JPH11279271A - Method for manufacturing resin pellets - Google Patents

Abstract

(57) [Problem] To provide a method for producing pellets for imparting excellent moldability using a lactone resin having a good balance of decomposability, moldability, and mechanical properties. SOLUTION: The method for kneading and extruding a resin composition obtained by mixing a resin additive with a lactone-containing resin composed of polycaprolactone and another biodegradable resin to form a strand, and cutting the strand into pellets, Radiation irradiation treatment is performed so that polycaprolactone, which is a component of the lactone-containing resin, has a gel fraction of 10% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing resin pellets for molding. More specifically, the present invention relates to a method for producing biodegradable resin pellets, in which a lactone resin is subjected to a radiation irradiation treatment at a pellet or its production stage.

[0002]

2. Description of the Related Art Conventionally, synthetic plastics such as polyolefin, polyvinyl chloride, polystyrene, polyamide, and polyester have been used as household goods, agricultural, marine, and general industrial materials. Because it is stable and hardly decomposes after being used and disposed of in the natural world, its disposal has become a social problem. As a countermeasure for this, various biodegradable resins have been proposed, and alternatives to the above resins have been studied. Here, the biodegradable resin is not biodegraded like polyethylene etc. while the molded article is used in general living environment, but when it is disposed and buried in activated sludge, soil, compost, etc., Biochemically quickly by microorganisms such as bacteria and mold,
Some resins decompose into carbon dioxide and water. Specific examples of the biodegradable resin include aliphatic polyesters such as poly-ε-caprolactone, polyhydroxybutyrate / polyhydroxyvalerate copolymer, and polylactic acid, and modified starch / modified polyvinyl alcohol (PVA) composition. And carbonyl group-containing photodegradable polymers. Of these, aliphatic polyesters such as poly-ε-caprolactone, polyhydroxybutyrate / polyhydroxyvalerate copolymer, and polylactic acid have received the most attention because they are completely biodegradable.

JP-A-8-188706 discloses a biodegradable resin, poly-ε-caprolactone (hereinafter sometimes abbreviated as polycaprolactone, PCL).
100% by weight of a mixture of 100% by weight and 20 to 0% by weight of a biodegradable linear polyester resin produced by living organisms
A biodegradable plastic film obtained by molding a composition comprising 0.3 to 0.8 parts by weight of a lubricant with respect to parts by weight is disclosed, but there is a problem in mechanical strength during film formation. Not only is it difficult to mass-produce the film, but also when the film is put into a composting device together with garbage, it takes 100 days for the biochemical decomposition of the film, so the decomposition rate can be said to be sufficiently fast. Absent.

[0004] Also, JP-A-8-11206 discloses that
Proposals have been made to use downward dies for inflation film formation of biodegradable resin, but there is no solution to the problem based on the characteristics of the biodegradable resin itself, only by lowering the extrusion direction. Therefore, it has not been a fundamental solution to the problem in inflation film formation of a biodegradable resin. Japanese Patent Application Laid-Open No. 8-150658 discloses heat sealability, mechanical strength, and the like using a composition comprising a biodegradable aliphatic polyester and a saponified ethylene-vinyl acetate copolymer, starch and a plasticizer. Although a method of forming an inflation film having excellent moisture resistance and the like is disclosed, since a biodegradable ethylene-vinyl acetate copolymer saponified compound is present, some of the biodegradable properties are sacrificed. This is not a disclosure of a solution to the above problem. As described above, there is no known biodegradable resin having a good balance of degradability, moldability, and mechanical properties.

When a molded article is produced using a resin, the resin or the resin composition is usually formed into pellets. The production of resin pellets for molding is usually to avoid bridging when powder is supplied to a molding machine in the form of fine powder, scattering of powder in the air, etc., and enables molding under uniform mixing with additives. In addition, it is used as a countermeasure against the problem of fine powder generated at the time of pulverizing and reusing waste molded products.

[0006]

Accordingly, the present invention provides a method for producing a lactone resin-containing pellet for imparting excellent moldability by using a resin having a good balance of decomposability, moldability and mechanical properties. It seeks to provide a way.

[0007]

Means for Solving the Problems The present inventor has conducted intensive studies to solve the above-mentioned problems, and as a result, the lactone resin alone,
In a mixture of a lactone resin and another biodegradable resin or in a pellet of a composition of the same and a resin additive, after the raw material stage or pelletization, by performing a specific radiation irradiation treatment, the production of molding resin pellets Succeeded and completed the present invention. That is, the gist of the present invention is as follows.

A first aspect of the present invention is a resin of a lactone resin (a) alone or a composition of a lactone resin (a) and another biodegradable resin (b) (both are also referred to as a lactone-containing resin (c)). A method for producing a pellet, which comprises a step of irradiating the lactone resin of the resin pellet alone or together with at least one other component with radiation irradiation. A second aspect of the present invention provides the method for producing a resin pellet according to the first aspect, wherein the other biodegradable resin is a synthetic and / or natural polymer. A third aspect of the present invention provides the method for producing a resin pellet according to the second aspect of the present invention, wherein the synthetic polymer is an aliphatic polyester, a biodegradable cellulose ester, a polypeptide, a polyvinyl alcohol, or a mixture thereof. . A fourth aspect of the present invention is that the natural polymer is starch, cellulose, paper, pulp, cotton, hemp, wool, silk, leather, carrageenan, chitin / chitosan, natural linear polyester resin, or a mixture thereof. A method for producing a resin pellet according to a second aspect of the present invention is provided. A fifth aspect of the present invention is that a lactone resin alone or a composition of a lactone resin and another biodegradable resin, which is a pellet raw material, is further subjected to photolysis, a biodegradation accelerator, fine powder particles produced from paper, a plasticizer, Heat stabilizer,
Bulking agents, fillers, lubricants, coloring agents, flame retardants, water resistance agents, auto-oxidants, UV stabilizers, cross-linking agents, antibacterial agents, fungicides, herbicides, antioxidants, droplets, deodorants, A method for producing a resin pellet according to any one of the first to fourth aspects of the present invention, wherein a pellet is produced by adding an antistatic agent or a mixture thereof. The sixth aspect of the present invention is the method according to any one of the first to fifth aspects of the present invention, wherein a radiation irradiation treatment is performed on a pellet raw material, or on a resin strand extruded from a discharge port of an extruder or on a resin pellet after the cut. Provided is a method for producing a resin pellet. A seventh aspect of the present invention is a lactone resin (a).
The present invention provides a method for producing a resin pellet according to any one of the first to sixth aspects, wherein the gel fraction of the resin pellet is in the range of 0.05 to 10%. The eighth aspect of the present invention is that the lactone resin (a) is poly-ε.
-A method for producing a resin pellet according to any one of the first to seventh aspects of the present invention, which is caprolactone.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. The lactone resin (a) used in the present invention has ε
-Caprolactone, 4-methylcaprolactone, 3,
Various methylated caprolactones such as 3,5-trimethylcaprolactone, 3,3,5-trimethylcaprolactone, β-propiolactone, γ-butyrolactone, δ-
Examples include valerolactone, a homopolymer of enantholactone, a copolymer of two or more of these monomers, and a mixture of these homopolymers or copolymers. In particular, those which do not soften at room temperature are preferable, and from this viewpoint, poly-ε-caprolactone having a high molecular weight and a melting point of 60 ° C. or more and which can easily obtain stable performance is preferable. The lactone resin may be copolymerized with a monomer other than the lactone monomer and the lactone monomer, for example, lactic acid, hydroxypropionic acid,
Aliphatic hydroxycarboxylic acids such as hydroxybutyric acid; and aliphatic diols and aliphatic dicarboxylic acids exemplified by the aliphatic polyester described below.

Hereinafter, the lactone resin according to the present invention will be described using polycaprolactone as a typical example. The number average molecular weight of the polycaprolactone before irradiation is preferably from 10,000 to 1,000,000, and particularly preferably from 100,000 to 500,000 from the viewpoint of efficient crosslinking. Polycaprolactone having the above molecular weight has a relative viscosity of 1.15 to JIS K6726.
2.80, particularly preferably 1.50.
~ 2.80.

The lactone-containing resin (c) used in the present invention is a lactone resin (a) alone or a composition of the lactone resin (a) and another biodegradable resin (b). As the other biodegradable resin, a synthetic and / or natural polymer is used. Examples of the synthetic polymer include an aliphatic polyester, a polyamide, a polyamide ester, a biodegradable cellulose ester, a polypeptide, a polyvinyl alcohol, an ethylene-vinyl acetate copolymer, and a mixture thereof. The synthetic aliphatic polyester resin is a polyester resin other than the lactone resin, and is an aliphatic polyester resin obtained by a condensation polymerization system. Hereinafter, the synthetic aliphatic polyester resin is simply referred to as an aliphatic polyester resin, and in the case of a naturally occurring resin, this is clearly indicated. As the aliphatic polyester resin,
Biodegradable polyester resins such as synthetic polylactic acid, polyethylene succinate and polybutylene succinate (such as low molecular weight aliphatic dicarboxylic acid and low molecular weight aliphatic resin represented by Bionole of Showa Polymer Co., Ltd.) Examples thereof include polyester resins synthesized from diols), JP-A-9-235360, and JP-A-9-235360.
And terpolymer aliphatic polyesters described in JP-A-233956, and lactic acid-hydroxycarboxylic acid copolymers described in JP-A-7-177826. The aliphatic polyester resin may be a resin obtained by adding an aliphatic isocyanate such as hexamethylene diisocyanate to a low-molecular-weight aliphatic polyester and reacting the aliphatic polyester with a urethane bond to increase the molecular weight. Examples of the biodegradable cellulose ester include organic acid esters such as cellulose acetate, cellulose butyrate, and cellulose propionate; inorganic acid esters such as cellulose nitrate, cellulose sulfate, and cellulose phosphate; cellulose acetate butyrate, cellulose acetate phthalate, and nitric acid. Hybrid esters such as cellulose acetate can be exemplified. These cellulose esters are
They can be used alone or in combination of two or more. Among these cellulose esters, organic acid esters, particularly cellulose acetate, are preferred. Examples of the polypeptide include polyamino acids such as polyglutamic acid and polymethylglutamic acid, and polyamide esters. Examples of polyamide esters include resins synthesized from ε-caprolactone and ε-caprolactam. As the synthetic polymer, for example, taking an aliphatic polyester resin as an example,
Number average molecular weight is 2 in terms of standard polystyrene by GPC
0000 or more and 200,000 or less, preferably 40,
More than 000 can be used.

As natural polymers, starch, cellulose,
Paper, pulp, cotton, hemp, wool, silk, leather, carrageenan, chitin / chitosan, natural linear polyester resin, or a mixture thereof. Examples of the starch include raw starch, processed starch, and a mixture thereof. As raw starch, corn starch, potato starch, sweet potato starch,
Wheat starch, cassava starch, sago starch, tapioca starch, rice starch, legume starch, kudzu starch, bracken starch, lotus starch, sis starch, and the like. , Moist heat-treated starch, etc.), enzyme-modified starch (hydrolyzed dextrin, enzyme-decomposed dextrin, amylose, etc.), chemically-modified starch (acid-treated starch, hypochlorite-oxidized starch, dialdehyde starch, etc.), chemically-modified starch derivative ( Esterified starch, etherified starch, cationized starch, cross-linked starch, etc.). Among the above, as the esterified starch, acetate-starch, succinate-starch, nitrate-starch, phosphate-starch, urea-phosphate-starch, xanthate-starch, acetoacetate-starch Etc .; etherified starch such as allyl etherified starch, methyl etherified starch, carboxymethyl etherified starch, hydroxyethyl etherified starch and hydroxypropyl etherified starch; etc .; cationized starch includes starch and 2-diethylaminoethyl chloride , A reaction product of starch and 2,3-epoxypropyltrimethylammonium chloride, etc .; Examples of the crosslinked starch include formaldehyde crosslinked starch, epichlorohydrin crosslinked starch, phosphoric acid crosslinked starch, and acrolein crosslinked starch.

In the present invention, the lactone-containing resin composition comprises a lactone-containing resin (c) and a resin additive (d). As a resin additive, a plasticizer, a heat stabilizer, a lubricant, an antiblocking agent, a nucleating agent, a photolytic agent, a biodegradation accelerator, an antioxidant, an ultraviolet stabilizer, an antistatic agent, a flame retardant, a dropping agent,
Examples include antimicrobial agents, deodorants, fillers, colorants, or mixtures thereof.

Examples of the plasticizer include aliphatic dibasic acid esters, phthalic acid esters, hydroxy polycarboxylic acid esters, polyester plasticizers, fatty acid esters, epoxy plasticizers, and mixtures thereof. Specifically, di-2-ethylhexyl phthalate (DOP), dibutyl phthalate (DBP), diisodecyl phthalate (D
Phthalic acid esters such as IDP), adipic acid-di-2-
Adipates such as ethylhexyl (DOA) and diisodecyl adipate (DIDA), azelaic acid-
Azelaic acid esters such as di-2-ethylhexyl (DOZ), tri-2-ethylhexyl acetylcitrate,
Polyester plasticizers such as hydroxy polyvalent carboxylate esters such as acetyl tributyl citrate and polypropylene glycol adipate esters, which are used alone or in a mixture of two or more. The addition amount of these plasticizers varies depending on the application, but is generally preferably in the range of 3 to 30 parts by weight based on 100 parts by weight of the lactone-containing resin (c). (If it is a film, 5-15
A range of parts by weight is preferred. If the amount is less than 3 parts by weight, the elongation at break and the impact strength may be reduced, and if it exceeds 30 parts by weight, the strength at break and the impact strength may be reduced.

As the heat stabilizer used in the present invention, there is an aliphatic carboxylate. As the aliphatic carboxylic acid, an aliphatic hydroxycarboxylic acid is particularly preferred. As the aliphatic hydroxycarboxylic acid, naturally occurring ones such as lactic acid and hydroxybutyric acid are preferable. Examples of the salt include salts of sodium, calcium, aluminum, barium, magnesium, manganese, iron, zinc, lead, silver, copper, and the like. These can be used as one kind or as a mixture of two or more kinds. The addition amount is in the range of 0.5 to 10 parts by weight based on 100 parts by weight of the lactone-containing resin (c). When a heat stabilizer is used in the above range, impact strength (Izod impact value) is improved, elongation at break, strength at break,
This has the effect of reducing the variation in impact strength.

The lubricant used in the present invention includes an internal lubricant,
Those generally used as an external lubricant can be used. For example, fatty acid esters, hydrocarbon resins, paraffins, higher fatty acids, oxy fatty acids, fatty acid amides, alkylene bis fatty acid amides, aliphatic ketones, fatty acid lower alcohol esters, fatty acid polyhydric alcohol esters, fatty acid polyglycol esters, fatty alcohols, Examples include a hydric alcohol, polyglycol, polychrycerol, metal soap, modified silicone or a mixture thereof. Preferably, fatty acid esters, hydrocarbon resins and the like are used. When selecting a lubricant, it is necessary to select a lubricant whose melting point is lower than the melting point of the lactone resin or other biodegradable resin. For example, considering the melting point of the aliphatic polyester resin, the fatty acid amide is 160 ° C.
The following fatty acid amides are selected. For example, in the case of a film, 0.05 to 5 parts by weight of a lubricant is added to 100 parts by weight of the lactone-containing resin (c). If the amount is less than 0.05 part by weight, the effect is not sufficient, and if it exceeds 5 parts by weight, the physical properties deteriorate. From the viewpoint of preventing environmental pollution, ethylene bisstearic acid amide, stearic acid amide, oleic acid amide, and erucic acid amide, which are highly safe and registered with the FDA (US Food and Drug Administration), are preferred.

Examples of the photodegradation accelerator include benzophenones such as benzoins, benzoin alkyl ethers, benzophenone and 4,4-bis (dimethylamino) benzophenone and derivatives thereof; acetophenone,
Acetophenones such as α, α-diethoxyacetophenone and derivatives thereof; quinones; thioxanthones; photoexciting materials such as phthalocyanine, anatase-type titanium oxide, ethylene-carbon oxide copolymer, sensitization of aromatic ketones with metal salts And the like. These photolysis accelerators are
One type or two or more types can be used in combination.

Examples of the biodegradation promoter include oxo acids (for example, oxo acids having about 2 to 6 carbon atoms such as glycolic acid, lactic acid, citric acid, tartaric acid, and malic acid) and saturated dicarboxylic acids (for example, Organic acids such as lower saturated dicarboxylic acids having about 2 to 6 carbon atoms such as oxalic acid, malonic acid, succinic acid, succinic anhydride, glutaric acid and the like; these organic acids and alcohols having about 1 to 4 carbon atoms; Lower alkyl esters. Preferred biodegradation promoters include organic acids having about 2 to 6 carbon atoms, such as citric acid, tartaric acid, and malic acid, and coconut shell activated carbon. One or more of these biodegradation accelerators can be used in combination.

In the present invention, at least the lactone resin (a) constituting the lactone-containing resin (c) is subjected to a predetermined irradiation treatment. In the present invention, "including a step of irradiating the component lactone resin alone or together with at least one other component" means that the lactone resin (a) alone and the lactone resin (a) are used separately. In the state of a composition with the biodegradable resin (b), the lactone-containing resin (c) is blended with at least one resin additive (d),
Irradiation before, during or after molding of the pellets. The shape may be a powder, a state during pellet molding, or a state after pelleting. Therefore, in the present invention, the lactone resin alone is subjected to a predetermined irradiation treatment in advance, and a synthetic aliphatic polyester resin is mixed with the lactone resin, or a resin composition obtained by further adding a fatty acid amide or the like, and synthesized with the lactone resin. A resin composition obtained by mixing the aliphatic polyester resin or fatty acid amide and performing the same radiation irradiation treatment and then mixing the remaining components, a lactone resin, a synthetic aliphatic polyester resin and a fatty acid amide, and then performing the above-described irradiation treatment. And a resin composition obtained by the above method. Further, there is also included a mode of irradiating with a low dose first and irradiating with a high dose at a later stage. For example, at the pellet stage, the gel fraction becomes 0.01 to 10%, preferably 0.05 to 1.0%. Irradiation can be as follows. As a result, the melting point is higher than that of the unirradiated one, so that the irradiation can be performed again while maintaining the shape at a higher temperature, the crosslinking occurs with a high probability, and the heat resistance is improved. The gel fraction is 0.01 to 10%, preferably 0.05
By irradiating so as to be ~ 1.0%, crosslinking occurs and the melting point becomes higher, and the tensile strength and tear strength are improved.
The releasability from the mold and the roll adhesion are reduced, and the transparency is increased.

The radiation source used in the radiation irradiation treatment according to the present invention includes α-rays, β-rays, γ-rays, X-rays, electron beams,
Ultraviolet rays and the like can be used, but γ-rays, electron beams, and X-rays from cobalt 60 are more preferable. Among them, γ-rays, electron beam irradiation treatment using an electron accelerator is useful for introducing a bridge structure of a polymer material. Most convenient.

The irradiation amount is determined using a gel fraction of a lactone resin as a measure for introducing a crosslinked structure of a polymer material as one measure. When irradiating the lactone resin before molding of the final product, the gel fraction is 0.05 in consideration of moldability.
For example, in the pellets according to the production method of the present invention, it is preferably about 0.1 to 1%. In addition, when irradiating the molded article after obtaining the molded article using the pellet,
The gel fraction of the lactone resin can be as high as about 90%. When the gel fraction is set to 10% or more, since crosslinking occurs mainly in the amorphous region of the polymer material, a large dose of, for example, 200 kGy is required in the irradiation treatment near room temperature, and in the treatment near the melting point, There is a tendency for a large number of voids to occur and reduce the strength. Therefore, in such a case, the lactone resin is cooled to a temperature not lower than the melting point (60 ° C. for polycaprolactone) and not crystallization after melting (50 to 35 ° C. for polycaprolactone). By performing the above treatment in this state, a gel with a very high gel fraction can be obtained at a low dose. The “state that does not lead to crystallization” here refers to a state in which the non-crystalline state is dominant because cross-linking occurs in the non-crystalline part, although it cannot be accurately specified. If the degree of crystallinity is lower than in the room temperature state, there is a corresponding irradiation effect. In addition, not only the treatment with the lactone resin alone, but also the treatment with the above various compositions comprising other components, it is sufficient to consider only the molten state of the lactone resin component. Of course, it is also possible to irradiate up to a high gel fraction without melting.

As a result of observing the effect of radiation treatment of the lactone resin in the present invention, the gel fraction and MI of the degree of crosslinking were measured.
When kGy is reached, the effect starts to appear, and the gel fraction is 100.
A sharp rise was seen at kGy, and MI was 60 kGy.
, And tend to be stable at higher doses. Regarding biodegradability, when measured in sludge, the higher the irradiation dose, the higher the decomposition rate,
Biodegradation was started by immersion for 4 to 5 days, and after about 10 days, a result of a decomposition rate of 50% was obtained. In addition, improvements in mechanical properties (tensile strength, tensile elongation, tear strength, impact strength) and anti-blocking properties of the film against nip rolls were also observed.

According to the present invention, a lactone-containing resin or a lactone-containing resin composition is formed into pellets, and the pellets are used for primary molding into plates, parisons, etc., and these are formed into sheets, films, tapes, fibers, Secondary molding into thin-walled containers and thick-walled containers, and film into bags, especially degradable garbage bags,
Drain bags, shrink films, etc .; Laminated films for agricultural multi-films, etc .; Fibers for threads, ropes, woven fabrics, fishing lines, nets, etc .; Tapes for packing tapes, nets, bands, etc .; Thin containers for trays, blisters For packs and the like;
Thick containers into bottles, planting containers, etc .; daily necessities such as hoses and pipes; industrial materials; foam into cushioning materials, agricultural materials, etc .; other pen bodies, cards, information media materials; outdoor It can be processed into equipment, sports equipment, leisure equipment body and the like. Extrusion molding, injection molding, blow molding, calender molding, compression molding, transfer molding,
Thermoforming, flow molding, lamination molding and the like are possible.

As a method for obtaining pellets obtained by adding the above-mentioned various additives, various methods conventionally used can be applied, and are not particularly limited. As the simplest method, there is a method of kneading the raw material of the biodegradable resin pellets according to the present invention, but it may be applied to the surface of the strand during pellet production or to the surface of the pellet after cutting. Good. This attachment method may be performed before or after the irradiation treatment.

An example of a method for producing pellets from the above composition will be described. First, lactone resin, aliphatic polyester resin and liquid lubricant are put in a tumbler and
Stir and mix for 0-20 minutes, then add fatty acid amide,
Fine powdered silica, starch, and a biodegradation accelerator are added thereto, and the mixture is further stirred and mixed for 20 to 30 minutes. After that, uniaxial or 2
Perform melt-kneading at about 140 to 210 ° C. using a screw extruder or the like, extrude a resin composition containing various additives as a strand from the extruder, cut after irradiation treatment,
Obtain pellets. Alternatively, radiation irradiation treatment is performed on pellets that do not lead to crystallization after cutting.

The pellet-shaped additive-containing resin composition obtained in this manner has a higher melting point than the conventional lactone resin without irradiation treatment or pellets of the composition, which is considered to be based on the crosslinked structure. By increasing the viscosity, the film is formed into a film by various conventional forming methods such as an inflation method and a T-die method. Hereinafter, a film forming method by an inflation method will be described as an example of using the obtained pellets. First, the pellets are supplied to an extruder equipped with an annular die, melt-kneaded at a resin temperature of 180 ° C., and extruded into a tube from an annular die slit. For example, the extrusion diameter of the extruder at this time is 40 to
About 65mm, length / diameter ratio (L / D) is 26 ~
The diameter of the annular die can be 50 to 150 mm, and the gap of the die slit is 0.5 to 1.5.
The range of mm is preferred. The extruded tube-shaped film expands to a predetermined diameter with a blow ratio (tube diameter / die diameter) of 2 or more by the pressure of gas introduced from a gas blowing pipe inserted through the die, and then Folded by a nip roll and taken off at a constant speed, a tubular film is obtained and used for use.When used as a wide flat film, cut out in the take-off direction when exiting the nip roll and Is manufactured.

[0027]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. In the Examples, “%” and “parts” are based on weight unless otherwise specified. MI at 190 ° C. is 21
It is a value indicating the flow characteristics under a load of 60 g.

(Example 1) Polycaprolactone pellets (melt index 2.57 g / 10 min) were heated to a melting point or higher, then cooled to 50 ° C, and while in an amorphous state, an electron beam was irradiated with 60 kGy and 160 kGy as radiation. Upon irradiation, the resulting treated pellets had a melt index of 0.05 g / 10 min (gel fraction 60 described below).
%) And 0.03 g / 10 min (gel fraction 80%). The untreated pellets and treated pellets were placed in an urban sewage sludge environment at 25 ° C. according to JIS K6950,
They were subjected to a 4-week biodegradability test. As a result, the decomposition rate of the non-irradiated product was 55%, while that of the irradiated product was 86.2% and 77.2%, respectively. Further, the irradiated product was formed into a sheet by a hot press at 200 ° C., and a biodegradability test was similarly performed on the pulverized sample. as a result,
The decomposition rates were 87.0% and 87.8%, respectively. The same test results were obtained by changing the irradiation type from electron beam to gamma ray.

Example 2 The polycaprolactone pellets used in Example 1 were irradiated at room temperature with an electron beam irradiation of 15 kGy. Processed pellets (melt index: 1.0 g / 10 min, gel fraction 0.2%) to 40 mmφ
And extruded with an extruder (resin temperature 150 ° C.) provided with a T-die to obtain a sheet having a thickness of about 270 μm. The obtained sheet was subjected to a tear test, an impact resistance test in accordance with JIS K7211 and a tensile test in accordance with JIS K6782 at room temperature, and compared with the test results of unirradiated products similarly formed into sheets. As a result, the tensile strength (MD: longitudinal direction) was 260, 280 in the order of the unirradiated product and the irradiated product.
kgf.cm, 210, 230kg in the transverse direction (TD)
f · cm, tensile elongation (MD) is 1130, 1240%,
The TD is 1130, 1160% and the tear strength (MD) is 1
60, 270 gf, the TD was 190 and 450 gf, and the impact strength test was 23.8 and 25.2 kgf · cm, respectively.

Example 3 An electron beam was applied to the polycaprolactone pellets used in Example 1 at room temperature at 10, 20, and 4
Irradiation at 0 and 100 kGy was performed to measure changes in MI and gel fraction (%), and the following values were obtained in order. Electron beam dose (kGy): 0, 10, 20, 40, 1
00 MI (g / 10 min): 2.6, 1.0, 0.5, 0.1, 0.08 Gel fraction (%): 0, 0.1, 0.2, 0.3, 23.7

In Examples 1 to 3, irradiation was examined for polycaprolactone to which biodegradable resin Bionole was added, but there was essentially no change.

In Example 3, a sample obtained by cutting a sheet obtained from 20 kGy-irradiated caprolactone into a 10 cm square was immersed in 70 ° C. hot water, and the shrinkage was measured. As a result, the sheet obtained from unirradiated caprolactone was melted, but the 20 kGy irradiated sheet was not melted and contracted 60% in the MD direction and 30% in the TD direction.

[Preparation Example 1] A pellet of 10 g of polycaprolactone (Placcel H7, trade name, manufactured by Daicel Chemical Industries, Ltd., number average molecular weight 1.28 × 10 ⁵ ) was placed in a 1.5 cm.
It was placed in a glass ampoule of diameter and connected to a vacuum line to remove air and then sealed. This sample was completely melted in an oven at 80 ° C., inserted into a metal block adjusted to 45 ° C. in advance, and irradiated with 100 kGy at a dose rate of 10 kGy / hr by gamma rays from cobalt 60.
After the irradiation, the glass ampule was opened, and a cylindrical PCL having a diameter of 1.5 cm was taken out. From this, a thin plate having a thickness of about 5 mm was cut out, wrapped in a 200-mesh stainless steel wire gauze, immersed in acetone for 24 hours, and the gel fraction (the ratio of insoluble content, representing the degree of crosslinking) was determined by the following equation. 7
It was 0%. Gel fraction _{(%) = (W 2 /} W 1) × 100 ( wherein, W ₁ represents the dry weight of the PCL before immersion, W ₂
Represents the dry weight after immersion. Further, in order to examine the heat resistance, PCL sliced to a thickness of 2 to 3 mm was compression-molded into a film by hot pressing at 200 ° C., and the obtained film was extremely excellent in transparency. For heat resistance, a tensile strength and an elongation at break were determined using a high-temperature tensile tester under the conditions of a tensile speed of 100 mm / min and 120 ° C. The results are shown in Table 1.

Example 4 40 parts of polycaprolactone, 60 parts of poly-1,4-butanediol-succinate, which had been subjected to an irradiation treatment adjusted to have the same gel fraction as in Preparation Example 1, 60 parts of liquid paraffin 0.5 part and 1 part of stearic acid amide were put into a twin screw type vented extruder (40 mm diameter), and extruded at a die temperature of 180 ° C. to obtain a resin composition pellet. M of this resin composition
I was 0.1 g / 10 min.

(Use Example 1) Using the resin pellets produced in Example 4, a blown film having a width of 450 mm was formed by an inflation method under the following forming conditions. (Molding conditions) Extruder: 40 mm diameter extruder Screw: L / D = 28, screw for MDPE (medium density polyethylene) Die: lip diameter 150 mm, die gap 1 mm Extrusion temperature: 170 ° C. at cylinder tip Die temperature: 170 ° C. Resin temperature (T1): 160 ° C. Screw rotation speed: 15 rpm Discharge rate: 15 kg / hr Blow ratio: 2.5

[Preparation Example 2] The gel fraction (%) of polycaprolactone obtained through the same step as the irradiation treatment described in Example 4 except that irradiation was performed at a dose of 150 kGy with γ-ray was 82%. Was. Preparation test for heat resistance
The procedure was as described above, and the results are shown in Table 1.

Example 5 40 parts of polycaprolactone, 60 parts of poly-1,4-butanediol-succinate, 0.5 part of liquid paraffin, 0.8 part of stearamide after the irradiation treatment step of Preparation Example 2 above Part and fine powder silica (“Aerosil # 200” manufactured by Nippon Aerosil Co., Ltd.)
Pellets of the resin composition were obtained in the same manner as in Example 4 using 8 parts. The MI of this resin composition is 0.09 g / 10 min.
Met.

(Example 6) 40 parts of polycaprolactone, 60 parts of poly 1,4-butanediol-succinate, 0.5 part of liquid paraffin, stearin which had been subjected to the same irradiation treatment step as described in Preparation Example 2 Pellets of the resin composition were obtained in the same manner as in Example 4 using 0.5 part of acid amide and 0.5 part of fine powdered silica (Aerosil # 200, same as above).
The MI of this resin composition was 0.09 g / 10 min.

(Example 7) 40 parts of polycaprolactone, 60 parts of poly 1,4-butanediol-succinate, 0.5 part of liquid paraffin, stearin, which had been subjected to the same irradiation treatment step as described in Preparation Example 2 0.5 parts of acid amide,
Pellets of a resin composition were obtained in the same manner as in Example 4 using 0.5 parts of fine powder silica (Aerosil # 200, same as above) and 50 parts of corn starch. The MI of this resin composition is 0.1.
It was 09 g / 10 min.

Comparative Example 1 Unirradiated Polycaprolactone 4
0 parts (test results of heat resistance are shown in Table 1), poly 1,4
-Butanediol-succinic ester 60 parts, liquid paraffin 0.5 part, stearic acid amide 0.8 part, fine powder silica ("Aerosil # 200" manufactured by Nippon Aerosil Co., Ltd.)
Pellets of the resin composition were obtained in the same manner as in Example 4 using 0.8 parts. The melt index of this resin composition is 3.
It was 9 g / 10 minutes.

[0041]

[Table 1]

[0042]

According to the method for producing resin pellets according to the present invention, it has been found that radiation irradiation treatment can be easily performed, and that pellets of a biodegradable resin or a composition thereof can be produced effectively. . It is considered that the obtained pellets are crosslinked, but they can be used for various moldings and can be said to be effective pellets in combination with the biodegradable function.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C08L 93/00 C08L 93/00 // C08J 7/00 305 C08J 7/00 305 (72) Inventor Hiroshi Mitomo Tenjin, Kiryu-shi, Gunma 1-5-1, Machi, Gunma University Faculty of Engineering (72) Inventor Dharmawan Dalwis 1-5-1, Tenjincho, Kiryu-shi, Gunma Gunma University Faculty of Engineering (72) Inventor Sada Murakami 1-1-1, Shinmatsudo Minami, Matsudo, Chiba 323

Claims (8)

[Claims] 1. A method for producing a resin pellet of a lactone resin (a) alone or a composition of a lactone resin (a) and another biodegradable resin (b), wherein a component lactone resin of the resin pellet is used. A method for producing resin pellets, comprising a step of performing radiation irradiation treatment alone or together with at least one other component. 2. The biodegradable resin (b) is synthesized and / or
The method for producing a resin pellet according to claim 1, wherein the resin pellet is a natural polymer. 3. The method according to claim 2, wherein the synthetic polymer is an aliphatic polyester, a biodegradable cellulose ester, a polypeptide, a polyvinyl alcohol, or a mixture thereof. 4. The natural polymer is starch, cellulose, paper,
The method for producing resin pellets according to claim 2, which is pulp, cotton, hemp, wool, silk, leather, carrageenan, chitin / chitosan, natural linear polyester resin, or a mixture thereof. 5. A composition comprising a lactone resin alone or a lactone resin and another biodegradable resin as a raw material for pellets, further comprising a photodecomposition accelerator, a biodegradation accelerator, fine powder particles produced from paper, a plasticizer, and a heat stabilizer. Agents, extenders, fillers, lubricants, coloring agents, flame retardants, waterproofing agents, auto-oxidants, UV stabilizers, cross-linking agents, antibacterial agents, fungicides, herbicides, antioxidants, droplets, deodorants Agent,
The method for producing a resin pellet according to any one of claims 1 to 4, wherein the pellet is produced by adding an antistatic agent or a mixture thereof. 6. A radiation irradiation treatment for a pellet raw material, for a resin strand extruded from a discharge port of an extruder, or for a cut resin pellet.
The method for producing a resin pellet according to any one of the above. 7. The lactone resin (a) having a gel fraction of 0.0
The method for producing a resin pellet according to any one of claims 1 to 6, wherein the content is in a range of 5 to 10%. 8. The method for producing resin pellets according to claim 1, wherein the lactone resin (a) is polyε-caprolactone.