WO2007036167A1

WO2007036167A1 - Hydrophobic biodegradable material

Info

Publication number: WO2007036167A1
Application number: PCT/CN2006/002602
Authority: WO
Inventors: Xiaolu Li
Original assignee: Xiaolu Li
Priority date: 2005-09-30
Filing date: 2006-09-30
Publication date: 2007-04-05
Also published as: CN1939968B; CN1939968A

Abstract

A hydrophobic biodegradable material is a product by melting a mixture, which comprises polyol, polyvinyl alcohol containing water, and starch contained or not. Said polyvinyl alcohol is a hydrophobic polyvinyl alcohol. The amount of polyol is 0.1% by weight to less than 15% by weight, based on the sum of the mixture. The melt temperature of the hydrophobic biodegradable material of the present invention is 130-210 , which is much lower than its decomposition temperature which is 260-420 , so in a true sense it can be extrusion-granulated and injection-molded. The resulting injection molded articles, produced by the hydrophobic biodegradable material of the present invention, have good charpy impact strength, yield strength in tension, elongation at break, water resistance and properties of biodegradation.

Description

Hydrophobic biodegradable material

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. , reinforcing agent, modifier, filler, etc.; then, 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. It is also taught that the above materials can be blown and foamed at a temperature ranging from 150 to 250 °C. However, when 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 Ό, 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 ratio is ethylene glycol: glycerin: polyester polyol = 1-3: 9-15: 3- 6 ternary composite system and water, 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. Like the material disclosed in CN 1405230A, 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.

It is well known that the cast film is not easy to control the thickness during the preparation process, and the cast film prepared is generally thick and uneven. In addition, 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. Furthermore, 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 two sides of the film are heat-sealed together, which is an important reason for the high cost of the film product; and the blow molding requires only melting the film to obtain a film product. In addition, the casting method can only produce film products, and cannot produce products for injection, foaming, and extruded sheets. Therefore, it is required to obtain a material containing polyvinyl alcohol which can be processed in a heated molten state, such as injection molding. Summary of the invention

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 injection molded articles, and provide a plasticity which can be used for injection molding products. Hydrophobic biodegradable material and preparation method thereof.

In order to enable the hydrophobic biodegradable material containing polyvinyl alcohol to be in a molten state, 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. And 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. In fact, 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. However, polyvinyl alcohol must react with starch and other components in a molten state to form a biodegradable material having a stable molten state. Therefore, it is because 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. It functions as a plasticizer and a modification, so that the melting temperature of the polyvinyl alcohol cannot be lowered, and the molten state of the polyvinyl alcohol is still not achieved, and the polyvinyl alcohol and the mixture of the plasticizer and the starch cannot be in a molten state.

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. Moreover, 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.

It is well known to those skilled in the art that granulation in the prior art and its subsequent injection molding, 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 injection molding in a subsequent process. However, 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. When heating these simple mixtures, if the heating temperature is higher than the melting temperature of the polyvinyl alcohol, at least part of the polyvinyl alcohol has been decomposed and carbonized without melting, and if the temperature is lower than the melting temperature, the polyethylene The alcohol can be melted, so that it can not be mixed and reacted with the plasticizer and starch in a molten state, and a reaction product having a stable molten state can be formed, so that blow molding and extrusion cannot be realized at all. Molded or injection molded.

In general, water is a taboo in the processing of thermoplastic materials, especially hydrophobic thermoplastics, because 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 a mixture of water and hydrophilic polyvinyl alcohol is first mixed, 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. The pelletizing can be carried out in a molten state in an extruder to obtain a pellet of hydrophilic 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 injection molding to form an injection molded article. This may be because the molecular weight of water is very small. When water is contacted with hydrophilic polyvinyl alcohol alone, water can easily enter the molecular structure of polyvinyl alcohol, and the molecular chain of polyvinyl alcohol is opened to make the original intertwined. The molecular chain of polyvinyl alcohol is fully stretched, so that the plasticizer can enter the polyvinyl alcohol more easily, and the polyvinyl alcohol can be plasticized and modified together. The fully plasticized and modified polyvinyl alcohol can form a stable Molten State, reacting 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, making thermoplastic molding of the biodegradable material 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 0.1% by weight to less than 15% by weight based on the total amount of the mixture.

Since the material provided by the present invention does not contain any synthetic resin which is difficult to biodegrade under natural environmental conditions, the materials and articles thereof provided by the present invention are completely biodegradable (ISO 14855, 99 days up to 90% or more). Most importantly, since 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 polyvinyl alcohol, starch and polyol, enabling true melt extrusion granulation. And injection molding.

The hydrophobic biodegradable material provided by the invention can be obtained by injection molding to obtain an injection molded product, and the obtained product has good impact strength, elongation at break and tensile yield strength of the simply supported beam, and the biodegradation rate is extremely high, 45 The biodegradation rate of the day is more than 60%, the biodegradation rate of 60 days is more than 70%, and the biodegradation rate of 99 days is more than 92%, which fully meets the requirements of ISO 14855 for biodegradable products (the biodegradation rate is greater than 90% in 180 days) . Since the polyvinyl alcohol is a hydrophobic polyvinyl alcohol, the injection molded 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 do not change. In addition, by adding 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;

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 starch may be present in the mixture in an amount of from 0 to 90% by weight, preferably from 3 to 85% by weight, based on the total amount of the mixture; the aqueous polyvinyl alcohol may be present in an amount of from 5 to 90% by weight, preferably 10% 60% by weight; the content of the polyol may be from 0.1% by weight to less than 15% by weight, preferably from 0.5 to 14.9% by weight.

The hydrophobic biodegradable material provided by the present invention has a melting temperature of 130-210 ° C, preferably 140-200, and a decomposition temperature of 260-420 "C, preferably 270-410" C o. For example, in Example 1, The mixture contains 63.0% by weight of starch, 27,0% by weight of aqueous polyvinyl alcohol, 0.5% by weight of sorbitol, 2.0% by weight of glycerin, 2.0% by weight of pentaerythritol, 2.0% by weight of zinc stearate, 2.0 weight. % calcium stearate, 0.5% by weight of carboxymethylcellulose, 0.5% by weight of epoxidized soybean oil and 0.5% by weight of antioxidant DSTP, the resulting material has a melting temperature of 150-195 ° C and a decomposition temperature of 275-380 ° 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. In the aqueous polyvinyl alcohol of the present invention, the weight ratio of polyvinyl alcohol to water is preferably from 5 to 10, more preferably from 6 to 9. The polyvinyl alcohol may be various hydrophobic polyvinyl alcohols in the prior art. In the present invention, 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 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 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.

Further, in the present invention, the mixture may further contain a cellulose-based polymer which also functions to plasticize polyvinyl alcohol. The cellulose-based polymer is selected from the group consisting of carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose.

(HPMC), one or more of hydroxypropylethylcellulose. 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, hydroxyalkane One or more of a starch, an alkyl starch, an aryl starch, a primary amine starch ether, a secondary amine starch ether, a tertiary amine starch ether, an anthraquinone starch ether, and a cyanamide starch.

In the present invention, the starch-free mixture also has a stable molten state, and the obtained material can also be used for preparing an injection molded article, but since the price of polyvinyl alcohol is much higher than the price of starch, especially ordinary starch. The addition of starch can correspondingly reduce the content of polyvinyl alcohol in the mixture, can reduce the raw material cost of the polyvinyl alcohol material of the present invention, and at the same time improve the biodegradability of the material. However, since 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 of the required materials can be adjusted as needed. The mixture of the present invention contains 0 to 90% by weight of starch, preferably 35 to 85% by weight, based on the total amount of the mixture.

In order to further improve the water resistance of the hydrophobic biodegradable material of the present invention, 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, the aliphatic polyester compound may be, for example, one or more of polycaprolactone, polycarbonate, polyhydroxybutyrate (PHB); preferably poly-β-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 methods 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 poly group. The degree of polymerization of components such as vinyl 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. Therefore, 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 of chromate, chromium nitrate, and organic titanate Kind or several. Examples of 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 blocking agent may be from 0 to 15% by weight, preferably from 0.5 to 15% by weight, based on the total amount of the mixture.

Further, the inventors of the present invention have found that an injection molded article obtained from a mixture containing the above components may ooze oily small liquid beads on the surface of the product at a temperature of more than 23 ° C and a relative humidity of more than 60%. Since the liquid bead is 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, and the content of the organic carboxylic acid may be 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. Examples of the organic carboxylic acid 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 .

In the present invention, 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. Kind. The stearates include stearates of Ca, Mg, Zn, Ba, Ce, and Fe. Such 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. Based on the total amount of the mixture, the salt is added. The content of the additive is from 0 to 5% by weight, preferably from 0.2 to 2% by weight.

In the mixture of the present invention, some commonly used 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. For example, in order to prevent and inhibit the premature degradation of starch during processing or during use due to factors such as light, heat, oxygen, microorganisms or bacteria, an antioxidant, 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 One or more of an acid ester (referred to as antioxidant DSTP), a phosphite, a composite antioxidant PKY, and a bisphenolphthalein. 'The light/heat stabilizer may be selected from one of UV-series light/heat stabilizers, carbon black, organotin light/heat stabilizers, tridecyl phenyl phosphite (TNPP), epoxidized soybean oil or Several. Among them, the UV-series light/heat stabilizer may be α-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, and 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 injection machine, 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 polyvinyl alcohol means that the weight ratio of polyvinyl alcohol to water in the swollen polyvinyl alcohol, that is, the aqueous polyvinyl alcohol is 5-10, preferably 6-9.

The reason for the contact of water with polyvinyl alcohol is that the molecular weight of water is small. When water is contacted with polyvinyl alcohol alone, water easily enters the molecular structure of the polyvinyl alcohol, and the hydrogen bonds between the molecules of the polyvinyl alcohol and the molecules are destroyed. Maximize the molecular chain of the intricately intertwined polyvinyl alcohol, which lays a foundation for the maximum penetration of the polyol plasticizer into the molecular structure of the polyvinyl alcohol, thereby finally reducing the melting temperature of the polyvinyl alcohol and causing the poly-poly The mixture of vinyl alcohol is capable of achieving a molten state. In order to sufficiently swell the polyvinyl alcohol, it is preferred that the weight ratio of the polyvinyl alcohol to water is from 1 to 8, preferably from 3.5 to 7. When the weight ratio of the polyvinyl alcohol to water is much less than 1, the polyvinyl alcohol is dissolved in water to form a solution state instead of the swelling state required by the present invention, or the swelling degree of polyvinyl alcohol is too high, and is not suitable for use. The injection molded article is prepared; when the weight ratio of the polyvinyl alcohol to the water is much larger than 8, the polyvinyl alcohol cannot be fully swelled, and the purpose of lowering the melting temperature of the polyvinyl alcohol is not achieved.

The conditions of the contact may be sufficient to sufficiently swell the polyvinyl alcohol. For example, 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. In this manner, although 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. Since the polyvinyl alcohol in the present invention is a hydrophobic polyvinyl alcohol, the polyvinyl alcohol is hardly soluble in water at 45 ° C (under 1 atm), so that the contact temperature of the polyvinyl alcohol with water is preferably 80-105 Torr. (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 ° C under stirring.

Since 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 that evaporates; the faster the mixing, the more The higher the calorific value, the more water is evaporated, so the weight ratio of polyvinyl alcohol to water in the obtained aqueous polyvinyl alcohol is slightly larger than the above-mentioned polyvinyl alcohol to water weight ratio and contact conditions. The weight ratio of polyvinyl alcohol to water, and when the stirring speed is faster and/or the stirring time is longer, the amount of water can be appropriately increased so that the weight ratio of polyvinyl alcohol to water in the aqueous polyvinyl alcohol is Within the range of 5-10.

The mixture containing a polyol and an aqueous polyvinyl alcohol, with or without a starch, can be obtained by uniformly mixing the aqueous polyvinyl alcohol, the polyol obtained above, and the starch selectively contained.

When the aqueous polyvinyl alcohol, the polyol, and the starch selectively contained are mixed, it is also preferred to add one or more of a polyester, a blocking agent and an organic carboxylic acid and mix them uniformly.

When the 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 any. For example, 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 may be selectively contained. After the polyol is uniformly mixed, the aqueous polyvinyl alcohol is added and uniformly mixed; the aqueous polyvinyl alcohol and the polyol may be firstly mixed and then the selectively contained starch may be added and uniformly mixed; the aqueous polyvinyl alcohol may also be mixed. The polyol and the selectively contained starch are uniformly mixed together. Preferably, in order to better effect the polyol on the plasticization of the aqueous polyvinyl alcohol, the aqueous polyvinyl alcohol and the polyol are uniformly mixed, and then the selectively contained starch is added and uniformly mixed.

The starch may be added in an amount of from 0 to 90% by weight, preferably from 35 to 85% by weight, based on the total amount of the mixture; the aqueous polyvinyl alcohol may be added in an amount of from 5 to 90% by weight, preferably from 10 to 60% by weight. The polyol may be added in an amount of 0.1% by weight to less than 15% by weight, preferably 0.5-14.9% by weight, and the polyester may be added in an amount of 0-20% by weight, preferably 0.5-15% by weight of the blocking agent. The amount of the organic carboxylic acid added may be from 0 to 15% by weight, preferably from 0.5 to 15% by weight, from 0 to 10 The weight %, preferably 0.5-10 weight, of the cellulose-based polymer may be added in an amount of 0 to 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 method and conditions for extruding the mixture by heating and then extruding the resulting melt are well known to those skilled in the art. For example, 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 to 64 and a screw rotation speed of 50 to 1,500 rpm. The twin-screw extruder is generally divided into 12 sections from the feeding end to the discharging end. From the feeding end to the discharging end, the temperature of each section is set to 90-150 ° C and 95-155 °, respectively. C, 100-160 ° C, 115-165. C, 120-175 ° C, 125-175 ° C, 130-185 ° C, 135-185 ° C, 110-180 ° C, 115-75 ^D C 120-185 ° C, 130-180. C, the 4th and 10th sections are vacuum sections, and the degree of vacuum is 0.02-0.09. MPa. In the present invention, 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, for example, 500 rpm or more, the intermeshing twin-screw pair is added to the twin-screw extruder: the material has strong friction and 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 specific steps of the method for preparing the material provided by the present invention are as follows:

(1) mixing and blending polyvinyl alcohol and water uniformly and fully swelling to obtain aqueous polyvinyl alcohol, followed by adding polyol and optionally containing starch, polyester, blocking agent, organic carboxylic acid, cellulose-based polymer One or more of the salt additives and the auxiliary agents are mixed to obtain a mixture. Wherein, 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;

(2) The obtained mixture is melted, extruded and granulated. Wherein, the granulation can be, for example, a twin-screw extruder with a length to diameter ratio of 20-64 and a screw rotation speed of 50-1200 rpm, from the feed end to the feed end The discharge end is divided into 12 sections, and 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, 135-185 ° C, 110-180 ° C, 115-175. C, 120-185 ° C, 130-180 ° C, the 4th and 10th sections are vacuum sections, and the mixture obtained above is melt-extruded and granulated under vacuum conditions of 0.02-0.09 MPa.

The hydrophobic biodegradable material of the present invention can be produced into an injection molded article by an injection molding method. The steps and conditions of the injection molding method are well known to those skilled in the art and will not be described again.

The invention is further illustrated by the following examples. Example 1

This embodiment is for explaining the hydrophobic biodegradable material provided by the present invention and a preparation method thereof.

(1) 24.0 parts by weight of 50 liters of purified water was added to 60.0 parts by weight of polyvinyl alcohol having a degree of alcoholysis of 90% and a median degree of polymerization of 2250 at a stirring speed of 500 rpm, and the system was heated and maintained at After stirring at about 95 ° C for 45 minutes, an aqueous polyvinyl alcohol was obtained in which the weight ratio of polyvinyl alcohol to water was 6.0. After the system was cooled to about 30 ° C, 0.5 parts by weight of sorbitol, 2.0 parts by weight of glycerin, and 2.0 parts by weight of pentaerythritol were added to 27.0 parts by weight of the above aqueous polyvinyl alcohol at 30 ° C. The mixture was stirred and mixed at a stirring speed of 300 rpm. After standing for 12 hours, 63.0 parts by weight (dry basis weight) of ordinary wheat starch having a number average molecular weight of 150,000 was added to the above mixture and stirred uniformly. The mixer was first turned at 100 rpm. Mix at low speed for about 7 minutes, then mix at high speed for 200 minutes at 200 rpm for 8 minutes, then add 2.0 parts by weight of zinc stearate, 2.0 parts by weight of calcium stearate, 0.5 parts by weight of antioxidant DSTP, 0.5. Parts by weight of epoxidized soybean oil and 0.5 parts by weight of carboxymethylcellulose and stirred to obtain a mixture M1, the composition of M1 is shown in Table 1 below;

(2) The above uniformly stirred mixture is fed into a feed port of a twin-screw extruder having an aspect ratio L: D = 50:1 and a screw diameter of Φ 72 mm. Adjust the speed of the screw to 900 rpm, from the feeding end to the discharge end, the temperature of each section is set to 130 ° C, 135 ° C, 140 ° C, 150 ° C, 160. (, 165 ° C, 165 ° C, 170 ° C, 175 ° C, 170 ° C, 180 ° C and 170 ° C; vacuum section vacuum maintained at 0.02-0.09 MPa; discharge in the extruder A strip-shaped extrudate having a diameter of 3 mm was obtained, and the strip-like extrudate was pelletized to obtain a hydrophobic biodegradable material pellet BSR-07V-IJ1 for preparing an injection-like shaped article having a length of 2 mm. Comparative example 1

This comparative example is used to illustrate the existing biodegradable material containing polyvinyl alcohol and a preparation method thereof.

(1) 23.0 parts by weight of polyvinyl alcohol (degree of alcoholysis of 90%, median degree of polymerization of 2,250) and

'63.0 parts by weight of starch mixed well, 'then with 9.0 parts by weight of water, 0.5 parts by weight of sorbitol, 2.0 parts by weight of glycerin, 2.0 parts by weight of pentaerythritol, '2.0 parts by weight of zinc stearate, 2.0. The parts by weight of calcium stearate, 0.5 part by weight of antioxidant DSTP, 0.5 part by weight of epoxidized soybean oil and 0.5 part by weight of decyl methylcellulose are added to a mixer and mixed, and the mixer is first stirred at a low speed of 100 rpm for about 7 minutes. And then stirring at a high speed of 200 rpm for 8 minutes to obtain a mixture CM1;

(2) The above mixture CM1 was extrusion-granulated according to the method described in the step (2) of Example 1, and as a result, a powdery carbide having no plasticity was obtained. This may be because the twin-screw extruder's twin-screws mesh with each other and the screw speed is as high as 900 rpm. The intermeshing twin-screw has a strong friction and shearing effect on the material added to the twin-screw extruder. Polyvinyl alcohol is an unplasticized polyvinyl alcohol. Before the polyvinyl alcohol melts and reacts with other components, the heat generated by the intense friction and shear causes the temperature to reach the decomposition temperature of polyvinyl alcohol, resulting in the carbonization of polyvinyl alcohol. The polyvinyl alcohol does not react with other components to form a reaction product having a stable molten state, thus producing a powdery carbide without any plasticity. Example 2

(1) Add 25.0 parts by weight of pure water at 55 ° C at a stirring speed of 350 rpm In a 50.0 parts by weight polyvinyl alcohol having a degree of alcoholysis of 85% and a median degree of polymerization of 2,450, the system is heated and maintained at about 100 ° C for 33 minutes to obtain an aqueous polyvinyl alcohol. The weight ratio of polyvinyl alcohol to water in the vinyl alcohol was 5.5. After the system is cooled to about 30 ° C, 3.0 parts by weight of sorbitol, 8, 0 parts by weight of glycerin and 2.0 parts by weight of pentaerythritol are added to 30.0 parts by weight of the above aqueous polyvinyl alcohol at 80 rpm. After stirring for a minute, the mixture was uniformly mixed. Then, 48.0 parts by weight (dry basis weight) of ordinary potato starch having a number average molecular weight of 200,000 was added to the above mixture and stirred uniformly. The mixer was first mixed at a low speed of 100 rpm for about 7 minutes, and then Then, mix at a high speed of 200 rpm for 8 minutes, and then add 3.0 parts by weight of zinc stearate, 3.0 parts by weight of PHB, 1.0 part by weight of liquid paraffin, 1.0 part by weight of epoxidized soybean oil, and 0.5 part by weight of borax. And 0.5 parts by weight of formaldehyde and stirred to obtain a mixture M2, the composition of which is shown in Table 1 below;

(2) Extrusion granulation of the above mixture M2 in a molten state according to the method described in the step (2) of Example 1 to obtain a pellet product BSR-07V for preparing a hydrophobic biodegradable material for an injection-molded article. -IJ2. Example 3

(1) 10.0 parts by weight of pure water of 55 ° C was added to 60.0 parts by weight of polyvinyl alcohol having a degree of alcoholysis of 90% and a median polymerization degree of 2050 at a stirring speed of 500 rpm, and the system was heated. After maintaining stirring at about 98 ° C for 45 minutes, an aqueous polyvinyl alcohol was obtained, and the weight ratio of polyvinyl alcohol to water in the aqueous polyvinyl alcohol was 9.0. After the system was cooled to about 30 ° C, 0.5 parts by weight of sorbitol and 1.0 part by weight of glycerin were added to the above 17.0 parts by weight of aqueous polyvinyl alcohol, stirred and mixed at 100 rpm, and then 75.0 parts by weight (dry basis weight) of ordinary sweet potato starch having a number average molecular weight of 180,000, 0.5 part by weight of carboxymethylcellulose, 1.0 part by weight of PHB, 0.5 part by weight of formaldehyde, 1.0 part by weight of zinc stearate 1.0 part by weight of liquid paraffin, 2.0 parts by weight of epoxidized soybean oil and 0.5 part by weight of antioxidant 1010 are added to the above mixture Stir well, the mixer was first mixed at a low speed of 100 rpm for about 7 minutes, and then mixed at a high speed of 200 rpm for 8 minutes to obtain a mixture M3. The composition of M3 is shown in Table 1 below;

(2) Extrusion granulation of the above mixture M3 in a molten state according to the method described in the step (2) of Example 1 to obtain a pellet product BSR for preparing a hydrophobically fully biodegradable material for an injection-molded article. -07V -IJ3. Example 4

(1) 20.0 parts by weight of purified water of 50 ° C was added to 74.0 parts by weight of polyvinyl alcohol having a degree of alcoholysis of 90% and a median polymerization degree of 2050 at a stirring speed of 450 rpm, and the system was heated and After stirring at 650 rpm for 45 minutes at about 95 ° C, an aqueous polyvinyl alcohol was obtained in which the weight ratio of polyvinyl alcohol to water was 8.0. After the system was cooled to about 30 ° C, 2.5 parts by weight of sorbitol and 0.5 parts by weight of glycerin were added to 35.0 · parts by weight of the above aqueous polyvinyl alcohol, and the mixer was first mixed at a low speed of 100 rpm for about 10 minutes. Then, mix at a high speed of 200 rpm for 8 minutes, and then add 57.0 parts by weight (dry basis weight) of ordinary corn starch having a number average molecular weight of 100,000, 1.0 part by weight of carboxymethylcellulose, and 1.0 part by weight of hard. Zinc citrate, 1.0 part by weight of calcium stearate, 0.5 part by weight of liquid paraffin, 1.0 part by weight of dimethyl urea and 0.5 part by weight of epoxidized soybean oil and stirred to obtain a mixture M4, the composition of which is as shown in Table 1. Show

(2) Extrusion granulation of the above mixture M4 in a molten state according to the method described in the step (2) of Example 1 to obtain a pellet product BSR-07V for preparing a hydrophobic biodegradable material for an injection-molded article. -IJ4. Example 5

This embodiment is for explaining the hydrophobic biodegradable material provided by the present invention and a preparation method thereof. (1) 20.0 parts by weight of purified water of 50 ° C was added to 74.0 parts by weight of polyvinyl alcohol having a degree of alcoholysis of 90% and a median polymerization degree of 2050 at a stirring speed of 350 rpm, and the system was heated and After stirring at 650 rpm for 45 minutes at about 95 ° C, an aqueous polyvinyl alcohol was obtained in which the weight ratio of polyvinyl alcohol to water was 8.0. After the system is cooled to about 30 ° C, 2.5 parts by weight of sorbitol and 0.5 parts by weight of glycerin are added to 35.0 parts by weight of the above aqueous polyvinyl alcohol, and the mixer is first mixed at a low speed of 100 rpm for about 10 minutes, and then The mixture was mixed at a high speed of 200 rpm for 8 minutes, and then 57.0 parts by weight (dry basis weight) of ordinary corn starch having a number average molecular weight of 100,000, 2.0 parts by weight of acetic acid, 1.0 part by weight of zinc stearate, and 1.0 part by weight. Formaldehyde, 0.5 parts by weight of liquid paraffin and 0.5 part by weight of epoxidized soybean oil and stirred to obtain a mixture M5, the composition of which is shown in Table 1 below;

(2) Extrusion granulation of the above mixture M5 in a molten state according to the method described in the step (2) of Example 1 to obtain a pellet product for preparing a hydrophobic biodegradable material for an injection-molded article: BSR- 07V-IJ5. Example 6

This embodiment is for explaining the hydrophobic biodegradable material provided by the present invention and a preparation method thereof. (1) 20.0 parts by weight of water at 50 ° C was added to 74.0 parts by weight of polyvinyl alcohol having a degree of alcoholysis of 90% and a median polymerization degree of 2050 at a stirring speed of 350 rpm, and the system was heated and maintained. After stirring at 650 rpm for 45 minutes at about 95 ° C, an aqueous polyvinyl alcohol was obtained in which the weight ratio of polyvinyl alcohol to water in the aqueous polyvinyl alcohol was 8.0. After the system was cooled to about 30 ° C, 2.5 parts by weight of sorbitol and 0.5 parts by weight of glycerin were added to 35.0 parts by weight of the above-mentioned aqueous polyvinyl alcohol, and the mixer was first mixed at a low speed of 100 rpm at 40 ° C. 10 minutes, then mix at a high speed of 200 rpm for 8 minutes, then add 57.0 parts by weight (dry basis weight) of ordinary corn starch with a number average molecular weight of 100,000, 1.0 part by weight of PHB, and 1.0 part by weight of stearic acid. Zinc, 1.5 parts by weight of acetic acid, 1.0 part by weight of succinic acid, 1.0 part by weight of dimethylurea and 0.5 Parts by weight of epoxidized soybean oil were stirred to obtain a mixture M6, and the composition of M6 was as shown in Table 1 below; (2) The above mixture M6 was extruded and granulated in a molten state according to the method described in the step (2) of Example 1. A pellet product BSR-07V-IJ6 for preparing a hydrophobic biodegradable material for injection molded articles was obtained.

Table 1

Example 7-12

The following examples illustrate the performance of the hydrophobic biodegradable materials provided by the present invention.

Add the above pellet products BSR-07V-IJ1 to BSR-07V-IJ6 to Ningbo Haitian Company In the feed port of the 300-gram injection machine, there are 6 sections from the feed end to the discharge end, and the temperature of each section is set to 150 ° C, 155 ° C, 165 ° C, 170 ° C, 165 °. C, 155 ° C, the pellet product was melted and injection molded at the die to obtain a dumbbell type I standard spline IJ1-IJ6 having a size of 100 mm (length) X 10 mm (width) X 1.0 mm (thickness).

The performance test of the above-mentioned injection dumbbell type I standard spline was carried out by the following standard methods. The test results are shown in Table 2 below:

The tensile elongation of the product was determined by GB/T1040-1992 plastic tensile test method; the impact strength of the simply supported beam of the product was determined by GB/T1043-93 hard plastic simply supported beam impact test method;

Determine the tensile yield strength of the product by GB/T1040;

The biodegradation rate of the above product was measured in accordance with the method specified in IS014855-99.

Water resistance test method: (1) completely immerse the above standard spline IJ1-IJ6 in 5 times weight of water for 1 hour at 1 atm, 25 ,, wipe off the surface moisture, observe the appearance change of the product, and test the immersion Tensile yield strength, simply supported beam impact strength, and elongation at break of the article. 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.

(2) The above standard splines IJ1-IJ6 were placed in an environment with a temperature of 30 ° C and a relative humidity of 70% for 30 days, and the appearance change of each spline was observed and the tensile yield strength and the simply supported beam impact strength were tested. , elongation at break. The appearance of the products before and after the placement was found to be no significant change. Other test results are shown in Table 2.

Test for surface tackiness of the product: According to the above-mentioned injection molding method of the dumbbell type I standard spline IJ1-IJ6, 20 rectangular parallelepiped samples IJ1 '-IJ6 having a size of 100 mm (length) X 100 mm (width) X 1.0 mm (thickness) were obtained. ', divide 20 samples into 10 groups (two in each group), stack two samples of each group together, the contact surface is 100 mm (length) X 100 mm (width) surface, then at a temperature of 30 ° C. After standing for 48 hours in an environment with a relative humidity of 70%, press each set of samples stacked in a direction perpendicular to the contact surface at a pressure of 1000 Pa, and then observe whether the samples of each group stick to each other. Together, the number of groups of the samples stuck together was recorded, and at the same time, the presence of oily small bead phenomenon on the surface of the side of the sample perpendicular to the pressing direction was observed, and the results were recorded in Table 2 below. Since the cuboid sample IJ1 '-IJ6 here is prepared from the above-mentioned sample IJ1-IJ6 by the same composition of the pellet product and the preparation method, the difference is only to form the sample to increase the contact area between the samples. The cuboid is used to accurately measure the surface tack of the sample to inject the sample into different shapes, so the test samples are collectively indicated by IJ1-IJ6 in the following table.

In Table 2 below, 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.

Table 2

As can be seen from the results shown in Table 2, the articles IJ1-IJ6 made of the hydrophobic biodegradable material pellets BSR-07V-IJ1 to BSR-07V-IJ6 of Examples 1-6 have a good simple support. Beam impact strength, elongation at break and tensile yield strength; biodegradation rate is extremely high, the biodegradation rate is more than 60% in 45 days, the biodegradation rate in 60 days is more than 75%, and the biodegradation rate in 99 days is greater than 92%, completely Meets the requirements of ISO 14855 for biodegradable products (biodegradation rate greater than 90% in 180 days). Since 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, the simply supported beam impact strength, elongation at break and stretching The change in yield strength is small, indicating that the water resistance of the product is very good. Examples 2-6 incorporate polyester and/or a capping agent in the preparation of the hydrophobic biodegradable material, and Example 1 does not use a polyester or a capping agent in the preparation of the hydrophobic biodegradable material, and is performed by BSR- Compared with the products made by 07V-IJ1, the products made from BSR-07-IJ2 to BSR-07V-IJ6 were soaked in water for 1 hour or placed at 70% humidity for 30 days, and the simply supported beam impact strength, elongation at break and The change in tensile yield strength is smaller and the water resistance is better.

Examples 5 and 6 were prepared by adding organic carboxylic acids to the preparation of hydrophobic biodegradable materials BSR-07V-U5 and BSR-07V-IJ6, and products U5 and IJ6 made from BSR-07V-IJ5 and BSR-07V-IJ6. There was no phenomenon of surface adhesion, and therefore, compared with the products IJ1-IJ4 made of the hydrophobic biodegradable material pellets BSR-07V-IJ1 to BSR-07V-IJ4 of Examples 1-4, by BSR-07V The surface viscosities of the articles IJ5 and IJ6 prepared by -IJ5 and BSR-07V-IJ6 are remarkably lowered, and the problem of oily small liquid beads and surface adhesion on the surface of the product does not occur during placement and use. Example 13

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-IJ1 obtained in Example 1 were determined by the following method.

Accurately weigh about 4.7 mg of the hydrophobic biodegradable material pellet BSR-07V-IJ1 prepared in Example 1, and place it in the sample cell of the NETZSCH DSC 204F1 differential scanning calorimeter at a flow rate of 60 ml/min. Under nitrogen protection, the sample was heated from 25 ° C to 180 ° C at a heating rate of 10 Ό / min, held at 180 ° C for 2 minutes, and then heated to 300 ° C at a temperature increase rate of 10 ° C / min, The resulting DSC curve is shown in Figure 1. Accurately weigh about 4.7 mg of the hydrophobic biodegradable material pellet BSR-07V-IJ1 prepared in Example 1, and placed it in the sample cell of the thermogravimetric analyzer (Germany NETZSCH Instrument Manufacturing Co., Ltd.) model TG209F1. The sample was heated from 25 ° C to 180 ° C at a heating rate of 10 Ό / min under a nitrogen flow rate of 60 cc / min, held at 180 ° C for 2 minutes, and then at a heating rate of 10 ° C / min Heating was continued to 600 ° C to obtain a thermogravimetric curve as shown in FIG. 2 .

It can be seen from Fig. 1 that the DSC curve of the sample has an endothermic peak in the temperature range of 150-195 ° C and around 275 ° C; as can be seen from Fig. 2, in the temperature range of 275-380 ,, the sample The weight loss is fast, and there is substantially no loss in the weight of the sample in the temperature range of 150-195 Torr. The results of Figure 1 and Figure 2 show that the endothermic peak at 150-195 Torr in the DSC curve of the sample is the endothermic peak caused by the melting endothermic of the sample, and the endothermic peak near 275 ° C is accompanied by the rapid sample. Loss of weight indicates that the sample decomposes at this temperature. Therefore, the endothermic peak is an endothermic peak caused by sample decomposition. This shows that the pellet obtained in Example 1 can achieve a stable molten state in a wide temperature range of 150-195 Torr, which is much lower than its own decomposition temperature, and can be granulated in the wide temperature range. The material is subjected to thermoplastic processing. As shown in Table 2, the article obtained by the melt melting and injection molding of the pellet of Example 1 had excellent impact strength, tensile yield strength and elongation at break, and completely met the requirements of injection molded articles. This further demonstrates that 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 thermoplastic material which has a melting temperature much lower than its own decomposition temperature. Example 14

This example is intended to illustrate the properties of articles made from the hydrophobic biodegradable materials of the present invention.

3 and 4 show scanning electron microscopy of the original starch used in Example 1 and the cross-sectional magnification of the hydrophobic biodegradable material pellet BSR-07V-IJ1 of Example 1 at 2000 magnification, respectively. photo. The scanning electron micrograph uses scanning electron microscopy of model JSM5600LV Mirror (Japan Electronics Co., Ltd.).

It can be clearly seen in Figure 3 that the starch granules are spherical granules, and the presence of starch granules is no longer visible in Figure 4. This shows that in the preparation of the pellets in Example 1, the starch granules were sufficiently refined under the shearing action of the twin-screw extruder, and the starch and other components were not only formed. Simple physical mixing, but a single uniform product. This further illustrates that 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.

In addition, 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, the elongation at break and the tensile yield strength, are significantly improved, which is superior to the material. An article made from any single component. This also demonstrates that the material provided by the present invention is a completely new reaction product that is completely different from existing simple mixtures.

Claims

Claim

A hydrophobic biodegradable material, characterized in that the material is a product formed by melting a mixture comprising a polyol and an aqueous polyvinyl alcohol, with or without starch, said poly The vinyl alcohol is a hydrophobic polyvinyl alcohol, and the content of the polyol is from 0.1% by weight to less than 15% by weight based on the total amount of the mixture.

The material according to claim 1, wherein the material has a melting temperature of 130 to 210 ° C and a decomposition temperature of 260 to 420 ° C.

3. The material according to claim L, wherein, based on the total amount of the mixture; the content of the aqueous polyvinyl alcohol in the mixture is 10 to 60% by weight, and the content of the polyol is 0.5 to 14.9. The weight %, the content of the starch is from 35 to 85% by weight.

The material according to claim 1 or 3, wherein the aqueous polyvinyl alcohol is obtained by contacting polyvinyl alcohol with water, the conditions of contact, and the amount of polyvinyl alcohol and water are sufficient to cause the aqueous poly The weight ratio of polyvinyl alcohol to water in the vinyl alcohol is 5-10.

5. The material according to claim 4, wherein the weight ratio of polyvinyl alcohol to water is

1-8.

The material according to claim 4, wherein the conditions of the contacting include the polyethylene glycol being contacted with water under stirring for a contact time of 30 to 60 minutes and a contact temperature of 80 to 105 °C.

7. The material according to claim 1, wherein the hydrophobic polyvinyl alcohol has a median degree of polymerization of from greater than 2,000 to 3,000 and a degree of alcoholysis of from 80 to 100%; the polyol is selected from the group consisting of sorbitol, One or more of glycerin and pentaerythritol.

8. The material according to claim 1, wherein the mixture further comprises 0.5-15% by weight of a blocking agent, and the blocking agent is selected from the group consisting of borax, boric acid, formaldehyde, dimethyl urea, trimethyl. One or more of melamine, dimethylethylurea, dialdehyde, dichromate, chromium nitrate, and organic titanate.

9. The material according to claim 1, wherein the mixture further comprises 0.5-15% by weight of a polyester selected from the group consisting of polycaprolactone, polycarbonate, and polyhydroxybutyrate. One or several.

The material according to claim 1, wherein said mixture further contains an organic carboxylic acid having a carbon number of from 1 to 20, based on the total amount of the mixture, said organic carboxylic acid The content is from 0.5 to 10% by weight.