WO2016090806A1

WO2016090806A1 - Degradable pp-evoh high resistance composite thin-film

Info

Publication number: WO2016090806A1
Application number: PCT/CN2015/076819
Authority: WO
Inventors: 高学文; 夏嘉良; 俞晓琴; 夏瑜; 唐敏艳
Original assignee: 嘉合实业(苏州)有限公司
Priority date: 2014-12-11
Filing date: 2015-04-16
Publication date: 2016-06-16
Also published as: AU2015361915A1; CN104369508A; CN104369508B; AU2015361915B2

Abstract

A degradable PP-EVOH high resistance composite thin-film; each layer of the material in the composite thin-film obtains substantially same biodegradability through the introduction of a biological base; the added amount of an additive masterbatch in each layer of the material is controlled to be in the range of 0.3-15 % of the total mass of the layer of the material; the hydrophilic activity of a hydrophilic group in the additive masterbatch should be greater than or equal to the hydrophilic activity of a hydrophilic group in each layer of the material; by adding the additive masterbatch, the molar ratio of the hydrophilic groups to the carbon atoms in each layer of the material is substantially the same; that is, the biological activity is substantially the same, such that the degradation rate of each layer of the material is substantially the same, while the appearance, function and physical and mechanical properties of the product remain unchanged.

Description

Degradable PP-EVOH high barrier composite film

Technical field

The invention relates to the technical field of multilayer composite films, in particular to a biodegradable PP-EVOH high barrier composite film.

Background technique

The multi-layer co-extruded composite film refers to a film which is compounded by a plurality of different polymers by a co-extrusion blow molding method, a co-extrusion casting method or a co-extrusion stretching method. This kind of film is widely used as a plastic packaging material in food, processed meat products, daily necessities, cosmetics, chemical products, pesticides, military products, etc., and can realize the sealing and soft packaging of products and meet various kinds of inflation or vacuuming, thermoforming, etc. The packaging function has various barrier properties such as high moisture resistance, oxygen barrier, oil resistance and fragrance retention under various environments.

With the use of a large number of composite films in various fields, the environmental pollution of composite films is increasing. Because of its difficulty in degradation, as the amount of use increases, the pollution caused by the composite film has become a worldwide public hazard. At present, some traditional methods for processing composite film waste, such as incineration, burial, recycling, etc., have defects and have certain limitations to bring serious load to the environment. Therefore, the development of biodegradable composite film that reduces environmental pollution is the solution to the environment. An important way of pollution.

According to the applicant's understanding, the biodegradation technology and application technology of composite films with the same degradation rate are still blank, and no relevant reports have been reported at home and abroad. However, from the current situation of rapid increase in market demand and the protection of ecological balance, it is urgent to study the biodegradable multilayer co-extruded composite film. How to make the various layers of the multi-layer co-extruded composite film in the biodegradation process The degradation rate in the gradual consistency, without losing the original mechanical properties and shelf life, is an important research topic of practical significance.

Summary of the invention

The object of the present invention is to provide a degradable PP-EVOH high barrier composite film which tends to have a uniform biodegradation rate.

In order to achieve the above object, the first technical solution adopted by the present invention is: a degradable PP-EVOH high barrier complex With a film, the structure of the composite film is as follows:

PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE type (1)

In the formula (1), the meanings from the left to the right are:

PP means an outer layer, the function of which is a protective layer or a display layer, the material of which is polypropylene, and the polypropylene does not contain a hydrophilic group;

PP-TIE denotes a first adhesive layer, the material of which is a maleic anhydride grafted polypropylene copolymer, and the maleic anhydride grafted polypropylene copolymer contains a hydrophilic group which is an acid anhydride;

PA/EVOH/PA denotes a middle layer formed by a combination of three layers, the function of which is a barrier layer, the material of which is PA represents polyamide, the hydrophilic group of polyamide contains amide group, and EVOH represents ethylene-vinyl alcohol copolymer. The hydrophilic group contained in the ethylene-vinyl alcohol copolymer is a hydroxyl group;

PE-TIE denotes a second adhesive layer whose material is a maleic anhydride grafted polyethylene copolymer, and the maleic anhydride grafted polyethylene copolymer contains a hydrophilic group which is an acid anhydride;

PE denotes an inner layer, the function of which is a heat seal layer, the material of which is polyethylene, and the polyethylene does not contain a hydrophilic group;

The innovation is that each layer of the composite film obtains a uniform biodegradability by introducing a bio-based group, which is a kind of additive type biodegradable activity in a garbage disposal field or composting condition. The additive masterbatch is uniformly added to each layer of the material in proportion, and then the composite film is prepared by a melt coextrusion method;

The additive type masterbatch is composed of a carrier and an active agent, and the active agent is a polymer containing a hydrophilic group, wherein the active component of the active agent is a hydrophilic group, and the hydrophilic group means a carboxylic acid. At least one of a salt, a carboxyl group, a hydroxyl group, an aldehyde group, an amide group, an acid anhydride, and an ester group;

In the material of each layer of the formula (1) and the additive type masterbatch, the hydrophilic group is a carboxylate, a carboxyl group, a hydroxyl group, an aldehyde group, an amide group, an acid anhydride, an ester group in order of the hydrophilic activity from high to low;

The carrier is selected for each layer of material according to a similar compatibility principle:

For the outer layer of the polypropylene material, the carrier in the additive type master batch is at least one of polypropylene and polyethylene;

For the maleic anhydride grafted polypropylene copolymer material of the first adhesive layer, the carrier in the additive type master batch is polypropylene, poly At least one of ethylene;

For the middle layer of the polyamide material, the carrier in the added masterbatch is a polyamide;

For the intermediate layer of ethylene-vinyl alcohol copolymer material, the carrier in the additive type masterbatch is polyethylene;

For the maleic anhydride grafted polyethylene copolymer material of the second adhesive layer, the carrier in the additive type master batch is polyethylene;

For the inner layer of polyethylene material, the carrier in the added masterbatch is polyethylene;

The added amount of the added masterbatch in each layer of material is controlled within a range of 0.3-15% of the total mass of the layer of the material; the hydrophilic activity of the hydrophilic group in the added masterbatch should be greater than or equal to the formula (1) The hydrophilic activity of the hydrophilic group in each layer of material; by adding the additive type masterbatch, the molar ratio of the hydrophilic group to the carbon atom of each layer of the material in the formula (1) tends to be uniform, that is, the biological activity tends to Consistently, the degradation rate of each layer of the composite film tends to be uniform.

In order to achieve the above object, the second technical solution adopted by the present invention is: a degradable PP-EVOH high barrier composite film, and the structure of the composite film is as follows:

PP/PP-TIE/EVOH/PE-TIE/PE type (2)

In equation (2), the meanings from left to right are:

EVOH denotes a middle layer, the function of which is a barrier layer, the material of which is an ethylene-vinyl alcohol copolymer, and the hydrophilic group contained in the ethylene-vinyl alcohol copolymer is a hydroxyl group;

The innovation is that each layer of the composite film obtains a uniform biodegradability by introducing a bio-based group, which is a type of additive type biodegradable in a garbage disposal field or composting condition. Material, the added type The masterbatch is uniformly added to each layer of the material in proportion, and then the composite film is prepared by a melt coextrusion method;

In the material of each layer of the formula (2) and the additive type masterbatch, the hydrophilic group is a carboxylate, a carboxyl group, a hydroxyl group, an aldehyde group, an amide group, an acid anhydride, an ester group in order of the hydrophilic activity from high to low;

For the maleic anhydride grafted polypropylene copolymer material of the first adhesive layer, the carrier in the additive type master batch is at least one of polypropylene and polyethylene;

The added amount of the added masterbatch in each layer of material is controlled within a range of 0.3-15% of the total mass of the layer of the material; the hydrophilic activity of the hydrophilic group in the added masterbatch should be greater than or equal to the formula (2) The hydrophilic activity of the hydrophilic group in each layer of material; by adding the additive type masterbatch, the molar ratio of the hydrophilic group to the carbon atom of each layer of the material in the formula (2) tends to be uniform, that is, the biological activity tends to Consistently, the degradation rate of each layer of the composite film tends to be uniform.

The relevant content in the above technical solutions is explained as follows:

1. In the above embodiment, in the outer layer, the polypropylene is composed of an isotactic polypropylene homopolymer or/and a polypropylene random copolymer, and the polypropylene has a density of 0.880 to 0.910 g/cm ³ .

2. In the above solution, the maleic anhydride grafted polypropylene copolymer has a density of 0.880-0.910 g/cm ³ in the first adhesive layer, wherein the maleic anhydride graft ratio has a mass percentage of 0.3. %-10%.

3. In the above solution, the density of the ethylene-vinyl alcohol copolymer is 1.170-1.19 g/cm ³ in the barrier layer, and the ethylene molar content of the ethylene-vinyl alcohol copolymer is 26-48%; the density of the polyamide is 1.12-1.14 g/cm ³ , the polyamide is a PA6 homopolymer or a PA6, 66 copolymer or an amorphous polyamide.

4. In the above embodiment, the density of the ethylene-vinyl alcohol copolymer in the barrier layer is 1.170-1.19 g/cm ³ , and the ethylene molar content of the ethylene-vinyl alcohol copolymer is 26-48%.

5. In the above embodiment, the density of the maleic anhydride grafted polyethylene copolymer in the second adhesive layer is from 0.910 to 0.950 g/cm ³ , wherein the mass percentage of the maleic anhydride graft ratio is 0.3%-10%.

6. In the above solution, in the heat seal layer, the density of the polyethylene is 0.900-0.935 g/cm ³ , and the polyethylene comprises a polyethylene blend, and the density of the polyethylene blend is 0.910-0.925 g/ Cm ³ , the polyethylene blend consists of 50-99% by weight of polyethylene and 1-50% by weight of a vinyl homopolymer, or the polyethylene blend consists of 50-99% by weight of polyethylene And a composition of 1 to 50% by weight of a vinyl copolymer composed of at least one of ethylene and a C4-C12 alpha-olefin, a cycloolefin, a vinyl arene, and a polar vinyl monomer. The vinyl copolymer has a density of from 0.880 to 0.915 g/cm ³ .

7. In the above solution, the function of the outer layer is a protective layer or a display layer, wherein when the function is a protective layer, the function is wear resistance and temperature resistance; when the function is a display layer, it can be used Print the display of relevant information, or transparently display the contents of the package.

8. In the above solution, the composite film can obtain corresponding additional functions through coating, metal evaporation, and compounding.

The technical principle of the present invention is that the materials constituting the composite film are classified into two types: a hydrophilic material and a hydrophobic material, wherein the hydrophilic material itself contains a hydrophilic group, and has biodegradability under the garbage disposal site or composting condition; The hydrophobic material does not contain a hydrophilic group. By adding a hydrophilic group to the hydrophobic material to impart biodegradability, the added masterbatch is added to each layer of the material in proportion, and the carrier and the active agent are fully compatible by blending. Then, the composite film is prepared by the melt co-extrusion method, and under the action of high temperature and high shear, the macromolecular chains are stably combined by hydrogen bonding and mutual bending between the macromolecular chains to form a stable Macromolecular aggregates to add and uniformly disperse hydrophilic groups in the active agent to each layer of material; in a biodegradable environment, the degradable active agent is first decomposed by microorganisms The molecular chain is broken, and the carrier linked to the hydrogen bond also undergoes molecular chain cleavage, thereby causing the macromolecular aggregate to decompose, thereby achieving the purpose of biodegradation of the plastic composite film.

The biodegradation process of the present invention begins with a characteristic expansion, and the bioactive compound in the plastic makes the carbon-containing polymer more susceptible to attack by microbial bacteria. When the microbial bacteria engulf the biologically active compound, an acidic substance is generated, thereby causing inclusion. The carbon polymer matrix expands. When the expansion contacts the heat and moisture, and the molecular structure of the carbon-containing polymer is expanded, and the expansion creates space in the molecular structure of the polymer, the combination of the biologically active compound and the masterbatch attracts microorganisms that can metabolize and neutralize the polymer. group. These microbial communities secrete acid to further shear the long chains of the polymer until the polymer is broken down into inert humus, carbon dioxide and methane. This biodegradation process can be carried out in an aerobic environment or under anaerobic conditions; it can be carried out under conditions of light, heat and humidity, or in the absence of light, heat and humidity. The key point of the technical solution of the present invention is that the hydrophilic activity of the hydrophilic group in the additive type masterbatch should be greater than or equal to the hydrophilic activity of the hydrophilic group in each layer of the composite film; by adding the added masterbatch, The molar ratio of the hydrophilic group to the carbon atom of each layer of the composite film tends to be the same, that is, the biological activity tends to be uniform, so that the degradation rate of each layer of the composite film tends to be uniform. When a bio-based group is added, an additive type masterbatch having a hydrophilic activity greater than that of the composite film material is added to each layer of the composite film to weaken the original hydrophilic activity in the composite film material, and by adding the additive type master batch, The molar ratio of the hydrophilic groups to the carbon atoms of the materials in the composite film tends to be uniform, that is, the biological activity tends to be uniform, so that the degradation rate of each layer of the composite film tends to be uniform.

The contribution of the present invention is that by balancing the molar ratio of hydrophilic groups to carbon atoms in the materials of the layers and the hydrophilic activity, the biological activities of the materials in the composite film structure tend to be uniform, thereby degrading the materials of the layers of the composite film. The rate tends to be uniform; when the addition amount is 0.3-15% of the total mass of the layer material, the appearance, function and physical and mechanical properties of the film remain unchanged before being processed by the compost.

detailed description

The present invention is further described below in conjunction with the embodiments:

Embodiment 1: (Example of the first technical solution)

A degradable PP-EVOH high barrier composite film, the structure of the composite film is as follows:

PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE type (1)

In the formula (1), the meanings from the left to the right are:

PP denotes an outer layer, the function of which is a protective layer or a display layer, the material of which is polypropylene, the monomer formula is -[CH ₂ -CH(CH ₃ )] _n -, and the polypropylene does not contain a hydrophilic group;

PP-TIE denotes a first adhesive layer which is a maleic anhydride grafted polypropylene copolymer formed by mixing 95% by weight of polypropylene and 5% by weight of maleic anhydride, and its monomer formula is -[CH ₂ -CH(CH ₃ )] _n -[C ₄ H ₂ O ₃ ] _m , the hydrophilic group of the maleic anhydride grafted polypropylene copolymer is anhydride-OC-O-CO-;

PA/EVOH/PA denotes a middle layer formed by a combination of three-layer structure, the function of which is a barrier layer, the material of which is PA6 represents polyamide 6, and its monomer formula is -[NH-(CH ₂ ) ₅ -CO] _n -, The hydrophilic group contained in the polyamide is an amide group -CONH ₂ -, EVOH represents an ethylene-vinyl alcohol copolymer, and the ethylene-vinyl alcohol copolymer is 32% by weight of ethylene PE and 68% by weight of vinyl alcohol PVA. The molecular formula is [CH ₂ CH ₂ ] ₁ [CH ₂ CHOH] _1.4 , and the hydrophilic group contained in the ethylene-vinyl alcohol copolymer is hydroxyl-OH;

PE-TIE denotes a second adhesive layer which is a maleic anhydride grafted polyethylene copolymer formed by mixing 95% by weight of polyethylene and 5% by weight of maleic anhydride, and its monomer formula is -[CH ₂ -CH ₂ ] _n -[C ₄ H ₂ O ₃ ] _m , the hydrophilic group of the maleic anhydride grafted polyethylene copolymer is anhydride-OC-O-CO-;

PE denotes an inner layer which functions as a heat seal layer and whose material is polyethylene, and its monomer formula is -[CH ₂ -CH ₂ ] _n -, and the polyethylene does not contain a hydrophilic group.

In the outer layer, the polypropylene is composed of an isotactic polypropylene homopolymer or/and a polypropylene random copolymer, and the density of the polypropylene is 0.910 g/cm ³ , and in practical use, the density is 0.880 g. The same effect can also be achieved with values of /cm ³ , 0.905 g/cm ³ or other values between 0.880 and 0.910 g/cm ³ .

In the first adhesive layer, the density of the maleic anhydride grafted polypropylene copolymer is 0.910 g/cm ³ , and in practical use, the density is 0.880 g/cm ³ , 0.905 g/cm ³ or the like. The same effect can be achieved by a value between 0.880 and 0.910 g/cm ³ , wherein the maleic anhydride graft ratio is 5% by weight, and in practice, 0.3% by weight, 8% by weight, 10% by weight or other A value between 0.3 and 10% by weight can also achieve the same effect.

The barrier layer, an ethylene - vinyl alcohol copolymer has a density of 1.170g / cm ^3, the actual application, if we take a density of ^{1.190g / cm 3, 1.18g / cm} 3 or other between 1.170-1.190g / cm The value between the ^three can also achieve the same effect. The ethylene-vinyl alcohol copolymer has an ethylene molar content of 32%. In practical applications, if the ethylene molar content is 26%, 30%, 48% or other between 26-48 The value between % can also achieve the same effect; the density of polyamide PA6 is 1.13g/cm ³ . In practical application, if the density of polyamide is 1.226g/cm ³ , 1.14g/cm ³ or other The same effect can be achieved by a value between 1.12-1.14 g/cm ³ , which is a PA6 homopolymer or a PA6,66 copolymer or an amorphous polyamide.

In the second adhesive layer, the density of the maleic anhydride grafted polyethylene copolymer is 0.910 g/cm ³ , and in practical use, if the density is 0.950 g/cm ³ , 0.930 g/cm ³ or Other values between 0.910 and 0.950 g/cm ³ can also achieve the same effect. The maleic anhydride graft ratio is 5% by weight. In practical applications, 0.3% by weight, 8% by weight, 10% by weight or Other values between 0.3 and 10% by weight can also achieve the same effect.

The heat seal layer, the polyethylene having a density of 0.900-0.935g / cm ^3, a polyethylene blend containing polyethylene, the density of the polyethylene blend of 0.910-0.925g / cm ^3, the poly The ethylene blend consists of 50-99% by weight of polyethylene and 1-50% by weight of a vinyl homopolymer, or the polyethylene blend consists of 50-99% by weight of polyethylene and 1-50% by weight. Composition of a vinyl copolymer composed of at least one of ethylene and a C4-C12 alpha-olefin, a cycloolefin, a vinyl arene, and a polar vinyl monomer, the vinyl copolymer The density is from 0.880 to 0.915 g/cm ³ .

The function of the outer layer is a protective layer or a display layer, wherein when it functions as a protective layer, it has the functions of abrasion resistance and temperature resistance; when its function is a display layer, it can be used for printing display related information or transparent display Package contents.

The composite film can obtain corresponding additional functions through coating, metal evaporation, and compounding.

Each layer of the composite film obtains a uniform biodegradability by introducing a bio-based group, which is a type of additive masterbatch having biodegradability in a garbage disposal site or composting condition, the addition Masterbatch The composite film was prepared by uniformly adding to each layer of the material in proportion and then by a melt coextrusion method.

The additive type masterbatch is composed of a carrier and an active agent, and the active agent is a polymer containing a hydrophilic group, wherein the active component of the active agent is a hydrophilic group, and the hydrophilic group means a carboxylic acid. salt -COO ^-, at least one carboxy group -COOH, a hydroxyl group -OH, an aldehyde group -CHO, amide groups -CONH _2, -OC-O-CO- acid anhydride and the ester group -COOR.

The formula (1) layers of material and the additive in the masterbatch, hydrophilic group according to the order of highest to lowest hydrophilic active carboxylate -COO ^-, a carboxyl group -COOH, a hydroxyl group -OH, -CHO aldehyde , amide group - CONH ₂ , anhydride - OC-O-CO -, ester group - COOR.

For the inner layer of polyethylene material, the carrier in the additive masterbatch is polyethylene.

According to the composite film structure of the first embodiment, the hydrophilic activity of the hydrophilic groups contained in the various materials is ranked from high to low to hydroxyl>amide>anhydride, that is, the hydrophilic activity of each layer of the material in the formula (1) is high. To low order ethylene-vinyl alcohol copolymer EVOH (32% PE + 68% PVA) > polyamide PA6 > PP-TIE (95% PP + 5% maleic anhydride) > PE-TIE (95% PE + 5% Maleic anhydride) > Polyethylene PE = Polypropylene PP.

The sodium alginate having a hydrophilic activity greater than the hydrophilic activity of EVOH (hydroxyl) in the composite film material is selected as an additive active agent to weaken the hydrophilic activity of the original hydrophilic group in the composite film material.

1. It is known that the monomeric formula of sodium alginate is (C ₅ H ₇ O ₄ COONa) _n . From the molecular formula, the hydrophilic group contained in sodium alginate is sodium carboxylate (—COONa) and hydroxyl group. (—OH) and ester group (—COOR), wherein the hydrophilic activity of sodium carboxylate (—COONa) is greater than the hydrophilic activity of hydroxyl group (—OH), and the hydrophilic activity of hydroxyl group (—OH) in sodium alginate is equal to The hydrophilic activity of the hydroxyl group (—OH) in the ethylene-vinyl alcohol copolymer EVOH, so the polymer sodium alginate was selected as the active agent in the present embodiment.

2. Since the hydrophilic activity of sodium carboxylate in sodium alginate is greater than the hydrophilic activity of hydroxyl groups in the ethylene-vinyl alcohol copolymer having the highest hydrophilic activity in the composite film material, it plays a leading role in the biodegradation process, and the composite film The role of the hydrophilicity of the hydroxy group in the EVOH, the amide group in the PA, the PP-TIE and the PE-TIE in the material was weakened. To simplify the formulation, EVOH, PA, PP-TIE and PE-TIE were assumed in the following calculations. The hydrophilic group to carbon atom molar ratio is zero.

3. Calculated: The molar ratio of hydrophilic group to carbon atom of sodium alginate is 2/3.

4. The molar ratio of hydrophilic groups to carbon atoms of EVOH, PA6, PP-TIE, PE-TIE, PE, PP is 0.

5. Since the addition amount of the additive type master batch is small, and the carrier in the added type master batch is the same as or similar to the added polymer, in order to simplify the expression, the quality of the carrier in the added type master batch is ignored in the following calculation.

The following is to calculate the mass percentage of sodium alginate added in each layer of material according to the addition amount of 1% and 2.2% molar amount of sodium alginate:

A. 1% molar amount of sodium alginate added

The material of each layer in formula (1) is mixed with sodium alginate in a molar ratio of 99:1, and the molar ratio of hydrophilic group to carbon atom after adding sodium alginate in each layer material is calculated:

99/100* polypropylene _{(n hydrophilic group: n carbon atom)} +1/100* sodium alginate _{(n hydrophilic group: n carbon atom)} =99/100*0+1/100*2/3 =0.0067;

99/100* maleic anhydride grafted polypropylene copolymer _{(n hydrophilic group: n carbon atom)} +1/100* sodium alginate _{(n hydrophilic group: n carbon atom)} = 99/100*0+ 1/100*2/3=0.0067;

99/100* polyamide 6 _{(n hydrophilic group: n carbon atom)} +1/100* sodium alginate _{(n hydrophilic group: n carbon atom)} =99/100*0+1/100*2/ 3=0.0067;

99/100* ethylene-vinyl alcohol copolymer _{(n hydrophilic group: n carbon atom)} + 1/100* sodium alginate _{(n hydrophilic group: n carbon atom)} = 99/100*0+1/100 *2/3=0.0067;

99/100* maleic anhydride grafted polyethylene copolymer _{(n hydrophilic group: n carbon atom)} +1/100* sodium alginate _{(n hydrophilic group: n carbon atom)} = 99/100*0+ 1/100*2/3=0.0067;

99/100* polyethylene _{(n hydrophilic group: n carbon atom)} +1/100* sodium alginate _{(n hydrophilic group: n carbon atom)} =99/100*0+1/100*2/3 =0.0067.

It is calculated from the above that in the PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE structure, the materials of each layer are mixed with sodium alginate in a molar ratio of 99:1, and the mixed pro is calculated. The molar ratio of water groups to carbon atoms is the same, that is, the hydrophilic activities of the materials of the layers tend to be uniform, and the degradation rates tend to be uniform. The mass of sodium alginate added in each layer of material is calculated as follows:

It is assumed that the PP after adding sodium alginate is 1 mol, the mass of PP is m _1-1 , and the mass of sodium alginate is m _2-1 ;

m _1-1 = molecular weight of PP (g/mol) * PP content (%) * molar amount (mol)

=41.07*99%*1=40.66 g;

m _2-1 = molecular weight of sodium alginate (g/mol) * sodium alginate content (%) * molar amount (mol)

=198.12*1%*1=1.98 g;

It is assumed that the PP-TIE after adding sodium alginate is 1 mol, the mass of PP-TIE is m _1-2 , and the mass of sodium alginate is m _2-2 ;

m _1-2 = molecular weight of PP-TIE (g/mol) * PP-TIE content (%) * molar amount (mol)

=45.56*99%*1=45.10 g;

m _2-2 = molecular weight of sodium alginate (g/mol) * sodium alginate content (%) * molar amount (mol)

=198.12*1%*1=1.98 g;

It is assumed that the PA6 after adding sodium alginate is 1 mol, the mass of PA6 is m _1-3 , and the mass of sodium alginate is m _2-3 ;

m _1-3 = molecular weight of PA6 (g/mol) * PA6 content (%) * molar amount (mol)

=113.16*99%*1=112.03 g;

m _2-3 = molecular weight of sodium alginate (g / mol) * sodium alginate content (%) * molar amount (mol)

=198.12*1%*1=1.98 g;

It is assumed that the EVOH after adding sodium alginate is 1 mol, the mass of EVOH is m _1-4 , and the mass of sodium alginate is m _2-4 ;

m _1-4 = molecular weight of EVOH (g/mol) * EVOH content (%) * molar amount (mol)

=89.73*99%*1=88.83 grams;

m _2-4 = molecular weight of sodium alginate (g/mol) * sodium alginate content (%) * molar amount (mol)

=198.12*1%*1=1.98 g;

It is assumed that the PE-TIE after adding sodium alginate is 1 mol, the mass of PE-TIE is m _1-5 , and the mass of sodium alginate is m _2-5 ;

m _1-5 = molecular weight of PE-TIE (g/mol) * PE-TIE content (%) * molar amount (mol)

=32.67*99%*1=32.34 grams;

m _2-5 = molecular weight of sodium alginate (g/mol) * sodium alginate content (%) * molar amount (mol)

=198.12*1%*1=1.98 g;

It is assumed that the amount of PE after adding sodium alginate is 1 mol, the mass of PE is m _1-6 , and the mass of sodium alginate is m _2-6 ;

m _1-6 = molecular weight of PE (g/mol) * PE content (%) * molar amount (mol)

=28.05*99%*1=27.77 grams;

m _2-6 = molecular weight of sodium alginate (g/mol) * sodium alginate content (%) * molar amount (mol)

=198.12*1%*1=1.98 g;

For example, in the outer layer PP, the mass of sodium alginate added is a percentage of the mass of PP. It is: 1.98/(40.66+1.98)*100%=4.64%; the calculation of the mass percentage of sodium alginate added in the remaining layers of materials is similar;

The percentage by mass of sodium alginate added from PP to PP-TIE/PA6/EVOH/PA6/PE-TIE/PE from left to right is 4.64/4.21/1.74/2.18/1.74/5.77/6.66.

B. 2.2% molar amount of sodium alginate added

The materials of each layer in formula (1) were mixed with sodium alginate in a molar ratio of 97.8:2.2, and the molar ratio of hydrophilic groups to carbon atoms after adding sodium alginate to each layer material was calculated:

97.8/100* polypropylene (n hydrophilic group: n carbon atom) +2.2/100* sodium alginate (n hydrophilic group: n carbon atom) = 97.8/100*0+2.2/100*2/3 =0.0147;

97.8/100* maleic anhydride grafted polypropylene copolymer (n hydrophilic group: n carbon atom) + 2.2/100* sodium alginate (n hydrophilic group: n carbon atom) = 97.8/100*0+ 2.2/100*2/3=0.0147;

97.8/100* polyamide 6 (n hydrophilic group: n carbon atom) + 2.2/100* sodium alginate (n hydrophilic group: n carbon atom) = 97.8/100*0+2.2/100*2/ 3=0.0147;

97.8/100* ethylene-vinyl alcohol copolymer (n hydrophilic group: n carbon atom) + 2.2/100* sodium alginate (n hydrophilic group: n carbon atom) = 97.8/100*0+2.2/100 *2/3=0.0147;

97.8/100* maleic anhydride grafted polyethylene copolymer (n hydrophilic group: n carbon atom) +2.2/100* sodium alginate (n hydrophilic group: n carbon atom) = 97.8/100*0+ 2.2/100*2/3=0.0147;

97.8/100* polyethylene (n hydrophilic group: n carbon atom) + 2.2/100* sodium alginate (n hydrophilic group: n carbon atom) = 97.8/100*0+2.2/100*2/3 =0.0147.

It is calculated from the above that in the PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE structure, the materials of each layer are mixed with sodium alginate in a molar ratio of 97.8:2.2, and the mixed pro is calculated. The molar ratio of water groups to carbon atoms is the same, that is, the hydrophilic activities of the materials of the layers tend to be uniform, and the degradation rates tend to be uniform. Alginate added in each layer of material The quality is calculated as follows:

m _1-1 = molecular weight of PP (g/mol) * PP content (%) * molar amount (mol)

=41.07*97.8%*1=40.17 g;

=198.12*2.2%*1=4.36 g;

=45.56*97.8%*1=44.56 g;

=198.12*2.2%*1=4.36 g;

m _1-3 = molecular weight of PA6 (g/mol) * PA6 content (%) * molar amount (mol)

=113.16*97.8%*1=100.67 g;

=198.12*2.2%*1=4.36 g;

=89.73*97.8%*1=87.76 g;

=198.12*2.2%*1=4.36 g;

=32.67*97.8%*1=31.95 g;

=198.12*2.2%*1=4.36 g;

m _1-6 = molecular weight of PE (g/mol) * PE content (%) * molar amount (mol)

=28.05*97.8%*1=27.43 grams;

=198.12*2.2%*1=4.36 g;

Taking the outer layer PP as an example, the mass of the added sodium alginate as a percentage of the mass of the PP is: 4.36 / (40.17 + 4.36) * 100% = 9.79%; the mass percentage of the sodium alginate added in the remaining layers is calculated by Such push;

The percentage by mass of sodium alginate added from left to right of PP/PP-TIE/PA6/EVOH/PA6/PE-TIE/PE is: 9.79/8.91/4.15/4.73/4.15/12.01/13.72.

When the amount of sodium alginate added is in the range of 0.3-15% of the total mass of the corresponding layer material, there is no influence on the mechanical properties and barrier properties of the layer material.

The polylactic acid having a hydrophilic activity greater than the hydrophilic activity of EVOH (hydroxyl) in the composite film material is selected as an additive active agent to weaken the hydrophilic activity of the original hydrophilic group in the composite film material.

1. The monomer formula of polylactic acid is known as H-[OCH(CH3)CO]n-OH. From the molecular formula, the hydrophilic group contained in polylactic acid is carboxyl group (-COOH) and hydroxyl group (- OH) and an ester group (—COOR), wherein the carboxyl group The hydrophilic activity of (-COOH) is greater than the hydrophilic activity of hydroxyl (-OH). The hydrophilic activity of hydroxyl (-OH) in polylactic acid is equal to the hydrophilic activity of hydroxyl (-OH) in ethylene-vinyl alcohol copolymer EVOH. Therefore, in this embodiment, polymer polylactic acid is selected as an active agent to be added to each layer of material.

2. Since the hydrophilic activity of the carboxyl group in the polylactic acid is greater than the hydrophilic activity of the hydroxyl group in the ethylene-vinyl alcohol copolymer having the highest hydrophilic activity in the composite film material, it plays a leading role in the biodegradation process, and the EVOH in the composite film material The hydrophilic activity of the anhydride in the hydroxy group, the amide group in PA, the PP-TIE and the PE-TIE was weakened. To simplify the expression, the hydrophilicity of EVOH, PA, PP-TIE and PE-TIE was assumed in the following calculations. The molar ratio of the group to the carbon atom is zero.

3. Calculated: The molar ratio of hydrophilic group to carbon atom of polylactic acid is 2/3.

Hereinafter, the mass percentage of the polylactic acid added in each layer of the material is calculated by using the amount of the polylactic acid added in a molar ratio of 2% and 0.6% as a reference value:

A. 2% molar amount of polylactic acid added

The material of each layer in the formula (1) is mixed with the polylactic acid in a molar ratio of 98:2, and the molar ratio of the hydrophilic group to the carbon atom after adding the polylactic acid to each layer material is calculated:

98/100* polypropylene (n hydrophilic group: n carbon atom) + 2/100* polylactic acid (n hydrophilic group: n carbon atom) = 98/100*0+2/100*2/3= 0.0333;

98/100* maleic anhydride grafted polypropylene copolymer (n hydrophilic group: n carbon atom) + 2/100* polylactic acid (n hydrophilic group: n carbon atom) = 98/100*0+2 /100*2/3=0.0133;

98/100* polyamide 6 (n hydrophilic group: n carbon atom) + 2/100* polylactic acid (n hydrophilic group: n carbon atom) = 98/100*0+2/100*2/3 =0.0133;

98/100* ethylene-vinyl alcohol copolymer (n hydrophilic group: n carbon atom) + 2/100* polylactic acid (n hydrophilic group: n carbon atom) = 98/100*0+2/100* 2/3=0.0133;

98/100* maleic anhydride grafted polyethylene copolymer (n hydrophilic group: n carbon atom) + 2/100* polylactic acid (n hydrophilic group: n carbon atom) = 98/100*0+2 /100*2/3=0.0133;

98/100* polyethylene (n hydrophilic group: n carbon atom) + 2/100* polylactic acid (n hydrophilic group: n carbon atom) = 98/100*0+2/100*2/3= 0.0133.

It is calculated from the above that in the PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE structure, the materials of each layer are mixed with the polylactic acid in a molar ratio of 98:2, and the hydrophilicity after mixing is calculated. The molar ratio of the group to the carbon atom is the same, that is, the hydrophilic activities of the materials of the layers tend to be uniform, and the degradation rates tend to be uniform. The mass of polylactic acid added in each layer of material is calculated as follows:

It is assumed that the PP after adding polylactic acid is 1 mol, the mass of PP is m _1-1 , and the mass of polylactic acid is m _2-1 ;

m _1-1 = molecular weight of PP (g/mol) * PP content (%) * molar amount (mol)

=41.07*98%*1=40.87 grams;

m _2-1 = molecular weight of polylactic acid (g/mol) * polylactic acid content (%) * molar amount (mol)

=162.14*2%*1=3.24 g;

It is assumed that the PP-TIE after adding polylactic acid is 1 mol, the mass of PP-TIE is m _1-2 , and the mass of polylactic acid is m _2-2 ;

=45.56*98%*1=44.65 g;

m _2-2 = molecular weight of polylactic acid (g/mol) * polylactic acid content (%) * molar amount (mol)

=162.14*2%*1=3.24 g;

It is assumed that the PA6 after adding polylactic acid is 1 mol, the mass of PA6 is m _1-3 , and the mass of polylactic acid is m _2-3 ;

m _1-3 = molecular weight of PA6 (g/mol) * PA6 content (%) * molar amount (mol)

=113.16*98%*1=110.90 g;

m _2-3 = molecular weight of polylactic acid (g/mol) * polylactic acid content (%) * molar amount (mol)

=162.14*2%*1=3.24 g;

It is assumed that the EVOH after adding polylactic acid is 1 mol, the mass of EVOH is m _1-4 , and the mass of polylactic acid is m _2-4 ;

=89.73*98%*1=87.94 g;

m _2-4 = molecular weight of polylactic acid (g/mol) * polylactic acid content (%) * molar amount (mol)

=162.14*2%*1=3.24 g;

It is assumed that the PE-TIE after adding polylactic acid is 1 mol, the mass of PE-TIE is m _1-5 , and the mass of polylactic acid is m _2-5 ;

=32.67*98%*1=32.02 g;

m _2-5 = molecular weight of polylactic acid (g/mol) * polylactic acid content (%) * molar amount (mol)

=162.14*2%*1=3.24 g;

It is assumed that the amount of PE after adding polylactic acid is 1 mol, the mass of PE is m _1-6 , and the mass of polylactic acid is m _2-6 ;

m _1-6 = molecular weight of PE (g/mol) * PE content (%) * molar amount (mol)

=28.05*98%*1=27.49 grams;

m _2-6 = molecular weight of polylactic acid (g/mol) * polylactic acid content (%) * molar amount (mol)

=162.14*2%*1=3.24 g;

As an example of the PP in the outer layer, the mass of the added polylactic acid is a percentage of the mass of the PP. It is: 3.24/(40.87+3.24)*100%=7.35%; the calculation of the mass percentage of polylactic acid added in the remaining layers of materials is similar;

The percentage by mass of PP/PP-TIE/PA6/EVOH/PA6/PE-TIE/PE from left to right polylactic acid was: 7.35/6.77/2.84/3.55/2.84/9.19/10.54.

B. 0.6% molar amount of polylactic acid added

The material of each layer in the formula (1) is mixed with the polylactic acid at a molar ratio of 99.4:0.6, and the molar ratio of the hydrophilic group to the carbon atom after adding the polylactic acid to each layer material is calculated:

99.4/100* polypropylene (n hydrophilic group: n carbon atom) + 0.6/100* polylactic acid (n hydrophilic group: n carbon atom) = 99.4/100*0+0.6/100*2/3= 0.0040;

99.4/100* maleic anhydride grafted polypropylene copolymer (n hydrophilic group: n carbon atom) + 0.6/100* polylactic acid (n hydrophilic group: n carbon atom) = 99.4/100*0+0.6 /100*2/3=0.0040;

99.4/100* polyamide 6 (n hydrophilic group: n carbon atom) + 0.6/100* polylactic acid (n hydrophilic group: n carbon atom) = 99.4/100*0+0.6/100*2/3 =0.0040;

99.4/100* ethylene-vinyl alcohol copolymer (n hydrophilic group: n carbon atom) + 0.6/100* polylactic acid (n hydrophilic group: n carbon atom) = 99.4/100*0+0.6/100* 2/3=0.0040;

99.4/100* maleic anhydride grafted polyethylene copolymer (n hydrophilic group: n carbon atom) + 0.6/100* polylactic acid (n hydrophilic group: n carbon atom) = 99.4/100*0+0.6 /100*2/3=0.0040;

99.4/100* polyethylene (n hydrophilic group: n carbon atom) + 0.6/100* polylactic acid (n hydrophilic group: n carbon atom) = 99.4/100*0+0.6/100*2/3= 0.0040.

It is calculated from the above that in the PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE structure, the materials of each layer are mixed with the polylactic acid in a molar ratio of 99.4:0.6, and the hydrophilicity after mixing is calculated. The molar ratio of the group to the carbon atom is the same, that is, the hydrophilic activities of the materials of the layers tend to be uniform, and the degradation rates tend to be uniform. The mass of polylactic acid added in each layer of material is calculated as follows:

m _1-1 = molecular weight of PP (g/mol) * PP content (%) * molar amount (mol)

=41.07*99.4%*1=40.82 g;

=162.14*0.6%*1=0.97 g;

=45.56*99.4%*1=45.29 grams;

=162.14*0.6%*1=0.97 g;

m _1-3 = molecular weight of PA6 (g/mol) * PA6 content (%) * molar amount (mol)

=113.16*99.4%*1=112.48 g;

=162.14*0.6%*1=0.97 g;

=89.73*99.4%*1=89.19 g;

=162.14*0.6%*1=0.97 g;

=32.67*99.4%*1=32.47 g;

=162.14*0.6%*1=0.97 g;

m _1-6 = molecular weight of PE (g/mol) * PE content (%) * molar amount (mol)

=28.05*99.4%*1=27.88 g;

=162.14*0.6%*1=0.97 g;

Taking the outer layer PP as an example, the mass of the added polylactic acid as a percentage of the mass of the PP is: 0.97 / (40.8 2 + 0.97) * 100% = 2.32%; the calculation of the mass percentage of the polylactic acid added in the remaining layers of materials and so on ;

The percentage by mass of PP/PP-TIE/PA6/EVOH/PA6/PE-TIE/PE from left to right polylactic acid was 2.32/2.10/0.86/1.08/0.86/2.90/3.36.

When the amount of polylactic acid added is in the range of 0.3-15% of the total mass of the corresponding layer material, there is no influence on the mechanical properties and barrier properties of the layer material.

In order to improve the processing suitability and dispersibility of the hydrophilic group, a polymer having excellent compatibility can be selected for copolymerization. For example: a copolymer of polycaprolactone (PCL) copolymerized with sodium alginate.

1. The monomeric formula of sodium alginate is known as (C ₅ H ₇ O ₄ COONa) _n , and the monomeric formula of polycaprolactone is [CH2-(CH2)4-COO] _m , grafting of sodium alginate The monomeric formula of the polycaprolactone copolymer having a rate of 50-80% is [CH2-(CH2)4-COO] _m (C ₅ H ₇ O ₄ COONa) _n , and the molecular formula of the monomer shows that sodium alginate The hydrophilic group contained in the group is sodium carboxylate (—COONa), hydroxyl group (—OH), and ester group (—COOR), and the hydrophilic group contained in the polycaprolactone is an ester group (—COOR), wherein The hydrophilic activity of sodium carboxylate (—COONa) is greater than the hydrophilic activity of hydroxyl (—OH). The hydrophilic activity of hydroxyl (—OH) in sodium alginate is equal to the hydroxyl (—OH) of ethylene-vinyl alcohol copolymer EVOH. Hydrophilic activity, this embodiment selects a sodium alginate grafted polycaprolactone copolymer, the grafting rate of sodium alginate is 60%, and is added as an active agent to each layer of material.

2. Since the hydrophilic activity of sodium carboxylate in the copolymer is greater than the hydrophilic activity of the hydroxyl group in the ethylene-vinyl alcohol copolymer having the highest hydrophilic activity in the composite film material, it plays a leading role in the biodegradation process, and the composite film material The effect of the hydrophilic activity of the hydroxy group in the EVOH, the amide group in the PA, the PP-TIE and the PE-TIE is weakened. To simplify the expression, EVOH, PA, PP-TIE and PE-TIE are assumed in the following calculations. The molar ratio of hydrophilic group to carbon atom is zero.

3. The molar ratio of hydrophilic group to carbon atom of sodium alginate in the sodium alginate grafted polycaprolactone copolymer is 2/3; the molar ratio of hydrophilic group to carbon atom of polycaprolactone is 1/ 7. Calculated: the molar ratio of hydrophilic group to carbon atom of the sodium alginate-grafted polycaprolactone copolymer=2/3*60%+1/7*40%=0.4571.

Hereinafter, the mass percentage of the sodium alginate-grafted polycaprolactone copolymer added in each layer of the material is calculated based on the addition amount of the 2% molar amount of the sodium alginate grafted polycaprolactone copolymer:

The polycaprolactone copolymer grafted with sodium alginate in each layer of the formula (1) is mixed at a molar ratio of 98:2, and the sodium alginate grafted polycaprolactone is calculated for each layer of material. The molar ratio of hydrophilic groups to carbon atoms after the copolymer:

98/100* polypropylene _{(n hydrophilic group: n carbon atom)} +2/100* sodium alginate grafted polycaprolactone copolymer _{(n hydrophilic group: n carbon atom)} = 98/100* 0+2/100*45.71/100=0.0091;

98/100* maleic anhydride grafted polypropylene copolymer _{(n hydrophilic group: n carbon atom)} + 2/100* sodium alginate grafted polycaprolactone copolymer _(n _{hydrophilic group: n carbon Atomic)} =98/100*0+2/100*45.71/100=0.0091;

98/100* polyamide 6 _{(n hydrophilic group: n carbon atom)} +2/100* sodium alginate grafted polycaprolactone copolymer _{(n hydrophilic group: n carbon atom)} = 98/100 *0+2/100*45.71/100=0.0091;

98/100* ethylene-vinyl alcohol copolymer _{(n hydrophilic group: n carbon atom)} + 2/100* sodium alginate grafted polycaprolactone copolymer _{(n hydrophilic group: n carbon} _atom) = 98/100*0+2/100*45.71/100=0.0091;

98/100* maleic anhydride grafted polyethylene copolymer _{(n hydrophilic group: n carbon atom)} + 2/100* sodium alginate grafted polycaprolactone copolymer _(n _{hydrophilic group: n carbon Atomic)} =98/100*0+2/100*45.71/100=0.0091;

98/100* polyethylene _{(n hydrophilic group: n carbon atom)} +2/100* sodium alginate grafted polycaprolactone copolymer _{(n hydrophilic group: n carbon atom)} = 98/100* 0+2/100*45.71/100=0.0091;

From the above calculations: in the PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE structure, the ratio of the polycaprolactone grafted with the sodium alginate in each layer of the material is 98: 2 The mixing is carried out, and the molar ratio of the hydrophilic group to the carbon atom is calculated to be the same, that is, the hydrophilic activities of the materials of the layers tend to be uniform, and the degradation rates tend to be uniform. The mass of the sodium alginate grafted polycaprolactone copolymer added in each layer of material is calculated as follows:

It is assumed that the PP of the sodium alginate grafted polycaprolactone copolymer is 1 mol, the mass of the PP is m _1-1 , and the mass of the sodium alginate grafted polycaprolactone copolymer is m _2-1. ;

m _1-1 = molecular weight of PP (g/mol) * PP content (%) * molar amount (mol)

=41.07*98%*1=40.25 g;

m _2-1 = molecular weight (g/mol) of sodium alginate grafted polycaprolactone copolymer * sodium alginate grafted polycaprolactone copolymer content (%) * molar amount (mol)

=164.52*2%*1=3.29 g;

The PP-TIE after adding the sodium alginate grafted polycaprolactone copolymer is 1 mole, the mass of the PP-TIE is m _1-2 , and the mass of the sodium alginate grafted polycaprolactone copolymer is m _2-2 ;

=45.56*98%*1=44.65 g;

m _2-2 = molecular weight (g/mol) of sodium alginate grafted polycaprolactone copolymer * sodium alginate grafted polycaprolactone copolymer content (%) * molar amount (mol)

=164.52*2%*1=3.29 g;

It is assumed that the PA6 of the sodium alginate grafted polycaprolactone copolymer is 1 mol, the mass of the PA6 is m _1-3 , and the mass of the sodium alginate grafted polycaprolactone copolymer is m _2-3. ;

m _1-3 = molecular weight of PA6 (g/mol) * PA6 content (%) * molar amount (mol)

=113.16*98%*1=1120.90 g;

m _2-3 = molecular weight (g/mol) of sodium alginate grafted polycaprolactone copolymer * sodium alginate grafted polycaprolactone copolymer content (%) * molar amount (mol)

=164.52*2%*1=3.29 g;

It is assumed that the EVOH of the sodium alginate grafted polycaprolactone copolymer is 1 mol, the mass of the EVOH is m _1-4 , and the mass of the sodium alginate grafted polycaprolactone copolymer is m _2-4 ;

=89.73*98%*1=87.94 g;

m _2-4 = molecular weight (g/mol) of sodium alginate grafted polycaprolactone copolymer * sodium alginate grafted polycaprolactone copolymer content (%) * molar amount (mol)

=164.52*2%*1=3.29 g;

The PE-TIE after adding the sodium alginate grafted polycaprolactone copolymer is 1 mol, the mass of the PE-TIE is m _1-5 , and the mass of the sodium alginate grafted polycaprolactone copolymer is m _2-5 ;

=32.67*98%*1=32.02 g;

m _2-5 = molecular weight (g/mol) of sodium alginate grafted polycaprolactone copolymer * sodium alginate grafted polycaprolactone copolymer content (%) * molar amount (mol)

=164.52*2%*1=3.29 g;

It is assumed that the polyethylene of the sodium alginate grafted polycaprolactone copolymer is 1 mol, the mass of the PE is m _1-6 , and the mass of the sodium alginate grafted polycaprolactone copolymer is m _2-6. ;

m _1-6 = molecular weight of PE (g/mol) * PE content (%) * molar amount (mol)

=28.05*98%*1=27.49 grams;

m _2-6 = molecular weight (g/mol) of sodium alginate grafted polycaprolactone copolymer * sodium alginate grafted polycaprolactone copolymer content (%) * molar amount (mol)

=164.52*2%*1=3.29 g;

Taking the outer layer PP as an example, the mass of the added sodium alginate grafted polycaprolactone copolymer accounts for the mass of the PP: 3.29/(40.25+3.29)*100%=7.56%; the remaining layers are added to the material. The calculation of the mass percentage of the sodium alginate grafted polycaprolactone copolymer is analogous;

The percentage by mass of PP/PP-TIE/PA6/EVOH/PA6/PE-TIE/PE from left to right sodium alginate grafted polycaprolactone copolymer is:

7.56/6.86/2,88/3.61/2.88/9.32/10.69.

When the polycaprolactone copolymer of the sodium alginate grafted polycaprolactone copolymer is added, the total mass of the corresponding layer material is When it is in the range of 0.3-15%, there is no influence on the mechanical properties and barrier properties of the layer material.

Embodiment 2: (Example of the second technical solution)

PP/PP-TIE/EVOH/PE-TIE/PE type (2)

In equation (2), the meanings from left to right are:

EVOH denotes a middle layer which functions as a barrier layer, the material of which is EVOH represents an ethylene-vinyl alcohol copolymer, the ethylene-vinyl alcohol copolymer is 32% by weight of ethylene PE and 68% by weight of vinyl alcohol PVA, and the monomer molecular formula is [ CH ₂ CH ₂ ] ₁ [CH ₂ CHOH] _1.4 , the hydrophilic group contained in the ethylene-vinyl alcohol copolymer is hydroxyl-OH;

The barrier layer, an ethylene - vinyl alcohol copolymer has a density of 1.170g / cm ^3, the actual application, if we take a density of ^{1.190g / cm 3, 1.18g / cm} 3 or other between 1.170-1.190g / cm The value between the ^three can also achieve the same effect. The ethylene-vinyl alcohol copolymer has an ethylene molar content of 32%. In practical applications, if the ethylene molar content is 26%, 30%, 48% or other between 26-48 The value between % can also achieve the same effect.

Each layer of the composite film obtains a uniform biodegradability by introducing a bio-based group, which is a type of additive masterbatch having biodegradability in a garbage disposal site or composting condition, the addition The master batch is uniformly added to each layer of the material in proportion, and then the composite film is prepared by a melt coextrusion method.

(2) The layers of additive in the masterbatch and the hydrophilic group according to the formula hydrophilic active were ordered from carboxylate -COO ^-, a carboxyl group -COOH, a hydroxyl group -OH, -CHO aldehyde , amide group - CONH ₂ , anhydride - OC-O-CO -, ester group - COOR.

According to the composite film structure of the second embodiment, the hydrophilic activity of the hydrophilic groups contained in the various materials is ranked from high to low to hydroxyl>anhydride, that is, the hydrophilic activity of each layer of the material in the formula (2) is ranked from high to low. It is ethylene-vinyl alcohol copolymer EVOH (32% PE + 68% PVA) > PP-TIE (95% PP + 5% maleic anhydride) > PE-TIE (95% PE + 5% maleic anhydride) > polyethylene PE = polypropylene PP.

2. Since the hydrophilic activity of sodium carboxylate in sodium alginate is greater than the hydrophilic activity of hydroxyl groups in the ethylene-vinyl alcohol copolymer having the highest hydrophilic activity in the composite film material, it plays a leading role in the biodegradation process, and the composite film The effect of the hydrophilic activity of the hydroxyl groups in the EVOH, PP-TIE and PE-TIE in the material was weakened. To simplify the description, the hydrophilic groups and carbon of EVOH, PP-TIE and PE-TIE were assumed in the following calculations. The atomic molar ratio is zero.

4. The molar ratio of hydrophilic group to carbon atom of EVOH, PP-TIE, PE-TIE, PE, PP is 0.

A. 1% molar amount of sodium alginate added

It is calculated from the above that in the PP/PP-TIE/EVOH/PE-TIE/PE structure, the materials of each layer are mixed with sodium alginate in a molar ratio of 99:1, and the mixed hydrophilic groups are calculated. The molar ratios of the carbon atoms are the same, that is, the hydrophilic activities of the materials of the layers tend to be uniform, and the degradation rates tend to be uniform. The mass of sodium alginate added in each layer of material is calculated as follows:

m _1-1 = molecular weight of PP (g/mol) * PP content (%) * molar amount (mol)

=41.07*99%*1=40.66 g;

=198.12*1%*1=1.98 g;

=45.56*99%*1=45.10 g;

=198.12*1%*1=1.98 g;

It is assumed that the EVOH after adding sodium alginate is 1 mol, the mass of EVOH is m _1-3 , and the mass of sodium alginate is m _2-3 ;

m _1-3 = molecular weight of EVOH (g/mol) * EVOH content (%) * molar amount (mol)

=89.73*99%*1=88.83 grams;

=198.12*1%*1=1.98 g;

It is assumed that the PE-TIE after adding sodium alginate is 1 mol, the mass of PE-TIE is m _1-4 , and the mass of sodium alginate is m _2-4 ;

m _1-4 = PE-TIE molecular weight (g / mol) * PE-TIE content (%) * molar rate (mol)

=32.67*99%*1=32.34 grams;

=198.12*1%*1=1.98 g;

It is assumed that the amount of PE after adding sodium alginate is 1 mol, the mass of PE is m _1-5 , and the mass of sodium alginate is m _2-5 ;

m _1-5 = molecular weight of PE (g/mol) * PE content (%) * molar amount (mol)

=28.05*99%*1=27.77 grams;

=198.12*1%*1=1.98 g;

Taking the outer layer PP as an example, the mass of the added sodium alginate as a percentage of the mass of the PP is: 1.98 / (40.66 + 1.98) * 100% = 4.64%; the mass percentage of the sodium alginate added in the remaining layers is calculated by Such push;

The percentage of added mass of sodium alginate from PP to PP-TIE/EVOH/PE-TIE/PE from left to right is:

4.64/4.21/2.18/5.77/6.66.

B. 2.2% molar amount of sodium alginate added

The material of each layer in formula (2) was mixed with sodium alginate in a molar ratio of 97.8:2.2, and the molar ratio of hydrophilic group to carbon atom after adding sodium alginate to each layer material was calculated:

97.8/100* polypropylene (n hydrophilic group: n carbon atom) + 2.2/100* sodium alginate (n hydrophilic group: n carbon atom) = 97.8/100*0+2.2/100*2/3=0.0147;

It is calculated from the above that in the PP/PP-TIE/EVOH/PE-TIE/PE structure, the materials of each layer are mixed with sodium alginate in a molar ratio of 97.8:2.2, and the mixed hydrophilic groups are calculated. The molar ratios of the carbon atoms are the same, that is, the hydrophilic activities of the materials of the layers tend to be uniform, and the degradation rates tend to be uniform. The mass of sodium alginate added in each layer of material is calculated as follows:

m _1-1 = molecular weight of PP (g/mol) * PP content (%) * molar amount (mol)

=41.07*97.8%*1=40.17 g;

=198.12*2.2%*1=4.36 g;

=45.56*97.8%*1=44.56 g;

=198.12*2.2%*1=4.36 g;

=89.73*97.8%*1=87.76 g;

=198.12*2.2%*1=4.36 g;

=32.67*97.8%*1=31.95 g;

=198.12*2.2%*1=4.36 g;

m _1-5 = molecular weight of PE (g/mol) * PE content (%) * molar amount (mol)

=28.05*97.8%*1=27.43 grams;

=198.12*2.2%*1=4.36 g;

9.79/8.91/4.73/12.01/13.72.

1. The monomer formula of polylactic acid is known as H-[OCH(CH3)CO]n-OH. From the molecular formula, the hydrophilic group contained in polylactic acid is carboxyl group (-COOH) and hydroxyl group (- OH) and an ester group (—COOR), wherein the hydrophilic activity of the carboxyl group (-COOH) is greater than the hydrophilic activity of the hydroxyl group (—OH), and the hydrophilic activity of the hydroxyl group (—OH) in the polylactic acid is equal to the ethylene-vinyl alcohol copolymerization. The hydrophilic activity of the hydroxyl group (—OH) in the EVOH, so in this embodiment, the polymer polylactic acid is selected as an active agent and added to each layer of material.

2. Since the hydrophilic activity of the carboxyl group in the polylactic acid is greater than the hydrophilic activity of the hydroxyl group in the ethylene-vinyl alcohol copolymer having the highest hydrophilic activity in the composite film material, it plays a leading role in the biodegradation process, and the EVOH in the composite film material The effect of the hydrophilic activity of the anhydride in the hydroxyl group, PP-TIE and PE-TIE was weakened. To simplify the expression, the molar ratio of hydrophilic groups to carbon atoms of EVOH, PP-TIE and PE-TIE was assumed in the following calculations. Is 0.

A. 2% molar amount of polylactic acid added

The material of each layer in the formula (2) is mixed with the polylactic acid in a molar ratio of 98:2, and the molar ratio of the hydrophilic group to the carbon atom after adding the polylactic acid to each layer material is calculated:

98/100* polypropylene (n hydrophilic group: n carbon atom) + 2/100* polylactic acid (n hydrophilic group: n carbon atom) = 98/100*0+2/100*2/3= 0.0133;

It is calculated from the above that in the PP/PP-TIE/EVOH/PE-TIE/PE structure, the material of each layer is mixed with the polylactic acid in a molar ratio of 98:2, and the mixed hydrophilic group and carbon are calculated. The molar ratios of the atoms are the same, that is, the hydrophilic activities of the materials of the layers tend to be uniform, and the degradation rates tend to be uniform. The mass of polylactic acid added in each layer of material is calculated as follows:

m _1-1 = molecular weight of PP (g/mol) * PP content (%) * molar amount (mol)

=41.07*98%*1=40.87 grams;

=162.14*2%*1=3.24 g;

=45.56*98%*1=44.65 g;

=162.14*2%*1=3.24 g;

It is assumed that the EVOH after adding polylactic acid is 1 mol, the mass of EVOH is m _1-3 , and the mass of polylactic acid is m _2-3 ;

=89.73*98%*1=87.94 g;

=162.14*2%*1=3.24 g;

It is assumed that the PE-TIE after adding polylactic acid is 1 mol, the mass of PE-TIE is m _1-4 , and the mass of polylactic acid is m _2-4 ;

=32.67*98%*1=32.02 g;

=162.14*2%*1=3.24 g;

It is assumed that the amount of PE after adding polylactic acid is 1 mol, the mass of PE is m _1-5 , and the mass of polylactic acid is m _2-5 ;

m _1-5 = molecular weight of PE (g/mol) * PE content (%) * molar amount (mol)

=28.05*98%*1=27.49 grams;

=162.14*2%*1=3.24 g;

Taking the outer layer PP as an example, the mass of the added polylactic acid accounts for the mass of the PP: 3.24/(40.87+3.24)*100%=7.35%; the calculation of the mass percentage of the polylactic acid added in the remaining layers of materials and so on ;

The percentage by mass of PP/PP-TIE/EVOH/PE-TIE/PE from left to right polylactic acid is:

7.35/6.77/3.55/9.19/10.54.

B. 0.6% molar amount of polylactic acid added

The material of each layer in the formula (2) is mixed with the polylactic acid in a molar ratio of 99.4:0.6, and the molar ratio of the hydrophilic group to the carbon atom after adding the polylactic acid to each layer material is calculated:

It is calculated from the above that in the PP/PP-TIE/EVOH/PE-TIE/PE structure, the material of each layer is mixed with the polylactic acid in a molar ratio of 99.4:0.6, and the mixed hydrophilic group and carbon are calculated. The molar ratios of the atoms are the same, that is, the hydrophilic activities of the materials of the layers tend to be uniform, and the degradation rates tend to be uniform. The mass of polylactic acid added in each layer of material is calculated as follows:

m _1-1 = molecular weight of PP (g/mol) * PP content (%) * molar amount (mol)

=41.07*99.4%*1=40.82 g;

=162.14*0.6%*1=0.97 g;

=45.56*99.4%*1=45.29 grams;

=162.14*0.6%*1=0.97 g;

=89.73*99.4%*1=89.19 g;

=162.14*0.6%*1=0.97 g;

=32.67*99.4%*1=32.47 g;

=162.14*0.6%*1=0.97 g;

m _1-5 = molecular weight of PE (g/mol) * PE content (%) * molar amount (mol)

=28.05*99.4%*1=27.88 g;

=162.14*0.6%*1=0.97 g;

2.32/2.10/1.08/2.90/3.36.

2. Since the hydrophilic activity of sodium carboxylate in the copolymer is greater than the hydrophilic activity of the hydroxyl group in the ethylene-vinyl alcohol copolymer having the highest hydrophilic activity in the composite film material, it plays a leading role in the biodegradation process, and the composite film material The effect of the hydrophilic activity of the hydroxy group in the EVOH, PP-TIE and PE-TIE is weakened. To simplify the expression, the following calculation It is assumed that the molar ratio of the hydrophilic group to the carbon atom of EVOH, PP-TIE and PE-TIE is zero.

The polycaprolactone copolymer grafted with sodium alginate in each layer of the formula (2) is mixed at a molar ratio of 98:2, and the sodium alginate grafted polycaprolactone is calculated for each layer of material. The molar ratio of hydrophilic groups to carbon atoms after the copolymer:

It is calculated from the above that in the PP/PP-TIE/EVOH/PE-TIE/PE structure, the polycaprolactone copolymers respectively grafted with sodium alginate are mixed at a molar ratio of 98:2. Calculate the molar ratio of mixed hydrophilic groups to carbon atoms The same is true, that is, the hydrophilic activity of each layer of materials tends to be uniform, and the degradation rates tend to be uniform. The mass of the sodium alginate grafted polycaprolactone copolymer added in each layer of material is calculated as follows:

m _1-1 = molecular weight of PP (g/mol) * PP content (%) * molar amount (mol)

=41.07*98%*1=40.25 g;

=164.52*2%*1=3.29 g;

=45.56*98%*1=44.65 g;

=164.52*2%*1=3.29 g;

It is assumed that the EVOH of the sodium alginate grafted polycaprolactone copolymer is 1 mol, the mass of the EVOH is m _1-3 , and the mass of the sodium alginate grafted polycaprolactone copolymer is m _2-3 ;

=89.73*98%*1=87.94 g;

=164.52*2%*1=3.29 g;

The PE-TIE after adding the sodium alginate grafted polycaprolactone copolymer is 1 mole, the mass of the PE-TIE is m _1-4 , and the mass of the sodium alginate grafted polycaprolactone copolymer is m _2-4 ;

=32.67*98%*1=32.02 g;

=164.52*2%*1=3.29 g;

It is assumed that the polyethylene of the sodium alginate grafted polycaprolactone copolymer is 1 mol, the mass of the PE is m _1-5 , and the mass of the sodium alginate grafted polycaprolactone copolymer is m _2-5. ;

m _1-5 = molecular weight of PE (g/mol) * PE content (%) * molar amount (mol)

=28.05*98%*1=27.49 grams;

=164.52*2%*1=3.29 g;

The percentage by mass of PP/PP-TIE/EVOH/PE-TIE/PE from left to right sodium alginate grafted polycaprolactone copolymer is:

7.56/6.86/3.61/9.32/10.69.

When the polycaprolactone copolymer of the sodium alginate grafted polycaprolactone copolymer is added in an amount of 0.3-15% of the total mass of the corresponding layer material, the mechanical properties and barrier properties of the layer material are not affected. .

In the above embodiment, the active agent selected sodium alginate, polylactic acid, and sodium alginate-grafted polycaprolactone copolymer, which are directly supported by the above embodiments, but in the present invention, in addition to the above In addition to the active agent, other polymers containing a hydrophilic group carboxylate, a carboxyl group, a hydroxyl group, an aldehyde group, an amide group, an acid anhydride, and an ester group, such as polycaprolactone and polycaprolactone polyol, may also be selected. Polysaccharide polymers, algae-based polymers, etc., those skilled in the art can understand and predict specific polymers containing these groups under the inspiration of the embodiments of the present invention, so the additive masterbatch described in the present invention is not limited These polymers are given by the examples.

In the above embodiments, the addition amount of the additive type masterbatch only gives some examples in numerical value, and those skilled in the art, inspired by the example, easily think that the additive type master batch can be in the range of 0.3-15%. The object and effect of the present invention are achieved.

In the above examples, in order to facilitate the implementation (suitable for melt extrusion), a range of density, copolymerization ratio, blending ratio of each layer of material is defined, and exemplified in the examples, but these requirements are for the present invention. It is not essential and should not be used as a basis for limiting the scope of protection of the present invention. In other words, the above various indexes suitable for melt extrusion outside the above range can realize the present invention and obtain corresponding technical effects.

In the present invention, although the structural formula of the composite film is given, the same material in the same position in the structural formula may be formed by one or more layers, for example, PP/PP-TIE/PA/EVOH/PA/PE- In the TIE/PE structural formula, the structural expression expresses a 7-layer structure on the surface, but the material at any position may be formed by combining two or more layers. For example, PE may be formed by combining two layers, thereby making the composite The film is formed by combining 8 layers, and so on.

The above embodiments are only for explaining the technical idea and the features of the present invention, and the purpose is to enable those skilled in the art to understand the contents of the present invention and implement them according to the above embodiments. Those skilled in the art can make other based on the above embodiments. Changes, such as selecting different densities of materials, selecting different activators, etc., do not limit the protection of the present invention. Range of protection. Equivalent variations or modifications made in accordance with the spirit of the invention are intended to be included within the scope of the invention.

Claims

A degradable PP-EVOH high barrier composite film, the structure of the composite film is as follows:

PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE type (1)

In the formula (1), the meanings from the left to the right are:

PP means an outer layer, the function of which is a protective layer or a display layer, the material of which is polypropylene, and the polypropylene does not contain a hydrophilic group;

PP-TIE denotes a first adhesive layer, the material of which is a maleic anhydride grafted polypropylene copolymer, and the maleic anhydride grafted polypropylene copolymer contains a hydrophilic group which is an acid anhydride;

PA/EVOH/PA denotes a middle layer formed by a combination of three layers, the function of which is a barrier layer, the material of which is PA represents polyamide, the hydrophilic group of polyamide contains amide group, and EVOH represents ethylene-vinyl alcohol copolymer. The hydrophilic group contained in the ethylene-vinyl alcohol copolymer is a hydroxyl group;

PE-TIE denotes a second adhesive layer whose material is a maleic anhydride grafted polyethylene copolymer, and the maleic anhydride grafted polyethylene copolymer contains a hydrophilic group which is an acid anhydride;

PE denotes an inner layer, the function of which is a heat seal layer, the material of which is polyethylene, and the polyethylene does not contain a hydrophilic group;

The invention is characterized in that each layer material in the composite film obtains a uniform biodegradability by introducing a bio-based group, which is a kind of additive type having biodegradability in a garbage disposal field or composting condition. The additive masterbatch is uniformly added to each layer of the material in proportion, and then the composite film is prepared by a melt coextrusion method;

The additive type masterbatch is composed of a carrier and an active agent, and the active agent is a polymer containing a hydrophilic group, wherein the active component of the active agent is a hydrophilic group, and the hydrophilic group means a carboxylic acid. At least one of a salt, a carboxyl group, a hydroxyl group, an aldehyde group, an amide group, an acid anhydride, and an ester group;

In the material of each layer of the formula (1) and the additive type masterbatch, the hydrophilic group is a carboxylate, a carboxyl group, a hydroxyl group, an aldehyde group, an amide group, an acid anhydride, an ester group in order of the hydrophilic activity from high to low;

The carrier is selected for each layer of material according to a similar compatibility principle:

For the outer layer of the polypropylene material, the carrier in the additive type master batch is at least one of polypropylene and polyethylene;

For the maleic anhydride grafted polypropylene copolymer material of the first adhesive layer, the carrier in the additive type master batch is at least one of polypropylene and polyethylene;

For the middle layer of the polyamide material, the carrier in the added masterbatch is a polyamide;

For the intermediate layer of ethylene-vinyl alcohol copolymer material, the carrier in the additive type masterbatch is polyethylene;

For the maleic anhydride grafted polyethylene copolymer material of the second adhesive layer, the carrier in the additive type master batch is polyethylene; and for the inner layer of the polyethylene material, the carrier in the additive type master batch is polyethylene;

The added amount of the added masterbatch in each layer of material is controlled within a range of 0.3-15% of the total mass of the layer of the material; the hydrophilic activity of the hydrophilic group in the added masterbatch should be greater than or equal to the formula (1) The hydrophilic activity of the hydrophilic group in each layer of material; by adding the additive type masterbatch, the molar ratio of the hydrophilic group to the carbon atom of each layer of the material in the formula (1) tends to be uniform, that is, the biological activity tends to Consistently, the degradation rate of each layer of the composite film tends to be uniform.
A degradable PP-EVOH high barrier composite film, the structure of the composite film is as follows:

PP/PP-TIE/EVOH/PE-TIE/PE type (2)

In equation (2), the meanings from left to right are:

PP means an outer layer, the function of which is a protective layer or a display layer, the material of which is polypropylene, and the polypropylene does not contain a hydrophilic group;

PP-TIE denotes a first adhesive layer, the material of which is a maleic anhydride grafted polypropylene copolymer, and the maleic anhydride grafted polypropylene copolymer contains a hydrophilic group which is an acid anhydride;

EVOH denotes a middle layer, the function of which is a barrier layer, the material of which is an ethylene-vinyl alcohol copolymer, and the hydrophilic group contained in the ethylene-vinyl alcohol copolymer is a hydroxyl group;

PE-TIE denotes a second adhesive layer whose material is a maleic anhydride grafted polyethylene copolymer, and the maleic anhydride grafted polyethylene copolymer contains a hydrophilic group which is an acid anhydride;

PE denotes an inner layer, the function of which is a heat seal layer, the material of which is polyethylene, and the polyethylene does not contain a hydrophilic group;

The invention is characterized in that each layer material in the composite film obtains a uniform biodegradability by introducing a bio-based group, which is a kind of additive type having biodegradability in a garbage disposal field or composting condition. Material, the addition The additive masterbatch is uniformly added to each layer of the material in proportion, and then the composite film is prepared by a melt coextrusion method;

The additive type masterbatch is composed of a carrier and an active agent, and the active agent is a polymer containing a hydrophilic group, wherein the active component of the active agent is a hydrophilic group, and the hydrophilic group means a carboxylic acid. At least one of a salt, a carboxyl group, a hydroxyl group, an aldehyde group, an amide group, an acid anhydride, and an ester group;

In the material of each layer of the formula (2) and the additive type masterbatch, the hydrophilic group is a carboxylate, a carboxyl group, a hydroxyl group, an aldehyde group, an amide group, an acid anhydride, an ester group in order of the hydrophilic activity from high to low;

The carrier is selected for each layer of material according to a similar compatibility principle:

For the outer layer of the polypropylene material, the carrier in the additive type master batch is at least one of polypropylene and polyethylene;

For the maleic anhydride grafted polypropylene copolymer material of the first adhesive layer, the carrier in the additive type master batch is at least one of polypropylene and polyethylene;

For the intermediate layer of ethylene-vinyl alcohol copolymer material, the carrier in the additive type masterbatch is polyethylene;

For the maleic anhydride grafted polyethylene copolymer material of the second adhesive layer, the carrier in the additive type master batch is polyethylene; and for the inner layer of the polyethylene material, the carrier in the additive type master batch is polyethylene;

The added amount of the added masterbatch in each layer of material is controlled within a range of 0.3-15% of the total mass of the layer of the material; the hydrophilic activity of the hydrophilic group in the added masterbatch should be greater than or equal to the formula (2) The hydrophilic activity of the hydrophilic group in each layer of material; by adding the additive type masterbatch, the molar ratio of the hydrophilic group to the carbon atom of each layer of the material in the formula (2) tends to be uniform, that is, the biological activity tends to Consistently, the degradation rate of each layer of the composite film tends to be uniform.
The degradable PP-EVOH high barrier composite film according to claim 1 or 2, wherein in the outer layer, the polypropylene is composed of an isotactic polypropylene homopolymer or/and a polypropylene random copolymer. The composition has a density of polypropylene of 0.880 to 0.910 g/cm 3 .
The degradable PP-EVOH high barrier composite film according to claim 1 or 2, wherein the density of the maleic anhydride grafted polypropylene copolymer in the first adhesive layer is from 0.880 to 0.910 g/cm. 3 , wherein the maleic anhydride grafting rate is from 0.3% to 10% by mass.
The degradable PP-EVOH high barrier composite film according to claim 1, wherein the density of the ethylene-vinyl alcohol copolymer in the barrier layer is 1.170-1.19 g/cm 3 , and the ethylene-vinyl alcohol copolymer The ethylene has a molar content of from 26 to 48%; the polyamide has a density of from 1.12 to 1.14 g/cm 3 and the polyamide is a PA6 homopolymer or a PA 6,66 copolymer or an amorphous polyamide.
The degradable PP-EVOH high barrier composite film according to claim 2, wherein the density of the ethylene-vinyl alcohol copolymer in the barrier layer is 1.170-1.19 g/cm 3 , and the ethylene-vinyl alcohol copolymer The ethylene content is from 26 to 48%.
The degradable PP-EVOH high barrier composite film according to claim 1 or 2, wherein the density of the maleic anhydride grafted polyethylene copolymer in the second adhesive layer is from 0.910 to 0.950 g/ Cm 3 wherein the maleic anhydride graft ratio is from 0.3% to 10% by mass.
The degradable PP-EVOH high barrier composite film according to claim 1 or 2, wherein the density of the polyethylene in the heat seal layer is 0.900-0.935 g/cm 3 , and the polyethylene comprises polyethylene. a blend having a density of from 0.910 to 0.925 g/cm 3 and a polyethylene blend consisting of 50-99% by weight of polyethylene and 1-50% by weight of a vinyl homopolymer. Or the polyethylene blend consists of 50-99% by weight of polyethylene and 1-50% by weight of a vinyl copolymer composed of ethylene and a C4-C12 alpha-olefin, a cyclic olefin, It is composed of at least one of a vinyl aromatic hydrocarbon and a polar vinyl monomer having a density of 0.880 to 0.915 g/cm 3 .