AU2015361915B2

AU2015361915B2 - Degradable PP-EVOH high resistance composite thin-film

Info

Publication number: AU2015361915B2
Application number: AU2015361915A
Authority: AU
Inventors: Xuewen Gao; Minyan TANG; Jialiang XIA; Yu Xia; Xiaoqin YU
Original assignee: J&A Industrial Suzhou Co Ltd
Current assignee: J&A Industrial Suzhou Co Ltd
Priority date: 2014-12-11
Filing date: 2015-04-16
Publication date: 2018-06-28
Anticipated expiration: 2035-04-16
Also published as: WO2016090806A1; AU2015361915A1; CN104369508B; CN104369508A

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

BACKGROUND OF INVENTION [0001a] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

[0002] Multilayer co-extruded film is the film made with several types of polymers by methods of co-extrusion blowing, casting or orientation. As plastic packaging material, this kind of film is widely used in food, processed meat, daily necessity, cosmetics, chemical, pesticide and military products etc. It can be used in sealed flexible packaging for gas puffing, vacuum and thermoforming etc. as well as providing barrier function such as moisture, oxygen, oil and aroma barrier etc. in various circumstances.

[0003] Along with the wide use of multilayer film in large quantity in various fields, pollution to the environment caused by multilayer film is becoming serious. Since it is difficult to degrade, with its growing consumption, pollution caused by multilayer film has become worldwide public hazard. Currently, traditional methods for multilayer film waste disposal such as incineration, landfill and recycle etc. are all with disadvantages and have limitations which brings heavy burden to the environment, therefore development of biodegradable multilayer film which is able to reduce pollution to the environment is an important way to solve the pollution problem.

[0004] According to the research of the applicant, the existing achievement right now is blank for biodegradation technology and its related application technology for multilayer film with uniform degrading speed for each layer. No related reporting has been found yet both domestic and abroad. However, considering the rapid increase of market demand and protection of ecological balance, research for biodegradable multilayer co-extruded film is pressing, among which, in the biodegrading process, how to achieve approximate uniform degrading speed for materials of each layer in the multilayer co-extruded film without loss of mechanical performance and shelf life of the film is an important research topic with practical significance.

DISCLOSURE OF THE INVENTION [0004a] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0005] The purpose of a preferred embodiment of this invention is to provide a degradable PPEVOH high barrier multilayer film with approximate uniform biodegrading speed of each layer.

[0006] To achieve above aim, the first technical solution applied in this invention is: a degradable PP-EVOH high barrier multilayer film with structure as follows:

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

2015361915 31 May 2018

In Structure (1), explicated from left to right:

PP represents the outer layer functioning as protection or displaying layer. Its material is polypropylene which doesn’t contain the hydrophilic group:

PP-TIE represents the 1st bonding layer. Its material is maleic anhydride grafted polypropylene copolymer containing hydrophilic group of acid anhydride;

PA/EVOH/PA represents the middle layer consisting of three-layer structure and functioning as barrier layer. Its material PA represents the polyamide containing the hydrophilic group of amide group, EVOH represents the ethylene-vinyl alcohol copolymer, containing the hydrophilic group of hydroxyl;

PE-TIE represents the 2nd bonding layer. Its material is maleic anhydride grafted polyethylene copolymer containing hydrophilic group of acid anhydride;

PE represents the inner layer functioning as heat-sealing layer. Its material is polyethylene, which does not contain hydrophilic groups;

The innovation is: the materials in different layers of the multilayer film gain proximate uniform biodegradability through the introduction of biological carrier. The biological carrier is an addible masterbatch with biodegradability in landfill or composting condition. The materials of each layer are added pro rata with the masterbatch and melt co-extruded to be multilayer film;

The addible masterbatch is composed of carrier and activator. The activator is polymer containing hydrophilic group which is the effective component. The hydrophilic group is at least one of the carboxylate, carboxyl, hydroxyl, aldehyde, amide, acid anhydride and ester group;

For Structure (1), in the materials of each layer and the addible masterbatch, the ranking of hydrophility of the hydrophilic group from high to low is carboxylate, carboxyl, hydroxyl, aldehyde, amide, acid anhydride and ester group;

The carrier is selected according to the like dissolves like principle:

For the polypropylene material of outer layer, the carrier of the addible masterbatch is at least one of the polypropylene and polyethylene;

For the maleic anhydride grafted polypropylene copolymer material of 1st bonding layer, the carrier of the addible masterbatch is at least one of the polypropylene and polyethylene;

For the polyamide material of middle layer, the carrier of the addible masterbatch is polyamide;

For the ethylene-vinyl alcohol copolymer material of middle layer, the carrier of the addible masterbatch is polyethylene;

For the maleic anhydride grafted polyethylene copolymer material of 2nd bonding layer, the carrier of the addible masterbatch is polyethylene;

For the polyethylene material of inner layer, the carrier of the addible masterbatch is polyethylene; The additive volume of the masterbatch to the materials of each layer is controlled within 0.3-15% of the total mass of each layer; the hydrophility of the hydrophilic group in the addible masterbatch should be higher than or equal to the hydrophility of hydrophilic group in materials of each layer in Structure (1). Through addition of the addible masterbatch, the molar ratio of hydrophilic group vs.

2015361915 31 May 2018 carbon atom in materials of each layer in Structure (1) is approaching uniform, namely biological activity of materials of each layer is approaching uniform, so the degrading speed of materials of each layer is approaching uniform.

[0007] To achieve above aim, the second technical solution applied in this invention is: a degradable PP-EVOH high barrier multilayer film with structure as follows: PP/PP-TIE/EVOH/PE-TIE/PE Structure (2)

In Structure (2), explicated from left to right:

PP represents the outer layer functioning as protection or displaying layer. Its material is polypropylene which doesn’t contain the hydrophilic group;

EVOH represents the middle layer functioning as barrier layer. Its material is the ethylene-vinyl alcohol copolymer, containing the hydrophilic group of hydroxyl;

For Structure (2), in the materials of each layer and the addible masterbatch, the ranking of hydrophility of the hydrophilic group from high to low is carboxylate, carboxyl, hydroxyl, aldehyde, amide, acid anhydride and ester group;

The carrier is selected according to the like dissolves like principle:

For the polyethylene material of inner layer, the carrier of the addible masterbatch is polyethylene; The additive volume of the masterbatch to the materials of each layer is controlled within 0.3-15%

2015361915 31 May 2018 of the total mass of each layer; the hydrophility of the hydrophilic group in the addible masterbatch should be higher than or equal to the hydrophility of hydrophilic group in materials of each layer in Structure (2). Through addition of the addible masterbatch, the molar ratio of hydrophilic group vs. carbon atom in materials of each layer in Structure (2) is approaching uniform, namely biological activity of materials of each layer is approaching uniform, so the degrading speed of materials of each layer is approaching uniform.

[0008] The above described technical solution is explained as follows:

In above described technical solution, in the outer layer, the polypropylene is composed of isotactic polypropylene homopolymer or/and polypropylene random copolymer. The density of the polypropylene is 0.880-0.910 g/cm³.

[0009] In above described technical solution, and in the 1st bonding layer, the density of maleic anhydride grafted polypropylene copolymer is 0.880-0.910 g/cm³, and the maleic anhydride grafting ratio in mass percentage is 0.3%-10%.

[0010] In above described technical solution, the density of the ethylene-vinyl alcohol copolymer is 1.170-1.19 g/cm³, and the molar quantity of ethylene of ethylene-vinyl alcohol copolymer is 2648%; the density of polyamide is 1.12-1.14 g/cm³ and the polyamide is PA6 homopolymer or PA6, 66 copolymer or amorphous polyamide.

[0011] In above described technical solution, the density of the ethylene-vinyl alcohol copolymer is 1.170-1.19 g/cm³, and the molar quantity of ethylene of ethylene-vinyl alcohol copolymer is 2648%.

[0012] In above described technical solution, and in the 2nd bonding layer, the density of maleic anhydride grafted polyethylene copolymer is 0.910-0.950g/cm³, and the maleic anhydride grafting ratio in mass percentage is 0.3%-10%.

[0013] In above described technical solution, the density of polyethylene in the heat seal layer is 0.900-0.935g/cm³. The polyethylene contains polyethylene blends with density of 0.910-0.925 g/cm³. The polyethylene blends are composed of 50-99% polyethylene and 1-50% vinyl homopolymer, or 50-99% polyethylene and 1-50% vinyl copolymer in mass percentage. The vinyl copolymer is composed of ethylene and at least one of the C4-C12 α-olefin, C4-C12 cycloolefin, C4-C12 vinyl aromatic hydrocarbon and polar vinyl monomer. The density of the vinyl copolymer is 0.880-0.915 g/cm³.

[0014] in above described technical solution, the outer layer functions as the protection or displaying layer. When it functions as the protection layer, it plays the function of abrasion resistance and temperature resistance; when it functions as the display layer, it could be used to print and display the relevant information or transparently display the packaging content.

[0015] In above described technical solution, the multilayer film can be obtain the corresponding additional function by coating, metal evaporation and compounding.

[0016] Technical theory of this invention is: Materials composing multilayer film could be divided into two types which are hydrophilic material and hydrophobic material, among which hydrophilic

2015361915 31 May 2018 material contains hydrophilic group and is biodegradable in landfill or composting condition; while hydrophobic material contains no hydrophilic group, its biodegradability is gained through addition of hydrophilic group. The masterbatch is added pro rata to the materials of each layer, the carrier and activator fully dissolve with each other trough blending, and then the multilayer film is made through melt co-extrusion process. With the effect of high temperature and shear force, macromolecular chains are stably bound to each other through due to the force of hydrogen bond as well as curving and intertwine with each other to form the macromolecular aggregates, thereafter hydrophilic group of the activator is added and dispersed evenly into materials in each layer; in the biodegradable circumstances, the degradable activator is decomposed by microbes first, which causes break of its molecular chain, and the molecular chain of the carrier which is bound to the degradable activator via hydrogen bond breaks as well, which leads to the decomposition of the macromolecular aggregates, so that the purpose of biodegradation of plastic multilayer film is achieved.

[0017] The biodegradation process of this invention starts from special swelling. Carbon containing polymer is easier to be intruded by microbial bacterial because of the existence of bioactive compounds in plastics. Acidic substance is produced after bioactive compounds are devoured by the microbial bacteria, which causes the swelling of carbon containing polymer substrate. The molecular structure of carbon containing polymer will expand when the swelling is exposed to heat and moisture. When space is created in molecular structure of the polymer, the combination of bioactive compounds and masterbatch will attract microbiota which can metabolize and neutralize polymers. The microbiota will secrete acid liquid to break the long molecular chain of the polymers until the polymers are decomposed into inert humus, carbon dioxide and methane. This biodegradation process can be conducted in aerobic or anaerobic condition; and in condition with or without the light, heat and humidity. The key part of the technical solution of this invention is: The hydrophility of the hydrophilic group in the addible masterbatch should be higher than or equal to the hydrophility of hydrophilic group in materials of each layer in the multilayer film; through addition of the addible masterbatch, the molar ratio of hydrophilic group vs. carbon atom in materials of each layer in the multilayer film is approaching uniform, namely biological activity of materials of each layer is approaching uniform, so the degrading speed of materials of each layer is approaching uniform. When adding the biological carrier, addibal masterbatch with higher hydrophility than that of materials in the multilayer film is selected to be added to materials of each layer in the multilayer film to weaken the hydrophility of materials in the multilayer film. Through addition of the addible masterbatch, the molar ratio of hydrophilic group vs. carbon atom in materials of each layer in the multilayer film is approaching uniform, namely biological activity of materials of each layer is approaching uniform, so the degrading speed of materials of each layer in the multilayer film is approaching uniform.

[0018] The contribution of this invention is: for materials of each layer, approximate uniform biological activity are achieved by balancing the molar ratio of hydrophilic group vs. carbon atom of

2015361915 31 May 2018 materials of each layer, so that approximate uniform degrading speed of materials of each layer of the multilayer film is achieved. When the additive volume in mass percentage is within 0.3 -15% of the total mass of the layer, the product appearance, function, physical and mechanism performance will be retained before composted.

SPECIFIC EMBODIMENT [0019] With reference to the embodiments, the present invention will be described in detail: Embodiment 1: (The embodiment of the 1st technical solution)

A degradable EVOH high barrier multilayer film with structure as follows: PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE Structure (1)

In Structure (1), explicated from left to right:

PP represents the outer layer functioning as protection or display. Its material is polypropylene, and its monomer molecular formula is -[CH2-CH(CH3)]n-, and it does not contain hydrophilic groups; PP-TIE represents the 2nd bonding layer. Its material is maleic anhydride grafted polypropylene copolymer, which is formed by blending 95% polypropylene and 5% maleic anhydride in mass percentage. Its monomer molecular formula is -[CH2-CH(CH3)]n-[C4H2C>3]m, and the hydrophilic group contained in the maleic anhydride grafted polypropylene copolymer is acid anhydride —OCO-CO—;

PA/EVOH/PA represents the three-layer middle layer functioning as barrier layer. Its material is PA6 which is polyamide 6 and its monomer molecular formula is -[NH- (CH2) 5-CO]_n-, containing the hydrophilic group of amide group -CONH2- and EVOH represents the ethylene-vinyl alcohol copolymer, which is formed by 32% ethylene PE and 68% vinyl alcohol PVA and its monomer molecular formula is [CH2CH2]i[CH2CHOH]i.4, containing the hydrophilic group of hydroxyl —OH; PE-TIE represents the 2nd bonding layer. Its material is maleic anhydride grafted polyethylene copolymer, which is formed by blending 95% polyethylene and 5% maleic anhydride in mass percentage. Its monomer molecular formula is -[CH2-CH2]n-[C4H2O3]_m, and the hydrophilic group contained in the maleic anhydride grafted polyethylene copolymer is acid anhydride —OC-O-CO—; PE represents the inner layer functioning as heat-sealing layer. Its material is polyethylene, and its monomer molecular formula is -[CH2-CH2]n-, and it does not contain hydrophilic groups;

[0020] In the outer layer, the polypropylene is composed of isotactic polypropylene homopolymer or/and polypropylene random copolymer. The density of the polypropylene is 0.910 g/cm³. In the practical application, if the density is 0. 880g/cm³, 0.905 g/cm³ or other values within 0.8800.910g/cm³, same effect could be reached.

[0021] In the 1st bonding layer, the density of maleic anhydride grafted polypropylene copolymer is 0. 910 g/cm³. In the practical application, if polypropylene copolymer with density of 0.880g/cm³, 0.905g/cm³ or other values within 0.880-0.91 Og/cm³ is applied, same effect could be reached. And the maleic anhydride grafting ratio in mass percentage is 5% and in the practical application, if the maleic anhydride grafting ratio in mass percentage is 0.3%, 8%, 10% or other values within 0.310%, same effect could be reached.

2015361915 31 May 2018 [0022] In the barrier layer, in above mentioned barrier layer, density of the ethylene vinyl alcohol copolymer is 1.170g/cm³. In practical application, if ethylene vinyl alcohol copolymer with density of 1.190 g/cm³, 1.18 g/cm³ or other values within 1.170-1.190 g/cm³ is applied, same effect could be reached. The molar quantity percentage of ethylene in ethylene vinyl alcohol copolymer is 32%. In practical application, if the molar quantity percentage of ethylene in ethylene vinyl alcohol copolymer is 26%, 30%, 48% or other values within 26-48%, same effect could be reached; the density of polyamide PA6 is 1.13 g/cm³, and in practical application, if the polyamide with density of 1.126 g/cm³, 1.14 g/cm³ or other values within 1.12-1.14 g/cm³ is applied, same effect could be reached. The polyamide is PA6 homopolymer or PA6, 66 copolymer or amorphous polyamide. [0023] In the 2nd bonding layer, the density of maleic anhydride grafted polyethylene copolymer is 0.910 g/cm³. In the practical application, if polyethylene copolymer with density of 0.950g/cm³, 0.930g/cm³, 0.950g/cm³ or other values within 0.910-0.950g/cm³ is applied, same effect could be reached. And the maleic anhydride grafting ratio in mass percentage is 5% and in the practical application, if the maleic anhydride grafting ratio in mass percentage is 0.3%, 8%, 10% or other values within 0.3-10%, same effect could be reached.

[0024] In the heat seal layer, the density of polyethylene is 0.900-0.935g/cm³. The polyethylene contains polyethylene blends with density of 0.910-0.925 g/cm³. The polyethylene blends are composed of 50-99% polyethylene and 1-50% vinyl homopolymer, or 50-99% polyethylene and 150% vinyl copolymer in mass percentage. The vinyl copolymer is composed of ethylene and at least one of the C4-C12 α-olefin, C4-C12 cycloolefin, C4-C12 vinyl aromatic hydrocarbon and polar vinyl monomer. The density of the vinyl copolymer is 0.880-0.915 g/cm³.

[0025] The outer layer functions as the protection or displaying layer. When it functions as the protection layer, it plays the function of abrasion resistance and temperature resistance; when it functions as the display layer, it could be used to print and display the relevant information or transparently display the packaging content.

[0026] The multilayer film can obtain the corresponding additional function by coating, metal evaporation and compounding.

[0027] The materials in different layers of the multilayer film gain proximate uniform biodegradability through the introduction of biological carrier. The biological carrier is an addible masterbatch with biodegradability in landfill or composting condition. The materials of each layer are added pro rata with the masterbatch and melt co-extruded to be multilayer film.

[0028] The addible masterbatch is composed of carrier and activator. The activator is polymer containing hydrophilic group which is the effective component. The hydrophilic group is at least one of the carboxylate—COO; carboxy!—COOH, hydroxyl—OH, aldehyde—CHO, amide—CONH2, acid anhydride —OC-O-CO—and ester group—COOR.

[0029] For Structure (1), in the materials of each layer and the addible masterbatch, the ranking of hydrophility of the hydrophilic group from high to low is carboxylate—COO , carboxyl—COOH, hydroxyl—OH, aldehyde—CHO, amide—CONH2, acid anhydride—OC-O-CO— and ester group—

2015361915 31 May 2018

COOR.

[0030] The carrier is selected according to the like dissolves like principie:

For the ethylene-vinyi alcohol copolymer material of middle layer, the carrier of the addible masterbatch is polyethylene;

For the polyethylene material of inner layer, the carrier of the addible masterbatch is polyethylene. [0031] The additive volume of the masterbatch to the materials of each layer is controlled within 0.3-15% of the total mass of each layer; the hydrophility of the hydrophilic group in the addible masterbatch should be higher than or equal to the hydrophility of hydrophilic group in materials of each layer in Structure (1). Through addition of the addible masterbatch, the molar ratio of hydrophilic group vs. carbon atom in materials of each layer in Structure (1) is approaching uniform, namely biological activity of materials of each layer is approaching uniform, so the degrading speed of materials of each layer is approaching uniform.

[0032] For materials of each layer in the multilayer film in embodiment 1, the ranking of hydrophility of the hydrophilic group from high to low is hydroxyl>amide group>acid anhydride, namely for Structure (1), the ranking of hydrophility of materials of each layer from high to low is ethylene-vinyl alcohol copolymer EVOH (32%PE+68%PVA) > polyamide PA6 > PP-TIE (95%PP+5% maleic anhydride) > polyethylene PE=polypropylene PP.

[0033] To weaken the hydrophility of the hydrophilic group in the multilayer film, sodium alginate whose hydrophility is higher than that in EVOH (hydroxyl) in the multilayer film is selected to be the activator added.

[0034] Known that the monomer molecular formula of sodium alginate is (C5H7O4COONa)_n. According to this molecular formula, the hydrophilic group in sodium alginate is carboxylic acid sodium (—COONa), hydroxyl (—OH) and ester group (—COOR), among which, hydrophility of carboxyiic acid sodium (—COONa) is higher than that of hydroxyl (—OH) and the hydrophility of hydroxyl (—OH) in sodium alginate is equal to that of hydroxyl (—OH) in ethylene-vinyl alcohol copolymer EVOH, so sodium alginate polymer is selected as activator to be added to materials of each layer.

[0035] As hydrophility of carboxylic acid sodium in sodium alginate is higher than that of hydroxy! in ethylene-vinyl alcohol copolymer whose hydrophility is the highest in the multilayer film, sodium alginate leads the function in the biodegradation process, while the function of hydrophility of hydroxyl in EVOH, amide group in PA and acid anhydride in PP-TIE and PE-TIE in the multilayer

2015361915 31 May 2018 film is weakened. To simplify the statement, assume molar ratio of hydrophilic group vs. carbon atom is 0 in EVOH, PA, PP-TIE and PE-TIE in following calculation.

[0036] Calculation of molar ratio of hydrophilic group vs. carbon atom in sodium alginate is 2/3. [0037] Molar ratio of hydrophilic group vs. carbon atom in EVOH, PA6, PP-TIE, PE-TIE, PE and PP is 0.

[0038] As additive volume of addible masterbatch is small, and the carrier of addible masterbatch is the same as or similar to the polymer to which the masterbatch is added, to simplify the statement, the mass of addible masterbatch carrier is neglected in following calculation.

[0039] Following taking 1%, 2.2% sodium alginate additive volume in molar quantity as fiducial value to calculate sodium alginate additive volume in mass percentage in each layer of the multilayer film respectively:

A. 1% sodium alginate additive volume in molar quantity

Assuming materials of each layer in Structure (1) are blended with sodium alginate in the molar ratio of 99:1, calculate the molar ratio of hydrophilic group vs. carbon atom in each layer: 99/100*polypropylene _(n hydrophilic group, n carbon atom; +1/100*sodium alginate _in 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) +1/1 00*SOdium alginate tn hydrophilic group, n carbon atom) ⁼ 99/100*0+1/100*2/3=0.0067;

99/1 00*pOlyamide 6 (n hydrophilic group, n carbon atom; +1 /1 00*SOdiUIT7 alginate m hydrophilic group, n carbon atom; ⁼99/100*0+1/100*2/3=0.0067;

99/100*ethylene-vinyl alcohol copolymer _in hydrophilic group, n carbon atom; +1/100*sodium alginate _(nhydrophilic 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 /1 00*SOdlUm alginate tn hydrophilic group, π carbon atom; ⁼ 99/100*0+1/100*2/3=0.0067;

99/100*polyethylene (n hydrophilic graup_; n carbon atom) +1/100*sodium alginate (n hydrophilic group; n carbon atom; ~ 99/100*0+1/100*2/3=0.0067.

[0040] According to above calculation: after materials of each layer in Structure PP/PPTIE/PA/EVOH/PA/PE-TIE/PE are blended with sodium alginate in the molar ratio of 99:1, the molar ratio of hydrophilic group vs. carbon atom in each layer is the same, namely hydrophility of materials of each layer is approaching uniform, the degrading speed of materials of each layer is approaching uniform. The calculation of sodium alginate additive volume in mass is as follows: Assuming molar quantity of PP blended with sodium alginate is 1, mass of PP is mi-ι, mass of sodium alginate is mn mi-i=molar mass of PP (g/mol) *molar quantity percentage of PP (%)*molar quantity (mo!) =41.07*99%*1=40.66g_; m2-i=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate

2015361915 31 May 2018 (%)*molar quantity (mo!) = 198.12*1%*1=1.98g;

Assuming molar quantity of PP-TIE blended with sodium alginate is 1, mass of PP-TIE is 101-2, mass of sodium alginate is 102-2;

mi-2=molar mass of PP-TIE (g/mol) ‘molar quantity percentage of PP-TIE (%)*molar quantity (mol) =45.56 *99%*1=45.10g_; m2-2=molar mass of sodium alginate (g/mol) ‘molar quantity percentage of sodium alginate (%)*molar quantity (mol) =198.12‘1%*1=1.98g;

Assuming molar quantity of PA6 blended with sodium alginate is 1, mass of PA6 is 101-3, mass of sodium alginate is 1112-3;

mi-3=molar mass of PA6 (g/mol) ‘molar quantity percentage of PA6 (%)*molar quantity (mol) = 113.16 *99%*1=112.03g;

m2-3=molar mass of sodium alginate (g/mol) ‘molar quantity percentage of sodium alginate (%)*molar quantity (mol) = 198.12*1%*1=1.98g;

Assuming molar quantity of EVOH blended with sodium alginate is 1, mass of EVOH is 101-4, mass of sodium alginate is 102-4;

mi-4=molar mass of EVOH (g/mol) ‘molar quantity percentage of EVOH (%)*molar quantity (mol) =89.73 *99%*1=88.83g_; m2-4=molar mass of sodium alginate (g/mol) ‘molar quantity percentage of sodium alginate (%)*molar quantity (mol) = 198.l2*1%*1=1.98g;

Assuming molar quantity of PE-TIE blended with sodium alginate is 1, mass of PE-TIE is m-i-s, mass of sodium alginate is 102-5;

mi-5=molar mass of PE-TIE (g/mol) ‘molar quantity percentage of PE-TIE (%)*molar quantity (mol) =32.67*99%*1=32.34g;

m2-5=molar mass of sodium alginate (g/mol) ‘molar quantity percentage of sodium alginate (%)*molar quantity (mol) =198.12*1%*1=1.98g;

Assuming molar quantity of PE blended with sodium alginate is 1, mass of PE is 101-6, mass of sodium alginate is 102-5;

mi-6=molar mass of PE (g/mol) ‘molar quantity percentage of PE (%)*molar quantity (mol)

2015361915 31 May 2018 =28.05*99%*1=27.77g;

m2-6=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mol) =198.12*1 %*1=1.98g;

Take the outer layer PP for example, mass percentage of sodium alginate added to the PP layer is: 1.98/(40.66+1,98)*100%=4.64%; mass percentage of sodium alginate added to the other layers is calculated in the same way;

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

[0041]

B. 2.2% sodium alginate additive volume in molar quantity

Assuming materials of each layer in Structure (1) are blended with sodium alginate in the molar ratio of 97.8:2.2, calculate the molar ratio of hydrophilic group vs. carbon atom in each layer:

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: Π carbon atom ) +2.2/100*sodium alginate (n hydrophilic group: Π carbon atom ) = 97.8/100*0+2.2/100*2/3=0.0147; 97.8/100*poly©thyl©n© (n hydrophilic group: Π carbon atom) +2.2/1 00*SOdiUtTI 3iCjindt@ (n hydrophilic group: Π carbon atom ) = 97.8/100*0+2.2/100*2/3=0.0147.

[0042] According to above calculation: after materials of each layer in Structure PP/PPTIE/PA/EVOH/PA/PE-TIE/PE are blended with sodium alginate in the molar ratio of 97.8:2.2, the molar ratio of hydrophilic group vs. carbon atom in each layer is the same, namely hydrophility of materials of each layer is approaching uniform, the degrading speed of materials of each layer is approaching uniform. The calculation of sodium alginate additive volume in mass is as follows: Assuming molar quantity of PP blended with sodium alginate is 1, mass of PP is mid, mass of sodium alginate is rri2-i;

mi-i=molar mass of PP (g/mol) ‘molar quantity percentage of PP (%)*molar quantity (mol)

2015361915 31 May 2018 =41.07*97.8%*1=40.17g_; m2-i=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mol) = 198.12*2.2%*1=4.36g;

Assuming molar quantity of PP-TIE blended with sodium alginate is 1, mass of PP-TIE is m-i-₂, mass of sodium alginate is m₂-₂;

mi-2=molar mass of PP-TIE (g/mol) *molar quantity percentage of PP-TIE (%)*molar quantity (mol) =45.56 *97.8%*1 =44.56g_; m2-2=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mol) = 198.12*2.2%*1=4.36g;

Assuming molar quantity of PA6 blended with sodium alginate is 1, mass of PA6 is m-i-3, mass of sodium alginate is ITI2-3;

mi-3=molar mass of PAS (g/mol) *molar quantity percentage of PA6 (%)*molar quantity (mol) = 113.16 *97.8%*1=100.67g_; m2-3=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (moi) = 198.12*2.2%*1=4.36g;

Assuming molar quantity of EVOH blended with sodium alginate is 1, mass of EVOH is mu, mass of sodium alginate is ITI2-4;

mi-4=molar mass of EVOH (g/mol) *molar quantity percentage of EVOH (%)*molar quantity (mol) =89.73 *97.8%*1 =87.76g_; m₂-4=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (moi) = 198.12*2.2%*1=4.36g;

Assuming molar quantity of PE-TIE blended with sodium alginate is 1, mass of PE-TIE is m-i-s, mass of sodium alginate is ITI2-5:

mi-5=molar mass of PE-TIE (g/mol) *molar quantity percentage of PE-TIE (%)*molar quantity (mol) =32.67*97.8%*1=31.95g_; m₂-5=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mol) = 198.12*2.2%*1=4.36g_;

2015361915 31 May 2018

Assuming molar quantity of PE blended with sodium alginate is 1, mass of PE is m-i-6, mass of sodium alginate is rrD-ei mi-6=molar mass of PE (g/mol) *molar quantity percentage of PE (%)*molar quantity (mol) =28.05*97.8%*1=27.43g_; m2-6=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mo!) = 198.12*2.2%*1=4.36g;

Take the outer layer PP for example, mass percentage of sodium alginate added to the PP layer is: 4.36/(40.17+4.36)*100%=9.79%; mass percentage of sodium alginate added to the other layers is calculated in the same way;

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

[0043] When sodium alginate additive volume in mass percentage is within 0.3 -15% of the total mass of the layer, mechanism and barrier performance of the layer to which sodium alginate is added will not be affected.

[0044] To weaken the hydrophility of the hydrophilic group in the multilayer film, poiylactic acid whose hydrophility is higher than that in EVOH (hydroxyl) in the multilayer film is selected to be the activator added.

[0045] Known that the monomer molecular formula of poiylactic acid is [OCH(CH3)CO]n-OH. According to this molecular formula, the hydrophilic group in poiylactic acid is carboxyl (-COOH), hydroxyl (—OH) and ester group (—COOR), among which, hydrophility of carboxyl (-COOH) is higher than that of hydroxyl (—OH) and the hydrophility of hydroxyl (—OH) in poiylactic acid is higher than that of (—OH) in ethylene-vinyl alcohol copolymer EVOH, so poiylactic acid polymer is selected as activator to be added to materials of each layer.

[0046] As hydrophility of carboxyl in poiylactic acid is higher than that of hydroxyl in ethylene-vinyl alcohol copolymer whose hydrophility is the highest in the multilayer film, sodium alginate leads the function in the biodegradation process, while the function of hydrophility of hydroxyl in EVOH, amide group in PA and acid anhydride in PP-TIE and PE-TIE in the multilayer film is weakened. To simplify the statement, assume molar ratio of hydrophilic group vs. carbon atom is 0 in EVOH, PA, PP-TIE and PE-TIE in following calculation.

[0047] Calculation of molar ratio of hydrophilic group vs. carbon atom in poiylactic acid is 2/3.

[0048] Molar ratio of hydrophilic group vs. carbon atom in EVOH, PA6, PP-TIE, PE-TIE, PE and PP is 0.

[0049] As additive volume of addible masterbatch is small, and the carrier of addible masterbatch is the same as or similar to the polymer to which the masterbatch is added, to simplify the statement, the mass of addible masterbatch carrier is neglected in following calculation.

[0050] Following taking 2%, 0.6% poiylactic acid additive volume in molar quantity as fiducial value

2015361915 31 May 2018 to calculate polylactic acid additive volume in mass percentage in each layer of the multilayer film respectively:

A. 2% polylactic acid additive volume in molar quantity

Assuming materials of each layer in Structure (1) are blended with polylactic acid in the molar ratio of 98:2, calculate the molar ratio of hydrophilic group vs. carbon atom in each layer: 98/100*polypropylene (n hydrophilic group: ΓΪ carbon atom) +2/100*polylactic acid (n hydrophilic group: Π carbon atom) = 98/100*0+2/100*2/3=0.0333;

98/100* maleic anhydride grafted polypropylene copolymer (n hydrophilic group: Π carbon atom ) +2/100*polylactic acid (n hydrophilic group: Π carbon atom ) = 98/100*0+2/100*2/3=0.0133; 98/100*polyamide 6 (n hydrophilic group: Π carbon atom ) +2/100*polylactic acid (n hydrophilic group: Π 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: Π 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*polylactlC acid (n hydrophilic group: n carbon atom) = 98/100*0+2/100*2/3=0.0133;

[0051] According to above calculation: after materials of each layer in Structure PP/PPTIE/PA/EVOH/PA/PE-TIE/PE are blended with polylactic acid in the molar ratio of 98:2, the molar ratio of hydrophilic group vs. carbon atom in each layer is the same, namely hydrophility of materials of each layer is approaching uniform, the degrading speed of materials of each layer is approaching uniform. The calculation of polylactic acid additive volume in mass is as follows: Assuming molar quantity of PP blended with polylactic acid is 1, mass of PP is mi-i, mass of polylactic acid is m2-i;

mi-i=molar mass of PP (g/mol) *molar quantity percentage of PP (%)*molar quantity (mol) =41.07*98%*1=40.87g_; m2-i=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.14*2%*1=3.24g;

Assuming molar quantity of PP-TIE blended with polylactic acid is 1, mass of PP-TIE is mi-2, mass of polylactic acid is m2-2;

mi-2=molar mass of PP-TIE (g/mol) *molar quantity percentage of PP-TIE (%)*molar quantity (mol) =45.56 *98%*1=44.65g_; m2-2=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (moi)

2015361915 31 May 2018 = 162.14*2%*1=3.24g;

Assuming molar quantity of PA6 blended with polyiactic acid is 1, mass of PA6 is m-1-3, mass of polylactic acid is 1TI2-3;

mi-3=molar mass of PA6 (g/mol) *molar quantity percentage of PA6 (%)*molar quantity (mol) = 113.16*98%*1 = 110.90g;

m2-3=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.l4*2%*1=3.24g;

Assuming molar quantity of EVOH blended with polylactic acid is 1, mass of EVOH is m-1-4, mass of polylactic acid is rri2-4;

mi-4=molar mass of EVOH (g/mol) *molar quantity percentage of EVOH (%)*molar quantity (mol) =89.73 *98%*1=87.94g_; m2-4=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (mo!) = 162.14*2%*1=3.24g;

Assuming molar quantity of PE-TIE blended with polylactic acid is 1, mass of PE-TIE is m-1-5, mass of polylactic acid is m2-s;

mi-5=molar mass of PE-TIE (g/mol) *molar quantity percentage of PE-TIE (%)*molar quantity (mol) =32.67*98%*1=32.02g;

m2-5=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (moi) = 162.14*2%*1=3.24g;

Assuming molar quantity of PE blended with polylactic acid is 1, mass of PE is m-i-6, mass of polyiactic acid is m2-e;

mi-6=molar mass of PE (g/mol) *molar quantity percentage of PE (%)*molar quantity (moi) =28.05*98%*1=27.49g;

m2-6=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.14*2%*1=3.24g;

Take the outer layer PP for example, mass percentage of polylactic acid added to the PP layer is: 3.24/(40.87+3.24)*100%=7.35%; mass percentage of sodium alginate added to the other layers is calculated in the same way;

PP/PP-TIE/PA6/EVOH/PA6/PE-TIE/PE from left to right the mass percentage of polylactic acid

2015361915 31 May 2018 added to each layer is: 7.35/6.77/2.84/3.55/2.84/9.19/10.54.

[0052] B. 0.6% poiylactic acid additive volume in molar quantity

Assuming materials of each layer in Structure (1) are blended with poiylactic acid in the molar ratio of 99.4:0.6, calculate the molar ratio of hydrophilic group vs. carbon atom in each layer:

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

99.4/100* maleic anhydride grafted polypropylene copolymer (n hydrophilic group: Π carbon atom ) +0.6/100*polylactic acid (Π hydrophilic group: Π carbon atom ) = 99.4/100*0+0.6/100*2/3=0.0040; 99.4/100*pOly3mide 6 (n hydrophilic group: Π carbon atom) +0.6/100*pOly!3CtlC 3Cld (Π hydrophilic group: Π 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: Π carbon atom ) +0.6/100*polylactic acid (n hydrophilic group: Π carbon atom) = 99.4/100*0+0.6/100*2/3=0.0040; 99.4/100*polyethylene (n hydrophilic group: π carbon atom) +0.6/100*polyl3ctic acid (n hydrophilic group: Π carbon atom ) = 99.4/100*0+0.6/100*2/3=0.0040;

[0053] According to above calculation: after materials of each layer in Structure PP/PPTIE/PA/EVOH/PA/PE-TIE/PE are blended with poiylactic acid in the molar ratio of 99.4:0.6, the molar ratio of hydrophilic group vs. carbon atom in each layer is the same, namely hydrophility of materials of each layer is approaching uniform, the degrading speed of materials of each layer is approaching uniform. The calculation of poiylactic acid additive volume in mass is as follows: Assuming molar quantity of PP blended with poiylactic acid is 1, mass of PP is mi-ι, mass of poiylactic acid is 1T12-1;

mi-i=molar mass of PP (g/mol) *molar quantity percentage of PP (%)*molar quantity (mol) =41,07*99.4%*1=40.82g_;

ITI2-1=molar mass of poiylactic acid (g/mol) *molar quantity percentage of poiylactic acid (%)*molar quantity (mo!) = 162.14*0.6%*1=0.97g;

Assuming molar quantity of PP-TIE blended with poiylactic acid is 1, mass of PP-TIE is mi-2, mass of poiylactic acid is 012-2;

mi-2=molar mass of PP-TIE (g/mol) *molar quantity percentage of PP-TIE (%)*molar quantity (mol) =45.56 *99.4%*1=45.29g_; m2-2=molar mass of poiylactic acid (g/mol) *molar quantity percentage of poiylactic acid (%)*molar quantity (mol)

2015361915 31 May 2018 = 162.14*0.6%*1=0.97g;

mi-3=molar mass of PA6 (g/mol) *molar quantity percentage of PA6 (%)*molar quantity (mol) = 113.16*99.4%*1=112.48g;

m2-3=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.14*0.6%*1=0.97g;

mi-4=molar mass of EVOH (g/mol) *molar quantity percentage of EVOH (%)*molar quantity (mol) =89.73 *99.4%*1=89.19g_; m2-4=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (mo!) = 162.14*0.6%*1=0.97g;

mi-5=molar mass of PE-TIE (g/mol) *molar quantity percentage of PE-TIE (%)*molar quantity (mol) =32.67*99.4%*1=32.47g;

m2-5=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (moi) = 162.14*0.6%*1=0.97g;

Assuming molar quantity of PE blended with polylactic acid is 1, mass of PE is m-i-6, mass of polyiactic acid is rru-e;

mi-6=molar mass of PE (g/mol) *molar quantity percentage of PE (%)*molar quantity (mol) =28.05*99.4%*1=27.88g;

m2-6=molar mass of polyiactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.14*0.6%*1=0.97g;

Take the outer layer PP for example, mass percentage of polylactic acid added to the PP layer is: 0.97/(40.82+0.97)*100%=2.32%; mass percentage of sodium alginate added to the other layers is calculated in the same way;

2015361915 31 May 2018 added to each layer is: 2.32/2.10/0.86/1.08/0.86/2.90/3.36.

[0054] When polylactic acid additive volume in mass percentage is within 0.3 -15% of the total mass of the layer, mechanism and barrier performance of the layer to which sodium alginate is added will not be affected.

[0055] To improve the processing adaptability and dispersibility of the hydrophilic group, polymers of excellent compatibility could be selected for copolymerization. For example, copolymer obtained from copolymerization of polycaprolactone (PCL) and sodium alginate.

[0056] Known that the molecular formula of sodium alginate monomer is (C5H7O4COONa)_n. The molecular formula of polycaprolactone monomer is [CH2-(CH2)4-COO]_m. The monomer molecular formula of sodium alginate grafted polycaprolactone copolymer whose grafting ratio is 50-80% in mass percentage is [CH2-(CH2)4-COO]_m(C5H7O4COONa)_n. According to this molecular formula, the hydrophilic group in sodium alginate is carboxylic acid sodium (—COONa), hydroxyl (—OH) and ester group (—COOR), the hydrophilic group in polycaprolactone is ester group (—COOR). The hydrophility of hydroxyl carboxylic acid sodium (—COONa) is higher than that of hydroxyl (— OH) and hydrophility of hydroxyl (—OH) in sodium alginate is equal to that of hydroxyl (—OH) in ethylene-vinyl alcohol copolymer EVOH. In this embodiment, sodium alginate grafted polycaprolactone copolymer whose sodium alginate grafting ratio in mass percentage is 60% is selected and added to each layer of the multilayer material as activator.

[0057] As hydrophility of carboxylic acid sodium in copolymer is higher than that of hydroxyl in ethylene-vinyl alcohol copolymer whose hydrophility is the highest in the multilayer film, sodium alginate leads the function in the biodegradation process, while the function of hydrophility of hydroxyl in EVOH, amide group in PA and acid anhydride in PP-TIE and PE-TIE in the multilayer film is weakened. To simplify the statement, assume molar ratio of hydrophilic group vs. carbon atom is 0 in EVOH, PA, PP-TIE and PE-TIE in following calculation.

[0058] In sodium alginate grafted polycaprolactone copolymer, molar ratio of hydrophilic group vs. carbon atom in sodium alginate is 2/3; molar ratio of hydrophilic group vs. carbon atom in polycaprolactone is 1/7, so molar ratio of hydrophilic group vs. carbon atom in sodium alginate grafted polycaprolactone copolymer = 2/3*60%+1/7*40%=0.4571.

[0059] Molar ratio of hydrophilic group vs. carbon atom in EVOH, PA6, PP-TIE, PE-TIE, PE and PP is 0.

[0060] As additive volume of addible masterbatch is small, and the carrier of addible masterbatch is the same as or similar to the polymer to which the masterbatch is added, to simplify the statement, the mass of addible masterbatch carrier is neglected in following calculation.

[0061] Following taking 2% sodium alginate grafted polycaprolactone copolymer additive volume in molar quantity as fiducial value to calculate sodium alginate grafted polycaprolactone copolymer additive volume in mass percentage in each layer of the multilayer film respectively:

Assuming materials of each layer in Structure (1) are blended with sodium alginate grafted polycaprolactone copolymer in the molar ratio of 98:2, calculate the molar ratio of hydrophilic group

2015361915 31 May 2018 vs. carbon atom in each layer after sodium alginate grafted polycaprolactone copolymer is added: 98/100*polypropylene (n hydrophilic group, n carbon atom;+2/100*sodium alginate grafted polycaprolactone Copolymer in hydrophilic group, n carbon atom; = 98/1 00*0+2/1 00*45.71/1 00⁼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 atom, — 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 atoms +2/1 Q0*SOdium alginate grafted polycaprolactone copolymer :n hydrophilic group, n carbon atom; ~ 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 in hydrophilic group, n carbon atom; ⁼ 98/100*0+2/100*45.71/100=0.0091;

According to above calculation: after materials of each layer in Structure PP/PPTIE/PA/EVOH/PA/PE-TIE/PE are blended with sodium alginate grafted polycaprolactone copolymer in the molar ratio of 98:2, the molar ratio of hydrophilic group vs. carbon atom in each layer is the same, namely hydrophility of materials of each layer is approaching uniform, the degrading speed of materials of each layer is approaching uniform. The calculation of sodium alginate grafted polycaprolactone copolymer additive volume in mass is as follows:

Assuming molar quantity of PP blended with sodium alginate grafted polycaprolactone copolymer is 1, mass of PP is m-i-i, mass of sodium alginate grafted polycaprolactone copolymer is ΠΙ2-1; mi-i=molar mass of PP (g/mol) *molar quantity percentage of PP (%)*molar quantity (mol) =41.07*98%*1=40.25g_: m2-i=molar mass of sodium alginate grafted polycaprolactone copolymer (g/mol) *molar quantity percentage of sodium alginate grafted polycaprolactone copolymer (%)*molar quantity (mol) = 164.52*2%*1=3.29g;

Assuming molar quantity of PP-TIE blended with sodium alginate grafted polycaprolactone copolymer is 1, mass of PP-TIE is mi-2, mass of sodium alginate grafted polycaprolactone copolymer is ITI2-2;

mi-2=molar mass of PP-TIE (g/mol) *molar quantity percentage of PP-TIE (%)*molar quantity (mol) =45.56 *98%*1=44.65g_; m2-2=molar mass of sodium alginate grafted polycaprolactone copolymer (g/mol) *molar quantity percentage of sodium alginate grafted polycaprolactone copolymer (%)*molar quantity (mol)

2015361915 31 May 2018 = 164.52*2%*1=3.29g;

Assuming molar quantity of PA6 blended with sodium alginate grafted polycaprolactone copolymer is 1, mass of PA6 is mu, mass of sodium alginate grafted polycaprolactone copolymer is m₂-3; mi-3=molar mass of PA6 (g/mol) molar quantity percentage of PA6 (%)*molar quantity (mol) = 113.16 *98%*1=1120.90g_; m2-3=molar mass of sodium alginate grafted polycaprolactone copolymer (g/mol) molar quantity percentage of sodium alginate grafted polycaprolactone copolymer (%)*molar quantity (mol) = 164.52*2%*1=3.29g;

Assuming molar quantity of EVOH blended with sodium alginate grafted polycaprolactone copolymer is 1, mass of EVOH is mi-4, mass of sodium alginate grafted polycaprolactone copolymer is m₂-4;

mi-4=molar mass of EVOH (g/mol) molar quantity percentage of EVOH (%)*molar quantity (mol) =89.73 *98%*1=87.94g_; m₂-4=molar mass of sodium alginate grafted polycaprolactone copolymer (g/mol) molar quantity percentage of sodium alginate grafted polycaprolactone copolymer (%)*molar quantity (mol) = 164.52*2%*1=3.29g;

Assuming molar quantity of PE-TIE blended with sodium alginate grafted polycaprolactone copolymer is 1, mass of PE-TIE is mvs, mass of sodium alginate grafted polycaprolactone copolymer is m₂-s;

m-i-5=molar mass of PE-TIE (g/mol) molar quantity percentage of PE-TIE (%)*molar quantity (mol) =32.67*98%*1=32.02g;

m2-5=molar mass of sodium alginate grafted polycaprolactone copolymer (g/mol) molar quantity percentage of sodium alginate grafted polycaprolactone copolymer (%)*molar quantity (mol) = 164.52*2%*1=3.29g;

Assuming molar quantity of PE blended with sodium alginate grafted polycaprolactone copolymer is 1, mass of PE is mi-6, mass of sodium alginate grafted polycaprolactone copolymer is m₂-6; mi-6=molar mass of PE (g/mol) molar quantity percentage of PE (%)*molar quantity (mol) =28.05*98%*1=27.49g;

m₂-6=molar mass of sodium alginate grafted polycaprolactone copolymer (g/mol) molar quantity percentage of sodium alginate grafted polycaprolactone copolymer (%)*molar quantity (mol) = 164.52*2%*1=3.29g;

Take the outer layer PP for example, mass percentage of sodium alginate grafted polycaprolactone copolymer added to the PP layer is: 3.29/(40.25+3.29)*100%=7.56%; mass percentage of sodium

2015361915 31 May 2018 alginate grafted polycaprolactone copolymer added to the other layers is calculated in the same way;

PP/PP-TIE/PA6/EVOH/PA6/PE-TIE/PE from left to right, the mass percentage of sodium alginate grafted polycaprolactone copolymer added to each layer is:

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

[0062] When sodium alginate grafted polycaprolactone copolymer additive volume in mass percentage is within 0.3 -15% of the total mass of the layer, mechanism and barrier performance of the layer to which sodium alginate is added will not be affected.

[0063] Embodiment 2: (The embodiment of the 2nd technical solution)

A degradable EVOH high barrier multilayer film with structure as follows:

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

In Structure (2), explicated from left to right:

PP represents the outer layer functioning as protection or display. Its material is polypropylene, and its monomer molecular formula is -[CH2-CH(CH3)]_n-, and it does not contain hydrophilic groups; PP-TIE represents the 2nd bonding layer. Its material is maleic anhydride grafted polypropylene copolymer, which is formed by blending 95% polypropylene and 5% maleic anhydride in mass percentage. Its monomer molecular formula is -[CH2-CH(CH3)]n-[C4H2O3]_m, and the hydrophilic group contained in the maleic anhydride grafted polypropylene copolymer is acid anhydride —OCO-CO—;

EVOH represents the middle layer functioning as barrier layer. Its material is EVOH which is formed by 32% ethylene PE and 68% vinyl alcohol PVA and its monomer molecular formula is [CH2CH₂]i[CH₂CHOH]i.₄, containing the hydrophilic group of hydroxy! —OH;

PE-TIE represents the 2nd bonding layer. Its material is maleic anhydride grafted polyethylene copolymer, which is formed by blending 95% polyethylene and 5% maleic anhydride in mass percentage. Its monomer molecular formula is -[CH2-CH2]_n-[C4H2O3]m, and the hydrophilic group contained in the maleic anhydride grafted polyethylene copolymer is acid anhydride —OC-O-CO—; PE represents the inner layer functioning as heat-sealing layer. Its material is polyethylene, and its monomer molecular formula is -[CH2-CH2]n-, and it does not contain hydrophilic groups;

[0064] In the outer layer, the polypropylene is composed of isotactic polypropylene homopolymer or/and polypropylene random copolymer. The density of the polypropylene is 0.910 g/cm³. In the practical application, if the density is 0. 880g/cm³, 0.905 g/cm³ or other values within 0.8800.91 Og/cm³, same effect could be reached.

[0065] In the 1st bonding layer, the density of maleic anhydride grafted polypropylene copolymer is 0. 910 g/cm³. In the practical application, if polypropylene copolymer with density of 0.880g/cm³, 0.905g/cm³ or other values within 0.880-0.91 Og/cm³ is applied, same effect could be reached. And the maleic anhydride grafting ratio in mass percentage is 5% and in the practical application, if the maleic anhydride grafting ratio in mass percentage is 0.3%, 8%, 10% or other values within 0.310%, same effect could be reached.

2015361915 31 May 2018 [0066] In the barrier layer, in above mentioned barrier layer, density of the ethylene vinyl alcohol copolymer is 1.170g/cm³. In practical application, if ethylene vinyl alcohol copolymer with density of 1.190 g/cm³, 1.18 g/cm³ or other values within 1.170-1.190 g/cm³ is applied, same effect could be reached. The molar quantity percentage of ethylene in ethylene vinyl alcohol copolymer is 32%. In practical application, if the molar quantity percentage of ethylene in ethylene vinyl alcohol copolymer is 26%, 30%, 48% or other values within 26-48%, same effect could be reached.

[0067] In the 2nd bonding layer, the density of maleic anhydride grafted polyethylene copolymer is 0.910 g/cm³. In the practical application, if polyethylene copolymer with density of 0.950g/cm³, 0.930g/cm³, 0.950g/cm³ or other values within 0.910-0.950g/cm³ is applied, same effect could be reached. And the maleic anhydride grafting ratio in mass percentage is 5% and in the practical application, if the maleic anhydride grafting ratio in mass percentage is 0.3%, 8%, 10% or other values within 0.3-10%, same effect could be reached.

[0068] In the heat seal layer, the density of polyethylene is 0.900-0.935g/cm³. The polyethylene contains polyethylene blends with density of 0.910-0.925 g/cm³. The polyethylene blends are composed of 50-99% polyethylene and 1-50% vinyl homopolymer, or 50-99% polyethylene and 150% vinyl copolymer in mass percentage. The vinyl copolymer is composed of ethylene and at least one of the C4-C12 α-olefin, C4-C12 cycloolefin, C4-C12 vinyl aromatic hydrocarbon and polar vinyl monomer. The density of the vinyl copolymer is 0.880-0.915 g/cm³.

[0069] The outer layer functions as the protection or displaying layer. When it functions as the protection layer, it plays the function of abrasion resistance and temperature resistance; when it functions as the display layer, it could be used to print and display the relevant information or transparently display the packaging content.

[0070] The multilayer film can obtain the corresponding additional function by coating, metal evaporation and compounding.

[0071] The materials in different layers of the multilayer film gain proximate uniform biodegradability through the introduction of biological carrier. The biological carrier is an addible masterbatch with biodegradability in landfill or composting condition. The materials of each layer are added pro rata with the masterbatch and melt co-extruded to be multilayer film.

[0072] The addible masterbatch is composed of carrier and activator. The activator is polymer containing hydrophilic group which is the effective component. The hydrophilic group is at least one of the carboxylate—COO; carboxyl—COOH, hydroxyl—OH, aldehyde—CHO, amide—CONH2, acid anhydride —OC-O-CO—and ester group—COOR.

[0073] For Structure (2), in the materials of each layer and the addible masterbatch, the ranking of hydrophility of the hydrophilic group from high to low is carboxylate—COO; carboxyl—COOH, hydroxyl—OH, aldehyde—CHO, amide—CONH2, acid anhydride—OC-O-CO— and ester group— COOR.

[0074] The carrier is selected according to the like dissolves like principle:

For the polypropylene materia! of outer layer, the carrier of the addible masterbatch is at least one

2015361915 31 May 2018 of the polypropylene and polyethylene;

For the polyethylene material of inner layer, the carrier of the addible masterbatch is polyethylene. [0075] The additive volume of the masterbatch to the materials of each layer is controlled within 0.3-15% of the total mass of each layer; the hydrophility of the hydrophilic group in the addible masterbatch should be higher than or equai to the hydrophility of hydrophilic group in materials of each layer in Structure (2). Through addition of the addible masterbatch, the molar ratio of hydrophilic group vs. carbon atom in materials of each layer in Structure (2) is approaching uniform, namely biological activity of materials of each layer is approaching uniform, so the degrading speed of materials of each layer is approaching uniform.

[0076] For materials of each layer in the multilayer film in embodiment 2, the ranking of hydrophility of the hydrophilic group from high to low is hydroxyl>acid anhydride, namely for Structure (1), the ranking of hydrophility of materials of each layer from high to low is ethylene-vinyl alcohol copolymer EVOH (32%PE+68%PVA) > PP-TIE (95%PP+5% maleic anhydride) > polyethylene PE=polypropylene PP.

[0077] To weaken the hydrophility of the hydrophilic group in the multilayer film, sodium alginate whose hydrophility is higher than that in EVOH (hydroxyl) in the multilayer film is selected to be the activator added.

[0078] Known that the monomer molecular formula of sodium alginate is (C5H7O4COONa)_n. According to this molecular formula, the hydrophilic group in sodium alginate is carboxylic acid sodium (—COONa), hydroxyl (—OH) and ester group (—COOR), among which, hydrophility of carboxylic acid sodium (—COONa) is higher than that of hydroxyl (—OH) and the hydrophility of hydroxyl (—OH) in sodium alginate is equai to that of hydroxy! (—OH) in ethylene-vinyl alcohol copolymer EVOH, so sodium alginate polymer is selected as activator to be added to materials of each layer.

[0079] As hydrophility of carboxylic acid sodium in sodium alginate is higher than that of hydroxy! in ethylene-vinyl alcohol copolymer whose hydrophility is the highest in the multilayer film, sodium alginate leads the function in the biodegradation process, while the function of hydrophility of hydroxyl in EVOH and acid anhydride in PP-TIE and PE-TIE in the multilayer film is weakened. To simplify the statement, assume molar ratio of hydrophilic group vs. carbon atom is 0 in EVOH, PPTIE and PE-TIE in following calculation.

[0080] Calculation of molar ratio of hydrophilic group vs. carbon atom in sodium alginate is 2/3. [0081] Molar ratio of hydrophilic group vs. carbon atom in EVOH, PP-TIE, PE-TIE, PE and PP is 0.

2015361915 31 May 2018 [0082] As additive volume of addible masterbatch is small, and the carrier of addible masterbatch is the same as or similar to the polymer to which the masterbatch is added, to simplify the statement, the mass of addible masterbatch carrier is neglected in following calculation.

[0083] Following taking 1%^ 2.2% sodium alginate additive volume in molar quantity as fiducial value to calculate sodium alginate additive volume in mass percentage in each layer of the multilayer film respectively:

A. 1% sodium alginate additive volume in molar quantity

Assuming materials of each layer in Structure (1) are blended with sodium alginate in the molar ratio of 99:1, calculate the molar ratio of hydrophilic group vs. carbon atom in each layer:

99/100*polypropylene in hydrophilic group, n carbon atom; +1/100*sodium alginate m 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;; ^1/1 00*SOdlUm elcjinste <n hydrophilic group_: n carbon atom) ⁼ 99/1 00*QM/1 00*2/3⁼0.0067; 99/100*ethylene-vinyl alcohol copolymer,_n hydrophilic group, n carbon atom; +1/100*sodium alginate <_nhydrophilic 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*SOdlUm 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.

[0084] According to above calculation: after materials of each layer in Structure PP/PPTIE/EVOH/PE-TIE/PE are blended with sodium alginate in the molar ratio of 99:1, the molar ratio of hydrophilic group vs. carbon atom in each layer is the same, namely hydrophility of materials of each layer is approaching uniform, the degrading speed of materials of each layer is approaching uniform. The calculation of sodium alginate additive volume in mass is as follows:

Assuming molar quantity of PP blended with sodium alginate is 1, mass of PP is mn, mass of sodium alginate is 1T12-1;

mi-i=molar mass of PP (g/mol) *molar quantity percentage of PP (%)*molar quantity (mol) =41.07*99%*1=40.66g_; m2-i=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mol) = 198.12*1%*1=1.98g;

Assuming molar quantity of PP-TIE blended with sodium alginate is 1, mass of PP-TIE is m-i-2, mass of sodium alginate is m2-2;

mi-2=molar mass of PP-TIE (g/mol) *molar quantity percentage of PP-TIE (%)*molar quantity (mol) =45.56 *99%*1=45.10g_; m2-2=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate

2015361915 31 May 2018 (%)*molar quantity (mo!) = 198.12*1%*1=1.98g;

Assuming molar quantity of EVOH blended with sodium alginate is 1, mass of EVOH is m-1-3, mass of sodium alginate is 012-3;

mi-3=molar mass of EVOH (g/mol) *molar quantity percentage of EVOH (%)*molar quantity (mol) =89.73 *99%*1=88.83g_; m2-3=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mo!) =198.12*1%*1=1.98g;

Assuming molar quantity of PE-TIE blended with sodium alginate is 1, mass of PE-TIE is m-i-4, mass of sodium alginate is m2-4;

mi-4=molar mass of PE-TIE (g/mol) *molar quantity percentage of PE-TIE (%)*molar quantity (mol) =32.67*99%*1=32.34g;

m2-4=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mol) = 198.12*1%*1=1.98g;

Assuming molar quantity of PE blended with sodium alginate is 1, mass of PE is rru-5, mass of sodium alginate is ΠΊ2-5;

mi-5=molar mass of PE (g/mol) *molar quantity percentage of PE (%)*molar quantity (mol) =28.05*99%*1 =27.77g;

m2-5=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mol) =198.12*1%*1=1.98g;

PP/PP-TIE/ EVOH/ PE-TIE/PE from left to right, the mass percentage of sodium alginate added to each layer is:

4.64/4.21/2.18/5.77/6.66.

[0085] B. 2.2% sodium alginate additive volume in molar quantity

Assuming materials of each layer in Structure (2) are blended with sodium alginate in the molar ratio of 97.8:2.2, calculate the molar ratio of hydrophilic group vs. carbon atom in each layer:

97.8/100*polypropylene (n hydrophilic group: n carbon atom) +2.2/100*sodium alginate (n

2015361915 31 May 2018 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) =
97.8/1000+2.2/1002/3=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) =
97.8/1000+2.2/1002/3=0.0147;
97.8/100* maleic anhydride grafted	polyethylene	copolymer (n	hydrophiiic group:	n carbon

atom) +2.2/1 00*SOdlUm 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.

[0086] According to above calculation: after materials of each layer in Structure PP/PPTIE/EVOH/PE-TIE/PE are blended with sodium alginate in the molar ratio of 97.8:2.2, the molar ratio of hydrophilic group vs. carbon atom in each layer is the same, namely hydrophility of materials of each layer is approaching uniform, the degrading speed of materials of each layer is approaching uniform. The calculation of sodium alginate additive volume in mass is as follows: Assuming molar quantity of PP blended with sodium alginate is 1, mass of PP is m-1-1, mass of sodium alginate is ITI2-1;

mi-i=molar mass of PP (g/mol) ‘molar quantity percentage of PP (%)*molar quantity (mo!) =41.07*97.8%*1=40.17g_; m2-i=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mol) = 198.12*2.2%*1=4.36g;

Assuming molar quantity of PP-TIE blended with sodium alginate is 1, mass of PP-TIE is mi-2, mass of sodium alginate is rri2-2;

mi-2=molar mass of PP-TIE (g/mol) *molar quantity percentage of PP-TIE (%)*molar quantity (mol) =45.56 *97.8%*1=44.56g_; m2-2=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mol) = 198.12*2.2%*1=4.36g_;

Assuming molar quantity of EVOH blended with sodium alginate is 1, mass of EVOH is m-i-3, mass of sodium alginate is ΠΊ2-3;

mi-3=molar mass of EVOH (g/mol) ‘molar quantity percentage of EVOH (%)*molar quantity (mol) =89.73 *97.8%*1=87.76g_;

2015361915 31 May 2018 m2-3=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mol) = 198.12*2.2%*1=4.36g_;

Assuming molar quantity of PE-TIE blended with sodium alginate is 1, mass of PE-TIE is m-i-4, mass of sodium alginate is 1112-4;

mi-4=molar mass of PE-TIE (g/mol) *molar quantity percentage of PE-TIE (%)*molar quantity (mol) =32.67*97.8%*1=31.95g_; m2-4=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (mo!) = 198.12*2.2%*1=4.36g_;

Assuming molar quantity of PE blended with sodium alginate is 1, mass of PE is m-i-5, mass of sodium alginate is ITI2-5;

mi-5=molar mass of PE (g/mol) *molar quantity percentage of PE (%)*molar quantity (mol) =28.05*97.8%*1=27.43g_; m2-5=molar mass of sodium alginate (g/mol) *molar quantity percentage of sodium alginate (%)*molar quantity (moi) = 198.12*2.2%*1=4.36g;

9.79/8.91/4.73/12.01/13.72.

[0087] When sodium alginate additive volume in mass percentage is within 0.3 -15% of the total mass of the layer, mechanism and barrier performance of the layer to which sodium alginate is added will not be affected.

[0088] To weaken the hydrophility of the hydrophilic group in the multilayer film, polylactic acid whose hydrophility is higher than that in EVOH (hydroxyl) in the multilayer film is selected to be the activator added.

[0089] Known that the monomer molecular formula of polylactic acid is [OCH(CH3 )CO]n-OH. According to this molecular formula, the hydrophilic group in polylactic acid is carboxyl (-COOH), hydroxyl (—OH) and ester group (—COOR), among which, hydrophility of carboxyl (-COOH) is higher than that of hydroxyl (—OH) and the hydrophility of hydroxyl (—OH) in polylactic acid is higher than that of (—OH) in ethylene-vinyl alcohol copolymer EVOH, so polylactic acid polymer is

2015361915 31 May 2018 selected as activator to be added to materials of each layer.

[0090] As hydrophility of carboxyl in polylactic acid is higher than that of hydroxyl in ethylene-vinyl alcohol copolymer whose hydrophility is the highest in the multilayer film, sodium alginate leads the function in the biodegradation process, while the function of hydrophility of hydroxyl in EVOH and acid anhydride in PP-TIE and PE-TIE in the multilayer film is weakened. To simplify the statement, assume molar ratio of hydrophilic group vs. carbon atom is 0 in EVOH, PP-TIE and PE-TIE in following calculation.

[0091] Calculation of molar ratio of hydrophilic group vs. carbon atom in polylactic acid is 2/3.

[0092] Molar ratio of hydrophilic group vs. carbon atom in EVOH, PP-TIE, PE-TIE, PE and PP is 0. [0093] As additive volume of addible masterbatch is small, and the carrier of addible masterbatch is the same as or similar to the polymer to which the masterbatch is added, to simplify the statement, the mass of addible masterbatch carrier is neglected in following calculation.

[0094] Following taking 2%, 0.6% polylactic acid additive volume in molar quantity as fiducial value to calculate polylactic acid additive volume in mass percentage in each layer of the multilayer film respectively:

A. 2% polylactic acid additive volume in molar quantity

Assuming materials of each layer in Structure (2) are blended with polylactic acid in the molar ratio of 98:2, calcuiate the molar ratio of hydrophilic group vs. carbon atom in each layer:

98/1 00*polypropylene (n hydrophilic group: Π carbon atom) +2/1 00*polyl3CtiC acid (n hydrophilic group: Π carbon atom) = 98/100*0+2/100*2/3=0.0133;

98/100* maleic anhydride grafted polypropylene copolymer (n hydrophilic group: Π carbon atom) +2/1 00*polylaCtlC acid (n hydrophilic group: ncarbonatom) = 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: ncarbonatom) = 98/100*0+2/100*2/3=0.0133;

98/100* maleic anhydride grafted polyethylene copolymer (n hydrophilic group: Π carbon atom) +2/1 00*polylaCtlC acid (n hydrophilic group: ncarbonatom) = 98/100*0+2/100*2/3=0.0133;

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

[0095] According to above calculation: after materials of each layer in Structure PP/PPTIE/EVOH/PE-TIE/PE are blended with polylactic acid in the molar ratio of 98:2, the molar ratio of hydrophilic group vs. carbon atom in each layer is the same, namely hydrophility of materials of each layer is approaching uniform, the degrading speed of materials of each layer is approaching uniform. The calculation of polylactic acid additive volume in mass is as follows:

Assuming molar quantity of PP blended with polylactic acid is 1, mass of PP is mn, mass of polylactic acid is 1T12-1;

mi-i=molar mass of PP (g/mol) *molar quantity percentage of PP (%)*molar quantity (mo!) =41.07*98%*1=40.87g_:

2015361915 31 May 2018 m2-i=molar mass of poly lactic acid (g/mol) ‘molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.14*2%*1=3.24g;

Assuming molar quantity of PP-TIE blended with polylactic acid is 1, mass of PP-TIE is 101-2, mass of polylactic acid is ΠΊ2-2;

mi-2=molar mass of PP-TIE (g/mol) ‘molar quantity percentage of PP-TIE (%)*molar quantity (mol) =45.56 *98%*1=44.65g_; m2-2=molar mass of polylactic acid (g/mol) ‘molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.14*2%‘1=3.24g;

Assuming molar quantity of EVOH blended with polylactic acid is 1, mass of EVOH is mi.3, mass of polylactic acid is 102-3;

mi-3=molar mass of EVOH (g/mol) ‘molar quantity percentage of EVOH (%)*molar quantity (mol) =89.73 *98%*1=87.94g_; m2-3=molar mass of polylactic acid (g/mol) ‘molar quantity percentage of polylactic acid (%)*molar quantity (moi) = 162.14*2%*1=3.24g;

Assuming molar quantity of PE-TIE blended with polylactic acid is 1, mass of PE-TIE is 101-4, mass of polylactic acid is Γ02-4;

mi-4=molar mass of PE-TIE (g/mol) ‘molar quantity percentage of PE-TIE (%)*molar quantity (mol) =32.67*98%‘1=32.02g;

m2-4=molar mass of polylactic acid (g/mol) ‘molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.14*2%*1=3.24g;

Assuming molar quantity of PE blended with polylactic acid is 1, mass of PE is mi-5, mass of polylactic acid is m2-s;

mi-5=molar mass of PE (g/mol) ‘molar quantity percentage of PE (%)*molar quantity (mol) =28.05*98%*1 =27.49g;

m2-5=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.14*2%‘1=3.24g;

Take the outer layer PP for example, mass percentage of polylactic acid added to the PP layer is: 3.24/(40.87+3.24)*100%=7.35%; mass percentage of sodium alginate added to the other layers is

2015361915 31 May 2018 calculated in the same way;

PP/PP-TIE/ EVOH/ PE-TIE/PE from left to right, the mass percentage of polylactic acid added to each layer is:

7.35/6.77/3.55/9.19/10.54.

[0096] B. 0.6% polylactic acid additive volume in molar quantity

Assuming materials of each layer in Structure (2) are blended with polylactic acid in the molar ratio of 99.4:0.6, calculate the molar ratio of hydrophilic group vs. carbon atom in each layer:

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

99.4/100* maleic anhydride grafted polypropylene copolymer (n hydrophilic group: Π carbon atom) +0.6/1 00*polylactic acid (n hydrophilic group: Π carbon atom) — 99.4/100*0+0.6/100*2/3—0.0040; 99.4/100*ethyiene-vinyi 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 copoiymer (n hydrophilic group: Π carbon atom ) +0.6/100*polylactic acid (n hydrophilic group: Π 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*poiyl3ctic acid (n hydrophilic group: H carbon atom ) = 99.4/100*0+0.6/100*2/3=0.0040;

[0097] According to above calculation: after materials of each layer in Structure PP/PPTIE/EVOH/PE-TIE/PE are blended with polylactic acid in the molar ratio of 99.4:0.6, the molar ratio of hydrophilic group vs. carbon atom in each layer is the same, namely hydrophility of materials of each layer is approaching uniform, the degrading speed of materials of each layer is approaching uniform. The calculation of polylactic acid additive volume in mass is as follows:

Assuming molar quantity of PP blended with polylactic acid is 1, mass of PP is m-M, mass of polylactic acid is m₂-i;

mi-i=molar mass of PP (g/mol) *molar quantity percentage of PP (%)*molar quantity (mol) =41.07*99.4%*1=40.82g_; m₂-i=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.14*0.6%*1=0.97g;

Assuming molar quantity of PP-TIE blended with polylactic acid is 1, mass of PP-TIE is mi-₂, mass of polyiactic acid is m₂-₂;

mi-₂=molar mass of PP-TIE (g/mol) *molar quantity percentage of PP-TIE (%)*molar quantity (mol) =45.56 *99.4%*1=45.29g_; m₂-₂=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar

2015361915 31 May 2018 quantity (moi) = 162.14*0.6%*1=0.97g;

Assuming molar quantity of EVOH blended with polylactic acid is 1, mass of EVOH is m-1-3, mass of polylactic acid is m₂-3;

mi-3=molar mass of EVOH (g/mol) *molar quantity percentage of EVOH (%)*molar quantity (mol) =89.73 *99.4%*1=89.19g;

Assuming molar quantity of PE-TIE blended with polylactic acid is 1, mass of PE-TIE is mi-4, mass of polylactic acid is m^;

mi-4=molar mass of PE-TIE (g/mol) *molar quantity percentage of PE-TIE (%)*molar quantity (mol) =32.67*99.4%*1=32.47g;

m2-4=molar mass of polylactic acid (g/mol) *molar quantity percentage of polylactic acid (%)*molar quantity (mo!) = 162.14*0.6%*1=0.97g;

Assuming molar quantity of PE blended with polylactic acid is 1, mass of PE is mrs, mass of polylactic acid is ITI2-5;

mi-5=molar mass of PE (g/mol) *molar quantity percentage of PE (%)*molar quantity (mol) =28.05*99.4%*1=27.88g;

m₂-5=molar mass of polylactic acid (g/mol) ‘molar quantity percentage of polylactic acid (%)*molar quantity (mol) = 162.14*0.6%*1=0.97g;

Take the outer layer PP for example, mass percentage of polylactic acid added to the PP layer is: 0.97/(40.82+0.97/100%=2.32%; mass percentage of sodium alginate added to the other layers is calculated in the same way;

2.32/2.10/1.08/2.90/3.36.

[0098] When polylactic acid additive volume in mass percentage is within 0.3 -15% of the total mass of the layer, mechanism and barrier performance of the layer to which sodium alginate is added will not be affected.

[0099] To improve the processing adaptability and dispersibility of the hydrophilic group, polymers of excellent compatibility could be selected for copolymerization. For example, copolymer obtained

2015361915 31 May 2018 from copolymerization of polycaprolactone (PCL) and sodium alginate.

[0100] Known that the molecular formula of sodium alginate monomer is (CsH7O4COONa)n. The molecular formula of polycaprolactone monomer is [CH2-(CH2)4-COO]_m. The monomer molecular formula of sodium alginate grafted polycaprolactone copolymer whose grafting ratio is 50-80% in mass percentage is [CH2-(CH2)4-COO]_m(C5H7O4COONa)_n. According to this molecular formula, the hydrophilic group in sodium alginate is carboxylic acid sodium (—COONa), hydroxyl (—OH) and ester group (—COOR), the hydrophilic group in polycaprolactone is ester group (—COOR). The hydrophility of hydroxyl carboxylic acid sodium (—COONa) is higher than that of hydroxyl (— OH) and hydrophility of hydroxyl (—OH) in sodium alginate is equal to that of hydroxyl (—OH) in ethylene-vinyl alcohol copolymer EVOH. In this embodiment, sodium alginate grafted polycaprolactone copolymer whose sodium alginate grafting ratio in mass percentage is 60% is selected and added to each layer of the multilayer material as activator.

[0101] As hydrophility of carboxylic acid sodium in copolymer is higher than that of hydroxyl in ethylene-vinyl alcohol copolymer whose hydrophility is the highest in the multilayer film, sodium alginate leads the function in the biodegradation process, while the function of hydrophility of hydroxyl in EVOH and acid anhydride in PP-TIE and PE-TIE in the multilayer film is weakened. To simplify the statement, assume molar ratio of hydrophilic group vs. carbon atom is 0 in EVOH, PPTIE and PE-TIE in following calculation.

[0102] In sodium alginate grafted polycaprolactone copolymer, molar ratio of hydrophilic group vs. carbon atom in sodium alginate is 2/3; molar ratio of hydrophilic group vs. carbon atom in polycaprolactone is 1/7, so molar ratio of hydrophilic group vs. carbon atom in sodium alginate grafted polycaprolactone copolymer = 2/3*60%+1/7*40%=0.4571.

[0103] Molar ratio of hydrophilic group vs. carbon atom in EVOH, PP-TIE, PE-TIE, PE and PP is 0. [0104] As additive volume of addible masterbatch is small, and the carrier of addible masterbatch is the same as or similar to the polymer to which the masterbatch is added, to simplify the statement, the mass of addible masterbatch carrier is neglected in following calculation.

[0105] Following taking 2% sodium alginate grafted polycaprolactone copolymer additive volume in molar quantity as fiducial value to calculate sodium alginate grafted polycaprolactone copolymer additive volume in mass percentage in each layer of the multilayer film respectively:

Assuming materials of each layer in Structure (2) are blended with sodium alginate grafted polycaprolactone copolymer in the molar ratio of 98:2, calculate the molar ratio of hydrophilic group vs. carbon atom in each layer after sodium alginate grafted polycaprolactone copolymer is added: 98/100*polypropylene (n hydrophilic group, n carbon atom)+2/100*sodium alginate grafted polycaprolactone Copolymer cn hydrophilic group, n carbon atom; ⁼ 98/1 00*0+2/1 00*45.71/1 00=0.0091 ;

98/100* maleic anhydride grafted polypropylene copolymer (n hydrophilic group, n carbon atom,+2/100*sodium alginate grafted polycaprolactone copolymer in hydrophilic group, n carbon atom) — 98/100*0+2/100*45.71/100=0.0091_;

2015361915 31 May 2018

98/100*ethylene-vinyl alcohol copolymer _!Π hydrophilic group, n carton atoms+2/100*sodium alginate grafted polycaprolactone copolymer ,n hydrophilic group, n carbon atom s = 98/100*0+2/100*45.71/100=0.0091:

98/100* maleic anhydride grafted polyethylene copolymer _cn hydrophilic group, n carbon atoms +2/1 00*SOdlUm alginate grafted polycaprolactone copolymer rn hydrophilic group, n carbon atoms ~ 98/100*0+2/100*45.71/100=0.0091_;

98/100*polyethylene ,_n hydrophilic group, n carbon atoms+2/100*sodium alginate grafted polycaprolactone Copolymer ;n hydrophilic group, n carbon atoms ⁼ 98/100*0+2/100*45.71/100=0.0091;

According to above calculation: after materials of each layer in Structure PP/PP-TIE/EVOH/PETIE/PE are blended with sodium alginate grafted polycaprolactone copolymer in the molar ratio of 98:2, the molar ratio of hydrophilic group vs. carbon atom in each layer is the same, namely hydrophility of materials of each layer is approaching uniform, the degrading speed of materials of each layer is approaching uniform. The calculation of sodium alginate grafted polycaprolactone copolymer additive volume in mass is as follows:

Assuming molar quantity of PP blended with sodium alginate grafted polycaprolactone copolymer is 1, mass of PP is m-i-i, mass of sodium alginate grafted polycaprolactone copolymer is ιτυ-ι; mi-i=molar mass of PP (g/mol) *molar quantity percentage of PP (%)*molar quantity (mol) =41.07*98%*1=40.25g_; m2-i=molar mass of sodium alginate grafted polycaprolactone copolymer (g/mol) *molar quantity percentage of sodium alginate grafted polycaprolactone copolymer (%)*molar quantity (mol) = 164.52*2%*1=3.29g;

Assuming molar quantity of PP-TIE blended with sodium alginate grafted polycaprolactone copolymer is 1, mass of PP-TIE is m-i-2, mass of sodium alginate grafted polycaprolactone copolymer is 012-2;

mi-2=molar mass of PP-TIE (g/mol) *molar quantity percentage of PP-TIE (%)*molar quantity (mol) =45.56 *98%*1=44.65g_; m2-2=molar mass of sodium alginate grafted polycaprolactone copolymer (g/mol) *molar quantity percentage of sodium alginate grafted polycaprolactone copolymer (%)*molar quantity (mol) = 164.52*2%*1=3.29g;

Assuming molar quantity of EVOH blended with sodium alginate grafted polycaprolactone copolymer is 1, mass of EVOH is m-1-3, mass of sodium alginate grafted polycaprolactone copolymer is 1112-3;

mi-3=molar mass of EVOH (g/mol) *molar quantity percentage of EVOH (%)*molar quantity (mol) =89.73 *98%*1=87.94g_; m2-3=molar mass of sodium alginate grafted polycaprolactone copolymer (g/mol) *molar quantity percentage of sodium alginate grafted polycaprolactone copolymer (%)*molar quantity (mol)

2015361915 31 May 2018 = 164.52*2%*1=3.29g;

Assuming molar quantity of PE-TIE blended with sodium alginate grafted poiycaproiactone copolymer is 1, mass of PE-TIE is m-M, mass of sodium alginate grafted poiycaproiactone copolymer is ITI2-4;

mi-4=molar mass of PE-TIE (g/mol) *molar quantity percentage of PE-TIE (%)*molar quantity (mol) =32.67*98%*1 =32.02g;

m2-4=molar mass of sodium alginate grafted poiycaproiactone copolymer (g/mol) *molar quantity percentage of sodium alginate grafted poiycaproiactone copolymer (%)*molar quantity (mol) = 164.52*2%*1=3.29g;

Assuming molar quantity of PE blended with sodium alginate grafted poiycaproiactone copolymer is 1, mass of PE is m-i-s, mass of sodium alginate grafted poiycaproiactone copolymer is ΙΎΙ2-5; mi-5=molar mass of PE (g/mol) *molar quantity percentage of PE (%)*molar quantity (mol) =28.05*98%*1=27.49g;

m₂-5=molar mass of sodium alginate grafted poiycaproiactone copolymer (g/mol) *molar quantity percentage of sodium alginate grafted poiycaproiactone copolymer (%)*molar quantity (mol) = 164.52*2%*1=3.29g;

Take the outer layer PP for example, mass percentage of sodium alginate grafted poiycaproiactone copolymer added to the PP layer is: 3.29/(40.25+3.29)*100%=7.56%; mass percentage of sodium alginate grafted poiycaproiactone copolymer added to the other layers is calculated in the same way;

PP/PP-TIE/EVOH/PE-TIE/PE from left to right, the mass percentage of sodium alginate grafted poiycaproiactone copolymer added to each layer is:

7.56/6.86/3.61/9.32/10.69.

[0106] When sodium alginate grafted poiycaproiactone copolymer additive volume in mass percentage is within 0.3 -15% of the total mass of the layer, mechanism and barrier performance of the layer to which sodium alginate is added will not be affected.

[0107] In above embodiment, sodium aiginate, polylactic acid and sodium alginate grafted copolymer are selected as activator, which is supported by above embodiment directly. However, in this invention, besides above mentioned activators, other polymer containing hydrophiiic groups of carboxylate, carboxyl, hydroxyl, aldehyde, amide, acid anhydride and ester group could be selecte, such as poiycaproiactone, poiycaproiactone polyol, polysaccharide polymers, algae based polymer etc. Enlightened by the embodiment of the invention, technicians in this field can understand and foresee the specific polymer containing these groups, therefore addibie masterbatch stated in this invention is not limited to polymers disclosed in the embodiment.

[0108] In above embodiment, only several examples in numerical value are given for the additive

2015361915 31 May 2018 volume of the addible masterbatch. Enlightened by the examples, it is easy for technicians in this field to think of all additive volume of addible masterbatch within 0.3-15% can achieve the aim and effect of this invention.

[0109] in above embodiment, for easier implementation (suitable for melt extrusion), limitation is set for density copolymerization ratio and blending ratio of materials of each layer, and illustrated in examples. However, these requirements are not compulsory for this invention so cannot be regarded as basis limiting the protection scope of this invention, in other words, all parameter setting suitable for melt extrusion out of above limitation can execute this invention and reach the corresponding technical effects.

[0110] In this invention, though the structure formula of the multilayer film is given, material in the same layer of the formula can be composed of one or several layers of the same material, for example, in the structure formula PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE, apparently the formula is a 7-layer structure, but material in any layer can be composed with two or more layers of the same material, e.g. PE can be composed of two layers so the multilayer film will be composed of 8 layers accordingly, and so on.

[0111] It should be noted that the above described embodiments are only for illustration of technical concept and characteristics of present invention with purpose of making those skilled in the art understand the present invention. The technicians in this art could make change on the basis of the above embodiment, such as choosing different densities of materials, choosing different activators, etc, and thus these embodiments shall not limit the protection range of present invention. The equivalent changes or modifications according to spiritual essence of present invention shall fall in the protection scope of present invention.

2015361915 31 May 2018

Claims

1. A degradable EVOH high barrier multilayer film with structure as follows:

PP/PP-TIE/PA/EVOH/PA/PE-TIE/PE Structure (1) in Structure (1), explicated from left to right:

PP represents an outer layer functioning as protection or displaying layer, whose material is polypropylene containing no hydrophilic group;

PP-TIE represents a 1st bonding layer, its material is maleic anhydride grafted polypropylene copolymer containing hydrophilic group of acid anhydride;

PA/EVOH/PA represents a middle layer consisting of a three-layer structure and functioning as a barrier layer, PA represents polyamide containing hydrophilic group of amide group, EVOH represents ethyiene-vinyi alcohol copolymer, containing hydrophilic group of hydroxyl;

PE-TIE represents a 2nd bonding layer, whose material is maleic anhydride grafted polyethylene copolymer containing hydrophilic group of acid anhydride;

PE represents a inner layer functioning as a heat-sealing layer, whose material is polyethylene containing no hydrophilic groups;

Wherein: the materials in different layers of the multilayer film gain proximate uniform biodegradability through introduction of biological carrier, the biologica! carrier is an addible masterbatch with biodegradability in landfill or composting condition, the materials of each layer are added pro rata with the masterbatch and then melt co-extruded to be multilayer fiim;

the addibie masterbatch is composed of carrier and activator, the activator is polymer containing hydrophilic group which is an effective component, the hydrophilic group is at least one of the carboxylate, carboxyl, hydroxyl, aldehyde, amide, acid anhydride and ester group;

for Structure (1), in the materials of each layer and the addible masterbatch, the ranking of hydrophility of the hydrophilic group from high to low is carboxylate, carboxyl, hydroxyl, aldehyde, amide, acid anhydride, ester group;

the carrier is selected according to the like dissolves like principle:

for polypropylene of the outer layer, carrier of the addible masterbatch is at least one of polypropylene and polyethylene;

for maleic anhydride grafted polypropylene copolymer of the 1st bonding layer, carrier of the addible masterbatch is at least one of polypropylene and polyethylene;

for polyamide of the middle layer, carrier of the addible masterbatch is polyamide;

for ethylene-vinyl alcohol copolymer of the middle layer, carrier of the addible masterbatch is polyethylene;

for maleic anhydride grafted polyethylene copolymer of the 2nd bonding layer, carrier of the addible masterbatch is polyethylene;

for polyethylene material of the inner layer, carrier of the addible masterbatch is polyethylene; the additive weight of the masterbatch to the materials of each layer is controlled within 0.3-15% of the total weight of each layer; the hydrophility of the hydrophilic group in the addible masterbatch

2015361915 31 May 2018 should be higher than or equal to the hydrophility of hydrophilic group in the materials of each layer in Structure (1), through addition of the addible masterbatch, the molar ratio of hydrophilic group vs. carbon atom in materials of each layer in Structure (1) is approaching uniform, namely biological activity of materials of each layer is approaching uniform, so the degrading speed of materials of each layer is approaching uniform.

2. A degradable EVOH high barrier multilayer film with structure as follows:

PP/PP-TIE/EVOH/PE-TIE/PE Structure (2) in Structure (2), explicated from left to right:

PP-TIE represents a 1st bonding layer, whose materia! is maleic anhydride grafted polypropylene copolymer containing hydrophilic group of acid anhydride;

EVOH represents a middle iayer functioning as a barrier layer, whose material is ethylene-vinyl alcohol copolymer containing hydrophiiic group of hydroxyl;

PE represents a inner layer functioning as heat-sealing layer, whose material is polyethylene containing no hydrophilic groups;

Wherein: the materials in different layers of the multilayer film gain proximate uniform biodegradability through introduction of biological carrier, the biological carrier is an addible masterbatch with biodegradability in landfill or composting condition, the materials of each layer are added pro rata with the masterbatch and then melt co-extruded to be multilayer film;

the addible masterbatch is composed of carrier and activator, the activator is polymer containing hydrophilic group which is an effective component, the hydrophilic group is at least one of the carboxylate, carboxyl, hydroxyl, aldehyde, amide, acid anhydride and ester group;

for Structure (2), in the materials of each layer and the addible masterbatch, the ranking of hydrophility of the hydrophiiic group from high to low is carboxylate, carboxyl, hydroxyl, aldehyde, amide, acid anhydride, ester group;

the carrier is selected according to the like dissolves like principle:

for ethylene-vinyl alcohol copolymer of the middle iayer, carrier of the addible masterbatch is polyethylene;

for maleic anhydride grafted polyethylene copolymer of the 2nd bonding iayer, carrier of the addible masterbatch is polyethylene;

2015361915 31 May 2018 for polyethylene of the inner layer, carrier of the addible masterbatch is polyethylene;

the additive weight of the masterbatch to the materials of each layer is controlled within 0.3-15% of the total weight of each layer; the hydrophility of the hydrophilic group in the addible masterbatch should be higher than or equal to the hydrophility of hydrophilic group in the materials of each layer in Structure (2), through addition of the addible masterbatch, the molar ratio of hydrophilic group vs. carbon atom in materials of each layer in Structure (2) is approaching uniform, namely biological activity of materials of each layer is approaching uniform, so the degrading speed of materials of each layer is approaching uniform.

3. The degradable PP-EVOH high barrier multilayer film of Claim 1 or 2, wherein: in the outer layer, the polypropylene is composed of isotactic polypropylene homopolymer or/and polypropylene random copolymer and the density of the polypropylene is 0.880-0.910 g/cm³.

4. The degradable PP-EVOH high barrier multilayer film of Claim 1 or 2, wherein: in the 1 st bonding layer, the density of maieic anhydride grafted polypropylene copolymer is 0.880-0.910 g/cm³, and the maleic anhydride grafting ratio in mass percentage is 0.3%-10%.

5. The degradable PP-EVOH high barrier multilayer film of Claim 1 or 2, wherein: in the barrier layer, the density of the ethylene-vinyl alcohol copolymer is 1.170-1.19 g/cm³, and the molar quantity of ethylene of ethylene-vinyl alcohol copolymer is 26-48%; the density of polyamide is 1.12-1.14 g/cm³ and the polyamide is PA6 homopolymer or PA6, 66 copolymer or amorphous polyamide.

6. The degradable PP-EVOH high barrier multilayer film of Claim 2, wherein: in the barrier layer, the density of the ethylene-vinyi alcohol copolymer is 1.170-1.19 g/cm³, and the molar quantity of ethylene of ethylene-vinyl alcohol copolymer is 26-48%.

7. The degradable PP-EVOH high barrier multilayer film of Claim 1 or 2, wherein: in the 1 st bonding layer, the density of maleic anhydride grafted polyethylene copolymer is 0.910-0.950g/cm³, and the maleic anhydride grafting ratio in mass percentage is 0.3%-10%.

8. The degradable PP-EVOH high barrier multilayer film of Claim 1 or 2, wherein: in the heatsealing layer, the density of polyethylene is 0.900-0.935g/cm³, the polyethylene contains polyethylene blends with density of 0.910-0.925 g/cm³, the polyethylene blends are composed of 50-99% polyethylene and 1-50% vinyl homopolymer, or 50-99% polyethylene and 1-50% vinyl copolymer in mass percentage, the vinyl copolymer is composed of ethylene and at least one of the C4-C12 α-olefin, C4-C12 cycloolefin, C4-C12 viny! aromatic hydrocarbon and polar vinyi monomer the density of the vinyi copolymer is 0.880-0.915 g/cm³.