JPH07188432A - Biodegradable film and laminate - Google Patents

Abstract

PURPOSE:To obtain a film made of a biodegradable plastic which has an elongation and satisfies all of suitability for application to a can, impact resistance, prevention of contents leakage, contents preservation, and sealability by thermal fusion; and to obtain a laminate containing the film. CONSTITUTION:A copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid is formed into a film, or laminated to paper on at least one side. The film or laminate is heated at a temp. not lower than 100 deg.C but not higher than the melting point of the copolymer, desirably at 100 deg.C for at least 10min, at 110 deg.C for at least 5min, at 120 deg.C for at least 2min, or at 130 deg.C for at least 1min, preferably at the temp. lower by 5 deg.C than the melting point for at least 1min.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film and a laminate for use as a packaging material, and more specifically to a film having elongation and complete biodegradability, as well as box suitability and impact resistance. And a completely biodegradable laminate.

[0002]

2. Description of the Related Art Conventionally, plastic films and laminates using the same have been widely used as packaging materials. Since these packaging materials are required to have rigidity, suitability for box making, impact resistance, leakage prevention function of contents, hygiene maintaining function of contents, heat fusion sealing function, and the like, polyolefins such as polyethylene and polypropylene among plastics are required. Is widely used.

When the above packaging material is disposed of after use and is landfilled or scattered as dust in the natural environment, the polyolefin remains in its original form without being decomposed. It will shorten the life of the place and cause environmental pollution.

As one of the solutions to the above problems, it has been proposed to replace the polyolefin with a biodegradable plastic. The inventors of the present invention also propose a packaging material using a 3-hydroxybutyric acid-3-hydroxyvaleric acid copolymer (hereinafter referred to as P (3HB-3HV)), which is a biodegradable plastic, and a method for producing the same. No. 249106 is presented.

However, P (3HB-3HV) has a drawback that it has a low elongation and is brittle as compared with polyolefins such as polyethylene and polypropylene. When it is used as a packaging material, its impact resistance is poor and the contents leak. However, when a container is made of a laminated body of paper, there is a problem that the suitability for box making is poor and a crack is generated at the part of the ruled line.

As one of the solutions to the above problem, P (3
HB-3HV) is blended with other biodegradable plastics or laminated, and there is a method of compensating for the disadvantage that the elongation is small and brittle, and the present inventors also used P (3HB-3HV) with biodegradable plastics. Japanese Patent Application No. Hei 4-1 describes a packaging material blended with a certain poly ε-caprolactone and a method for producing the same.
It is presented in No. 97463.

However, P (3HB-3HV), which is a microbial-produced polyester, can be regarded as a natural material similar to paper and has no hygienic problems, and other biodegradable plastics such as poly ε-caprolactone. There is a big advantage that the decomposition rate is faster, and P (3HB-3
HV) A single film having elongation is desired.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has elongation, suitability for box making, impact resistance, leakage preventing function of contents, and contents. A biodegradable plastic that is a packaging material that satisfies all of the hygiene retention function and heat fusion sealing function, and that is completely decomposed by the action of microorganisms even if it is landfilled after use or scattered as dust in the natural environment. It aims at providing the film and laminated body characterized by using.

[0009]

In order to solve the above-mentioned problems, the present invention provides a film made of a 3-hydroxybutyric acid-3-hydroxyvaleric acid copolymer, or a paper made of 3-hydroxybutyric acid. A laminate in which 3-hydroxyvaleric acid copolymers are laminated, and after molding or lamination, 100
℃ or more and melting point or less, preferably 100 ℃ 10 minutes or more or 110 ℃ 5 minutes or more, 120 ℃ 2 minutes or more or 130 ℃ 1 minute or more, more preferably (melting point -5) ℃ 1
There is provided a biodegradable film or laminate, which is characterized by performing heat treatment for at least a minute.

The present invention will be described in detail below. The P (3HB-3HV) film used in the present invention and the laminated body in which P (3HB-3HV) is laminated on at least one side of the paper are the same as those used for producing ordinary films and laminated bodies. However, the coextrusion coating method with a polyolefin presented by the inventor in Japanese Patent Application No. 3-2491006 is preferable from the viewpoint of processability of P (3HB-3HV).

The P (3HB-3HV) used in the present invention preferably has a 3HV content of 1 to 20% from the viewpoint of extrusion processability.

P (3HB-3H produced by the above method
V) the film and the laminate to 100 ° C or higher and melting point or lower,
The film according to each claim is preferably subjected to heat treatment at 100 ° C. for 10 minutes or longer, 110 ° C. for 5 minutes or longer, 120 ° C. for 2 minutes or longer, or 130 ° C. for 1 minute or longer, and more preferably (melting point −5) ° C. for 1 minute or longer. And a laminate is obtained. The heat treatment method is not particularly limited even if it is an ordinary hot air dryer, and there is no particular limitation.

[0013]

[Function] Since films and laminates used for conventional packaging materials use non-degradable plastics such as polyolefins as plastics, if they are landfilled after use and are scattered as garbage into the natural environment, they are almost permanent. Retained its form. However, by using biodegradable plastics, films and laminates composed of these decompose in landfills or in the natural environment.

However, among biodegradable plastics, P (3HB-3HV), which is a microbial-produced polyester, has the advantages of no hygienic problems and a high decomposition rate, but has the drawback of poor elongation and brittleness. Therefore, it was not used alone as a packaging material, but was forced to be blended or laminated with other biodegradable plastics.

Therefore, according to the present invention, by subjecting them to a heat treatment at a temperature of 100 ° C. or higher and a melting point or lower, they can be used in food applications, have elongation, and are suitable for box making, impact resistance, and a function of preventing leakage of contents. It has become possible to obtain a film and a laminate having biodegradability satisfying all the functions of maintaining the hygiene of contents and the function of sealing by heat fusion.

The reason why the elongation increases when P (3HB-3HV) is heat-treated on the biodegradable resin has not been completely clarified. Has the property that the solidification of
It is said that the optimum temperature for crystallization is about 60 to 70 ° C. However, when heat treatment is performed at a high temperature of 100 ° C. or higher, the progress of crystallization itself is delayed, but the elongation increases in the process of crystallization. It seems to act in the direction.

[0017]

EXAMPLE P (3HB-3HV) (manufactured by Zeneca: trade name Biopol "D610G", HV content 12%) and polyethylene having a melt flow rate of 25 g / 10 min at a processing temperature of 170 ° C. and a multi-manifold system T-die. The thickness of the P (3HB-3HV) layer is 2 by the mold coextrusion machine.
It was coextruded so that the thickness of the polyethylene layer was 0 μm and 20 μm, and laminated on the biaxially stretched polyethylene terephthalate film so that the P (3HB-3HV) layer was placed. Then, the polyethylene layer and the polyethylene terephthalate film were peeled off, and P (3HB-
3HV) film was obtained.

According to the above method, instead of the biaxially stretched polyethylene terephthalate film, the basis weight is 350 g / m.
It laminated similarly using the paperboard of No. ² , and the polyethylene layer was peeled after that, and the laminated body of P (3HB-3HV) / paperboard was obtained.

The above film and laminate were heat-treated using a hot air dryer of a dry laminator. The heat treatment conditions were temperature and time as factors, and each condition shown in Table 1 was carried out.

The tensile elongation and decomposability of the film and the film of the laminate thus produced and the water resistance and impact resistance of the laminate were measured by the following methods.

<Tensile Elongation> A rectangular test piece having a width of 15 mm was cut out from the film, and the elongation until breaking was measured by a tensile tester. However, 10% or more is good, and elongation is 10
Those less than% were defined as x.

<Degradability> Polyvinyl chloride nets are wrapped in a sludge tank in an activated sludge tank at a wastewater treatment plant and suspended. Periodically, the state of decomposition is evaluated. The retained one was marked with x.

<Water resistance> The above laminated body has an internal volume of 500 ml.
Mold the container, fill it with water, heat seal, and bring it to room temperature.
After being left for a month, those with no water leakage were marked with ◯, and those with water leakage were marked with x.

<Impact resistance> After filling the above-mentioned container with water and heat-sealing, the container is dropped vertically from a height of 1 m onto a concrete floor. It was set to x.

[0025]

[Table 1]

[0026]

[Table 2]

In Table 2, all of the water resistant samples x showed water leakage from the ruled lines, that is, the bent portions. In addition, all of the impact-resistant × also had water leakage from the ruled lines, that is, the bent portions. Each of these has a tensile elongation of less than 20%, and it can be seen that there is a correlation between the tensile elongation and the water resistance and impact resistance.

From Table 2, 100 ° C for 10 minutes or longer, 110 ° C
The elongation is 20% or more at 5 minutes or more, 120 ° C. for 2 minutes or more, and 130 ° C. for 1 minute or more, and both the water resistance and the impact resistance are improved, and the effect of heat treatment is recognized. Further, these materials had good decomposability, and no adverse effects due to the heat treatment were observed.

As described above, the effect of heat treatment is 100 ° C. 1
The effect is recognized in 0 minutes or more, but considering the processing efficiency, 1
It may be 10 ° C for 5 minutes or longer, 120 ° C for 2 minutes or longer, and 130 ° C for 1 minute or longer.

As a matter of course, the effect is exhibited even at intermediate temperatures such as 105 ° C. and 128 ° C. which are not shown in the examples. In this example, the material used, that is, P (3
HB-3HV) (manufactured by Zeneca: trade name Biopol "D
610 G ", HV content 12%) has a melting point of 136 ° C., so no examples of 130 ° C. or higher are shown, but different HV contents have different melting points, for example,“ D310G ”.
(Same as above, HV content 6%) has a melting point of 151 ° C.
It has been confirmed that a similar effect can be obtained by heat treatment at 40 ° C. for 1 minute or more.

[0031]

According to the present invention, 3-hydroxybutyric acid
3-hydroxyvaleric acid copolymer (P (3HB-3HV)
After making a laminate of the above film and paper and the resin, 100 ° C
Above melting point, preferably below 100 ° C. for 10 minutes, 110
By subjecting it to heat treatment at 5 ° C. or higher, 120 ° C. for 2 minutes or higher, and 130 ° C. for 1 minute or higher, more preferably (melting point −5) ° C. for 1 minute or higher, it can be used for food applications as well, and has elongation. It is possible to obtain a film and a laminate which have satisfactory box suitability and impact resistance and have biodegradability and which can be used as a packaging material.

Claims (6)

[Claims] 1. A film made of a 3-hydroxybutyric acid / 3-hydroxyvaleric acid copolymer, which is formed into a film and then 10
A biodegradable film which is characterized by being subjected to a heat treatment at 0 ° C. or higher and a melting point or lower. 2. The heat treatment is performed at 100 ° C. for 10 minutes or longer, 110 ° C. for 5 minutes or longer, or 120 ° C. for 2 minutes or longer, or 1.
The biodegradable film according to claim 1, which is at 30 ° C for 1 minute or more. 3. The biodegradable film according to claim 1, wherein the heat treatment is (melting point −5) ° C. for 1 minute or more. 4. A laminate in which a 3-hydroxybutyric acid / 3-hydroxyvaleric acid copolymer is laminated on at least one surface of paper,
A laminated body having biodegradability, which is characterized by performing a heat treatment at 100 ° C. or higher and a melting point or lower after lamination. 5. The heat treatment is performed at 100 ° C. for 10 minutes or longer, 110 ° C. for 5 minutes or longer, or 120 ° C. for 2 minutes or longer, or 1.
30 degreeC and 1 minute or more, The laminated body which has biodegradability of Claim 4 characterized by the above-mentioned. 6. The biodegradable laminate according to claim 4, wherein the heat treatment is (melting point −5) ° C. for 1 minute or more.