Polyvinyl alcohol-based foam material containing expanded microspheres as well as preparation method and application of polyvinyl alcohol-based foam material

Abstract

The invention provides a polyvinyl alcohol-based foam material containing expanded microspheres as well as a preparation method and application of the polyvinyl alcohol-based foam material, and belongs to the technical field of high polymer materials. The polyvinyl alcohol-based foam material containing the expanded microspheres is prepared from the following components in parts by mass: 100 to 200 parts of polyvinyl alcohol resin, 1 to 30 parts of nucleating agent, 1 to 100 parts of expanded microspheres, 0.1 to 5 parts of foaming agent, 50 to 200 parts of inorganic strong acid, 50 to 250 parts of cross-linking agent and 400 to 600 parts of water. Expanded microspheres are uniformly dispersed in a polyvinyl alcohol-based foam material prepolymer, and when the polyvinyl alcohol-based foam material prepolymer is cured under a heating condition, the expanded microspheres are wrapped in a net structure of the polyvinyl alcohol-based foam material and expand after being heated, so that the expanded microspheres are formed; therefore, the compression set performance of the polyvinyl alcohol-based foam material is obviously improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and particularly relates to a polyvinyl alcohol-based foam material containing expanded microspheres and a preparation method and application thereof. BACKGROUND

[0002] The polyvinyl alcohol-based foam material is a kind of medical porous foam material commonly used in VSD (Vacuum Sealing Drainage). The foam material is generally prepared by using various physical and chemical foaming technologies and a hydroxy aldehyde condensation reaction under the catalysis of an acid with polyvinyl alcohol resin and organic aldehyde. The compression permanent deformation performance of the polyvinyl alcohol-based foam material is generally inferior to that of another commonly used medical porous foam material, i.e., polyurethane foam. This may be due to the fact that the polyurethane molecule composition simultaneously has a rigid polyisocyanate hard chain and a flexible polyester polyol or polyether polyol soft chain, and the ratio of the hard chain and the soft chain is adjusted to obtain a foam material with excellent compression permanent deformation performance. However, the polyvinyl alcohol-based foam material does not have a combination of hard and soft chains in the molecular composition, and can only be realized by a pore forming process. However, compared with the polyurethane foam material, the polyvinyl alcohol-based foam material is not easy to adhere to a wound surface, has stronger drainage capacity, can reduce bleeding and foreign matter residues on a wound surface, and is helpful to the survival of skin grafts after skin grafting. Therefore, in the case of fixing skin grafts to promote the survival of skin grafts after skin grafting, preparation of a wound bed before large-area burn skin grafting, and the presence of deep wounds or sinuses, the polyvinyl alcohol-based foam material is generally preferred.

[0003] In the prior art, there are mainly two methods for preparing the polyvinyl alcohol-based foam material. One is a method of filling and foaming starch. The product prepared by this method still has a high water absorption rate and good compression recovery capacity after radiation sterilization. However, the water resource consumption is huge during the cleaning process of the starch, and it is difficult to completely clean the starch. A small amount of starch residues in the product can easily cause mildew and product deterioration, which limits the application of the product in the medical field. The other is a method of air foaming by adding a surfactant. The product prepared by this method has general water absorption rate and poor compression recovery capacity after radiation sterilization, and the pore structure is greatly affected by changes in environmental temperature and humidity, and the quality stability of the product is difficult to control. SUMMARY

[0004] Based on the above technical problems, the present application provides a polyvinyl alcohol-based foam material containing expanded microspheres and a preparation method thereof. By uniformly dispersing the expanded microspheres in the polyvinyl alcohol-based foam material prepolymer, when the polyvinyl alcohol-based foam material prepolymer is cured under heating conditions, the expanded microspheres are wrapped in the network structure of the polyvinyl alcohol-based foam material and expand under heat, thereby significantly improving the compression permanent deformation performance of the polyvinyl alcohol-based foam material.

[0005] Specifically, the present application adopts the following technical scheme to achieve the above-mentioned purpose. The polyvinyl alcohol-based foam material containing expanded microspheres comprises the following components in mass fraction: 100-200 parts of polyvinyl alcohol resin, 1-30 parts of nucleating agent, 1-100 parts of expanded microspheres, 0.1-5 parts of foaming agent, 50-200 parts of inorganic strong acid, 50-250 parts of crosslinking agent, and 400-600 parts of water.

[0006] In the preferred scheme, the nucleating agent is at least one of white carbon black, talcum powder and silica sol.

[0007] In the preferred scheme, the foaming agent is at least one of triton-100, tween-80 and sodium dodecyl sulfonate.

[0008] In the preferred scheme, the inorganic strong acid is sulfuric acid or / and hydrochloric acid.

[0009] In the preferred scheme, the crosslinking agent is at least one of formaldehyde, glutaraldehyde and boric acid.

[0010] In the preferred scheme, the polyvinyl alcohol resin has an alcoholysis degree of >80 mol% and a polymerization degree of 500-2200.

[0011] The preparation method of the polyvinyl alcohol-based foam material containing expanded microspheres comprises the following steps: S1, uniformly mixing the polyvinyl alcohol resin, the nucleating agent and water to obtain a polyvinyl alcohol-based emulsion; S2, cooling the polyvinyl alcohol-based emulsion, and then sequentially adding the expanded microspheres, the foaming agent, the inorganic strong acid and the crosslinking agent; uniformly mixing to obtain a polyvinyl alcohol-based foam material prepolymer; S3, heating and expanding the polyvinyl alcohol-based foam material prepolymer, and then cooling and curing to form a polyvinyl alcohol-based foam material containing expanded microspheres.

[0012] In the preferred scheme, the uniform mixing in step S1 is achieved by stirring at 85-100℃.

[0013] In the preferred scheme, the uniform mixing in step S2 is achieved by stirring at a speed of 200-400 rpm.

[0014] In the preferred scheme, the heating and curing conditions in step S3 are: first heating to 80-100℃ for 1-30 minutes, and then maintaining at 50-70℃ for 6-15 hours.

[0015] The present application also provides a preparation method of a medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following steps: S1, uniformly mix the polyvinyl alcohol resin, the nucleating agent and water to obtain a polyvinyl alcohol-based emulsion; S2, cool the polyvinyl alcohol-based emulsion, and then sequentially add the expanded microspheres, the foaming agent, the inorganic strong acid and the crosslinking agent; uniformly mix to obtain a polyvinyl alcohol-based foam material prepolymer; S3, heat and expand the polyvinyl alcohol-based foam material prepolymer, and then cool and solidify to form a polyvinyl alcohol-based foam material containing expanded microspheres; S4, wash the polyvinyl alcohol-based foam material containing expanded microspheres to be acidic or neutral, and after cutting, packaging and radiation sterilization, obtain a medical polyvinyl alcohol-based foam material containing expanded microspheres.

[0016] In the preferred scheme, the uniform mixing in step S1 is achieved by stirring at 85-100°C.

[0017] In the preferred scheme, the water in step S1 is purified water.

[0018] In the preferred scheme, the uniform mixing in step S2 is achieved by stirring at a speed of 200-400 rpm.

[0019] In the preferred scheme, the heating and solidification conditions in step S3 are: first heated to 80-100°C for 1-30 minutes, and then kept at 50-70°C for 6-15 hours.

[0020] In the preferred scheme, the polyvinyl alcohol-based foam material containing expanded microspheres is washed to have a pH of 4.0-7.0.

[0021] The polyvinyl alcohol-based foam material containing expanded microspheres provided by the application or the prepared medical polyvinyl alcohol-based foam material containing expanded microspheres can be used to prepare medical dressings.

[0022] Compared with the prior art, the technical scheme of the application has the following beneficial effects: (1) In the application, the expanded microspheres are dispersed in the network structure of the polyvinyl alcohol-based foam material, which helps to enhance the supporting force of the foam material under negative pressure and significantly improves the compression permanent deformation capacity of the foam material. At the same time, the nucleating agent also has a synergistic effect on the compression permanent deformation capacity of the polyvinyl alcohol-based foam material.

[0023] (2) The method for preparing the polyvinyl alcohol-based foam material in the application can avoid the problems of huge water resource consumption and product deterioration caused by moldy residual starch in the starch foaming method, and the prepared polyvinyl alcohol-based foam material has the same performance as the polyvinyl alcohol foam material prepared by the starch foaming method. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Figure 1 is a photograph of the medical polyvinyl alcohol-based foam material containing expanded microspheres prepared in Example 1 of the present application under an optical microscope at 30 times magnification; Figure 2 Figure 2 is a photograph of the medical polyvinyl alcohol-based foam material containing expanded microspheres prepared in Example 1 of the present application under an optical microscope at 50 times magnification; Figure 3 Figure 3 is a photograph of the expanded microsphere dispersion used in the present application under an optical microscope at 50 times magnification before and after heating and expansion; Figure 4 Figure 4 is a photograph of the air-foamed polyvinyl alcohol foam material prepared in Comparative Example 1 of the present application under an optical microscope at 30 times magnification; Figure 5 Figure 5 is a photograph of the starch-foamed polyvinyl alcohol foam material prepared in Comparative Example 2 of the present application under an optical microscope at 30 times magnification; Figure 6 Figure 6 is a photograph of the medical polyvinyl alcohol-based foam material containing expanded microspheres prepared in Example 1 of the present application; Figure 7 Figure 7 is a photograph of the air-foamed polyvinyl alcohol-based foam material prepared in Comparative Example 1 of the present application; Figure 8 Figure 8 is a photograph of the starch-foamed polyvinyl alcohol-based foam material prepared in Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0025] The technical solutions of the present application are described below in conjunction with the examples to make the present application clear and complete, and to enable those skilled in the art to fully understand the present application. Obviously, the described examples are only some preferred examples of the present application, but not all examples. Any equivalent changes or substitutions made by those skilled in the art without creative labor to the following examples shall fall within the protection scope of the present application.

[0026] In the following examples, the expanded microspheres used are Expancel® DE 620 (Expancel® DE 620) and Expancel® DE 620 (Expancel® DE 620) from Nouryon. ®WU series microspheres. The expanded microspheres are thermoplastic expandable microspheres, having a core-shell structure, consisting of a thermoplastic polymer shell encapsulating a low-boiling point solvent (liquid alkane gas or other compounds), the diameter of the microspheres is 20-60 μm, the diameter expands 10-60 times after heating, and the expanded microspheres can still maintain the volume at the time of expansion without shrinking after cooling. The silica sol used is the nano-silica sol HN-S01 series of Hangzhou Hengge Nanotechnology Co., Ltd., with a particle size of 30-100 nm. The starch used is AR grade potato starch of Sinopharm Chemical Reagent Co., Ltd. The polyvinyl alcohol resin used has an alcoholysis degree of >80 mol% and a polymerization degree of 500-2200.

[0027] Example 1 A medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following components by mass: 100 parts of polyvinyl alcohol resin, 10 parts of silica sol (nucleating agent), 10 parts of expanded microspheres, 0.33 parts of Triton-100 (foaming agent), 66.7 parts of sulfuric acid (inorganic strong acid), 66.7 parts of formaldehyde (crosslinking agent), and 600 parts of purified water.

[0028] The preparation method of the medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following steps: S1, mix 300 g of polyvinyl alcohol resin (alcoholysis degree 88 mol%, polymerization degree 1700), 30 g of silica sol and 1800 g of purified water, and stir and dissolve at 90°C to obtain a uniformly dispersed polyvinyl alcohol-based emulsion.

[0029] S2, when the polyvinyl alcohol-based emulsion in step S1 is cooled to 40°C, 30 g of expanded microspheres, 1 g of Triton-100, 200 g of 50wt% sulfuric acid and 200 g of formaldehyde are added in sequence to obtain a mixture A. Stir the mixture A at 300 rpm to obtain a polyvinyl alcohol-based foam material pre-polymer with a volume about 3.2 times the volume of the mixture A.

[0030] S3, immediately place the polyvinyl alcohol-based foam material pre-polymer obtained in step S2 into a mold, first place it in a 90°C environment for 10 minutes to expand the expanded microspheres, and then place it in a 55°C environment for 12 hours to solidify and form the polyvinyl alcohol-based foam material.

[0031] S4, wash the material after forming in step S3 with purified water until the pH is 6.5. Then cut, package and sterilize by radiation to obtain a medical polyvinyl alcohol-based foam material containing expanded microspheres (the appearance structure is as shown in Figure 6 ).

[0032] Observe the medical polyvinyl alcohol-based foam material containing expanded microspheres under an optical microscope, the structure is as shown in Figure 1 (magnification 30 times) and Figure 2(magnified 50 times). From Figure 1 and Figure 2 It can be seen from Figure 3 the left picture that the expanded microspheres were dispersed in the polyvinyl alcohol-based foam material. It can be seen from Figure 3 the right picture that the expanded microspheres were expanded after being heated. It can be seen from Figure 3 that the expanded microspheres were obviously expanded after being heated, and the pores between the microspheres were significantly increased. It can be seen from Figures 1-3 that the expansion mode of the expanded microspheres in the polyvinyl alcohol-based foam material was consistent with the original expansion mode of the expanded microspheres, which indicated that the types, amounts and reaction conditions of the other raw materials added in the application would not inhibit the expansion effect of the expanded microspheres.

[0033] Example 2 A medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following components by mass: 100 parts of polyvinyl alcohol resin, 6.7 parts of fumed silica (nucleating agent), 20 parts of expanded microspheres, 0.67 parts of Tween-80 (foaming agent), 50 parts of sulfuric acid (inorganic strong acid), 93.3 parts of formaldehyde (crosslinking agent), 1 part of glutaraldehyde (crosslinking agent), and 500 parts of purified water.

[0034] The preparation method of the medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following steps: S1, 300 g of polyvinyl alcohol resin (alcoholysis degree 88 mol%, polymerization degree 1700), 20 g of fumed silica (one kind of white carbon black) and 1500 g of purified water were mixed and dissolved under stirring at 95°C to obtain a uniformly dispersed polyvinyl alcohol-based emulsion.

[0035] S2, when the polyvinyl alcohol-based emulsion in step S1 was cooled to 20°C, 60 g of expanded microspheres, 2 g of Tween 80, 150 g of 50wt% sulfuric acid, 280 g of formaldehyde and 3 g of glutaraldehyde were added in sequence to obtain a mixture A. The mixture A was stirred at 200 rpm to obtain a polyvinyl alcohol-based foam material prepolymer with a volume about 3.8 times the volume of the mixture A.

[0036] S3, the polyvinyl alcohol-based foam material prepolymer obtained in step S2 was immediately placed in a mold, first placed in an environment at 85°C for 30 minutes to expand the expanded microspheres, and then placed in an environment at 60°C for 10 hours to solidify and form the polyvinyl alcohol-based foam material.

[0037] S4, the material after molding in step S3 is washed with purified water until the pH is 6.5. Then cut, package, radiation sterilization, get medical polyvinyl alcohol-based foam material containing expanded microspheres.

[0038] Example 3 A medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following components by mass fraction: 100 parts of polyvinyl alcohol resin, 5 parts of white carbon black (nucleating agent), 6.7 parts of silica sol (nucleating agent), 3.33 parts of expanded microspheres, 0.67 parts of Tween-80 (foaming agent), 50 parts of sulfuric acid (strong inorganic acid), 93.3 parts of formaldehyde (crosslinking agent), 6.7 parts of boric acid (crosslinking agent), 567 parts of purified water.

[0039] The preparation method of the medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following steps: S1, 300g of polyvinyl alcohol resin (alcoholysis degree 88mol%, polymerization degree 1700), 15g of white carbon black, 20g of silica sol and 1700g of purified water are mixed, stirred and dissolved in 90℃ environment, to obtain a uniformly dispersed polyvinyl alcohol-based emulsion.

[0040] S2, when the polyvinyl alcohol-based emulsion in step S1 is cooled to 20℃, 10g of expanded microspheres, 2g of Tween 80, 150g of 50wt% sulfuric acid, 280g of formaldehyde and 20g of boric acid are added in turn to obtain a mixture A. Stir the mixture A at 350rpm to obtain a polyvinyl alcohol-based foam material prepolymer with a volume about 3.4 times the volume of the mixture A.

[0041] S3, immediately place the polyvinyl alcohol-based foam material prepolymer obtained in step S2 into a mold, first place it in an 85℃ environment for 30 minutes to make the expanded microspheres expand, and then place it in a 60℃ environment for 10 hours to make the polyvinyl alcohol-based foam material solidify and form.

[0042] S4, the material after molding in step S3 is washed with purified water until the pH is 6.5. Then cut, package, radiation sterilization, get medical polyvinyl alcohol-based foam material containing expanded microspheres.

[0043] Example 4 A medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following components by mass fraction: 150 parts of polyvinyl alcohol resin, 1 part of white carbon black (nucleating agent), 1 part of expanded microspheres, 0.1 part of sodium dodecyl sulfonate (foaming agent), 200 parts of hydrochloric acid (strong inorganic acid), 50 parts of glutaraldehyde (crosslinking agent), 400 parts of purified water.

[0044] The preparation method of the medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following steps: S1, 150 g of polyvinyl alcohol resin (alcoholysis degree 88 mol%, polymerization degree 500), 300 g of polyvinyl alcohol resin (alcoholysis degree 88 mol%, polymerization degree 200), 3 g of white carbon black, and 1200 g of purified water were mixed and dissolved by stirring in an environment of 85°C to obtain a polyvinyl alcohol-based emulsion uniformly dispersed.

[0045] S2, when the polyvinyl alcohol-based emulsion in step S1 was cooled to 30°C, 3 g of expanded microspheres, 0.3 g of sodium dodecyl sulfonate, 600 g of 50 wt% concentrated hydrochloric acid, and 150 g of glutaraldehyde were sequentially added to obtain a mixture A. The mixture A was stirred at 400 rpm to obtain a polyvinyl alcohol-based foam pre-polymer having a volume about 2.2 times the volume of the mixture A.

[0046] S3, the polyvinyl alcohol-based foam pre-polymer obtained in step S2 was immediately placed in a mold, and first placed in an environment of 80°C for 28 minutes to expand the expanded microspheres, and then placed in an environment of 50°C for 6 hours to solidify and form the polyvinyl alcohol-based foam material.

[0047] S4, the material after forming in step S3 was washed with purified water until the pH was 4.0. Then it was cut, packaged, and sterilized by radiation to obtain a medical polyvinyl alcohol-based foam material containing expanded microspheres.

[0048] Example 5 A medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following components by mass: 200 parts of polyvinyl alcohol resin, 30 parts of talc (nucleating agent), 100 parts of expanded microspheres, 2 parts of Triton-100 (foaming agent), 3 parts of Tween-80 (foaming agent), 100 parts of sulfuric acid (inorganic strong acid), 100 parts of glutaraldehyde (crosslinking agent), 150 parts of boric acid (crosslinking agent), and 600 parts of purified water.

[0049] The preparation method of the medical polyvinyl alcohol-based foam material containing expanded microspheres, comprising the following steps: S1, 600 g of polyvinyl alcohol resin (alcoholysis degree 88 mol%, polymerization degree 1700), 90 g of talc, and 1800 g of purified water were mixed and dissolved by stirring in an environment of 100°C to obtain a polyvinyl alcohol-based emulsion uniformly dispersed.

[0050] S2, when the polyvinyl alcohol-based emulsion in step S1 was cooled to 50°C, 300 g of expanded microspheres, 6 g of Triton-100, 9 g of Tween-80, 300 g of 50 wt% sulfuric acid, 300 g of glutaraldehyde, and 450 g of boric acid were sequentially added to obtain a mixture A. The mixture A was stirred at 300 rpm to obtain a polyvinyl alcohol-based foam pre-polymer having a volume about 3.6 times the volume of the mixture A.

[0051] S3, immediately place the polyvinyl alcohol-based foam material prepolymer obtained in step S2 into a mold, first place it in a 100°C environment for 1 minute to make the expanded microspheres swell, and then place it in a 70°C environment for 15 hours to make the polyvinyl alcohol-based foam material solidify and form.

[0052] S4, wash the material formed in step S3 with purified water until the pH is 7.0. Then cut, package, and sterilize by irradiation to obtain a medical polyvinyl alcohol-based foam material containing expanded microspheres.

[0053] Comparative Example 1 An air-foamed polyvinyl alcohol foam material includes the following components in mass fractions: 50 parts of polyvinyl alcohol resin, 10 parts of white carbon black, 0.67 parts of Tween-80, 83.3 parts of sulfuric acid, 83.3 parts of formaldehyde, and 292 parts of purified water.

[0054] The preparation method of the air-foamed polyvinyl alcohol foam material includes the following steps: P1, mix 150 g of polyvinyl alcohol resin (alcoholysis degree 88%, polymerization degree 1700), 30 g of white carbon black, and 875 g of purified water, and stir and dissolve in a 90°C-95°C environment to obtain a uniformly dispersed polyvinyl alcohol-based emulsion.

[0055] P2, after the polyvinyl alcohol-based emulsion in step P1 cools to 40°C, add 2 g of Tween 80, 250 g of sulfuric acid, and 250 g of formaldehyde in sequence to obtain a mixture B. Stir the mixture B at 300 rpm to obtain a polyvinyl alcohol-based foam material prepolymer B1.

[0056] P3, immediately place the polyvinyl alcohol-based foam material prepolymer B1 obtained in step P2 into a mold, and heat to 65°C to solidify and form.

[0057] P4, wash the material formed in step P3 with purified water until the pH is 4-7 (for example, pH 6.5), and then cut to obtain an air-foamed polyvinyl alcohol foam material (appearance structure as shown in Figure 7 ). Observe the polyvinyl alcohol-based foam material prepared in this comparative example under an optical microscope, and the structure is as shown in Figure 4 . As can be seen from Figure 4 , the pore bubble uniformity is poor, and there are no tiny pore bubbles on the pore bubble support column.

[0058] Comparative Example 2 A starch-foamed polyvinyl alcohol foam material includes the following components in mass fractions: 50 parts of polyvinyl alcohol resin, 20 parts of starch, 66.7 parts of sulfuric acid, 100 parts of formaldehyde, and 317 parts of water.

[0059] The preparation method of the starch-foamed polyvinyl alcohol foam material includes the following steps: R1, 150 g of polyvinyl alcohol resin (alcoholysis degree 88%, polymerization degree 1700), 60 g of starch and 950 g of purified water were mixed and dissolved by stirring at 90-95 °C to obtain a polyvinyl alcohol-based emulsion uniformly dispersed.

[0060] R2, after the polyvinyl alcohol-based emulsion in step S1 was cooled to 30 °C, 200 g of sulfuric acid and 300 g of formaldehyde were added in sequence to obtain a mixture C. The mixture C was stirred at 400 rpm to obtain a polyvinyl alcohol-based foam pre-polymer C1.

[0061] R3, the polyvinyl alcohol-based foam pre-polymer C1 obtained in step R2 was immediately placed in a mold and cured by heating to 60 °C to form a material.

[0062] R4, the material formed in step R3 was washed with purified water until the pH was 4-7 (for example, pH 6.5), and then cut to obtain a starch-foamed polyvinyl alcohol-based foam material (the appearance structure is shown in Figure 8 The polyvinyl alcohol-based foam material prepared in the comparative example was observed under an optical microscope, and the structure is shown in Figure 5 It can be seen from Figure 5 that there are many tiny pores on the support structure of the large pore interspace, which are generated by starch gelatinization elution.

[0063] Comparative Example 3 A medical polyvinyl alcohol-based foam material comprising the following components by mass: 100 parts of polyvinyl alcohol resin, 10 parts of silica sol (nucleating agent), 0.33 parts of Triton-100 (foaming agent), 66.7 parts of sulfuric acid (inorganic strong acid), 66.7 parts of formaldehyde (crosslinking agent), and 600 parts of purified water. That is, compared with Example 1, the medical polyvinyl alcohol-based foam material in the comparative example does not contain expanded microspheres.

[0064] The preparation method of the medical polyvinyl alcohol-based foam material is basically the same as that of Example 1, except that no expanded microspheres are added in step S2.

[0065] Comparative Example 4 A medical polyvinyl alcohol-based foam material comprising the following components by mass: 100 parts of polyvinyl alcohol resin, 10 parts of expanded microspheres, 0.33 parts of Triton-100 (foaming agent), 66.7 parts of sulfuric acid (inorganic strong acid), 66.7 parts of formaldehyde (crosslinking agent), and 600 parts of purified water. That is, compared with Example 1, the medical polyvinyl alcohol-based foam material in the comparative example does not contain the nucleating agent silica sol.

[0066] The preparation method of the medical polyvinyl alcohol-based foam material is basically the same as that of Example 1, except that no silica sol is added in step S1.

[0067] Comparative Example 5 This comparative example provides a medical polyvinyl alcohol-based foam material containing expanded microspheres, which has the same composition as that in Example 4.

[0068] The preparation method of the medical polyvinyl alcohol-based foam material containing expanded microspheres is basically the same as that in Example 4, except that the polyvinyl alcohol-based foam material prepolymer obtained in step S2 is immediately placed in a mold in step S3, and then placed in an environment at 75°C for 28 minutes and then placed in an environment at 50°C for 6 hours. Under an optical microscope, it is found that there are almost no tiny pores generated by the expansion of the expanded microspheres in the obtained medical polyvinyl alcohol-based foam material containing expanded microspheres, which indicates that the expanded microspheres cannot effectively expand under the experimental conditions of this comparative example.

[0069] Comparative Example 6 This comparative example provides a medical polyvinyl alcohol-based foam material containing expanded microspheres, which has the same composition as that in Example 4.

[0070] The preparation method of the medical polyvinyl alcohol-based foam material containing expanded microspheres is basically the same as that in Example 4, except that the polyvinyl alcohol-based foam material prepolymer obtained in step S2 is immediately placed in a mold in step S3, and then placed in an environment at 75°C for 12 hours. Under an optical microscope, it is found that there are almost no tiny pores generated by the expansion of the expanded microspheres in the obtained medical polyvinyl alcohol-based foam material containing expanded microspheres, which indicates that the expanded microspheres cannot effectively expand under the experimental conditions of this comparative example.

[0071] Comparative Example 7 This comparative example provides a medical polyvinyl alcohol-based foam material containing expanded microspheres, which has the same composition as that in Example 1.

[0072] The preparation method of the medical polyvinyl alcohol-based foam material containing expanded microspheres is basically the same as that in Example 4, except that the polyvinyl alcohol-based foam material prepolymer obtained in step S2 is immediately placed in a mold in step S3, and then placed in an environment at 90°C for 12 hours. Due to the high temperature accelerating the expansion of the gas in the system, the polyvinyl alcohol-based foam material collapses and cracks, and cannot be subjected to subsequent sample performance test experiments.

[0073] Comparative Example 8 This comparative example provides a medical polyvinyl alcohol-based foam material containing expanded microspheres, which has the same composition as that in Example 1.

[0074] The preparation method of the medical polyvinyl alcohol-based foam material containing expanded microspheres is basically the same as that in Example 4, except that the polyvinyl alcohol-based foam material prepolymer obtained in step S2 is immediately placed in a mold in step S3, and then placed in an environment of 105°C for 10 minutes, and then placed in an environment of 55°C for 12 hours for curing and forming. The product obtained in this comparative example has obvious foam layering after forming, the outer layer of the pore foam structure is dense, the inner layer of the pore foam has local large pores and uneven distribution, the product skin discoloration is uneven, the skin is brittle, and subsequent sample preparation cannot be carried out.

[0075] Performance test of foam material The polyvinyl alcohol-based foam materials prepared in Examples 1-5 and Comparative Examples 1-8 were tested for compression permanent deformation, density, and water absorption ratio according to the method in “YY / T 1872-2022 Negative Pressure Drainage Sponge”. The test results are shown in Table 1.

[0076] Table 1 Performance test of polyvinyl alcohol-based foam material

[0077] The water absorption multiple reflects the ability of the polyvinyl alcohol-based foam material to absorb and lock water, and the density reflects the economic index of the polyvinyl alcohol-based foam material. By detecting the size of the density of the polyvinyl alcohol-based foam material, the internal pore condition of the polyvinyl alcohol-based foam material can also be indirectly reflected, and the size of the pores and pore size of the polyvinyl alcohol-based foam material will affect the discharge of the liquid. As can be seen from the experimental data in Table 1, the polyvinyl alcohol-based foam material containing expanded microspheres has little difference in compression permanent deformation value, water absorption multiple and density compared with the traditional starch foaming method (i.e. the scheme of Comparative Example 2), but is obviously better than the material foamed by air (i.e. the scheme of Comparative Example 1). This shows that dispersing the expanded microspheres in the network structure of the polyvinyl alcohol-based foam material can not only avoid the difficulty of cleaning the starch foaming material and the disadvantage of easy mold growth during storage, but also ensure the density and water absorption multiple of the material, and at the same time, can enhance the support of the network structure of the foam material and improve the compression permanent deformation capacity of the foam material. By comparing the performance test results of the products prepared in Example 1 and Comparative Examples 3 and 4, it can be seen that in the scheme of the present application, the expanded microspheres can significantly improve the compression permanent deformation capacity of the polyvinyl alcohol-based foam material, but when there are only expanded microspheres, the water absorption multiple of the polyvinyl alcohol-based foam material is not high enough. The nucleating agent also has a certain improvement effect on the compression permanent deformation capacity of the polyvinyl alcohol-based foam material, and the improvement amplitude of the water absorption multiple of the polyvinyl alcohol-based foam material is greater than that of the expanded microspheres. Therefore, under the joint action of the two, the compression permanent deformation capacity and water absorption multiple of the polyvinyl alcohol-based foam material are simultaneously significantly improved. By comparing the performance test results of the products prepared in Example 4 and Comparative Examples 5 to 8, it can be seen that in the scheme of the present application, only when the expanded microspheres are expanded at a higher temperature and then the polyvinyl alcohol-based foam material is solidified at a lower temperature, can qualified products be obtained. In the presence of other raw materials of the present application, if the expansion temperature is too low, the expanded microspheres cannot be effectively expanded; if the expansion temperature is too high, the obtained product is unqualified and cannot be tested for performance. Even if the expansion temperature is appropriate, but the expansion time is too long, the effective product that can effectively test the compression permanent deformation capacity, density and water absorption multiple cannot be obtained.

[0078] The above-described examples are only preferred embodiments of the present application and are not intended to limit the protection scope of the present application. For any skilled person in the art, the present application can have various changes and variations. Any simple equivalent changes and modifications made according to the protection scope and content of the specification of the present application shall be included in the protection scope of the present application.

Claims

1. A polyvinyl alcohol-based foam material containing expanded microspheres, characterized in that: The composition comprises the following components in parts by mass: 100-200 parts of polyvinyl alcohol resin, 1-30 parts of nucleating agent, 1-100 parts of expanded microspheres, 0.1-5 parts of foaming agent, 50-200 parts of inorganic strong acid, 50-250 parts of crosslinking agent, and 400-600 parts of water.

2. The polyvinyl alcohol-based foam material containing expanded microspheres according to claim 1, characterized in that: The nucleating agent is at least one of white carbon black, talc, and silica sol; or / and the foaming agent is at least one of Triton-100, Tween-80, and sodium dodecyl sulfate.

3. The polyvinyl alcohol-based foam material containing expanded microspheres according to claim 1, characterized in that: The inorganic strong acid is sulfuric acid and / or hydrochloric acid; or / and the cross-linking agent is at least one of formaldehyde, glutaraldehyde, and boric acid.

4. The polyvinyl alcohol-based foam material containing expanded microspheres according to claim 1, characterized in that: The alcoholysis degree of the polyvinyl alcohol resin is greater than 80 mol%, and the polymerization degree is 500-2200.

5. The method for preparing the polyvinyl alcohol-based foam material containing expanded microspheres according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, mixing the polyvinyl alcohol resin, the nucleating agent and water to obtain a polyvinyl alcohol-based emulsion; S2, cooling the polyvinyl alcohol-based emulsion, and then sequentially adding the expanded microspheres, the foaming agent, the inorganic strong acid, and the cross-linking agent; and mixing them evenly to obtain a polyvinyl alcohol-based foam material prepolymer; S3, heating the polyvinyl alcohol-based foam material prepolymer to expand it, then cooling it, keeping it warm and solidifying it to form it, so as to obtain a polyvinyl alcohol-based foam material containing expanded microspheres.

6. The preparation method according to claim 5, characterized in that The uniform mixing in step S1 is achieved by stirring at 85-100° C.; or / and the uniform mixing in step S2 is achieved by stirring at a speed of 200-400 rpm.

7. The preparation method according to claim 5, characterized in that The heating and curing conditions in step S3 are: first heating to 80-100° C. and maintaining for 1-30 minutes, and then maintaining at 50-70° C. for 6-15 hours.

8. A method for preparing a medical polyvinyl alcohol-based foam material containing expanded microspheres, characterized in that: The method comprises steps S1 to S3 in claim 5 and the following steps: The polyvinyl alcohol-based foam material containing expanded microspheres is washed until it becomes acidic or neutral, and then cut, packaged, and sterilized by radiation to obtain a medical polyvinyl alcohol-based foam material containing expanded microspheres.

9. The preparation method according to claim 8, characterized in that The polyvinyl alcohol-based foam material containing expanded microspheres is washed until the pH value is 4.0-7.

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10. Use of the polyvinyl alcohol-based foam material containing expanded microspheres according to any one of claims 1 to 4 or the medical polyvinyl alcohol-based foam material containing expanded microspheres prepared by the preparation method according to claim 8 in the preparation of medical dressings.

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