WO2021213113A1

WO2021213113A1 - Self-repairing tpu protective film for 3d curved screen and preparation method therefor

Info

Publication number: WO2021213113A1
Application number: PCT/CN2021/082268
Authority: WO
Inventors: 薛萌; 丁敬德; 庄永剑; 朱丽萍
Original assignee: 广东邦固薄膜涂料创新研究院有限公司
Priority date: 2020-04-23
Filing date: 2021-03-23
Publication date: 2021-10-28
Also published as: CN111363488A

Abstract

A self-repairing TPU protective film for a 3D curved screen, comprising a release film A, an optical-grade self-repairing coating layer, an optical-grade hard TPU resin film layer, an optical-grade high-viscosity acrylic pressure-sensitive adhesive layer, and a release film B attached from top to bottom. The optical-grade self-repairing coating layer is formed by coating an optical-grade self-repairing coating, and the composition of the optical-grade self-repairing coating comprises 100 parts by weight of a self-repairing resin, 60 to 150 parts by weight of a first solvent, 1 to 10 parts by weight of a slip assistant, and 30 to 100 parts by weight of a first curing agent. The self-repairing TPU protective film for a 3D curved screen has good conformability to a curved screen, has no warping, has a smooth surface, and is foldable and scratch resistant.

Description

Self-repairing TPU protective film for 3D curved screen and preparation method thereof

Technical field

This application relates to the technical field of screen protective films, and in particular to a self-repairing TPU protective film for 3D curved screens and a preparation method thereof.

Background technique

Existing smart phones have entered the era of curved screens and folding screens from straight touch screens. Touch screens have strict requirements for screen shatter resistance and scratch resistance. When the screen becomes a curved screen or a folding screen, the performance of the screen protector is Also put forward higher requirements.

The curvature of the 3D curved screen is getting larger and larger, and the traditional PET, PC, TAC, PMMA base film and the composite film with TPU cannot be attached to the 3D curved screen. Only pure TPU film can be bent arbitrarily on the curved screen without bursting, but when the TPU base film is used alone, it is not resistant to scratches. Moreover, most of the current TPU films on the market are made by the casting method. For example, the screen protector mentioned in the patent CN110202901A uses a commercially available TPU base film. The TPU film formed by this method is flat and transparent. The rate is lacking, and the base film is soft, and the smoothness of the surface coating in the later stage is difficult to control.

Moreover, the surface of the 3D curved screen is generally treated with anti-fingerprints, and the water contact angle reaches 110-120°. The surface energy of the 3D curved screen after anti-fingerprint treatment is lower. The traditional protective film uses silicone pressure sensitive adhesive or acrylic Pressure-sensitive adhesives have relatively low adhesion. It is difficult for ordinary pressure-sensitive adhesives to automatically drain bubbles on the screen, and it is difficult to stick firmly to the screen. After being attached to the mobile phone screen, the curved surface is likely to rebound and warp. For example, the curved screen protective film mentioned in patent CN108116020A uses silicone pressure sensitive adhesive.

In addition, as the functions of smart phones now become more powerful, people run large-scale games on their phones to achieve fingerprint recognition, under-screen unlocking and other functions. The surface of the phone’s protective film needs to be smooth, scratch-resistant, wear-resistant, and fingerprint-resistant. In the era of flat screens, it is a common practice to use UV curing coatings for the surface hardening treatment of the protective film, but on 3D curved screens, the UV hardening coating on the protective film is easy to burst. A better solution is to do self-repairing coating.层处理。 Layer processing.

To this end, we propose a 3D curved screen self-repairing TPU protective film and its preparation method.

Application content

The main purpose of this application is to provide a self-repairing TPU protective film for a 3D curved screen and a preparation method thereof, which has the advantages of good fit of the curved screen, no warping, smooth surface, foldable and scratch-resistant. Moreover, the structure is simple, the manufacturing cost is low, and the TPU protective film suitable for 3D curved screens and with good protection effect can be quickly prepared.

In order to achieve the above purpose, the present application provides a self-healing TPU protective film for 3D curved screens, which includes a top-to-bottom release film A, an optical-grade self-healing coating, an optical-grade hard TPU resin film, and an optical Grade high-viscosity acrylic pressure-sensitive adhesive layer, release film B;

The optical-grade automatic repair coating is coated by an optical-grade self-healing paint, and the composition of the optical-grade self-healing paint includes: wherein the thickness of the optical-grade automatic repair coating ranges from 5 to 30 μm.

100 parts by weight of the self-healing resin, 60-150 parts by weight of the first solvent, 1-10 parts by weight of the slip aid, and 30-100 parts by weight of the first curing agent.

Preferably, the self-healing resin is one or more of polyhydroxy acrylate, polyhydroxy urethane acrylate, polyhydroxy silicon modified acrylate, and polyhydroxy fluorine modified acrylate; the first solvent is acetic acid One or more of ethyl ester, n-butyl acetate, toluene, propylene glycol methyl ether acetate, and methyl ethyl ketone; the slip aid is a fluorine-containing leveling agent, a silicon-containing leveling agent, and a fluorosilicone leveling agent One or more of them; the first curing agent is a dimer or trimer of hexamethylene diisocyanate.

Preferably, the release film A and the release film B are both silicone oil release films of PET base material, and the thickness of the release film A and the release film B are both in the range of 20-60 μm.

Preferably, the optical-grade hard TPU resin film layer is coated with optical-grade hard TPU glue, and the optical-grade hard TPU glue is made of polyisocyanate, polyester polyol and chain extender through the action of a catalyst. It is polymerized in the second solvent; the thickness of the optical-grade hard TPU resin film layer ranges from 50 to 200 μm.

Preferably, the polyisocyanate is one or more of hexamethylene diisocyanate or its polymer, isophorone diisocyanate or its polymer; the polyester polyol is a conventional polyester polyol One or more of alcohol, polycaprolactone polyol and polycarbonate diol; the chain extender is ethylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, One or more of methylolpropane; the catalyst is dibutyltin dilaurate; the second solvent is one of ethyl acetate, toluene, butanone, and N,N-dimethylformamide Or several.

Preferably, the optical-grade high-viscosity acrylic pressure-sensitive adhesive layer is coated with optical-grade high-viscosity acrylic pressure-sensitive adhesive, and the optical-grade high-viscosity acrylic pressure-sensitive adhesive is composed of 100 parts by weight of acrylic soft monomer, 10~ 30 parts by weight of hard acrylic monomer and 3-10 parts of hydroxy acrylic monomer are polymerized in the third solvent through the action of an initiator; the thickness of the optical-grade high-viscosity acrylic pressure-sensitive adhesive layer is in the range of 15-40 μm.

Preferably, the acrylic soft monomer is two or more of n-butyl acrylate, ethyl acrylate, isooctyl acrylate, lauryl acrylate, and lauryl methacrylate; the acrylic hard monomer is acrylic acid, Two or more of methacrylic acid, methyl methacrylate, vinyl acetate, acrylamide, isobornyl acrylate, and glycidyl methacrylate; the hydroxy acrylic monomer is hydroxy ethyl acrylate, hydroxy acrylate One or more of propyl ester, hydroxybutyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; the initiator is azobisisobutyronitrile, azobisisoheptonitrile, peroxide One or more of dibenzoyl and lauroyl peroxide; the third solvent is one or more of ethyl acetate, toluene, acetone, and cyclohexane.

Preferably, during the coating process, 0.1 to 2% of a second curing agent is added to the optical-grade high-viscosity acrylic pressure-sensitive adhesive, and the second curing agent is a dimer or tripolymer of hexamethylene diisocyanate. Aggregate.

Preferably, the light transmittance of the self-repairing TPU protective film of the 3D curved screen is greater than 90%, the haze is less than 1%, the water contact angle reaches 105° or more, and the dynamic friction coefficient is less than 0.2.

A preparation method of a self-repairing TPU protective film for a 3D curved screen includes the following steps:

(1) Coat optical grade hard TPU glue on PET release film C, dry and cure at 90-120℃ to form optical grade hard TPU resin film layer; coating by doctor blade or slit coating Way.

(2) Coat optical-grade high-viscosity acrylic pressure-sensitive adhesive on the optical-grade hard TPU resin film layer, and dry and cure at 80-120℃ to form an optical-grade high-viscosity acrylic pressure-sensitive adhesive layer. A layer of release film B is covered on the high-viscosity acrylic pressure-sensitive adhesive layer;

(3) Tear off the release film C, apply an optical-grade self-healing coating on the other side of the optical-grade hard TPU resin film layer, and dry and cure at a temperature of 80-110°C to form an optical-grade self-healing coating Then cover the release film A on the surface of the self-healing coating, rewind, and place it at 50-60°C after rewinding and curing for 48-72h to obtain a 3D curved screen self-repairing TPU protective film.

Compared with the prior art, this application has the following beneficial effects:

1. Using TPU material as the base film, it has good optical performance, no rainbow pattern, interference pattern. Moreover, in this application, the commercially available TPU resin film layer made by the casting method is not used, but the optical-grade hard TPU glue is synthesized first, and then the TPU base film is coated with a coater. The single-layer base film has a relatively simple structure, does not require a hot bending process, and has low preparation cost; and the thickness is adjustable, the hardness of the film material is adjustable, the surface flatness is high, the film material thickness is uniform, and flexibility and curved surface are taken into account. Screen fit.

2. One side of the protective film attached to the 3D curved screen is coated with optical-grade high-viscosity acrylic pressure-sensitive glue. Silicone pressure-sensitive glue is not used, which avoids the difficulty of direct coating of silica gel on the TPU base film. The fingerprint-treated 3D curved screen is stronger; and it does not use expensive fluorine release film and acrylic pressure-sensitive adhesive to bond, and the cost is low.

3. The surface of the protective film is coated with optical-grade self-healing paint, which solves the problem that the TPU base film is not scratch-resistant when used alone. It can quickly repair itself even with small scratches, and the self-healing paint has good flexibility Any bending. In addition, the slip additives added to the self-healing coating can make the outer surface of the protective film have good anti-fouling ability and anti-fingerprint performance. The water contact angle can reach 105° or more, and the dynamic friction coefficient is less than 0.2 to achieve better sliding. Operational touch.

4. The preparation method is simple and easy to implement, and can quickly produce 3D curved screen self-repairing TPU protective film products with good protection effect and good comprehensive performance, and high production efficiency.

Detailed ways

In order to make the technical means, creative features, goals and effects achieved by this application easy to understand, the application will be further elaborated below in conjunction with specific implementations.

Example 1

Optical-grade self-healing coating composition includes: 100 parts by weight of polyhydroxy acrylate, 60 parts by weight of ethyl acetate, 1 part by weight of fluorine-containing leveling agent, and 30 parts by weight of dimer of hexamethylene diisocyanate;

Optical grade hard TPU glue is made by mixing hexamethylene diisocyanate, polyester polyol and ethylene glycol at a molar ratio of 1:0.9:0.1 and polymerizing in toluene through the catalysis of dibutyltin dilaurate;

Optical grade high-viscosity acrylic pressure-sensitive adhesive is made by polymerizing 100 parts by weight of n-butyl acrylate, 10 parts by weight of acrylic acid, and 3 parts by weight of hydroxyethyl acrylate in acetone through the catalysis of azobisisobutyronitrile; adding 0.2 Parts by weight of the dimer of hexamethylene diisocyanate.

The preparation method of the 3D curved screen self-repairing TPU protective film is as follows:

Coat the optical grade hard TPU glue on the PET release film C with a thickness of 25μm, and dry and cure it at 90-120℃ to form an optical grade hard TPU resin film layer with a thickness of 50μm; The viscous acrylic pressure-sensitive adhesive is coated on the optical-grade hard TPU resin film layer, dried and cured at a temperature of 80-120 ℃ to form an optical-grade high-viscosity acrylic pressure-sensitive adhesive layer with a thickness of 25μm. The pressure-sensitive adhesive layer is covered with a release film B with a thickness of 25μm; the release film C is removed, and the optical-grade self-healing coating is coated on the other side of the optical-grade hard TPU resin film layer, at 80- After drying and curing at 110℃, an optical-grade self-repairing coating with a thickness of 25μm is formed, and then the surface of the self-repairing coating is covered with a release film A with a thickness of 25μm, rewinding, and then placed at 50℃ for curing 72h, get 3D curved screen self-repairing TPU protective film.

Example 2

Optical-grade self-healing coating composition includes: 100 parts by weight of polyhydroxyurethane acrylate, 150 parts by weight of n-butyl acetate, 10 parts by weight of silicon-containing leveling agent, 100 parts by weight of dimerization of hexamethylene diisocyanate body;

Optical grade hard TPU glue is mixed with isophorone diisocyanate, polycaprolactone polyol and 1,4-butanediol at a molar ratio of 1:0.8:0.2 and is catalyzed by dibutyltin dilaurate in N, Polymerized from N-dimethylformamide;

Optical grade high-viscosity acrylic pressure-sensitive adhesive is made by polymerizing 100 parts by weight of ethyl acrylate, 30 parts by weight of methacrylic acid, and 10 parts by weight of hydroxypropyl acrylate in cyclohexane through the catalytic action of azobisisoheptonitrile; 2 parts by weight of the dimer of hexamethylene diisocyanate was also added.

Coat the optical grade hard TPU glue on the PET release film C with a thickness of 25μm, and dry and cure it at 90-120℃ to form an optical grade hard TPU resin film layer with a thickness of 50μm; Adhesive acrylic pressure-sensitive adhesive is coated on the optical-grade hard TPU resin film layer, dried and cured at a temperature of 80-120 ℃ to form an optical-grade high-viscosity acrylic pressure-sensitive adhesive layer with a thickness of 30μm. In the optical-grade high-viscosity acrylic The pressure-sensitive adhesive layer is covered with a release film B with a thickness of 25μm; the release film C is removed, and the optical-grade self-healing coating is coated on the other side of the optical-grade hard TPU resin film layer, at 80- After drying and curing at 110℃, an optical-grade self-repairing coating with a thickness of 15μm is formed, and then the surface of the self-repairing coating is covered with a release film A with a thickness of 25μm, wound up, and then placed at 50℃ for curing 72h, get 3D curved screen self-repairing TPU protective film.

Example 3

Optical grade hard TPU glue is made by mixing hexamethylene diisocyanate, polyester polyol and ethylene glycol at a molar ratio of 1:0.85:0.15 and polymerizing in toluene through the catalysis of dibutyltin dilaurate;

Coat the optical-grade hard TPU glue on the PET release film C with a thickness of 50μm, dry and cure at 90-120℃ to form an optical-grade hard TPU resin film with a thickness of 200μm; Adhesive acrylic pressure-sensitive adhesive is coated on the optical-grade hard TPU resin film layer, dried and cured at a temperature of 80-120 ℃ to form an optical-grade high-viscosity acrylic pressure-sensitive adhesive layer with a thickness of 40μm. In the optical-grade high-viscosity acrylic The pressure-sensitive adhesive layer is covered with a release film B with a thickness of 50μm; the release film C is removed, and the optical-grade self-healing paint is coated on the other side of the optical-grade hard TPU resin film layer, at 80- After drying and curing at 110°C, an optical self-healing coating with a thickness of 30μm is formed, and then a release film A with a thickness of 50μm is covered on the surface of the self-healing coating, rewinding, and curing at 60°C after rewinding 48h, get 3D curved screen self-repairing TPU protective film.

Example 4

Optical grade self-healing coating composition includes: 100 parts by weight of polyhydroxy urethane acrylate, 150 parts by weight of n-butyl acetate, 10 parts by weight of silicon-containing leveling agent, 100 parts by weight of dimerization of hexamethylene diisocyanate body;

Optical grade hard TPU glue is mixed with isophorone diisocyanate, polycaprolactone polyol and 1,4-butanediol at a molar ratio of 1:0.92:0.08 and is catalyzed by dibutyltin dilaurate in N, Polymerized from N-dimethylformamide;

Optical grade high-viscosity acrylic pressure-sensitive adhesive is made by polymerizing 100 parts by weight of ethyl acrylate, 30 parts by weight of methacrylic acid, and 10 parts by weight of hydroxypropyl acrylate in cyclohexane through the catalytic action of azobisisoheptonitrile; 2 parts by weight of trimer of hexamethylene diisocyanate was also added.

Coat the optical-grade hard TPU glue on the PET release film C with a thickness of 38μm, dry and cure at 90-120℃ to form an optical-grade hard TPU resin film with a thickness of 200μm; The viscous acrylic pressure-sensitive adhesive is coated on the optical-grade hard TPU resin film layer, dried and cured at a temperature of 80-120 ℃ to form an optical-grade high-viscosity acrylic pressure-sensitive adhesive layer with a thickness of 35μm. In the optical-grade high-viscosity acrylic The pressure-sensitive adhesive layer is covered with a release film B with a thickness of 38μm; the release film C is removed, and the optical-grade self-healing paint is coated on the other side of the optical-grade hard TPU resin film layer, at 80- After drying and curing at 110℃, an optical-grade self-repairing coating with a thickness of 30μm is formed, and then a release film A with a thickness of 38μm is covered on the surface of the self-repairing coating, rewinding, and curing at 60℃ after rewinding 48h, get 3D curved screen self-repairing TPU protective film.

The performance test of the 3D curved screen self-repairing TPU protective film prepared in Examples 1 to 4 is performed below. The optical performance test results of Examples 1 to 4 are shown in Table 1:

Table 1

Combined with the optical performance test results in Examples 1 to 4, it can be seen from Table 1 that the self-repairing TPU protective film for 3D curved screens obtained in Examples 1 to 4 has a light transmittance of more than 90%, a haze of less than 1%, and a water contact angle of 105 Above °, the coefficient of dynamic friction is less than 0.2, which increases the touch of sliding operation.

The above shows and describes the basic principles and main features of the application and the advantages of the application. Those skilled in the industry should understand that this application is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principles of this application. Without departing from the spirit and scope of this application, this application will also have Various changes and improvements, these changes and improvements all fall within the scope of the claimed application. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

A self-repairing TPU protective film for 3D curved screens, which is characterized in that it includes a top-down laminated release film A, an optical-grade self-repairing coating, an optical-grade hard TPU resin film layer, and an optical-grade high-viscosity acrylic pressure Sensitive adhesive layer, release film B;

The optical-grade self-healing coating is coated by optical-grade self-healing paint, and the composition of the optical-grade self-healing paint includes:

100 parts by weight of the self-healing resin, 60-150 parts by weight of the first solvent, 1-10 parts by weight of the slip aid, and 30-100 parts by weight of the first curing agent.
The 3D curved screen self-healing TPU protective film according to claim 1, wherein the self-healing resin is polyhydroxy acrylate, polyhydroxy urethane acrylate, polyhydroxy silicon modified acrylate, polyhydroxy fluorine modified One or more of acrylate; the first solvent is one or more of ethyl acetate, n-butyl acetate, toluene, propylene glycol methyl ether acetate, and methyl ethyl ketone; the slip aid is One or more of a fluorine-containing leveling agent, a silicon-containing leveling agent, and a fluorosilicone leveling agent; the first curing agent is a dimer or trimer of hexamethylene diisocyanate.
The 3D curved screen self-healing TPU protective film according to claim 1, wherein the release film A and the release film B are both silicone oil release films of PET substrate, and the release film A and the release film The thickness of the film B is in the range of 20 to 60 μm.
The 3D curved screen self-repairing TPU protective film according to claim 1, wherein the optical-grade hard TPU resin film layer is coated with optical-grade hard TPU glue, and the optical-grade hard TPU The glue is formed by polymerizing polyisocyanate, polyester polyol and chain extender in a second solvent through the action of a catalyst; the thickness of the optical-grade hard TPU resin film layer ranges from 50 to 200 μm.
The 3D curved screen self-healing TPU protective film according to claim 4, wherein the polyisocyanate is hexamethylene diisocyanate or its polymer, isophorone diisocyanate or its polymer One or more; the polyester polyol is one or more of conventional polyester polyol, polycaprolactone polyol and polycarbonate diol; the chain extender is ethylene glycol, 1, One or more of 4-butanediol, 1,6-hexanediol, glycerin, and trimethylolpropane; the catalyst is dibutyltin dilaurate; the second solvent is ethyl acetate, toluene One or more of, butanone, N,N-dimethylformamide.
The 3D curved screen self-healing TPU protective film according to claim 1, wherein the optical-grade high-viscosity acrylic pressure-sensitive adhesive layer is coated with optical-grade high-viscosity acrylic pressure-sensitive adhesive. The high-viscosity acrylic pressure-sensitive adhesive is polymerized by 100 parts by weight of soft acrylic monomer, 10-30 parts by weight of hard acrylic monomer, and 3-10 parts of hydroxy acrylic monomer in a third solvent through the action of an initiator; The thickness of the high-viscosity acrylic pressure-sensitive adhesive layer ranges from 15 to 40 μm.
The 3D curved screen self-healing TPU protective film according to claim 6, wherein the acrylic soft monomer is n-butyl acrylate, ethyl acrylate, isooctyl acrylate, lauryl acrylate, lauryl methacrylate Two or more of the acrylic acid hard monomers are acrylic acid, methacrylic acid, methyl methacrylate, vinyl acetate, acrylamide, isobornyl acrylate, and glycidyl methacrylate. Several; the hydroxy acrylic monomer is one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; the initiator It is one or more of azobisisobutyronitrile, azobisisoheptonitrile, dibenzoyl peroxide, and lauroyl peroxide; the third solvent is ethyl acetate, toluene, acetone, and cyclohexane One or more of alkanes.
The 3D curved screen self-healing TPU protective film according to claim 1, characterized in that, in the coating process, 0.1-2% of the second curing agent is added to the optical-grade high-viscosity acrylic pressure-sensitive adhesive water, and the The second curing agent is a dimer or trimer of hexamethylene diisocyanate.
The 3D curved screen self-healing TPU protective film according to claim 1, wherein the light transmittance of the 3D curved screen self-healing TPU protective film is greater than 90%, the haze is less than 1%, and the water contact angle reaches 105° Above, the dynamic friction coefficient is less than 0.2.
A method for preparing a self-repairing TPU protective film for a 3D curved screen, which is characterized in that it comprises the following steps:

(1) Coat the optical grade hard TPU glue on the PET release film C, dry and cure at 90-120℃ to form an optical grade hard TPU resin film layer;

(2) Coat optical-grade high-viscosity acrylic pressure-sensitive adhesive on the optical-grade hard TPU resin film layer, and dry and cure at 80-120℃ to form an optical-grade high-viscosity acrylic pressure-sensitive adhesive layer. A layer of release film B is covered on the high-viscosity acrylic pressure-sensitive adhesive layer;

(3) Tear off the release film C, apply an optical-grade self-healing coating on the other side of the optical-grade hard TPU resin film layer, and dry and cure at a temperature of 80-110°C to form an optical-grade self-healing coating Then cover the release film A on the surface of the self-healing coating, rewind, and place it at 50-60°C after rewinding and curing for 48-72h to obtain a 3D curved screen self-repairing TPU protective film.