CN114369339A

CN114369339A - Production technology and application of low-cost biodegradable material

Info

Publication number: CN114369339A
Application number: CN202110688535.2A
Authority: CN
Inventors: 周曦东; 刘兰英
Original assignee: Beijing Nastek Nano Technology Co ltd
Current assignee: Zhejiang Xingneng Electronic Materials Co ltd
Priority date: 2021-06-18
Filing date: 2021-06-18
Publication date: 2022-04-19

Abstract

The invention discloses a production technology and application of low-cost completely degradable biodegradable plastic, which mainly comprises resin synthesis and granulationModification technology, product production, application and the like, the biodegradable plastic comprises the following components: a thermoplastic resin 100; cellulose plant powder

0.8-40% of a dispersant; 0.5-60 of modifier; filler material

Stabilizer

Description

Production technology and application of low-cost biodegradable material

Technical Field

The invention belongs to the field of synthesis, modification and application of high polymer materials, and particularly relates to a biodegradable polyester composition composite material with excellent thermal-oxidative aging resistance and surface appearance performance and application thereof, wherein the biodegradable resin polybutylene adipate terephthalate (PBAT) is synthesized by a direct esterification method and is compounded with cellulose substances.

Background

Due to the comprehensive excellent performance of the plastic material, the plastic material is widely applied to agriculture and industry and daily life of people, but various plastic products are greatly convenient for people, and the environmental pollution caused by the waste of the plastic products is increasingly serious. Therefore, in recent years, biodegradable plastics have attracted more and more attention and are considered to be an effective way to solve the pollution of plastic wastes, and industrial production of biodegradable plastics is now implemented in countries such as china, the united states, japan and europe, and corresponding products are also made available. In the synthetic biodegradable materials which are industrially produced at present, polybutylene adipate terephthalate (PBAT) is copolyester with aliphatic polyester biodegradation performance and aromatic polyester mechanical property, has good ductility and elongation at break, has good heat resistance and impact resistance, and is very beneficial to processing and forming. The industrial product has stable performance in a dry environment, can be stored and used for a long time, can be completely biodegraded into carbon dioxide and water in soil, seawater and compost after being discarded, and cannot generate environmental pollution. Due to the comprehensive excellent performance of the polybutylene adipate terephthalate, the polybutylene adipate terephthalate can be widely applied to the field of packaging, such as packaging films, lunch boxes, cosmetic bottles, medicine bottles, electronic device packaging and the like; disposable devices, such as disposable eating utensils, disposable medical supplies, and the like; the agricultural field, such as agricultural films, pesticides, fertilizer slow release materials and the like, and the biomedical polymer field. But because the existence of the aromatic chain segment reduces the degradation speed of the copolyester, and simultaneously, the tensile strength is not large, and the application of the material in the field with higher requirements on mechanical properties is limited, the modification of the polybutylene adipate-terephthalate by using a blending means is particularly important for improving the comprehensive properties of the polybutylene adipate-terephthalate.

The natural plant fiber has the advantages of light weight, high strength, good toughness, biodegradability and the like, and modification research based on cellulose is a new active field at present. The preparation of the cellulose modified polymer composite material requires lower energy consumption, and simultaneously reduces the emission of harmful gases. CN104194288A discloses a modified poly (adipic acid)/butylene terephthalate) composite material containing water chestnut white shell fibers and a preparation method thereof, the mechanical properties of the obtained composite material are improved to a certain extent, but the tensile strength is effectively improved, the breaking elongation is reduced, the good toughness of the material is damaged, and the large-scale application of the modified poly (adipic acid)/butylene terephthalate composite material in the industrial production aspect is hindered due to the fact that the requirements on the tolerance and the flexibility of the material in the field of packaging plastics are high. Meanwhile, the preparation process is complex, the dosage is not easy to control from the acquisition of raw materials to the modification and the addition of a coupling agent, an antioxidant, a heat stabilizer and the like, and the labor cost is greatly increased. Therefore, further research and innovative improvements in selecting raw materials, improving processes, improving the overall mechanical properties of the composite material, and the like are needed.

Compared with the traditional cellulose, the nano-cellulose has the characteristics of huge specific surface area, high purity, high polymerization degree, high crystallinity, high strength, high Young modulus and the like, shows extremely high Young modulus, strength and other properties in material synthesis, and has the characteristics of light weight, degradability, good biocompatibility, renewability and the like of a biological material, so that the nano-cellulose has huge application prospects in high-performance composite materials. Meanwhile, the surface of the nano-cellulose contains a large amount of high-purity hydroxyl groups, so that the surface of the nano-cellulose is easy to chemically modify, different characteristics are endowed to the surface, the dispersibility of the nano-cellulose in a hydrophobic matrix material is improved, and the application range of the nano-cellulose is expanded. The potential advantages of nano-new vitamin as a reinforcing material are attracting more and more attention, and the development of the reinforcing material has important significance in the aspects of environmental protection and resource protection.

Polylactic acid (PLA) can be completely biodegraded, is derived from renewable resources such as plants and the like, has the performance similar to that of common plastic polypropylene, such as high modulus, high tensile strength and good processability. However, the brittleness of the polylactic acid is serious, the notch impact strength is less than 3KJ/m2, the wide application of the polylactic acid is severely limited, and the method of adopting multi-component blending modification to improve the toughness of the polylactic acid is the main technical means at present. The biodegradable copolyester is aliphatic copolyester or aliphatic/aromatic copolyester, has complete biodegradation performance, and mainly comprises polybutylene succinate (PBS), poly (butylene adipate-co-terephthalate) (PBAT) and poly (butylene succinate-co-p-adipate) (PBSA). The material is used as a packaging material in engineering, is related to articles for daily use, medical use and agriculture, and has lower cost and stable mechanical property compared with other degradation materials. The biodegradable copolyester and the polylactic acid are blended and modified to effectively improve the performance of the polylactic acid, but the poor compatibility of the PLA and the copolyester causes the mechanical strength of the blend to be reduced more, and the tear strength of the blend is poor when the blend is used as a film or a sheet, so that the use performance is influenced.

CN201210250009.9 discloses a PLA/PBAT blend with high interface compatibility and a preparation method thereof, wherein two chain extenders are adopted to form a PLA and PBAT block copolymer in the blend by adopting different reactivity of different end groups of polyester, the process steps are simplified, the PLA/PBAT blend with high interface compatibility is obtained, but the improvement of the tearing strength of a base material is not mentioned in oCN201310731579.4, a PLA modified material is disclosed, the PBAT is added into the PLA, and the chain extender is used to compatibilize the polymer, so that the prepared material not only retains the characteristics of high strength, high transmittance and high cost performance of the PLA after blow molding film forming, but also improves the flexibility, but the tearing strength of the blend film is still lower.

Polybutylene adipate terephthalate (PBAT) is a copolymer of butylene adipate and butylene terephthalate, having both the properties of PBA and PBT. Polybutylene adipate terephthalate (PBAT) contains flexible aliphatic chains and rigid aromatic chains, thus has high toughness and high temperature resistance, and is one of the most active and best degradable materials for market application in the research of the current biodegradable plastics due to the existence of ester bonds which promote the biodegradability of the polybutylene adipate terephthalate (PBAT). However, during storage and use of the molded product made of the PBAT resin, the molded product made of the PBAT resin is easily degraded during storage and use due to the action of microorganisms, light, radiation, air and the substance environment contacted with the molded product, and the service life of the product is greatly influenced.

In addition, the surface appearance of the film or the product is affected by precipitates precipitated on the surface of the film or the product of a molded product prepared from the PBAT resin under the condition of boiling with 95% ethanol.

The invention is surprisingly found through researches that the service life of the PBAT resin composition can be greatly prolonged and the excellent surface appearance performance of the PBAT resin composition can be ensured by adding a small amount of cyclic ester and iron-containing substances into the PBAT resin composition.

The polyester prepared by the condensation polymerization method is widely applied to various fields of daily life of people as an engineering material, and can be made into materials such as fibers, beverage bottles, films and the like. These polymers are prepared by two processes: esterification or ester exchange of terephthalic acid/aliphatic ester or an esterification product thereof with aliphatic diol, wherein the esterification process usually occurs under high pressure, and the ester exchange process is performed under normal pressure; esterification or vacuum polycondensation of the transesterified product.

The polybutylene terephthalate/butanediol adipate copolyester (PBTA) is a long-chain aliphatic-aromatic copolyester high polymer material obtained by condensing esterification Products of Terephthalic Acid (PTA), Adipic Acid (AA) and 1, 4-T diol (L3-BD). The composite material combines the degradability of aliphatic polyester and the excellent mechanical and thermal properties of aromatic polyester, and is mostly similar to Low Density Polyethylene (LDPE) in physical property from comprehensive performance, so that the composite material is suitable for manufacturing soft products. And simultaneously, the negative influence on the environment is minimized due to the biodegradability of the composite material.

There are three general methods for synthesizing aliphatic-aromatic copolyesters: putting dihydric alcohol, dibasic acid and the like and dimethyl terephthalate (DMT) into a reaction kettle, firstly carrying out ester exchange reaction at a relatively low temperature, then raising the temperature and improving the vacuum degree, and carrying out melt polycondensation reaction; secondly, performing ester exchange reaction on aromatic components such as polyethylene terephthalate (PET) and polymers such as polyethylene glycol (PEG), Polyglycolide (PGA), polylactic acid (PLA), poly (e-caprolactone) (e-PCL) directly at high temperature and high vacuum degree; dissolving ethylene (butylene) terephthalate or its derivative and bis (carpet acid) chloride in organic solvent, and solution polycondensing at proper temperature.

U.S. Pat. No. 5,721,721 to BASF, Germany, discloses an aliphatic-aromatic copolyester in which an aliphatic acid, dimethyl terephthalate (DMT) and 1, 4-T diol (L4-BD) are subjected to esterification and transesterification in steps under the action of tin and titanium compounds, respectively, and the esterification and transesterification products are subjected to copolycondensation together.

The process for the production of aliphatic-aromatic copolyesters by BASF, Germany, is described in U.S. Pat. No. 4,6018004, USA6046248, carried out in two stages. Firstly, esterifying Adipic Acid (AA) and 1, 4-butanediol (1, 4-BD), and using tin dioctoate as a catalyst to obtain an esterification product for later use; then, the esterification product of the first step, dimethyl terephthalate (DMT), 1, 4-butanediol (1, 4-BD) and tetrabutyl titanate are added into another reaction kettle at the same time, the ester exchange of DMT and 1, 4-BD is finished, and the system is vacuumized and polycondensed.

At present, the research on the preparation of PBTA by directly esterifying terephthalic acid (PTA) and 1, 4-butanediol (1, 4-BD) is not reported in a published document. This is mainly because the direct esterification process is generally performed under high pressure and high temperature conditions, so that 1, 4-butanediol is easily dehydrated and cyclized to produce a by-product of the tetrahydrocerate-like pyran (THF), which adversely affects the quality of the product. Compared with the ester exchange process, the direct esterification process has the advantages that the excess of aliphatic diol is less, the feeding is economical, and the generated byproduct water does not generate toxic action on the surrounding production environment like methanol. Therefore, it is desired to provide a method for synthesizing a polyester, which is simple in operation (one-shot charging), reduces the occurrence of side reactions of cyclization of 1, 4-butanediol (normal pressure, low temperature esterification), and improves the molecular weight and whiteness of a polyester resin.

Disclosure of Invention

The invention aims to provide a polybutylene adipate-terephthalate/nanocellulose degradable composite material. The nano-cellulose is used as a filling material of a polymer, can improve the mechanical property of polybutylene adipate terephthalate (PBAT), does not change the crystallization property of the material while improving the toughness, has very obvious social significance, is a novel composite material formed by mixing the polybutylene adipate terephthalate and the nano-cellulose, and can improve the nano-scale uniform dispersion and form stronger interface interaction in a polybutylene adipate terephthalate substrate by modifying the surface of the nano-cellulose, thereby greatly improving the mechanical property and the thermal property of the composite material.

The second purpose of the invention is to provide a poly-catalytic synthesis preparation method of poly-butylene adipate terephthalate degradable resin.

The invention aims to provide a method for synthesizing polybutylene terephthalate/butanediol adipate copolyester (PBTA) under the catalysis of a composite catalyst, the composite catalyst can be used for not only enabling esterification reaction to be carried out at the low temperature of 150-220 ℃, shortening polymerization reaction time, but also enabling PBTA obtained by polymerization to have high intrinsic viscosity and good hue; the invention provides a method for producing a PBTA polymer with high intrinsic viscosity and high whiteness by direct polymerization, wherein esterification reaction is carried out at low temperature and normal pressure, and the generation amount of a by-product, namely, tetrahydrocerate pyrane (THF) is small.

A third object of the present invention is to provide a PBAT resin composition, in which a small amount of a cyclic ester and an iron-containing compound are added to make the PBAT resin composition have a long life and excellent surface appearance.

The invention is realized by the following technical scheme:

1. synthesis of polybutylene adipate terephthalate (PBAT)

The invention takes titanium compound, magnesium compound and organic pulse compound as ternary composite catalyst, the method for catalytic synthesis of PBTA comprises the following steps:

(1) esterification reaction

Directly adding terephthalic acid (PTA), Adipic Acid (AA) and L4-T diol (1, 4-BD) or adding into a reaction kettle together in a mode of preparing into slurry, wherein the gauge pressure is 1MPa (normal pressure),

carrying out esterification reaction at the temperature, removing by-product water to generate terephthalic acid L4-T glycol ester, adipic acid 1, 4-T glycol ester and oligomer thereof, and finishing the esterification reaction when the total esterification rate reaches more than 95%; terephthalic Acid (PTA) to Adipic Acid (AA) in a molar ratio of

The ratio of the sum of the moles of terephthalic acid (PTA) and Adipic Acid (AA) to the moles of 1, 4-butanediol (1, 4-BD) is

(2) Polycondensation reaction

Continuously reducing the pressure of the reaction kettle to high vacuum within 60 minutes

During the process, the by-product 1, 4-butanediol is continuously generated, and the final temperature of the reaction is controlled to be

Then using inert gas to make the reaction kettle return to normal pressure to obtain polymer melt, making the polymer melt undergo the process of casting, granulating so as to obtain the invented product with intrinsic viscosity

And good color phase polybutylene terephthalate/butanediol adipate copolyester (PBTA) slice, high vacuum polycondensation time

And (3) minutes.

Adding a composite catalyst of a titanium compound and a magnesium compound during the feeding in the step (1) or before the pressure reduction operation in the step (2), and adding an organic pulse compound before the pressure reduction operation in the step (2); the composite catalyst is added partially or completely in the step (1), and the rest or the whole of the step (1) is added in the step (2).

2. The following examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following examples. The raw materials adopted by the invention are as follows:

silane coupling agent modified kaolin: KH560 modified corn straw powder with grain size range

Micron size;

silane coupling agent modified white carbon black: KH550 modified wheat straw powder with particle size range

Nano;

alkyl quaternary salt modified montmorillonite: hexadecyl trimethyl string salt modified wood dust with the particle size range of

Detailed description of the preferred embodiments

Example A

A5L stainless steel kettle equipped with a nitrogen inlet, a condensate outlet and a stirrer was charged with 820g of terephthalic acid (PTA), 180g of Adipic Acid (AA) and 383gl, 4-T diol (L, 4-BD), 0.2g of tetrabutyltitanate (corresponding to 200ppm of the total weight of PTA and AA), 0.6g of acu acetate (corresponding to 600ppm of the total weight of PTA and AA). Keeping normal pressure in the kettle, stirring at a constant speed, dewatering when the temperature in the reaction kettle rises to 15CTC, continuously heating and controlling the temperature in the reaction kettle to be not higher than 220 ℃, and finishing the esterification reaction when the water yield of the byproduct of the stuffing in the reaction kettle reaches the theoretical water yield. Continuously adding 0.05g of trimethyl phosphate (corresponding to 50ppm of the total weight of PTA and AA) into the kettle, vacuumizing to reduce the pressure in the polymerization kettle to below 150Pa within 60 minutes, reacting for 85 minutes under the pressure, controlling the reaction final temperature to be 280 ℃, then restoring the reaction system to normal pressure by using nitrogen, and obtaining white polybutylene terephthalate/polybutylene adipate terephthalate copolyester (PBTA) chips after the polymer melt is subjected to tape casting and grain cutting.

Example B

Raw material components are calculated according to parts by weight

According to the mixture ratio in the table, firstly, the biodegradable copolyester is dried for 5 hours in an oven at the temperature of 80 ℃; mechanically blending the dried biodegradable copolyester with an inorganic filler, a lubricant and a compatilizer in a high-speed mixer for 5 minutes; feeding the uniformly mixed material obtained in the step (2) into a double-screw extruder for melting plasticization, extrusion and granulation to obtain biodegradable master batch; the double-screw extruder is a co-rotating parallel double-screw extruder, and the set temperature is as follows: a first area: 60-90 ℃, zone two: 120-150 ℃, three zone: 140 ℃ and 170 ℃, four zones: 170 ℃ and 190 ℃, and five zones: 170 ℃ 190 ℃, and six zones: 170 ℃ and 190 ℃, and a seventh zone: 170 ℃ and 190 ℃, eight zones: 170 ℃ and 190 ℃, nine zones: 170 ℃ and 190 ℃, and a head: 170 ℃ and 190 ℃, screw rotation speed: 300rpm, the screw length-diameter ratio is 40: 1.

Example C

The biodegradable polyester composition obtained in example B was blown on a double-ring film blower with a film thickness of 25 μm, and the air flow rates of the inner and outer air rings were controlled to be within the range

With a blow-up ratio of

The compositions and performance results of the components of the performance examples and the comparative examples of the obtained film show that the ratio of the longitudinal and transverse tearing strength is as follows: part 2, determination of tear resistance of plastic films and sheets according to GB/T16578.2: the Elmendorf method has the advantages that the film thickness is 20-35um, the longitudinal and transverse tearing strength is respectively measured, and the test result calculation proves that the film has good performance and can meet the requirements of various packaging films.

Claims

1. A biodegradable material, the material comprising:

A. the biodegradable resin is mainly polybutylene terephthalate/butanediol adipate copolyester, the PBAT content is 20-80%, the synthesis method is that the phthalic acid, the adipic acid and the 1, 4-butanediol are synthesized by adopting a multi-element composite catalytic direct esterification method under the conditions of certain temperature, pressure and inert gas, wherein the catalyst is a titanium compound, a magnesium compound and an organic lode compound.

B. The natural cellulose nano powder or processing material with the content of 10-60% is derived from various plant oil rich in cellulose such as crop straws, corn cobs, leaves and the like, and is crushed by common crushing, and the particle diameter is 0.5-25 microns.

C. The modifier mainly comprises a reinforcing agent, a compatilizer, a dispersant and a stabilizer, wherein the reinforcing agent is inorganic filler such as kaolin, calcium carbonate, hydrotalcite compounds and the like, and the content of the reinforcing agent is 0.5-5%; the compatilizer is generally oleamide, erucamide and the like, and the content is generally 0.2 to 2.5 percent; the stabilizer is used for improving the light, heat and water resistance of the material, such as an antioxidant, acrylic epoxy resin, cyclic ester, inorganic iron element and the like, and the content of the stabilizer is generally 0.2-5%.

2. The article of claim 1 wherein the biodegradable material comprises polylactic acid (PLA), polyvinyl alcohol (PVA), one, two or three of which are combined with PBAT, and the other type of biodegradable resin is generally 5-15% of the PBAT resin composition of claim 1, wherein the polybutylene adipate terephthalate resin has a melt index of 8g/10min-25g/10min at 190 ℃ and 5Kg load according to GB/T3682-2000 standard.

3. The product of claim 1, wherein the natural cellulose material is selected from modified cellulose such as acid methyl cellulose, plant starch or plant raw powder, preferably plant powder, with particle size of 50-5000 nm.

4. The article of claim 1 wherein the material stability modifier is one or a combination of the two. (1) The best structure of the cyclohexanedicarboxylic lactone compound is as follows:

iron compounds, mainly including various iron salts, iron oxides, iron-organic and iron complexes, etc., copolymers containing epoxy groups and based on styrene, acrylates and/or methacrylates.

5. The PBAT resin composition of claim 1, further comprising other auxiliaries, wherein the other auxiliaries are one or more of antioxidants, dispersants, light stabilizers, impact modifiers, flame retardants, inorganic fillers, optical brighteners, lubricants, plasticizers, antistatic agents, mold release agents, pigments. Wherein the dispersant is silane coupling agent, titanate coupling agent, Nami compound coupling agent, aluminate coupling agent, borate coupling agent, complex coupling agent, magnesium coupling agent, stearic acid or its salt, liquid paraffin, silicone oil, erucamide, oleamide, N, -diethenylene stearamide, ethylenebisoleamide, stearamide, glycerol monooleate, diglycerol Engraulic monooleate, modified triglyceride, behenamide ram, citric acid trioctadecyl ester, N-butyl stearate, stearyl alcohol, monooleate (pentaerythritol glyceryl) monooleate, stearic acid monoglyceride, stearic acid diglyceride, stearic acid triglyceride, dibutyl phthalate, diethyl phthalate, dioctyl terephthalate, butyl oleate, dioctyl adipate, dioctyl azelate, dioctyl sebacate, trioctyl phosphate, dibutyl phthalate, magnesium coupling agent, stearic acid, and stearic acid, and stearic acid, or its salts, and its salts, salts, Triphenyl phosphate, tribasic phosphate, epoxidized soybean oil, octyl epoxystearate, propylene glycol adipate polyester, propylene glycol sebacate polyester, poly-a-methylstyrene, chlorinated paraffin, liquid rubber, epoxy resin, phenolic resin, polyester oil, polyamide, polyurethane and/or phenyl alkyl sulfonate. The inorganic filler is one or a mixture of natural starch, plasticized starch, modified starch, natural fiber or wood powder; the inorganic filler is selected from one or a mixture of talcum powder, montmorillonite, kaolin, chalk, calcium carbonate, graphite, gypsum, conductive carbon black, calcium chloride, ferric oxide, dolomite, silica, wollastonite, titanium dioxide, silicate, mica, glass fiber or mineral fiber.

6. The PBAT resin composition according to any of claims 1-5 having a half-life of > 50 days after thermo-humid ageing in a thermo-hygrostat at 60 ℃ and 60% humidity.

7. The PBAT resin composition of any of claims 1-6, in which the AL value of the PBAT resin composition after boiling in 95% ethanol at 40 ℃ for 240h is < 0.60.

8. The biodegradable material can be used for manufacturing plastic products such as tubular, box-shaped and film-shaped products in the modes of injection molding, extrusion, film blowing and the like, is applied to the fields of various industrial packages, food packages, logistics express delivery, agricultural films and the like, has the characteristics of biodegradability and environmental protection compared with the traditional products, and simultaneously has the obvious advantages of low cost, complete biodegradability, energy conservation, low pollution and the like compared with the common biodegradable plastic products.