JP3203022B2 - Easy-to-collapse molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to easily disintegrable films, sheets or containers.

[0002]

2. Description of the Related Art In general, synthetic polymers are widely used in various fields because they have high material properties, are excellent in processability, and are inexpensive. However, the molded product is bulky,
Due to its own durability, it does not collapse naturally even when it is dumped or landfilled, and its heat generation is high when incinerated. Therefore, studies have been made to reduce the bulk of the plastic waste by partially decomposing it by light or microorganisms, and to effectively use waste treatment facilities or landfills.

[0003] Above all, studies on a thermoplastic resin composition having biodegradability by blending a relatively inexpensive and completely biodegradable starch with a thermoplastic resin as an easily disintegrating agent have been actively conducted. (Japanese Patent Application Laid-Open Nos. 2-142228 and 3-33333).

[0004]

However, the conventional EVOH having a high ethylene content cannot provide a molded product having excellent disintegration properties.

[0005] An object of the present invention is to provide a film or a sheet having excellent disintegration properties and excellent gas barrier properties.
Or to provide a container .

[0006]

An object of the present invention is to provide an easily disintegrable film or sheet comprising a hot water-soluble ethylene-vinyl alcohol copolymer having an ethylene content of 3 to 14 mol% and a saponification degree of 50 to 95% , and a plasticizer. Or by providing a container .

[0007] The ease of disintegration of EVOH by living organisms is partially described in the Nikkei New Materials, March 26, 1990, and the resin composition comprising EVOH and starch which is a natural product is disclosed in JP-A-2- 14228 and JP-A-3-31333. However, the ethylene content of EVOH conventionally used in the art is 25 mol% or more, and these publications or publications disclose EVOH having a low ethylene content as specified in the present invention. There is no specific example of using.
Among the above publications, JP-A-3-31333 discloses an ethylene content of 10 to 90% by weight (in terms of mol%, 1%).
4.9 to 93.4 mol%),
EVOH with ethylene content less than 25 mol%
Is not described as having excellent disintegration properties. Further, as a result of the additional tests by the present inventors, ethylene 2
It was found that EVOH of 5 mol% or more had significantly lower disintegration than the EVOH described in the present invention. This is clear from a comparative example described later.

In the present invention, it is important that the ethylene content of the EVOH is 3 to 24 mol%, preferably 3 to 20 mol%, more preferably 3 to 14 mol%, and most preferably 5 to 12 mol%. %. If the ethylene content is more than 24 mol%, the spreadability at the time of forming the film, which is the object of the present invention, cannot be obtained, and the disintegration property is not sufficient. On the other hand, if the amount is less than 3 mol%, a sufficient strength that can withstand practical use cannot be obtained when molded into a film, and the disintegration property is also insufficient.

The saponification degree of the vinyl ester component of EVOH is preferably at least 50%. From the viewpoint of thermal stability, it is preferably at least 80%, more preferably at least 90%. If the degree of saponification is less than 50%, the thermal stability is reduced and a large amount of gel is generated at the time of molding. From the viewpoint of solubility in hot water, the degree of saponification is 50
９５95%, more preferably 60-95%. EVOH is a saponified copolymer of ethylene and vinyl ester. Here, vinyl acetate is a typical example of vinyl ester. Other fatty acid vinyl esters (eg, vinyl pivalate) can also be used. . In addition, EVOH, olefins having 3 or more carbon atoms such as propylene, (meth) acrylic acid, vinylsilane-based compounds (vinyltrimethoxysilane, vinyltriethoxysilane, etc.), vinylpyrrolidone-based compounds can be used as long as the object of the present invention is not impaired. It is free to copolymerize the third component such as. Further, EVOH having an alkyl group having 4 to 50 carbon atoms at the terminal and / or side chain, EVOH having a part of hydroxyl group oxidized, EVOH having an aliphatic polyester grafted, and ionic group (carboxylic acid EVOH having a group or a salt thereof, a sulfonic acid group or a salt thereof, an ammonium group, and the like. In addition, the intrinsic viscosity of EVOH [solvent water / phenol
15/85 (weight ratio), 30 ° C.] is 0.05 to 0.2 l / g, preferably 0.07 to 0.15 l / g.
g.

It is particularly preferable that the EVOH used in the present invention is soluble in hot water because it has an effect of promoting the easy disintegration of the EVOH. Here, the term "soluble in hot water" means a property of substantially completely dissolving when immersed in hot water of 95 ° C for 1 minute. EVOH is preferably thermoplastic because it can be melt-molded.

It is important that the weight loss of the film as defined in Example 1 is at least 20%, more preferably at least 40%, even more preferably at least 50% and optimally at least 60%.
That is all.

The molded articles (films, sheets,
The container) may be freely added with other additives, for example, a plasticizer such as water or glycerin, in order to further increase the moldability and flexibility of the resin. Examples of plasticizers include polyethylene glycol, ethylene glycol, diglycerin, glycerin, 1,3- and 1.4-butanediol, 1,2-propylene glycol, sorbitol, ε-caprolactam, urea, toluenesulfonamide, lauryl Amide, acetamide, formamide,
One or a mixture of two or more selected from dimethyl sulfoxide, dioctyl phthalate, dibutyl phthalate, water and the like is used. Preferably, glycerin, water, urea and the like are used.

The molded article of the present invention may further contain a filler (talc, clay, mica, cellulose fiber, PVA fiber, etc.), a heat stabilizer, an ultraviolet absorber, an antioxidant, a vegetable oil, as long as the effects of the invention are not impaired. It is also free to blend a coloring agent or the like.

The EVOH of the present invention can obtain any molded product (eg, film, sheet, various containers (various injection molded products, parison)) using a well-known extruder, injection molding machine, press machine and the like. Alternatively, the resulting film may be stretched into a split yarn, which may be a woven or knitted fabric. When obtaining a molded product, stretch molding, for example, uniaxial stretching, biaxial stretching (simultaneously or sequentially), and heat treatment can be appropriately performed.

Examples of the molded product are not particularly limited, but the molded product which is discarded after being used for a certain period of time, for example, a cup, a bottle, a tray as a food container, a sheet, a pile, and a mulch as an agricultural material ( Multi-film), planters, containers or carrier materials for agricultural chemicals, fertilizers, soil conditioners, etc., tying straps as daily necessities, toys for children, trash cans, cushioning materials for industrial use, packing,
Examples include various containers and colostomy bags.

When the molded article is discarded after being used, the disintegration starts immediately after being dumped in a garbage collection area similar to general garbage, but in order to enhance the effect of disintegration by microorganisms in the soil, A landfill method is preferred. Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0017]

EXAMPLES Reference Example 1 The ease of disintegration of the EVOH alone of the present invention was examined. EVOH having an ethylene content of 7 mol% and a degree of saponification of 99.7% was converted to water /
Using a mixed solution of propanol as a solvent, 10% by weight of E
A VOH solution was obtained. The solvent was evaporated by applying the solution on a rotating drum adjusted to a temperature of 75 ° C.
A uniform film of μ was obtained.

The film was cut into a size of 15 × 100 mm, immersed in hot water adjusted to 95 ° C. for 1 minute, and examined for hot water solubility. The results are shown first. The hot water solubility was evaluated in three stages as described below. ○ ・ ・ ・ Completely dissolved △ ・ ・ ・ Swelled and separated × ・ ・ ・ Invariant

0.2 g of the film was cut out and immersed in 100 ml (ml) of a liquid medium containing 0.3% of polyvinyl alcohol (PVA) which had been sterilized in advance. This medium is inoculated with 1 milliliter (ml) of a PVA-degrading bacterium solution previously grown on a liquid medium containing 0.3% of PVA by shaking for 3 days, and the pH is adjusted to 7 to 7.5 for 2 weeks. After shaking, the change in weight of the film was determined by the following equation and is shown in Table 1. The shaking conditions were 120 rpm (30
° C).

[0020] The weight is a value measured after allowing the film to stand at 20 ° C. and 50% RH for 48 hours.

The composition of the liquid medium containing 0.3% of PVA (PH = 7.5) is as follows. PVA (polymerization degree 1700, saponification degree _{99.9%) 0.3% NH 4 NO} 3 0.1% KH 2 PO 4 0.02% K 2 HPO 4 0.1% MgSO 4 · 7H 2 O 0.02 % NaCl 0.01% CaCl ₂ .2H ₂ O 0.01% FeSO ₄ .7H ₂ O 0.001% Peptone 0.005% ext. 0.005% pyrroloquinoline quinone 1 μg / ml

Reference Examples 2 to 7 The same conditions as in Reference Example 1 were carried out except as shown in Table 1. Table 1 shows the results.

Example 1 90 parts by weight of EVOH having an ethylene content of 10 mol% and a saponification degree of 90% as an easily disintegrating agent and 10 parts by weight of glycerin as a plasticizer were blended.
m, L / D = 26, melt kneading using a single screw extruder having a full flight screw, forming a strand at an extruder temperature of 180 ° C. from a pellet die attached to the tip of the extruder, and subsequently using a pelletizer. It turned into pellets.

The pellets are 550 mm wide in the above extruder,
The film was extruded from a film forming apparatus equipped with a coat hanger die having a lip opening of 0.3 mm, and a film (15 μ) was obtained with a take-off apparatus having a cast drum having a diameter of 800 mm.

The obtained film was placed in soil (5-1 to 1 below the surface layer).
0 cm), and the state of the film after 6 months was evaluated for easy disintegration in the following four stages. As a result, the film of the present invention was evaluated as B. A: severely damaged B: considerably damaged C: slightly damaged D: unchanged In addition, the breaking strength and breaking elongation of the films obtained in Examples 1 to 4 showed values enough to withstand practical use. .

[0026]

[Table 1]

[0027]

The film, sheet or container of the present invention is excellent in easy disintegration, and when these are buried in soil as waste after use, they are quickly disintegrated by microorganisms, and their shape, strength, etc. Disappears.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-152407 (JP, A) JP-A-60-173838 (JP, A) JP-A-54-40287 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C08J 5/00 C08J 5/18 C08L 29/04

Claims (4)

(57) [Claims] An easily disintegrable film comprising a hot water-soluble ethylene-vinyl alcohol copolymer having an ethylene content of 3 to 14 mol% and a saponification degree of 50 to 95%, and a plasticizer.
Is a sheet . 2. Saponification with an ethylene content of 3 to 14 mol%.
Hot water soluble ethylene-vinyl alcohol with a degree of 50 to 95%
Easily collapsible container comprising a copolymer and a plasticizer. 3. A hot water-soluble ethylene-vinyl alcohol copolymer having an ethylene content of 3 to 14 mol% and a saponification degree of 50 to 95% and a plasticizer are melt-kneaded by an extruder and then molded. To easily disintegrate film or sheet
Method of manufacturing a door. 4. Saponification with an ethylene content of 3 to 14 mol%
Hot water soluble ethylene-vinyl alcohol with a degree of 50 to 95%
After melt-kneading the copolymer and plasticizer with an extruder,
A method for producing an easily collapsible container, characterized by being shaped.