阅读说明：本技术 一种耐紫外湿热老化的透明pi硬化膜用预涂液及其应用 (Ultraviolet-damp-heat-aging-resistant pre-coating liquid for transparent PI (polyimide) hardened film and application thereof ) 是由 张毓浩 于 2019-09-27 设计创作，主要内容包括：本发明属于透明聚酰亚胺硬化膜用预涂液技术领域,具体涉及一种耐紫外湿热老化的透明PI硬化膜用预涂液及其应用,所述预涂液由如下重量份的各组分组成：低分子量树脂100份、强极性单体50-100份、热引发剂1-5份、流平剂0.05-1份、溶剂1000-1500份。本发明的预涂液中含有适量的低分子量树脂和强极性单体,二者相互配合,可以使预涂液渗入透明PI基材中,与透明PI基材穿插渗透咬蚀,经固化交联,预涂层牢牢附着在基材表面,提高硬化涂层与透明PI基层间的附着力,而且预涂液的组成决定了预涂层与硬化层之间也具有良好的结合力,进而提高PI硬化膜的耐紫外湿热性能,且不会影响硬化层的硬度、耐磨性等综合性能。(The invention belongs to the technical field of pre-coating liquid for transparent polyimide hardened films, and particularly relates to ultraviolet-humidity-heat-aging-resistant pre-coating liquid for transparent PI hardened films and application thereof, wherein the pre-coating liquid comprises the following components in parts by weight: 100 parts of low molecular weight resin, 50-100 parts of strong polar monomer, 1-5 parts of thermal initiator, 0.05-1 part of flatting agent and 1000-1500 parts of solvent. The precoating liquid contains a proper amount of low molecular weight resin and a strong polar monomer which are matched with each other, so that the precoating liquid can permeate into the transparent PI base material, penetrate and bite with the transparent PI base material, and the precoating layer is firmly attached to the surface of the base material through curing and crosslinking, so that the adhesive force between the hardened coating and the transparent PI base material is improved, and the composition of the precoating liquid determines that the precoating layer and the hardened layer also have good binding force, so that the ultraviolet and damp heat resistance of the PI hardened film is improved, and the comprehensive performances of hardness, wear resistance and the like of the hardened layer cannot be influenced.)

1. The precoating liquid for the ultraviolet-moisture-heat-aging-resistant transparent PI hardened film is characterized by comprising the following components in parts by weight: the composition comprises the following components in parts by weight:

100 parts of low molecular weight resin

50-100 parts of strong polar monomer

1-5 parts of thermal initiator

0.05 to 1 portion of flatting agent

1000 portions of solvent and 1500 portions.

2. The precoat liquid for a transparent PI hardened film resistant to ultraviolet, humidity and heat aging according to claim 1, characterized in that: the low molecular weight resin is one or more of 2-functional or 3-functional amide acrylate, 2-functional or 3-functional pentaerythritol acrylate, oligomeric caprolactam, oligomeric polycaprolactone, oligomeric lactide, four-arm PEG vinyl sulfone and four-arm PEG acrylate.

3. The precoat liquid for a transparent PI hardened film resistant to ultraviolet, humidity and heat aging according to claim 1, characterized in that: the strong polar monomer is one or more of N, N-dimethylacrylamide, tetrahydrofuran acrylate, polycaprolactone acrylate, N-diethylaminoethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 3- (trimethylsilyl) propyl acrylate, 3- (triethylsilyl) propyl acrylate, pyridyl acrylate, glycidyl acrylate, vinyl pyrrolidone, tetrahydrofurfuryl acrylate, imidazolyl acrylate, furyl acrylate and N-succinimidyl acrylate.

4. The precoat liquid for a transparent PI hardened film resistant to ultraviolet, humidity and heat aging according to claim 1, characterized in that: the thermal initiator is one or more of peroxide initiators, azo initiators and redox initiators.

5. The precoat liquid for a transparent PI hardened film resistant to ultraviolet, humidity and heat aging according to claim 1, characterized in that: the leveling agent is one or more of an organic silicon leveling agent, an acrylate leveling agent and a fluorine leveling agent.

6. The precoat liquid for a transparent PI hardened film resistant to ultraviolet, humidity and heat aging according to claim 1, characterized in that: the solvent is one or more of ketone solvent, ester solvent, benzene solvent, ether solvent, alcohol solvent and amide solvent.

7. Use of the precoat liquid for transparent PI hardened films resistant to ultraviolet, moist and heat aging according to any one of claims 1 to 6, characterized in that: used between the transparent PI substrate and the hardened layer.

8. Use of the precoat liquid for a transparent PI hardened film resistant to ultraviolet, humid and heat aging according to claim 7, characterized in that: the method comprises the following steps:

(1) uniformly coating the pre-coating liquid on a transparent PI substrate, and then performing heat curing to obtain a pre-coating layer;

(2) and uniformly coating a layer of hardening liquid on the surface of the precoating layer, then curing to obtain a hardened layer, and attaching a protective film after the hardened layer is cooled.

9. Use of the precoat liquid for a transparent PI hardened film resistant to ultraviolet, humid and heat aging according to claim 8, characterized in that: the conditions of thermal curing in the step (1) are as follows: treating at 60-80 deg.C for 30-60s, at 80-100 deg.C for 30-60s, at 80-100 deg.C for 30-60s, and at a drying tunnel pressure of 1.01-1.05 ATM.

10. Use of the precoat liquid for a transparent PI hardened film resistant to ultraviolet, humid and heat aging according to claim 8, characterized in that: the thickness of the precoat layer is 50-200 nm.

Technical Field

The invention belongs to the technical field of pre-coating liquid for transparent polyimide hardened films, and particularly relates to ultraviolet, humidity and heat aging resistant pre-coating liquid for transparent PI hardened films and application thereof.

Background

The technique of curved screen has been generally regarded and pursued by consumers and the industry in recent years. With the continuous development and improvement of the fixed curvature curved screen technology in the future, the flexible touch screen capable of realizing arbitrary bending is bound to become an important development direction. Although flexible screens can be bent, if they are bent frequently, they suffer from fatigue problems like metal paper. If multiple bending and prolonged use are performed, the flexible screen may suffer from a crease in the middle of the screen after being subjected to multiple compressive and tensile stresses. In addition, circuit boards, components, and the like, when subjected to a large amount of bending and non-bending, may also be damaged or otherwise fail when folded. The existing glass panel can not meet the requirement of high frequency, the transparent polyimide (CPI) film is used for replacing the existing glass cover plate because the transparent Polyimide (PI) film has good foldability, but the Polyimide (PI) material can not meet the requirement of hardness, and a hardening coating needs to be added on the surface of a PI substrate to enhance the hardness.

However, in the existing transparent PI hardened film products, the transparency of the transparent PI is generally improved by fluorine modification, which makes it more difficult for the hardened layer on the surface of the substrate to adhere, and the hardened layer falls off after the uv-hygrothermal aging test. Therefore, there is a need to develop a precoat layer capable of improving the adhesion between the transparent PI substrate and the hardened layer, and improving the ultraviolet, humidity and heat aging resistance of the transparent PI hardened film, while not affecting the overall properties of the hardened coating, such as hardness and wear resistance.

Disclosure of Invention

The invention discloses a pre-coating liquid for a transparent PI hardening film with ultraviolet-damp-heat aging resistance and application thereof, aiming at providing a pre-coating layer capable of improving the adhesive force between a transparent PI base material and a hardening layer, improving the ultraviolet-damp-heat aging resistance of the transparent PI hardening film without affecting the comprehensive performances of hardness, wear resistance and the like of the hardening coating, wherein the pre-coating liquid can effectively improve the adhesive force between the transparent PI base material and the hardening layer, thereby improving the ultraviolet-damp-heat aging resistance of the PI hardening film without affecting the hardness and wear resistance of the hardening film.

In order to achieve the purpose, the invention adopts the following technical scheme:

the pre-coating liquid for the ultraviolet, damp and heat aging resistant transparent PI hardened film comprises the following components in parts by weight:

preferably, the low molecular weight resin is one or more of 2-functional or 3-functional amide acrylate, 2-functional or 3-functional pentaerythritol acrylate, oligomeric caprolactam, oligomeric polycaprolactone, oligomeric lactide, four-arm PEG vinyl sulfone, and four-arm PEG acrylate.

Preferably, the strongly polar monomer is one or more selected from the group consisting of N, N-dimethylacrylamide, tetrahydrofuryl acrylate, polycaprolactone acrylate, N-diethylaminoethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 3- (trimethylsilyl) propyl acrylate, 3- (triethylsilyl) propyl acrylate, pyridyl acrylate, glycidyl acrylate, vinyl pyrrolidone, tetrahydrofuryl acrylate, imidazolyl acrylate, furyl acrylate, and N-succinimidyl acrylate.

Preferably, the thermal initiator is one or more of a peroxide initiator, an azo initiator, and a redox initiator.

Preferably, the leveling agent is one or more of an organic silicon leveling agent, an acrylate leveling agent and a fluorine leveling agent.

Preferably, the solvent is one or more of ketone solvent, ester solvent, benzene solvent, ether solvent, alcohol solvent and amide solvent.

The application of the pre-coating liquid for the transparent PI hardened film with ultraviolet, humidity and heat aging resistance is used between a transparent PI base material and a hardened layer.

Preferably, the application of the pre-coating liquid for the transparent PI hardened film with ultraviolet, humidity and heat aging resistance comprises the following steps:

(1) uniformly coating the pre-coating liquid on a transparent PI substrate, and then performing heat curing to obtain a pre-coating layer;

(2) and uniformly coating a layer of hardening liquid on the surface of the precoating layer, then curing to obtain a hardened layer, and attaching a protective film after the hardened layer is cooled.

Preferably, the conditions for heat curing in the step (1) are as follows: treating at 60-80 deg.C for 30-60s, at 80-100 deg.C for 30-60s, at 80-100 deg.C for 30-60s, and at a drying tunnel pressure of 1.01-1.05 ATM.

Preferably, the thickness of the precoat layer is 50 to 200 nm.

The invention has the following beneficial effects:

(1) the precoating liquid contains a proper amount of low molecular weight resin and strong polar monomer, the strong polar monomer and the low molecular weight resin are matched with each other, so that the precoating liquid can permeate into the transparent PI base material and penetrate and bite with the transparent PI base material, the precoating layer is firmly attached to the surface of the base material through curing and crosslinking, the adhesive force between the hardened coating and the transparent PI base layer is improved, the composition of the precoating liquid determines that the precoating layer and the hardened layer also have good binding force, and further the ultraviolet and moisture resistance of the PI hardened film is improved, and the binding force between the transparent PI base material and the hardened layer can not be improved due to the precoating layer, so that the other properties of the hardened layer can not be influenced, and the comprehensive properties such as hardness, wear resistance and the like of the hardened layer can not be influenced by the use of;

(2) the precoating liquid of the invention sets a specific drying gradient and curing conditions in the drying process, controls the mutual permeation of the precoating layer and the transparent PI base material to reach a specific concentration gradient and a specific permeation depth, and enables the precoating layer to be firmly attached to the surface of the transparent PI base material like a tree root is pricked into soil, thereby finally achieving the purpose of improving the ultraviolet, humidity and heat aging resistance.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a graphical representation of different depth fluorine levels in transparent PI substrates of examples of the invention and some comparative examples;

FIG. 2 is a schematic illustration of the process of the invention for penetration of a pre-coat liquid into a clear PI substrate.

Detailed Description

The present invention will now be described in further detail with reference to examples.

The preparation method of the pre-coating liquid comprises the following steps: weighing low molecular weight resin, strong polar monomer, thermal initiator, flatting agent and solvent according to a proportion, and mixing uniformly.

The application of the pre-coating liquid for the transparent PI hardening film with ultraviolet, moisture and heat aging resistance comprises the following steps:

(1) uniformly coating the pre-coating liquid on a transparent PI substrate, and then performing heat curing to obtain a pre-coating layer;

(2) and uniformly coating a layer of hardening liquid on the surface of the precoating layer, then curing to obtain a hardened layer, and attaching a protective film after the hardened layer is cooled.

Drying conditions of the precoating liquid:

condition 1: the distance from the coating head to the drying tunnel is 2.5 meters, the drying tunnel has 16 sections, each section has 2.5 meters, the vehicle speed is 10 meters/min, and the pressure of the drying tunnel is as follows: 1.01-1.05 ATM.

Baking oven	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16
																	T/℃	60	70	70	80	80	90	90	100	100	110	110	120	120	100	100	80

Condition 2: the distance from the coating head to the drying tunnel is 2.5 meters, the drying tunnel has 16 sections, each section has 2.5 meters, the vehicle speed is 10 meters/min, and the pressure of the drying tunnel is as follows: 1.01-1.05 ATM.

Baking oven	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16
																	T/℃	60	65	70	75	80	85	90	95	100	105	110	120	110	100	90	80

Condition 3: the distance from the coating head to the drying tunnel is 2.5 meters, the drying tunnel has 16 sections, each section has 2.5 meters, the vehicle speed is 10 meters/min, and the pressure of the drying tunnel is as follows: 1.01-1.05 ATM.

Baking oven	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16
																	T/℃	60	60	70	70	80	80	90	90	100	100	90	90	80	80	60	60

The hardening liquid can be directly selected from the hardening liquids for PI hardening films sold in the market, and the specific curing conditions are based on the requirements of the selected hardening liquid sold in the market.

The components of the precoat liquids used in examples 1 to 5 and comparative examples 1 to 8, their amounts by weight, and curing conditions are detailed in Table 1.

TABLE 1

Comparative example 9, comparative example 9 is substantially the same as example 4 except that comparative example 9 does not apply the pre-coating liquid on the transparent PI substrate.

The results of UV-moist heat aging resistance of the PI hardened films prepared using the precoat solutions prepared in examples 1 to 5 and comparative examples 1 to 8 and the PI hardened film of comparative example 9 are shown in Table 2.

TABLE 2

The conditions of uv damp heat ageing in the hundred cells after uv damp heat ageing in table 2 are: strong ultraviolet at 340nm, 60 deg.C, relative humidity of 90%, 72 hr.

Since the precoating liquid is applied between the transparent PI base material and the surface hardened layer, the hardness, wear resistance, yellowing resistance and the like of the hardened film are not affected.

FIG. 1 is a schematic diagram of fluorine contents at different depths in the transparent PI base materials of the embodiment and some comparative examples of the present invention, and it can be seen that the fluorine contents in the surface layers of the transparent PI base materials of the embodiments 1-5 are much lower than those of the comparative examples 1-8, and it can be seen from FIG. 2 that after the pre-coating liquid of the embodiments 1-5 is coated on the surface of the transparent PI base material, the pre-coating liquid penetrates into the transparent PI base material, and penetrates and bites with the transparent PI base material, and after curing and crosslinking, the pre-coating layer is firmly attached to the surface of the base material, so that the binding force between the pre-coating layer and the transparent PI base material is improved, and the composition of the pre-coating layer determines that the pre-coating layer and the hardened layer also have good binding.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.