High-viscosity silica gel protective film and preparation method thereof

Abstract

The invention relates to a high-viscosity silica gel protective film which comprises a base material layer and an adhesive layer arranged on the base material layer, and the adhesive layer is prepared from the following raw materials in parts by weight: 55-99.7 parts of organic silicon adhesive; 0.1 to 20 parts of a cross-linking agent; 0.1 to 10 parts of an anchoring agent; and 0.1 to 20 parts of a catalyst. Wherein the organic silicon adhesive is a mixture of high-viscosity silica gel and low-viscosity silica gel, the weight ratio of the high-viscosity silica gel to the low-viscosity silica gel is 1: (0.05-1), the high-viscosity silica gel and the low-viscosity silica gel are compounded according to a specific proportion, and an optimized cross-linking system is matched, so that after the prepared protective film is aged at the high temperature of 85 DEG C or at the high temperature and the high humidity of 85 DEG C / 85% RH, the high-viscosity silica gel and the low-viscosity silica gel are not prone to cracking. The stripping force climbing proportion is obviously reduced; and moreover, the stripping force is effectively controlled after aging, so that the protective film can still be easily stripped from a pasted object after being stored in a severe environment, and the risks of adhesive residue and surface pollution are greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, and more particularly to a high-viscosity silicone protective film and its preparation method. Background Technology

[0002] Silicone protective films are widely used in precision manufacturing fields such as electronics, semiconductor packaging, and optical devices due to their excellent resistance to high and low temperatures, chemical corrosion, low surface energy, and easy peeling. They protect product surfaces from scratches, dust, and chemical corrosion during transportation and processing. An ideal high-adhesion silicone protective film should adhere tightly to various material surfaces at room temperature and be easily peeled off without leaving residue when needed.

[0003] However, in practical applications, especially during the summer transportation of electronic products, protective films may be subjected to extreme high temperature and humidity environments. For example, the temperature inside a sealed container can reach 70-80°C. Under such conditions, the peel force of traditional silicone protective films increases significantly after being applied to the object, exhibiting a noticeable "peel force climb" phenomenon. This makes the protective film difficult to peel off and may cause problems such as residual adhesive and contamination on the surface of the object, seriously affecting customer experience and even leading to quality complaints.

[0004] Therefore, developing a high-adhesion silicone protective film that can maintain stable peel performance and is easy to peel off under harsh environments has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art by proposing a high-viscosity silicone protective film and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a high-viscosity silicone protective film, comprising a substrate layer and an adhesive layer disposed on the substrate layer. The adhesive layer is composed of the following raw materials in parts by weight: silicone adhesive: 55-99.7 parts; crosslinking agent: 0.1-20 parts; anchoring agent: 0.1-10 parts; catalyst: 0.1-20 parts. The silicone adhesive is a mixture of high-viscosity silicone and low-viscosity silicone, and the weight ratio of the high-viscosity silicone to the low-viscosity silicone is 1:0.05-1.

[0008] Furthermore, the high-viscosity silicone is Dow 7657 silicone.

[0009] Furthermore, the low-viscosity silicone is Dow 7688 silicone or Dow 7647 silicone.

[0010] This invention provides a method for preparing the above-mentioned high-viscosity silicone protective film, comprising the following steps:

[0011] S1: Weigh the silicone adhesive, crosslinking agent, anchoring agent and catalyst according to the ratio, mix them evenly to obtain the adhesive mixture;

[0012] S2: Apply the adhesive mixture onto the substrate layer;

[0013] S3: Cross-link the coated substrate layer, cure it, and dry it to form an adhesive layer;

[0014] S4: A release film layer is bonded to the adhesive layer, and the high-adhesion silicone protective film is obtained by winding it up.

[0015] Furthermore, in step S2, comma-shaped doctor blade coating, slit coating, or micro-recessed coating are used.

[0016] Furthermore, in step S3, the cross-linking curing temperature is greater than 130°C.

[0017] Furthermore, in step S3, the drying time is 1-1.5 minutes.

[0018] The present invention provides a high-viscosity silicone protective film and its preparation method, which have the following advantages:

[0019] By using a specific ratio of high-viscosity and low-viscosity silicone composites, along with an optimized crosslinking system, the resulting protective film exhibits a significantly reduced peel strength increase rate after aging at 85°C or 85°C / 85%RH. Furthermore, because the peel strength is effectively controlled after aging, the protective film can still be easily peeled off from the substrate after storage in harsh environments, greatly reducing the risk of residual adhesive and surface contamination. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] The high-viscosity silicone protective film of this invention has a conventional design in the art, typically including a substrate layer, an adhesive layer, and a release film layer. The core improvement of this invention lies in the composition of the adhesive layer. The silicone adhesive is crucial in determining performance; it is a blend of high-viscosity and low-viscosity silicone. The applicant has found that while high-viscosity silicone alone provides strong initial adhesion, its cohesive strength increases too rapidly after aging, leading to a sharp increase in peel force. Conversely, low-viscosity silicone alone results in insufficient initial adhesion. Specifically, the adhesive layer of this invention is composed of the following parts by weight: silicone adhesive: 55-99.7 parts; crosslinking agent: 0.1-20 parts; anchoring agent: 0.1-10 parts; catalyst: 0.1-20 parts. The silicone adhesive is a mixture of high-viscosity and low-viscosity silicone, with a weight ratio of 1:0.05-1. Dow 7028 can be used as a crosslinking agent, Dow 297 as an anchoring agent, and Dow 4000 as a catalyst.

[0022] By mixing high-viscosity and low-viscosity silicone in a specific ratio, the excessive compression of the colloidal crosslinking network under high temperature and high humidity can be effectively alleviated by utilizing the segment flexibility of the low-viscosity silicone, while ensuring sufficient initial adhesion. This suppresses the abnormal rise in peel force. Crosslinking agents, anchoring agents, and catalysts are used to construct a stable and moderately crosslinking network.

[0023] In an optional embodiment of the present invention, the high-viscosity silicone is Dow 7657 silicone.

[0024] In an optional embodiment of the present invention, the low-tack silicone is Dow 7688 silicone or Dow 7647 silicone.

[0025] A method for preparing a high-viscosity silicone protective film includes the following steps:

[0026] S1: Weigh the silicone adhesive, crosslinking agent, anchoring agent and catalyst according to the ratio, mix them evenly to obtain the adhesive mixture;

[0027] S2: Apply the adhesive mixture onto the substrate layer;

[0028] S3: Cross-link the coated substrate layer, cure it, and dry it to form an adhesive layer;

[0029] S4: Lay a release film layer onto the adhesive layer and then roll it up to obtain the high-adhesion silicone protective film.

[0030] In an optional embodiment of the present invention, step S2 employs methods such as comma-shaped blade coating, slot coating, or micro-recessed coating.

[0031] In an optional embodiment of the present invention, in step S3, the crosslinking curing temperature is greater than 130°C.

[0032] In an optional embodiment of the present invention, the drying time in step S3 is 1-1.5 minutes.

[0033] Example 1: In this example, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 60 parts; crosslinking agent: 10 parts; anchoring agent: 10 parts; catalyst: 15 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 11.5. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0034] Example 2: In this example, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 60 parts; crosslinking agent: 10 parts; anchoring agent: 10 parts; catalyst: 15 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 19. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0035] Comparative Example 1: In this embodiment, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 70 parts; crosslinking agent: 10 parts; anchoring agent: 10 parts; catalyst: 15 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 11.5. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0036] Comparative Example 2: In this embodiment, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 70 parts; crosslinking agent: 10 parts; anchoring agent: 10 parts; catalyst: 15 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 19. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0037] Example 3: In this example, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 98 parts; crosslinking agent: 10 parts; anchoring agent: 15 parts; catalyst: 20 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 7.33. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0038] Example 4: In this example, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 95 parts; crosslinking agent: 15 parts; anchoring agent: 10 parts; catalyst: 20 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 8.01. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0039] Example 5: In this example, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 98 parts; crosslinking agent: 15 parts; anchoring agent: 10 parts; catalyst: 20 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 10.11. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0040] Comparative Example 3: In this embodiment, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 95 parts; crosslinking agent: 15 parts; anchoring agent: 10 parts; catalyst: 20 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 9.01. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0041] Comparative Example 4: In this embodiment, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 98 parts; crosslinking agent: 15 parts; anchoring agent: 10 parts; catalyst: 20 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 7.33. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0042] Example 6: In this example, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 55 parts; crosslinking agent: 10 parts; anchoring agent: 10 parts; catalyst: 10 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 4.55. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0043] Example 7: In this example, the raw materials for preparing the adhesive layer include the following components by weight percentage: silicone adhesive: 62 parts; crosslinking agent: 10 parts; anchoring agent: 15 parts; catalyst: 10 parts, wherein the ratio of high-viscosity silicone to low-viscosity silicone is 6.14. The raw materials for the adhesive layer are mixed and prepared according to the above formula, coated on the substrate, crosslinked and cured at 150°C, and baked for 1.5 minutes to obtain a silicone protective film.

[0044] Test method:

[0045] According to the national standard GB / T 2792-1998 "Test Method for 180° Peel Strength of Pressure-Sensitive Adhesive Tapes", a universal tensile testing machine was used for testing. The test procedure was as follows: After cutting the sample, it was bonded to a SUS304 stainless steel plate, and the following conditions were tested: (a) the initial peel force after 20 minutes of bonding (KJ-6001A SUS*20min); (b) the peel force after aging in an 85℃ oven for 96 hours (SUS 85℃*96H); (c) the peel force after aging at 85℃ and 85% relative humidity for 96 hours (SUS 85℃&85RH%*96H). Each set of data was tested three times and the average value was taken. The aging creep rate at 85℃ and the aging creep rate at 85℃ / 85%RH were calculated. The test results are shown in the table below:

[0046] Viscosity test items Example 1 Example 2 Comparative Example 1 Comparative Example 2 Example 3 Example 4 Example 5 Comparative Example 3 Comparative Example 4 Example 6 Example 7 KJ-6001A SUS*20mingf / 25mm 831 935 792 846 873 922 910 979 933 884 912 SUS 85℃*96Hgf / 25mm 1183 1397 1157 1299 1154 1170 1098 1379 1452 1362 1493 SUS 85℃ & 85RH% * 96Hgf / 25mm 1458 1732 1692 1586 1373 1331 1299 1501 1736 1586 1677 85℃*96H aging ramp-up ratio gf / 25mm 42.36% 49.41% 46.09% 53.55% 32.19% 26.90% 20.66% 40.86% 55.63% 54.07% 63.71% 85℃ & 85%RH * 96H aging ramp-up ratio gf / 25mm 75.45% 85.24% 113.64% 87.47% 57.27% 44.36% 42.75% 53.32% 86.07% 79.41% 83.88%

[0047] As can be seen from the test results in the table above, after high temperature and high humidity aging, the peel strength of Comparative Examples 1 and 2, as well as Comparative Examples 3 and 4, generally increased by a relatively high percentage (for example, Comparative Example 4 reached as high as 86.07%).

[0048] In contrast, the embodiments of the present invention, especially embodiments three, four, and five, while maintaining a high initial adhesion, show a significantly reduced peel force creep rate after high temperature and high humidity aging (57.27%, 44.36%, and 42.75%, respectively), demonstrating excellent anti-aging peel force creep performance. Embodiments six and seven also show better results than most comparative embodiments.

[0049] This indicates that by controlling the ratio of high-viscosity silicone (such as Dow 7657) to low-viscosity silicone (such as Dow 7688 or 7647) within a specific range (such as the ratio range corresponding to Examples 3-5), and by coordinating with the appropriate amount of other components, the objective of this invention can be effectively achieved.

[0050] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-adhesion silicone protective film, comprising a substrate layer and an adhesive layer disposed on the substrate layer, characterized in that: The adhesive layer is composed of the following raw materials in parts by weight: silicone adhesive: 55-99.7 parts; crosslinking agent: 0.1-20 parts; anchoring agent: 0.1-10 parts; catalyst: 0.1-20 parts; wherein, The silicone adhesive is a mixture of high-viscosity silicone and low-viscosity silicone, and the weight ratio of the high-viscosity silicone to the low-viscosity silicone is 1:0.05-1.

2. The high-viscosity silicone protective film according to claim 1, characterized in that: The high-viscosity silicone is Dow 7657 silicone.

3. The high-adhesion silicone protective film according to claim 1 or 2, characterized in that: The low-viscosity silicone is Dow 7688 silicone or Dow 7647 silicone.

4. A method for preparing a high-viscosity silicone protective film as described in any one of claims 1-3, characterized in that: Includes the following steps, S1: Weigh the silicone adhesive, crosslinking agent, anchoring agent and catalyst according to the ratio, mix them evenly to obtain the adhesive mixture; S2: Apply the adhesive mixture onto the substrate layer; S3: Cross-link the coated substrate layer, cure it, and dry it to form an adhesive layer; S4: A release film layer is bonded to the adhesive layer, and the high-adhesion silicone protective film is obtained by winding it up.

5. The preparation method according to claim 4, characterized in that: In step S2, the adhesive mixture is applied to the substrate layer using comma-shaped doctor blade coating, slot coating, or micro-recessed coating.

6. The preparation method according to claim 4, characterized in that: In step S3, the cross-linking curing temperature is greater than 130°C.

7. The preparation method according to claim 4, characterized in that: In step S3, the drying time is 1-1.5 minutes.