A method of forming a metal lid for sealing a packaging container

Abstract

The application discloses a forming method of a metal cover for sealing a packaging container, and belongs to the technical field of metal cover forming. The forming method is as follows: a semi-finished metal piece is punched and covered to form a hollow cover, a sealing piece is arranged in the hollow cover, the hollow cover is heated, and a metal cover for sealing a packaging container is obtained after mold pressing; the metal cover comprises the sealing piece and the hollow cover, the sealing piece is a circular annular or circular polyvinyl chloride type polymer, is arranged in the metal cover, and cooperates with the packaging container in a closed state to realize barrier and oxygen removal functions. The prepared sealing piece has an oxygen permeability of less than 10.0 cm 3 / m 2 ·d·Pa at 20 DEG C, and can absorb 150 mu g / cm 2 The prepared metal cover enables the packaging object to be in a relatively oxygen-free state.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal cover forming, in particular to a forming method of metal cover for sealing packaging container. BACKGROUND

[0002] The basic structure of the food, agricultural and sideline products, milk powder and other materials on the market is a packaging container such as a glass bottle, a metal can, a plastic container, and a metal cover or a plastic cover is used for sealing, and the sealing material between the metal cover or the plastic cover and the packaging container cannot be absolutely sealed, that is, there is chronic air leakage between the metal cover or the plastic cover and the packaging container, although the "air leakage" is very slow and trace, but most of the packaging products will be spoiled due to the slow air leakage and the breeding of microorganisms, and the slow leakage of oxygen will also accelerate the spoilage of the packaging products. SUMMARY

[0003] In view of the defects of the prior art, the present application provides a forming method of metal cover for sealing packaging container. The present application uses a special polymer formula technology to prepare a polyvinyl chloride type polymer for sealing metal cover, which is used for the forming of the metal cover, and the prepared metal cover has good oxygen barrier and oxygen removal functions.

[0004] The technical scheme of the present application is as follows:

[0005] A forming method of metal cover for sealing packaging container, the forming method is: a semi-finished metal part is made into a blank cover through punching and rolling, a sealing part is placed in the blank cover, the blank cover is heated, and a metal cover for sealing packaging container is obtained after molding; the metal cover comprises a sealing part and a blank cover, the sealing part is a circular ring or a circular polyvinyl chloride type polymer, which is arranged in the metal cover to cooperate with the packaging container in a closed state to realize the barrier and oxygen removal functions.

[0006] Further, the semi-finished metal part is one or more of tin-plated iron, chromium-plated iron, film-coated iron and aluminum alloy; the thickness of the semi-finished metal part is 0.10-0.45mm; the thickness of the sealing part is 0.5-2.0mm, and the width of the circular ring of the circular ring is 7.0-10.0mm; the oxygen transmission rate of the metal cover at 20℃ is <10.0cm 3 / m 2 ·d·Pa, and the oxygen absorption amount of the sealing part in 30 days is >150μg / cm 2 .

[0007] Further, the preparation method of the sealing part is:

[0008] (1) The materials are sequentially added into a premixer, and a premixed material is obtained by stirring;

[0009] (2) The premix prepared in step (1) is added to a single screw granulator, and sieved by a vibrating screen to prepare a polyvinyl chloride type polymer;

[0010] (3) The polyvinyl chloride type polymer prepared in step (2) is extruded by an injection molding machine to form a sealing element.

[0011] Further, in step (1), the material includes the following components by weight fraction: 30-65 parts of polyvinyl chloride, 10-35 parts of barrier resin, 20-60 parts of plasticizer, 1-10 parts of oxygen absorber, 0.5-15 parts of filler, 0.1-2.5 parts of opening agent, 1-5 parts of stabilizer, and 3-15 parts of ethylene terpolymer.

[0012] Further, the K value of the polyvinyl chloride is 65-85, the standard paste viscosity is 1.0-8.0 Pa.s, and the residual amount of vinyl chloride monomer is <5.0 mg / kg; the barrier resin is polyvinylidene chloride, and the residual amount of vinyl chloride monomer in the polyvinylidene chloride is <5.0 mg / kg.

[0013] Further, the plasticizer is one or more of dioctyl terephthalate, citrate ester, epoxy soybean oil, diisononyl cyclohexane 1,2-dicarboxylate, and adipic acid polyester, all with a purity of >98%.

[0014] Further, the oxygen absorber is one or more of sodium sulfite, vitamin C, and 2,6-di-tert-butyl-p-cresol, all with a purity of >98%; the filler is white carbon black with a SiO2 content of >95% and a specific surface area of 145-185 m 2 / g; the opening agent is cis-1,3-docosene acid amide with a purity of >98% and a melting point of 78-85°C; and the stabilizer is calcium stearate with a purity of >99%.

[0015] Further, the ethylene-vinyl acetate-carbonyl terpolymer, ethylene-butyl acrylate-glycidyl ester terpolymer, and ethylene-butyl acrylate-carbonyl terpolymer are one or more of the above, and the molecular weight of the ethylene terpolymer is >20,000 Dalton, and the melting point is 40-75°C.

[0016] Further, in step (1), the stirring speed is 30-500 r / min, the time is 30-60 min, and the temperature is ≤40°C.

[0017] Further, in step (2), the length-diameter ratio of the single screw is 15-20:1; the granulation temperature is 100-135°C; the vibrating screen is a linear vibrating screen with a length of ≥3 m and a pore size of 4 mm; and the polyvinyl chloride type polymer has a melt index of 3-8 dg / min at 190°C under a load of 2.16 kg, and a diameter of 1-4 mm.

[0018] The beneficial technical effects of the present application are:

[0019] (1) The raw materials used for preparing the sealing member are all food-grade contact materials, do not contain melamine, bisphenol A and other high-risk substances of concern, have the characteristics of safety and environmental protection, and the entire forming process of the metal cover is almost VOC-free.

[0020] (2) The polyethylene type polymer prepared by the special polymer formulation technology has good barrier properties. The application of special barrier resin polyvinylidene chloride utilizes its strong intermolecular cohesive force, natural hydrophobicity of chlorine atoms and the characteristics of not forming hydrogen bonds, so that the sealing member has good oxygen barrier and dehumidification performance, and finally the oxygen transmission rate of the sealing member is less than 10.0 cm 3 / m 2 ·d·Pa at 20℃.

[0021] (3) The polyethylene type polymer prepared by the special polymer formulation technology has good oxygen removal performance. The special application of oxygen absorbers sodium sulfite, vitamin C and 2,6-di-tert-butyl-p-cresol complex utilizes the chemical reaction between the oxygen absorber in the sealing member and the trace residual oxygen in the packaging container, which can absorb 150 μg / cm 2 of oxygen in 30 days, so that the packaging is in a relatively oxygen-free state, the color, aroma and flavor of the packaging are not changed, and the shelf life of the packaging is effectively prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the forming process flow chart of the metal cover of the present application.

[0023] Figure 2 is a structural schematic diagram of the semi-finished metal part used in the present application. DETAILED DESCRIPTION

[0024] The present application will be specifically described below in combination with the drawings and examples.

[0025] A forming method of a metal cover for sealing a packaging container, as shown in Figure 1 , the forming method is to make an empty cover by punching and covering a semi-finished metal part (as shown in Figure 2 , which includes upper and lower coating or film layers, and a base material layer in the middle.), inject a polyvinyl chloride type polymer into the inside of the empty cover, and heat the empty cover to obtain a metal cover after molding the polyvinyl chloride type polymer; the metal cover includes a sealing member and an empty cover, the sealing member is obtained by molding a polyvinyl chloride type polymer, is arranged in the metal cover to cooperate with the packaging container in a closed state, and realizes the barrier and oxygen removal functions.

[0026] Example 1

[0027] A method for forming a metal cap for sealing a packaging container, the method comprising the following steps:

[0028] (1) Weigh out 50 parts of polyvinyl chloride (PVC) by weight. The PVC has a K value of 70, a standard paste viscosity of 1.0–8.0 Pa·s, and a vinyl chloride monomer residue of <5.0 mg / kg. Weigh out 20 parts of polyvinylidene chloride (PVDC) (barrier resin, with a vinyl chloride monomer residue of <5.0 mg / kg), 35 parts of trioctyl citrate (plasticizer), and an oxygen absorber consisting of a mixture of sodium sulfite and vitamin C. All components have a purity greater than 98%, including 4 parts of sodium sulfite, 4 parts of vitamin C, and 4 parts of silica (filler). The silica contains >95% SiO2 and has a specific surface area of ​​145–185 m². 2 / g, 1.5 parts of cis-13-docosahexaenoic acid amide (opening agent) (purity > 98%, melting point 78-85℃), 4 parts of calcium stearate (stabilizer) (purity > 99%), and 8 parts of ethylene-vinyl acetate-carbonyl terpolymer were added sequentially to a premixer, maintaining the material temperature at 38℃ and stirring at 300 rpm for 45 minutes; the premixed material was then added to a single screw extruder (screw length-to-diameter ratio 18:1), with the screw extruder temperature set at 1 Granulation is carried out at 00℃, and the product is screened through a linear vibrating screen (length ≥3m, aperture 4mm) to produce a polyvinyl chloride (PVC) polymer. The PVC polymer has a melt index of 3-8 dg / min at 190℃ and 2.16kg, and a particle size of 1-4mm. The polymer is then added to an injection molding machine, heated and melted at 120℃, and extruded to form a ring-shaped seal through a customized injection mold. The seal has a thickness of 0.5mm and a ring width of 7.0mm.

[0029] (2) The semi-finished metal parts (the semi-finished metal parts are 0.10mm aluminum alloy) are punched and rolled to form an empty cover, and the empty cover is heated by medium frequency with a power set at 5kw. The sealing part prepared in step (1) is placed in the empty cover. According to the product requirements, the gap between the die head and the metal parts is adjusted. After molding, a metal cover containing the sealing part is obtained.

[0030] The metal cap has an oxygen permeability of 3.2 cm at 20°C. 3 / m 2 The oxygen uptake of the seal over 30 days is 300 μg / cm³. 2 .

[0031] Example 2

[0032] A method for forming a metal cap for sealing a packaging container, the method comprising the following steps:

[0033] (1) by weight parts, respectively, take polyvinyl chloride 30 parts, polyvinyl chloride K value is 65, the standard paste viscosity is 1.0-8.0 Pa.s, vinyl chloride monomer residual amount <5.0 mg / kg, polyvinylidene chloride (barrier resin, polyvinylidene chloride vinyl chloride monomer residual amount <5.0 mg / kg) 10 parts, dioctyl phthalate (plasticizer) 20 parts, oxygen absorber is a mixture of 2,6-di-tert-butyl-p-cresol and vitamin C, purity is greater than 98%, wherein sodium sulfite 0.5 parts, vitamin C 0.5 parts, white carbon black (filler) 0.5 parts, the content of SiO2 in white carbon black is > 95%, the specific surface area is 145-185 m 2 / g, cis-13-docosene acid amide (opening agent) 0.1 parts (purity > 98%, melting point is 78-85 °C), calcium stearate (stabilizer) 1 part (purity > 99%), ethylene-butyl acrylate-glycidyl ester terpolymer 3 parts, sequentially added to the pre-mixer, the material temperature is maintained at 38 °C, stirring at 30 rpm for 30 minutes; the pre-mixed material is added to a single screw machine (screw length-diameter ratio 15:1), the screw machine temperature is set at 120 °C for granulation, screened by a linear vibrating screen (length ≥ 3 m, aperture 4 mm) to produce a polyvinyl chloride type polymer, the polyvinyl chloride type polymer has a melt index of 3-8 dg / min at 190 °C, 2.16 kg, and a particle size of 1-4 mm. The polymer is then added to an injection molding machine and heated to melt and extrude at 120 °C, and a circular ring type seal is formed by a custom injection mold, the seal has a thickness of 2.0 mm and a circular ring width of 8.0 mm.

[0034] (2) the semi-finished metal part (the semi-finished metal part is 0.10 mm tin-plated iron) is made into a cover by punching and rolling, and the cover is heated by medium frequency, with a power setting of 5 kw. The seal prepared in step (1) is placed in the cover, the gap between the die and the metal part is adjusted according to product requirements, and a metal cover containing the seal is obtained after die pressing.

[0035] The metal cover has an oxygen transmission rate of 9.5 cm 3 / m 2 ·d·Pa at 20 °C, and the seal has an oxygen absorption amount of 153 μg / cm 2 .

[0036] Example 3

[0037] A forming method of a metal cover for sealing a packaging container, the forming method comprising the following steps:

[0038] (1) by weight parts, respectively, take polyvinyl chloride 65 parts, polyvinyl chloride K value is 85, the standard paste viscosity is 1.0-8.0 Pa.s, vinyl chloride monomer residual amount < 5.0 mg / kg, polyvinylidene chloride (barrier resin, polyvinylidene chloride vinyl chloride monomer residual amount < 5.0 mg / kg) 35 parts, epoxy soybean oil 25 parts, cyclohexane 1,2-dicarboxylic acid diisononyl ester 35 parts (plasticizer 60 parts), oxygen absorber is a mixture of sodium sulfite and 2,6-di-tert-butyl-p-cresol 10 parts, purity is greater than 98%, wherein sodium sulfite 4 parts, vitamin C 6 parts, white carbon black (filler) 15 parts, the content of SiO2 in white carbon black > 95%, the specific surface area is 145-185 m 2 / g, cis-13-docosene acid amide (opening agent) 2.5 parts (purity > 98%, melting point 78-85 °C), calcium stearate (stabilizer) 5 parts (purity > 99%), ethylene-butyl acrylate-carbonyl terpolymer 15 parts, are added to the pre-mixer in turn, the material temperature is maintained at 38 °C, stirring at 500 rpm for 60 minutes; the pre-mixed material is added to a single screw machine (screw length-diameter ratio 20:1), the screw machine temperature is set at 100 °C for granulation, screened by a linear vibrating screen (length ≥ 3 m, aperture 4 mm), to produce a polyvinyl chloride type polymer, the polyvinyl chloride type polymer has a melt index of 3-8 dg / min at 190 °C, 2.16 kg, and a particle size of 1-4 mm, the polymer is then added to an injection molding machine, heated and melted at 140 °C, extruded, and formed into a circular ring type seal by a custom injection mold, the seal has a thickness of 0.5 mm and a circular ring width of 10 mm.

[0039] (2) the semi-finished metal part (the semi-finished metal part is a 0.2 mm film-coated iron) is made into a cover by punching and rolling, and the cover is heated by medium frequency, with a power setting of 5 kw, the seal prepared in step (1) is placed in the cover, the gap between the die and the metal part is adjusted according to product requirements, and a metal cover containing the seal is obtained after die pressing.

[0040] The metal cover has an oxygen transmission rate of 9.8 cm 3 / m 2 ·d·Pa at 20 °C, and the seal has an oxygen absorption amount of 280 μg / cm 2 .

[0041] Example 4

[0042] A forming method of a metal cover for sealing a packaging container, the forming method comprising the following steps:

[0043] (1) by weight parts, respectively, take polyvinyl chloride 50 parts, polyvinyl chloride K value is 70, the standard paste viscosity is 1.0-8.0 Pa.s, vinyl chloride monomer residual amount <5.0 mg / kg, polyvinylidene chloride (barrier resin, polyvinylidene chloride vinyl chloride monomer residual amount <5.0 mg / kg) 20 parts, adipic acid polyester (plasticizer) 35 parts, oxygen absorber is sodium sulfite 6 parts, purity is greater than 98%, white carbon black (filler) 4 parts, the content of SiO2 in white carbon black > 95%, the specific surface area is 145-185 m 2 / g, cis-13-docosene acid amide (opening agent) 1.5 parts (purity > 98%, melting point is 78-85 °C), calcium stearate (stabilizer) 4 parts (purity > 99%), ethylene-vinyl acetate-carbonyl terpolymer 8 parts, sequentially added to the pre-mixer, the material temperature is maintained at 38 °C, stirring at 300 rpm for 45 minutes; the pre-mixed material is added to a single screw machine (screw length-diameter ratio 18:1), the screw machine temperature is set at 100 °C for granulation, screened by a linear vibrating screen (length ≥ 3 m, aperture 4 mm) to produce a polyvinyl chloride type polymer, the polyvinyl chloride type polymer has a melt index of 3-8 dg / min at 190 °C, 2.16 kg, and a particle size of 1-4 mm. The polymer is then added to an injection molding machine, heated and melted at 135 °C, extruded, and formed into a circular ring type seal by a custom injection mold. The seal has a thickness of 2.0 mm and a circular ring width of 7.0 mm.

[0044] (2) The semi-finished metal part (the semi-finished metal part is 0.45 mm chrome-plated iron) is subjected to punching and curling to form a cover, and the cover is heated by medium frequency heating with a power setting of 5 kw. The seal prepared in step (1) is placed in the cover, and the gap between the die and the metal part is adjusted according to product requirements. After die pressing, a metal cover containing the seal is obtained.

[0045] The metal cover has an oxygen transmission rate of 6.3 cm 3 / m 2 ·d·Pa at 20 °C, and the seal has an oxygen absorption amount of 240 μg / cm 2 .

[0046] Comparative Example 1

[0047] A conventional method for forming a metal cover for sealing a packaging container includes the following steps:

[0048] (1) by weight parts, respectively, take polyvinyl chloride 100 parts, plasticizer 60 parts, filler 6 parts, cis-13-docosene acid amide (opening agent) 2 parts, calcium stearate 8 parts, sequentially added to a high-speed disperser, the material temperature is maintained at 55 °C, stirring at 1500 rpm for 45 minutes to obtain a plasticized sol.

[0049] (2) The semi-finished metal piece (the semi-finished metal piece is an aluminum alloy with a thickness of 0.10 mm) is punched into a blank, and the blank is heated by medium frequency, with the power set at 5 kw. The seal prepared in step (1) is placed in the blank, and the gap between the die and the metal piece is adjusted according to product requirements. After die pressing, a metal lid containing a seal is prepared.

[0050] The oxygen transmission rate of the metal lid is 12.1 cm 3 / m 2 ·d·Pa at 20°C, and the oxygen absorption amount of the seal is 0 μg / cm 2 .

[0051] Comparative Example 2

[0052] A forming method of a metal lid for sealing a packaging container, the forming method comprising the following steps:

[0053] (1) 50 parts by weight of polyvinyl chloride, 11 parts by weight of polyvinylidene chloride (barrier resin, the residual amount of vinyl chloride monomer in polyvinylidene chloride is <5.0 mg / kg), 35 parts by weight of trioctyl citrate (plasticizer), 1 part by weight of sodium sulfite, and 0.2 parts by weight of vitamin C, which are mixed in a premixer at a temperature of 38°C and stirred at 300 rpm for 45 minutes, are added to a single-screw extruder (the length-diameter ratio of the screw is 18:1) at a temperature of 100°C to form a polyvinyl chloride polymer, wherein the polyvinyl chloride has a K value of 70 and a standard paste viscosity of 1.0-8.0 Pa.s, the residual amount of vinyl chloride monomer is <5.0 mg / kg, the polyvinylidene chloride has a residual amount of vinyl chloride monomer <5.0 mg / kg, the content of SiO2 in the white carbon black is >95%, the specific surface area of the white carbon black is 145-185 m 2 / g, the cis-13-docosene amide (opening agent) has a purity of >98% and a melting point of 78-85°C, and the calcium stearate (stabilizer) has a purity of >99%.

[0054] (2) The semi-finished metal piece (the semi-finished metal piece is an aluminum alloy with a thickness of 0.10 mm) is punched into a blank, and the blank is heated by medium frequency, with the power set at 5 kw. The seal prepared in step (1) is placed in the blank, and the gap between the die and the metal piece is adjusted according to product requirements. After die pressing, a metal lid containing a seal is prepared.

[0055] The oxygen transmission rate of the metal cover is 6.2 cm 3 / m 2 ·d·Pa, the oxygen absorption amount of the seal is 151 μg / cm 2 .

[0056] Test Example:

[0057] The metal cover or seal prepared in Examples 1-4 and Comparative Examples 1-2 of the present application were pretreated respectively, and the VOCs were determined by GB / T 38608 standard method, the oxygen transmission rate was determined by GB / T 19789 standard method, the oxygen absorption amount was determined by gas detector, the seal flavor was evaluated by a flavor evaluation team (using a scoring system, the flavor gradually deteriorates from 1-5 points, and 5 points is unacceptable), the fast shelf life was evaluated by T / CNFIA 001 standard method (in days, the longer the number of days, the longer the actual shelf life), the sealing vacuum value was determined by a vacuum gauge, and the bonding strength between the seal and the empty cover was determined by a grid method (0-3 levels, the higher the level, the worse the strength, and levels 0-2 are qualified products)

[0058] Table 1: Performance comparison of the metal cover or seal prepared in Examples 1-4 and Comparative Examples 1-2 of the present application:

[0059]

[0060] The technical requirements of each parameter are as follows: VOCs < 0.3%, oxygen transmission rate (20°C) < 10.0 cm 3 / m 2 ·d·Pa; 30-day oxygen absorption amount > 150 μg / cm 2 ; flavor: no odor; fast shelf life; 50°C constant temperature and humidity for 15 days; sealing vacuum value > 0.04 MPa. As can be seen from the data in Table 1, compared with the metal bottle cap of Comparative Examples 1-2, the metal cap prepared by the present application has higher 30-day oxygen absorption amount, lower VOCs content, better flavor retention, better sealing vacuum degree, and better bonding of the seal. The performance of the seal and metal cap prepared by using other types or models of barrier resins was also investigated, and it was found that when a barrier resin with a residual amount of vinyl chloride monomer that is too large is used to prepare a seal for a metal cap, the oxygen transmission rate of the metal cap increases significantly, the product flavor retention is poor, and the shelf life is shortened; when the oxygen absorber is simply vitamin C, the oxygen absorption amount decreases rapidly.

[0061] Although the present application has been disclosed with reference to the preferred embodiments above, it is not intended to limit the present application, and any person skilled in the art can make various modifications and modifications without departing from the spirit and scope of the present application, therefore the protection scope of the present application should be defined by the claims.

Claims

1. A method for forming a metal cap for sealing a packaging container, characterized in that, The molding method is as follows: the semi-finished metal parts are punched and rolled to form an empty cap, the sealing element is placed inside the empty cap, the empty cap is heated, and after molding, a metal cap for sealing packaging containers is obtained; the metal cap includes a sealing element and an empty cap, the sealing element is a ring-shaped or circular polyvinyl chloride polymer, which is set in the metal cap so that it cooperates with the packaging container in a closed state to achieve the functions of barrier and oxygen removal. The method for preparing the seal is as follows: (1) Add the materials to the premixer in sequence and stir to obtain premixed materials; (2) The premixed material prepared in step (1) is added to a single screw press for granulation and screened by a vibrating screen to obtain a polyvinyl chloride polymer; (3) The polyvinyl chloride polymer prepared in step (2) is extruded using an injection molding machine to form a sealing component; By weight, in step (1), the material comprises the following components in parts by weight: 30-65 parts of polyvinyl chloride, 10-35 parts of barrier resin, 20-60 parts of plasticizer, 1-10 parts of oxygen absorber, 0.5-15 parts of filler, 0.1-2.5 parts of opening agent, 1-5 parts of stabilizer, and 3-15 parts of ethylene terpolymer; The barrier resin is polyvinylidene chloride, and the residual amount of vinyl chloride monomer in polyvinylidene chloride is <5.0 mg / kg; The oxygen absorber is one or more of sodium sulfite, vitamin C, and 2,6-di-tert-butyl-p-cresol, all with a purity >98%.

2. The molding method according to claim 1, characterized in that, The semi-finished metal part is one of tin-plated iron, chrome-plated iron, coated iron, and aluminum alloy; the thickness of the semi-finished metal part is 0.10~0.45mm; the thickness of the sealing element is 0.5~2.0mm.

3. The molding method according to claim 1, characterized in that, The polyvinyl chloride has a K value of 65~85, a standard paste viscosity of 1.0~8.0 Pa·s, and a vinyl chloride monomer residue of <5.0 mg / kg.

4. The molding method according to claim 1, characterized in that, The plasticizer is one or more of dioctyl terephthalate, citrate, epoxidized soybean oil, diisononyl cyclohexane 1,2-dicarboxylate, and polyester adipate, all with a purity >98%.

5. The molding method according to claim 1, characterized in that, The filler is silica, with a SiO2 content >95% and a specific surface area of ​​145~185 m². 2 / g; the opening agent is cis-1,3-eicosenoic acid amide, with a purity >98% and a melting point of 78~85℃; the stabilizer is calcium stearate, with a purity >99%.

6. The molding method according to claim 1, characterized in that, The ethylene terpolymer is one or more of the following: ethylene-vinyl acetate-carbonyl terpolymer, ethylene-butyl acrylate-glycidyl acrylate terpolymer, and ethylene-butyl acrylate-carbonyl terpolymer. The molecular weight of the ethylene terpolymer is greater than 200,000 Daltons, and the melting point is 40~75℃.

7. The molding method according to claim 1, characterized in that, In step (1), the stirring speed is 30~500r / min, the time is 30~60min, and the temperature is ≤40℃.

8. The molding method according to claim 1, characterized in that, In step (2), the length-to-diameter ratio of the single screw is 15~20:1; the granulation temperature is 100~135℃; the vibrating screen is a linear vibrating screen with a length ≥3m and a aperture of 4mm; the polyvinyl chloride polymer has a melt index of 3~8 dg / min at 190℃ and a volume of 2.16kg, and a diameter of 1~4mm.

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