Transparent biodegradable film material and preparation method thereof

Abstract

The invention discloses a transparent biodegradable film material and a preparation method thereof, and belongs to the technical field of high polymer materials, the transparent biodegradable film material comprises the following raw materials by weight: 80-85 parts of polyolefin resin, 15-20 parts of starch grafted dialkyl phosphate, 0.3-0.5 part of an antioxidant and 0.3-0.5 part of a lubricant; the preparation method of the starch-grafted dialkyl phosphate comprises the following steps: dissolving urea and dialkyl phosphate in distilled water, adjusting the pH value, stirring, adding starch, filtering, pre-drying a filter cake at 50 DEG C, heating and reacting to prepare the starch-grafted dialkyl phosphate; the film material provided by the invention has high transparency and is biodegradable.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, in particular to a transparent biodegradable film material and a preparation method thereof. Background Art

[0002] Polyolefin film is a colorless, tasteless, odorless, translucent, non-toxic insulating material. It is most widely used in the packaging field and can also be used to make various containers. It is a type of polymer material with the largest output and a wide range of applications. However, this material degrades very slowly in the natural environment. Therefore, the "white pollution" caused by discarded products has caused considerable harm to the environment.

[0003] Biodegradable plastics refer to a type of plastic that is degraded by microorganisms such as bacteria, molds and algae that exist in nature. An ideal biodegradable plastic is a polymer material that has excellent performance and can be completely decomposed by microorganisms in the environment after being discarded, and is eventually degraded into carbon dioxide and water. Although there are studies that polyolefin materials can be biodegraded in the environment, the degradation time is particularly long. Adding starch can improve the biodegradability of polyolefin films.

[0004] In the prior art, the use of starch alone has the disadvantages of seriously affecting the transparency of the substrate and having poor compatibility with the substrate, and has a significant impact on the mechanical properties of the polyolefin material, resulting in low strength and poor light transmittance of the polypropylene composite material. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention proposes a transparent biodegradable film material and a preparation method thereof. The present invention first uses dialkyl phosphates to functionalize starch. The dialkyl phosphates serve as the nucleus core of heterogeneous nucleation, thereby improving the heterogeneous nucleation effect in the crystallization process of the material, reducing the crystal size, improving the crystallinity, and reducing the scattering and refractive index of light on the crystal interface, thereby improving the transparency of the material. Grafting can improve the lipophilicity of starch, and has good dispersibility in polyolefins, which can improve the strength of the material; after the starch is degraded, the material produces micropores, which increases the surface area of ​​the material, causing the end groups of the polymer material to be exposed, promoting further degradation of the material, and can increase the biodegradation rate of the polyolefin material. The purpose of the present invention can be achieved by the following technical solutions:

[0006] A transparent biodegradable film material comprises the following raw materials in parts by weight: 80-85 parts of polyolefin resin, 15-20 parts of starch grafted dialkyl phosphate, 0.3-0.5 parts of antioxidant and 0.3-0.5 parts of lubricant; the preparation method of the starch grafted dialkyl phosphate comprises the following steps: dissolving urea and dialkyl phosphate in distilled water, adjusting the pH value, adding starch with stirring, filtering, pre-drying the filter cake at 50°C, heating, reacting, and obtaining the starch grafted dialkyl phosphate.

[0007] Preferably, the polyolefin resin includes one or more of polyethylene and random copolymer polypropylene.

[0008] Preferably, the heating reaction time is 2 hours.

[0009] Preferably, the dialkyl phosphate includes one or more of dimethyl magnesium phosphate and diethyl aluminum hypophosphite.

[0010] Preferably, the starch includes one or more of corn starch and potato starch.

[0011] Preferably, the antioxidant includes one or more of aromatic amine antioxidants, hindered phenol antioxidants and phosphite antioxidants.

[0012] Preferably, the lubricant includes one or more of a stearic acid soap lubricant and a silicone lubricant.

[0013] Preferably, the stirring time is 30 min.

[0014] Preferably, the heating temperature is 150°C.

[0015] A method for preparing a transparent biodegradable film material comprises the following steps:

[0016] Mixing 80-85 parts of a polyolefin resin, 0.3-0.5 parts of an antioxidant and 0.3-0.5 parts of a lubricant to obtain a mixed material;

[0017] The above mixture and 15-20 parts of starch grafted dialkyl phosphate are melted, extruded and dried to obtain a transparent biodegradable film material.

[0018] Beneficial effects of the present invention:

[0019] 1. The highly transparent biodegradable film material and preparation method thereof of the present invention, the starch grafted dialkyl phosphate in the raw material can improve the lipophilicity of the starch, thereby improving its compatibility with polyolefin materials and reducing the influence of adding starch on the mechanical properties of the material.

[0020] 2. Dialkyl phosphates act as the nucleus of heterogeneous nucleation, which improves the heterogeneous nucleation effect in the crystallization process of the material, reduces the crystal size, improves the crystallinity, reduces the scattering and refractive index of light on the crystal interface, and thus improves the transparency of the material.

[0021] 3. Adding starch can increase the biodegradation rate of polyolefin materials. Starch degrades faster in polymer materials. After starch degradation, micropores are generated in the material, which increases the surface area of ​​the material, causing the end groups of the polymer material to be exposed, thus promoting further degradation of the material. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0023] The present invention first uses dialkyl phosphate to functionalize starch. The dialkyl phosphate serves as the nucleus core of heterogeneous nucleation, improves the heterogeneous nucleation effect in the crystallization process of the material, reduces the crystal size, improves the crystallinity, reduces the scattering and refractive index of light on the crystal interface, and thus improves the transparency of the material. Grafting can improve the lipophilicity of starch, has good dispersibility in polyolefins, and can improve the strength of the material; after starch degradation, the material generates micropores, increases the surface area of ​​the material, causes the end groups of the polymer material to be exposed, promotes further degradation of the material, and can improve the biodegradation rate of the polyolefin material.

[0024] Example 1

[0025] A highly transparent biodegradable film material in this embodiment is made of the following raw materials in parts by weight:

[0026]

[0027] The specific preparation method comprises the following steps:

[0028] S1. Dissolve 1g urea and 5g dimethyl magnesium phosphate in distilled water, adjust the pH value to 5, add 50g corn starch with stirring, stir at 23°C for 30min, filter, pre-dry the filter cake at 50°C to a moisture content of 5%, heat it in an oven to 150°C, react for 2h, and obtain corn starch grafted dimethyl magnesium phosphate.

[0029] S2, weighing polyolefin resin, antioxidant and lubricant according to the proportion, adding them into a high-speed mixer and mixing for 5 minutes to obtain a mixed material;

[0030] S3. Add the mixture obtained in step S2 into a twin-screw extruder through a main feeding hopper, add the corn starch grafted dimethyl magnesium phosphate in step S1 through the side of the first natural exhaust port, and obtain a highly transparent biodegradable film material through melting, extrusion, and drying; wherein the barrel temperature of the twin-screw extruder is 220° C., the screw speed is 500 r / min, the main engine speed is 22 Hz, and the vacuum degree is -0.08 MPa.

[0031] Example 2

[0032] A highly transparent biodegradable film material in this embodiment is made of the following raw materials in parts by weight:

[0033]

[0034]

[0035] The specific preparation method comprises the following steps:

[0036] S1. Dissolve 1g urea and 5g diethylaluminum hypophosphite in distilled water, adjust the pH value to 6, add 50g potato starch with stirring, stir at 23°C for 30min, filter, pre-dry the filter cake at 50°C to a moisture content of 5%, heat it in an oven to 150°C, react for 2h, and obtain potato starch grafted diethylaluminum hypophosphite.

[0037] S2, weighing polyolefin resin, antioxidant and lubricant according to the proportion, adding them into a high-speed mixer and mixing for 5 minutes to obtain a mixed material;

[0038] S3, adding the mixture obtained in step S2 into a twin-screw extruder through a main feeding hopper, adding the potato starch grafted diethyl aluminum hypophosphite in step S1 through the side of the first section natural exhaust port, and obtaining a highly transparent biodegradable film material through melting, extrusion and drying; wherein the barrel temperature of the twin-screw extruder is 220° C., the screw speed is 500 r / min, the main engine speed is 22 Hz, and the vacuum degree is -0.08 MPa.

[0039] Example 3

[0040] A highly transparent biodegradable film material in this embodiment is made of the following raw materials in parts by weight:

[0041]

[0042] The specific preparation method comprises the following steps:

[0043] S1. Dissolve 50g potato starch and 1g dimethyl magnesium phosphate in 100ml distilled water, heat at 300W microwave for 5min, add anhydrous ethanol, stir at 23℃ for 30min, add catalyst, heat to 75℃, react for 8h, and obtain potato starch grafted dimethyl magnesium phosphate.

[0044] S2, weighing polyolefin resin, antioxidant and lubricant according to the proportion, adding them into a high-speed mixer and mixing for 5 minutes to obtain a mixed material;

[0045] S3, adding the mixed material obtained in step S2 into a twin-screw extruder through a main feeding hopper, adding the potato starch grafted dimethyl magnesium phosphate in step S1 through the side of the first section natural exhaust port, and obtaining a highly transparent biodegradable film material through melting, extrusion and drying; wherein the barrel temperature of the twin-screw extruder is 220° C., the screw speed is 500 r / min, the main engine speed is 22 Hz, and the vacuum degree is -0.08 MPa.

[0046] Comparative Example 1

[0047] The difference from Example 1 is that the starch is not grafted. The composite material of this comparative example is made of the following raw materials in parts by weight:

[0048] A highly transparent biodegradable film material in this embodiment is made of the following raw materials in parts by weight:

[0049]

[0050] The specific preparation method comprises the following steps:

[0051] S1, weighing polyolefin resin, antioxidant and lubricant according to the proportion, adding them into a high-speed mixer and mixing for 5 minutes to obtain a mixed material;

[0052] S2. Add the mixed material obtained in step S1 into a twin-screw extruder through a main feeding hopper, add the starch in step S1 through the side of the first natural exhaust port, and obtain a highly transparent biodegradable film material through melting, extrusion, and drying; wherein the barrel temperature of the twin-screw extruder is 220° C., the screw speed is 500 r / min, the main engine speed is 22 Hz, and the vacuum degree is -0.08 MPa.

[0053] The main physical properties of the polypropylene composite materials obtained in the above Examples 1-3 and Comparative Example 1 were tested according to relevant testing standards, and the testing standards and test results of the tensile strength, degradation rate and light transmittance are shown in Table 1:

[0054] Table 1: Main physical properties of polypropylene composite materials in Examples 1-3 and Comparative Examples 1-2

[0055]

[0056] In the present invention, dialkyl phosphate is used to functionalize starch. Dialkyl phosphate serves as the nucleus core of heterogeneous nucleation, improves heterogeneous nucleation in the crystallization process of the material, reduces crystal size, improves crystallinity, reduces light scattering and refractive index on the crystal interface, and thus improves the transparency of the material. Grafting can improve the lipophilicity of starch, and has good dispersibility in polyolefins, which can improve the strength of the material; after starch degradation, the material generates micropores, which increases the surface area of ​​the material, causes the end groups of the polymer material to be exposed, promotes further degradation of the material, and can improve the biodegradation rate of the polyolefin material.

[0057] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0058] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A transparent biodegradable film material, It is characterized in that The method comprises the following raw materials in parts by weight: 80-85 parts of polyolefin resin, 15-20 parts of starch grafted dialkyl phosphate, 0.3-0.5 parts of antioxidant and 0.3-0.5 parts of lubricant; The preparation method of starch grafted dialkyl phosphate comprises the following steps: dissolving urea and dialkyl phosphate in distilled water, adjusting the pH value, stirring and adding starch, filtering, pre-drying the filter cake at 50° C., heating, reacting, and preparing starch grafted dialkyl phosphate.

2. The transparent biodegradable film material according to claim 1, It is characterized in that The polyolefin resin includes one or more of polyethylene and random copolymer polypropylene.

3. The transparent biodegradable film material according to claim 1, It is characterized in that The heating reaction time is 2h.

4. The transparent biodegradable film material according to claim 1, It is characterized in that The dialkyl phosphate includes one or more of dimethyl magnesium phosphate and diethyl aluminum hypophosphite.

5. The transparent biodegradable film material according to claim 1, It is characterized in that The starch includes one or more of corn starch and potato starch.

6. The transparent biodegradable film material according to claim 1, It is characterized in that The antioxidant includes one or more of aromatic amine antioxidants, hindered phenol antioxidants and phosphite antioxidants.

7. The transparent biodegradable film material according to claim 1, It is characterized in that The lubricant includes one or more of a stearic acid soap lubricant and a silicone lubricant.

8. The transparent biodegradable film material according to claim 1, It is characterized in that The stirring time is 30 min.

9. The transparent biodegradable film material according to claim 1, It is characterized in that The heating temperature is 150°C.

10. A method for preparing a transparent biodegradable film material, It is characterized in that The following steps are involved: Mixing 80-85 parts of a polyolefin resin, 0.3-0.5 parts of an antioxidant and 0.3-0.5 parts of a lubricant to obtain a mixed material; The above mixture and 15-20 parts of starch grafted dialkyl phosphate are melted, extruded and dried to obtain a transparent biodegradable film material.

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