KR102181942B1 - Method for manufacturing plastic substrate and plastic substrate manufactured by the same - Google Patents

Abstract

The present invention relates to a method for producing a plastic substrate having excellent surface flatness, thickness uniformity, and heat resistance dimensional stability, and to a plastic substrate produced thereby.

Description

The manufacturing method of a plastic substrate and the plastic substrate manufactured thereby TECHNICAL FIELD [METHOD FOR MANUFACTURING PLASTIC SUBSTRATE AND PLASTIC SUBSTRATE MANUFACTURED BY THE SAME}

The present invention relates to a method for manufacturing a plastic substrate and a method for manufacturing a plastic substrate manufactured thereby.

Recently, a device for providing a 3D image to a user has been developed using a virtual reality device and an augmented reality device.

The virtual reality device or the augmented reality device may form a diffraction light guide pattern on lenses such as general glasses to display a desired image to a user. In general, a lens for a virtual reality device or an augmented reality device uses a glass substrate having a high refractive index, and the glass substrate has the advantage of having a high refractive index and light transmittance, but when it is damaged, it can cause fatal damage to the user's eyes. , Due to the heavy weight, there is a discomfort in wearing for a long time.

Accordingly, there is a need for research on a lens substrate that has high light transmittance and a high refractive index so that it can be used as a virtual reality device or an augmented reality device, and is light and relatively safe when damaged.

In the case of a plastic substrate for replacing a glass substrate, there is a problem in that physical properties such as surface flatness and thickness uniformity do not significantly exceed that of the existing glass substrate, and thus research for improvement thereof is required. In addition, in order to use the plastic substrate as a diffractive light guide lens, a deposition process or the like is performed, and at this time, there is a problem in that the plastic substrate is deformed due to a deposition process, and thus, research to improve this is required.

Korea Open Publication: KR 10-2015-0060562 A

The present invention is to provide a method for manufacturing a plastic substrate and a plastic substrate manufactured thereby. Specifically, the present invention provides a plastic substrate having excellent thickness uniformity and heat-resistant dimensional stability, and a method of manufacturing the same.

However, the problem to be solved by the present invention is not limited to the above-mentioned problems, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

An exemplary embodiment of the present invention, the step of manufacturing a plastic film; Mounting the plastic film so that the outer surface of the plastic film is exposed; Heat treatment of the plastic film to prepare a plastic substrate; Including, wherein the plastic substrate provides a method of manufacturing a plastic substrate having a change in bending distance of 15 μm or less after being left for 2 hours at a temperature of 80°C.

An exemplary embodiment of the present invention provides a plastic substrate manufactured by the method for manufacturing the plastic substrate.

In the method for manufacturing a plastic substrate according to an exemplary embodiment of the present invention, a plastic substrate having excellent surface flatness, thickness uniformity, and heat resistance dimensional stability can be easily manufactured.

The plastic substrate according to an exemplary embodiment of the present invention has excellent advantages in surface flatness, thickness uniformity, and heat resistance dimensional stability.

The effects of the present invention are not limited to the above-described effects, and effects not mentioned will be clearly understood by those skilled in the art from the present specification and the accompanying drawings.

1 is a cross-sectional view illustrating a step of curing a curable composition according to an exemplary embodiment of the present invention.
2 is a schematic view showing mounting a plastic film according to an exemplary embodiment of the present invention.
3 schematically shows measuring the bending distance of a plastic substrate according to an exemplary embodiment of the present invention.

In the present specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

In the present specification, when a member is said to be located "on" another member, this includes not only the case where the member is in contact with the other member, but also the case where another member exists between the two members.

In the present specification, the term "step (to)" or "step of" as used does not mean "step for".

Hereinafter, the present specification will be described in more detail.

An exemplary embodiment of the present invention, the step of manufacturing a plastic film; Mounting the plastic film so that the outer surface of the plastic film is exposed; Heat treatment of the plastic film to prepare a plastic substrate; Including, wherein the plastic substrate provides a method of manufacturing a plastic substrate having a change in bending distance of 15 μm or less after being left for 2 hours at a temperature of 80°C.

In the method for manufacturing a plastic substrate according to an exemplary embodiment of the present invention, a plastic substrate having excellent surface flatness, thickness uniformity, and heat resistance dimensional stability can be easily manufactured.

According to an exemplary embodiment of the present invention, in the manufacturing of the plastic film, a plastic film having excellent surface flatness and thickness uniformity may be manufactured.

Specifically, the manufacturing of the plastic film includes a flat lower substrate, a flat upper substrate, and a buffer spacer between the flat lower substrate and the flat upper substrate, and is molded by the buffer spacer. Preparing mold equipment in which the space is partitioned; Buffering the curable composition in the molding space; Compressing the curable composition under the load of the flat upper substrate, and curing the curable composition; And removing the flat upper substrate and the flat lower substrate to obtain a plastic film, wherein the curing of the curable composition may satisfy Equation 1:

[Equation 1]

{(Load of flat upper substrate + curing shrinkage force of curable composition) × 0.95} ≤ Compressive stress of buffer spacer ≤ {(load of flat upper substrate + curing shrinkage force of curable composition) × 1.05}

The method of manufacturing a plastic substrate according to an exemplary embodiment of the present invention uses a buffer spacer to minimize peeling from the substrate of the mold equipment due to shrinkage during curing of the curable composition, so that the surface flatness and thickness uniformity are very Excellent plastic film can be produced. Through this, there is an advantage of being able to manufacture a plastic substrate having a surface flatness and thickness uniformity suitable for a substrate for a diffractive light guide lens.

According to an exemplary embodiment of the present invention, the compressive stress of the buffer spacer satisfies Equation 1 above. Specifically, since the compressive stress of the buffer-type spacer has a difference within 5% of the sum of the load of the flat upper substrate and the curing contraction force of the curable composition, the curing of the curable composition in the step of curing the curable composition According to the shrinkage, the flat upper substrate comes into close contact with the curable composition. Accordingly, the manufactured plastic film exhibits excellent surface flatness, and further, thickness uniformity can be excellently implemented.

Specifically, according to an exemplary embodiment of the present invention, Equation 1 may satisfy Equation 1-1, 1-2, or 1-3 below.

[Equation 1-1]

{(Load of flat upper substrate + curing shrinkage force of curable composition) × 0.97} ≤ Compressive stress of buffer spacer ≤ {(load of flat upper substrate + curing shrinkage force of curable composition) × 1.03}

[Equation 1-2]

{(Load of flat upper substrate + curing shrinkage force of curable composition) × 0.98} ≤ Compressive stress of buffer spacer ≤ {(load of flat upper substrate + curing shrinkage force of curable composition) × 1.02}

[Equation 1-3]

{(Load of flat upper substrate + curing shrinkage force of curable composition) × 0.99} ≤ Compressive stress of buffer spacer ≤ {(load of flat upper substrate + curing shrinkage force of curable composition) × 1.01}

That is, the compressive stress of the buffer-type spacer may have a difference within 3%, within 2%, or within 1% of the sum of the load of the flat upper substrate and the curing shrinkage force of the curable composition, and the plastic manufactured accordingly The film can have better surface flatness and thickness uniformity.

In the present specification, the unit of the load, the curing contraction force, and the compressive stress of the flat upper substrate may be kgf or N.

According to an exemplary embodiment of the present invention, the buffer spacer serves to prevent the curable composition from being peeled off from the flat upper substrate according to the shrinkage caused by curing of the curable composition. Specifically, since the buffer spacer has a compressive stress in consideration of the degree of contraction of the curable composition and the load of the flat upper substrate as the curable composition is cured, the load of the flat upper substrate according to the contraction of the curable composition It is compressed, and in the step of curing the curable composition, it may serve to maintain a state in which the curable composition and the flat upper substrate are in close contact with each other.

According to an exemplary embodiment of the present invention, the load of the flat upper substrate may be 3.4 N or more and 34 N or less. Specifically, the load of the flat upper substrate may be 5.9 N or more and 27 N or less.

When the load of the flat upper substrate is within the above range, deformation due to curing shrinkage during curing of the curable composition may be minimized. In addition, when the load of the flat upper substrate is within the above range, it is possible to minimize the decrease in transmittance during photocuring of the curable composition, and also minimize non-uniformity in discharge of reaction heat during thermal curing of the curable composition. It can lead to uniform curing.

In the present specification, the curing shrinkage force of the curable composition may be measured by the following method. Specifically, after applying a certain amount of the curable composition on the lower jig using a texture analyzer device of TA company at 25° C. and 50 RH% atmosphere, the upper jig is lowered and contacted with the curable composition to record the initial value of the force. And, after raising the temperature to 90° C. and maintaining it for 5 hours, the final value of the force is recorded, and the value obtained as the difference between the final value of the force and the initial value can be measured.

In the present specification, the compressive stress of the buffer-type spacer is in an atmosphere of 25° C. and 50 RH%, when the sample area is compressed at 5 × 5 mm 2 and a compression rate of 1 mm/min using a TA texture analyzer, the deformation of the sample (( It may be a measure of the force at the moment of reaching initial thickness-thickness after deformation)/initial thickness).

According to an exemplary embodiment of the present invention, the molding space may mean an empty space provided between the flat lower substrate and the flat upper substrate partitioned by the buffer spacer.

According to an exemplary embodiment of the present invention, the step of buffering the curable composition means that the curable composition is sufficiently filled so that the curable composition is in close contact with the flat lower substrate and the flat upper substrate by injecting the curable composition into the molding space. can do. Specifically, the step of buffering the curable composition may include injecting the curable composition in an amount of 95 vol% or more, 97 vol% or more, 99 vol% or more, or preferably 100 vol% of the molding space.

According to an exemplary embodiment of the present invention, the step of buffering the curable composition includes injecting the curable composition into a molding space of a flat lower substrate provided with the buffer spacer, and laminating the flat upper substrate, or Various methods, such as a method of injecting the curable composition by providing an injection hole in the mold equipment, may be used.

1 shows a cross-section in the step of curing the curable composition. Specifically, FIG. 1 shows a curable composition 300 is injected into a molding space of a molding equipment including buffer spacers 201 and 202 provided between the flat lower substrate 101 and the flat upper substrate 102. It shows that it is buffered. In this way, after the curable composition is buffered, photocuring and/or thermal curing may be performed to prepare a plastic film.

According to an exemplary embodiment of the present invention, each of the flat lower substrate and the flat upper substrate may have a flexural modulus of 3 GPa or more. Specifically, the flexural modulus of the flat lower substrate and the flat upper substrate may be 10 GPa or more, 20 GPa or more, and 40 GPa or more, respectively. Further, the flexural modulus of the flat lower substrate and the flat upper substrate may be 70 GPa or less, 65 GPa or less, or 60 GPa or less, respectively.

When the flexural modulus of the flat lower substrate and the flat upper substrate is within the above range, the bowing phenomenon of the flat upper substrate can be minimized, so that the thickness uniformity of the manufactured plastic film can be greatly increased. There is an advantage.

According to an exemplary embodiment of the present invention, surface flatness of the flat lower substrate and the flat upper substrate may be 5 μm or less, respectively. Specifically, surface flatness of the flat lower substrate and the flat upper substrate may be 2 μm or less, or 1 μm or less, respectively. Further, surface flatness of the flat lower substrate and the flat upper substrate may be 0.5 μm or less, or 0.3 μm or less, respectively.

When surface flatness of the flat lower substrate and the flat upper substrate are within the above range, the surface flatness of the manufactured plastic film may be significantly improved than that of a general plastic film.

In the present specification, the surface flatness is measured at a point per 0.16 × 0.16 mm 2 in a 200 mm diameter area with QED's aspheric stitching interferometry (ASI) equipment at 25° C. and 50 RH% atmosphere, or the three-dimensional Using a shape measuring device, it can mean the difference between the highest and the lowest values of heights measured at intervals of 5 mm and 11.25 degrees in radius based on an arbitrary origin in a 200 mm diameter region.

According to an exemplary embodiment of the present invention, the compressive elastic modulus of the buffer-type spacer may be 0.1 MPa or more and 10 MPa or less. Specifically, the compressive elastic modulus of the buffer spacer may be 0.1 MPa or more and 5 MPa or less, 0.1 MPa or more and 3 MPa or less, or 0.1 MPa or more and 2 MPa or less.

When the compressive elastic modulus of the buffer-type spacer is within the above range, a load is uniformly transmitted to the curable composition when the flat upper substrate is in contact, thereby increasing the thickness uniformity of the plastic film.

In the present invention, the compressive elastic modulus of the buffer-type spacer is the force measured when compressing with a specimen area of 5 × 5 mm 2 and a compression speed of 1 mm/min using a TA texture analyzer in an atmosphere of 25° C. and 50 RH%. It can mean the slope for specimen deformation ((initial thickness-thickness after deformation)/initial thickness). In addition, when the buffer spacer is composed of two or more different layers, the compressive modulus of the buffer spacer is the force measured when the laminated specimen is prepared with an area of 5 × 5 mm 2 and compressed at a compression speed of 1 mm/min. It can mean a slope for deformation ((initial thickness-thickness after deformation)/initial thickness).

According to an exemplary embodiment of the present invention, the buffer spacer may be a structure in which an inelastic layer and an elastic layer are stacked, an elastic layer is provided between the inelastic layers, or an inelastic layer is provided between the elastic layers.

The buffer-type spacer may be designed in consideration of the degree of shrinkage of the curable composition, and the inelastic layer of the buffer-type spacer serves as a support, and the elastic layer controls the height change according to the contraction of the curable composition. Can play a role.

According to an exemplary embodiment of the present invention, the curable shrinkage rate of the curable composition may be 15% or less. Specifically, the curable shrinkage rate of the curable composition may be 1% or more and 15% or less, 1% or more and 12% or less, or 1% or more and 10% or less.

The curing shrinkage rate of the curable composition may be derived as in General Formula 1 below.

[General Formula 1]

Curing shrinkage (%) = {(volume before curing-volume after complete curing) / volume before curing} × 100.

According to an exemplary embodiment of the present invention, the thickness of the plastic film may be 400 μm or more and 2,000 μm or less, and the thickness variation of the plastic film may be within 1%.

Specifically, as the thickness deviation value of the plastic film is lower, the thickness uniformity of the plastic film may be higher. That is, the plastic film manufactured according to the exemplary embodiment of the present invention may have a thickness variation of less than 1%, and thus have very excellent thickness uniformity. That is, the plastic substrate manufactured using the plastic film has excellent surface flatness and thickness uniformity, and thus has an advantage suitable for use as a lens substrate such as a virtual reality device and an augmented reality device.

According to an exemplary embodiment of the present invention, the thickness of the plastic film may be adjusted according to a separation distance between the flat lower substrate and the flat upper substrate and a curing shrinkage rate of the curable composition. Further, it is possible to adjust the thickness of the plastic substrate within the above range according to the use of the plastic substrate.

In addition, the thickness deviation of the plastic film may be derived as shown in the following general formula 2.

[General Formula 2]

Thickness deviation (%) = (maximum deviation/average thickness) × 100

In the present specification, the maximum thickness or minimum thickness can be measured using a contact measurement method using Mitsutoyo's Digimatic Thick 547-401 equipment in an atmosphere of 25° C. and 50 RH%. In addition, in this specification, the maximum thickness or minimum thickness can be measured using a non-contact measurement method using Micro-Epsilon's IFS-2405-1 or IFC-2451-MP equipment at 25° C. and 50 RH%. have.

In the present specification, the average thickness of the member is at 25° C. and 50 RH% atmosphere, using a contact measurement method using Mitsutoyo's Digimatic Thick 547-401 equipment, using a random point of the randomly placed specimen as the origin, and a radius of 10 It may be an average value of the thickness measured at intervals of mm and 22.5 degrees. In addition, in the present specification, the average thickness of the member is in an atmosphere of 25° C. and 50 RH%, using a non-contact measurement method using Fiber Pro's Optical Waper Thickness Measurement system (OWTM) equipment, to determine any point of the randomly placed specimen. As the origin, it may be an average value of thickness measured at intervals of 10 mm in radius and 22.5 degrees.

According to an exemplary embodiment of the present invention, the curable composition may be a photocurable composition or a thermosetting composition. Specifically, the curable composition may be a thermosetting composition.

According to an exemplary embodiment of the present invention, each of the flat lower substrate and the flat upper substrate may be a transparent substrate. Specifically, the planar lower substrate and the planar upper substrate may each be an organic substrate, which may effectively perform photocuring of the curable composition due to excellent light transmission properties.

In an exemplary embodiment of the present invention, a plastic film may be obtained by removing the flat upper substrate and the flat lower substrate. Removing the flat upper substrate and the flat lower substrate means separating the flat upper substrate and the flat lower substrate from the plastic film, which is a cured product of the curable composition, after curing of the curable composition is completed can do.

According to an exemplary embodiment of the present invention, the surfaces of the flat lower substrate and the flat upper substrate may each be surface-treated with a release agent. The releasing agent can be applied without limitation as long as it is generally used in the art. For example, a fluorine-based silane coupling agent may be used as the release agent, and the surfaces of the flat lower substrate and the flat upper substrate may be surface coated. Surfaces of the flat lower substrate and the flat upper substrate surface-treated with a release agent may mean a surface adjacent to and/or in contact with the curable composition.

When the surfaces of the flat lower substrate and the flat upper substrate are surface-treated using the release agent, in the step of obtaining the plastic film, damage to the surface of the plastic film is minimized, and the flat lower substrate and the The flat upper substrate can be removed.

According to an exemplary embodiment of the present invention, the curable composition may be applied without limitation as long as it is for manufacturing a plastic film. Specifically, the curable composition may be applied without limitation as long as it can produce a plastic film using mold casting.

According to an exemplary embodiment of the present invention, in the step of mounting the plastic film, the plastic film may be mounted so that the outer surface of the plastic film is exposed to a heat treatment process. Specifically, the step of mounting the plastic film may include mounting the plastic film so that one side and the other side of the plastic film are heat treated.

As a method of mounting the plastic film, a general method of mounting a member in the art may be adopted and used without limitation. For example, by attaching a cradle to the side of the plastic film, one side and the other side of the plastic film may be heat treated. In addition, an adhesive tape may be attached to the side surface of the plastic film, and the adhesive tape may be hung on a cradle so that one side and the other side of the plastic film are heat treated.

2 is a schematic view showing mounting a plastic film according to an exemplary embodiment of the present invention. Specifically, FIG. 2 is a view showing that an adhesive tape is attached to the side (F3) of the plastic film 400, and the adhesive tape is hung on a cradle to expose one surface (F1) and the other surface (F2) of the plastic film 400 to be.

According to an exemplary embodiment of the present invention, one surface and the other surface of the plastic film may mean a surface having the largest area among the surfaces of the plastic film, and one surface and the other surface of the plastic film may be opposed to each other.

According to an exemplary embodiment of the present invention, by mounting the outer surface of the plastic film, specifically one side and the other side of the plastic film to be exposed to a heat treatment process, and heat treatment of one side and the other side of the plastic film, a plastic substrate having excellent heat resistance dimensional stability is obtained. Can be manufactured. Specifically, by heat-treating the manufactured plastic film, a plastic substrate having improved durability against heat deformation may be manufactured. Through this, even when the plastic substrate is exposed to high temperature conditions by performing a deposition process or the like on the plastic substrate, deformation of the plastic substrate can be suppressed. That is, by heat-treating the plastic film in advance, it is possible to suppress the occurrence of deformation when the plastic substrate to be produced is exposed to high temperature conditions.

In the case of heat treatment by placing the other side of the plastic film on a glass plate, only one side of the plastic film is mainly heat treated, so that deformation occurs in the plastic film, and durability against heat deformation may not be greatly improved.

On the other hand, according to an exemplary embodiment of the present invention, by heat-treating one side and the other side of the plastic film, the surface of the plastic film can be evenly heat-treated, and thermal deformation of the plastic film can be effectively suppressed. Through this, it is possible to manufacture a plastic substrate having excellent heat resistance dimensional stability.

In addition, by mounting the plastic film so that the entire area of one side and the other side of the plastic film is exposed, the one side and the other side of the plastic film can be evenly heat-treated, and the heat-resistant dimensional stability of the plastic substrate can be further improved.

According to an exemplary embodiment of the present invention, the manufacturing of the plastic substrate may include heat-treating the plastic film at a temperature of 90° C. or more and 110° C. or less for 60 minutes or more and 180 minutes or less. Specifically, the plastic film may be heat-treated at a temperature of 95°C to 105°C, 98°C to 103°C, 90°C to 100°C, or 97°C to 110°C. In addition, the heat treatment time of the plastic film may be adjusted to 70 minutes or more and 150 minutes or less, 90 minutes or more and 120 minutes or less, or 80 minutes or more and 130 minutes or less. By controlling the heat treatment temperature and heat treatment time of the plastic film in the above-described range, a plastic substrate having excellent heat resistance dimensional stability can be manufactured. Specifically, when the heat treatment temperature and heat treatment time are within the above ranges, durability against heat deformation of the manufactured plastic substrate may be improved.

According to an exemplary embodiment of the present invention, the heat treatment of the plastic film can be used without limitation in a method and apparatus for heat treatment of a member in the art. For example, after mounting the plastic film on a cradle so that the outer surface of the plastic film is exposed, the plastic film may be heat-treated by placing it in an oven. In this case, the outer surface of the plastic film may be set so as not to be directly exposed to the oven hot air, and the plastic film may be heat treated. For example, when the plastic film is heat-treated using a convection oven, by placing a plate material between the hot air inlet of the convection oven and the plastic film, and between the inlet and the plastic film, the plastic film is directly exposed to the oven hot air. Can be prevented.

By setting the outer surface of the plastic film not to be directly exposed to the oven hot air, it is possible to prevent the plastic film from shaking during the heat treatment process of the plastic film, thereby effectively suppressing the occurrence of deformation in the plastic film.

According to an exemplary embodiment of the present invention, the plastic substrate may have a deflection distance change amount of 15 μm or less after being left for 2 hours at a temperature of 80°C. Specifically, compared to the initial bending distance of the plastic substrate, the amount of change in which the bending distance is changed after leaving the plastic substrate at a temperature of 80° C. for 2 hours may be 15 μm or less, 13 μm or less, 10 μm or less, or 8 μm or less. . The plastic substrate satisfying the amount of change in the bending distance described above has an advantage of excellent heat resistance dimensional stability.

In addition, the amount of change in the bending distance of the plastic substrate may be an absolute value of a difference between the initial bending distance of the plastic substrate and the bending distance after leaving the plastic substrate in a temperature condition of 80° C. for 2 hours. At this time, the bending distance of the plastic substrate is set to the virtual plane (minimum square plane) closest to the shape of the plastic substrate, and the longest length of the vertical length from the virtual plane to the upper portion of the plastic substrate along the upper side, It may be the sum of the longest lengths of the vertical lengths from the virtual plane to the lower portion of the plastic substrate along the bottom.

In the present specification, the bending distance of the plastic substrate may be measured by the following method. Prepare a sample with warpage, and in an atmosphere of 25° C. and 50 RH%, using OWTM (Optical Wafer Thickness Microgauge; Fiber Pro), with respect to the cross section of the sample, 1 mm in the x-axis and y-axis directions. Measure the height at which warpage occurs at intervals. Thereafter, the reference height is set through the height calculated using the least squares method, and the first distance, which is the longest vertical length from the reference height to the upper part of the member, is calculated along the upper direction of the member, and A second distance, which is the longest length of the vertical length from the reference height to the lower portion of the member along the direction, may be calculated, and a sum of the first distance and the second distance may be used as the bending distance value. In this case, the upper part of the member may refer to a protruding part of the member in which warping has occurred, and the lower part of the member may refer to a corner part of the member.

3 schematically shows measuring the bending distance of a plastic substrate according to an exemplary embodiment of the present invention. Specifically, FIG. 3 is the longest length of the vertical length from the reference height to the upper portion of the plastic substrate along the upper direction of the plastic substrate 500 with respect to the reference height of the plastic substrate 500 set using the least squares method. It represents the first distance and the second distance, which is the longest length of the vertical length from the reference height to the lower portion of the plastic substrate along the lower direction of the plastic substrate 500.

According to an exemplary embodiment of the present invention, the plastic substrate may be left for 2 hours under a temperature condition of 80°C using a hot plate. Specifically, after placing one side of the plastic substrate in contact with a hot plate set at a temperature of 80 °C, the plastic substrate may be left for 2 hours. Making one surface of the plastic substrate in contact with the hot plate may be similar to performing a deposition process on one surface of the manufactured plastic substrate. Through this, there is an advantage of being able to confirm in advance whether the plastic substrate has excellent heat resistance dimensional stability with respect to a high temperature process such as a deposition process.

The method of manufacturing a plastic substrate according to an exemplary embodiment of the present invention may further include cooling the plastic substrate at a cooling rate of 5° C./min or less. Specifically, after heating the plastic film to prepare a plastic substrate, the plastic substrate was 5°C/min or less, 4°C/min or less, 2.5°C/min or less, 1°C/min or less, 0.7°C/min or less, By cooling at a cooling rate of 0.5° C./min or less, or 0.2° C./min or less, a plastic substrate may be finally prepared. By cooling the plastic substrate at a cooling rate within the above-described range, the heat-resistant dimensional stability of the plastic substrate can be more uniformly maintained. Specifically, when the plastic substrate is cooled at a cooling rate within the above-described range, it is possible to suppress the occurrence of stress distribution and deformation of the plastic substrate due to a difference in the thickness of the plastic substrate and the shrinkage rate in the plane direction. Through this, it is possible to easily implement a plastic substrate having excellent surface flatness.

The method of manufacturing a plastic substrate according to an exemplary embodiment of the present invention may further include processing the plastic substrate. Specifically, depending on the use of the plastic substrate, the shape of the plastic substrate may be processed differently. Processing the plastic substrate can be used without limitation a method and apparatus for processing a member in the art. For example, the manufactured plastic substrate can be processed into a specific shape using an end mill.

An exemplary embodiment of the present invention provides a plastic substrate manufactured by the method for manufacturing the plastic substrate.

According to an exemplary embodiment of the present invention, the plastic substrate may satisfy the following physical properties.

According to an exemplary embodiment of the present invention, the plastic substrate may have a photorefractive index of 1.6 or more at a wavelength of 532 nm. Specifically, the plastic substrate may have a photorefractive index of 1.65 or more at a wavelength of 532 nm.

In the case of a general glass substrate, the photorefractive index is 1.6 or more at a wavelength of 532 nm. Although the plastic substrate according to an exemplary embodiment of the present invention is made of a plastic material, since it can implement a light refractive index equivalent to that of the glass substrate, there is an advantage of being able to replace the glass substrate.

According to an exemplary embodiment of the present invention, the glass transition temperature of the plastic substrate may be 40 °C or higher. In the case of a display device such as a virtual reality device, an augmented reality device, or a wearable device, continuous image transmission and output may be performed, and accordingly, the temperature of the lens substrate may increase. Since the plastic substrate according to the exemplary embodiment of the present invention can be implemented with a glass transition temperature of 40° C. or higher, even when used as a lens substrate of a display device, there is an advantage of minimizing changes in physical properties according to temperature.

According to an exemplary embodiment of the present invention, the plastic substrate may be a substrate for a diffractive light guide lens. Specifically, the plastic substrate may be a substrate for a diffractive light guide lens of a wearable device.

An exemplary embodiment of the present invention provides a wearable device including the plastic substrate. Specifically, the wearable device may be an augmented reality device or a virtual reality device. The plastic substrate may be included as a lens substrate of the wearable device, and the plastic substrate may be applied as a substrate for inputting, moving, and transmitting optical information including a diffraction light guide pattern portion on one surface.

Since the plastic substrate according to an exemplary embodiment of the present invention has a high optical refractive index, when used as a lens substrate of a wearable device, optical loss can be minimized and optical information can be moved. Furthermore, since the plastic substrate has a high glass transition temperature, it is possible to implement high durability by minimizing changes in physical properties due to heat caused by the operation of the wearable device.

Hereinafter, examples will be described in detail to illustrate the present invention in detail. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention is not construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely describe the present invention to those of ordinary skill in the art.

Preparation of curable composition

Bis(2,3-epithiopropyl) disulfide 88.5 parts by weight, 2,2'-thiodiethanethiol 6.5 parts by weight, isophorone di A curable composition comprising 5.0 parts by weight of isocyanate (Isophorone diisocyanate) and 0.07 parts by weight of tetrabutylphosphonium bromide was prepared.

The curing shrinkage force of the prepared curable composition was 2.00 × 10 ^-4 N/mm 3, as measured by the method of measuring the curing shrinkage force described above.

Manufacture of plastic film

Manufacturing example One

As the lower substrate, a glass substrate with a flexural modulus of 70 GPa, a surface flatness of 0.5 µm, a thickness of 30 ㎜, and a diameter of 200 ㎜ was used. After forming a molding space by providing a silicone buffer spacer at intervals of 120° so as to contact the circumference of the lower substrate, the prepared curable composition is injected into the molding space, and then as an upper substrate, a flexural modulus of 70 GPa, a load The curable composition was buffered in the molding space using this 8.2 N, a glass substrate having a diameter of 200 mm and a surface flatness of 0.5 µm.

Further, the curable composition was placed in a convection oven manufactured by Jeio Tech, and thermally cured at 90° C. for 5 hours to prepare a plastic film. Thereafter, the plastic film was processed with an end mill, and cut into a rectangular shape having a width of 80 mm and a length of 60 mm.

Manufacturing example 2

A plastic film was manufactured in the same manner as in Preparation Example 1, except that the height of the spacer was adjusted to 1,007 µm. Thereafter, the plastic film was processed with an end mill, and cut into a rectangular shape having a width of 80 mm and a length of 60 mm.

Specific matters according to Preparation Example 1 and Preparation Example 2 and physical properties of the manufactured plastic film are shown in Table 1 below.

Spacer compressive modulus of elasticity
(MPa) Spacer height
(㎛) Spacer compressive stress
(N) Shrinkage force of curable composition
(N) Load on upper board
(N) Diameter of plastic substrate
(Mm) Plastic substrate thickness
(㎛) Thickness deviation
(%) Exterior Manufacturing Example 1 1.0 427 9.62 1.46 8.2 150 413±2 0.4 Good Manufacturing Example 2 1.0 1,007 11.56 3.56 8.2 150 961±4 0.4 Good

Manufacturing example 3

Using an ultraviolet crosslinked polyolefin-based elastic layer with a compressive modulus of 0.16 MPa and an inelastic layer made of glass with a compressive modulus of 70 GPa, the structure of the spacer is made of an elastic layer (171 µm)/non-elastic layer (829 µm). A plastic film was manufactured in the same manner as in Preparation Example 1 except for the change. Thereafter, the plastic film was processed with an end mill, and cut into a rectangular shape having a width of 80 mm and a length of 60 mm.

Manufacturing example 4

Using an ultraviolet crosslinked polyolefin-based elastic layer with a compressive modulus of 0.16 MPa and an inelastic layer made of glass with a compressive modulus of 70 GPa, the structure of the spacer is inelastic layer (198 µm)/elastic layer (164 µm)/non-elastic layer A plastic film was manufactured in the same manner as in Preparation Example 1, except that the structure was changed to (198 μm). Thereafter, the plastic film was processed with an end mill, and cut into a rectangular shape having a width of 80 mm and a length of 60 mm.

Manufacturing example 5

Using an elastic layer made of silicon with a compressive modulus of 1.0 MPa and an inelastic layer made of glass with a compressive modulus of 70 GPa, the structure of the spacer is changed to an elastic layer (542 µm)/non-elastic layer (500 µm). A plastic film was manufactured in the same manner as in Example 1, except for one. Thereafter, the plastic film was processed with an end mill, and cut into a rectangular shape having a width of 80 mm and a length of 60 mm.

Specific matters according to Preparation Examples 3 to 5 and the physical properties of the manufactured plastic film are shown in Table 2 below.

Spacer compression modulus
(MPa) Spacer
Height
(㎛) Spacer compressive stress
(N) Shrinkage force of curable composition
(N) Load on upper board
(N) Diameter of plastic substrate
(Mm) Plastic substrate thickness
(㎛) Thickness deviation
(%) Exterior Elastic layer Inelastic layer Elastic layer Inelastic layer Manufacturing Example 3 0.16 70,000 171 829 11.56 3.4 8.2 150 959±2 0.2 Good Manufacturing Example 4 0.16 70,000 164 198/198 10.02 1.86 8.2 150 526±3 0.3 Good Manufacturing Example 5 1.0 70,000 542 500 11.40 3.24 8.2 150 913±2 0.2 Good

compare Manufacturing example One

A plastic film was manufactured in the same manner as in Preparation Example 1, except that a polycarbonate-based spacer having a compressive modulus of 4 GPa and a height of 502 μm was used. Thereafter, the plastic film was processed with an end mill, and cut into a rectangular shape having a width of 80 mm and a length of 60 mm.

compare Manufacturing example 2

Using a polycarbonate-based elastic layer with a compressive modulus of 4 GPa and an inelastic layer made of glass with a compressive modulus of 70 GPa, the structure of the spacer is changed to an elastic layer (502 µm)/non-elastic layer (492 µm). Except for one, a plastic film was manufactured in the same manner as in Preparation Example 1. Thereafter, the plastic film was processed with an end mill, and cut into a rectangular shape having a width of 80 mm and a length of 60 mm.

Specific matters according to Comparative Preparation Example 1 and Comparative Preparation Example 2 and physical properties of the manufactured plastic film are shown in Table 3 below.

Spacer compression modulus
(MPa) Spacer height
(㎛) Spacer compressive stress
(N) Shrinkage force of curable composition
(N) Load on upper board
(N) Diameter of plastic substrate
(Mm) Plastic substrate thickness
(㎛) Thickness deviation
(%) Exterior Elastic layer Inelastic layer Elastic layer Inelastic layer Comparative Preparation Example 1 4,000 - 502 - Below detection limit 1.76 8.2 150 478 8.4 Bad Comparative Preparation Example 2 4,000 70,000 502 492 Below detection limit 3.52 8.2 150 949 6.3 Bad

Evaluation of the appearance of the plastic films in Tables 1 to 3 was determined by visually determining whether there was streaking of the plastic film. If no stria was found visually, it was evaluated as good, and if streaking was found visually, it was evaluated as poor.

Further, the compressive modulus of elasticity of the spacers in Tables 1 to 3, compressive stress of the spacer, shrinkage of the curable composition, and thickness deviation were measured as described above. For reference, the spacers of Comparative Preparation Example 1 and Comparative Preparation Example 2 were at a level at which compressive stress could not be measured, that is, at a level that was not substantially compressed.

According to Tables 1 to 3, it can be seen that the plastic film manufactured according to the manufacturing example according to the exemplary embodiment of the present invention exhibits very low thickness variation, and thus has a high thickness uniformity. On the other hand, in the case of Comparative Preparation Example 1 and Comparative Preparation Example 2, the compressive modulus of the spacer was too high, and as in Preparation Example, it was not possible to maintain adhesion with the upper substrate when the curable composition was cured due to curing, and thus, very poor thickness deviation. Since it represents, it can be confirmed that it has a low thickness uniformity. Further, it can be seen that the plastic film prepared in Comparative Preparation Example exhibits streaking on the surface due to the separation from the upper substrate during curing, and the appearance characteristics are also poor.

Accordingly, according to an exemplary embodiment of the present invention, a plastic film having excellent thickness uniformity and surface flatness can be manufactured, and a plastic substrate having excellent thickness uniformity and surface flatness can be provided by using this.

Manufacture of plastic substrates

Example One

The plastic film prepared in Preparation Example 1 was prepared. Thereafter, as shown in FIG. 2, an adhesive tape was attached to one side of the plastic film, and the adhesive tape was hung on the clamps of the holder. Thereafter, the plastic film and the holder were placed in an oven (OF-21E, Jeio Tech), and heat-treated at a temperature of 100° C. for 2 hours. At this time, a PET film having a thickness of 250 μm was placed between the hot air inlet of the oven hot air and the plastic film, and between the suction port and the plastic film, so that the plastic film was not directly exposed.

Thereafter, after stopping the operation of the oven, after leaving the plastic film in the oven for 4 hours, the plastic film was taken out to finally prepare a plastic substrate. At this time, the cooling rate of the plastic film was about 0.2°C/min.

Example 2

A plastic substrate was prepared in the same manner as in Example 1, except that the plastic film was immediately taken out of the oven after stopping the operation of the oven, and the cooling rate of the plastic film was adjusted to about 5°C/min.

Comparative example One

The plastic film prepared in Preparation Example 1 was prepared, and the heat treatment process was not performed.

Comparative example 2

The plastic film was placed on the glass plate so that one side of the plastic film prepared in Preparation Example 1 was in contact with the glass plate, and the plastic film was heat-treated in the same manner as in Example 1. After stopping the operation of the oven, after leaving the plastic film in the oven for 4 hours, the plastic film was taken out to finally prepare a plastic substrate. At this time, the cooling rate of the plastic film was about 0.2°C/min.

The bending distances of the plastic substrates in Examples 1 to 2 and Comparative Examples 1 to 2 were measured by the method described above, and are shown in Table 1 below.

Evaluation of heat resistance of plastic substrates

The plastic substrates in Examples 1 to 2 and Comparative Examples 1 to 2 were prepared, and heat resistance evaluation was conducted as follows.

It was placed on a hot plate set at 80° C. (RCT basic IKAMAG, Ika Corporation) so that one side of the plastic substrate was in contact, and allowed to stand for 2 hours. Thereafter, the amount of change in the bending distance of the plastic substrate after heat resistance evaluation compared to the bending distance of the plastic substrate before heat resistance evaluation (before placing it on the hot plate) was measured by the above-described measuring method, and is shown in Table 4 below.

Initial bending distance (㎛) After heat resistance evaluation
Bending distance change amount (㎛) Example 1 32.3 0.6 Example 2 41.1 12.4 Comparative Example 1 44.1 21.7 Comparative Example 2 124.0 17.3

Referring to Table 4, after mounting so that one side and the other side of the plastic film are exposed, heat treatment is performed at a temperature of 90° C. or more and 110° C. for 60 minutes or more and 180 minutes or less. The plastic substrate confirmed that the amount of change in the bending distance after heat resistance evaluation was 15 µm or less. That is, it can be seen that the plastic substrate produced by the method according to the present invention has excellent heat resistance dimensional stability and surface flatness.

In addition, referring to Examples 1 and 2, it was confirmed that the amount of change in the bending distance after heat resistance evaluation can be reduced by slowing the cooling rate of the plastic substrate after heat treatment, thereby improving the heat resistance dimensional stability of the plastic substrate. It can be seen that the plastic substrate can be effectively suppressed from being deformed.

On the other hand, in the case of Comparative Example 2, in which the plastic substrate of Comparative Example 1 without performing the heat treatment process, the amount of change in the bending distance after heat resistance evaluation exceeded 15 µm, and the plastic film was placed on the glass plate and heat treated so that one side of the plastic film was in contact with the glass plate It was confirmed that the initial bending distance was very large, and the amount of change in bending distance after heat resistance evaluation also exceeded 15 μm.

Accordingly, the method of manufacturing a plastic substrate according to an exemplary embodiment of the present invention can manufacture a plastic substrate having excellent surface flatness, thickness uniformity, and heat resistance dimensional stability.

101: flat bottom substrate
102: flat upper substrate
201, 202: buffer spacer
300: curable composition
400: plastic film
500: plastic substrate

Claims (14)

Manufacturing a plastic film;
Mounting the plastic film so that the outer surface of the plastic film is exposed;
Heat treatment of the plastic film to prepare a plastic substrate; Including,
The plastic substrate is a method of manufacturing a plastic substrate having a change in bending distance of 15 μm or less after being left for 2 hours at a temperature of 80°C.
The method according to claim 1,
A method for producing a plastic substrate by heat-treating the plastic film at a temperature of 90° C. or more and 110° C. or less for 60 minutes or more and 180 minutes or less.
The method according to claim 1,
The step of mounting the plastic film includes mounting the plastic film to heat-treat one side and the other side of the plastic film.
The method according to claim 1,
A method of manufacturing a plastic substrate further comprising cooling the plastic substrate at a cooling rate of 5° C./min or less.
The method according to claim 1,
The step of preparing the plastic film,
Preparing a mold equipment including a flat lower substrate, a flat upper substrate, and a buffer spacer between the flat lower substrate and the flat upper substrate, wherein a molding space is partitioned by the buffer spacer;
Buffering the curable composition in the molding space;
Compressing the curable composition under the load of the flat upper substrate, and curing the curable composition; And
Removing the flat upper substrate and the flat lower substrate to obtain a plastic film; Including,
The step of curing the curable composition is a method for producing a plastic substrate satisfying the following Equation 1:
[Equation 1]
{(Load of flat upper substrate + curing shrinkage force of curable composition) × 0.95} ≤ Compressive stress of buffer spacer ≤ {(load of flat upper substrate + curing shrinkage force of curable composition) × 1.05}.
The method of claim 5,
The method of manufacturing a plastic substrate having a flexural modulus of 3 GPa or more, respectively, of the flat lower substrate and the flat upper substrate.
The method of claim 5,
The method of manufacturing a plastic substrate having a surface flatness of 5 μm or less, respectively, of the flat lower substrate and the flat upper substrate.
The method of claim 5,
The method of manufacturing a plastic substrate having a compressive modulus of elasticity of 0.1 MPa or more and 10 MPa or less of the buffer spacer.
The method of claim 5,
The buffer spacer is a method of manufacturing a plastic substrate having a structure in which an inelastic layer and an elastic layer are stacked, an elastic layer is provided between the inelastic layers, or an inelastic layer is provided between the elastic layers.
The method of claim 5,
The method for producing a plastic substrate, wherein the curable shrinkage of the curable composition is 15% or less.
The method according to claim 1,
The plastic film has a thickness of 400 μm or more and 2,000 μm or less, and a thickness deviation of the plastic film is within 1%.
A plastic substrate manufactured by the method for manufacturing a plastic substrate according to claim 1.
The method of claim 12,
The plastic substrate is a plastic substrate having a light refractive index of 1.6 or more at a wavelength of 352 nm.
The method of claim 12,
The plastic substrate is a plastic substrate for a diffractive light guide lens.

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