CN101870791B - A kind of preparation method of hygroscopic film - Google Patents

Abstract

The embodiment of the invention discloses a method for preparing a hygroscopic film. Polyvinylalcohol, glycerol and water are mixed and heated to form hydrogel, wherein the polyvinylalcohol is used as a substrate. The polyvinylalcohol and the glycerol comprise a large number of hydroxide radicals which are easy to hold gaseous water molecules in air so as to fulfill the aim of absorbing moisture. The glycerol and the water are used for endowing the polyvinylalcohol with flexibility under the heating condition, so the prepared hygroscopic film has flexibility. Polymethylacrylic acid has a spacial network structure; carboxyl groups in molecular chains absorb the gaseous water molecules in the air first; and then the water molecules enter the internal spacial network; therefore, the water molecules in the air are continuously absorbed until balance. Compared with the prior art, the method has the advantages of simple and easily controllable operation; and experiment results show that the prepared hygroscopic film has good hygroscopic property.

Description

A kind of preparation method of hygroscopic film

technical field

The invention relates to the technical field of moisture absorption, and more specifically, relates to a method for preparing a moisture absorption film.

Background technique

Air humidity is a physical quantity that indicates the degree of dryness of the atmosphere, and is closely related to human life. At a given temperature, the less water vapor there is in a given volume of air, the drier the air; the more water vapor, the wetter the air. If the air humidity is too high, it will corrode and damage various metals, food, wood, etc. For example, in a humid environment, metal materials tend to form a condensed water film on the surface, resulting in electrochemical corrosion; a humid environment is suitable for the growth and reproduction of mold and pests, so food is prone to deterioration in a humid environment. Therefore, air dehumidification is a ubiquitous problem.

Chinese patent CN1284850A discloses an absorbent article comprising a microporous film made by stretching a thermoplastic resin and inorganic filler mixture in at least one direction. However, absorbent articles employing such microporous films have unsatisfactory absorbent properties.

In the prior art, the Chinese patent 200910260217.5 applied for by the present invention provides a method for preparing a film-like hygroscopic material. The preparation method uses methacrylic acid as a raw material, and polymerizes under the action of a crosslinking agent and an initiator to obtain a hygroscopic material. The film-like hygroscopic material is prepared by a mold method, and the preparation process is complicated.

Contents of the invention

In view of this, the technical problem to be solved by the present invention is to provide a method for preparing a hygroscopic film, and the purpose is to provide a simple and easy method to prepare the hygroscopic film.

The invention provides a method for preparing a hygroscopic film, comprising:

mixing polyvinyl alcohol, glycerin and water to obtain a mixture, and heating the mixture to obtain a colloid;

Add polymethacrylic acid in the colloid, fully react;

The fully reacted product was knife coated into a film and dried.

Preferably, it also includes:

Molecular sieve powder is added to the colloid.

Preferably, the weight ratio of the molecular sieve powder to polyvinyl alcohol is 0.5-2:10.

Preferably, the molecular sieve powder is 80-120 mesh, 1- prepared by crushing molecular sieves.

Preferably, the weight ratio of polymethacrylic acid to polyvinyl alcohol is 0.05˜0.15:10.

Preferably, the weight ratio of glycerin and polyvinyl alcohol is 1-5:10.

Preferably, it also includes:

Sodium benzoate was added to the gel.

Preferably, it also includes:

To the mixture was added n-octanol.

Preferably, the heating is specifically:

Heat at 90-120°C for 3-10 minutes.

Preferably, the drying is specifically:

Bake at a temperature of 90-120° C. for 3-4 hours.

It can be seen from the above-mentioned technical scheme that the present invention provides a method for preparing a hygroscopic film. Polyvinyl alcohol, glycerin and water are mixed and heated, and the polyvinyl alcohol is used as a matrix, and polyvinyl alcohol, glycerin and water are heated to become Hydrogels. Both polyvinyl alcohol and glycerin contain a large number of hydroxyl groups, which can easily catch gaseous water molecules in the air to achieve the purpose of moisture absorption. Glycerin and water are used to give polyvinyl alcohol flexibility under heating conditions, so that the prepared hygroscopic film has softness. Polymethacrylic acid is a kind of spatial network structure. Firstly, the carboxyl group in the molecular chain absorbs the gaseous water molecules in the air, and then allows the water molecules to enter the internal space network, so as to continuously absorb the water molecules in the air until the equilibrium. Compared with the prior art, the invention is simple in operation and easy to control, and the experimental results show that the prepared hygroscopic film has good hygroscopic performance.

Detailed ways

The following clearly and completely describes the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The embodiment of the invention discloses a method for preparing a hygroscopic film to improve the hygroscopic performance of the material.

The invention provides a method for preparing a hygroscopic film, comprising:

mixing polyvinyl alcohol, glycerin and water to obtain a mixture, and heating the mixture to obtain a colloid;

Add polymethacrylic acid in the colloid, fully react;

The fully reacted product is scraped into a film and dried to prepare a hygroscopic film.

Polyvinyl alcohol is a polyhydric polymer, which can easily catch the gaseous water molecules in the air to achieve the purpose of moisture absorption. For polyvinyl alcohol, it is preferable to choose polyvinyl alcohol grades with very good water solubility, such as polyvinyl alcohol 1788, but not limited thereto, which is conducive to the preparation of films;

The weight ratio of the glycerol to polyvinyl alcohol is preferably 1-5:10, more preferably 1-3:10.

Glycerin contains a large number of hydroxyl groups, which can easily catch gaseous water molecules in the air to achieve the purpose of moisture absorption.

Glycerin and water are added to give polyvinyl alcohol flexibility under heating conditions, and polyvinyl alcohol, glycerin and water are heated to become hydrogels, thereby making the prepared film flexible.

The heating temperature is preferably 90-120°C, more preferably 100°C. The heating time is preferably 3 to 10 minutes, more preferably 3 to 5 minutes.

For heating mode, the present invention is not particularly limited, can adopt and put polyvinyl alcohol, glycerin and water into the beaker, stir evenly with glass rod, then put the beaker on the electric stove and boil under the stirring condition.

The weight ratio of polymethacrylic acid to polyvinyl alcohol is preferably 0.05˜0.15:10, more preferably 0.1˜0.15:10.

Polymethacrylic acid is an organic polymer hygroscopic material with very good moisture absorption capacity and moisture absorption rate. It is a space network structure. It first absorbs gaseous water molecules in the air by the carboxyl groups in the molecular chain, and then allows the water molecules to enter the interior. The space network, which continuously absorbs water molecules in the air until equilibrium. A small amount of polymethacrylic acid can be mixed with the above-mentioned hydrogel to improve the hygroscopic performance of the material.

According to the present invention, there is no special limitation on the way of scraping the film to form a film. It is preferable to take part of the colloid and place it on a glass plate, and use a triangular plate to scrape and coat the colloid on the glass plate to form a film.

The drying is preferably specifically:

Bake at a temperature of 90-120°C for 3-4 hours, more preferably at a temperature of 100°C for 3-4 hours. There is no special limitation on the drying tool, and an oven can be used for baking.

According to the present invention, it also includes:

To the mixture was added n-octanol.

The weight ratio of the n-octanol to the polyvinyl alcohol is preferably 0.05˜0.2:10, more preferably 0.05˜0.1:10.

n-octanol has the function of defoaming, which can reduce the blisters in the prepared film.

According to the present invention, it also includes:

Molecular sieve powder is added to the colloid, and the weight ratio of the molecular sieve powder to polyvinyl alcohol is preferably 0.5-2:10, more preferably 1-1.5:10.

The molecular sieve powder is preferably 80-120 mesh.

的分子筛粉碎制得，更优选由的分子筛粉碎制得。The molecular sieve powder is preferably from 1 to

The molecular sieves are pulverized, more preferably by prepared by crushing molecular sieves.

The composition of the molecular sieve is not particularly limited in the present invention.

Molecular sieve is a traditional hygroscopic material with good hygroscopic properties. It physically absorbs water through its own many pores. Its moisture absorption rate is very high and its static equilibrium point is very low.

The purpose of adding a small amount of molecular sieve powder is to further improve the hygroscopic performance of the film.

Wherein, the purpose of sufficient reaction can be achieved by stirring with a glass rod, and the time for sufficient reaction is preferably 20-60 minutes, more preferably 30 minutes.

According to the present invention, it also includes:

Sodium benzoate was added to the gel.

The weight ratio of the sodium benzoate to the polyvinyl alcohol is preferably 0.01˜0.05:10, more preferably 0.02˜0.04:10.

Sodium benzoate is a stabilizer, which can enhance the stability of the prepared hygroscopic film.

According to the present invention, the hygroscopic capacity test method is:

1g of the sample to be tested was kept at 100°C to a constant weight. Then the weighing is accurate to 0.01g, the weighing speed should be fast, and the time of exposure to the air should be minimized. Put the sample into a constant temperature and humidity chamber with air stirring and a relative humidity of 90%, at a temperature of 30°C, until the difference between two consecutive weighings at an interval of 1 hour does not exceed 5mg, then take out the sample and weigh it. Calculate the moisture absorption capacity according to the formula:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; G</span>}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>$

In the formula:

M is the moisture absorption capacity (%),

G is the increased weight (g) of the sample after absorbing moisture,

W is the weight (g) of the sample before moisture absorption.

In order to further understand the technical solution of the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than limiting the claims of the present invention.

Example 1

Take 10 grams of polyvinyl alcohol 1788 and put it into a 500 ml beaker, then add 1 gram of glycerin, stir it evenly with a glass rod, then add 70 grams of water to the beaker, stir it evenly with a glass rod while adding water, and then stir it under the condition of stirring Put the beaker on the electric stove and boil for 5 minutes;

Remove the beaker from the electric stove, add 0.15 g of polymethacrylic acid to the beaker, and stir evenly with a glass rod;

Then add 0.02 gram of sodium benzoate and stir evenly with a glass rod;

After resting the beaker for 30 minutes, take out part of the colloid in the beaker and put it on a glass plate, scrape and coat the colloid on the glass plate with a triangular plate to form a film, then put the glass plate in an oven at 100°C and dry it for 4 hours. The film on the glass plate is peeled off slowly to form a polyvinyl alcohol hygroscopic film.

The film had a moisture absorption capacity of 62% at a relative humidity of 90% RH and a temperature of 30°C.

Example 2

Take 10 grams of polyvinyl alcohol 1788 and put it into a 500 ml beaker, then add 1 gram of glycerin, stir evenly with a glass rod, then add 0.05 g of n-octanol and 70 g of water to the beaker, and stir evenly with a glass rod while adding water , and then put the beaker on the electric stove and boil for 5 minutes under the condition of stirring;

Remove the beaker from the electric stove, add 0.15 g of polymethacrylic acid to the beaker, and stir evenly with a glass rod;

Then add 0.02 gram of sodium benzoate and stir evenly with a glass rod;

的分子筛粉碎制得100目的分子筛粉；Will

The molecular sieve pulverization made 100 mesh molecular sieve powder;

Add 1 gram of 100-mesh molecular sieve powder into the beaker and stir evenly with a glass rod;

After resting the beaker for 30 minutes, take out part of the colloid in the beaker and put it on a glass plate, scrape and coat the colloid on the glass plate with a triangular plate to form a film, then put the glass plate in an oven at 100°C and dry it for 4 hours. The film on the glass plate is peeled off slowly to form a polyvinyl alcohol hygroscopic film.

The film had a moisture absorption capacity of 69% at a relative humidity of 90% RH and a temperature of 30°C.

Example 3

Take 10 grams of polyvinyl alcohol 1788 and put it into a 500 ml beaker, then add 3 grams of glycerin, stir well with a glass rod, then add 0.1 g of n-octanol and 90 grams of water to the beaker, and stir evenly with a glass rod while adding water , then put the beaker on the electric stove and boil for 3 minutes under the condition of stirring;

Remove the beaker from the electric stove, add 0.1 gram of polymethacrylic acid to the beaker, and stir evenly with a glass rod;

Then add 0.04 gram of sodium benzoate and stir evenly with a glass rod;

的分子筛粉碎制得80目的分子筛粉；Will

Molecular sieve pulverization made 80 mesh molecular sieve powder;

Add 1.5 grams of 80-mesh molecular sieve powder into the beaker and stir evenly with a glass rod;

After resting the beaker for 30 minutes, take out part of the colloid in the beaker and put it on a glass plate, scrape and coat the colloid on the glass plate with a triangular plate to form a film, then put the glass plate in an oven at 100°C and dry it for 3 hours. The film on the glass plate is peeled off slowly to form a polyvinyl alcohol hygroscopic film.

The film had a moisture absorption capacity of 73% at a relative humidity of 90% RH and a temperature of 30°C.

Example 4

Put 10 grams of polyvinyl alcohol 1788 into a 500 ml beaker, then add 2 grams of glycerin, stir well with a glass rod, then add 0.1 g of n-octanol and 80 grams of water to the beaker, and stir evenly with a glass rod while adding water , and then put the beaker on the electric stove and boil for 5 minutes under the condition of stirring;

Remove the beaker from the electric stove, add 0.1 gram of polymethacrylic acid to the beaker, and stir evenly with a glass rod;

Then add 0.02 gram of sodium benzoate and stir evenly with a glass rod;

的分子筛粉碎制得120目的分子筛粉；Will

Molecular sieve pulverization made 120 mesh molecular sieve powder;

Add 1.5 grams of 120-mesh molecular sieve powder into the beaker and stir evenly with a glass rod;

After resting the beaker for 30 minutes, take out part of the colloid in the beaker and put it on a glass plate, scrape and coat the colloid on the glass plate with a triangular plate to form a film, then put the glass plate in an oven at 100°C and dry it for 3 hours. The film on the glass plate is peeled off slowly to form a polyvinyl alcohol hygroscopic film.

The film had a moisture absorption capacity of 71% at a relative humidity of 90% RH and a temperature of 30°C.

Example 5

Take 10 grams of polyvinyl alcohol 1788 into a 500 ml beaker, then add 3 grams of glycerin, stir well with a glass rod, then add 0.05 g of n-octanol and 70 grams of water to the beaker, and stir evenly with a glass rod while adding water , then put the beaker on the electric stove and boil for 3 minutes under the condition of stirring;

Remove the beaker from the electric stove, add 0.15 g of polymethacrylic acid to the beaker, and stir evenly with a glass rod;

Then add 0.04 gram of sodium benzoate and stir evenly with a glass rod;

的分子筛粉碎制得120目的分子筛粉；Will

Molecular sieve pulverization made 120 mesh molecular sieve powder;

Add 1 gram of 120-mesh molecular sieve powder into the beaker and stir evenly with a glass rod;

After resting the beaker for 30 minutes, take out part of the colloid in the beaker and put it on a glass plate, scrape and coat the colloid on the glass plate with a triangular plate to form a film, then put the glass plate in an oven at 100°C and dry it for 3.5 hours. The film on the glass plate is peeled off slowly to form a polyvinyl alcohol hygroscopic film.

The film had a moisture absorption capacity of 72% at a relative humidity of 90% RH and a temperature of 30°C.

Example 6

Take 10 grams of polyvinyl alcohol 1788 and put it into a 500 ml beaker, then add 3 grams of glycerin, stir evenly with a glass rod, then add 0.08 g of n-octanol and 90 g of water to the beaker, and stir evenly with a glass rod while adding water , and then put the beaker on the electric stove and boil for 4 minutes under the condition of stirring;

Remove the beaker from the electric stove, add 0.13 g of polymethacrylic acid to the beaker, and stir evenly with a glass rod;

Then add 0.02 gram of sodium benzoate and stir evenly with a glass rod;

的分子筛粉碎制得80目的分子筛粉；Will

Molecular sieve pulverization made 80 mesh molecular sieve powder;

Add 1.2 grams of 80-mesh molecular sieve powder into the beaker and stir evenly with a glass rod;

After resting the beaker for 30 minutes, take out part of the colloid in the beaker and put it on a glass plate, scrape and coat the colloid on the glass plate with a triangular plate to form a film, then put the glass plate in an oven at 100°C and dry it for 4 hours. The film on the glass plate is peeled off slowly to form a polyvinyl alcohol hygroscopic film.

The film had a moisture absorption capacity of 70% at a relative humidity of 90% RH and a temperature of 30°C.

It can be seen from the above examples that the operation of the present invention is simple and easy to control, and the experimental results show that the prepared hygroscopic film has good hygroscopic performance.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. a preparation method of hygroscopic film, is characterized in that, comprises: mixing polyvinyl alcohol, glycerin and water to obtain a mixture, and heating the mixture to obtain a colloid; Adding polymethacrylic acid to the colloid for full reaction, the weight ratio of polymethacrylic acid and polyvinyl alcohol is 0.05-0.15:10; scraping the fully reacted product to form a film and drying. 2. preparation method according to claim 1, is characterized in that, also comprises: Molecular sieve powder is added to the colloid. 3. The preparation method according to claim 2, characterized in that the molecular sieve powder and polyvinyl alcohol have a weight ratio of 0.5 to 2:10. 4. the preparation method according to claim 2 is characterized in that, described molecular sieve powder is 80～120 meshes, by

prepared by crushing molecular sieves. 5. The preparation method according to claim 1, characterized in that the glycerin and polyvinyl alcohol are in a weight ratio of 1 to 5:10. 6. The preparation method according to any one of claims 1 to 5, further comprising: Sodium benzoate was added to the gel. 7. The preparation method according to any one of claims 1 to 5, further comprising: To the mixture was added n-octanol. 8. The preparation method according to any one of claims 1 to 5, wherein the heating is specifically: Heating at 90-120°C for 3-10 minutes. 9. The preparation method according to any one of claims 1 to 5, characterized in that, the drying is specifically: Bake at a temperature of 90-120° C. for 3-4 hours.