JP2860883B2 - Degradable resin molded product - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a polyvinyl alcohol resin, cellulose particles and a polyhydric alcohol.
The present invention relates to a molded article formed from a composition that is decomposed in a natural environment such as soil or seawater. [0002] Molded articles made of synthetic polymers have been used in a very wide range of fields to date because of their excellent mechanical properties and high economic efficiency. However, in recent years, because of the durability and weather resistance, which are the most useful characteristics of the synthetic polymer molded article, it has become a serious problem that the environment is degraded due to the disposal of used resin molded articles. Became. To cope with this problem, to date, polyesters produced by microorganisms and aliphatic polyesters produced by synthetic methods have already been put to practical use. However, these still have the disadvantage that they are economically expensive and require a long time for biodegradation. On the other hand, among synthetic polymers, packaging films
Polyvinyl alcohol resin which is widely in equal, Pseudomonas putida (Pseudomonas pu
tida) to be degraded by certain microorganisms, such as
It has been reported in research, but is universally used in soil, rivers and seawater.
Not easily degraded by inhabiting microorganisms. Especially for molded products such as films and bottles made of polyvinyl alcohol resin, the surface of the molded product usually becomes rough even after one year in the environment such as soil or seawater, and bacteria may Although there is a change in appearance due to adhesion, the molded article itself is unlikely to collapse or decompose. As described above, since it takes a very long time to disintegrate or decompose a polyvinyl alcohol-based resin, various compositions for promoting the biodegradability of the polyvinyl alcohol-based resin have been conventionally proposed. . For example, JP-A No. 2-15
JP 1639 discloses a polyvinyl alcohol-starch film comprising polyvinyl alcohol and starch and stretched in at least one direction, and JP-A-3-79645 discloses a composition comprising a polyvinyl alcohol resin and a modified starch. However, JP-A-6-200108 discloses a composition of a polyvinyl alcohol-based resin and gluten, but a molded article made from the composition has poor water resistance and heat resistance, and has a short biodegradation time. All were unsatisfactory because they were longer than necessary. [0004] The present invention has been made to solve the above problems of the prior art,
An object of the present invention is to provide a resin molded article having excellent moldability, good mechanical strength, and biodegradability. Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result of repeated studies, have found that a molding obtained from a composition obtained by adding cellulose particles to a polyvinyl alcohol resin is used. It has been found that the product is accelerated to disintegrate in the environment such as ordinary soil or seawater, and the decomposition time can be significantly reduced. Cellulose is a natural macromolecule, which is decomposed by microorganisms and incorporated into the natural circulation system.However, since it alone was not physically or chemically durable, it was used in combination with other macromolecular substances. For example, attempts have been made to make a blend with chitin or a modified cellulose, but the degradability is satisfied, but the physical properties of the molded product are not yet sufficient. Polyvinyl
By suppressing the particle size of the cellulose particles added to the alcohol-based resin and adding polyhydric alcohol, the moldability of the polyvinyl alcohol-based resin and the excellent biodegradability without substantially impairing the mechanical properties of the molded product are improved. Achieved
Things . That is, the present invention is characterized by adding a cellulose alcohol having a particle size distribution specially prepared to a polyvinyl alcohol-based resin and a polyhydric alcohol, and cellulose particles having a particle size of 50 μm or less.
This is a biodegradable composition in which 300 parts by weight and 10 to 100 parts by weight of a polyhydric alcohol having a plasticizing effect on a polyvinyl alcohol-based resin are mixed and dispersed in 100 parts by weight of a polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin used in the present invention may be any vinyl alcohol-based polymer mainly composed of vinyl alcohol-based resin units, but preferably has an average polymerization degree of 500 to 2,500 and a polydispersity of 1.0 to 1.0.
2.5, those having a vinyl alcohol resin unit of 15 mol% or more and a saponification degree of 75 mol% or more are preferred. As the cellulose particles in the present invention, a particle diameter of 50 μm
When larger cellulose particles are used, not only the moldability is impaired, but also the mechanical properties of the molded article are significantly reduced, so that the particle diameter is 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less. Cellulose particles are suitable. The particle diameter here is, needless to say, a diameter if the cellulose particles are spherical, but in the case of a columnar shape, a similar shape thereof, or when there are a short diameter and a long diameter, the particle diameter means a long diameter. I do. If the added amount of the cellulose particles is less than 10 parts by weight, the disintegration of the molded article obtained from the resin composition is extremely slow, and it takes a long time to decompose, and if it is more than 300 parts by weight, the moldability is significantly deteriorated. However, the mechanical properties of the molded article are extremely lost. As the cellulose particles satisfying the above conditions, for example, finely selected wood pulp is separated into short fibers, dried and mechanically pulverized to the limit by a dry ball mill.
The amorphous portion of the cellulose raw material such as pulp or cotton linter was hydrolyzed with a mineral acid, collapsed, washed with water, dried and then pulverized microcrystalline cellulose, and the microcrystalline cellulose suspension was treated with a high-pressure homogenizer. Thing, cellulose fine powder obtained by exploding a delignified cellulose material, and acid hydrolysis, alkali oxidative decomposition, enzymatic decomposition, steam explosion decomposition,
Subjected to depolymerization processes steam cooking, ceramics or gold this
Microcellulose which is wet-pulverized by forcible stirring in a container together with a pulverizing medium such as metal beads may be used. The polyhydric alcohol used in the present invention has the effects of improving the plasticity and processability of the obtained resin composition, and further improving the flexibility of the molded product as well as the biodegradability. Preferred polyhydric alcohols for this purpose include glycerin, diglycerin, polyglycerin, ethylene glycol, diethylene glycol, propylene glycol, pentaerythritol,
Examples include glycerol monoacetate, sorbitol, polyethylene glycol, polypropylene glycol, and poly (ethylene-propylene) glycol. Also,
If the amount of the polyhydric alcohol is less than 10 parts by weight, the moldability is remarkably deteriorated, the mechanical properties of the molded article are extremely lost, and the biodegradability is significantly delayed. Conversely 100
When the amount is more than the weight part, the moldability becomes good, but the water resistance and mechanical properties of the obtained molded article are remarkably deteriorated, so that it cannot be used practically. The resin composition of the present invention comprises the above-mentioned polyvinyl alcohol-based resin, cellulose powder and polyhydric alcohol. The resin composition may further include a filler, a lubricant, a modifier, Foaming agent, extender, flow accelerator, release agent, dispersion stabilizer, anti-blocking agent,
A coloring agent or the like can be prepared and added according to the purpose of use. In the resin composition of the present invention, the aqueous solution is formed by slitting .
Ri also to be able to film formation by casting, dried to an aqueous solution casting method on the thermal drum, also known extruder, an injection molding machine, hot press molding machine, blow molding machine, inflation molding machine, T-die Molded products such as films, sheets, various injection molded products, and various containers can also be obtained by a cast molding machine or the like. The present invention will be described in more detail with reference to the following Examples, which do not limit the scope of the present invention. The measurement of the mechanical properties and the biodegradability test of Examples and Comparative Examples were evaluated by the following methods. As a measurement of the mechanical properties of the film, the film was cut into a strip having a sample width of 15 mm and a length of 200 mm, and a chuck interval of 100 mm and a tensile speed of 100 mm / m were measured using a tensile tester.
In, the strength and elongation at break were measured. For the biodegradability test of the molded product, the sample was 50 mm x 50 mm.
mm, hold it with a 20-mesh wire mesh and bury it in the soil (depth about 15 cm) in Toyohashi City, Aichi Prefecture, or immerse it in the seawater (water depth about 50 cm) at Toyohashi Port in Aichi Prefecture for one year Observe the decomposition state of the molded article afterwards, and
Expressed as area percentage relative to the original sample . Example 1 Shimadzu laser diffraction type particle size distribution analyzer (S
ALD-1100) is 3.5μ.
After sufficiently dispersing 50 parts by weight of cellulose particles (microcrystalline cellulose manufactured by Asahi Kasei Corporation, CEOLUS CREAM FP-03) in warm water at 90 ° C., the average degree of polymerization was 1,650 and the degree of polydispersity was 2.0.
4.Polyvinyl alcohol resin with saponification degree of 99.6mol%
(Unitika Chemical, UV) 100 parts by weight were added and dissolved. After dissolution, 30 parts by weight of glycerin (manufactured by Wako Pure Chemical Industries) was added as a polyhydric alcohol, and the mixture was sufficiently stirred and mixed. The aqueous solution was cast from a slit on a drum maintained at 90 ° C. and dried by blowing hot air at 90 ° C. to obtain a uniform film having a thickness of 50 μm. Table 1 shows the mechanical properties of the film and the results of the biodegradation test. Example 2 Cellulose particles having an average particle diameter of 6.0 μm
(Asahi Kasei crystalline cellulose, Avicel PH-M06) 20
After thoroughly dispersing 0 parts by weight in warm water at 90 ° C., 100 parts by weight of a polyvinyl alcohol-based resin (manufactured by Shin-Etsu Chemical, SN) having an average degree of polymerization of 1,650, a polydispersity of 2.04, and a saponification degree of 99.6 mol% are added. Dissolved. After dissolution, 50 parts by weight of diglycerin (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a polyhydric alcohol, and the mixture was sufficiently stirred and mixed. The aqueous solution was cast from a slit on a drum held at 90 ° C, and dried by blowing hot air at 90 ° C.
A uniform film having a thickness of 50 μm was obtained. Table 1 shows the mechanical properties of the film and the results of the biodegradation test. Example 3 Extrusion grade flake-like polyvinyl alcohol resin having a polymerization degree of 1,500 and a saponification degree of 78 mol% (manufactured by Kuraray, SV-217) has an average particle diameter of 100 parts by weight of 6.0 μm.
m cellulose particles (Asacel Kasei Chemical Cellulose, Avicel PH-M06) (50 parts by weight) and polyethylene glycol having an average molecular weight of 400 as a polyhydric alcohol (manufactured by Sanyo Chemical Co., Ltd.).
0 parts by weight blended, screw diameter 50mm, L / D = 26
Was melt-kneaded with a single-screw extruder having a single-flight type screw, made into a strand from a pellet die at the tip of the extruder, cut into a pellet with a diameter of 2.0 mm and a length of 5.0 mm with a pelletizer. The above pellets are 600mm
Extruded from a film forming apparatus with a T-die of width,
A 0.2 mm sheet was obtained. Table 1 shows the mechanical properties and biodegradation test results of the sheet. EXAMPLE 4 The pellets prepared in Example 3 were blown using a blow molding machine to have a side surface thickness of 1.0 mm and a bottom surface thickness of 2.0 m.
m, a bottle with an internal volume of 500 mL was molded. Table 1 shows the biodegradation test results of the bottle. Comparative Example 1 Degree of polymerization: 1,650, degree of polydispersity: 2.04, degree of saponification: 9
100 parts by weight of a 9.6 mol% polyvinyl alcohol resin (manufactured by Unitika Chemical, UV) was dissolved in warm water at 90 ° C., and 30 parts by weight of glycerin (manufactured by Wako Pure Chemical Industries) was added as a plasticizer, followed by sufficient stirring. The aqueous solution was cast on a drum maintained at 90 ° C. from a slit and dried to obtain a uniform film having a thickness of 50 μm. Table 1 shows the mechanical properties of the film and the results of the biodegradation test. Comparative Example 2 When observed with a scanning electron microscope, 75 μm was observed.
Cellulose powder containing a large amount of cellulose particles having a particle diameter of at least m (Sanyo Kokusaku Valve, Valve Floc W-
1) After fully dispersing 200 parts by weight in warm water at 90 ° C,
Polyvinyl alcohol resin having a polymerization degree of 1,650, a polydispersity of 2.04, and a saponification degree of 99.6 mol% (manufactured by Unitika Chemical Co., Ltd.
V) 100 parts by weight were added and dissolved. After dissolution, 50 parts by weight of diglycerin (manufactured by Tokyo Chemical Industry) was added as a polyhydric alcohol, and the mixture was sufficiently stirred. The aqueous solution was cast on a drum maintained at 90 ° C. through a slit and dried to obtain a film having a thickness of 50 μm. Table 1 shows the mechanical properties of the film and the results of the biodegradation test. [Table 1] As described above, the biodegradable resin composition of the present invention exhibits good moldability and the molded article has good mechanical properties, but the molded article obtained from this resin composition is When placed in an environment such as soil or seawater, it has a remarkable effect that it is broken down by microorganisms and loses its shape and strength remarkably.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification code FI (C08L 29/04 1:00) (58) Field surveyed (Int.Cl. ⁶ , DB name) C08L 29/04 C08L 1 / 00-1/32 C08K 5/053

Claims (1)

(57) [Claim I] (A) Polyvinyl alcohol resin 10
0 parts by weight, (B) 10 to 300 parts by weight of cellulose particles having a particle diameter of 50 μm or less, (C) 10 to 50 polyhydric alcohols
Soil / seawater easily degradable resin molded product consisting of parts by weight .