CN212493791U

CN212493791U - Transparent polyimide film

Info

Publication number: CN212493791U
Application number: CN201922116407.1U
Authority: CN
Inventors: 耿龙飞; 徐金龙; 葛建峰; 孔祥永; 尹晓峰
Original assignee: Hunan Zhongtian Bishui Membrane Technology Co ltd
Current assignee: Great Rich Technology Co Ltd
Priority date: 2019-11-29
Filing date: 2019-11-29
Publication date: 2021-02-09
Anticipated expiration: 2029-11-29

Abstract

The utility model provides a transparent polyimide film, including the sclerosis coating, colorless transparent polyimide substrate, sclerosis coating elongation at break/substrate elongation at break ratio range is 0.7-1.5, has realized that the polyimide sclerotomide can be when less radius of buckling, and the index of buckling and outer bending 10 ten thousand times of not splitting in the realization, when less radius of curvature is buckled even, the technical problem that the sclerosis coating does not split.

Description

Transparent polyimide film

Technical Field

The utility model relates to an optical film, concretely relates to polyimide film.

Background

In recent years, with the development of mobile smart phones and tablet computers, it is required to make the substrate for displays thin and lightweight. Glass materials are generally used as materials having excellent mechanical characteristics as well as optical characteristics for protection at the outer layer of a display for a mobile smart device. But the weight of the mobile device is increased due to the glass having a large density of its own, and there is a defect of breakage due to external impact or drop.

Therefore, high molecular plastic resins are being studied as substitutes for glass. The polymer plastic resin composition is lightweight, can resist external large impact force or drop resistance, and thus is suitable for the trend of pursuing lighter smart mobile terminals. In particular, in order to obtain compositions having high hardness, high abrasion resistance and strong anti-fouling properties, compositions for applying a hardbanding coating on a supporting substrate have been proposed.

Meanwhile, a display in which a portion of a display device is bent or flexibly twisted has recently attracted market attention for aesthetic and functional reasons, and this tendency is particularly remarkable in mobile devices such as smart phones and tablet computers. However, since glass is not suitable for use as a cover plate for protecting such a flexible display, it is necessary to replace glass with plastic resin or the like. However, when the product is bent, the functional hardening coating does not crack due to the certain thickness of the hardening coating, and when the functional hardening coating cracks or even falls off seriously, the coating does not crack when the product is bent with a larger radius curvature.

SUMMERY OF THE UTILITY MODEL

The main object of the utility model is to provide a transparent polyimide film can be when less radius of buckling in order to realize the polyimide hardening film, and the index that buckles and not split is buckled outward in the realization, and when less radius of curvature buckles even, the problem that the hardened coating does not split.

The transparent polyimide film is characterized by comprising a hardened coating and a colorless transparent polyimide substrate, wherein the ratio of the elongation at break of the hardened coating to the elongation at break of the colorless transparent polyimide substrate ranges from 0.7 to 1.5, the ratio of the elongation at break of the hardened coating to the elongation at break of the colorless transparent polyimide substrate is lower than 0.7, when the hardened coating is bent outwards, the bending curvature radius of the hardened coating relative to the substrate is larger, the coating is easy to crack and even fall off, and when the ratio of the elongation at break of the hardened coating to the elongation at break of the colorless transparent polyimide substrate exceeds 1..

Further, the coating thickness of the hardened coating ranges from 2 to 10 μm, and the smaller the thickness, the lower the pencil hardness, the thickness exceeding 10 μm, the severe warping, and the poor outer bending performance.

Further, the hardened coating has a refractive index in the range of 1.45 to 1.55.

Furthermore, the elongation at break of the hardened coating is greater than or equal to 10%, and the larger the elongation at break of the hardened coating is, the harder the hardened coating cracks and even falls off when the flexible polyimide hardened film is bent inside and outside the film.

Further, the colorless transparent polyimide substrate has an elongation at break of 10% or more, and when the colorless transparent polyimide substrate is bent inside and outside, the coating and the colorless transparent polyimide substrate themselves are not damaged by tensile force caused by bending.

Further, the colorless transparent polyimide substrate has a young's modulus of 4 or more, which is one of the conditions that the colorless transparent polyimide substrate can be effectively bent 10 ten thousand times, and a transparent polyimide film can have a pencil hardness of 4H or more by applying a hard coat having a high hardness.

Further, the hardened coating comprises:

organic resin: 10 to 40 percent of

Inorganic particles: 4 to 10 percent of

Leveling agent: 1-10%

A slipping auxiliary agent: 1 to 5 percent

Initiator: 1 to 3 percent of

Solvent: 49 to 83 percent

The organic resin is selected from: the adhesive comprises one or more of dipentaerythritol pentaacrylate, pentaerythritol tetraacrylate and polyurethane acrylate, wherein the dipentaerythritol pentaacrylate/pentaerythritol tetraacrylate/polyurethane acrylate (2/1/3) can realize that the elongation at break of a hardened coating meets the requirement of 10%, the higher the content of dipentaerythritol pentaacrylate is, the higher the hardness of the coating after glue curing is, the higher the content of polyurethane acrylate is, the lower the hardness of the coating but the better the bending performance of the coating is, the leveling agent is BYK-3760, the smooth assistant is organosilicon-modified polyurethane acrylate, the water contact angle of the surface of the coating is improved, the abrasion resistance of the surface of the coating is improved, and the initiator comprises initiator 184 and TPO.

Further, the inorganic particles are surface-treated silica particles, the refractive index of the silica particles ranges from 1.45 to 1.5, the surfaces of the inorganic particles are subjected to surface treatment by fluorine-containing organic substances, the fluoride is selected from tridecafluorooctyl siloxane and propenyl siloxane, the surfaces of the inorganic particles simultaneously contain fluorine organic substances and double bond-containing organic compounds, the surface-treated inorganic particles further reduce the agglomeration among nano particles, and the hardened coating reacts with other unsaturated bond organic resins containing unsaturated bonds during UV curing, so that the inorganic particles are further locked in the hardened coating and on the surface of the hardened coating, and the wear resistance of the coating is enhanced.

The inorganic particle surface treatment is as follows:

2 g of silica nanoparticles (average diameter 25nm) were purchased from the market, and placed in 50mL of anhydrous xylene solvent, 2mL of tridecafluorooctylsiloxane and 2mL of acryl siloxane organic substance were added, and refluxed for 5 hours, and further a hydrophobic group tridecafluorooctyl group and an organic substance having an unsaturated bond were grafted onto the surface of the silica particles, and finally dried at 120 ℃ for 10 hours to obtain fluorine compound-treated silica particles.

Further, the inorganic particles have a particle size ranging from 10 to 200nm, and the larger the particle diameter is, the poorer the optical effect of the film containing the hard coat layer is.

Further, the difference in refractive index between the organic resin and the inorganic particles is in the range of 0.01 to 0.3, and if the difference in refractive index between the two is too large, the rainbow unevenness is liable to be heavy.

Advantageous effects

The utility model discloses realize polyimide hardening film can be when less radius of buckling, realize interior buckling promptly buckle 10 ten thousand times towards the hardened coating and outer bending promptly buckle 10 ten thousand times indexs that do not split towards the base material face promptly, when less radius of curvature buckles even, the technical problem that the hardened coating does not split.

Drawings

FIG. 1 is a schematic structural view of example 1, wherein 1 is a colorless transparent substrate, and 2 is a hardened coating.

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.

Example 1

The hardened coating glue was applied to one optical surface of a substrate of colorless transparent polyimide (korean Kolon substrate) having a thickness of 50 μm, and after thermal drying and UV curing, a hardened coating having an optical thickness of 8 μm was formed.

A hardening coating, the total content of organic resin is 30%, and the hardening coating comprises 10% of dipentaerythritol pentaacrylate, 5% of pentaerythritol tetraacrylate and 15% of urethane acrylate; the content of the silicon dioxide particles subjected to surface treatment is 10%, the content of a flatting agent BYK-3760 is 2%, the content of a slipping auxiliary agent organosilicon modified polyurethane acrylate is 3%, the content of an initiator 184 is 2%, and the content of an initiator TPO is 1%.

The elongation at break of the hardened coating is 15 percent,

the elongation at break of the polyimide is 12 percent,

the elongation at break of the hardened coating/elongation at break of polyimide was 1.25,

the refractive index of the hardened coating is 1.51,

refractive index of hardened coating 1.49

The Young's modulus of the colorless transparent polyimide is 6.2,

the results of the tests on the optical properties, hardness, abrasion resistance, water contact angle, coefficient of dynamic friction, etc. of the flexible polyimide film prepared in example 1 are shown in Table I

Example 2

Unlike example 1, the content of inorganic particles in the glue in the hard coating was 4%.

Example 3

Unlike example 1, the slip aid in the glue in the hard coat was 1%.

Example 4

Unlike example 1, the slip aid in the glue in the hard coat was 5%.

Example 5

Unlike example 1, the total content of organic resin in the glue in the hardcoat was 10%, where dipentaerythritol pentaacrylate/pentaerythritol tetraacrylate/urethane acrylate was 2/1/3.

Example 6

Unlike example 1, the total content of organic resin in the glue in the hardcoat layer was 40%, where dipentaerythritol pentaacrylate/pentaerythritol tetraacrylate/urethane acrylate was 2/1/3.

Example 7

Unlike example 1, the elongation at break of the hardened coating was 18%, and the elongation at break of the hardened coating/elongation at break of polyimide was 1.5.

Wherein the hard coating contains 3% of dipentaerythritol pentaacrylate, 1% of pentaerythritol tetraacrylate and 26% of urethane acrylate in the glue.

Example 8

Unlike example 1, the hardened coating elongation at break was 10%, the polyimide elongation at break was 14.29%, and the hardened coating elongation at break/polyimide elongation at break was 0.7.

Wherein the content of dipentaerythritol pentaacrylate in the glue is 27%, the content of pentaerythritol tetraacrylate is 1%, and the content of urethane acrylate is 2%.

Example 9

Unlike example 1, the elongation at break of the polyimide substrate was 10%, and the elongation at break of the hardened coating/elongation at break of the polyimide was equal to 1.5.

Example 10

Unlike example 1, the colorless transparent polyimide substrate pattern modulus was 4.

Example 11

The thickness of the hardened coating was 2 μm, unlike in example 1.

Example 12

The thickness of the hardened coating was 10 μm, unlike in example 1.

Comparative example 1

Unlike example 1, the elongation at break of the hardened coating was 5%.

Comparative example 2

Unlike example 1, the polyimide substrate had an elongation at break of 5%.

Comparative example 3

Unlike example 1, the elongation at break of the hardened coating/elongation at break of polyimide was 0.3.

In the hardening coating glue, the content of dipentaerythritol pentaacrylate is 30%, the content of pentaerythritol tetraacrylate is 1%, and the content of urethane acrylate is 0.

Comparative example 4

Unlike example 1, the elongation at break of the hardened coating/elongation at break of polyimide was 3.

In the hardening coating glue, the content of dipentaerythritol pentaacrylate is 0, the content of pentaerythritol tetraacrylate is 0, and the content of urethane acrylate is 30%.

Comparative example 5

Unlike example 1, the inorganic particle content was 1%.

Comparative example 6

Unlike example 1, the inorganic particle content was 30%.

Comparative example 7

Unlike example 1, no slip aid was included.

Comparative example 8

Unlike example 1, the slip aid content was 10%.

Comparative example 9

Unlike example 1, the substrate colorless polyimide pattern modulus was 2.

Comparative example 10

Unlike example 1, the total organic resin content was 5%.

Comparative example 11

Unlike example 1, the total organic resin content was 50%.

Comparative example 12

Different from the example 1, the total content of the organic resin is 30%, the content of pentaerythritol tetraacrylate in the glue in the hard coating is 1%, and the content of urethane acrylate is 29%.

Comparative example 13

Different from the example 1, the total content of the organic resin is 30%, the content of dipentaerythritol pentaacrylate in the glue in the hard coating is 29%, and the content of pentaerythritol tetraacrylate is 1%.

Comparative example 14

The thickness of the hardened coating was 1 μm, unlike in example 1.

Comparative example 15

Unlike example 1, the thickness of the first hardened coating was 15 μm.

	T.T. (％)	Haze	WCA	Pencil hardness Degree of rotation	Dynamic friction system Number of	Abrasion resistance (1 kg/2000) Second)	WCA after abrasion resistance (1kg/20 times) (°)	Inner bend (R3)	Outer bend (R5)
										Example 1	91.5	0.75	115	7H	0.13	OK	98	OK	OK
Example 2	91.3	0.8	114	6H	0.13	OK	98	OK	OK
										Example 3	91.4	0.74	112	7H	0.2	OK	96	OK	OK
Example 4	91.4	0.78	113	7H	0.15	OK	95	OK	OK
										Example 5	91.3	0.75	112	7H	0.25	OK	96	OK	OK
Example 6	91.3	0.8	113	6H	0.15	OK	98	OK	OK
										Example 7	91.2	0.8	113	6H	0.15	OK	98	OK	OK
Example 8	91.3	0.75	112	7H	0.25	OK	96	OK	OK
										Example 9	91.5	0.77	115	7H	0.13	OK	98	OK	OK
Examples 10	91.2	0.8	115	6H	0.13	OK	98	OK	OK
										Examples 11	91.2	0.8	115	4H	0.13	OK	98	OK	OK
Examples 12	91.2	0.8	115	7H	0.13	OK	98	OK	OK
										Comparative example 1	91	0.8	115	7H	0.13	OK	98	OK	NG
Comparative example 2	91	0.8	115	7H	0.14	OK	98	NG	NG
										Comparative example 3	91	0.8	115	7H	0.14	OK	98	OK	NG
Comparative example 4	91	0.8	115	2H	0.4	NG	63	OK	OK
										Comparative example 5	91	0.75	100	4H	0.3	NG	80	OK	OK
Comparative example 6	91	1.2	102	5H	0.8	NG	70	NG	NG
										Comparative example 7	91	0.76	105	7H	0.6	OK	80	OK	OK
Comparative example 8	91	0.75	110	6H	0.15	NG	64	OK	OK
										Comparative example 9	91	0.75	113	2H	0.3	OK	90	OK	OK
Comparative example 10	89	1	110	2H	0.6	NG	65	NG	NG
										Comparative example 11	91	0.7	109	5H	0.3	NG	70	OK	OK
Comparative example 12	91	0.73	110	3H	0.3	NG	69	OK	OK
										Comparative example 13	91	0.75	110	6H	0.3	NG	60	NG	NG
Comparative example 14	91	0.8	114	2H	0.3	OK	95	OK	OK
										Comparative example 15	91	0.75	113	7H	0.3	OK	97	NG	NG

TABLE 1

R3: radius 3mm

R5: radius 5mm

And (3) internal bending: bending 10 ten thousand times towards the hardened coating

And (3) bending outwards: bending the substrate surface for 10 ten thousand times

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 transparent polyimide film is characterized by comprising a hardened coating and a colorless transparent polyimide substrate, wherein the ratio of the elongation at break of the hardened coating to the elongation at break of the colorless transparent polyimide substrate is in the range of 0.7-1.5.

2. The transparent polyimide film of claim 1, wherein the hardened coating has a coating thickness in the range of 2-10 μ ι η.

3. The transparent polyimide film of claim 1 wherein the hardened coating has a refractive index in the range of 1.45 to 1.55.

4. The transparent polyimide film of claim 1 wherein the hardened coating has an elongation at break of 10% or more.

5. The transparent polyimide film according to claim 1, wherein the colorless transparent polyimide substrate has an elongation at break of 10% or more.