CN1730562A - Cross-linking type degradable cereal protein plastic and its preparation method - Google Patents

Abstract

The invention discloses a cross-linking type cereal protein degradable plastic and its preparing process, wherein the plastic comprises cereal protein 100 weight parts, plasticizing agent 20-100 weight parts, lubricating agent 0.5-1.5 weight parts, anti-oxidant 0.5-1.5 weight parts, preservative agent 0-1 weight part, cross linking agent 1-7 weight parts. The preparing process comprises, subjecting the sulfur element and sulfhydryl compound contained in cereal protein molecules to reduction reaction under room temperature strong shearing condition, and carrying out cross-linking reaction under high temperature moulding. The obtained degradable plastic has fine mechanic performance.

Description

Cross-linking type degradable cereal protein plastic and preparation method thereof

Technical field

The present invention relates to a kind of cross-linking type degradable cereal protein plastic and preparation method thereof.

Background technology

Our times plastics ultimate production surpasses 1.7 hundred million tons, has been penetrated into the every field of national economy all departments and people's lives.Yet plastic raw materials is subjected to the restriction of oil shortage to show especially out day by day, and the problem of environmental pollution that the discarded back of a large amount of plastics is caused is also serious day by day.According to statistics, waste plastic accounts for 7～8% of developed country's rubbish total amount.The development degradable plastics can reduce white pollution, and remarkable economic efficiency and social benefit are arranged.With natural polymers such as agricultural-food natural polymer such as starch, Mierocrystalline cellulose, chitin, protein is the raw material production degradative plastics, becomes one of international research hot of research and development.These material sources are abundant, fully biodegradable.The exploitation comparative maturity of full starch-type degradable plastics, is main raw material as U.S. Wamer-Lambert company, SUMITOMO CHEMICAL Itochu, Italian Ferruzzi company with starch based agricultural-food such as corn, potato or sweet potatoes, made the complete biodegradable plastic (Chen Yun of starch content more than 90%, explain the literary composition that continues, Qiu Xianhua, Wang Feidi, Qiu Weiyang, starch plastic present situation and development prospect. polymer circular, 2000, (4): 77-82).

Have a long history for the feedstock production plastics with the plant protein, all delivered patent (the Edekson DR. for preparing half plastic material by soy-protein as France and Britain in 1913, Practical handbook ofsoybean processing and utillization.St.L.Missouri:AOCS Press and UnitedSoybean Board, 1993,387-391).After the forties in 20th century, along with the rise of petrochemical industry, synthetic plastics has been controlled market, people to protein plastic research seldom report.In recent years, for reasons such as environment protection and petrochemical industry shortages of resources, people begin to restudy the biodegradable plastic that utilizes plant protein production environment close friend, the food product pack mould material that particularly consumption is huge.Gennadios etc. have commented based on the edibility film of gluten powder, soybean protein, zein, milk proteins, Semen arachidis hypogaeae protein or collagen protein etc. or the preparation method and performance (the Gennadios A. of coated material, McHughTH., Weller CL., Krochta JM., Edible coatings and films based on proteins.In Edible coatings andfilms to improve food quality; Krochta JM., Baldwin EA., Nisperos-Carriedo MO., Eds., Technomic Publishing Co.:Lancaster, PA, 1994; 201-277.).

Protein film adopts the solution method preparation usually, solution or suspension with protein, softening agent and other reagent are filming medium (Anker A., Foster GA., Loader MA., Method of preparing glutencontaining films and coatings. United States Patent (USP) 3.653,925,1972; Aydt TP., Weller CL., Testin RF., Mechanical and barrier properties of edible corn and wheat protein films.Trans.ASAE, 1991,34,207-211), improve proteinic solubleness, improve performance (the Gennadios A. of mould material by heat or acid-alkali treatment, Brandenburg AH., Weller CL., Testin RF., Effect ofpH on properties of wheat gluten and soy protein isolate films.J.Agric.Food.Chem., 1993,41:1835-1839; Roy S., Gennadios A., Weller CL., Zeece MG., Testin RF., Physical and molecular properties of wheat gluten films cast from heatedfilm-forming solutions.J.Food Sci., 1999,64:57-60).The mechanical property of com gluten protein material is relatively poor, needs to wait rigidity, thermotolerance and the water tolerance that improves material through uv irradiation, gamma-radiation irradiation, enzyme processing or chemically crosslinked.

Solution legal system film need consume a large amount of organic solvents, and is not suitable for the moulding of big scale material.On the other hand, because stronger interaction of hydrogen bond and the intramolecularly/intermolecular disulfide bond of intermolecular existence, the thermoforming processing (as extruding processing) of protein material is difficult for implementing, and the hot-work under the comparatively high temps can cause proteinic thermolysis.Thereby, need add a large amount of softening agent during the protein thermo forming, to reduce molecular interaction, improve the snappiness of molecular chain.Spendable softening agent has water or polyvalent alcohol such as glycerine, monose, disaccharides or oligose etc.Discoveries such as Mangavel, the mechanical property of the gluten powder film of thermoforming is better than solution casting film (Mangavel C., Rossignol N., Perronnet A., Barbot J., Popineau Y., Gueguen J., Properties and microstructure of thermo-pressed wheat gluten films:a comparisonwith cast films.Biomacromolecules, 2004,5,1596-1601).

In preparation plasticising protein composition process, strong shearing can reduce protein molecular weight.Under comparatively high temps, can form chemically crosslinked again between the protein molecule.This provides theoretical foundation for adopting conventional device of plastic processing to prepare the cross-linked type protein in grain plastics.Employing mechanically mixing such as Domenek have prepared the plasticising gluten powder, adopt compression-moulding methods to prepare crosslinked sample (Domenek S., Morel MH., Redl A., Guilbert S., Rheological investigation of swollen gluten polymer networks:effects ofprocess parameters on cross-link density.Macrom.Symp., 2003,200:137-146), and investigated the plasticising gluten powder extrude complete processing (Pommet M., Redl A., Morel MH., Domenek S., Guilbert S., Thermoplastic processing of protein-based bioplastics:chemicalengineering aspects of mixing, extrusion and hot molding.Macrom.Symp., 2003,197:207-218).

Protein contains a large amount of active groups.Under the situation that does not contain crosslinking additives, thermoforming relates generally to the generation of disulfide linkage between protein molecule.Some can with the material of amino in the protein molecule, amide group, hydroxyl, thiol group generation chemical reaction, as halogenation acetic ester, diimine ester, two-n-hydroxyl-succinimide, dialdehyde or two ketone reagent, all can be used as proteinic chemical cross-linking agent, wherein the most frequently used is aldehydes reagent such as formaldehyde, oxalic dialdehyde or glutaraldehyde.

It is novel reduction-linking agent that the present invention adopts the compound that contains sulfydryl, adopts conventional device of plastic processing, and preparation can be carried out the grain protein composition and the cross-linked type protein in grain plastics of plasticity-processing.Chemical additives such as the present invention proposes to make with lubricator, oxidation inhibitor and sanitas, with the plasticity-processing that improves cereal protein plastics, water tolerance and performance such as ageing-resistant, when prolonging cereal protein plastics work-ing life, guarantee the characteristics that it can be degraded fully again under physical environment.Characteristics of the present invention are not with an organic solvent, thereby preparation technology is eco-friendly.Based on the Young's modulus of the prepared cross-linking type degradable cereal protein plastic of the present invention and tensile strength apparently higher than compounds containing thiol groups linking agent not but other forms identical materials, also apparently higher than the material of the same composition that adopts aldehydes reagent such as formaldehyde crosslinking.

Summary of the invention

The purpose of this invention is to provide a kind of cross-linking type degradable cereal protein plastic and preparation method thereof.

Cross-linking type degradable cereal protein plastic comprises grain protein 100 weight parts, softening agent 20～100 weight parts, lubricant 0.5～1.5 weight part, oxidation inhibitor 0.5～1.5 weight part, sanitas 0～1 weight part, linking agent 1～7 weight part.

The preparation method of cross-linking type degradable cereal protein plastic may further comprise the steps:

1) grain protein, polyol plasticiser, lubricant, oxidation inhibitor and sanitas are carried out pre-mixing,, and in mixing process, add linking agent, obtain the grain protein composition then at 10～40 ℃ of mechanically milling 5～15min;

2) the grain protein composition is placed mould, the 1～3min that colds pressing under room temperature and 5～20MPa pressure rises to 60～80 ℃ with temperature, hot pressing 0～10min, temperature is risen to 110～140 ℃ then, hot pressing 10～30min obtains the corn protein degradable plastic goods.

Grain protein is gluten powder, rice protein powder, wheat gliadin, hordein, zein or kafirin; Softening agent is 1,2-propylene glycol, 1, ammediol, glycol ether, triglycol, 1,4-butyleneglycol, 1,3-butyleneglycol, 2,3-butyleneglycol, glycerine, 1,2,4-trihydroxybutane, 1,2,3-hexanetriol, 1,2,6-hexanetriol, glyceryl monoacetate or glyceryl diacetate; Lubricant is stearic acid, oxystearic acid, n-butyl stearate, single stearic acid glycerine lipoprotein, methyl hydroxystearate, soybean oil, peanut oil, Semen Maydis oil, Rice pollard oil, rapeseed oil, Oleum Gossypii semen, sunflower seed oil or camellia seed oil; Oxidation inhibitor is 2,6-di-tert-butyl-4-methy phenol, 2,6-di-t-butyl-4-methylolphenol, tertiarybutylhydroquinone, butylhydroxy anisole, tea-polyphenol, propyl gallate, tocopherol, Progallin A, Tenox PG, Stabilizer GA 8, lauryl gallate, gallic acid octadecyl ester, xitix, Quicifal, D-saccharosonic acid or sodium D-isoascorbate; Sanitas is Sodium Benzoate, potassium sorbate, sthyl sorbate, Sorbic Acid butyl p-hydroxybenzoate, dehydroacetic acid (DHA), sodium dehydroacetate, Tegosept M, propylparaben, ethyl p-hydroxybenzoate, Sodium Methyl Hydroxybenzoate, nipagin A sodium, Sodium propyl p-hydroxybenzoate or nipabutyl sodium; Linking agent is a 1,1,3-dimercaptopropane, 1,2-succinimide mercaptans, 1,4-succinimide mercaptans, 2,3-succinimide mercaptans, 1,5-pentane disulfide thioalcohol, 1,6-ethanthiol, 1,7-mercaptan in heptan two, 1, hot two mercaptan, 1 of 2-, hot two mercaptan, 1 of 8-, 9-mercaptan in the ninth of the ten Heavenly Stems two, 1,10-mercaptan in the last of the ten Heavenly stems two, positive hexylmercaptan, uncle's hexylmercaptan, n-heptanthiol, octyl mercaptan, uncle's spicy thioalcohol, positive decyl mercaptan, Dodecyl Mercaptan or stearylmercaptan.

Advantage of the present invention is:

1) grain protein does not need through chemistry or physically modified, and production cost is low;

2) utilize the compound that contains sulfydryl to be novel crosslinker, adopt conventional device of plastic processing and method to prepare cross-linking type degradable cereal protein plastic, production technique is simple;

3) corn protein degradable plastic contains softening agent, lubricant, sanitas and oxidation inhibitor, and machine-shaping easily has higher water tolerance and ageing-resistant performance;

4) grain protein is a kind of renewable agricultural resource, and wide material sources are compared with petrochemical material and to be had inexhaustible advantage.

Description of drawings

Fig. 1 is the stress-strain curve of the prepared cross-linking type gluten powder degradable plastics of embodiment 1;

Fig. 2 is the stress-strain curve of the prepared cross-linking type gluten powder degradable plastics of embodiment 2;

Fig. 3 is the stress-strain curve of uncrosslinked type gluten powder degradable plastics (comparative example 1), and except that not containing the linking agent Dodecyl Mercaptan, comparative example 1 composition and complete processing are with embodiment 1;

Fig. 4 is the stress-strain curve of cross-linking type gluten powder degradable plastics (comparative example 2), and except that adopting formaldehyde to replace Dodecyl Mercaptan to do the linking agent, comparative example 2 composition and complete processing are with embodiment 1.

Embodiment

It is gluten powder, rice protein powder, wheat gliadin, hordein, zein or kafirin that the present invention uses protein.

Gluten powder also claims vital wheat gluten, is a kind of natural plant protein matter of extracting for the raw material deep processing with the whole meal flour.Suitable gluten powder can be selected from the commerical prod of protein content 〉=75% (butt), buys gluten powder as can be from Shanghai prosperous flavor Food Co., Ltd, Zhoukou City's "Lotus" gourmet powder group, sky, Henan Province hat vegetable-protein company limited, the happy health food in Tongcheng City, Anhui Province company limited.

Rice protein powder is a kind of highly purified rice protein product of producing from rice meal, rice slag or rice are poor, its protein content 〉=80% (butt).The technology of extracting rice protein from rice meal, rice slag or rice are poor is known, as stating in following document, the document is incorporated herein by reference: " Wang Zhangcun, Yao Huiyuan: Extraction of Rice Protein from Rice Dregs. research grain and fodder industry; 2003, (8): 37-38 ".In addition, Chinese patent 03134973.0 discloses " extracting the method for rice protein from rice ", Chinese patent 03134972.2 discloses " alkaline process extracts the method for rice protein ", and Chinese patent 200410039303.0 discloses " being raw material extraction rice protein and the processing method of making Starch rice with the rice ".Suitable rice protein powder also can be selected from the commerical prod of protein content 〉=80% (butt), as buying rice protein powder from Guilin Red Star bio tech ltd.

The technology of extracting wheat gliadin from wheat-flour is known, as in following document, stating, the document is incorporated herein by reference: " sesame is learned by department; Li Jianwei; Wang Jinshui, girth intelligence, the research of gliadine and glutenin extraction conditions. Zhengzhou Engineering College's journal; 2004,25 (3): 33-39 ".

The technology of extracting hordein from barley grain or seed powder is known, as in following document, stating, these documents are incorporated herein by reference: " Yan Qichuan; yellow second place; Xu Yuan; the seeds prolamine electrophoresis method that ISTA on probation recommends is identified barley and wheat breed. Acta Agronomica Sinica, 1992,18 (1): 61-68; The Dong ox, Wang Lirong, Lan Lan, Zhang Deyi, the dissolution characteristics of high-lysine component research in the hordein. the plant department of the Chinese Academy of Sciences, 1989,31:689-695 ".

The technology of extracting zein from Zein powder (also claiming corn gluten meal) is known, as in following document, stating, the document is incorporated herein by reference: " Zhang Zhong; Qi Aiyun: zein extraction process and Study on Functional; grain and fodder industry; 2004 (9): 21-23. " Chinese patent 00101222.3 discloses the technology of " using preparing alcohol-soluble corn protein membrane from corn gluten ", has wherein described the method for extracting zein from Zein powder.Highly purified zein can be selected from the commerical prod of protein content 〉=80% (butt), can buy zein from Japan and the pure medicine of light company, U.S. Freeman Industries company.

The technology of extracting kafirin from sorghum seed or sorghum flour is known, as in following document, stating, these documents are incorporated herein by reference: " Emmambux MN.; Taylor JRN.; Sorghumkafirin interaction with various phenolic compounds.J.Sci.Food Agric.; 2003,83:402-407; Gao C., Taylor J., Wellner N., Byaruhanga YB., Parker ML., Mills ENC., Belton PS., Effect of preparation conditions on protein secondary structure andbiofilm formation of Kafirin.J.Agric.Food Chem., 2005,53:306-312; Huang CP., Hejlsoe-Kohsel E., Han XZ., Protelytic activity in sorghum flour and its interferencein protein analysis.Cereal Chem., 2000,77:343-344 ".

The corn protein degradable plastic preparation of compositions is carried out in two steps, and the first step is carried out pre-mixing with grain protein, softening agent, lubricant, oxidation inhibitor and sanitas.The present invention is not very strict to premixed requirement, can adopt the mixing instrument of high-speed mixer or Haake, mixed at room temperature 2～10min under 50～3000r/min rotating speed; Also can the material elementary mixing evenly be got final product by the manual 10～30min that stirs of instrument.Second step was adopted further mixing above-mentioned pre-mixing material of mechanical mixing method, can adopt mill or Banbury mixer, at 10～40 ℃ of following mechanically milling 5～15min, and added sulfhydryl compound in mixing process, obtained the grain protein composition.

Grain protein contains 1～2% halfcystine or Gelucystine.In the grain protein of natural output, protein molecule associates by intramolecularly or intermolecular disulfide bond, forms the huge gluten associated complex of molecular weight.In solution or suspension, adopt the compound such as the mercaptoethanol that contain sulfydryl disulfide linkage can be interrupted, reduce protein molecular weight.In the present invention, one of purpose of mechanically milling is that sulfhydryl compound is evenly dispersed in the corn protein degradable plastic composition; Another purpose is, under strong shearing action, sulfhydryl compound makes that disulfide linkage reduces in the protein molecule,

And make the intermolecular disulfide bond fracture, Rapsyn matter molecule is reduced to the simple protein molecule,

Prot represents protein molecule in the formula, and R-SH represents sulfhydryl compound.That is to say that under the strong shearing condition of the preparation process of protein composition, sulfhydryl compound uses as reductive agent.After the protein reduction, the processing characteristics of protein composition is able to obvious raising.

The preparation of cross-linking type degradable cereal protein plastic is carried out in two steps, and the first step places mould with the grain protein composition, and 1～3min colds pressing under room temperature and 5～20MPa pressure.At room temperature, the grain protein composition has excellent flowability, can realize flowing and mold filling under the effect of relative broad range pressure.Second step was to be heating and curing, and at first temperature was risen to 60～80 ℃, and hot pressing 0～10min rises to temperature 110～140 ℃ then, and hot pressing 10～30min obtains the corn protein degradable plastic goods.The curing of grain protein can be adopted conventional vulcanizing press, and its principle of solidification is

In the hot press moulding moulding process, sulfhydryl compound uses as linking agent.In the present invention, the dimercapto compound can get up a plurality of cross linking of protein molecule, forms more fine and close network structure.

Processing characteristics, water tolerance and the ageing-resistant performance of giving the corn protein degradable plastic excellence are one of keys of the present invention.The use of softening agent and lubricant and the reductive action of sulfhydryl compound make the grain protein composition have excellent processing characteristics, can adopt plastic working conventional equipment moulding press to carry out excipient processing.The use of lubricant and proteinic crosslinked action are greatly improved the water tolerance of corn protein degradable plastic.

The cross-linking type degradable cereal protein plastic that the present invention obtained is implemented crosslinked by disulfide linkage between protein molecule.Under field conditions (factors), these disulfide linkage can rupture, and protein molecule can be hydrolyzed to amino acid.Thereby the cereal protein plastics that is obtained can be degraded fully.

Further specify the present invention below in conjunction with specific embodiment.

Embodiment 1:

With the gluten powder is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

1) takes by weighing 100g gluten powder, 20g glycerine, 0.5g stearic acid and 0.5g 2, the 6-di-tert-butyl-4-methy phenol, place in the high-speed mixer, mixed at room temperature 2min under the 3000r/min rotating speed, the mixture material is placed in the mill, in 10 ℃ of mixing 15min, and in mixing process, add 2g linking agent Dodecyl Mercaptan, obtain the grain protein composition;

2) the grain protein composition is placed GB/T1040-92 plastic tensile performance test Standard Module, adopt the vulcanizing press 3min that under room temperature and 5MPa pressure, colds pressing, temperature is risen to 60 ℃, hot pressing 10min, temperature is risen to 110 ℃ then, hot pressing 10min obtains the corn protein degradable plastic goods after cooling, the demoulding.

Embodiment 2:

With the gluten powder is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

1) takes by weighing 100g gluten powder, 20g glycerine, 0.5g stearic acid and 0.5g 2, the 6-di-tert-butyl-4-methy phenol, place in the high-speed mixer, mixed at room temperature 10min under the 1000r/min rotating speed, the mixture material is placed in the mill, in 40 ℃ of mixing 5min, and in mixing process, add 2g linking agent Dodecyl Mercaptan, obtain the grain protein composition;

2) the grain protein composition is placed GB/T1040-92 plastic tensile performance test Standard Module, adopt the vulcanizing press 1min that under room temperature and 20MPa pressure, colds pressing, temperature is risen to 140 ℃, and hot pressing 30min obtains the corn protein degradable plastic goods after cooling, the demoulding.

Embodiment 3:

With the rice protein powder is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

1) takes by weighing 100g rice protein powder, 100g 1,2-propylene glycol, 1.5g oxystearic acid, 1.5g 2,6-di-t-butyl-4-methylolphenol and 1g Sodium Benzoate, place in the high-speed mixer, mixed at room temperature 5min under the 2000r/min rotating speed places the mixture material in the mill, in 30 ℃ of mixing 10min, and in mixing process, add 1g linking agent 1, obtain the grain protein composition;

2) the grain protein composition is placed GB/T1040-92 plastic tensile performance test Standard Module, adopt the vulcanizing press 3min that under room temperature and 5MPa pressure, colds pressing, temperature is risen to 80 ℃, hot pressing 5min, temperature is risen to 120 ℃ then, hot pressing 20min obtains the corn protein degradable plastic goods after cooling, the demoulding.

Embodiment 4:

With the wheat gliadin is feedstock production cross-linking type degradable cereal protein plastic preparation of compositions method, may further comprise the steps:

1) takes by weighing 100g wheat gliadin, 100g 1, ammediol, 1g n-butyl stearate, 1g tertiarybutylhydroquinone and 0.5g potassium sorbate, place in the high-speed mixer, mixed at room temperature 5min under the 2000r/min rotating speed, the mixture material is placed in the mill,, and in mixing process, add 7g linking agent 1 in 30 ℃ of mixing 10min, the 3-dimercaptopropane obtains the grain protein composition;

2) the grain protein composition is placed GB/T1040-92 plastic tensile performance test Standard Module, adopt the vulcanizing press 2min that under room temperature and 10MPa pressure, colds pressing, temperature is risen to 80 ℃, hot pressing 5min, temperature is risen to 120 ℃ then, hot pressing 20min obtains the corn protein degradable plastic goods after cooling, the demoulding.

Embodiment 5:

With the hordein is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

1) takes by weighing 50g hordein, 30g glycol ether, 0.5g single stearic acid glycerine lipoprotein, 0.5g butylhydroxy anisole and 0.2g sthyl sorbate, place in the mixing instrument of Haake, mixed at room temperature 5min under the 50r/min rotating speed, the mixture material is placed in the mill, in 30 ℃ of mixing 10min, and in mixing process, adding 2g linking agent 1, the 2-succinimide mercaptans obtains the grain protein composition;

2) preparation method of degradable plastics is with embodiment 4.

Embodiment 6:

With the zein is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

1) takes by weighing 50g zein, 30g 1,4-butyleneglycol, 0.5g methyl hydroxystearate, 0.5g tea-polyphenol and 0.2g Sorbic Acid butyl p-hydroxybenzoate, place in the 200ml beaker, the manual 20min that stirs, the mixture material is placed in the mill,, and in mixing process, add 2g linking agent 1 in 30 ℃ of mixing 10min, the 4-succinimide mercaptans obtains the grain protein composition;

2) preparation method of degradable plastics is with embodiment 4.

Embodiment 7:

With the kafirin is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

Replace gluten powder with kafirin, all the other conditions are with embodiment 1.

Embodiment 8～14:

With the gluten powder is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

Respectively with 1,3 butylene glycol, 2,3-butyleneglycol, 1,2,4-trihydroxybutane, 1,2,3-hexanetriol, 1,2,6-hexanetriol, glyceryl monoacetate or glyceryl diacetate replace glycerine, and all the other conditions are with embodiment 1.

Embodiment 15～22:

With the gluten powder is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

With soybean oil, peanut oil, Semen Maydis oil, Rice pollard oil, rapeseed oil, Oleum Gossypii semen, sunflower seed oil or camellia seed oil place of magnesium stearate, all the other conditions are with embodiment 2 respectively.

Embodiment 23～32:

With the rice protein powder is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

Replace 2 with propyl gallate, tocopherol, Progallin A, Tenox PG, Stabilizer GA 8, lauryl gallate, gallic acid octadecyl ester, xitix, Quicifal, D-saccharosonic acid or sodium D-isoascorbate respectively, 6-di-t-butyl-4-methylolphenol, all the other conditions are with embodiment 3.

Embodiment 33～41:

With the wheat gliadin is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

Replace potassium sorbate with dehydroacetic acid (DHA), sodium dehydroacetate, Tegosept M, propylparaben, ethyl p-hydroxybenzoate, Sodium Methyl Hydroxybenzoate, nipagin A sodium, Sodium propyl p-hydroxybenzoate or nipabutyl sodium respectively, all the other conditions are with embodiment 4.

Embodiment 42～56:

With the hordein is the preparation method of feedstock production cross-linking type degradable cereal protein plastic, may further comprise the steps:

Respectively with 2,3-succinimide mercaptans, 1,5-pentane disulfide thioalcohol, 1,6-ethanthiol, 1,7-mercaptan in heptan two, 1, hot two mercaptan, 1 of 2-, hot two mercaptan, 1 of 8-, 9-mercaptan in the ninth of the ten Heavenly Stems two, 1,10-mercaptan in the last of the ten Heavenly stems two, positive hexylmercaptan, uncle's hexylmercaptan, n-heptanthiol, octyl mercaptan, uncle's spicy thioalcohol, positive decyl mercaptan or stearylmercaptan replace 1, the 2-succinimide mercaptans, all the other conditions are with embodiment 5.

Embodiment 57: the mechanical property of cross-linking type gluten powder degradable plastics

Table 1 has compared Young's modulus, tensile strength and the elongation at break of embodiment 1 (see figure 1), embodiment 2 (see figure 2)s, comparative example's 1 (see figure 3) and comparative example's 2 samples that (see figure 4) obtains.Experiment adopts CMT-4204 universal testing machine (material tests company limited is newly thought carefully in Shenzhen) at room temperature and 10mm min with reference to the GB/T1040-92 standard ^-1Carry out under the speed, get 5 sample test results' mean value.

Table 1

	Young's modulus (MPa)	Tensile strength (MPa)	Elongation at break (%)
				Example 1	40.4±1.6	3.1±0.2	112±6
Example 2	42.7±4.4	2.9±0.3	114±10
				Comparative Examples 1	1.05±0.11	0.48±0.08	108±24
Comparative Examples 2	1.60±0.08	0.66±0.07	53.5±6.6

The invention provides a kind of cross-linking type degradable cereal protein plastic and preparation method thereof.Main raw material grain protein involved in the present invention belongs to renewable agricultural resource, wide material sources; The preparation method and the technical process of corn protein degradable plastic involved in the present invention are simple, and low production cost is easy to promotion and implementation.Crosslinked based on the corn protein degradable plastic that the present invention makes by disulfide linkage enforcement between protein molecule, have excellent in water resistance and ageing-resistant performance, and can degrade fully under field conditions (factors).

Claims (8)

1. cross-linking type degradable cereal protein plastic, it is characterized in that it comprises grain protein 100 weight parts, softening agent 20～100 weight parts, lubricant 0.5～1.5 weight part, oxidation inhibitor 0.5～1.5 weight part, sanitas 0～1 weight part and linking agent 1～7 weight part.

2. the preparation method of cross-linking type degradable cereal protein plastic according to claim 1 is characterized in that described grain protein is gluten powder, rice protein powder, wheat gliadin, hordein, zein or kafirin.

3. the preparation method of cross-linking type degradable cereal protein plastic according to claim 1 is characterized in that described softening agent is 1,2-propylene glycol, 1, ammediol, glycol ether, triglycol, 1,4-butyleneglycol, 1,3 butylene glycol, 2,3-butyleneglycol, glycerine, 1,2,4-trihydroxybutane, 1,2,3-hexanetriol, 1,2,6-hexanetriol, glyceryl monoacetate or glyceryl diacetate.

4. the preparation method of cross-linking type degradable cereal protein plastic according to claim 1, it is characterized in that described lubricant is stearic acid, oxystearic acid, n-butyl stearate, single stearic acid glycerine lipoprotein, methyl hydroxystearate, soybean oil, peanut oil, Semen Maydis oil, Rice pollard oil, rapeseed oil, Oleum Gossypii semen, sunflower seed oil or camellia seed oil.

5. the preparation method of cross-linking type degradable cereal protein plastic according to claim 1, it is characterized in that, described oxidation inhibitor is 2,6-di-tert-butyl-4-methy phenol, 2,6-di-t-butyl-4-methylolphenol, tertiarybutylhydroquinone, butylhydroxy anisole, tea-polyphenol, propyl gallate, tocopherol, Progallin A, Tenox PG, Stabilizer GA 8, lauryl gallate, gallic acid octadecyl ester, xitix, Quicifal, D-saccharosonic acid or sodium D-isoascorbate.

6. the preparation method of cross-linking type degradable cereal protein plastic according to claim 1, it is characterized in that described sanitas is Sodium Benzoate, potassium sorbate, sthyl sorbate, Sorbic Acid butyl p-hydroxybenzoate, dehydroacetic acid (DHA), sodium dehydroacetate, Tegosept M, propylparaben, ethyl p-hydroxybenzoate, Sodium Methyl Hydroxybenzoate, nipagin A sodium, Sodium propyl p-hydroxybenzoate or nipabutyl sodium.

7. the preparation method of cross-linking type degradable cereal protein plastic according to claim 1, it is characterized in that, described linking agent is 1,2-dithioglycol, 1,3-dimercaptopropane, 1,4-succinimide mercaptans, 2,3-succinimide mercaptans, 1,5-pentane disulfide thioalcohol, 1,6-ethanthiol, 1,7-mercaptan in heptan two, 1, hot two mercaptan, 1 of 2-, hot two mercaptan, 1 of 8-, 9-mercaptan in the ninth of the ten Heavenly Stems two, 1,10-mercaptan in the last of the ten Heavenly stems two, positive hexylmercaptan, uncle's hexylmercaptan, n-heptanthiol, octyl mercaptan, uncle's spicy thioalcohol, positive decyl mercaptan, Dodecyl Mercaptan or stearylmercaptan.

8. the preparation method of a cross-linking type degradable cereal protein plastic as claimed in claim 1 is characterized in that, it may further comprise the steps:

1) grain protein, polyol plasticiser, lubricant, oxidation inhibitor and sanitas are carried out pre-mixing,, and in mixing process, add linking agent, obtain the grain protein composition then at 10～40 ℃ of mechanically milling 5～15min;

2) the grain protein composition is placed mould, the 1～3min that colds pressing under room temperature and 5～20MPa pressure rises to 60～80 ℃ with temperature, hot pressing 0～10min, temperature is risen to 110～140 ℃ then, hot pressing 10～30min obtains the corn protein degradable plastic goods.

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