JPS63284232A - Spontaneously degradable sheet or molding - Google Patents

Abstract

PURPOSE:To obtain a sheet or molding which can disappear spontaneously by hydrolysis, biodegradation or the like, by bonding vegetable fine fiber, particles or the like to a polyurethane resin comprising an ester group-containing polyol and an organic polyisocyanate. CONSTITUTION:A polyol having at least one ester group in the molecule (e.g., a polyester polyol synthesized from diethylene glycol and adipic acid) is mixed with an organic polyisocyanate (e.g., diphenylmethane diisocyanate) and fine fibers and/or particles of vegetable (e.g., rice hulls or wood flour). The mixture is poured into a mold and subjected to pressure and heat to form a urethane resin to which the vegetable fibers, particles or the like are bonded and simultaneously mold it. In this way, a sheet or molding is formed. When this sheet is left standing in the natural world, it disappears by hydrolysis or biodegradation in soil or the like, so that it does not pollute environment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a degradable sheet or molded product that disappears due to hydrolysis or biodegradation in the soil when left in nature.

[Problems to be Solved by the Prior Art and Inventions] When waste plastics are burned after they have been used, there are problems such as generation of toxic gas and damage to the combustion furnace. Another problem is that when disposed of without being burned, it often remains undecomposed for a long time.

On the other hand, if you grow vegetable or tree seedlings in plastic or ceramic pots, you will need to move them from the plastic or ceramic pot at certain times, but this is time-consuming and can damage the roots of the plants. There are problems such as inhibiting the growth of seedlings.

[Means for Solving the Problems] The present invention can be completely removed even if it is left in nature or buried in the soil because it is hydrolyzed by rainwater or broken down by bacteria. It is a urethane resin obtained by the reaction of a polyol containing at least one ester group in its molecule and an organic polyisocyanate, and is made from vegetable fine fibers. and/or relating to sheets or molded products that decompose in nature and are made by bonding vegetable powder particles.

[Example: Vegetable fine fibers and/or vegetable powder (hereinafter referred to as vegetable fine fibers, etc.) used in the present invention]
Examples include, but are not limited to, rice husk, rice husk smoked charcoal, wheat husk, buckwheat husk, rice straw, rice bran, bean cake, wood flour, wood shavings, and vegetable fiber waste. These may be used alone or in combination of two or more.

In the present invention, the above-mentioned inexpensive by-products, plant fine fibers such as waste, etc. that have little use can be effectively utilized as raw materials.

Polyols containing at least one ester group in the molecule used in the present invention include adipic acid, phthalic acid,
Dibasic acids such as dimer acid and ethylene glycol,
Polyols obtained by condensation and dehydration reaction with low molecular weight polyols such as 4-butanediol, trimethylolpropane, and glycerin; polycaprolactones obtained by ring-opening polymerization of ε-caprolactone;

Polycarbonate polyols obtained by the reaction of glycols such as 6-hexanediol with phosgene or ethylene carbonate, castor oil, alkylene oxide adducts of castor oil, transesterified products of castor oil and polyhydric alcohol, castor oil Partially acylated products of castor oil, castor oil derivatives such as partial oxides of castor oil, esterified products of ricinoleic acid and polyhydric alcohol, addition of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, etc. alone or in combination to the above-mentioned ester-containing polyols. Examples include, but are not limited to, things.

These may be used alone or in combination of two or more.

The number average molecular weight of the polyol is 300 to 100
．． 000 is preferable from the viewpoint of moldability, physical properties, etc. of the molded article, and t, ooo to 10. (About 100 is more preferable.

Examples of the organic polyisocyanate used in the present invention include tolylene diisocyanate (TDI), diphenylmethane diisocyanate, xylene diisocyanate, polyphenylpolymethylene polyisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate (hydrogenated MDI). Examples include, but are not limited to, polyisocyanate adducts of lower alcohols. These may be used alone or in combination of 28 or more.

In the present invention, the urethane resin obtained by the reaction of the polyol and the organic polyisocyanate is used as the binder, but when using the urethane resin as the binder, the method of directly reacting the polyol and the organic polyisocyanate ( It may be produced and used by a one-shot method (one-shot method), or it may be produced by reacting the polyol with an organic polyisocyanate in advance (by a prepolymer method).
It may be used after producing the terminal NCO urethane prepolymer.

When producing the urethane resin or prepolymer, only the polyol and the organic polyisocyanate may be reacted, but the polyol may be reacted with a polyoxyalkylene polyol other than the polyol, a polyether polyol such as polytetramethylene glycol, water, Furthermore, 4
A crosslinking agent such as amines such as 4°-methylenebis(2-chloroaniline), diaminodiphenylmethane, and hydrazine may be mixed or used in combination. Furthermore, when curing the prepolymer, it may be cured with moisture or excess water.

There are no limitations on the ratio of these active hydrogen compounds to the polyisocyanate, but NC01011 is generally used at a blending ratio close to 1.0 in terms of equivalent ratio.

The amount of urethane resin used is 100 parts such as vegetable fine fiber (
It is preferably 1 to 100 parts by weight (the same applies hereinafter),
More preferably 5 to 30 parts.

It is generally preferable to mix the urethane resin and the vegetable fine fibers before curing the urethane resin, and the polyol used in the present invention may be blended with the vegetable fine fibers in advance. It may be mixed simultaneously with the polyisocyanate. However, if the urethane resin is thermoplastic, the urethane resin may be melted and vegetable fine fibers etc. may be kneaded into the molded material, and the present invention is not limited thereto.

Mixing these urethane resins with vegetable fine fibers, etc.
It may be carried out at room temperature or under heating, and is usually carried out at 0 to 200°C, preferably 10 to 150°C.

When mixing the vegetable fine fibers, etc., inorganic fillers, plasticizers, colorants, catalysts, and other additives may be further added.

The mixture of the vegetable fine fibers etc. prepared in this way and the urethane resin or the composition to become the urethane resin is continuously formed into a sheet by a belt conveyor, for example, in order to be formed into a desired size and shape. or molded under normal pressure or pressure in a mold made of metal, plastic, wood, concrete, etc., to form the sheet or molded product of the present invention.

The sheet or molded product of the present invention is manufactured using vegetable waste such as wood flour and rice husks as its main ingredients, and a special urethane resin as a binder, so it can be used for flower pots, seedling boxes, fish boxes, nursery beds, etc. Even if it is disposed of afterwards, it will completely disappear in the natural world and will not cause any pollution problems. In addition, when used as a flower pot or seedling box, the pot used for growing the seedling can be buried in the soil, so there is no need to replant the seedling from the pot into the soil, improving work efficiency and allowing the seedlings to grow. It does not damage the plants or inhibit the growth of seedlings.

In addition, after being decomposed in the soil, since the main component is vegetable fiber and the urethane resin contains nitrogen, it remains effective even after it has disappeared, such as acting as a fertilizer.

Next, the sheet or molded article of the present invention will be explained in more detail based on production examples, comparative production examples, working examples, and comparative examples.

Production Example 1 Polyester polyol synthesized from diethylene glycol and adipic acid (average molecular weight approximately 3000.0) IV
Approximately 37.4) 100 parts of methyl ethyl ketone and ground powder discharged from a factory that saws logs of cedar and cypress (moisture content 3.1%, passing through 60 meshes is 20% (wt%)
, the same applies hereafter), 60-52 meshes 6.7%, 52-52 meshes
5.3% passed 48 meshes, 68% did not pass 48 meshes.
After pre-mixing 1000 parts of wood flour (wood flour with particle size of
Mix 4.7 parts at room temperature (20℃), pour into an aluminum mold, press at a pressure of 5kg/C112, 80℃ for 30 minutes to form a mold with a length of 1100e s width of 30cm and a thickness of 2.5 cm.
A molded article with a density of +as and a density of 0.63 g/am3 was produced.

Production Example 2 A polyester polyol (average molecular weight approximately 1200) obtained from phthalic acid and 1,4-butanediol is subjected to an addition reaction with ethylene oxide to obtain an average molecular weight approximately 3800.0II
A polyester-bolyether polyol of about 29.5 V was obtained.

3 parts of methyl ethyl ketone was added to 55.7 parts of the obtained polyol.
After adding 0 parts, add 3 parts of TDI-8014 and 3 parts at 90℃.
After reaction time, a prepolymer with a free NGO content of 8.0% was obtained.

After mixing 100 parts of this prepolymer with 300 parts of water, 200 parts of wood flour and 200 parts of rice husk charcoal used in Production Example 1 were mixed within 1 minute, and the mixture was spread on a polypropylene sheet at room temperature (20°C). Made into a sheet. Then at room temperature 4
The sheet obtained by drying at 50℃ for 24 hours,
Thickness 5Il1111 Area 0.54g, Density OJ8g/c
It was "m".

Production Example 3 22.5 parts of ricinoleic acid ester (OIIV about 98.0) of polyethylene glycol (molecular weight about 600) and ethylene oxide (a (1%), propylene oxide (20%)) random addition polyol of glycerin (OIIV about 2
1.5) Dissolve 22.5 parts in 40 parts of methyl ethyl ketone to obtain crude MDI (NGO content 31.5%) 14.
9 parts were reacted at 90°C for 3 hours, and the free NGO content was 4.
3% prepolymer was obtained.

A solution of 100 parts of this prepolymer in 100 parts of acetone was mixed with 100 parts of the same wood flour and 100 parts of wheat husk as used in Production Example 1, placed in a Teflon-coated mold, and heated under a gauge pressure of 2. Spray water vapor at .0 atm for about 3 minutes and dry at 50°C for 5 hours to a thickness of 30aa+, ratio ff! I got a foam block of 0.25.

Production Example 4 Polycaprolactone polyol (average molecular weight approximately 2000
) 70 parts of diethylene glycol, 22.3 parts of diethylene glycol, 0.2 parts of trimethylolpropane, 6.5 parts of dimethylolpropionic acid and 65 parts of isophorone diisocyanate in acetone. It was added to water and emulsified.

300 parts of the obtained urethane aqueous dispersion (solid content 30%) and 2000 parts of rice husk smoked charcoal (water content 4.2%) were mixed and molded in the same manner as in Production Example 1 to a density of 0.41 g/cm'. I got the goods.

Comparative Production Example 1 A molded product with a density of 0.44 g/cm" was produced in the same manner as Production Example 4, except that a vinyl acetate resin emulsion (resin content 50%) was used instead of the urethane aqueous dispersion used in Production Example 4. I got it.

Comparative Production Example 2 Polyoxypropylene glycol (average molecular weight approximately 200
0) 100 parts of urethane prepolymer (free 1vNCO content 3.7%) obtained by reaction of 95 parts of polyoxypropylene triol (average molecular weight approximately 260) with 5 parts of TDI-8021, 4.4-methylene bis (2
-Chloroaniline) dissolved in 60 parts of polyoxypropylene glycol (average molecular weight approximately 2000), 100 parts of xylene, and 1000 parts of the same powder used in Production Example 1 were mixed. Similarly, the density is 0.
A molded product weighing 71 g/cm3 was obtained.

Example 1 The molded articles obtained in Production Examples 1 to 4 and Comparative Production Examples 1 to 2 were evaluated by the following method, and changes thereof were investigated. The results are shown in Table 1.

(Test method) Wet grassy soil was collected in a plastic container, the molded product was buried in it, a flask filled with water was left in an oven in the space above the soil, the plastic container was sealed, and the container was sealed for 30 minutes. The molded product was placed in a constant temperature room at ℃ and kept under constant temperature and humidity conditions for two years, and the specimens were taken out at regular intervals to determine the tensile strength of the molded product.
The presence or absence of microorganisms was observed.

The soil conditions are as follows: Moisture rate = 45-46% pH: 5.95 Cells: Bacteria (albumin agar) 4.5 The main bacteria are Eubaeterale S, Ps
EudoIlonades was present, and the filamentous fungi were mainly Deuteromycota, Basidiomycetes, and Streptococcus algae.

Example 2 A molded article was exposed for 500 hours using a sunshine weatherometer, and the rate at which a part of the molded article fell off (weight percentage) was measured. The results are shown in Table 1.

[Margins below] [Effects of the Invention] When the sheets, mats, or molded products of the present invention are left in nature, they disappear through hydrolysis or biodegradation in the soil, and do not cause pollution like conventional plastics.

Claims (1)

[Claims] 1. A urethane resin obtained by the reaction of a polyol containing at least one ester group in its molecule and an organic polyisocyanate, and a sheet that decomposes in nature, made by bonding vegetable fine fibers and/or vegetable powder. or molded products.