CN112553967A

CN112553967A - Degradable kraft paper buffer air cushion film with good barrier property and preparation method thereof

Info

Publication number: CN112553967A
Application number: CN202011412411.3A
Authority: CN
Inventors: 涂宗铃; 陈赐辉
Original assignee: Xiamen Ameson New Material Inc
Current assignee: Xiamen Ameson New Material Inc
Priority date: 2020-12-04
Filing date: 2020-12-04
Publication date: 2021-03-26
Anticipated expiration: 2040-12-04
Also published as: CN112553967B

Abstract

The invention relates to the technical field of plastic films, in particular to a degradable kraft paper buffer air cushion film with good barrier property and a preparation method thereof. It comprises an outer layer, a middle layer and an inner layer; the preparation raw material of the inner layer comprises PBAT; the preparation raw material of the middle layer comprises polymethyl ethylene carbonate; the outer layer is made of kraft paper, and the content of needle pulp in the kraft paper is not lower than 95 wt%. The kraft paper buffer air cushion film provided by the invention has excellent degradability, and completely avoids the problem of environmental pollution caused by the traditional plastic film. In addition, the mechanical strength, the barrier property and the heat sealing property of the buffer air cushion film are effectively improved by the targeted regulation and control of the components, the proportion, the physical and chemical properties and the like of the three layers of raw materials inside and outside the film. In addition, the water resistance and hand feeling of the film at different temperatures are effectively improved by adjusting the physical and chemical properties of kraft paper used in the film, the components and the proportion of hydrolysis resistant agents and the like.

Description

Degradable kraft paper buffer air cushion film with good barrier property and preparation method thereof

Technical Field

The invention relates to the technical field of plastic films, in particular to a degradable kraft paper buffer air cushion film with good barrier property and a preparation method thereof.

Background

Nowadays, plastic film products are widely applied to various industries of human society, and mainly made of PE (polyethylene) materials. The PE film, namely the polyethylene film, is commonly used as a packaging material for various products, and has the characteristics of rich raw material resources, moderate price, stable and reliable production process, superior product comprehensive performance and the like, so that the application range of the PE film is gradually expanded, and particularly in the field of packaging and protection films, the dosage of the PE film always accounts for the first of the general packaging materials. With the development of the e-commerce industry, the usage amount of the cache air cushion film is increased day by day, most of the cache air cushion films on the market are produced by taking PE or PE/PA as materials, and because of the non-degradability, the pollution to the environment is increased day by day while the economic benefit is created.

Although, it is also disclosed in the prior art to prepare films having degradable properties by combining kraft paper with the above-mentioned thermoplastic components. However, kraft paper is poor in waterproof property because it is mainly composed of wood pulp, and is limited in use in the field of cushioning, packaging. In addition, because the performance difference between the existing thermoplastic components and kraft paper is large, the thermoplastic components cannot be tightly bonded with thermoplastic high polymer materials, the interlayer density is not high, the gas barrier property and the mechanical strength of the air cushion film are influenced, and the service life of the air cushion film is shortened.

Disclosure of Invention

In view of the above technical problems, a first aspect of the present invention provides a degradable kraft paper cushion film with good barrier property, which includes an outer layer, a middle layer and an inner layer; the preparation raw material of the inner layer comprises PBAT; the preparation raw material of the middle layer comprises polymethyl ethylene carbonate; the outer layer is made of kraft paper, and the content of needle pulp in the kraft paper is not lower than 95 wt%.

As a preferable technical scheme, the molar content of the terephthalic acid chain segment in the PBAT structure is 30-45%.

As a preferable technical scheme of the invention, the weight average molecular weight of the PBAT is 10-15 ten thousand.

As a preferred technical scheme of the invention, the melt index of the PBAT under the condition of 190 ℃/2.16kg is 1-10g/10 min.

As a preferable technical scheme of the invention, the preparation raw materials of the inner layer also comprise an anti-hydrolysis agent and an opening agent; the content of the hydrolysis resistant agent and the content of the opening agent are respectively 0.3-0.5 wt% and 0.4-0.6 wt%.

As a preferable technical scheme, the weight average molecular mass of the polymethyl ethylene carbonate is 15-20 ten thousand; preferably, the melt index of the polymethyl ethylene carbonate is 1-8 g/10min under the condition of 190 ℃/2.16 kg.

As a preferable technical scheme of the invention, the preparation raw material of the middle layer also comprises an opening agent; the content of the polymethyl ethylene carbonate at least accounts for 99 wt% of the total mass of the intermediate layer preparation raw materials.

In a preferred embodiment of the present invention, the kraft paper has a grammage of not more than 30 g.

The invention provides a preparation method of the degradable kraft paper buffer air cushion film with good barrier property, which comprises the following steps:

(1) placing a kraft paper coiled material on a machine platform placing frame, drawing the kraft paper coiled material to a casting die head of a film coating machine through a drawing wheel, and heating a drawing roller, the casting die head and a screw;

(2) adding the preparation raw material of the middle layer into a first laminating machine; adding the preparation raw materials of the inner layer into a second film laminating machine;

(3) spraying the surface of kraft paper on a machine station placing frame by using a first film coating machine and a second film coating machine in sequence, pressing by using a cooling pressing wheel, slitting and rolling to obtain the finished product;

the temperature range of the first laminating machine is 170-220 set degrees; the temperature range of the second film laminating machine is 145-190 ℃.

As a preferred technical scheme, kraft paper is preheated before being sprayed by a first film spraying machine in the step (3), and the preheating temperature is 60-100 ℃; the temperature range of the cooling pinch roller is 5-10 ℃, and the cooling pinch roller is made of tungsten steel.

Has the advantages that: the kraft paper buffer air cushion film provided by the invention has excellent degradability, and completely avoids the problem of environmental pollution caused by the traditional plastic film. In addition, the mechanical strength, the barrier property and the heat sealing property of the buffer air cushion film are effectively improved by the targeted regulation and control of the components, the proportion, the physical and chemical properties and the like of the three layers of raw materials inside and outside the film. In addition, the water resistance and hand feeling of the film at different temperatures are effectively improved by adjusting the physical and chemical properties of kraft paper used in the film, the components and the proportion of hydrolysis resistant agents and the like.

Detailed Description

The technical features of the technical solutions provided by the present invention will be further clearly and completely described below with reference to the specific embodiments, and it should be apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The words "preferred", "preferably", "more preferred", and the like, in the present invention, refer to embodiments of the invention that may provide certain benefits, under certain circumstances. However, other embodiments may be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

It should be understood that other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about".

The melt index measurement described in the present invention was carried out at 190 ℃ under 2.16 kg.

The invention provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer; the preparation raw material of the inner layer comprises PBAT; the preparation raw material of the middle layer comprises polymethyl ethylene carbonate; the outer layer is made of kraft paper, and the content of needle pulp in the kraft paper is not lower than 95 wt%.

The degradable kraft paper buffer air cushion film with good barrier property has a three-layer composite structure, namely an outer layer, a middle layer and an inner layer in sequence, wherein the thickness of each layer can be adjusted according to actual needs. In some embodiments, the degradable kraft paper buffer air cushion film with good barrier property has a thickness of 30-100 μm, wherein the outer layer is mainly kraft paper, and the thickness of the outer layer can reach 3-5C (i.e. 30-50 μm), and the thickness of the inner layer and the middle layer can be 1-3C (i.e. 10-30 μm). In some preferred embodiments, the thickness of the inner and middle layers is the same. Preferably, the thickness of the middle layer and the inner layer is 10 μm (1C).

The inner layer preparation raw material of the degradable kraft paper buffer air cushion film with good barrier property comprises PBAT, and further preferably also comprises a proper amount of auxiliary agent, wherein preferably, the auxiliary agent comprises a hydrolysis-resistant agent and an opening agent; the content of the hydrolysis resistant agent and the content of the opening agent are respectively 0.3-0.5 wt% and 0.4-0.6 wt%.

The inner layer preparation raw material of the three-layer composite film comprises PBAT. The PBAT described in the present invention is a copolymer of butylene adipate and butylene terephthalate. PBAT is a semicrystalline polymer, generally has a crystallization temperature of about 100 ℃ and a melting point of about 120 ℃, and has excellent degradation properties of aliphatic polyesters and good mechanical properties of aromatic polyesters. Further, the melt index of the PBAT at 190 ℃/2.16kg is 1-10g/10 min.

In the invention, as the kraft paper used for the outer layer is a forming material, when the preparation raw materials of the middle layer and the inner layer are melted and laminated on the surface of the formed kraft paper by a laminating machine, the surface of the kraft paper in the middle layer of the laminated film cannot be well spread and wetted due to the high viscoelasticity of the solution extruded from the laminating machine, so that an obvious interface exists between the solution of the inner layer and the solution of the middle layer, the gas barrier property of the film is influenced, and particularly when the melt index of PBAT is low, the viscoelasticity of the solution is too high, which is particularly obvious. The applicant finds that the fluidity of the inner layer raw material solution can be effectively improved by the targeted control of the physical and chemical properties (such as melt index) of the inner layer preparation raw material, so that the inner layer raw material solution can be melted and extruded by a laminating machine, and can be more fully spread on the middle layer on the surface of kraft paper during laminating and molding on the kraft paper, and the formation of a clear interface between the inner layer raw material solution and the kraft paper can be avoided. However, the applicant finds that when the melt index of PBAT is too high, the PBAT can be better spread on the surface of kraft paper due to higher fluidity of the prepared raw material solution, but because the strength of the prepared raw material solution is too low, the solution is easily coated on the surface of the middle layer of the kraft paper to cause uneven coating thickness, thin film edges and serious edge effect, thus increasing the production cost. Especially when the hydrolysis resistant agent, the opening agent and other auxiliary agents are added into the inner layer preparation raw material, the phenomenon is more obvious. The applicant speculates that these small molecular components such as hydrolysis resistance agent and opening agent play a role in plasticization when the inner layer raw material is subjected to film coating molding, and further improve the fluidity of the solution.

In some embodiments, the PBAT has a weight average molecular weight of 10 to 15 ten thousand.

Preferably, the molar content of the terephthalic acid segment in the PBAT structure is 20-75%.

Further preferably, the molar content of the terephthalic acid chain segment in the PBAT structure is 30-45%

In the invention, in order to avoid the excessively high degradation speed of the composite film and maintain the strength performance of the product, the molar content of a BT (butylene terephthalate) chain segment in a PBAT structure is correspondingly regulated and controlled, so that the molar content is not too high, the normal degradation of the composite film is avoided being influenced, and simultaneously, the molar content is not too low, so that the degradation is too high, the normal use of the product is influenced, and the molar content of BT is controlled to be 20-75%.

The opening agent is also called as slipping agent, and the opening performance of the film can be improved by using a proper amount of the opening agent in the inner layer of the buffer air cushion film, so that adverse factors such as adhesion of the film in the preparation and use processes can be effectively avoided. The type of the opening agent in the present invention is not particularly limited, and various opening agents known to those skilled in the art can be selected, including but not limited to amide opening agents, inorganic opening agents, and the like, such as oleamide, erucamide, silica, and the like. The film inner layer preparation raw material is added with a certain amount of the opening agent, so that the material can be uniformly discharged from a die after being melted, the roller sticking phenomenon is avoided during film spraying, and the problem that the inner layer is mutually stuck with a buffer air cushion air chamber during rolling and cannot be opened and inflated during the use of a finished product is solved. Experiments show that the phenomenon of nonuniform film coating can occur when the dosage of the opening agent is less than 0.4 percent, and the problem of poor adhesion with the middle layer can occur when the dosage is more than 1 percent.

The hydrolysis inhibitor of the present invention is a component capable of reacting with a component such as a polyester, e.g., PBAT, in the film system to cause the easily hydrolyzable component to generate a carboxylic acid upon hydrolysis and thereby further promote the degree of hydrolysis, and is a component capable of consuming the generated carboxylic acid to avoid further promotion of hydrolysis by the component.

In some preferred embodiments, the anti-hydrolysis agent comprises bis (2, 6-diisopropylphenyl) carbodiimide.

Further preferably, the hydrolysis resistant agent further comprises a polymeric carbodiimide; preferably, the polymeric elastomer of the polymeric carbodiimide is 1,3, 5-triisopropylphenyl-2, 4-carbodiimide; preferably, the polymerized carbodiimide has a carbodiimide-diimine content of not less than 15%; preferably, the number average molecular weight of the polymerized carbodiimide is 2.5 to 3.5 ten thousand; preferably 3 million (e.g., of Lailan industries, Ltd., Shanghai)

2 particles).

Further, the weight ratio of the bis (2, 6-diisopropylphenyl) carbodiimide to the polymeric carbodiimide is (1-3): 1.

further, the weight ratio of the raw materials is 2.6: 1.

however, the applicant also found that when the molar content of the terephthalic acid segment in the PBAT structure is 30-45%, the barrier property of the film can be effectively improved, and particularly after a certain content of hydrolysis resistant agent is used, the barrier property of the film is remarkably improved. The applicant speculates that the hydrolysis resistant agent in the inner layer raw material captures carboxylic acid generated by hydrolysis of PBAT, so that the active group of PBAT, the hydroxyl group of the reaction group on the surface of PBAT and the captured water molecule are subjected to linking reaction while further hydrolysis of PBAT is avoided, the degraded molecular chain is coupled, the weight average molecular weight is improved, the material performance is recovered, and the degradation is delayed. Meanwhile, the hydrolysis resistant agent can also react with hydroxyl on the surface of the PPC in the film spraying process to improve the compatibility of the middle layer and the inner layer. The adhesive force and the compactness between the raw materials of the inner layer and the middle layer are further improved, thereby being beneficial to improving the barrier property of the film.

In addition, the applicant unexpectedly discovers that when the hydrolysis resistant agent with a specific structure compounded in a specific ratio is adopted, the gas barrier property of the prepared film is obviously improved, the hand feeling of the film can be effectively improved, and the high-temperature (40 ℃) waterproof performance of the film is obviously improved. Probably because the adopted carbodiimide hydrolysis-resistant agent structure contains a large number of benzene ring structures, pi-pi interaction force can be formed between the carbodiimide hydrolysis-resistant agent structure and benzene ring structures in a PBAT structure, and the orderly arrangement of raw materials during forming is promoted through pi-pi accumulation when the raw material solution of the inner layer is formed by film coating, which is beneficial to improving the density of the inner layer. In addition, through adopting the polymeric carbodiimide with certain molecular weight, the migration speed of a molecular chain of the hydrolysis-resistant agent is regulated and controlled, the molecule entanglement between the hydrolysis-resistant agent and an inner-layer preparation raw material PBAT is regulated, the mutual group force between active hydroxyl and active groups in the hydrolysis-resistant agent in the PBAT structure is increased, the interaction force between moisture in the environment is correspondingly weakened, the hydrolysis-resistant agent is equal to that in the environment, so that the sensitivity degree of the film to water molecules in the environment is reduced, and the waterproofness of the film is effectively improved. Meanwhile, under the synergistic action between the PBAT with the specific structure and the hydrolysis resistant agent compounded with the specific structure and the content, the raw materials of the film are orderly arranged, the microstructure is further improved, the surface of the film is softer and smoother, and the hand feeling of the film is improved.

The middle layer of the film of the invention is prepared from raw materials containing poly (methyl ethylene carbonate) (PPC). The polymethyl ethylene carbonate is a degradable environment-friendly material synthesized by taking carbon dioxide and propylene oxide as raw materials.

In some embodiments, the poly (methyl ethylene carbonate) has a weight average molecular mass of 15 to 20 ten thousand; preferably, the melt index of the polymethyl ethylene carbonate under the condition of 190 ℃/2.16kg is 1-8 g/10 min; further, the melt index is 2-3 g/10 min. In order to improve the fluidity of the raw material solution, an auxiliary agent which is conventional in the art may be added as needed.

The applicant finds that in the process of preparing the three-layer composite structure film, when the content of the polymethyl ethylene carbonate in the raw materials for preparing the middle layer is lower, the density of the composite film and the density of the product of the composite film are obviously reduced, the gas barrier performance of the product is seriously influenced, and the phenomena of serious gas leakage and the like occur in the product of the buffer air cushion film. Wherein, after the middle layer is separately made into a film, when the polymethyl ethylene carbonic ester in the preparation raw materials is respectively 80%, 90% and 98% (the rest is PBAT), the oxygen permeability of the film is respectively 512 cm³/(m².d.atm0]、471[cm³/(m².d.atm0]And 33[ cm ] of³/(m².d.atm0]The oxygen permeability, air permeability and the like of the film have important influences on the buffering effect, physical properties and the like of the buffering film product. Therefore, it is further preferable that the content of the polymethylethylene carbonate in the intermediate layer preparation raw material of the three-layer composite structure film of the present invention is not less than 99 wt%.

In some preferred embodiments, the raw material for preparing the middle layer further comprises a mouth-opening agent. In the invention, the components of the opening agent in the raw material for preparing the middle layer are not particularly limited, and the opening agent same as the opening agent in the inner layer can be selected, including but not limited to amide opening agents, inorganic opening agents and the like, such as oleamide, erucamide, silicon dioxide and the like. A certain amount of opening agent is added into the middle layer, so that the opening agent is slowly extruded to the surface of the film, and the film has long-term opening anti-adhesion performance. Further preferably, the opening slipping agent is a mixture of erucamide and fumed silica, and the weight ratio is 1: 1. the applicant finds that when the compounded components are used as the opening slipping agent, the slipping effect of the film can be obviously improved, the film does not separate out after slipping for a long time, and the mechanical strength and the waterproof performance of the film can be greatly improved.

The kraft paper is prepared by pulping the wood fiber of coniferous trees by a chemical method, pulping in a pulping machine, adding sizing material, dye and the like, and finally making into paper in a paper machine. Due to the material and the structure of the kraft paper, the three-layer composite film has excellent degradability, and the pollution of the film to the environment can be effectively avoided. In addition, a large amount of fillers are often added into the existing kraft paper to increase rigidity so that the existing kraft paper has good strength, however, the kraft paper is easy to have the problems of brittleness and edge cracking in the process of preparing the three-layer composite structure film, even the kraft paper is easy to tear and break in the heating and drawing process of the laminated film due to the overhigh rigidity, when the kraft paper is made into products such as a cushion air cushion and the like, the inflation resistance is overhigh, the inflation unsaturated phenomenon occurs, and the normal use of the products is influenced.

In some embodiments, the kraft paper has a grammage of no more than 30 g.

More preferably, the grammage of the kraft paper is 20-28 g; preferably, the grammage is 26 g.

Grammage as used herein is the conventional unit of kraft weight measured in the art, and is the weight per meter of kraft paper, calculated according to methods conventional in the art. The applicant finds that the kraft paper can effectively avoid the problems of edge cracking, tearing and the like in the process of preparing the three-layer composite film by using the kraft paper. Meanwhile, the applicant also unexpectedly discovers that the surface characteristics of the three-layer composite film and the product thereof can be effectively improved through the interaction between the kraft paper and the middle layer raw material and the inner layer raw material with specific components and proportions, so that the three-layer composite film is lighter and thinner and has better hand feeling.

In the degradable kraft paper buffer air cushion film, the processing temperature of the PPC component of the main preparation raw material of the middle layer is at least above 185 ℃, the processing temperature of the PBAT component of the main preparation raw material of the inner layer is only about 145 ℃, and the phenomenon of film forming can not occur due to too large temperature difference of two materials when a double-layer film coating machine is used for mold stripping, so that a single film coating mode is used, and a production mode of simultaneous tape casting of two single-layer film coating machines is used.

In some embodiments, the kraft paper is preheated before spraying by using a first film spraying machine in the step (3), and the preheating temperature is 60-100 ℃ (preferably 80 ℃); the temperature range of cooling pinch roller is 5 ~ 10 degrees centigrade, and its material is the tungsten steel, and the cooling pinch roller that adopts other materials appears gluing the wheel phenomenon easily, is showing the normal processing preparation that influences composite film.

In some preferred embodiments, the spraying time interval between the first film coating machine and the second film coating machine adopted in the step (3) is not more than 1.5s, and preferably, kraft paper passes through the second film coating machine at the interval of 1 s. According to the invention, after the set temperature parameters of the traction roller, the first laminating machine and the second laminating machine are required, the motor is started, the traction roller drives the kraft paper, the kraft paper is heated, the surface temperature can reach 80 ℃ when the kraft paper reaches the position below the first laminating machine, the middle layer material PPC is laminated on the kraft paper, the heating of the kraft paper can increase the melt time of the PPC on the paper, the permeability of the PPC on the surface of the kraft paper is increased, the problem of the adhesive force of the kraft paper and the PPC is solved, meanwhile, the inner layer material passes through the laminating die head of the second laminating machine within 1s, covers the uncooled PPC melt, and finally, the outer layer, the middle layer and the inner layer are laminated together through the cooling pinch roller. The temperature setting range of the first laminating machine is 170-220 ℃, the temperature setting range of the second laminating machine is 145-190 ℃, and the temperature setting range of the traction roller is 60-100 ℃.

The present invention will be specifically described below by way of examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above disclosure are still within the scope of the present invention.

Examples

Example 1: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.2 wt% of PBAT, 0.4 wt% of hydrolysis resistant agent and 0.4 wt% of opening agent; the preparation raw materials of the middle layer comprise 99.6 wt% of polymethyl ethylene carbonate and 0.4 wt% of an opening agent; the outer layer is made of kraft paper.

The grammage of the kraft paper is 26g, and the content of the needle pulp is 98%; the molar content of a terephthalic acid chain segment in the PBAT structure is 40%, the weight average molecular weight is 12 ten thousand, and the melt index of the PBAT is 3.5g/10 min; the anti-hydrolysis agent is prepared from bis (2, 6-diisopropylphenyl) carbodiimide and polymeric carbodiimide(s) (II)

2) The weight ratio of the components is 2.6: 1; the opening agent is a mixture of erucamide and fumed silica, and the weight ratio is 1: 1; the weight average molecular mass of the polymethyl ethylene carbonate is 15 ten thousand, and the melt index of the polymethyl ethylene carbonate is 2.5g/10 min.

The preparation method of the degradable kraft paper buffer air cushion film with good barrier property comprises the following steps:

(1) placing a kraft paper coiled material with the width of 1.2m on a machine station placing frame, drawing the kraft paper coiled material to a casting die head of a film coating machine through a traction wheel, and heating a traction roller, the casting die head and a screw rod by a starter station heating device; the specific temperature parameters are shown in table 1 below:

TABLE 1

(2) Adding the preparation raw material of the middle layer into a first laminating machine; adding the preparation raw materials of the inner layer into a second film laminating machine; the arrangement sequence of the machine stations is as follows: a kraft paper placing rack, a traction roller, a film coating machine, a cooling press wheel and a slitting and winding device;

(3) the motor is started after the single temperature meets the parameter requirement, the traction roller drives the kraft paper and heats the kraft paper, the surface temperature can reach 80 ℃ when the kraft paper reaches the lower part of the first laminating machine, at the moment, the middle-layer material PPC is laminated on the kraft paper, the heating kraft paper can increase the melt time of the PPC on the paper, the permeability of the PPC on the surface of the kraft paper is increased, the problem of the adhesive force of the kraft paper and the PPC is solved, meanwhile, the middle-layer material passes through the laminating die head of the second laminating machine within 1s, the inner-layer material covers the uncooled PPC melt, and finally, the outer layer, the middle layer and the inner layer are laminated together through the cooling press wheel. The cooling pressing wheel is forged by a tungsten steel material, other materials can be stuck to the wheel, and finally the product is obtained by rolling and slitting.

Example 2: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.6 wt% of PBAT and 0.4 wt% of a mouth-opening agent; the preparation raw materials of the middle layer comprise 99.6 wt% of polymethyl ethylene carbonate and 0.4 wt% of an opening agent; the outer layer is made of kraft paper.

The grammage of the kraft paper is 26g, and the content of the needle pulp is 98%; the molar content of a terephthalic acid chain segment in the PBAT structure is 40%, the weight average molecular weight is 12 ten thousand, and the melt index of the PBAT is 3.5g/10 min; the opening agent is a mixture of erucamide and fumed silica, and the weight ratio is 1: 1; the weight average molecular mass of the polymethyl ethylene carbonate is 15 ten thousand, and the melt index of the polymethyl ethylene carbonate is 2.5g/10 min.

(1) placing a kraft paper coiled material with the width of 1.2m on a machine station placing frame, drawing the kraft paper coiled material to a casting die head of a film coating machine through a traction wheel, and heating a traction roller, the casting die head and a screw rod by a starter station heating device; the specific temperature parameters were the same as in example 1;

Example 3: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.2 wt% of PBAT, 0.4 wt% of hydrolysis resistant agent and 0.4 wt% of opening agent; the preparation raw materials of the middle layer comprise 99.6 wt% of polymethyl ethylene carbonate and 0.4 wt% of an opening agent; the outer layer is made of kraft paper.

The grammage of the kraft paper is 26g, and the content of the needle pulp is 98%; the molar content of a terephthalic acid chain segment in the PBAT structure is 40%, the weight average molecular weight is 12 ten thousand, and the melt index of the PBAT is 3.5g/10 min; the hydrolysis resisting agent is bis (2, 6-diisopropylphenyl) carbodiimide; the opening agent is a mixture of erucamide and fumed silica, and the weight ratio is 1: 1; the weight average molecular mass of the polymethyl ethylene carbonate is 15 ten thousand, and the melt index of the polymethyl ethylene carbonate is 2.5g/10 min.

Example 4: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.2 wt% of PBAT, 0.4 wt% of hydrolysis resistant agent and 0.4 wt% of opening agent; the preparation raw materials of the middle layer comprise 99.6 wt% of polymethyl ethylene carbonate and 0.4 wt% of an opening agent; the outer layer is made of kraft paper.

The Kraft paper has a grammage of 26g and is made of needle-leaved pulpThe content is 98 percent; the molar content of a terephthalic acid chain segment in the PBAT structure is 40%, the weight average molecular weight is 12 ten thousand, and the melt index of the PBAT is 3.5g/10 min; the hydrolysis-resistant agent is polymerized carbodiimide (A)

2) (ii) a The opening agent is a mixture of erucamide and fumed silica, and the weight ratio is 1: 1; the weight average molecular mass of the polymethyl ethylene carbonate is 15 ten thousand, and the melt index of the polymethyl ethylene carbonate is 2.5g/10 min.

(1) placing a kraft paper coiled material with the width of 1.2m on a machine station placing frame, drawing the kraft paper coiled material to a casting die head of a film coating machine through a traction wheel, and heating a traction roller, the casting die head and a screw rod by a starter station heating device; the specific temperature parameters were the same as in example 1:

Example 5: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.2 wt% of PBAT, 0.4 wt% of hydrolysis resistant agent and 0.4 wt% of opening agent; the preparation raw materials of the middle layer comprise 99.6 wt% of polymethyl ethylene carbonate and 0.4 wt% of an opening agent; the outer layer is made of kraft paper.

P200 liquid, about 7% carbodiimide content), in a weight ratio of 2.6: 1; the opening agent is a mixture of erucamide and fumed silica, and the weight ratio is 1: 1; the weight average molecular mass of the polymethyl ethylene carbonate is 15 ten thousand, and the melt index of the polymethyl ethylene carbonate is 2.5g/10 min.

Example 6: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.2 wt% of PBAT, 0.4 wt% of hydrolysis resistant agent and 0.4 wt% of opening agent; the preparation raw materials of the middle layer comprise 99.6 wt% of polymethyl ethylene carbonate and 0.4 wt% of an opening agent; the outer layer is made of kraft paper.

The grammage of the kraft paper is 41g, and the content of the needle pulp is 90%; the molar content of a terephthalic acid chain segment in the PBAT structure is 40%, the weight average molecular weight is 12 ten thousand, and the melt index of the PBAT is 3.5g/10 min; the hydrolysis resisting agent consists of bis (2, 6-diisopropylphenyl) carbodiimide and polymerized carbodiimide

The weight ratio of the components is 2.6: 1; the opening agent is a mixture of erucamide and fumed silica, and the weight ratio is 1: 1; the weight average molecular mass of the polymethyl ethylene carbonate is 15 ten thousand, and the melt index of the polymethyl ethylene carbonate is 2.5g/10 min.

Example 7: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.2 wt% of PBAT, 0.4 wt% of hydrolysis resistant agent and 0.4 wt% of opening agent; the preparation raw material of the middle layer is polymethyl ethylene carbonate; the outer layer is made of kraft paper.

The grammage of the kraft paper is 26g, and the content of the needle pulp is 98%; the molar content of a terephthalic acid chain segment in the PBAT structure is 40%, the weight average molecular weight is 12 ten thousand, and the melt index of the PBAT is 3.5g/10 min; the hydrolysis resisting agent consists of bis (2, 6-diisopropylphenyl) carbodiimide and polymerized carbodiimide

Example 8: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.2 wt% of PBAT, 0.4 wt% of hydrolysis resistant agent and 0.4 wt% of opening agent; the preparation raw materials of the middle layer comprise 99.6 wt% of polymethyl ethylene carbonate and 0.4 wt% of an opening agent; the outer layer is made of kraft paper.

The weight ratio of the components is 2.6: 1; the opening agent is erucamide; the weight average molecular mass of the polymethyl ethylene carbonate is 15 ten thousand, and the melt index of the polymethyl ethylene carbonate is 2.5g/10 min.

Example 9: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.2 wt% of PBAT, 0.4 wt% of hydrolysis resistant agent and 0.4 wt% of opening agent; the preparation raw materials of the middle layer comprise 99.6 wt% of polymethyl ethylene carbonate and 0.4 wt% of an opening agent; the outer layer is made of kraft paper.

2) The weight ratio of the components is 2.6: 1; the opening agent is fumed silica; the weight average molecular mass of the polymethyl ethylene carbonate is 15 ten thousand, and the melt index of the polymethyl ethylene carbonate is 2.5g/10 min.

Example 10: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.2 wt% of PBAT, 0.4 wt% of hydrolysis resistant agent and 0.4 wt% of opening agent; the preparation raw materials of the middle layer comprise 99.6 wt% of polymethyl ethylene carbonate and 0.4 wt% of an opening agent; the outer layer is made of kraft paper.

The Kraft paper has a grammage of 26g, the content of needle leaf pulp is 98%; the molar content of a terephthalic acid chain segment in the PBAT structure is 20%, the weight average molecular weight is 10 ten thousand, and the melt index of the PBAT is 4.8g/10 min; the hydrolysis resisting agent consists of bis (2, 6-diisopropylphenyl) carbodiimide and polymerized carbodiimide

Example 11: the embodiment provides a degradable kraft paper buffer air cushion film with good barrier property, which comprises an outer layer, a middle layer and an inner layer, wherein the thicknesses of the outer layer, the middle layer and the inner layer are respectively 30 micrometers, 10 micrometers and 10 micrometers; the preparation raw materials of the inner layer comprise 99.2 wt% of PBAT, 0.4 wt% of hydrolysis resistant agent and 0.4 wt% of opening agent; the preparation raw materials of the middle layer comprise 99.6 wt% of polymethyl ethylene carbonate and 0.4 wt% of an opening agent; the outer layer is made of kraft paper.

The weight ratio of the components is 2.6: 1; the opening agent is a mixture of erucamide and fumed silica, and the weight ratio is 1: 1; the weight average molecular mass of the polymethyl ethylene carbonate is 24 ten thousand, and the melt index of the polymethyl ethylene carbonate is 1.0g/10 min.

Performance testing

The applicant carried out a series of performance tests on the samples in the above examples, and the specific test contents and specific test methods were as follows:

mechanical Property test: the tensile strength (MPa) is obtained by testing according to the national standard GB/T1040.3-2006, and the test results are shown in Table 2.

Barrier properties: the permeability of the film to oxygen is carried out according to the national standard GB/T1038-³/(m².d.atm0)]The test results are shown in table 2.

Heat sealability: the finished product is tested by the quick heat sealing of an air cushion machine, and the heat sealing air leakage rate (%) of each hundred air pillows is observed, wherein the specific test conditions are as follows: the bag-making specification was 200 × 100mm, the inflator air volume was 28L/min, the heat-seal temperature was 180 ℃, the speed was 15m/min, and the number of heat-seals was 100, and the test results are shown in Table 2.

Average thickness deviation: the film samples of the examples were subjected to thickness measurement using a surface profiler, each sample was measured at least 80 positions, the test points were evenly distributed at the middle and edge positions of the film, and the thickness deviation was calculated, the results of which are shown in table 2 below.

Table 2 results of performance testing

	Air leakage rate of heat sealing	Barrier properties	Tensile strength	Deviation in thickness%
					Example 1	0％	19[cm³/(m².d.atm0)]	46	2％
Example 2	15％	49[cm³/(m².d.atm0)]	34	9％
					Example 3	7％	35[cm³/(m².d.atm0)]	39	5％
Example 4	5％	34[cm³/(m².d.atm0)]	43	6％
					Example 5	2％	23[cm³/(m².d.atm0)]	41	3％
Example 6	13％	29[cm³/(m².d.atm0)]	47	--
					Example 7	6％	32[cm³/(m².d.atm0)]	37	--
Example 8	3％	68[cm³/(m².d.atm0)]	32	--
					Example 9	7％	26[cm³/(m².d.atm0)]	47	--
Example 10	0％	30[cm³/(m².d.atm0)]	43	10％
					Example 11	0％	34[cm³/(m².d.atm0)]	40	14％

Water resistance: the finished product is quickly heat-sealed by an air cushion machine, then is put into water and stands for 30min, the water tank is vacuumized to observe the air leakage condition of the air pillow, the vacuum degree is-30 kpa, and the specific test conditions are as follows: the bag making specification is 200 x 100mm, the inflator air volume is 28L/min, the heat sealing temperature is 180 ℃, the speed is 15m/min, the heat sealing quantity is 50, the bag is kept still in water at 40 or 25 ℃ for 30min, the vacuum degree is-30 kpa, the vacuum air leakage rate (%) is detected, and the test result is shown in table 3.

Sensory testing: the buffer air cushion film is divided into 1-3 grades according to the light, thin, smooth and soft degree of the surface, wherein the 1 grade has the best hand feeling, the 3 grade has the worst degree, and the result is shown in the following table 3:

table 3 results of performance testing

Through the experimental results, the kraft paper buffer air cushion film provided by the invention has excellent degradability, and the problem of environmental pollution caused by the traditional plastic film is completely avoided. In addition, the mechanical strength, the barrier property and the heat sealing property of the buffer air cushion film are effectively improved by the targeted regulation and control of the components, the proportion, the physical and chemical properties and the like of the three layers of raw materials inside and outside the film. In addition, the water resistance and hand feeling of the film at different temperatures are effectively improved by adjusting the physical and chemical properties of kraft paper used in the film, the components and the proportion of hydrolysis resistant agents and the like.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in other forms, and any person skilled in the art may modify or change the technical content disclosed above into an equivalent embodiment with equivalent changes, but all those simple modifications, equivalent changes and modifications made on the above embodiment according to the technical spirit of the present invention still belong to the protection scope of the present invention.

Claims

1. A degradable kraft paper buffer air cushion film with good barrier property is characterized by comprising an outer layer, a middle layer and an inner layer; the preparation raw material of the inner layer comprises PBAT; the preparation raw material of the middle layer comprises polymethyl ethylene carbonate; the outer layer is made of kraft paper, and the content of needle pulp in the kraft paper is not lower than 95 wt%.

2. The degradable kraft paper buffer air cushion film with good barrier property according to claim 1, wherein the molar content of the terephthalic acid segment in the PBAT structure is 30-45%.

3. The degradable kraft paper buffer air cushion film with good barrier property according to claim 2, wherein the weight average molecular weight of the PBAT is 10-15 ten thousand.

4. The degradable kraft paper buffer air cushion film with good barrier property according to claim 2, wherein the PBAT has a melt index of 1-10g/10min at 190 ℃/2.16 kg.

5. The degradable kraft paper buffering air cushion film with good barrier property according to claim 1, wherein the preparation raw materials of the inner layer further comprise a hydrolysis-resistant agent and an opening agent; the content of the hydrolysis resistant agent and the content of the opening agent are respectively 0.3-0.5 wt% and 0.4-0.6 wt%.

6. The degradable kraft paper buffer air cushion film with good barrier property according to claim 1, wherein the weight average molecular mass of the polymethyl ethylene carbonate is 15-20 ten thousand; preferably, the melt index of the polymethyl ethylene carbonate is 1-8 g/10min under the condition of 190 ℃/2.16 kg.

7. The degradable kraft paper buffer air cushion film with good barrier property according to claim 6, wherein the preparation raw material of the middle layer further comprises a mouth-opening agent; the content of the polymethyl ethylene carbonate at least accounts for 99 wt% of the total mass of the intermediate layer preparation raw materials.

8. The degradable kraft paper buffer air cushion film with good barrier property according to claim 1, wherein the grammage of kraft paper should not exceed 30 g.

9. The preparation method of the degradable kraft paper buffer air cushion film with good barrier property according to any one of claims 1 to 8, characterized by comprising the following steps:

10. The preparation method of the degradable kraft paper buffer air cushion film with good barrier property according to claim 9, wherein in the step (3), the kraft paper is preheated before being sprayed by a first film spraying machine, and the preheating temperature is 60-100 ℃; the temperature range of the cooling pinch roller is 5-10 ℃, and the cooling pinch roller is made of tungsten steel.