JPH06255039A - Biodegradable paper laminate - Google Patents

Abstract

PURPOSE:To obtain a paper laminate having a complete biodegradable property as well as excellent physical properties as a laminate. CONSTITUTION:A biodegradable paper laminate obtained from aliphatic polyester constituted mainly of repeated units of a general formula -O-CHR-CO-(R denotes H or 1-3C alkyl) and from paper. Since this paper laminate has a complete biodegradable property, it is decomposed in a natural environment even when it is used uncollectably after the use, and thus causes no problem of an environmental public nuisance. Accordingly, it can be applied to various uses of the paper laminate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a biodegradable paper laminate obtained from an aliphatic polyester having biodegradability and paper.

[0002]

2. Description of the Related Art In the field of packaging materials and molding materials such as milk cartons and paper cups, paper laminates such as polylaminated paper laminated with thermoplastic resin and polylaminated paperboard are useful and used in large quantities. . Most of the thermoplastic resins currently used are general-purpose resins such as polyethylene. These paper laminated bodies are collected after use and are incinerated or buried in the soil. In addition, recently, recyclable materials have come to be reused after being collected. However, since it takes a lot of effort to collect it, in reality it cannot be recovered and it is left on the road,
It has been dumped in the ocean, causing various problems including environmental damage. That is, among the constituent materials of the laminated body, the thermoplastic resin such as polyethylene is not so biodegradable at all and remains semi-permanently in the state of being left unattended, which causes a problem. Is well known.

In recent years, in order to impart biodegradability to such polyethylene and the like, various studies have been made on blending a biodegradable component such as starch. Furthermore,
A method of imparting photodegradability, or a method of blending a photodegradable polyethylene with a biodegradable component such as starch has been studied, and has been drawing attention as a solution to the above problems. In the method of blending starch, the starch portion is biodegradable and thus is decomposed by microorganisms, so that the strength of the paper laminate is reduced, and the shape is not maintained. However, the polymer portion other than starch is not decomposed in such a decomposition process, and the laminate is eventually separated, but it is merely cut into pieces, which is not a fundamental solution to the above problem. Further, the same can be said for photodegradability, and light only causes a decrease in the degree of polymerization, and cannot be said to have biodegradability.

[0004]

As described above, a paper laminated body which is completely decomposed in a state of being left naturally under the condition of soil or water has not been obtained yet.

[0005]

Means for Solving the Problems As a result of intensive investigations by the present inventors to develop a paper laminate having true biodegradability,
Finally, the present invention has been completed. That is, the present invention provides a biodegradable paper laminate obtained from an aliphatic polyester containing the following general formula (I) as a main repeating unit and paper. -O-CHR-CO -... (I) (However, R shows H or a C1-C3 alkyl group.)

In the present invention, an aliphatic polyester containing the above-mentioned formula (I) as a main repeating unit and a paper laminate containing paper as an essential constituent material can achieve both excellent properties and complete biodegradability. That is truly amazing. As described above, the biodegradable paper laminate of the present invention has sufficient performance during use and exhibits excellent biodegradability when it is disposed of in soil or water after use. It is extremely useful in industry.

The paper laminate in the present invention means a laminate containing the polymer represented by the above (I) and paper as essential constituents.

Examples of the polymer represented by the general formula (I) in the present invention include, but are not limited to, polylactic acid, polyglycolic acid, poly (2-oxybutyric acid) and the like. . In some cases, they may be used alone, or a mixture or copolymer may be used. Those having an asymmetric carbon in the polymer are
There are optical isomers such as L-form, DL-form and D-form,
Any of them may be used, or a mixture of these optical isomers may be used. The above-mentioned polymers, which are the materials for these molded articles, are dehydrated and polycondensed from the corresponding α-oxy acid,
It is produced by a known method such as ring-opening polymerization of a dehydrated cyclic ester compound of oxyacid.

Examples of the paper which is another component of the biodegradable paper laminate of the present invention include kraft paper, carton paper, glassine paper, coated paper, art paper, Kurupak paper and acid resistant paper. The material is not particularly limited, and paperboard can be used. The biodegradable paper laminate of the present invention is produced by using a polymer as described above as a raw material and a well-known method such as a melt extrusion laminating method at a melting point of the polymer or higher, a thermal bonding method, or an adhesive bonding method. You can

The polymer represented by the general formula (I) used in the present invention is required to have a viscosity average molecular weight of 5 × 10 ³ or more. When it is less than 5 × 10 ³ , the physical properties of the obtained polymer layer are remarkably inferior, and the decomposition rate is too fast to attain the object of the present invention. Further, the molecular weight of the polymer tends to be cut during the production of a laminate by the melt extrusion laminating method at a high temperature, and the molecular weight tends to decrease. Therefore, the viscosity average molecular weight of 5 × 10 ³ or more is required. On the other hand, if the viscosity average molecular weight is too high, problems such as difficult melt extrusion occur in the laminate manufacturing process,
Not preferable. A preferred range is 10 ⁴ or more and 10 ⁶ or less.

A laminate having a coat layer of various thicknesses can be produced by the above-mentioned production method according to the purpose, but the polyester coat layer of the laminate must have a thickness of 5 μm or more regardless of the purpose. If the thickness is less than 5 μm, pinholes may be generated, and in manufacturing a laminate by the melt extrusion laminating method, thickness unevenness may occur due to surging, and a stable laminate layer may not be obtained.

The biodegradable paper laminate of the present invention may have an aliphatic polyester layer on both sides of the paper, and a case where only one is included is also included. Further, it also includes the case where a well-known method such as corona treatment is applied to improve the adhesiveness between the paper and the resin layer such as the aliphatic polyester. Depending on the intended use and purpose, the biodegradable paper laminate has a gas barrier property,
If further improvement of various properties such as permeability, moisture resistance, cold resistance, oil resistance, water resistance, heat sealability, aroma retention, chemical resistance, heat resistance is required, other polymers or metal foils, Inorganic substances may be added or laminated. Further, as with ordinary polyesters, matting agents, pigments such as carbon black, antioxidants such as hindered phenol compounds, hindered amine compounds, phosphorus compounds, ultraviolet absorbers such as benzophenone compounds, benzotriazole compounds, salicylate compounds, etc., However, depending on the case, it does not matter even if it contains a compound having a crosslinkable group.

Specific examples of the biodegradable paper laminate of the present invention include food containers such as cups and trays, packs of various food products and soft drinks, pastes of various food products, toothpaste and cosmetics. Examples of the material include, but are not limited to, tube for state material, heavy bag for industrial chemicals and fertilizers, and packaging material.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 Poly-L-lactic acid having a viscosity average molecular weight of 270,000 was charged into an extruder and melt-extruded at 220 ° C. on both front and back sides of acid-resistant paper having a basis weight of 400 g / m ² to obtain a paper laminate (A). It was made. still,
The thickness of the coating layer was 20 μm.

Example 2 A paper laminate (B) was prepared in the same manner as in Example 1 except that polyglycolic acid having a viscosity average molecular weight of 100,000 was melt extruded at 260 ° C. instead of 220 ° C. instead of polylactic acid. It was made. The thickness of the coating layer was 40 μm.

Example 3 The paper laminates produced in Examples 1 to 3 were embedded in the soil collected and kept at a temperature of 35 ° C. for 6 months under sufficient humidity, and then the state of each paper laminate was observed. did. Further, it was soaked in the ingested seawater, kept at 20 ° C. for 6 months, and then similarly observed. The results are shown in Table 1. For comparison, the results of the paper laminate (C) coated with polyethylene are also shown in Table 1. From Table 1, it is clear that the biodegradable paper laminate of the present invention has excellent biodegradability. Incidentally, Examples 1 to 3
The paper laminate obtained in 1. above had good adhesion between the paper and the coating layer, and was sufficiently durable for use.

[0018]

[Table 1]

[0019]

INDUSTRIAL APPLICABILITY The biodegradable paper laminate of the present invention has excellent biodegradability and, at the same time, has sufficient physical properties as an excellent laminate and is extremely useful in each field.

Front page continued (72) Inventor Keiichi Uno 1-1-1, Katata, Otsu City, Shiga Prefecture Inside Toyobo Co., Ltd.

Claims (1)

[Claims] 1. A biodegradable paper laminate obtained from an aliphatic polyester mainly containing the general formula (I) and a paper. -O-CHR-CO -... (I) (However, R shows H or a C1-C3 alkyl group.)