Acid and alkali resistant protective film and preparation method thereof

Abstract

The invention relates to the technical field of protective films, in particular to an acid and alkali resistant protective film and a preparation method thereof, the acid and alkali resistant protective film comprises an acid and alkali resistant base film, an acid and alkali resistant adhesive layer coated on the surface of the acid and alkali resistant base film, and a release film pasted on the surface of the acid and alkali resistant adhesive layer, comprising the following components in parts by weight: 15-50 parts of butyl rubber, 2-5 parts of high molecular weight polyisobutene, 2-5 parts of low molecular weight polyisobutene, 1-3 parts of an antioxidant and 30-80 parts of an organic solvent. According to the invention, butyl rubber with excellent acid and alkali resistance and air tightness is used as matrix resin, and saturated linear polymer polyisobutene is used as tackifying resin, so that the adhesive has excellent air tightness and excellent acid and alkali resistance, and has better retention force while ensuring proper adhesive strength; the method can be applied to the electroplating industry, the PCB and FPC circuit field, the metal protection field and the precision electronic protection field.

Description

Technical Field

[0001] The present application relates to the technical field of protective films, and in particular to an acid- and alkali-resistant protective film and a preparation method thereof. Background Art

[0002] With the continuous development of science and technology, various electronic products emerge in an endless stream. With the changing use environment of electronic products, in the process of process protection and factory protection, certain protective measures need to be taken on the surface of equipment, devices and other products to prevent the surface of the product from being contaminated or corroded during processing or transportation. Especially in the process of PCB or FPC, the circuit board needs to be immersed in a container containing etching liquid for etching. Faced with different manufacturing processes, some need to be cleaned with alkali first, and then electroplated or etched in an acidic environment; some are directly etched in an acidic environment. In order to avoid contamination and corrosion of the pre-printed circuit, a protective film needs to be attached to the surface. However, the existing PET acid-alkali resistant acrylic protective film or gold finger PI tape is either not acid-resistant or not alkali-resistant, and cannot meet the application requirements in acid-resistant or alkali-resistant environments while ensuring the adhesion to copper foil. Therefore, it is necessary to develop a protective film that is both acid-resistant and alkali-resistant. Summary of the invention

[0003] In order to solve the above technical problems, the present application provides an acid- and alkali-resistant protective film, comprising an acid- and alkali-resistant base film, an acid- and alkali-resistant adhesive layer coated on the surface of the acid- and alkali-resistant base film, and a release film attached to the surface of the acid- and alkali-resistant adhesive layer, wherein the acid- and alkali-resistant adhesive layer comprises the following components in parts by weight: 15 to 50 parts of butyl rubber, 2 to 5 parts of high molecular weight polyisobutylene, 2 to 5 parts of low molecular weight polyisobutylene, 1 to 3 parts of an antioxidant, and 30 to 80 parts of an organic solvent.

[0004] Preferably, the number average molecular weight Mn of the high molecular weight polyisobutylene is ≥50000 g / mol

[0005] Preferably, the number average molecular weight of the low molecular weight polyisobutylene is Mn≤3000 g / mol.

[0006] Preferably, the thickness of the acid-alkali resistant adhesive layer is 10 to 50 um.

[0007] Preferably, the acid-base resistant base film is any one of a polyethylene film, a polypropylene film, a polyvinyl chloride film, a polytetrafluoroethylene film, a polyvinylidene fluoride film, a polyimide film, and a polyetheretherketone film.

[0008] Preferably, the acid-base resistant film has a thickness of 5 to 100 um.

[0009] Preferably, a preparation method for preparing the above-mentioned acid- and alkali-resistant protective film comprises the following steps:

[0010] S1. Weigh butyl rubber, high molecular weight polyisobutylene, low molecular weight polyisobutylene, antioxidant and organic solvent according to parts by weight;

[0011] S2, adding butyl rubber into an organic solvent and stirring, and obtaining a rubber solution after the butyl rubber is fully dissolved;

[0012] S3, adding the remaining raw materials to the rubber solution in sequence and stirring evenly to obtain a coating solution;

[0013] S4, applying the coating liquid to the surface of the acid-base resistant base film, when the coating liquid is cured, an acid-base adhesive layer is formed on the acid-base resistant surface, and a release film is attached to the surface of the acid-base resistant adhesive layer to obtain an acid-base resistant protective film.

[0014] Preferably, in step S2, the butyl rubber is first cut into small pieces by a cutting machine, and added into a container containing an organic solvent for stirring. The stirring time is 8 to 12 hours and the stirring speed is 600 to 800 rpm.

[0015] Preferably, in step S3, high molecular weight polyisobutylene is first added to the rubber solution, the stirring time is 5 to 8 minutes, and the stirring speed is 400 to 600 rpm;

[0016] Then, low molecular weight polyisobutylene is added to the rubber solution, and the stirring time is 5 to 8 minutes and the stirring speed is 400 to 600 rpm;

[0017] Finally, the antioxidant is added to the rubber solution, the stirring time is 5 to 8 minutes, and the stirring speed is 400 to 600 rpm to obtain a mixed solution;

[0018] The mixed solution was filtered through a 300-mesh filter to obtain a coating solution.

[0019] Preferably, in step S4, after the coating liquid is applied to the surface of the acid- and alkali-resistant base film, the acid- and alkali-resistant base film coated with the coating liquid is baked in a continuous oven at 70°C, 90°C, 100°C, 120°C, 120°C and 100°C in sequence to completely evaporate the solvent and solidify it.

[0020] As can be seen from the above, the following beneficial effects can be obtained by applying the present application: the present invention adopts butyl rubber with excellent acid and alkali resistance and air tightness as the base resin, and selects saturated linear polymer polyisobutylene as the tackifying resin, which not only has excellent air tightness, but also can be acid and alkali resistant. The acid and alkali resistant protective film of the present application has excellent acid and alkali resistance, and has good holding power while ensuring appropriate adhesion, so that the acid and alkali resistant protective film and the copper foil have appropriate adhesion and holding power, and can fit tightly on the surface of the copper foil to form an effective barrier to prevent acid, alkali and other corrosive media from directly contacting the copper foil. At the same time, when it is necessary to peel off, the effect of easy peeling should be achieved, and no residual glue layer will remain on the surface of the copper foil. It can be used in the electroplating industry, PCB and FPC board circuit fields, metal protection fields, and precision electronic protection fields to improve product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the description of the embodiments of the present application or the prior art are briefly introduced below. Obviously, the drawings described below are only part of the embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor.

[0022] Figure 1 This is a flowchart of the method for preparing the acid and alkali resistant protective film according to an embodiment of the present application;

[0023] Figure 2 This is a structural diagram of the acid- and alkali-resistant protective film of an embodiment of the present application;

[0024] Figure 3 This is a structural diagram of an acid- and alkali-resistant protective film according to another embodiment of the present application;

[0025] Figure 4 This is a structural diagram of the acid- and alkali-resistant protective film of other embodiments of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0027] Example 1

[0028] In order to solve the above technical problems, this embodiment provides an acid-alkali resistant protective film, such as Figure 2As shown, it includes an acid- and alkali-resistant base film, an acid- and alkali-resistant adhesive layer coated on the surface of the acid- and alkali-resistant base film, and a release film attached to the surface of the acid- and alkali-resistant adhesive layer. The acid- and alkali-resistant adhesive layer includes the following components in parts by weight: 15 to 50 parts of butyl rubber, 2 to 5 parts of high molecular weight polyisobutylene, 2 to 5 parts of low molecular weight polyisobutylene, 1 to 3 parts of antioxidant, and 30 to 80 parts of organic solvent.

[0029] In this embodiment, butyl rubber is 20 parts, high molecular weight polyisobutylene is 2 parts, low molecular weight polyisobutylene is 2 parts, antioxidant is 2 parts, and organic solvent is 60 parts.

[0030] Among them, butyl rubber is a saturated, non-polar high molecular polymer with excellent air tightness and acid and alkali resistance. It has a stable structure, good corrosion resistance, and is not easy to react with other substances. Polyisobutylene is a saturated linear polymer. In its composition structure, the side chain methyl groups are tightly and symmetrically distributed. It is a unique tackifying resin with excellent air tightness, acid and alkali resistance, and corrosion resistance. Unlike other conventional tackifying resins, conventional tackifying resins such as terpene resins, petroleum resins, rosin resins, etc., although they have good tackifying effects, have poor acid and alkali resistance. Therefore, these conventional resins cannot be used in the technical field of protective films.

[0031] Specifically, the number average molecular weight Mn of the high molecular weight polyisobutylene is ≥50000 g / mol, wherein the high molecular weight polyisobutylene has the characteristics of high modulus and high strength, and can be used to adjust the elasticity, elongation, cohesion and air tightness of the acid and alkali resistant adhesive layer.

[0032] Furthermore, the number average molecular weight of the low molecular weight polyisobutylene is Mn≤3000 g / mol. The low molecular weight polyisobutylene is often used as a tackifier or plasticizer. When used in a matrix resin, the low molecular weight polyisobutylene can play a good tackifying role, and at the same time has good compatibility with butyl rubber, thereby improving the adhesion effect of the protective film.

[0033] In some embodiments, the antioxidant can be any one of phenolic antioxidants, amine antioxidants and ester antioxidants to prevent the rubber from aging during use. The organic solvent can be at least one of white spirit, n-heptane and toluene. In this embodiment, white spirit is used.

[0034] Furthermore, the thickness of the acid-base resistant base film is 5 to 100 um. The thickness of the acid-base resistant adhesive layer is 10 to 50 um. The thickness of the acid-base resistant adhesive layer can be selected according to the thickness of the acid-base resistant base film, so that the acid-base resistant adhesive layer has a certain adhesion to the copper foil on the surface of the circuit board to achieve a protective effect, and during use, it is ensured that the protective film can be easily peeled off when needed, and no adhesive layer will remain on the surface of the copper foil.

[0035] Furthermore, the acid-base resistant base film can be any one of polyethylene film, polypropylene film, polyvinyl chloride film, polytetrafluoroethylene film, polyvinylidene fluoride film, polyimide film, and polyetheretherketone film.

[0036] In some other embodiments, the structure of the acid-base resistant protective film can also be as follows Figure 3-4 As shown,

[0037] On the other hand, this embodiment provides a preparation method for preparing the above-mentioned acid- and alkali-resistant protective film, such as Figure 1 As shown, the following steps are included:

[0038] S1. Weigh butyl rubber, high molecular weight polyisobutylene, low molecular weight polyisobutylene, antioxidant and organic solvent according to parts by weight;

[0039] S2, adding butyl rubber into an organic solvent and stirring, and obtaining a rubber solution after the butyl rubber is fully dissolved;

[0040] In step S2, the butyl rubber is first cut into small pieces by a cutting machine, and then added into a container containing an organic solvent for stirring. The stirring time is 8 to 12 hours, and the stirring speed is 600 to 800 rpm.

[0041] S3, adding the remaining raw materials to the rubber solution in sequence and stirring evenly to obtain a coating solution;

[0042] In step S3, high molecular weight polyisobutylene is first added to the rubber solution, and the stirring time is 5 to 8 minutes, and the stirring speed is 400 to 600 rpm; then low molecular weight polyisobutylene is added to the rubber solution, and the stirring time is 5 to 8 minutes, and the stirring speed is 400 to 600 rpm; finally, an antioxidant is added to the rubber solution, and the stirring time is 5 to 8 minutes, and the stirring speed is 400 to 600 rpm to obtain a mixed solution; the above mixed solution is filtered with a 300-mesh filter to obtain a coating solution.

[0043] S4, applying the coating liquid to the surface of the acid-base resistant base film, when the coating liquid is cured, an acid-base adhesive layer is formed on the acid-base resistant surface, and a release film is attached to the surface of the acid-base resistant adhesive layer to obtain an acid-base resistant protective film.

[0044] In step S4, after the coating liquid is applied to the surface of the acid- and alkali-resistant base film, the acid- and alkali-resistant base film coated with the coating liquid is baked in a continuous oven at 70°C, 90°C, 100°C, 120°C, 120°C and 100°C in sequence to completely evaporate the solvent and solidify it, and finally obtain an acid- and alkali-resistant protective film.

[0045] Example 2

[0046] In this embodiment 2, the raw material components of the acid-base resistant adhesive layer are: 20 parts of butyl rubber, 3 parts of high molecular weight polyisobutylene, 3 parts of low molecular weight polyisobutylene, 2 parts of antioxidant, and 60 parts of organic solvent. The preparation steps are the same as those in embodiment 1 to obtain an acid-base resistant protective film.

[0047] Example 3

[0048] In this embodiment 3, the raw material components of the acid-base resistant adhesive layer are: 20 parts of butyl rubber, 4 parts of high molecular weight polyisobutylene, 4 parts of low molecular weight polyisobutylene, 2 parts of antioxidant, and 60 parts of organic solvent. The preparation steps are the same as those in embodiment 1 to obtain an acid-base resistant protective film.

[0049] Example 4

[0050] In this embodiment 3, the raw material components of the acid-base resistant adhesive layer are: 20 parts of butyl rubber, 5 parts of high molecular weight polyisobutylene, 5 parts of low molecular weight polyisobutylene, 2 parts of antioxidant, and 60 parts of organic solvent. The preparation steps are the same as those in embodiment 1 to obtain an acid-base resistant protective film.

[0051] Comparative Example 1

[0052] In this comparative example 1, the raw material components of the acid-base resistant adhesive layer are: 20 parts of butyl rubber, 2 parts of antioxidant, and 60 parts of organic solvent. In this comparative example, high molecular weight polyisobutylene and low molecular weight polyisobutylene are not added, and the preparation steps are the same as those in Example 1.

[0053] Comparative Example 2

[0054] In this embodiment 3, the raw material components of the acid-base resistant adhesive layer are: 20 parts of butyl rubber, 1 part of high molecular weight polyisobutylene, 1 part of low molecular weight polyisobutylene, 2 parts of antioxidant, and 60 parts of organic solvent. The preparation steps are the same as those in embodiment 1.

[0055] The protective films obtained in the embodiments and the control examples were attached to the surface of the circuit board to protect the copper foil, and then the circuit board with the protective films was subjected to an adhesion test and an acid and alkali resistance test.

[0056]

[0057]

[0058] Table 1

[0059] As shown in Table 1 above, it is a table of test results of various embodiments and control examples. It can be seen from Table 1 above that the content of high molecular weight polyisobutylene and low molecular weight polyisobutylene in Comparative Examples 1 and 2 is insufficient, resulting in the adhesive layer of the protective film failing to meet the test requirements of acid and alkali resistance, failing the acid and alkali resistance test, and failing to protect the copper foil layer of the circuit board. And from the results of Comparative Examples 1 and 2, it can be seen that when high molecular weight polyisobutylene and low molecular weight polyisobutylene are not added, the adhesive layer will have very low adhesion to the copper foil, resulting in the protective film failing to maintain adhesion to the copper foil, while in Comparative Example 2, 1 part of high molecular weight polyisobutylene and low molecular weight polyisobutylene is added, and the adhesion to the copper foil is significantly improved, and the retention force is long-lasting, but the requirements of acid and alkali resistance cannot be met.

[0060] It can be seen from Examples 1-4 in Table 1 that when the content of high molecular weight polyisobutylene and low molecular weight polyisobutylene reaches more than 2 parts, the protective film meets the acid and alkali resistance test requirements. Therefore, the protective films of Examples 1-4 meet the acid and alkali resistance protective films required by this solution.

[0061] Furthermore, as the content of high molecular weight polyisobutylene and low molecular weight polyisobutylene in the adhesive layer increases, the adhesive force of the adhesive layer to the copper foil also increases significantly, but the retention force decreases as the content of high molecular weight polyisobutylene and low molecular weight polyisobutylene increases. Therefore, the relationship between the adhesive force and the retention force of the acid-base resistant protective film is inversely proportional, which means that when designing and applying the acid-base resistant protective film, it is necessary to balance the relationship between the adhesive force and the retention force of the adhesive layer to ensure its long-term effective protection in a specific environment. In addition, the content of high molecular weight polyisobutylene and low molecular weight polyisobutylene is not the higher the better. When the adhesive force is too large, it may cause difficulty in peeling and even damage the copper foil during peeling. Therefore, it is necessary to design the appropriate content of high molecular weight polyisobutylene and low molecular weight polyisobutylene so that the acid-base resistant protective film has appropriate adhesion and retention force with the copper foil, can fit tightly on the surface of the copper foil, and form an effective barrier to prevent corrosive media such as acids and alkalis from directly contacting the copper foil. At the same time, it is easy to peel off when peeling is needed, and no adhesive layer will remain on the surface of the copper foil. Embodiment 1 has good holding power while ensuring appropriate copper foil adhesion, so embodiment 1 can be used as the best embodiment.

[0062] The above-described implementation methods do not constitute a limitation on the protection scope of the technical solution. Any modification, equivalent replacement and improvement made within the spirit and principle of the above-described implementation methods shall be included in the protection scope of the technical solution.

Claims

1. An acid and alkali resistant protective film, characterized in that: It includes an acid- and alkali-resistant base film, an acid- and alkali-resistant adhesive layer coated on the surface of the acid- and alkali-resistant base film, and a release film attached to the surface of the acid- and alkali-resistant adhesive layer. The acid- and alkali-resistant adhesive layer includes the following components in parts by weight: 15 to 50 parts of butyl rubber, 2 to 5 parts of high molecular weight polyisobutylene, 2 to 5 parts of low molecular weight polyisobutylene, 1 to 3 parts of antioxidant, and 30 to 80 parts of organic solvent.

2. The acid and alkali resistant protective film according to claim 1, characterized in that: The number average molecular weight Mn of the high molecular weight polyisobutylene is ≥50000 g / mol.

3. The acid- and alkali-resistant protective film according to claim 1, characterized in that: The number average molecular weight of the low molecular weight polyisobutylene is Mn≤3000 g / mol.

4. The acid- and alkali-resistant protective film according to claim 1, characterized in that: The thickness of the acid-alkali resistant adhesive layer is 10 to 50 μm.

5. The acid- and alkali-resistant protective film according to claim 1, characterized in that: The acid-base resistant base film is any one of polyethylene film, polypropylene film, polyvinyl chloride film, polytetrafluoroethylene film, polyvinylidene fluoride film, polyimide film and polyetheretherketone film.

6. The acid- and alkali-resistant protective film according to claim 1, characterized in that: The thickness of the acid-base resistant film is 5 to 100 um.

7. A preparation method, characterized in that: The method for preparing the acid- and alkali-resistant protective film according to any one of claims 1 to 6 comprises the following steps: S1. Weigh butyl rubber, high molecular weight polyisobutylene, low molecular weight polyisobutylene, antioxidant and organic solvent according to parts by weight; S2, adding butyl rubber into an organic solvent and stirring, and obtaining a rubber solution after the butyl rubber is fully dissolved; S3, adding the remaining raw materials to the rubber solution in sequence and stirring evenly to obtain a coating solution; S4, applying the coating liquid to the surface of the acid-base resistant base film, when the coating liquid is cured, an acid-base adhesive layer is formed on the acid-base resistant surface, and a release film is attached to the surface of the acid-base resistant adhesive layer to obtain an acid-base resistant protective film.

8. The preparation method according to claim 7, characterized in that: In step S2, the butyl rubber is first cut into small pieces by a cutting machine, and then added into a container containing an organic solvent for stirring. The stirring time is 8 to 12 hours and the stirring speed is 600 to 800 rpm.

9. The preparation method according to claim 7, characterized in that: In step S3, high molecular weight polyisobutylene is first added to the rubber solution, with a stirring time of 5 to 8 minutes and a stirring speed of 400 to 600 rpm; Then, low molecular weight polyisobutylene is added to the rubber solution, and the stirring time is 5 to 8 minutes and the stirring speed is 400 to 600 rpm; Finally, the antioxidant is added to the rubber solution, the stirring time is 5 to 8 minutes, and the stirring speed is 400 to 600 rpm to obtain a mixed solution; The mixed solution was filtered through a 300-mesh filter to obtain a coating solution.

10. The preparation method according to claim 7, characterized in that: In step S4, after the coating liquid is applied to the surface of the acid- and alkali-resistant base film, the acid- and alkali-resistant base film coated with the coating liquid is baked in a continuous oven at 70°C, 90°C, 100°C, 120°C, 120°C and 100°C in sequence to completely evaporate the solvent and solidify it.

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