A fully biodegradable composite film with high mechanical strength, its processing technology and its application

Abstract

The present invention relates to a fully biodegradable composite film with high mechanical strength, its processing technology, and its application. This fully biodegradable composite film with high mechanical strength is structured in three layers: an inner film, a bonding film, and an outer film. The outer film is composed of modified polylactic acid; the bonding film consists of an aqueous dispersion of polyester-polyurethane elastomer; the inner film is composed of the following components by mass percentage: polyterephthalic acid-adipic acid-butylene glycol ester at 75-85%, and polylactic acid at 15-25%; the modified polylactic acid comprises the following components by mass percentage: polylactic acid at 92.7-96.7%, polybutylene succinate at 1-2%, a biocompatible agent at 2-5%, an antioxidant at 0.1%, and a sliding agent at 0%.2%; the processing technology is as follows: S1, manufacturing of modified polylactic acid; S2, manufacturing of the outer film; S3, manufacturing of the inner film; S4, application of aqueous dispersion of polyester-polyurethane elastomer; S5, curing. The fully biodegradable composite film with high mechanical strength of the present invention can be used to form the packaging bag, and has the advantages of high mechanical strength and 100% complete degradation.

Description

Title of the invention: A fully biodegradable composite film with high mechanical strength, its processing technology and its application Technical field

[0001] The present invention relates to the technical field of polymer materials, and specifically, it relates to a fully biodegradable composite film with high mechanical strength, its processing technology and its application. State of the art

[0002] Currently, as the national economy continues to develop, the consumption of plastic products increases, synthetic plastic plays an increasingly important role in production and life. However, most of the plastic products cannot be degraded after being discarded and they have accumulated for a long time, causing serious white pollution. With the increasing pollution and the growing awareness of environmental protection, degradable resin has become a hot spot of research, due to its degradable and economical characteristics.

[0003] Polylactic acid (PLA) is one of the fully biodegradable and environmentally friendly materials coated with good mechanical performance and biodegradability, it is easily replaced by the enzymatic decomposition of various microorganisms or animals and plants in nature, finally forming water and carbon dioxide, and does not pollute the environment. It is considered as the bio-environmental material with both ecological and economic effects, it is the most active and fastest developing biodegradable material in recent years, and it is considered as the most promising biodegradable polymer material.

[0004] However, polylactic acid is a hard and brittle material at room temperature, with extremely low elongation rate at break and impact strength, which greatly limits its application, especially in the field of packaging, so unmodified PLA products are difficult to meet the needs of real life.

[0005] Among the current technologies, the Chinese invention patent document with application number CN201610962651.8 relates to a biodegradable black mulch film, and its manufacturing method, comprising the components by weight: 15-20 pcs of PBAT, 60-70 pcs of PLA, 2-8 pcs of microcrystalline cellulose, 1-5 pcs of starch, 2-10 pcs of chitosan, 0.5-2 pcs of chain extender, 8-12 pcs of black PLA masterbatch.

[0006] The present biodegradable mulch film, polylactic acid and starch are mixed to modify the polylactic acid. Although the product has achieved complete biodegradation, the mechanical properties of the starch / polylactic acid mixture are low due to the poor adhesion of starch, which results in the mechanical strength of the composite film not high, when the article to be packaged is harder, the composite film will be torn and damaged easily, therefore, the realization of the invention of a coated composite film with high mechanical strength and 100% complete degradation is a problem to be solved. Statement of the invention

[0007] Aiming at the insufficiency of existing technologies, the first object of the present invention is to provide a fully biodegradable composite film with high mechanical strength which has the advantages of high tensile strength and elongation rate at break and complete degradation.

[0008] The second object of the present invention is to provide the processing technology of a fully biodegradable composite film with high mechanical strength which has the advantages of a simple manufacturing process and easy operation.

[0009] The third object of the present invention is to provide the application of a fully biodegradable composite film with high mechanical strength which has the advantages of high mechanical properties and complete degradation.

[0010] For these purposes, the invention relates to a kind of fully biodegradable composite film with high mechanical strength which comprises the inner film, the bonding film and the outer film, of which the outer film is composed of modified polylactic acid; the bonding film consists of the aqueous dispersion of the polyester-polyurethane elastomer; the inner film is composed of the following mass percentage components: polyterephthalic acid-adipic acid-butylene glycol ester 75-85%, polylactic acid 15-25%; Modified polylactic acid includes the following mass percentage components: 92.7-96.7% polylactic acid, 1-2% polybutylene succinate, 2-5% biocompatible agent, 0.1% antioxidant, 0.2% slip agent.

[0011] The fully biodegradable composite film with high mechanical strength according to the invention may further have the following characteristics:

[0012] - the mentioned external film can have a thickness of 0.02-0.06mm, the internal film which can have a thickness of 0.025-0.1mm.

[0013] - the molecular weight of polylactic acid may be from 100,000 to 180,000, and the molecular weight of polyterephthalic acid-adipic acid-butylene glycol ester can be 60,000-100,000, the melt index can be 3.2-3.5g / 10min; and

[0014] - the antioxidant may be one of the antioxidants of 2112, 1010 and 1076; the agent of slip can be EVA3 wax;

[0015] The invention extends to a method for manufacturing the fully biodegradable composite film with high mechanical strength, comprising the following steps: SI) manufacturing modified polylactic acid:(l) drying polylactic acid and polybutylene succinate;(2) mixing dried polylactic acid and polybutylene succinate with biocompatible agent, antioxidant and slip agent uniformly at 200-210°C to produce modified polylactic acid with extrusion granulation; S2) outer film manufacturing: adding modified polylactic acid into the extrusion machine, to form into outer film after melting, extruding, cooling, pulling and rolling; S3) manufacturing inner film: drying and mixing polylactic acid and polyterephthalic acid-adipic acid-butylene glycol ester homogeneously, to form into inner film after extrusion, cooling, pulling and rolling; S4) applying the aqueous dispersion of the polyester-polyurethane elastomer; heating the outer film to 40-50°C, and then applying a layer of the aqueous dispersion of the polyester-polyurethane elastomer with the brush roller at a temperature of 35-50°C on the side of the outer film, and then pressing the inner film with the brush roller at a temperature of 35-50°C on the layer of the aqueous dispersion of the polyester-polyurethane elastomer, finally performing cooling, pulling and rolling on the formed composite film to form a semi-finished composite film; S5) Maturation: Place the semi-finished composite film into the maturation chamber, control the maturation temperature from 35 to 45°C, the maturation time is 12 to 48 h, and the finished composite film will be formed after maturation.

[0016] The method for manufacturing the fully biodegradable and high mechanical strength composite film according to the invention may further have the following characteristics:

[0017] - the coating quantity of the aqueous dispersion of the polyester elastomer- polyurethane can be 3-5g / m2, brush roller pressure can be 0.1-0.8MPa, and pressure time can be 0.5-1min / mm;

[0018] - the design can be printed on the side of the outer film formed in step S2, and then it can be dried at a temperature of 60 to 80°C; and

[0019] - the drying temperature of polylactic acid and polybutylene succinate can be 60 to 80°C, and the drying time can be 6 to 10 minutes.

[0020] The invention extends to an application of the fully high-strength biodegradable composite film to the field of packaging bags.

[0021] The application of the fully high-strength biodegradable composite film according to the invention may have the following characteristic:

[0022] - the fully biodegradable high strength composite film can be used for forming the three-side sealed flattened bag, three-side sealed holding bag, four-side sealed bag, back sealed bag and holding bag into opening and closing strip and to pack the product close to the inner film.

[0023] In order to achieve said first aim, the present invention provides the following technical program: a fully biodegradable composite film with high mechanical strength is structured into three layers, namely the inner film, the bonding film and the outer film, of which the outer film is composed of modified polylactic acid;

[0024] The bonding film consists of the aqueous dispersion of the polyester-polyurethane elastomer;

[0025] The inner film is composed of the following mass percentage components: polyterephthalic acid-adipic acid-butylene glycol ester 75-85%, polylactic acid 15-25%;

[0026] The modified polylactic acid comprises the following mass percentage components: 92.7-96.7% polylactic acid, 1-2% polybutylene succinate, 2-5% biocompatible agent, 0.1% antioxidant, 0.2% slip agent;

[0027] (1) By adopting said technical program, polylactic acid has the characteristics Excellent optical and mechanical properties, strong mechanical strength, good processing performance and biocompatibility, but its toughness is poor, brittleness is large, and polyterephthalic acid-adipic acid-butylene glycol ester also has good toughness as the fully biodegradable material.Polyterephthalic acid-adipic acid-butylene glycol ester and polylactic acid are combined as the inner film, the proper control of the content of polyterephthalic acid-adipic acid-butylene glycol ester and polylactic acid can accelerate the hydrolysis rate of ester bonds of PBAT and PLA, thus increasing the degradation rate of the composite film, using the aqueous dispersion of polyester-polyurethane elastomer as the intermediate film, bonding and compounding the outer film and the inner film, the aqueous dispersion of polyester-polyurethane elastomer has excellent shear strength and impact resistance, has excellent flexibility characteristics, can improve the mechanical properties of the composite film, and the aqueous dispersion of polyester-polyurethane elastomer has good degradation property, . to make the compound film degrade completely with high mechanical strength; modify polylactic acid by using polybutylene succinate, biocompatible agent, antioxidant and slip agent into modified polylactic acid, to form the outer film due to the excellent mechanical properties of polybutylene succinate which is recognized worldwide as the biodegradable material with the best synthetic performance, modify polylactic acid by blending polybutylene succinate and polylactic acid, and it can increase the degradation rate and degree of polylactic acid, and increase the mechanical strength of modified polylactic acid, the biocompatible agent can promote the bonding of polybutylene succinate and polylactic acid to obtain the stable modified polylactic acid, at the same time, the biocompatible agent can increase the toughness of polylactic acid, adhesion,the printability, anti-static and luster of modified polylactic acid, and the slip agent can make the composite film more complete, smooth and delicate.

[0028] The biocompatible agent can promote the bonding of polybutylene succinate and polylactic acid, both improve the light transmittance, and reduce the haze of the modified polylactic acid, improve the transparency of the outer film, the slip agent is the biodegradable polymer material, the antioxidant and the slip agent can modify the polylactic acid but do not affect the degradation rate of the polylactic acid.

[0029] Furthermore, the thickness of the mentioned outer film is 0.02-0.06mm, and that of the inner film is 0.025-0.1mm.

[0030] By adopting said technical program, the thickness of the outer film and the inner film is appropriate, so that the strength, toughness, tear resistance and barrier property of the composite film are better.

[0031] Furthermore, the molecular weight of polylactic acid is 100,000-180,000, and the molecular weight of polyterephthalic acid-adipic acid-butylene glycol ester is 60,000-100,000, and the melt index is (3.2-3.5) g / 10 min.

[0032] Furthermore, the antioxidant mentioned is one of the antioxidants of 2112, 1010 and 1076; the slip agent mentioned is EVA3 wax.

[0033] In order to achieve said second aim, the present invention provides the following technical program: a processing technology of the fully biodegradable composite film with high mechanical strength comprises the following steps:

[0034] SI. The manufacture of modified polylactic acid: (1) drying polylactic acid and polybutylene succinate; (2) mixing dried polylactic acid and polybutylene succinate with biocompatible agent, antioxidant and slip agent uniformly at 200-210°C, to produce modified polylactic acid with extrusion granulation;

[0035] S2. The manufacture of the outer film: adding modified polylactic acid into the extrusion machine, to form into outer film after melting, extruding, cooling, pulling and rolling;

[0036] S3. The manufacture of the inner film: drying and mixing polylactic acid and polyterephthalic acid-adipic acid-butylene glycol ester homogeneously, to form into an internal film after extrusion, cooling, pulling and rolling;

[0037] S4. Application of the aqueous dispersion of the polyester-polyurethane elastomer; heating the outer film to 40-50°C, and then applying a layer of the aqueous dispersion of the polyester-polyurethane elastomer with the brush roller at a temperature of 35-50°C on the side of the outer film, and then pressing the inner film with the brush roller at a temperature of 35-50°C on the layer of the aqueous dispersion of the polyester-polyurethane elastomer, finally performing cooling, pulling and rolling on the formed composite film to form a semi-finished composite film;

[0038] S5. Maturation: placing the semi-finished composite film in the maturation chamber, control the curing temperature from 35 to 45°C, the curing time is 12 to 48 h, and the finished composite film will be formed after curing.

[0039] Furthermore, the coating amount of the aqueous dispersion of the polyester-polyurethane elastomer in the mentioned step S4 is (3-5) g / m2, the brush roller pressure is 0.1-0.8 MPa, and the pressing time is (0.5-1) min / mm.

[0040] Further, drawing the design on the side of the outer film formed in step S2 mentioned, and then drying it at the temperature of 60-80°C.

[0041] Furthermore, the drying temperature of polylactic acid and polybutylene succinate is 60-80°C, and the drying time is 6-10h.

[0042] To achieve said third aim, the present invention provides the following technical program: the application of a fully biodegradable composite film with high mechanical resistance, in the field of packaging bags.

[0043] In addition, this fully biodegradable composite film with high mechanical strength can be used to form the three-side sealed flattened bag, the three-side sealed holding bag, the four-side sealed bag, the back sealed bag and the opening and closing strip holding bag and to package the product close to the inner film.

[0044] In summary, the present invention has the following beneficial effects:

[0045] Firstly, since the present invention uses modified polylactic acid to form the outer film of the composite film, and polylactic acid and polyterephthalic acid-adipic acid-butylene glycol ester to form the inner film of the composite film, and polyurethane as the bonding film, since polylactic acid has good film-forming property, adding the polyte- Biodegradable poly(lactic acid)-butylene glycol ester can improve the properties of tensile strength, impact resistance, toughness, tear resistance; using modified poly(lactic acid) to form the outer film can improve the mechanical properties, heat resistance and flexibility to obtain the composite film with high mechanical strength and 100% completely degraded.

[0046] Secondly, the present invention is preferably used polybutylene succinate, biocompatible agent, slip agent, and antioxidant to modify polylactic acid, polybutylene succinate has good mechanical properties and heat resistance, as the biodegradable material, and the biocompatible agent can improve the compatibility of polylactic acid and polybutylene succinate, improve the transparency and mechanical strength of the film formed by modified polylactic acid. Detailed description

[0047] The present invention will be described in more detail below with reference to the modes of application.

[0048] Example of application

[0049] The polylactic acid selected from Example 1-6 is the one sold by Chengda Plastic Chemical Co., Ltd in Zibo in model 4032D under the brand of NatureWorks of the United States, the polyterephthalic acid-adipic acid-butylene glycol ester selected is the one sold by Jinfa Technology Co., Ltd in model Flex-64D, the aqueous dispersion of the polyester-polyurethane elastomer selected is the one sold by BASF in Germany in model Epotal®ECO3702, the antioxidants 2112, 1011 and 1076 selected are all those sold by BASF in Germany, the EVA3 wax selected is the one sold by Kaiyin Chemical Industry Co., Ltd in model LUWAX EVA3 under the brand of BASF, the polybutylene succinate selected is the one sold by Jiabairui Material Technology Co., Ltd in Dongguan in model TH803S 1 of Lanshan Tunhe of Xinjiang, and the biocompatible agent chosen is the one sold by Jiayirong Compatible Agent Co., Ltd in Jiangsu as SOG-008.

[0050] Application example 1: A fully biodegradable composite film with high mechanical strength, comprising an outer film, a bonding film and an inner film, of which the outer film is composed of modified polylactic acid, the proportion of the raw material of the inner film is shown in Table 1, the thickness of the outer film is 0.02mm, the thickness of the inner film is 0.025mm, the molecular weight of polyterephthalic acid-adipic acid-butylene glycol ester is 60,000 and the molecular weight of polylactic acid is 100,000, the melt index is 3.2g / 10min.

[0051] The manufacturing process of the fully biodegradable composite film with high mechanical strength includes the following steps:

[0052] SI. The manufacture of modified polylactic acid:

[0053] (1) according to the weight percentage in Table 2, dry the poly(acid) 92.7% lactic acid and 2% polybutylene succinate, the drying temperature is 60°C, and the drying time is 10 h;

[0054] (2) mixing dried polylactic acid and polybutylene succinate with 5% biocompatible agent, 0.1% antioxidant and 0.2% slip agent uniformly at 200°C, to produce modified polylactic acid with extrusion granulation, the antioxidant is that of 2112, the slip agent is EVA3 wax;

[0055] S2. The manufacture of the outer film: adding modified polylactic acid into the extrusion machine, and then form the outer film after melting, extruding, cooling, pulling and rolling, the temperatures of each zone of the extrusion machine are as follows: zone 1: 150°C, zone 2: 160°C, zone 3: 165°C, zone 4: 170°C, zone 5: 175°C, zone 6: 185°C, and the pulling speed of the outer film is 100m / min.

[0056] S3. The manufacture of the internal film: drying and mixing 15% polylactic acid and polyterephthalic acid-adipic acid-butylene glycol ester 85% homogeneously, and then form the inner film after extrusion, cooling, pulling and rolling, the temperatures of each zone of the extrusion machine are as follows: zone 1: 115°C, zone 2: 125°C, zone 3: 125°C, zone 4: 130°C, zone 5: 140°C, zone 6: 150°C, and the pulling speed of the inner film is 100m / min.

[0057] S4. Application of the aqueous dispersion of the polyester-polyurethane elastomer; heating the outer film to 40°C, and then applying a layer of the aqueous dispersion of the polyester-polyurethane elastomer with the brush roller at a temperature of 35°C on the side of the outer film, and then pressing the inner film with the brush roller at a temperature of 35°C on the layer of the aqueous dispersion of the polyester-polyurethane elastomer, finally performing cooling, pulling and rolling on the formed composite film to form a semi-finished composite film, of which the coating amount of the aqueous dispersion of the polyester-polyurethane elastomer is 3g / m2, the pressure of the brush roller is 0. IMPa, and the pressing time is (0.5-l)min / mm, the unwinding tension of the outer film and the inner film is 6kg / m, the winding tension of the semi-finished composite film is 7kg / m.

[0058] S5. Maturation: placing the semi-finished composite film in the maturation chamber, control the maturation temperature at 35°C, the maturation time is 48 hours and the finished composite film will be formed after curing.

[0059] The fully biodegradable composite film with high mechanical strength is applied in the field of packaging bag, can be used to form the three-side sealed flattened bag, three-side sealed holding bag, four-side sealed bag, back sealed bag and opening and closing strip holding bag and to pack the product close to the inner film.

[0060] Table 1, the composition of the inner and outer film materials of Example 1-6

[0061] [Tables 1] Item Outer film material composition Inner film material composition Thickness / mm / internal / external Application example 1 100% modified polylactic acid 15% modified polylactic acid Polyterephthalic acid-adipic acid-butylene glycol ester 85% 0.02 / 0.025 Application example 2 100% modified polylactic acid 18% modified polylactic acid Polyterephthalic acid-adipic acid-butylene glycol ester 82% 0.04 / 0.0625 Application example 3 100% modified polylactic acid 20% modified polylactic acid Polyterephthalic acid-adipic acid-butylene glycol ester 80% 0.06 / 0.1 Example d'applicati on 4 100% modified polylactic acid 23% modified polylactic acid 77% polyterephthalic acid-adipic acid-butylene glycol ester 0.03 / 0.0425 Application example 5 100% modified polylactic acid 25% modified polylactic acid 75% polyterephthalic acid-adipic acid-butylene glycol ester 0.05 / 0.0825 Application example 6 100% modified polylactic acid 15% modified polylactic acid 85% polyterephthalic acid-adipic acid-butylene glycol ester 0.02 / 0.025 .

[0062] Table 2, the proportion of the raw material of the modified polylactic acid of Example 1-5

[0063] [Tables2] % Component Application example 1 Application example 2 Application example 3 Application example 4 Application example 5 Application example 6 Polylactic acid 92.7 93.7 94.7 95.7 96.7 96.7 Polyterephthalic acid-adipic acid-butylene glycol ester 2 1.8 1.5 1.2 1 1 Biocompatible agent 5 4.2 3.5 2.8 2 2 Antioxidant 0.1 0.1 0.1 0.1 0.1 0.1 Glide agent 0.2 0.2 0.2 0.2 0.2 0.2

[0064] Application example 2: A fully biodegradable composite film with high mechanical strength, comprising an outer film, a bonding film and an inner film, of which the outer film is composed of modified polylactic acid, the proportion of the raw material of the inner film is shown in Table 1, the thickness of the outer film is 0.04mm, the thickness of the inner film is 0.0625mm, the molecular weight of polylactic acid is 140,000 and the molecular weight of polyterephthalic acid-adipic acid-butylene glycol ester is 80,000, the melt index is 3.3g / 10min.

[0065] The manufacturing process of the fully biodegradable composite film with high mechanical strength includes the following steps:

[0066] SI. The manufacture of modified polylactic acid:

[0067] (1) according to the weight percentage in Table 2, dry the poly(acid) lactic acid at 93.7% and polybutylene succinate at 1.8%, the drying temperature is 70°C, and the drying time is 8 hours;

[0068] (2) mixing dried polylactic acid and polybutylene succinate with 4.2% biocompatible agent, 0.1% antioxidant and 0.2% slip agent uniformly at 205°C, to produce modified polylactic acid with extrusion granulation, the antioxidant is that of 1010, the slip agent is EVA3 wax;

[0069] S2. The manufacture of the outer film: adding modified polylactic acid into the extrusion machine, and then form the outer film after melting, extruding, cooling, pulling and rolling, the temperatures of each zone of the extrusion machine are as follows: zone 1: 155°C, zone 2: 165°C, zone 3: 170°C, zone 4: 175°C, zone 5: 180°C, zone 6: 190°C, and the outer film pulling speed is 150m / min.

[0070] S3. The manufacture of the internal film: drying and mixing 18% polylactic acid and polyterephthalic acid-adipic acid-butylene glycol ester 82% homogeneously, and then form the inner film after extrusion, cooling, pulling and rolling, the temperatures of each zone of the extrusion machine are as follows: zone 1: 120°C, zone 2: 130°C, zone 3: 130°C, zone 4: 135°C, zone 5: 145°C, zone 6: 155°C, and the pulling speed of the inner film is 150m / min.

[0071] S4. Application of the aqueous dispersion of the polyester-polyurethane elastomer; heating the outer film to 45°C, and then applying a layer of the aqueous dispersion of the polyester-polyurethane elastomer with the brush roller at a temperature of 40°C on the side of the outer film, and then pressing the inner film with the brush roller at a temperature of 40°C on the layer of the aqueous dispersion of the polyester-polyurethane elastomer, finally performing cooling, pulling and rolling on the formed composite film to form a semi-finished composite film, of which the coating amount of the aqueous dispersion of the polyester-polyurethane elastomer is 4g / m2, the pressure of the brush roller is 0.4MPa, and the pressing time is 0.8min / mm, the unwinding tension of the outer film and the inner film is 7kg / m, the winding tension of the semi-finished composite film is 10kg / m.

[0072] S5. Maturation: placing the semi-finished composite film in the maturation chamber, control the maturation temperature at 40°C, the maturation time is 30h and the finished composite film will be formed after maturation.

[0073] The fully biodegradable composite film with high mechanical strength is applied in the field of packaging bag, can be used to form the three-side sealed flattened bag, three-side sealed holding bag, four-side sealed bag, back sealed bag and opening and closing strip holding bag and to pack the product close to the inner film.

[0074] Application example 3: A fully biodegradable composite film with high mechanical strength, comprising an outer film, a bonding film and an inner film, of which the outer film is composed of modified polylactic acid, the proportion of the raw material of the inner film is shown in Table 1, the thickness of the outer film is 0.06mm, the thickness of the inner film is 0.1mm, the molecular weight of polylactic acid is 180,000 and the molecular weight of polyterephthalic acid-adipic acid-butylene glycol ester is 100,000, the melt index is 3.5g / 10min.

[0075] The manufacturing process of the fully biodegradable composite film with high mechanical strength includes the following steps:

[0076] SI. The manufacture of modified polylactic acid:

[0077] (1) according to the weight percentage in Table 2, dry the poly(acid) 94.7% lactic acid and 1.5% polybutylene succinate, the drying temperature is 80°C, and the drying time is 6 hours;

[0078] (2) mixing dried polylactic acid and polybutylene succinate with 3.5% biocompatible agent, 0.1% antioxidant and 0.2% slip agent uniformly at 210°C, to produce modified polylactic acid with extrusion granulation, the antioxidant is that of 1076, the slip agent is EVA3 wax;

[0079] S2. The manufacture of the outer film: adding modified polylactic acid into the extrusion machine, and then form the outer film after melting, extruding, cooling, pulling and rolling, the temperatures of each zone of the extrusion machine are as follows: zone 1: 160°C, zone 2: 170°C, zone 3: 180°C, zone 4: 185°C, zone 5: 190°C, zone 6: 195°C, and the pulling speed of the outer film is 200m / min.

[0080] S3. The manufacture of the internal film: drying and mixing 20% ​​polylactic acid and polyterephthalic acid-adipic acid-butylene glycol ester 80% homogeneously, and then form the inner film after extrusion, cooling, pulling and rolling, the temperatures of each zone of the extrusion machine are as follows: zone 1: 125°C, zone 2: 135°C, zone 3: 135°C, zone 4: 140°C, zone 5: 150°C, zone 6: 160°C, and the pulling speed of the inner film is 200m / min.

[0081] S4. Application of the aqueous dispersion of the polyester-polyurethane elastomer; heating the outer film to 50°C, and then applying a layer of the aqueous dispersion of the polyester-polyurethane elastomer with the brush roller at a temperature of 50°C on the side of the outer film, and then pressing the inner film with the brush roller at a temperature of 50°C on the layer of the aqueous dispersion of the polyester-polyurethane elastomer, finally performing cooling, pulling and rolling on the formed composite film to form a semi-finished composite film, of which the coating amount of the aqueous dispersion of the polyester-polyurethane elastomer is 5g / m2, the pressure of the brush roller is 0.8MPa, and the pressing time is 0.5min / mm, the unwinding tension of the outer film and the inner film is 8kg / m, the winding tension of the semi-finished composite film is 12kg / m.

[0082] S5. Maturation: placing the semi-finished composite film in the maturation chamber, control the maturation temperature at 45°C, the maturation time is 12 hours and the finished composite film will be formed after curing.

[0083] The fully biodegradable composite film with high mechanical strength is applied in the field of packaging bag, can be used to form the three-side sealed flattened bag, three-side sealed holding bag, four-side sealed bag, back sealed bag and opening and closing strip holding bag and to pack the product close to the inner film.

[0084] Application Example 4: A fully biodegradable composite film with high mechanical strength, which differs from Application Example 1 is that the raw material composition of the inner and outer film is shown in Table 1, the thickness of the inner film is 0.0425mm, and that of the outer film is 0.03mm, and the raw material composition of polylactic acid is shown in Table 2, drawing the design on the side of the outer film, and then drying at the temperature of 60°C.

[0085] Application Example 5: A fully biodegradable composite film with high mechanical strength, which differs from Application Example 1 is that the raw material composition of the inner and outer film is shown in Table 1, the thickness of the inner film is 0.0825mm, and that of the outer film is 0.05mm, and the raw material composition of polylactic acid is shown in Table 2, drawing the design on the side of the outer film, and then drying at the temperature of 70°C.

[0086] Application Example 6: A fully biodegradable composite film with high mechanical strength, which differs from Application Example 1 is that the raw material composition of the inner and outer film is shown in Table 1, the thickness of the inner film is 0.025mm, and that of the outer film is 0.02mm, and the raw material composition of polylactic acid is shown in Table 2, drawing the design on the side of the outer film, and then drying at the temperature of 80°C.

[0087] Example of comparison

[0088] Comparison Example 1: A fully biodegradable composite film with high mechanical strength, which differs from Application Example 1 is that the amount of raw material of the inner film is shown in Table 3.

[0089] Table 3, the amount of raw material of the inner film of Comparison Example 1-4. [Tables 3] Comparison example The amount of raw material of the inner film Comparison example 1 5% polylactic acid, 95% polyterephthalic acid-adipic acid-butylene glycol ester Comparison example 2 10% polylactic acid, 90% polyterephthalic acid-adipic acid-butylene glycol ester Comparison example 3 30% polylactic acid, 70% polyterephthalic acid-adipic acid-butylene glycol ester Comparison example 4 35% polylactic acid, 65% polyterephthalic acid-adipic acid-butylene glycol ester

[0091] Comparison Example 5: A fully biodegradable composite film with high mechanical strength, which differs from Application Example 1 in that the poly-lactic acid of the outer film has not been modified.

[0092] Comparison Example 6: A fully biodegradable composite film with high mechanical strength, which differs from Application Example 1 is that the modified poly-lactic acid of the outer film is replaced by the modified PLA material produced in Application Example 1 of Chinese patent document under application number CN104086777A, the prescription of the modified PLA material is as follows: 100 pcs of PLA, 30 pcs of PETG, 0.1 pc of polyether, 0.05 pc of N,N-2,6-diisopropylphenylcarbodiimide, 0.5 pc of paraffin, 0.1 pc of oleic acid amide, 0.1 pc of Joncryl ADR-4368, 1 pc of RX-80, 0.1 pc of Ca / Zn composite stabilizer.

[0093] Comparison Example 7: A fully biodegradable composite film with high mechanical strength, which differs from Application Example 1 is that the PLA / PBAT biodegradable composite film produced in Application Example 1 of Chinese patent document in application number CN201210289135.5 was treated as the inner film, (1) drying PLA (4032D) and PB AT for 12 h in the blow dryer at 80°C, and calcium carbonate for 6 hours, (2) then mix 90 parts of PLA, 10 parts PB AT, 0.04 part of 2.2'-bis(2-oxazoline), 2.4 parts of hexamethylene diisocyanate, 0.6 part of calcium stearate, 0.1 part of antioxidant 1010, 10 parts of calcium carbonate in a high-frequency mixer at room temperature for 5 minutes; (3) add the obtained mixture into a twin-screw machine to obtain extrusion granulation, the temperature of each zone of the twin-screw machine is: zone 1: 150°C, zone 2: 160°C, zone 3: 160°C, zone 4: 170°C, zone 5: 170°C, zone 6: 175°C, machine head: 180°C; the screw rotation speed is 200 rpm / min and the height / width ratio L / D is 40 / 1; (4) drying the granulation obtained in step (3) in the blowing dryer at 80°C for 12 hours; (5) adding dried granulation in step (4) into the single screw machine to make blow molding.The temperature of each zone of the single screw machine is: zone 1: 120°C, zone 2: 140°C, zone 3: 160°C, zone 4: 170°C, zone 5: 170°C, zone 6: 170°C, machine head: 165°C; the screw rotation speed is 150 rpm / min and the aspect ratio L / D is 25:1; the ratio of the die diameter of the single screw extruder and that of the bubble tube is 3:1.

[0094] Comparison Example 8: A fully biodegradable composite film with high mechanical strength, which differs from Application Example 1 is that the outer film is formed by the modified PLA material of Comparison Example 6, the inner film is formed by the PLA / PBAT composite film of Comparison Example 7, and then forming the composite film in the same manner as in Application Example 1.

[0095] Property detection test

[0096] 1. Transparency detection of outer film and composite film: forming the composite film according to the method of Application Example 1-6 and Comparison Example 5-6, and detecting the light transmission rate and haze degree of the outer film and the composite film according to the method of GB / T2410-1980 “Test Method of Light Transmission Rate and Haze Degree of Transparent Plastic”, and the test results are shown in Table 4.

[0097] Table 4, Test results of light transmission rate and haze degree of composite film of Application Example 1-6 and Comparison Example 5-6

[0098] [Tables 4] Test Items Light Transmission Rate / % Haze Degree / % Outer Film Composite Film Outer Film Composite Film Application Example 1 98.1 70.4 3.5 6.3 Application Example 2 98.2 70.8 3.4 6.2 Application Example 3 98.5 71.1 3.2 6.1 Application Example 4 98.3 70.6 3.3 6.3 Application Example 5 98.6 70.9 3.2 6.2 Application Example 6 98.2 70.5 3.5 6.4 Comparison Example 5 87.3 63.2 5.8 8.5 Comparison Example 6 90.2 65.3 5.7 8.4

[0099] According to the data in Table 4, the outer film which forms modified polylactic acid, the light transmission rate of which is 98% or more, the degree of haze is 3.2-3.5%, the transparency is high, even after combining with the inner film, the transparency of the composite film has reached 70.4-71.1%, the degree of haze is 6.1-6.4%, the transparency is still good.

[0100] In Comparison Example 5, whose outer film was not formed from the acid Modified polylactic acid, the light transmittance is not high, just reached 87.3%, the degree of haze increases, the transparency has been weakened, after combining with the inner film, the transparency has reduced obviously compared to that of application example 1-6, it means that using modified polylactic acid to prepare the outer film can improve the transparency of the outer film and the composite film.

[0101] In Comparison Example 6, polylactic acid is modified with the current technology, and then formed into an outer film, the light transmission rate of which is 90.25%, and the degree of haze is 5.7%, for the outer film formed in Comparison Example 6, the light transmission rate of which is lower and the degree of haze is higher compared to that of Application Example 1-6, it means that the transparency of the outer film formed by the polylactic acid modified by the current technology is not good as that of the outer film formed by the modified polylactic acid of the present invention.

[0102] 2. Detection of mechanical strength of the composite film: forming the composite film in according to the method of Application Example 1-6 and Comparison Example 1-8, and detect all mechanical properties via the following methods, and record the detection results in Table 5.

[0103] 1. Tensile strength and tensile modulus: tested in accordance with GB13022-1991 “Test Method for Tensile Properties of Plastic Film”;

[0104] 2. Elongation rate at break: controlled according to GBB / T 1040.3-2006 “Determination of tensile properties - Part 3: Film and sheet test conditions”;

[0105] 3. Dart impact quality: tested according to GB / T9639-1988 “Test method impact resistance of plastic film and sheet-free fall dart»;

[0106] 4. Puncture resistance: according to GB / T10004 “Test method for puncture resistance to the perforation of the composite film of the plastic packaging bag”.

[0107] Table 5, Mechanical strength detection of the composite film formed in each application and comparison example [Tables 5] Test articles Tensile strength (MPa) Tensile modulus (MPa) Rate of elongation at break (%) Impact quality of darts (G) Punching strength(N / pm) 83.8 3550 3281 50.2 41.3 168 0.78 Example of application 2 85.9 83.9 3559 3284 50.5 41.5 175 0.80 Example of application 50.8 41.8 179 0.83 Example of application 4 86.4 84.4 3567 3293 51.3 42.3 185 0.85 Example of application 5 86.5 84.7 3572 3955 1694. 0.88 Example of application 6 85.6 83.9 3558 3283 50.4 41.4 169 0.79 Example of comparison 1 56.7 52.1 2183 1822 28.6 21.5 1023 Example of comparison. 55.4 2216 1943 29.8 22.8 137 0.26 Exemple 55.3 53.6 2205 1962 30.4 23.5 142 0.24 Comparison Example 3 Comparison Example 4 56.2 52.6 2227 1954 28.9 22.3 146 0.25 Comparison Example 5 50.7 48.5 1875 1572 25.3 16.8 123 0.18 Comparison Example 6 61.9 59.6 2248 1976 31.6 24.7 137 0.20 Comparison Example 7 66.8 54.3 2616 2487 34.3 26.3 145 0.34 Comparison Example 8 68.7 61.8 2742 2576 36.5 25.6 168 0.43

[0109] According to the data in Table 5, the composite film prepared in Examples 1-6, whose horizontal and vertical tensile strength is high, the horizontal and vertical tensile modulus is large, the elongation rate at break is high, and the dart impact quality is large and the puncture resistance is large, indicating that the composite film prepared in Examples 1-6 of the invention has good tensile strength, good tensile modulus, high elongation rate at break, good puncture and impact resistance and good mechanical strength.

[0110] In Comparison Example 1, the content of polylactic acid of the inner film is 5%, and that of polyterephthalic acid-adipic acid-butylene glycol ester is 95%, after combining the formed inner and outer film of Comparison Example 1, the tensile strength and elongation rate at break of the composite film decreased, the puncture resistance and impact resistance were weakened, this means that when the content of polylactic acid is decreased and that of polyterephthalic acid-adipic acid-butylene glycol ester is increased, the mechanical strength of the composite film is reduced.

[0111] In Comparison Example 2, the content of polylactic acid of the outer film is 10%, and that of polyterephthalic acid-adipic acid-butylene glycol ester is 90%, according to the data in Table 5, several mechanical strengths of the composite film of Comparison Example 2 were reduced obviously, it means that when the content of polylactic acid is decreased and that of polyterephthalic acid-adipic acid-butylene glycol ester is increased, the mechanical strength of the composite film is reduced.

[0112] In Comparison Example 3 and 4, the content of polylactic acid is increased and the content of polyterephthalic acid-adipic acid-butylene glycol ester is reduced, the tensile strength and elongation rate at break of the composite film are decreased, the puncture resistance and impact resistance are weakened, it means that when the content of polylactic acid is increased and that of polyterephthalic acid-adipic acid-butylene glycol ester is decreased, the mechanical strength of the composite film is reduced.

[0113] In Comparison Example 5, the outer film of which was not formed from the modified polylactic acid, and the outer film was combined with the inner film, and the mechanical properties of the composite film were poor, it means that using the modified polylactic acid of the present invention to prepare the outer film can improve the mechanical strength of the composite film.

[0114] Comparison Example 6 is to modify polylactic acid using the existing modification method. After forming the outer film, it is combined with the inner film and the mechanical properties of the composite film are better than those of Comparison Example 5, but the mechanical strength is still insufficient compared with the composite film formed in Application Examples 1-6.

[0115] In Comparison Example 7, the inner film is formed from the mixture of the existing polylactic acid and polyterephthalic acid-adipic acid-butylene glycol ester, being combined with the outer film made of the modified polylactic acid, but the mechanical strength is reduced compared to the composite film formed in Application Examples 1-6.

[0116] Comparison Example 8 is to modify polylactic acid using the existing modification method. After forming the outer film, it is combined with the inner film made of the mixture of PLA and PB AT, the mechanical properties of the composite film of which are better than those of Comparison Example 5-7, but the mechanical strength is still insufficient compared with the composite film formed in Application Examples 1-6, indicating that the composite film prepared in Application Examples 1-6 of the invention has good tensile strength, high elongation rate at break, good puncture resistance and impact resistance.

[0117] 3. Detection of biodegradation rate of composite film: forming the composite film According to the method of Application Example 1-6 and Comparison Example 1-8, choose 100 pcs of composite film in each application and comparison example, and detect each composite film according to to HJ / T209-2005 “Technical requirements for environmental labeling products packaging products”, finally, take the average of the detection results of each of the 100 pcs of the application or comparison example, and record the detection results in Table 6.

[0118] Table 6, Detection results of the biodegradation rate of the composite film formed in each of the application and comparison examples

[0119] [Tableauxô] Item Biodegradation Rate / % 80d 90d lOOd HOd 120d Application Example 1 69.8 83.7 94.9 100 100 Application Example 2 71.3 82.4 96.7 100 100 Application Example 3 73.2 85.7 96.2 100 100 Application Example 4 75.8 88.9 98.8 100 100 Application Example 5 72.5 90.2 99.2 100 100 Application Example 6 71.9 88.5 98.4 100 100 Comparison Example 1 52.1 72.3 86.5 98.2 98.2 Comparison Example 2 53.8 73.3 88.4 99.2 99.2 Comparison example 3 52.7 71.6 83.3 98.1 98.1 Comparison example 4 56.0 76.8 88.9 99.3 99.3 Comparison example 5 51.3 70.5 81.5 96.3 96.3 Comparison example 6 64.4 81.8 91.1 98.6 98.6 Comparison example 67.3 82.3 91.4 99.8 99.8 comparison 7 Example of comparison 8 70.2 82.7 92.6 99.9 100

[0120] According to the data in Table 6, the composite film formed via the methods of Application Examples 1-6, the biodegradation rate of which reaches nearly 100% at the 100th day, at the 110th day, all degradation is completed, it is degraded quickly and completely.

[0121] The composite film formed in Comparison Example 1-4, the biodegradation rate of which reaches only 83.3-88.9% at the 100th day, and only 98.1-99.3% at the 110th day, and the biodegradation rate at the 120th day is the same as that at the 110th day, the degradation rate of the composite film in Comparison Examples 1-4 is slower than that of the composite film in Application Examples 1-6, moreover, it cannot achieve 100% complete degradation.

[0122] Comparison Example 5 concerns the outer film made of unmodified polylactic acid. The degradation rate of the composite film is the same at the 110th day and at the 120th day, the degradation rate is slow and the degradation is incomplete.

[0123] In Comparison Example 6, polylactic acid is modified with current technology, and then formed into an outer film, the degradation rate of the composite film of which is faster than that of Comparison Example 5, but compared with Application Examples 1-6, the degradation rate is still low, the rate is slow, and the degradation is incomplete.

[0124] Comparison example 7 concerns the inner film made of PLA and PBAT, the degradation rate of the composite film reaches 99.8% at the 110th day and at the 120th day, the degradation rate is fast, but has not completely degraded.

[0125] Comparison Example 8 is to modify polylactic acid using the existing modification method. After forming the outer film, it is combined with the inner film made of the mixture of PLA and PBAT, the degradation rate of the formed composite film is fast, reaching 99.9% at the 110th day and 100% at the 120th day.

[0126] 4. Detection of the degradation rate of the compost of the composite film according to the manner from application example 1-5: Detect according to EN 13432 “Requirements for testing and final assessment of packaging materials by recycling by compost and biological decomposition”, the virgin group is the degradable film sold to the market, the detection results are shown in Table 4.

[0127] Table 7, Detection results of the degradation rate of the film compost composite of Example 1-5.

[0128] [Paintings?] Sensing Element Chemical Properties Aerobic Degradation Rate / % Compost Disintegration Rate / % Biological Toxicity / 90d 120d 150d 180d 6 Weeks 9 Weeks 12 Weeks Germination Rate / % Average Daily Plant Gain / g Application Example 1 Heavy metal does not exceed the limit 89.6 98.6 99.8 100 89.7 95.4 98.8 98.7 1.8 Application Example 2 Heavy metal does not exceed the limit 90.8 99.5 100 100 90.5 97.4 100 97.5 1.9 Application Example 3 Heavy metal does not exceed the limit 91.3 100 100 100 84.6 92.6 99.7 98.2 2.1 Application example 4 Heavy metal does not exceed the limit 89.4 96.2 98. 6 100 86.1 96.3 100 97.8 2.0 Application example 5 Heavy metal does not exceed the limit 92.1 98.6 100 100 89.5 97.8 100 99.1 1.9 Group The metal 67.8 78.4 84. 96.7 67.1 76.2 84.3 82.1 1.1 heavy virgin does not exceed limit 2

[0129] According to the data shown in Table 4, there is no heavy metal in the fully degradable composite film formed according to Application Example 1-5, and the degradation rate of the compost can reach 100% at the 120-180th day, and 99.3-100% can be decomposed into piece which can pass the screen in diameter of 22mm, no biological toxicity, the germination rate is high after the tree is planted, and the growth speed is fast.

[0130] The present application examples are only the explanation of the present invention, but not the limit, the technician in this field can make the non-creative modification on the application examples as needed after reading this instruction manual, and everything is protected by patent law within the scope of the claim of the present invention.

Claims

Claims

1. A fully biodegradable composite film with high mechanical strength which comprises an inner film, a bonding film and an outer film, wherein the outer film is composed of the modified polylactic acid; the bonding film is composed of the aqueous dispersion of the polyester-polyurethane elastomer; the inner film is composed of the following mass percentage components: 75-85% polyterephthalic acid-adipic acid-butylene glycol ester, 15-25% polylactic acid; the modified polylactic acid comprises the following mass percentage components: 92.7-96.7% polylactic acid, 1-2% polybutylene succinate, 2-5% biocompatible agent, 0.1% antioxidant, 0.2% slip agent.

2. Fully biodegradable composite film with high mechanical strength according to claim 1 characterized in that the outer film has a thickness of 0.02 to 0.06mm, the inner film having a thickness of 0.025 to 0.1mm.

3. A fully biodegradable composite film with high mechanical strength according to claim 1 characterized in that the molecular weight of polylactic acid is 100,000 to 180,000, and the molecular weight of polyterephthalic acid-adipic acid-butylene glycol ester is 60,000 to 100,000, the melt index is 3.2 to 3.5g / 10min.

4. Fully biodegradable composite film with high mechanical strength according to claim 1 characterized in that the antioxidant is one of the antioxidants 2112, 1010 and 1076; the slip agent is EVA3 wax.

5. A method for processing the fully biodegradable composite film with high mechanical strength according to any one of claims 1 to 4 characterized in that the following steps are included: S1) manufacturing the modified polylactic acid: (1) drying the polylactic acid and polybutylene succinate; (2) mixing the dried polylactic acid and polybutylene succinate with biocompatible agent, antioxidant and slip agent uniformly at 200-210°C, to produce modified polylactic acid with extrusion granulation; S2) manufacturing the outer film: adding modified polylactic acid into the extrusion machine, to form into outer film after melting, extrusion, cooling, traction and rolling; S3) manufacturing the inner film: drying and mixing poly-lactic acid and polyterephthalic acid-adipic acid-butylene glycol ester homogeneously, to form into an inner film after extrusion, cooling, traction and rolling; S4) applying the aqueous dispersion of the polyester-polyurethane elastomer; heating the outer film to 40-50°C, and then applying a layer of the aqueous dispersion of the polyester-polyurethane elastomer with the brush roller at a temperature of 35-50°C on the side of the outer film, and then pressing the inner film with the brush roller at a temperature of 35-50°C on the layer of the aqueous dispersion of the polyester-polyurethane elastomer, finally performing cooling, traction and rolling on the formed composite film to form a semi-finished composite film;S5) Maturation: Place the semi-finished composite film into the maturation chamber, control the maturation temperature from 35 to 45°C, the maturation time is 12 to 48h, and the finished composite film will be formed after maturation.;

6. A treatment method according to claim 5 of the fully biodegradable composite film with high mechanical strength characterized in that the coating amount of the aqueous dispersion of the polyester-polyurethane elastomer is 3 to 5 g / m2, the pressure of the brush roller is 0.1 to 0.8 MPa, and the pressing time is 0.5 to 1 min / mm.

7. A treatment method according to claim 5 of the fully biodegradable composite film with high mechanical strength characterized in that the design is printed on the side of the outer film formed in step S2, and then it is dried at a temperature of 60 to 80°C.

8. A treatment method according to claim 5 of the fully biodegradable composite film with high mechanical strength characterized in that the drying temperature of polylactic acid and polybutylene succinate is 60 to 80°C, and the drying time is 6 to 10 minutes.

9. Use of the fully biodegradable composite film with high mechanical strength according to any one of claims 1 to 4 in the field of packaging bags.

10. Use of the fully biodegradable composite film with high mechanical strength according to claim 9 characterized in that this fully biodegradable composite film with high mechanical strength is used to form three-side sealed flattened bag, three-side sealed holding bag, four-side sealed bag, back sealed bag and opening and closing strip holding bag and to pack the product close to the inner film.