed in a sterile petri dish as it is, and
Store at 5 ° C. The viable cell count is measured for the bacterial solution on the sample 24 hours after the former and 48 hours after the latter. The percentage obtained by dividing the number of bacteria after the lapse of time by the number of bacteria at the start is defined as the viable cell rate in the antibacterial / antifungal performance test in the present invention.

Example 1 Using an extruder equipped with a T-die, at 300 ° C., a polypropylene resin having an MI of 20 g / 10 minutes [Mitsubishi Chemical Corporation, trade name: Mitsubishi Polypropylene FL25]
T] is melted and extruded, and paperboard [thickness 2 mm, basis weight 1600]
g / m2] on one side by extrusion lamination.
A polypropylene resin layer having a thickness of 20 μm was formed. The resin temperature immediately after being discharged from the T-die was 300 ° C. Next, a polypropylene resin layer was formed on the other side of the paperboard in the same manner as described above, and a polypropylene resin layer was formed on both sides of the paperboard. The sheet was cut into a size of 1100 mm in length and 1400 mm in width to obtain a composite separate sheet. The properties of the sheet were evaluated by the above method. The obtained results are shown in [Table 1] and [Table 2].

Example 2 A paperboard having a thickness of 0.5 mm and a basis weight of 400 g / m2 (hereinafter referred to as S1 and S2), and an MI of 23 g / 10
Minute polypropylene resin [Grand Polymer Co., Ltd.
(S1) and (S2) each having a thickness of 20 μm on one surface in the same manner as in Example 1 except that trade name: F769] was used.
m of the polypropylene resin layer was formed to obtain laminates (A1) and (A2). On the other hand, the same two paperboards as in S1 were treated with a vinyl acetate emulsion-based adhesive [manufactured by Koatsu Gas Industries Co., Ltd.
Product name: Pegal 61LR, coating thickness: 25 g / m2]
To produce a laminated body (S3). Finally, using the above adhesive (application thickness: 25 g / m2), (A
(S1) of (1) and (S2) of (A2)
3) was laminated to obtain a composite separate sheet composed of six layers of resin layer / paperboard / paperboard / paperboard / paperboard / resin layer.
Cutting was performed in the same manner as in Example 1. The performance evaluation results of the sheet are shown in [Table 1] and [Table 2].

Examples 3 to 4 0.5% by weight (Example 3) and 4.5% by weight of a silver-zinc zeolite antibacterial agent (trade name: Bakutekira) manufactured by Kanebo Kasei Co., Ltd. Example 4)
Was added in the same manner as in Example 2 except that was added, to obtain a composite separate sheet. The performance evaluation results of the sheet are shown in [Table 1] and [Table 2].

Example 5 The procedure of Example 2 was repeated, except that a polyolefin resin layer was formed of a polypropylene resin (trade name: Sumitomo Noblen FW363, manufactured by Sumitomo Chemical Co., Ltd.) with an MI of 30 g / 10 min. A composite separate sheet was obtained. The performance evaluation results of the sheet are shown in [Table 1] and [Table 2].

Examples 6 and 7 A composite separate sheet was obtained in the same manner as in Example 2 except that the polyolefin resin layers were formed to have a thickness of 15 μm (Example 6) and 45 μm (Example 7), respectively. The performance evaluation results of the sheet are shown in [Table 1] and [Table 2].

Examples 8 to 9 A linear low-density polyethylene resin having an MI of 8 g / 10 minutes (Example 8) or 12 g / 10 minutes (Example 9) was added to a polyolefin resin layer [Mitsui Chemicals, Inc. ), Trade name: Ultzex 2081C, 15100C], and a composite separate sheet was obtained in the same manner as in Example 2. [Table 1] and [Table 2]
Shown in

Comparative Example 1 A polypropylene resin having an MI of 23 g / 10 minutes used in Example 2 was formed into a film with an extruder equipped with a T-die and had a thickness of 20 μm.
m of polypropylene film (hereinafter referred to as film 1). The film 1 and the paperboard used in Example 2 were overlaid and pressed by a pair of heating rolls heated to 145 ° C. to obtain a laminate of the film 1 and the paperboard. The performance evaluation results of the laminate are shown in [Table 1].

Comparative Examples 2 to 5 Polypropylene resin having an MI of 15 g / 10 min [manufactured by Grand Polymer Co., Ltd., trade name: S106LA, Comparative Example 2], and a polypropylene resin having an MI of 35 g / 10 min in the polyolefin resin layer [ Mitsubishi Chemical Corporation, trade name: Mitsubishi Polypropylene MG04AS, Comparative Example 3], MI 5.1 g /
10 minute low density polyethylene resin [Mitsui Chemicals, Inc.
Product name: Mirason 14P, Comparative Example 4] or M
Composite Separate was prepared in the same manner as in Example 2 except that a linear low-density polyethylene resin having an I of 18 g / 10 min [trade name: J-LEX LL-AJ 6381, manufactured by Nippon Polyolefin Co., Ltd., Comparative Example 5] was used. I got a sheet. The performance evaluation results of the sheet are shown in [Table 1].

Comparative Examples 6 and 7 The polyolefin resin layer was 5 μm (Comparative Example 6),
m (Comparative Example 7), except that the composite separate sheet was obtained in the same manner as in Example 2 except that the composite separate sheet was formed. The performance evaluation results of the sheet are shown in [Table 1].

In Table 1, "PP" means polypropylene and "PE" means polyethylene.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

The composite separate sheet according to the present invention has excellent adhesion between the base sheet and the polyolefin-based resin layer despite the use of paper as the base sheet.
Therefore, the resin layer hardly peels even under various mechanical stresses, and the influence of moisture on the base sheet at that time can be suppressed. Further, even if oil or the like adheres, it does not impregnate, and can be used hygienically for a longer period than the conventional separate sheet. Further, if an antibacterial agent is added to the resin layer, the sanitary property is further improved. Therefore, the composite separate sheet of the present invention is extremely useful as a bulk packaging material in the field of physical distribution.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B32B 31/30 B32B 31/30 // C08J 5/18 CES C08J 5/18 CES B29K 23:00 B29L 9: 00 C08L 23:06 23:12 (72) Inventor Rintaro Tsuruta 2-1-1 Tango-dori, Minami-ku, Nagoya City, Aichi Prefecture Inside Mitsui Chemicals Platec Co., Ltd. (72) Inventor Shigezo Nishiba 1-Sarugakucho, Chiyoda-ku, Tokyo 5-18 No. Mitsui Chemicals Platec Co., Ltd. (72) Inventor Tadao Yamamoto 1-18, Sarakucho, Chiyoda-ku, Tokyo F-term in Mitsui Chemicals Platech Co., Ltd. 4F071 AA15 AA20 AA88 AF19Y AH04 BB06 BC02 CA01 4F100 AK04B AK04C AK07B AK07C BA03 BA04 BA05 BA06 BA08 BA10B BA10C BA13 CA12B CA12C CB00 DG10A DG10D EC182 EH231 EH232 GB15 JA06B JA06C JC00 B JC00C JC00H JD04 JD05 JK04 JK06 YY00 YY00A YY00B YY00C YY00D YY00H 4F207 AA03 AA11 AB01 AD06 AD08 AG01 AG03 AH81 AR12 KA01 KA17 KB11 KB22 KJ05 KL65 KL84

Claims (11)

[Claims] 1. A polypropylene having a melt index of 18 to 32 g / 10 minutes, and a melt index of 7 to 1 on both sides of a paper base sheet having a thickness of 0.5 to 5 mm.
A composite sheet having at least one polyolefin-based resin layer having a thickness of 10 to 50 μm selected from polyethylene of 5 g / 10 minutes, wherein the paper-made base sheet and the polyolefin-based resin layer after the bending treatment are formed. And a retention rate of the minimum value of the peel strength with the composite separate sheet is at least 50%. 2. The method according to claim 1, wherein the base paper sheet made of paper is liner paper, paperboard,
The composite separate sheet according to claim 1, which is a paper tube base paper or a chip ball. 3. The polyolefin-based resin layer comprises at least one additive selected from the group consisting of an antibacterial agent and an antifungal agent.
The composite separate sheet according to claim 1, wherein the composite separate sheet contains 1% by weight. 4. The composite separate sheet according to claim 1, wherein a retention ratio of a bending strength after the bending treatment and the humidification treatment is at least 70%. 5. The method according to claim 1, wherein the thickness is 0.5 to 5 mm.
5. The composite separate sheet according to any one of 4. 6. A method for producing a composite separate sheet wherein a polyolefin-based resin layer is formed on both sides of a paper base sheet (S), wherein the extruder equipped with a T-die is used.
At 0 to 330 ° C, the melt index is 18 to 3
2 g / 10 min of polypropylene and a melt index of at least one polyolefin resin selected from polyethylene having a melt index of 7 to 15 g / 10 min are melt-extruded to form a 0.5 to 5 mm thick paper base sheet. A method for producing a composite separate sheet, comprising forming a polyolefin-based resin layer having a thickness of 10 to 50 μm on both surfaces by an extrusion lamination method. 7. A laminate (A1) or (A2) by forming a polyolefin-based resin layer on one side of a paper base sheet (S1) or (S2) by an extrusion lamination method, and then an adhesive. -Based base material sheet layer (S1)
The method for producing a composite separate sheet according to claim 6, wherein the paper base sheet (S) is formed by laminating the base sheet (S2) and (S2). 8. Paper base sheet layers (S1) and (S2)
The paper base sheet (S) is formed by laminating a paper base sheet layer (S3) in which 1 to 5 layers of paper are joined with an adhesive between the layers by using an adhesive. Claim 7
A method for producing the composite separate sheet as described above. 9. The holding ratio of the minimum value of the peel strength between the base sheet and the polyolefin resin layer after the bending treatment is controlled to at least 50%.
The method for producing a composite separate sheet according to any one of the above. 10. The method for producing a composite separate sheet according to claim 6, wherein the retention of bending strength after the bending treatment and the humidification treatment is controlled to at least 70%. 11. The method according to claim 6, wherein the thickness is 0.5 to 5 mm.
9. The method for producing a composite separate sheet according to any one of items 1 to 8.