Degradable environment-friendly plastic film and preparation method thereof

Abstract

The invention relates to the technical field of polystyrene plastic, and discloses a degradable environment-friendly plastic film and a preparation method thereof. The preparation method comprises the following steps: adding 20-50 parts by weight of styrene, 50-80 parts by weight of 4-(phenyl carbonate) styrene and 2.2-3 parts by weight of an initiator into a solvent, carrying out a reaction, pouring the obtained solution into the surface of a mold, carrying out film casting, and drying to remove the solvent so as to obtain the degradable environment-friendly plastic film. The film has good tensile strength and elongation at break. And a degradable carbonate group is introduced into a polystyrene molecular chain, so that the film is endowed with good biodegradability. Good practical application is realized in the aspects of food and medicine packaging and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polystyrene plastics, and specifically to a degradable environmental protection plastic film and a preparation method thereof. Background Art

[0002] Due to its excellent mechanical properties, heat resistance, insulation and other properties, polystyrene can be made into products such as films and plastics, and has a wide range of applications in the fields of packaging materials, electronic appliances, medical devices, etc. Traditional polystyrene does not have biodegradable properties and causes relatively large pollution, which is not conducive to its practical application in disposable packaging products and other aspects. Introducing biodegradable ester groups, carbonate groups, etc. into polystyrene can enhance the biodegradable properties of polystyrene materials. Chinese Patent CN110066355B discloses a degradable polystyrene and its preparation method. By reacting a dihalide and a dicarboxylic acid initiator, a macromolecular initiator is obtained, and then reacting with styrene, the obtained ester group multi-block polystyrene has good degradable properties. However, the preparation method of the macromolecular initiator in this patent is relatively complex, and the prepared polystyrene does not show good mechanical properties such as tensile strength. Summary of the Invention

[0003] The technical problem solved by the present invention is to provide a degradable environmental protection plastic film, which solves the problem that polystyrene film materials are not easily biodegradable.

[0004] The technical solution of the present invention: A preparation method of a degradable environmental protection plastic film, comprising: adding 20 - 50 parts by weight of styrene and 50 - 80 parts by weight of 4-(phenyl carbonate)styrene to a solvent, stirring and dissolving, then in a nitrogen atmosphere, heating to the reaction temperature, dropping 2.2 - 3 parts by weight of an initiator, stirring and reacting, then pouring the solution onto the surface of a mold, casting into a film, and drying to remove the solvent to obtain a degradable environmental protection plastic film. The reaction formula is:

[0005]

[0006] Preferably, the solvent is tetrahydrofuran, toluene, dimethyl sulfoxide or N,N-dimethylformamide.

[0007] Preferably, the initiator is azobisisobutyronitrile or benzoyl peroxide.

[0008] Preferably, the reaction temperature is 60 - 75°C, and the reaction time is 12 - 18 h.

[0009] Preferably, the drying temperature is 60 - 150°C, and the time is 1 - 8 h.

[0010] Preferably, the preparation method of 4-(benzyl carbonate)styrene comprises the following steps: adding 4-hydroxystyrene, phenyl chloroformate, and a catalyst into a reaction solvent, stirring and reacting at room temperature for 4-6 h, distilling under reduced pressure, washing with water, and recrystallizing the product in ethyl acetate to obtain 4-(benzyl carbonate)styrene. The reaction formula is as follows:

[0011]

[0012] Preferably, the reaction solvent is dichloromethane, chloroform, or ethyl acetate.

[0013] Preferably, the molar ratio of 4-hydroxystyrene, phenyl chloroformate, and the catalyst is 1:(1-1.2):(1-1.3).

[0014] Preferably, the catalyst is triethylamine or N,N-diisopropylethylamine.

[0015] The beneficial technical effects of the present invention: reacting 4-hydroxystyrene with phenyl chloroformate to obtain 4-(benzyl carbonate)styrene monomer, then copolymerizing with styrene to obtain a polystyrene copolymer, and after casting, drying, and forming a film, the obtained polystyrene plastic film has good tensile strength and elongation at break. And introducing a degradable carbonate group into the polystyrene molecular chain endows the film with good biodegradability. It has good practical applications in food and drug packaging and other aspects. Detailed implementation mode

[0016] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0017] Example 1

[0018] (1) Add 30 mmol of 4-hydroxystyrene, 30 mmol of phenyl chloroformate, and 36 mmol of the catalyst triethylamine to 40 mL of dichloromethane, stir and react at room temperature for 6 h, distill under reduced pressure, wash with water, and recrystallize the product in ethyl acetate to obtain 4-(benzyl carbonate)styrene.

[0019] (2) Add 50 g of styrene and 50 g of 4-(phenyl carbonate)styrene to 800 mL of toluene, stir to dissolve, then under a nitrogen atmosphere, heat to 70 °C, dropwise add 2.4 g of the initiator azobisisobutyronitrile, stir and react for 12 h, pour the solution onto the surface of a mold, cast into a film, and dry at 110 °C for 4 h to remove the solvent to obtain a degradable environmental protection plastic film.

[0020] Example 2

[0021] (1) 30 mmol of 4-hydroxystyrene, 36 mmol of phenyl chloroformate, and 39 mmol of the catalyst N,N-diisopropylethylamine were added to 50 mL of ethyl acetate, and the mixture was stirred at room temperature for 4 h. After distillation under reduced pressure, the product was washed with water and recrystallized from ethyl acetate to obtain 4-(benzyl carbonate)styrene.

[0022] (2) 40 g of styrene and 60 g of 4-(phenyl carbonate)styrene were added to 1 L of dimethyl sulfoxide and stirred until dissolved. Then, under a nitrogen atmosphere, the temperature was raised to 75 °C, and 2.2 g of the initiator azobisisobutyronitrile was added dropwise. The mixture was stirred for 12 h, and the solution was poured onto the surface of a mold and cast into a film. The film was dried at 150 °C for 8 h to remove the solvent, obtaining a degradable environmental protection plastic film.

[0023] Example 3

[0024] (1) 30 mmol of 4-hydroxystyrene, 30 mmol of phenyl chloroformate, and 30 mmol of the catalyst triethylamine were added to 40 mL of chloroform, and the mixture was stirred at room temperature for 6 h. After distillation under reduced pressure, the product was washed with water and recrystallized from ethyl acetate to obtain 4-(benzyl carbonate)styrene.

[0025] (2) 30 g of styrene and 70 g of 4-(phenyl carbonate)styrene were added to 1 L of tetrahydrofuran and stirred until dissolved. Then, under a nitrogen atmosphere, the temperature was raised to 60 °C, and 3 g of the initiator benzoyl peroxide was added dropwise. The mixture was stirred for 18 h with reflux condensation during the reaction. The solution was poured onto the surface of a mold and cast into a film. The film was dried at 60 °C for 1 h to remove the solvent, obtaining a degradable environmental protection plastic film.

[0026] Example 4

[0027] (1) 4-(Phenyl carbonate)styrene was prepared according to the method of Example 1.

[0028] (2) 20 g of styrene and 80 g of 4-(phenyl carbonate)styrene were added to 1 L of N,N-dimethylformamide solvent and stirred until dissolved. Then, under a nitrogen atmosphere, the temperature was raised to 75 °C, and 2.7 g of the initiator azobisisobutyronitrile was added dropwise. The mixture was stirred for 12 h, and the solution was poured onto the surface of a mold and cast into a film. The film was dried at 150 °C for 8 h to remove the solvent, obtaining a degradable environmental protection plastic film.

[0029] Comparative Example 1

[0030] (1) Add 100 g of styrene to 800 mL of toluene. After stirring and dissolving, under a nitrogen atmosphere, heat the mixture to 70 °C, dropwise add 2.4 g of the initiator azobisisobutyronitrile, stir and react for 12 h. Pour the solution onto the surface of a mold, cast it into a film, and dry it at 110 °C for 4 h to remove the solvent, obtaining a degradable environmental protection plastic film.

[0031] Comparative Example 2

[0032] (1) Add 30 mmol of 2-methylallyl alcohol, 30 mmol of phenyl chloroformate, and 36 mmol of the catalyst triethylamine to 40 mL of dichloromethane. Stir and react at room temperature for 6 h, perform vacuum distillation, and after washing with water, recrystallize the product from ethyl acetate to obtain phenyl 2-methylallyl carbonate. The structural formula is

[0033] (2) Add 50 g of styrene and 50 g of phenyl 2-methylallyl carbonate to 800 mL of toluene. After stirring and dissolving, under a nitrogen atmosphere, heat the mixture to 70 °C, dropwise add 2.4 g of the initiator azobisisobutyronitrile, stir and react for 12 h. Pour the solution onto the surface of a mold, cast it into a film, and dry it at 110 °C for 4 h to remove the solvent, obtaining a degradable environmental protection plastic film.

[0034] Test the biodegradability of the film according to the method of GB / T 19277.2-2013.

[0035] Test the tensile strength and elongation at break of the film according to the method of GB / T 1040.3-2006.

[0036] Table 1 Film Performance Test

[0037]

[0038] After testing, the 60-day biodegradation rate of the polystyrene film in Comparative Example 1 is only 0.17%, and it hardly has biodegradability. In Examples 1-4, through the copolymerization reaction of styrene with 4-(phenyl carbonate)styrene containing a styrene structure and a degradable carbonate group , the main chain of the copolymer obtained is a polystyrene molecular chain, enabling the film material to still maintain good mechanical properties. The tensile strength and elongation at break have a very small difference from those of the polystyrene film material in Comparative Example 1. And by introducing the degradable carbonate group into the polystyrene molecular chain, good biodegradability is imparted to the film.

[0039] In Comparative Example 2, using 2-methylallyl alcohol as a raw material, phenyl 2-methylallyl carbonate (not containing a styrene structure) was prepared. After polymerization with styrene, the main chain of the copolymer prepared is styrene and 2-methylallyl The block molecular chain, rather than a simple polystyrene molecular chain, has its mechanical properties greatly affected, with the tensile strength and elongation at break significantly reduced.

Claims

1. A preparation method of a degradable environmental protection plastic film, characterized in that, The preparation method comprises the following steps: adding 20-50 parts by weight of styrene and 50-80 parts by weight of 4-(phenyl carbonate) styrene into a solvent, stirring to dissolve, then under a nitrogen atmosphere, heating to the reaction temperature, dropping 2.2-3 parts by weight of an initiator, stirring and reacting, then pouring the solution onto the surface of a mold, casting into a film, drying to remove the solvent, and obtaining a degradable environmental protection plastic film.

2. The preparation method of the degradable environmental protection plastic film according to claim 1, characterized in that, The solvent is tetrahydrofuran, toluene, dimethyl sulfoxide or N,N-dimethylformamide.

3. The preparation method of the degradable environmental protection plastic film according to claim 1, wherein, The initiator is azobisisobutyronitrile or benzoyl peroxide.

4. The preparation method of the degradable environmental protection plastic film according to claim 1, characterized in that, The reaction temperature is 60-75 °C and the reaction time is 12-18 h.

5. The preparation method of the degradable environmental protection plastic film according to claim 1, characterized in that, The drying temperature is 60-150 °C and the time is 1-8 h.

6. The preparation method of the degradable environmental protection plastic film according to claim 1, characterized in that, The preparation method of the 4-(benzyl carbonate) styrene comprises the following steps: adding 4-hydroxystyrene, phenyl chloroformate and a catalyst into a reaction solvent, stirring and reacting at room temperature for 4-6 h, performing vacuum distillation, washing with water, and recrystallizing the product in ethyl acetate to obtain 4-(benzyl carbonate) styrene.

7. The preparation method of the degradable environmental protection plastic film according to claim 6, wherein The reaction solvent is dichloromethane, chloroform or ethyl acetate.

8. The preparation method of the degradable environmental protection plastic film according to claim 6, characterized in that, The molar ratio of the 4-hydroxystyrene, phenyl chloroformate and the catalyst is 1:(1-1.2):(1-1.3).

9. The preparation method of the degradable environmental protection plastic film according to claim 6, characterized in that, The catalyst is triethylamine or N,N-diisopropylethylamine.

10. A degradable environmental protection plastic film obtained by the preparation method according to claims 1-9.

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