Preparation method of bending-resistant protective film for projection and protective film

Abstract

The invention discloses a preparation method of a bending-resistant protective film for projection, the protective film is based on a first outer layer, a core layer and a second outer layer which are stacked in sequence, and the preparation method comprises the following steps: S1, respectively drying raw materials of the first outer layer, the core layer and the second outer layer, and mixing according to a proportion; s2, the raw materials of all the layers are subjected to melt co-extrusion and piece casting; s3, cooling and tempering the obtained casting piece in sequence; cooling comprises a first cooling section, a second cooling section and a third cooling section, and the temperatures of the first cooling section, the second cooling section and the third cooling section are sequentially increased; tempering comprises a first tempering section, a second tempering section and a third tempering section, and the temperature of the second tempering section is higher than that of the first tempering section and that of the third tempering section; the third cooling section is adjacent to the first tempering section, and the temperature of the first tempering section is lower than that of the third cooling section. According to the preparation method, the toughness and smoothness of the protective film are optimized by combining cooling and tempering processes and regulating and controlling segmented temperatures, and the protective film does not warp in use and is suitable for curved-surface objects.

Description

Technical Field

[0001] The present invention relates to the technical field of protective films, and particularly to a preparation method and a protective film for a bend-resistant protective film for projection. Background Art

[0002] Projection films are widely used in commercial displays, retail windows, home theaters and other scenarios. Commonly used materials at present are polyethylene terephthalate (PET), polyvinyl chloride (PVC), acrylic (PMMA), modified copolyester (PETG), etc. PET has poor toughness, and PMMA is brittle, and both are not suitable for preparing bend-resistant protective films; PVC has poor environmental protection and is easy to age; PETG has excellent optical properties, environmental protection and bendability, but the cost is high.

[0003] Therefore, it is necessary to improve the protective film for projection in the prior art. Summary of the Invention

[0004] One of the purposes of the present invention is to overcome the defects existing in the prior art, and provide a preparation method for a bend-resistant protective film for projection. The cooling and tempering processes are combined and set, and through the regulation of segmented temperatures, the toughness and flatness of the protective film are optimized, ensuring that the protective film does not warp during use and is suitable for the protection of curved objects.

[0005] In order to achieve the above process effects, the technical solution of the present invention is: a preparation method for a bend-resistant protective film for projection, the protective film is based on a first outer layer, a core layer and a second outer layer stacked in sequence, and includes the following steps:

[0006] S1: Dry the raw materials of the first outer layer, the core layer and the second outer layer respectively, and mix them in proportion;

[0007] S2: Melt and co-extrude and cast the raw materials of each layer respectively;

[0008] S3: The obtained cast sheet is cooled and tempered in sequence;

[0009] The cooling includes a first cooling section, a second cooling section and a third cooling section, and the temperatures of the first cooling section, the second cooling section and the third cooling section increase in sequence;

[0010] The tempering includes a first tempering section, a second tempering section and a third tempering section, and the temperature of the second tempering section is greater than the temperatures of the first tempering section and the third tempering section;

[0011] The third cooling section is adjacent to the first tempering section, and the temperature of the first tempering section is less than the temperature of the third cooling section.

[0012] The preferred technical solution is that the materials of the first outer layer and the second outer layer are both PETG, and the material of the core layer includes PET and a chain extender toughening agent.

[0013] Preferably, the temperatures of the first cooling section, the second cooling section and the third cooling section are 25-30 °C, 28-34 °C and 35-40 °C respectively. If the temperature of the first cooling section is 28 °C, the temperature of the second cooling section is 29 °C, 30 °C, 31 °C, 32 °C, 33 °C or 34 °C; if the temperature of the first cooling section is 26 °C, the temperature of the second cooling section is 28 °C, 29 °C, 30 °C, 31 °C, 32 °C, 33 °C or 34 °C; if the temperature of the first cooling section is 30 °C, the temperature of the second cooling section is 31 °C, 32 °C, 33 °C or 34 °C.

[0014] Preferably, the temperatures of the first tempering section, the second tempering section and the third tempering section are 23-29 °C, 32-39 °C and 23-29 °C respectively.

[0015] Preferably, the melting and extrusion temperatures of the raw materials of the first outer layer are set to be 220±7 °C, 238±3 °C, 238±3 °C, 238±5 °C, 238±5 °C, 240±5 °C, 238±5 °C in sequence;

[0016] the melting and extrusion temperatures of the raw materials of the second outer layer are set to be 220±7 °C, 238±3 °C, 240±3 °C, 240±5 °C, 240±5 °C, 240±5 °C, 240±5 °C in sequence;

[0017] the melting and extrusion temperatures of the raw materials of the core layer are set to be 250±7 °C, 260±3 °C, 260±3 °C, 262±5 °C, 262±5 °C, 262±5 °C, 260±5 °C, 260±5 °C in sequence;

[0018] The die temperature for melt co-extrusion of each layer is 260±5 °C.

[0019] Preferably, the intrinsic viscosity of the PET is 0.62-0.70 dL / g, and the chain extender and toughener is polyolefin elastomer grafted with glycidyl methacrylate. If the intrinsic viscosity of the PET is too low, both the toughness and mechanical properties are poor, resulting in poor bending performance of the protective film and being unsuitable for conforming protection of curved objects. If the intrinsic viscosity of the PET is too high, the processing viscosity increases, which is not conducive to uniform mixing with the chain extender and toughener, and the reaction difficulty of their reactive groups increases, resulting in poor modification effect.

[0020] Preferably, the grafting rate of the glycidyl methacrylate is 1.5%-2%. If the grafting rate of the glycidyl methacrylate is too low, the compatibility between the chain extender and toughener and the PET is poor, and the toughness modification is not obvious; when the grafting rate of the glycidyl methacrylate is too high, the crosslinking density of the PET and the chain extender and toughener increases in the molten state, resulting in an increase in viscosity, requiring higher energy, and excessive grafting easily leads to a decrease in the rigidity of the protective film and poor tensile strength.

[0021] The preferred technical solution is that the mass ratio of the PET to the chain extender and toughener is (85-90):(10-15).

[0022] The preferred technical solution is that the ratio of the thickness of the first outer layer, the core layer and the second outer layer is (10-18): (64-80): (10-18), and the total film thickness of the protective film is 150-500 μm. Furthermore, the total film thickness of the protective film is one of 150 μm, 180 μm, 200 μm, 250 μm, 280 μm, 300 μm, 320 μm, 350 μm and 400 μm. The total film thickness of the protective film is mainly selected according to customer needs, taking into account performance and cost.

[0023] The second object of the present invention is to overcome the defects existing in the prior art and provide a bending-resistant protective film for projection, wherein the protective film is prepared by the preparation method of the bending-resistant protective film for projection.

[0024] The advantages and beneficial effects of the present invention are:

[0025] The method for preparing the bending-resistant protective film for projection combines cooling and tempering processes, and optimizes the toughness and flatness of the protective film by regulating the temperature in sections, thereby ensuring that the protective film does not warp during use and is suitable for protecting curved objects. DETAILED DESCRIPTION

[0026] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0027] model

[0028] PETG was purchased from Sinopec Yizheng Chemical Fiber Co., Ltd., model FG703;

[0029] Polyolefin elastomer (POE) was purchased from DuPont, USA, model 8200.

[0030] Chain Extender Toughener

[0031] Octene in polyolefin elastomer (POE) has a freely rotating flexible molecular chain and a curled structure, which gives it good impact resistance and provides network crosslinking points for crosslinking with other molecules; there are only single bonds in the internal structure, which has good antioxidant and anti-aging properties; it has good fluidity and can be better dispersed in the matrix when blended with PET, exerting a toughening effect.

[0032] Preparation method: Take 2 kg of POE, 10 g of dicumyl peroxide initiator, and 30 - 40 g of glycidyl methacrylate monomer, mix them, and conduct melt grafting through a twin-screw extruder. The extruded spline is cooled and then pelletized for standby. Among them, the melting temperature of the twin-screw extruder is set at 170 - 183 °C, and the screw speed is 58 - 62 r / min.

[0033] Example 1

[0034] The bend-resistant protective film for projection is based on a first outer layer, a core layer, and a second outer layer laminated in sequence. The materials of the first outer layer and the second outer layer are both PETG, and the material of the core layer includes PET and a chain extender toughening agent with a mass ratio of 88:12. Among them, the chain extender toughening agent is a polyolefin elastomer grafted with glycidyl methacrylate, and the grafting rate of glycidyl methacrylate is 1.8%; the model of PET is FG600, and the intrinsic viscosity is 0.675 dL / g.

[0035] The preparation method of the bend-resistant protective film for projection includes the following steps:

[0036] S1: Dry the raw materials of the first outer layer, the core layer, and the second outer layer respectively, and mix them in proportion;

[0037] S2: Melt and co-extrude and cast films for each layer of raw materials. The melting and extrusion temperatures of the raw materials of the first outer layer are set at 220 °C, 238 °C, 238 °C, 238 °C, 238 °C, 240 °C, 238 °C in sequence; the melting and extrusion temperatures of the raw materials of the second outer layer are set at 220 °C, 238 °C, 240 °C, 240 °C, 240 °C, 240 °C, 240 °C in sequence; the melting and extrusion temperatures of the raw materials of the core layer are set at 250 °C, 260 °C, 260 °C, 262 °C, 262 °C, 262 °C, 260 °C, 260 °C in sequence; the die temperature for each layer of melt co-extrusion is 260 °C;

[0038] S3: The obtained cast film is cooled and tempered in sequence. The cooling includes a first cooling section, a second cooling section, and a third cooling section, and the tempering includes a first tempering section, a second tempering section, and a third tempering section. The third cooling section is adjacent to the first tempering section; among them, the temperatures of the first cooling section, the second cooling section, and the third cooling section are 28 °C, 30 °C, and 37 °C respectively, and the temperatures of the first tempering section, the second tempering section, and the third tempering section are 26 °C, 35 °C, and 26 °C respectively.

[0039] The layer thickness of the first outer layer is 48 μm, the layer thickness of the core layer is 224 μm, and the layer thickness of the second outer layer is 48 μm.

[0040] Example 2

[0041] Example 2 is based on Example 1, the difference is that PET is the Kanghui model KH2650A, and the intrinsic viscosity is 0.63 dL / g.

[0042] Example 3

[0043] Example 3 is based on Example 1, with the difference that the model of PET is FG720A; the intrinsic viscosity is 0.74 dL / g.

[0044] Example 4

[0045] Example 4 is based on Example 1, with the difference that the material of the core layer includes PET and a chain extender toughening agent with a mass ratio of 80:20.

[0046] Example 5

[0047] Example 5 is based on Example 1, with the difference that the material of the core layer includes PET and a chain extender toughening agent with a mass ratio of 85:15.

[0048] Example 6

[0049] Example 6 is based on Example 1, with the difference that the total film thickness of the protective film remains unchanged, the layer thickness of the first outer layer is 32 μm, the layer thickness of the core layer is 256 μm, and the layer thickness of the second outer layer is 32 μm.

[0050] Example 7

[0051] Example 7 is based on Example 1, with the difference that the total film thickness of the protective film remains unchanged, the layer thickness of the first outer layer is 16 μm, the layer thickness of the core layer is 288 μm, and the layer thickness of the second outer layer is 16 μm.

[0052] Example 8

[0053] Example 8 is based on Example 1, with the difference that the materials of the first outer layer and the second outer layer are both PETG; the core layer only includes PET and no chain extender toughening agent is added.

[0054] Comparative Example 1

[0055] Comparative Example 1 is based on Example 1, with the difference that in S3, the cast sheet is only cooled in three stages.

[0056] Comparative Example 2

[0057] Comparative Example 2 is based on Example 1, with the difference that the temperatures of the first cooling stage, the second cooling stage, and the third cooling stage are 28 °C, 37 °C, and 37 °C respectively, and the temperatures of the first tempering stage, the second tempering stage, and the third tempering stage are 26 °C, 26 °C, and 26 °C respectively.

[0058] Comparative Example 3

[0059] Comparative Example 3 is based on Example 1, with the difference that the temperatures of the first cooling section, the second cooling section, and the third cooling section are 28°C, 30°C, and 37°C respectively, and the temperatures of the first tempering section, the second tempering section, and the third tempering section are 26°C, 26°C, and 26°C respectively.

[0060] Performance Test

[0061] 1. Notched impact strength: According to standard GB / T 1843, the temperature is 23°C;

[0062] 2. Flexural resistance: Using the paint film bending tester QTY-32, the sample size is a 50mm*100mm cut piece. Bend the cut piece with the hardened layer surface facing the shaft rod by 180°, reset, repeat bending 100,000 times and 200,000 times, and then remove the cut piece to observe whether the hardened layer cracks;

[0063] 3. Tensile strength: According to standard GB / T 1040;

[0064] 4. Flatness: Wind the protective film into a roll for one week, then take 5 samples with the sample size of 1000mm×1000mm. Lay the samples flat on a flat black marble slab, and use a feeler gauge to measure the gap between the corners and sides of the sample and the marble slab, and record H0;

[0065] △: H0 = 0; ▲: H0 ≤ 0.1mm; ■: H0 > 0.1mm;

[0066] Among them, △ and ▲ are qualified, and ■ is unqualified.

[0067] The performance test results of the examples and comparative examples are as follows:

[0068]

[0069]

[0070] Compared with Example 1, the intrinsic viscosity of PET in Example 2 decreases, which has a negative impact on the mechanical properties;

[0071] Compared with Example 1, the intrinsic viscosity of PET in Example 3 is too high, the processing viscosity increases, and under the condition of unchanged process conditions, the raw materials are not evenly dispersed, which easily leads to a decrease in the reaction probability between the terminal hydroxyl groups and terminal carboxyl groups in high molecular weight PET and the epoxy groups in the chain extender, and the toughness modification effect is not obvious.

[0072] Compared with Example 1, in Example 4, as the amount of the chain extender increases, the toughness of the protective film improves, but the tensile strength decreases.

[0073] Compared with Example 1, in Examples 6 and 7, the layer thicknesses of the first outer layer and the second outer layer are reduced, which has a negative impact on the toughness of the protective film.

[0074] In Example 8, compared with Example 1, the core layer was not modified with a chain extender toughening agent, resulting in a decrease in the toughness of the protective film and poor bending resistance.

[0075] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principles of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a bend-resistant protective film for projection, the protective film being based on a first outer layer, a core layer, and a second outer layer laminated in sequence, characterized in that, It includes the following steps: S1: Dry the raw materials of the first outer layer, the core layer and the second outer layer respectively and mix them in proportion; S2: Melt and co-extrude the raw materials of each layer and cast into sheets; S3: The obtained cast sheets are successively cooled and tempered; The cooling includes a first cooling section, a second cooling section and a third cooling section, and the temperatures of the first cooling section, the second cooling section and the third cooling section increase in sequence; The tempering includes a first tempering section, a second tempering section and a third tempering section, and the temperature of the second tempering section is greater than the temperatures of the first tempering section and the third tempering section; The third cooling section is adjacent to the first tempering section, and the temperature of the first tempering section is less than the temperature of the third cooling section.

2. The preparation method of the bend-resistant protective film for projection according to claim 1, characterized in that, The materials of the first outer layer and the second outer layer are both PETG, and the material of the core layer includes PET and a chain extender toughening agent.

3. The preparation method of the bend-resistant protective film for projection according to claim 1 or 2, characterized in that The temperatures of the first cooling section, the second cooling section and the third cooling section are 25 - 30°C, 28 - 34°C, 35 - 40°C respectively.

4. The preparation method of the bend-resistant protective film for projection according to claim 3, wherein, The temperatures of the first tempering section, the second tempering section and the third tempering section are 23 - 29°C, 32 - 39°C, 23 - 29°C respectively.

5. The preparation method of the bend-resistant protective film for projection according to claim 2, characterized in that, The melting and extrusion temperatures of the raw materials of the first outer layer are successively set as 220 ± 7°C, 238 ± 3°C, 238 ± 3°C, 238 ± 5°C, 238 ± 5°C, 240 ± 5°C, 238 ± 5°C; The melting and extrusion temperatures of the raw materials of the second outer layer are successively set as 220 ± 7°C, 238 ± 3°C, 240 ± 3°C, 240 ± 5°C, 240 ± 5°C, 240 ± 5°C, 240 ± 5°C; The melting and extrusion temperatures of the raw materials of the core layer are successively set as 250 ± 7°C, 260 ± 3°C, 260 ± 3°C, 262 ± 5°C, 262 ± 5°C, 262 ± 5°C, 260 ± 5°C, 260 ± 5°C; The die temperature for melting and co-extruding each layer is 260 ± 5°C.

6. The preparation method of the bend-resistant protective film for projection according to claim 2, characterized in that The intrinsic viscosity of the PET is 0.62 - 0.70 dL / g, and the chain extender toughening agent is polyolefin elastomer grafted with glycidyl methacrylate.

7. The preparation method of the bend-resistant protective film for projection according to claim 6, wherein, The grafting rate of the glycidyl methacrylate is 1.5% - 2%.

8. The preparation method of the bend-resistant protective film for projection according to claim 2 or 6, characterized in that, The mass ratio of the PET to the chain extender toughening agent is (85 - 90):(10 - 15).

9. The preparation method of the bend-resistant protective film for projection according to claim 2, wherein, The layer thickness ratio of the first outer layer, the core layer and the second outer layer is (10 - 18):(64 - 80):(10 - 18), and the total film thickness of the protective film is 150 - 500 μm.

10. A bend-resistant protective film for projection, characterized in that, The protective film is prepared by the preparation method of the bend-resistant protective film for projection according to any one of claims 1 - 9.

Images