CN102558589B - Preparation method of formaldehyde cross-linked gelatin/polyvinyl alcohol(PVA) composite membrane - Google Patents

Abstract

A method for preparing a formaldehyde-crosslinked gelatin/PVA composite film relates to a method for preparing a gelatin/PVA composite film. After mixing polyvinyl alcohol aqueous solution and gelatin aqueous solution, a certain amount of plasticizer and formaldehyde are added, and then Store at 0-10°C for 2-5 hours, then stir evenly in a constant temperature water bath, pour the evenly mixed mixture into a mold for natural casting, and dry the mixture at room temperature to obtain formaldehyde-crosslinked gelatin/PVA Composite film. The product prepared by the invention not only has good compatibility and degradability, but also has better mechanical properties than the general gelatin/PVA composite film.

Description

A kind of preparation method of formaldehyde cross-linked gelatin/PVA composite film

technical field

The invention relates to a preparation method of a gelatin/PVA composite film, in particular to a preparation method of a formaldehyde-crosslinked gelatin/PVA composite film.

Background technique

In recent years, people have become more and more aware of the serious harm to the environment caused by the white pollution caused by the extensive use of polyvinyl chloride packaging materials. People have also begun to study more and more new degradable composite materials. Most of these composite materials are based on the degradability of natural polymer materials and the good mechanical properties and mechanical properties of synthetic polymer materials. Polymers and synthetic polymers are combined to make composite materials that combine the advantages of the two types of materials. There are many types of such composite materials, and gelatin/PVA composite film is one of them. Gelatin is a protein composed of various amino acids and derived from animal bodies. It is a natural polymer material with good biocompatibility and degradability. Polyvinyl alcohol (PVA) is a non-toxic, non-toxic An irritating hydrophilic polymer with good biocompatibility, film-forming properties and good mechanical properties. The common gelatin/PVA composite film made by the existing technology can control its compatibility and other issues better by controlling the ratio of the two components in the film, but the mechanical properties and solubility of the film are often not as good as those High use requirements, but the present invention finally makes the gelatin/PVA composite film obtained have better mechanical properties than ordinary films by adding cross-linking agent formaldehyde and plasticizer in the film-making process, and improving other process conditions .

Contents of the invention

In order to improve the mechanical properties of ordinary gelatin/PVA composite film, the invention provides a preparation method of formaldehyde crosslinked gelatin/PVA composite film.

In order to achieve the above object, the technical solution of the present invention is achieved in that a kind of preparation method of formaldehyde cross-linked gelatin/PVA composite film comprises the following steps:

(1) Preparation of polyvinyl alcohol (PVA) solution: Weigh 4-11 parts by weight of polyvinyl alcohol into a three-necked flask, then measure 80-105 parts by weight of distilled water into the three-necked flask, and place the flask at 80-90 Stir in a constant temperature water bath at ℃ until the polyvinyl alcohol is completely dissolved to obtain an aqueous solution of polyvinyl alcohol, namely solution A;

(2) Preparation of gelatin solution: Weigh 5-10 parts by weight of gelatin into a beaker, then add 80-100 parts by weight of distilled water into the beaker, swell at room temperature for 30 minutes, and stir in a constant temperature water bath at 50°C until The gelatin is completely dissolved, and the impurities are removed by filtration to obtain a gelatin solution, namely B solution;

(3) Preparation of gelatin/PVA composite film: Weigh the two solutions A and B according to the weight ratio of 3:1-5:1 and add them to a three-necked flask, then add plasticizer and formaldehyde, and stir at a low temperature of 0-10 Store at ℃ for 2-5 hours, then stir in a constant temperature water bath at 30-70℃ for 4 hours, pour the evenly mixed mixture into a mold and cast it naturally, and let the mixture dry at room temperature to obtain gelatin/PVA composite membrane.

In the A solution, the weight ratio of polyvinyl alcohol to water is preferably 1:9, in the B solution, the weight ratio of gelatin to water is preferably 1:9, and the weight ratio of the two solutions A and B is preferably 4: 1.

The plasticizer is ethylene glycol, glycerin or PEG200, and its consumption is 0.6% of the total weight of the two solutions of A and B.

The dosage of the formaldehyde is 0.03%-0.08% of the total weight of the two solutions of A and B.

Beneficial effects: the gelatin/PVA composite film prepared by the present invention not only has good compatibility and certain degradability, but also has better mechanical properties than ordinary films, and improves the tensile strength and water resistance of the composite film; In the method of the present invention, especially after a period of low-temperature treatment, the mechanical properties of the film are also assisted; the product of the present invention can be applied in the field of agricultural mulch film and other article packaging.

Detailed ways

A preparation method of formaldehyde cross-linked gelatin/PVA composite film, comprising the following steps:

(1) Preparation of polyvinyl alcohol solution: Weigh 4-11 parts by weight of polyvinyl alcohol into a three-necked flask, then weigh 80-105 parts by weight of distilled water into the three-necked flask, and place the flask at a constant temperature of 80-90°C Stir in a water bath until the polyvinyl alcohol is completely dissolved to obtain an aqueous solution of polyvinyl alcohol, i.e. solution A;

(2) Preparation of gelatin solution: Weigh 5-10 parts by weight of gelatin into a beaker, then add 80-100 parts by weight of distilled water into the beaker, swell at room temperature for 30 minutes, and stir in a constant temperature water bath at 50°C until The gelatin is completely dissolved, and the impurities are removed by filtration to obtain a gelatin solution, namely B solution;

(3) Preparation of gelatin/PVA composite film: Weigh the two solutions A and B according to the weight ratio of 3:1-5:1 and add them to a three-necked flask, then add plasticizer and formaldehyde, and stir at a low temperature of 0-10 Store at ℃ for 2-5 hours, then stir in a constant temperature water bath at 30-70℃ for 4 hours, pour the evenly mixed solution into a mold and cast it naturally, and let the mixed solution dry at room temperature to obtain formaldehyde cross-linked gelatin /PVA composite film.

In the A solution, the weight ratio of polyvinyl alcohol to water is preferably 1:9, in the B solution, the weight ratio of gelatin to water is preferably 1:9, and the weight ratio of the two solutions A and B is preferably 4: 1.

The plasticizer is ethylene glycol, glycerin or PEG200, and its consumption is 0.6% of the total weight of the two solutions of A and B.

The dosage of the formaldehyde is 0.03%-0.08% of the total weight of the two solutions of A and B.

Mechanical properties test: According to the national standard GB/T1040.3, the film is cut into sub-prismatic shapes, placed in a desiccator at room temperature (the bottom of the desiccator is a saturated KBr solution) and tested after equilibrating for 60 hours. The distance between the test fixtures is 25mm. The speed is 50mm/min, the test is carried out at room temperature, and 5 to 7 samples are tested, and the arithmetic mean value is taken.

Dissolution rate test method: Cut the film into a square of 1cm×1cm, first dry it and weigh its mass m ₁ , then immerse the film in a small beaker containing 10mL distilled water for 60min, absorb the surface moisture with filter paper, and finally Then put the film into an oven to dry, weigh its mass m ₂ , and its dissolution rate = (m ₁ -m ₂ )/m ₁ ×100%.

Example 1

Weigh 10g of polyvinyl alcohol into a three-necked flask, add 90g of distilled water, mechanically stir in a constant temperature water bath at 90°C until it is completely dissolved, and then filter to remove impurities to obtain an aqueous solution of polyvinyl alcohol with a solution concentration of 10%;

Weigh 10g of gelatin and place it in a beaker, add 90g of distilled water, first swell at room temperature for 30min, then stir in a constant temperature water bath at 50°C until it is completely dissolved, then filter to remove impurities, and obtain a gelatin solution with a solution concentration of 10%;

Add the above polyvinyl alcohol solution and gelatin solution into a 250ml three-necked flask at a weight ratio of 4:1, then add 0.6% plasticizer ethylene glycol with a total weight of the two solutions and 0.08% formaldehyde with a total weight of the two solutions, and then Store at 0°C for 5 hours, then mechanically stir and react in a constant temperature water bath at 50°C for 4 hours, pour the evenly mixed mixture into a mold and cast it naturally, and dry the mixture at room temperature to obtain gelatin/PVA Composite film.

The mechanical performance test results of the composite film are: the tensile strength is 38.3MPa, the elongation at break is 501%, and the dissolution rate test result of the film is 11.8%.

Example 2

Weigh 10g of polyvinyl alcohol into a three-necked flask, add 90g of distilled water, mechanically stir in a constant temperature water bath at 90°C until it is completely dissolved, and then filter to remove impurities to obtain an aqueous solution of polyvinyl alcohol with a solution concentration of 10%;

Weigh 10g of gelatin and place it in a beaker, add 90g of distilled water, first swell at room temperature for 30min, then stir in a constant temperature water bath at 50°C until it is completely dissolved, then filter to remove impurities, and obtain a gelatin solution with a solution concentration of 10%;

The above-mentioned polyvinyl alcohol solution and gelatin solution were added into a 250ml three-necked flask in a weight ratio of 4:1, and then 0.6% of the plasticizer glycerin and 0.03% of the total weight of the two solutions were added. Store at ℃ for 2 hours, then mechanically stir and react in a constant temperature water bath at 30℃ for 4 hours, pour the evenly mixed mixture into a mold and cast it naturally, and let the mixture dry at room temperature to obtain a gelatin/PVA composite membrane.

The test results of the mechanical properties of the composite film are: the tensile strength is 30.3MPa, the elongation at break is 539%, and the test result of the dissolution rate of the film is 17.6%.

Example 3

Weigh 10g of polyvinyl alcohol into a three-necked flask, add 90g of distilled water, mechanically stir in a constant temperature water bath at 90°C until it is completely dissolved, and then filter to remove impurities to obtain an aqueous solution of polyvinyl alcohol with a solution concentration of 10%;

Weigh 10g of gelatin and place it in a beaker, add 90g of distilled water, first swell at room temperature for 30min, then stir in a constant temperature water bath at 50°C until it is completely dissolved, then filter to remove impurities, and obtain a gelatin solution with a solution concentration of 10%;

The above-mentioned polyvinyl alcohol solution and gelatin solution were added into a 250ml three-necked flask at a weight ratio of 3:1, and then 0.6% of the plasticizer PEG200 with a total weight of the two solutions and 0.06% formaldehyde with a total weight of the two solutions were added. Store at ℃ for 2 hours, then mechanically stir and react in a constant temperature water bath at 50℃ for 4 hours, pour the evenly mixed mixture into a mold and cast it naturally, and let the mixture dry at room temperature to obtain a gelatin/PVA composite membrane.

The test results of the mechanical properties of the composite film are: the tensile strength is 33.6MPa, the elongation at break is 535%, and the test result of the dissolution rate of the film is 16.1%.

Example 4

Weigh 10g of polyvinyl alcohol into a three-necked flask, add 90g of distilled water, mechanically stir in a constant temperature water bath at 90°C until it is completely dissolved, and then filter to remove impurities to obtain an aqueous solution of polyvinyl alcohol with a solution concentration of 10%;

Weigh 10g of gelatin and place it in a beaker, add 90g of distilled water, first swell at room temperature for 30min, then stir in a constant temperature water bath at 50°C until it is completely dissolved, then filter to remove impurities, and obtain a gelatin solution with a solution concentration of 10%;

Add the above-mentioned polyvinyl alcohol solution and gelatin solution into a 250ml three-necked flask at a weight ratio of 5:1, then add 0.6% plasticizer ethylene glycol with a total weight of the two solutions and 0.08% formaldehyde with a total weight of the two solutions, and then Store at 5°C for 4 hours, then mechanically stir and react in a constant temperature water bath at 70°C for 4 hours, pour the evenly mixed mixture into a mold and cast it naturally, and dry the mixture at room temperature to obtain gelatin/PVA Composite film.

The test results of the mechanical properties of the composite film are: the tensile strength is 36.5MPa, the elongation at break is 531%, and the test result of the dissolution rate of the film is 9.6%.

Comparative example 1

Weigh 10g of polyvinyl alcohol into a three-necked flask, add 90g of distilled water, mechanically stir in a constant temperature water bath at 90°C until it is completely dissolved, and then filter to remove impurities to obtain an aqueous solution of polyvinyl alcohol with a solution concentration of 10%;

Weigh 10g of gelatin and place it in a beaker, add 90g of distilled water, first swell at room temperature for 30min, then stir in a constant temperature water bath at 50°C until it is completely dissolved, then filter to remove impurities, and obtain a gelatin solution with a solution concentration of 10%;

Add the above polyvinyl alcohol solution and gelatin solution into a 250ml three-neck flask at a weight ratio of 4:1, add 0.6% plasticizer ethylene glycol of the total weight of the two solutions, and store them at 0°C for 5 hours. The reaction was mechanically stirred in a constant temperature water bath at 50°C for 4 hours, and the uniformly mixed mixture was poured into a mold for natural casting, and the mixture was dried at room temperature to obtain a gelatin/PVA composite film.

The test results of the mechanical properties of the composite film are: the tensile strength is 19.8MPa, the elongation at break is 610%, and the test result of the dissolution rate of the film is 32.9%.

By comparison between the comparative examples and the examples, it can also be seen that when gelatin and PVA are in the same ratio in the composite film, the elongation at break of the composite film decreases after adding formaldehyde, but the tensile strength of the composite film decreases. At the same time, the dissolution rate of the film decreased after adding formaldehyde, which can enhance its water resistance.

Claims (1)

1. the preparation method of formaldehyde crosslinking gelatin/PVA composite membrane is characterized in that: comprise following step:

(1) preparation of polyvinyl alcohol solution: the polyvinyl alcohol that takes the 4-11 weight part adds there-necked flask, the distilled water that adds again the 80-105 weight part, flask is placed in the water bath with thermostatic control of 80-90 ℃ is stirred to polyvinyl alcohol and dissolves fully, obtain polyvinyl alcohol water solution, i.e. PVA solution;

(2) preparation of gelatin solution: the gelatin that takes the 5-10 weight part adds in beaker, the distilled water that adds again the 80-100 weight part after swelling 30min, is stirred to gelatin and dissolves fully under room temperature in the water bath with thermostatic control of 50 ℃, after removing by filter impurity, namely obtain gelatin solution;

(3) preparation of gelatin/PVA composite membrane: above-mentioned PVA solution and gelatin solution are joined in there-necked flask by weight 3:1-5:1, add again softening agent and formaldehyde, preserved 2-5 hour under 0-10 ℃ of low temperature after stirring, then stirred 4 hours in the water bath with thermostatic control of 30-70 ℃, pour the mixed solution that mixes in mould natural curtain coating, make mixed solution at room temperature dry, namely obtain gelatin/PVA composite membrane;

Described softening agent is ethylene glycol, glycerine or PEG200, and its consumption is 0.6% of PVA solution and gelatin solution gross weight;

The consumption of described formaldehyde is the 0.03%-0.08% of PVA solution and gelatin solution gross weight.