JPH03146509A - Container - Google Patents

Abstract

PURPOSE:To obtain a container, composed of a polymer having specific recurring units as the backbone chain, good in mechanical properties, excellent in transparency and heat resistance, having degradability with time, decomposable in the air, soil and water in a short time and suitable for fertilizer and refuse bags, foods, etc. CONSTITUTION:The objective container composed of a polymer having the backbone chain substantially composed of recurring units (e.g. formulas II to IV) expressed by formula I (R<1> to R<6> are H or lower alkyl).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a container that has good mechanical properties, excellent transparency and heat resistance, and is degradable over time.

[Conventional technology]

In recent years, there has been a rapid rise in interest in the various problems caused by plastic waste, including concerns about the increasing proportion of plastic in waste and aesthetic problems. plastic products that do not cause
Packaging materials are required. As such degradable packaging materials, films obtained from blends of low-density polyethylene and starch are currently used in some cases.

[Problem to be solved by the invention]

Films obtained from blends of low-density polyethylene and starch described above have a low degree of biodegradation of the starch portion of about 110°C, which is low, and have poor heat resistance, so their use as packaging materials is limited. in this way.

Films obtained from low-density polyethylene blended with starch do not have sufficient properties such as degradability, transparency, and heat resistance. Currently, there is a demand for packaging materials having these properties.

An object of the present invention is to provide a container that has excellent mechanical properties, transparency, and heat resistance, and is degradable over time.

[Means to solve the problem]

The present inventors have discovered that a container that has excellent mechanical properties, transparency, and heat resistance, and that decomposes in the air, soil, or water in a relatively short time can be obtained from a polymer having a tetrahydrofuran skeleton. Ta.

According to the present invention, the above object is distantly related by providing a container consisting of a polymer whose main chain consists essentially of the following repeating units (I):

(In the formula, R1, B2.B3.B4.B!+ and R6 each represent a hydrogen atom or a lower alkyl group.

) R1, FL2, FL in the above repeating unit (I)
3, H, 4°R5 and R' (hereinafter referred to as R1-6)
The lower alkyl groups represented by
Examples include methyl group, ethyl group, propyl group, inglovir group, and butyl group. It is preferable that FL1-6 represent a hydrogen atom or a methyl group, all of R1-6 represent a hydrogen atom, and any one of R1-6 represents a methyl group, and all others represent a hydrogen atom. It is better to express . Preferred polymers in the present invention include those having the following repeating units.

The polymer in the present invention has a polystyrene-equivalent number average molecular weight of s, o determined by gel permeation chromatography (hereinafter referred to as GPC).
Those within the range of oo to 200,000 are preferred. In the case of a polymer with a number average molecule f as small as s, ooo, the mechanical properties of the obtained container are not sufficient, and 2
In the case of a polymer larger than 0.00,000, the moldability when molding a container becomes insufficient, which is not preferable in either case.

In addition, the polymer in the present invention has the above repeating unit (I
) may have only one type of repeating unit <,
Moreover, it may have two or more types of repeating units. Also,
The polymer in the present invention may contain other structural units within a range that does not impair its properties.

Depending on necessity, various additives such as plasticizers, lubricants, antistatic agents, antioxidants, and ultraviolet absorbers may be present in the polymer.

The polymer in the present invention is 2,3-dihydrofuran represented by the following symbol (II). It can be produced by subjecting the compound or its derivative to a known cationic polymerization reaction in the presence of a suitable initiator.

(In the formula, B1 to B6 are as defined above.) Examples of the initiator used in producing the polymer in the present invention include protonic acids such as hydroiodic acid; metals such as chromium oxide and molybdenum oxide; Oxides: iodine, bromine, iodine bromide, and other boron halides; boron trifluoride, boron trifluoride ether complex, and other boron halides; aluminum chloride, aluminum bromide, titanium tetrachloride, titanium tetrabromide , tin tetrachloride, iron trichloride, etc.; organometallic compounds such as ethylaluminum dichloride, diethylaluminum chloride, diethylaluminium chloride, diethylzinc; triphenylmethylantimony hexachloride, triphenylmethyltinpentachloride Examples include carbonium ion salts such as The initiator is used in an amount ranging from 0.01 to 10 mol, preferably from 0.05 to 2 mol, relative to 2,3-dihydro7rane or its derivative.

The polymerization temperature is in the range of -200°C to 100°C,
Preferably, a temperature in the range of -100°C to 50°C is employed. The polymerization reaction is usually performed under an inert gas atmosphere such as nitrogen, argon, helium, or the like. Although the polymerization can be carried out in the absence of a solvent, aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylenium; hexane, heptane,
Removal of the heat of reaction is carried out in the presence of a solvent such as aliphatic hydrocarbons such as octane; alicyclic hydrocarbons such as cyclohexane and cyclooctane; It is favorable in terms of ease of handling of the produced polymer. Depending on the type of initiator used, in addition to the above solvents, ethers such as diethyl ether, shear ether, dioctyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and tetrahtomifuran; methyl acetate, ethyl acetate, and impropyl acetate may be used. The polymerization reaction can be carried out more effectively by appropriately coexisting esters such as , methyl benzoate, and ketones such as acetone, methyl ethyl ketone, and methyl imbutyl ketone. The reaction time is usually selected within the range of 1 second to 100 hours. After reaching the desired degree of polymerization, the reaction is stopped by a known method, and the resulting polymer is isolated and purified.

By subjecting the thus produced polymer to a known film forming method such as a T-die method, a melt extrusion method such as an inflation method, a hot press method, a melt acid casting method, or a calender method, a sifilm casing or A container is obtained by obtaining a sheet and then subjecting the film or sheet to a known molding or processing method. Alternatively, the above-mentioned polymer can be directly formed into a container by subjecting it to a known molding method such as injection molding or extrusion molding. It is preferable that the thickness of the above film or sheet is usually within the range of 5 to 500 μm. The obtained film or sheet can be formed and processed into a container, but in order to improve the mechanical properties of the container, the film or sheet is hot-stretched and then formed into a container. The film or sheet can be combined with other materials to form a container.

Since the molecular weight of the polymer used as the material for the container of the present invention decreases over time, its mechanical strength decreases and it decomposes in a relatively short period of time. Therefore, the containers of the present invention do not pose environmental pollution problems. This rate of decomposition depends on the thickness of the container. ! The rate of decomposition can be controlled by adding suitable antioxidants and/or UV absorbers to the polymer.

The containers of the present invention include boxes, cartons, large bags, cups, bottles,
Containers such as buckets and pots are used for storing or transporting goods or materials, and can be used in the following fields in particular by taking advantage of their characteristics such as transparency, heat resistance, and degradability. .

(I) Fertilizer bags, seed storage bags, seedling capacity pots, and tree planting pots.

(2) Garbage bags and filth bags.

(3) Shopping bags.

(4) Food containers for instant foods, seasonings, edible oils, vegetables, meat, dairy products, sugar, sweets, etc.

(5) Packaging bags or containers for daily necessities such as cosmetics, cigarettes, soap, oxygen absorbers, desiccants, deodorizers, textile products, etc.

(6) Other products include portable hand warmer bags, book covers, and coffins.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.

In addition, the physical property values were measured according to the following method.

(2) Number average molecular weight and molecular weight distribution: Determined by GPC (polystyrene equivalent).

(2) Glass transition temperature: Measured by differential thermal analysis (in nitrogen, heating rate 10°C/min).

■ Tensile strength, tensile modulus and elongation at break: 8゜ttm
A test piece formed to a size of X 20 t'l was measured using a tensile testing machine at a grip distance of 30 mm and a tensile speed of 1 wa for 7 minutes.

(2) Light transmittance: The value at a light wavelength of 400 nm was measured using a spectrophotometer.

Reference Example 1 After the inside of a glass container equipped with a stirring device and having a capacity of 10 fi is sufficiently replaced with dry nitrogen gas, dehydrated heptagonal toluene and dehydrated ethyl acetate 70011 were placed in the container.
and ethylaluminum dichloride in n-hexane solution (concentration: 1 mol/j) and cooled to 0°C. While stirring, 1,400 f of dehydrated 2,3-dihydrofuran was gradually added to the solution over 4 hours. Added to 0℃
After continuing the reaction for 2 hours, 233 trtl of a 1N methanol solution of aqueous ammonia was added to the reaction mixture to stop the polymerization. Next, the mixed solution and toluene 7I!
After mixing, the mixture was added dropwise to methanol 702 and isolated by reprecipitation according to a conventional method to obtain 1.33Of white product. The number average molecular weight of the product was 150.000 and the molecular weight distribution was 1.7.

When the product was dissolved in deuterated chloroform and its NMR spectrum was measured by 1H-NMR, two absorptions occupying equal areas on the spectrum were observed at 1.9 ppm and 3.8 ppm. Regarding these absorptions, the latter can be attributed to methine and methylene protons adjacent to oxygen, and the former can be attributed to other methine and methylene protons.

The product was made into a tetrahydrofuran solution, and a film At7'C with a thickness of 8 μm was prepared on a Teflon sheet, and the infrared absorption spectrum was measured.
, 3-dihydrofuran, the wave number is 910 crI.
Absorption due to -C-O-C- was observed at the positions t-1 and LO60cvr'. Note that the absorption due to the double bond observed at the 1630 cm-' position in the case of 2,3-dihydrofuran disappeared.

From these results, the product is a polymer consisting of the following repeating units: 45.2.3-dihydrofuran without opening its 5-membered ring, and the glass transition temperature of this polymer is 140 at the endocyclic double bond. It was ℃.

Reference Example 2 In Reference Example 1, 2,3-dihydrofuran 1.4002
Instead of υ, 2,3-dihydrofuran 98o2 and 2゜3-
The polymerization reaction and isolation operation were carried out in the same manner except that a mixture of dihydro-2,2-dimethylfuran 420f was charged, thereby producing s1. :340y white product was obtained. Analysis of this product by IH-NMR revealed that the product was a polymer consisting of the following repeating units (DI) in an amount of 68% and repeating units (IV) in an amount of more than 32% by weight, and the glass transition temperature of this polymer was 152°C.

Example 1 The polymer synthesized in Reference Example 1 was heated at 280°C using a hot press molding machine (manufactured by Shinto Metal Industries) at 50 to 9/crA to 100.
It was formed into a film with the size of se1005e cod x 0.2cm. Next, the film was stretched 2 times vertically and 2 times horizontally at 150° C. using a biaxial stretching device (Toyo Seiki Seisakusho, ×6H type).
Biaxial stretching was performed at a speed of 5 m 7 minutes to obtain a stretched film with a thickness of 49 μm. This film had a smooth surface, a light transmittance of 89%, and good transparency. The tensile strength of the film is K9/mj, the tensile modulus is 317 Ky/-1, the elongation at break is 7.0%, and f
The mechanical properties were measured in two directions perpendicular to each other, and they were almost the same.

A bag of 8 cm x 5 cm was molded using the above stretched film. The bags were subjected to outdoor exposure tests from May to June, and the test results are shown in Table 1.

Example 2 A degradability test was conducted on a bag molded in the same manner as in Example 1 using a Sunshine Carbon Arc Light Weather-O-meter (
This was done by irradiating the bag surface for a predetermined period of time using a model WE-2 manufactured by Suga Test Instruments.

The test results are shown in Table 1.

Example 3 Using a stretched film formed in the same manner as in Example 1, a 7 cm x 7 cm x 5 cm pot for raising seedlings was formed. After the pot was buried in the soil for three months, when it was taken out, it was found to have fallen into pieces.

Example 4 To the polymer 10y synthesized in Reference Example 1, 0.1f' of tetrakis[methylene-3-(3,5-di-tert-butyl-4'-hydroxyphenyl)propionate comethane] was stirred with a mixer. The mixture was added to the resin, molded in the same manner as in Example 1, and then stretched to obtain a film. This film had a smooth surface, a light transmittance of 90 or better, and good transparency. The tensile strength of the film is 7.
9 ky/ad, tensile modulus was 320-/-1, and elongation at break was 7.2. The mechanical properties were measured in two directions perpendicular to each other, and they were almost the same.

A bag was formed using the above film in the same manner as in Example 1, and the iron degradability test was conducted in the same manner as in Example 1.

The test results are shown in Table 1.

Example 5 Using the polymer synthesized in Reference Example 2, a bag was obtained in the same manner as in Example 1. The iron degradability test was conducted in the same manner as in Example 1. The test results are shown in Table 1.

1st Example Test Time Light Transmittance (Salary) Tensile Strength C/-) Example 1 0 days 30 days 50 days 89 7.843
3.7 Cracks occur and cannot be measured Example 2 Cracks occur and cannot be measured for 0 hours 50 hours 100 hours Example 4 0 days 30 days 50 days Example 5 0 days 30 days 50 days 6.7 4°7 Cracks occur [Effects of the Invention] According to the present invention, a container is provided that has excellent mechanical properties, transparency, and heat resistance, and is degradable over time.

Claims (1)

[Claims] A repeating unit (I) whose main chain is substantially the following: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R^1, R^2, R^3, R^ 4, R^5 and R^6 each represent a hydrogen atom or a lower alkyl group).