CN107142032B

CN107142032B - Self-adhesion protective film

Info

Publication number: CN107142032B
Application number: CN201710305106.6A
Authority: CN
Inventors: 邵雪; 李道光
Original assignee: Zhangjiagang Kangdexin Optronics Material Co Ltd
Current assignee: Zhangjiagang Kangdexin Optronics Material Co Ltd
Priority date: 2017-05-03
Filing date: 2017-05-03
Publication date: 2020-12-08
Anticipated expiration: 2037-05-03
Also published as: CN107142032A

Abstract

The invention provides a self-adhesive protective film. The protective film comprises a substrate layer and an adhesion layer located on the substrate layer, wherein the adhesion layer comprises 50-90% of component A and 10-50% of component B in percentage by weight, the component A is an SEBS thermoplastic elastomer, and the component B is one or more of first random polypropylene, first low-density polyethylene and TPO thermoplastic elastomer. The protective film has good adhesiveness and peelability, the adhesive force changes little with temperature and time, the parent roll unwinding force changes little with time and temperature, and the parent roll unwinding force is easy to unwind. In addition, the self-adhesive protective film provided by the invention also has the advantages of low crystal point and high cleanliness, and is very suitable for being used as a surface protective film of a diffusion film.

Description

Self-adhesion protective film

Technical Field

The invention relates to the technical field of organic films, in particular to a self-adhesive protective film.

Background

With the rapid development of the IT and electronic industries and the development of many new high-tech application fields, the demand for protective films of electronic products is increasing. In recent years, ultra-thin displays such as liquid crystal displays, which are mainly composed of a liquid crystal panel and a backlight module, have been used as display devices for personal computers, ultra-thin televisions, and the like. Generally, a backlight module comprises a light source, a reflective film, a light guide plate, an upper diffuser film, an upper brightness enhancement film, a lower brightness enhancement film, and a lower diffuser film. The diffusion film mainly plays a role in converting a point light source or a line light source into a uniform surface light source in order to improve the front brightness of the liquid crystal display. In order to prevent stains or scratches on the surface of the diffusion film during processing and handling, it is necessary to protect the surface thereof. As the diffusion film surface protective film, the protective film is required to have an appropriate adhesive force. And the diffusion film can be rolled into a mother roll after being attached with the protective film, so that the protective film is required not to be difficult to peel off and the like after being subjected to rolling action and extrusion. Also, it is required that the surface of the adherend is not contaminated after the protective film is peeled off. The film appearance is also very strict, and no scratch defect such as a dent or deformation is generated on the adherend due to a convex defect such as a crystal spot or a curl in the surface protective film.

Conventionally, two types of diffusion film surface protection films have been used in most cases:

the adhesive protective film has an adhesive layer, and the adhesive layer is generally coated with low molecular resin, has a wide adhesive strength range, and is widely applied. However, when the protective film is used for manufacturing, an organic solvent is required, the process is not an environmental protection process, odor is generated, and the organic solvent is removed by a secondary baking process, thereby increasing the cost. In addition, the adhesive-coated protective film is prone to cause adhesive residue and dirt on the surface of the optical film microstructure, and high static electricity is prone to be generated during film tearing, so that when the optical film is applied to a backlight module, the problem of poor image quality is caused, and the product reject ratio is increased.

(II) self-adhesive protective film. Since the surface of the diffusion film has irregular diffusion particles and the contact area between the protective film and the film sheet is small, the protective film is generally a rubber-like high-adhesion film and the adhesive layer is in direct contact with the surface of the base material layer in order to provide a suitable stable adhesive force. Self-adhesive protective films generally suffer from the following problems: the unwinding force required for unwinding the parent roll is large, and when the parent roll is stored as a film roll for a long period of time, the unwinding force gradually increases, and the peeling property of the film roll is not good, which causes a problem of significantly lowering the handling property. When the diffusion film is attached to the self-adhesive protective films of different types, other problems can also exist, such as unstable and uneven adhesive force, unstable adhesion between the diffusion film and the protective film, air bubbles, wrinkles and sticking phenomena, or exposure to high temperature in the transportation and storage processes, which causes great change of adhesive force and prevents the film from being torn off.

For the above reasons, it is necessary to provide a self-adhesive protective film having stable adhesive force and small unwinding force under long-term storage and temperature change conditions.

Disclosure of Invention

The invention mainly aims to provide a self-adhesive protective film to solve the problems that the self-adhesive protective film in the prior art is unstable in adhesive force and too high in unwinding force under the conditions of long-term storage and temperature change.

In order to achieve the above object, according to one aspect of the present invention, a self-adhesive protective film is provided, which includes a substrate layer and an adhesive layer on the substrate layer, and the material of the adhesive layer includes, by weight, 50 to 90% of a component a and 10 to 50% of a component B, where the component a is an SEBS thermoplastic elastomer, and the component B is one or more of a first random polypropylene, a first low density polyethylene, and a TPO thermoplastic elastomer.

Further, the material of the adhesion layer comprises, by weight, 60-90% of the component A and 10-40% of the component B.

Furthermore, the density of the SEBS thermoplastic elastomer is 0.88-0.95 g/cm³The melt index is 5-50 g/10 min; preferably, the density of the first random polypropylene is 0.90-0.92 g/cm³The melt index is 3-30 g/10 min; preferably, the density of the first low-density polyethylene is 0.915-0.960 g/cm³The melt index is 3-30 g/10 min; preferably, the density of the TPO thermoplastic elastomer is 0.83 to 0.95g/cm³The melt index is 3-30 g/10 min.

Further, the substrate layer comprises a surface layer and a core layer, and the core layer is located between the surface layer and the adhesion layer.

Further, the material of the surface layer comprises 20-90 parts by weight of a first ethylene-propylene block copolymer and 10-80 parts by weight of a second low-density polyethylene; preferably, the material of the surface layer comprises 20 to 40 parts by weight of the first ethylene-propylene block copolymer and 60 to 80 parts by weight of the second low density polyethylene.

Further, the first ethylene-propylene block copolymer has a density of 0.90 to 0.91g/cm³The melt index is 3-30 g/10 min; preference is given toThe density of the second low-density polyethylene is 0.915-0.930 g/cm³The melt index is 3-30 g/10 min.

Further, the surface layer material also comprises 2-6 parts of anti-sticking particles in parts by weight; preferably, the particle size of the anti-sticking particles is 5-10 μm; preferably, the anti-adhesive particles are one or more of silica particles, silicone particles, amide particles.

Further, the material of the core layer comprises 50-90 parts by weight of a second ethylene-propylene block copolymer and 10-50 parts by weight of a second random polypropylene; preferably, the material of the core layer comprises 60-80 parts of the second ethylene-propylene block copolymer and 20-40 parts of the second random polypropylene.

Further, the density of the second ethylene-propylene block copolymer is 0.90-0.91 g/cm³The relative molecular weight is 50000-300000, and the melt index is 3-30 g/10 min; preferably, the density of the second random polypropylene is 0.90-0.91 g/cm³The relative molecular weight is 30000-200000, and the melt index is 3-30 g/10 min.

Further, the thickness of the surface layer is 4-8 μm; the thickness of the core layer is preferably 24-32 mu m; the thickness of the adhesive layer is preferably 4 to 8 μm.

The technical scheme of the invention is applied to provide a self-adhesive protective film which comprises a base material layer and an adhesive layer positioned on the base material layer, wherein the material of the adhesive layer comprises 50-90% of a component A and 10-50% of a component B in percentage by weight, wherein the component A is an SEBS thermoplastic elastomer, and the component B is one or more of a first random polypropylene, a first low-density polyethylene and a TPO thermoplastic elastomer. The protective film has good adhesiveness and peelability, the adhesive force changes little with temperature and time, the parent roll unwinding force changes little with time and temperature, and the parent roll unwinding force is easy to unwind. In addition, the self-adhesive protective film provided by the invention also has the advantages of low crystal point and high cleanliness, and is very suitable for being used as a surface protective film of a diffusion film.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

As described in the background section, the prior art self-adhesive protective films have unstable adhesion and excessively high unwinding force under long-term storage and temperature change conditions.

In order to solve the problem, the invention provides a self-adhesive protective film which comprises a base material layer and an adhesive layer positioned on the base material layer, wherein the material of the adhesive layer comprises 50-90% of a component A and 10-50% of a component B in percentage by weight, wherein the component A is an SEBS thermoplastic elastomer, and the component B is one or more of first random polypropylene, first low-density polyethylene and TPO thermoplastic elastomer.

The self-adhesive protective film provided by the invention comprises a base material layer and an adhesive layer positioned on the base material layer. The adhesion layer ensures the adhesion characteristic of the protective film, and the base material layer provides mechanical property for the protective film. Specifically, in the adhesive layer, the component A is an SEBS thermoplastic elastomer which has good temperature resistance, plasticity and high elasticity; the component B is one or more of first random polypropylene, first low-density polyethylene and TPO thermoplastic elastomer, and the three polymers have good flexibility, high transparency and self-cleaning property. The adhesive layer formed by the two components according to the dosage relationship can obviously improve the adhesive property of the self-adhesive protective film, so that the self-adhesive protective film has better adhesive property and stripping property, the change of the adhesive force along with temperature and time is smaller, the change of the unwinding force of the mother roll along with time and temperature is also small, and the mother roll is easy to unwind. In addition, the self-adhesive protective film provided by the invention also has the advantages of low crystal point and high cleanliness, and is very suitable for being used as a surface protective film of a diffusion film.

In a preferred embodiment, the material of the adhesion layer comprises 60-90% of component A and 10-40% of component B by weight percentage. The dosage relationship between the two components is controlled within the range, so that the performance of each component can be further integrated, the self-adhesive protective film has better adhesive performance, and the performance of other aspects such as transparency and the like is more balanced.

As mentioned before, onlyThe adhesive property of the protective film can be effectively improved by adopting the materials in the adhesive layer. In a preferred embodiment, the density of the SEBS thermoplastic elastomer is 0.88-0.950 g/cm³The melt index is 5 to 50g/10 min. The SEBS thermoplastic elastomer has more excellent temperature resistance, better plasticity and high elasticity, and can further improve the adhesive force stability and the easy unwinding performance of the protective film as the component A. Preferably, the density of the first random polypropylene is 0.90-0.92 g/cm³The melt index is 3-30 g/10 min. The random polypropylene has better flexibility and transparency, and the resin has higher cleanliness, which is beneficial to further improving the adhesive property, transparency and self-cleaning property of the protective film. Preferably, the density of the first low-density polyethylene is 0.915-0.960 g/cm³The melt index is 3-30 g/10 min. The low-density polyethylene is softer in property, has good extensibility, chemical stability and processability, and can further improve the uncoiling property, the chemical stability and the processability of the protective film when being used as an adhesive layer component. More preferably, the first low density polyethylene has a relative molecular weight of 10000 to 100000. Preferably, the density of the TPO thermoplastic elastomer is 0.83 to 0.95g/cm³The melt index is 3-30 g/10 min. The TPO thermoplastic elastomer has narrow molecular weight distribution, low crystallinity, excellent transparency and glossiness and good compatibility with other resins.

In the self-adhesive protective film, the base material layer serves to provide mechanical properties for the protective film. In a preferred embodiment, the substrate layer comprises a skin layer and a core layer, and the core layer is located between the skin layer and the adhesive layer. The surface layer and the core layer are jointly used as the base material layer, so that the surface layer can provide better film-forming performance besides better mechanical property.

In the above substrate layer, the materials of the surface layer and the core layer may be those commonly used for the protective film substrate layer. In a preferred embodiment, the material of the surface layer comprises 20 to 90 parts by weight of the first ethylene-propylene block copolymer and 10 to 80 parts by weight of the second low density polyethylene. The surface layer formed by the material has better mechanical property, and the strength, the hardness and the elasticity are better. Preferably, the material of the surface layer comprises 20 to 40 parts by weight of the first ethylene-propylene block copolymer and 60 to 80 parts by weight of the second low density polyethylene. The surface layer in the dosage relation has better mechanical property and film-forming property.

In a preferred embodiment, the first ethylene-propylene block copolymer has a density of 0.90 to 0.91g/cm³The melt index is 3-30 g/10 min. The performance of the segmented polypropylene in the aspects of strength, hardness and elasticity is more comprehensive. Preferably, the density of the second low-density polyethylene is 0.915-0.930 g/cm³The melt index is 3-30 g/10 min. The surface layer formed by matching the low-density polyethylene and the block polypropylene can provide better mechanical property and film-forming property, and meanwhile, the cleaning property of the surface layer is better.

In addition to the first block polypropylene and the second low density polyethylene, in order to further improve the release properties of the skin layer, in a preferred embodiment, the material of the skin layer further comprises 2 to 6 parts by weight of release particles. The addition of the anti-sticking particles in the amount can further improve the anti-sticking property of the surface layer and ensure that the surface layer and the whole protective film keep higher transparency and low crystallinity. Preferably, the particle size of the anti-sticking particles is 5-10 μm; preferably, the anti-adhesive particles include, but are not limited to, one or more of silica particles, silicone particles, amide particles.

The material of the core layer can also adopt the common material in the protective film base material layer. In a preferred embodiment, the material of the core layer comprises 50 to 90 parts by weight of the second ethylene-propylene block copolymer and 10 to 50 parts by weight of the second random polypropylene. The ethylene-propylene block copolymer has better mechanical property, the strength, hardness and elasticity of the ethylene-propylene block copolymer are better, the random polypropylene has high strength, toughness, better hardness and better extensibility, and the core layer formed by the two materials under the dosage relationship has better mechanical property in all aspects. More preferably, the material of the core layer comprises 60-80 parts of the second ethylene-propylene block copolymer and 20-40% of the second random polypropylene.

In a preferred embodimentIn an embodiment, the second ethylene-propylene block copolymer has a density of 0.90 to 0.91g/cm³The molecular weight is 50000-300000, and the melt index is 3-30 g/10 min. The performance of the block polypropylene of the type in strength, hardness and elasticity is more balanced. Preferably, the density of the second random polypropylene is 0.90-0.91 g/cm³The relative molecular weight is 30000-200000, and the melt index is 3-30 g/10 min. This type of random polypropylene is stronger and tougher, and is harder and slightly elongatable than low density polyethylene. The core layer formed by adopting the materials has better mechanical property.

The thickness of each layer can be adjusted, and preferably, the thickness of the surface layer accounts for 10-20% of the whole thickness, the thickness of the core layer accounts for 60-80% of the whole thickness, and the thickness of the adhesive layer accounts for 10-20% of the whole thickness. The protective film has comprehensive mechanical property, adhesive property, transparency and other aspects under the proportional relation. In a preferred embodiment, the thickness of the surface layer is 4 to 8 μm; the thickness of the core layer is preferably 24-32 mu m; the thickness of the adhesive layer is preferably 4 to 8 μm. By setting the thickness of each layer in this way, various performance indexes of the protective film can be further balanced.

In a word, the self-adhesive protective film provided by the invention has the characteristics of small uncoiling force, good temperature resistance, easiness in tearing and pasting, no residual glue and the like. The adhesive force of the bonding diffusion film at normal temperature is 5-30 gf/25mm, and the bonding diffusion film is rolled and stored in natural environment, the adhesive force is 5-30 gf/25mm, and the adhesive force is slightly changed along with the environment.

The self-adhesive protective film of the invention can be manufactured by using the conventional manufacturing method in the field, such as: the production process is characterized in that a three-layer co-extrusion casting process is applied to a dust-free workshop, a supercritical nitrogen fluid conveying system is adopted, the generation of crystal points is reduced from the source, and meanwhile, a defect detector, a beta ray thickness tester and other equipment are applied to carry out online tracking detection on the appearance defects and the thickness of the film in the production process, so that the film has the excellent characteristics of uniform thickness, high cleanliness, no impurities, smooth appearance, low crystal points and the like.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.

The performance test method for the protective film is as follows:

(1) thickness measurement

A Mark thickness gauge is adopted, and the reference standard is GB/T6672.

(2) Tensile Strength and elongation at Break test

The United states Meits MTS tensile tester was used, with reference to GB/T1040.3.

(3) Peel force test (adhesion)

A Kejian instrument tensile testing machine is adopted, and the reference standard is GB/T2792.

(4) Light transmittance and haze test

An AT-4725 transmission fog projector of BYK chemical company in Germany is adopted, and the reference standard is GB/T2410.

(5) Unwind force test

A tensile testing machine of a Kejian instrument is adopted.

The production process flow of the protective film in the following embodiments is as follows: and (3) heating and casting the layers according to the proportion of the components: extruding by an extruder, casting by a T-shaped opening die, air knife, casting roller, cooling roller, beta-ray thickness gauge, waste edge cutting, defect detector and coiling.

In the melt casting process, the temperature of a machine head in the T-shaped die casting process is 230 ℃; the surface of the casting roller is subjected to fine machining, the rotating speed is stable, and the temperature of the casting roller is controlled at 25 ℃; the temperature of the cooling roller is controlled at 30 ℃; an air knife device is arranged above the casting roller, a vacuum box device is arranged below the die head, the blowing pressure power of the air knife is controlled to be 40 percent, and the vacuum suction power is controlled to be 20 percent; simultaneously controlling the suction power of the die head to be 60%; after the film passes through the cooling roller, the gap of the T-shaped die is automatically regulated and controlled by a beta-ray thickness gauge, and the average error of the thickness of the casting film is controlled within 2 percent. And simultaneously, the winding tension is adjusted according to the thickness, the production speed and the like of the film, and the winding tension is controlled to be 100N.

Example 1

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and random polypropylene according to the weight ratio of 90/10. Wherein the random polymerization is carried outThe density of propylene was 0.90g/cm³The melt index was 6.0g/10 min. The density of the SEBS thermoplastic elastomer is 0.90g/cm³The melt index was 8.0g/10 min.

The core layer is formed by compounding block polypropylene and random polypropylene according to the weight ratio of 70/30. The density of the block polypropylene is 0.90g/cm³The melt index was 5.0g/10 min. The density of the random polypropylene is 0.905g/cm³The melt index was 7.0g/10 min.

The surface layer is formed by compounding low-density polyethylene, block polypropylene and anti-sticking master batches according to the weight ratio of 20/75/5. The low density polyethylene has a density of 0.921g/cm³The melt index was 6.0g/10 min. The density of the block polypropylene is 0.90g/cm³The melt index was 5.0g/10 min. The anti-sticking master batch is artificially synthesized silicon dioxide particles with the density of 0.910g/cm³The melt index was 12.0g/10min, and the particle size was 5 μm.

The physical properties of the obtained protective film were measured as shown in table 1 (it should be noted that the thicknesses are the total thickness of each layer, and the thicknesses of each layer of the surface layer, the core layer, and the adhesive layer, which are the same below):

TABLE 1

Example 2

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and low-density polyethylene according to the weight ratio of 60/40. Wherein the density of the SEBS thermoplastic elastomer is 0.89g/cm³The melt index was 5.0g/10 min. The density of the low density polyethylene is 0.922g/cm³The melt index ranged from 4.0g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 2:

TABLE 2

Example 3

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and TPO thermoplastic elastomer according to the weight ratio of 75/25. Wherein the TPO thermoplastic elastomer has a density of 0.89g/cm³The melt index was 7.0g/10 min. The density of the SEBS thermoplastic elastomer is 0.92g/cm³The melt index was 5.0g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 3:

TABLE 3

Example 4

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and random polypropylene according to the weight ratio of 90/10. Wherein the density of the random polypropylene is 0.92g/cm³The melt index was 30.0g/10 min. The density of the SEBS thermoplastic elastomer is 0.95g/cm³The melt index was 5.0g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 4:

TABLE 4

Example 5

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and random polypropylene according to the weight ratio of 60/40. Wherein the random polypropylene has a density of 0.90g/cm³The melt index was 3.0g/10 min. The density of the SEBS thermoplastic elastomer is 0.88g/cm³The melt index was 50.0g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 5:

TABLE 5

Example 6

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and random polypropylene according to the weight ratio of 50/50. Wherein the density of the random polypropylene is 0.88g/cm³The melt index was 32.0g/10 min. The density of the SEBS thermoplastic elastomer is 0.87g/cm³The melt index was 4.0g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 6:

TABLE 6

Example 7

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and low-density polyethylene according to the weight ratio of 90/10. Wherein the density of the SEBS thermoplastic elastomer is 0.88g/cm³The melt index was 5.0g/10 min. Of low density polyethyleneThe density is 0.915g/cm³The melt index ranged from 30g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 7:

TABLE 7

Example 8

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and low-density polyethylene according to the weight ratio of 50/50. Wherein the density of the SEBS thermoplastic elastomer is 0.95g/cm³The melt index was 50.0g/10 min. The low density polyethylene has a density of 0.96g/cm³The melt index ranged from 3g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 8:

TABLE 8

Example 9

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and low-density polyethylene according to the weight ratio of 50/50. Wherein the density of the SEBS thermoplastic elastomer is 0.87g/cm³The melt index was 4.0g/10 min. The density of the low density polyethylene is 0.90g/cm³The melt index ranged from 32g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 9:

TABLE 9

Example 10

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and TPO thermoplastic elastomer according to the weight ratio of 60/40. Wherein the TPO thermoplastic elastomer has a density of 0.95g/cm³The melt index was 3g/10 min. The density of the SEBS thermoplastic elastomer is 0.88g/cm³The melt index was 5.0g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 10:

watch 10

Example 11

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and TPO thermoplastic elastomer according to the weight ratio of 50/50. Wherein the TPO thermoplastic elastomer has a density of 0.83g/cm³The melt index was 10g/10 min. The density of the SEBS thermoplastic elastomer is 0.95g/cm³The melt index was 8.0g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 11:

TABLE 11

Example 12

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and TPO thermoplastic elastomer according to the weight ratio of 50/50. Wherein the TPO thermoplastic elastomer has a density of 0.80g/cm³The melt index was 11g/10 min. The density of the SEBS thermoplastic elastomer is 0.96g/cm³The melt index was 4.0g/10 min.

The core layer material was the same as in example 1;

the skin material was the same as in example 1;

the physical properties of the obtained protective film were measured as shown in Table 12:

TABLE 12

Example 13

The material of the adhesive layer was the same as in example 1;

the core layer is formed by compounding block polypropylene and random polypropylene according to the weight ratio of 60/40. The density of the block polypropylene is 0.91g/cm³The melt index was 3g/10 min. The density of the random polypropylene is 0.90g/cm³The melt index was 30g/10 min.

The surface layer is formed by compounding low-density polyethylene, ethylene-propylene block copolymer and anti-sticking master batch according to the weight ratio of 34/60/6. The density of the low density polyethylene is 0.915g/cm³The melt index was 30g/10 min. The density of the ethylene-propylene block copolymer was 0.91g/cm³The melt index was 10g/10 min. The density of the artificial synthetic silicon dioxide of the anti-sticking master batch is 0.910g/cm³The melt index was 12.0g/10min, and the particle size was 10 μm.

The physical properties of the obtained protective film were measured as shown in Table 13:

watch 13

Example 14

The material of the adhesive layer was the same as in example 1;

the core layer is formed by compounding block polypropylene and random polypropylene according to the weight ratio of 80/20. The density of the block polypropylene is 0.90g/cm³The melt index was 30g/10 min. The density of the random polypropylene is 0.91g/cm³The melt index was 3g/10 min.

The surface layer is formed by compounding low-density polyethylene, block polypropylene and anti-sticking master batches according to the weight ratio of 40/58/2. The density of the low density polyethylene is 0.930g/cm³The melt index was 3g/10 min. The density of the block polypropylene is 0.90g/cm³The melt index was 3g/10 min. The density of the artificial synthetic silicon dioxide of the anti-sticking master batch is 0.910g/cm³The melt index was 12.0g/10min, and the particle size was 10 μm.

The physical properties of the obtained protective film were measured as shown in Table 14:

TABLE 14

Example 15

The material of the adhesive layer was the same as in example 1;

the core layer is formed by compounding block polypropylene and random polypropylene according to the weight ratio of 90/10. The density of the block polypropylene is 0.89g/cm³The melt index was 11g/10 min. The density of the random polypropylene is 0.89g/cm³The melt index was 2g/10 min.

The surface layer is composed ofThe density polyethylene and the block polypropylene are compounded according to the weight ratio of 90/10. The density of the low density polyethylene is 0.90g/cm³The melt index was 2g/10 min. The density of the block polypropylene is 0.92g/cm³The melt index was 11g/10 min.

The physical properties of the obtained protective film were measured as shown in Table 15:

watch 15

Comparative example 1

The adhesion layer is formed by compounding SEBS thermoplastic elastomer and random polypropylene according to the weight ratio of 40/60. Wherein the density of the random polypropylene is 0.90g/cm³The melt index was 6.0g/10 min. The density of the SEBS thermoplastic elastomer is 0.90g/cm³The melt index was 8.0g/10 min.

The core layer is formed by compounding block polypropylene and random polypropylene according to the weight ratio of 40/60. The density of the block polypropylene is 0.90g/cm³The melt index was 5.0g/10 min. The density of the random polypropylene is 0.905g/cm³The melt index was 7.0g/10 min.

The surface layer is formed by compounding low-density polyethylene and block polypropylene according to the weight ratio of 40/60. The low density polyethylene has a density of 0.921g/cm³The melt index was 6.0g/10 min. The density of the block polypropylene is 0.90g/cm³The melt index was 5.0g/10 min.

The physical properties of the obtained protective film were measured as shown in Table 16:

TABLE 16

From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:

the self-adhesive protective films provided in embodiments 1 to 15 of the present invention have good adhesion, low unwinding force, good mechanical properties, good transparency, low haze, and high cleaning performance. Particularly, after the properties such as the component ratio, the material density, the melt index and the like of each layer are optimized, the adhesive force of the protective film at normal temperature is more suitable, the adhesive force is 5-35 gf/25mm, and the adhesive force changes little after 3d and 7d, which shows that the adhesive force stability is better; the uncoiling force of the protective film is small and is 45-95 gf/25mm, and the comprehensive performance is better.

In conclusion, the self-adhesive protective film provided by the invention has good adhesiveness and stripping property, the change of the adhesive force along with temperature and time is small, the change of the unwinding force of the parent roll along with time and temperature is small, and the parent roll is easy to unwind. In addition, the self-adhesive protective film provided by the invention also has the advantages of low crystal point and high cleanliness, and is very suitable for being used as a surface protective film of a diffusion film.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The self-adhesive protective film is characterized by comprising a base material layer and an adhesive layer positioned on the base material layer, wherein the material of the adhesive layer comprises 50-90 wt% of a component A and 10-50 wt% of a component B, wherein the component A is an SEBS thermoplastic elastomer, the component B is a first random polypropylene or TPO thermoplastic elastomer, or the component B is two or three of the first random polypropylene, the first low-density polyethylene and the TPO thermoplastic elastomer; the substrate layer comprises a surface layer and a core layer, and the core layer is positioned between the surface layer and the adhesion layer; the material of the surface layer comprises, by weight, 20-90 parts of a first ethylene-propylene block copolymer and 10-80 parts of a second low-density polyethylene; the core layer is made of 50-90 parts by weight of a second ethylene-propylene block copolymer and 10-50 parts by weight of a second random polypropylene;

the density of the first random polypropylene is 0.90-0.92 g/cm³The melt index is 3-30 g/10 min;

the TPO thermoplastic elastomer has a density of 0.83 to 0.95g/cm³The melt index is 3-30 g/10 min;

the first ethylene-propylene block copolymer has a density of 0.90 to 0.91g/cm³The melt index is 3-30 g/10 min; the density of the second low-density polyethylene is 0.915-0.930 g/cm³The melt index is 3-30 g/10 min;

the density of the second ethylene-propylene block copolymer is 0.90-0.91 g/cm³The relative molecular weight is 50000-300000, and the melt index is 3-30 g/10 min; the density of the second random polypropylene is 0.90-0.91 g/cm³The molecular weight is 30000-200000, and the melt index is 3-30 g/10 min.

2. The self-adhesive protective film according to claim 1, wherein the material of the adhesive layer comprises 60-90% of component A and 10-40% of component B by weight percentage.

3. The self-adhesive protective film according to claim 1 or 2, wherein the density of the SEBS thermoplastic elastomer is 0.88-0.95 g/cm³The melt index is 5 to 50g/10 min.

4. The self-adhesive protective film according to claim 1 or 2, wherein the density of the first low-density polyethylene is 0.915-0.960 g/cm³The melt index is 3-30 g/10 min.

5. The self-adhesive protective film according to claim 1, wherein the material of the surface layer comprises 20 to 40 parts by weight of the first ethylene-propylene block copolymer and 60 to 80 parts by weight of the second low-density polyethylene.

6. The self-adhesive protective film according to claim 1, wherein the material of the surface layer further comprises 2-6 parts by weight of release particles.

7. The self-adhesive protective film according to claim 6, wherein the particle size of the release particles is 5 to 10 μm.

8. The self-adhesive protective film according to claim 6, wherein the release particles are one or more of silica particles, silicone particles, amide particles.

9. The self-adhesive protective film according to claim 1, wherein the material of the core layer comprises 60 to 80 parts of the second ethylene-propylene block copolymer and 20 to 40 parts of the second random polypropylene.

10. The self-adhesive protective film according to claim 1, wherein the thickness of the surface layer is 4 to 8 μm.

11. The self-adhesive protective film according to claim 1, wherein the core layer has a thickness of 24 to 32 μm.

12. The self-adhesive protective film according to claim 1, wherein the thickness of the adhesive layer is 4 to 8 μm.