Soft polyvinyl alcohol foam material with uniform pore size distribution as well as preparation method and application of soft polyvinyl alcohol foam material

Abstract

The invention discloses a soft polyvinyl alcohol foam material with uniform pore size distribution as well as a preparation method and application thereof, and relates to the technical field of high polymer material preparation. Comprising the following raw materials in percentage by weight: 5-20% of polyvinyl alcohol, 5-17% of inorganic acid, 5-17% of formaldehyde, 0.2-2% of a foaming agent, 0.2-2% of a stabilizer, 3-14% of a plasticizer and the balance of distilled water. The polyvinyl alcohol foam material provided by the invention is stable in preparation process, easy to realize industrial production, low in cost, stable and simple in process. The prepared foam material is stable in foam structure, good in biocompatibility, uniform in pore size distribution and long in service life, has popularization and application potential and is wide in market prospect. The invention solves the problem of poor performance of polyvinyl alcohol foam in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer material preparation, in particular to a soft polyvinyl alcohol foam material with uniform pore size distribution and a preparation method and application thereof. BACKGROUND

[0002] The stabilizer generally has high molecular weight, is non-toxic, has certain biodegradability, is soluble in water, has a hydrophilic group and a hydrophobic group in the molecular structure, can effectively reduce the surface tension of a liquid, and has the functions of promoting the formation, stability and durability of foam. At present, the reports on polyvinyl alcohol porous foam at home and abroad mainly focus on the research on pure polyvinyl alcohol foam. The pure polyvinyl alcohol foam has the problems of decreased foam stability, foam shrinkage and poor thermal stability when being formed at high temperature, which may cause partial damage of the foam, and the foam has high hardness after drying. At present, there is no report on the polyvinyl alcohol foam material added with various stabilizers and glycerol as a plasticizer. SUMMARY

[0003] In order to solve the above technical problems, the purpose of the present application is to provide a soft polyvinyl alcohol foam material with uniform pore size distribution and a preparation method and application thereof, so as to solve the problem of poor performance of the polyvinyl alcohol foam in the prior art.

[0004] The technical scheme for solving the above technical problems is as follows: a soft polyvinyl alcohol foam material with uniform pore size distribution is provided, which comprises the following raw materials in percentage by weight: polyvinyl alcohol 5-20%, inorganic acid 5-17%, formaldehyde 5-17%, foaming agent 0.2-2%, stabilizer 0.2-2%, plasticizer 3-14%, and the remaining amount is distilled water.

[0005] On the basis of the above technical scheme, the present application can be further improved as follows: Further, the soft polyvinyl alcohol foam material with uniform pore size distribution comprises the following raw materials in percentage by weight: polyvinyl alcohol 10%, inorganic acid 15%, formaldehyde 13%, foaming agent 0.6%, stabilizer 0.6%, plasticizer 10%, and the remaining amount is distilled water.

[0006] Further, the polyvinyl alcohol has a degree of polymerization of 1749-1849.

[0007] Further, the inorganic acid is hydrochloric acid, sulfuric acid or phosphoric acid, and the inorganic acid is of analytical pure grade.

[0008] Further, the foaming agent is sodium bicarbonate.

[0009] Further, the stabilizer is polysorbate-20, polysorb-80, sorbitan oleate, triton X-100 or sorbitol.

[0010] Further, the plasticizer is glycerol.

[0011] The application further provides a preparation method of the soft polyvinyl alcohol foam material with uniform pore size distribution. (1) mixing polyvinyl alcohol and distilled water, heating and stirring to dissolve, to obtain a mixture; (2) adding formaldehyde, a foaming agent, a stabilizer and a plasticizer into the mixture prepared in step (1), stirring and mixing, then adding an inorganic acid, stirring and foaming, to obtain a foaming body; (3) hot forming the foaming body obtained in step (2), then cleaning and drying, to obtain the soft polyvinyl alcohol foam material with uniform pore size distribution.

[0012] Further, in step (1), the dissolving is performed at 80-100℃ and 300-400r. Further, in step (1), the dissolving is performed at 90℃ and 350r.

[0013] Further, in step (2), the stirring and foaming is performed at 350-450r.

[0014] Further, in step (2), the stirring and foaming is performed at 400r.

[0015] Further, in step (3), the hot forming is performed at 60-90℃ for 2-5h.

[0016] Further, in step (3), the hot forming is performed at 80℃ for 3h.

[0017] Further, in step (3), the hot air drying is performed at 60-80℃ for 6-8h.

[0018] Further, in step (3), the hot air drying is performed at 70℃ for 7h.

[0019] The application further provides application of the soft polyvinyl alcohol foam material with uniform pore size distribution in preparation of a wound auxiliary material, a negative pressure sealing drainage liquid absorbing foam or a hemostatic foam.

[0020] The application has the following beneficial effects: 1、In view of the good histocompatibility, mechanical properties, no toxic side effects and higher hardness of pure polyvinyl alcohol. But if there is no stabilizer and plasticizer added, the structure of pure polyvinyl alcohol foam is relatively fragile and the pore size is not uniform, and the foam may be broken due to thermal expansion or change of surface tension after heating, resulting in decreased stability. In addition, the foam will shrink during drying, resulting in a decrease in foam volume and an increase in hardness, which is not conducive to industrial production. The addition of stabilizer can effectively reduce the surface tension of polyvinyl alcohol aqueous solution, thereby increasing the dispersibility of gas and promoting the formation and stability of foam. In addition, the addition of glycerol as a plasticizer can significantly improve the flexibility of the foam, thereby obtaining a soft polyvinyl alcohol foam material with uniform pore size distribution.

[0021] 2、The present application prepares a stable polyvinyl alcohol foam material by blending polyvinyl alcohol, stabilizer and plasticizer. The molecular structure of the stabilizer usually has hydrophilic groups and hydrophobic groups, the hydrophilic groups interact with water, and the hydrophobic groups interact with oil or bubble surface. This amphiphilic structure enables the stabilizer to effectively reduce the surface tension of the liquid, thereby promoting the formation, stability and durability of the foam. The plasticizer glycerol can increase the softness of the foam, making the foam more flexible and not easy to crack, which is very effective for improving the durability and pressure resistance of the foam. Since the stabilizer and plasticizer have good solubility and biocompatibility in water and other solutions, subsequent cleaning is easy to remove, and the preparation steps are relatively simple. Therefore, the foam material of the present application can be applied to the industrial preparation of wound dressings, negative pressure sealing drainage liquid absorbing foam, hemostatic foam, etc.

[0022] 3、The polyvinyl alcohol foam material preparation process provided by the present application is stable, easy to realize industrial production, and has low cost, stability and simple process. The prepared foam material has stable foam structure, good biocompatibility, uniform pore size distribution and long service life, has potential for popularization and application, and has broad market prospects. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 SEM image of the foam material prepared in Example 1; Figure 2 SEM image of the foam material prepared in Comparative Example 1; Figure 3 Cytotoxicity test of the foam material prepared in Example 1. DETAILED DESCRIPTION

[0024] The principles and characteristics of the present application are described below in conjunction with the drawings, and the examples are only used to explain the present application and are not intended to limit the scope of the present application. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0025] Embodiment 1 A soft polyvinyl alcohol foam material with uniform pore size distribution comprises the following raw materials by weight percentage: polyvinyl alcohol 10% (degree of polymerization 1800), inorganic acid 15% (analytically pure hydrochloric acid), formaldehyde 13%, foaming agent 0.6% (sodium bicarbonate), stabilizer 0.6% (polysorbate-20), plasticizer 10% (glycerol), and the balance being distilled water.

[0026] A method for preparing a soft polyvinyl alcohol foam material with uniform pore size distribution comprises the following steps: (1) mixing polyvinyl alcohol and distilled water, and dissolving by heating and stirring under the condition of 900℃ and 350r to obtain a mixture; (2) adding formaldehyde, foaming agent, stabilizer, and plasticizer to the mixture obtained in step (1), mixing by stirring, then adding inorganic acid, and foaming by stirring under the condition of 400r to obtain a foaming body; (3) pouring the foaming body obtained in step (2) into a mold, hot forming under the condition of 80℃ for 3h, then washing, and hot air drying under the condition of 70℃ for 7h to obtain a soft polyvinyl alcohol foam material with uniform pore size distribution.

[0027] Embodiment 2 A soft polyvinyl alcohol foam material with uniform pore size distribution comprises the following raw materials by weight percentage: polyvinyl alcohol 5% (degree of polymerization 1749), inorganic acid 5% (analytically pure sulfuric acid), formaldehyde 5%, foaming agent 0.2% (sodium bicarbonate), stabilizer 0.2% (polysorbate-80), plasticizer 3% (glycerol), and the balance being distilled water.

[0028] A method for preparing a soft polyvinyl alcohol foam material with uniform pore size distribution comprises the following steps: (1) mixing polyvinyl alcohol and distilled water, and dissolving by heating and stirring under the condition of 80℃ and 300r to obtain a mixture; (2) adding formaldehyde, foaming agent, stabilizer, and plasticizer to the mixture obtained in step (1), mixing by stirring, then adding inorganic acid, and foaming by stirring under the condition of 350r to obtain a foaming body; (3) pouring the foaming body obtained in step (2) into a mold, hot forming under the condition of 60℃ for 5h, then washing, and hot air drying under the condition of 60℃ for 8h to obtain a soft polyvinyl alcohol foam material with uniform pore size distribution.

[0029] Embodiment 3 A soft polyvinyl alcohol foam material with uniform pore size distribution, comprising the following raw materials by weight percentage: polyvinyl alcohol 20% (degree of polymerization 1849), inorganic acid 17% (analytically pure phosphoric acid), formaldehyde 17%, foaming agent 2% (sodium bicarbonate), stabilizer 2% (oleic acid sorbitan), plasticizer 14% (glycerol), and the balance being distilled water.

[0030] A method for preparing a soft polyvinyl alcohol foam material with uniform pore size distribution, comprising the following steps: (1) mixing polyvinyl alcohol and distilled water, and dissolving by heating and stirring at 100°C and 400r to obtain a mixture; (2) adding formaldehyde, foaming agent, stabilizer, and plasticizer to the mixture obtained in step (1), stirring and mixing, then adding inorganic acid, and stirring and foaming at 450r to obtain a foaming body; (3) pouring the foaming body obtained in step (2) into a mold, hot forming at 90°C for 2h, then washing, and hot air drying at 80°C for 6h to obtain a soft polyvinyl alcohol foam material with uniform pore size distribution.

[0031] Comparative Example 1: A polyvinyl alcohol foam material, comprising the following raw materials by weight percentage: no stabilizer and plasticizer, and the rest being the same as Example 1.

[0032] A method for preparing a polyvinyl alcohol foam material, comprising the following steps: The same as Example 1.

[0033] Comparative Example 2: A polyvinyl alcohol foam material, comprising the following raw materials by weight percentage: no stabilizer and plasticizer, and the rest being the same as Example 2.

[0034] A method for preparing a polyvinyl alcohol foam material, comprising the following steps: The same as Example 2.

[0035] Comparative Example 3: A polyvinyl alcohol foam material, comprising the following raw materials by weight percentage: no stabilizer and plasticizer, and the rest being the same as Example 3.

[0036] A method for preparing a polyvinyl alcohol foam material, comprising the following steps: The same as Example 3.

[0037] Test Example I. Morphology The soft polyvinyl alcohol foam material with uniform pore size distribution prepared in Example 1 and the polyvinyl alcohol foam material prepared in Comparative Example 1 were respectively subjected to scanning electron microscope detection to observe the material morphology, and the results are shown in Figures 1-2 ( Figure 1From left to right and from top to bottom, they are ×16, 50, 200 and 400 times respectively. Figure 2 From left to right in the middle, they are ×200 and ×400 respectively).

[0038] Depend on Figure 1 It can be seen that by observing the foam material of Example 1 through scanning electron microscopy at different magnifications, the microstructure of the foam material shows a strong correlation with the application scenario: at ×16 times, the overall outline presents uniform bubbles and porous morphology, laying a structural foundation for the medical water absorption function; at ×50 times, the size, shape and connectivity of the bubbles are clearly presented, and this connected porous structure is beneficial to the absorption of exudate in medical scenarios; at ×200 times to ×400 times, the rough texture, fine bumps and other microstructures of the pore wall are gradually revealed, which not only enhances the porous characteristics of the material, but also provides a good contact interface for medical bonding.

[0039] Depend on Figure 2 Scanning electron microscopy of the foam material in Comparative Example 1 at various magnifications, from ×200 to ×400, revealed smooth pore walls with no apparent voids, uneven pores, and a lack of good contact interfaces. Furthermore, the foam material exhibited poor connectivity. Therefore, the complex microscopic morphology of the foam material in Example 1 further enhances biocompatibility, meeting practical requirements for liquid absorption and wound adhesion in medical applications.

[0040] 2. Analysis of physical properties of foam materials The foam materials obtained in Examples 1-3 and Comparative Examples 1-3 were subjected to the following physical property analysis: 1. Apparent density test According to GB / T 6343-1995, the apparent density is calculated as follows: p=m / v Where m is the mass of the sample and v is the volume of the sample. Take three samples from each group and take the average value.

[0041] 2. Water absorption test After the foam material is saturated with water, gently pinch a corner with tweezers to remove it from the water, and let the sample stay in the air for 30 seconds, then weigh it again and calculate. According to the Ministry of Light Industry standard SG-232-81, calculate the water absorption rate as follows: X=(M2-M1) / M1 Where M1 is the mass of the foam material before absorbing water, and M2 is the mass of the foam material after absorbing water.

[0042] 3. Appearance and morphology characterization Upon visual inspection, the foam material should be white or off-white in compressed form, and its surface should be clean, without signs of mold, damage, etc.

[0043] 4. Elastic recovery rate test The foam material was pressed by hand, and the recovery rate of the shape of the foam material was observed. If it can recover instantly after the pressure is released, it is called the elastic recovery rate of 100%.

[0044] The results are shown in Tables 1 and 2.

[0045] Table 1 Physical properties of foam materials of Examples 1-3

[0046] Table 2 Physical properties of foam materials of Comparative Examples 1-3

[0047] As can be seen from Table 1, the foam materials of the present application have significant commonality and balanced characteristics in appearance and core performance. From the appearance, they all have the characteristics of uniform cells and softness in wet state, which not only ensures the comfort of the contact part during use, but also provides a structural basis for the water absorption function; the elastic recovery rate reaches 100%, which means that they can completely recover to the original state after being deformed by external force, showing stable and excellent elastic properties, suitable for various medical scenarios that require repeated deformation. Although there are slight differences in the density and water absorption rate of individual samples, through the average density and average water absorption rate data, it can be found that the overall density control and water absorption capacity remain balanced.

[0048] As can be seen from Table 2, the foam materials of the comparative examples are weaker than the foam materials of the present application in terms of water absorption efficiency, liquid diffusion capacity and appearance.

[0049] III. Cytotoxicity test L929 cell suspension was inoculated into a 96-well plate at about 100 μL per well, and cultured for 24 h until the cells formed a semi-confluent monolayer. According to the ISO 10993-12 standard, sample leaching liquor was prepared (see Example 1), and then the culture medium was replaced with 25vt%, 50vt%, 75vt%, and 100vt% concentration series leaching liquor, and cultured for another 24 h. Then, the culture medium containing 10vt% CCK-8 was directly used to replace the liquid, and the culture plate was placed in a light-proof incubator for incubation for 1 h. The absorbance (OD value) at 450 nm was measured using a microplate reader, and compared with the absorbance of the control group of cells to calculate the cell proliferation and evaluate the toxicity.

[0050] According to the standard GB / T16886.1, the cell survival rate was calculated according to the following formula: Survival rate (%) = 100 x OD 450a / OD 450b In the formula, OD 450a is the average absorbance of the foam material under different concentrations of leaching liquor, and OD 450bis the average value of blank absorbance. Figure 3 .

[0051] Depend on Figure 3 As can be seen, cells in the 25%-75% immersion solution showed significant proliferation after 24 hours of culture, all exceeding 100%. The cell viability in the 100% immersion solution was 91%, exceeding the 70% requirement of the foam material industry standard GB / T 16886.1. The material is considered non-cytotoxic. These findings demonstrate the excellent practicality and performance consistency of the foam material of the present invention.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A soft polyvinyl alcohol foam material with uniform pore size distribution, characterized in that: The invention comprises the following raw materials in percentage by weight: 5-20% polyvinyl alcohol, 5-17% inorganic acid, 5-17% formaldehyde, 0.2-2% foaming agent, 0.2-2% stabilizer, 3-14% plasticizer and the balance is distilled water.

2. The soft polyvinyl alcohol foam material with uniform pore size distribution according to claim 1, characterized in that: The degree of polymerization of polyvinyl alcohol is 1749-1849.

3. The soft polyvinyl alcohol foam material with uniform pore size distribution according to claim 1, characterized in that: The inorganic acid is hydrochloric acid, sulfuric acid or phosphoric acid, and the inorganic acid is of analytical grade.

4. The soft polyvinyl alcohol foam material with uniform pore size distribution according to claim 1, characterized in that: The foaming agent is sodium bicarbonate.

5. The soft polyvinyl alcohol foam material with uniform pore size distribution according to claim 1, characterized in that: The stabilizer is polysorbate 20, polysorbate 80, sorbitan oleate, Triton X-100 or sorbitol.

6. The soft polyvinyl alcohol foam material with uniform pore size distribution according to claim 1, characterized in that: The plasticizer is glycerol.

7. The method for preparing a soft polyvinyl alcohol foam material with uniform pore size distribution according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Mixing polyvinyl alcohol and distilled water, heating and stirring to dissolve, to obtain a mixture; (2) adding formaldehyde, a foaming agent, a stabilizer and a plasticizer to the mixture obtained in step (1), stirring and mixing, and then adding an inorganic acid, stirring and foaming to obtain a foam; (3) The foamed body obtained in step (2) is thermoformed, and then cleaned and dried to obtain a soft polyvinyl alcohol foam material with uniform pore size distribution.

8. The method for preparing a soft polyvinyl alcohol foam material with uniform pore size distribution according to claim 7, characterized in that: In step (1), dissolution is carried out at 80-100°C and 300-400r.

9. The method for preparing a soft polyvinyl alcohol foam material with uniform pore size distribution according to claim 7, characterized in that: In step (3), thermoforming is performed at 60-90°C for 2-5 hours.

10. Use of the soft polyvinyl alcohol foam material with uniform pore size distribution according to any one of claims 1 to 6 in the preparation of wound dressings, negative pressure sealing drainage and fluid absorption foams or hemostatic foams.

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