High-strength barrier polyformaldehyde and preparation method thereof

Abstract

The invention discloses high-barrier-property polyformaldehyde and a preparation method thereof, and is characterized in that based on high-barrier polymer materials such as polyamide and polyvinyl alcohol which are excellent in barrier property, relatively low in cost and relatively good in compatibility with polyformaldehyde, the high-barrier polymer materials are blended with polyformaldehyde to obtain a polyformaldehyde blending system in which a high-barrier polymer is uniformly dispersed; then blow molding is performed in a temperature range between the melting point of the polyformaldehyde and the melting point of the high-barrier polymer material, and the high-barrier polymer component is subjected to solid-phase stretching orientation in a blowing process to form a microfiber structure to be dispersed in a polyformaldehyde matrix, so that not only can the mechanical strength of the polyformaldehyde film be improved, but also the gas barrier property of the polyformaldehyde film can be remarkably improved; and the application range of the high-strength barrier polyformaldehyde is expanded.

Description

Technical Field

[0001] The invention relates to high-strength barrier polyoxymethylene and a preparation method thereof, and belongs to the field of polymer material processing. Background Art

[0002] Polyoxymethylene (POM) is a thermoplastic engineering plastic with [-CH2-O-] as the main chain, no branching, high melting point, high density, and high crystallinity. It has excellent mechanical properties, creep resistance, fatigue resistance, wear resistance, self-lubrication, and chemical resistance. It is the closest to metal among engineering plastics and can be used to replace non-ferrous metals and alloy products such as copper, aluminum, and zinc. It is widely used in electronics, automobiles, light industry, machinery, chemicals, building materials, and other fields. Polyoxymethylene film has good application prospects in construction, packaging, medicine, and other fields.

[0003] In addition to mechanical properties and chemical resistance, gas barrier properties are one of the important properties of polymer film products, hollow containers, etc. High barrier polymers or inorganic nano-layered materials such as ethylene-vinyl alcohol copolymer (EVOH), polyamide, nanoclay, graphene, vermiculite, and alumina are used through coating, deposition, blending and compounding, or processing methods such as stretching and orientation. By enhancing the intermolecular force, extending the gas diffusion transmission path, and increasing its diffusion resistance, it is beneficial to improve the oxygen barrier properties of polymers. However, research reports on barrier polyoxymethylene are extremely scarce. Summary of the invention

[0004] In view of the research and development of barrier polyformaldehyde, the present invention provides a high-strength barrier polyformaldehyde and a preparation method thereof, which are characterized in that high-barrier polymer materials such as polyamide and polyvinyl alcohol, which have excellent barrier properties, low cost and good compatibility with polyformaldehyde, are blended with polyformaldehyde to obtain a polyformaldehyde blend system in which the high-barrier polymer is evenly dispersed; subsequently, blow molding is performed in a temperature range between the melting point of polyformaldehyde and the melting point of the high-barrier polymer material, and the high-barrier polymer component undergoes solid-phase stretching orientation during the blowing process to form a microfiber structure and is dispersed in the polyformaldehyde matrix, which can not only improve the mechanical strength of the polyformaldehyde film, but also significantly improve its gas barrier properties, thereby obtaining high-strength barrier polyformaldehyde and expanding its scope of application.

[0005] The object of the present invention is achieved by the following technical measures, wherein the parts of the raw materials are all parts by weight unless otherwise specified.

[0006] A high-strength barrier polyoxymethylene is prepared by blow molding after polyoxymethylene, an antioxidant and a high-barrier polymer are blended.

[0007] The high barrier polymer is any one of nylon 610, nylon 612 or polyvinyl alcohol; the polyvinyl alcohol is polyvinyl alcohol plasticized with glycerol.

[0008] The plasticizing method of the polyvinyl alcohol is as follows: 5-50 parts of polyvinyl alcohol with a polymerization degree of 400-3000 and a degree of alcoholysis of 75-99% and 2-20 parts of glycerol are plasticized at 60-90° C. for 5-30 minutes to obtain polyvinyl alcohol plasticized with glycerol.

[0009] The blow molding temperature is between the melting point of polyoxymethylene and the melting point of the high barrier polymer, preferably 170-200°C.

[0010] The antioxidants are pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (i.e., Irganox 1010), N,N'-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexanediamine (i.e., Irganox 1098), β-(4-hydroxy-3,5-di-tert-butylphenyl)propionate octadecyl alcohol (i.e., Irganox 1076), triethylene glycol bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (i.e., Irganox 245), and 2,6-di-tert-butyl-4-methylphenol (i.e., BHT(264)).

[0011] The present invention also provides a method for preparing the above-mentioned high-strength barrier polyoxymethylene, comprising the following steps: (1) Adding polyoxymethylene, an antioxidant and a high barrier polymer into a high-speed mixer and mixing them evenly to obtain a mixed material; if the added high barrier polymer is polyvinyl alcohol, glycerol is first added to plasticize the polyvinyl alcohol, and then mixed evenly with the polyoxymethylene and the antioxidant to obtain a mixed material; (2) melt-kneading the mixture obtained in step (1) using a twin-screw extruder, and extruding and granulating to obtain a polyoxymethylene / high barrier polymer blend; (3) Blow molding the polyoxymethylene / high barrier polymer blend described in step (2) to obtain high-strength barrier polyoxymethylene.

[0012] The extrusion granulation process parameters of step (2) are: screw speed 100-300 rpm, barrel temperature 150-230°C.

[0013] The blowing temperature in step (3) is between the melting point of polyoxymethylene and the melting point of the high barrier polymer, preferably 170-200°C, the blowing ratio of the film is 1.5-3.0, and the drawing ratio is 2.5-6.

[0014] The dosage of each raw material is: 100 parts of polyoxymethylene, 0.05-5 parts of antioxidant, 5-50 parts of high barrier polymer, and 2-20 parts of glycerol.

[0015] The present invention aims at the research and development of barrier polyoxymethylene, and provides a high-strength barrier polyoxymethylene and a preparation method thereof, which has the following beneficial effects: Polymer materials such as polyamide and polyvinyl alcohol have polyamine or polyhydroxy structures. Due to the strong hydrogen bonding between the amino groups and hydroxyl groups on their molecular chains, they have excellent barrier properties. They are low in cost and have good compatibility with polyformaldehyde. By blending them with polyformaldehyde, a polyformaldehyde blend system in which high-barrier polymers are uniformly dispersed can be obtained. On this basis, blow molding is performed in a temperature range between the melting point of polyformaldehyde and the melting point of the high-barrier polymer material. Since the high-barrier polymer component is not melted, it undergoes solid-phase stretching orientation during the inflation process to form a microfiber structure and is dispersed in the polyformaldehyde matrix; the formation of this oriented microfiber structure can not only improve the mechanical strength of the polyformaldehyde film, but also make the diffusion path of the gas molecules more tortuous through the orientation of the high-barrier polymer molecules, the transmission path is extended, and the diffusion resistance is increased, thereby significantly improving its gas barrier properties, obtaining high-strength barrier polyformaldehyde, and expanding its application range. The oxygen permeability coefficient of the strong barrier polyformaldehyde film material prepared by the present invention can be increased from 5.40×10 -12 cm 3 .cm / cm 2 .s .Pa dropped to 6.12×10 -14 cm 3 .cm / cm 2 .s .Pa, oxygen barrier performance increased by about 99%. At the same time, this processing method of achieving in-situ fiberization of polymers through blow molding is conducive to its industrial production and application. DETAILED DESCRIPTION

[0016] The embodiments of the present invention will be described in detail below with reference to examples. The following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0017] Example 1 100 parts of polyoxymethylene, 0.5 parts of triethylene glycol bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (i.e., Irganox 245), and 20 parts of nylon 610 are added into a high-speed mixer and mixed evenly, and then the mixture is melt-kneaded and extruded into granules using a twin-screw extruder, with a screw speed of 150 rpm and a barrel temperature of 170-230° C., to obtain a polyoxymethylene / nylon 610 blended material; Subsequently, the polyoxymethylene / nylon 610 blended material was blow-molded at a temperature of 200°C, a blow-up ratio of 2, and a draft ratio of 3 to obtain a high-strength barrier polyoxymethylene film material with an oxygen permeability coefficient of 1.0×10 -13 cm 3 .cm / cm 2 .s .Pa.

[0018] Example 2 10 parts of glycerol are added to 30 parts of polyvinyl alcohol with a polymerization degree of 1700 and a degree of alcoholysis of 99%, and plasticized at 80°C for 20 minutes; then 100 parts of polyoxymethylene, 0.3 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (i.e., Irganox1010), and 30 parts of plasticized polyvinyl alcohol are added to a high-speed mixer and mixed evenly, and then the mixture is melt-kneaded and extruded into granules using a twin-screw extruder, with a screw speed of 200 rpm and a barrel temperature of 170-230°C, to obtain a polyoxymethylene / polyvinyl alcohol blended material; Subsequently, the polyoxymethylene / polyvinyl alcohol blended material was blow-molded at a blow molding temperature of 195°C, a film blowing ratio of 3, and a draft ratio of 4 to obtain a high-strength barrier polyoxymethylene film material; its oxygen permeability coefficient is 6.12×10 - 14 cm 3 .cm / cm 2 .s .Pa.

[0019] Example 3 100 parts of polyoxymethylene, 0.5 parts of triethylene glycol bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (i.e., Irganox 245), and 20 parts of nylon 612 are added into a high-speed mixer and mixed evenly, and then the mixture is melt-kneaded and extruded into granules using a twin-screw extruder, with a screw speed of 150 rpm and a barrel temperature of 170-230° C., to obtain a polyoxymethylene / nylon 612 blended material; Subsequently, the polyoxymethylene / nylon 610 blended material was blow-molded at a temperature of 190°C, a blow-up ratio of 2, and a draft ratio of 2.5 to obtain a high-strength barrier polyoxymethylene film material with an oxygen permeability coefficient of 8.9×10 -14 cm 3 .cm / cm 2 .s .Pa.

[0020] Example 4 Same as Example 2, except that the blowing temperature was 220°C, and the oxygen permeability coefficient of the obtained polyoxymethylene film material was 9.6×10 -13 cm 3 .cm / cm 2 .s .Pa.

[0021] Example 5 Same as Example 2, except that the blowing ratio of the film is 3.5, the drawing ratio is 2, and the oxygen permeability coefficient of the obtained polyoxymethylene film material is 8.3×10 -13 cm 3 .cm / cm 2 .s .Pa.

[0022] Comparative Example 1 Pure polyoxymethylene was blow-molded at a temperature of 200°C, a film blowing ratio of 2, and a draft ratio of 3 to obtain a polyoxymethylene film material with an oxygen permeability coefficient of 6.0×10 -12 cm 3 .cm / cm 2 .s .Pa.

[0023] Comparative Example 2 Pure polyoxymethylene was blow-molded at a temperature of 195°C, a film blowing ratio of 3, and a draft ratio of 4 to obtain a polyoxymethylene film material; its oxygen permeability coefficient was 5.4×10 -12 cm 3 .cm / cm 2 .s .Pa.

Claims

1. A high-strength barrier polyoxymethylene, characterized in that: It is made by blow molding after blending polyoxymethylene, antioxidant and high barrier polymer.

2. The high-strength barrier polyoxymethylene according to claim 1, characterized in that: The high barrier polymer is any one of nylon 610, nylon 612 or polyvinyl alcohol; the polyvinyl alcohol is polyvinyl alcohol plasticized with glycerol.

3. The high-strength barrier polyoxymethylene according to claim 2, characterized in that: The plasticizing method of the polyvinyl alcohol is as follows: 5-50 parts of polyvinyl alcohol with a polymerization degree of 400-3000 and a degree of alcoholysis of 75-99% and 2-20 parts of glycerol are plasticized at 60-90° C. for 5-30 minutes to obtain polyvinyl alcohol plasticized with glycerol.

4. The high-strength barrier polyoxymethylene according to claim 1, characterized in that: The blow molding temperature is between the melting point of polyoxymethylene and the melting point of the high barrier polymer, preferably 170-200°C.

5. The high-strength barrier polyoxymethylene according to claim 1, characterized in that: The antioxidant is any one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester, N,N'-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexanediamine, β-(4-hydroxy-3,5-di-tert-butylphenyl)propionate octadecyl ester, triethylene glycol bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, and 2,6-di-tert-butyl-4-methylphenol.

6. The method for preparing a high-strength barrier polyoxymethylene according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Adding polyoxymethylene, an antioxidant and a high barrier polymer into a high-speed mixer and mixing them evenly to obtain a mixed material; if the added high barrier polymer is polyvinyl alcohol, glycerol is first added to plasticize the polyvinyl alcohol, and then mixed evenly with the polyoxymethylene and the antioxidant to obtain a mixed material; (2) melt-kneading the mixture obtained in step (1), and extruding and granulating to obtain a polyoxymethylene / high barrier polymer blend; (3) Blow molding the polyoxymethylene / high barrier polymer blend described in step (2) to obtain high-strength barrier polyoxymethylene.

7. The method for preparing high-strength barrier polyoxymethylene according to claim 6, characterized in that: The extrusion granulation process parameters of step (2) are: screw speed 100-300 rpm, barrel temperature 150-230°C.

8. The method for preparing high-strength barrier polyoxymethylene according to claim 6, characterized in that: The blowing temperature in step (3) is between the melting point of polyoxymethylene and the melting point of the high barrier polymer, preferably 170-200°C, the blowing ratio of the film is 1.5-3.0, and the drawing ratio is 2.5-6.

9. The method for preparing high-strength barrier polyoxymethylene according to claim 6, characterized in that: The dosage of each raw material is: 100 parts of polyoxymethylene, 0.05-5 parts of antioxidant, 5-50 parts of high barrier polymer, and 2-20 parts of glycerol.