Low-crystal-point composite protective film and preparation method thereof

Abstract

The invention discloses a low-crystal-point composite protective film and a preparation method, and relates to the technical field of composite protective films, and the preparation method comprises the following steps: S1, raw material pretreatment: preliminarily dispersing an adhesive raw material containing an inorganic filler and a functional additive by a 10000 rpm high-shear emulsifying machine; s2, preparation of a release layer: feeding the PET film into a coating machine; s3, coating a first bonding layer: coating the pretreated acrylate adhesive on the release layer by using intaglio printing; s4, compounding the base material layer: compounding the polyester film with the release layer coated with the first bonding layer; s5, coating a second bonding layer: coating an acrylate adhesive on the surface of the base material layer according to the process of the first bonding layer; s6, compounding a protective layer: winding the transparent PE film and the base material layer coated with the second bonding layer at the tension of 10-20 N to form the compounded protective film; through the innovative design of the raw material pretreatment link, the adhesive raw material is treated from multiple dimensions, and the filler / additive agglomeration defect is effectively eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of composite protective films, in particular to a low-crystal point composite protective film and a preparation method thereof. Background Art

[0002] In high-end fields such as electronics and optics, composite protective films are widely used on the surfaces of various products to provide protection against scratches, dust, and fingerprints. However, the crystal point problem has always been a key factor restricting the improvement of the quality of composite protective films.

[0003] In existing technologies, inorganic fillers and functional additives are unevenly dispersed to form agglomerates. Air bubbles and impurities introduced during the production process also lead to the generation of a large number of crystal points. These crystal points not only affect the appearance quality of the protective film, but also reduce its optical and mechanical properties, making it unable to meet the stringent requirements of the high-end market for protective films.

[0004] Current improvement measures are difficult to solve the crystal point problem from the root, so there is an urgent need to develop new preparation methods to prepare low crystal point composite protective films. Summary of the Invention

[0005] In order to solve the above technical problems, a low-crystal point composite protective film and a preparation method are provided to solve the problems existing in the background technology of the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a low-crystal point composite protective film, comprising the following steps:

[0007] S1. Raw material pretreatment: The adhesive raw materials containing inorganic fillers and functional additives are initially dispersed in a 10,000 rpm high-shear emulsifier, and then refined using a 20 kHz ultrasonic dispersing device to a filler particle size of ≤50 nm and an agglomerate ratio of <2%. Real-time monitoring is performed using a laser particle size analyzer and a viscosity sensor. When the particle size distribution D50 fluctuates by more than 5% or the particle size suddenly changes by more than 10%, the adhesive is automatically refluxed and remixed. In a vacuum degassing device with a vacuum degree of ≤-0.09 MPa, degassing is performed using a scraper on the mixing barrel wall with a clearance of ≤0.1 mm to a bubble content of ≤0.1%. The adhesive is then filtered through a filter with a mesh size of 300 or higher and a precision of 50 μm. Production is carried out in a Class 10,000 clean room.

[0008] S2, preparation of release layer: feed the PET film into the coating machine at 3-5g / m 2 Apply silicone oil and dry at 80-100℃ for 10-15 minutes;

[0009] S3. First adhesive layer coating: Apply the pretreated acrylic adhesive to the release layer using gravure printing to a thickness of 5-8 μm and dry at 60-80°C for 5-10 minutes;

[0010] S4, laminating the substrate layer: laminating the polyester film and the release layer coated with the first adhesive layer at 50-70°C and 0.2-0.4 MPa;

[0011] S5. Second adhesive layer coating: Same as the first adhesive layer process, apply acrylic adhesive on the surface of the substrate layer with a thickness of 5-8 μm and dry at 60-80°C for 5-10 minutes;

[0012] S6, protective layer lamination: laminating the transparent PE film with the substrate layer coated with the second adhesive layer at 50-70°C and 0.2-0.4 MPa;

[0013] S7, Rewinding: Rewind the laminated protective film with a tension of 10-20N.

[0014] A low-crystal point composite protective film, characterized by comprising a release layer, a first adhesive layer, a substrate layer, a second adhesive layer and a protective layer stacked in sequence;

[0015] The release layer is made by coating silicone oil on a PET film, the first bonding layer and the second bonding layer are both acrylic adhesive layers, the base material layer is a polyester film, and the protective layer is a transparent PE film.

[0016] Compared with existing technologies, the present invention offers advantages: through innovative design of the raw material pretreatment process, it treats the adhesive raw materials from multiple dimensions, effectively eliminating filler / additive agglomeration defects and significantly reducing the number and size of crystals caused by bubbles and impurities. Testing has also shown that the number and size of crystals in the low-crystal-point composite protective film produced by the present invention are significantly reduced, greatly improving the protective film's appearance quality and meeting the stringent appearance requirements of the high-end market. DETAILED DESCRIPTION

[0017] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0018] Example 1

[0019] Raw material pretreatment: 100 kg of acrylate adhesive containing silica filler and photoinitiator was placed in an XJ-100 high-shear emulsifier at 10,000 rpm for initial dispersion for 15 minutes. The material was then transferred to a CS-20 ultrasonic dispersing unit at 20 kHz for 20 minutes. Testing revealed a filler particle size of 45 nm and an aggregate ratio of 1.8%.

[0020] During the dispersion process, a laser particle size analyzer (LS-POP6) and a viscosity sensor (DV-2T) were used for real-time monitoring. When the system detected a 4.8% fluctuation in the particle size distribution (D50), the reflux remixing mechanism was not triggered, ensuring uniform dispersion of the material.

[0021] The dispersed adhesive raw materials were transferred to a TP-50 vacuum degassing device, the vacuum degree was reduced to -0.092 MPa, and the scraper on the wall of the mixing barrel was used to stir and degas for 30 minutes to reduce the bubble content to 0.08%.

[0022] The deaerated raw materials are filtered through a 325-mesh (45 μm precision) filter. The entire production process is carried out in a Class 10,000 clean room (compliant with ISO14644-1 standards). Detection shows that the probability of impurities being mixed is 0.008%.

[0023] Preparation of release layer: PET film with a thickness of 50μm was selected and fed into the TB-2000 coating machine at a rate of 4g / m 2 The silicone oil is evenly applied on the film, and then the film is sent into a drying oven and dried at 90°C for 12 minutes to obtain a release layer.

[0024] Coating of the first bonding layer: Use a WB-1500 gravure printing machine to evenly coat the pretreated acrylic adhesive on the surface of the release layer, control the coating thickness to 6 μm, and dry it in a drying equipment at 70°C for 8 minutes to form the first bonding layer.

[0025] Substrate layer lamination: A polyester film with a thickness of 25 μm was selected and laminated with the release layer coated with the first adhesive layer using a laminating machine model FH-3000. The laminating temperature was set at 60° C. and the laminating pressure was set at 0.3 MPa to achieve firm bonding.

[0026] Coating of the second adhesive layer: Use the WB-1500 gravure printing machine again to evenly coat the surface of the substrate layer with an acrylic adhesive to a thickness of 6 μm, and dry at 70° C. for 8 minutes to form a second adhesive layer.

[0027] Protective layer lamination: A transparent PE film with a thickness of 12 μm and a base material layer coated with a second adhesive layer are laminated using an FH-3000 laminating machine at a laminating temperature of 60°C and a laminating pressure of 0.3 MPa to complete the construction of the main structure of the protective film.

[0028] Winding: Using an SJ-500 winder, the laminated protective film was wound at a tension of 15 N to produce the finished product. Testing showed that the film had 92% fewer crystal points than conventional processes, a tensile strength of 36 MPa, a light transmittance of 96%, and a haze of 0.4%.

[0029] Example 2

[0030] Raw material pretreatment: Weigh 150 kg of acrylic adhesive raw material containing aluminum oxide filler and curing agent, disperse it in a high-shear emulsifier (model XJ-150) at 10,000 rpm for 20 minutes, and then treat it in an ultrasonic disperser (model CS-20) for 25 minutes. The final filler particle size reaches 48 nm and the agglomerate ratio is 1.6%.

[0031] During the real-time monitoring process using a laser particle size analyzer (LS-POP6) and a viscosity sensor (DV-2T), when a 12% sudden change in particle size occurs, the system automatically triggers reflux remixing, and after 10 minutes of re-dispersion, the material becomes uniform again.

[0032] The material was placed in a vacuum degassing device (TP-80), the vacuum degree was reduced to -0.095 MPa, and degassing was carried out for 40 minutes until the bubble content was reduced to 0.07%.

[0033] Filtered through a 350-mesh (40 μm precision) filter and produced in a Class 10,000 clean room, the probability of impurities being mixed in is 0.006%.

[0034] Preparation of release layer: 45μm thick PET film was used on TB-2000 coating machine at 3.5g / m 2 The silicone oil coating amount was applied and dried at 85° C. for 13 minutes to prepare a release layer.

[0035] Coating of the first bonding layer: Use a WB-1500 gravure printing machine to coat the adhesive on the release layer with a thickness of 7 μm and dry at 65° C. for 9 minutes.

[0036] Substrate layer lamination: 28 μm polyester film and the first adhesive layer were laminated on a FH-3000 laminating machine at 55° C. and 0.25 MPa.

[0037] Second adhesive layer coating: Same process as the first adhesive layer, thickness 7μm, drying at 65℃ for 9 minutes.

[0038] Protective layer lamination: 13 μm thick PE film and the second adhesive layer were laminated in a FH-3000 laminating machine at 55°C and 0.25 MPa.

[0039] Winding: The SJ-500 winder was used at a tension of 18 N. Inspection of the finished product showed a 93% reduction in the number of crystal points, a tensile strength of 37 MPa, a light transmittance of 96.5%, and a haze of 0.35%.

[0040] Comparative Example 1

[0041] The composite protective film is produced using traditional preparation technology. The specific steps are as follows:

[0042] Raw material processing: The acrylate adhesive raw material containing silica filler and photoinitiator was put into ordinary stirring equipment and stirred at a speed of 2000 rpm for 30 minutes for dispersion without ultrasonic refinement treatment.

[0043] Degassing treatment: Place the adhesive raw materials in a common degassing device, maintain the vacuum degree at -0.08MPa, and degas for 20 minutes without using a scraper on the wall of the stirring barrel to assist in degassing.

[0044] Impurity filtration: Filter through a 200-mesh (75μm precision) filter. The production process is carried out in an ordinary workshop environment.

[0045] Subsequent steps: coating of release layer, adhesive layer and lamination of each layer were the same as those in Example 1. The protective film finally obtained was tested and found to have a large number of crystal points, a tensile strength of 28 MPa, a light transmittance of 90% and a haze of 1.2%.

[0046] Performance test comparison

[0047] project Number of crystal points ((pieces / ㎡) Tensile strength (Mpa) Light transmittance (%) Haze (%) Example 1 8 36 96 0.4 Example 2 7 37 96.5 0.35 Comparative Example 1 100 28 90 1.2

[0048] It can be clearly seen from the above comparison table that the composite protective film prepared by the improved preparation method of the present invention is significantly superior to the protective film prepared by the traditional process in key performance indicators such as the number of crystal points, tensile strength, light transmittance and haze, fully demonstrating the technical advantages and innovative value of the present invention.

[0049] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a low crystal point composite protective film, characterized in that: The following steps are involved: S1. Raw material pretreatment: The adhesive raw materials containing inorganic fillers and functional additives are initially dispersed in a 10,000 rpm high-shear emulsifier, and then refined using a 20 kHz ultrasonic dispersing device to a filler particle size of ≤50 nm and an agglomerate ratio of <2%. Real-time monitoring is performed using a laser particle size analyzer and a viscosity sensor. When the particle size distribution D50 fluctuates by more than 5% or the particle size suddenly changes by more than 10%, the adhesive is automatically refluxed and remixed. In a vacuum degassing device with a vacuum degree of ≤-0.09 MPa, degassing is performed using a scraper on the mixing barrel wall with a clearance of ≤0.1 mm to a bubble content of ≤0.1%. The adhesive is then filtered through a filter with a mesh size of 300 or higher and a precision of 50 μm. Production is carried out in a Class 10,000 clean room. S2, preparation of release layer: feed the PET film into the coating machine at 3-5g / m 2 Apply silicone oil and dry at 80-100℃ for 10-15 minutes; S3. First adhesive layer coating: Apply the pretreated acrylic adhesive to the release layer using gravure printing to a thickness of 5-8 μm and dry at 60-80°C for 5-10 minutes; S4, laminating the substrate layer: laminating the polyester film and the release layer coated with the first adhesive layer at 50-70°C and 0.2-0.4 MPa; S5. Second adhesive layer coating: Same as the first adhesive layer process, apply acrylic adhesive on the surface of the substrate layer with a thickness of 5-8 μm and dry at 60-80°C for 5-10 minutes; S6, protective layer lamination: laminating the transparent PE film with the substrate layer coated with the second adhesive layer at 50-70°C and 0.2-0.4 MPa; S7, Rewinding: Rewind the laminated protective film with a tension of 10-20N.

2. The method for preparing a low crystal point composite protective film according to claim 1, characterized in that: The rotation speed of the high shear emulsifier is 10000 rpm, and the operating frequency of the ultrasonic dispersing device is 20 kHz.

3. The method for preparing a low crystal point composite protective film according to claim 1, characterized in that: The vacuum degree of the vacuum degassing device is ≤-0.09MPa, and the gap between the scrapers on the wall of the mixing barrel is ≤0.1mm.

4. The method for preparing a low crystal point composite protective film according to claim 1, characterized in that: The filter has a mesh size of 300 or more and a precision of 50 μm.

5. The method for preparing a low crystal point composite protective film according to claim 1, characterized in that: The dynamic online monitoring system includes a laser particle size analyzer and a viscosity sensor. When the D50 fluctuation of the particle size distribution exceeds 5%, or the particle size mutation is greater than 10%, reflux remixing is triggered.

6. A low crystal point composite protective film, characterized in that: It includes a release layer, a first adhesive layer, a base material layer, a second adhesive layer and a protective layer stacked in sequence; The release layer is made by coating silicone oil on a PET film, the first bonding layer and the second bonding layer are both acrylic adhesive layers, the base material layer is a polyester film, and the protective layer is a transparent PE film.

7. The low crystal point composite protective film according to claim 6, wherein the coating amount of the silicone oil on the PET film is 3-5 g / m 2 .

8. The low crystal point composite protective film according to claim 6, characterized in that: The thickness of the first adhesive layer and the second adhesive layer are both 5-8 μm.

9. The low crystal point composite protective film according to claim 6, characterized in that: The thickness of the substrate layer is 20-30 μm, and the thickness of the protective layer is 10-15 μm.