Special tape casting method co-extrusion PP (polypropylene) self-adhesive protective film for nano-silver conductive film

Abstract

The invention discloses a special tape casting method co-extrusion PP self-adhesive protective film for a nano-silver conductive film. The protective film is prepared from the following materials in parts by weight: 60 to 80 parts of block co-polypropylene, 5 to 10 parts of TPX, 2 to 3 parts of EMMA, 1 to 5 parts of low-density polyethylene, 5 to 15 parts of SEPS, 0.1 to 0.3 part of antioxidant and 2 to 3 parts of hydrogenated terpene resin, and 0.1 to 0.5 part of fumed silica. The PP is used as the base material layer, so that the temperature resistance is effectively improved, and the surface of the film is frosted and the anti-adhesion effect is realized by adding the TPX and a small amount of PE; sEPS is used as a self-adhesive layer, hydrogenated terpene resin is used for increasing the softening point of SEPS, the adhesive layer is endowed with good initial adhesion and wettability, LDPE is added to the adhesive layer, and fumed silica is added to the adhesive layer, so that the problem of viscosity climbing caused by creep deformation of the adhesive layer in the baking process is solved, and the service life of the adhesive layer is prolonged. And meanwhile, the problems of adhesive residue of the coating protective film, poor temperature resistance of the PE base material protective film and the like are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of protective films, and particularly relates to a cast co-extruded PP self-adhesive protective film for a nano-silver conductive film. Background Art

[0002] With the development of electronic displays towards large size and flexibility, the requirements for the electrical conductivity, optical properties and flexibility of conductive films are getting higher and higher. Currently, the most widely used ITO (indium tin oxide) transparent conductive film in the market has brittle and yellowing conductive layers while meeting the requirements of large-size touch control in terms of electrical conductivity, and is not suitable for large-size touch displays. Among new materials, nano-silver wires have become the optimal alternative to ITO due to their excellent comprehensive properties such as good optical properties, good flexibility and low sheet resistance.

[0003] Currently, the special protective films for nano-silver conductive films on the market generally have problems such as many crystal points, unstable adhesion, poor heat resistance and poor flatness. When coating these protective films, the residual glue rate is relatively high, and the number of meters per roll is small, resulting in frequent roll changes and inability to produce continuously.

[0004] Therefore, how to provide a cast co-extruded PP self-adhesive protective film for a nano-silver conductive film to solve the problems existing in the prior art is of great significance for its application. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a cast co-extruded PP self-adhesive protective film for a nano-silver conductive film to solve the problems.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A cast co-extruded PP self-adhesive protective film for a nano-silver conductive film, comprising the following materials in parts by weight: 60-80 parts by weight of polypropylene, 5-10 parts by weight of TPX (a copolymer based on 4-methyl-1-pentene, hereinafter referred to as TPX), 2-3 parts by weight of EMMA (ethylene-methyl methacrylate copolymer), 1-5 parts by weight of low-density polyethylene, 5-15 parts by weight of SEPS, 0.1-0.3 parts by weight of antioxidant and 2-3 parts by weight of hydrogenated terpene resin; 0.1-0.5 parts of fumed silica.

[0008] Preferably, the self-adhesive protective film is divided into a base material layer and a self-adhesive layer, and the base material layer includes a middle layer and a surface layer.

[0009] Preferably, the component ratio of the surface layer includes: PP: 88%-97%; TPX: 1-10%, EMMA 2-3%.

[0010] Preferably, the component ratio of the middle layer includes: PP: 80%-87%; TPX: 1-10%; cast film edge material: 10%, EMMA 2-3%.

[0011] Preferably, the parts by weight of the self-adhesive layer include:

[0012] SEPS: 40 parts; hydrogenated terpene resin: 0-50 parts; LDPE: 40 parts; fumed silica: 1.5 parts; antioxidant: 0.5 part.

[0013] Preferably, the antioxidant used is antioxidant 1010.

[0014] Preferably, the self-adhesive protective film is formed by the T-die casting co-extrusion method.

[0015] Preferably, the processing temperature of the base material of the T-die casting co-extrusion method is 245 °C, the processing temperature of the adhesive layer is 230 °C, the die is 240 °C, and the temperature of the cooling forming roll is 25 °C.

[0016] Preferably, the softening point of the hydrogenated terpene resin is preferably 100-140.

[0017] Preferably, the styrene content in the SEPS is 10-30, and the MI is 3-30 g / 10 min.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. The present invention uses PP as the base material layer, effectively improving the heat resistance of this type of self-adhesive protective film. The anti-blocking effect is achieved by adding TPX to the surface layer, solving the problems of viscosity reduction and precipitation of traditional silicon or fluorine-based unwinding materials. Before processing, the low-temperature grinding process is used to make TPX form powder with a diameter of about 50 μm and then add it to the film. Utilizing the incompatibility between TPX and PP, a sea-island structure is realized, reducing the contact points of the adhesive layer with the surface layer. At the same time, due to the low surface tension of TPX itself, the unwinding force is further reduced. Due to its incompatibility, it may fall off to the adhesive layer after being wound into a roll, thereby affecting the surface of the adherend. Therefore, EMMA is added to bond TPX and PP to prevent TPX from falling off. TPX can improve the heat resistance of PP, reduce the molecular chain movement after high temperature, and reduce the shrinkage and curling of the film.

[0020] 2. The present invention significantly improves the overall flatness of the film after casting processing and forms a uniform matte effect in cooperation with TPX and PP by adding a small amount of PE to the base material layer;

[0021] 3. The present invention uses SEPS as the self - adhesive layer, which improves good elasticity. By adding hydrogenated terpene resin, the softening point of SEPS is increased and good initial adhesion and wettability are imparted to the adhesive layer. By adding LDPE to the adhesive layer, the adhesion of the protective film on the surface of the conductive film is effectively controlled to prevent difficult peeling due to excessive viscosity. By adding fumed silica to the adhesive layer, the problem of viscosity climb caused by creep of the adhesive layer during the baking process of the film is well solved. At the same time, problems such as residual glue of the coated protective film and poor heat resistance of the PE - based protective film are solved.

[0022] The above description is only an overview of the technical solution of this application. In order to be able to understand the technical means of this application more clearly, so that it can be implemented in accordance with the content of the description, and in order to make the above - mentioned and other purposes, features and advantages of this application more obvious and understandable, the following takes the preferred embodiments of this application and combines with the drawings to describe in detail as follows.

[0023] According to the following detailed description of the specific embodiments of this application in combination with the drawings, those skilled in the art will be more clear about the above - mentioned and other purposes, advantages and features of this application. Brief Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of this application or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following - described drawings are some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to actual scale.

[0025] Figure 1 It is the formula table in the present invention;

[0026] Figure 2 It is the example table of the substrate layer in the present invention;

[0027] Figure 3 It is the example table of the adhesive layer in the present invention;

[0028] Figure 4 It is the test result table of the adhesive layer in the present invention. Detailed Description of the Specific Embodiments

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. In the following description, specific details such as specific configurations and components are provided only to assist in a comprehensive understanding of the embodiments of this application. Therefore, those skilled in the art should clearly understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Additionally, descriptions of known functions and structures are omitted in the embodiments for clarity and conciseness.

[0030] In addition, this application may repeat reference numerals and / or letters in different instances. This repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or arrangements discussed.

[0031] The term "and / or" in this document is merely a description of the associated relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" in this document describes another associated object relationship, indicating that two relationships may exist. For example, A / and B may represent: A exists alone, and A and B exist alone. Additionally, the character " / " in this document generally indicates that the associated objects before and after are in an "or" relationship.

[0032] It should also be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variation thereof are intended to cover non-exclusive inclusion.

[0033] Please refer to Figures 1-3 , this invention provides a technical solution for a cast co-extruded PP self-adhesive protective film dedicated to a nano-silver conductive film:

[0034] Selection of the substrate layer

[0035] Example 1: Surface layer ratio: 97% PP, 1% TPX, 2% EMMA; Middle layer: 87% PP, 1% TPX, 10% cast film edge material, 2% EMMA;

[0036] Example 2: Surface layer ratio: 95% PP, 3% TPX, 2% EMMA; Middle layer: 85% PP, 3% TPX, 10% cast film edge material, 2% EMMA;

[0037] Example 3: Surface layer ratio: 93% PP, 5% TPX, 2% EMMA; Middle layer: 83% PP, 5% TPX, 10% cast film edge material, 2% EMMA;

[0038] Example 4: Surface layer ratio: 90% PP, 8% TPX, 2% EMMA; Middle layer: 80% PP, 8% TPX, 10% cast film edge material, 2% EMMA;

[0039] Example 5: Surface layer ratio: 88% PP, 10% TPX, 2% EMMA; Middle layer: 78% PP, 10% TPX, 10% cast film edge material, 2% EMMA;

[0040] It is formed by the T-shaped cast co-extrusion method, with a processing temperature of 245 degrees and a cooling roll temperature of 25 degrees. The substrate film is tested for the film surface roughness and cost, and Example 3 is preferably used as the substrate layer of the self-adhesive film.

[0041] Among them, PP uses Dushanzi W725F, TPX uses Mitsui Chemicals DX560M, and EMMA uses Sumitomo WH303.

[0042] Using PP as the substrate layer effectively improves the heat resistance of this type of self-adhesive protective film. The anti-blocking effect is achieved by adding TPX to the surface layer, solving the problems of viscosity reduction and precipitation of traditional silicon or fluorine-based uncoiling materials. Before processing, the low-temperature grinding process is used to make TPX form powder with a diameter of about 50um and then add it to the film. Utilizing the incompatibility between TPX and PP, a sea-island structure is achieved, reducing the contact points of the adhesive layer with the surface layer. At the same time, due to the low surface tension of TPX itself, the uncoiling force is further reduced. Because of its incompatibility, it may fall off to the adhesive layer after being wound into a roll, thus affecting the surface of the adhered object. Therefore, EMMA is added to bond TPX and PP to prevent TPX from falling off. TPX can improve the heat resistance of PP, reduce the molecular chain movement after high temperature, and reduce the shrinkage and curling of the film.

[0043] Then is the selection of the self-adhesive layer;

[0044] Adhesive Example 1: 40 parts of SEPS, 40 parts of LDPE, 1.5 parts of fumed silica, 0.5 part of antioxidant 1010;

[0045] Adhesive Example 2: 40 parts of SEPS, 10 parts of hydrogenated terpene resin, 40 parts of LDPE, 1.5 parts of fumed silica, 0.5 part of antioxidant 1010;

[0046] Adhesive Example 3: 40 parts of SEPS, 20 parts of hydrogenated terpene resin, 40 parts of LDPE, 1.5 parts of fumed silica, 0.5 part of antioxidant 1010;

[0047] Adhesive Example 4: 40 parts of SEPS, 30 parts of hydrogenated terpene resin, 40 parts of LDPE, 1.5 parts of fumed silica, 0.5 part of antioxidant 1010;

[0048] Adhesive Example 5: 40 parts of SEPS, 40 parts of hydrogenated terpene resin, 40 parts of LDPE, 1.5 parts of fumed silica, 0.5 part of antioxidant 1010;

[0049] Adhesive Example 6: 40 parts of SEPS, 50 parts of hydrogenated terpene resin, 40 parts of LDPE, 1.5 parts of fumed silica, 0.5 part of antioxidant 1010;

[0050] Among them, SEPS is from Kraton G1701, hydrogenated terpene resin is from Exxon T-115, LDPE is from CNOOC and Shell 2420H, fumed silica is from Evonik A380, and antioxidant 1010 is from BASF.

[0051] The processing temperature of the adhesive layer is 230 °C. Using the substrate of Example 3, a film with a thickness of 42 μm is obtained, with a surface layer thickness of 8 μm, a middle layer thickness of 30 μm, and an adhesive layer thickness of 4 μm. It is wound into a roll with a width of 1300 mm and a length of 3000 m using a 3-inch ABS pipe and delivered.

[0052] Test results:

[0053] (1) Unwinding force

[0054] The surface protective film was respectively wound around a PP core with an inner diameter of 3 inches to make a film roll with a width of 50 mm. According to JIS Z0237, the surface protective film was unwound from the film roll at an unwinding speed of 20 m / min, and the high-speed unwinding force was measured. The test value is the unwinding force;

[0055] Internal standard: An unwinding force less than 0.5 N / 50 mm is evaluated as A, more than 0.5 N / mm but not exceeding 1 N / 50 mm is B, and more than 1 N / 50 mm is C.

[0056] (2) Initial adhesion

[0057] Lamination was carried out within 3 days after the production of the surface protective film to cover the protected surface of the conductive film. A conductive film with a surface sheet resistance of 20 ± Ω, a haze of 3% ± 1%, and a surface hardness of H was prepared. The lamination conditions were in an environment of room temperature 23 °C and relative humidity 50%, using a 2 kg rubber roller, and laminating at a speed of 300 mm / min. After leaving it in this state for 30 min, the 180° peel strength of a 25 mm width was measured at a speed of 300 mm / min according to JIS Z0237. The peel strength at this time is used as the initial adhesion.

[0058] (3) Adhesion after high temperature

[0059] Lamination was carried out within 3 days after the surface protective film was fabricated to cover the protected surface of the conductive film. The conductive film was prepared. The lamination conditions were as follows: in an environment of room temperature 23°C and relative humidity 50%, using a 2 kg rubber roller, laminating at a speed of 300 mm / min. After placing in this state for 30 min, the laminated product was placed in a baking environment at 150°C for 30 min. After the baking was completed, it was taken out and left standing for 30 min, and then the 180-degree peel strength of a 25 mm width was tested at a speed of 300 mm / min according to JIS Z0237. The peel strength at this time was used as the adhesion after high temperature.

[0060] (4) Contamination

[0061] After peeling the sample film from the adherend, the adherend surface was irradiated with concentrated light in a dark room, and the surface contamination state was observed with the naked eye. The determined states were: no contamination A, slight contamination B, and contamination C.

[0062] (5) Test of film curling degree

[0063] The laminated product was cut into the size of A4 paper with a blade. At normal temperature and after high temperature, the laminated adherend product was placed on a glass tabletop. After standing for 30 min, the distance from the edge to the tabletop was measured. The judgment results were: warping less than 1 cm was A, greater than 1 cm but less than 3 cm was B, and greater than 3 cm was C;

[0064] The test results of normal temperature peel force for adhesive examples 1 - 6 were 0.01 N / 25 mm, 0.03 N / 25 mm, 0.05 N / 25 mm, 0.08 N / 25 mm, 0.2 N / 25 mm, and 0.5 N / 25 mm respectively;

[0065] The test results of peel force after high temperature for adhesive examples 1 - 6 were 0.25 N / 25 mm, 0.38 N / 25 mm, 0.2 N / 25 mm, 0.25 N / 25 mm, 0.6 N / 25 mm, and 1.0 N / 25 mm respectively;

[0066] The test results of contamination for adhesive examples 1 - 4 were A, and 5 - 6 were B;

[0067] The test results of curling degree for adhesive examples 1 - 6 were all grade A;

[0068] The test results of unfolding force for adhesive examples 1 - 6 were all grade A;

[0069] After comprehensive evaluation, adhesive example 4 was preferably selected.

[0070] The present invention uses SEPS as the self-adhesive layer, which improves good elasticity, and improves the softening point of SEPS and gives the adhesive layer good initial adhesion and wettability by adding hydrogenated terpene resin. By adding LDPE to the adhesive layer, the adhesion of the protective film on the surface of the conductive film is effectively controlled to prevent difficult peeling due to excessive viscosity. By adding fumed silica to the adhesive layer, the problem of viscosity climb caused by creep of the adhesive layer during baking of the film is well solved, and at the same time, problems such as residual glue of the coated protective film and poor heat resistance of the PE substrate protective film are solved.

[0071] The above are only the preferred embodiments of the present invention, and it does not limit the protection scope of the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any changes, modifications, substitutions, integrations and parameter changes made to these embodiments by means of conventional substitutions or capable of achieving the same functions without departing from the principle and spirit of the present invention fall within the protection scope of the present invention.

Claims

1. A casting co-extrusion PP self-adhesive protective film for nano-silver conductive films, characterized in that: Comprising the following materials in parts by weight: 60 - 80 parts by weight of polypropylene, 5 - 10 parts by weight of TPX (a copolymer based on 4-methyl-1-pentene, hereinafter referred to as TPX), 2 - 3 parts by weight of EMMA (ethylene-methyl methacrylate copolymer), 1 - 5 parts by weight of low density polyethylene, 5 - 15 parts by weight of SEPS, 0.1 - 0.3 parts by weight of antioxidant, and 2 - 3 parts by weight of hydrogenated terpene resin; 0.1 - 0.5 parts of fumed silica.

2. The casting co-extrusion PP self-adhesive protective film for nano-silver conductive films according to claim 1, characterized in that: The self-adhesive protective film is divided into a substrate layer and a self-adhesive layer, and the substrate layer includes a middle layer and a surface layer.

3. The casting co-extrusion PP self-adhesive protective film for nano-silver conductive films according to claim 2, characterized in that: The component ratio of the surface layer includes: PP: 88% - 97%; TPX: 1 - 10%, EMMA 2 - 3%.

4. The casting co-extrusion PP self-adhesive protective film for nano-silver conductive films according to claim 3, characterized in that: The component ratio of the middle layer includes: PP: 80% - 87%; TPX: 1 - 10%; cast film edge material: 10%, EMMA 2 - 3%.

5. The casting co-extrusion PP self-adhesive protective film for nano-silver conductive films according to claim 4, characterized in that: The parts by weight of the self-adhesive layer include: SEPS: 40 parts; hydrogenated terpene resin: 0 - 50 parts; LDPE: 40 parts; fumed silica: 1.5 parts; antioxidant: 0.5 parts.

6. The casting co-extrusion PP self-adhesive protective film for nano-silver conductive films according to claim 5, characterized in that: The antioxidant used is antioxidant 1010.

7. The casting co-extrusion PP self-adhesive protective film for nano-silver conductive films according to claim 6, characterized in that: The self-adhesive protective film is formed by the T-die casting co-extrusion method.

8. The casting co-extrusion PP self-adhesive protective film for nano-silver conductive films according to claim 7, characterized in that: For the T-die casting co-extrusion method, the processing temperature of the substrate is 245 degrees, the processing temperature of the adhesive layer is 230 degrees, the temperature of the die is 240 degrees, and the temperature of the cooling forming roll is 25 degrees.

9. The casting co-extrusion PP self-adhesive protective film for nano-silver conductive films according to claim 8, characterized in that: The softening point of the hydrogenated terpene resin is preferably 100 - 140.

10. The casting co-extrusion PP self-adhesive protective film for nano-silver conductive films according to claim 9, characterized in that: The styrene content in the SEPS is 10 - 30, and the MI is 3 - 30 g / 10 min.

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