WO2007036168A1 - Materiau biodegradable hydrophobe - Google Patents

Materiau biodegradable hydrophobe Download PDF

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Publication number
WO2007036168A1
WO2007036168A1 PCT/CN2006/002603 CN2006002603W WO2007036168A1 WO 2007036168 A1 WO2007036168 A1 WO 2007036168A1 CN 2006002603 W CN2006002603 W CN 2006002603W WO 2007036168 A1 WO2007036168 A1 WO 2007036168A1
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Prior art keywords
polyvinyl alcohol
weight
mixture
starch
water
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PCT/CN2006/002603
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English (en)
French (fr)
Inventor
Xiaolu Li
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Xiaolu Li
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Publication of WO2007036168A1 publication Critical patent/WO2007036168A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/05—Alcohols; Metal alcoholates
    • C08K5/053—Polyhydroxylic alcohols
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L29/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
    • C08L29/02—Homopolymers or copolymers of unsaturated alcohols
    • C08L29/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L3/00—Compositions of starch, amylose or amylopectin or of their derivatives or degradation products

Definitions

  • This invention relates to a biodegradable material, and more particularly to a hydrophobic biodegradable material. Background technique
  • CN 1405230 A discloses a water-soluble, non-contaminating and completely biodegradable plastic molding material which contains polyvinyl alcohol, glycerol, diethylene glycol, sorbitol, fiber, white carbon black. , ultra-fine calcium, modified starch.
  • CN 1405230A also discloses a preparation method of the material: adding 1-30 parts of glycerin to the polyvinyl alcohol raw material, stirring at a high temperature, sufficiently wetting, and then adding an appropriate amount of a plasticizer and a crosslinking agent.
  • the reaction is blended at a temperature of 25-65 ° C for 5-50 minutes, and the obtained material is added to a single screw or twin screw extruder for granulation.
  • the above materials can be blown and foamed at a temperature ranging from 150 to 250 °C.
  • the material prepared by this method is subjected to thermoplastic extrusion under heating at 160 to 190 ° C according to the method of CN 1405230A, the inventors of the present invention have found that only a small portion of the material is in a molten state, and is heated. By 200 ° C, the material has begun to carbonize. This indicates that the material is not a thermoplastic material, and blown film formation in a molten state cannot be achieved, and the cast film can be prepared only by a casting method which does not require heating and melting.
  • CN 1357563A discloses a preparation method of a starch-polyvinyl alcohol-polyester ternary system biodegradable film, the raw material of the biodegradable film containing: 30-65% starch, 15-40% poly Vinyl alcohol, 0-10% polyester, 10-20% plasticizer, 0.4% reinforcing agent, 0.5-1.5% wet strength agent and 0.4% antifoaming agent, wherein plasticizer by weight
  • the biodegradable film is prepared by first mixing polyvinyl alcohol with starch, and then Dissolve water dissolved in a reinforcing agent, a wet strength agent and an antifoaming agent The liquid is mixed with a mixture of polyvinyl alcohol and starch, and finally mixed with a plasticizer and stirred and uniformly granulated and extruded.
  • the material prepared by this method cannot be formed into a molten state, nor is it a thermoplastic material, nor can it be blown film formed in a molten state, and can only be cast by a method which does not require heating and melting. A cast film was prepared.
  • the cast film is not easy to control the thickness during the preparation process, and the cast film prepared is generally thick and uneven.
  • the mechanical properties of the cast film such as tensile rupture strength, elongation at break and right angle tear strength are inferior to those of the thermoplastic formed blown film, and the general requirements for the mechanical properties of the film product cannot be satisfied.
  • the production efficiency of the cast film is very low, and the method and process for forming the cast film into a product are complicated. For example, when a bag is made of a cast film, it is necessary to fold a cast film in half, and then cast the folded film.
  • the object of the present invention is to overcome the shortcomings of the existing biodegradable materials containing polyvinyl alcohol which are not plastic and can not be used for forming a sheet-like shaped article, and provide a plasticity which can be used for forming a sheet. Hydrophobic biodegradable materials for articles and methods for their preparation.
  • the inventors of the present invention conducted research on polyvinyl alcohol, and as a result, found that there is a large amount of hydroxyl groups in the molecule of polyvinyl alcohol, and between the hydroxyl group and the hydroxyl group. Strong hydrogen bonding is formed, so that a large number of hydrogen bonds exist between the molecules of the polyvinyl alcohol and in the molecule; in addition, since the polyvinyl alcohol molecules are flexible molecules, the molecules are intertwined to form an intricate high-barrier molecular chain structure.
  • the interaction force between the polymer molecules is much larger than the van der Waals force between the molecules of the general compound, thus causing to overcome this
  • the force requires a higher melting temperature.
  • the melting temperature of polyvinyl alcohol is as high as 220-240 ° C, which is higher than its decomposition temperature (about 200 ° C).
  • the melting temperature of polyvinyl alcohol is higher than its decomposition temperature so that polyvinyl alcohol generally begins to decompose and carbonize before melting, and it is almost impossible for polyvinyl alcohol to reach a stable molten state.
  • polyvinyl alcohol must react with starch and other components in a molten state to form a biodegradable material having a stable molten state.
  • the polyvinyl alcohol under the above process conditions fails to destroy the original hydrogen bond.
  • the action is not possible to achieve a stable molten state, so that the existing biodegradable material containing polyvinyl alcohol cannot achieve the molten state and its thermoplastic processing.
  • the inventors of the present invention have speculated that although the method disclosed in CN 1405230A uses plasticizer glycerin to plasticize polyvinyl alcohol, the plasticizer glycerol cannot destroy the interweaving between polyvinyl alcohol molecules and cannot enter. In the case of polyvinyl alcohol molecules, the mixing between the plasticizer and the polyvinyl alcohol is only a simple physical blend. The polyvinyl alcohol in the mixture is still the original polyvinyl alcohol, and the plasticizer cannot truly be used for the polyvinyl alcohol.
  • the preparation method disclosed in CN 1357563A is to first mix polyvinyl alcohol with starch, and then add an aqueous solution in which a reinforcing agent, a wet strength agent and an antifoaming agent are dissolved, and the polyvinyl alcohol is flocculent, granular or powder at normal temperature. Since the water absorption of starch is much greater than the water absorption of polyvinyl alcohol, most of the water in the added aqueous solution is quickly absorbed by the starch, and only a very small part of the water is absorbed by the polyvinyl alcohol, and most of the polyvinyl alcohol is still original. Physical state.
  • the polyvinyl alcohol is coated in the starch due to the expansion gelation of the starch after absorbing moisture, which prevents the contact of the polyvinyl alcohol with the water, so that even if a large amount of water is added, it cannot be contacted with the polyvinyl alcohol, and most of the polyethylene is
  • the alcohol is still in the original state of polyvinyl alcohol, and such polyvinyl alcohol still cannot reach the molten state.
  • the added plasticizer still cannot be plasticized into polyvinyl alcohol and can only be absorbed by the starch, so the above mixture is a simple mixture of the aqueous starch and polyvinyl alcohol, plasticizer and auxiliary components. The molten state is still not achieved.
  • prior art granulation and subsequent extrusion molding thereof, etc. The process is carried out by heating and melting the mixture in a single-screw or twin-screw extruder in a molten state with a certain fluidity. Only such molten material can be used in a single-screw or twin-screw extruder. Extrusion granulation and extrusion molding in a subsequent process.
  • the materials disclosed in the existing polyvinyl alcohol-containing materials such as CN 1405230A and CN 1357563A, are a simple mixture. Since polyvinyl alcohol is not substantially plasticized, most of the polyvinyl alcohol The original state exists.
  • thermoplastic materials especially hydrophobic thermoplastics
  • there is no compatibility between the free-form water and the thermoplastic material which causes a large amount of bubbles in the thermoplastic material during processing. Cracking, which seriously affects the appearance quality and physical properties of the product. Therefore, in the preparation of thermoplastic materials, it is necessary to strictly control the content of water in the raw materials and the amount of water present during the processing.
  • the inventors of the present invention have unexpectedly discovered that water and hydrophobic polyvinyl alcohol are first mixed at 45 Torr or more, and after the polyvinyl alcohol is sufficiently swollen by water to form an aqueous polyvinyl alcohol, the polyol and the starch are added and uniformly mixed to obtain
  • the mixture can be extruded and granulated in a molten state in an extruder to obtain a pellet of hydrophobic biodegradable material which can reach a stable melting temperature and whose melting temperature is significantly lower than its decomposition temperature.
  • the pellet has a melting temperature of 130-210 ° C and a decomposition temperature of 260-420 ° C.
  • the thermoplastic processing property is very good and can be used for extrusion molding into sheet-formed articles.
  • the molecular weight of water is very small.
  • water and hydrophobic polyvinyl alcohol are separately contacted at 45 ° C or above, water easily enters the molecular structure of polyvinyl alcohol, opening the molecular chain of polyvinyl alcohol, so that the original The intertwined molecular chains of polyvinyl alcohol are fully stretched, making it easier for plasticizers to enter the polyvinyl alcohol, and plasticizing and modifying the polyvinyl alcohol together, fully plasticizing and modifying the polyethylene.
  • the alcohol can form a stable molten state and react with starch and a plasticizer under molten conditions to obtain a reaction product.
  • the reaction product not only has a stable melting temperature of 130-210 ° C, but the melting temperature is significantly lower than its decomposition temperature of 260-420 ° C.
  • the above properties of the material determine that the material is a completely new thermoplastic material that makes thermoplastic molding of biodegradable materials possible.
  • the present invention provides a hydrophobic biodegradable material, wherein the material is a product formed by melting a mixture comprising a polyol and an aqueous polyvinyl alcohol, with or without starch, the poly
  • the vinyl alcohol is a hydrophobic polyvinyl alcohol, and the content of the polyol is from 15% by weight to less than 25% by weight based on the total weight of the mixture.
  • the materials and articles thereof provided by the present invention are completely biodegradable (ISO 14855, 99 days up to 90% or more).
  • the hydrophobic biodegradable material provided by the present invention is a product formed by melting a mixture, the melting temperature of the material is 130-210 ° C, the decomposition temperature is 260-420 ° C, and the melting temperature is low. At the decomposition temperature, it has a molten state, and has an unparalleled thermoplastic processability of a mixture material obtained by simple physical mixing between ordinary polyvinyl alcohol, starch and polyol, enabling true melt extrusion granulation and Extrusion molding.
  • the hydrophobic biodegradable material provided by the invention can be obtained by extrusion molding to obtain a sheet-like shaped article, and the obtained product has good impact strength and tensile yield strength of the simply supported beam, and the biodegradation rate is extremely high, 45 days.
  • the biodegradation rate is greater than 60%, the 60-day biodegradation rate is greater than 70%, and the 99-day biodegradation rate is greater than 90%, which fully meets the requirements of ISO 14855 for biodegradable products (the biodegradation rate is greater than 90% in 180 days).
  • the sheet-formed article thus obtained has excellent water resistance, and the shape and mechanical properties of the product which is immersed in water for 1 hour or more are not changed.
  • an organic carboxylic acid during the preparation of the hydrophobic biodegradable material, the phenomenon that the oily small liquid bead is oozing out from the surface of the product prepared by the material and the adhesion between the products can be avoided, and the product is further improved. Usability.
  • DRAWINGS 1 is a differential scanning calorimetry (DSC) curve of a hydrophobic biodegradable material prepared in Example 1 of the present invention
  • FIG. 2 is a thermogravimetric curve of a hydrophobic biodegradable material prepared in Example 1 of the present invention
  • FIG. 3 is a scanning electron micrograph of the original starch used in Example 1 of the present invention
  • Figure 4 is a scanning electron micrograph of a cross section of a hydrophobic biodegradable material prepared in Example 1 of the present invention. detailed description
  • the present invention provides a hydrophobic biodegradable material, wherein the material is a product formed by melting a mixture comprising a polyol and an aqueous polyvinyl alcohol, with or without starch, the poly
  • the vinyl alcohol is a hydrophobic polyvinyl alcohol, and the content of the polyol is from 15% by weight to less than 25% by weight based on the total weight of the mixture.
  • the content of the aqueous polyvinyl alcohol in the mixture is from 5 to 80, preferably from 10 to 70, based on the total weight of the mixture, and the content of the polyol is from 15% by weight to less than 25% by weight, preferably from 15 to 24.9 by weight.
  • the content of starch is from 0 to 75% by weight, preferably from 15 to 70% by weight.
  • the hydrophobic biodegradable material provided by the present invention has a melting temperature of 130 to 210 ° C, preferably 140 to 200 ° C, and a decomposition temperature of 260 to 420 Torr, preferably 270 to 410 °C.
  • the mixture contained 15.0% by weight of aqueous polyvinyl alcohol, 60.0% by weight of starch, 8.0% by weight of glycerin, 10.0% by weight of pentaerythritol, 1.0% by weight of carboxymethylcellulose, 2.0. Weight% zinc stearate, 1.0% by weight?
  • the resulting material has a melting temperature of 148-195 ° C and a decomposition temperature of 279-385 ° C.
  • the content of each component in the mixture is different, and the melting temperature and decomposition temperature of the obtained material are also slightly different.
  • the weight ratio of polyvinyl alcohol to water is preferably from 1.5 to less than 5, more preferably from 1.5 to 4.9.
  • the polyvinyl alcohol may be various hydrophobic polyvinyl alcohols in the prior art.
  • the hydrophobic polyvinyl alcohol means a polyvinyl alcohol which can be dissolved only in water of 45 ° C or more.
  • the polyvinyl alcohol has the formula -(CH 2 CHOH) n -, which is white or yellowish flocculent, granular or powdery solid at normal temperature.
  • the degree of alcoholysis of the hydrophobic polyvinyl alcohol is from 80 to 100%, preferably from 85 to 95%; and the degree of polymerization of the hydrophobic polyvinyl alcohol is from more than 2,000 to 3,000, preferably from 2050 to 3,000.
  • Polyvinyl alcohol is mainly obtained by the alcoholysis of polyvinyl acetate, that is, the reduction of polyvinyl acetate, the degree of alcoholysis indicates the degree of reduction (alcoholysis), and the higher the degree of alcoholysis, the reduction of polyvinyl acetate. The higher the degree of polyvinyl alcohol.
  • the polyol may be selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, glycerin, pentaerythritol, sorbitol, and one of an incomplete esterification product of a polyhydric alcohol with a long-chain fatty acid (such as glyceryl monostearate). Or several, preferably one or more of glycerin, sorbitol and pentaerythritol.
  • the polyol can function to plasticize polyvinyl alcohol.
  • the polyols may be used singly or in combination of two or more kinds, preferably used in combination.
  • the mixture may further contain a cellulose-based polymer which also functions as a plasticizer for plasticizing polyvinyl alcohol.
  • the cellulose-based polymer is selected from the group consisting of carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose (HPMC), and hydroxypropyl ethyl cellulose. Or several.
  • the cellulose-based polymer may be included in an amount of from 0 to 10% by weight, based on the total amount of the mixture, preferably from 2 to 6% by weight.
  • the starch may be various starches of the prior art, for example, natural starch or modified starch may be used.
  • the natural starch may be selected from one or more of corn starch, potato starch, sweet potato starch, tapioca starch, wheat starch, and legume starch, and may be amylopectin and/or amylose.
  • Examples of the modified starch include oxidized starch, esterified starch, and etherified starch.
  • the esterified starch may be selected from one or more of starch phosphate, starch sulfate, starch nitrate, starch acetate, and starch propionate.
  • the etherified starch may be selected from the group consisting of carboxyl starch, cyano starch, amide starch, hydroxyalkyl starch, alkyl starch, aryl starch, primary amine starch ether, secondary amine starch ether, tertiary amine starch ether, and key starch ether.
  • carboxyl starch cyano starch
  • amide starch hydroxyalkyl starch
  • alkyl starch aryl starch
  • primary amine starch ether secondary amine starch ether
  • tertiary amine starch ether tertiary amine starch ether
  • key starch ether key starch ether.
  • One or more of the cyanamide starch is selected from the group consisting of carboxyl starch, cyano starch, amide starch, hydroxyalkyl starch, alkyl starch, aryl starch, primary amine starch ether, secondary amine starch ether, terti
  • the starch-free mixture also has a stable molten state, and the obtained material is obtained. It can also be used to prepare sheet-formed articles.
  • the addition of starch can correspondingly reduce the content of polyvinyl alcohol in the mixture, and reduce the material of the present invention.
  • the cost of raw materials can also increase the biodegradability of materials.
  • starch is a hydrophilic substance, and the higher the content of starch, the mechanical properties of the obtained material and its products are also lowered. Considering the various factors of biodegradability, mechanical properties and cost, the starch content can be adjusted as needed.
  • the mixture according to the invention contains from 0 to 75% by weight of starch, preferably from 15 to 70% by weight, based on the total amount of the mixture.
  • the mixture may further contain a polyester.
  • the polyester may be various hydrophobic polyester compounds, for example, may be selected from various polyester compounds in which an ester group is branched, and the polyester compound may be an aliphatic polyester compound or an aromatic polyester compound or A mixture thereof, which may be, for example, one or more of polycaprolactone, polycarbonate, poly- ⁇ -hydroxybutyrate ( ⁇ ); preferably poly- ⁇ -hydroxybutyrate .
  • the polyester may be included in an amount of from 0 to 20% by weight, based on the content of the mixture, preferably from 0.5 to 15% by weight.
  • Another method of increasing the water resistance of the hydrophobic biodegradable material of the present invention is to enclose a hydrophilic hydroxyl group in a component such as polyvinyl alcohol.
  • the hydroxyl group can be blocked by various means in the prior art. For example, a cross-linking condensation reaction between polyvinyl alcohol molecules can be carried out to form a hydrophobic ether bond to block the hydroxyl group, and the hydroxyl group condensation between the molecules can also enhance the polyethylene.
  • the degree of polymerization of the components such as alcohol further increases the molecular weight, and the hydrophobicity of the molecule is further improved. It is also possible to block the hydroxyl group by other hydroxyl groups to form other hydrophobic groups by other blocking agents.
  • the mixture of the present invention may further contain a blocking agent, and the blocking agent may be selected from the group consisting of borax, boric acid, formaldehyde, dialdehyde, trimethyl melamine, dimethyl urea, dimethyl ethyl urea, heavy One or more of chromate, chromium nitrate, and organic titanate.
  • a blocking agent may be selected from the group consisting of borax, boric acid, formaldehyde, dialdehyde, trimethyl melamine, dimethyl urea, dimethyl ethyl urea, heavy One or more of chromate, chromium nitrate, and organic titanate.
  • dialdehydes include, but are not limited to, glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde and isomers thereof, adipaldehyde and isomers thereof, pimediol and its isomers, suberaldehyde And isomers thereof, sebacaldehyde and its isomers, sebacaldehyde and isomers thereof.
  • the content of the agent may be from 0 to 15% by weight, preferably from 0.5 to 15% by weight.
  • a sheet-like shaped article obtained from a mixture containing the above components may have an oily small liquid bead oozing on the surface of the product at a temperature of more than 23 ° C and a relative humidity of more than 60%. Phenomenon, because the liquid beads are sticky, the articles are easily adhered together, which causes inconvenience in the use of the product.
  • the inventors of the present invention have found that the above problems can be effectively avoided by adding an organic carboxylic acid to the above mixture. Accordingly, preferably, the mixture of the present invention further contains an organic carboxylic acid in an amount of from 0.5 to 10% by weight, preferably from 2 to 7% by weight, based on the total weight of the mixture.
  • the organic carboxylic acid may be one or more of organic carboxylic acids having 1 to 20 carbon atoms, preferably one or more of organic carboxylic acids having 1 to 12 carbon atoms.
  • the organic carboxylic acid may be a monobasic organic carboxylic acid or a polybasic organic carboxylic acid.
  • organic carboxylic acid examples include, but are not limited to, formic acid, acetic acid, propionic acid, butyric acid and isomers thereof, valeric acid and isomers thereof, hexanoic acid and isomers thereof, heptanoic acid and isomers thereof, Octanoic acid and its isomers, citric acid and its isomers, citric acid and its isomers, malonic acid, succinic acid and its isomers, glutaric acid and its isomers, adipic acid and Isomers, pimelic acid and its isomers, suberic acid and its isomers, sebacic acid and its isomers, sebacic acid and its isomers, citric acid, tartaric acid, lauric acid, benzoic acid .
  • the mixture may also optionally contain a salt additive.
  • the salt additive may be selected from one or more of an alkyl sulfonate, an organic acid iron salt, a polyhydroxybutyrate, a stearate, a calcium carbonate, a calcium hydrogencarbonate, a light calcium carbonate, and a shell powder.
  • the stearates include the stearates of Ca, Mg, Zn, Ba, Ce and Fe. These additives can act as lubricants to reduce friction between components of the material and between the material and the processing equipment. These additives may be used singly or in combination of two or more, and it is preferred to use them in combination.
  • the content of the salt additive is from 0 to 5% by weight, preferably from 0.2 to 2% by weight, based on the total amount of the mixture.
  • auxiliary agents may be added as needed, and the auxiliary agents include an antioxidant, a light/heat stabilizer, a photo oxidizing agent, an antifogging agent, a flame retardant, an antistatic agent, and a coupling agent. , One or more of an antifoaming agent, a coloring agent, and a lubricant.
  • the type and amount of the adjuvant are well known to those skilled in the art, for example, the amount of the adjuvant is from 0 to 5% by weight, preferably from 0.3 to 4% by weight, based on the total amount of the mixture.
  • a light/heat stabilizer may be added.
  • the antioxidant may be selected from tetrakis(3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionic acid) pentaerythritol ester (referred to as antioxidant 1010), thiodipropionate distearyl
  • antioxidant DSTP an acid ester
  • phosphite a phosphite
  • composite antioxidant PKY a bisphenol oxime.
  • the light/heat stabilizer may be selected from one or more of UV-series light/heat stabilizers, carbon black, organotin light/heat stabilizers, tridecyl phenyl phosphite (TNPP), epoxidized soybean oil.
  • the UV-series light/heat stabilizer may be ⁇ -hydroxy-4-n-octyloxybenzophenone (abbreviated as UV-531).
  • the organotin light/heat stabilizer may be selected from the group consisting of dibutyltin dilaurate, isooctyl dimethyl thiomethacrylate (hereinafter referred to as ester tin), ester tin RWS-784, double ( Isooctyl thioglycolate) One or more of di-n-octyltin (referred to as Jingxi '8831), dibutyltin dimaleate, dibutyltin thioglycol isooctyl ester.
  • the lubricant may be various lubricants conventionally used, such as liquid paraffin and/or petroleum ether. Lubricants are used to reduce the friction between the pellets and the article and the extruder, which facilitates demolding of the article.
  • the above various adjuvants may be used singly or in combination of two or more.
  • the hydrophobic biodegradable material provided by the present invention can be obtained by heat-melting a mixture containing a polyol, an aqueous polyvinyl alcohol, or a starch containing or not, and then reacting, extruding, and granulating the obtained melt.
  • the aqueous polyvinyl alcohol can be obtained by contacting water with polyvinyl alcohol, and the conditions of contact as well as the amount of polyvinyl alcohol and water are sufficient to sufficiently swell the polyvinyl alcohol.
  • the sufficient swelling of the polyvinyl alcohol means that the weight ratio of the polyvinyl alcohol to water in the swollen polyvinyl alcohol, i.e., the aqueous polyvinyl alcohol, is from 1.5 to less than 5, preferably from 1.5 to 4.9.
  • the reason for the contact of water with polyvinyl alcohol is that the molecular weight of water is small.
  • water When water is contacted with polyvinyl alcohol alone, water easily enters the molecular structure of polyvinyl alcohol, destroying the inter-molecular and molecular molecules of polyvinyl alcohol.
  • the internal hydrogen bond maximizes the intricately intertwined polyvinyl alcohol molecular chain, laying the foundation for the polyol plasticizer to enter the polyvinyl alcohol molecular structure to the maximum extent, thereby ultimately reducing the melting of the polyvinyl alcohol.
  • the temperature allows the mixture containing polyvinyl alcohol to be in a molten state.
  • the weight ratio of the polyvinyl alcohol to water is from 1 to 3, preferably from 1 to 2.5.
  • the conditions of the contact may be sufficient to sufficiently swell the polyvinyl alcohol.
  • the water may be contacted with the polyvinyl alcohol in a standing state for a sufficient period of time until the polyvinyl alcohol is sufficiently swollen.
  • the contact time required may be long.
  • the production efficiency is relatively low. Therefore, in order to sufficiently swell the polyvinyl alcohol in a short period of time to improve the production efficiency, the contact conditions preferably include the polyvinyl alcohol being contacted with water under stirring, and the stirring speed may be 50-650 rpm, contact time can be 30-60 minutes.
  • the polyvinyl alcohol in the present invention is a hydrophobic polyvinyl alcohol, the polyvinyl alcohol is hardly soluble in water at 45 ° C (1 large 'atmospheric pressure) or less, so the contact temperature of the polyvinyl alcohol with water is preferably 80. -105 ° C (1 atmosphere). Since the PVA is directly added to the hot water, there is a phenomenon of clumping and skin dissolution. Therefore, it is preferable to add warm water of less than 60 ° C to the PVA, and gradually increase the temperature of the system to 80-105 with stirring. C.
  • the viscosity of the mixture is large at the above temperature and because the viscosity of the mixture of water and polyvinyl alcohol is large, a large amount of heat is generated during the stirring, so that part of the added water is evaporated, and the longer the stirring time is, the more The higher the heat, the more water is evaporated; the faster the agitation, the higher the heat generated, and the more water that evaporates, so under the above-mentioned polyvinyl alcohol to water weight ratio and contact conditions
  • the weight ratio of polyvinyl alcohol to water in the obtained aqueous polyvinyl alcohol is slightly larger than the weight ratio of polyvinyl alcohol to water, and when the stirring speed is faster and/or the stirring time is longer, the water can be appropriately increased.
  • the amount is such that the weight ratio of polyvinyl alcohol to water in the aqueous polyvinyl alcohol is in the range of from 1.5 to less than 5.
  • the mixture comprising a polyol and an aqueous polyvinyl alcohol, with or without starch can be passed
  • the aqueous polyvinyl alcohol, the polyol obtained above and the starch selectively contained are uniformly mixed.
  • aqueous polyvinyl alcohol, the polyol, and the starch selectively contained are mixed, one or more of a cellulose-based polymer, a salt additive, and an auxiliary agent may be added and uniformly mixed.
  • the mixing is preferably carried out under agitation, and the stirring speed may be from 50 to 650 rpm.
  • the mixing order of the various components in the mixture may be arbitrary.
  • the aqueous polyvinyl alcohol may be firstly mixed with the selectively contained starch, and then the polyol may be added and uniformly mixed; the starch and the selective starch may be mixed.
  • the aqueous polyvinyl alcohol is added and uniformly mixed; the aqueous polyvinyl alcohol and the polyhydric alcohol may be uniformly mixed first, then the selectively contained starch may be added and uniformly mixed; and the aqueous polyvinyl alcohol and the polyhydric alcohol may also be mixed.
  • the alcohol, optionally containing starch is mixed well.
  • the aqueous polyvinyl alcohol and the polyol are uniformly mixed, and then the selectively contained starch is added and uniformly mixed.
  • the aqueous polyvinyl alcohol is added in an amount of 5 to 80% by weight, preferably 10 to 70% by weight based on the total weight of the mixture; the polyol is added in an amount of 15% by weight to less than 25% by weight, preferably 15%.
  • the starch is added in an amount of 0 to 75% by weight, preferably 15 to 70% by weight;
  • the polyester may be added in an amount of 0 to 20% by weight, preferably 0.5 to 15% by weight;
  • the amount of the blocking agent added It may be 0-15% by weight, preferably 0.5-15% by weight;
  • the organic carboxylic acid may be added in an amount of 0-10% by weight, preferably 0.5-10% by weight;
  • the cellulose-based polymer may be added in an amount of 0- 10% by weight
  • the salt additive may be added in an amount of 0 to 5% by weight, and the auxiliary agent may be added in an amount of 0 to 5% by weight.
  • the obtained melt may be subjected to extrusion granulation using a twin-screw extruder under the following conditions, and the twin-screw extruder has an aspect ratio of 20-64 and a screw rotation speed of 50-1500 rpm.
  • the twin-screw extruder is generally divided into 12 sections from the feed end to the discharge end, from the feed end to the discharge. The temperature of each section is set to 90-150 ° C, 95-155 ° C, 100-160 ° C, 115-165 ° C, 120-175 ° C 125-175 ° C, 130-185 ° C, respectively.
  • the 4th and 10th sections are vacuum sections, the vacuum is 0.02-0.09 MPa .
  • the degree of vacuum refers to the absolute value of the difference between the absolute pressure and the atmospheric pressure (the absolute pressure is less than the atmospheric pressure).
  • the twin-screw extruder twin-screws mesh with each other. When the rotation speed of the screw is high, such as 500 rpm or more, the intermeshing twin-screw pair has strong friction and shearing on the material added to the twin-screw extruder. The heat generated by the shearing action, friction and shear causes the actual temperature of the material to be higher than the set temperature of each of the above sections.
  • the blending time of polyvinyl alcohol and water is 30-60 minutes, the stirring speed is 50-650 rpm, the blending temperature is 80-105 ° C; the aqueous polyvinyl alcohol and starch, the polyol
  • the stirring and blending time of the materials may be 5-25 minutes, and the stirring blending speed is 50-250 rpm, preferably first stirring at a low speed and then stirring at a high speed;
  • the obtained mixture is melted, extruded and granulated.
  • the granulation can be carried out, for example, by using a twin-screw extruder, having a length to diameter ratio of 20-64, a screw rotation speed of 50-1200 rpm, and dividing into 12 sections from the feeding end to the discharge end, each section.
  • the temperature is set to 90-150 ° C, 95-155 ° C, and 100-160 in sequence.
  • the 4th and 10th sections are vacuum sections, and the vacuum section has a vacuum of 0.02-0.09 MPa.
  • the mixture is melt extruded and granulated.
  • the hydrophobic biodegradable material of the present invention can be used to prepare a sheet-like shaped article.
  • the method for preparing a sheet-like shaped article from a hydrophobic degradable material may be, for example, first extruding the mixture through a twin-screw extruder to obtain pellets, and then feeding the pellet into a single-screw extruder. Self feed port To the extrusion sequence, follow 140. C, 150 ° C, 160. C, 170 ° C, 175.
  • the temperature of the T-die is 185 ° C, 175 ° C, 185 ° C, respectively, after the molten material is extruded through the T-die, after The three rolls are calendered and wound into a semi-finished sheet; then, the sheet is molded into a molding machine and a mold thereof at a temperature of 160 to 185 ° C to form a sheet-like molded product.
  • Example 1 The invention is further illustrated by the following examples. However, it should be understood that these examples do not constitute a limitation of the scope of the invention.
  • Example 1 Example 1
  • This embodiment is for explaining the hydrophobic biodegradable material provided by the present invention and a preparation method thereof.
  • This comparative example is used to illustrate the existing biodegradable material containing polyvinyl alcohol and a preparation method thereof.
  • This embodiment is for explaining the hydrophobic biodegradable material provided by the present invention and a preparation method thereof.
  • This embodiment is for explaining the hydrophobic biodegradable material provided by the present invention and a preparation method thereof.
  • This embodiment is for explaining the hydrophobic biodegradable material provided by the present invention and a preparation method thereof.
  • This embodiment is for explaining the hydrophobic biodegradable material provided by the present invention and a preparation method thereof.
  • This embodiment is for explaining the hydrophobic biodegradable material provided by the present invention and a preparation method thereof.
  • the above pellet products BSR-07V-HS1 to BSR-07V-HS6 were added to the feed port of the ⁇ 90 extruder manufactured by Guangdong Shantou Jinmeng Packaging Machinery Factory, and divided into 6 zones from the feeding end to the discharge end.
  • the temperature of each section is set to 140 °C, 150 °C, 160 °C, 170 ° (:, 175 °C, 170 °C, and the temperature of the T-die is set to 185 °C, 175 °, respectively.
  • the impact strength of the simply supported beam of the product is determined by the GB/T1043-93 hard plastic simply supported beam impact test method
  • the biodegradation rate of the above product was measured in accordance with the method specified in IS014855-99.
  • Water resistance test method (1) After cutting the above products HS1-HS6 into a standard sample having a size of 100 mm (length) X 100 mm (width) X 0.8 mm (thickness) at 1 atm, 25 ° C After completely immersing in 5 times weight of water for 1 hour, the surface moisture was wiped off, and the appearance change of the product was observed, and the tensile yield strength, the simply supported beam impact strength and the elongation at break of the impregnated product were tested. It was found that the appearance of the product before and after immersion did not change significantly. Other test results are shown in Table 2.
  • Test for surface tackiness of the product Cut the above products HS1-HS6 into 20 samples of 100 mm (length) X 100 mm (width) X 0.8 mm (thickness), and divide the 20 samples into 10 groups (each Two sets), two samples of each set are stacked together, the contact surface is 100 mm (length) X 100 mm (width) surface, and then placed in an environment of 30 ° C and 70% relative humidity. After 48 hours, press each stack of samples in a direction perpendicular to the contact surface with a pressure of 1000 Pa. Then, observe whether each group of samples is stuck together, and record the number of groups of the samples stuck together, and observe whether there are oily small liquid beads on each surface of the sample, and record the results in the following table.
  • A indicates that under normal conditions
  • B indicates that after immersion in 5 times weight of water for 1 hour
  • C indicates the test result after being left at 70% humidity for 30 days.
  • the articles HS1-HS6 made of the hydrophobic biodegradable material pellets BSR-07V-HS1 to BSR-07V-HS6 of Examples 1-6 have a good simple support. Beam strength and tensile yield strength; High biodegradation rate, 45 days biodegradation rate greater than 60%, 60 days biodegradation rate greater than 70%, 99 days biodegradation rate greater than 90%, fully in line with ISO 14855 Requirements for biodegradable products (biodegradation rate greater than 90% in 180 days).
  • the material is a hydrophobic material
  • the product is immersed in water for 1 hour or after being placed in an environment of 30 ° C and 70% relative humidity for 30 days, the appearance does not change, and the strength of the simply supported beam and the tensile yield strength change.
  • the chemical properties are small, indicating that the water resistance of the product is very good.
  • Examples 1, 2 and 6 incorporate polyester and/or a capping agent in the preparation of the hydrophobic biodegradable material, and Examples 3-5 do not use a polyester or a capping agent in the preparation of the hydrophobic biodegradable material.
  • the products made from BSR-07-HS1, BSR-07-HS2 and BSR-07V-HS6 are soaked in water for 1 hour or compared with the products made from BSR-07-HS3 to BSR-07-HS5. After 30 days of standing at 70% humidity, the change in the strength and tensile yield strength of the simply supported beam is smaller and the water resistance is better.
  • This example is intended to illustrate the melting and thermal decomposition properties of the hydrophobic biodegradable material provided in Example 1 of the present invention.
  • the melting and thermal decomposition properties of the hydrophobic biodegradable material pellet product BSR-07V-HS1 obtained in Example 1 were determined by the following method.
  • BSR-07V-HS1 placed in the sample cell of ETZSCH DSC 204F1 differential scanning calorimeter, under the protection of nitrogen gas with a flow rate of 60 ml/min, the sample was taken from 25 °C at a heating rate of 10 °C/min. It was heated to 180 ° C, held at 180 Torr for 2 minutes, and then heated to 300 ° C at a temperature increase rate of 10 Torr / minute to obtain a DSC curve as shown in FIG.
  • thermogravimetric analyzer Germany NETZSCH Instrument Manufacturing Co., Ltd.
  • TG209F1 heated at 10 °C/min under nitrogen protection at a flow rate of 60 ml/min.
  • the sample was heated from 25 ° C to 180 ° C, held at 180 ° C for 2 minutes, and then heated to 600 ° C at a heating rate of 10 ⁇ / min to obtain a thermogravimetric curve as shown in FIG. 2 .
  • the DSC curve of the sample is in the temperature range of 148-195 ° C, 279
  • Example 1 shows that the pellet obtained in Example 1 can achieve a stable molten state in a wide temperature range of 148-195 Torr, which is much lower than its own decomposition temperature, and can be in this wide temperature range.
  • the pellets are subjected to thermoplastic processing.
  • Table 2 the sheet-like molded article obtained by melting and extruding the pellet of Example 1 had excellent impact strength and tensile yield strength, and was completely in conformity with the requirements of the sheet-formed product.
  • the material provided by the present invention is completely different from a simple mixture containing polyvinyl alcohol, starch and a plasticizer, and is a completely new thermoplastic material which has a melting temperature much lower than its own decomposition temperature.
  • Example 14 shows that the pellet obtained in Example 1 can achieve a stable molten state in a wide temperature range of 148-195 Torr, which is much lower than its own decomposition temperature, and can be in this wide temperature range.
  • the pellets are subjected to thermoplastic processing.
  • Table 2 the sheet
  • This example is intended to illustrate the properties of articles made from the hydrophobic biodegradable materials of the present invention.
  • Figures 3 and 4 show scanning electron microscopy of the original starch used in Example 1 and the cross-section of the hydrophobic biodegradable material pellet BSR-07V-HS1 of Example 1 at 2000 magnification. photo.
  • the scanning electron micrograph was obtained by a scanning electron microscope (Japan Electronics Co., Ltd.) of the model JSM5600LV.
  • Figure 3 shows that the starch granules are spherical granules, while the presence of starch granules is no longer visible in Figure 4.
  • the material provided by the present invention is completely different from a simple mixture containing polyvinyl alcohol, starch and plasticizer and is a completely new material.
  • the data in Table 2 indicates that the mechanical properties of the article made of the hydrophobic biodegradable material provided by the present invention, such as the simply supported beam impact strength and the tensile yield strength, are significantly improved, and are superior to any single one of the materials.

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Description

一种疏水性可生物降解材料 技术领域
本发明是关于一种可生物降解材料，尤其是关于一种疏水性可生物降解 材料。 背景技术
CN 1405230A公开了一种水溶性、无污染且短期内即可完全生物降解的 塑料成型材料， 该材料含有聚乙烯醇、 丙三醇、 二縮二乙二醇、 山梨醇、 纤 维、 白炭黑、超细钙、改性淀粉。 CN 1405230A还公开了该材料的制备方法： 在聚乙烯醇原料中加入 1-30份的丙三醇， 在高温下搅拌， 使其充分润湿后 再加入适量的助增塑剂、交联剂、补强剂、 改性剂、填料等； 然后， 在 25-65 °C的温度下共混反应 5-50分钟， 再将所得物料加入到单螺杆或双螺杆挤出 机中进行造粒， 并且还教导上述物料可在 150-250°C的温度范围内吹膜、 发 泡成型。但是，当按照 CN 1405230A的方法，用该方法制备的材料在 160-190 °〇加热条件下进行热塑挤出时， 本发明的发明人发现， 该材料只有很少一部 分呈熔融状态， 在加热到 200 °C时， 该材料已经幵始碳化。 这说明， 该材料 不是一种热塑性材料， 不能实现在熔融状态下吹膜成型， 只能通过无需加热 熔融的流延法制备流延膜。
CN 1357563A公开了一种淀粉-聚乙烯醇-聚酯类三元体系生物降解膜的 制备方法，所述生物降解膜的原料按重量百分比含有： 30-65 %的淀粉、 15-40 %的聚乙烯醇、 0-10 %的聚酯类、 10-20 %的增塑剂、 0.4%的补强剂、 0.5-1.5%的湿强剂和 0.4%的消泡剂，其中增塑剂按重量比为乙二醇：甘油： 聚酯多元醇 = 1-3: 9-15： 3-6的三元复合体系及水， 该生物降解膜的制备方 法为先将聚乙烯醇与淀粉混合， 再将溶解有补强剂、湿强剂和消泡剂的水溶 液与上聚乙烯醇与淀粉的混合物混合，最后与增塑剂混合并搅拌均匀造粒挤 出。 与 CN 1405230A公开的材料一样， 用该方法制备的材料也不能形成熔 融状态，该材料也不是一种热塑性材料，也不能实现在熔融状态下吹膜成型， 只能通过无需加热熔融的流延法制备流延膜。
而众所周知， 流延膜在制备过程中不容易控制厚度， 制备出来的流延膜 一般厚度较大而且不均匀。 此外， 与热塑成型的吹塑薄膜相比， 流延膜的力 学性能如拉伸断裂强度、 断裂延伸率和直角撕裂强度比较差， 无法满足对薄 膜制品力学性能的一般要求。 再者， 流延膜的生产效率很低， 将流延膜制成 制品的方法和工序复杂， 例如， 用流延膜制作袋子时， 需要将一块流延膜对 折， 然后将对折后的流延膜的两个侧边热封在一起， 上述是造成其薄膜产品 成本很高的重要原因； 而吹塑成型时只需要将材料熔融吹膜即可得到膜制 品。 另外， 流延法只能生产薄膜类产品， 不能够生产注射类、 发泡类以及挤 出片材类的产品。 因此， 需要获得能够在加热熔融状态下加工成型如挤出成 型的含有聚乙烯醇的材料。 发明内容
本发明的目的是为了克服现有的含有聚乙烯醇的可生物降解材料可塑 性差、 不能用于制成片材类成型制品的缺点， 提供一种可塑性好、 能够用于 制成片材类成型制品的疏水性可生物降解材料及其制备方法。
为了能够使含有聚乙烯醇的疏水性可生物降解材料实现熔融状态，本发 明的发明人对聚乙烯醇进行了研究， 结果发现， 由于聚乙烯醇分子中存在大 量的羟基， 羟基与羟基之间形成较强的氢键作用， 使得聚乙烯醇分子间和分 子内有大量的氢键存在； 另外， 由于聚乙烯醇分子为柔性分子， 分子相互交 织在一起形成错综复杂的高阻隔性分子链结构， 并且这种聚合物分子之间的 相互作用力比一般化合物分子之间的范德华力大得多， 因此导致要想克服这 种作用力需要较高的熔融温度， 事实上， 聚乙烯醇的熔融温度高达 220-240 °C， 高于其分解温度（200°C左右）。 聚乙烯醇的熔融温度高于其分解温度使 得聚乙烯醇一般在熔融之前就开始分解碳化了，聚乙烯醇几乎不可能达到稳 定的熔融状态。 而聚乙烯醇必须在熔融状态下才能与淀粉等组分反应， 生成 具有稳定的熔融状态的可生物降解材料， 因此， 正是由于上述工艺条件下的 聚乙烯醇未能破坏原有的氢键作用而不可能达到稳定的熔融状态，才使得现 有的含有聚乙烯醇的可生物降解材料不能实现熔融状态及其热塑加工。
据本发明的发明人推测， 虽然 CN 1405230A公开的方法使用增塑剂丙 三醇对聚乙烯醇进行增塑，但增塑剂丙三醇不能破坏聚乙烯醇分子之间的交 织作用， 无法进入到聚乙烯醇分子中， 增塑剂与聚乙烯醇之间的混合只是一 种简单的物理共混， 混合物中聚乙烯醇仍然是原始状态的聚乙烯醇， 增塑剂 无法真正对聚乙烯醇起到增塑和改性的作用， 因而不能降低聚乙烯醇的熔融 温度， 仍然不能实现聚乙烯醇的熔融状态， 聚乙烯醇与增塑剂和淀粉等的混 合物同样也不能实现熔融状态。
CN 1357563A公开的制备方法为先将聚乙烯醇与淀粉混合，再加入溶解 有补强剂、 湿强剂和消泡剂的水溶液， 聚乙烯醇在常温下为絮状、 颗粒状或 粉状， 由于淀粉的吸水性远大于聚乙烯醇的吸水性， 因而所加入的水溶液中 的大部分水迅速被淀粉吸收， 只有非常少部分的水分被聚乙烯醇吸收， 绝大 部分聚乙烯醇仍为原始物理状态。 由于吸收水分后的淀粉膨胀胶化而将聚乙 烯醇包覆在淀粉内， 阻止了聚乙烯醇与水分的接触， 因而即便加入再大量的 水也无法与聚乙烯醇接触， 绝大部分聚乙烯醇仍然为原始状态的聚乙烯醇， 这样的聚乙烯醇仍然不能达到熔融状态。而且加入的增塑剂仍然不能进入聚 乙烯醇中对其进行增塑， 只能被淀粉吸收， 因而上述混合物是含水的淀粉与 聚乙烯醇、 增塑剂及助剂等组分的简单混合物， 仍然不能实现熔融状态。
而本领域技术人员公知的是，现有技术中的造粒及其后续的挤出成型等 工艺均是在单螺杆或双螺杆挤出机中将混合物加热熔融使其处于具有一定 的流动性的熔融状态下进行的，只有这样的熔融状态的物料才能在单螺杆或 双螺杆挤出机中挤出造粒以及在后续工艺中挤出成型。但是， 现有的含聚乙 烯醇的材料， 如 CN 1405230A和 CN 1357563A中公开的材料都是一种简单 的混合物， 由于聚乙烯醇实质上并没有被增塑， 绝大部分聚乙烯醇以其原始 的状态存在， 在对这些简单的混合物进行加热时， 如果加热温度高于聚乙烯 醇熔融温度， 至少部分聚乙烯醇未经熔融就已经分解碳化了， 而如果温度低 于熔融温度， 聚乙烯醇不能熔融， 也就不能使其在熔融态下与增塑剂和淀粉 实现真正意义上的混合并反应， 形成具有稳定的熔融状态的反应产物， 也就 根本无法实现吹塑成型、 挤出成型或注射成型。
一般情况下，水是热塑性材料尤其是疏水性热塑性材料加工过程中的大 忌， 因为自由状态的水与热塑性材料之间没有相容性， 因而会使热塑性材料 在加工过程中出现大量的气泡甚至破裂， 从而严重影响制品外观质量和物理 性能。 因此在热塑性材料的制备过程中， 需要严格控制原料中水的含量及加 工过程中水的存在量。
本发明的发明人意外地发现，先将水与疏水性聚乙烯醇在 45Ό以上进行 混合， 待聚乙烯醇被水充分溶胀形成含水的聚乙烯醇后， 再加入多元醇和淀 粉并混合均匀后得到的混合物可以在挤出机中在熔融状态下挤出造粒，得到 疏水性可生物降解材料粒料， 该粒料可以达到稳定的熔融温度， 并且其熔融 温度明显低于其分解温度。 该粒料的熔融温度为 130-210°C， 分解温度为 260-420 °C , 热塑性加工性能非常好， 可以用于挤出成型制成片材类成型制 品。这可能是因为， 水的分子量很小， 将水与疏水性聚乙烯醇在 45°C以上单 独接触时，水很容易进入到聚乙烯醇分子结构内部，打开聚乙烯醇的分子链， 使原本交织在一起的聚乙烯醇分子链充分舒展，使增塑剂更容易进入到聚乙 烯醇中， 共同对聚乙烯醇起到增塑和改性作用， 充分增塑并改性后的聚乙烯 醇可以形成稳定的熔融状态，在熔融条件下与淀粉和增塑剂反应得到反应产 物。 该反应产物不仅具有稳定的 130-210°C的熔融温度， 而且该熔融温度明 显低于其分解温度 260-420°C。 该材料的上述性质决定了该材料是一种全新 的热塑性材料， 使可生物降解材料热塑成型成为可能。
本发明提供了一种疏水性可生物降解材料， 其中， 该材料是由一种混合 物经熔融而形成的产物， 所述混合物含有多元醇和含水的聚乙烯醇， 含或不 含淀粉， 所述聚乙烯醇为疏水性聚乙烯醇， 以混合物的总重量为基准， 所述 多元醇的含量为 15重量％至小于 25重量％。
由于本发明提供的材料中不含有任何在自然环境条件下难以生物降解 的合成树脂， 因此本发明提供的材料及其制品可完全生物降解（ISO 14855， 99天高达 90%以上）。 最重要的是， 由于本发明提供的疏水性可生物降解材 料是一种混合物经熔融形成的产物， 材料的熔融温度为 130-210°C， 分解温 度为 260-420°C， 熔融温度远低于分解温度， 因而具有熔融状态， 具有普通' 聚乙烯醇、淀粉及多元醇之间简单物理混合得到的混合物材料无可比拟的热 塑加工性， 能够实现真正意义上的熔融挤出造粒和挤出成型。
本发明提供的疏水性可生物降解材料可以通过挤出成型得到片材类成 型制品， 制得的制品具有很好的简支梁冲击强度和拉伸屈服强度， 生物降解 率极高， 45 天的生物降解率大于 60% , 60天的生物降解率大于 70% , 99 天的生物降解率大于 90%， 完全符合 ISO 14855对可生物降解制品的要求 ( 180天内生物分解率大于 90% )。 由于聚乙烯醇为疏水性聚乙烯醇， 使得 由此制得的片材类成型制品具有优良的耐水性，在水中浸泡 1小时以上制品 的形状和力学性能均不发生变化。 另外， 在该疏水性可生物降解材料的制备 过程中加入有机羧酸，可以避免由所述材料制得的制品表面渗出油状小液珠 的现象以及制品之间出现粘连的现象， 进一步提高制品的使用性。
附图说明 图 1 为本发明实施例 1 制备的疏水性可生物降解材料的差示扫描量热 (DSC) 曲线；
图 2为本发明实施例 1制备的疏水性可生物降解材料的热重曲线； 图 3为本发明实施例 1所使用的原淀粉的扫描电子显微照片；
图 4为本发明实施例 1制备的疏水性可生物降解材料的横截面的扫描电 子显微照片。 具体实施方式
本发明提供了一种疏水性可生物降解材料， 其中， 该材料是由一种混合 物经熔融而形成的产物， 所述混合物含有多元醇和含水的聚乙烯醇， 含或不 含淀粉， 所述聚乙烯醇为疏水性聚乙烯醇， 以混合物的总重量为基准， 多元 醇的含量为 15重量％至小于 25重量％。
以混合物的总重量为基准，所述混合物中含水的聚乙烯醇的含量为 5-80 重量 优选为 10-70重量 多元醇的含量为 15重量％至小于 25重量％， 优选为 15-24.9重量％; 淀粉的含量为 0-75重量％， 优选为 15-70重量％。
本发明提供的疏水性可生物降解材料的熔融温度为 130-210°C， 优选为 140-200 °C， 分解温度为 260-420 Ό , 优选为 270-410°C。 例如， 在实施例 1 中， 混合物中含有 15.0重量％的含水的聚乙烯醇、 60.0重量％的淀粉、 8.0 重量％的甘油、 10.0重量％的季戊四醇、 1.0重量％的羧甲基纤维素、 2.0重 量％的硬脂酸锌、 1.0重量％的？1©、 2.0重量％的环氧大豆油、 1.0重量％ 的抗氧剂 1010， 所得材料的熔融温度为 148-195°C， 分解温度为 279-385 °C。 混合物中各组分的含量不同， 所得材料的熔融温度和分解温度也略有不同。
在本发明所述含水的聚乙烯醇中， 聚乙烯醇与水的重量比优选为 1.5至 小于 5， 更优选为 1.5-4.9。 所述聚乙烯醇可以是现有技术中的各种疏水性聚 乙烯醇。本发明中，疏水性聚乙烯醇指只能溶于 45°C以上的水中的聚乙烯醇。 所述聚乙烯醇的化学式为 -(CH2CHOH)n -， 常温下为白色或微黄色絮状、 颗粒状或粉末状固体。 疏水性聚乙烯醇的醇解度为 80-100%， 优选为 85-95 %； 疏水性聚乙烯醇的中值聚合度为大于 2000至 3000， 优选为 2050-3000。 聚乙烯醇主要是由聚醋酸乙烯醇解得到的， 也就是将聚醋酸乙烯进行还原得 到的， 醇解度表示还原 （醇解） 的程度， 醇解度越高， 则表示聚醋酸乙烯还 原成聚乙烯醇的程度越高。
所述多元醇可以选自乙二醇、 二甘醇、 丙二醇、 甘油、 季戊四醇、 山梨 糖醇以及多元醇与长链脂肪酸的不完全酯化产物（如单硬脂酸甘油酯）中的 一种或几种， 优选为甘油、 山梨糖醇和季戊四醇中的一种或几种。 多元醇可 以起到对聚乙烯醇进行增塑的作用。所述多元醇可单独使用或者两种或两种 以上配合使用， 优选配合使用。
此外， 本发明中， 所述混合物还可以含有纤维素基聚合物， 该纤维素基 聚合物同样可以起到对聚乙烯醇进行增塑的增塑剂作用。所述纤维素基聚合 物选自羧甲基纤维素 （CMC)、 甲基纤维素、 乙基纤维素、 羟丙基甲基纤维 素 （HPMC)、 羟丙基乙基纤维素中的一种或几种。 以混合物的总量为基准， 纤维素基聚合物的含量可以为 0-10重量％， 优选为 2-6重量％。
所述淀粉可以是现有技术中的各种淀粉，例如可以使用天然淀粉或者改 性淀粉。 天然淀粉可以选自玉米淀粉、 马铃薯淀粉、 红薯淀粉、 木薯淀粉、 麦类淀粉和豆类淀粉中的一种或几种， 可以是支链淀粉和 /或直链淀粉。 所 述改性淀粉的例子包括氧化淀粉、 酯化淀粉和醚化淀粉。 所述酯化淀粉可以 选自淀粉磷酸酯、 淀粉硫酸酯、 淀粉硝酸酯、 淀粉醋酸酯、 淀粉丙酸酯中的 一种或几种。 所述醚化淀粉可以选自羧基淀粉、 氰基淀粉、 酰胺淀粉、 羟烷 基淀粉、 烷基淀粉、 芳基淀粉、 伯胺淀粉醚、 仲胺淀粉醚、 叔胺淀粉醚、 鑰 类淀粉醚、 氨腈淀粉中的一种或几种。
本发明中， 不含淀粉的所述混合物也具有稳定的熔融状态， 制得的材料 也能用于制备片材类成型制品， 但是， 由于聚乙烯醇的价格远高于淀粉尤其 是普通淀粉的价格， 淀粉的加入可以相应地降低混合物中聚乙烯醇的含量， 降低本发明材料的原料成本， 同时还能提高材料的生物降解性。但由于淀粉 是亲水性物质， 且淀粉的含量越高， 所得材料及其制品的力学性能也下降。 综合生物降解性、 力学性能和成本多方面因素考虑， 可以根据需要调节淀粉 的含量。 以混合物的总量为基准， 本发明所述混合物中含有 0-75 重量％的 淀粉， 优选含有 15-70重量％的淀粉。
为了进一歩提高本发明所述疏水性可生物降解材料的耐水性，所述混合 物中还可以含有聚酯。 所述聚酯可以是各种疏水性聚酯类化合物， 例如可以 选自酯基为支链的各种聚酯化合物，所述聚酯化合物可以是脂肪族聚酯化合 物或芳香族聚酯化合物或者它们的混合物，所述脂肪族聚酯化合物例如可以 是聚己内酯、 聚碳酸酯、 聚 β -羟基丁酸酯（ΡΗΒ) 中的一种或几种； 优选为 聚 β -羟基丁酸酯。以所述混合物的含量为基准，所述聚酯的含量可以为 0-20 重量％， 优选为 0.5-15重量％。
提高本发明疏水性可生物降解材料耐水性的另一个方法是将聚乙烯醇 等组分中的亲水性羟基进行封闭。可以采用现有技术中的各种方式进行羟基 封闭， 例如可以通过聚乙烯醇分子之间的交联缩合反应， 生成疏水性醚键来 封闭羟基， 同时分子之间的羟基縮合还能提高聚乙烯醇等组分的聚合度， 进 一步增大分子量， 使分子的疏水性得到进一步的提高。 也可以通过其它封端 剂使羟基生成其它疏水性基团而将羟基封闭。 因此， 本发明所述混合物中还 可以含有封端剂， 所述封端剂可以选自硼砂、 硼酸、 甲醛、 二醛、 三甲基三 聚氰胺、 二甲基脲、 二甲基乙基脲、 重铬酸盐、 硝酸铬、 有机钛酸盐中的一 种或几种。 二醛的例子包括但不限于乙二醛、 丙二醛、 丁二醛、 戊二醛及其 异构体、 己二醛及其异构体、 庚二醛及其异构体、 辛二醛及其异构体、 壬二 醛及其异构体、 癸二醛及其异构体。 以所述混合物的总量为基准， 所述封端 剂的含量可以为 0-15重量％， 优选为 0.5-15重量％。
此外， 本发明的发明人发现， 由含有上述组分的混合物制得的片材类成 型制品在温度大于 23°C、 相对湿度大于 60%的环境下会发生制品表面渗出 油状小液珠的现象，由于这种液珠具有粘性，导致制品之间容易粘连在一起， 给制品的使用带来不便。本发明的发明人发现， 通过在上述混合物中加入有 机羧酸， 即可有效避免上述问题。 因此， 优选情况下， 本发明所述混合物还 含有有机羧酸， 以混合物的总重量为基准， 有机羧酸的含量可以为 0.5-10重 量％， 优选为 2-7重量％。
所述有机羧酸可以为碳原子数为 1-20.的有机羧酸中的一种或几种， 优 选为碳原子数为 1-12 的有机羧酸中的一种或几种。 所述有机羧酸可以为一 元有机羧酸， 也可以为多元有机羧酸。所述有机羧酸的例子包括但不限于甲 酸、 乙酸、 丙酸、 丁酸及其异构体、 戊酸及其异构体、 己酸及其异构体、 庚 酸及其异构体、 辛酸及其异构体、 壬酸及其异构体、 癸酸及其异构体， 丙二 酸、 丁二酸及其异构体、 戊二酸及其异构体、 己二酸及其异构体、 庚二酸及 其异构体、 辛二酸及其异构体、 壬二酸及其异构体、 癸二酸及其异构体、 柠 檬酸、 酒石酸、 月桂酸、 苯甲酸。
本发明中， 所述混合物还可以选择性地含有盐类添加剂。所述盐类添加 剂可以选自烷基磺酸盐、 有机酸铁盐、 聚羟基丁酸盐、 硬脂酸盐、 碳酸钙、 碳酸氢钙、 轻质碳酸钙和贝壳粉中的一种或几种。 所述硬脂酸盐包括 Ca、 Mg、 Zn、 Ba、 Ce及 Fe的硬脂酸盐。 这类添加剂可以作为润滑剂降低材料 各组分之间、 以及材料与加工设备之间的摩擦力。 所述添加剂可单独使用或 两种以上配合使用， 优选为两种配合使用。 以混合物的总量为基准， 盐类添 加剂的含量为 0-5重量％， 优选为 0.2-2重量％。
本发明所述混合物中还可以根据需要加入常用的一些助剂，所述助剂包 括抗氧剂、 光 /热稳定剂、 光氧化剂、 防雾剂、 阻燃剂、 抗静电剂、 偶联剂、 消泡剂、 着色剂、 润滑剂中的一种或几种。 所述助剂的种类和用量已为本领 域技术人员所公知， 例如， 以混合物的总量为基准， 助剂的含量为 0-5重量 % , 优选为 0.3-4重量％。 例如， 为了防止和抑制淀粉在加工过程中或使用 过程中， 由于光、 热、 氧、 微生物或菌等因素引起过早降解， 可以加入抗氧 剂、 光 /热稳定剂。 抗氧剂可以选自四 （3-(3',5'-二叔丁基 -4'-羟基苯基）丙酸) 季戊四醇酯 (简称抗氧剂 1010)、硫代二丙酸二硬脂酸酯 (简称抗氧剂 DSTP)、 亚磷酸酯类、 复合抗氧剂 PKY、 双酚 Α中的一种或几种。 光 /热稳定剂可以 选自 UV-系列光 /热稳定剂、 炭黑、 有机锡类光 /热稳定剂、 亚磷酸三壬基苯 酯 （TNPP)、 环氧大豆油中的一种或几种。 其中， UV-系列光 /热稳定剂可以 是 α-羟基 -4-正辛氧基二苯甲酮 （简称 UV-531 )。 所述有机锡类光 /热稳定剂 可以选自二月桂酸二丁基锡、 二硫代乙醇异辛酯二甲酯基亚乙基锡（简称酯 基锡）、 酯基锡 RWS-784、 双 （硫代甘醇酸异辛酯） 二正辛基锡 （简称京锡' 8831 )、 二马来酸二丁基锡、 硫代甘醇异辛酯二丁基锡中的一种或几种。 所 述润滑剂可以为常规使用的各种润滑剂，如液体石蜡和 /或石油醚。润滑剂用 于降低粒料和制品与挤出机之间的摩擦， 有利于制品的脱模。上述各种助剂 可以单独使用， 也可以两种或两种以上配合使用。
本发明提供的疏水性可生物降解材料可以通过将含有多元醇、含水的聚 乙烯醇、含或不含的淀粉的混合物加热熔融，然后将所得熔融物反应、挤出、 造粒而制得。
所述含水的聚乙烯醇可以通过将水与聚乙烯醇接触而得到，接触的条件 以及聚乙烯醇和水的用量足以使聚乙烯醇充分溶胀。聚乙烯醇充分溶胀是指 溶胀的聚乙烯醇即含水的聚乙烯醇中聚乙烯醇与水的重量比为 1.5至小于 5， 优选为 1.5-4.9。
将水与聚乙烯醇接触的原因是水的分子量小，将水与聚乙烯醇单独接触 时， 水非常容易进入到聚乙烯醇分子结构内部， 破坏聚乙烯醇分子间和分子 内的氢键， 将错综复杂交织在一起的聚乙烯醇分子链最大程度地展开， 为多 元醇类增塑剂最大程度地进入到聚乙烯醇分子结构内部奠定了基础，从而最 终降低聚乙烯醇熔融温度， 使含有聚乙烯醇的混合物能够实现熔融状态。 为 了使聚乙烯醇充分溶胀， 优选聚乙烯醇与水的用量重量比为 1-3， 优选为 1-2.5。
所述接触的条件只要满足能够使聚乙烯醇充分溶胀即可。 例如， 可以使 水与聚乙烯醇在静置状态下接触足够长的时间， 直至聚乙烯醇被充分溶胀， 采用这种方式虽然可以使聚乙烯醇充分溶胀， 但是需要的接触时间会比较 长， 生产效率比较低， 因此， 为了使聚乙烯醇在较短的时间内即可充分溶胀 从而提高生产效率，所述接触的条件优选包括所述聚乙烯醇与水在搅拌下接 触， 搅拌速度可以为 50-650转 /分钟， 接触时间可以为 30-60分钟。 由于本 发明中聚乙烯醇为疏水性聚乙烯醇， 这种聚乙烯醇几乎不溶于 45 °C ( 1个大' 气压） 以下的水中， 因而所述聚乙烯醇与水的接触温度优选为 80-105°C ( 1 个大气压）。 由于将 PVA直接加入热水中会出现包团和皮溶内生现象， 因而 优选将低于 60°C的温水加入到 PVA 中， 搅拌下再逐渐将体系温度升高到 80-105。C。
由于在上述温度下， 以及由于水与聚乙烯醇的混合物粘度较大， 搅拌的 阻力较大， 因而搅拌过程中会产生大量的热， 使加入的部分水蒸发掉， 并且 搅拌时间越长， 产生的热量也越高， 蒸发掉的水也越多； 搅拌速度越快， 产 生的热量也越高， 蒸发掉的水也越多， 因此在上述聚乙烯醇与水的用量重量 比和接触条件下，得到的含水的聚乙烯醇中聚乙烯醇与水的重量比略大于聚 乙烯醇与水的用量重量比，而且当搅拌速度较快和 /或搅拌时间较长时，可以 适当地增加水的用量， 以使含水的聚乙烯醇中聚乙烯醇与水的重量比在 1.5 至小于 5的范围内。
所述含有多元醇和含水的聚乙烯醇、含或不含淀粉的混合物可以通过将 上述得到的含水的聚乙烯醇、 多元醇和选择性含有的淀粉混合均匀而得到。 在将含水的聚乙烯醇、 多元醇和选择性含有的淀粉混合时， 还优选加入 聚酯、 封端剂和有机羧酸中的一种或几种并混合均匀。
在将含水的聚乙烯醇、 多元醇和选择性含有的淀粉混合时， 还可以加入 纤维素基聚合物、 盐类添加剂和助剂中的一种或几种并混合均匀。
所述混合优选在搅拌下进行， 搅拌的速度可以为 50-650转 /分钟。
该混合物中各种成分的混合顺序可以是任意的， 例如， 可以将含水的聚 乙烯醇与选择性含有的淀粉先混合均匀后再加入多元醇并混合均匀；可以将 选择性含有的淀粉与多元醇混合均匀后再加入含水的聚乙烯醇并混合均匀； 可以将含水的聚乙烯醇与多元醇先混合均匀后再加入选择性含有的淀粉并 混合均匀； 也可以将含水的聚乙烯醇、 多元醇、 选择性含有的淀粉一起混合 均匀。优选情况下，为了使多元醇更好地起到对含水的聚乙烯醇的增塑作用， 先将含水的聚乙烯醇与多元醇混合均匀后再加入选择性含有的淀粉并混合 均匀。
以混合物的总重量为基准， 含水的聚乙烯醇的加入量为 5-80重量％， 优选为 10-70重量％; 多元醇的加入量为 15重量％至小于 25重量％， 优选 为 15-24.9重量％; 淀粉的加入量为 0-75重量％， 优选为 15-70重量％; 聚 酯的加入量可以为 0-20重量％， 优选为 0.5-15重量％; 封端剂的加入量可 以为 0-15重量％， 优选为 0.5-15重量％; 有机羧酸的加入量可以为 0-10重 量％， 优选为 0.5-10重量％; 纤维素基聚合物的加入量可以为 0-10重量％， 盐类添加剂的加入量可以为 0-5重量％， 助剂的加入量可以为 0-5重量％。
将该混合物加热熔融， 然后将所得熔融物挤出造粒的方法、 条件己为本 领域技术人员所公知。例如， 可以釆用双螺杆挤出机在下述条件下将所得熔 融物挤出造粒，双螺杆挤出机的长径比为 20-64， 螺杆转速 50-1500转 /分钟。 所述双螺杆挤出机从进料端到出料端一般分为 12个区段， 从进料端到出料 端， 各区段温度分别依次设定为 90-150°C、 95-155°C、 100-160°C、 115-165 °C、 120-175°C 125-175°C、 130-185°C、 135-185°C、 110-180°C、 115-75°C、 120-185 °C , 130-180°C , 第 4和 10个区段为真空段， 真空度为 0.02-0.09兆 帕。 本发明中， 所述真空度是指绝对压力与大气压力的差值的绝对值（绝对 压力小于大气压力）。 双螺杆挤出机的双螺杆相互啮合， 当螺杆的转速较高 时如大于等于 500转 /分钟，相互啮合的双螺杆对加入到双螺杆挤.出机中的物 料有很强的摩擦和剪切作用，摩擦和剪切作用产生的热量使物料的实际温度 高于上述各区段的设定温度。
用于制备本发明提供的材料的方法的具体步骤如下：
( 1 )将聚乙烯醇与水搅拌混合均匀并充分溶胀， 得到含水的聚乙烯醇， 之后加入多元醇以及选择性含有的淀粉、 聚酯、 封端剂、 有机羧酸、 纤维素 基聚合物、 盐类添加剂、 助剂中的一种或几种， 将上述物料混合均匀得到混 合物。 其中， 聚乙烯醇与水搅拌共混的时间为 30-60 分钟， 搅拌的速度为 50-650转 /分钟， 共混的温度为 80-105°C ; 含水的聚乙烯醇与淀粉、 多元醇 等物料的搅拌共混的时间可以是 5-25 分钟， 搅拌共混的转速为 50-250转 / 分钟， 优选先以低速搅拌再以高速搅拌；
(2) 将得到的混合物熔融、 挤出造粒。 其中， 所述造粒例如可以采用 双螺杆挤出机， 在长径比为 20-64， 螺杆转速 50-1200转 /分钟， 从进料端到 出料端分为 12个区段，各区段温度依次设定为 90-150°C、 95-155°C、 100-160 。C、 115-165°C、 120-175。C、 125-175°C、 130-185。C、 135-185°C、 110-180。C：、 115-175°C、 120-185°C、 130-180°C , 第 4和 10个区段为真空段， 真空段的 真空度为 0.02-0.09兆帕的条件下将上述得到的混合物熔融挤出造粒。
本发明的疏水性可生物降解材料可用于制备片材类成型制品。 由疏水性 可降解材料制备片材类成型制品的方法可以釆用例如，先将该混合物经双螺 杆挤出机挤出造粒得到粒料， 然后将粒料投入到单螺杆挤出机中， 自喂料口 至挤出段顺序， 按照 140。C、 150°C、 160。C、 170°C、 175。C、 170°C分别设定 挤出机各段的温度， T型模头的温度分别为 185°C、 175°C、 185°C， 使熔融 的物料经过 T型模头挤出后， 经过三辊压延、收卷成为片材半成品； 然后使 用这种片材， 按照 160-185 °C的温度条件， 在成型机及其模具内成型， 最终 制成片材类成型制品。
以下通过实施例对本发明作进一步的说明。但应该理解的是， 这些实施 例并不构成对本发明保护范围的限制。 实施例 1
本实施例用于说明本发明提供的疏水性可生物降解材料及其制备方法。
( 1 )在 100转 /分钟的搅拌条件下将 25.0重量份 60Ό的纯净水加入到 37.5重量份的醇解度为 95 %、 中值聚合度为 2250的聚乙烯醇中将体系加热 并维持在 100°C左右下，并搅拌 50分钟得到含水的聚乙烯醇，其中聚乙烯醇 与水的重量比为 1.8: 1。 待体系降温至室温后再将 8.0重量份的甘油和 10.0 重量份季戊四醇加入到 15.0重量份上述得到的含水的聚乙烯醇中， 以 80转 / 分钟的速度下搅拌混合均匀后再将 60.0重量份 （干基重）数均分子量为 20 万的普通马铃薯淀粉加入到上述混合物中搅拌均匀， 然后再将 1.0重量份的 羧甲基纤维素、 2.0重量份的硬脂酸锌、 1.0重量份的 PHB、 2.0重量份的环 氧大豆油、 1.0重量份的抗氧剂 1010加入到上述混合物中搅拌均匀， 搅拌机 先以 100转 /分钟低速混合约 6分钟，然后再以 200转 /分钟高速混合 8分钟， 得到混合物 Ml， Ml的组成如下表 1所示；
(2)将上述搅拌均匀的混合物送入双螺杆挤出机的进料口中， 挤出机 的长径比 L:D=50:1，螺杆直径为 Φ72毫米。调整螺杆的转速至 900转 /分钟， 从进料端到出料端， 各区段温度分别设定为 130°C、 135°C、 140°C、 150 , 160°C、 165°C、 165°C、 170°C、 175°C、 170°C、 180°C和 170°C ; 真空段的真 空度保持为 0.02-0.09兆帕； 在挤出机的出料口得到直径为 3毫米的条状挤 出物， 将条状挤出物切粒， 得到长度为 2毫米的用于制备片材类成型制品的 疏水性可生物降解材料粒料产品 BSR-07V-HS1。 对比例 1
该对比例用于说明现有的含聚乙烯醇的可生物降解材料及其制备方法。
( 1 )将 13.0重量份聚乙烯醇（醇解度为 95 % , 中值聚合度为 2250)与 60.0重量份淀粉混合均匀， 然后与 7.0重量份水、 8.0重量份的甘油、 10.0 重量份的季戊四醇、 1.0重量份的羧甲基纤维素、 2.0重量份的硬脂酸锌、 1,0 重量份的 PHB、 2.0重量份的环氧大豆油、 1.0重量份的抗氧剂 1010—起加 入到搅拌机中混合， 搅拌机先以 100转 /分钟低速搅拌约 Ί分钟， 然后再以 200转 /分钟高速搅拌 8分钟， 得到混合物 CM1；
(2)按照实施例 1步骤（2)所述的方法将上述混合物 CM1挤出造粒， 结果得到没有任何可塑性的粉末状碳化物。这可能是因为双螺杆挤出机的双 螺杆相互啮合，螺杆的转速高达 900转 /分钟，相互啮合的双螺杆对加入到双' 螺杆挤出机中的物料有强烈的摩擦和剪切作用，而聚乙烯醇为未增塑的聚乙 烯醇， 在聚乙烯醇融化并与其它组分反应前， 强烈的摩擦和剪切作用产生的 热量就使温度达到聚乙烯醇分解温度，聚乙烯醇碳化造成了聚乙烯醇与其它 组分不能反应生成具有稳定熔融状态的反应产物， 因此生成了没有任何可塑 性的粉末状碳化物。 实施例 2
本实施例用于说明本发明提供的疏水性可生物降解材料及其制备方法。
( 1 ) 在 550转 /分钟的搅拌条件下将 35重量份 50°C的纯净水加入到 42 重量份醇解度为 95 %、 中值聚合度为 2450的聚乙烯醇中， 将体系加热并维 持在 95°C， 并搅拌 40分钟得到含水的聚乙烯醇， 其中聚乙烯醇与水的重量 比为 2: 1。 待体系降温至 35°C左右后再将 10.0重量份的山梨糖醇和 5.0重 量份的甘油加入到 25.0重量份上述得到的含水的聚乙烯醇中，在 80转 /分钟 的速度下搅拌混合均匀后再将 50.0重量份 （干基重） 数均分子量为 15万的 普通小麦淀粉加入到上述混合物中搅拌均匀， 然后再将 3.0重量份的羧甲基 纤维素、 3.0重量份的硬脂酸锌、 0.5重量份的环氧大豆油、 1.0重量份液体 石蜡、 0.5重暈份的抗氧剂 DSTP、 1.0重量份的硼砂、 1.0重量份的甲醛加入 到上述混合物中搅拌均匀，搅拌机先以 100转 /分钟低速混合约 5分钟，然后 再以 200转 /分钟高速混合 8分钟， 得到混合物 M2， M2的组成如下表 1所 示；
(2) 按照实施例 1步骤（2) 所述的方法将上述混合物 M2在熔融状态 下挤出造粒，得到用于制备片材类成型制品的疏水性可生物降解材料的粒料 产品 BSR-07V-HS2。 实施例 3
本实施例用于说明本发明提供的疏水性可生物降解材料及其制备方法。
( 1 ) 在 500转 /分钟的搅拌条件下将 32.0重量份 40°C的纯净水加入到 90.0重量份的醇解度为 90%、 中值聚合度为 2050的聚乙烯醇中， 将体系加 热并维持在 98°C， 并搅拌 55分钟得到含水的聚乙烯醇， 其中聚乙烯醇与水 的重量比为 4.5: 1。待体系降温至 30°C左右后，再将 8.0重量份的山梨糖醇、 8.0重量份的甘油和 8.0重量份的季戊四醇加入到 76.0重量份上述得到的含 水的聚乙烯醇中，以 50转 /分钟的速度搅拌混合均勾并在室温放置 24小时得 到混合物 M3， M3的组成如下表 1所示；
(2)按照实施例 1歩骤 （2)所述的方法将上述混合物 M3在熔融状态 下挤出造粒，得到用于制备片材类成型制品的疏水性可生物降解材料的粒料 产品 BSR-07V-HS3 实施例 4
本实施例用于说明本发明提供的疏水性可生物降解材料及其制备方法。
( 1 )在 600转 /分钟的搅拌条件下将 30.0重量份 45°C的纯净水加入到
60.0重量份的醇解度为 85 %、 中值聚合度为 2450的聚乙烯醇中将体系加热 并维持在 98Ό， 并搅拌 35分钟得到含水的聚乙烯醇， 其中聚乙烯醇与水的 重量比为 3.0: 1。 待体系温度降至 40Ό后再将 5.0重量份的山梨糖醇、 10.0 重量份的甘油和 5.0重量份季戊四醇加入到 40.0重量份上述得到的含水的聚 乙烯醇中搅拌均匀， 再加入 30.0重量份（干基重） 数均分子量为 15万的羧, 甲基淀粉、 3.0重量份的羧甲基纤维素、 2.0重量份的硬脂酸锌、 2.0重量份 的硬脂酸钙、 1.0重量份的液体石蜡、 1.5重量份的环氧大豆油、 0.5重量份 的抗氧剂 DSTP, 搅拌机先以 100转 /分钟低速混合约 8分钟， 然后再以 200 转 /分钟高速混合 10分钟， 得到混合物 Μ4， Μ4的组成如下表 1所示；
(2)按照实施例 1步骤（2)所述的方法将上述混合物 Μ4在熔融状态 下挤出造粒，得到用于制备片材类成型制品的疏水性可生物降解材料的粒料 产品 BSR-07V-HS4。 实施例 5
本实施例用于说明本发明提供的疏水性可生物降解材料及其制备方法。
( 1 )在 100转 /分钟的搅拌条件下将 30.0重量份 60 °C的纯净水加入到 37.5重量份的醇解度为 95 %、 中值聚合度为 2250的聚乙烯醇中将体系加热 并维持在 10CTC左右下，并搅拌 50分钟得到含水的聚乙烯醇，其中聚乙烯醇 与水的重量比为 1.8: 1。 待体系降温至室温后再将 8.0重量份的甘油和 10.0 重量份季戊四醇与 15.0重量份上述得到的含水的聚乙烯醇中， 以 80转 /分钟 的速度下搅拌混合均匀后再将 60.0重量份 （干基重）数均分子量为 20万的 普通马铃薯淀粉加入到上述混合物中搅拌均匀， 然后再将 1.0重量份的羧甲 基纤维素、 1.0重量份的硬脂酸锌、 1.0重量份的硬脂酸钙、 1.0重量份的环 氧大豆油、 2.0重量份的乙酸、 1.0重量份的抗氧剂 1010加入到上述混合物 中搅拌均匀， 搅拌机先以 100转 /分钟低速混合约 6分钟， 然后再以 200转 / 分钟高速混合 8分钟， 得到混合物 M5， M5的组成如表 1所示；
(2)按照实施例 1步骤 （2)所述的方法将上述混合物 M5在熔融状态 下挤出造粒，得到用于制备片材类成型制品的疏水性可生物降解材料的粒料 产品 BSR-07V-HS5。 实施例 6
本实施例用于说明本发明提供的疏水性可生物降解材料及其制备方法。
( 1 )在 100转 /分钟的搅拌条件下将 25.0重量份 60°C的纯净水加入到 37.5重量份的醇解度为 95%、 中值聚合度为 2250.的聚乙烯醇中将体系加热 并维持在 100°C左右下，并搅拌 50分钟得到含水的聚乙烯醇，其中聚乙烯醇 与水的重量比为 1.8: 1。待体系降温至室温后再将 60.0重量份（干基重）数 均分子量为 20万的普通马铃薯淀粉加入到 15.0重量份上述得到的含水的聚 乙烯醇中， 以 80转 /分钟的速度下搅拌混合均匀后再将 8.0重量份的甘油和 10.0重量份季戊四醇加入到上述混合物中搅拌均匀， 然后再将 1.0重量份的 PHB、 1.0重量份的硬脂酸锌、 1.0重量份的硼砂、 1.0重量份的环氧大豆油、 2.0重量份的乙酸、 1.0重量份的丁二酸加入到上述混合物中搅拌均匀， 搅拌 机先以 100转 /分钟低速混合约 6分钟， 然后再以 200转 /分钟高速混合 8分 钟， 得到混合物 M6， M6的组成如表 1所示；
(2)按照实施例 1步骤 (2)所述的方法将上述混合物 M6在熔融状态 下挤出造粒，得到用于制备片材类成型制品的疏水性可生物降解材料的粒料 产品 BSR-07V-HS6。
表 1
Figure imgf000021_0001
实施例 7-12
下面的实施例说明本发明提供的疏水性可生物降解材料的性能。
将上述粒料产品 BSR-07V-HS1至 BSR-07V-HS6加入到广东汕头金盟包 装机械厂制造的 Φ90型挤出机的进料口中，从进料端到出料端分为 6个区段， 各区段温度依次设定为 140 °C、 150°C、 160°C、 170° (：、 175°C、 170°C， T型 模头的温度分别设定为 185°C、 175°C、 185 , 使熔融的物料经过 T型模头 挤出后， 经过三辊压延、 收卷成为片材半成品； 然后在 160-185°C的温度条 件下在成型机及其模具内将上述片材半成品成型，最终得到尺寸为 680毫米 (宽) χθ.8毫米 (厚) xlOO千克 /卷的片材类成型制品 HS1-HS6。
釆用如下标准方法对上述制品进行各项性能测试，测试结果如下表 2所 示：
用 GB/T1043-93 硬质塑料简支梁冲击试验方法测定制品的简支梁冲击 强度；
用 GB/T1040测定制品的拉伸屈服强度；
按照 IS014855-99中规定的方法测定上述制品的生物降解率。
按照 GB/T5009.60-1996、 GB/T5009.60-1996 中规定的方法评价制品的 外观；
耐水性测试方法： （1 ) 在 1个大气压、 25°C下， 将上述制品 HS1-HS6 裁切成尺寸为 100毫米（长） X 100毫米（宽） X 0.8毫米（厚）的标准样品 后完全浸泡在 5倍重量的水中 1小时，擦去表面水分后观察制品的外观变化， 并测试浸泡后的制品的拉伸屈服强度、 简支梁冲击强度、 断裂延伸率。 发现 浸泡前后制品的外观并无明显变化， 其它测试结果如表 2所示。
(2)将上述制品 HS1-HS6裁切成尺寸为 100毫米（长） X 100毫米（宽) X 0.8毫米（厚） 的标准样品， 将标准样品在温度为 30°C、 相对湿度为 70% 的环境中放置 30天， 观察各个样品的外观变化并测试其拉伸屈服强度和简 支梁冲击强度。 发现放置前后制品的外观并无明显变化， 其它测试结果如表 2所示。
制品表面粘性的测试:将上述制品 HS1-HS6分别裁切出 20块尺寸为 100 毫米 （长） X 100毫米 （宽） X 0.8毫米 （厚） 的样品， 将该 20块样品分成 10组（每组两块）， 将每组的两块样品叠放在一起， 接触面为 100毫米（长) X 100毫米（宽）表面， 然后在温度为 30°C、相对湿度为 70%的环境中放置 48小时后以 1000帕的压力以垂直于接触面的方向按压叠放在一起的每组样 品， 然后观察每组样品之间是否粘在一起， 并记录粘在一起的样品的组数， 同时观察样品的各个表面上是否有油状小液珠现象出现，将结果记录在下表
2中。
下表 2中， A表示通常条件下， B表示在 5倍重量水中浸泡 1小时后， C表示在 70%湿度下放置 30天后的测试结果。
表 2
Figure imgf000023_0001
从表 2所示的结果可以看出， 由实施例 1-6的疏水性可生物降解材料粒 料 BSR-07V-HS1至 BSR-07V-HS6制成的制品 HS1-HS6具有很好的简支梁 强度和拉伸屈服强度； 生物降解率极高， 45天的生物降解率大于 60%， 60 天的生物降解率大于 70%， 99天的生物降解率大于 90%， 完全符合 ISO 14855对可生物降解制品的要求（180天内生物分解率大于 90% )。由于所述 材料为疏水性材料，制品在水中浸泡 1小时或者在温度为 30°C、相对湿度为 70%的环境中放置 30天后外观没有变化， 简支梁强度和拉伸屈服强度的变 化很小， 说明制品的耐水性很好。 实施例 1、 2和 6在制备疏水性可生物降 解材料时加入了聚酯和 /或封端剂，实施例 3-5在制备疏水性可生物降解材料 时没有使用聚酯或封端剂， 因此， 与由 BSR-07-HS3至 BSR-07-HS5制得的 制品相比， 由 BSR-07-HSl、 BSR-07-HS2和 BSR-07V-HS6制得的制品在水 中浸泡 1小时或者在 70%湿度下放置 30天后简支梁强度和拉伸屈服强度的 变化更小， 耐水性更好。
实施例 5 和 6 在制备疏水性可生物降解材料 BSR-07V- HS5 和 BSR-07V-HS6时加入了有机羧酸，由 BSR-07V-HS5和 BSR-07V-HS6制得的 制品 HS5和 HS6没有出现表面粘连的现象， 因此， 与由实施例 1-4的疏水 性可生物降解材料粒料 BSR-07V-HS1至 BSR-07V-HS4制成的制品 HS1-HS4 相比， 由 BSR-07V-HS5和 BSR-07V-HS6制得的制品 HS5和 HS6的表面粘 性显著降低，在放置和使用过程中不会出现制品表面渗出油状小液珠和表面 粘连的问题。 实施例 13
该实施例用于说明本发明实施例 1提供的疏水性可生物降解材料的熔融 和热分解性质。
通过下面的方法测定实施例 1 制得的疏水性可生物降解材料粒料产品 BSR-07V-HS1的熔融和热分解性质。
准确称取约 4.7 毫克实施例 1 制得的疏水性可生物降解材料粒料
BSR-07V-HS1 ,置于 ETZSCH DSC 204F1型示差扫描量热分析仪的样品池 中， 在流速为 60毫升 /分钟的氮气保护下， 以 10°C/分钟的升温速率将样品 由 25°C加热至 180°C，在 180Ό下保持 2分钟，然后以 10Ό/分钟的升温速率 继续加热至 300°C， 得到的如图 1所示的 DSC曲线。
准确称取约 4.7 毫克实施例 1 制得的疏水性可生物降解材料粒料 BSR-07V-HS1 , 置于型号为 TG209F1 的热重分析仪 （德国耐驰仪器制造有 限公司） 的样品池中， 在流速为 60毫升 /分钟的氮气保护下， 以 10°C/分钟 的升温速率将样品由 25°C加热至 180°C， 在 180°C下保持 2分钟， 然后以 10 Ό/分钟的升温速率继续加热至 600°C， 得如图 2所示的热重曲线。
从图 1可以看出， 样品的 DSC曲线上在 148-195°C的温度范围内、 279
°C附近有一个吸热峰； 从图 2可以看出， 在 279-385°C的温度范围内， 样品 快速失重， 而在 148-195°C的温度范围内样品的重量基本上没有损失。 结合 图 1和图 2的结果表明，样品的 DSC曲线中的在 148-195Ό的吸热峰为样品 熔融吸热造成的吸热峰，在 279°C附近的吸热峰由于伴随着样品的快速失重， 说明样品在此温度下分解， 因此， 该吸热峰为样品分解造成的吸热峰。.这说 明实施例 1得到的粒料在 148-195Ό的较宽的温度范围内可以实现稳定的熔 融状态， 该熔融温度大大低于其自身的分解温度， 可以在该较宽的温度范围 内对粒料进行热塑加工。 如表 2所示， 由实施例 1的粒料熔融、 挤出成型得 到的片材类成型制品的简支梁冲击强度、 拉伸屈服强度非常优异， 完全符合 片材类成型制品的要求。这进一步说明本发明提供的材料完全不同于含有聚 乙烯醇、 淀粉和增塑剂的简单混合物， 是一种全新的热塑性材料， 该材料的 熔融温度大大低于其本身的分解温度。 实施例 14
该实施例用于说明由本发明的疏水性可生物降解材料制得的制品的性 质。
图 3和图 4分别给出了实施例 1中所使用的原淀粉和由实施例 1的疏水 性可生物降解材料粒料 BSR-07V-HS1横截面的放大倍数为 2000倍的扫描电 子显微照片。 该扫描电子显微照片采用型号为 JSM5600LV的扫描电子显微 镜 （日本电子株式会社） 得到。 在图 3中可以清晰地看到淀粉颗粒为球形颗粒，而在图 4中已经看不到 淀粉颗粒的存在。这说明在实施例 1制备所述粒料的过程中， 在双螺杆挤出 机的双螺杆的剪切作用下， 淀粉颗粒被充分细化， 而且淀粉与其它组分之间 不仅仅是发生了简单的物理混合， 而是形成了一种单一的均匀的产物。 这进 一步说明本发明提供的材料完全不同于含有聚乙烯醇、淀粉和增塑剂的简单 混合物， 是一种全新的材料。
此外， 表 2中的数据表明， 本发明提供的疏水性可生物降解材料制成的 制品的力学性能如简支梁冲击强度和拉伸屈服强度显著提高，优于由所述材 料中的任意单一组分制成的制品。这也说明本发明提供的材料是一种完全不 同于现有简单混合物的全新的反应产物。

Claims

权利要求书
1、 一种疏水性可生物降解材料， 其特征在于， 该材料是由一种混合物 经熔融而形成的产物， 所述混合物含有多元醇和含水的聚乙烯醇、含或不含 淀粉， 所述聚乙烯醇为疏水性聚乙烯醇， 以混合物的总重量为基准， 所述多 元醇的含量为 15重量％至小于 25重量％。
2、 根据权利要求 1 所述的材料， 其中， 该材料的熔融温度为 130-210 °C， 分解温度为 260-420 °C。 .
3、 根据权利要求 1所述的材料， 其中， 以混合物的总重量为基准， 所 述混合物中含水的聚乙烯醇的含量为 10-70重量％，多元醇的含量为 15-24.9 重量％， 淀粉的含量为 15-70重量％。
4、 根据权利要求 1或 3所述的材料， 其中， 所述含水的聚乙烯醇通过 将聚乙烯醇与水接触而得到，接触的条件及聚乙烯醇和水的用量足以使所述 含水的聚乙烯醇中聚乙烯醇与水的重量比为 1.5至小于 5。
5、 根据权利要求 4所述的材料， 其中， 聚乙烯醇和水的用量重量比为 1-3。
6、 根据权利要求 4所述的材料， 其中， 所述接触的条件包括所述聚乙 烯醇与水在搅拌下接触，接触的时间为 30-60分钟，接触的温度为 80-105 °C。
7、 根据权利要求 1所述的材料， 其中， 所述疏水性聚乙烯醇的中值聚 合度为大于 2000至 3000， 醇解度为 80-100% ; 所述多元醇选自山梨糖醇、 甘油、 季戊四醇中的一种或几种。
8、 根据权利要求 1所述的材料， 其中， 所述混合物中还含有 0.5-15重 量％的封端剂， 所述封端剂选自硼砂、 硼酸、 甲醛、 二甲基脲、 三甲基三聚 氰胺、 二甲基乙基脲、 二醛、 重袼酸盐、 硝酸铬、 有机钛酸盐中的一种或几 种。
9、 根据权利要求 1所述的材料， 其中， 所述混合物中还含有 0.5-15重 量％的聚酯， 所述聚酯选自聚己内酯、 聚碳酸酯、 聚 β -羟基丁酸酯中的一 种或几种。
10、根据权利要求 1所述的材料，其中，所述混合物中还含有有机羧酸， 所述有机羧酸的碳原子数为 1-20， 以混合物的总量为基准， 该有机羧酸的含 量为 0.5-10重量％。
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