Low-viscosity low-pollution protective film as well as preparation method and application thereof

Abstract

The invention provides a low-viscosity and low-pollution protective film as well as a preparation method and application thereof. The low-viscosity and low-pollution protective film comprises a base material layer, a polyurethane adhesive layer, an acrylate adhesive layer and a release material layer which are sequentially stacked, and the preparation raw materials of the acrylate adhesive layer comprise polyacrylate and polyester resin. The protective film provided by the invention comprises the polyurethane adhesive layer and the acrylate adhesive layer which are arranged according to a specific sequence, and meanwhile, polyester resin is introduced into the acrylate adhesive layer, so that the protective film has low viscosity and low pollution, and the viscous force of the protective film does not climb.

Description

Technical Field

[0001] The invention belongs to the technical field of protective films, and relates to a low-viscosity and low-pollution protective film and a preparation method and application thereof. Background Art

[0002] In scenarios where a high-cleanliness production environment is required for PET, PI, etc., the protective film is used for isolation and protection. Therefore, during the production process, the protective film needs to have good adsorption properties on the attached surface. In the later stage of production, the protective film needs to be easy to peel off and have low pollution to the attached object. The existing protective films are all single-layer structures. Although some protective films can maintain a low viscosity, small molecules are precipitated and have high pollution in the later stage. Although other protective films have low pollution to the attached object and good adsorption, the peeling force is easy to climb and it is not easy to peel off in the later stage of production. That is, traditional protective films generally coat the adhesive directly on the surface of the substrate and cure it with isocyanate and epoxy curing agents, which cannot meet the production process requirements of low viscosity, low pollution and no climbing.

[0003] Therefore, in the art, it is desired to develop a protective film that has both low viscosity and low contamination properties. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a low-viscosity and low-pollution protective film and its preparation method and application. The present invention provides a multi-purpose protective film with low viscosity, good adsorption, low pollution to the object being attached, and no increase in adhesion, which can meet the requirements of safety, stability and pollution prevention of substrate products such as PET and PI in the production process at this stage. At the same time, the protective film does not affect the performance of the object being attached, and the rear protective film is easy to remove.

[0005] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a low-viscosity and low-pollution protective film, the low-viscosity and low-pollution protective film comprising a substrate layer, a polyurethane adhesive layer, an acrylate adhesive layer, and a release material layer stacked in sequence;

[0007] The raw materials for preparing the acrylic ester adhesive layer include polyacrylate and polyester resin.

[0008] The protective film provided by the present invention comprises a polyurethane adhesive layer and an acrylate adhesive layer arranged in a specific order, and polyester resin is introduced into the acrylate adhesive layer, so that the protective film has low viscosity and low pollution, and its adhesive force does not increase.

[0009] The present invention first coats a polyurethane adhesive layer on the substrate, and then transfers the acrylic adhesive layer to the polyurethane adhesive layer. The polyurethane adhesive layer has excellent flexibility, outstanding wear resistance and flexibility, and good elasticity, and can ensure excellent bonding performance with the surface acrylic adhesive, and can tightly bond the surface adhesive. At the same time, polyester resin is added to the surface adhesive to further reduce the surface viscosity and stabilize it. The overall structure can achieve the effects of no climbing, easy adhesion, and low pollution.

[0010] In the present invention, the "low adhesion" in the low adhesion and low pollution protective film means that the peeling force between the protective film and the bonding surface is less than 10.0gf / inch, and the "low pollution" means that compared with the peeling force between the tesa 7475 tape and the bonding surface directly tested without the protective film, the percentage change in the peeling force between the tesa 7475 tape and the bonding surface after the protective film is attached to the bonding surface for 7 days and then removed, and the peeling force between the tesa 7475 tape and the bonding surface is not higher than 10%, and the percentage change in the peeling force between the tesa 7475 tape and the bonding surface after the protective film is attached to the bonding surface for 30 days and then removed, is not higher than 15%.

[0011] Preferably, the raw materials for preparing the acrylic adhesive layer further include any one of an antistatic agent, a tackifying resin, and a curing agent, or a combination of at least two of them.

[0012] Preferably, the raw materials for preparing the acrylic adhesive layer include the following components in parts by weight: 100 parts of polyacrylate, 0.5-2 parts of antistatic agent (for example, 0.5 parts, 0.8 parts, 1 parts, 1.3 parts, 1.5 parts, 1.8 parts, 2 parts, etc.), 1-4 parts of polyester resin (for example, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, etc.), 15-45 parts of tackifying resin (for example, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, etc.), 0.1 to 3 parts of curing agent (for example, 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, 1.3 parts, 1.5 parts, 1.8 parts, 2 parts, 2.3 parts, 2.5 parts, 2.8 parts, 3 parts, etc.), and 20 to 80 parts of solvent (for example, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, etc.).

[0013] Preferably, the raw materials for preparing the polyurethane adhesive layer include the following components in parts by weight: 100 parts of polyurethane resin, 15-45 parts of tackifying resin (for example, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, etc.), 0.1-3 parts of curing agent (for example, 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 parts, 1.3 parts, 1.5 parts, 1.8 parts, 2 parts, 2.3 parts, 2.5 parts, 2.8 parts, 3 parts, etc.), 0.1-1 parts of catalyst (for example, 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 parts, etc.), and 20-80 parts of solvent (for example, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, etc.).

[0014] Preferably, the polyacrylate is obtained by polymerizing any one of methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate or n-butyl acrylate, or copolymerizing at least two of them.

[0015] Preferably, the antistatic agent includes any one of tributylmethylammonium trifluoromethanesulfonyl imide salt, bis(trifluoromethanesulfonyl)imide lithium salt, and dimethyl carbonate, or a combination of at least two thereof.

[0016] Preferably, the polyester resin is a copolyester polymer compound formed by alternating copolymerization of diols and alternating diols.

[0017] Preferably, the polyurethane resin is obtained by polymerization of polyisocyanate and polyether polyol or polyester polyol.

[0018] Preferably, the catalyst includes any one of dibutyltin dilaurate, stannous oleate, triethylamine, triethanolamine, and N-methylmorpholine, or a combination of at least two thereof.

[0019] Preferably, the tackifying resin in the raw materials for preparing the acrylic adhesive layer and the polyurethane adhesive layer independently includes any one of liquid C5 petroleum resin Wingtack 10, liquid polyterpene resin Dercolyte LTG, hydrogenated rosin acid methyl ester, dicyclopentadiene resin, 2,2'-thiodiethyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and ethyl acetate, or a mixture of at least two thereof.

[0020] Preferably, the curing agents in the raw materials for preparing the acrylic adhesive layer and the polyurethane adhesive layer independently include any one of hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate or dicyclohexylmethane diisocyanate, or a combination of at least two thereof.

[0021] Preferably, the solvents in the raw materials for preparing the acrylic adhesive layer and the polyurethane adhesive layer independently include any one of ethyl acetate, toluene, ethanol, methyl ethyl ketone, acetone, and dichloromethane, or a combination of at least two of them.

[0022] Preferably, the substrate layer is made of polyethylene terephthalate (PET). According to the requirements of certain application scenarios, the substrate layer may be coated with an antistatic agent on a side away from the polyurethane adhesive layer.

[0023] The present invention does not specifically limit the tensile strength, elongation at break, and surface impedance of the substrate layer, which can be selected according to actual application requirements.

[0024] Preferably, the release material layer is made of polyethylene terephthalate.

[0025] Preferably, the thickness of the substrate layer is 30 to 90 μm, for example, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, etc.

[0026] Preferably, the thickness of the polyurethane adhesive layer is 5 to 10 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0027] Preferably, the thickness of the acrylic adhesive layer is 5 to 10 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0028] Preferably, the thickness of the release material layer is 20-40 μm, for example, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, etc.

[0029] Preferably, the total thickness of the low-viscosity and low-pollution protective film is 60 to 150 μm, for example, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, etc.

[0030] In a second aspect, the present invention provides a method for preparing the low-viscosity and low-pollution protective film as described in the first aspect, the preparation method comprising the following steps:

[0031] (1) mixing raw materials for preparing a polyurethane adhesive layer to obtain a polyurethane adhesive solution, coating the polyurethane adhesive solution on a surface of a substrate, and curing the mixture to form a polyurethane adhesive layer;

[0032] (2) mixing the raw materials for preparing the acrylate adhesive layer to obtain an acrylate type adhesive solution, coating the acrylate type adhesive solution on the surface of the polyurethane adhesive layer, and curing the mixture to form an acrylate adhesive layer;

[0033] (3) A release profile is pasted on the surface of the acrylic adhesive layer and cured to obtain the low-viscosity and low-pollution protective film.

[0034] Preferably, the curing temperature in step (1) is 110-130°C, for example, 110°C, 115°C, 120°C, 125°C, 130°C, etc., and the curing time is 5-15min, for example, 5min, 10min, 15min, etc.

[0035] Preferably, the curing temperature in step (2) is 110-130°C, for example, 110°C, 115°C, 120°C, 125°C, 130°C, etc., and the curing time is 5-15min, for example, 5min, 10min, 15min, etc.

[0036] Preferably, the aging temperature in step (3) is 40-50°C, for example, 40°C, 45°C, 50°C, etc., and the aging time is 30-50h, for example, 30h, 32h, 35h, 38h, 40h, 42h, 45h, 48h, 50h, etc.

[0037] In a third aspect, the present invention provides an application of the low-viscosity and low-pollution protective film as described in the first aspect in a display screen manufacturing process.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The protective film provided by the present invention comprises a polyurethane adhesive layer and an acrylate adhesive layer arranged in a specific order, and polyester resin is introduced into the acrylate adhesive layer, so that the protective film has low viscosity and low pollution, and its adhesive force does not increase. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of the structure of the low-viscosity and low-pollution protective film provided in Example 1;

[0041] Among them, 1-substrate layer, 2-polyurethane adhesive layer, 3-acrylate adhesive layer, 4-release material layer. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0043] Unless otherwise specified, some of the raw material information used in the examples and comparative examples of the present invention is shown in Table 1 below:

[0044] Table 1

[0045] Brand Polyacrylate Changxing Chemical 7725G Polyester resin DY-9002 Polyurethane resin Sanhe paint UA80-10

[0046] Example 1

[0047] In this embodiment, a low-viscosity and low-pollution protective film is provided, and its structural schematic diagram is as follows: Figure 1 As shown, the low-viscosity and low-pollution protective film comprises a substrate layer 1, a polyurethane adhesive layer 2, an acrylate adhesive layer 3, and a release material layer 4 which are stacked in sequence;

[0048] The substrate layer is a PET substrate layer with a thickness of 50 μm;

[0049] The release material layer is made of PET and has a thickness of 30 μm;

[0050] The thickness of the acrylic adhesive layer is 8 μm, and the raw materials for preparing the layer include the following components in parts by weight: 100 parts of polyacrylate, 1 part of antistatic agent, 2 parts of polyester resin, 20 parts of tackifying resin, 1 part of curing agent, and 60 parts of solvent;

[0051] The thickness of the polyurethane adhesive layer is 8 μm, and the raw materials for preparing the layer include the following components by weight: 100 parts of polyurethane resin, 25 parts of tackifying resin, 2.5 parts of curing agent, 0.2 parts of catalyst, and 60 parts of solvent;

[0052] Among them, the antistatic agent is tributyl methyl ammonium trifluoromethanesulfonyl imide salt; the catalyst is dibutyl tin dilaurate; the tackifying resin in the preparation raw materials of the acrylate adhesive layer and the polyurethane adhesive layer is French DRT Deercolyte LTG, the curing agent is trimethyl hexamethylene diisocyanate, and the solvent is ethyl acetate.

[0053] The preparation method comprises the following steps:

[0054] (1) mixing raw materials for preparing a polyurethane adhesive layer to obtain a polyurethane adhesive solution, coating the polyurethane adhesive solution on a surface of a substrate, and curing at 120° C. for 5 minutes to form a polyurethane adhesive layer;

[0055] (2) mixing the raw materials for preparing the acrylate adhesive layer to obtain an acrylate type adhesive solution, coating the acrylate type adhesive solution on the surface of the polyurethane adhesive layer, and curing at 110° C. for 5 minutes to form an acrylate adhesive layer;

[0056] (3) A release profile is pasted on the surface of the acrylic adhesive layer and cured at 40° C. for 40 h to obtain the low-viscosity and low-pollution protective film.

[0057] Example 2

[0058] In this embodiment, a low-viscosity and low-pollution protective film is provided, wherein the low-viscosity and low-pollution protective film comprises a substrate layer, a polyurethane adhesive layer, an acrylate adhesive layer, and a release material layer which are stacked in sequence;

[0059] The substrate layer is a PET substrate layer with a thickness of 50 μm;

[0060] The release material layer is made of PET and has a thickness of 30 μm;

[0061] The thickness of the acrylic adhesive layer is 5 μm, and the raw materials for preparing the layer include the following components in parts by weight: 100 parts of polyacrylate, 0.5 parts of antistatic agent, 1 part of polyester resin, 15 parts of tackifying resin, 0.5 parts of curing agent, and 40 parts of solvent;

[0062] The thickness of the polyurethane adhesive layer is 5 μm, and the raw materials for preparing the layer include the following components in parts by weight: 100 parts of polyurethane resin, 15 parts of tackifying resin, 1 part of curing agent, 0.1 part of catalyst, and 40 parts of solvent;

[0063] Among them, the antistatic agent is dimethyl carbonate; the catalyst is dibutyltin dilaurate; the tackifying resin in the preparation raw materials of the acrylate adhesive layer and the polyurethane adhesive layer is French DRT Dercolyte LTG, the curing agent is isophorone diisocyanate, and the solvent is ethyl acetate.

[0064] The preparation method is the same as that of Example 1.

[0065] Example 3

[0066] In this embodiment, a low-viscosity and low-pollution protective film is provided, wherein the low-viscosity and low-pollution protective film comprises a substrate layer, a polyurethane adhesive layer, an acrylate adhesive layer, and a release material layer which are stacked in sequence;

[0067] The substrate layer is a PET substrate layer with a thickness of 50 μm;

[0068] The release material layer is made of PET and has a thickness of 30 μm;

[0069] The thickness of the acrylic adhesive layer is 10 μm, and the raw materials for preparing the layer include the following components in parts by weight: 100 parts of polyacrylate, 2 parts of antistatic agent, 4 parts of polyester resin, 45 parts of tackifying resin, 2 parts of curing agent, and 80 parts of solvent;

[0070] The thickness of the polyurethane adhesive layer is 10 μm, and the raw materials for preparing the layer include the following components in parts by weight: 100 parts of polyurethane resin, 45 parts of tackifying resin, 3 parts of curing agent, 0.5 parts of catalyst, and 80 parts of solvent;

[0071] Among them, the antistatic agent is tributyl methyl ammonium trifluoromethanesulfonyl imide salt; the catalyst is dibutyl tin dilaurate; the tackifying resin in the preparation raw materials of the acrylate adhesive layer and the polyurethane adhesive layer is French DRT Deercolyte LTG, the curing agent is trimethyl hexamethylene diisocyanate, and the solvent is ethyl acetate.

[0072] The preparation method is the same as that of Example 1.

[0073] Example 4

[0074] In this embodiment, a low-viscosity and low-pollution protective film is provided, wherein the low-viscosity and low-pollution protective film comprises a substrate layer, a polyurethane adhesive layer, an acrylate adhesive layer, and a release material layer which are stacked in sequence;

[0075] The substrate layer is a PET substrate layer with a thickness of 50 μm;

[0076] The release material layer is made of PET and has a thickness of 30 μm;

[0077] The thickness of the acrylic adhesive layer is 5 μm, and the raw materials for preparing the layer include the following components in parts by weight: 100 parts of polyacrylate, 1 part of antistatic agent, 2 parts of polyester resin, 20 parts of tackifying resin, 1 part of curing agent, and 60 parts of solvent;

[0078] The thickness of the polyurethane adhesive layer is 10 μm, and the raw materials for preparing the layer include the following components in parts by weight: 100 parts of polyurethane resin, 25 parts of tackifying resin, 2.5 parts of curing agent, 0.2 parts of catalyst, and 60 parts of solvent;

[0079] Among them, the antistatic agent is tributyl methyl ammonium trifluoromethanesulfonyl imide salt; the catalyst is dibutyl tin dilaurate; the tackifying resin in the preparation raw materials of the acrylate adhesive layer and the polyurethane adhesive layer is French DRT Deercolyte LTG, the curing agent is trimethyl hexamethylene diisocyanate, and the solvent is ethyl acetate.

[0080] The preparation method is the same as that of Example 1.

[0081] Example 5

[0082] In this embodiment, a low-viscosity and low-pollution protective film is provided, wherein the low-viscosity and low-pollution protective film comprises a substrate layer, a polyurethane adhesive layer, an acrylate adhesive layer, and a release material layer which are stacked in sequence;

[0083] The substrate layer is a PET substrate layer with a thickness of 50 μm;

[0084] The release material layer is made of PET and has a thickness of 30 μm;

[0085] The thickness of the acrylic adhesive layer is 10 μm, and the raw materials for preparing the layer include the following components by weight: 100 parts of polyacrylate, 1 part of antistatic agent, 2 parts of polyester resin, 20 parts of tackifying resin, 1 part of curing agent, and 60 parts of solvent;

[0086] The thickness of the polyurethane adhesive layer is 5 μm, and the raw materials for preparing the layer include the following components by weight: 100 parts of polyurethane resin, 25 parts of tackifying resin, 2.5 parts of curing agent, 0.2 parts of catalyst, and 60 parts of solvent;

[0087] Among them, the antistatic agent is tributyl methyl ammonium trifluoromethanesulfonyl imide salt; the catalyst is dibutyl tin dilaurate; the tackifying resin in the preparation raw materials of the acrylate adhesive layer and the polyurethane adhesive layer is French DRT Deercolyte LTG, the curing agent is trimethyl hexamethylene diisocyanate, and the solvent is ethyl acetate.

[0088] The preparation method is the same as that of Example 1.

[0089] Comparative Example 1

[0090] The only difference between this comparative example and Example 1 is that the protective film does not include a polyurethane adhesive layer; the thickness of other layers, preparation raw materials, etc. are the same as those in Example 1, and the preparation method is adaptively adjusted.

[0091] Comparative Example 2

[0092] The only difference between this comparative example and Example 1 is that the protective film does not include an acrylate adhesive layer; the thickness of other layers, preparation raw materials, etc. are the same as those in Example 1, and the preparation method is adaptively adjusted.

[0093] Comparative Example 3

[0094] The only difference between this comparative example and Example 1 is that the order of the polyurethane adhesive layer and the acrylate adhesive layer is exchanged, that is, the protective film includes a substrate layer, an acrylate adhesive layer, a polyurethane adhesive layer, and a release material layer stacked in sequence; the thickness of each layer, the raw materials for preparation, etc. are the same as those in Example 1, and the preparation method is adaptively adjusted.

[0095] Comparative Example 4

[0096] The only difference between this comparative example and Example 1 is that the raw materials for preparing the acrylic adhesive layer do not include polyester resin.

[0097] Comparative Example 5

[0098] A conventional protective film, comprising a substrate layer, an acrylate adhesive layer, and a release material layer stacked in sequence;

[0099] The substrate layer is a PET substrate layer with a thickness of 50 μm;

[0100] The release material layer is made of PET and has a thickness of 30 μm;

[0101] The thickness of the acrylic adhesive layer is 16 μm, and the raw materials for preparing the layer include the following components in parts by weight: 100 parts of polyacrylate, 1 part of curing agent, and 40 parts of solvent;

[0102] Among them, the polyacrylate is Changxing Chemical 7710, the curing agent is trimethylhexamethylene diisocyanate, and the solvent is ethyl acetate.

[0103] The preparation method comprises the following steps:

[0104] (1) mixing raw materials for preparing an acrylate adhesive layer to obtain an acrylate adhesive solution, coating the acrylate adhesive solution on the surface of the PET substrate layer, and curing at 110° C. for 5 minutes to form an acrylate adhesive layer;

[0105] (2) A release profile is attached to the surface of the acrylic adhesive layer and cured at 40° C. for 40 h to obtain the conventional protective film.

[0106] The performance test of the protective film provided in the embodiment of the present invention and the comparative example is carried out, and the test method is as follows:

[0107] (1) Peel strength: Ordinary 50 μm PET (Huamei HM50TAN) was used as the test surface, and then the obtained protective film sample was tested for 180° peel strength according to the method provided in GB / T 2792-2014 "Test method for peel strength of adhesive tape";

[0108] (2) Without protective film, the peel strength of tesa 7475 on 50 μm PET (Huamei HM50TAN) is tested by using ordinary 50 μm PET as the test surface, and then testing the 180° peel strength of tesa 7475 tape according to the method provided in GB / T 2792-2014 “Test method for peel strength of adhesive tapes”;

[0109] (3) Peel strength of tesa 7475 on 50 μm PET (Huamei HM50TAN) with protective film: Take ordinary 50 μm PET as the test surface, stick the obtained protective film sample on the PET test surface and keep it at constant temperature and humidity (temperature 22.5±2.5℃, humidity 50±10%RH) for 7d to 60d, then tear off the protective film, and then test the 180° peel strength of tesa 7475 tape according to the method provided in GB T 2792-2014 "Test method for peel strength of adhesive tapes".

[0110] The performance test results are shown in Table 2.

[0111] Table 2

[0112]

[0113] It can be seen from Table 2 that the protective film provided by the embodiment of the present invention has low viscosity and low pollution, stable peeling force without climbing, low pollution to the bonding surface, no impact on the performance of the bonding surface, convenient for subsequent product applications, energy saving and environmental protection, and reduced pollution.

[0114] Compared with Example 1, the peeling force of the protective film provided by Comparative Example 1 increases significantly, and there is a greater pollution to the bonding surface; the peeling force of the protective film provided by Comparative Example 2 increases less, but still has a certain pollution to the bonding surface; the peeling force of the protective film provided by Comparative Example 3 increases significantly, and there is a greater pollution to the bonding surface; the peeling force of the protective film provided by Comparative Example 4 increases significantly, and there is a greater pollution to the bonding surface; the peeling force of the protective film provided by Comparative Example 5 increases significantly, and there is a greater pollution to the bonding surface.

[0115] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the low-viscosity and low-pollution protective film and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A low-viscosity and low-pollution protective film, characterized in that: The low-viscosity and low-pollution protective film comprises a substrate layer, a polyurethane adhesive layer, an acrylate adhesive layer, and a release material layer which are stacked in sequence; The raw materials for preparing the acrylic ester adhesive layer include polyacrylate and polyester resin.

2. The low-viscosity and low-pollution protective film according to claim 1, characterized in that: The raw materials for preparing the acrylic adhesive layer also include any one or a combination of at least two of an antistatic agent, a tackifying resin, and a curing agent; Preferably, the raw materials for preparing the acrylic adhesive layer include the following components in parts by weight: 100 parts of polyacrylate, 0.5-2 parts of antistatic agent, 1-4 parts of polyester resin, 15-45 parts of tackifying resin, 0.1-3 parts of curing agent, and 20-80 parts of solvent; Preferably, the raw materials for preparing the polyurethane adhesive layer include the following components in parts by weight: 100 parts of polyurethane resin, 15-45 parts of tackifying resin, 0.1-3 parts of curing agent, 0.1-1 part of catalyst, and 20-80 parts of solvent.

3. The low-viscosity and low-pollution protective film according to claim 1 or 2, characterized in that: The polyacrylate is obtained by polymerizing any one of methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate or n-butyl acrylate, or copolymerizing at least two of them; Preferably, the antistatic agent includes any one of tributylmethylammonium trifluoromethanesulfonyl imide salt, bis(trifluoromethanesulfonyl)imide lithium salt, and dimethyl carbonate, or a combination of at least two thereof.

4. The low-viscosity and low-pollution protective film according to any one of claims 1 to 3, characterized in that: The polyester resin is a copolyester polymer compound formed by alternating copolymerization of diols and alternating diols; Preferably, the polyurethane resin is obtained by polymerization of polyisocyanate and polyether polyol or polyester polyol; Preferably, the catalyst includes any one of dibutyltin dilaurate, stannous oleate, triethylamine, triethanolamine, and N-methylmorpholine, or a combination of at least two thereof.

5. The low-viscosity and low-pollution protective film according to any one of claims 2 to 4, characterized in that: The tackifying resins in the raw materials for preparing the acrylic adhesive layer and the polyurethane adhesive layer independently include any one of liquid C5 petroleum resin, liquid polyterpene resin, hydrogenated rosin acid methyl ester, dicyclopentadiene resin, 2,2'-thiodiethyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and ethyl acetate, or a mixture of at least two thereof; Preferably, the curing agent in the raw materials for preparing the acrylic adhesive layer and the polyurethane adhesive layer independently includes any one of hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate or dicyclohexylmethane diisocyanate, or a combination of at least two thereof; Preferably, the solvents in the raw materials for preparing the acrylic adhesive layer and the polyurethane adhesive layer independently include any one of ethyl acetate, toluene, ethanol, methyl ethyl ketone, acetone, and dichloromethane, or a combination of at least two of them.

6. The low-viscosity and low-pollution protective film according to any one of claims 1 to 5, characterized in that: The material of the substrate layer is polyethylene terephthalate; Preferably, the release material layer is made of polyethylene terephthalate.

7. The low-viscosity and low-pollution protective film according to any one of claims 1 to 6, characterized in that: The thickness of the substrate layer is 30 to 90 μm; Preferably, the thickness of the polyurethane adhesive layer is 5 to 10 μm; Preferably, the thickness of the acrylic adhesive layer is 5 to 10 μm; Preferably, the thickness of the release material layer is 20-40 μm; Preferably, the total thickness of the low-viscosity and low-pollution protective film is 60-150 μm.

8. A method for preparing a low-viscosity and low-pollution protective film as claimed in any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: (1) mixing raw materials for preparing a polyurethane adhesive layer to obtain a polyurethane adhesive solution, coating the polyurethane adhesive solution on a surface of a substrate, and curing the mixture to form a polyurethane adhesive layer; (2) mixing the raw materials for preparing the acrylate adhesive layer to obtain an acrylate type adhesive solution, coating the acrylate type adhesive solution on the surface of the polyurethane adhesive layer, and curing to form an acrylate adhesive layer; (3) A release profile is pasted on the surface of the acrylic adhesive layer and cured to obtain the low-viscosity and low-pollution protective film.

9. The preparation method according to claim 8, characterized in that: The curing temperature in step (1) is 110-130° C. and the curing time is 5-15 min. Preferably, the curing temperature in step (2) is 110-130° C., and the curing time is 5-15 min; Preferably, the aging temperature in step (3) is 40-50° C., and the aging time is 30-50 h.

10. Use of the low-viscosity and low-pollution protective film according to any one of claims 1 to 7 in a display screen manufacturing process.

Images