CN108383917B - A kind of multifunctional cellulose film and preparation method thereof - Google Patents

Abstract

The invention discloses a multifunctional cellulose film and a preparation method thereof. The cellulose is oxidized with sodium periodate and then chemically grafted with polyethyleneimine. After the reaction product is centrifuged, the obtained precipitate is washed, suction filtered, and thermally solidified to form a multifunctional cellulose membrane. The cellulose film of the present invention has the properties of water resistance, oil resistance, ultraviolet absorption and environmental sensitivity, and can be used for glass exterior walls, display exterior screens, environmental humidity detectors, etc., and has the functions of absorbing ultraviolet rays, preventing pollution and scratches. injury effect.

Description

A kind of multifunctional cellulose film and preparation method thereof

technical field

The invention belongs to the field of self-cleaning material development, and particularly relates to a multifunctional cellulose film and a preparation method thereof.

Background technique

Plastic products undergo structural changes due to the irradiation of ultraviolet rays of the sun, resulting in discoloration, brittleness and hardening, so the scope of application is limited. At present, with the expansion of the application field of polymer materials, the application of ultraviolet absorbers in the whole polymer additives is more and more extensive. Ultraviolet absorbers use ultraviolet rays to rearrange the hydroxyl groups of molecules in special positions to convert the absorbed ultraviolet rays into harmless heat energy to achieve a stable effect. However, UV absorbers only have the function of absorbing UV, and it is necessary to develop multifunctional materials with UV absorption and other functions.

Patent CN 105273585 A has developed a UV blocking and antifouling coating composition. The hardened film made by this patent has the high hardness and optical properties of conventional hardened films, as well as UV blocking performance, hydrophobic and oleophobic antifouling performance As well as excellent scratch resistance, it can be widely used in display exterior screens, glass exterior walls and injection molding and other fields. However, the fluorine-containing antifouling agent used has certain toxicity, and the experimental process is complicated, so it is necessary to study a simple, green and pollution-free film-forming method. CN 103261287 A prepares a cellulose acylate film with excellent mechanical and physical properties. The durability of the cellulose acylate film is greatly improved, but the performance is single, which greatly limits its application range. Therefore, the prior art lacks a multifunctional cellulose membrane that is simple and green, and has both water-blocking, oil-blocking, ultraviolet absorption, and environmental humidity sensitivity.

SUMMARY OF THE INVENTION

In view of the above defects or improvement needs of the prior art, the purpose of the present invention is to provide a multifunctional cellulose film and a preparation method thereof, which have the functions of water resistance, oil resistance, ultraviolet absorption and sensitivity to environmental humidity. .

For achieving the above object, the present invention adopts the following technical scheme:

The cellulose is oxidized with sodium periodate and then chemically grafted with polyethyleneimine. After the reaction product is centrifuged, the obtained precipitate is washed and filtered to obtain a uniform solid mixture, and the obtained solid mixture is thermally solidified under low pressure to form Multifunctional cellulose membrane.

The mass ratio of the cellulose, sodium periodate and polyethyleneimine is 1:1:0.5.

The temperature of the thermal curing is 30°C to 150°C.

The specific preparation process of the method is:

First, the pulp cellulose was added to the NaOH/urea solution, and the pulp cellulose suspension was obtained after mixing evenly. The sodium periodate was added to the pulp cellulose suspension under stirring, and the pH was adjusted to 4. Oxidize for 1h to obtain oxidized pulp cellulose suspension;

Then, polyethylenimine was added to the oxidized pulp cellulose suspension for a 3-h graft reaction to obtain a pulp cellulose suspension solution;

Finally, the pulp cellulose suspension solution is centrifuged to obtain the lower layer precipitate, the lower layer sediment is washed and suction filtered to obtain a dry solid mixture, and the solid mixture is thermally solidified and pressed at a temperature of 60° C. and a pressure of 10Mpa using a plate vulcanizer to obtain the polyamide mixture. Functional cellulose membrane.

The cellulose can be pulp cellulose and cotton cellulose.

Compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

1. The multifunctional cellulose film prepared by the present invention has the properties of water blocking, oil blocking and UV absorption at the same time.

2. The multifunctional cellulose film prepared by the present invention exhibits different mechanical properties and forms under different environmental humidity, and has environmental humidity sensitivity.

3. The multifunctional cellulose film prepared by the present invention is reusable. Due to the water blocking property of the multifunctional cellulose film, after use, it can be used again after being rinsed with water.

4. The preparation process of the present invention uses cellulose and polyethyleneimine as raw materials, the synthesis is simple, the cost is low, the energy consumption is low, no harmful substances are generated during the preparation process, and secondary pollution to the environment is not generated, and it is easy to scale. of industrial production.

The multifunctional cellulose film prepared by the invention can be used for attaching to glass outer walls, display outer screens, environmental humidity detectors, etc., and has the effects of absorbing ultraviolet rays, preventing pollution and scratching.

Description of drawings

1 is a schematic diagram of the water contact angle of the multifunctional cellulose film obtained in Example 1.

FIG. 2 is a schematic diagram of the ultraviolet absorption spectrum of the multifunctional cellulose film obtained in Example 1. FIG.

3 is a schematic diagram of the oil contact angle of the multifunctional cellulose film obtained in Example 2.

Detailed ways

In order to further illustrate the technical means adopted by the present invention and the beneficial effects thereof, the following detailed description is given in conjunction with the embodiments of the present invention and the accompanying drawings.

Embodiments of the present invention are as follows:

Example 1:

(1) 2g of pulp cellulose was added to 50ml of the mixed solution containing 7wt% NaOH and 12wt% urea, the pulp cellulose suspension was obtained after mixing uniformly, and 2g of sodium periodate was added to the pulp cellulose under stirring In the suspension, the pH was adjusted to 4 with 2M hydrochloric acid solution, and oxidized at 50 °C for 1 h to obtain an oxidized pulp cellulose suspension; 1 g of polyethyleneimine was added to the above pulp cellulose suspension for 3 h of grafting reaction, A pulp cellulose suspension solution was obtained; the obtained pulp cellulose suspension solution was centrifuged at 10,000 rpm for 10 min to separate and obtain a lower layer precipitate; the obtained lower layer sediment was washed 4 times and then filtered to obtain a relatively dry solid mixture, and a plate vulcanizer was used. The solid mixture was thermally cured and pressed at 30° C. and 10 Mpa for 10 minutes to obtain a multifunctional cellulose film.

(2) Cut a 2cm*1cm rectangular strip on the prepared multifunctional cellulose film, drop a drop of water on the rectangular film using a GBX company contact angle tester, use a standard CCD camera to image, and then use computer multimedia technology to analyze the The contact angle of the functional cellulose film with water, the resulting water contact angle was 98.93° (as shown in Figure 1).

(3) Cut a 2cm*1cm rectangular strip on the prepared multifunctional cellulose film, drop a drop of diesel oil on the rectangular film using a GBX company contact angle tester, use a standard CCD camera to image, and then use computer multimedia technology to analyze the The contact angle of the functional cellulose film with diesel oil, the obtained oil contact angle was 92.18°.

(4) Using an ultraviolet-visible-near-infrared spectrophotometer, fix the prepared multifunctional cellulose film at the designated position of the instrument, and irradiate it with ultraviolet light, and it is measured that it has the effect of absorbing ultraviolet light in the range of 220-533 nm. (as shown in picture 2)

(5)) Cut 3 rectangular strips of 2cm*1cm on the prepared multifunctional cellulose film, put the cut rectangular strips into a temperature and humidity environmental climate box, and control the humidity of the environmental climate box to 20% RH , 50% RH, 80% RH, after 10 minutes, immediately take out the long film with a certain humidity, measure the tensile strength of the multi-functional cellulose film, and measure the 20% RH, 50% RH, 80% RH humidity The tensile strengths of the films are 2.32Mpa, 3.23Mpa, 3.85Mpa. respectively. Moreover, the bending angles of the rectangular strips measured under the humidity of 20% RH, 50% RH, and 80% RH are 30°, 15°, and 3°, respectively, which can be applied to the detection of environmental humidity.

In addition, in this example, the multifunctional cellulose film was cut with a knife in a normal temperature and humidity environment, and it was found that scratches were not easy to appear.

Example 2:

(1)) 2g of cotton cellulose was added to 50ml of mixed solution containing 7wt% NaOH and 12wt% urea, the cotton cellulose suspension was obtained after mixing, and 2g of sodium periodate was added to this cellulose under stirring In the suspension, the pH was adjusted to 4 with 2M hydrochloric acid solution, and oxidized at 50 °C for 2 hours to obtain an oxidized cotton cellulose suspension; 1 g of polyethyleneimine was added to the above cotton cellulose suspension for 3 hours of grafting reaction, The cotton cellulose suspension solution was obtained; the obtained cotton cellulose suspension solution was centrifuged for 10 min under the condition of 10000 rpm, and the lower layer sediment was obtained by separation; the obtained lower layer sediment was washed 4 times to obtain a relatively dry solid mixture after suction filtration, and the solid mixture was obtained. The multifunctional cotton cellulose film was obtained by thermosetting and pressing at 90°C and 10Mpa for 10min.

(2) Cut a 2cm*1cm rectangular strip on the prepared multifunctional cotton cellulose film, drop a drop of water on the rectangular film using a GBX company contact angle tester, use a standard CCD camera to image, and then use computer multimedia technology to analyze The contact angle of the multifunctional cotton cellulose film with water, the obtained water contact angle is 101.34°.

(3) Cut a 2cm*1cm rectangular strip on the prepared multifunctional cotton cellulose film, drop a drop of diesel oil on the rectangular film using a GBX company contact angle tester, use a standard CCD camera to image, and then use computer multimedia technology to analyze The contact angle between the multifunctional cotton cellulose film and diesel oil, the obtained oil contact angle is 90.45° (as shown in Figure 3).

(4) Using an ultraviolet-visible-near-infrared spectrophotometer, fix the prepared cotton cellulose film at the designated position of the instrument, irradiate it with ultraviolet rays, and measure the effect of absorbing ultraviolet rays in the range of 236-437nm.

(5) Cut three rectangular strips of 2cm*1cm on the prepared multifunctional cotton cellulose film, put the cut rectangular strips into a temperature and humidity environmental climate box, and control the humidity of the environmental climate box to 20% RH , 50%RH, 80%RH, after 10min, immediately take out the long film with a certain humidity, measure the tensile strength of the multifunctional cotton cellulose film, and measure the humidity of 20%RH, 50%RH, 80%RH The tensile strengths of the lower films were 1.50Mpa, 1.75Mpa, and 2.02Mpa, respectively. Moreover, the bending angles of the rectangular strips measured at 20% RH, 50% RH, and 80% RH humidity are 26°, 11°, and 1°, respectively, which can be applied to the detection of ambient humidity.

In addition, in this example, the multifunctional cellulose film was cut with a knife in a normal temperature and humidity environment, and it was found that scratches were not easy to appear.

Example 3:

(1)) 2g of cotton cellulose was added to 50ml of mixed solution containing 7wt% NaOH and 12wt% urea, the cotton cellulose suspension was obtained after mixing, and 2g of sodium periodate was added to this cellulose under stirring In the suspension, the pH was adjusted to 4 with 2M hydrochloric acid solution, and oxidized at 50 °C for 2 hours to obtain an oxidized cotton cellulose suspension; 1 g of polyethyleneimine was added to the above cotton cellulose suspension for 3 hours of grafting reaction, The cotton cellulose suspension solution was obtained; the obtained cotton cellulose suspension solution was centrifuged for 10 min under the condition of 10000 rpm, and the lower layer sediment was obtained by separation; the obtained lower layer sediment was washed 4 times to obtain a relatively dry solid mixture after suction filtration, and the solid mixture was obtained. The multifunctional cotton cellulose film was obtained by thermosetting and pressing at 150°C and 10Mpa for 10min.

(2) Cut a 2cm*1cm rectangular strip on the prepared multifunctional cotton cellulose film, drop a drop of water on the rectangular film using a GBX company contact angle tester, use a standard CCD camera to image, and then use computer multimedia technology to analyze The contact angle of the multifunctional cotton cellulose film with water, the obtained water contact angle is 105.75°.

(3) Cut a 2cm*1cm rectangular strip on the prepared multifunctional cotton cellulose film, drop a drop of diesel oil on the rectangular film using a GBX company contact angle tester, use a standard CCD camera to image, and then use computer multimedia technology to analyze The contact angle between the multifunctional cotton cellulose film and diesel oil, the obtained oil contact angle is 96.31°.

(4) Using an ultraviolet-visible-near-infrared spectrophotometer, fix the prepared cotton cellulose film at the designated position of the instrument, irradiate it with ultraviolet rays, and measure the effect of absorbing ultraviolet rays in the range of 216-425nm.

(5) Cut three rectangular strips of 2cm*1cm on the prepared multifunctional cotton cellulose film, put the cut rectangular strips into a temperature and humidity environmental climate box, and control the humidity of the environmental climate box to 20% RH , 50%RH, 80%RH, after 10min, immediately take out the long film with a certain humidity, measure the tensile strength of the multifunctional cotton cellulose film, and measure the humidity of 20%RH, 50%RH, 80%RH The tensile strengths of the lower films were 1.67Mpa, 1.82Mpa, and 2.64Mpa, respectively. In addition, the measured bending angles of the rectangular strip under the humidity of 20% RH, 50% RH and 80% RH are 23°, 8°, and 4°, respectively, which can be applied to the detection of environmental humidity.

In addition, in this example, the multifunctional cellulose film was cut with a knife in a normal temperature and humidity environment, and it was found that scratches were not easy to appear.

It can be seen from the above examples that the multifunctional cellulose film prepared by the present invention has good functions of water blocking, oil blocking, UV absorption and environmental humidity sensitivity.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (3)

1. A preparation method of a multifunctional cellulose membrane is characterized by comprising the following steps: the method comprises the following specific steps:

oxidizing cellulose by using sodium periodate, grafting the oxidized cellulose with polyethyleneimine, centrifugally separating a reaction product, washing and filtering an obtained precipitate to obtain a uniform solid mixture, and thermally curing the obtained solid mixture under low pressure to form a multifunctional cellulose membrane;

the cellulose is paper pulp cellulose or cotton cellulose;

the method comprises the following specific preparation processes:

firstly, adding cellulose into a NaOH/urea solution, uniformly mixing to obtain a cellulose suspension, adding sodium periodate into the cellulose suspension under the stirring action, adjusting the pH to 4, and oxidizing at 50 ℃ for 1h to obtain an oxidized cellulose suspension;

then, adding polyethyleneimine into the oxidized cellulose suspension for grafting reaction for 3 hours to obtain a cellulose suspension solution;

and finally, centrifugally separating the cellulose suspension solution to obtain a lower-layer precipitate, washing and suction-filtering the lower-layer precipitate to obtain a dry solid mixture, and thermally curing and pressing the solid mixture at the temperature of 60 ℃ and the pressure of 10MPa by using a flat vulcanizing machine to obtain the multifunctional cellulose membrane.

2. The method for preparing a multifunctional cellulose film according to claim 1, wherein:

the mass ratio of the cellulose to the sodium periodate to the polyethyleneimine is 1: 1: 0.5.

3. a multifunctional cellulose film, characterized in that: prepared by the preparation method of any one of claims 1-2.

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