CN100453581C - Biodegradable material and process for producing the same - Google Patents

Abstract

A biodegradable aliphatic polyester, such as polylactic acid, is mixed with a monomer having allyl and molded into a molding having the crosslinking degree of the biodegradable aliphatic polyester increased. Thereafter, the molding is exposed to ionizing radiation to thereby obtain a molding excelling in heat resistance. Triallyl isocyanurate or triallyl cyanurate is used as the monomer having allyl.

Description

Biodegradable material and its production method

Invention field

But the method that the present invention relates to a kind of Biodegradable material and produce this Biodegradable material.The present invention relates more specifically to the Biodegradable material made by thermotolerance, retention of configuration performance (being high rigidity), intensity and the good synthesizing biological degradable polymer materials of mouldability, with have the high heat-resisting factor and can be used as the Biodegradable material of heat-shrinkage material, and the method for producing this Biodegradable material.

Background technology

A lot of series products such as film, container, heat shrinkable material etc. form by molding oil synthesizing polymeric material.But after use, when being abandoned waste, its burning goes wrong.Following social concern has promptly appearred: the Global warming that heat that produces when burning because of product and waste gas cause; Contained toxic substance is to the influence of food and health in combustion gases after their burnings and the resistates; How to guarantee to abandon or the place safety of landfill refuse.

For these problems, having focused onto with starch and poly(lactic acid) is the biodegradable polymers of representative abandons oil synthetic polymer problem as solution material.Biodegradable polymers so can not cause detrimentally affect to global environment (comprising the ecosystem) than the heat (when this biodegradable polymers burns) of oil synthesized polymer deposits yields less amount and the circulation that keeps decomposition and resynthesis in physical environment.Generally speaking, having the aliphatic polyester resin that intensity and workability feature be equivalent to the oil synthetic polymer is the material of being paid close attention in recent years.

Particularly, poly(lactic acid) is by the starch preparation that comes from plant.Because of reducing the cost that large-scale production causes, it is cheaper than other biodegradable polymers that poly(lactic acid) more and more becomes in recent years.Therefore at present its application is being studied.

Because poly(lactic acid) has workability and the intensity that is equal to general oil synthetic polymer with regard to its feature, so poly(lactic acid) is the biodegradable resin approaching with the equivalent material of oil synthetic polymer.In addition, because poly(lactic acid) has the transparency that is equivalent to acrylic resin, therefore, the expection poly(lactic acid) will be used as its surrogate.Simultaneously, because poly(lactic acid) has high Young's modulus and high retention of configuration performance (being high rigidity), therefore expect that poly(lactic acid) is used as the surrogate of ABS resin, this ABS resin is as electric appliance casing and be used for various uses.

Yet poly(lactic acid) has glass transition point under near 60 ℃ relative low temperature.The Young's modulus modulus is reduced to such degree fast near 60 ℃: sheet glass becomes the tablecloth that is made of Vinylite suddenly.Therefore poly(lactic acid) has fatal defective: promptly poly(lactic acid) is difficult to the shape that keeps it to have at low temperatures.

The crystallising part of the poly(lactic acid) that just melts when reaching 160 ℃ of fusing points is not for showing the crystal of bulk (mass).Poly(lactic acid) is structurizing so not, to such an extent as to partly support whole intensity at normal crystallization.This is the reason that Young's modulus reduces fast.Young's modulus variation fast occurs near glass transition point, puts noncrystalline part rapid movement at this.Therefore the quick variation of Young's modulus is mainly owing to such fact: noncrystalline part is almost lost its intramolecular interaction being not less than under 60 ℃ the temperature.

Know, be to improve thermotolerance, with material with radiation exposure with to wherein introducing crosslinking structure.For example, know that heat-proof polythene obtains by the polyethylene that the radioactive ray irradiation with about 100kGy is used as near the fusing 100 ℃ of resins for universal use.Also know, in the time of in active polyfunctional monomer adds by the polymer materials material that constitutes and the material with low cross-linking efficient of easy decomposition, by promoting crosslinked to its irradiation radioactive ray.

When the polyfunctional poly compound was added biodegradable polymers, the high density that usually polyfunctional monomer is not less than the 5wt% of gross weight with concentration added wherein.When the Biodegradable material that has wherein added polyfunctional monomer with high density shines with radioactive ray, be difficult to make its 100% reaction, and the therefore monomer of remained unreacted.So the problem that occurs is: cross-linking efficiency is low, and this Biodegradable material is easily because of adding thermal distortion and reducing thermotolerance.

Usually, the Biodegradable material that is not less than 99% is classified as the material that decomposes by microbial process.Therefore, when the crosslinking technological that will use polyfunctional monomer was used for Biodegradable material, this Biodegradable material did not still belong to the Biodegradable material class, and this depends on the concentration of polyfunctional monomer.

Consider the thermotolerance of improving biodegradable polymers, know that poly(lactic acid) is only decomposed when shining with radioactive ray, therefore can not obtain effectively crosslinked.

As medical Biodegradable material, in Japanese Patent Application Laid-Open No.2002-114921 (patent documentation 1) and Japanese Patent Application Laid-Open No.2003-695 (patent documentation 2), disclosing the radioactive ray irradiation is not to be used to improve thermotolerance, but is used for sterilization.

In other words, provide a kind of composition in this patent documentation 1, wherein by heating biodegradable polymers molding and by the carry out disinfection reduction of back weight-average molecular weight of radioactive rays, by will polyfunctional monomer such as triallyl isocyanurate add in the biodegradable polymers and be suppressed to being no more than 30% of initial weight-average molecular weight.

A kind of medical material is provided in patent documentation 2, and it is made up of the polymer material that contains multifunctional triaizine compounds such as triallyl isocyanurate such as collagen, gelatin, poly(lactic acid) and polycaprolactam.This medical material can be by using the radioactive rays radiation sterilization with it.

Disclosed composition comprises that the thermal history neutralization of polyfunctional monomer when being suppressed at by heating biodegradable polymers molding reduces by the molecular weight of biodegradable polymers in the radiation exposure sterilizing process in the patent documentation 1 and 2.

The amount that discloses free-radical scavengers in the patent documentation 1 preferably is not less than 0.01wt%, by the 100wt% biodegradable polymers, in an embodiment, the 0.2wt% triallyl isocyanurate is added the 100wt% poly(lactic acid) of free-radical scavengers, and mixture is shone under 20kGy with gamma-radiation.

Yet, the other test of carrying out according to the inventor, found when the add-on of triallyl isocyanurate is 0.2wt%, be difficult to take place crosslinking reaction and gel section per-cent is lower than 3%, although with the gamma-radiation irradiation of biodegradable polymers with 20kGy.Therefore, this biodegradable polymers does not almost have crosslinking structure, therefore can not provide thermotolerance.

Having described the multifunctional triaizine compounds of being made up of triallyl isocyanurate that will be not less than 0.01wt% in patent documentation 2 adds in the biodegradable polymers, in an embodiment, the triallyl isocyanate of 1wt% is added in the poly(lactic acid), this poly(lactic acid) is shone under 25kGy with gamma-radiation, and gel component per-cent is set at 67%.Yet when gel component per-cent was 67%, poly(lactic acid) is easy deformation in having the atmosphere of 60 ℃ (being the glass transition temp of poly(lactic acid)) of surpassing.Therefore, can not improve the low-profile performance (being high rigidity) and the bad thermotolerance of poly(lactic acid).

For making the heat-stable method of poly(lactic acid), disclose following technology at " the Grade advancedterramack of injection molding of highly heat-resistant Polylacticacid " of magazine " PlasticAge " (rather than patent documentation 1): the particle that nano level fine particle mineral filler is mixed with poly(lactic acid) to have passed through nucleogenesis in the quite short time improves degree of crystallinity.What the method for describing in above-mentioned paper made might take out mixture from die head in tens of minutes to several minutes, so prepare heat-proof polylactic acid.Although improved cost in industrial production, adding is not less than 1 to 5wt% opaque clay filler, by the gross weight of poly(lactic acid).Therefore, poly(lactic acid) is lost its transparency.Filler makes originally as the slick poly(lactic acid) surface roughen of glass simultaneously.Therefore, the defective of the product that is made of said composition is, it looks not meticulous, and therefore the product that is made of said composition can use in limited range.

In addition, the mineral filler of adding poly(lactic acid) can not be with the size dispersion bigger than its original size.Therefore the Strength Changes that occurs composition easily.In addition, between mineral filler and the base-material that constitutes by resin, do not have basic bonding, and reinforced effects depends on the intensity of filler itself.Therefore, must improve the intensity of the add-on of filler with enhancing composition.But the add-on that increases filler is damaged above-mentioned transparency and slickness.Another problem is, when molding contained the mixture of this filler, filler was passed in time easily and taken place from the phenomenon of oozing out that the resin as composition base comes out.

As improving the method that poly(lactic acid) does not at high temperature have the shortcoming of retention of configuration performance (being high rigidity) and its poor heat resistance, be increased to 90-95% by the noncrystalline part of reduction poly(lactic acid) and with its degree of crystallinity, can prevent that poly(lactic acid) is not less than 60 ℃ in temperature and softens and keep its shape down.

Yet, as the method that improves poly(lactic acid) degree of crystallinity, must be by its fusing being molded as different shape with poly(lactic acid) by injection moulding etc., wait for subsequently for a long time until not only being not less than glass transition temp but also not being higher than that crystallization no longer carries out under the temperature of its temperature of fusion.Therefore, for example for produce have thickness from several millimeters to the parts parts that are lower than 1 centimetre slightly, must be injection moulding is finished after these parts be remained in the die head heating under tens of minutes.Therefore, this method can not be used for industrial production, is not ideal therefore.

For the situation of Biodegradable material wherein, do not provide as yet and can be not less than 100-120 ℃ and be not less than the suitable heat shrinkable material of shrinking for 40% time in shrinking percentage in temperature as heat shrinkable material.

As the heat shrinkable material of making by this class Biodegradable material, in Japanese Patent Application Laid-Open No.2003-221499 (patent documentation 3), disclose the heat shrinkable material based on poly(lactic acid), its transparency adds based on the polymkeric substance of poly(lactic acid) with except that based on its transparency of improvement in the mixture of the aliphatic polyester the polymkeric substance of poly(lactic acid) by gathering carbodiimide.

Yet in containing the heat shrinkable material of poly(lactic acid), the glass transition temp of poly(lactic acid) is 50 ℃ to 60 ℃.Therefore, based on heat shrinkable material deformable and its poor heat resistance of poly(lactic acid).Disclose in the patent documentation 3, expanded down based on the heat shrinkable material of poly(lactic acid) 60-70 ℃ during heating, and do not expanded being not less than under the poly(lactic acid) fusing point at the glass transition temp (being lower than 60 ℃ slightly) of a little higher than poly(lactic acid).Therefore, it has the crystallising part thermal contraction of the low restoring force of resistance to deformation at it.The thermal contraction factor based on the heat shrinkable material of poly(lactic acid) only is 30 to 40% like this.

Mierocrystalline cellulose and starch are water wetted materials.Therefore become when wetting when Mierocrystalline cellulose and starch, different with oil synthetic polymer material, Mierocrystalline cellulose and starch are difficult to keep its intensity.In addition, different with the oil synthetic polymer material with sharp melting point, Mierocrystalline cellulose and starch can not be by melting molding with it.Be molding starch, it be similar to liquid, aqueous behind molding under the melted state, must anhydrate by being dried to remove in case of necessity.Have snappiness with water blended starch, but intensity is extremely low.On the other hand, exsiccant starch embrittlement and lack snappiness.

This specific character is owing to the hydroxyl of Mierocrystalline cellulose and starch.In other words, hydroxyl shows wetting ability because of its strong polarity, and then forms hydrogen bond and this key to thermally-stabilised between hydroxyl.Make it melt molding starch for being similar to the oil synthetic polymer by heating starch, the hydroxyl by esterification modification starch also is disclosed in patent No.2579843 and 3154056 the hydrophobic starch derivative that obtains of hydroxyl of esterification.

Yet the hydrophobicity esterified starch derivative is almost nonelastic and embrittlement.For example, when using above-mentioned lipid acid to carry out esterification, use above-mentioned acetic ester with lipid acid of lowest molecular weight as the lipid acid of substituted radical, has intensity to a certain degree, but almost nonelastic and have a very high Young's modulus, therefore the resin that is highly brittle for having similar glass properties.

When having high-molecular weight lipid acid (being higher fatty acid) when being used for esterification, the intermolecular forces in the starch molecule reduces.As a result, become deformable and can make it have elasticity of starch derivative.But because intermolecular forces reduces, its intensity reduces.

By the product of commercial hydrophobic starch derivative preparation, its intensity and expansion per-cent improve by Biodegradable polyester or mineral filler are added in the hydrophobic starch derivative, as disclosed among the Japanese Patent Application Laid-Open No.8-502552 (patent documentation 4).

Yet, Biodegradable polyester is added the intensity that to improve hydrophobic starch itself in the hydrophobic starch, and only make hydrophobic starch near with the characteristic of its blended Biodegradable polyester, and the Biodegradable polyester that the strength ratio of hydrophobic starch derivative is added wherein is poor.Therefore the necessity of using the expansion hydrophobic starch is thrown doubt upon.Simultaneously, mineral filler is added destroyed slickness and transparency in the hydrophobic starch derivative.Therefore, use the product that contains mineral filler to have restriction.

Know, be to strengthen intensity, with radiation exposure to material so that it has crosslinking structure.Yet natural starch that decomposes polysaccharide and Mierocrystalline cellulose and derivative thereof are the material by decomposing with radiation exposure.Therefore, be that they decompose when they are applied radioactive rays.It is crosslinked to consider that starch and cellulosic derivative are undertaken by radioactive rays, knows, by obtaining cross-linked material in the high concentration mixture heating back with water and said derivative with this mixture of radiation exposure.In other words, water is necessary for being undertaken crosslinked by radioactive rays.Even do not using under the situation of carrying out chemical bonding under the radioactive rays, the reaction in water-free system also is difficult to carry out.

Because hydropholic starch derivatives is water insoluble, therefore can not mediate by water.Therefore can not be by using the crosslinked lyophobic dust of conventional planning line that uses in the crosslinked field.In addition, can not be by the aldehyde crosslinked lyophobic dust of linking agent as the chemical treatment that is used for cross-linking starch.

Patent documentation 1: Japanese Patent Application Laid-Open No.2002-114921

Patent documentation 2: Japanese Patent Application Laid-Open No.2003-695

Patent documentation 3: Japanese Patent Application Laid-Open No.2003-221499

Patent documentation 4: Japanese Patent Application Laid-Open No.8-502552

Non-patent literature 1: " Grade advancedterramack of injection molding of highlyheat-resistant Polylactic acid " (the April, 2003, issue of " Plastic Age ", pages 132 to135).

Summary of the invention

The present invention is based on the problems referred to above carries out.Therefore; an object of the present invention is to provide a kind of Biodegradable material; the product that its thermotolerance of this material improvement constitutes Biodegradable material thus is as the surrogate of the product that is made of moulded plastic such as film, wrapping material, protecting materials, sealing material etc.; and after use,, and provide a kind of manufacture method of industrial practicality because of its biodegradable performance can solve the problem that abandons waste.

More specifically, first purpose of the present invention provides and a kind ofly makes it have stable on heating Biodegradable material by improving it being not less than the retention of configuration performance of deterioration under the glass transition point (being high rigidity), and its transparency of this Biodegradable material, surface luster and slickness are not destroyed.

Second purpose of the present invention provides a kind ofly to be had high heat shrinkability characteristic, can be preferred in the hot environment and can be used as the Biodegradable material of heat shrinkable material.

The 3rd purpose of the present invention provides as the Biodegradable material that has such intensity and turgidity simultaneously: this Biodegradable material can be used as the surrogate of oil synthetic polymer, and a large amount of other materials can not added in the hydrophobic polysaccharide derivates.

Embodiment

For realizing strengthening stable on heating first purpose of Biodegradable material, the inventor has carried out active research and has found, this purpose can by will have that allylic monomer mixes with biodegradable aliphatic polyester and with this mixture with radiation exposure so that molecule be cross-linked with each other and satisfy predetermined condition and realize.Especially, the inventor finds, poly(lactic acid) retention of configuration performance (being high rigidity) at high temperature can by with the noncrystalline part of poly(lactic acid) with contain that allylic monomer is full cross-linked to be improved, although poly(lactic acid) is decayed by radioactive rays, and it has been generally acknowledged that with common monomer can be not crosslinked.

Based on above-mentioned discovery, first invention provides a kind of Biodegradable material, it comprises by its gross weight and is not less than 95wt% and is no more than the biodegradable aliphatic polyester of 99wt%, and has the crosslinking structure of following mode: promptly this biodegradable aliphatic polyester has gel component per-cent (gel component dry weight/initial dry weight) and is not less than 75% and be no more than 95 so that Biodegradable material is heat-resisting.

Be to measure gel component per-cent, the membrane sealed of predetermined amount in 200 purpose wire nettings, was boiled it 48 hours in chloroform colloidal sol, remove dissolved colloidal sol inclusion, and the dry gel component that remains on the wire netting.In this manner, measure the weight of film.By following Equation for Calculating gel component per-cent:

Gel component per-cent (%)=(gel component dry weight)/(initial dry weight) * 100

As mentioned above, in the Biodegradable material of first invention, the gel component per-cent that constitutes the polymkeric substance (it is the major constituent of biodegradable aliphatic polyester) of biodegradable aliphatic polyester is set at is not less than 75%, and the polymkeric substance more than 75% forms with crosslinking structure, generates countless three-dimensional screen structures thus in polymkeric substance.Can make Biodegradable material have the thermotolerance of following degree like this: promptly it is not less than under the glass transition temp of polymkeric substance indeformable in temperature.Therefore this Biodegradable material has improved thermotolerance, has the retention of configuration performance (being high rigidity) that is similar to the rosin products of being made by the oil synthetic polymer, therefore can be used as its surrogate.In addition, because Biodegradable material of the present invention is biodegradable, so the present invention can solve the problem that abandons waste.

Have the method for the first heat-resisting Biodegradable material of inventing of crosslinking structure as preparation, preferably the biodegradable aliphatic polyester of allylic monomer of having of 1.2wt% to 5wt% and 100wt% is mediated; The uniform mixture that obtains is suppressed by this uniform mixture of heating under pressure, and quick then cooling is to be molded as desired shape with this uniform mixture; And, producing crosslinking reaction thus in such a manner with the uniform mixture of molding ionization radiation exposure, promptly biodegradable aliphatic polyester is to be no more than the 75% crosslinked of its total amount.

Preferably with poly(lactic acid) as biodegradable aliphatic polyester and use cyanacrylate or triallylcyanurate as having allylic monomer.

In other words, an object of the present invention is to provide a kind of have various performances that are equal to general oil synthetic polymer and the Biodegradable material that can replace it.Therefore, as biodegradable aliphatic polyester, poly(lactic acid), its L-and D-isomer and its mixture, poly-succinic crotonylidene ester, polycaprolactam and poly butyric ester have been listed for realizing that the object of the invention is used.These materials can use separately or be used in combination with its two or more.Consider cost and characteristic, poly(lactic acid) is specially suitable.

For improving the flexibility of Biodegradable material; as can be, can use softening agent such as glycerine, ethylene glycol, triacetyl glycerol liquids at normal temperatures or as biodegradable resin such as the polyglycolic acid and the polyvinyl alcohol solid at normal temperatures of softening agent to the additive that wherein adds.In addition, a small amount of other biodegradablely can be added in the poly(lactic acid) as softening agent.But be to use these softening agent in the present invention not necessarily.

As with aliphatic polyester blended monomer, the Acrylic Acid Monomer or the methacrylic acid monomer that have two or more pairs of keys in a molecule are effective: 1,6 hexanediol diacrylate, trimethylolpropane trimethacrylate (hereinafter referred to as TMPT) etc.But for obtaining high-crosslinking-degree under the lower concentration relatively, it is effective having allylic following monomer.

Cyanacrylate; front three is for the allyl group isocyanuric acid ester; triallylcyanurate; front three is for the allyl group cyanurate; diallyl amine; triallylamine; two acryl chlorine mattress acid esters; allyl acetate; the phenylformic acid allyl ester; allyl group dipropyl isocyanuric acid ester; oxalic acid allyl group octyl group ester; phthalic acid allyl group propyl diester; oxysuccinic acid butyl allyl ester; hexanodioic acid diallyl ester; carbonic acid diallyl ester; diallyldimethylammonium chloride; fumaric acid diallyl ester; properties of diallyl isophathalate; propanedioic acid diallyl ester; oxalic acid diallyl ester; diallyl phthalate; diallyl propyl group isocyanuric acid ester; sebacic acid diallyl ester; Succinic Acid diallyl ester; terephthalic acid diallyl ester; diallyltatolate; phthalic acid dimethyl-allyl ester; oxysuccinic acid allyl ethyl ester; fumaric acid methacrylic ester and oxysuccinic acid methyl methylallyl ester.

Cyanacrylate in these monomers (hereinafter referred to as TAIC) and front three are specially suitable for allyl group isocyanuric acid ester (hereinafter referred to as TMAIC).This TAIC is preferred especially for poly(lactic acid).Can be similar with TAIC and TMAIC basically for its effect of allyl group cyanurate by TAIC and TMAIC respectively by the triallylcyanurate and the front three of thermal conversion.

As above-mentioned ionizing rays, can use gamma-radiation, x-ray, beta-rays or α-ray.In industrial production, preferably from the gamma-radiation of cobalt 60 emissions with from rumbatron ejected electron bundle.For introducing crosslinking structure, emitting electrons radiation.But chemical initiator can be used for producing crosslinking reaction.

In the case, the monomer that will have allyl group and a chemical initiator adds in the Biodegradable material under temperature is not less than the fusing point of Biodegradable material, they is fully mediated and uniform mixing mutually.Temperature when then this moulding material being heated to the chemical initiator thermolysis.

As can be used for chemical initiator of the present invention, can use any peroxide catalyst that produces peroxide group such as dicumyl peroxide, peroxidation propionitrile, peroxidation penzoil, di-t-butyl peroxide, peroxidation diasyl, peroxidation beralgonyl, peroxidation mirystoil, TBPB tertiary butyl perbenzoate and 2,2 '-Diisopropyl azodicarboxylate; With the catalyzer that is used to cause monomer polymerization.Be similar to radiation exposure, preferably in the inert atmosphere of removing air or vacuum, carry out crosslinked.

For realizing above-mentioned first purpose, the inventor has carried out active research, finds that this purpose can be by realizing by crosslinked mutually combining biodegradable aliphatic polyester and hydrophobic polysaccharide derivative for one.

Above-mentioned combination means therein two kinds of components separately in the dissolved solvent, and at least a portion of two kinds of components is contained in this solvent as because of crosslinked its insoluble material composition that makes.

Second Biodegradable material of finishing based on above-mentioned knowledge of inventing is made up of heat-resisting cross-linked material, and this material is by forming by crosslinked biodegradable aliphatic polyester that is together with each other and hydrophobic polysaccharide derivative.

Method as second invention of making heat-resisting Biodegradable material, derive and polyfunctional monomer is not less than under the temperature of biodegradable aliphatic polyester mutually uniform mixing in temperature after, at biodegradable aliphatic polyester, hydrophobic polysaccharide this mixture ionization radiation irradiation.

In the heat-resisting Biodegradable material of second invention with crosslinking structure, with biodegradable aliphatic polyester and hydrophobic polysaccharide derivates crosslinked so that its be together with each other and the countless tridimensional networks of formation in polymkeric substance.Can make Biodegradable material have the thermotolerance of such degree like this, promptly it is not less than under the glass transition temp of polymkeric substance indeformable in temperature.Especially, in the time will melting molding temperature basically and be set at 150 ℃ to 200 ℃, this temperature is not less than the fusing point of biodegradable aliphatic polyester and is not less than the softening temperature of hydrophobic polysaccharide derivates, and the tensile strength of this Biodegradable material and its expansion per-cent under near the high temperature 150 ℃ to 200 ℃ is respectively 30 to 70g/mm ²With 20 to 50%.In other words, this Biodegradable material is set at low and its tensile strength height of its expansion per-cent.

As mentioned above, because Biodegradable material is set at high temperature low and its tensile strength height of its expansion per-cent to prevent its distortion, therefore this Biodegradable material at high temperature has retention of configuration performance (being high rigidity), and has improved the thermotolerance as the Biodegradable material shortcoming.Therefore, this Biodegradable material can be widely used as the material of Industrial products.Therefore, the product made of Biodegradable material has the retention of configuration performance (being high rigidity) that is similar to the resins for universal use product that the oil synthetic polymer makes and can be used as its substituent.In addition, because the product that Biodegradable material is made is biodegradable, therefore can solve the refuse problem that abandons by the product that uses Biodegradable material to make.

In the heat-resisting Biodegradable material of second invention,, use and the similar poly(lactic acid) of first invention as biodegradable aliphatic polyester with crosslinking structure.As the cross-linking type polyfunctional monomer, the preferred allylic monomer that has that is similar to first invention that uses.As ionizing rays, the preferred radioactive rays that are similar to first invention that use.Except ionizing rays, chemical initiator can be used to produce crosslinking reaction.

For realizing second purpose, the 3rd invention provides a kind of Biodegradable material, and its thermal contraction factor can uprise and can be used as heat shrinkable material.

The heat-shrinkable Biodegradable material of the 3rd invention is by biodegradable aliphatic polyester and have the monomeric mixture of allylic lower concentration and form.Mixture is by adding under the state crosslinked in the mixture with this mixture of ionization radiation irradiation or with chemical initiator therein, and this mixture is expanding under it applies heat.When this mixture is not less than when heating under the temperature of using when expanding in temperature, the contraction factor of this mixture is not less than 40% and be no more than 80%.

More specifically, poly(lactic acid) is used as biodegradable aliphatic polyester.To be set at 10 to 90% by the gel component per-cent (gel component dry weight/initial dry weight) that crosslinked this mixture obtains.The contraction factor of this mixture is set at when being no more than 140 ℃, be lower than 10%, be 40 to 80% when being not less than 160 ℃.

The above-mentioned thermal contraction factor is defined as follows:

For sheet material

(length) contraction factor (%)=(length after perisystolic length-contraction)/(perisystolic length) * 100 and

For pipe:

(internal diameter) contraction factor (%)=(internal diameter after perisystolic internal diameter-contraction)/(perisystolic internal diameter) * 100.

Therefore, when contraction factor was 50%, the length of sheet material (pipe) became 1/2 (50%) of raw footage (internal diameter).

When contraction factor was 80%, the length of sheet material (pipe) became 20% of raw footage (internal diameter).

As mentioned above,, the add-on of cross-linking type polyfunctional monomer is set at wherein mixture to a certain extent in the agglomerative scope in third aspect present invention, simultaneously, use may minimum cross-linking type polyfunctional monomer so that its concentration is low.So in subsequent step, gel component per-cent is set at 10 to 90% during with the ionization radiation irradiation at mixture, preferred 50 to 70%, so strengthen thermotolerance and its contraction factor of Biodegradable material.When this gel component per-cent is too low, does not obviously form the network that to store and do not shrink.

The required gel component per-cent of being made up of oil synthetic resins of conventional heat shrinkable material contraction is 10 to 30%, and among the present invention, gel component per-cent when aliphatic polyester, particularly the gel component per-cent of poly(lactic acid) increased to 90% o'clock, made that Biodegradable material is a heat-shrinkable.

When gel component per-cent was too high, so firm by the network that is cross-linked to form, to such an extent as to deflection, promptly elongation was too little, although the convergent force height.Contraction factor is low as a result.Therefore gel component per-cent is preferably 50 to 70%.

In the 3rd invention of making the heat-shrinkable Biodegradable material, the cross-linking type polyfunctional monomer is added in the Biodegradable material with lower concentration, this cross-linking type polyfunctional monomer and Biodegradable material are mediated, and this mixture is molded as pre-setting by this mixture of heating under pressure; This mixture is cooled off fast; With this mixture with ionization radiation irradiation to produce crosslinking reaction, its gel component per-cent is set at and is not less than 10% and be not higher than 90% like this; Behind this mixture usefulness ionization radiation irradiation, this mixture is not less than the Biodegradable material temperature of fusion and when high temperature does not heat under by the temperature that temperature of fusion and 20 ℃ of additions are obtained in temperature, this mixture expansion forms the mixture as heat shrinkable material.

In the heat-shrinkable Biodegradable material of the 3rd invention,, use and the similar poly(lactic acid) of first invention as biodegradable aliphatic polyester with crosslinking structure.As the cross-linking type polyfunctional monomer, the preferred allylic monomer that has that is similar to first invention that uses.As ionizing rays, the preferred radioactive rays that are similar to first invention that use.Except ionizing rays, chemical initiator can be used to produce crosslinking reaction.

For realizing the 3rd purpose, the inventor has carried out active research, discovery can be by mediating polyfunctional monomer and hydrophobic polysaccharide derivates, crosslinked with this mixture of ionization radiation irradiation then by the radioactive rays realization, and pass through the crosslinked hydrophobic polysaccharide derivates of radioactive rays such as acetic ester starch and its intensity of Mierocrystalline cellulose and expand good.

Based on above-mentioned discovery, the 4th invention provide a kind of by hydrophobic polysaccharide derivates and cross-linking type polyfunctional monomer as having the Biodegradable material that allylic monomer is formed, this cross-linking type polyfunctional monomer adds hydrophobic polysaccharide derivates makes the mixture of hydrophobic polysaccharide derivates and cross-linking type polyfunctional monomer have crosslinking structure, and the gel component per-cent of this crosslinking structure (gel component dry weight/initial dry weight) is 10 to 90%.

In the method for the 4th invention of making Biodegradable material, polyfunctional monomer is added in the hydrophobic polysaccharide derivates, the mixture of polyfunctional monomer and hydrophobic polysaccharide derivates is mediated, after this mixture is molded as predetermined shape, with this moulding material ionization radiation irradiation, this Biodegradable material has crosslinking structure like this.

In the heat-shrinkable Biodegradable material of the 4th invention,, use and the similar poly(lactic acid) of first invention as biodegradable aliphatic polyester.As the cross-linking type polyfunctional monomer, the preferred allylic monomer that has that is similar to first invention that uses.As ionizing rays, the preferred radioactive rays that are similar to first invention that use.Except ionizing rays, chemical initiator can be used to produce crosslinking reaction.

The invention effect

As mentioned above, because the Biodegradable material of first to fourth each invention has the enhanced thermotolerance.Therefore they can be extensive use of.Especially, this Biodegradable material almost has no adverse effect to natural ecosystems.Therefore this Biodegradable material can be used as the material that substitutes plastic prod scale operation and that abandon.In addition, because this Biodegradable material has no adverse effects to organism, so it is applicable in vivo and the outer medical device that uses of organism.

Because the gel component per-cent of the heat-resisting Biodegradable material of first invention is set at 75 to 95%, therefore, has improved biodegradable aliphatic polyester thermotolerance greatly.

The heat-resisting Biodegradable material of second invention can improve biodegradable aliphatic polyester, particularly poly(lactic acid) and be not less than retention of configuration performance (being high rigidity) under 60 ℃ in temperature.In addition because hydrophobic polysaccharide derivates is added in the poly(lactic acid) at high temperature to keep the intensity of Biodegradable material, therefore with wherein use mineral filler different, transparency and its surface luster of poly(lactic acid) done little harm.In addition, although must set high temperature in industrial production, this Biodegradable material can pass through to use conventional injection moulding apparatus manufacturing, and can not reduce productivity.Simultaneously, because hydrophobic polysaccharide derivates is biodegradable, therefore almost natural ecosystems are had no adverse effect.Like this, expect that this Biodegradable material is used as the material of the plastic prod that substitutes scale operation and abandon.

The heat-shrinkable Biodegradable material of the 3rd invention is inflatable to reaching about 5 times of original length.When this expansible heat shrinkable material being heated to temperature when being not less than the temperature of its fusing point, because the network that its shape is stored, it can be in 40 to 80% times thermal contractions of contraction factor.Because crystallising part and under the glass transition temp of about poly(lactic acid) infusible network portion, so its shape invariance shape of this heat shrinkable material and have resistance toheat.

The successful part of the 4th invention is by making it crosslinked with the hydrophobic polysaccharide derivates of ionization radiation irradiation.In addition, can improve low strength greatly by molecule crosslinked effect as hydrophobic polysaccharide derivates shortcoming.Especially at high temperature can expect this effect.Simultaneously, because hydrophobic polysaccharide derivates is also biodegradable, so it almost has no adverse effect to natural ecosystems.Like this, expect that this Biodegradable material is used as the material of the plastic prod that substitutes scale operation and abandon.

Description of drawings

Fig. 1 is the graph of a relation of electron beam irradiation dose and gel component per-cent in the embodiment 1 to 5 that shows first embodiment of the present invention and the comparative example 1 to 8.

Fig. 2 is tensile strength in the tension test of carrying out in the embodiment 1 to 5 that shows first embodiment of the present invention and the comparative example 1 to 8 and the graph of a relation between the irradiation dose in 180 ℃ atmosphere.

Fig. 3 is fracture expansion in the tension test of carrying out in the embodiment 1 to 5 that shows first embodiment of the present invention and the comparative example 1 to 8 and the graph of a relation between the irradiation dose in 180 ℃ atmosphere.

Fig. 4 is the graph of a relation of electron beam irradiation dose and gel component per-cent in the embodiment 6 to 11 that shows second embodiment of the present invention and the comparative example 9 to 18.

Fig. 5 is tensile strength in the tension test of carrying out in the embodiment 6 to 11 that shows second embodiment of the present invention and comparative example 15 and 16 and the graph of a relation between the irradiation dose in 100 ℃ atmosphere.

The structure of Fig. 6 (A) to (D) during and the synoptic diagram of the thermal contraction structure of sheet material for the crosslinking structure that shows the 3rd embodiment of the present invention, expansion texture, glass transition temp.

Fig. 7 (A) to (D) is for showing the synoptic diagram of uncrosslinked sheet material.

Fig. 8 is the graph of a relation between reading beam irradiation dose and the gel per-cent.

Fig. 9 is for showing the graph of a relation between shrinkage temperature and the contraction factor.

Figure 10 for the embodiment 12,13,18 that shows the 4th embodiment of the present invention and 19 and comparative example 27 in gel component per-cent with respect to the variation diagram of electron beam irradiation dose.

Figure 11 be in the embodiment 12 of fourth aspect present invention and the comparative example 27 the fracture elongation strengths with respect to the variation diagram of electron beam irradiation dose.

Reference symbol and icon

A: crystallising part

B: crystallising part not

C: network

Best mode for carrying out the invention

The Biodegradable material of first embodiment is made up of the heat-resisting cross-linked material of first invention.Form by biodegradable aliphatic polyester by the Biodegradable material that gross weight is not less than 95wt% and is not more than 99wt%.This Biodegradable material is crosslinked in such a way, and promptly biodegradable aliphatic polyester has gel component per-cent (gel component dry weight/initial dry weight) and is not less than 75% and be not more than 95%.

For promoting the crosslinking reaction of biodegradable aliphatic polyester, the allylic monomer that has with 1.2 to 5wt% mixes with the biodegradable aliphatic polyester of 100wt%.In addition, even owing to also can promote crosslinking reaction under the 3wt%, for promoting the crosslinking reaction under 3wt%, preferred 1.2 to 3wt%.

For biodegradable aliphatic polyester, preferred poly(lactic acid).For improving its snappiness, can be to wherein adding above-mentioned softening agent.

As with aliphatic polyester blended monomer, it is effective having allylic monomer.As having allylic monomer, can preferably use cyanacrylate (hereinafter referred to as TAIC) and front three for allyl group isocyanuric acid ester (hereinafter referred to as TMAIC).

Can carry out crosslinked when time in the biodegradable polymers of the above-mentioned monomer adding 100wt% that will be not less than 0.5wt%.But for realizing that the present invention reaches the purpose (can at high temperature guarantee to obtain to improve the effect of Biodegradable material this moment) that is not less than 75% gel component per-cent, as monomeric concentration, the 1.0wt% deficiency, but require to be not less than 1.2wt%.Yet, even increasing to, monomeric concentration is not less than 3wt%, its effect does not have too big difference yet.When monomeric add-on was not less than 5wt%, there was very little difference in effect.Consider with Biodegradable material that as bio-degradable plastics Biodegradable material need comprise guarantees the more the more sugar that decomposes.Therefore monomeric add-on being set at 1.2 to 5wt%, advantageously is 1.2 to 3wt%.

The Biodegradable material of first embodiment has fusing point and is not less than 150 ℃ and be not higher than 200 ℃, and the tensile strength 20 under near the high temperature the fusing point is to 100g/mm ²And expansion per-cent 30 to 100%.In other words, the expansion per-cent setting of Biodegradable material is very low, and set its tensile strength very high.

As mentioned above, under near the high temperature its fusing point, that the Biodegradable material setting is very low and its tensile strength setting is very high to prevent the Biodegradable material distortion.Therefore, under this high temperature, Biodegradable material has retention of configuration performance (being high rigidity) and makes its enhanced thermotolerance, and can be widely used in Industrial products and the practical goods.

Method as the Biodegradable material of making first invention, the biodegradable aliphatic polyester of allylic monomer of having of 1.2wt% to 5wt% and 100wt% is mediated, should suppress by this uniform mixture of heating under pressure with this monomeric uniform mixture by biodegradable aliphatic polyester, cool off fast then so that this uniform mixture is molded as desired shape; And, producing crosslinking reaction thus in such a manner with the uniform mixture of molding ionization radiation irradiation, promptly biodegradable aliphatic polyester is to be not less than the 75% crosslinked of its total amount.

Ionizing radiation exposure dosage is somewhat dependent upon monomeric concentration.Although take place under the amount of crosslinked even 5 to 10kGy,, can obtain the effect of cross-linking effect and improvement Biodegradable material intensity at high temperature being not less than 20kGy, more suitably being not less than under the 30kGy (can guarantee to obtain effect this moment).Preferably as originally the experience radioactive rays decay of the poly(lactic acid) of aliphatic polyester.Therefore when irradiation dose during more than necessary irradiation dose, with crosslinked opposite, the decomposition of poly(lactic acid) will speed up.Therefore, irradiation dose is set at is not more than 150kGy, more advantageously be not more than 100kGy.Irradiation dose is more advantageously set 20kGy to 50kGy.

More specifically, aliphatic polyester is heated to by thermoplastic temperature, or with its fusion and be scattered in the solvent that dissolves in chloroform, cresols or its analogue.Then, have allylic monomer to wherein adding, and these materials are mixed as far as possible mutually.Then mixture heating up is made it softening, so it is molded as desired shape.This molding therein mixture by thermoplastic state down or wherein mixture be dissolved under the state in the solvent and carry out.As another selection, remove in the cooling of this mixture or by drying desolvate after, it can be molded as desired shape by thermoplastic once more by injection moulding etc.

Then, this moulding material is used the ionization radiation irradiation to produce crosslinking reaction.

Although so that its crosslinking structure, above-mentioned chemical initiator can mix with aliphatic polyester with the generation crosslinking reaction with the ionization radiation for this moulding material.

In the present embodiment, the TAIC with 1.2 to 5wt% (cyanacrylate) adding is dissolved in the 100wt% poly(lactic acid) of solvent.Then this mixture is mediated,, then be quickly cooled to conventional temperature with about 100 ℃/minute by under pressure, heating molding (hot pressing) under 180 ℃.So obtain to have the sheet material of desired thickness.

In removing the inert atmosphere of air, this sheet material is shone under irradiation dose 20 to 100kGy, the voltage 2MeV that applies and current value 1mA with electron beam, promote polylactic acid molecule crosslinked by TAIC thus.After crosslinked the finishing, gel component per-cent is 75% to 95%.

The tensile strength of heat-resisting cross-linked material is set at 20 to 100g/mm ², and its expansion per-cent that (is higher than 160 ℃ of poly(lactic acid) fusing points) under 180 ℃ of high temperature is set at 30 to 100%.In other words, the expansion per-cent setting of heat-resisting cross-linked material is very low and tensile strength setting under its high temperature is very high, so that it has high retention of configuration performance (being high rigidity).

(embodiment 1)

As aliphatic polyester, use fine powder poly(lactic acid) (Racia H-100J, the Mitsui Kagaku of manufacturers).To add as the 1.2wt%TAIC (the Nippon Kasei Inc. of manufacturers) of allyl monomer with Lab Plast mill (it is airtight basically kneader) in 180 ℃ of poly(lactic acid) that melt down, and fully mediate until its bleach.This mixture was fully mediated 10 minutes under 20rpm.Then with this uniform mixture 180 ℃ of following hot pressing, obtain to have the sheet material of thickness 1mm thus.

In removing the atmosphere of air, this sheet material is shone under irradiation dose 20kGy to 100kGy with electron beam by rumbatron (acceleration voltage 2meV, current value 1mA).To be used as the sheet material of embodiment 1 by the cross-linked material that shines this sheet material acquisition with electron beam.

(embodiment 2 to 5)

Each sample of embodiment 2 to 5 and embodiment's 1 is similar, and different is that the concentration that adds the TAIC of poly(lactic acid) is respectively 1.5wt%, 2wt%, 3wt%, and 5wt%.

(comparative example 1 to 5)

Except irradiation dose was 0kGy to 10kGy, each sample of comparative example 1 to 5 prepared by the mode identical with embodiment 1 to 5.

(comparative example 6)

Except irradiation dose is 0 to 100kGy, the sample of comparative example 6 prepares by the mode identical with embodiment 1.

(comparative example 7,8)

Except the concentration of TAIC is respectively the 0.5wt% to 1wt, each sample of comparative example 7,8 prepares by the mode identical with comparative example 6.

Creating conditions of embodiment and comparative example provides in table 1.

[table 1]

(assessment embodiment and comparative example)

To each embodiment and comparative example assessment (1) gel component per-cent and (2) tension test at high temperature.The result provides in Fig. 1 and 2.

(the tension test assessment under the high temperature)

After sample is shaped to the rectangle of wide 1cm, long 10cm, this sample is spurred under the 2cm at interval with draw speed 10mm/min and chuck in 180 ℃ thermostatic bath, measure breaking tenacity and its fracture expansion thus.

After reaching 180 ℃, measures the sample temperature of putting into thermostatic bath.

Breaking tenacity (kg/cm ²Tensile strength/(thickness of sample * sample width) during)=fracture

Fracture expands (%)=distance during fracture between the chuck-2cm)/2cm * 100.

(assessment result of embodiment and comparative example)

Fig. 1 provides the relation between electron beam irradiation dose, gel component per-cent and the monomer concentration of each embodiment and comparative example.

As shown in Figure 1, in the sample of the comparative example 6 that does not contain TAIC, crosslinking reaction does not take place, gel component per-cent is 0.Monomer concentration is in the sample of comparative example 7 of 0.5wt% therein, although irradiation dose is big, crosslinking reaction takes place hardly, and gel component per-cent is no more than 7%.Monomer concentration is that gel component per-cent is no more than 70% in the sample of comparative example 8 of 1wt% therein.

In the sample of comparative example 1 to 5, when the irradiation dose of radioactive rays was 10kGy, gel component per-cent was 12 to 67%, although the concentration of TAIC is not less than 1.2wt%.

In embodiment 1 to 5, regardless of the concentration of TAIC, when the irradiation dose of electron beam is in 30 to 50kGy scopes, gel component per-cent maximum, and gel component per-cent surpasses 75%.In embodiment 5 and 6, gel component per-cent reaches 95%.Found when irradiation dose is 20kGy 80% to 90% of the effect that the effect of acquisition obtains for the place, peak.In embodiment 1,2 and 3, along with irradiation dose increases, gel component per-cent reduces gradually.Although not shown in the diagram, when 150kGy, gel component per-cent is 50% to 60% of place, peak gel component per-cent, and at the 200kGy place, gel component per-cent is brought down below 50%, and promptly place, peak gel component per-cent about 30%.

Fig. 2 provides the relation between the tensile strength under the high temperature and electron beam irradiation dose in embodiment and the comparative example.Fig. 3 provides the relation between electron beam irradiation dose and the fracture expansion.

In comparative example 1 to 6, in the sample without the electron beam irradiation, under 180 ℃ (surpassing 160 ℃ of its fusing points), sample melts fully, limbers up, expands and break, and do not produce tensile strength.Although show outside figure that for simplicity the fracture expansion is infinitely great, the energy measurement fracture is expanded.

When irradiation dose was 10kGy, wherein to be lower than its intensity of each sample (tensile strength) of the embodiment 6 to 8 of 1.2wt% be 0 to TAIC concentration.On the other hand, wherein the TAIC concentration tensile strength of comparative example 1 to 5 each sample that equals the sample of embodiment falls into wherein in the measurable scope of tensile strength.But at this point, as shown in Figure 3, it is big to expand.In other words, when sample is out of shape when big, produce tensile strength.In above-mentioned irradiation dose scope, the sheet material easy deformation.

Irradiation dose is not less than in the scope of 20kGy therein, and promptly in the scope of embodiment 1 to 5, expansion per-cent reduces, and produces tensile strength.Tensile strength 20 to 100g/mm ²In the scope, and expansion per-cent is 30 to 100%.

Consider the deformation performance that the present invention seeks to improve under the high temperature, the per-cent that importantly expands is little and tensile strength is big.Similar with gel component per-cent, it is big that tensile strength becomes at the 20kGy place.The peak 30 in the 50kGy scope.Tensile strength reduces when being not less than 100kGy.

In the sample of comparative example 7 and 8, different with the sample of embodiment 1 to 5, the fracture that shows among Fig. 3 not step-down that expands.So its thermotolerance deficiency of sample of comparative example 7 and 8.The sample that does not contain the comparative example 6 of TAIC melts under any dosage.Therefore, tensile strength energy measurement and in Fig. 2 and 3, not providing not.

At high temperature tensile strength and fracture expansion per-cent confirms that its retention of configuration performance of the sample of the embodiment of the invention (being high rigidity) height is not easy distortion and heat-resisting from the sample of embodiment and comparative example.

Second embodiment is described below.

The Biodegradable material of second embodiment is made by the heat-resisting cross-linked material of second invention

In the Biodegradable material of second embodiment, biodegradable aliphatic polyester and hydrophobic polysaccharide derivates are together with each other by crosslinked, improve retention of configuration performance (being high rigidity) (this performance be not less than under the temperature of glass transition point deterioration) fast thus and give the Biodegradable material thermotolerance, and further give its unbroken transparency, surface luster and slickness in temperature.

The Biodegradable material of second embodiment has the crosslinking structure that contains 50% to 95% gel component per-cent (gel component dry weight/initial dry weight).

As mentioned above, will contain biodegradable aliphatic polyester is set at as the gel component per-cent of the polymkeric substance of its main ingredient and is not less than 50%, preferred 65%.Simultaneously, biodegradable aliphatic polyester and hydrophobic polysaccharide derivates mutually combine by crosslinked, form countless three-dimensional screen structures like this in polymkeric substance.Therefore, can give this Biodegradable material thermotolerance, it is not less than under the glass transition temp indeformable in temperature.

As biodegradable aliphatic polyester, be similar to first invention, preferably use poly(lactic acid).

As passing through the hydrophobic polysaccharide derivates of crosslinked and biodegradable aliphatic polyester bonded, can use etherification starch derivative such as methyl starch, ethyl starch etc., it uses W-Gum, potato starch, sweet potato starch, wheat starch, W-Gum, tapioca (flour), sago starch as its material; Esterified starch derivative such as acetic ester starch, aliphatic ester starch etc.; With the alkylation starch derivative.

As hydrophobic polysaccharide derivates, can use the derivative that is similar to starch, its material is Mierocrystalline cellulose and other polysaccharide derivates such as Pullulan (amylopectin) (amylopectin).

Hydrophobic polysaccharide derivates can use separately or by mix use mutually with its two or more.Consider that the present invention with hydrophobic polysaccharide derivates and the mutual blended purpose of aliphatic polyester, can preferably use and bring enough hydrophobic derivative, wherein hydroxyl is not less than 1.5, advantageously is not less than 1.8, more advantageously is not less than 2.0 and replaces with substituting group.

Substitution value is meant the mean value that constitutes unitary three hydroxyl values that is included in polysaccharide by replacements such as esterifications.Therefore the maximum value of substitution value is 3.The derivative of polysaccharide is by coming modification by replacing to wherein introducing functional group.Polysaccharide derivates shows wetting ability when its substitution value is not more than 1.5, show hydrophobicity when its substitution value is not less than 1.5.

Be to improve the snappiness of Biodegradable material, similar with first invention, softening agent can be added in the biodegradable resin as at normal temperatures glycerol liquids or softening agent is added wherein as at normal temperatures polyoxyethylene glycol and polyvinyl alcohol solid.In addition, a small amount of other biodegradable aliphatic polyester such as polycaprolactam can be added in the poly(lactic acid) as softening agent.But this not necessarily.

Similar with first invention, preferably will have allylic monomer and add in aliphatic polyester and the hydrophobic sugar.This monomer can crosslinked independently aliphatic polyester and hydrophobicity sugar.Similar with first invention, have the bright base of alkene suitable especially when monomer be that cyanacrylate (hereinafter referred to as TAIC) and front three are for allyl group isocyanuric acid ester (hereinafter referred to as TMAIC).

When the monomer that will be not less than 0.1wt% adds in the 100wt% aliphatic polyester, can recognize the effect of adding.When monomeric concentration is 0.5 to 3wt%, can obtain better effect.Consider and use to use Biodegradable material that suitable is sets the biodegradable aliphatic polyester that decomposes reliably and the total amount of hydrophobic polysaccharide derivates is not less than 99% as bio-degradable plastics.Therefore monomeric add-on is 0.5 to 1wt%.

The Biodegradable material of being made up of the heat-resisting cross-linked material of second embodiment of the present invention is by biodegradable aliphatic polyester, hydrophobic polysaccharide derivates and cross-linking type polyfunctional monomer are mixed under the temperature that is not less than biodegradable aliphatic polyester fusing point mutually, then with its mixture ionization radiation irradiation.

More specifically, with aliphatic polyester and hydrophobic polysaccharide derivates initial heating temperature to its mixture melt, or by thermoplastic or dissolving be scattered in the solvent that dissolves in chloroform, cresols or its analogue.Then, then this monomer is added in the mixture, and with the mutual as far as possible uniform mixing of these three kinds of components.These three kinds of components can be mixed mutually or, for example aliphatic polyester and hydrophobic polysaccharide derivates can be mediated in advance, so that hydrophobic polysaccharide derivates thorough mixing is scattered in the aliphatic polyester two kinds of mixing in three kinds of components.

With extruding of this mixture and cooling fast, thus this mixture is molded as desired shape then, wherein this mixture is by thermoplastic or be dissolved in the solvent.In addition, this mixture heated once more make its softening, extruding, cooling fast then, remove in the mixture cooling or by drying thus desolvate after this mixture be molded as desired shape.With this moulding material ionization radiation irradiation, produce crosslinking reaction thus.

The ionizing rays and first invention with its irradiation moulding material are similar, for example, can use gamma-radiation, x-ray, beta-rays or α-ray.In industrial production, preferably from the gamma-radiation of cobalt 60 emissions with from rumbatron ejected electron bundle.Produce crosslinking reaction when irradiation dose is not less than 1kGy and is not higher than 300kGy, advantageously be not less than 30kGy and be not higher than 100kGy, the most advantageously be not less than 30kGy and be not higher than 50kGy,

Similar with first invention, except that using radioactive rays, above-mentioned chemical initiator can be used to produce crosslinking reaction.

In manufacture method of the present invention, when using monomer when having allylic TAIC, biodegradable aliphatic polyester and hydrophobic polysaccharide derivates are by whole mutually crosslinked with ionization radiation irradiation moulding material.Improve aliphatic polyester thus and be not less than the bad shortcoming of 60 ℃ of following aliphatic polyester retention of configuration performances (being high rigidity) in temperature.

In other words, be what describe below as the pass between the biodegradable aliphatic polyester of Biodegradable material major constituent, hydrophobic polysaccharide derivates, the cross-linking type polyfunctional monomer.

When the uniform mixture of above-mentioned three kinds of components shines with the ionization emission, because the cross-linking type polyfunctional monomer is by radioactivation, between the molecule as the biodegradable aliphatic polyester of Biodegradable material major constituent, forming crosslinking structure between the hydrophobic polysaccharide derivates molecule mediated and between the molecule of biodegradable aliphatic polyester molecule and hydrophobic polysaccharide derivates.Form countless three-dimensional net structures thus.

Thereby soften the as a whole hydrophobic polysaccharide derivates of its one-tenth of jade-like stone near being chosen in biodegradable aliphatic polyester fusing point, hydrophobic polysaccharide derivates and biodegradable aliphatic polyester can be kneaded together by heating.Hydrophobic polysaccharide derivates does not have clear and definite fusing point and at high temperature stone.For biodegradable aliphatic polyester as be not less than 60 ℃ of glass transition temps (its far below near the fusing point 160 ℃) deliquescing and lose the poly(lactic acid) of its configuration retention property (being high rigidity) down in temperature, this hydrophobic polysaccharide derivates is given whole uniform mixture hardness because it have the softening temperature that is not less than 160 ℃ and for hard and temperature be lower than 160 ℃ indeformable down.

In other words, in the present invention, hydrophobic polysaccharide derivates is mediated with biodegradable aliphatic polyester.Further, with hydrophobic polysaccharide derivates and biodegradable aliphatic polyester by by radioactivation and capture cross-linking type polyfunctional monomer in the network structure and mutually combine and be one.Therefore, can effectively provide to contain to have the block polymer of stable on heating biodegradable aliphatic polyester as its major constituent, this thermotolerance makes to be not less than under the glass transition temp in temperature and keeps the hard shape and the polymkeric substance of polymkeric substance to be not easy sex change.

It is similar with the method that strengthens poly(lactic acid) with disclosed mineral filler in the above-mentioned non-patent literature at high temperature to mix the method for hard hydrophobic polysaccharide derivates and biodegradable aliphatic polyester.But hydrophobic polysaccharide derivates is good aspect following:

(1) can not be with its size dispersion mineral filler greater than original size.On the other hand, hydrophobic polysaccharide derivates is when by heating or be dissolved in the solvent when mixing with aliphatic polyester and melt.Therefore, by selecting combined amount as required, then hydrophobic polysaccharide derivates can aequum mixes with aliphatic polyester under particle size before hydrophobic polysaccharide derivates aliphatic polyester mixes and the molecular dimension

(2) between mineral filler and the matrix formed by resin, do not have bonding, and reinforced effects depends primarily on the intensity of filler itself.On the other hand, crosslinked by using identical monomer to occur between the aliphatic polyester of hydrophobic polysaccharide derivates and formation Biodegradable material matrix.Therefore, owing to comprise hydrophobic polysaccharide derivates hardness, provide matrix that improved hardness and hydrophobic polysaccharide derivates and resin constitute by the crosslinked three kinds of effects that are combined as a whole by crosslinked, hydrophobic polysaccharide derivates can offer matrix that resin constitutes acquires reinforced effects during as filler above hydrophobic polysaccharide derivates thermotolerance.

(3) when filler during with the mixed with resin that constitutes the Biodegradable material matrix and this mixture molding, the phenomenon of oozing out that filler oozes out resin appears as time passes.On the other hand, based on the same reasons of describing in top (2), when mixing, not crosslinked so its molecule of hydrophobic polysaccharide derivates is disperseed.Hydrophobic like this polysaccharide derivates can mix with aliphatic polyester easily.But behind radiation exposure, hydrophobic polysaccharide derivates molecule is cross-linked with each other and is crosslinked with aliphatic polyester integral body.As a result, hydrophobic polysaccharide derivates becomes polymkeric substance.Therefore this hydrophobic polysaccharide derivates never oozes out.

(4) mineral filler mixes with aliphatic polyester such as poly(lactic acid) and causes poly(lactic acid) to lose its transparency and its surface luster, so surface feel is coarse.On the other hand, in the present invention, because mixing condition, Biodegradable material is only slightly lost its transparency, so the appearance of Biodegradable material is not destroyed.

(5) for the workability of Biodegradable material, shortening in stage high temperature hold-time that wherein degree of crystallinity improves, using the method for nano-scale mineral filler to succeed.Do not need the high temperature hold-time among the present invention.Therefore the present invention can reduce during the manufacturing time greatly.

Retention of configuration performance (being high rigidity), particularly poly(lactic acid) that the Biodegradable material of being made up of heat-resisting cross-linked material can improve biodegradable aliphatic polyester is not less than retention of configuration performance (being high rigidity) under 60 ℃ in temperature.Further, because for keeping Biodegradable material intensity at high temperature that hydrophobic polysaccharide derivates is added in the poly(lactic acid), therefore, to be used for poly(lactic acid) different with mineral filler wherein, and the transparency of poly(lactic acid) and its surface luster can not be subjected to very big infringement.In addition, although must must set high temperature in industrial production, this Biodegradable material can pass through to use conventional injection moulding apparatus manufacturing, and can not reduce productivity.

In addition, because hydrophobic polysaccharide derivates also is biodegradable, therefore in fact the ecosystem is almost had no adverse effect.Therefore, expect that this Biodegradable material can be used as the equivalent material of plastic prod of scale operation and discardable.In addition, owing to Biodegradable material has no adverse effects to organism, so it is specially adapted to the inside and outside middle medicine equipment that uses of organism.

In the present embodiment,, use poly(lactic acid) and acetic ester starch is used as hydrophobic polysaccharide derivates so that poly(lactic acid) and acetic ester starch become one mutually as biodegradable aliphatic polyester.In addition, as the cross-linking type polyfunctional monomer, use TAIC.For the 100wt% poly(lactic acid), use 0.5wt% to 3wt%TAIC.

Above-mentioned three kinds of materials are mixed mutually.This mixture injection moulding is formed sheet material.With the ionization radiation irradiation of this sheet material with 30 to 100kGy amounts.Crosslinked by using TAIC to promote, make poly(lactic acid) and acetic ester starch be one thus by crosslinked mutually combining.

The Biodegradable material of being made up of the heat-resisting cross-linked material of gained that obtains has 150 ℃ to 200 ℃ of gel component per-cent 50 to 95%, essence temperature of fusion, and this temperature is not less than the fusing point of biodegradable aliphatic polyester and is not less than the softening temperature of hydrophobic polysaccharide derivates, the tensile strength 30 under near the high temperature 150 ℃ to 200 ℃ to 70g/mm ², expansion per-cent 20 to 50%.In other words, in having the pyritous environment, setting Biodegradable material expansion per-cent is low, tensile strength is high and configuration keeps performance height (being high rigidity).

The embodiment (6 to 11) and the comparative example (9 to 18) of second embodiment of preparation.

(embodiment 6)

As aliphatic polyester, use fine powder poly(lactic acid) (Racia H-100J, the Mitsui Kagaku of manufacturers).As hydrophobic polysaccharide derivates, use acetic ester starch powder (CP-1, the Nippon Corn of manufacturers starch Inc.).

In this polysaccharide derivates, the substitution value of hydroxyl is about 2.0.This polysaccharide derivates water fast, but be dissolved in the acetone.Therefore, this polysaccharide derivates is hydrophobic.This polysaccharide derivates is being not less than under 180 ℃ the temperature softeningly, and does not have clear and definite softening temperature and has high Young's modulus.

5wt% acetic ester starch is mixed with the 100wt% poly(lactic acid).This mixture is melted down at 190 ℃ with Lab Plast mill (a kind of sealing kneader), and fully mediate until its bleach.Then with 3wt%TAIC manufacturers: Nippon Kasei Inc.) (it is for having allylic monomer) adds in the mixture of poly(lactic acid) and acetic ester starch.This component is fully mediated under 20rpm and mixing mutually.

Then with this uniform mixture 190 ℃ of following hot pressing, be quickly cooled to normal temperature with about 100 ℃/min subsequently.Obtain to have the sheet material of thickness 1mm thus.In removing the inert atmosphere of air, this sheet material is shone under dosage 50kGy with electron beam by using rumbatron (acceleration voltage 2meV, current value 1mA).The cross-linked material that obtains is used as the sample of embodiment 6.

(embodiment 7 and 8)

Prepare each sample of embodiment 7 and 8 by mode similar to Example 6, different is is set at 10wt% with the ratio of hydrophobic polysaccharide derivates and aliphatic polyester in embodiment 7, be set at 30wt% in embodiment 8.

(embodiment 9)

The sample for preparing embodiment 9 by mode similar to Example 6, different is as hydrophobic polysaccharide derivates, use has the cellulose diacetate (rhodia L-30, the Dicel Inc. of manufacturers) of substitution value about 2 and the ratio of hydrophobic polysaccharide derivates and aliphatic polyester is set at 10wt%.

(embodiment 10)

In embodiment 10,, use the secondary cellulose acetate with substitution value about 2 identical with the sample of embodiment 9 as hydrophobic polysaccharide derivates.The ratio of hydrophobic polysaccharide derivates and aliphatic polyester is 30wt%.In addition, prepare sample by the mode identical with embodiment 6.

(embodiment 11)

Succinic acid-butanediol ester (Bionore#1020, manufacturer Showa Kobunshi Inc.) is used as aliphatic polyester.Aliphatic ester starch (CP-5, manufacturer Nippon Corn starch Inc) is used as hydrophobic polysaccharide derivates.This aliphatic ester starch has substitution value 2 and hydrocarbon mean length about 10.

By mode similar to Example 6, be 3 with the weight ratio of TAIC and aliphatic polyester and hydrophobic polysaccharide derivates total amount.In addition, preparation sample.

Aliphatic polyester and hydrophobic polysaccharide derivates are mediated down and this mixture is pushed down at 150 ℃ 150 ℃ (being softening temperature).In this way, obtain sheet material.

(comparative example 9 to 14)

Except without the electron beam irradiation, with each sample of comparative example 9 to 14 by preparing with embodiment 6 to 11 similar modes.

(comparative example 15)

Prepare the sample of comparative example 15 by mode similar to Example 6, different is not use hydrophobic polysaccharide derivates and monomer, only with poly(lactic acid) as specimen material.

(comparative example 16)

Hydrophobic polysaccharide derivates is not used in the sample of comparative example 16.

(comparative example 17)

The sample of comparative example 17 prepares by mode similar to Example 8, but replaces TAIC with 3wt%TMPT.

(comparative example 18)

Prepare the sample of comparative example 18 by the mode identical, but do not use the cross-linking type polyfunctional monomer with embodiment 11.

Difference between embodiment 6 to 11 and the comparative example 9 to 18 is provided in table 2.

In the table 2, label o represents not change shape before and after the specimen test.Label △ represents that shape changes to a certain extent, and for example its is crooked or similar variation takes place.Label x represents that sample falls fully and can not keep its original-shape.

For being evaluated at those effects that temperature is not less than improvement heat-resisting effect and the comparative example 9 to 18 of embodiment 6 to 11 under the glass transition temp, assess the retention of configuration performance (be high rigidity) of each sample under 80 ℃ and 150 ℃.

To assessing with the embodiment of the electron beam irradiation with irradiation dose 0kGy and 50kGy and the sample of comparative example, table 2 provides the result.

Be the crosslinking degree of assessment, measure the irradiation dose that imposes on embodiment in each embodiment and the comparative example and the relation between the gel component per-cent with the molecule of electron beam irradiation.Fig. 4 provides the result.

Be not less than the effect of improving Young's modulus under the glass transition temp for detecting in temperature, it applies intensity expansion curve in the sample measurement tension test of the embodiment 6 to 8 of 50kGy dosage electron beam and comparative example 15 subtend.Fig. 5 provides the result.

Appraisal procedure is described below.

(configuration retention property assessment (being high rigidity))

With each embodiment of the rectangular shape with length 10cm and width 1cm that cuts out and sample sheets almost vertical establishing in the groove with width 1mm (equaling the thickness of sheet material) and degree of depth 1cm of comparative example, wherein the longer sides of sheet material is vertical.Sheet material and groove are put into the thermostatic bath with 80 ℃ of temperature, detect this sheet material and whether establish.Be evaluated under 80 ℃ and 150 ℃ and carry out.

Gel component per-cent assessment at high temperature and tension test assessment are by as above carrying out.

(assessment result of embodiment and comparative example)

At the configuration retention property (being high rigidity) of the glass transition temp of poly(lactic acid) (be higher than 60 ℃) under 80 ℃ shown in the table 2, almost there is not any variation before all samples heating beginning of embodiment 6 to 11 and comparative example 16 to 18, after the heating beginning, very little variation is arranged, and fusing of the sample of comparative example 9 to 15 and whereabouts, and do not maintain the original shape.Under near the fusing point 150 ℃, the bending of the sheet material of embodiment 6 and its shape change, and the sheet material of embodiment 7 to 11 shows preferred configuration retention property (being high rigidity).

For gel fraction per-cent, as shown in Figure 4, the sample of crosslinked embodiment 6 to 11 is undertaken by irradiating electron beam, and the result who obtains is, aliphatic polyester, hydrophobic polysaccharide derivates and cross-linking type polyfunctional monomer mix and mutually combine and be one.Peak value reaches 68 to 95%.In embodiment 6 to 8, when irradiation dose was about 50kGy, gel component per-cent reached peak value.In embodiment 9 to 11, when irradiation dose was 100kGy, gel component per-cent reached peak value.When irradiation dose surpassed 100kGy, the sample that contains the poly(lactic acid) of being decomposed by radioactivity began to decompose, and gel component per-cent reduces.

The sample of comparative example 16 that will contain poly(lactic acid) and TAIC is crosslinked according to being similar to embodiment.In the sample of comparative example 9, because of the heat that produces in the perparation of specimen takes place crosslinked in TMPT.Therefore, when sample shone with electron beam, this sample was lost crosslinked function and is decomposed by irradiation.

For tensile strength and expansion, as shown in Figure 5, under 100 ℃ of measuring conditions, the sample of the comparative example of being made up of poly(lactic acid) 15 has very little tensile strength and expands greatly when pulling.The sample that contains poly(lactic acid) and TAIC and crosslinked comparative example 16 shows tensile strength to a certain degree, but tensile strength is not obvious.

On the other hand, in embodiment 6 to 8, tensile strength is 30 to 70g/mm ²And expansion per-cent is 20 to 50%.Along with hydrophobic polysaccharide derivates adding quantitative change is big, tensile strength raises continuously, and degrees of expansion reduces.In other words, confirm that Young's modulus increases and retention of configuration performance (being high rigidity) raises.

By the assessment of embodiment and comparative example sheet material, its Young's modulus of poly(lactic acid) descends fast under 60 ℃ and becomes very soft being not less than.Therefore, poly(lactic acid) is difficult to keep its original-shape.Can confirm, although because of increasing retention of configuration performance (being high rigidity) deficiency to wherein adding the crosslinked retention of configuration performance (being high rigidity) that makes that monomer such as TAIC cause.

With acetic ester starch and typel element (it is hydrophobic polysaccharide derivates) by TAIC crosslinked and be not less than under the poly(lactic acid) glass transition temp crosslinked and be not less than the very high Young's modulus of demonstration under the poly(lactic acid) glass transition temp.Can confirm that near the poly(lactic acid) fusing point, it is few that acetic ester starch and typel element do not show that clearly fusing point and its Young's modulus reduce.

The 3rd embodiment will be described below.

The Biodegradable material of the 3rd embodiment is the heat-stable material as the 3rd invention of the heat shrinkable material with high heat shrinkability characteristic.The Biodegradable material of the 3rd embodiment is by biodegradable aliphatic polyester and have allylic lower concentration monomer and form.With this mixture ionization radiation irradiation, or chemical initiator added make this mixture have crosslinked result in the mixture, then with this mixture by adding thermal expansion.When this mixture is being not less than when heating under the temperature of using when expanding, this mixture is being not less than 40% and be not higher than in 80% the scope and shrink.

More specifically, as biodegradable aliphatic polyester, use poly(lactic acid).Gel component per-cent (gel component dry weight/initial dry weight) by crosslinked acquisition is 10 to 90%.The contraction factor that is no more than under 140 ℃ in temperature is not less than 10%.The contraction factor that is not less than under 160 ℃ in temperature is 40 to 80%.

As aliphatic polyester, use the above-mentioned poly(lactic acid) that is similar to first and second embodiments as biodegradable polymers.For improving the snappiness of biodegradable aliphatic polyester, can add therein and be similar to first and second softening agent in the embodiment.

As with aliphatic polyester blended cross-linking type polyfunctional monomer, use to be similar to the allylic monomer of having of first and second embodiments.

When having allylic monomeric concentration ratio when being 0.5wt% for the 100wt% poly(lactic acid), crosslinking reaction is difficult to carry out.Therefore for gel component per-cent is set at 10 to 90%, obtain the purpose of high heat resistance and high shrinkage character to realize the present invention, as monomer concentration 0.5wt% deficiency.Preferably monomer concentration is set at 0.7wt% to 3wt%.

Even monomer concentration risen to be not less than 3wt%, still there are not different especially on the effect.When monomer add-on during up to about 5wt%, gel component per-cent rises at once and is not less than 80%, and is not easy control.

For improving contraction factor, gel component per-cent is preferably 50 to 70%.In a word, the monomer add-on advantageously is 0.7 to 2wt%, the most advantageously is 0.8 to 0.9wt%.

Degree of crosslinking can be based on above-mentioned gel component per-cent assessment.

Although with this mixture with the ionization radiation irradiation so that it has crosslinking structure, the chemical initiator that is similar to first and second embodiments can be mixed with aliphatic polyester, produce crosslinking reaction thus.

When using ionizing rays, similar with first and second embodiments, as being used for crosslinked ionizing rays, can use gamma-radiation, x-ray, beta-rays or α-ray.In the industrial production, preferably from the gamma-radiation of cobalt 60 emissions with from rumbatron ejected electron bundle.The dosage of ionizing rays is somewhat dependent upon monomer concentration.Crosslinkedly under average about 1 to 150kGy, carry out.But cross-linking effect and the effect of improving Biodegradable material intensity under the high temperature can be not less than 5kGy, more preferably obtain being not less than under the 10kGy, can guarantee to obtain these effects this moment.

Preferably will be by the radioactive rays disintegration as the poly(lactic acid) of aliphatic polyester itself.Therefore when irradiation agent during,, will aggravate the poly(lactic acid) decomposition with crosslinked opposite greater than necessary irradiation dose.Therefore, being limited to 80kGy on the irradiation dose, advantageously is 50kGy.

Therefore, the irradiation dose of electron beam is set at and is not less than 5kGy and is not higher than 50kGy, advantageously is not less than 10kGy and is not higher than 50kGy, advantageously is not less than 15kGy and is not higher than 30kGy.

Poly(lactic acid) is the type by the radioactive rays decay.Although but its part decomposition, apparent gel component per-cent does not reduce when poly(lactic acid) partly connects by cross-linked network.Consider that the present invention stores the Biodegradable material shape but not store the purpose that has the part that is connected with network portion and have the structure of a lot of gel section that are not suitable for the storage shape, be preferably as follows this structure, wherein the corsslinking molecular of poly(lactic acid) connects to form strong reticulated structure and to have much free-moving non-crosslinked part can be in heating the time at a lot of points mutually, thereby this structure has high convergent force and very big deflection, and therefore has high contraction factor.Therefore, in the present invention, this structure has the ideal state at once when monomer crosslinked reaction is finished.

More specifically, X-coordinate is that irradiation dose and ordinate zou are among the figure shown in Fig. 1 (Fig. 4) of gel component per-cent therein, and along with irradiation dose becomes big, gel component per-cent increases gradually, saturated and no longer increase.Can be before gel component per-cent have just remained unchanged, promptly near the point the flex point of figure obtains perfect condition at once.

The perfect condition of gel component per-cent is according to monomer concentration and difference.Under high density, gel component per-cent is saturated under high gel component per-cent.Under lower concentration, gel component per-cent is saturated under low gel component per-cent.

According to the inventor's research, as mentioned above, ideal gel component per-cent is 50 to 70%.As mentioned above, when monomer concentration is 0.7 to 1.3wt%, obtain perfect condition, i.e. flex point among the figure.

When after crosslinking reaction is finished, proceeding ionization radiation irradiation, the molecular breakdown of poly(lactic acid).Although think crosslinked based on the generation of gel component per-cent, when gel component per-cent uprised, crosslinked network broke at a lot of points.Crosslinked like this molecule is helpless to shape and stores.Therefore, excessive descent after causing by the peak because of the irradiation dose increase has been that 50 to 70% gel component per-cent becomes once more at 50 to 70% o'clock, and gel component per-cent is inappropriate.

As mentioned above, be 10 to 90% by setting gel component per-cent, preferred 50 to 70%, in polymkeric substance, produce countless three-dimensional networks.Thus, to the thermotolerance that polymkeric substance provides, polymkeric substance is not less than under the glass transition temp indeformable in temperature like this.

As mentioned above, heating is expanded it under its fusing point owing to when expanding poly(lactic acid) is not less than in temperature, the crystallising part of poly(lactic acid) with and therefore crystallising part fusing and poly(lactic acid) do not expand.When mixture cools off under swelling state, the not crystallising part of poly(lactic acid) with and crystallising part hardening and keep swelling state.The film that this three-dimensional structure is made by monomer is stored dilatational strain.When mixture heats once more, the fusing of the not crystallising part of poly(lactic acid), but keep expanding by its crystallising part.When crystallising part melts at the fusing point place, the strain relief of in three-dimensional net structure, storing, poly(lactic acid) is shunk simultaneously, and gets back to its original-shape.

For example, when expansion temperature being set at 160 to 180 ℃, the biodegradable heat shrinkable material that contains poly(lactic acid) is being not less than 160 ℃ of contractions down.Because strong three-dimensional net structure, contraction factor can rise to 40 to 80% greatly.

In the method for making the 3rd invention of heat-shrinkable Biodegradable material, the cross-linking type polyfunctional monomer is added Biodegradable material with suitable lower concentration, and cross-linking type polyfunctional monomer and Biodegradable material are mediated; By depressing this mixture of heating this mixture be molded as predetermined shape and this mixture is cooled off fast adding; With this mixture with ionization radiation irradiation to produce crosslinking reaction, gel component per-cent is set at and is not less than 10% and be not higher than 90% like this; Behind the mixture that mixture is formed with the ionization radiation irradiation as heat shrinkable material, mixture is not less than the Biodegradable material temperature of fusion in temperature but is not higher than that heating makes mixture expansion under the temperature that temperature of fusion adds 20 ℃ of sums.

According to this manufacture method, when this uniform mixture is not less than when heating under the temperature of using when expanding in temperature, form uniform mixture as heat shrinkable material, this heat shrinkable material is being not less than 40% and be not higher than 80% time contraction.

Have in the method for biodegradable heat shrinkable material of the thermal contraction factor 40 to 80% in manufacturing, to have allylic monomer and add biodegradable aliphatic polyester, and will have allylic monomer and biodegradable aliphatic polyester and mediate and this mixture is molded as predetermined shape with lower concentration;

This mixture is produced crosslinking reaction with the ionization radiation thus being not less than 1kGy and not being higher than under the 150kGy irradiation, and gel component per-cent is set at and is not less than 10% and be not higher than 90% like this; With this mixture with ionization radiation irradiation after, this mixture 60 ℃ of temperature under 200 ℃, add thermosetting as the mixture of heat shrinkable material in this mixture expansion.

When heating under the temperature that heat shrinkable material is used when temperature is not less than expansion, this heat shrinkable material is shunk for 40% to 80% time at contraction factor.

When poly(lactic acid) when the biodegradable aliphatic polyester, will be not less than 0.7 and be not higher than the allylic monomer of having of 3.0wt% and add in the 100wt% poly(lactic acid), and with poly(lactic acid) with have allylic monomer and mediate together;

This mixture is molded as very thin film, thick sheet or pipe, then should very thin film, thick sheet or effective ionizing rays be not less than 5kGy and be not higher than that irradiation produces crosslinking reaction thus under the 50kGy, its gel component per-cent is set at and is not less than 50% and be not higher than 70% like this; With

After obtaining crosslinking structure, with very thin film, thick sheet or pipe be not less than 150 ℃ and be not higher than 180 ℃ down heating so that very thin film, thick sheet or pipe under 2 to 5 times of expansion multiples, expand.

More advantageously, use has allylic cyanacrylate as monomer, the cyanacrylate of add-on set to(for) the 100wt% poly(lactic acid) is not less than 0.7wt% and is not higher than 2.0wt%, be not less than 10kGy and be not higher than under the 30kGy this mixture of irradiation with electron beam, and when expanding, be not less than 160 ℃ and be not higher than 180 ℃ of these mixtures of heating down.

Gel component per-cent is set at 10 to 90% when crosslinking reaction is finished, preferred 50 to 70% reason is, according to as mentioned above, in this scope, can improve crosslinked, strengthen thermotolerance and improve heat shrinkability characteristic.By setting gel component per-cent is about 60% o'clock, can obtain 40 to 80% heat shrinkability characteristic by be not less than 160 ℃ of these mixtures of heating in temperature.

When the evaluates dilation characteristic, with gel component per-cent 50 to 70% be labeled as ◎, gel component per-cent 10 to 50% and 70 to 90% is labeled as zero, gel component per-cent 6 is labeled as △ to 10%, and gel component per-cent 0 to 5% and 90 to 96% is labeled as *.

Because shape is stored by the network of crosslinked acquisition, then degree of crosslinking is lower than 50%.When degree of crosslinking is set at when being lower than 10%, forfeiture shrinkage character and thermotolerance.On the other hand,,, crosslinkedly excessively carry out, and therefore shape becomes firmly and is difficult to distortion more specifically greater than 90% o'clock when degree of crosslinking is set at greater than 70%.The result damages expansion characteristics and shrinkage character.So be sure of: the scope that wherein can give thermotolerance and heat shrinkability characteristic is 10 to 90%, and in 50 to 70% scopes, polymkeric substance has good thermotolerance and heat shrinkability characteristic.

Fig. 6 display network structure, expansion and according to the relation between the percent thermal shrinkage of the gel component per-cent before expanding.In Fig. 6, stain is represented crystallising part A, and the part beyond the stain is represented not crystallising part B, and oblique line is represented network C.When the sheet material 10 of the crosslinking structure shown in Fig. 6 (A) with gel component per-cent 50 to 70% by when under 180 ℃, adding thermal expansion for 160 ℃, shown in Fig. 6 B, the obliquity of network C changes and also has swelling state.When the expansion sheet material is not less than 60 ℃ (they are the glass transition temp of poly(lactic acid)) when heating down in temperature, shown in Fig. 6 (C), crystallising part B fusing.When the expansion sheet material is not less than 160 ℃ (for the temperature of fusion of poly(lactic acid)) down during heating in temperature, crystallising part A fusing.But the mutually complete bonding of the molecule of network C, and network C does not melt.Because the configuration component property height of network C, so the expansible network C is got back to its original shape (shown in Fig. 6 (D)) and contraction.

Fig. 7 shows made by poly(lactic acid) and not crosslinked sheet material.After sheet material shown in Fig. 7 (A) expands under 70 ℃ to 80 ℃ heating condition (shown in Fig. 7 (B)), crystallising part B does not melt near the poly(lactic acid) glass transition temp and its warpage (shown in Fig. 7 (C)).Shown in Fig. 7 (D), when sheet material heats under temperature is not less than fusing point, crystallising part A fusing.

Crosslinked when finishing after heating condition be set at 60 ℃ to 200 ℃, advantageously be not less than 150 ℃ and be not higher than 180 ℃, the most advantageously be not less than 160 ℃ and be not higher than 180 ℃ reason owing to such fact: cross-linking polylactic acid crystallising part does not begin to transform the time temperature (glass transition temp) be lower than 60 ℃ slightly, and the fusing point during crystal melting is 150 to 160 ℃.

When sheet material expands in the scope of (60 to 150 ℃) from glass transition temp to fusing point, its not crystallising part under glass transition temp, melt and be out of shape.Therefore this sheet material is 60 ℃ of beginning thermal contractions.But its crystallising part does not shrink, so the thermal contraction factor does not increase.Therefore for increasing the thermal contraction factor, sheet material is being not less than 150 ℃ of expansions down (its crystallising part fusing this moment), sheet material shrinks down at 150 to 160 ℃ then.So, the thermal contraction factor can increase to 40 to 80%.

Heating temperature during therefore, with expansion advantageously is set at and is not less than 150 ℃.If be set at 200 ℃ the heat-up time when expanding, sheet material is expanded at short notice.Therefore, the Heating temperature when expanding is set at and is not higher than 180 ℃, the most advantageously is not less than 160 ℃ and neither be higher than 180 ℃ and also be not less than fusing point.

When this mixture expands, expansion multiple is set at 2 to 5 under above-mentioned heating condition.This is equivalent to such fact: the thermal contraction factor that will comprise the biodegradable heat shrinkable material of poly(lactic acid) is set at 40 to 80%.

The thermal contraction factor is no more than 5% when temperature is no more than 140 ℃, and tube swelling per-cent not.In the time of 150 ℃, contraction factor is about 40%.But when sheet material is heated to when being not less than 160 ℃, contraction factor is 65 to 70%.Therefore, expansion multiple is set at and is not less than 2 and be not higher than 3, advantageously is no more than 2.5.

This sheet material expands by one of the expansion of use single shaft, twin shaft expansion and multiaxis expansion, and can pass through roller method, Denter method or Cheng Guanfa expansion.

As mentioned above, in the Biodegradable material of the 3rd embodiment, when the mixture of said components is used the ionization radiation irradiation, has allylic monomer owing to mix, promote that biodegradable aliphatic polyester such as poly(lactic acid) are crosslinked, and therefore gel component per-cent can be set at 10 to 90%.Therefore inflatable to its original length about 5 times of the length of mixture.In addition, when the expansible heat shrinkable material is heated to when being not less than fusing point, because network is stored shape, it can be in 40 to 80% times thermal contractions of contraction factor.Simultaneously, prevent change of shape by infusible crystallising part and network under the glass/glass point of inversion of poly(lactic acid) glass transition temp.Biodegradable material is heat-resisting like this.

In the present embodiment, TAIC (cyanacrylate) is added poly(lactic acid) with lower concentration.Add in the poly(lactic acid) of 100wt% 0.7 to 0.9wt%TAIC.

After TAIC adds in the dissolved poly(lactic acid), with its kneading.By this mixture is depressed 180 ℃ of down heating adding, then be quickly cooled to normal temperature with this mixture molding (hot pressing) with about 100 ℃/min then, acquisition has the sheet material of desired thickness thus.。

In removing the inert atmosphere of air, with this sheet material with electron beam in irradiation dose 10 to 30kGy, apply under voltage 2MeV and the current value 1mA and shine, carry out the crosslinked of polylactic acid molecule by TAIC thus.When finishing when crosslinked, gel component per-cent is 50% to 70%.

Will be with the sheet material of electron beam irradiation 160 to 180 ℃ of heating down, so that being no more than 5 times at expansion multiple, this sheet material expands by single shaft expansible mode.This sheet material obtains biodegradable heat shrinkable material thus with sheet cools to room temperature after expanding.

The invention is not restricted to above-mentioned embodiment.Type by changing Biodegradable material and have allylic monomeric type, can change the irradiation dose of electron beam, because of electron beam shines the crosslinked gel component per-cent that obtains that causes, Heating temperature and the expansion within the scope of the present invention when expanding amplified.At this moment, the Heating temperature when expanding is set at and is not less than the fusing point that is used for the Biodegradable material material and near fusing point.The mixture of each component is expanded under this heating condition.In this way, preparation heat shrinkable material.Be not less than when heating under the said temperature when heat shrinkable material like this, its contraction factor can rise to about 80%.

(embodiment and comparative example)

Press the embodiment of the 3rd embodiment of preparation shown in the table 3 and 42 kinds of samples of comparative example.

For aliphatic polyester, use fine powder poly(lactic acid) (Racia H-100J, the Mitsui Kagaku of manufacturers).TAIC (the Nippon Kasei Inc. of manufacturers) (it is for having allylic monomer) is added in the poly(lactic acid) with 0wt%, 0.5wt%, 1.0wt%, 2.0wt% and 3.0wt%, this poly(lactic acid) is melted down and fully mediates to its bleach at 180 ℃ with Lab Plast mill (it is a kind of kneader of sealing).This mixture was fully mediated 10 minutes under 20rpm.

Then with this uniform mixture 180 ℃ of following hot pressing, obtain to have the sheet material of thickness 1mm thus.In removing the inert atmosphere of air, with this sheet material by using rumbatron (acceleration voltage: 2MeV and current value: 1mA) shine with electron beam.Irradiation dose is set at 0kGy, 10kGy, 20kGy, 30kGy, 50kGy, 80kGy and 120kGy, and is as shown in table 3.

Then will with the sheet material of electron beam irradiation 180 ℃ down heating make this sheet material be expanded to 2.5 times at the most of its original length.This sheet material cools the temperature to room temperature after expanding, and wherein sheet material is fixed with this state.Prepare the thermal contraction sample in this way.

[table 3]

Irradiation dose	The concentration 0% of TAIC	0.5％	1.0％	1.5％	2.0％	3.0％
							0kGy	× 0％	× 0％	× 0％	× 0％	× 0％	× 0％
10kGy	× 0％	× 0％	○ 12％	◎ 50％	◎ 58％	◎ 66％
							20kGy	× 0％	× 3％	◎ 56％	○ 80％	○ 83％	△ 86％
30kGy	× 0％	× 5％	◎ 69％	○ 78％	○ 90％	× 91％
							50kGy	× 0％	× 5％	◎ 55％	○ 77％	○ 86％	× 93％

80kGy	× 0％	× 9％	△ 51％	△ 76％	△ 84％	× 96％
							120kGy	× 0％	× 0％	△ 47％	△ 68％	△ 83％	× 93％

The expansion characteristics of 42 kinds of samples of assessment, and measure its gel component per-cent.Table 3 provides the result.Gel component per-cent is measured by aforesaid method.Gel component per-cent provides in the rolling off the production line of each sample.

Pass between gel component per-cent and the electron beam irradiation dose ties up among Fig. 8 and provides.

[method of evaluates dilation characteristic]

For the sample that can not be expanded to 2.5 times of raw footages, the ratio of enlargement when not breaking following can the expansion by assessing sample stage by stage.Ratio of enlargement provides in the reaching the standard grade of each sample.

*=almost can not the expansible sample

△=under the expansion multiple that is expanded to 1.2 to 2.0 times of its original lengths, break

2.0 to 2.5 of zero=its original length

2.5 times of its original length of ◎=be not less than

In table 3, the sample of embodiment centers on two-wire and assesses with ◎ and zero.The sample of comparative example be in the two-wire periphery and be labeled as △ and *.

Be labeled as △ and * some samples of comparative example in, the irradiation dose 0kGy of electron beam or the add-on of TAIC are no more than 0.5wt%.In some samples of comparative example, the irradiation dose of electron beam is 80kGy and 120kGy, regardless of the add-on of TAIC.

By the measuring result that provides among Fig. 3, the sample that contains the comparative example that is lower than 1.0wt% (0.5wt%) TAIC has gel component per-cent and is not more than 9%.Find that gel component per-cent is no more than 30 to 50kGy (regardless of the concentration of TAIC), and the effect of the effect when 20kGy when being gel component per-cent 30 to 50kGy 80 to 90%.Confirm that also along with irradiation dose increases, gel component per-cent reduces gradually.

In the evaluates dilation characteristic, gel component per-cent 50 is labeled as ◎ to 70%; Gel component per-cent 10 to 50% and 70 to 90% is labeled as zero; Gel component per-cent 10 is labeled as △ to 6%; And gel component per-cent 0 to 5% and 90 to 96% is labeled as *.

This shape is stored by the network that is cross-linked to form.Therefore be no more than 50% and when preferably being lower than 10% when cross-linking density, lose shrinkage character and thermotolerance.On the other hand,, particularly surpass at 90% o'clock, crosslinked excessively carry out and sample becomes firmly and distortion hardly when cross-linking density surpasses 70%.Therefore, confirm that expansion characteristics and heat shrinkability characteristic are good in 50 to 70% scopes.

As mentioned above, the irradiation dose of electron beam is preferred for being 10kGy to 50kGy.

This be because when by the use TAIC crosslinking reaction of carrying out when finishing under 30 to 50kGy, only carry out the decomposition reaction of polylactic acid molecule.In other words, after crosslinking reaction was finished, cross-linked network broke because of polylactic acid molecule decomposes at a lot of points, and corsslinking molecular is helpless to the shape storage.Therefore heat shrinkability characteristic reduces.

The sample that is labeled as ◎ and zero that to be made up of the sheet heat shrinkable material is not less than 150 to 160 ℃ (they are the poly(lactic acid) temperature of fusion) and is not higher than under 180 ℃ the condition at heating condition and expands, and wherein gel component per-cent is set at 50 to 70%.

When this expanded, heat shrinkable material was inflatable to being not less than 2.5 times of its original length.Therefore when being heated to, heat shrinkable material is not less than 160 ℃ so that during its thermal contraction, this is crosslinked because of the TAIC partial rupture, and heat shrinkable material is got back to the shape by the corsslinking molecular storage.Therefore, heat shrinkable material is contracted to and is not less than 40% and be not higher than 70%.

In addition, under poly(lactic acid) glass transition temp (being lower than 60 ℃ slightly), contraction factor is not higher than 10%, and gel component per-cent be 50 to 70% promote thus crosslinked.Heat shrinkable material is not easy distortion at normal temperatures and improves its thermotolerance like this.Therefore this heat shrinkable material can be preferred for vehicle and open air.

In table 3, the sample that its expansion characteristics is evaluated as ◎ and zero satisfies following three conditions:

(1) add-on of TAIC is 1.0 to 3.0wt%.

1.0 to 2.0wt% the time, be ◎ with a lot of sample evaluatings.

(2) irradiation dose of electron beam is 10kGy to 50kGy,

(3) gel component per-cent is 50% to 70%

[measuring the thermal contraction factor]

The heating of expansible sample is returned to its preceding degree that expands with measurement.

As measuring method, after sample expanded poured into thermostatic bath and be heated to preset temperature, in the length that is higher than under 40 ℃ with 10 ℃ of interval measurement expansion directions.

(length) contraction factor (%)=(length after perisystolic length-contraction)/(perisystolic length) * 100

Figure among Fig. 9 shows the measuring result of the thermal contraction factor of the postradiation sample of electron beam that contains TAIC 1.0wt% and use dosage 20kGy.

As shown in Figure 9, regardless of the per-cent that expands, contraction factor is no more than 5% under 140 ℃ the temperature being no more than, and this sample begins to shrink under temperature surpasses 140 ℃.Contraction factor is about 40% in the time of 150 ℃, and is about 65 to 70% when being not less than 160 ℃.

Use identical poly(lactic acid) and identical TAIC as those of the sample of the foregoing description, the uniform mixture by molding poly(lactic acid) and TAIC forms heat-shrinkable tube.Similar to the above embodiments, by changing the irradiation dose electron beam irradiation tube.Similar with the foregoing description 1, after heat-shrinkable tube irradiation, it is expanded to 2.5 times of its raw footage, prepares the heat-shrinkable tube sample thus.

Can confirm,, need be not less than the TAIC of 1.0wt%, and when the irradiation dose of electron beam is 10 to 50kGy, can obtain 10 to 90% gel component per-cent even in heat-shrinkable tube.

As mentioned above, because the electron beam irradiation, the 3rd heat-shrinkable Biodegradable material has gel component per-cent 10 to 90%h and preferred 50 to 70% crosslinking structure.Therefore, Biodegradable material is stable on heating, and behind the mixture expansion, and crosslinked mesh network shrinks, its storage shape during thermal contraction under the temperature that reason is to use when mixture when component is in thermal expansion.Therefore, Biodegradable material makes it have the thermal contraction factor 40 to 80%, is higher than the thermal contraction factor of conventional Biodegradable material.

The 4th embodiment is described below.

In the Biodegradable material of the 4th embodiment,, use polysaccharide derivates such as hydrophobic starch and Mierocrystalline cellulose as biodegradable polymers.Other amount of substance that adds in the polysaccharide derivates is not the very big Biodegradable material that forms the 4th embodiment with high strength and expansion per-cent thus.The cross-linking type polyfunctional monomer is added hydrophobic polysaccharide derivates so that Biodegradable material has the crosslinking structure of gel component per-cent (gel component dry weight/initial dry weight) 10 to 90%.

More specifically, in Biodegradable material, 0.1 to 3wt% polyfunctional monomer is added in the hydrophobic polysaccharide derivates of 100wt%.This mixture is crosslinked to produce by polyfunctional monomer with the ionization radiation irradiation of dosage 250kGy, crosslinked thus hydrophobic polysaccharide derivates.So, the friendship derivative that makes mixture have gel component per-cent (gel component dry weight/initial dry weight) 10 to 90% connects structure.

As hydrophobic polysaccharide derivates, similar with second embodiment, the starch derivative of etherificate is as using starch such as W-Gum, yam starch, sweet potato starch, wheat starch, rice starch, tapioka starch, sago starch as the methyl starch of its material, ethyl starch etc.; Esterified starch derivative such as amylcose acetate, aliphatic ester starch etc. and alkyl starch derivative.As hydrophobic polysaccharide derivates, can use to be similar to the derivative that its material is cellulosic starch.Can also use other polysaccharide such as Pullulan (amylopectin) derivative.

These hydrophobic polysaccharide derivates can use separately or use by mixing its two or more.But the substitution value that requires hydroxyl basically is not less than 1.5, be not less than 1.8 and more preferably be not less than 2.0 and be not higher than 3.0 suitably.In other words, require derivative fully hydrophobic.

Further, as these derivatives, for improving its snappiness, can use those softening agent that are similar to first to the 3rd invention.

As with hydrophobic polysaccharide derivates blended polyfunctional monomer, be similar to first to the 3rd the invention the allylic monomer that has be effective.Especially, can preferably use cyanacrylate (hereinafter referred to as TAIC) and front three for allyl group isocyanuric acid ester (hereinafter referred to as TMAIC).

As mentioned above, the concentration ratio that adds hydrophobic polysaccharide derivates is set at is not less than 0.1wt% and is not higher than 3wt%.This is because can guarantee to obtain this effect in 0.5 to 3wt% scope, although it is believed that this effect under 0.1wt%.

Owing to polyfunctional monomer is added in the hydrophobic polysaccharide derivates, by producing crosslinking reaction with this mixture of ionization radiation irradiation.At this moment, by being to make this mixture have gel component per-cent (gel component dry weight/initial dry weight) to be not less than 10% crosslinking structure and can to keep to a certain degree intensity.For reliably guaranteeing intensity, preferably gel component per-cent is set at and is not less than 50%.

For making gel component per-cent be not less than 50%; preferred fatty acid ester starch, acetic ester starch and typel element or the acetylize Pullulan (amylopectin) of using is as hydrophobic polysaccharide derivates; use cyanacrylate (TAIC) or front three for allyl group isocyanuric acid ester (TMAIC) as polyfunctional monomer, and shine the mixture of these components with dosage 20 to 50kGy.

As mentioned above, owing to polyfunctional monomer adds in hydrophobic polysaccharide derivates such as starch or the Mierocrystalline cellulose, by its mixture is made this Biodegradable material generation crosslinking reaction with the ionization radiation irradiation.Can provide Biodegradable material, because in polymkeric substance, form countless three-dimensional net structures with the indeformable such intensity of polymkeric substance.Therefore, can improve the strength characteristics of Biodegradable material and make it have the retention of configuration performance (being high rigidity) of the conventional universal product that is similar to the product that the oil synthesizing polymeric material makes and make this Biodegradable material as surrogate.By using Biodegradable material, can solve the problem of processing of waste in addition.

In the method for the 4th embodiment of making Biodegradable material, polyfunctional monomer adds in the hydrophobic polysaccharide derivates, and behind the mixture of mediating polyfunctional monomer and hydrophobic polysaccharide derivates, this mixture is molded as predetermined shape.Make this Biodegradable material have crosslinking structure thus with the ionization radiation irradiation moulding material then.

More specifically, this hydrophobic polysaccharide derivates is heated to such temperature during beginning: this derivative is by thermoplastic or be dissolved or dispersed in and hydrophobic polysaccharide derivates can be dissolved in the solvent of acetone, ethyl acetate or its analogue under this temperature.Then, this polyfunctional monomer is added in the hydrophobic polysaccharide derivates that dissolves and be scattered in the solvent.Then, these materials are mixed as far as possible mutually equably.Molding mixture is therein undertaken down or by its mixture being dissolved under the state in the solvent by thermoplastic state.In addition, this mixture can by in cooling or be dried remove desolvate after with its once more thermoplastic be molded as desired shape by injection moulding etc.

Similar with first to the 3rd invention, as being used for crosslinked ionizing rays, can use gamma-radiation, x-ray, beta-rays or α-ray.In industrial production, preferably from the gamma-radiation of cobalt 60 emissions with from rumbatron ejected electron bundle.Produce the required irradiation dose of crosslinking reaction for being not less than 1kGy and not being higher than 300kGy, advantageously be not less than 2 and be not higher than 50kGy.

Except using ionizing rays, similar with first to the 3rd invention, can add chemical initiator and carry out crosslinking reaction.In the case, will have and add hydrophobic polysaccharide derivates under allylic monomer and chemical initiator be not less than biodegradable aliphatic polyester fusing point in temperature the temperature.Component mediated and mutually behind the uniform mixing, the temperature of the moulding material be made up of mixture of raising is until the chemical initiator thermolysis.

The embodiment (embodiment 12 to 19) and the comparative example (comparative example 19 to 27) that prepare the 4th embodiment.

(embodiment 12)

As hydrophobic polysaccharide derivates, use aliphatic ester starch (CP-5, manufacturer Nippon Corn starch Inc.).In polysaccharide derivates, the substitution value of hydroxyl is about 2.0.CH at fatty acid ester starch ₂The substitution value average out to 10 of side chain place chain.The polysaccharide derivates water fast, but dissolve in the acetone.Therefore, this polysaccharide derivates is hydrophobic.Then this fatty acid ester starch is melted down at 150 ℃ with Lab Plast mill (it is a kind of kneader of sealing).Then add 3wt%TAIC (the NipponKasei Inc. of manufacturers) in fatty acid ester starch, it is for having allylic monomer.This mixture was mediated 10 minutes under 20rpm.Be sheet material with this mixture 150 ℃ of following hot pressing then with thickness 1mm.In removing the inert atmosphere of air, with this sheet material by using rumbatron (acceleration voltage: 2MeV and current value: 1mA) under irradiation dose 50kGy, shine with electron beam.The cross-linked material that obtains is used as the sample of embodiment 12.

(embodiment 13,14)

The add-on of the TAIC that uses in embodiment 12 (it is for having allylic monomer) prepares the sample of embodiment 13 as the 1wt% by mode similar to Example 12.Except the add-on of TMAIC (it is produced by Nippion Kasei Inc. for having allylic monomer) is outside the 1wt%, prepare the sample of embodiment 14 by mode similar to Example 12.

(embodiment 15 to 17)

Acetic ester starch (the CP-1 that has substitution value 2 except use, produce by Nippon Corn starch Inc.) as hydrophobic polysaccharide derivates, use 1wt% TAIC as having allylic monomer and under kneading time and extrusion time, Heating temperature be set at outside 200 ℃ (consistent with the softening temperature of resin), obtain the sample of embodiment 15 by the mode identical with embodiment 12.

As hydrophobic polysaccharide derivates; use has the rhodia (L-30 of substitution value 2; produce by DaiseruKagaku Inc.) and have the acetylize Pullulan (amylopectin) (NSP-26 is by Sanuki Kagaku Kogyo Inc. production) of substitution value 2.6.80wt% acetone and 1wt%TAIC are added in the 100wt% polysaccharide derivates.These components are mixed mutually by using mixed milling machine (a kind of rotation kneader).After the mixture drying, be poured in the die head, be 0.5mm at its its thickness of dry back like this.Then it at room temperature slowly after the drying, is prepared the casting films of embodiment 16,17 thus.

(embodiment 18,19)

Except with 3wt%ofHDDA as the polyfunctional monomer, prepare the sample of embodiment 18 by the mode identical with embodiment 12.Except the TMPT (producing) that uses 3wt%, prepare the sample of embodiment 19 by mode similar to Example 12 by Aldrich Inc..

(comparative example 19 to 27)

By preparing the sample of each comparative example 19 to 26 with the similar mode of embodiment 12-19, different is that sample shines without electron beam.Prepare the sample of comparative example 27 by mode similar to Example 12, but do not contain monomer in this sample.

Embodiment 12 to 19 provides in table 4 with the difference of comparative example 19 to 27.

For embodiment and comparative example,, measure gel component per-cent by aforesaid method for the molecule crosslinked degree that assessment is undertaken by irradiation.Be the effect of assessment, measure breaking tenacity by carrying out tension test by crosslinked improvement sample strength.

The gel component per-cent of the sample of each embodiment and comparative example (when shining under 50kGy) provides in table 4.

The figure that shows the relation between the electron beam irradiation dose and gel component per-cent in the sample of embodiment 12,13,18 and 19 provides in Figure 10.

When the sample of embodiment 12 and comparative example 27 is shaped to the rectangle with width 1cm and length 10cm, the chuck of sample with interval 2cm spurred with draw speed 10m/min, measure its tensile break strength thus.

Breaking tenacity (kg/cm ²Tensile strength/(thickness of sample * sample width) during)=fracture

Based on this result, the figure of the relation between reading beam irradiation dose and the breaking tenacity provides in Figure 11.

(result of assessment embodiment and comparative example)

Find out that from result's (table 1) of gel component per-cent found not crosslinked differently with the sample of comparative example 19 to 27, in embodiment 12 to 19, glycan molecule is cross-linked with each other by radioactive rays.Find to have allylic monomer such as TAI and compare with TMPT with TMAIC and monomer such as HDDA and make molecule more effective mutually crosslinked.

This is apparent from Figure 11.Even when TAIC has 1% lower concentration, TAIC also can make crosslinked more effective carrying out.Therefore, TAIC is fit to the crosslinked monomer that is used as the hydrophobic polysaccharide derivates of biodegradable resin very much.

As shown in figure 11, crosslinked effect reflects its intensity.In other words, contain add fatty acid ester starch TAIC with sample by the crosslinked embodiment 12 of radioactive rays, have for the intensity of the about twice of sample of the comparative example 27 that do not contain TAIC and under irradiation dose 50kGy up to the intensity of 1.5 times of its green strength amounts.

Consider that this crosslinkedly is the bonding between the molecule, therefore estimate easily to have improved the distortion that the intensity under the high temperature, melt resistant cause, promptly improved thermotolerance.Therefore need therein in the application of intensity at high temperature, product of the present invention is effective.

As mentioned above, the 4th invention can be achieved by shine crosslinked hydrophobic polysaccharide derivates with the ionization mode.In addition, can improve low strength greatly by molecule crosslinked effect as hydrophobic polysaccharide derivates shortcoming.The feature of the Enhancement Method that is cross-linked with each other by molecule can be expected at high temperature reinforced effects especially, and makes Biodegradable material of the present invention be widely used as the surrogate of general-purpose plastics.

Claims (3)

1. the method for preparing Biodegradable material is wherein mediated the biodegradable aliphatic polyester of allylic monomer of having of 1.2wt% to 5wt% and 100wt%; The uniform mixture that obtains is molded as desired shape; Use the uniform mixture of molding greater than 30kGy and be not higher than the ionizing ray irradiation of 100kGy irradiation dose, produce crosslinking reaction thus, described so biodegradable aliphatic polyester is crosslinked in such a way, and the gel component per-cent of described biodegradable aliphatic polyester is not less than 75% and be not higher than 95%.

2. the Biodegradable material of making by claim 1 method.

3. the Biodegradable material of claim 2, it has 150 to 200 ℃ fusing point, and expansion per-cent is 100 to 30%, and the tensile strength under near the high temperature the described fusing point is 20 to 100g/mm ²

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