A polyvinyl alcohol sponge roller

Abstract

The application relates to a polyvinyl alcohol sponge roller for semiconductor cleaning and a preparation method of the sponge roller. The polyvinyl alcohol sponge roller is composed of an inner shaft and a microporous hydrophilic polyvinyl alcohol sponge attached to the outer surface of the inner shaft, and the polyvinyl alcohol sponge is prepared from the following raw material system: 100 parts of first polyvinyl alcohol, 50-100 parts of second polyvinyl alcohol, 500-800 parts of deionized water, 90-150 parts of formaldehyde aqueous solution, 0.2-0.6 parts of aliphatic dialdehyde aqueous solution and 30-50 parts of sulfuric acid, wherein the polymerization degree of the first polyvinyl alcohol is 1500-2400, and the polymerization degree of the second polyvinyl alcohol is 300-700. The polyvinyl alcohol sponge in the sponge roller has a porosity of 80-92%, a pore size of 5-15 mu m, a water absorption rate of more than 400%, and a 30% compression stress of 5-15 KPa under the condition of 200% water content.

Description

Technical Field

[0001] This invention relates to the field of sponge rollers, and more specifically, to a polyvinyl alcohol sponge roller for semiconductor cleaning and a method for preparing the sponge roller. Background Technology

[0002] As the modern microelectronics industry moves towards large-scale, highly integrated systems, increasingly stringent requirements are being placed on the flatness and cleanliness of wafers. Chemical mechanical planarization (CMP) is currently the only reliable path to achieve nanoscale flatness on wafer surfaces. However, after CMP, the wafers require post-cleaning, which necessitates the use of polyvinyl alcohol (PVA) sponge rollers. PVA sponge rollers consist of a plastic inner shaft and a ring-shaped polyvinyl alcohol sponge tightly attached to the outer surface of the inner shaft.

[0003] Polyvinyl alcohol (PVA) sponge is a hydrophilic sponge material produced by the acetalization reaction of PVA with formaldehyde under acidic conditions. To prepare PVA sponge, pore-forming agents such as starch are typically added to create pores in the PVA sponge. Specifically, during sponge preparation, starch is uniformly dispersed in the system. Simultaneously with the initiation of the acetalization cross-linking reaction, the starch particles absorb water, gradually increase in size, and swell to their maximum size. Under the action of a catalyst, the glycosidic bonds in the starch are hydrolyzed and broken. Finally, after the acetalization and starch hydrolysis reactions are completed, a porous PVA sponge is obtained. The metal ion content varies depending on the origin and variety of starch. Common potato starch and corn starch can have a total metal ion content of up to 1000 ppm. However, the metal ion content of PVA sponge rollers used in semiconductors is typically required to be below 100 ppb, or even below 10 ppb. Therefore, PVA sponge rollers prepared using starch as a pore-forming agent require specialized cleaning equipment and a complex and time-consuming cleaning process to achieve high cleanliness. Furthermore, the starch residue remaining in the sponge rollers is difficult to clean completely, easily leading to mold growth and causing yellowing. As chip manufacturing processes enter the 5-nanometer era, even higher requirements are placed on the cleanliness of PVA sponge rollers.

[0004] To overcome the negative effects of starch as a pore-forming agent, researchers attempted to create pores using surfactant-assisted strong mechanical stirring or SD phase separation technology. However, these methods still have significant drawbacks. For example, adding surfactants introduces a large number of metal ions into the system, requiring a cumbersome cleaning process later. While phase separation technology can avoid the introduction of new substances, it is difficult to prepare PVA sponges with high porosity.

[0005] The information disclosed in the Background section is only for the purpose of helping to understand the background of the present invention, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] To address the aforementioned challenges, this invention aims to provide a novel polyvinyl alcohol (PVA) sponge roller and its preparation method. This invention, without using starch or surfactants or other pore-forming agents, utilizes the synergistic reaction of various PVA raw materials and different aldehydes to prepare a PVA sponge roller in one step. This sponge roller possesses characteristics such as low pore size, high porosity, high water absorption, and suitable compressive stress.

[0007] The pore-forming mechanism of the polyvinyl alcohol sponge of the present invention differs from that in previous literature. The raw materials used include at least two PVA raw materials with different degrees of polymerization and two aldehyde raw materials with different functional groups. It mainly utilizes the differences in migration and reactivity caused by the different viscosity and activity of different PVA raw materials and aldehyde raw materials in the reaction system, so that some PVA reacts first to form a low-shrinkage porous framework structure. Then, within this porous framework, the remaining unreacted PVA undergoes an acetal reaction, thereby forming an overall high-open-porosity, low-shrinkage acetal sponge structure.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a polyvinyl alcohol (PVA) sponge roller, comprising an inner shaft and a microporous hydrophilic PVA sponge attached to the outer surface of the inner shaft, characterized in that the PVA sponge is prepared by reacting the following raw material system, comprising, by weight, the following raw materials: 100 parts of first PVA, 50-100 parts of second PVA, 500-800 parts of deionized water, 90-150 parts of formaldehyde aqueous solution, 0.2-0.6 parts of aliphatic dialdehyde aqueous solution, and 30-50 parts of sulfuric acid; the degree of polymerization of the first PVA is 1500-2400; the degree of polymerization of the second PVA is 300-700; the concentration of the formaldehyde aqueous solution is 37 wt%; the concentration of the aliphatic dialdehyde aqueous solution is 50 wt%; and the concentration of sulfuric acid is 98 wt%.

[0009] The polyvinyl alcohol sponge contained in the sponge roller of the present invention has a porosity of 80-92%, a pore size of 5-15 μm, a water absorption rate of over 400%, and a 30% compressive stress of 5-15 kPa under a water content of 200%.

[0010] When the porosity of polyvinyl alcohol (PVA) sponge is higher than 92%, the actual strength of the sponge material is easily too small. When it is lower than 80%, the PVA sponge is easily not flexible enough in a wet state. Both of these situations are not conducive to its use in the wafer cleaning process.

[0011] Polyvinyl alcohol (PVA) sponges have a pore size of 5–15 μm, with 5–10 μm being preferred. As advanced manufacturing processes upgrade and cleaning performance requirements increase, smaller pore sizes are beneficial for fine cleaning of wafer surfaces. However, if the pore size is too low, below 5 μm, it becomes difficult to ensure the water absorption rate of the sponge roller and the water flow during the cleaning process. Furthermore, it is also difficult to guarantee sufficient elasticity of the sponge material when wet. Conversely, if the pore size is greater than 15 μm, the mesh size becomes too large for demanding fine cleaning requirements.

[0012] Polyvinyl alcohol (PVA) sponges have a water absorption rate of over 400%, with over 600% being preferred. Under the same conditions, a higher water absorption rate indicates that the PVA sponge retains more hydroxyl groups, which is more conducive to increasing water flow during the cleaning process and thus improving cleaning efficiency.

[0013] Polyvinyl alcohol (PVA) sponge material has a 30% compressive stress of 5–15 kPa, preferably 5–10 kPa. When the 30% compressive stress is less than 5 kPa, the PVA sponge material is too soft and is prone to deformation during cleaning after CMP. When the 30% compressive stress is greater than 15 kPa, the sponge material is too hard and may cause metal oxides (various metal oxides are present in the abrasive) adhering to the surface of the sponge roller to scratch the wafer surface during the cleaning process.

[0014] The first polyvinyl alcohol has a degree of polymerization of 1500–2400, preferably 1700–2100. The degree of hydrolysis is not particularly limited, but is typically 88%–99%. The second polyvinyl alcohol has a degree of polymerization of 300–700, preferably 300–500. The degree of hydrolysis is not particularly limited, but is typically 88%–99%.

[0015] When the first polyvinyl alcohol in the raw materials is 100 parts, the second polyvinyl alcohol is 50 to 100 parts. Preferably, the second polyvinyl alcohol is 50 to 80 parts. The mass fractions of the two polyvinyl alcohol raw materials are within this range, which is beneficial to control the pore size of the sponge material within a suitable range.

[0016] When the first polyvinyl alcohol in the raw material is 100 parts, the amount of formaldehyde aqueous solution added is 90-150 parts, and the formaldehyde concentration is 37 wt%. Preferably, the amount of formaldehyde added is 120-130 parts. When the first polyvinyl alcohol in the raw material is 100 parts, the amount of aliphatic dialdehyde added is 0.2-0.6 parts, and the aliphatic dialdehyde concentration is 50%. Preferably, the amount of aliphatic dialdehyde added is 0.4-0.6 parts.

[0017] If the formaldehyde content is too low, the cross-linked network will not be fully formed, and the sponge will be gel-like. If the formaldehyde content is continuously increased, the pore size will become smaller. Although this is beneficial for the fine cleaning of wafers, it will cause an excessive decrease in hydrophilicity. On the one hand, this manifests as a decrease in water absorption. On the other hand, the sponge material will become harder and exhibit insufficient elasticity in a wet state. Specifically, when performing a 30% compression stress test, the sample cannot recover completely or quickly after being compressed by 30%.

[0018] Adding too little aliphatic dialdehyde can lead to two problems: firstly, it cannot effectively reduce the amount of formaldehyde used; secondly, it has a limited impact on pore size and can cause the long axis of the pores to stretch, deforming the pores from the usual circular shape to an elliptical shape. Adding too much will result in pores that are too small, reducing hydrophilicity and making the sponge material less absorbent. It can also easily lead to insufficient elasticity when wet.

[0019] Aliphatic dialdehydes can be one of glyoxal, succinaldehyde, glutaraldehyde, and trimethylglutaraldehyde. Considering reactivity, water solubility, and migration, succinaldehyde and glutaraldehyde are preferred, with glutaraldehyde being the most preferred.

[0020] Because formaldehyde has a small molecular weight, it tends to react with the two adjacent hydroxyl groups on the polyvinyl alcohol (PVA) molecular chain, undergoing intramolecular condensation to form a stable six-membered ring. Aliphatic dialdehydes, on the other hand, have a relatively large molecular weight and two terminal aldehyde groups, making them more likely to react with hydroxyl groups on different PVA molecular chains, linking the different chains together and reducing the distance between them, thus acting as cross-linking bridges. This process leads to the formation of a more complex porous framework structure. As the reaction proceeds, the remaining unreacted PVA continues to react along the framework; therefore, even a very small amount of aliphatic dialdehyde can alter the pore structure of a sponge.

[0021] When the first polyvinyl alcohol in the raw material is 100 parts, the amount of sulfuric acid added is 30-50 parts, and the sulfuric acid concentration is 98%. If the amount of sulfuric acid is too small, the acetal reaction between PVA and the two aldehydes will be slow, the cross-linked network will not be fully formed, and the sponge will be gel-like.

[0022] The preparation method of this polyvinyl alcohol sponge roller is not particularly limited and may include the following steps:

[0023] (1) Dissolve a certain mass fraction of the first polyvinyl alcohol and the second polyvinyl alcohol in deionized water to obtain two polyvinyl alcohol aqueous solutions;

[0024] (2) Then mix the two polyvinyl alcohol aqueous solutions evenly, and add 37wt% formaldehyde, 50wt% aliphatic dialdehyde and 98wt% sulfuric acid in a predetermined mass fraction. Stir for 30 minutes to mix evenly to obtain a mixed reaction solution.

[0025] (3) After removing the air bubbles from the mixed reaction solution, pour it into the sponge roller mold, seal the mold, and place it in an oven at 80°C for 5 hours to cure. After demolding, take out the sponge roller and clean it with deionized water to obtain the polyvinyl alcohol sponge roller.

[0026] The above preparation process is preferably carried out in a Class 100 cleanroom.

[0027] The advantages of this invention are: the polyvinyl alcohol (PVA) sponge roller can be used for post-CMP cleaning of wafers. The sponge material of the roller has a porosity of 80-92% and a pore size of 5-15 μm. Under conditions of 200% moisture content, the compressive stress at 30% is 5-15 kPa. Because this PVA sponge roller does not use starch, it can be used in the post-CMP cleaning process of wafers after simple post-cleaning. Furthermore, by adding a very small amount of aliphatic dialdehyde during the preparation of the sponge roller, the amount of formaldehyde used can be significantly reduced, by more than 20%. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope image of the sponge material in the polyvinyl alcohol sponge roller prepared in Example 2;

[0029] Figure 2 This is a photograph of the sponge roller prepared in Example 2. Detailed Implementation

[0030] The technical solution of the present invention will be further described and illustrated below through specific embodiments, but the present invention is not limited to the embodiments described. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0031] The testing methods for pore size, porosity, separation efficiency, and water flux are as follows.

[0032] Pore ​​size: The average pore size of the sponge was obtained by statistically analyzing the SEM images of the sponge using Image-Pro Plus 6.0 software.

[0033] Porosity and water absorption: The sponges from the polyvinyl alcohol sponge roller were cut into regular cubic samples and completely dried using a freeze dryer to measure their volume. Then, the sponges were immersed in beakers filled with water to promote complete water absorption. Afterward, the absorbent sponges were placed on the support of a density balance to measure their mass in water. Finally, the sponges were removed from the water, and their mass in air filled with absorbed water was measured. Each set of sponges was measured five times, and the results can be calculated using the following formula:

[0034] F=(m1-m2)g=ρ W gV0

[0035]

[0036]

[0037]

[0038] Where F is the buoyancy force on the sponge; P is the porosity of the sponge; ρ is the apparent density of the sponge; W is the water absorption rate of the sponge; ρ W It is the density of water, with a value of 1 g / cm³. 3 m0 is the mass of the dry sponge; m1 is the mass of the absorbent sponge in the air; m2 is the mass of the absorbent sponge in water; V0 is the volume of the absorbent sponge; V1 is the volume of the internal pores of the sponge; V2 is the volume of the dry sponge.

[0039] Compression stress at 30%: Controlling the water absorption rate of the sponge to 200%, under this moisture content condition, the sponge is cut into lengths (height in the longitudinal direction) of 30 mm between opposite ends, placed in the compression fixture of the universal testing machine, and then the length of the sponge is compressed downward in the longitudinal direction by 30% (9 mm) in a manner that applies a load to the entire end surface. The load is recorded and divided by the area of ​​the end surface to obtain the compression stress at 30%.

[0040] Example 1

[0041] The following is a method for preparing a sponge roller, in which all preparation and cleaning steps are carried out in a Class 100 cleanroom.

[0042] 100 parts by mass of PVA1799 and 50 parts by mass of PVA0388 were dissolved in a certain amount of distilled water to obtain two polyvinyl alcohol aqueous solutions; then the two polyvinyl alcohol aqueous solutions were mixed evenly to obtain a polyvinyl alcohol mixture containing 100 parts by mass of PVA1799, 50 parts by mass of PVA0388 and 750 parts by mass of deionized water.

[0043] Then, to the above polyvinyl alcohol mixture, add 123 parts by weight of 37 wt% formaldehyde and 0.5 parts by weight of 50 wt% glutaraldehyde. Also add 47 parts by weight of 98% sulfuric acid diluted with deionized water. Stir for 30 minutes to mix thoroughly, obtaining a mixed reaction solution. During the mixing process, continue to add an appropriate amount of deionized water to this mixed reaction solution, so that the total deionized water content in the mixed reaction solution is 1200 parts by weight.

[0044] After removing air bubbles from the mixed reaction solution, it is poured into the sponge roller mold, the mold is sealed, and the mold is placed in an oven at 80°C for 5 hours to cure. After demolding, the sponge roller is taken out and cleaned with deionized water to obtain the polyvinyl alcohol sponge roller.

[0045] Example 2

[0046] The following is a method for preparing a sponge roller, in which all preparation and cleaning steps are carried out in a Class 100 cleanroom.

[0047] 100 parts by mass of PVA1799 and 67 parts by mass of PVA0388 were dissolved in a certain amount of distilled water to obtain two polyvinyl alcohol aqueous solutions; then the two polyvinyl alcohol aqueous solutions were mixed evenly to obtain a polyvinyl alcohol mixture containing 100 parts by mass of PVA1799, 67 parts by mass of PVA0388 and 900 parts by mass of deionized water.

[0048] Then, to the above polyvinyl alcohol mixture, add 123 parts by weight of 37 wt% formaldehyde and 0.5 parts by weight of 50 wt% glutaraldehyde. Also add 47 parts by weight of 98% sulfuric acid diluted with deionized water. Stir for 30 minutes to mix thoroughly, obtaining a mixed reaction solution. During the mixing process, continue to add an appropriate amount of deionized water to this mixed reaction solution, so that the total deionized water content in the mixed reaction solution is 1200 parts by weight.

[0049] After removing air bubbles from the mixed reaction solution, it is poured into the sponge roller mold, the mold is sealed, and the mold is placed in an oven at 80°C for 5 hours to cure. After demolding, the sponge roller is removed and cleaned with deionized water to obtain the polyvinyl alcohol sponge roller.

[0050] Example 3

[0051] A method for preparing a sponge roller is as follows, which differs from Example 2 in that: the mass fraction of PVA0388 is 100 parts by mass, and the rest are the same as in Example 2.

[0052] Comparative Example 1

[0053] A method for preparing a sponge roller is as follows, which differs from Example 2 in that the mass fraction of PVA0388 is 25 parts by mass, while the rest are the same as in Example 2.

[0054] Comparative Example 2

[0055] A method for preparing a sponge roller is as follows, which differs from Example 2 in that the mass fraction of PVA0388 is 150 parts by mass, and the rest is the same as in Example 2.

[0056]

[0057] The average pore size of Examples 1-3 is 5-15 μm, the porosity is 80-92%, and the water absorption rate is over 400%; under a water content of 200%, the compressive stress at 30% is 5-15 kPa. A scanning microscope image of the sponge material in the sponge roller of Example 2 is shown below. Figure 1 As shown, the scanning microscope images of the other embodiments are similar. A photograph of the actual sponge roller prepared in Example 2 is shown below. Figure 2 As shown.

[0058] Examples 1-3 were prepared under the same conditions except for the increasing mass fraction of PVA0388. The mass fractions of PVA0388 were 50, 67, and 100, respectively. As the mass fraction increased, the pore size gradually increased, the porosity gradually increased, and the water absorption rate continuously increased.

[0059] Comparative Example 1 has a small average pore size and low porosity, and does not rebound after compression under 30% compressive stress. Comparative Example 2, with a pore size of 18.1 μm, also exhibits no rebound after compression under 30% compressive stress. This may be due to the higher content of PVA0388 added, consuming more aldehydes in the system, resulting in insufficient reaction with PVA1799.

[0060] Example 4

[0061] The preparation method of a sponge roller is as follows, which differs from Example 2 in that the mass fraction of formaldehyde solution is 150 parts by mass, and the rest is the same as in Example 2.

[0062] Example 5

[0063] A method for preparing a sponge roller is as follows, which differs from Example 2 in that the formaldehyde solution has a mass fraction of 90 parts, while the rest are the same as in Example 2.

[0064] Comparative Example 3

[0065] A method for preparing a sponge roller is as follows, which differs from Example 2 in that the mass fraction of formaldehyde solution is 180 parts by mass, while the rest are the same as in Example 2.

[0066] Comparative Example 4

[0067] A method for preparing a sponge roller is as follows, which differs from Example 2 in that the formaldehyde solution has a mass fraction of 80 parts, while the rest are the same as in Example 2.

[0068]

[0069] Comparing Examples 2, 4, and 5 longitudinally, the higher the mass fraction of formaldehyde solution, the smaller the pore size. This is mainly because as the amount of formaldehyde increases, the number of cross-linking points per unit volume also increases, making the cross-linked network's skeletal structure denser and thus reducing the pore size. Furthermore, the increase in formaldehyde content also reduces the number of remaining hydroxyl groups in the sponge, affecting its hydrophilicity.

[0070] As shown in Comparative Example 3, as the formaldehyde content increased to 180 parts by mass, the pore size of the sponge decreased to 3.5 μm, the water absorption decreased to 270%, and it did not rebound after compression during the 30% compressive stress test.

[0071] As shown in Comparative Example 4, as the formaldehyde content was reduced to 80 parts by mass, a normal microporous sponge could not be prepared; only a gel-like substance could be obtained. It was impossible to measure its pore size, water absorption rate, and 30% compressive stress. This was mainly because the amount of formaldehyde added was insufficient, resulting in insufficient cross-linking and the inability to form a network skeleton structure.

[0072] Example 6

[0073] A method for preparing a sponge roller is as follows, which differs from Example 2 in that: the 50wt% glutaraldehyde solution is 0.2 parts by mass, and the rest are the same as in Example 2.

[0074] Example 7

[0075] A method for preparing a sponge roller is as follows, which differs from Example 2 in that: the 50wt% glutaraldehyde solution is 0.6 parts by mass, and the rest are the same as in Example 2.

[0076] Comparative Example 5

[0077] A method for preparing a sponge roller is as follows, which differs from Example 2 in that: the 50wt% glutaraldehyde solution is 0.1 parts by mass, and the rest are the same as in Example 2.

[0078] Comparative Example 6

[0079] A method for preparing a sponge roller is as follows, which differs from Example 2 in that: the 50wt% glutaraldehyde solution is 0.65 parts by mass, and the rest are the same as in Example 2.

[0080]

[0081] Comparing Examples 2, 6, and 7 longitudinally, the addition of only 0.2–0.6 parts by mass of glutaraldehyde solution resulted in a very drastic reduction in pore size. Because formaldehyde has a small molecular weight, it tends to react with the two adjacent hydroxyl groups on the polyvinyl alcohol (PVA) molecular chain, undergoing intramolecular condensation to form a stable six-membered ring. Glutaraldehyde, with its relatively large molecular weight and two terminal aldehyde groups, is more inclined to react with hydroxyl groups on different PVA molecular chains, connecting the different chains and reducing the distance between them, thus acting as a cross-linking bridge. This process leads to the establishment of a more complex porous framework structure. As the reaction proceeds, the remaining unreacted PVA continues to react along the framework; therefore, even a very small amount of glutaraldehyde can alter the pore structure of the sponge.

[0082] As shown in Comparative Example 5, when the 50wt% glutaraldehyde solution is 0.1 parts by mass, the bridging between molecules is insufficient, the morphology of the bubbles is significantly deformed, and many irregular pore sizes appear, with a porosity as high as 93%, while the 30% compression pressure test is only 1.3 kPa.

[0083] As shown in Comparative Example 6, when the 50wt% glutaraldehyde solution is 0.65 parts by mass, the bridging between molecules is excessive, the pore size of the bubble decreases to 3.3μm, the porosity is only 80%, and it cannot rebound after compression under 30% pressure test.

[0084] Comparative Example 7

[0085] The following is a method for preparing a sponge roller, in which all preparation and cleaning steps are carried out in a Class 100 cleanroom.

[0086] 100 parts by mass of PVA1799 and 67 parts by mass of PVA0388 were dissolved in a certain amount of distilled water to obtain two polyvinyl alcohol aqueous solutions; then the two polyvinyl alcohol aqueous solutions were mixed evenly to obtain a polyvinyl alcohol mixture containing 100 parts by mass of PVA1799, 67 parts by mass of PVA0388 and 900 parts by mass of deionized water.

[0087] Then, 123 parts by mass of 37 wt% formaldehyde were added to the above polyvinyl alcohol mixture. Then, 47 parts by mass of 98% sulfuric acid, diluted with deionized water, were also added. The mixture was stirred for 30 minutes to ensure homogeneity, resulting in a mixed reaction solution. During the mixing process, an appropriate amount of deionized water was continuously added to this mixed reaction solution, so that the total deionized water content in the mixed reaction solution was 1200 parts by mass.

[0088] After removing air bubbles from the mixed reaction solution, it is poured into the sponge roller mold, the mold is sealed, and the mold is placed in an oven at 80°C for 5 hours to cure. After demolding, the sponge roller is removed and cleaned with deionized water to obtain the polyvinyl alcohol sponge roller.

[0089] Comparative Example 8

[0090] A method for preparing a sponge roller is as follows, which differs from Comparative Example 7 in that: 37wt% of formaldehyde is 180 parts by mass, and the rest are the same as Comparative Example 7.

[0091]

[0092]

[0093] Comparative Examples 7 and 8, without the addition of aliphatic dialdehyde, showed a significantly larger pore size compared to Example 2 with the addition of glutaraldehyde, exceeding 20 μm. Comparative Examples 7 and 8 demonstrate that the pore size decreases with increasing formaldehyde content. Due to the larger pore size, their 30% compressive stress was greater than 20 kPa.

[0094] Example 8

[0095] A method for preparing a sponge roller is as follows, which differs from Example 2 in that: instead of using 0.5 parts by weight of 50% glutaraldehyde solution, 0.5 parts by weight of 50 wt% butyraldehyde solution is used, while the rest are the same as in Example 2.

[0096] Comparative Example 9

[0097] A method for preparing a sponge roller is as follows, which differs from Example 2 in that: instead of using 0.5 parts by weight of 50% glutaraldehyde solution, 0.5 parts by weight of 50 wt% adipaldehyde solution is used, while the rest is the same as in Example 2.

[0098]

[0099] Comparing Examples 2 and 8 longitudinally, the 50% glutaraldehyde solution was changed to a 50% succinaldehyde solution. As can be seen from the above data, succinaldehyde is not as effective as glutaraldehyde in reducing cell size, and the 30% compressive stress is slightly higher.

[0100] As can be seen from Example 2 and Comparative Example 9, after adding 50wt% adipic aldehyde solution, the foam cells underwent irregular deformation, and did not rebound after compression during the 30% compressive stress test.

Claims

1. A polyvinyl alcohol sponge roller, the sponge roller comprising an inner shaft and a microporous hydrophilic polyvinyl alcohol sponge attached to the outer surface of the inner shaft, characterized in that, The polyvinyl alcohol sponge is prepared by reacting the following raw material system, which, by weight, includes the following raw materials: 100 parts of first polyvinyl alcohol, 50-100 parts of second polyvinyl alcohol, 500-800 parts of deionized water, 90-150 parts of formaldehyde aqueous solution, 0.2-0.6 parts of aliphatic dialdehyde aqueous solution, and 30-50 parts of sulfuric acid; the degree of polymerization of the first polyvinyl alcohol is 1500-2400; the degree of polymerization of the second polyvinyl alcohol is 300-700; the concentration of the formaldehyde aqueous solution is 37 wt%; the concentration of the aliphatic dialdehyde aqueous solution is 50 wt%; and the concentration of sulfuric acid is 98 wt%, wherein the aliphatic dialdehyde is one of butyraldehyde and glutaraldehyde.

2. In the polyvinyl alcohol sponge roller according to claim 1, when the first polyvinyl alcohol is 100 parts, the second polyvinyl alcohol is 50 to 80 parts.

3. In the polyvinyl alcohol sponge roller according to claim 1, the amount of formaldehyde added is 120-130 parts, and the amount of aliphatic dialdehyde added is 0.4-0.6 parts.

4. In the polyvinyl alcohol sponge roller according to claim 1, the aliphatic dialdehyde is glutaraldehyde.

5. The method for preparing the polyvinyl alcohol sponge roller according to claim 1, comprising the following steps: (1) Dissolve a certain mass fraction of the first polyvinyl alcohol and the second polyvinyl alcohol in deionized water to obtain two polyvinyl alcohol aqueous solutions; (2) Then mix the two polyvinyl alcohol aqueous solutions evenly, and add 37wt% formaldehyde, 50wt% aliphatic dialdehyde and 98wt% sulfuric acid in a predetermined mass fraction. Stir for 30 minutes to mix evenly to obtain a mixed reaction solution. (3) After removing the air bubbles from the mixed reaction solution, pour it into the sponge roller mold, seal the mold, and place it in an oven at 80°C for 5 hours to cure. After demolding, take out the sponge roller and clean it with deionized water to obtain the polyvinyl alcohol sponge roller.

Images