CN109177401B - Completely biodegradable blown film, preparation method and application thereof - Google Patents

Abstract

The invention provides a completely biodegradable blown film, a preparation method and application thereof. The film includes an inner layer, a middle layer and an outer layer that are contacted in sequence; in parts by weight, the inner layer includes polylactic acid, polyterephthalic acid - Butylene adipate, talc, blocking agent, and carbon black; both middle and outer layers include polylactic acid, polybutylene terephthalate-adipate, and titanium dioxide; three layers also They all include glycerol monooctaate, acetyl tributyl citrate, ethylene bis-stearic acid amide and chain extender respectively; the opening agent is erucamide or oleic acid amide; the chain extender is styrene-acrylic acid - Copolymer of glycidyl methacrylate and/or styrene-maleic anhydride-glycidyl methacrylate. The films have high tensile elongation at break, pendulum impact strength, tensile strength, Young's modulus and heat seal strength, and remain fully biodegradable.

Description

A completely biodegradable blown film, its preparation method and its application

technical field

The invention belongs to the technical field of polymer materials, and in particular relates to a completely biodegradable blown film, a preparation method and application thereof.

Background technique

Unlike traditional petroleum-based plastics, polybutylene terephthalate-adipate (PBAT) is an aliphatic aromatic copolyester made from petroleum-based resources and consists of two comonomers, one One is a rigid BT segment (butylene terephthalate) composed of terephthalic acid and 1,4-butanediol monomers, and the other is a flexible BA segment (butylene adipate) composed of hexamethylene Acid and 1,4-butanediol monomer composition. PBAT has both the degradability of aliphatic polyesters and the better mechanical properties of aromatic polyesters.

Polylactic acid (PLA) is polymerized from lactic acid obtained by fermentation of plant starch, which is a renewable resource and has biodegradable properties, which is of great significance to protect the environment. Under the increasingly tense situation of petroleum energy, the development and research of PLA resin is particularly important. PLA itself has properties similar to general-purpose plastic polypropylene, such as high modulus, high tensile strength and good processability. However, the brittleness of PLA is serious, and its impact strength is less than 5KJ/m ² , which severely limits its wide application.

Therefore, in view of the serious shortcomings of PLA's brittleness, modification research is actively carried out at home and abroad, and the use of multi-component blending and modification to improve the toughness of PLA is the main technical means at present. Biodegradable PLA resin is a requirement for the preparation of products such as degradable packaging films.

PBAT is biodegradable, with tensile elongation at break up to around 700% and low elastic modulus, so it is considered a good choice for toughening PLA. Their blends are still biodegradable and could theoretically have the high strength of PLA and the high ductility and toughness of PBAT, respectively. However, simple mixing of PLA with other components often does not yield satisfactory properties, as the two components are usually thermodynamically incompatible due to unfavorable interactions between the molecular segments of the components. Immiscible or poor interfacial adhesion. In order to improve the compatibility of polymer blends and increase the interfacial adhesion between the matrix and the dispersed phase, reactive compatibilizers or the addition of compatibilizers are often used to improve compatibility to obtain desirable properties.

The world invention patent WO2018/028513A1 disclosed by Xiong Kai et al. discloses a biodegradable film and its preparation method. After blow molding, a biodegradable blown film with balanced longitudinal and transverse tearing strengths is obtained.

The Chinese invention patent of Qin Wensheng et al. with the application number of 201710167009.5 discloses an enhanced fully biodegradable material and a preparation method thereof. Screw extrusion, followed by blow molding, can significantly improve the tensile strength and elongation at break of the film.

The Chinese invention patents of Mi Qinghua et al. with application numbers 201710572627.8 and 201710572630.X disclose an ultra-thin transparent fully biodegradable film blown film grade material and its preparation method. The method combines PBAT, PLA, reinforced, toughened and transparent. Inorganic hydrophobic nano-silica, or organic Akema AX-8900 or ADX-1200s resin compatibilizer or Hangzhou Aike CE-AZ01 compatibilizer Or several kinds, together with epoxidized soybean oil or silicone oil, extruded by twin-screw, and then processed by blow molding to obtain an ultra-thin, ultra-transparent and fully biodegradable film with a thickness of 5 microns, which can be used for packaging films, shopping bags, and mulch films.

Weraporn Pivsa-Art et al. studied in the journal Energy Procedia (2011, 9:581-588.) to fix the weight ratio of PLA/PBSA at 80/20, and then add the weight ratios of 10%, 20%, 30%, 40%, respectively. %, and 50% of PBAT were extruded and blown into film. The study showed that when the amount of PBAT was 20%, the PLA/PBSA/PBAT blend had the highest tensile strength and impact strength. Scanning electron microscope Excellent compatibility between PLA/PBSA/PBAT blends was shown.

Jeff Schneider et al. reported the PLA/PBAT film modified by glycidolide in the Journal of Applied Polymer Science (2016, DOI: 10.1002/APP.43310.), and the results showed that the modified film had good physical and chemical properties. Mechanical behavior.

Worasak Phetwarotai et al. reported the blending of PLA, PBAT, nucleating agent talc (Talc) and compatibilizer diphenylmethane diisocyanate (MDI) in the Journal of Thermal Analysis and Calorimetry (2016, 126: 1797-1808.) And blown into film, the ratio of PLA/PBAT/Talc/MDI (phr/phr/phr/phr) is 100/0/0/0, 90/10/0/0, 90/10/1/0 respectively , 90/10/1/1, 90/10/1/3, 90/10/1/5, 90/10/1/7, the results show that talc is a good nucleating agent for PLA, Talc and PBAT The addition greatly increased the nucleation rate of PLA, but the addition of the compatibilizer MDI, and the formation of more long-chain compounds would hinder the crystallization behavior of PLA.

Sutinee Girdthep et al. reported in the European Polymer Journal (2016, 82: 244-259.) that when silver-loaded nano-kaolinite was added to the PLA/PBAT film, the degradation time of the film would be delayed.

Si Peng et al. reported in the journal "Plastic Science and Technology" (2015, 43(10): 68-72.) that PLA and PBAT were blended, extruded and blown using dibenzoyl peroxide (BOP) as the interfacial compatibilizer. Plastic film, the proportion of PLA/PBAT/antioxidant 1010/BOP (phr/phr/phr/phr) is 55/45/0.5/1, 45/55/0.5/1, 35/65/0.5/ 1. The results show that the film has strong tensile strength and tear strength, and when the PBAT increases to a certain extent, the film has a better elongation at break.

Under the premise of advocating green environmental protection and improving the ecological environment in the current world, biodegradable films have a broad space for development. Modifying polylactic acid and researching biodegradable films with better production performance and lower prices are the future development trends in the field of polylactic acid films.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a fully biodegradable blown film, its preparation method and its application, the film has high tensile elongation at break and resistance to pendulum impact strength.

The present invention provides a fully biodegradable blown film, comprising an inner layer, a middle layer and an outer layer in contact with each other in sequence;

In parts by weight, the inner layer includes 10 to 25 parts of polylactic acid, 61.8 to 88.95 parts of polybutylene terephthalate-adipate, 0.1 to 2 parts of a compatibilizer, and 0.1 to 25 parts of a plasticizer. 5 parts, 0.1-3 parts of nucleating agent, 0.05-0.2 parts of chain extender, 0.1-1 part of opening agent, 0.1-2 parts of lubricant and 0.2-2 parts of carbon black;

The middle layer includes 10-25 parts of polylactic acid, 52.8-83.25 parts of polybutylene terephthalate-adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, and 0.1-2 parts of lubricant , 0.05～0.2 part of chain extender and 6～12 parts of titanium dioxide;

The outer layer includes 15-30 parts of polylactic acid, 53.8-82.65 parts of polybutylene terephthalate-adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, and 0.1-2 parts of lubricant parts, 0.05-0.2 parts of chain extender and 2-6 parts of titanium dioxide;

The compatibilizer is glycerol monooctaate; the plasticizer is acetyl tributyl citrate; the lubricant is ethylene bis-stearic acid amide; the opening agent is erucamide or oleic acid amide; The agent is talc powder; the chain extender is a copolymer of styrene-acrylic acid-glycidyl methacrylate and/or a copolymer of styrene-maleic anhydride-glycidyl methacrylate.

Preferably, the thickness of the fully biodegradable blown film is 0.05-0.06 mm.

Preferably, the polylactic acid is the polylactic acid of the model REVODE110;

The polyterephthalate-adipate-butylene glycol ester is polyterephthalate-adipate-butylene glycol ester of model TH801T.

Preferably, the type of the chain extender is ADR4368 and/or ADR4370.

The present invention provides a preparation method of the fully biodegradable blown film described in the above technical solution, comprising the following steps:

10-25 parts of polylactic acid, 61.8-88.95 parts of polybutylene terephthalate-adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-3 parts of nucleating agent , 0.05-0.2 part of chain extender, 0.1-1 part of opening agent and 0.2-2 part of carbon black are mixed, melted, extruded and pelletized to obtain inner layer resin;

10-25 parts of polylactic acid, 52.8-83.25 parts of polybutylene terephthalate-adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-2 parts of lubricant, 0.05-0.2 part of chain extender and 6-12 parts of titanium dioxide are mixed, melted, extruded and pelletized to obtain a middle-layer resin;

15-30 parts of polylactic acid, 53.8-82.65 parts of polybutylene terephthalate-adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-2 parts of lubricant, 0.05-0.2 part of chain extender and 2-6 parts of titanium dioxide are mixed, melted, extruded and pelletized to obtain outer layer resin;

The inner layer resin, the middle layer resin and the outer layer resin are co-extruded and blown into a film to obtain a completely biodegradable blown film.

Preferably, the temperature of the extrusion granulation is: the first zone: 120-140°C, the second zone: 150-170°C, the third zone: 160-180°C, the fourth zone: 170-190°C, the fifth zone: 170-170°C 190℃, 6th zone: 170～190℃, 7th zone: 170～190℃, 8th zone: 170～190℃, 9th zone: 170～190℃, 10th zone: 170～190℃, nose: 170～190℃ .

Preferably, when the film is formed by blowing, the temperature of the inner layer is: the first zone: 155-160°C, the second zone: 165-170°C, the third zone: 165-180°C, the fourth zone: 165-180°C, the fifth zone: 165-180°C Zone: 160～175℃;

The set temperature of the middle layer is: Zone 1: 155-160℃, Zone 2: 165-170℃, Zone 3: 165-180℃, Zone 4: 165-180℃, Zone 5: 160-175℃;

The set temperature of the outer layer is: zone 1: 155-160°C, zone 2: 165-170°C, zone 3: 165-180°C, zone 4: 165-180°C, zone 5: 160-175°C.

The present invention provides a fully biodegradable bag, which is prepared from the fully biodegradable film described in the above technical solution or the fully biodegradable film prepared by the preparation method described in the above technical solution.

The invention provides a completely biodegradable blown film, comprising an inner layer, a middle layer and an outer layer that are in contact with each other in sequence; in parts by weight, the inner layer comprises 10-25 parts of polylactic acid, poly(ethylene terephthalate) 61.8-88.95 parts of diacid-butanediol ester, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-3 parts of nucleating agent, 0.05-0.2 part of chain extender, 0.1-1 part of opening agent , 0.1-2 parts of lubricant and 0.2-2 parts of carbon black; the middle layer includes 10-25 parts of polylactic acid, 52.8-83.25 parts of polybutylene terephthalate-adipate, and 0.1-2 parts of compatibilizer , 0.1-5 parts of plasticizer, 0.1-2 parts of lubricant, 0.05-0.2 parts of chain extender and 6-12 parts of titanium dioxide; the outer layer includes 15-30 parts of polylactic acid, polyterephthalic acid-adipic acid -53.8-82.65 parts of butanediol ester, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-2 parts of lubricant, 0.05-0.2 parts of chain extender and 2-6 parts of titanium dioxide; the The compatibilizer is glycerol monooctaate; the plasticizer is acetyl tributyl citrate; the lubricant is ethylene bis-stearic acid amide; the opening agent is erucamide or oleic acid amide; the nucleating agent is Talc; the chain extender is a copolymer of styrene-acrylic acid-glycidyl methacrylate and/or a copolymer of styrene-maleic anhydride-glycidyl methacrylate. The present invention adopts polyterephthalic acid-adipate-butylene glycol ester as the toughening agent of polylactic acid, glycerol monooctaate as the compatibilizing agent, and uses styrene-acrylic acid-glycidyl methacrylate as the compatibilizer. Ester copolymers and/or styrene-maleic anhydride-glycidyl methacrylate copolymers are chain extenders, and together with additives, the synergistic use can effectively improve the tensile fracture of fully biodegradable blown films Elongation and Pendulum Impact Strength. The synergistic use of chain extenders and compatibilizers can improve the melt strength of the film, while ensuring the processability of the film. Dispersibility in blown film resins. The films also have high tensile strength, Young's modulus and heat seal strength, and remain fully biodegradable. The experimental results show that the tensile strength in the transverse direction is 20.3-23.7MPa, and the tensile strength in the longitudinal direction is 27.4-33.6MPa; the elongation at break in the transverse direction is 310.9-560.7%, and the elongation at break in the longitudinal direction is 169.8-284.1%; The transverse Young's modulus is 393.7-782.4MPa, the longitudinal Young's modulus is 541.8-1182.3MPa; the transverse right-angle tear strength is 65.6-113.7KN/m, and the longitudinal right-angle tear strength is 85.9-121.4KN/ m; heat sealing strength is 21.3～26.1N/15mm; pendulum impact strength is 0.82～1.18J.

Detailed ways

The present invention provides a fully biodegradable blown film, comprising an inner layer, a middle layer and an outer layer in contact with each other in sequence;

In parts by weight, the inner layer includes 10 to 25 parts of polylactic acid, 61.8 to 88.95 parts of polybutylene terephthalate-adipate, 0.1 to 2 parts of a compatibilizer, and 0.1 to 25 parts of a plasticizer. 5 parts, 0.1-3 parts of nucleating agent, 0.05-0.2 parts of chain extender, 0.1-1 part of opening agent, 0.1-2 parts of lubricant and 0.2-2 parts of carbon black;

The middle layer includes 10-25 parts of polylactic acid, 52.8-83.25 parts of polybutylene terephthalate-adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, and 0.1-2 parts of lubricant , 0.05～0.2 part of chain extender and 6～12 parts of titanium dioxide;

The outer layer includes 15-30 parts of polylactic acid, 53.8-82.65 parts of polybutylene terephthalate-adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, and 0.1-2 parts of lubricant parts, 0.05-0.2 parts of chain extender and 2-6 parts of titanium dioxide;

The compatibilizer is glycerol monooctaate; the plasticizer is acetyl tributyl citrate; the lubricant is ethylene bis-stearic acid amide; the opening agent is erucamide or oleic acid amide; The agent is talc; the chain extender is the copolymer of styrene-acrylic acid-glycidyl methacrylate (ADR-4368) and/or the copolymer of styrene-maleic anhydride-glycidyl methacrylate ( ADR-4370).

The present invention adopts polyterephthalic acid-adipate-butylene glycol ester as the toughening agent of polylactic acid, glycerol monooctaate as the compatibilizing agent, and uses styrene-acrylic acid-glycidyl methacrylate as the compatibilizer. Ester copolymers and/or styrene-maleic anhydride-glycidyl methacrylate copolymers are chain extenders, and together with additives, the synergistic use can effectively improve the tensile fracture of fully biodegradable blown films Elongation and Pendulum Impact Strength. The synergistic use of chain extenders and compatibilizers can improve the melt strength of the film, while ensuring the processability of the film. Dispersibility in blown film resins.

In the present invention, the polylactic acid is preferably the model REVODE110. The polybutylene terephthalate-adipate is preferably polybutylene terephthalate-adipate with a model of TH801T.

In the present invention, the polybutylene terephthalate-adipate (PBAT) is a copolyester of adipic acid, terephthalic acid and butanediol, and has both polybutylene adipate Ester (PBA) and polybutylene terephthalate (PBT) are characterized by good ductility and elongation at break, good heat resistance and impact properties, and excellent biodegradation It is very active in biodegradable plastic research and one of the best biodegradable materials in the market. However, the compatibility between PBAT and polylactic acid PLA is poor, lack of entanglement between molecular chains, easy phase separation during the blown film processing, insufficient transverse tensile strength of the film, resulting in the cracking of the blown film bubble.

In the present invention, the compatibilizer is glycerol monooctaate (GMS), which is a yellowish waxy solid or flake, and contains a small amount of diester and triester in addition to the monoester, It is tasteless, odorless and non-toxic; its chemical structure has hydrophilic hydroxyl and lipophilic long-chain alkyl functional groups, which can improve the compatibility of PLA and PBAT, play the role of compatibilizer and lubricant, and help reduce PLA The viscosity of the /PBAT blend improves the processing fluidity of the blend system, especially the fluidity during the drawing process of the melt from the die head of the film blowing machine during the film blowing process, and the melt strength and melt flow rate. Controlled within a reasonable and effective blown film processing range.

In the present invention, the chain extender is a copolymer of styrene-acrylic acid-glycidyl methacrylate and/or a copolymer of styrene-maleic anhydride-glycidyl methacrylate; chain extender It contains epoxy functional groups, which can react with the terminal hydroxyl and carboxyl groups of PBAT and PLA, and bind to the end of different macromolecular fragments (carboxyl and hydroxyl groups in polyester). Multifunctional additives, thereby extending the polymer molecular chain and increasing the The average molar mass of the polymer, and can also be used as a reactive compatibilizer in the blend to link PLA and PBAT molecular chains together, improve the entanglement of PLA and PBAT molecular chains, and improve the PLA/PBAT blend. Melt strength and viscosity, improve the compatibility of PLA with PBAT.

In the invention, the chain extender and the compatibilizer GMS are used synergistically, so as to improve the melt strength of the blending system, at the same time, the processability of the film is ensured, and under the synergistic effect of other additives, the titanium dioxide or carbon black can be improved in Dispersibility in PLA/PBAT blown film resins.

In the present invention, the plasticizer is acetyl tributyl citrate (ATBC). The plasticizer can effectively improve the tensile elongation at break and the impact strength of the PLA film, maintain the flexibility of the film, and solve the brittle defect of the express bag film.

In the present invention, the lubricant is ethylene bis-stearic acid amide, which is beneficial to the extrusion of the special resin for modified polylactic acid blown film and the blow molding of the blown film, and to improve the surface smoothness of the film.

In the present invention, the opening agent is erucamide (EA) or oleic acid amide; the opening agent can improve the opening of the film and avoid the mutual interaction of the two layers of the blown film during the rolling and winding process. glue.

The nucleating agent is talc. The talc powder is a kind of auxiliary agent with environmental protection, excellent performance and low price; adding talc powder to the plastic film can be used as a high-efficiency nucleating agent of polylactic acid, reducing the size of crystal grains of polylactic acid and increasing the density of crystal nuclei. , Improve the strength and heat resistance of the film, and also significantly improve the waterproof performance and anti-aging performance.

In the present invention, the carbon black is used to improve the light blocking performance of the express bag film, avoid visible light transmission, and protect the safety of mail. The titanium dioxide can improve the whiteness of the film and at the same time hide the black color of the inner layer of the express bag, which is beneficial to improve the appearance of the express bag.

In the present invention, the thickness of the fully biodegradable blown film is preferably 0.05-0.06 mm.

The fully biodegradable blown film is a fully biodegradable film whose outer layer is off-white and the inner layer is black. All components used in the film can be completely biodegraded, the film has a wide range of applications, can replace PE, and can be made into various environmentally friendly express packaging bags, with a broad market prospect. The industrialization of biodegradable materials and express bags is conducive to the long-term development of energy and material resources, solves white pollution, and promotes the development of new environmentally friendly materials industry, which is of great economic and social significance.

The present invention provides a preparation method of the fully biodegradable blown film described in the above technical solution, comprising the following steps:

10-25 parts of polylactic acid, 61.8-88.95 parts of polybutylene terephthalate-adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-3 parts of nucleating agent , 0.05-0.2 part of chain extender, 0.1-1 part of opening agent and 0.2-2 part of carbon black are mixed, melted, extruded and pelletized to obtain inner layer resin;

10-25 parts of polylactic acid, 52.8-83.25 parts of polybutylene terephthalate-adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-2 parts of lubricant, 0.05-0.2 part of chain extender and 6-12 parts of titanium dioxide are mixed, melted, extruded and pelletized to obtain a middle-layer resin;

15-30 parts of polylactic acid, 53.8-82.65 parts of polybutylene terephthalate-adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-2 parts of lubricant, 0.05-0.2 part of chain extender and 2-6 parts of titanium dioxide are mixed, melted, extruded and pelletized to obtain outer layer resin;

The inner layer resin, the middle layer resin and the outer layer resin are co-extruded and blown into a film to obtain a completely biodegradable blown film.

In the present invention, the inner layer resin, the middle layer resin and the outer layer resin are extruded and pelletized by a twin-screw extruder; when extruding and pelletizing, the set temperature of the twin-screw extruder is: one zone: 120～ 140℃, Zone 2: 150～170℃, Zone 3: 160～180℃, Zone 4: 170～190℃, Zone 5: 170～190℃, Zone 6: 170～190℃, Zone 7: 170～190℃ , Eight zone: 170～190℃, Nine zone: 170～190℃, Tenth zone: 170～190℃, Head: 170～190℃, Screw speed: 200～400rpm.

Film forming machine is used for blow molding. When blowing into a film, the set temperature of the film blowing machine is:

Inner layer: Zone 1: 155～160℃, Zone 2: 165～170℃, Zone 3: 165～180℃, Zone 4: 165～180℃, Zone 5: 160～175℃;

Middle layer: Zone 1: 155～160℃, Zone 2: 165～170℃, Zone 3: 165～180℃, Zone 4: 165～180℃, Zone 5: 160～175℃;

Outer layer: Zone 1: 155-160℃, Zone 2: 165-170℃, Zone 3: 165-180℃, Zone 4: 165-180℃, Zone 5: 160-175℃;

Mold body: 160～175℃; Die mouth: 160～175℃;

The inner screw speed: 50～300rpm, the middle screw speed: 50～300rpm, the outer screw speed: 50～300rpm, the traction speed is 10～20m/min, the inflation ratio is 2～6.

The invention adopts the three-layer co-extrusion technology to reasonably optimize the composition ratio of each layer of PLA and PBAT, so that the composition ratio of the inner, middle and outer three layers of PLA and PBAT is in a relatively close range, so as to avoid delamination between the layers; The synergistic effect of the auxiliary agents ensures the consistency of the film blowing temperature and melt strength during the co-extrusion film blowing process of each layer during the film blowing process, and is conducive to ensuring the mechanical properties of the film.

The present invention provides a fully biodegradable bag, which is prepared from the fully biodegradable film described in the above technical solution or the fully biodegradable film prepared by the preparation method described in the above technical solution.

In the present invention, the preparation method of the fully biodegradable bag preferably includes the following steps:

Printing and winding the fully biodegradable film to obtain the printed film;

The printed film is coated with glue during the drawing process, and the release film is simultaneously covered with the glue surface, and then heat-sealed and cut to obtain a complete biodegradable bag.

In the present invention, during the drawing process of the film after printing, the glue is applied through the sizing port, and the sealing glue is applied to the edge of the film, and the release film is simultaneously covered on the glue surface on the glue surface. . The temperature of the heat sealing is preferably 300-400°C; the cutting speed is preferably 100-150 pieces/min.

In order to further illustrate the present invention, a fully biodegradable film provided by the present invention, its preparation method and its application are described in detail below with reference to the examples, but they should not be construed as limiting the protection scope of the present invention.

The PLA in the following examples was purchased by Zhejiang Hisun Biomaterials Co., Ltd., and the model was REVODE110; PBAT was purchased by Xinjiang Lanshan Tunhe Polyester Co., Ltd., the model was TH801T; the chain extender was purchased by BASF, and the model was ADR -4370 or ADR-4368. The tensile properties of the films in the following examples are tested according to the standard of GB/T 1010.3-2006; the tear strength is tested according to the standard of QB/T 1130-91; and the heat sealing strength is tested according to the standard of ASTMF88-05.

Example 1

The invention provides a completely biodegradable film, the composition of the formula and the proportion of parts by mass are:

Inner resin: 20 parts of PLA; 71.25 parts of PBAT; 0.6 parts of carbon black; 2 parts of compatibilizer GMS; 2 parts of plasticizer ATBC; 1 part of lubricant EBS; 1 part of opening agent EA; 2 parts of nucleating agent talc.

PLA, PBAT, carbon black, GMS, ATBC, EA, EBS, ADR and talc were weighed according to the above formula, and the components were mechanically blended for 5 minutes. The conditions for granulation are: the set temperature of the twin-screw extruder is: zone one: 120-140°C, zone two: 150-170°C, zone three: 160-180°C, zone four: 170-190°C, Five zone: 170～190℃, six zone: 170～190℃, seven zone: 170～190℃, eighth zone: 170～190℃, head: 170～190℃, screw speed: 100～300rpm.

Middle resin: 20 parts of PLA; 64.95 parts of PBAT; 10 parts of titanium dioxide; 1 part of compatibilizer GMS; 3 parts of plasticizer ATBC; 1 part of lubricant EBS; 0.05 part of chain extender 4370 ADR;

PLA, PBAT, titanium dioxide, GMS, ATBC, EBS and ADR were weighed according to the above formula, and the components were mechanically blended for 5 minutes. For: the set temperature of the twin-screw extruder is: the first zone: 120～140℃, the second zone: 150～170℃, the third zone: 160～180℃, the fourth zone: 170～190℃, the fifth zone: 170～170℃ 190℃, six zones: 170～190℃, seven zones: 170～190℃, eight zones: 170～190℃, head: 170～190℃, screw speed: 100～300rpm.

Outer resin: 25 parts of PLA; 66.8 parts of PBAT; 4 parts of titanium dioxide; 1 part of compatibilizer GMS; 2 parts of plasticizer ATBC; 1 part of lubricant EBS; 0.2 part of chain extender 4370 ADR;

PLA, PBAT, titanium dioxide, GMS, ATBC, EBS and ADR were weighed according to the above formula, and the components were mechanically blended for 5 minutes. For: the set temperature of the twin-screw extruder is: the first zone: 120～140℃, the second zone: 150～170℃, the third zone: 160～180℃, the fourth zone: 170～190℃, the fifth zone: 170～170℃ 190℃, six zones: 170～190℃, seven zones: 170～190℃, eight zones: 170～190℃, head: 170～190℃, screw speed: 100～300rpm.

The obtained inner layer, middle layer and outer three-layer blown film special resin were dried in a constant temperature oven at 80°C for 5 hours respectively, and then added to the inner, middle and outer hoppers of the three-layer co-extrusion blown film machine respectively. middle.

The setting temperature of the film blowing machine is:

Inner layer: Zone 1: 155～160℃, Zone 2: 165～170℃, Zone 3: 165～180℃, Zone 4: 165～180℃, Zone 5: 160～175℃;

Middle layer: Zone 1: 155～160℃, Zone 2: 165～170℃, Zone 3: 165～180℃, Zone 4: 165～180℃, Zone 5: 160～175℃;

Outer layer: Zone 1: 155～160℃, Zone 2: 165～170℃, Zone 3: 165～180℃, Zone 4: 165～180℃, Zone 5: 160～175℃;

Mold body: 160～175℃; Die mouth: 160～175℃.

The inner screw speed: 50～300rpm, the middle screw speed: 50～300rpm, the outer screw speed: 50～300rpm, the traction speed is 10～20m/min, and the inflation ratio is 2～6.

The film thickness was controlled at 0.05-0.06 mm, and the mechanical properties of the film were tested. The test results are listed in Table 1.

Table 1 Performance test results of the fully biodegradable films prepared in Examples 1 to 5 of the present invention

As can be seen from Table 1: using the express bag film provided by the present invention, along with the increase of the content of PBAT, the tensile elongation at break and the anti-pendulum impact strength of the blend can be improved, but its tensile strength, Young's Modulus and tear strength are reduced to some extent.

Example 2:

The invention provides a completely biodegradable film, the composition of the formula and the proportion of parts by mass are:

Inner resin: 10 parts of PLA; 81.9 parts of PBAT; 0.6 parts of carbon black; 1 part of compatibilizer GMS; 2 parts of plasticizer ATBC; 1 part of lubricant EBS; 1 part of opening agent EA; 2.4 parts of nucleating agent talc.

Middle layer resin: 10 parts of PLA; 74.9 parts of PBAT; 10 parts of titanium dioxide; 1 part of compatibilizer GMS; 3 parts of plasticizer ATBC; 1 part of lubricant EBS; 0.1 part of chain extender 4368 ADR.

Outer resin: 15 parts of PLA; 76.3 parts of PBAT; 4 parts of titanium dioxide; 0.5 part of compatibilizer GMS; 3 parts of plasticizer ATBC; 1 part of lubricant EBS; 0.2 part of chain extender 4368 ADR.

The mixing and processing conditions of the blown film resins of the inner, middle and outer layers are the same as those in Example 1.

The setting temperature of the film blowing machine is the same as that of Example 1.

The film thickness was controlled at 0.05-0.06 mm, and the mechanical properties of the film were tested. The test results are listed in Table 1.

Example 3:

The invention provides a completely biodegradable film, the composition of the formula and the proportion of parts by mass are:

Inner resin: PLA 25 parts; PBAT 66.85 parts; carbon black 0.6 parts; compatibilizer GMS 1 part; plasticizer ATBC 2 parts; lubricant EBS 1 part; opening agent EA 1 part; chain extender 4370 ADR 0.15 parts; nucleating agent talc 2.4 parts.

Middle layer resin: 25 parts of PLA; 58.9 parts of PBAT; 10 parts of titanium dioxide; 1 part of compatibilizer GMS; 4 parts of plasticizer ATBC; 1 part of lubricant EBS; 0.1 part of chain extender 4370 ADR;

Outer resin: 30 parts of PLA; 60.3 parts of PBAT; 4 parts of titanium dioxide; 0.5 part of compatibilizer GMS; 4 parts of plasticizer ATBC; 1 part of lubricant EBS; 0.2 part of chain extender 4370 ADR.

The mixing and processing conditions of the blown film resins of the inner layer, the middle layer and the outer layer are the same as those in Example 1.

The setting temperature of the film blowing machine is the same as that of Example 1.

The film thickness was controlled at 0.05-0.06 mm, and the mechanical properties of the film were tested. The test results are listed in Table 1.

Example 4:

The invention provides a completely biodegradable film, the composition of the formula and the proportion of parts by mass are:

Inner layer resin: PLA 15 parts; PBAT 77.7 parts; carbon black 0.6 parts; compatibilizer GMS 0.5 parts; plasticizer ATBC 2 parts; lubricant EBS 1 part; ; 2 parts of nucleating agent talc.

Middle resin: 20 parts of PLA; 61.8 parts of PBAT; 12 parts of titanium dioxide; 1 part of compatibilizer GMS; 4 parts of plasticizer ATBC; 1 part of lubricant EBS; 0.2 part of chain extender 4370 ADR;

Outer resin: 20 parts of PLA; 70.9 parts of PBAT; 4 parts of titanium dioxide; 1 part of compatibilizer GMS; 3 parts of plasticizer ATBC; 1 part of lubricant EBS; 0.1 part of chain extender 4370 ADR.

The mixing and processing conditions of the blown film resins of the inner layer, the middle layer and the outer layer are the same as those in Example 1.

The setting temperature of the film blowing machine is the same as that of Example 1.

The film thickness was controlled at 0.05-0.06 mm, and the mechanical properties of the film were tested. The test results are listed in Table 1.

Example 5:

The invention provides a completely biodegradable film, the composition of the formula and the proportion of parts by mass are:

Inner layer resin: PLA 15 parts; PBAT 76.85 parts; carbon black 0.6 parts; compatibilizer GMS 1 part; plasticizer ATBC 3 parts; lubricant EBS 1 part; 05 parts; 2 parts of nucleating agent talc.

Middle layer resin: 20 parts of PLA; 65.3 parts of PBAT; 10 parts of titanium dioxide; 0.5 parts of compatibilizer GMS; 3 parts of plasticizer ATBC; 1 part of lubricant EBS; 0.2 part of chain extender 4370 ADR;

Outer resin: 25 parts of PLA; 66.9 parts of PBAT; 4 parts of titanium dioxide; 1 part of compatibilizer GMS; 2 parts of plasticizer ATBC; 1 part of lubricant EBS; 0.1 part of chain extender 4370 ADR.

The compounding and processing conditions of the inner layer, middle layer and outer layer blown film resin are the same as in Example 1.

The setting temperature of the film blowing machine is the same as that of Example 1.

The film thickness was controlled at 0.05-0.06 mm, and the mechanical properties of the film were tested. The test results are listed in Table 1.

Comparative Example 1

In contrast to the embodiment of the present invention 5, the plasticizer selects polyethylene glycol to replace acetyl tributyl citrate, and the composition of its formula and the proportion of parts by mass are:

Inner layer resin: 15 parts of PLA; 76.85 parts of PBAT; 0.6 part of carbon black; 1 part of compatibilizer GMS; 3 parts of plasticizer polyethylene glycol (molecular weight 1500 g/mol); 1 part of lubricant EBS; parts; chain extender 4370 type ADR 0.05 parts; nucleating agent talcum powder 2 parts.

Middle resin: 20 parts of PLA; 65.3 parts of PBAT; 10 parts of titanium dioxide; 0.5 parts of compatibilizer GMS; 3 parts of plasticizer polyethylene glycol (molecular weight 1500 g/mol); 1 part of lubricant EBS; ADR 0.2 copies;

Outer resin: 25 parts of PLA; 66.9 parts of PBAT; 4 parts of titanium dioxide; 1 part of compatibilizer GMS; 2 parts of plasticizer polyethylene glycol (molecular weight 1500 g/mol); 1 part of lubricant EBS; chain extender 4370 Type ADR 0.1 copies.

The film thickness was controlled at 0.05-0.06 mm, and the mechanical properties of the film were tested. The test results are listed in Table 2.

Comparative Example 2

As the comparative example of embodiment 3, the complete biodegradable film of the present invention, its formula removes chain extender, and its composition and mass fraction ratio are:

Inner resin: 25 parts of PLA; 67 parts of PBAT; 0.6 parts of carbon black; 1 part of compatibilizer GMS; 2 parts of plasticizer ATBC; 1 part of lubricant EBS; 1 part of opening agent EA;

Middle resin: 25 parts of PLA; 59 parts of PBAT; 10 parts of titanium dioxide; 1 part of compatibilizer GMS; 4 parts of plasticizer ATBC; 1 part of lubricant EBS;

Outer layer resin: 30 parts of PLA; 60.5 parts of PBAT; 4 parts of titanium dioxide; 0.5 parts of compatibilizer GMS; 4 parts of plasticizer ATBC; 1 part of lubricant EBS.

The mixing and processing conditions of the blown film resins of the inner layer, the middle layer and the outer layer are the same as those in Example 1.

The setting temperature of the film blowing machine is the same as that of Example 1.

The film thickness was controlled at 0.05-0.06 mm, and the mechanical properties of the film were tested. The test results are listed in Table 2.

Table 2 Performance test results of films prepared in Comparative Examples 1-2

By comparing the analysis results of Comparative Example 1 and Example 5, it can be found that after only changing the plasticizer from acetyl tributyl citrate to polyethylene glycol, the tensile strength and elongation at break of the film bag product performance , right-angle tear strength, heat sealing strength, and anti-pendulum impact strength all decreased by about 10%, indicating that acetyl tributyl citrate has better plasticizing effect than polyethylene glycol in the blend system of the present invention.

Comparing the analysis results of Comparative Example 2 and Example 3, it can be found that the tensile strength, elongation at break, right-angle tear strength and resistance to pendulum impact of the film bag product are not added without chain extender 4370 ADR. The strength decreased by about 5%-10%, and the heat sealing strength decreased by about 20%, indicating that the chain extender 4370 has better chain extension effect in the blend system of the present invention, and can improve the comprehensive mechanical properties of the film bag.

It can be seen from the above examples that the present invention provides a completely biodegradable blown film, including an inner layer, a middle layer and an outer layer that are in contact with each other in sequence; in parts by weight, the inner layer comprises 10-25 parts of polylactic acid, poly 61.8-88.95 parts of terephthalic acid-adipate-butanediol, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-3 parts of nucleating agent, 0.05-0.2 part of chain extender, 0.1-1 part of opening agent, 0.1-2 parts of lubricant and 0.2-2 parts of carbon black; the middle layer includes 10-25 parts of polylactic acid, 52.8-83.25 parts of poly(terephthalate-adipate-butylene glycol), 0.1-2 parts of container, 0.1-5 parts of plasticizer, 0.1-2 parts of lubricant, 0.05-0.2 parts of chain extender and 6-12 parts of titanium dioxide; the outer layer includes 15-30 parts of polylactic acid, polyparaphenylene Diformic acid-adipate-butanediol 53.8-82.65 parts, compatibilizer 0.1-2 parts, plasticizer 0.1-5 parts, lubricant 0.1-2 parts, chain extender 0.05-0.2 parts and titanium dioxide 2 parts ～6 parts; the compatibilizer is glycerol monostearate; the plasticizer is acetyl tributyl citrate; the lubricant is ethylene bis-stearic acid amide; the opening agent is erucamide or oleic acid amide; the nucleating agent is talc; the chain extender is a copolymer of styrene-acrylic acid-glycidyl methacrylate and/or a copolymer of styrene-maleic anhydride-glycidyl methacrylate. The present invention adopts polyterephthalic acid-adipate-butylene glycol ester as the toughening agent of polylactic acid, glycerol monooctaate as the compatibilizing agent, and uses styrene-acrylic acid-glycidyl methacrylate as the compatibilizer. Ester copolymers and/or styrene-maleic anhydride-glycidyl methacrylate copolymers are chain extenders, and together with additives, the synergistic use can effectively improve the tensile fracture of fully biodegradable blown films Elongation and Pendulum Impact Strength. The synergistic use of chain extenders and compatibilizers can improve the melt strength of the film, while ensuring the processability of the film. Dispersibility in blown film resins. The films also have high tensile strength, Young's modulus and heat seal strength, and remain fully biodegradable. The experimental results show that the tensile strength in the transverse direction is 20.3-23.7MPa, and the tensile strength in the longitudinal direction is 27.4-33.6MPa; the elongation at break in the transverse direction is 310.9-560.7%, and the elongation at break in the longitudinal direction is 169.8-284.1%; The transverse Young's modulus is 393.7-782.4MPa, the longitudinal Young's modulus is 541.8-1182.3MPa; the transverse right-angle tear strength is 65.6-113.7KN/m, and the longitudinal right-angle tear strength is 85.9-121.4KN/ m; heat sealing strength is 21.3～26.1N/15mm; pendulum impact strength is 0.82～1.18J.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (6)

1. A completely biodegradable blown film comprises an inner layer, a middle layer and an outer layer which are contacted in sequence;

the inner layer comprises, by weight, 10-25 parts of polylactic acid, 61.8-88.95 parts of polybutylene terephthalate-adipate-butylene glycol ester, 0.1-2 parts of a compatibilizer, 0.1-5 parts of a plasticizer, 0.1-3 parts of a nucleating agent, 0.05-0.2 part of a chain extender, 0.1-1 part of an opening agent, 0.1-2 parts of a lubricant and 0.2-2 parts of carbon black;

the middle layer comprises 10-25 parts of polylactic acid, 52.8-83.25 parts of poly (terephthalic acid) -butanediol adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-2 parts of lubricant, 0.05-0.2 part of chain extender and 6-12 parts of titanium dioxide;

the outer layer comprises 15-30 parts of polylactic acid, 53.8-82.65 parts of polybutylene terephthalate-adipate-butylene glycol ester, 0.1-2 parts of a compatibilizer, 0.1-5 parts of a plasticizer, 0.1-2 parts of a lubricant, 0.05-0.2 part of a chain extender and 2-6 parts of titanium dioxide;

the compatibilizer is glycerol monostearate; the plasticizer is acetyl tributyl citrate; the lubricant is ethylene bis stearamide; the opening agent is erucamide or oleamide; the nucleating agent is talcum powder; the chain extender is a copolymer of styrene-acrylic acid-epoxypropyl methacrylate and/or a copolymer of styrene-maleic anhydride-epoxypropyl methacrylate;

the polylactic acid is polylactic acid with a model REVODE 110;

the polybutylene terephthalate-adipate is polybutylene terephthalate-adipate with the model number TH 801T; the model of the chain extender is ADR4368 and/or ADR 4370.

2. The fully biodegradable blown film according to claim 1, wherein said fully biodegradable blown film has a thickness of 0.05 to 0.06 mm.

3. A method for preparing a fully biodegradable blown film according to any one of claims 1 to 2, comprising the following steps:

mixing 10-25 parts of polylactic acid, 61.8-88.95 parts of polybutylene terephthalate-adipate, 0.1-2 parts of a compatibilizer, 0.1-5 parts of a plasticizer, 0.1-3 parts of a nucleating agent, 0.05-0.2 part of a chain extender, 0.1-1 part of an opening agent and 0.2-2 parts of carbon black, melting, extruding and granulating to obtain inner layer resin;

mixing 10-25 parts of polylactic acid, 52.8-83.25 parts of poly (terephthalic acid) -butanediol adipate, 0.1-2 parts of compatibilizer, 0.1-5 parts of plasticizer, 0.1-2 parts of lubricant, 0.05-0.2 part of chain extender and 6-12 parts of titanium dioxide, melting, extruding and granulating to obtain middle layer resin;

mixing 15-30 parts of polylactic acid, 53.8-82.65 parts of polybutylene terephthalate-adipate, 0.1-2 parts of a compatibilizer, 0.1-5 parts of a plasticizer, 0.1-2 parts of a lubricant, 0.05-0.2 part of a chain extender and 2-6 parts of titanium dioxide, melting, extruding and granulating to obtain outer layer resin;

and co-extruding the inner layer resin, the middle layer resin and the outer layer resin, and performing blow molding to form a film, thereby obtaining the completely biodegradable blown film.

4. The method according to claim 3, wherein the temperature of the extrusion granulation is: a first area: 120-140 ℃, and a second zone: 150-170 ℃, three areas: 160-180 ℃, four zones: 170-190 ℃, and five zones: 170-190 ℃, and six zones: 170-190 ℃, seven areas: 170-190 ℃, eight zones: 170-190 ℃, nine areas: 170-190 ℃, ten areas: 170-190 ℃, head: 170-190 ℃.

5. The production method according to claim 3, wherein the temperature of the inner layer when the film is blown into the film is: a first area: 155-160 ℃, and in the second zone: 165-170 ℃, three areas: 165-180 ℃, four zones: 165-180 ℃, five zones: 160-175 ℃;

the set temperature of the middle layer is as follows: a first area: 155-160 ℃, and in the second zone: 165-170 ℃, three areas: 165-180 ℃, four zones: 165-180 ℃, five zones: 160-175 ℃;

the set temperature of the outer layer is: a first area: 155 ℃ and 160 ℃, and the second zone: 165-170 ℃, three areas: 165-180 ℃, four zones: 165-180 ℃, five zones: 160-175 ℃.

6. A completely biodegradable bag, which is produced from the completely biodegradable film according to any one of claims 1 to 2 or the completely biodegradable film produced by the production method according to any one of claims 3 to 5.