A degradable environmentally friendly plastic film and preparation method thereof

Abstract

The present invention belongs to the technical field of polymer composite materials, and particularly relates to a degradable environmental protection plastic film and a preparation method thereof. The plastic film is made of polyacrylic acid, starch, modified SiO2 particles, benzoyl peroxide, silane coupling agent KH-570, and polyethylene glycol. The film has hydrophobicity, which can avoid the problems of the plastic film becoming soft and the strength decreasing due to the absorption of water by starch molecules. It can slow down the erosion of starch by microorganisms, increase the service life of the film, reduce the scattering of light, and reduce the impact on the light transmittance of the film.

Description

Technical Field

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

[0002] At present, various plastic films, such as PET film, PMMA film, PE film, etc., have been widely used in chemical, medical, pesticide and food fields. Among them, packaging films made of these plastic films account for the largest proportion. However, since most of these plastic films are non-degradable, they pose a great threat to the ecological environment and may even endanger human health or animal life. This is because the covalent bonds on the main chain of the polymer in the plastic are very strong, and it is difficult to degrade naturally when entering the environment. Burning is the most convenient way to deal with plastic pollution, but the waste gas generated by burning polymers will pollute the environment. Therefore, the development of degradable plastic films is of great significance.

[0003] At present, most degradable plastic films are made by mixing synthetic high molecular polymers with natural polymers. This type of film has achieved good results in terms of degradability. However, the addition of natural polymers such as starch, cellulose and other materials will cause some negative problems. For example: 1. Starch contains a large number of hydroxyl groups, which easily absorbs water molecules, causing the film structure to be destroyed, which may soften the plastic film and reduce its strength; 2. Starch is a polysaccharide that is easily eroded by microorganisms, which affects the life of the film; 3. When starch and high molecular polymers are mixed, uneven dispersion may affect the quality of the film and light transmittance. Summary of the invention

[0004] The present invention provides a degradable environmentally friendly plastic film and a preparation method thereof to overcome the drawbacks of the prior art. The film is hydrophobic, and can avoid the problem that starch molecules absorb water, causing the plastic film to become soft and the strength to decrease. It can slow down the erosion of starch by microorganisms, increase the service life of the film, reduce the scattering of light, and reduce the impact on the light transmittance of the film.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A degradable and environmentally friendly plastic film is provided, the raw materials of the plastic film are made of the following materials:

[0007] Polyacrylic acid: 40-60 parts by mass;

[0008] Starch: 20-30 parts by weight;

[0009] Modified SiO 2 Particles: 10-15 parts by mass;

[0010] Benzoyl peroxide: 2-4 parts by weight;

[0011] Silane coupling agent KH-570: 3 to 6 parts by mass;

[0012] Polyethylene glycol: 2 to 4 parts by weight;

[0013] The modified SiO 2 The particles have an incompletely closed cavity structure. The starch is modified by SiO 2 Inside the cavity of the particle, the modified SiO 2 The hydroxyl (-OH) groups on the surface of the particles in the solution are replaced by alkyl (-CH 3 ) group substitution, modified SiO 2 The diameter of the particles is 30 to 150 nm.

[0014] Starch and modified SiO 2 Particle bonding, modified SiO 2 The particle surface is -CH 3 (Methyl) replaces -OH (hydroxyl) to make it hydrophobic, thus avoiding the problem of starch molecules absorbing water and causing the plastic film to soften and lose strength. 2 The cavity of the particles can hold a portion of the starch inside, slowing down its erosion by microorganisms and increasing the service life of the film. 2 The particle size is small, about 30 to 150 nm. After loading starch, it is easy to composite with high molecular polymers. The size is 30 to 150 nm. The light scattering effect will be greatly reduced, which can reduce the impact on the transmittance of the original film.

[0015] As a further preferred degradable environmentally friendly plastic film.

[0016] Preferably, modified SiO 2 The preparation of particles comprises the following steps:

[0017] S11, dissolving 0.3 parts by mass of polyacrylic acid in 6-8 parts by mass of ammonia water, stirring for 1 hour, then adding 50-80 parts by mass of anhydrous ethanol, stirring for 2 hours, and finally adding 0.5-1 parts by mass of tetraethyl orthosilicate, continuing to stir and react for 5-10 hours, and finally washing with deionized water to obtain an open-pored SiO 2 particle;

[0018] S12, to 4 parts by mass of open-pore SiO 2 100 parts by mass of anhydrous ethanol was added to the particles, and then 1 to 2 parts by mass of hexamethyldiazaalkane was added and stirred for 3 to 6 hours, and then centrifuged to obtain modified SiO 2 particle.

[0019] During the synthesis, the amount of ammonia is critical. When the amount of ammonia is small, the micelles formed by polyacrylic acid are too large, and the micelles serve as the SiO2 2 Templates that are too large will result in open SiO 2 The particle size is too large. And the ammonia water forms SiO 2 It plays the role of catalyst in the reaction. When the amount is small, the reaction is slow and a closed-pore hollow SiO 2 Particles, which prevents starch from combining with external polyester. When the amount of ammonia is too much, the silicon source forms SiO 2 The reaction will be very fast, resulting in it not being able to grow on the micelle template, but directly forming a solid SiO 2 particle.

[0020] Modified SiO 2 The particles have a large number of hydroxyl groups (-OH) in the solution and are hydrophilic. Through hexamethyldiazaalkane modification, the hydroxyl groups are replaced by alkyl groups, making them hydrophobic.

[0021] Preferably, starch is modified SiO 2 The method for preparing the interior of the cavity of the particle comprises the following steps:

[0022] Add 6-9 parts by mass of starch to 50-80 parts by mass of deionized water, heat to dissolve, and then add 3-4.5 parts by mass of modified SiO 2 The particles were stirred for 10 min, then the temperature was lowered and allowed to stand until precipitation occurred. The white powder was immediately centrifuged to obtain white powder, which was then washed with cold water and ethanol.

[0023] After heating, the starch dissolves and enters the modified SiO 2 The particles are in the cavity, and after cooling, the starch will precipitate, and the modified SiO 2 The starch particles were mixed with starch, and then the outer starch was washed off with water to obtain starch in the modified SiO 2 The interior of the particle cavity.

[0024] The present invention also provides a method for preparing a degradable environmentally friendly plastic film, which comprises the following steps:

[0025] S21, feeding the raw materials described in claim 1 into an internal mixer and stirring them evenly, and then extruding the substrate melt;

[0026] S22, forming a degradable and environmentally friendly plastic film on a cooling roller with the melt in step S21.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) Compared with the original starch-based biodegradable film, this film is hydrophobic, which can avoid the problem of starch molecules absorbing water, causing the plastic film to become soft and the strength to decrease.

[0029] (2) Most starch is modified with SiO 2 The cavity inside the particles can slow down the erosion of starch by microorganisms and increase the service life of the film.

[0030] (3) Starch and modified SiO 2 After the particles are combined, their size is fixed at 30 to 150 nm, which can reduce the aggregation and the generation of oversized particles, reduce the scattering of light, and reduce the impact on the light transmittance of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 (a)-1(b) are respectively the modified SiO prepared in Example 1 2 Transmission electron micrographs and scanning electron micrographs of particles;

[0032] Figure 2 (a)-2(b) are SiO prepared in Comparative Example 1 and Comparative Example 2 respectively. 2 Transmission electron micrograph of particles;

[0033] Figure 3 is a photo of the degradable and environmentally friendly plastic film of Example 2;

[0034] Figure 4 are photos of plastic films prepared in Comparative Examples 3 and 4;

[0035] Figure 5 3 is the light transmittance curve of the plastic film prepared in Example 3, Comparative Example 3 and Comparative Example 4;

[0036] Figure 6 This is a scanning electron microscope photograph of the degradation of the degradable and environmentally friendly plastic film prepared in Example 3. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with embodiments and comparative examples.

[0038] Example 1

[0039] This embodiment provides a degradable and environmentally friendly plastic film and a preparation method thereof.

[0040] Modified SiO 2 Preparation of particles:

[0041] S11, 0.3 parts by mass of polyacrylic acid was dissolved in 6 parts by mass of ammonia water, stirred for 1 hour, then 50 parts by mass of anhydrous ethanol was added, stirred for 2 hours, and finally 0.5 parts by mass of tetraethyl orthosilicate was added, and the reaction was continued by stirring for 5 hours, and finally washed with deionized water to obtain an open-pored SiO 2 particle;

[0042] S12, to 4 parts by mass of open-pore SiO 2 100 parts by mass of anhydrous ethanol was added to the particles, and then 1 part by mass of hexamethyldiazepine was added and stirred for 3 hours, and then centrifuged to obtain modified SiO 2 particle.

[0043] Starch in modified SiO 2 Preparation method of the cavity interior of the particle:

[0044] Add 6 parts by mass of starch to 50 parts by mass of deionized water, heat to dissolve, and then add 3 parts by mass of modified SiO 2 The particles were stirred for 10 min, then the temperature was lowered and allowed to stand until precipitation occurred. The white powder was immediately centrifuged to obtain white powder, which was then washed with cold water and ethanol.

[0045] Preparation method of degradable environmentally friendly plastic film:

[0046] S21, 40 parts by mass of polyacrylic acid, 20 parts by mass of starch, 10 parts by mass of modified SiO 2 The particles, 2 parts by mass of benzoyl peroxide, 3 parts by mass of silane coupling agent KH-570 and 2 parts by mass of polyethylene glycol are fed into an internal mixer and stirred evenly, and then the substrate melt is extruded;

[0047] S22, forming a degradable and environmentally friendly plastic film on a cooling roller with the melt in step S21.

[0048] Example 2

[0049] This embodiment provides a degradable and environmentally friendly plastic film and a preparation method thereof.

[0050] Modified SiO 2 Preparation of particles:

[0051] S11, 0.3 parts by mass of polyacrylic acid was dissolved in 7 parts by mass of ammonia water, stirred for 1 hour, then 60 parts by mass of anhydrous ethanol was added, stirred for 2 hours, and finally 0.7 parts by mass of tetraethyl orthosilicate was added, and the reaction was continued by stirring for 8 hours, and finally washed with deionized water to obtain an open-pored SiO 2 particle;

[0052] S12, to 4 parts by mass of open-pore SiO 2100 parts by mass of anhydrous ethanol was added to the particles, and then 1.5 parts by mass of hexamethyldiazepine was added and stirred for 4 hours, and then centrifuged to obtain modified SiO 2 particle.

[0053] Starch in modified SiO 2 Preparation method of the cavity interior of the particle:

[0054] Add 8 parts by mass of starch to 60 parts by mass of deionized water, heat to dissolve, and then add 4 parts by mass of modified SiO 2 The particles were stirred for 10 min, then the temperature was lowered and allowed to stand until precipitation occurred. The white powder was immediately centrifuged to obtain white powder, which was then washed with cold water and ethanol.

[0055] Preparation method of degradable environmentally friendly plastic film:

[0056] S21, 50 parts by mass of polyacrylic acid, 15 parts by mass of starch, 12 parts by mass of modified SiO 2 The particles, 3 parts by mass of benzoyl peroxide, 4 parts by mass of silane coupling agent KH-570 and 3 parts by mass of polyethylene glycol are put into an internal mixer and stirred evenly, and then the substrate melt is extruded;

[0057] S22, forming a degradable and environmentally friendly plastic film on a cooling roller with the melt in step S21.

[0058] Example 3

[0059] This embodiment provides a degradable and environmentally friendly plastic film and a preparation method thereof.

[0060] Modified SiO 2 Preparation of particles:

[0061] S11, 0.3 parts by mass of polyacrylic acid was dissolved in 8 parts by mass of ammonia water, stirred for 1 hour, then 80 parts by mass of anhydrous ethanol was added, stirred for 2 hours, and finally 1 part by mass of tetraethyl orthosilicate was added, and the reaction was continued by stirring for 10 hours, and finally washed with deionized water to obtain an open-pored SiO 2 particle;

[0062] S12, to 4 parts by mass of open-pore SiO 2 100 parts by mass of anhydrous ethanol was added to the particles, and then 2 parts by mass of hexamethyldiazepine was added and stirred for 6 hours, and then centrifuged to obtain modified SiO 2 particle.

[0063] Starch in modified SiO 2 Preparation method of the cavity interior of the particle:

[0064] Add 9 parts by mass of starch to 80 parts by mass of deionized water, heat to dissolve, and then add 4.5 parts by mass of modified SiO 2 The particles were stirred for 10 min, then the temperature was lowered and allowed to stand until precipitation occurred. The white powder was immediately centrifuged to obtain white powder, which was then washed with cold water and ethanol.

[0065] Preparation method of degradable environmentally friendly plastic film:

[0066] S21, 60 parts by mass of polyacrylic acid, 30 parts by mass of starch, 15 parts by mass of modified SiO 2 The particles, 4 parts by mass of benzoyl peroxide, 6 parts by mass of silane coupling agent KH-570 and 4 parts by mass of polyethylene glycol are fed into an internal mixer and stirred evenly, and then the substrate melt is extruded;

[0067] S22, forming a degradable and environmentally friendly plastic film on a cooling roller with the melt in step S21.

[0068] Comparative Example 1

[0069] Provided is a method for preparing SiO 2 The method for preparing the particles is different from that in Example 1 in that the amount of ammonia water added in this comparative example is 3 parts by mass.

[0070] Comparative Example 2

[0071] Provided is a method for preparing SiO 2 The method for preparing the particles is different from that in Example 1 in that the amount of ammonia water added in this comparative example is 12 parts by mass.

[0072] Comparative Example 3

[0073] This comparative example is different from Example 1 in that no starch and modified SiO 2 particle.

[0074] Specific preparation method:

[0075] S21, 40 parts by mass of polyacrylic acid, 2 parts by mass of benzoyl peroxide, 3 parts by mass of silane coupling agent KH-570 and 2 parts by mass of polyethylene glycol are fed into an internal mixer and stirred evenly, and then the substrate melt is extruded;

[0076] S22, forming a degradable and environmentally friendly plastic film on a cooling roller with the melt in step S21.

[0077] Comparative Example 4

[0078] This comparative example is different from Example 1 in that no modified SiO 2 particle.

[0079] Specific preparation method:

[0080] S21, 40 parts by mass of polyacrylic acid, 20 parts by mass of starch, 2 parts by mass of benzoyl peroxide, 3 parts by mass of silane coupling agent KH-570 and 2 parts by mass of polyethylene glycol are fed into an internal mixer and stirred evenly, and then the substrate melt is extruded;

[0081] S22, forming a degradable and environmentally friendly plastic film on a cooling roller with the melt in step S21.

[0082] Figure 1 (a)-1(b) are respectively the modified SiO prepared in Example 1 2 Transmission electron micrographs and scanning electron micrographs of particles. It can be seen that the modified SiO 2 The particles have a cavity structure and an open-pore structure. The cavity can carry starch, and the open-pore structure allows starch to combine with organic polymers to form a film.

[0083] Figure 2 (a)-2(b) are SiO prepared in Comparative Example 1 and Comparative Example 2 respectively. 2 Transmission electron microscope photo of particles. This shows that too much or too little ammonia will not form Figure 1 (a) Similar structures.

[0084] Figure 3 is a photo of the degradable and environmentally friendly plastic film prepared in Example 2. Figure 4 The following are photos of the plastic films prepared in Comparative Examples 3 and 4. From the photos, it can be seen that the plastic film prepared without adding starch has the best light transmittance, while the transmittance decreases significantly after adding starch. In Example 2 of the present invention, the light transmittance effect is between the film prepared without adding starch and the film prepared by directly adding starch.

[0085] Figure 5 The transmittance curves of the degradable and environmentally friendly plastic films prepared in Example 3, Comparative Example 3 and Comparative Example 4 are shown. The transmittance spectra can be shown from the experimental results to show that the problem of significantly reduced transmittance caused by directly adding starch can be improved in the present invention.

[0086] Figure 6 This is a scanning electron microscope photo of the degradation of the degradable environmentally friendly plastic film prepared in Example 3. The microstructure shows that the film is dense at first, but after being immersed in water for 90 days, a large number of pores appear in the microstructure of the film, indicating that the film has been degraded, indicating that the plastic film prepared by the present invention is a degradable environmentally friendly plastic film.

[0087] Table 1 Water contact angle results of the degradable environmentally friendly plastic films prepared in the examples and comparative examples

[0088] sample Example 1 Example 2 Example 3 Comparative Example 3 Comparative Example 4 Water contact angle 132.4 125.3 128.5 72.5 86.7

[0089] The water contact angle data in Table 1 show that the coating prepared in the present invention has better hydrophobicity, which can reduce the absorption of water molecules in the environment by starch, thereby increasing the service life of the degradable environmentally friendly plastic film.

[0090] Those skilled in the art should understand that the above are only some specific embodiments of the present invention, rather than all embodiments. It should be noted that for those of ordinary skill in the art, many modifications and improvements can be made, and all modifications or improvements that do not exceed the scope of protection of the present invention should be regarded as the scope of protection of the present invention.

Claims

1. A degradable and environmentally friendly plastic film, characterized in that: The raw materials of plastic film are made of the following materials: Polyacrylic acid: 40-60 parts by mass; Starch: 20-30 parts by weight; Modified SiO2 particles: 10-15 parts by mass; Benzoyl peroxide: 2-4 parts by mass; Silane coupling agent KH-570: 3~6 parts by mass; Polyethylene glycol: 2-4 parts by mass; The modified SiO2 particles have an incompletely closed cavity structure, the starch is inside the cavity of the modified SiO2 particles, the hydroxyl (-OH) groups on the surface of the modified SiO2 particles in the solution are replaced by methyl (-CH3) groups, and the diameter of the modified SiO2 particles is 30~150nm.

2. The degradable and environmentally friendly plastic film according to claim 1, characterized in that: The preparation of modified SiO2 particles comprises the following steps: S11, dissolving 0.3 parts by mass of polyacrylic acid in 6-8 parts by mass of ammonia water, stirring for 1 hour, then adding 50-80 parts by mass of anhydrous ethanol, stirring for 2 hours, and finally adding 0.5-1 parts by mass of tetraethyl orthosilicate, continuing to stir and react for 5-10 hours, and finally washing with deionized water to obtain open-pored SiO2 particles; S12. Add 100 parts by mass of anhydrous ethanol to 4 parts by mass of open-pored SiO2 particles, then add 1 to 2 parts by mass of hexamethyldiazapine and stir for 3 to 6 hours, and then centrifuge to obtain modified SiO2 particles.

3. The degradable and environmentally friendly plastic film according to claim 1, characterized in that: The method for preparing the starch inside the cavity of the modified SiO2 particles comprises the following steps: Add 6-9 parts by mass of starch to 50-80 parts by mass of deionized water, heat to dissolve, then add 3-4.5 parts by mass of modified SiO2 particles, stir for 10 minutes, then let it stand to precipitate, immediately centrifuge to obtain white powder, and then wash the white powder with cold water and ethanol.

4. A method for preparing the degradable environmentally friendly plastic film according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: S21, feeding the raw materials described in claim 1 into an internal mixer and stirring them evenly, and then extruding the substrate melt; S22, forming a degradable and environmentally friendly plastic film on a cooling roller with the melt in step S21.

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