Method for evaluating the adhesive strength and oil stain resistance of an EVA resin for pre-coated films

Abstract

This invention provides a method for evaluating the degree of oil stain resistance of the bonding performance between EVA resin and a pre-coated film base film, belonging to the field of packaging materials technology. This invention is based on the fact that the oil stain resistance of the bonding strength of EVA resin in pre-coated films is related not only to the molecular structure of EVA and the molecular structure, hydrophilicity, and surface hardness of the polypropylene film base film, but also to their compatibility, fluidity under external stimuli, mechanical properties, and their changing patterns. By designing corresponding analytical methods, relevant parameters are obtained, and formulas are designed to calculate parameters reflecting the degree of loss in bonding strength of EVA resin after lamination with the pre-coated film base film under the influence of oil stains. This method evaluates the oil stain resistance of EVA resin when used as a pre-coated film and lamination with the base film, thus achieving an accurate and rapid evaluation of its oil stain resistance. The calculation formula is as follows:

Description

Technical Field

[0001] This invention belongs to the field of performance testing technology for packaging film materials, specifically relating to an evaluation method for the oil resistance of EVA resin bonding strength in pre-coated films, that is, a test method for the degree of oil resistance affecting the bonding performance between EVA resin and the pre-coated film base film. Background Technology

[0002] Pre-coated film refers to a type of adhesive film material formed by pre-coating a plastic film with adhesive and then rewinding it. Pre-coated film typically uses polypropylene or PET film as the substrate. The adhesive applied to the substrate surface is usually a hot melt adhesive, which bonds the substrate after heating, and is typically ethylene-vinyl acetate copolymer (EVA resin). Pre-coated film is widely used in books, packaging, digital printing, posters, and commercial advertising.

[0003] The structure of a pre-coated film consists of a pre-coated base film (usually a polypropylene film or a PET film) and an EVA layer. The bonding strength between the two determines the usability of the final product. However, in actual use, it has been found that even if the bonding strength between the produced EVA layer and the pre-coated base film is high enough, the performance of the pre-coated film may not meet expectations in subsequent use because this bonding strength is often affected by various environmental factors.

[0004] For example, because pre-coated films often come into contact with oil or organic solvents during use, the bond strength between the EVA layer and the pre-coated film base film can be significantly reduced due to oil contamination, leading to delamination and peeling. Therefore, the performance of pre-coated films needs to be examined in terms of how their bond strength changes under the influence of environmental factors such as oil contamination. Only pre-coated films with oil resistance can maintain high bond strength over a long period, thus meeting the requirements of various applications.

[0005] Therefore, it is necessary to test the bond strength between the base film and EVA resin of the pre-coated film, and to comprehensively consider the impact of oily environments on the bond strength. Thus, it is necessary to examine the oil resistance of the EVA resin bond strength in the pre-coated film. However, currently there is no specific characterization and evaluation method for this. Generally, the bond strength of the material in an oily environment can only be determined by preparing the pre-coated film using conventional methods and then conducting long-term oil immersion tests. However, this method has drawbacks such as being time-consuming and yielding inaccurate test results. Therefore, there is an urgent need to provide a method that can directly test the oil resistance of the EVA resin bond strength in the pre-coated film. Summary of the Invention

[0006] This invention addresses the issue that the bonding performance of EVA resin in existing pre-coated films is significantly affected by oil contamination, necessitating prior knowledge of the extent to which oil contamination affects the bonding performance of EVA resin. Therefore, it provides a method for evaluating the oil resistance of EVA resin bonding strength in pre-coated films. This solves the current lack of methods for characterizing and evaluating this aspect, thus facilitating accurate assessment of whether EVA resin maintains stable bonding strength in oily environments.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for evaluating the adhesive strength and oil resistance of EVA resin for pre-coated films includes the following steps:

[0009] (1) Take EVA resin and pre-coated film base film respectively, and crush them into particles;

[0010] (2) The pulverized EVA resin and the pre-coated film base film are mixed and molded according to the mass ratio x to obtain composite material X;

[0011] (3) Tensile properties of composite material X were tested to obtain the tensile properties of composite material X at tensile temperature T. tx , tensile deformation rate d x Tensile strength S x and elongation at break l x ;

[0012] (4) The melt flow index (MI) of composite material X was tested. x ;

[0013] (5) Take EVA resin and pre-coated film base film separately, crush them into particles and blend them according to mass ratio x. At the same time, add additive Z with a mass fraction of y of the total mass of EVA resin and pre-coated film base film particles. After mixing evenly, plasticize, blend, and mold to obtain composite material Y.

[0014] (6) Tensile properties of composite material Y were tested to obtain the tensile properties of composite material Y at tensile temperature T. ty , tensile deformation rate d y Tensile strength S y and elongation at break l y ;

[0015] (7) The melt flow index (MI) of the composite material Y was tested. y ;

[0016] (8) The water contact angle (WCA) of the pre-coated film base film was tested and obtained; the test was conducted according to the national standard "GB / T 30693-2014 Measurement of the water contact angle of plastic film".

[0017] (9) Test the surface hardness of the pre-coated film base film to obtain its surface hardness H; test according to the national standard "GBT3398.2-2008 Plastics Hardness Determination Part 2: Rockwell Hardness";

[0018] (10) Calculate the evaluation index S of the adhesion performance between EVA resin and pre-coated film base film under the influence of oil pollution using the following formula; the higher the S value, the greater the degree of loss of adhesion performance between EVA resin and pre-coated film base film under the influence of oil pollution; the calculation formula is as follows:

[0019]

[0020] Furthermore, the mass ratio x mentioned in steps (2) and (5) is 1:99 to 68:32, preferably 18:82 to 41:59.

[0021] Furthermore, the tensile temperature T mentioned in step (3) tx =15~80℃, preferably T tx =25~60℃.

[0022] Furthermore, the tensile deformation rate d mentioned in step (3) x =30-300% per minute, preferably d x =50-150% per minute.

[0023] Furthermore, the additive Z mentioned in step (5) is a mixture of one or more of the following: maleic anhydride-grafted polypropylene, maleic anhydride-grafted polyethylene, acrylonitrile-styrene copolymer-acrylate copolymer, ionic liquid, hydrogenated petroleum resin, cellulose acetate, sodium hydroxymethyl cellulose, cyclic olefin copolymer, white oil, silicone oil, and xylene.

[0024] Furthermore, the mass fraction y of additive Z in step (5) is 0.1-16.8%, preferably 0.5-9.2%.

[0025] Furthermore, the tensile temperature T mentioned in step (6) ty =25~100℃, preferably T ty =30~80℃.

[0026] Furthermore, the tensile deformation rate d mentioned in step (6) y =40-400% per minute, preferably d y =80-120% per minute.

[0027] Furthermore, the test method for the melt flow index in steps (4) and (7) is carried out in accordance with the national standard "GB T3682.1-2018 Determination of melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastic plastics".

[0028] This invention innovatively proposes that the oil resistance characteristics of the pre-coated film, being a multi-layered, multi-component composite material, are not only related to the molecular structure of EVA and the molecular structure, hydrophilicity, and surface hardness of the polypropylene film base layer, but also to their compatibility, fluidity under external stimuli, mechanical properties, and their variation patterns. By designing corresponding analytical methods to obtain relevant parameters, and designing formulas to calculate parameters reflecting the degree of loss in the bonding strength of the EVA resin used in the pre-coated film after lamination with the base film under the influence of oil, this invention evaluates its oil resistance performance when used as a pre-coated film and laminated with the base film, thereby achieving an accurate and rapid evaluation of its oil resistance performance.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) This invention proposes for the first time a method that can quickly evaluate the degree of loss of bonding strength of EVA resin for pre-coated film under the influence of oil stains after being combined with pre-coated film base film. It has the characteristics of being reliable, fast and accurate.

[0031] (2) The method provided by the present invention can be used to quickly and accurately test the bonding strength and oil resistance of pre-coated films, and provides guidance on the long-term performance of such materials. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described in detail below with reference to embodiments. It should be noted that the following embodiments are for explanation and illustration only and are not intended to limit the invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description are still within the scope of protection of this invention.

[0033] Example 1

[0034] To investigate the adhesion properties and resistance to oil contamination of EVA resin A and EVA resin B, the following methods were used to test them respectively.

[0035] (1) Take EVA resin A, resin B and pre-coated film base film respectively, and crush them into fine particles respectively;

[0036] (2) The EVA resin A or EVA resin B is mixed with the fine particles of the pre-coated film base film at a mass ratio of x = 24:76, and then molded to obtain composite materials XA and XB.

[0037] (3) Tensile properties were tested on composite materials XA and XB respectively. The test conditions were: tensile temperature T tx =50℃, tensile deformation rate d x =140% per minute, its tensile strength S was measured x The strengths are 24 MPa and 30 MPa, respectively, and the elongation at break is l. x They were 340% and 290% respectively;

[0038] (4) Melt flow index tests were performed on composite materials XA and XB respectively to obtain their melt flow index MI. x The concentrations were 3.8g / 10min and 6.9g / 10min, respectively.

[0039] (5) The EVA resin A or EVA resin B is blended with the fine particles of the pre-coated film base film at a mass ratio of x = 24:76. At the same time, maleic anhydride grafted polyethylene is added as an additive accounting for 1% of the total mass fraction of EVA and pre-coated film base film particles y = 1%. After mixing evenly, the mixture is plasticized, blended, and molded to obtain composite materials YA and YB respectively.

[0040] (6) Tensile properties were tested on composite materials YA and YB respectively. The test conditions were: tensile temperature T ty =80℃, tensile deformation rate d y =120% per minute, its tensile strength S was measured y The strengths are 29 MPa and 32 MPa, respectively, and the elongation at break is l. y They are 300% and 285% respectively;

[0041] (7) Melt flow index tests were performed on composite materials YA and YB respectively to obtain their melt flow index MI. y The concentrations were 5.8g / 10min and 6.6g / 10min, respectively.

[0042] (8) The water contact angle of the pre-coated base film was tested, and the water contact angle WCA was found to be 66°.

[0043] (9) The surface hardness of the pre-coated film base film was tested and found to be H=48;

[0044] (10) Using the following formulas, the oil resistance performance index S of the bonding strength of EVA resin A and EVA resin B were calculated to be 20.5% and 18.3%, respectively. This indicates that the bonding strength of the pre-coated film prepared by EVA resin A decreased by a greater proportion after being exposed to oil than that of EVA resin B, meaning that its oil resistance is not as good as that of resin B. Pre-coated films prepared using EVA resin A and EVA resin B through the traditional pre-coating process, and after long-term oil resistance tests, were tested for bonding strength. The results showed that under oil exposure, the bonding strength loss rates of EVA resin A and EVA resin B were 20.6% and 18.2%, respectively. This indicates that the oil resistance of EVA resin A in the pre-coated film is not as good as that of EVA resin B, which is consistent with the results calculated by this evaluation method.

[0045]

[0046] Example 2

[0047] To assess the bonding strength and oil resistance of EVA resins C and D, the following tests were conducted:

[0048] (1) Take EVA resin C, resin D and pre-coated film base film respectively, and crush them into fine particles respectively;

[0049] (2) The EVA resin C or EVA resin D is mixed with the fine particles of the pre-coated film base film at a mass ratio of x = 40:60, and then molded to obtain composite materials XC and XD.

[0050] (3) Tensile properties were tested on composite materials XC and XD respectively. The test conditions were: tensile temperature T tx =60℃, tensile deformation rate d x =150% per minute, its tensile strength S was measured x The strengths are 12 MPa and 25 MPa, respectively, and the elongation at break is l. x They are 350% and 180% respectively;

[0051] (4) Melt flow index tests were performed on composite materials XC and XD respectively to obtain their melt flow index MI. x The values ​​were 12g / 10min and 4.9g / 10min, respectively.

[0052] (5) The EVA resin C or EVA resin D is blended with the fine particles of the pre-coated film base film at a mass ratio of x = 40:60. At the same time, hydrogenated petroleum resin is added as an additive accounting for 2.8% of the total mass fraction of EVA and pre-coated film base film particles y = 2.8%. After mixing evenly, the mixture is plasticized, blended, and molded to obtain composite materials YC and YD respectively.

[0053] (6) Tensile properties were tested on composite materials YC and YD respectively. The test conditions were: tensile temperature T ty =50℃, tensile deformation rate d y =80% per minute, its tensile strength S was measured y The strengths are 18 MPa and 27 MPa, respectively, and the elongation at break is l. y They are 160% and 155% respectively;

[0054] (7) Melt flow index tests were performed on composite materials YC and YD respectively to obtain their melt flow index MI. y The values ​​were 18g / 10min and 7.2g / 10min, respectively.

[0055] (8) The water contact angle of the pre-coated base film was tested, and the water contact angle WCA was found to be 42°.

[0056] (9) The surface hardness of the pre-coated film base film was tested and found to be H=69;

[0057] (10) Using the following formulas, the oil resistance performance index S of the bonding strength of EVA resin C and EVA resin D were calculated to be 10.2% and 23.9%, respectively. This indicates that the bonding strength of the pre-coated film prepared by EVA resin C decreased less after being exposed to oil than that of EVA resin D, meaning that its oil resistance is better than that of resin D. Pre-coated films prepared using EVA resin C and EVA resin D through the traditional pre-coating process, and after long-term oil resistance tests, were tested for bonding strength. The results showed that under oil exposure, the bonding strength loss rates of EVA resin C and EVA resin D were 10.0% and 24.1%, respectively. This indicates that the oil resistance of EVA resin D in the pre-coated film is inferior to that of EVA resin C, which is consistent with the results calculated by this evaluation method.

[0058]

[0059] Example 3

[0060] To examine the bonding strength and oil resistance of EVA resins E and F, the following tests were conducted:

[0061] (1) Take EVA resin E, resin F and pre-coated film base film respectively, and crush them into fine particles respectively;

[0062] (2) The EVA resin E or EVA resin F is mixed with the fine particles of the pre-coated film base film at a mass ratio of x = 39:61, and then molded to obtain composite materials XE and XF.

[0063] (3) Tensile properties were tested on composite materials XE and XF respectively. The test conditions were: tensile temperature T tx =25℃, tensile deformation rate d x =60% per minute, its tensile strength S was measured x The strengths are 26 MPa and 18 MPa, respectively, and the elongation at break is l. x They were 190% and 228% respectively;

[0064] (4) Melt flow index tests were performed on composite materials XE and XF respectively to obtain their melt flow index MI. x The values ​​were 6.8g / 10min and 10g / 10min, respectively.

[0065] (5) The EVA resin E or EVA resin F is blended with the fine particles of the pre-coated film base film at a mass ratio of x = 39:61. At the same time, a mixture of additive white oil and silicone oil (mass ratio of 1:1) accounting for 4.9% of the total mass fraction of EVA and pre-coated film base film particles is added. After the mixture is evenly mixed, it is plasticized, blended, and molded to obtain composite materials YE and YF respectively.

[0066] (6) Tensile properties were tested on composite materials YE and YF respectively. The test conditions were: tensile temperature T ty =30℃, tensile deformation rate d y =100% per minute, the tensile strength S was measured. y The strengths are 22 MPa and 8 MPa, respectively, and the elongation at break is l. y They were 242% and 266% respectively;

[0067] (7) Melt flow index tests were performed on composite materials YE and YF respectively to obtain their melt flow index MI. y The values ​​were 9.5g / 10min and 16g / 10min, respectively.

[0068] (8) The water contact angle of the pre-coated base film was tested, and the water contact angle WCA was found to be 83°.

[0069] (9) The surface hardness of the pre-coated film base film was tested and found to be H=61;

[0070] (10) Using the following formulas, the oil resistance performance index S of the bonding strength of EVA resin E and EVA resin F were calculated to be 29.8% and 19.6%, respectively. This indicates that the bonding strength of the pre-coated film prepared by EVA resin E decreased by a greater proportion after being exposed to oil than that of EVA resin F, meaning that its oil resistance is not as good as that of resin F. Pre-coated films prepared using EVA resin E and EVA resin F through the traditional pre-coating process, and after long-term oil resistance tests, were tested for bonding strength. The results showed that under oil exposure, the bonding strength loss rates of EVA resin E and EVA resin F were 30% and 19.5%, respectively. This indicates that the oil resistance of EVA resin E for pre-coated films is not as good as that of EVA resin F, which is consistent with the results calculated by this evaluation method.

[0071]

[0072] Example 4

[0073] To examine the bonding strength and oil resistance of EVA resins G and H, the following tests were conducted:

[0074] (1) Take EVA resin G, resin H and pre-coated film base film respectively, and crush them into fine particles respectively;

[0075] (2) The EVA resin G or EVA resin H is mixed with the fine particles of the pre-coated film base film at a mass ratio of x = 28:72, and then molded to obtain composite materials XG and XH.

[0076] (3) Tensile properties were tested on composite materials XG and XH respectively. The test conditions were: tensile temperature T tx =40℃, tensile deformation rate d x =120% per minute, its tensile strength S was measured x The strengths are 15 MPa and 22 MPa, respectively, and the elongation at break is l. x They were 221% and 190% respectively;

[0077] (4) Melt flow index tests were performed on composite materials XG and XH respectively to obtain their melt flow index MI. x The concentrations were 14.2g / 10min and 10.8g / 10min, respectively.

[0078] (5) The EVA resin G or EVA resin H is blended with the fine particles of the pre-coated film base film at a mass ratio of x = 28:72. At the same time, an additive cyclic olefin copolymer accounting for y = 8.8% of the total mass fraction of EVA and pre-coated film base film particles is added. After the mixture is evenly mixed, it is plasticized, blended, and molded to obtain composite materials YG and YH respectively.

[0079] (6) Tensile properties were tested on composite materials YG and YH respectively. The test conditions were: tensile temperature T ty =40℃, tensile deformation rate d y =110% per minute, its tensile strength S was measured y The strengths are 24 MPa and 38 MPa, respectively, and the elongation at break is l. y The percentages were 198% and 97%, respectively.

[0080] (7) Melt flow index tests were performed on composite materials YG and YH respectively to obtain their melt flow index MI. y The concentrations were 10.1 g / 10 min and 6.6 g / 10 min, respectively.

[0081] (8) The water contact angle of the pre-coated base film was tested, and the water contact angle WCA = 90° was obtained;

[0082] (9) The surface hardness of the pre-coated film base film was tested and found to be H = 72.

[0083] (10) Using the following formulas, the oil resistance performance index S of the bonding strength of EVA resin G and EVA resin H were calculated to be 25.8% and 14.3%, respectively. This indicates that the bonding strength of the pre-coated film prepared by EVA resin G decreased by a greater percentage after being exposed to oil than that of EVA resin H, meaning its oil resistance is inferior to that of resin H. Pre-coated films prepared using EVA resin G and EVA resin H through the traditional pre-coating process, and after long-term oil resistance tests, were tested for bonding strength. The results showed that under oil exposure, the bonding strength loss rates of EVA resin G and EVA resin H were 25.7% and 14.4%, respectively. This indicates that the oil resistance of EVA resin G in the pre-coated film is inferior to that of EVA resin H, which is consistent with the results calculated by this evaluation method.

[0084]

[0085] Example 5

[0086] To examine the bonding strength and oil resistance of EVA resins I and J, the following tests were conducted:

[0087] (1) Take EVA resin I, resin J and pre-coated film base film respectively, and crush them into fine particles respectively;

[0088] (2) The EVA resin I or EVA resin J is mixed with the fine particles of the pre-coated film base film at a mass ratio of x = 31:69, and then molded to obtain composite materials XI and XJ.

[0089] (3) Tensile properties were tested on composite materials XI and XJ respectively. The test conditions were: tensile temperature T tx =55℃, tensile deformation rate d x =80% per minute, its tensile strength S was measured x The strengths are 29 MPa and 12 MPa, respectively, and the elongation at break is l. x They were 68% and 290% respectively;

[0090] (4) Melt flow index tests were performed on composite materials XI and XJ respectively to obtain their melt flow index MI. x The concentrations were 13.6g / 10min and 7.4g / 10min, respectively.

[0091] (5) The EVA resin I or EVA resin J is blended with the fine particles of the pre-coated film base film at a mass ratio of x = 31:69. At the same time, a mixture of additive xylene and ionic liquid (mass ratio of 1:1) accounting for 6.9% of the total mass fraction of EVA and pre-coated film base film particles is added. After the mixture is evenly mixed, it is plasticized, blended, and molded to obtain composite materials YI and YJ respectively.

[0092] (6) Tensile properties were tested on composite materials YA and YB respectively. The test conditions were: tensile temperature T ty =70℃, tensile deformation rate d y =90% per minute, its tensile strength S was measured y The strengths are 19.8 MPa and 11.4 MPa, respectively, and the elongation at break is l. y They were 134% and 257% respectively;

[0093] (7) Melt flow index tests were performed on composite materials YI and YJ respectively to obtain their melt flow index MI. y The concentrations were 21.4 g / 10 min and 9.9 g / 10 min, respectively.

[0094] (8) The water contact angle of the pre-coated base film was tested, and the water contact angle WCA was found to be 72°.

[0095] (9) The surface hardness of the pre-coated film base film was tested and found to be H=38;

[0096] (10) Using the following formulas, the oil resistance performance index S of the bonding strength of EVA resin I and EVA resin J were calculated to be 32% and 21%, respectively. This indicates that the bonding strength of the pre-coated film prepared by EVA resin I decreased by a greater percentage after being exposed to oil than that of EVA resin J, meaning that its oil resistance is not as good as that of resin J. Pre-coated films prepared using EVA resin I and EVA resin J through the traditional pre-coating process, and after a long-term oil resistance test, were tested for bonding strength. The results showed that under the influence of oil, the bonding strength loss rates of EVA resin I and EVA resin J were 32.4% and 20.8%, respectively. This indicates that the oil resistance of EVA resin I in the pre-coated film is not as good as that of EVA resin J, which is consistent with the results calculated by this evaluation method.

[0097]

Claims

1. A method for evaluating the bonding strength and oil resistance of EVA resin for pre-coated films, characterized in that, Includes the following steps: (1) Take EVA resin and pre-coated film base film respectively, and crush them into particles; (2) The crushed EVA resin and the pre-coated film base film are mixed according to the following mass ratio. x The mixture is then subjected to intensive mixing, compression molding, and finally, a composite material is obtained. X ; (3) For composite materials X Tensile property tests were conducted to obtain the composite material. X At stretching temperature T tx , tensile deformation rate d x Tensile strength below S x and elongation at break l x ; (4) For composite materials X Melt flow index was obtained by performing a melt flow index test. MI x ; (5) Take EVA resin and pre-coated film base film separately, crush them into particles and then mix them according to the mass ratio. x The mixture is blended, and a certain percentage of the total mass of EVA resin and pre-coated film base particles is added. y Additive Z is mixed evenly, then plasticized, blended, and molded to obtain a composite material. Y The additive Z is a mixture of one or more of the following: ionic liquid, hydrogenated petroleum resin, cellulose acetate, sodium carboxymethyl cellulose, cyclic olefin copolymer, white oil, silicone oil, and xylene. (6) For composite materials Y Tensile property tests were conducted to obtain the composite material. Y At stretching temperature T ty , tensile deformation rate d y Tensile strength below S y and elongation at break l y ; (7) For composite materials Y Melt flow index was obtained by performing a melt flow index test. MI y ; (8) The water contact angle of the pre-coated base film was tested to obtain the water contact angle. WCA The test was conducted according to the national standard "GB / T 30693-2014 Measurement of the contact angle between plastic film and water". (9) The surface hardness of the pre-coated film base film was tested to obtain its surface hardness. H Tested according to the national standard "GB / T 3398.2-2008 Determination of Hardness of Plastics Part 2: Rockwell Hardness"; (10) Calculate the evaluation index S of the adhesion performance between EVA resin and pre-coated film base film under the influence of oil pollution using the following formula; the higher the S value, the greater the degree of loss of adhesion performance between EVA resin and pre-coated film base film under the influence of oil pollution; the calculation formula is as follows: 。 2. The evaluation method according to claim 1, characterized in that, The mass ratio mentioned in steps (2) and (5) x The ratio is 1:99 to 68:

32.

3. The evaluation method according to claim 2, characterized in that, The mass ratio mentioned in steps (2) and (5) x The time is 18:82~41:

59.

4. The evaluation method according to claim 1 or 2, characterized in that, The stretching temperature mentioned in step (3) T tx =15~80℃.

5. The evaluation method according to claim 4, characterized in that, The stretching temperature mentioned in step (3) T tx =25~60℃.

6. The evaluation method according to claim 1 or 2, characterized in that, The tensile deformation rate described in step (3) d x =30~300% per minute.

7. The evaluation method according to claim 6, characterized in that, The tensile deformation rate described in step (3) d x =50~150% per minute.

8. The evaluation method according to claim 1 or 2, characterized in that, The mass fraction of additive Z mentioned in step (5) y The range is 0.1% to 16.8%.

9. The evaluation method according to claim 8, characterized in that, The mass fraction of additive Z mentioned in step (5) y The range is 0.5% to 9.2%.

10. The evaluation method according to claim 1 or 2, characterized in that, The stretching temperature mentioned in step (6) T ty =25~100℃.

11. The evaluation method according to claim 10, characterized in that, The stretching temperature mentioned in step (6) T ty =30~80℃.

12. The evaluation method according to claim 1 or 2, characterized in that, The tensile deformation rate described in step (6) d y =40~400% per minute.

13. The evaluation method according to claim 12, characterized in that, The tensile deformation rate described in step (6) d y =80~120% per minute.

14. The evaluation method according to claim 1, characterized in that, The melt flow index test method described in steps (4) and (7) shall be carried out in accordance with the national standard "GB / T 3682.1-2018 Determination of melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastic plastics".

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