Light-transmitting and breathable polymeric membrane as well as preparation method and application thereof

Abstract

The invention discloses a light-transmitting and breathable polymeric membrane as well as a preparation method and application thereof. According to the invention, the light-transmitting and breathable polymeric membrane is successfully obtained, and the light-transmitting and breathable polymeric membrane comprises a metallocene high-molecular polymer; the light transmittance of the light-transmitting and breathable polymeric membrane is 80%-99%; the haze is 30%-51%, and the gas permeation rate per unit film thickness is 0.8 * 10 <-4 >-2 * 10 <-2 > L / (cm < 2 >. Min.mu m); the thickness of the film is 50-500 microns; the porosity is 0-30%; and the elongation at break is 33%-380%. In general, the light-transmitting and breathable polymeric membrane is high in transparency, low in haze, high in breathability, high in mechanical stability and capable of being bent by 90 degrees. The preparation method of the light-transmitting and breathable polymeric membrane is simple and easy to implement.

Description

Technical Field

[0001] The present invention relates to the field of oxygen polymerization inhibition type high-precision continuous light-curing 3D printing, and specifically to a light-transmitting and breathable polymer film and a preparation method and application thereof. Background Art

[0002] In order to improve the accuracy of continuous light-curing 3D printing, scientists have developed an oxygen polymerization inhibition method. The photocuring process is inhibited by using oxygen to quench the photoexcited photoinitiator or by combining with free radicals from the photoinitiator to produce peroxide. As a result, a "dead zone" is formed under the printing interface, and the photocuring process is completed only in the specified area, thereby accurately controlling the 3D printing process. This oxygen polymerization inhibition method has improved the accuracy and speed by thousands of times compared to the original digital light processing 3D printing technology. At present, the light-transmitting release film made of perfluoroethylene propylene copolymer film (FEP) is used in 3D printing technology. Its purpose is to be easy to peel off after printing, so the literature currently reports that the research on release film basically reduces the release force between the film and the printed part. However, this light-transmitting release film made of perfluoroethylene-propylene copolymer film (FEP) is not oxygen-permeable. Therefore, higher requirements are currently placed on the original release film: it must have controllable oxygen permeability and be able to continuously replenish oxygen to the dead zone during the printing cycle; it must have a certain mechanical stability. In order to ensure oxygen permeability during the printing process, the original quartz window needs to be removed and the release film needs to independently carry the liquid resin before curing; while being breathable, it must also be able to effectively intercept the uncured resin to prevent it from penetrating downward.

[0003] At present, the preparation of organic membranes with selective permeability generally adopts organic diluents / porogens. The main polymer material is blended with the organic solvent and scraped into a membrane at room temperature or high temperature. After the organic diluent / porogen is removed, the membrane becomes breathable. However, there is a problem that when the organic solvent is introduced into the preparation process, the polymer interacts with the organic solvent and forms a membrane through phase transformation. Even if a polymer material with good light transmittance is used, it undergoes crystallization behavior in the above-mentioned phase transformation process, thereby becoming pure white and completely opaque, which results in the obtained breathable membrane being only breathable but not light-transmitting.

[0004] In addition, the polymer materials used to prepare polymer films in the prior art are usually polypropylene and ethylene-propylene copolymers. The advantage of using polypropylene and ethylene-propylene copolymers to prepare polymer films is that some researchers can use fluorine atoms to make the film surface have low surface energy, making the peeling force small and thus easy to peel. However, due to the low transparency of polypropylene and ethylene-propylene copolymers, the transmittance of polymer films is difficult to be applied to 3D printing.

[0005] In order to solve the above problems, the present invention is proposed. Summary of the invention

[0006] The present invention aims to overcome the deficiencies of the prior art and provide a light-transmitting and breathable polymer film for use in continuous light-curing 3D printing.

[0007] The present invention adopts the following technical solutions:

[0008] The first aspect of the present invention provides a light-transmitting and breathable polymer film, wherein the light-transmitting and breathable polymer film comprises a metallocene polymer; the light transmittance of the light-transmitting and breathable polymer film is 80%-99%; the haze is 30%-51%; and the gas permeation per unit film thickness is 0.8×10 -4 -2×10 -2 L / (cm 2 ·min·μm); the thickness of the film is 50-500 microns; the porosity is 0-30%; the elongation at break is 33%-380%.

[0009] Preferably, the light transmittance of the light-transmitting and breathable polymer film is 85.4%-90.9%; the haze is 40.24%-50.62%; and the gas permeability per unit film thickness is 1.03×10 -4 -1.77×10 -2 L / (cm 2 ·min·μm); the thickness of the membrane is 113-120 microns; the porosity is 10-19%; and the elongation at break is 245%-292%.

[0010] Preferably, the metallocene high molecular polymer includes metallocene polypropylene and metallocene ethylene propylene copolymer.

[0011] The second aspect of the present invention provides a method for preparing the light-transmitting and breathable polymer film according to the first aspect of the present invention, wherein the light-transmitting and breathable polymer film is prepared by a hot pressing method, and the method comprises the following steps:

[0012] The metallocene polymer material is weighed, and then a porogen is added, and a 200g Haake rheometer is used to melt, heat and stir evenly. After crushing with a powder machine, a flat plate vulcanizer is used to hot press into a film, and the hot-pressed film material is cooled and peeled off from the film-making mold, and then a porogen treatment is performed to obtain a light-transmitting and breathable polymer film.

[0013] Preferably, the metallocene olefin polymer comprises metallocene polypropylene and metallocene ethylene propylene copolymer;

[0014] The porogen includes nano-scale carbonate or nano-scale soluble inorganic salt, the nano-scale carbonate includes nano-scale calcium carbonate and nano-scale magnesium carbonate, and the nano-scale soluble inorganic salt includes nano-scale sodium chloride, nano-scale magnesium chloride and nano-scale calcium chloride;

[0015] Preferably, the pore-inducing treatment includes dilute hydrochloric acid soaking, EDTA soaking, and water soaking.

[0016] Preferably, the soaking time is 0-3 hours. During the soaking process, excessive dilute hydrochloric acid soaking, excessive EDTA soaking or excessive water soaking is required.

[0017] Preferably, based on the total mass of the metallocene polymer and the porogen, the mass ratio of the added porogen is 0%-30%.

[0018] Preferably, the melting heating temperature is 100-200° C., and the heating stirring time is 2-4 hours.

[0019] Preferably, the hot pressing film forming temperature is 100-300°C, the hot pressing thickness is 50-500 microns, and the hot pressing pressure is 2-20 MPa;

[0020] The method for cooling the hot pressed film material is to take the hot pressed film material out of the flat vulcanizing machine mold and put it into a pneumatic cold press for cooling.

[0021] The third aspect of the present invention provides an application of the light-transmitting and breathable polymer film described in the first aspect of the present invention, wherein the light-transmitting and breathable polymer film is applied to oxygen polymerization-inhibited high-precision continuous light-curing 3D printing to achieve the effect of loading uncured resin and allowing oxygen to pass through.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] On the product:

[0024] 1. The present invention successfully obtains a polymer film that is both light-transmitting and breathable. The light transmittance of the light-transmitting and breathable polymer film is 80%-99%; the haze is 30%-51%, and the gas permeability per unit film thickness is 0.8×10 -4 -2×10 -2 L / (cm 2 ·min·μm); porosity is 0-30%; elongation at break is 33%-380%. In general, the light-transmitting and breathable polymer film of the present invention has high transparency, low haze, high air permeability, high mechanical stability, and can be bent at 90 degrees.

[0025] 2. The present invention selects highly light-transmitting polymer metallocene polypropylene and metallocene ethylene propylene copolymer to prepare light-transmitting and breathable polymer film. There is no report on the production of such film at present. Metallocene polypropylene and metallocene ethylene propylene copolymer are much cheaper than fluorinated ethylene propylene copolymer (FEP). In addition, metallocene polypropylene and metallocene ethylene propylene copolymer have good chemical stability and are not easy to react with resin.

[0026] Preparation method:

[0027] 3. The present invention adopts hot pressing method to prepare the film without introducing organic solvent, thus avoiding the interaction between the polymer material and the organic solvent and the crystal transformation behavior of the polymer material, so that the original light transmittance of the polymer material can still be maintained, thereby ensuring the light transmittance of the polymer film.

[0028] 4. The present invention uses nano inorganic particles as porogens to adjust the pore size, and finally removes the nano particles by acid washing or dissolving, which can further improve the air permeability. The preparation method of the light-transmitting and air-permeable polymer film of the present invention is simple and easy.

[0029] 5. The present invention finds that different cooling methods during the cooling process of the hot-pressed membrane material will affect the air permeability of the product membrane. It can be seen from Examples 6-8 of the present invention that the air permeability of the membrane obtained by cooling by a pneumatic cold press is better than that of the membrane prepared by other cooling methods (cooling in tap water and natural cooling).

[0030] Application:

[0031] 5. In the oxygen polymerization inhibition method, 3D printing does not occur directly at the interface, so there is a dead zone at the boundary, and the requirement for peeling force is reduced. Therefore, in the oxygen polymerization inhibition method, the use of metallocene polypropylene and metallocene ethylene propylene copolymer can also meet the peeling requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a diagram showing the flexibility of the polymer film obtained in Example 1.

[0033] Figure 2 This is a diagram showing the transparency of the polymer film obtained in Example 2.

[0034] Figure 3 This is a diagram showing the transparency of the polymer film obtained in Example 3.

[0035] Figure 4 This is a diagram showing the transparency of the polymer film obtained in Example 4.

[0036] Figure 5 This is a diagram showing the transparency of the polymer film obtained in Example 5. DETAILED DESCRIPTION

[0037] The present invention is further described below by way of examples, which are not limited to the examples. Experimental methods without specific conditions specified in the examples are generally carried out under conventional conditions and conditions described in the manual, or under conditions recommended by the manufacturer. The general equipment, materials, reagents, etc. used are all commercially available unless otherwise specified.

[0038] Example 1

[0039] Weigh 100g of metallocene ethylene propylene copolymer particles, put them into the corresponding film-making mold, put them into a flat-plate vulcanizer for preheating, and hot-press at a hot-pressing temperature of 200℃ and a hot-pressing pressure of 20MPa. Take the hot-pressed film sample out of the flat-plate vulcanizer mold and put it into a pneumatic cold press for cooling for 2 minutes, and then peel it off from the film-making mold. The film can be bent 90°, and its appearance is as follows Figure 1 Its performance parameters are shown in Table 1. Figure 1 It can be seen that the obtained polymer film has excellent flexibility.

[0040] Example 2

[0041] Weigh 100g of metallocene ethylene propylene copolymer particles, put them into the corresponding film-making mold, put them into a flat-plate vulcanizer for preheating, and hot-press at a hot-pressing temperature of 300°C and a hot-pressing pressure of 2MPa. Take the hot-pressed film sample out of the flat-plate vulcanizer mold, put it into a pneumatic cold press for cooling for 2 minutes, and peel it off from the film-making mold. Place it as follows Figure 2 The transparency is shown in the following table 1. Figure 2 It can be seen that the obtained polymer film has good transparency.

[0042] Example 3

[0043] Put 100g of metallocene ethylene propylene copolymer particles and 5g of analytical pure sodium chloride into a 200g Haake rheometer to mix the solid materials. The melting temperature is 170°C. When the torque display in the rheometer remains unchanged, the materials are evenly mixed. Take the evenly mixed materials out of the rheometer. After the material is cooled, put it into a crusher to crush the material into small particles. Put the crushed small particles into the corresponding film-making mold, put it into a flat-plate vulcanizer for preheating, and hot press it at a hot pressing temperature of 250°C and a hot pressing pressure of 12.5MPa. Take out the hot-pressed film sample from the flat-plate vulcanizer mold and put it into a pneumatic cold press to cool for 2 minutes. Peel it off the film-making mold and place it as follows Figure 3 On the markings shown. Figure 3 It can be seen that there are a large number of holes on the surface of the polymer membrane obtained in this example, and the addition of non-nanoscale porogen (analytical pure sodium chloride) cannot produce a finished membrane.

[0044] Example 4

[0045] Put 100g of metallocene ethylene propylene copolymer particles and 5g of nano-grade sodium chloride into a 200g Haake rheometer to mix the solid materials. The melting temperature is 150°C. When the torque display in the rheometer remains unchanged, the materials are evenly mixed. Take the evenly mixed materials out of the rheometer. After the material has cooled, put it into a crusher to crush the material into small particles. Put the crushed small particles into the corresponding film-making mold, put it into a flat-plate vulcanizer for preheating, and hot press it at a hot pressing temperature of 250°C and a hot pressing pressure of 12.5MPa. Take out the hot-pressed film sample from the flat-plate vulcanizer mold and put it into a pneumatic cold press to cool it for 2 minutes. Peel it off from the film-making mold. The film can be bent 90° and has excellent flexibility. Place it as follows Figure 4 The marker shown has good transparency from a macroscopic perspective. After being soaked in an excess of distilled water, its performance parameters are shown in Table 1 below.

[0046] Example 5

[0047] Put 100g of metallocene ethylene propylene copolymer particles and 2g of nano-calcium carbonate into a 200g Haake rheometer to mix the solid materials. The melting temperature is 170°C. When the torque display in the rheometer remains unchanged, the materials are evenly mixed. Take the evenly mixed materials out of the rheometer. After the material is cooled, put it into a crusher to crush the material into small particles. Put the crushed small particles into the corresponding film-making mold, put it into a flat-plate vulcanizer for preheating, and hot press it at a hot pressing temperature of 250°C and a hot pressing pressure of 12.5MPa. Take out the hot-pressed film sample from the flat-plate vulcanizer mold and put it into a pneumatic cold press to cool it for 2 minutes. Peel it off from the film-making mold. The film can be bent 90° and has excellent flexibility. Place it as follows Figure 5 The marker shown has good transparency from a macroscopic point of view. It is first soaked in excess dilute hydrochloric acid and then soaked in excess EDTA. Its performance parameters are shown in Table 1 below.

[0048] Example 6

[0049] 100g of metallocene ethylene propylene copolymer and 5g of nano-grade sodium chloride are put into a 200g Haake rheometer for solid material mixing. The melting temperature is 200℃. When the torque display in the rheometer remains unchanged, the material is evenly mixed. The evenly mixed material is taken out of the rheometer. After the material is cooled, it is placed in a crusher to crush the material into small particles. The crushed small particles are placed in the corresponding film-making mold, and preheated in a flat vulcanizer. Hot pressing is performed under the conditions of a hot pressing temperature of 250℃ and a hot pressing pressure of 12.5MPa. The hot-pressed film sample is taken out of the flat vulcanizer mold and cooled in tap water. It is peeled off from the film-making mold. The film can be bent at 90° and has excellent flexibility. Put it on the marker. From a macroscopic point of view, its transparency is good. Soak it in excess distilled water. Its performance parameters are shown in Table 1 below.

[0050] Example 7

[0051] 100g of metallocene ethylene propylene copolymer and 5g of nano-grade sodium chloride are put into a 200g Haake rheometer for solid material mixing. The melting temperature is 200°C. When the torque display in the rheometer remains unchanged, the material is evenly mixed. The evenly mixed material is taken out of the rheometer. After the material is cooled, it is placed in a crusher to crush the material into small particles. The crushed small particles are placed in the corresponding film-making mold, which is preheated in a flat vulcanizer and hot-pressed at a hot pressing temperature of 250°C and a hot pressing pressure of 12.5MPa. The hot-pressed film sample is taken out of the flat vulcanizer mold and allowed to cool naturally. After cooling, it is peeled off from the film-making mold. The film can be bent at 90° and has excellent flexibility. Put it on the marker, and its transparency is good from a macroscopic point of view. Soak it in excess distilled water, and its performance is shown in Table 1 below.

[0052] Example 8

[0053] Put 100g of metallocene ethylene propylene copolymer and 5g of nano-grade sodium chloride into a 200g Haake rheometer for solid material mixing. The melting temperature is 200℃. When the torque display in the rheometer remains unchanged, the material is evenly mixed. Take the evenly mixed material out of the rheometer. After the material is cooled, put it into a crusher to crush the material into small particles. Put the crushed small particles into the corresponding film-making mold, put it into a flat vulcanizer for preheating, and hot press at a hot pressing temperature of 250℃ and a hot pressing pressure of 12.5MPa. Take the hot-pressed film sample out of the flat vulcanizer mold and put it into a pneumatic cold press for refrigeration for 2min. Peel it off from the film-making mold. The film can be bent at 90° and has excellent flexibility. Put it on the marker. From a macroscopic point of view, its transparency is good. Soak it in excess distilled water. Its performance parameters are shown in Table 1 below.

[0054] Table 1 Performance parameters of finished films obtained in different embodiments

[0055]

[0056]

[0057] From the comparison of the above examples, it can be seen that the polymer film obtained by adding non-nanoscale porogen (analytical pure sodium chloride) in Example 3 has a large number of holes on the surface, and the finished film required by the present invention cannot be prepared. However, the obtained films in Examples 4-7 have excellent flexibility, good transparency, low haze, high air permeability, and high mechanical stability. In addition, it is found from the examples that the cooling method affects the final air permeability. The air permeability of the films obtained in Examples 6-8 that were cooled by a pneumatic cold press is better than that of the films prepared by other cooling methods (cooling in tap water and natural cooling).

[0058] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A light-transmitting and breathable polymer film, characterized in that: The light-transmitting and breathable polymer film comprises a metallocene polymer; the light transmittance of the light-transmitting and breathable polymer film is 80%-99%; the haze is 30%-51%; and the gas permeability per unit film thickness is 0.8×10 -4 -2×10 -2 L / (cm 2 ·min·μm); the thickness of the film is 50-500 microns; the porosity is 0-30%; the elongation at break is 33%-380%.

2. The light-transmitting and breathable polymer film according to claim 1, characterized in that: The metallocene high molecular polymer includes metallocene polypropylene and metallocene ethylene propylene copolymer.

3. The light-transmitting and breathable polymer film according to claim 1, characterized in that: The light transmittance of the light-transmitting and breathable polymer film is 85.4%-90.9%; the haze is 40.24%-50.62%; the gas permeability per unit film thickness is 1.03×10 -4 -1.77×10 -2 L / (cm 2 ·min·μm); the thickness of the membrane is 113-120 microns; the porosity is 10-19%; and the elongation at break is 245%-292%.

4. A method for preparing a light-transmitting and breathable polymer film according to any one of claims 1 to 3, characterized in that: The light-transmitting and breathable polymer film is prepared by a hot pressing method, which comprises the following steps: The metallocene polymer material is weighed, and then a porogen is added, and a Hake rheometer is used for melting, heating and stirring. After crushing with a powder machine, a flat plate vulcanizer is used for hot pressing to form a film. After the hot-pressed film material is cooled, it is peeled off from the film-making mold, and then a porogen treatment is performed to obtain a light-transmitting and breathable polymer film.

5. The preparation method according to claim 4, characterized in that: The metallocene olefin polymer includes metallocene polypropylene and metallocene ethylene propylene copolymer; The porogen includes nano-scale carbonate or nano-scale soluble inorganic salt. The nano-scale carbonate includes nano-scale calcium carbonate and nano-scale magnesium carbonate. The nano-scale soluble inorganic salt includes nano-scale sodium chloride, nano-scale magnesium chloride and nano-scale calcium chloride.

6. The preparation method according to claim 4, characterized in that: The pore-forming treatment includes dilute hydrochloric acid soaking, ethylenediaminetetraacetic acid (EDTA) soaking, and water soaking; The soaking time is 0-3 hours.

7. The preparation method according to claim 4, characterized in that: Based on the total mass of the metallocene polymer and the porogen, the mass ratio of the added porogen is 0%-30%.

8. The preparation method according to claim 4, characterized in that: The melting temperature is 100-200°C, and the heating and stirring time is 2-4 hours.

9. The preparation method according to claim 4, characterized in that: The hot pressing film forming temperature is 100-300℃, the hot pressing thickness is 50-500 microns, and the hot pressing pressure is 2-20MPa; The method for cooling the hot pressed film material is to take the hot pressed film material out of the flat vulcanizing machine mold and put it into a pneumatic cold press for cooling.

10. An application of the light-transmitting and breathable polymer film according to any one of claims 1 to 3, characterized in that: The light-transmitting and breathable polymer film is applied to oxygen polymerization-inhibited high-precision continuous light-curing 3D printing to achieve the effects of loading uncured resin and allowing oxygen to pass through.

Images