Hydrophilic porous polyethylene film, preparation method thereof and fever cooling patch prepared from hydrophilic porous polyethylene film

Abstract

The invention relates to the technical field of polymer films, in particular to a hydrophilic porous polyethylene film, a preparation method thereof and a fever cooling patch prepared from the hydrophilic porous polyethylene film. The polyethylene film is prepared by using a two-way stretching process, and the modified PE film obtained by dipping in a compound hydrophilic solution mainly comprising Tween 80 and gradient drying is better in softness and comfort and lighter in overall weight compared with a traditional material; in the cooling effect, compared with traditional spunlace cloth, the cooling patch has better moisture permeability and water retention, the cooling duration is 6.5 h or above, the moisture permeability per 24 h is about 8000 + / -150 g / m < 2 >, and the cooling patch far exceeds the industrial standard.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer films, in particular to a hydrophilic porous polyethylene film, a preparation method thereof, and a fever-reducing patch prepared using the same. Background Art

[0002] The gel layer of conventional cooling patches is usually composed of hydrogel materials (such as sodium polyacrylate, carboxymethyl cellulose, etc.), which achieve physical cooling through water evaporation and heat absorption. However, its base film is mostly made of hard spunlace non-woven fabric as the supporting layer. Although this material has certain air permeability and cost advantages, it has problems with insufficient softness and ductility, resulting in the following limitations: (1) Poor fit: Due to the high hardness of spunlace fabric, it is difficult to fit tightly to the curved surface of the skin (such as the forehead, joints, etc.), which easily creates gaps and affects the effective cooling effect of the gel layer; (2) Low comfort: During activities, the hard film material may wrinkle or fall off due to bending and deformation, reducing the user experience; (3) Limited breathability: Although spunlace fabric has certain breathability, its structural density may still hinder the efficient evaporation of water vapor, weakening the durability of the cooling effect.

[0003] In addition, spunlace fabrics have slow liquid absorption, low tensile strength, and a longitudinal tensile strength of less than 30N. They are also prone to fiber shedding (particle residue ≥5mg / sheet after friction testing). Among existing medical substrates, ordinary PE films (>20μm) are too thick, resulting in insufficient flexibility (bending stiffness >2mN·m). While biaxially oriented ultra-thin PE films (0.5-100μm) have excellent mechanical strength (longitudinal tensile strength ≥50MPa) and breathability (porosity ≥50%), their hydrophobic properties hinder their use in hydrophilic dressings. Conventional modified PE films, such as those treated with plasma, only maintain hydrophilicity for 24 hours, and the equipment costs are enormous. When using blended modified PE films, the modified materials can reduce porosity by more than 40%, resulting in poorer air and moisture permeability.

[0004] CN201610483961 discloses a fever-reducing patch and its preparation process. The patch comprises: a non-woven fabric, a hydrogel layer, and a membrane isolation layer; the hydrogel layer is coated on the non-woven fabric, and the membrane isolation layer covers the hydrogel layer; the hydrogel is composed of the following components by weight: 0.1-5% water-soluble cooling agent, 0.1-5% cross-linking curing agent, 0.01-5% stabilizing softener, 0.1-20% thickener, and 0.1-20% forming agent. This technology features the use of non-woven fabric as the base material and certain innovative adjustments to the hydrogel formula. By subjecting BOPE film to a special surface hydrophilic modification and using it as a base material, the surface is coated with hydrogel to produce a fever-reducing patch with high cooling efficiency and low production cost. However, the base material is relatively stiff and not thin and soft enough, resulting in the hydrogel layer, which plays the main role in cooling fever, not being able to fully adhere to the area where it is needed.

[0005] The conventional combination mode of the base film layer and the hydrogel layer in the existing technology will affect the overall heat transfer and heat conduction efficiency of the cooling patch. The spunlace fabric used in the traditional cooling patch is also prone to fiber shedding during production and use (after friction testing, the residual particles are ≥5mg / piece).

[0006] Therefore, providing a fever-reducing patch with balanced softness and flexibility has great application prospects. Summary of the Invention

[0007] The present invention prepares a new type of fever-reducing patch by laminating a hydrophilically treated biaxially oriented polyolefin film with a hydrogel layer. The fever-reducing patch can improve the overall softness and planar flexibility of the fever-reducing patch due to its thin and soft base film layer, so that it can be completely adhered to the body part that needs to be cooled and fever-reducing for a long time during use. In addition, the present invention combines the chemical bonding mode between the base film layer and the hydrogel layer to reduce the addition of other unstable substances used for interface bonding, so as to improve the overall heat conduction and fever-reducing efficiency of the fever-reducing patch. Furthermore, using a plastic film as a base film material solves the problem of base material fiber shedding during use, while making the product more beautiful as a whole. To achieve this purpose, the present invention is implemented through the following technical solutions.

[0008] A first aspect of the present invention provides a method for preparing a hydrophilic porous polyethylene membrane, comprising the following steps:

[0009] S1. A polyolefin-based polymer and a lubricant are added to a twin-screw extruder, blended and extruded into a gel film, which is then formed into a film by a stretching process, and finally extracted and annealed to obtain a polyolefin film. The surface pH of the polyolefin film is adjusted to 6.5-7.5;

[0010] S2. The polyolefin film is wound and passed through a solution tank containing a hydrophilic liquid at a speed of 0.5-2m / min;

[0011] S3. The polyolefin film treated in S2 is washed with distilled water and dried to obtain a hydrophilic porous polyethylene film.

[0012] In some preferred embodiments, the stretching process in S1 specifically comprises: simultaneous biaxial stretching, stretching the gel film to 16 times the original size at a temperature of 90-110°C and a speed of 6-12 m / min; then stretching the film to 64 times the original size at a temperature of 110-120°C and a speed of 3-6 mm / min; and then stretching the film to 200 times the original size at a temperature of 120-135°C and a speed of 1.2-3 m / min.

[0013] In some preferred embodiments, the polyolefin film has a thickness of 0.5-100 μm, a pore size of 20-40 nm, and a porosity of 20-75%.

[0014] In some preferred embodiments, the hydrophilic liquid has a raw material composition by mass percentage of: 5-15% wt Tween 80, 2-5% wt polyethylene glycol 400, 10-20% wt anhydrous ethanol, and the balance deionized water.

[0015] Adjusting the surface pH value of the polyolefin film in S1 to 6.5-7.5 is to stabilize the HLB value of Tween 80 (prevent acid hydrolysis), avoid damage to the PE molecular chain in alkaline conditions, and improve the uniformity of the active agent in the pores.

[0016] In some preferred embodiments, the solution tank in S2 is provided with ultrasonic assistance, and the power is 300 W.

[0017] In some preferred embodiments, the temperature of the liquid tank is 25±2°C.

[0018] Using the hydrophilic liquid to impregnate the polyolefin film can ensure that the inner wall of the polyolefin film pores is wetted, further improving the hydrophilic properties of the material.

[0019] In some preferred embodiments, the drying in S3 specifically comprises: drying at 35-45°C for 2-5 min, and then vacuum drying at 20-30°C for 8-15 min.

[0020] Through the double drying steps, the inner pore surfactant can be further solidified, and its hydrophilicity is maintained.

[0021] In some preferred embodiments, the lubricant comprises at least one of petrolatum, polyethylene wax, liquid paraffin, polydimethylsiloxane, calcium stearate, zinc stearate, and stearic acid monoglyceride.

[0022] The second aspect of the present application provides a hydrophilic porous polyethylene film obtained by the above preparation method.

[0023] The third aspect of the present application provides a fever-reducing patch comprising, from top to bottom, an anti-adhesion layer, a hydrogel layer and a hydrophilic porous polyethylene film layer.

[0024] In some preferred embodiments, the preparation method of the fever-reducing patch comprises: coating a hydrogel monomer solution on the surface of the hydrophilic porous polyethylene film, and combining the anti-adhesion layer with the hydrogel layer after solidification to obtain the fever-reducing patch.

[0025] In some preferred embodiments, the coating amount of the hydrogel monomer solution is 60-90 g / m 2 The anti-adhesion layer is a non-woven fabric.

[0026] The embodiments of the present application have the following beneficial effects:

[0027] (1) The present application uses a biaxial stretching process to prepare a polyethylene film, which is immersed in a complex hydrophilic solution mainly containing Tween 80 and dried in a gradient manner, so that the modified PE film has better flexibility and comfort, and is lighter in overall weight compared to traditional materials. In terms of cooling effect, the fever-reducing patch of the present application has better moisture permeability and water retention compared to traditional spunlace fabric. When the temperature sensor wrapped with the fever-reducing patch of the present application is placed in a 39℃ oven, the temperature change of the sensor is recorded over time, and the cooling duration of the fever-reducing patch of the present application is averagely more than 6.5h. The moisture permeability is tested by the positive cup method, and the moisture permeability is about 8000±150g / m 2 per 24h, which is much higher than the industry standard.

[0028] (2) Compared with the spunlace fabric backing material, the plastic backing film of the present application is light and thin in texture, soft and moderate in tear resistance. In the use process, the overall fitting form of the fever-reducing patch is mainly determined by the gel layer, which can ensure the bending fitting of any shape with any part of the body that needs to be cooled.

[0029] (3) The traditional fever-reducing patch is thick, has poor moisturizing effect, and is prone to fiber shedding. The present application performs hydrophilic treatment on the backing film layer, so that the two interfaces are combined by chemical bonding mode, and finally form an integral, tightly connected, thin and breathable film. The material performance of the film layer is stable and will not be affected by the reaction of the water gel layer, thereby improving the overall heat conduction and heat absorption effect of the fever-reducing patch. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application.

[0031] Figure 1Schematic diagram of the structure of the cooling patch of the present invention.

[0032] Figure 2 This is a scanning electron microscope image of the polyolefin film prepared in Example 1.

[0033] Figure 3 This is the tensile stress-strain diagram of the PE film after hydrophilic treatment.

[0034] Figure 4 This is the contact angle diagram of the film of Comparative Example 1 that was not subjected to hydrophilic treatment.

[0035] Figure 5 This is the contact angle diagram of the film in Example 2.

[0036] Figure 6 This is the contact angle diagram of the hydrophilic treated film in comparative example 2. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, each embodiment of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in each embodiment of the present invention, many technical details are provided to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in this application can be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with each other and referenced to each other under the premise that there is no contradiction.

[0038] The information of the raw materials used in the present invention is as follows:

[0039] Ultra-high molecular weight polyethylene was purchased from Mitsui Chemicals, Japan, model: 145M, average molecular weight 500w;

[0040] The lubricant was purchased from Shanghai Better Chemical Co., Ltd., CAS No.: 8042-47-5, liquid paraffin.

[0041] Example 1

[0042] A hydrophilic porous polyethylene membrane, the preparation method comprising the following steps:

[0043] S1. Polyethylene and lubricant were added to a twin-screw extruder at a mass ratio of 9:1, and the mixture was extruded into a gel film. The film was then stretched into a thin film. Finally, the film was extracted and annealed to obtain a polyolefin film. The surface pH of the polyolefin film was adjusted to between 6.5 and 7.5 using a sodium citrate system. Specifically, the polyolefin film was immersed in a 0.1 mol / L sodium citrate solution for 2-3 minutes. The polyolefin film had a thickness of 3 μm, a pore size of approximately 30 nm, a porosity of 40%, and a puncture strength of approximately 1 gf / μm. See [1] for details. Figure 2 ;

[0044] The specific steps of the stretching process described in S1 are: simultaneous biaxial stretching, stretching the gel film to 16 times its original size at a temperature of 100°C at a speed of 7 m / min; then stretching the film to 64 times its original size at a temperature of 115°C at a speed of 5 mm / min; then stretching the film to 200 times its original size at a temperature of 130°C at a speed of 2 m / min;

[0045] S2. The polyolefin film is rolled up and passed through a solution tank containing a hydrophilic liquid at a speed of 0.5 m / min. The solution tank temperature is 25 ± 2 ° C.

[0046] The composition of the hydrophilic liquid is as follows, in percentage by mass: 5% wt Tween 80, 2% wt polyethylene glycol 400, 10% wt anhydrous ethanol, and the balance deionized water.

[0047] S3. The polyolefin film treated in S2 was washed with distilled water, dried at 40°C for 3 min, and then vacuum-dried at 25°C for 10 min to obtain a hydrophilic porous polyethylene film.

[0048] The specific steps of extraction and annealing treatment in S1 are:

[0049] (1) Extraction:

[0050] Step 1: multi-stage countercurrent impregnation;

[0051] The stretched film passes through 3 to 5 extraction tanks continuously, and the tanks are filled with dichloromethane (main solvent). Temperature: 50℃;

[0052] Residence time: 1 to 3 minutes per tank

[0053] Step 2: Rinse and drain;

[0054] Rinse away any residual oil with clean solvent and drain the surface solvent.

[0055] Rinse solvent purity (oil content <0.1%), drain time (≤30 seconds).

[0056] Step 3: hot air drying;

[0057] The film is dried by passing through a hot air oven. Temperature: 60-80℃

[0058] Air speed: 10-20 m / s; Residual solvent: ≤ 100 ppm

[0059] (2) Annealing:

[0060] Step 1: High temperature relaxation

[0061] The dried film is passed through a heat setting oven under tension constraint. Temperature: 120-135℃ (5-15℃ below melting point) Time: 1-3 minutes

[0062] Step 2: Constant tension control

[0063] Low constant tension (about 10-20% of the stretching tension) is applied in MD / TD direction. MD tension: 5-15 N / m

[0064] TD tension: locked by tenter width (avoid shrinkage)

[0065] Step 3: Slow cooling and winding

[0066] After setting, the temperature is gradually decreased to below 50℃, and the film is wound under constant tension.

[0067] Control parameter: cooling rate ≤ 10℃ / s.

[0068] A fever-reducing patch, as shown in the structure Figure 1 from top to bottom, including an anti-sticking layer of non-woven fabric, a hydrogel layer, and a hydrophilic porous polyethylene film layer, the preparation method comprising: coating a hydrogel monomer solution on the surface of the hydrophilic porous polyethylene film, the coating amount being 60 g / m 2 After UV curing, the anti-sticking layer of non-woven fabric is combined with the hydrogel layer to obtain the fever-reducing patch.

[0069] Example 2

[0070] The difference between this example and Example 1 is that the composition of the hydrophilic liquid is 15% wt Tween 80, 5% wt polyethylene glycol 400, 20% wt anhydrous ethanol, and the balance is deionized water.

[0071] Example 3

[0072] The difference between this example and Example 1 is that polyethylene is replaced by polypropylene, purchased from SABIC, model: PP-UMS.

[0073] Example 4

[0074] The difference between this embodiment and embodiment 1 is that in S2, the polyolefin film is treated with plasma instead of hydrophilic liquid. The specific steps are: using O2 / Ar mixture (4:1V / V) at normal pressure with a power density of 100W / cm 3 , executed every 30 seconds for three consecutive times.

[0075] Comparative Example 1

[0076] This embodiment differs from embodiment 1 in that no hydrophilic treatment is performed.

[0077] Films that are not hydrophilic treated have a contact angle above 90°, and direct compounding with hydrogels will result in poor hydrogel adhesion and delamination after curing;

[0078] The contact angle of the film without hydrophilic treatment in Comparative Example 1 is shown in FIG. Figure 4 The contact angle of the film of Example 2 after hydrophilic treatment is shown in FIG. Figure 5 .

[0079] Comparative Example 2

[0080] The difference between this embodiment and embodiment 1 is that a single component of Tween 80 is used for hydrophilic treatment, and the hydrophilic solution is composed of 15%wt Tween 80 and the balance of deionized water in terms of mass percentage;

[0081] Comparative Example 2: The contact angle of the hydrophilic treated film is shown in FIG. Figure 6 .

[0082] Performance Testing

[0083] (1) Stress-strain test:

[0084] Test method:

[0085] Figure 3 This is the tensile stress-strain diagram of the PE film after hydrophilic treatment. Sample 1 in the figure is the product of Example 1, and Sample 2 is the product of Example 2. It can be seen from the figure that: during the stress-strain tensile test, the treated hydrophilic PE film substrate has good consistency in both directions, and the elongation at break is above 80%, and the stress is greater than 250 MPa. The PE film after hydrophilic treatment maintains excellent mechanical strength and elongation.

[0086] (2) Moisture permeability test

[0087] Test standard: Water vapor transmission rate of breathable film dressings, standard number YY / T047.2-2004, test method for contact wound dressings Part 2: Water vapor transmission rate of breathable film dressings, positive cup method for testing the moisture permeability of hydrophilic base films;

[0088] Table 1

[0089]

[0090]

[0091] (3) Contact angle test

[0092] The contact angle results are as follows Figure 6 As shown by Figure 6 It can be seen that the compound Tween 80 hydrophilic solution has the best effect and the smallest contact angle. After the test stabilizes (30 seconds after the test starts), it is basically stable below 65°, followed by the plasma treatment hydrophilic method.

[0093] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a hydrophilic porous polyethylene membrane, characterized in that: The following steps are involved: S1. A polyolefin-based polymer and a lubricant are added to a twin-screw extruder, blended and extruded into a gel film, which is then formed into a film by a stretching process, and finally extracted and annealed to obtain a polyolefin film. The surface pH of the polyolefin film is adjusted to 6.5-7.5; S2. The polyolefin film is wound and passed through a solution tank containing a hydrophilic liquid at a speed of 0.5-2m / min; S3. The polyolefin film treated in S2 is washed with distilled water and dried to obtain a hydrophilic porous polyethylene film.

2. The preparation method according to claim 1, characterized in that The polyolefin film has a thickness of 0.5-100 μm, a pore diameter of 20-40 nm, and a porosity of 20-75%.

3. The preparation method according to claim 2, characterized in that Calculated by mass percentage, the raw material composition of the hydrophilic liquid is: 5-15% wt Tween 80, 2-5% wt polyethylene glycol 400, 10-20% wt anhydrous ethanol, and the balance deionized water.

4. The preparation method according to claim 3, characterized in that The solution tank in S2 is equipped with ultrasonic assistance and has a power of 300W.

5. The preparation method according to claim 4, characterized in that The specific steps of drying in S3 are: drying at 35-45°C for 2-5 minutes, and then drying under vacuum at 20-30°C for 8-15 minutes.

6. The preparation method according to claim 5, characterized in that The lubricant includes at least one of petrolatum, polyethylene wax, liquid paraffin, polydimethylsiloxane, calcium stearate, zinc stearate, and stearic acid monoglyceride.

7. A hydrophilic porous polyethylene membrane, characterized in that The method is obtained by the preparation method according to any one of claims 1 to 6.

8. A fever-reducing patch, characterized in that: From top to bottom, it comprises an anti-adhesive layer, a hydrogel layer and the hydrophilic porous polyethylene film layer according to claim 7.

9. The cooling patch according to claim 8, characterized in that: The preparation method of the cooling patch comprises: coating a hydrogel monomer solution on the surface of a hydrophilic porous polyethylene film, and after curing, laminating and combining an anti-sticking layer with the hydrogel to obtain the cooling patch.

10. The cooling patch according to claim 9, characterized in that: The coating amount of the hydrogel monomer solution is 60-90g / m 2 , the anti-sticking layer is non-woven fabric.

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