CN113881110A

CN113881110A - Full-biodegradable composite film, preparation method and express delivery bag thereof

Info

Publication number: CN113881110A
Application number: CN202110743266.5A
Authority: CN
Inventors: 靳玉娟; 翁云宣; 徐景美; 张波涛; 武睿泽; 汪倩; 沈坤良; 张天宇; 湛卫林
Original assignee: Nantong Huasheng Green Plastic Packaging Products Co ltd; Beijing Technology and Business University; Shunqihe Shenzhen Technology Co Ltd
Current assignee: Nantong Huasheng Green Plastic Packaging Products Co ltd; Beijing Technology and Business University; Shunqihe Shenzhen Technology Co Ltd
Priority date: 2020-07-02
Filing date: 2021-07-01
Publication date: 2022-01-04
Anticipated expiration: 2041-07-01
Also published as: CN113881110B

Abstract

The invention provides a full-biodegradable composite membrane, a preparation method and an express delivery bag thereof. Specifically, the composite film comprises a first layer, a second layer and a third layer which are sequentially stacked; the first layer and the third layer include: 70-90 parts by weight of plasticized starch, 5-15 parts by weight of polylactic acid, 5-15 parts by weight of polycaprolactone and 0.02-0.1 part by weight of chain extender; the second layer includes: 60-80 parts by weight of polypropylene carbonate, 5-15 parts by weight of poly (adipic acid/terephthalic acid) butylene, 5-15 parts by weight of polycaprolactone and 0.02-0.1 part by weight of chain extender. The full-biodegradable composite film and the express bag thereof have excellent barrier property, high strength, high toughness and puncture resistance, meet various requirements in the express transportation process, and have certain degradation capability in soil and seawater.

Description

Full-biodegradable composite film, preparation method and express delivery bag thereof

Technical Field

One or more embodiments of the specification relate to the field of biodegradable materials, in particular to a full-biodegradable composite film, a preparation method and a express delivery bag thereof.

Background

In recent years, rapid development of the internet has led to rapid development of electronic commerce platforms, and aspects of online shopping and life become dense. The online shopping brings convenience to the life of people, a large number of express packages are also promoted, the national express quantity is more than 500 hundred million pieces in 2018 year according to statistics, the number of consumed plastic bags is up to 245 hundred million, the express packaging plastic bags are subjected to multiple transfer in the express transportation process, are polluted by a lot of collision, have no recycling value basically, and the total recovery rate is less than 10 percent at present. The express plastic bags in large quantities can not be reprocessed and degraded, most of the express plastic bags can only be buried and burned, which causes huge pollution to the natural environment and is more difficult to treat than white pollution caused by the traditional shopping bags.

At present, although some research and application are carried out on the full-biodegradable express delivery bag, compared with the traditional plastic bag, the full-biodegradable express delivery bag has the defects of high strength, high toughness, low cost and the like, and is difficult to replace the traditional plastic bag.

Disclosure of Invention

In view of this, an object of one or more embodiments of the present disclosure is to provide a fully biodegradable composite film, a preparation method thereof, and a express delivery bag thereof, so as to solve a problem that the fully biodegradable composite film in the prior art is difficult to meet requirements of the express delivery bag on properties such as strength and toughness.

In view of the above objects, a first aspect of one or more embodiments of the present specification provides a fully biodegradable composite membrane comprising a first layer, a second layer and a third layer sequentially stacked;

the first layer and the third layer include: 70-90 parts by weight of plasticized starch, 5-15 parts by weight of polylactic acid, 5-15 parts by weight of polycaprolactone and 0.02-0.1 part by weight of chain extender;

the second layer includes: 60-80 parts by weight of polypropylene carbonate, 5-15 parts by weight of poly (adipic acid/terephthalic acid) butylene, 5-15 parts by weight of polycaprolactone and 0.02-0.1 part by weight of chain extender.

Further, the first layer further comprises a first colorant, and the third layer further comprises a third colorant, wherein the first colorant and the third colorant are different in color.

Further, the plasticized starch comprises 35-45 parts by weight of starch, 50-60 parts by weight of polybutylene adipate/terephthalate and 8-12 parts by weight of polylactic acid.

Further, the plasticized starch comprises 38-42 parts by weight of starch.

Further, the chain extender includes at least one of an epoxy-terminated hyperbranched polymer or styrene and glycidyl acrylate.

Further, the epoxy-terminated hyperbranched polymer comprises a structure shown as a formula (II);

further, the thickness ratios of the first layer, the second layer and the third layer are: (25-35%), 30-50%, 25-35%).

In a second aspect of one or more embodiments of the present disclosure, there is provided a method for preparing a fully biodegradable composite membrane, including:

uniformly mixing 70-90 parts by weight of plasticized starch, 5-15 parts by weight of polylactic acid, 5-15 parts by weight of polycaprolactone and 0.02-0.1 part by weight of chain extender, and granulating to obtain first master batches;

uniformly mixing 60-80 parts by weight of polypropylene carbonate, 5-15 parts by weight of poly (adipic acid/terephthalic acid) butylene terephthalate, 5-15 parts by weight of polycaprolactone and 0.02-0.1 part by weight of chain extender, and granulating to obtain a second master batch;

carrying out three-layer co-extrusion film blowing by utilizing the first master batch and the second master batch to obtain the fully biodegradable composite film; the first master batch forms a first layer and a third layer of the full-biodegradable composite film, and the second master batch forms a second layer of the full-biodegradable composite film.

Further, before the three-layer co-extrusion film blowing is performed by using the first master batch and the second master batch to obtain the fully biodegradable composite film, the method further comprises the following steps:

mixing the first master batch and a first colorant to obtain a material for forming the first layer; and

mixing the first master batch and a third colorant to obtain a material for forming the third layer; wherein the first colorant and the third colorant are different in color.

Further, the plasticized starch is prepared by the following steps:

dehydrating the raw material starch to obtain starch with the water content of 8-9%;

and uniformly mixing the starch, the polybutylene (adipate/terephthalate) and the polylactic acid, adding a phase solvent, and performing co-extrusion, bracing and granulation to obtain the plasticized starch.

In a third aspect of one or more embodiments of the present disclosure, there is also provided a express delivery bag made of the fully biodegradable composite film according to any one of the above descriptions.

As can be seen from the above, the fully biodegradable composite film, the preparation method and the express delivery bag provided in one or more embodiments of the present disclosure have excellent barrier property, high strength, high toughness and puncture resistance, meet various requirements in the express delivery transportation process, and have a certain degradation capability in soil and seawater.

Drawings

Fig. 1 is a schematic diagram of a synthetic route of a hydroxyl-terminated hyperbranched polyester (HBPE) provided in an embodiment of the present disclosure;

fig. 2 is an infrared spectrum of the epoxy-terminated hyperbranched polymer prepared in the example of the disclosure.

Detailed Description

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.

It is to be noted that unless otherwise defined, technical or scientific terms used in one or more embodiments of the present specification should have the ordinary meaning as understood by those of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," and similar terms in one or more embodiments of the specification is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items.

Based on the fact that the fully biodegradable composite film in the prior art is difficult to meet the requirements of the express bag on the performances such as strength and toughness, the first aspect of the specification provides a fully biodegradable composite film.

The composite film comprises a first layer, a second layer and a third layer which are sequentially stacked; the first layer and the third layer include: 70-90 parts by weight of plasticized starch, 5-15 parts by weight of polylactic acid, 5-15 parts by weight of polycaprolactone and 0.02-0.1 part by weight of chain extender; the second layer includes: 60-80 parts by weight of polypropylene carbonate, 5-15 parts by weight of poly (adipic acid/terephthalic acid) butylene terephthalate (PBAT), 5-15 parts by weight of polycaprolactone and 0.02-0.1 part by weight of chain extender.

Therefore, the composite membrane with the rights biodegradation provided by the specification has a three-layer structure which is overlapped, the three-layer interface has better intermiscibility, and the puncture performance, toughness, strength, edge sealing heat sealing indexes and the like of the composite membrane are ensured to meet the requirements of express transportation processes. In addition, the composite film has good retention performance on the adhesive and the release film, can ensure the durability of the adhesive and the release film, and avoids the defect that the adhesive of the express bag made of the existing biodegradable material is not firm.

Here, the polycaprolactone component has not only good compatibility with the plastic starch, but also good degradability in water and soil environments.

Here, the polypropylene carbonate and the poly (adipic acid/terephthalic acid) butylene and the like impart good barrier properties to the composite film.

It should be understood that the specific contents of the components of the first and third layers may be the same or different. For example, the first layer comprises 70 parts by weight of plasticized starch; the third layer included 85 parts by weight of plasticized starch.

Alternatively, the polypropylene carbonate may be 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight.

In some embodiments of the present description, the first layer further comprises a first colorant, the third layer further comprises a third colorant, and the first colorant and the third colorant are different colors.

By adding the coloring agent into the first layer and the third layer, the light transmittance of the composite film is low, and the requirement of a consumer on privacy protection in the process of using the express delivery bag is met. Different coloring agents are added into the first layer and the third layer, so that more colors can be provided, the using mode of the composite film is increased, and the requirements of different users are met.

Optionally, the colorant is a color masterbatch.

As an alternative embodiment, the first colorant is a white masterbatch and the third colorant is a black masterbatch.

Further, the second layer also includes a second colorant. Optionally, the second colorant is the same color as the first colorant.

In some embodiments of the present description, the mass part of the first colorant and/or the second colorant is 4 to 10 parts;

in some embodiments of the present description, the third colorant is 2 to 6 parts by mass.

In some embodiments of the present description, the plasticized starch comprises 35 to 45 parts by weight of starch, 50 to 60 parts by weight of polybutylene adipate/terephthalate and 8 to 12 parts by weight of polylactic acid.

Compared with the method that starch is directly added into the composite film, the plasticized starch is used for the first layer and the third layer, so that the composite film can be prevented from being wetted and leached when the temperature and the humidity are changed, the phenomenon that oil is wet and sticky on the surface is avoided, and the composite film can adapt to various environmental conditions. At the same time, by using plastic starch, the overall cost of the composite membrane can be reduced and the degradation of the composite membrane in water and soil can be promoted.

Optionally, the plasticized starch comprises 38 to 42 parts by weight of starch. By adopting 38-42 parts by weight of starch, the performance of the composite film can better meet the requirement of preparing the express delivery bag.

Optionally, the content of raw starch in the first and third layers is not higher than 32%. Illustratively, the content of raw starch in the first and third layers may alternatively be 30%, 28%, 25%, 22%, 20%, etc.

In some embodiments of the present description, the chain extender is a polymer containing epoxy functional groups. The chain extender has good reactivity with end groups carried by polyesters such as polylactic acid, polycaprolactone, polypropylene carbonate, poly (adipic acid/terephthalic acid) butylene terephthalate and the like, has an obvious chain extension effect, can effectively improve the physical properties and the processing heat resistance of products, and avoids the performance reduction of materials caused by the reduction of molecular weight.

Optionally, the chain extender is selected from one or more of basf ADR4385, ADR4368 or ADR 4370.

Optionally, the chain extender includes styrene and glycidyl acrylate. Illustratively, the chain extender is selected from one or more of the group consisting of preferably easy SAG-002, SAG-005 or SAG-008.

In some embodiments, the epoxy functional group-containing polymer comprises an epoxy-terminated hyperbranched polymer (EHBP for short).

Optionally, the epoxy-terminated hyperbranched polymer is prepared by modifying hydroxyl groups at opposite ends of a compound containing an epoxy group, with hydroxyl-terminated hyperbranched polyester (abbreviated as HBPE) as a raw material.

The structure of the epoxy-terminated hyperbranched polymer is a highly branched three-dimensional sphere, and the epoxy-terminated hyperbranched polymer has a plurality of terminal epoxy groups and has the characteristics of higher functionality, good solubility, high activity and the like.

Alternatively, the epoxy group-containing compound modifies at least a portion of the terminal hydroxyl groups. It should be noted that the hydroxyl-terminated hyperbranched polyester includes a plurality of terminal hydroxyl groups, and there is steric hindrance, and the difficulty of modifying the terminal hydroxyl groups by the compound containing epoxy groups increases with the improvement of the modification ratio. The modification ratio can be adjusted by adjusting the reaction conditions, for example, the ratio of the epoxy group-containing compound, and will not be described in detail here.

In some embodiments, the hydroxy hyperbranched polyester comprises a structure of formula (i);

in some embodiments, the epoxy-terminated hyperbranched polymer comprises a structure represented by formula (ii);

as an alternative example, referring to fig. 1, the preparation method of the hydroxyl-terminated hyperbranched polyester comprises:

trimethylolpropane (TMP), 2, 2-dimethylolpropionic acid (DMPA) and P-toluenesulfonic acid (P-TSA) are used as raw materials, and the hydroxyl-terminated hyperbranched polyester is prepared by a one-step melt polycondensation method.

P-toluenesulfonic acid is used as a catalyst in the reaction.

Alternatively, the melt polycondensation conditions include:

stirring and reacting for 1.5-2.5 hours at the temperature of 135-145 ℃ under the protection of inert gas; and

and (4) carrying out reduced pressure distillation to continue the reaction for 1.5-2.5 hours.

The inert gas may be nitrogen, argon, helium, etc.

Wherein the reaction temperature may be 135 deg.C, 137 deg.C, 140 deg.C, 142 deg.C, 145 deg.C.

The reaction time may be 1.5 hours, 1.8 hours, 2.0 hours, 2.3 hours, or 2.5 hours.

Wherein the stirring speed can be 170r/min, 175r/min, 180r/min and 185 r/min.

Wherein the pressure of the reduced pressure distillation is not more than 0.10mPa, for example 0.08 mPa.

In some embodiments, the method of preparing the epoxy-terminated hyperbranched polymer comprises:

and modifying the terminal hydroxyl of the terminal hydroxyl hyperbranched polyester by using epoxy chloropropane to prepare the modified polyester.

As an alternative example, the synthetic route of the epoxy-terminated hyperbranched polymer is as follows:

wherein,

optionally, the epoxy-terminated hyperbranched polymer comprises a structure represented by formula (iii);

optionally, the modifying specifically includes:

(1) dropwise adding boron trifluoride diethyl etherate and epichlorohydrin into the prepared hydroxyl-terminated hyperbranched polyester at 78-82 ℃, such as 80 ℃, and reacting for 1.5-2.5 hours, such as 2 hours, under stirring. Here, a small amount of epichlorohydrin was added and boron trifluoride diethyl etherate was added dropwise. The rotational speed of the stirring can be, for example, 180r/min, 200r/min or 210 r/min.

(2) And continuously adding saturated sodium hydroxide solution, reacting for 1.5-2.5 hours, heating to 98-102 ℃, and distilling under reduced pressure. Wherein the reaction time may be 2 hours. Wherein the temperature after the temperature rise may be 100 ℃.

The vacuum distillation can remove water, epichlorohydrin, and other substances in the reaction product.

(3) Reducing the temperature to 48-52 ℃ after reduced pressure distillation, adding a solvent such as trichloromethane, dissolving the product, standing, carrying out suction filtration, and carrying out reduced pressure distillation to obtain the target product-terminated epoxy hyperbranched polymer. Here, the target product was a viscous liquid.

In some embodiments of the present description, the thickness ratio of the first layer, the second layer, and the third layer is: (25-35%), 30-50%, 25-35%).

Optionally, the thickness of the composite film is 0.03mm to 0.08 mm. The composite film with the thickness is suitable for preparing express bags.

In a second aspect of the present specification, there is also provided a method for preparing a fully biodegradable composite membrane, comprising:

The fully biodegradable composite membrane prepared in such a way can ensure that good bonding performance is kept between layers.

Optionally, the first masterbatch and the second masterbatch are prepared by a twin screw granulator.

Alternatively, the time of mixing may be determined by the homogeneity of the raw materials, for example 5 minutes.

In some embodiments of the present disclosure, before the obtaining of the fully biodegradable composite film by performing three-layer co-extrusion film blowing with the first master batch and the second master batch, the method further includes:

In some embodiments of the present description, the plasticized starch is prepared by:

and uniformly mixing the starch, the polybutylene (adipate/terephthalate) and the polylactic acid, adding a phase solvent, co-extruding, drawing strips, granulating and drying to obtain the plasticized starch.

Optionally, in the step of adding the phase solvent for co-extrusion, bracing and granulating to obtain the plasticized starch, the phase solvent can be added in a side feeding manner.

Optionally, the phase solvent is a biobased glycerol.

The water content of starch is usually about 14%, and the water content of the plasticized starch obtained in this example is 180 to 210 ppm. Optionally, the water is 200 ppm.

The moisture in the plasticized starch is reduced, so that the performance of the plasticized starch in a warm and humid environment is guaranteed, and the plasticized starch is prevented from getting damp.

Optionally, before the drying step, a step of granulating is further included.

Optionally, the starch, poly (butylene adipate/terephthalate) and polylactic acid are blended using a cold mixing process.

Optionally, the drying method is vacuum drying.

Optionally, the raw starch is corn starch.

In a third aspect of the present specification, there is also provided a express delivery bag, wherein the express delivery bag is made of the fully biodegradable composite film.

Optionally, the express bag is made using an edge sealing bag machine.

The technical solution of the present invention will be specifically described below with reference to specific examples.

Example 1

The express delivery bag made of the full-biodegradable composite film is prepared from the following components in parts by weight.

A first layer: 75 parts of plasticized starch, 10 parts of polylactic acid, 15 parts of polycaprolactone, 43850.02 parts of ADR and 4 parts of white master batch;

a second layer: 70 parts of polypropylene carbonate, 15 parts of poly (adipic acid/terephthalic acid) butylene terephthalate, 15 parts of polycaprolactone, 43850.02 parts of ADR and 4 parts of white master batch;

and a third layer: 75 parts of plasticized starch, 10 parts of polylactic acid, 15 parts of polycaprolactone, 43850.02 parts of ADR and 2 parts of black master batch.

Wherein, plasticized starch is obtained through coextrusion brace granulation, and it includes: 50 parts by weight of corn starch, 35 parts by weight of polybutylene (adipate/terephthalate) and 10 parts by weight of polylactic acid and 5 parts by weight of a phase solvent; wherein the phase solvent is a bio-based glycerol.

Example 2

A first layer: 80 parts of plasticized starch, 5 parts of polylactic acid, 15 parts of polycaprolactone, 43680.02 parts of ADR and 6 parts of white master batch;

a second layer: 70 parts of polypropylene carbonate, 15 parts of poly (adipic acid/terephthalic acid) butylene terephthalate, 15 parts of polycaprolactone, 43680.02 parts of ADR and 6 parts of white master batch;

and a third layer: 80 parts of plasticized starch, 5 parts of polylactic acid, 15 parts of polycaprolactone, 43680.02 parts of ADR and 3 parts of black master batch.

Wherein, plasticized starch is obtained through coextrusion brace granulation, and it includes: 35 parts of corn starch, 50 parts of poly (adipic acid/terephthalic acid) butyl diester, 12 parts of polylactic acid and 3.5 parts of a phase solvent; wherein the phase solvent is a bio-based glycerol.

Example 3

A first layer: 70 parts of plasticized starch, 15 parts of polylactic acid, 15 parts of polycaprolactone, 43700.02 parts of ADR and 10 parts of white master batch;

a second layer: 70 parts of polypropylene carbonate, 15 parts of poly (adipic acid/terephthalic acid) butylene terephthalate, 15 parts of polycaprolactone, 43700.02 parts of ADR and 10 parts of white master batch;

and a third layer: 70 parts of plasticized starch, 15 parts of polylactic acid, 15 parts of polycaprolactone, 43700.02 parts of ADR and 4 parts of black master batch.

Wherein, plasticized starch is obtained through coextrusion brace granulation, and it includes: 45 parts of corn starch, 50 parts of poly (adipic acid/terephthalic acid) butyl diester, 10 parts of polylactic acid and 4.5 parts of a phase solvent; wherein the phase solvent is a bio-based glycerol.

Example 4

This example differs from example 1 in that: the composition of the plasticized starch in the first and third layers is: 35 parts by weight of corn starch, 53 parts by weight of polybutylene (adipate/terephthalate), 12 parts by weight of polylactic acid and 3 parts by weight of a phase solvent.

Example 5

This example differs from example 1 in that: the composition of the plasticized starch in the first and third layers is: 40 parts of corn starch, 50 parts of poly (adipic acid/terephthalic acid) butyl diester, 10 parts of polylactic acid and 4 parts of a phase solvent.

Example 6

The present embodiment differs from embodiment 2 in that: the plasticized starch in the first and third layers was 95 parts.

Example 7

This example differs from example 1 in that: ADR4385 was replaced with EHBP. The preparation method of the terminal epoxy type hyperbranched polymer is described in detail below. Wherein, the reagents used are all commercially available.

Preparation of HBPE

(1) Weighing 5.02g of TMP, 99.95g of DMPA and 0.37g of P-TSA, mixing the three reagents and pouring the mixture into a three-neck flask;

(2) sequentially connecting a three-neck flask in an oil bath pot into a stirrer, a reflux condenser tube and a thermometer, heating the oil bath pot to 140 ℃, starting a stirring paddle when reactants in the three-neck flask are molten without starting the stirring paddle, starting timing, keeping the rotating speed at 180r/min, and reacting for two hours under the protection of nitrogen;

(3) after 2h of reaction by distillation under reduced pressure (0.08mPa), the reaction was stopped and a hard, brittle, translucent solid formed after the product had cooled.

Preparation of EHBP

(1) After the temperature of the reaction mixture in example 1 was reduced to 80 ℃, 2.5mL of boron trifluoride diethyl etherate was slowly added to the reaction mixture using a constant pressure funnel, and 100mL of epichlorohydrin was slowly added dropwise to the reaction mixture using a constant pressure funnel, in this order, a small amount of epichlorohydrin was added first and then boron trifluoride diethyl etherate was added dropwise. As boron trifluoride diethyl etherate is easy to react with water, the boron trifluoride diethyl etherate is kept in an anhydrous state when being added, and the color of a reactant is orange after the epichlorohydrin and the boron trifluoride diethyl etherate are added dropwise. The temperature is kept at 80 ℃ for reaction for 2h, and the color is changed from orange to yellow after the rotation speed is kept at 200 r/min.

(2) The temperature of the reaction mixture was maintained at 80 ℃, and 30mL of saturated sodium hydroxide solution was added and the reaction was carried out for 2 h. After the reaction is finished, when the temperature is raised to 100 ℃, the reaction product is subjected to reduced pressure distillation by a circulating water pump, and substances such as water, epichlorohydrin and the like in the reaction product are removed.

(3) After distillation under reduced pressure, the temperature was again lowered to 50 ℃ and 200mL of chloroform was added thereto, and the mixture was stirred until the product was dissolved. After the product was dissolved, the mixture was allowed to stand, and solid-liquid separation between a white solid and a yellow liquid was observed. And then carrying out suction filtration, and finally carrying out reduced pressure distillation to obtain orange yellow viscous liquid, namely the target product epoxy-terminated hyperbranched polymer EHBP with the structure shown in the formula (III).

Taking a trace target product and a proper amount of dried KBr crystals, grinding the target product and the dried KBr crystals into powder with the particle size less than or equal to 2 mu m in an agate mortar, tabletting the powder to prepare a sample, pressing the sample into a complete transparent sheet, and performing FTIR (infrared fluorescence spectroscopy) test, wherein the scanning range is set to be 4000-500 cm-^-1Scan 32 times, and see figure 2 for details of the results.

As can be seen from FIG. 2, the absorption peak of EHBP ester group is 1740cm^-1All appear in the formula (I), and the trans epoxy ring is 837cm^-1Vibration occurs, the cis epoxy ring is 908cm^-1Vibration also occurred at the spot, and thus it was confirmed that the distance was 1256cm^-1Is a ternary epoxy ether group; -CH₂-O-CH₂Absorption peak at 1101cm^-1Appears at 3550cm^-1The absorption peak appeared is that of hydroxyl group, and is 2700cm^-1The position is a C-H bond stretching vibration peak. In summary, the composition can be determined to be an epoxy terminated hyperbranched polyester.

Example 8

This example differs from example 7 in that: the amount of EHBP added was 0.04 part.

Example 9

This example differs from example 7 in that: the amount of EHBP added was 0.10 part.

Comparative example 1

The present comparative example differs from example 2 in that: the plasticized starch in the first and third layers was replaced with starch, poly (adipic/terephthalic acid) butylene ester, and polylactic acid in the same proportions, that is, the starch in this comparative example was not pelletized by co-extrusion ribbing.

Comparative example 2

The present comparative example differs from example 2 in that: except for black and white master batches, the first layer, the second layer and the third layer are replaced by modified blown film grade master batches commonly used in the market, and the components comprise 60 percent of poly (adipic acid/terephthalic acid) butylene succinate, 5 percent of polylactic acid, 30 percent of starch and 5 percent of special master batches for a plasticizer.

Comparative example 3

The present comparative example differs from example 2 in that: the proportion of master batch and master batch of each layer is unchanged, and when the fully biodegradable composite film is formed, the feeding proportion of the three layers is different.

Comparative example 4

The present comparative example differs from example 2 in that: the raw materials of the second layer comprise: 5 parts of polylactic acid, 80 parts of poly (adipic acid/terephthalic acid) butylene succinate, 15 parts of polycaprolactone, 43680.02 parts of ADR, and 6 parts of white master batch.

The above nine examples and comparative examples 1 to 4 were prepared as follows, wherein the steps not involved, for example comparative example 1, which did not involve the preparation of plasticized starch, were omitted.

According to the embodiments 1-9 and the proportion of each proportion, firstly, uniformly mixing the components except the color master batch, and granulating by using a double-screw granulator to obtain master batches of each layer; the preparation method of the plasticized starch comprises the following steps: dehydrating the corn starch to obtain starch with the water content of 8-9%; and uniformly mixing the starch, the polybutylene adipate/terephthalate and the polylactic acid according to the proportion, adding a phase solvent, co-extruding, bracing and granulating to obtain the plasticized starch.

Wherein, the specific conditions of the co-extrusion bracing granulation for preparing the plasticized starch are as follows: the temperature of each zone of the double-screw granulator set is set as follows: first zone 90 deg.C, second zone 120 deg.C, third zone 125 deg.C, fourth zone 130 deg.C, fifth zone 135 deg.C, sixth zone 135 deg.C, seventh zone 140 deg.C, eighth zone 140 deg.C, ninth zone 145 deg.C, tenth zone 145 deg.C, eleventh zone 150 deg.C, twelfth zone 150 deg.C, thirteenth zone 150 deg.C, and head 150 deg.C; the screw speed was set at 300 rpm.

Wherein, the conditions for preparing each layer of master batch are as follows: the temperature of each zone of the double-screw granulator set is set as follows: first zone 90 deg.C, second zone 120 deg.C, third zone 125 deg.C, fourth zone 130 deg.C, fifth zone 135 deg.C, sixth zone 135 deg.C, seventh zone 135 deg.C, eighth zone 135 deg.C, ninth zone 135 deg.C, tenth zone 140 deg.C, eleventh zone 140 deg.C, twelfth zone 140 deg.C, thirteenth zone 130 deg.C, and head 130 deg.C; the screw speed was set at 220 rpm.

And then respectively mixing the master batches of all layers and the master batches, adding the mixture into a three-layer hopper corresponding to three-layer co-extrusion equipment, wherein the feeding proportion is as follows: 1: 1: and 1, blowing the film to obtain the full-biodegradation composite film, wherein the thickness of the full-biodegradation composite film is 5.5 filaments.

Preparation method of comparative example 3

The preparation methods of comparative example 3 and example 2 are different in that: the feeding proportion is 2: 1: 2. comparative example 3 the thickness of the fully biodegradable composite film obtained by blowing the film was 5.5 filaments.

The full-biodegradable composite films prepared in examples 1-9 and comparative examples 1-4 are used for manufacturing express bag products by using an edge sealing bag making machine. The express bag products corresponding to the embodiments 1-9 are numbered as I, II, III, IV, V, VI, VII, VIII and IX in sequence; the express bag products corresponding to the comparative examples are sequentially numbered A, B, C, D. And respectively testing the tensile property, the right-angle tearing property, the heat-sealing edge heat-sealing property, the puncture resistance, the pendulum impact resistance, the light transmittance and the material breaking property of each product.

Wherein, tensile test detects the tensile properties of express delivery bag. Specifically, according to the test of GB/T1040.3-2006, the sample adopts type 2, the length is 150mm, the width is 15mm, and the test speed is 200 mm/min. The sample was examined in both the longitudinal and transverse directions and corresponding data was obtained.

Wherein, the right angle of detecting express bag is torn to the right angle and the performance is torn. Specifically, the test was carried out according to the regulation of GB/T16578.2-2009. The sample was examined in both the longitudinal and transverse directions and corresponding data was obtained.

Wherein, the heat-seal test is used for detecting the heat-seal limit heat sealability of express delivery bag. Specifically, the test was performed according to QB/T2358. Wherein, puncture test is used for detecting the puncture resistance ability of express delivery bag. Specifically, the test is carried out according to GB/T10004-2008 standard.

Wherein, pendulum bob resistant test is used for detecting the pendulum bob impact resistance of express delivery bag. Specifically, the test was carried out according to GB/T8809-2015 standard.

Wherein, the light transmittance test is carried out according to the GB/T2410 standard.

The results of the performance tests on the express bag products I, II, III, IV, V, VI, VII, VIII, IX and the comparative product A, B, C, D are shown in Table 1 below.

As can be seen from the test results in Table 1, the performance of the express bag products I-IX can basically meet the use requirements of the express bags; wherein II, III, IV, V and IX have better performance. Comparing the products I-V with the product VI, the comprehensive performance of the product VI can be reduced, which shows that the product performance can be reduced due to the increase of the proportion of raw starch in the first layer and the third layer and the reduction of the proportion of polylactic acid. Compared with products VII to IX, the products VII to IX have better physical properties, and particularly, the toughness and the strength of the products are improved to a certain extent by adding excessive EHBP in the IX products, which is related to the multi-branched structure of the EHBP.

The comprehensive performance of the product A is obviously reduced, which shows that under the condition of the same raw materials, different feeding modes can also have great influence on the final performance of the product. For the use of the raw material starch, the plastic starch is obtained by co-extrusion, bracing and granulation, and then the master batches of the first layer and the third layer are formed, so that the plasticity of the raw material is improved, and further the comprehensive performance of the product is improved.

The overall performance of product B, C is much less than that of products I-VI, indicating that the formulation of the second layer and the effective proportions in the product can significantly improve the final properties of the product.

Further, the material breaking performance of the express bag product is tested. Utilize the hot melt adhesive to carry out broken material performance test to the express delivery bag, can detect the rubberizing performance of complex film.

Specifically, products I, II, VII, VIII, IX and products A to B were tested. The test method comprises the following steps: selecting a general water-based hot melt adhesive, setting the thickness of the hot melt adhesive to be 0.25mm, peeling the release film under three temperature conditions of-5 ℃, 25 ℃ and 40 ℃, then pasting for 1 minute, and testing the destructiveness, wherein the number of samples in each group is 50, and the test results are shown in Table 2. The term "material to be crushed" as used herein means: when tearing the express bag in hot melt adhesive department, hot melt adhesive and express bag do not separate to the express bag is damaged under the exogenic action.

TABLE 2 results of the material fracture Property test

As can be seen from the test results in table 2, compared with comparative example 1 and comparative example 2, the number of the broken materials in examples 1 and 2 of the present specification is excellent at each temperature, which indicates that the express delivery bags provided by the present invention have excellent adhesive performance. The number of the broken materials of the express bag products prepared by the formulas of examples 7 to 9 is higher than that of the express bag product of example 1 at various temperatures, and the rubberizing performance is better, probably because the multi-branched epoxy group of EHBP can react with the water-based hot melt adhesive, and the degumming problem is effectively avoided.

Further, the water vapor transmission rate and the oxygen transmission rate of the express bag product are tested.

Specifically, the product II of example 2 and the comparative products A to D were selected and tested according to GB/T21529, GB/T19789, and the results are shown in Table 3. It is to be noted that the products of the remaining examples have similar results and are not further listed here.

TABLE 3 Barrier Effect test

As can be seen from table 3, compared with the express bag product of the comparative example, the express bag product prepared by the formulation of the embodiment of the present specification has excellent water-blocking and oxygen-insulating properties, and can meet transportation and use requirements of various environments. Wherein, the addition of the polypropylene carbonate plays an important role in the water and oxygen blocking performance of the product.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the spirit of the present disclosure, features from the above embodiments or from different embodiments may also be combined, steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present description as described above, which are not provided in detail for the sake of brevity.

It is intended that the one or more embodiments of the present specification embrace all such alternatives, modifications and variations as fall within the broad scope of the appended claims. Therefore, any omissions, modifications, substitutions, improvements, and the like that may be made without departing from the spirit and principles of one or more embodiments of the present disclosure are intended to be included within the scope of the present disclosure.

Claims

1. The full-biodegradable composite membrane is characterized by comprising a first layer, a second layer and a third layer which are sequentially laminated;

2. The fully biodegradable composite film according to claim 1, wherein the plasticized starch comprises 35-45 parts by weight of starch, 50-60 parts by weight of polybutylene adipate/terephthalate and 8-12 parts by weight of polylactic acid.

3. The fully biodegradable composite film according to claim 2, wherein the plasticized starch comprises 38-42 parts by weight of starch.

4. The fully biodegradable composite membrane according to claim 1, wherein the chain extender comprises at least one of epoxy-terminated hyperbranched polymer or styrene and glycidyl acrylate.

5. The fully biodegradable composite membrane according to claim 1, wherein the epoxy-terminated hyperbranched polymer comprises a structure represented by formula (II);

6. the fully biodegradable composite membrane according to claim 1, wherein the thickness ratio of the first, second and third layers is: (25-35%), 30-50%, 25-35%).

7. A preparation method of a full-biodegradable composite membrane is characterized by comprising the following steps:

8. The preparation method according to claim 7, wherein before the obtaining of the fully biodegradable composite film by performing three-layer co-extrusion film blowing with the first masterbatch and the second masterbatch, the method further comprises:

9. The method of claim 7, wherein the plasticized starch is prepared by:

10. A express delivery bag, which is made of the full-biodegradable composite film according to any one of claims 1-6.