KR101854722B1 - Manufacturing method of composite sheet with excellent heat resistance, chemical resistance and flexibility - Google Patents

Abstract

Disclosed are: a composite sheet with excellent heat resistance, chemical resistance and flexibility, which can secure excellent physical properties by adding high temperature heat resistance which is the strength of a polyimide resin while maintaining flexibility and chemical resistance which are the strengths of silicone rubber; a manufacturing method thereof. The composite sheet with excellent heat resistance, chemical resistance and flexibility according to the present invention comprises: silicone rubber; and the polyimide resin mixed with the silicone rubber.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite sheet having excellent heat resistance, chemical resistance and flexibility,

The present invention relates to a composite sheet and a method of manufacturing the same, and more particularly, to a composite sheet and a method of manufacturing the same, which are capable of securing excellent physical properties by adding high temperature heat resistance which is a strength of a polyimide resin while maintaining flexibility and chemical resistance, Heat resistance, chemical resistance, and flexibility, and a method for producing the same.

2. Description of the Related Art Generally, display products such as LCDs are manufactured using a thermocompression bonding process in which a drive IC such as a flexible printed circuit board (FPCB) or a chip is bonded to a display glass panel using an ACF (anisotropy conductive film) have.

In this case, the ACF refers to a material in which fine conductive ball particles are uniformly dispersed in an organic polymer adhesive component, and adhesion is caused by heat and pressure.

In such an ACF bonding process, if heat and pressure are applied directly to the FPCB or chip to bond the display glass panel to the display glass panel, the drive IC or the display glass panel is damaged, and heat and pressure are transmitted unevenly There is a high risk of failure during bonding.

Therefore, the buffer sheet is used for uniformly transmitting heat and pressure, and at the same time, buffering from a tool tip of a steel material so that the ACF is completely bonded.

As a conventional buffer sheet, a silicone rubber excellent in heat resistance, chemical resistance and flexibility was used. However, in the case of a buffer sheet using silicone rubber, it has excellent heat resistance up to about 250 캜. However, at a high temperature of 300 캜 or more, there is a problem that the life time is short because of the restriction on the use frequency and the like due to lack of heat resistance.

A related prior art is disclosed in Korean Patent Laid-Open Publication No. 10-2013-0074956 (published on May 3, 2015), which discloses a resin composition for fixing a semiconductor lead and a tape for fixing a lead using the same.

An object of the present invention is to provide a composite sheet excellent in heat resistance, chemical resistance, and flexibility, which can secure excellent physical properties by adding high temperature heat resistance which is a strength of polyimide resin while maintaining flexibility and chemical resistance, And a method for manufacturing the same.

In order to achieve the above object, the present invention provides a composite sheet excellent in heat resistance, chemical resistance, and flexibility, comprising: a silicone rubber; And a polyimide resin mixed with the silicone rubber.

According to an aspect of the present invention, there is provided a method of manufacturing a composite sheet excellent in heat resistance, chemical resistance, and flexibility, comprising: (a) forming a silicone rubber solution in which a silicone rubber is dissolved in a first solvent; (b) dissolving an aromatic diamine and an aromatic dianhydride in a second solvent to form a polyamic acid; (c) mixing the silicone rubber solution and the polyamic acid, and then adding a third solvent to form a coating solution; And (d) coating the coating solution on the carrier film, drying and imidizing the coating solution to form a composite sheet.

The composite sheet excellent in heat resistance, chemical resistance, and flexibility according to the present invention and the method for producing the same can be obtained by adding a polyimide resin to a silicone rubber to make the silicone rubber have a heat resistance- And the low elongation problem of the polyimide resin can be compensated by the addition of the silicone rubber.

As a result, the composite sheet excellent in heat resistance, chemical resistance, and flexibility according to the present invention is obtained by compounding a silicone rubber with a polyimide resin to make it flexible and chemically resistant, which is the strength of silicone rubber, By adding heat resistance, excellent high-temperature heat resistance, chemical resistance and flexibility can be secured at the same time.

In addition, the composite sheet excellent in heat resistance, chemical resistance and flexibility according to the present invention has excellent heat resistance and chemical resistance, and has a considerably high elongation of 10 to 50%. Therefore, A substrate for a display (stretchable display), various clothes used in a high-temperature environment, and footwear.

1 is a sectional view showing a composite sheet excellent in heat resistance, chemical resistance and flexibility according to an embodiment of the present invention.
2 is a process flow chart showing a method for producing a composite sheet excellent in heat resistance, chemical resistance and flexibility according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent by reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a composite sheet having excellent heat resistance, chemical resistance, and flexibility according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a composite sheet excellent in heat resistance, chemical resistance, and flexibility according to an embodiment of the present invention.

Referring to FIG. 1, the composite sheet 100 having excellent heat resistance, chemical resistance, and flexibility according to an embodiment of the present invention includes a polyimide resin mixed with silicone rubber and silicone rubber. Accordingly, the composite sheet 100 having excellent heat resistance, chemical resistance, and flexibility according to the embodiment of the present invention has a single layer structure in which a silicone rubber and a polyimide resin are mixed.

That is, the composite sheet 100 having excellent heat resistance, chemical resistance, and flexibility according to the present invention is obtained by compounding a silicone rubber with a polyimide resin so as to make it possible to maintain the flexibility and chemical resistance of the silicone rubber, Heat resistance, heat resistance, chemical resistance, and flexibility at the same time.

At this time, silicone rubber has excellent chemical resistance and flexibility, and has been used as a buffer sheet for ACF bonding in an LCD module process. However, in the case of a buffer sheet made only of silicone rubber, it has excellent heat resistance up to about 250 캜, but at a high temperature of 300 캜 or more, there is a problem that the lifetime is short because of the restriction of the use frequency and the like due to lack of heat resistance.

The polyimide resin is a polymer having an imide bond in the main chain, and particularly excellent in heat resistance even at a high temperature of 300 캜 or more. The polyimide resin also exhibits excellent properties in terms of mechanical strength, chemical resistance, and the like. However, the polyimide resin is a polymer having excellent heat resistance even at a high temperature of 300 캜 or more, but has a disadvantage of low elongation.

Such a polyimide resin is a polyimide resin prepared by synthesizing an aromatic dianhydride having any one of an ether group, a ketone group and a methyl group and an ether group, a ketone group and a methyl group in a polar solvent, Is preferably used.

As the polyamic acid, it is preferable to use a thermoplastic type rather than a thermosetting type because the thermoplastic type is more effective in improving the elongation than the thermosetting type.

The aromatic diamine includes 3,3'-dimethyl- [1,1'-biphenyl] -4,4'-diamine represented by the following formula (1).

[Chemical Formula 1]

Further, the aromatic dianhydride includes 3,3 ', 4,4'-benzophenonetetracarbolxyl dianhydride represented by the following formula (2).

(2)

The polar solvent may be at least one selected from DMF (dimethylformamide), NMP (N-methyl-2-pyrrolidone), DMSO (dimethyl sulfoxide), DMAc (dimethylacetamide)

The composite sheet 100 having excellent heat resistance, chemical resistance, and flexibility according to the embodiment of the present invention is formed by adding a polyimide resin to a silicone rubber to make the silicone rubber have a portion lacking heat resistance at a high temperature of 300 ° C or higher The addition of the polyimide resin makes it possible to compensate and the low elongation problem of the polyimide resin can be compensated by the addition of the silicone rubber.

To this end, the composite sheet 100 having excellent heat resistance, chemical resistance, and flexibility according to the embodiment of the present invention preferably includes 55 to 80% by weight of silicone rubber and 45 to 20% by weight of polyimide resin.

When the addition amount of the silicone rubber is less than 55% by weight of the total weight of the composite sheet, the elongation is decreased due to an increase in the amount of the polyimide resin relative to that of the composite sheet. On the other hand, if the amount of silicone rubber added exceeds 80% by weight of the total weight of the composite sheet, it may be difficult to ensure high temperature heat resistance at 300 ° C or higher.

The composite sheet excellent in heat resistance, chemical resistance, and flexibility according to the above-described embodiment of the present invention is formed by adding a polyimide resin to a silicone rubber to make the silicone rubber a polyimide resin having a low heat resistance at a high temperature of 300 캜 or higher, , And the low elongation problem of the polyimide resin can be compensated by the addition of the silicone rubber.

As a result, the composite sheet excellent in heat resistance, chemical resistance, and flexibility according to the embodiment of the present invention is obtained by compounding a silicone rubber with a polyimide resin so that the flexibility and chemical resistance of the silicone rubber are maintained, By adding high temperature heat resistance which is a strength, excellent heat resistance, chemical resistance, and flexibility can be ensured at the same time.

In addition, the composite sheet excellent in heat resistance, chemical resistance, and flexibility according to the embodiment of the present invention is excellent in high temperature heat resistance and chemical resistance, and has a considerably high elongation of 10 to 50% It may be possible to utilize it as a base material of a stretchable display substrate, various clothes used in a high temperature environment, and footwear.

Hereinafter, a method for manufacturing a composite sheet having excellent heat resistance, chemical resistance, and flexibility according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a process flow chart showing a method for producing a composite sheet excellent in heat resistance, chemical resistance, and flexibility according to an embodiment of the present invention.

Referring to FIG. 2, the method for manufacturing a composite sheet having excellent heat resistance, chemical resistance, and flexibility according to an embodiment of the present invention includes forming a silicone rubber solution S110, forming a polyamic acid S120, And a composite sheet forming step (S140).

silicon Rubber  Solution formation

In the silicone rubber solution forming step (S110), a silicone rubber solution in which the silicone rubber is dissolved in the first solvent is formed.

Generally, because silicone rubbers are not well soluble in polar solvents, their compatibility with polar solvents, which are the second solvents for dissolving polyamic acids, is poor and they do not mix with each other. Therefore, it is preferable to use a non-polar solvent as the first solvent for dissolving the silicone rubber. As the nonpolar solvent, at least one selected from toluene, pentane, n-hexane, heptane, octane, carbon tetrachloride, benzene, methylcyclohexane and the like may be used.

In addition, the solubility of the silicone rubber dissolved in the non-polar solvent is also important. Unless the silicone rubber is dissolved in the non-polar solvent in an amount of 20 wt% or more, the remaining polar solvent repels the polar solvent of the polyamic acid, and a uniform coating film can not be formed. Further, when an excess amount of silicone rubber exceeding 40 wt% is dissolved in the nonpolar solvent, the silicone rubber does not dissolve in the non-polar solvent and reacts with the polyamic acid to cause a color change, and it becomes difficult to secure a uniform film thickness during film film formation.

Polyamic acid  formation

In the step of forming the polyamic acid (S120), the aromatic diamine and the aromatic dianhydride are dissolved in the second solvent to form the polyamic acid.

In this step, the polyamic acid is obtained by synthesizing an aromatic dianhydride having any one of an ether group, a ketone group and a methyl group and an ether group, a ketone group and a methyl group in a second solvent .

As the polyamic acid, it is preferable to use a thermoplastic type rather than a thermosetting type because the thermoplastic type is more effective in improving the elongation than the thermosetting type.

The aromatic diamine includes 3,3'-dimethyl- [1,1'-biphenyl] -4,4'-diamine represented by the following formula (1).

[Chemical Formula 1]

The aromatic dianhydrides also include 3,3 ', 4,4'-benzophenonetetracarbolxylic dianhydride (3,3', 4,4'-benzophenonetetracarbolxylic dianhydride) represented by the following formula .

(2)

The second solvent is preferably a polar solvent. As the polar solvent, at least one selected from DMF (dimethylformamide), NMP (N-methyl-2-pyrrolidone), DMSO (Dimethyl Sulfoxide), DMAc (Dimethylacetamide)

Coating solution formation

In the coating solution forming step (S130), a silicon rubber solution and a polyamic acid are mixed, and then a third solvent is added to form a coating solution.

In this case, the third solvent is preferably a solvent having a polarity between the first and second solvents. For this purpose, cyclohexanone (Cyclo hexanone) or ethyl lactate may be used as the third solvent.

As in the present invention, a silicone rubber solution in which silicone rubber is dissolved in a nonpolar solvent as a first solvent and a polyamic acid dissolved in a polar solvent as a second solvent are mixed with a solvent having a polarity intermediate between the first and second solvents 3 solvent, cyclohexanone or ethyl lactate is further added to make the complex, the reaction force between the solvents can be eliminated, so that the complexation can be made possible.

In addition, the coating solution may further include at least one of cyclohexanone and methyl cyclohexanone. One or more of these cyclohexanone and methyl cyclohexanone is added together with the third solvent to control the viscosity between the silicone rubber solution and the polyamic acid.

Composite Sheet Formation

In the composite sheet forming step S140, a coating solution is coated on the carrier film, dried and imidized to form a composite sheet. At this time, the application may be carried out by any one method selected from spin coating, nozzle coating, spray coating, dip coating, bar coating and the like.

The drying can be carried out at a temperature of 120 ° C or higher, more preferably 150-200 ° C, which is a temperature at which the first, second and third solvents can be removed by volatilization.

The imidization can be carried out at 200 to 300 ° C.

The composite sheet having excellent heat resistance, chemical resistance, and flexibility produced by the above process is obtained by mixing a silicone rubber solution and a polyamic acid, and then adding a third solvent having a polarity between the first and second solvents, And then coating the coating solution on the carrier substrate and drying the coating solution, thereby making it possible to composite the silicone rubber and the polyimide resin.

As a result, the composite sheet excellent in heat resistance, chemical resistance, and flexibility produced by the method according to the embodiment of the present invention is superior in flexibility and chemical resistance, which is the strength of silicone rubber, while adding high temperature heat resistance, which is a strength of polyimide resin Heat resistance, chemical resistance and flexibility at the same time.

Further, the composite sheet excellent in heat resistance, chemical resistance, and flexibility produced by the method according to the embodiment of the present invention has a considerably high elongation of 10 to 50%, so that the buffer sheet for bonding in the field of electronic materials, stretchable display) substrate material, various clothes used in a high-temperature environment, and footwear.

Example

Hereinafter, a preferred embodiment will be described in order to facilitate understanding of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims.

1. Composite Sheet Production

Example  One

A silicone rubber solution was prepared by dissolving 100 g of silicone rubber in 170 ml of methylcyclohexane.

Next, 22 g of 3,3'-dimethyl- [1,1'-biphenyl] -4,4'-diamine and 34 g of 3,3 ', 4,4'-benzophenonetracarboxylic anhydride were dissolved in DMAc To prepare polyamic acid.

Next, 43 ml of silicone rubber solution and 41 ml of polyamic acid were mixed, and then 10 ml of cyclohexanone was added to prepare a coating solution.

Next, a coating solution was coated on the carrier film to a thickness of 100 탆, dried at 180 캜 and imidized at 300 캜 to prepare a composite sheet composed of 70% by weight of silicone rubber and 30% by weight of polyimide resin.

Example  2

A silicone rubber solution was prepared by dissolving 100 g of silicone rubber in 170 ml of methylcyclohexane.

Next, 31 g of 3,3'-dimethyl- [1,1'-biphenyl] -4,4'-diamine and 45 g of 3,3 ', 4,4'-benzophenonetracarboxylic anhydride were dissolved in DMF To prepare polyamic acid.

Next, 37 ml of silicone rubber solution and 55 ml of polyamic acid were mixed, and 2 ml of ethyl lactate and 2 ml of cyclohexanone were added to prepare a coating solution.

Next, a coating solution was coated on the carrier film to a thickness of 100 탆, dried at 180 캜 and imidized at 300 캜 to prepare a composite sheet composed of silicone rubber 60 wt% and polyimide resin 40 wt%.

Comparative Example  One

A silicone rubber solution in which 90 g of silicone rubber was dissolved in 200 ml of methylcyclohexane was prepared.

Then, 22 g of 3,3'-dimethyl- [1,1'-biphenyl] -4,4'-diamine and 34 g of 3,3 ', 4,4'-benzophenonetracarboxylic anhydride were dissolved in DMF To prepare polyamic acid.

Next, 36 ml of silicone rubber solution and 63 ml of polyamic acid were mixed, and 3 ml of ethyl lactate was added to prepare a coating solution.

Next, a coating solution was coated on the carrier film to a thickness of 100 탆, dried at 180 캜 and imidized at 300 캜 to prepare a composite sheet composed of 50 wt% silicone rubber and 50 wt% polyimide resin.

2. Property evaluation

Table 1 shows the results of physical properties evaluation of the composite sheet produced according to Examples 1 and 2 and Comparative Example 1. [

1) Heat resistance

The weight loss of each temperature from 0 ° C to 1100 ° C under air pressure of 0.61MP was compared.

Weight loss (wt%) = (initial weight - weight after exposure) / (initial weight) × 100

2) Chemical resistance

The sample was subjected to a strain of 1.5% in a low-temperature chamber maintained at -20 ° C, and then allowed to stand for 30 minutes. Then, the result of cracking for 20 minutes after applying the thinner was visually observed and evaluated.

Excellent: A, Medium: B, Thirteen: C

3) Tensile strength and elongation

Tensile strength and elongation were measured according to ASTM D-1708.

[Table 1]

Referring to Table 1, it can be confirmed that the composite sheet produced according to Examples 1 and 2 has excellent heat resistance and chemical resistance, and has excellent flexibility with 13.5 ~ 48.5% elongation.

On the other hand, the composite sheet prepared according to Comparative Example 1 exhibited excellent heat resistance due to excessive addition of the polyimide resin, but the chemical resistance was moderate and the elongation was only 9.1% .

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. These changes and modifications may be made without departing from the scope of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.

S110: Silicon rubber solution forming step
S120: Polyamic acid forming step
S130: coating solution forming step
S140: composite sheet forming step

Claims (11)

delete delete delete delete (a) forming a silicone rubber solution in which silicone rubber is dissolved in a first solvent;
(b) dissolving an aromatic diamine and an aromatic dianhydride in a second solvent to form a polyamic acid;
(c) mixing the silicone rubber solution and the polyamic acid, and then adding a third solvent to form a coating solution; And
(d) applying the coating solution onto the carrier film, drying and imidizing the coating solution to form a composite sheet;
Which is excellent in heat resistance, chemical resistance and flexibility.
6. The method of claim 5,
Wherein the first solvent is a non-polar solvent,
Wherein the second solvent is a polar solvent,
And the third solvent is a solvent having a polarity of the value between the first and second solvents. The method for producing a composite sheet excellent in heat resistance, chemical resistance, and flexibility.
The method according to claim 6,
The third solvent
And at least one selected from the group consisting of cyclohexanone and ethyl lactate. The method for producing a composite sheet having excellent heat resistance, chemical resistance, and flexibility.
6. The method of claim 5,
In the step (b)
The polyamic acid
A method for producing a composite sheet excellent in heat resistance, chemical resistance, and flexibility, wherein a thermoplastic type is used.
6. The method of claim 5,
In the step (c)
The coating solution
A method for producing a composite sheet excellent in heat resistance, chemical resistance, and flexibility, which further comprises at least one of cyclohexanone and methylcyclohexane.
6. The method of claim 5,
The aromatic diamine
3,3'-dimethyl- [1,1'-biphenyl] -4,4'-diamine,
Characterized in that the aromatic dianhydride comprises 3,3 ', 4,4'-benzophenonetetracarbolxyl dianhydride (3,3', 4,4'-benzophenontetracarboxylic dianhydride). And a method for producing a composite sheet excellent in flexibility.
The method according to claim 6,
The non-polar solvent
The method for producing a composite sheet excellent in heat resistance, chemical resistance and flexibility, which comprises at least one selected from the group consisting of toluene, pentane, n-hexane, heptane, octane, carbon tetrachloride, benzene and methylcyclohexane.

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