Environmentally friendly degradable plastic and preparation method thereof

Abstract

The present invention proposes an environmentally friendly degradable plastic and a preparation method thereof, and belongs to the technical field of degradable materials. It includes: S1. dissolving benzyl alcohol in acetonitrile, adding lactic acid, stirring and dissolving, adding benzoyl alcohol, heating and stirring to react, and obtaining intermediate A; S2. dissolving intermediate A in dichloromethane, dropping thionyl chloride, stirring to react, and obtaining intermediate B; S3. dissolving intermediate B and styrene methanol in N, N-dimethylformamide, adding alkali, heating and stirring to react, and obtaining intermediate C; S4. dissolving intermediate C in toluene, adding initiator, heating and stirring to react, and blowing into plastic film by hot melt extrusion through a single screw extrusion film blowing machine, and finally cutting, rolling and packaging to obtain environmentally friendly degradable plastic. The present invention solves the shortcomings of common degradable plastics that they degrade rapidly and slowly, and that they degrade incompletely. In addition, the mechanical properties of plastics are greatly improved, thereby expanding their scope of application.

Description

Technical Field

[0001] The present invention relates to the technical field of degradable materials, and in particular to an environmentally friendly degradable plastic and a preparation method thereof. Background Art

[0002] Plastics are synthetic polymer compounds, which are materials polymerized by synthesis or condensation reaction of monomer raw materials. They are composed of synthetic resins and additives such as fillers, plasticizers, stabilizers, lubricants, and colorants. Most plastics have the advantages of light weight, chemical stability, no rust, good impact resistance, and good insulation. Therefore, plastics are widely used in stationery products, catering supplies, packaging supplies and other fields. Since the main raw materials of plastics are high molecular weight polyolefin resins such as PVC, PS, PP, PE, and PET, their products are difficult to degrade or have a long degradation cycle, and waste products are difficult to recycle and reuse, which wastes resources.

[0003] There are many technical problems that need to be solved in the existing degradable plastic films, such as the high cost, incomplete degradation, and uncontrollable degradation of bio-based materials and plastics directly blended to prepare films; the use of multi-layer composite films to prepare degradable plastic films has complex processes, mismatches between layers, and incomplete composite and incomplete degradation. Most existing technologies achieve a high degradation rate by adding a large amount of biomass materials, but the mechanical properties of the film cannot be guaranteed, the remaining plastic is difficult to continue to degrade, and the undegraded fragments will still cause environmental pollution. Summary of the invention

[0004] The purpose of the present invention is to provide an environmentally friendly degradable plastic and a preparation method thereof, which solves the shortcomings of ordinary degradable plastics that they degrade slowly and incompletely, and in addition, greatly improves the mechanical properties of the plastic, thereby expanding its application range.

[0005] The technical solution of the present invention is achieved in this way:

[0006] The present invention provides an environmentally friendly degradable plastic having a structural formula as shown in Formula I:

[0007]

[0008] Among them, m=10-100; n=20-50.

[0009] The present invention provides a method for preparing the above-mentioned environmentally friendly and degradable plastic, comprising the following steps:

[0010] S1. Benzyl alcohol and lactic acid are reacted in the presence of an initiating catalyst to obtain an intermediate A, the structure of which is as follows:

[0011] S2. Intermediate A is treated with thionyl chloride to obtain intermediate B, the structure of which is as follows:

[0012] S3. The intermediate B is reacted with styrene methanol to obtain an intermediate C having the following structure:

[0013] S4. The intermediate C is treated with an initiator to produce an environmentally friendly biodegradable plastic.

[0014] As a further improvement of the present invention, the initiating catalyst in step S1 is benzoyl alcohol.

[0015] As a further improvement of the present invention, the mass ratio of benzyl alcohol, lactic acid and initiating catalyst in step S1 is 10:22-27:0.5-1.

[0016] As a further improvement of the present invention, the mass ratio of the intermediate A to thionyl chloride in step S2 is 10:3-5.

[0017] As a further improvement of the present invention, the mass ratio of the intermediate B to styrene methanol in step S3 is 15-20:2-3.

[0018] As a further improvement of the present invention, the initiator in step S4 is selected from at least one of sodium persulfate, ammonium persulfate and potassium persulfate.

[0019] As a further improvement of the present invention, the mass ratio of the intermediate C to the initiator in step S4 is 100:1-2.

[0020] As a further improvement of the present invention, the present invention specifically comprises the following steps:

[0021] S1. Dissolve 10 parts by weight of benzyl alcohol in acetonitrile, add 22-27 parts by weight of lactic acid, stir to dissolve, add 0.5-1 parts by weight of benzoyl alcohol, heat to 35-40°C, stir to react for 1-3h, filter, wash, and dry to obtain intermediate A;

[0022] S2. 10 parts by weight of intermediate A was dissolved in dichloromethane, 3-5 parts by weight of thionyl chloride was added dropwise, the reaction was stirred at 0°C to room temperature for 0.5-1h, filtered, washed and dried to obtain intermediate B;

[0023] S3. Dissolve 15-20 parts by weight of intermediate B and 2-3 parts by weight of styrene methanol in N,N-dimethylformamide, add 5-7 parts by weight of a base, heat to 60-80 ° C, stir the reaction for 2-3h, filter, wash, and dry to obtain intermediate C;

[0024] S4. Dissolve the intermediate C in toluene, heat to 110-120°C, add 1-2 parts by weight of initiator, stir and react for 2-4 hours, filter, wash, dry, and use a single screw extrusion film blowing machine to hot melt extrude and blow mold into a plastic film at 150-180°C. Finally, cut, roll and package to obtain an environmentally friendly and degradable plastic.

[0025] As a further improvement of the present invention, the base is selected from at least one of triethylamine, diethylamine, sodium carbonate, sodium bicarbonate, NaOH, and KOH.

[0026] The invention has the following beneficial effects: the invention produces a modified polylactic acid type degradable and environmentally friendly plastic, the plastic molecular chain contains a polylactic acid structure, has good degradability, biocompatibility, safety and environmental protection, and at the same time, contains a rigid structure of a benzene ring molecule, so that the plastic has good hardness and mechanical properties, the benzene ring is connected to the polylactic acid structure by an ether group, and the ether group also has good decomposition performance, thereby solving the shortcomings of ordinary degradable plastics that they degrade quickly and slowly and are not completely degraded, and in addition, greatly improves the mechanical properties of the plastic, thereby expanding its application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 Schematic diagram of the synthesis of the environmentally friendly and degradable plastic of the present invention. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] like Figure 1 This embodiment provides an environmentally friendly and degradable plastic, which specifically includes the following steps:

[0032] S1. Dissolve 10 parts by weight of benzyl alcohol in acetonitrile, add 22 parts by weight of lactic acid, stir to dissolve, add 0.5 parts by weight of benzoyl alcohol, heat to 35°C, stir to react for 1h, filter, wash, and dry to obtain intermediate A;

[0033] S2. 10 parts by weight of intermediate A was dissolved in dichloromethane, 3-5 parts by weight of thionyl chloride was added dropwise, the reaction was stirred at 0°C for 0.5, filtered, washed and dried to obtain intermediate B;

[0034] S3. 15 parts by weight of intermediate B and 2 parts by weight of styrene methanol were dissolved in N,N-dimethylformamide, 5 parts by weight of KOH were added, heated to 60 ° C, stirred for 2h, filtered, washed, and dried to obtain intermediate C;

[0035] S4. Dissolve the intermediate C in toluene, heat to 110°C, add 1 part by weight of ammonium persulfate, stir and react for 2 hours, filter, wash, dry, and use a single-screw extrusion film blowing machine to hot-melt extrude and blow mold into a plastic film at 150°C. Finally, cut, roll and package to obtain an environmentally friendly and degradable plastic.

[0036] Example 2

[0037] like Figure 1 This embodiment provides an environmentally friendly and degradable plastic, which specifically includes the following steps:

[0038] S1. Dissolve 10 parts by weight of benzyl alcohol in acetonitrile, add 27 parts by weight of lactic acid, stir to dissolve, add 1 part by weight of benzoyl alcohol, heat to 40°C, stir to react for 3h, filter, wash, and dry to obtain intermediate A;

[0039] S2. 10 parts by weight of intermediate A was dissolved in dichloromethane, 5 parts by weight of thionyl chloride was added dropwise, the reaction was stirred at room temperature for 1h, filtered, washed and dried to obtain intermediate B;

[0040] S3. 20 parts by weight of intermediate B and 3 parts by weight of styrene methanol were dissolved in N,N-dimethylformamide, 7 parts by weight of NaOH were added, heated to 80 ° C, stirred for 3h, filtered, washed and dried to obtain intermediate C;

[0041] S4. Dissolve the intermediate C in toluene, heat to 120°C, add 2 parts by weight of potassium persulfate, stir and react for 4 hours, filter, wash, dry, and use a single-screw extrusion film blowing machine to hot-melt extrude and blow mold into a plastic film at 180°C. Finally, cut, roll and package to obtain an environmentally friendly and degradable plastic.

[0042] Example 3

[0043] like Figure 1 This embodiment provides an environmentally friendly and degradable plastic, which specifically includes the following steps:

[0044] S1. Dissolve 10 parts by weight of benzyl alcohol in acetonitrile, add 25 parts by weight of lactic acid, stir to dissolve, add 0.7 parts by weight of benzoyl alcohol, heat to 37° C., stir to react for 2 h, filter, wash, and dry to obtain intermediate A;

[0045] S2. 10 parts by weight of intermediate A was dissolved in dichloromethane, 4 parts by weight of thionyl chloride was added dropwise, the reaction was stirred at room temperature for 1h, filtered, washed, and dried to obtain intermediate B;

[0046] S3. 17 parts by weight of intermediate B and 2.5 parts by weight of styrene methanol were dissolved in N,N-dimethylformamide, 6 parts by weight of triethylamine were added, heated to 70 ° C, stirred for 2.5h, filtered, washed and dried to obtain intermediate C;

[0047] S4. Dissolve the intermediate C in toluene, heat to 115°C, add 1.5 parts by weight of sodium persulfate, stir and react for 3 hours, filter, wash, dry, and use a single-screw extrusion film blowing machine to hot-melt extrude and blow mold into a plastic film at 170°C. Finally, cut, roll and package to obtain an environmentally friendly and degradable plastic.

[0048] Test Example 1

[0049] The performance tests were conducted on Examples 1-3 of the present invention, the prepared environmentally friendly degradable plastics, polylactic acid plastics, and commercially available degradable plastics. The results are shown in Table 1.

[0050] The elongation at break and tensile strength are determined according to GB / T 1040-1992.

[0051] The water absorption rate is determined according to GB / T 1034-2008 method.

[0052] The 15-day degradation rate is determined according to the GB / T 20197-2006 method.

[0053] Oil stain resistance test: Use the plastic sample in a place with oil stains, and observe the state of oil stains adhering to the surface of the plastic sample after one week.

[0054] Table 1

[0055]

[0056] It can be seen from the above table that the environmentally friendly degradable plastics prepared in Examples 1-3 of the present invention have good mechanical properties, reduced water absorption, excellent degradation properties, and good oil resistance.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing environmentally friendly degradable plastics, characterized in that: The following steps are involved: S1. Benzyl alcohol and lactic acid are reacted in the presence of an initiating catalyst to obtain an intermediate A, the structure of which is as follows: ； S2. Intermediate A is treated with thionyl chloride to obtain intermediate B, the structure of which is as follows: ; S3. The intermediate B is reacted with styrene methanol to obtain an intermediate C having the following structure: ； S4. The intermediate C is treated with an initiator to obtain an environmentally friendly biodegradable plastic; The environmentally friendly degradable plastic has a structural formula as shown in Formula I: ； Among them, m=10-100; n=20-50.

2. The preparation method according to claim 1, characterized in that: The initiating catalyst in step S1 is benzoyl alcohol.

3. The preparation method according to claim 1, characterized in that: The mass ratio of benzyl alcohol, lactic acid and initiating catalyst in step S1 is 10:22-27:0.5-1.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the intermediate A to thionyl chloride in step S2 is 10:3-5.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the intermediate B to styrene methanol in step S3 is 15-20:2-3.

6. The preparation method according to claim 1, characterized in that: The initiator in step S4 is at least one selected from sodium persulfate, ammonium persulfate, and potassium persulfate.

7. The preparation method according to claim 1, characterized in that: The mass ratio of the intermediate C to the initiator in step S4 is 100:1-2.

8. The preparation method according to claim 1, characterized in that: The specific steps include: S1. Dissolve 10 parts by weight of benzyl alcohol in acetonitrile, add 22-27 parts by weight of lactic acid, stir to dissolve, add 0.5-1 parts by weight of benzoyl alcohol, heat to 35-40°C, stir to react for 1-3h, filter, wash, and dry to obtain intermediate A; S2. 10 parts by weight of intermediate A was dissolved in dichloromethane, 3-5 parts by weight of thionyl chloride was added dropwise, the reaction was stirred at 0°C to room temperature for 0.5-1h, filtered, washed and dried to obtain intermediate B; S3. Dissolve 15-20 parts by weight of intermediate B and 2-3 parts by weight of styrene methanol in N,N-dimethylformamide, add 5-7 parts by weight of a base, heat to 60-80 ° C, stir the reaction for 2-3h, filter, wash, and dry to obtain intermediate C; S4. Dissolve the intermediate C in toluene, heat to 110-120°C, add 1-2 parts by weight of initiator, stir and react for 2-4 hours, filter, wash, dry, and use a single screw extrusion film blowing machine to hot melt extrude and blow mold into a plastic film at 150-180°C. Finally, cut, roll and package to obtain an environmentally friendly and degradable plastic.

9. The preparation method according to claim 8, characterized in that: The base is selected from at least one of triethylamine, diethylamine, sodium carbonate, sodium bicarbonate, NaOH, and KOH.

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