KR102183420B1 - Method of producing film - Google Patents

Abstract

The present invention discloses a method for producing a film. The disclosed method of manufacturing a film of the present invention includes the steps of forming a first synthetic resin sheet on a first plate; Forming a second synthetic resin sheet on a second plate facing the first plate; Forming an azobenzene derivative monomer and an initiator on the first synthetic resin sheet; Bonding the first plate and the second plate with the azobenzene derivative monomer and the initiator therebetween; Heating and compressing the first plate and the second plate to form a film; And separating the film from the first plate and the second plate.
Accordingly, the film manufacturing method according to the present invention has an effect of simplifying the process and shortening the film production time by omitting the ultraviolet light irradiation process by forming a film through compression molding at a high temperature. In addition, the diffusion of the azobenzene monomer and the initiator may be promoted by stress in the hot compression molding process, and the orientation may be improved.

Description

Film manufacturing method {Method of producing film}

The present invention relates to a method for manufacturing a film, and more particularly, to a method for manufacturing a film having a short manufacturing time and manufacturing process, excellent uniformity, and excellent polarization properties.

In recent years, as the era of full-fledged information is entered, the field of display devices that visually express electrical information signals has developed rapidly, and in response to this, various flat panel display devices with excellent performance of thinner, lighter, and low power consumption. (Flat Display Device) is being developed.

As a constituent element of the flat panel display, a film having polarization characteristics having functions such as transmission and shielding of light is used. Recently, a photo-alignment method using light irradiation to induce anisotropy to a polymer film has been studied. As a film having the above polarization properties, a film containing an azo compound has been developed. The azo compound may contain an azobenzene derivative.

Films using azobenzene derivatives are formed in cis-type or trans-type by different light wavelengths. A film using an azobenzene derivative formed in cis type or trans type can transmit only light of a specific wavelength. The film using the azobenzene derivative is suitable for various flat panel display devices, vehicle-mounted applications requiring high polarization performance and durability, and display applications for high-tech instruments used in various environments.

However, the method of manufacturing a film using the azobenzene derivative has a problem in that the manufacturing process is fair, the manufacturing time is long, and uniform orientation is difficult. In more detail, it is as follows.

In the conventional process of forming the film, a polyimide (PI) alignment layer rubbed in one direction is formed on a first glass substrate. In addition, a polyimide (PI) alignment layer rubbed in one direction is formed on the second glass substrate. Thereafter, the first glass substrate and the second glass substrate are bonded to each other through an actual material with the azobenzene composition therebetween.

The azobenzene composition includes at least one or more azobenzene derivatives, and includes a photoinitiator. Preferably, an azobenzene derivative monomer, a bifunctional crosslinking agent, and a photoinitiator may be included. In order to polymerize the azobenzene derivative and the photoinitiator to form a film, heat of about 70° C. to 80° C. is applied, and ultraviolet (UV) irradiation is required. The ultraviolet (UV) light must be irradiated for 8 hours or more with a light intensity of 30mW or more. Thereafter, the film is separated from the first glass substrate and the second glass substrate to which the polyimide film is attached.

In this case, if the distribution of the azobenzene derivative is uneven during the polymerization process, the film is not oriented evenly. In addition, a large amount of unreacted azobenzene derivative remains in the interior due to the decrease in light penetration. Due to this, a thickening phenomenon occurs, only surface hardening is achieved, and it is difficult to secure transparency.

In addition, when the temperature is applied higher than the required temperature, for example, when a temperature exceeding 120° C. is applied, carbonization of the azobenzene derivative and the photoinitiator may occur. In addition, when the wavelength range of ultraviolet (UV) rays is incorrectly set, such as using a wavelength range other than the radical formation wavelength of the photoinitiator, there is a problem that polymerization itself is not performed.

That is, the azobenzene composition must be uniformly distributed to maintain a constant thickness, a constant temperature must be maintained, and the degree of polymerization must be controlled according to the wavelength and intensity of light. In addition, even if a film having transparency is formed through a normal polymerization process, there is a problem that the manufacturing time is required to be 8 hours or more.

An object of the present invention is to provide a film manufacturing method that simplifies the process and shortens the film production time by omitting the ultraviolet light irradiation process by forming a film through compression molding at a high temperature.

In addition, another object of the present invention is to provide a method for producing a film with improved orientation and promoting diffusion of an azobenzene monomer and an initiator by stress in a high-temperature compression molding process.

In addition, the present invention has another object to provide a film manufacturing method for forming a film of a large area through a high-temperature compression molding process.

The film manufacturing method of the present invention for solving the problems of the prior art as described above, the steps of forming a first synthetic resin sheet on a first plate; Forming a second synthetic resin sheet on a second plate facing the first plate; Forming an azobenzene derivative monomer and an initiator on the first synthetic resin sheet; Bonding the first plate and the second plate with the azobenzene derivative monomer and the initiator therebetween; Heating and compressing the first plate and the second plate to form a film; And separating the film from the first plate and the second plate.

The film production method according to the present invention has a first effect of simplifying the process and shortening the film production time by omitting the ultraviolet light irradiation process by forming a film through compression molding at a high temperature.

In addition, the film manufacturing method according to the present invention has a second effect of promoting diffusion of an azobenzene monomer and an initiator by stress in a high-temperature compression molding process, and improving orientation.

In addition, the film manufacturing method according to the present invention has a third effect of forming a large-area film through a high-temperature compression molding process.

1 to 4 are views showing a film manufacturing method according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided as examples in order to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. In addition, in the drawings, the size and thickness of the device may be exaggerated for convenience. The same reference numbers throughout the specification denote the same elements.

1 to 4 are views showing a film manufacturing method according to the present invention.

Referring to FIG. 1, in order to manufacture a film according to the present invention, a first plate 10 and a second plate 20 are disposed to face each other. The first plate 10 may be connected to the fixing part 12, and the second plate 20 may be connected to the moving part 22.

A first synthetic resin sheet 11 is formed on the first plate 10, and a second synthetic resin sheet 12 is formed on the second plate 20. The first synthetic resin sheet 11 and the second synthetic resin sheet 12 may be sheets formed by stretching in one direction. In addition, the first synthetic resin sheet 11 and the second synthetic resin sheet 12 may be polytetrafluoroethylene (PTFE).

Referring to FIG. 2, an azo compound 120 and an initiator 110 are formed on the first synthetic resin sheet 11 formed on the first plate 10. The azo compound 120 may be an azobenzene derivative monomer having two phenyl rings connected by a nitrogen-nitrogen double bond. More preferably, the azo compound 120 may include an azobenzene derivative monomer represented by Formula 1 below.

[Formula 1]

The R1 and R2 are each independently C=1-30 alkyl acrylate or -O-R3, and R3 is C=1-30 alkyl acrylate.

In addition, the azo compound 120 may include two or more types of azobenzene derivative monomers. Each of the two or more types of azobenzene derivative monomers may include an azobenzene derivative monomer represented by Formula 1 above. More preferably, the azo compound 120 may include an azobenzene derivative monomer represented by Formula 2 below and an azobenzene derivative monomer represented by Formula 3.

[Formula 2]

[Formula 3]

The film including the azobenzene derivative according to the present invention may be oriented by a property having photoisomerization properties for a specific wavelength of the azobenzene derivative. The azobenzene derivative undergoes photoisomerization, which is formed to have a cis-type or a trans-type depending on the wavelength of the irradiated light.

In addition, the azobenzene derivative causes a large change in structure due to the photoisomerization phenomenon, and decreases further when the distance between carbon elements in the molecule is cis type than when it is trans type. With such a decrease in the distance between molecules, the azobenzene derivative changes its physical and chemical properties such as dipole moment, refractive index, and dielectric constant. For this reason, the film including the azobenzene derivative can be applied and used in various fields.

The initiator 110 may be a thermal initiator. The initiator 110 may be an azo-based thermal initiator. More preferably, the initiator 110 may be azobis cyclohexanecarbonitrile (1,1′-azobis (cyclohexanecarbonitrile). Conventionally, in the process of manufacturing a film containing an azobenzene derivative, UV rays are irradiated for orientation. Since the process is essential, a photoinitiator was used However, in the method for producing a film according to the present invention, a film including an azobenzene derivative is formed by a high-temperature compression process instead of a long-time UV irradiation process, and a thermal initiator is required.

Referring to FIG. 3, the first plate 10 and the second plate 20 are bonded with the azo compound 120 and the initiator 110 therebetween. Thereafter, the film 100 is formed through a high-temperature compression process.

In more detail, the first plate 10 and the second plate 20 are heated to 100°C to 110°C. In addition, the second plate 20 is lowered through the moving part 22 to perform a compression process. The compression process may be performed at 0.3 MPa. The high-temperature compression process may proceed within 2 hours.

When the azo compound 120 and the initiator 110 are compressed with the heated first plate 10 and the second plate 20, an azobenzene derivative monomer, which is the azo compound 120, is polymerized with each other. At this time, the first synthetic resin sheet 11 and the second synthetic resin sheet 12 stretched in one direction allow the film 100 to be oriented.

When the film 100 is formed by a high-temperature compression process through a hot press using a heated plate, the properties of covalent bonds appear large in the orientation direction of the film 100 during polymerization of the monomer. As the stress acts vertically in the upper and lower portions of the film 100, a direct covalent bond of the azobenzene derivative monomer may strongly act in the orientation direction. That is, the high-temperature compression process through hot pressing is also advantageous for orientation of the film 100.

Conventionally oriented films were formed using a rubbing method. The rubbing method is a method in which the outer surface of the film is rubbed in a certain direction with a cloth or the like, and oriented in a certain direction according to the rubbing direction. At this time, there is a problem in that impurities such as static electricity and dust generated by friction remain on the surface of the alignment layer and affect liquid crystal molecules, thereby causing defects in the liquid crystal display.

In addition, a conventional film containing an azobenzene derivative was prepared by attaching to a glass substrate, applying an azo compound and a photoinitiator on a polyimide film oriented by a rubbing method, and irradiating ultraviolet rays at a temperature of 70 to 80 for at least 8 hours. . That is, the process is very complex, takes a lot of time, and is affected by the temperature and the wavelength of ultraviolet rays. In addition, the conventional film may have a problem in that it is not uniformly oriented over the entire area in terms of uniformity, which becomes more problematic as the total area becomes larger.

The film 100 formed by the film manufacturing method according to the present invention is to form the film 100 by a high-temperature compression process through a hot press using the heated plates 10 and 20, and the film 100 is completed in a single process. It can be done, and the rubbing process and the UV irradiation process can be omitted. That is, the process is simple and the process time can be shortened. In particular, since the process proceeds evenly at high temperature and high pressure over the entire area of the film 100, it is excellent in terms of uniformity, and it is easy to manufacture the film 100 having a large area.

Referring to FIG. 4, the film 100 is separated from the first plate 10 and the second plate 20. By separating the film 100, the manufacturing process of the film is terminated. The film 100 according to the present invention has polarization characteristics and may be a polarizing film. The film 100 is changed into a cis type or a trans type according to the wavelength range of light, so that only a specific wavelength is transmitted. In particular, since the process proceeds evenly over the entire area of the film 100 at high temperature and high pressure, it is excellent in terms of uniformity, unreacted monomers are reduced, and has superior polarization characteristics than a film formed by a conventional process.

In addition, the film 100 according to the present invention has a bending property and may be a light-driven actuator film. The film 100 may change in cis-type or trans-type according to a wavelength range, and thus its shape may be reversibly changed. In particular, as a result of irradiating light having a complex wavelength, it was confirmed that the film 100 according to the present invention has superior driving performance than a film formed by a conventional process. In addition, it was confirmed that the transparency and other mechanical properties were similar to the films formed by the conventional process.

Accordingly, the film manufacturing method according to the present invention has an effect of simplifying the process and shortening the film production time by omitting the ultraviolet light irradiation process by forming a film through compression molding at a high temperature. In addition, the diffusion of the azobenzene monomer and the initiator may be promoted by stress in the hot compression molding process, and the orientation may be improved.

It will be appreciated by those skilled in the art through the above description that various changes and modifications can be made without departing from the technical idea of the present invention. Therefore, the technical scope of the present invention should not be limited to the content described in the detailed description of the specification, but should be determined by the claims.

10: first plate 100: film
11: first synthetic resin sheet 110: initiator
20: second plate 120: azo compound
21: second synthetic resin sheet

Claims (11)

Forming a first synthetic resin sheet on the first plate;
Forming a second synthetic resin sheet on a second plate facing the first plate;
Forming an azobenzene derivative monomer and an initiator on the first synthetic resin sheet;
Bonding the first plate and the second plate with the azobenzene derivative monomer and the initiator therebetween;
Heating and compressing the first plate and the second plate to form a film; And
And separating the first plate and the first synthetic resin sheet from one surface of the film, and separating the second plate and the second synthetic resin sheet from the other surface of the film.
The method of claim 1,
The step of heating and compressing the first plate and the second plate to form a film comprises heating the first plate and the second plate to 100°C to 110°C.
The method of claim 1,
The step of forming a film by heating and compressing the first plate and the second plate is performed for 2 hours.
The method of claim 1,
The step of heating and compressing the first plate and the second plate to form a film comprises compressing the first plate and the second plate to 0.3 MPa.
The method of claim 1,
The method of manufacturing a film, characterized in that the initiator is a thermal initiator.
The method of claim 5,
The thermal initiator is azobis cyclohexanecarbonitrile (1,1'-azobis (cyclohexanecarbonitrile), characterized in that the film manufacturing method.
The method of claim 1,
The azobenzene derivative monomer comprises a compound represented by the following formula (1), characterized in that the film production method:
[Formula 1]

R1 and R2 are each independently C=1-30 alkyl acrylate or -O-R3, and R3 is C=1-30 alkyl acrylate.
The method of claim 1,
The first synthetic resin sheet and the second synthetic resin sheet is a film manufacturing method, characterized in that stretched in one direction.
The method of claim 8,
The first synthetic resin sheet and the second synthetic resin sheet is a film manufacturing method, characterized in that polytetrafluoroethylene.
The method of claim 1,
The film is a method of manufacturing a film, characterized in that the polarizing film having polarizing properties.
The method of claim 1,
The film is a film manufacturing method, characterized in that the optical drive type actuator (actuator) film having a bending property.

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