JP2008001837A - Biodegradable resin composite material and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable resin composite material capable of maintaining its shape and strength at or higher than a glass transition point or softening point temperature of the biodegradable resin, also without becoming hard and brittle at or lower than the glass transition point temperature of the biodegradable resin and equipped with flexibility and elongation corresponding to its uses, a method for producing the same and a biodegradable resin composite material obtained by combining the characteristics of another polymer than the biodegradable resin with the biodegradable resin. <P>SOLUTION: This biodegradable resin composite material is provided by forming a molded article with a kneaded material obtained by blending a cross-linkable monomer with the biodegradable resin, cross-linking the biodegradable resin of the molded article to make a biodegradable resin-cross-linked article, immersing the biodegradable resin-cross-linked article in an impregnating material containing a heated plasticizer or polymerizable monomer to impregnate the impregnating material into the inside of the biodegradable resin-cross-linked article, cooling the biodegradable resin-cross-linked article in a swollen state to make a composite of the biodegradable resin with the impregnating material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a biodegradable biodegradable resin composite and a method for producing the same, and in particular, is used in a field where plastic products such as structures, parts such as films, containers, and cases are used. In particular, it has a required hardness according to the application.

Petroleum synthetic polymer materials currently used for many films and containers are used for the global warming caused by heat and exhaust gas from heat treatment and the food and health caused by toxic substances in combustion gases and residues after combustion. Various social problems are concerned about the disposal process alone, such as adverse effects on the environment and securing of landfill sites.
Biodegradable polymer materials typified by starch and aliphatic polyester have been attracting attention as materials for solving such problems of disposal of petroleum synthetic polymer materials. Biodegradable polymer materials have a negative impact on the global environment, including ecosystems, such as the amount of heat generated by combustion is less than petroleum synthetic polymer materials and the cycle of decomposition and resynthesis in the natural environment is maintained. Don't give. Among biodegradable polymer materials, aliphatic polyester resins have characteristics comparable to petroleum synthetic polymer materials in terms of strength and processability, and are recently attracting particular attention. Among the aliphatic polyester resins, polylactic acid is especially made from starch supplied from plants, and it is becoming cheaper than other biodegradable polymer materials due to cost reduction due to mass production in recent years. Therefore, many studies are currently being made on its application.

  However, biodegradable resins such as starch, cellulose and their derivatives, and polylactic acid are very hard, have substantially no elongation, and have a drawback of poor absorbency against deformation and impact. On the other hand, biodegradable resins such as polybutylene adipate terephthalate, polycaprolactone, and polybutylene succinate have the disadvantage that they are flexible but have a low breaking strength. Thus, many biodegradable resins do not have flexibility and strength and are difficult to use as they are.

Therefore, in order to improve these biodegradable resins, attempts have been actively made to mix modifiers such as mixing of plastics and plasticizers, which are techniques conventionally performed with plastic resins. For example, in order to improve hardness and brittleness at a glass transition temperature of 60 ° C. or lower and improve impact resistance to the same level as general-purpose plastics, it is possible to mix a specific plasticizer with a biodegradable resin (polylactic acid) as follows. It is described in Non-Patent Document 1.
Moreover, in order to solve the problem that when the glass transition temperature is exceeded, the resin becomes too flexible and the strength is reduced, it is possible to crosslink polylactic acid using ionizing radiation or a chemical initiator. (Patent Document 1).

Japanese Patent No. 3759067 Issued by Arakawa Chemical Industries, Ltd., “Arakawa NEWS”, issued in July 2004, No. No.326 Page 2-7

  However, even if each of these technologies is used alone, both the maintenance of flexibility and elongation below the glass transition temperature of the biodegradable resin and the maintenance of shape and strength above the glass transition temperature (that is, heat resistance) are solved simultaneously. It is not possible. That is, as in Non-Patent Document 1, simply mixing a plasticizer with a biodegradable resin only lowers the glass transition temperature and weakens the bonding force between the biodegradable resin molecules. Although it is difficult to break, it cannot impart a restoring force against deformation and impact, and the glassy material becomes like clay and cannot retain its strength. Moreover, in order to improve the maintainability of the shape and strength above the glass transition temperature, it is effective to crosslink the biodegradable resin as in Patent Document 1, but the crosslinked biodegradable material obtained in this way. Is hard and brittle and does not have flexibility or elongation.

  In addition, these techniques can be carried out independently, but if they are to be made compatible, problems such as inability to crosslink occur due to crosslink inhibition caused by the composite material. For example, even when these techniques are simply combined and a composition in which a plasticizer is kneaded with a biodegradable resin is crosslinked by irradiation with ionizing radiation, the crosslinking does not proceed completely. In addition to the fact that the plasticizer eliminates radicals caused by ionizing radiation, the cause of hindering cross-linking is that when the plasticizer is kneaded first, the plasticizer enters between the molecules of the biodegradable resin. It is conceivable to prevent binding between molecules. In order for the biodegradable resin to crosslink, the molecules of the biodegradable resin need to contact and bond with each other.

  Therefore, the present invention can maintain the shape and strength above the glass transition temperature or softening temperature of the biodegradable resin, and does not become hard and brittle below the glass transition temperature of the biodegradable resin. Accordingly, it is an object of the present invention to provide a biodegradable resin composite having flexibility and elongation and a method for producing the same.

  In addition, the present invention provides a biodegradable resin composite in which a biodegradable resin and another polymer are combined in a very uniform mixed state at a level similar to that of a copolymer, and a method for producing the same. It is an object to provide various biodegradable resin composites having flexibility and hardness according to applications by incorporating characteristics.

In order to solve the above problems, the present invention provides:
Forming a molded body from a kneaded product in which a crosslinkable monomer is blended with a biodegradable resin,
Cross-linking the biodegradable resin of the molded body to a biodegradable resin cross-linked product,
The biodegradable resin crosslinked product is immersed in an impregnated material containing a heated plasticizer or polymerizable monomer, and the biodegradable resin crosslinked product is impregnated with the impregnated material,
Cooling in a state where the biodegradable resin crosslinked product is swollen,
Provided is a method for producing a biodegradable resin composite, wherein the biodegradable resin is combined with the impregnating material.

In the method for producing a biodegradable resin composite of the present invention, as described above, first, a biodegradable resin molded body is molded from a kneaded material in which a crosslinkable monomer is blended with a biodegradable resin, and the biodegradable resin The resin molded product is crosslinked to give heat resistance. Next, the cross-linked biodegradable resin imparted with heat resistance is immersed in an impregnating material containing a heated liquid plasticizer or polymerizable monomer.
When the heated impregnating material is used, the molecules of the biodegradable resin move to expand the molecules, so that the impregnating material can easily enter between the molecules of the crosslinked biodegradable resin. Furthermore, since the viscosity of the impregnating material decreases when heated, the molecular mobility of the impregnating material can be increased, so that the impregnating material easily enters between the crosslinked networks.

  On the other hand, many plasticizers and polymerizable monomers that are liquid at room temperature are liable to vaporize or evaporate by heating, and such plasticizers or polymerizable monomers need to be at a temperature lower than the vaporization temperature. For example, some impregnating materials such as a crosslinkable monomer have a boiling point in the vicinity of 80 to 150 ° C., and if the temperature is higher than this, it is easy to vaporize, so it is difficult to raise the temperature of the impregnating material. Therefore, in the case of using an impregnating material that easily vaporizes, the upper limit of the temperature is preferably set to 80 ° C. The upper limit of the impregnating material that is difficult to vaporize is preferably 120 to 140 ° C. Furthermore, since the impregnating material needs to be in a chemically stable state and in a liquid state, the upper limit of the temperature of the impregnating material is set to be equal to or lower than the melting point or the decomposition temperature of the biodegradable resin.

According to the study of the present inventor, the softening temperature and glass transition temperature of many biodegradable resins are around 60 ° C., and softening occurs near this temperature, so the lower limit of the temperature of the impregnating material is 60 ° C. Is preferred. If the temperature of the impregnating material is 60 ° C. or higher, the composite can be made very efficiently. In the case of a crosslinked biodegradable resin having a higher molecular weight, the temperature of the impregnating material is preferably 80 ° C. or higher, more preferably 100 ° C. or higher.
Thus, the optimum temperature of the impregnating material varies depending on the type of biodegradable resin, the type of impregnating material, and the combination of the biodegradable resin and the impregnating material. For example, fat having a glass transition temperature of generally 60 ° C. or less. It is suitable for the group polyesters that the temperature of the impregnating material is equal to or higher than the glass transition temperature. Even polysaccharides generally having a high glass transition temperature and softening temperature can be swollen by an impregnating material when heated to 80 to 100 ° C.

  In Non-Patent Document 1, the biodegradable resin is crosslinked after mixing with the plasticizer. In the present invention, the biodegradable resin is immersed before being immersed in the impregnating material containing the plasticizer or the polymerizable monomer. Therefore, in the biodegradable resin composite obtained by the present invention, the crosslinks between the biodegradable resin molecules are maintained almost completely. As a result, there is no reduction in strength that occurs when the biodegradable resin is cross-linked after mixing the plasticizer or polymerizable monomer, and shape retention can be improved.

  In the present invention, the impregnated material is impregnated with the biodegradable resin crosslinked product, and the hardness of the biodegradable resin crosslinked product is adjusted by a plasticizer or a polymerizable monomer to be impregnated, for example, a relatively hard polysaccharide In the biodegradable resin, a plasticizer is impregnated to reduce the hardness to give flexibility, and the relatively flexible polybutylene adipate terephthalate is impregnated with a polymerizable monomer to obtain the required hardness. It is said. In this way, the impregnated material that can adjust the hardness of the biodegradable resin is impregnated, the crosslinked biodegradable resin swelled with the impregnated material is cooled, and the shape is fixed in that state. The biodegradable resin composite adjusted to the hardness according to can be obtained.

When a plasticizer is used as the impregnating material, the impregnating material prevents the interaction between molecules of the biodegradable resin, and the obtained biodegradable resin composite is very low even at a temperature below the glass transition temperature and the softening temperature. It has excellent flexibility and elongation and exhibits excellent impact resistance.
This is generally considered to be the same effect as the heat shrinkable material has shape memory property due to the crosslinked structure. That is, the heat-shrinkable material is manufactured by fixing the shape in the stretched state, and becomes flexible only when heated during use and can exhibit the shape-recovering ability. However, the biodegradable resin composite of the present invention In this case, it is recognized that when the material is returned to room temperature by containing an impregnating material composed of a plasticizer, the plasticizer returns to a flexible shape.

  In addition, a polymerizable monomer is used as an impregnating material, and the polymerizable monomer is graft-polymerized to the crosslinked biodegradable resin or the polymerizable monomer for the purpose of fixing the polymerizable monomer in the crosslinked network of the crosslinked biodegradable resin. Can be combined with a biodegradable resin to form a polymer, and the biodegradable resin and the polymer can be made into a polymer alloy. By polymer-alloying, it is possible to produce a material having a property such as hardness that combines the properties of both the biodegradable resin and the polymer produced by polymerization of the polymer.

  Furthermore, the method for producing a biodegradable resin composite of the present invention is also excellent in that an impregnated material can be formed in a very uniform and finely dispersed state in the biodegradable resin. When a biodegradable resin and an impregnating material are combined, in the conventional method, both are physically kneaded and heated and mixed to disperse, so that a polymer alloy or nanocomposite can be formed without using a compatibilizer. Fine dispersion could not be achieved. In contrast, in the method for producing a biodegradable resin composite of the present invention, if a fine crosslinked network structure is formed when forming a biodegradable resin crosslinked product, a drug such as a compatibilizer is used. Even without this, a finely dispersed state of the impregnating material can be easily formed. Such a fine network structure of the biodegradable resin crosslinked product may be formed by controlling the conditions such as the amount of the crosslinkable monomer and the radiation dose. As described above, in the production method of the present invention, when the biodegradable resin and the impregnating material are simply combined or mixed, compounding unevenness of the material that is an accessory, large lumps or lumps that could not be mixed remain. There is no worry to do.

The said process is demonstrated in detail using Fig.1 (a)-(g).
First, FIG. 1A shows a biodegradable resin crosslinked product 1 obtained by crosslinking a biodegradable resin molded product. When the biodegradable resin crosslinked product 1 is viewed microscopically, the molecules of the biodegradable resin are mutually constrained by the crosslinking 11 as shown in FIG. In this state, it has an advantage that it is difficult to be deformed even when the temperature is equal to or higher than the glass transition temperature. However, the interaction between the molecules of the biodegradable resin at the temperature equal to or lower than the glass transition temperature (arrow in FIG. 1 (e)). Has a drawback that it is hard and brittle and lacks durability.

In this invention, as shown in FIG.1 (b), biodegradable resin crosslinked material 1 is immersed in the liquid impregnating material 2 which consists of a heated plasticizer or a polymerizable monomer. By heating the impregnating material, the permeability of the impregnating material is increased, and the liquid impregnating material 2 is impregnated into the biodegradable resin crosslinked product 1.
Next, when the biodegradable resin crosslinked product 1 is cooled while being swollen with the impregnating material 2, the biodegradable resin composite 3 of the present invention is obtained as shown in FIG. 1 (c).

  When the impregnating material is a plasticizer, the biodegradable resin composite 3 is impregnated with the impregnating material (plasticizer) 2 in the network of the crosslinks 11 of the biodegradable resin as shown in FIG. Yes. Since the impregnating material 2 prevents the interaction between the molecules of the biodegradable resin, a flexible state at the glass transition temperature or softening temperature is maintained even at room temperature. In addition, in the biodegradable resin composite 3 of the present invention, the crosslinks 11 between the biodegradable resin molecules are formed almost completely. As a result, the biodegradable resin molecules are not unconstrained even when the glass transition temperature or the softening temperature is reached, and the shape can be maintained.

  In the biodegradable resin composite 3, the impregnated material is only impregnated between the molecules of the biodegradable resin, and is not fixed. In the present invention, an impregnating material containing a polymerizable monomer is used, and after impregnating the impregnating material, as shown in FIG. 1 (d), the impregnating material 2 is impregnated and then the impregnating material 2 is polymerized to produce a biodegradable resin composite. 4 can be formed and the impregnating material can be fixed to the biodegradable resin. The impregnating material 2 forms a polymerization network bonded to each other by polymerization 41.

In the method for producing a biodegradable resin composite of the present invention, as described above, it is important to first produce a biodegradable resin crosslinked product by almost completely crosslinking the biodegradable resin molded product.
2 and 3 show the phenomena that occur when the biodegradable resin molding 4 that has not been cross-linked is immersed in an impregnating material made of a plasticizer by the method of the present invention.
As shown in FIG. 2B, when the non-crosslinked biodegradable resin molded product 4 is immersed in the impregnating material 2, there is no cross-linking that binds the biodegradable resin molecules to each other. As shown in FIG. 2 (c), the biodegradable resin is dissolved and the shape is deformed or collapsed.
Further, as shown in FIG. 3B, when the non-crosslinked biodegradable resin molded product 4 is placed at a temperature higher than the glass transition temperature, the non-crystalline portion is gradually crystallized (reference numeral in FIG. 3B). 5) In some cases, the impregnating material hardens and hardens before entering, and a crystallized biodegradable resin molded body 6 as shown in FIG.
In the present invention, it is the biodegradable resin crosslinked product 1 that is impregnated with the impregnating material 2, and the biodegradable resin molecules are constrained and integrated by the crosslinking 11, so that the non-crystalline portion begins to gradually crystallize. No recrystallization is seen.

In order to prevent the phenomenon shown in FIGS. 2 and 3 from occurring, it is preferable that the biodegradable resin component is substantially 100% crosslinked in the biodegradable resin composite of the present invention. Therefore, the biodegradable resin crosslinked product before dipping in the impregnating material containing a plasticizer or a polymerizable monomer has a gel fraction of 95% by mass or more, preferably 98% by mass or more, more preferably substantially 100% by mass. % Is preferably completely cross-linked.
Even in the range where the gel fraction substantially exceeds 100% by mass, the amount of crosslinking points, that is, the crosslinking density is important, and the content of the impregnating material can be controlled by increasing the crosslinking density. is there. This utilizes the fact that the cross-linked network structure becomes dense, making it difficult for structural changes and volume changes to occur. The amount of cross-linkable monomer in forming the biodegradable resin cross-linked product, the amount of ionizing radiation to be cross-linked, It is possible to control the amount of impregnation of the impregnating material by increasing or decreasing the amount or the like to increase or decrease the crosslinking density.

The biodegradable resin used in the present invention may be any biodegradable resin capable of introducing a crosslinked structure, and is particularly selected from polysaccharides, aliphatic polyesters, and copolymers of aliphatic polyesters and aromatic polyesters. One type or two or more types of biodegradable resins are preferred.
Specifically, for example, polysaccharide-based biodegradable resins containing natural polysaccharides such as cellulose, starch, chitin, chitosan, alginic acid, and derivatives obtained by acetylating or esterifying them,
Aliphatic polyester-based biodegradable resins such as polycaprolactone (PCL), polybutylene succinate (PBS), polyethylene succinate, or polyethylene succinate adipate,
Alternatively, a biodegradable resin of a copolymer of an aliphatic polyester and an aromatic polyester typified by polybutylene adipate terephthalate (PBAT) into which aromatics such as terephthalic acid are introduced,
Etc. These may be used alone or in combination of two or more.

The crosslinkable monomer is not particularly limited as long as it is a monomer that can be crosslinked by irradiation with ionizing radiation, and examples thereof include acrylic or methacrylic crosslinkable monomers or allyl crosslinkable monomers.
Examples of the acrylic or methacrylic crosslinkable monomer include 1,6-hexanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and ethylene oxide-modified trimethylol. Propane tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, ethylene oxide modified bisphenol A di (meth) acrylate, diethylene glycol di (meth) acrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, Caprolactone-modified dipentaerythritol hexaacrylate, pentaerythritol tri (meth) acrylate, pentaerythritol Tetra (meth) acrylate, polyethylene glycol di (meth) acrylate, tris (acryloyloxyethyl) isocyanurate, tris (methacryloxyethyl) isocyanurate.

  Examples of the allyl crosslinking monomer include triallyl isocyanurate, trimethallyl isocyanurate, triallyl cyanurate, trimethallyl cyanurate, diallylamine, triallylamine, diacrylic chlorentate, allyl acetate, allyl benzoate, and allyl diester. Propisocyanurate, allyl octyl oxalate, allyl propyl phthalate, bityl allyl malate, diallyl adipate, diallyl carbonate, diallyl dimethyl ammonium chloride, diallyl fumarate, diallyl isophthalate, diallyl malonate, diallyl oxalate, diallyl phthalate, Diallylpropyl isocyanurate, diallyl sebacate, diallyl succinate, diallyl terephthalate, diallyl tartrate, dimethyl Diallyl phthalate, ethyl allyl malate, methyl allyl fumarate, methyl meta-allyl maleate, diallyl monoglycidyl isocyanurate.

  As the crosslinkable monomer used in the present invention, an allylic crosslinkable monomer is preferably used because a high degree of crosslinking can be obtained at a relatively low concentration. Of these, triallyl isocyanurate is particularly preferable because of its high crosslinking effect on the biodegradable resin. Further, even when triallyl isocyanurate and triallyl cyanurate which can be mutually converted by heating are used, the effect is substantially the same.

Although the said crosslinkable monomer is based also on the kind of biodegradable resin, it is preferable to mix | blend in the ratio of 0.5 to 15 mass parts with respect to 100 mass parts of biodegradable resin. A more preferable blending amount of the crosslinkable monomer is 3 parts by mass or more and 8 parts by mass or less. This is because if the blending amount of the crosslinkable monomer is less than 3 parts by mass, the crosslinking effect of the biodegradable resin due to the crosslinkable monomer is not sufficiently exerted, and the composite of the composite at a high temperature above the glass transition temperature or the softening temperature. This is because the strength decreases and the shape may not be maintained in the worst case. On the other hand, the blending amount of the crosslinkable monomer is 8 parts by mass or less because if the blending amount of the crosslinkable monomer exceeds 8 parts by mass, it is difficult to uniformly mix the entire amount of the crosslinkable polymer into the biodegradable resin. This is because there is substantially no significant difference in the crosslinking effect.
The blending amount of the crosslinkable monomer is more preferably 5 parts by mass or more in order to ensure the shape maintaining effect at a high temperature above the glass transition temperature or the softening temperature, and the content of the biodegradable resin is increased. In order to improve biodegradability, it is more preferable that it is 10 mass parts or less.

In addition to the biodegradable resin and the crosslinkable monomer, other components may be blended in the kneaded material constituting the biodegradable resin molded product used in the present invention as long as the object of the present invention is not violated.
For example, a biodegradable resin other than the biodegradable resin may be blended. Examples of biodegradable resins other than the biodegradable resin include synthetic biodegradable resins such as polyvinyl alcohol.
Moreover, synthetic polymer and / or natural polymer powders having biodegradability may be mixed as long as the dissolution characteristics are not impaired. Examples of the biodegradable synthetic polymer include polypeptides such as polyglutamic acid, polyaspartic acid or polyleucine. Examples of the natural polymer include starch, raw starch such as corn starch, wheat starch or rice starch, or processed starch such as acetate esterified starch, methyl etherified starch or amylose.

  Furthermore, the kneaded product includes resin components other than biodegradable resins, curable oligomers, various stabilizers, flame retardants, antistatic agents, antifungal agents, additives such as anti-tackifiers, viscosity imparting agents, glass fibers, glass beads, Metal powders, inorganic and organic fillers such as talc, mica and silica, and colorants such as dyes and pigments can also be blended.

  A kneaded product containing the above-described biodegradable resin, crosslinkable monomer, and optionally other components is formed into a desired shape. A shaping | molding method is not specifically limited, You may use a well-known method. For example, known molding machines such as an extrusion molding machine, a compression molding machine, a vacuum molding machine, a blow molding machine, a T-die molding machine, an injection molding machine, and an inflation molding machine are used.

Next, the obtained biodegradable resin molded product is crosslinked to form a biodegradable resin crosslinked product. As a method for forming a crosslinked structure, a known method can be used. Examples thereof include a method of irradiating ionizing radiation and a method of using a chemical initiator. In the present invention, it is preferable to use a method of irradiating ionizing radiation.
As ionizing radiation, γ-rays, X-rays, β-rays or α-rays can be used. However, for industrial production, γ-ray irradiation with cobalt-60 or electron beam irradiation with an electron beam accelerator is preferable.
The irradiation with ionizing radiation is preferably performed in an inert atmosphere or air except for air. This is because the active species generated by irradiation with ionizing radiation is inactivated by binding to oxygen in the air and the crosslinking effect is lowered.

The dose of ionizing radiation is preferably 50 kGy or more and 200 kGy or less.
Depending on the amount of the crosslinkable monomer, the biodegradable resin can be crosslinked even when the dose of ionizing radiation is 1 kGy or more and 10 kGy or less. However, in order to crosslink almost 100% of the biodegradable resin molecules, The irradiation dose is preferably 50 kGy or more. Furthermore, in order to suppress a change in shape and swell uniformly when immersed in a liquid impregnating material in a later step, the ionizing radiation dose is preferably 80 kGy or more.
On the other hand, the irradiation dose of ionizing radiation is 200 kGy or less because the biodegradable resin has the property of being disintegrated by radiation when the resin alone is used. Therefore, when the irradiation dose of ionizing radiation exceeds 200 kGy, it is decomposed contrary to crosslinking. It is because it will advance. The upper limit of the ionizing radiation dose is preferably 150 kGy, and more preferably 100 kGy.

Instead of crosslinking with ionizing radiation, the biodegradable resin is mixed with a crosslinkable monomer and a chemical initiator, molded into a desired shape, and raised to a temperature at which the chemical initiator is thermally decomposed. A biodegradable resin crosslinked product may be prepared.
As the crosslinkable monomer, the same substance as in the above embodiment can be used.
Chemical initiators include dicumyl peroxide that generates peroxide radicals by thermal decomposition, propionitrile peroxide, benzoyl peroxide, di-t-butyl peroxide, diacyl peroxide, pelargonyl peroxide, myristoyl peroxide, Any catalyst that initiates the polymerization of a monomer such as a peroxide catalyst such as t-butyl benzoate or 2,2′-azobisisobutyronitrile may be used.
The temperature conditions for crosslinking can be appropriately selected depending on the type of chemical initiator. Crosslinking is preferably performed in an inert atmosphere or air except for air, as in the case of irradiation with radiation.

The crosslinked biodegradable resin obtained by the above-described method is immersed in an impregnating material containing a liquid plasticizer or a polymerizable monomer heated to the temperature as described above.
The impregnating material containing the plasticizer or polymerizable monomer can be used without particular limitation as long as it is liquid at room temperature, or is solid at room temperature and can be heated and melted to become liquid. .
In the present invention, the biodegradable resin is cross-linked with radiation before impregnating the impregnating material into the biodegradable resin. Therefore, when selecting the impregnating material, it is necessary to consider resistance to cross-linking means such as radiation and cross-linking inhibition. There is no. The impregnating material can be arbitrarily selected only by compatibility with the biodegradable resin, and the cross-linked state of the biodegradable resin can be controlled regardless of the impregnating material.

The plasticizer used as the impregnating material preferably has a high affinity with the biodegradable resin because it is necessary to impregnate the biodegradable resin. Therefore, as the impregnating material, a material which is weak but polar and does not have a large molecular weight is preferable, and a biodegradable resin or a derivative thereof is most suitable.
Specifically, the plasticizer preferably contains at least one of the following (a) to (c).
(A) Plasticizer containing a fatty acid polyester derivative or rosin derivative (b) Plasticizer containing a dicarboxylic acid derivative (c) Plasticizer containing a glycerin derivative Among them, the biodegradability of the biodegradable resin composite of the present invention is more enhanced. In order to keep it high, it is preferable to have biodegradability. Specifically, the biodegradability of biodegradable resins and other low molecular weight polyesters or derivatives thereof, dicarboxylic acids and glycerin derivatives, lactones, etc. is recognized. The plasticizers that are used are preferred.

Examples of the aliphatic polyester derivatives include polycondensates and copolycondensates of aliphatic diols and aliphatic dicarboxylic acids or derivatives thereof as main components, and aliphatic diols and aliphatic dicarboxylic acids or derivatives thereof and hydroxycarboxylic acids. More specifically, for example, α-hydroxycarboxylic acids (for example, glycolic acid, lactic acid, hydroxybutyric acid, etc.), hydroxydicarboxylic acids (for example, malic acid), hydroxytricarboxylic acids (for example, , Citric acid, etc.) and the like, polymers, copolymers or mixtures thereof. Among these, it is preferable to use a biodegradable resin as the fatty acid polyester.
The molecular weight of the aliphatic polyester is preferably smaller than the molecular weight of the biodegradable resin constituting the biodegradable resin composite. Specifically, it is 1 × 10 ⁵ or less, more preferably 1 × 10 ⁴ or less, and further preferably 1 × 10 ² to 1 × 10 ³ .
As the derivative of the aliphatic polyester, a known compound obtained by chemically modifying the aliphatic polyester can be used. Among them, it is preferable to use “Lactosizer GP-4001 (trade name)” manufactured by Arakawa Chemical Industries, which is a plasticizer containing a biodegradable resin derivative.

Examples of the rosin derivative include raw rosins such as gum rosin, wood rosin or tall oil rosin, stabilized rosin or polymerized rosin obtained by disproportionating or hydrogenating the raw rosin, other rosin esters, reinforced rosin esters, rosin phenol And rosin-modified phenolic resin.
Among them, in the present invention, it is particularly preferable to use “Lactosizer GP-2001 (trade name)” manufactured by Arakawa Chemical Industries, which is a plasticizer containing a rosin derivative.

Examples of the dicarboxylic acid derivative include an ester of dicarboxylic acid, a metal salt of dicarboxylic acid, and an anhydride of dicarboxylic acid.
As said dicarboxylic acid, it is C2-C50, especially C2-C20 linear or branched saturated or unsaturated aliphatic dicarboxylic acid, C8-C20 aromatic dicarboxylic acid, and number average molecular weight 2000. In the following, particularly, 1000 or less polyether dicarboxylic acid and the like can be mentioned. Among these, aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid or decanedicarboxylic acid, and aromatics such as phthalic acid, terephthalic acid and isophthalic acid Dicarboxylic acids are preferred.

The dicarboxylic acid derivative is preferably a dicarboxylic acid ester. Examples of the ester of dicarboxylic acid include bis (methyldiglycol) adipate, bis (ethyldiglycol) adipate, bis (butyldiglycol) adipate, methyldiglycolbutyldiglycoladipate, methyldiglycolethyldiglycoladipate, ethyl Diglycol butyl diglycol adipate, dibenzyl adipate, benzylmethyl diglycol adipate, benzylethyl diglycol adipate,
Benzyl butyl diglycol adipate, bis (methyl diglycol) succinate, bis (ethyl diglycol) succinate, bis (butyl diglycol) succinate, methyl diglycol ethyl diglycol succinate, methyl diglycol butyl diglycol succinate, ethyl di Glycol butyl diglycol succinate, dibenzyl succinate, benzyl methyl diglycol succinate, benzyl ethyl diglycol succinate, benzyl butyl diglycol succinate, ethyl methyl diglycol adipate, ethyl butyl diglycol adipate, butyl methyl diglycol adipate , Butyl butyl diglycol adipate, ethyl methyl diglycol succinate, ethyl ethyl diglycol succinate , Ethyl butyl diglycol succinate, butyl methyl diglycol succinate, butyl ethyl diglycol succinate, butyl butyl diglycol succinate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, bis (2-ethylhexyl) phthalate, di-n -Octyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, diisononyl phthalate, ethyl phthalyl ethylene glycolate and the like.

  The dicarboxylic acid derivative is preferably an esterified product represented by an acetylated product of a dicarboxylic acid such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid or phthalic acid. In particular, in the present invention, it is particularly preferable to use “DAIFFFITY-101 (trade name)” manufactured by Daihachi Chemical Industry Co., Ltd., which is an adipic acid ester.

Examples of the glycerin derivative include derivatives obtained by esterifying glycerin. More specifically, glycerin fatty acid monoester, glycerin fatty acid diester, or glycerin fatty acid triester is exemplified.
Examples of fatty acids constituting the esters include saturated or unsaturated fatty acids having 2 to 22 carbon atoms. Specifically, acetic acid, propionic acid, butyric acid (butanoic acid), isobutyric acid, valeric acid (pentanoic acid), Valeric acid, caproic acid (hexanoic acid), heptanoic acid, caprylic acid, nonanoic acid, capric acid, isocapric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, oleic acid, linol An acid, erucic acid, 12-hydroxy oleic acid, etc. are mentioned. The two or three fatty acids constituting the glycerin fatty acid diester or the glycerin fatty acid triester may be the same or different.

  In particular, in the present invention, acetylated glycerin such as triacetylglyceride (commonly called triacetin) and “Riquemar PL (series)” manufactured by Riken Vitamin Co., Ltd., which is an acetylated monoglyceride, is suitable as the glycerin derivative.

  In addition, useful substances such as drugs, agricultural chemicals, medicines and foods may be used as the plasticizer. By using such a useful substance as an impregnating material and supporting the useful substance on the cross-linked network of the biodegradable resin in the biodegradable resin composite of the present invention, the useful substance can be obtained as the biodegradable resin is biodegraded. A sustained release system that is released can be constructed.

Furthermore, when using the said polymerizable monomer as an impregnating material, it is preferable to contain at least 1 type of following (d)-(h).
(D) Low molecular weight polymer having acrylic monomer or / and acrylic group (e) Low molecular weight polymer having methacrylic monomer or / and methacrylic group (f) Styrene monomer (g) Allyl monomer or / and allyl group Low molecular weight polymer (h) Low molecular weight polymer having a vinyl monomer and / or vinyl group

Examples of the acrylic or methacrylic monomer include acrylic acid, methacrylic acid, methyl (meth) acrylate, glycidyl methacrylate (glycidyl methacrylate), 1,6-hexanediol di (meth) acrylate, 1,4-butanediol di ( (Meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, ethylene oxide modified bisphenol A di (meth) acrylate, diethylene glycol di (meta) ) Acrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, caprolactone modified dipenta Lithitol hexaacrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, polyethylene glycol di (meth) acrylate, tris (acryloxyethyl) isocyanurate, tris (methacryloxyethyl) isocyanurate, etc. Can be mentioned.
The low molecular weight polymer having an acrylic group or the low molecular weight polymer having a methacryl group is a low molecular weight polymer having a molecular weight of about 100 to 1000 obtained by polymerizing one or more of the acrylic or methacrylic monomers. Can be mentioned.

  Examples of the styrenic monomer include styrene, p-methyltoluene, etc., which have a functional group mainly at the para position, styrene sulfonate, chlorostyrene, α-methylstyrene, tert-butylstyrene, chloromethylstyrene, and the like. Can be mentioned.

Examples of the allyl monomers include triallyl isocyanurate, trimethallyl isocyanurate, triallyl cyanurate, trimethallyl cyanurate, diallylamine, triallylamine, diacrylic chlorate, allyl acetate, allyl benzoate, and allyl dipropiocyanate. Nurate, allyl octyl oxalate, allyl propyl phthalate, bityl allyl malate, diallyl adipate, diallyl carbonate, diallyl dimethyl ammonium chloride, diallyl fumarate, diallyl isophthalate, diallyl malonate, diallyl oxalate, diallyl phthalate, diallyl propyl Isocyanurate, diallyl sebacate, diallyl succinate, diallyl terephthalate, diallyl tartrate, dimethyl ali Phthalate, ethyl allyl malate, methyl allyl fumarate, methyl meta-allyl maleate, diallyl monoglycidyl isocyanurate.
Examples of the low molecular weight polymer having an allyl group include a low molecular weight polymer having a molecular weight of about 100 to 1000 obtained by polymerizing one or more of the allyl monomers.

Examples of the vinyl monomers include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl bivalate, vinyl octylate, vinyl monochloroate, adipine Examples include divinyl acid, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, and vinyl cinnamate.
Examples of the low molecular weight polymer having a vinyl group include low molecular weight polymers having a molecular weight of about 100 to 1,000, which are obtained by polymerizing one or more of the vinyl monomers.

As long as the temperature of the impregnating material when immersing the biodegradable resin crosslinked product is a temperature that can maintain a liquid state at a temperature lower than the temperature at which the impregnating material vaporizes as described above, the temperature is appropriately determined according to the type of the impregnating material. You can choose.
In order to quickly diffuse the impregnating material into the crosslinked structure of the biodegradable resin crosslinked product, a high temperature is preferable, but generally a range of 65 to 120 ° C., more preferably 80 to 120 ° C. is preferable.
Further, the immersion time is not particularly limited, but generally, the diffusion phenomenon is proportional to the square of the thickness, and therefore it is preferably in the range of 5 minutes to 20 hours depending on the thickness. The thing of the thickness within 1 mm can also shorten immersion time to 5-120 minutes, and also 30-90 minutes. On the other hand, when the thickness is several mm or more, it is preferable to increase the thickness to 10 to 20 hours.

The biodegradable resin and the impregnated material are combined by impregnating the impregnated material inside the biodegradable resin crosslinked material and cooling the biodegradable resin crosslinked material to the vicinity of room temperature in the swollen state. In addition, the biodegradable resin composite of the present invention is obtained.
The biodegradable resin composite of the present invention thus produced is impregnated with an impregnating material in a crosslinked network of biodegradable resin.

The biodegradable resin composite of the present invention thus obtained preferably has an impregnating material content in the biodegradable resin composite of 5% by mass or more and 70% by mass or less. When a plasticizer is used as the impregnating material in order to ensure flexibility at or below the glass transition temperature of the biodegradable resin composite, the lower limit of the content of the impregnating material is preferably 5% by mass. In order to exhibit the effect of improving flexibility, the content of the impregnating material is preferably 10% by mass or more, and particularly preferably 20% by mass or more.
The reason why the upper limit of the impregnating material content is 70% by mass is that when the impregnating material content exceeds 70% by mass, precipitation of the impregnating material, so-called bleeding may occur. The impregnating material content is more preferably 65% by mass or less.
The content of the impregnating material is measured by the method described in the examples.

  Further, when the polymerizable monomer is included as the impregnating material and the impregnating material is polymerized, it is preferable to perform the polymerization using ionizing radiation as in the first cross-linking of the biodegradable resin. In that case, the ionizing radiation to be used is the same as the first cross-link of the biodegradable resin, and γ rays, X rays, β rays or α rays can be used. For industrial production, γ-ray irradiation with cobalt-60 and electron beam with an electron beam accelerator are preferred. The amount of irradiation depends somewhat on the amount of the polymerizable monomer impregnated, but it is not required to be as much as the first crosslinking, and is effective even at several kGy to several tens kGy.

The present invention provides a biodegradable resin composite produced by the production method described above.
Further, impregnation containing a plasticizer or a polymerizable monomer in one or more cross-linked products of biodegradable resins selected from polysaccharides, aliphatic polyesters, and copolymers of aliphatic polyesters and aromatic polyesters. A biodegradable resin composite obtained by compounding by impregnating a material is provided. The biodegradable resin composite is characterized in that a cross-linked product of the biodegradable resin is made to have a required hardness by a plasticizer or a polymerizable monomer to be blended, and biodegradability having the characteristics is provided. If it is a resin composite, it will not be limited to what was manufactured by the said manufacturing method.

  Furthermore, the biodegradable resin composite obtained by the present invention is contained in a crosslinked network structure using a polar solvent such as methanol or DMSO (dimethylsulfoxide) in addition to the plasticizer and the crosslinkable monomer described above. Therefore, it can be applied to molecular sieves such as gel filtration and liquid chromatography. This is because the biodegradable resin complex of the present invention can exhibit a gel-like structure by the polar solvent, and can be widely used in the field of separation analysis technology by controlling the crosslinked structure by the method described above. Is possible.

The biodegradable resin composite produced by the production method of the present invention reliably maintains the shape and strength even at high temperatures exceeding the glass transition temperature or softening temperature of the biodegradable resin by the crosslinked network of the biodegradable resin. be able to. Furthermore, even below the glass transition temperature of the biodegradable resin, the crosslinkable network of the biodegradable resin is impregnated with the impregnating material, which inhibits the interaction between the biodegradable resin molecules, thereby increasing the hardness and brittleness. It has excellent flexibility and elongation. Thus, according to the method for producing a biodegradable resin composite of the present invention, it is possible to obtain a biodegradable resin composite that has simultaneously improved a plurality of material properties in a wide temperature range.
For this reason, the biodegradable resin composite of the present invention can be applied to general uses where petroleum synthetic polymer materials are currently used, particularly to uses where soft vinyl chloride is used such as rubber suckers. it can. Further, it can be used as a shape memory product that requires both flexibility and shape memory.

  Further, by using an impregnating material containing a polymerizable monomer and polymerizing the impregnating material, the impregnating material can be polymerized into a biodegradable resin. This makes it possible to produce a biodegradable resin composite that combines the properties of both the biodegradable resin and the polymer after the impregnating material is polymerized, and modifies the biodegradable resin having a low softening temperature. A function can be imparted to the biodegradable resin depending on the purpose, for example, a hard property even at a softening temperature or higher.

  Furthermore, since the biodegradable resin composite of the present invention has biodegradability, it has very little influence on the ecosystem in nature, and solves various problems related to disposal treatment that conventional plastics have. it can. Moreover, since the biodegradable resin composite of the present invention has unprecedented flexibility, it can be expected to be applied to fields where biodegradable resins could not be used so far. In addition, since it does not affect the living body, it is a material that can be applied to medical instruments such as syringes and catheters used inside and outside the living body.

  In addition, considering the biodegradability and biocompatibility or biodegradability of the biodegradable resin, the biodegradable resin composite of the present invention should be applied to a sustained release system of useful substances using its carrier characteristics. Can do. That is, if a biodegradable resin is impregnated as a plasticizer with a useful substance such as a drug or medicine, the impregnated useful substance is gradually released as the biodegradable resin decomposes. . Thus, the biodegradable resin composite of the present invention can be applied to a wide range of technical fields.

The first embodiment of the present invention will be described below.
In the method for producing a biodegradable resin composite of the present invention, first, a biodegradable resin crosslinked product is produced by the following procedure.
First, the biodegradable resin is softened by heating, or the biodegradable resin is dissolved or dispersed in a solvent in which the biodegradable resin can be dissolved. As the biodegradable resin, a biodegradable resin capable of introducing a crosslinked structure is used. In this embodiment, cellulose acetate (CDA) which is a polysaccharide biodegradable resin, polycaprolactone (PCL) which is an aliphatic polyester biodegradable resin, polybutylene succinate (PBS), aliphatic polyester and aromatic Polybutylene adipate terephthalate (PBAT), which is a polyester copolymer, is used.
Next, a crosslinkable monomer is added. Triallyl isocyanurate is used as the crosslinkable monomer. The addition amount of the crosslinkable monomer is 0.5 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the biodegradable resin.
After the addition, the mixture is stirred and mixed so that the crosslinkable monomer is uniform.
Then, when the solvent is first used, the solvent may be removed by drying.
Thus, the kneaded material which comprises a biodegradable resin molding is adjusted. The kneading temperature and kneading time may be appropriately selected depending on the types of the biodegradable resin and the crosslinkable monomer.

  The composition is softened again by heating or the like, and formed into a desired shape such as a sheet, a film, a fiber, a tray, a container, or a bag to form a formed body. This molding may be performed after the composition is adjusted, for example, in a dissolved state, or may be performed after being once cooled or removed by drying.

Subsequently, the obtained biodegradable resin molding is irradiated with ionizing radiation to crosslink the biodegradable resin to obtain a biodegradable resin crosslinked product.
The ionizing radiation is performed by electron beam irradiation by an electron beam accelerator.
The radiation irradiation amount may be appropriately selected from the range of 80 kGy or more and 200 kGy or less depending on the blending amount of the crosslinkable monomer, and the gel fraction of the biodegradable resin crosslinked product obtained after ionizing radiation irradiation is 80% by mass or more. It is trying to become.

Thereafter, the obtained biodegradable resin crosslinked product is immersed in an impregnating material containing a plasticizer.
In this embodiment, a plasticizer containing an aliphatic polyester derivative or a rosin derivative, a plasticizer containing a dicarboxylic acid derivative, or a plasticizer containing a glycerin derivative is used as the plasticizer.
The temperature of the impregnating material when immersed in the impregnating material is 65 to 120 ° C., which is a temperature at which the impregnating material can maintain a liquid state. Moreover, the time for immersing in the impregnating material is appropriately selected according to the thickness of the biodegradable resin crosslinked product. In the present embodiment, the thickness is 10 mm to 20 hours when the thickness is 0.1 mm or more.

The cross-linked biodegradable resin is impregnated with an impregnating material, and the cross-linked biodegradable resin is swollen and cooled to near room temperature. Cooling may be performed gradually by cooling, or may be rapidly cooled by water cooling or the like.
The biodegradable resin composite of the present embodiment thus obtained contains 5% by mass to 70% by mass of the impregnating material.

Next, a second embodiment of the present invention will be described.
In the second embodiment, after the biodegradable resin crosslinked product is formed by the same method as in the first embodiment, a polymerizable monomer is used as the impregnating material instead of the impregnating material used in the first embodiment, and biodegradable After the resin and the impregnating material (polymerizable monomer) are combined, the impregnating material is crosslinked. As the impregnating material of this embodiment, a polymerizable monomer and / or a low molecular weight polymer can be used. Specifically, a low molecular weight polymer having an acrylic monomer or / and an acrylic group, a low molecular weight polymer having a methacrylic monomer or / and a methacryl group, a styrene monomer, an allyl monomer or / and a low molecular weight polymer having an allyl group , Vinyl monomers and / or low molecular weight polymers having vinyl groups are used.

The biodegradable resin crosslinked product is immersed in the impregnating material by the same method and conditions as in the first embodiment to form a composite of the biodegradable resin and the impregnating material. Thereafter, the composite of the biodegradable resin and the impregnated material is irradiated with ionizing radiation, and the impregnated material is crosslinked to obtain a biodegradable resin composite.
The ionizing radiation is performed by electron beam irradiation with an electron beam accelerator, and the radiation irradiation amount is appropriately selected from the range of 1 kGy or more and 100 kGy or less in accordance with the type and blending amount of the polymerizable monomer.

  The biodegradable resin composite produced by the method of the second embodiment is obtained by impregnating an impregnating material containing a polymerizable monomer and then crosslinking the polymerizable monomer so that the polymerizable monomer is transformed into a biodegradable resin. It has become. The biodegradable resin composite has properties that combine the characteristics of both the biodegradable resin and the polymer produced by polymerization of the impregnating material. For example, when cross-linked polycaprolactone is impregnated with a methacrylic acid monomer to form polymethacrylic acid, polycaprolactone having a low softening temperature and impaired shape retention at 60 ° C. is affected by polymethacrylic acid having a hard property up to a glass transition temperature of 166 ° C. Reinforced and becomes hard even at 60 ° C. or higher.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited only to these Examples.

(Example 1)
As the biodegradable resin, a pellet-shaped polycaprolactone “Placcel H7 (trade name)” manufactured by Daicel Chemical Industries, Ltd. was used. A triallyl isocyanurate “TAIC (registered trademark, trade name)” manufactured by Nippon Kasei Kogyo Co., Ltd., which is one of allyl-based crosslinkable monomers, is prepared as a crosslinkable monomer, and an extruder (PCM30 type manufactured by Ikekai Tekko Co., Ltd.) is prepared. When the biodegradable resin is melt-extruded at a cylinder temperature of 160 ° C. using a peristaltic pump, the crosslinkable monomer is dropped at a constant speed with a peristaltic pump into the pellet supply section of the extruder, and the crosslinkable monomer is added to the biodegradable resin. . At that time, the addition amount was adjusted so that the amount of the crosslinkable monomer was 2 parts by mass with respect to 100 parts by mass of the biodegradable resin. The extruded product was cooled with water and pelletized with a pelletizer to obtain a pellet-like kneaded product of a biodegradable resin and a crosslinkable monomer.

The kneaded product was hot-pressed into a sheet at 160 ° C. and then rapidly cooled with water to produce a 500 μm thick sheet.
This sheet was irradiated with an electron beam at 90 kGy by an electron accelerator (acceleration voltage 10 MeV, current amount 12 mA) in an inert atmosphere excluding air to obtain a biodegradable resin crosslinked product.

  The obtained biodegradable resin crosslinked product was immersed in an impregnating material for 12 hours in a constant temperature bath at 105 ° C. to be expanded. As the impregnation material, a glycerin plasticizer “PL-710 (trade name)” manufactured by Riken Vitamin Co., Ltd., which is a plasticizer mainly composed of a glycerin derivative, was used. Thereafter, the impregnated material was returned to room temperature while being immersed, and the excess monomer was wiped off to obtain the biodegradable resin composite of the present invention.

(Examples 2 to 4)
Except that the biodegradable resin was polybutylene succinate “Bionore # 1020 (trade name)” manufactured by Showa High Polymer Co., Ltd., Example 2 was used, and the biodegradable resin was BASF. Example 3 was carried out in the same manner as in Example 1 except that the product was polybutylene adipate terephthalate “Ecoflex (trade name)”.
Similarly, the biodegradable resin was made from Daicel Chemical Industries, Ltd. cellulose acetate “L-30 (trade name)”, and the cylinder temperature and the molding temperature of the sheet were set to 190 ° C., in the same manner as in Example 1. Example 4 was adopted.

(Examples 5 to 8)
As the impregnating material, methacrylic acid, which is a polymerizable monomer, was used, and the immersion condition in the impregnating material was set at 80 ° C. for 12 hours, and after removing the impregnating material on the surface by pulling up from the impregnating material, the inertness except for air was removed. Except that the electron beam was irradiated with 90 kGy by an electron accelerator (acceleration voltage: 10 MeV, current amount: 12 mA) in an atmosphere, the same operations as in Examples 1 to 4 were performed, and Examples 5 to 8 were obtained.

(Comparative Examples 1-16)
Comparative Examples 1 to 8 were made in the same manner as in Examples 1 to 8, respectively, except that triallyl isocyanurate as a crosslinkable monomer was not blended.
Moreover, it was set as Comparative Examples 9-16 similarly to Examples 1-8 except not having performed electron beam irradiation, respectively.

In Examples and Comparative Examples, the gel fraction of the biodegradable resin crosslinked product before impregnation with the impregnating material was evaluated by the following method, and the impregnating material content rate or impregnating material fixing rate of the biodegradable resin composite after impregnation with the impregnating material was evaluated. Was evaluated by the following method.
(1) Evaluation of gel fraction After accurately measuring the dry mass of each biodegradable resin cross-linked product, wrapped in 200 mesh stainless steel wire, boiled in chloroform solution for 48 hours, and then dissolved in chloroform. The remaining gel content was obtained. After drying at 50 ° C. for 24 hours, chloroform in the gel was removed, and the dry mass of the gel was measured. Based on the obtained value, the gel fraction was calculated based on the following formula.
Gel fraction (%) = (dry weight of gel content / dry weight of biodegradable resin crosslinked product) × 100

(2) Evaluation of impregnating material content rate About Examples 1-4, the mass of the biodegradable resin crosslinked material in normal temperature before immersing in an impregnating material was measured previously, and it returned to normal temperature after immersing in an impregnating material. The mass of the later biodegradable resin composite was measured. Based on the obtained value, the impregnating material content was calculated based on the following formula.
Impregnation content (%) = {(A−B) / A} × 100
A: Mass of biodegradable resin composite B: Mass of biodegradable resin crosslinked product before impregnation into impregnation material

(3) Impregnating material fixation rate evaluation For Examples 5 to 8 in which the impregnating material was crosslinked after impregnating with the impregnating material, the sample was allowed to stand in an 80 ° C constant temperature bath for 24 hours and then returned to room temperature. Using the value B measured in (2), the impregnating material fixing ratio was calculated based on the following formula.
Impregnating material fixation rate (%) = {(C−B) / C} × 100
B: Mass of the biodegradable resin crosslinked product before impregnation into the impregnating material C: Mass of the biodegradable resin composite after 24 hours at 80 ° C.

  The results of the evaluation are summarized in Table 1 together with differences in manufacturing conditions. In the table, polycaprolactone is represented as PCL, polybutylene succinate as PBS, polybutylene adipate terephthalate as PBAT, and cellulose acetate as CDA.

  In each of Examples 1 to 8, biodegradable resin composites containing an impregnating material were obtained. In Examples 1 to 4, sheets that were more flexible and elastic than the original biodegradable resin were obtained. In Examples 5 to 8, on the contrary, a sheet having rigidity and higher stiffness than the original biodegradable resin was obtained. Thus, the hardness of the biodegradable resin could be adjusted by the impregnating material.

  In contrast to Examples 1 to 8, Comparative Examples 1 to 16 in which the biodegradable resin is not crosslinked are not impregnated with the impregnating material, and some of them are dissolved or become brittle and cracked. Could not be combined.

It is a schematic diagram for demonstrating the manufacturing process of the biodegradable resin composite_body | complex of this invention, (a) is a schematic diagram of biodegradable resin crosslinked material, (b) is biodegradable resin crosslinked material to an impregnation material. Schematic diagram showing the state when immersed, (c) is a schematic diagram of the biodegradable resin composite, (d) is a schematic diagram of the biodegradable resin composite cross-linked impregnating material in the biodegradable resin composite (E) is a schematic view when the biodegradable resin crosslinked product of (a) is microscopically viewed, and (f) is a microscopic view of the biodegradable resin composite of (c). (G) is a schematic view when the biodegradable resin composite obtained by crosslinking the impregnating material of (d) is viewed microscopically. It is a schematic diagram for explaining a phenomenon that occurs when an impregnating material is combined with a non-crosslinked biodegradable resin molded product, (a) is a schematic diagram of a non-crosslinked biodegradable resin molded product, (B) is a schematic diagram which shows a state when the biodegradable resin molding of (a) is immersed in an impregnation material, (c) is a schematic diagram which shows that shape collapse | disintegration occurs by permeation of an impregnation material. It is a schematic diagram for demonstrating another phenomenon which arises when an impregnating material is compounded with the biodegradable resin molding which is not bridge | crosslinked, (a) is a model of the biodegradable resin molding which is not bridge | crosslinked. (B) is a schematic diagram showing a state when the biodegradable resin molded product of (a) is immersed in an impregnating material, and (c) is a schematic diagram showing that the biodegradable resin molded product is recrystallized. It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crosslinkable biodegradable resin 11 Crosslink of biodegradable resin 2 Impregnated material 3 Biodegradable resin composite 4 Biodegradable resin composite obtained by polymerizing impregnated material 41 Polymerization of impregnated material 5 Biodegradable resin molded product 6 Crystallized biodegradable resin molding

Claims (9)

Forming a molded body from a kneaded product in which a crosslinkable monomer is blended with a biodegradable resin,
Cross-linking the biodegradable resin of the molded body to a biodegradable resin cross-linked product,
The biodegradable resin crosslinked product is immersed in an impregnated material containing a heated plasticizer or polymerizable monomer, and the biodegradable resin crosslinked product is impregnated with the impregnated material,
Cooling in a state where the biodegradable resin crosslinked product is swollen,
A method for producing a biodegradable resin composite, wherein the biodegradable resin is combined with the impregnating material.   The biodegradable resin according to claim 1, wherein the biodegradable resin is one or more biodegradable resins selected from among polysaccharides, aliphatic polyesters, and copolymers of aliphatic polyesters and aromatic polyesters. A method for producing a degradable resin composite.   The manufacturing method of Claim 1 or Claim 2 which bridge | crosslinks the said biodegradable resin by irradiation of ionizing radiation.   The biodegradable resin composite manufactured by the manufacturing method of any one of Claims 1 thru | or 3.   An impregnating material containing a plasticizer or a polymerizable monomer on a cross-linked product of one type or two or more types of biodegradable resins selected from polysaccharides, aliphatic polyesters, copolymers of aliphatic polyesters and aromatic polyesters A biodegradable resin composite which is impregnated and combined. The polysaccharide-based biodegradable resin includes natural polysaccharides such as cellulose, starch, chitin, chitosan and alginic acid, and derivatives obtained by acetylating or esterifying them,
The aliphatic polyester-based biodegradable resin is polycaprolactone (PCL), polybutylene succinate (PBS), polyethylene succinate, or polyethylene succinate adipate,
The biodegradable resin composite according to claim 4 or 5, wherein the biodegradable resin of the aliphatic polyester and aromatic polyester copolymer is polybutylene adipate terephthalate (PBAT). The biodegradable resin composite according to any one of claims 4 to 6, comprising at least one of the following (a) to (c) as the plasticizer.
(A) Plasticizer containing an aliphatic polyester derivative or rosin derivative (b) Plasticizer containing a dicarboxylic acid derivative (c) Plasticizer containing a glycerin derivative The biodegradable resin composite according to any one of claims 4 to 6, comprising at least one of the following (d) to (h) as the polymerizable monomer.
(D) Low molecular weight polymer having acrylic monomer or / and acrylic group (e) Low molecular weight polymer having methacrylic monomer or / and methacrylic group (f) Styrene monomer (g) Allyl monomer or / and allyl group Low molecular weight polymer (h) Low molecular weight polymer having a vinyl monomer and / or vinyl group   The biodegradable resin composite according to any one of claims 4 to 8, wherein a content of the impregnating material in the biodegradable resin composite is 5% by mass or more and 70% by mass or less.