KR20210088249A - Method for manufacturing plastic substrate - Google Patents

Abstract

The present specification relates to a method for manufacturing a plastic substrate for an optical lens that is excellent in surface flatness and thickness uniformity, is excellent in strength and hardness, is capable of realizing various colors, and is capable of realizing a high refractive index. The present invention comprises the steps of: preparing a mold apparatus comprising a flat lower substrate, a flat upper substrate, and a cushioning spacer between the flat lower substrate and the flat upper substrate, wherein a molding space is partitioned by the cushioning spacer; buffering a 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 substrate.

Description

Manufacturing method of a plastic substrate {METHOD FOR MANUFACTURING PLASTIC SUBSTRATE}

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

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

A virtual reality device or an augmented reality device may form a diffraction light guide pattern on a lens 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, but the glass substrate has the advantage of having a high refractive index and light transmittance, but when it is broken, fatal damage to the user's eye can be applied. , It is heavy and uncomfortable to wear for a long time.

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

In the case of a plastic substrate to replace a glass substrate, physical properties such as surface flatness and thickness uniformity do not significantly reach the existing glass substrate, and there is a problem in that it is difficult to implement a high refractive index compared to glass. the current situation.

Korean Publication: KR 10-2015-0060562 A

The present invention is an optical lens that is lighter than glass or tempered glass used for conventional display substrates, has excellent surface flatness and thickness uniformity, has excellent strength and hardness, can implement various colors, and can implement high refractive index. To provide a method for manufacturing a plastic substrate for

Preparing a mold equipment comprising a flat lower substrate, a flat upper substrate, and a cushioning spacer between the flat lower substrate and the flat upper substrate, wherein a molding space is partitioned by the cushioning spacer;

buffering a curable composition in the molding space;

compressing the curable composition under a load of the flat upper substrate, and curing the curable composition; and

Including; removing the flat upper substrate and the flat lower substrate to obtain a plastic substrate;

The curable composition includes an episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups,

The weight ratio of the thiol compound and the aromatic ring compound having two or more hydroxyl groups is 7:3 to 9:1,

Compressing the curable composition under a load of the flat upper substrate, and curing the curable composition, provides a method of manufacturing a plastic substrate satisfying Equation 1 below.

[Equation 1]

{(load of flat top substrate + curing shrinkage force of curable composition) Х 0.95} ≤ compressive stress of cushioning spacer ≤ {(load of flat top substrate + curing shrinkage force of curable composition) Х 1.05}.

Hereinafter, a method for manufacturing a plastic substrate according to a specific embodiment of the present invention will be described in more detail.

In the present specification, when a part "includes" a certain component, this 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 a case in which a member is in contact with another member but also a case in which another member exists between the two members.

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

In this specification, terms such as first and second are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

As used herein, the definition of 'episulfide compound' refers to a compound containing one or more episulfide, wherein the episulfide refers to a compound in which the oxygen (O) atom of the epoxide is substituted with a sulfur (S) atom.

As used herein, the definition of 'thiol compound' refers to a compound containing at least one thiol group (-SH).

As used herein, the term 'curing' includes both thermosetting and photocuring, and the term 'curable composition' refers to a composition capable of being thermosetting and/or photocuring.

In the present specification, high refractive index means about 1.6 or more in a wavelength region of 350 to 800 nm or a wavelength of 532 nm.

According to an embodiment of the invention, a flat lower substrate, a flat upper substrate, and a cushioning spacer between the flat lower substrate and the flat upper substrate, wherein a molding space is partitioned by the cushioning spacer preparing the mold equipment; buffering a curable composition in the molding space; compressing the curable composition under a 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 substrate, wherein the curable composition contains an episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups, , The weight ratio of the thiol compound and the aromatic ring compound having two or more hydroxyl groups is 7:3 to 9:1, 7:3 to 8.5:1.5, or 7:3 to 8:2, and the load of the flat upper substrate In the step of compressing the curable composition, and curing the curable composition, a method of manufacturing a plastic substrate satisfying Equation 1 is provided.

The present inventors inject a curable composition containing an episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups in a specific weight ratio into the molding space of the mold equipment having the above-described specific structure, and then cure it to satisfy Equation 1 In the case of manufacturing a plastic substrate by the above-described manufacturing method, it minimizes the phenomenon of 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, and the strength and hardness are excellent And, it was discovered that a plastic substrate capable of implementing various colors and realizing a high refractive index can be manufactured, leading to the present invention.

Specifically, the step of compressing the curable composition under the load of the flat upper substrate and curing the curable composition included in the method for manufacturing the plastic substrate may satisfy Equation 1 below.

[Equation 1]

{(load of flat top substrate + curing shrinkage force of curable composition) Х 0.95} ≤ compressive stress of cushioning spacer ≤ {(load of flat top substrate + curing shrinkage force of curable composition) Х 1.05}.

Specifically, in Equation 1, since the compressive stress of the cushioning spacer has a difference within 5% of the sum of the load of the flat upper substrate and the curing shrinkage force of the curable composition, in the step of curing the curable composition, the When the curable composition is cured, the flat upper substrate may be in close contact with the curable composition according to shrinkage. Accordingly, the manufactured plastic substrate exhibits excellent surface flatness, and furthermore, excellent thickness uniformity can be achieved.

On the other hand, if the compressive stress of the cushioning spacer is less than {(load of flat upper substrate + curing shrinkage force of curable composition) Х 0.95}, curing may be completed before equilibrium is reached, resulting in non-uniformity in the thickness of the plastic substrate. . And, when the compressive stress of the cushioning spacer is greater than {(load of flat upper substrate + curing shrinkage force of curable composition) Х 1.05}, non-uniformity of shrinkage occurs during curing, and the appearance characteristics of the plastic substrate may be poor. .

Specifically, Equation 1 may satisfy Equation 1-1, Equation 1-2, or Equation 1-3 below.

[Equation 1-1]

{(Load of flat top substrate + curing shrinkage of curable composition) Х 0.97} ≤ Compressive stress of cushioning spacer ≤ {(Load of flat top substrate + curing shrinkage of curable composition) Х 1.03}

[Equation 1-2]

{(Load of the flat top substrate + curing shrinkage force of the curable composition) Х 0.98} ≤ Compressive stress of the cushioning spacer ≤ {(Load of the flat top substrate + curing shrinkage force of the curable composition) Х 1.02}

[Equation 1-3]

{(Load of flat top substrate + curing shrinkage force of curable composition) Х 0.99} ≤ Compressive stress of cushioning spacer ≤ {(Load of flat top substrate + curing shrinkage force of curable composition) Х 1.01}

Specifically, the compressive stress of the buffer-type spacer may have a difference of 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 thus manufactured The plastic substrate exhibits better surface flatness, and thickness uniformity may also be better implemented.

The unit of the load of the flat upper substrate, the curing shrinkage force, and the compressive stress may be kgf or N.

The buffer-type spacer serves to prevent the curable composition from being peeled off from the flat upper substrate according to shrinkage due to curing of the curable composition. Specifically, since the cushioning spacer has a compressive stress in consideration of the degree of shrinkage as the curable composition is cured and the load of the flat upper substrate, by the load of the flat upper substrate according to the shrinkage of the curable composition. Compressed, in the step of curing the curable composition, the curable composition and the flat upper substrate may serve to maintain a state in close contact.

The load of the flat upper substrate may be 3.4 N to 34 N, 5.9 N to 27 N, 6.5 N to 15 N, or 7.5 N to 10 N. When the load of the flat upper substrate is within the above range, it is possible to minimize deformation due to curing shrinkage during curing of the curable composition, it is possible to minimize a decrease in transmittance during photocuring of the curable composition, and the heat of the curable composition It is possible to induce uniform curing of the curable composition by minimizing the non-uniformity of discharging reaction heat during curing.

Each of the flat lower substrate and the flat upper substrate may be a transparent substrate. Specifically, each of the flat lower substrate and the flat upper substrate may be an organic substrate, which can effectively photo-cur the curable composition due to excellent light transmittance.

Meanwhile, the curing shrinkage force of the curable composition may be measured by the following method. Specifically, at 25° C. and 50 RH% atmosphere, using TA's Texure Analyzer equipment, a predetermined amount of the curable composition is applied on the lower jig, and then the upper jig is lowered to contact the curable composition to record the initial value of the force. Then, after raising the temperature to 90° C. and maintaining it for 5 hours, the final value of the force is recorded, and it can be measured as a value obtained as a difference between the final value of the force and the initial value. The curing shrinkage force of the curable composition may be, for example, 1 to 5 N, 1.5 to 4.8 N, 1.6 to 4.7 N, or 1.7 to 4.5 N.

A value calculated by dividing the curing shrinkage force of the curable composition by the volume of the curable composition may be referred to as a compressive stress coefficient, and the compressive stress coefficient of the curable composition is 0.00001 to 0.00100 N/m ³ , 0.00010 to 0.00080 N/m ³ , or It may be 0.00015 to 0.00050 N/m ^{3 .}

The compressive stress of the cushioning spacer is 25 ℃ and 50 RH% atmosphere, using TA's Texture Analyzer, the specimen area 5 Х 5 ㎟, when compressed at a compression rate of 1 mm / min, the deformation of the specimen ((initial thickness-deformation) After thickness)/initial thickness) may be a measurement value of the force at the moment. The compressive stress of the cushioning spacer may be, for example, 4.4 to 39 N, 5.4 to 32 N, 7.4 to 25 N, or 8.4 to 20 N.

The height (H) of the buffer spacer included in the mold equipment may satisfy Equation 2 below.

[Equation 2]

A X 0.95 ≤ H ≤ A X 1.05

In Equation 2 above,

A is (thickness of plastic substrate)/{1 - (load of flat top substrate + curing shrinkage force of curable composition)/(compressive elastic modulus of buffer type spacer X cross-sectional area of buffer type spacer)}.

The height of the buffer-type spacer means a minimum length between a surface of the buffer-type spacer in contact with the flat upper substrate and a surface in contact with the flat lower substrate. That is, the height of the buffer-type spacer means the thickness of the buffer-type spacer parallel to the thickness direction of the flat upper/lower substrate.

In A of Equation 2 above, the denominator (load of the flat upper substrate + curing shrinkage force of the curable composition)/(compressive elastic modulus of the cushioning spacer X the cross-sectional area of the cushioning spacer) is, It means the spacer strain when the stress is the same. In this case, the two external forces acting on the spacer mean the load of the flat upper substrate and the shrinkage force of the curable composition, and the compressive stress of the spacer means the spacer strain X the compressive elastic modulus of the spacer, and more specifically, the spacer strain = ( spacer thickness - plastic substrate thickness)/spacer thickness).

Therefore, A represents the initial height of the spacer that can reach the equilibrium state of force when manufacturing a plastic substrate of a certain thickness, and the height of the buffer spacer is within 5%, within 3%, within 2%, or 1 of A. As the difference within % is satisfied, in addition to the effect that the thickness of the manufactured plastic substrate is uniform, the effect of absorbing curing shrinkage to prevent distortion of the plastic substrate may be exhibited.

In Formula A, the thickness of the plastic substrate may be the thickness of the plastic substrate finally manufactured in the method for manufacturing the plastic substrate, or the thickness of the plastic substrate to be obtained in the manufacturing method of the plastic substrate. The thickness of the plastic substrate may be 400 μm to 2,000 μm, 400 μm to 1,500 μm, or 405 μm to 1,200 μm.

In Formula A, the compressive elastic modulus of the cushioning spacer may be 0.1 MPa to 10 MPa, 0.1 MPa to 5 MPa, 0.1 MPa to 3 MPa, or 0.1 MPa to 2 MPa. When the compressive elastic modulus of the cushioning spacer is within the above range, the load is uniformly transmitted to the curable composition when the flat upper substrate is in contact, thereby increasing the thickness uniformity of the plastic substrate.

The compressive elastic modulus of the cushioning spacer was measured at 25 ° C and 50 RH% in an atmosphere of 50 RH%, using the TA's Texture Analyzer with a specimen area of 5 Х 5 ㎟, and a compression rate of 1 mm/min. It may mean a slope with respect to the initial thickness-thickness after deformation)/initial thickness). In addition, the compressive elastic modulus of the cushioning spacer when the cushioning spacer is composed of two or more different layers is the force measured when a laminated specimen is prepared with an area of 5 Х 5 ㎟ and compressed at a compression rate of 1 mm/min. It may mean a slope with respect to deformation ((initial thickness - thickness after deformation)/initial thickness).

The buffer spacer may have a structure in which an inelastic layer and an elastic layer are laminated, a structure in which an elastic layer is provided between the inelastic layers, or a structure in which an inelastic layer is provided between the elastic layers. Since the buffer spacer may be designed in consideration of the degree of shrinkage of the curable composition, the inelastic layer may serve as a support, and the elastic layer may serve to adjust the height change according to the shrinkage of the curable composition. have.

On the other hand, when the buffer-interface of the between the two elastic layer provided between the non-elastic layer and the elastic layer is a laminate structure, the non-elastic layer structure, or the elastic layer comprises a non-elastic layer structure, the buffer-interface by the formula 2 The compressive elastic modulus of may mean the compressive elastic modulus of the elastic layer, and in Equation 2, the height of the cushioning spacer is a value limiting the height of the inelastic layer from the thickness of the plastic substrate (thickness of the plastic substrate - the height of the inelastic layer) ) may mean

Meanwhile, the compressive elastic modulus of the inelastic layer may be 60,000 to 80,000 MPa, 63,000 to 78,000 MPa, or 68,000 to 72,000 MPa.

When the buffer spacer includes only an elastic layer, the height of the buffer spacer may be 800 to 1,200 μm, 900 to 1,100 μm, or 950 to 1,050. On the other hand, when the buffer spacer includes both an elastic layer and an inelastic layer, the height of the elastic layer may be 200 to 600 μm, 250 to 500 μm, or 300 to 450 μm, and the height of the inelastic layer is 400 to 950 μm, 450 to 900 μm, and 480 to 850 μm.

In Equation 2, the cross-sectional area of the buffer-type spacer means the sum of the cross-sectional areas of the buffer-type spacer in a direction perpendicular to the height direction of the buffer-type spacer. The shape of the cross-sectional area of the cushioning spacer is not particularly limited thereto, but may have, for example, a shape such as a square, a triangle, a pentagon, a hexagon, or a circle. Three or more points of the buffer-type spacer of the above shape may be arranged at uniform intervals outside the lower mold. In addition, the sum of the cross-sectional areas of the cushioning spacer may be 300 to 1600 mm ² , 400 to 1000 mm ² , or 600 to 800 mm ^{2 When} the cross-sectional area of the cushioning spacer is a rectangle, the length of one side of the rectangle is 5 mm to 20 mm, 10 mm to 15 mm.

The manufacturing method of the plastic substrate, Preparing a mold equipment comprising the flat lower substrate, the flat upper substrate, and a cushioning spacer between the flat lower substrate and the flat upper substrate, the molding space being partitioned by the cushioning spacer may include

The flexural modulus of the flat lower substrate and the flat upper substrate may be 3 GPa or more, 10 GPa or more, 20 GPa or more, 40 GPa or more, and 40 to 200 GPa, 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, and thus the thickness uniformity of the manufactured plastic substrate can be greatly increased. There are advantages.

Surface flatness of the flat lower substrate and the flat upper substrate may be 5 μm or less, 2 μm or less, 1 μm or less, or 0.001 to 1 μm, respectively. When the surface flatness of the flat lower substrate and the flat upper substrate is within the above range, the surface flatness of the manufactured plastic substrate may also be significantly improved compared to that of a general plastic substrate.

The surface flatness was measured at 25 ℃ and 50 RH% atmosphere by QED's ASI (aspheric stitching interferometry) equipment in a 200 mm diameter area, measuring one point per 0.16 Х 0.16 ㎟, or using a three-dimensional shape measuring instrument of Deokin Corporation. Thus, it may mean the difference between the highest and lowest values of heights measured at intervals of 5 mm and 11.25 degrees with respect to an arbitrary origin in the area of 200 mm in diameter.

The molding space may refer to an empty space provided between the flat lower substrate and the flat upper substrate, partitioned by the buffer spacer.

The manufacturing method of the plastic substrate, After preparing the molding equipment, it may include buffering the curable composition in the molding space.

The step of buffering the curable composition in the molding space may refer to injecting the curable composition into the molding space to sufficiently fill the curable composition to closely contact the flat lower substrate and the flat upper substrate. Specifically, the step of buffering the curable composition may mean injecting the curable composition into the molding space at 95 vol% or more, 97 vol% or more, 99 vol% or more, or 100 vol%.

In addition, the step of buffering the curable composition in the molding space includes injecting the curable composition into the molding space of the flat lower substrate provided with the buffer spacer, and laminating the flat upper substrate, or the mold equipment A variety of methods such as a method of injecting the curable composition by providing an injection hole in the can be used.

The method of manufacturing the plastic substrate may include, after buffering the curable composition in the molding space, compressing the curable composition under a load of the flat upper substrate, and curing the curable composition.

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

In order to perform the thermosetting, a temperature increase rate during heat treatment of the curable composition may be 2 °C/min or less or 1 °C/min or less. When the temperature increase rate is within the above range, it is possible to induce uniform curing of the curable composition by minimizing the deviation between positions of heat transferred to the curable composition and minimizing the non-uniformity of discharging reaction heat.

The final temperature during thermosetting may be 85 °C to 100 °C, 87 °C to 98 °C, or 89 °C to 95 °C, and by placing an isothermal holding section at a temperature lower than the final temperature before reaching the final temperature three times or more It is possible to minimize the deviation between positions of heat transferred to the curable composition. The temperature difference between the isothermal holding sections may be 10 ℃ to 20 ℃, 12 ℃ to 18 ℃, or 14 ℃ to 16 ℃, the holding time of the isothermal holding section is 1 hour to 5 hours, or 2 hours to respectively It can be 4 hours. For example, after leaving the curable composition at room temperature (25° C.) for 2 hours, thermosetting at 45° C. for 2 hours, 60° C. for 2 hours, 75° C. for 2 hours, and 90° C. for 4 hours to form a plastic substrate can be manufactured.

In the method for manufacturing a plastic substrate according to an embodiment, the curable composition is compressed with a load of the flat upper substrate, and after curing the curable composition, the flat upper substrate and the flat lower substrate are removed, and obtaining a plastic substrate.

Removing the flat upper substrate and the flat lower substrate means separating the flat upper substrate and the flat lower substrate from a plastic substrate that is a cured product of the curable composition after curing of the curable composition is completed can do.

Surfaces of the flat lower substrate and the flat upper substrate may be surface-treated with a release agent, respectively. The release agent may be applied without limitation as long as it is generally used in the art. For example, the surface-treated material with the release agent may be surface-coated using a fluorine-based silane coupling agent.

When the surface is coated using the release agent, in the step of obtaining the plastic substrate, damage to the surface of the plastic substrate is minimized and the flat lower substrate and the flat upper substrate may be removed.

The curable composition may include an episulfide compound, a thiol compound, and an aromatic ring compound including two or more hydroxyl groups.

The weight ratio of the thiol compound and the aromatic ring compound including two or more hydroxyl groups may be 7:3 to 9:1, 7:3 to 8.5:1.5, or 7:3 to 8:2. If the weight ratio of the thiol compound and the aromatic ring compound containing two or more hydroxyl groups is less than 7:3, the yellowness of the plastic substrate may increase and it may be difficult to implement a high refractive index, and if it exceeds 9:1, the curable composition is cured during curing Because it is difficult to control the speed, streaking may occur in the plastic substrate.

The episulfide compound may include a compound represented by Formula 1 below.

[Formula 1]

In Formula 1,

R ₁ and R ₂ are each independently hydrogen or alkyl having 1 to 10 carbon atoms,

R ₃ and R ₄ are each independently a single bond or alkylene having 1 to 10 carbon atoms,

a is an integer from 0 to 4,

b is an integer from 0 to 6.

The episulfide compound represented by Formula 1 has an aliphatic chain-like skeleton in which episulfide is linked to both ends of the molecule, and in the aliphatic chain, an alkylene group is linked by a sulfur (S) atom. ether) in the form of a repeating unit.

The episulfide compound may contain a high content of sulfur (S) atoms having high atomic refraction in the molecule due to the specific chemical structure described above, and the refractive index of the plastic substrate may be increased by this high content of sulfur atoms. In addition, the episulfide compound can be cured by ring-opening polymerization, and the alkylene sulfide group formed by ring-opening polymerization of the episulfide group may further increase the refractive index of the plastic substrate.

Meanwhile, in Formula 1, R ₁ and R ₂ may each independently be hydrogen or a methyl group, but is not limited thereto.

In addition, R ₃ and R ₄ may each independently be a single bond, methylene, ethylene, propylene, isopropylene, butylene, or isobutylene, but is not limited thereto.

In addition, a and b may each independently be 0 or 1.

a in Formula 1 relates to the number of carbon atoms of the alkylene group included in the thioether repeating unit. When a is too large, the length of the carbon chain in the molecule becomes long, and the glass transition temperature of the plastic substrate is lowered. , this may cause a problem in that the heat resistance of the plastic substrate is lowered, and also, a problem in that the refractive index of the plastic substrate is lowered because the relative sulfur content is lowered.

b in Formula 1 is the number of repeats of thioether repeating units in which an alkylene group is connected by a sulfur (S) atom. When b is too large, the chain length of the molecule becomes longer and thus the plastic substrate is cured. The glass transition temperature is lowered, and accordingly, there may be a problem in that the heat resistance of the plastic substrate is lowered.

In addition, the compound represented by the above formula (1) may be used alone or in combination of two or more.

The episulfide compound is, for example, bis(β-epithiopropyl)sulfide, bis(β-epithiopropyl)disulfide, bis(β-epithiopropylthio)methane, 1,2-bis(β-epi). It may include at least one selected from the group consisting of thiopropylthio)ethane, 1,3-bis(β-epithiopropylthio)propane, 1,4-bis(β-epithiopropylthio)butane, and the like. The invention is not necessarily limited thereto.

The content of the episulfide compound may be 50 to 99% by weight, 60 to 95% by weight, or 70 to 90% by weight based on 100% by weight of the total plastic substrate. When the content of the episulfide compound is too large, there is a problem in that the glass transition temperature of the plastic substrate is lowered and the yellow index (YI) is increased. On the other hand, when the content of the episulfide compound is too small, the glass transition temperature of the plastic substrate is lowered and the yellow index (YI) is increased, and mechanical properties such as hardness and strength may be deteriorated.

The thiol compound may include at least one selected from compounds represented by the following Chemical Formulas 2 and 3.

[Formula 2]

In Formula 2,

R ₅ and R ₆ are each independently a single bond or alkylene having 1 to 10 carbon atoms,

c is an integer from 0 to 4,

d is an integer from 0 to 6,

[Formula 3]

In Formula 3,

Ring A is a 5-membered or 6-membered aromatic heterocyclic ring containing at least one of nitrogen (N) and sulfur (S) atoms,

e is an integer from 1 to 3,

Specifically, the thiol compound represented by Formula 2 has an aliphatic chain skeleton in which thiol groups (-SH) are linked to both ends of the molecule, and in the aliphatic chain, an alkylene group is formed by a sulfur (S) atom. It may include a repeating unit in the form of a linked thioether.

Meanwhile, in the thiol compound represented by Formula 3, one or more thiol groups may be connected to a 5- or 6-membered aromatic ring including a hetero atom such as nitrogen (N) and/or sulfur (S).

The thiol compound represented by Formula 2 or 3 may react with an episulfide group in a curing reaction with the episulfide compound, that is, a ring-opening polymerization reaction of the episulfide group, to form a disulfide bond, etc., and atoms in the molecule It is possible to further increase the refractive index of the plastic substrate and improve the physical strength of the plastic substrate by including high refractive index sulfur (S) atoms in a high content.

Meanwhile, in Formula 2, R ₅ and R ₆ may each independently be a single bond, methylene, ethylene, propylene, isopropylene, butylene, or isobutylene, but is not limited thereto.

Also, c and d may each independently be 0 or 1.

c in Formula 2 relates to the number of carbon atoms in the alkylene group included in the thioether repeating unit. When c is too large, the length of the carbon chain in the molecule becomes long, so that the glass transition temperature of the plastic substrate is lowered. Accordingly, there may be a problem in that the heat resistance of the plastic substrate is lowered, and also, a problem in that the refractive index of the plastic substrate is lowered due to a decrease in the relative sulfur content may occur.

d in Formula 2 is the number of repeats of thioether repeating units in which an alkylene group is connected by a sulfur (S) atom. When d is too large, the chain length of the molecule becomes long, resulting in glass of a plastic substrate. The transition temperature is lowered, and accordingly, there may be a problem in that the heat resistance of the plastic substrate is lowered.

In addition, in Formula 3, ring A may be pyridine, pyrimidine, triazine, imidazole, thiophene, thiazole or thiadiazole, but is not limited thereto.

Also, e may be 2 or 3.

In addition, the compound represented by Formula 2 or 3 may be used alone or in combination of two or more.

The thiol compound may include, for example, at least one selected from the following compounds.

The content of the thiol compound may be 1 to 30% by weight, 5 to 25% by weight, or 7 to 10% by weight based on 100% by weight of the total plastic substrate. When the content of the thiol compound is excessively large, there may be problems in that the glass transition temperature of the plastic substrate is lowered, the yellow index (YI) is increased, and physical properties such as hardness and strength are lowered. On the other hand, when the content of the thiol compound is too small, there is a problem of lowering the glass transition temperature of the plastic substrate and increasing the yellow index (YI).

The aromatic ring compound having two or more hydroxyl groups may include at least one selected from compounds represented by the following Chemical Formulas 4 and 5.

[Formula 4]

In Formula 4,

R ₇ and R ₈ are each independently deuterium, halogen, cyano, nitrile, nitro, amino, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, cycloalkyl having 1 to 40 carbon atoms alkenyl, aryl having 6 to 60 carbon atoms, or heteroaryl having 1 to 40 carbon atoms including at least one of O, N, Si and S;

f and g are each independently an integer of 1 to 7,

h and i are each independently an integer of 0 to 6,

f+h is an integer less than or equal to 7,

g+i is an integer of 7 or less,

[Formula 5]

In Formula 5,

Ar ₁ and Ar ₂ are each independently an aryl having 6 to 60 carbon atoms substituted with one or more hydroxyl groups,

R ₉ and R ₁₀ are each independently deuterium, halogen, cyano, nitrile, nitro, amino, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, cycloalkyl having 1 to 40 carbon atoms alkenyl, aryl having 6 to 60 carbon atoms, or heteroaryl having 1 to 40 carbon atoms including at least one of O, N, Si and S;

m and n are each independently an integer of 0 to 4.

Specifically, the aromatic ring compound having two or more hydroxyl groups represented by Chemical Formula 4 has a skeleton in which two naphthalenes are connected, and one or more hydroxyl groups may be connected to each naphthalene.

On the other hand, the aromatic ring compound having two or more hydroxyl groups represented by Formula 5 may represent a form in which two aryl groups substituted with one or more hydroxyl groups at the 9th position of fluorene are substituted.

The aromatic ring compound having two or more hydroxyl groups represented by Formula 4 or 5 can implement a high refractive index of a plastic substrate by a conjugation system of an aromatic functional group, and also, due to this aromatic functional group, plastic Even if the content of sulfur atoms is reduced by including the aromatic ring compound in the substrate, a decrease in refractive index may be minimized, and further, mechanical properties may be improved by increasing the glass transition temperature (Tg) of the plastic substrate.

Meanwhile, in Formula 4, R ₇ and R ₈ may each independently be deuterium, halogen, cyano, nitrile, nitro, amino, methyl, or ethyl, but is not limited thereto.

Also, f and g may each independently be 1 or 2.

Also, h and i may each independently be 0 or 1.

In addition, in Formula 5, Ar ₁ and Ar ₂ may each independently be phenyl or naphthalenyl substituted with one or two hydroxyl groups, but is not limited thereto.

In addition, R ₉ and R ₁₀ may each independently be deuterium, halogen, cyano, nitrile, nitro, amino, methyl or ethyl, but is not limited thereto.

In addition, m and n may each independently be 0 or 1.

In addition, the compound represented by the formula (4) or (5) may be used alone or in combination of two or more.

The aromatic ring compound having two or more hydroxyl groups may include, for example, at least one selected from the following compounds.

The content of the aromatic ring compound having two or more hydroxyl groups may be 0.1 to 10% by weight, 0.5 to 5% by weight, or 1 to 3% by weight based on 100% by weight of the total plastic substrate. When the content of the aromatic ring compound having two or more hydroxyl groups is too large, there is a problem in that the refractive index of the plastic substrate is lowered, and when the content is too small, the curing reaction rate is too fast, and streaks occur in the plastic substrate.

In addition, the curable composition may further include a catalyst in order to promote polymerization and curing of the above-described compound.

Examples of the catalyst include amines, ammonium salts, and phosphates, and specifically, for example, tertiary amines such as N,N-dimethylcyclohexylamine, tetra-n-butylammonium salt, and ammonium salts such as triethylbenzylammonium salt.

The content of the catalyst may be from about 0.001 to about 10% by weight, from 0.001 to about 5% by weight, or from about 0.01 to about 1.5% by weight, based on the total weight of the above-described curable composition.

In addition, the curable composition may further include other additives such as a UV absorber, a bluing agent, and a pigment.

The curable composition may be a photocurable composition or a thermosetting composition. Specifically, the curable composition may be a thermosetting composition.

The curing shrinkage of the above-described curable composition may be 15% or less, 1% to 15%, 1% to 12%, or 1% to 10%.

In addition, the cure shrinkage of the curable composition may be derived as shown in Equation 3 below.

[Equation 3]

Curing shrinkage (%) = {(Volume before curing - Volume after complete curing) / Volume before curing} Х 100

Meanwhile, the curable composition may have an initial viscosity of 80 to 120 cP, 90 to 110 cP, or 95 to 105 cP immediately after mixing of each component. Meanwhile, the viscosity of the curable composition after storage for 12 hours may be 4500 cP or less, 4000 cP or less, or 200 to 3500 cP.

The plastic substrate manufactured by the method for manufacturing the plastic substrate may include a cured product of an episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups. In addition, the cured product may include a weight ratio of the thiol compound and the aromatic ring compound having two or more hydroxyl groups in a ratio of 7:3 to 9:1.

The plastic substrate has a thickness of 400 μm to 2,000 μm, 400 μm to 1,500 μm, or 405 μm to 1,200 μm, and the thickness deviation of the plastic substrate is 1% or less, 0.8% or less, 0.7% or less, or 0.0001 to 0.7 It can be %.

The thickness of the plastic substrate may be adjusted according to the separation distance between the flat lower substrate and the flat upper substrate and the curing shrinkage of the curable composition. Furthermore, the thickness of the plastic substrate may be adjusted within the above range according to the use of the plastic substrate.

As the thickness deviation value of the plastic substrate decreases, the thickness uniformity of the plastic substrate may be high. That is, the plastic substrate may have very good thickness uniformity with a thickness deviation of 1% or less. The thickness deviation of the plastic substrate may be derived as shown in Equation 4 below.

[Equation 4]

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

The thickness of the member can be measured at 25 ℃ and 50 RH% atmosphere, using the contact measurement method using Mitsutoyo Digimatic Thick 547-401 equipment, the maximum thickness or the minimum thickness can be measured. In addition, the thickness of the member can be measured at 25 ℃ and 50 RH% using a non-contact measurement method using Micro-Epsilon's IFS-2405-1 or IFC-2451-MP equipment to measure the maximum thickness or the minimum thickness.

The average thickness of the member is at 25 ℃ and 50 RH% atmosphere, using the contact measurement method using Mitsutoyo's Digimatic Thick 547-401 equipment, at any point on the randomly placed specimen as the origin, with a radius of 10 mm and 22.5 degrees. It may be an average value of thicknesses measured at intervals. In addition, the average thickness of the member is at 25 ℃ and 50 RH% atmosphere, using a non-contact measurement method using FiberPro's OWTM (Optical Waper Thickness Measurement System) equipment, any point of the randomly placed specimen as the origin, horizontal And it may be an average value of the thickness measured at intervals of 1 mm for each length.

The plastic substrate may have a refractive index of 1.70 or more, about 1.70 to about 1.90, about 1.71 to about 1.89, or about 1.72 to about 1.88 at a wavelength of 532 nm. In the case of a general glass substrate, since the optical refractive index is 1.65 or more at a wavelength of 532 nm, the plastic substrate can implement the same level of optical refractive index as that of the glass substrate, even though the plastic substrate is a plastic material, there is an advantage that can replace the glass substrate .

The plastic substrate has a transmittance measured according to JIS K 7361 when the thickness is 1 mm, more specifically, the transmittance value measured according to JIS K 7361 when the thickness of the above-described cured product is 1 mm is about 80% or more, From about 80 to about 99%, or from about 85 to about 90%, it can have a very high transmittance.

In addition, the plastic substrate has a haze value measured according to JIS K 7136 when the thickness is 1 mm, more specifically, the haze value measured according to JIS K 7136 when the thickness of the cured product is 1 mm about It can have a very low haze value of 1% or less, about 0.01 to about 1%, or about 0.01 to about 0.5%.

In addition, the plastic substrate has a yellowness (YI; Yellow Index), specifically, a yellowness degree measured according to ASTM E313-1973 of 1.0 to 5.0, 1.5 to 4.5, or 2.0 to 4.0, and may exhibit low yellowness.

In addition, the content of sulfur atoms in the plastic substrate may be 52.0 to 59.0 wt%, 52.5 to 57.0 wt%, or 53.0 to 56.0 wt%.

The glass transition temperature of the plastic substrate may be 40 °C or higher, 40 to 200 °C, or 50 to 180 °C. In the case of a wearable device, continuous image transmission and output may proceed, and accordingly, the temperature of the lens substrate may rise. Therefore, the plastic substrate capable of implementing a glass transition temperature of 40° C. or higher is a lens substrate of a wearable device. Even when used, the change in physical properties according to temperature can be minimized.

The plastic substrate may be used as a base material for a diffractive light guide lens of a wearable device. 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 include a diffraction light guide pattern part on one surface to be applied as a substrate for inputting, moving, and transmitting input optical information.

Since the plastic substrate has a high 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 realize high durability by minimizing a change in physical properties due to heat caused by the operation of the wearable device.

According to the present invention, it is lighter than glass or tempered glass used in conventional display substrates, etc., has excellent surface flatness and thickness uniformity, has excellent strength and hardness, can implement various colors, and can realize high refractive index. A method for manufacturing a plastic substrate for an optical lens can be provided.

1 shows a cross-section in the step of curing the curable composition according to an embodiment of the present invention.

Hereinafter, examples will be given to describe 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 to be construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely explain the present invention to those of ordinary skill in the art.

Preparation Example 1: Preparation of a curable composition

90 g of the following 70A as an episulfide compound, 9 g of the following 70B as a thiol compound, and 1 g of the following A1 as an aromatic ring compound having two or more hydroxyl groups were vigorously mixed at 20° C. for 1 hour, and then the pore size was 1 Filtration was performed using a glass filter of ㎛, and filtration was performed once again using a PVDF filter having a pore size of 0.45 ㎛. Thereafter, 1.5 g of N,N-dicyclohexylmethylamine as a catalyst was added and mixed for 5 minutes to prepare a curable composition. The cure shrinkage force of the curable composition was measured by the above-described measuring method of cure shrinkage force, and the compressive stress coefficient calculated by dividing the measured cure shrinkage force by the volume of the sample was 0.00022 N/m ³ .

Preparation Examples 2 to 9: Preparation of a curable composition

A curable composition was prepared in the same manner as in Preparation Example 1, except that the episulfide compound, the thiol compound, and the aromatic ring compound containing two or more hydroxyl groups were used in the amounts and compounds shown in Table 1 below.

(Unit: g) 70A 70B T1 A1 A2 A3 Compressive Stress Coefficient (N/m ³ ) Preparation Example 1 90 9 - One - - 0.00022 Preparation 2 90 - 9 One - - 0.00024 Preparation 3 90 - 7 3 - - 0.00021 Preparation 4 90 - 9 - One - 0.00020 Preparation 5 90 - 9 - - One 0.00019 Preparation 6 90 10 - - - - 0.00018 Preparation 7 90 - 10 - - - 0.00019 Preparation 8 90 9.3 - 0.7 - - 0.00021 Preparation 9 90 6.7 3.3 0.00020

Examples and Comparative Examples: Preparation of plastic substrates

Example 1

A glass substrate having a flexural modulus of 70 GPa, a surface flatness of 0.5 μm, a thickness of 30 mm, and a diameter of 200 mm was used as the lower substrate, and a compressive elastic modulus of 1.0 MPa, a height of 1,042 μm, and a cross-sectional area of 10 Х 10 mm2 was used. After forming a molding space by providing buffer-type spacers made of silicon at 120° intervals so as to be in contact with the circumference of the lower substrate, the curable composition prepared according to Preparation Example 1 is injected into the molding space, and then bending as an upper substrate The curable composition was buffered in the molding space using a glass substrate having an elastic modulus of 70 GPa, a load of 8.2 N, a diameter of 200 mm, and a surface flatness of 0.5 μm.

Furthermore, the curable composition was placed in a convection oven of J.O.Tec, and left at room temperature for 2 hours, the temperature increase rate was set to 1°C/min, and then at 45°C for 2 hours, at 60°C for 2 hours, and at 75°C for 2 hours. , and thermosetting at 90 °C for 4 hours to prepare a plastic substrate.

Example 2

A plastic substrate was prepared in the same manner as in Example 1, except that the curable composition prepared according to Preparation Example 2 was injected into the molding space, and the height of the buffer spacer was adjusted to 423 μm.

Example 3

A plastic substrate was prepared in the same manner as in Example 1, except that the curable composition prepared according to Preparation Example 2 was injected into the molding space.

Example 4

The curable composition prepared according to Preparation Example 2 is injected into the molding space, and a UV-crosslinked polyolefin-based elastic layer having a compressive elastic modulus of 0.16 MPa and a non-elastic layer made of glass having a compressive elastic modulus of 70 GPa are used to form a buffer spacer A plastic substrate was prepared in the same manner as in Example 1 except that the structure of the elastic layer (height 301 μm)/inelastic layer (height 831 μm) was changed (cross-sectional area 10 Х 10 mm 2 ).

Example 5

By injecting the curable composition prepared according to Preparation Example 2 into the molding space, and using a silicone material having a compressive elastic modulus of 1.0 MPa and an inelastic layer made of a glass material having a compressive elastic modulus of 70 GPa, the structure of the buffer spacer A plastic substrate was prepared in the same manner as in Example 1, except that the structure (cross-sectional area 10 Х 10 mm 2 ) was changed to an elastic layer (height 442 μm)/inelastic layer (height 500 μm).

Example 6

A plastic substrate was prepared in the same manner as in Example 1, except that the curable composition prepared according to Preparation Example 3 was injected into the molding space.

Example 7

A plastic substrate was prepared in the same manner as in Example 1, except that the curable composition prepared according to Preparation Example 4 was injected into the molding space.

Example 8

A plastic substrate was prepared in the same manner as in Example 1, except that the curable composition prepared according to Preparation Example 5 was injected into the molding space.

Comparative Example 1

The curable composition prepared according to Preparation Example 2 was injected into the molding space, and a polycarbonate-based buffer spacer (cross-sectional area 10 Х 10 mm2) having a compressive elastic modulus of 2 GPa and a height of 502 μm was used. A plastic substrate was prepared in the same manner as in 1.

Comparative Example 2

The curable composition prepared according to Preparation Example 2 was injected into the molding space, and a UV-crosslinked polyolefin-based elastic layer having a compressive modulus of 0.16 MPa and a non-elastic layer made of a glass material having a compressive modulus of 70 GPa were used. A plastic substrate was prepared in the same manner as in Example 1, except that the structure of the elastic layer (height 160 μm)/inelastic layer (height 829 μm) was changed (cross-sectional area 10 Х 10 mm 2 ).

Comparative Example 3

A plastic substrate was prepared in the same manner as in Example 1, except that the curable composition prepared according to Preparation Example 2 was injected into the molding space, and the height of the buffer spacer was adjusted to 1,007 μm.

Comparative Example 4

A plastic substrate was prepared in the same manner as in Example 1, except that the curable composition prepared according to Preparation Example 8 was injected into the molding space.

Comparative Example 5

A plastic substrate was prepared in the same manner as in Example 1, except that the curable composition prepared according to Preparation Example 9 was injected into the molding space.

Specific details according to the Examples and Comparative Examples are shown in Table 2 below. On the other hand, the compressive stress of the buffer-type spacer of Table 1 and the curing shrinkage force of the curable composition were measured as described above.

curable composition Shock-absorbing spacer Compressive modulus (MPa) Height of buffer spacer (㎛) Compressive stress of cushioning spacer (N) Cure shrinkage force of the curable composition (N) Load of upper substrate (N) elastic layer inelastic layer elastic layer inelastic layer Example 1 Preparation Example 1 1.0 - 1,042 - 11.52 3.89 8.2 Example 2 Preparation 2 1.0 - 423 - 9.93 1.73 8.2 Example 3 Preparation 2 1.0 - 1,042 - 12.96 4.25 8.2 Example 4 Preparation 2 0.16 70,000 301 831 12.44 4.46 8.2 Example 5 Preparation 2 1.0 70,000 442 500 12.07 3.91 8.2 Example 6 Preparation 3 1.0 - 1,042 - 11.52 3.72 8.2 Example 7 Preparation 4 1.0 - 1,042 - 12.09 3.54 8.2 Example 8 Preparation 5 1.0 - 1,042 - 11.80 3.36 8.2 Comparative Example 1 Preparation 2 2,000 - 502 - 21513.94 2.14 8.2 Comparative Example 2 Preparation 2 0.16 70,000 160 829 8.40 4.03 8.2 Comparative Example 3 Preparation 2 1.0 - 1,007 - 10.72 4.10 8.2 Comparative Example 4 Preparation 8 1.0 - 1,042 - 11.95 3.72 8.2 Comparative Example 5 Preparation 9 1.0 - 1,042 - 11.66 3.54 8.2

evaluation

1. Viscosity measurement before and after long-term storage

Immediately after preparing the curable composition of Preparation Examples 1 to 9, the viscosity was measured using a Viscometer TV-22 viscometer manufactured by Toki Sangyo, and then, the curable composition was maintained at a temperature of -5°C for 12 hours, and then the viscosity was measured in the same manner. measured, and the results are shown in Table 3 below.

Viscosity (cP) Early after 12 hours Preparation Example 1 100 3000 Preparation Example 2 100 2500 Preparation 3 100 200 Preparation 4 100 2500 Production Example 5 100 3000 Preparation 6 100 Hardening Preparation 7 100 Hardening Preparation 8 100 5000 Preparation 9 100 200

According to Table 3, in Preparation Examples 1 to 5 and 9, curing did not occur even after storage for 12 hours, but the composition of Preparation Example 8 used very little aromatic ring compound having two or more hydroxyl groups and had a very high viscosity at 5000 cP. It was confirmed that high, and the compositions of Preparation Examples 6 and 7 did not use any aromatic ring compound having two or more hydroxyl groups, so it was confirmed that curing occurred after 12 hours.

2. Measurement of diameter, average thickness and thickness deviation of plastic substrates

For the plastic substrates of Examples and Comparative Examples, the diameter, minimum thickness, maximum thickness, etc. of the plastic substrate were measured by a contact measurement method using Mitsutoyo's Digimatic Thick 547-401 equipment in an atmosphere of 25 ° C. and 50 RH%.

In addition, in order to measure the average thickness, the thickness was measured at an arbitrary point on the plastic substrate with a radius of 10 mm as the origin and an interval of 22.5 degrees, and the average value of the thickness was calculated. Furthermore, the thickness deviation of Equation 4 below was calculated using the measured minimum thickness, maximum thickness, and the calculated average value.

[Equation 4]

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

3. Appearance evaluation of plastic substrates

For the plastic substrates of Examples and Comparative Examples, the appearance was evaluated by checking whether there was a streaking phenomenon with the naked eye. Specifically, when stria phenomenon is not observed with the naked eye, it is evaluated as good, and when stria phenomenon is detected with the naked eye, it is evaluated as bad, and the results are shown in Table 4 below.

4. Measurement of transmittance, haze and yellowness of plastic substrates

For the plastic substrates of Examples and Comparative Examples, in the thickness direction, Nippon Denshoku Industries Co. Ltd. Haze (JIS K 7136), transmittance (JIS K 7361) and yellowness (ASTM E313-1973) were measured using NDH-5000 manufactured by LTD, and the results are shown in Table 4 below. On the other hand, in the case of Comparative Examples 1 and 2, the transmittance, haze, and yellowness were not measured due to poor appearance, and were expressed as '-'.

5. Sulfur atom content

For the plastic substrates of Examples and Comparative Examples, the content of sulfur atoms was measured using elemental analysis, and the results are shown in Table 4 below.

6. refractive index

For the plastic substrates of Examples and Comparative Examples, refractive index values at a wavelength of 532 nm were measured using spectroscopic ellipsometry manufactured by Ellipso Technology, and the results are shown in Table 4 below.

Diameter of plastic substrate (mm) Average thickness of plastic substrate
(μm) Thickness deviation (%) Exterior Transmittance (%) Haze (%) yellowness sulfur atom content
(weight%) refractive index Example 1 150 1002 0.4 Good 87.4 0.3 3.2 54.15 1.723 Example 2 150 409 0.2 Good 88 0.3 2.9 54.3 1.741 Example 3 150 997 0.5 Good 87.5 0.3 3.4 54.30 1.741 Example 4 150 1054 0.7 Good 87.5 0.3 3.3 54.3 1.741 Example 5 150 924 0.4 Good 87.4 0.4 3.2 54.3 1.741 Example 6 150 1002 0.3 Good 87.5 0.3 3.7 53.02 1.736 Example 7 150 1000 0.2 Good 87.7 0.3 2.4 54.30 1.730 Example 8 150 1001 0.1 Good 87.5 0.3 3.0 54.30 1.734 Comparative Example 1 150 484 7.1 bad - - - 54.3 1.741 Comparative Example 2 150 961 6.4 bad - - - 54.3 1.741 Comparative Example 3 150 971 3.3 Good 87.5 0.3 3.3 54.3 1.741 Comparative Example 4 150 1001 0.4 Good 87.3 0.3 6.7 54.33 1.702 Comparative Example 5 150 1002 0.6 Good 87.4 0.7 8.5 52.71 1.699

According to Table 4, the plastic substrate manufactured according to the embodiment exhibits a very low thickness deviation, and thus has high thickness uniformity, good appearance characteristics, very high transmittance, low haze and yellowness, and relatively high It confirmed that it has refractive index.

On the other hand, in the case of Comparative Examples 1 to 3, the compressive stress of the buffer-type spacer is too high or low, so that it cannot maintain adhesion with the upper substrate during shrinkage due to curing of the curable composition, thus exhibiting a very poor thickness deviation, low thickness It was confirmed to have uniformity. In particular, in the case of Comparative Examples 1 and 2, it was confirmed that the appearance characteristics were also poor because streaks appeared on the surface due to the separation from the upper substrate during curing.

In Comparative Examples 4 and 5, it was confirmed that the thiol compound and the aromatic ring compound having two or more hydroxyl groups did not satisfy the weight ratio of 7:3 to 9:1, so that the refractive index was somewhat low while the yellowness was high. .

101: flat lower substrate 102: flat upper substrate
201, 202: cushioning spacer 300: curable composition

Claims (15)

Preparing a mold equipment comprising a flat lower substrate, a flat upper substrate, and a cushioning spacer between the flat lower substrate and the flat upper substrate, wherein a molding space is partitioned by the cushioning spacer;
buffering a curable composition in the molding space;
compressing the curable composition under a load of the flat upper substrate, and curing the curable composition; and
Including; removing the flat upper substrate and the flat lower substrate to obtain a plastic substrate;
The curable composition includes an episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups,
The weight ratio of the thiol compound and the aromatic ring compound having two or more hydroxyl groups is 7:3 to 9:1,
Compressing the curable composition under a load of the flat upper substrate, and curing the curable composition, satisfies Equation 1 below, a method of manufacturing a plastic substrate:
[Equation 1]
{(load of flat top substrate + curing shrinkage force of curable composition) Х 0.95} ≤ compressive stress of cushioning spacer ≤ {(load of flat top substrate + curing shrinkage force of curable composition) Х 1.05}.
According to claim 1,
The height (H) of the buffer-type spacer satisfies the following Equation 2: Manufacturing method of a plastic substrate:
[Equation 2]
AX 0.95 ≤ H ≤ AX 1.05
In Equation 2 above,
A is (thickness of plastic substrate)/{1 - (load of flat top substrate + curing shrinkage force of curable composition)/(compressive elastic modulus of buffer type spacer X cross-sectional area of buffer type spacer)}.
According to claim 1,
The compression elastic modulus of the cushioning spacer is 0.1 to 10 MPa, a method of manufacturing a plastic substrate.
According to claim 1,
The buffer spacer is a structure in which an inelastic layer and an elastic layer are laminated, a structure in which an elastic layer is provided between the inelastic layers, or a structure in which an inelastic layer is provided between the elastic layers, a method of manufacturing a plastic substrate.
According to claim 1,
The load of the flat upper substrate is 3.4 N to 34 N, a method of manufacturing a plastic substrate.
According to claim 1,
The flexural modulus of the flat lower substrate and the flat upper substrate are each independently 3 GPa or more,
Surface flatness of the flat lower substrate and the flat upper substrate are each independently 5 μm or less, a method of manufacturing a plastic substrate.
According to claim 1,
The thickness of the plastic substrate is 400 to 2,000 μm, a method of manufacturing a plastic substrate.
According to claim 1,
The curing shrinkage force of the curable composition is 1 to 5 N, a method of manufacturing a plastic substrate.
According to claim 1,
The episulfide compound is a method of manufacturing a plastic substrate comprising a compound represented by the following formula (1):
[Formula 1]

In Formula 1,
R ₁ and R ₂ are each independently hydrogen or alkyl having 1 to 10 carbon atoms,
R ₃ and R ₄ are each independently a single bond or alkylene having 1 to 10 carbon atoms,
a is an integer from 0 to 4,
b is an integer from 0 to 6.
According to claim 1,
The thiol compound is a method of manufacturing a plastic substrate comprising at least one selected from compounds represented by the following formula (2) or (3):
[Formula 2]

In Formula 2,
R ₅ and R ₆ are each independently a single bond or alkylene having 1 to 10 carbon atoms,
c is an integer from 0 to 4,
d is an integer from 0 to 6,
[Formula 3]

In Formula 3,
Ring A is a 5-membered or 6-membered aromatic heterocyclic ring containing at least one of nitrogen (N) and sulfur (S) atoms,
e is an integer from 1 to 3.
According to claim 1,
The method of manufacturing a plastic substrate, wherein the aromatic ring compound including two or more hydroxyl groups includes at least one selected from compounds represented by the following Chemical Formulas 4 and 5:
[Formula 4]

In Formula 4,
R ₇ and R ₈ are each independently deuterium, halogen, cyano, nitrile, nitro, amino, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, al having 1 to 40 carbon atoms kenyl, aryl having 6 to 60 carbon atoms, or heteroaryl having 1 to 40 carbon atoms including at least one of O, N, Si and S;
f and g are each independently an integer from 1 to 7,
h and i are each independently an integer from 0 to 6,
f+h is 7 or less, g+i is 7 or less,
[Formula 5]

In Formula 5,
Ar ₁ and Ar ₂ are each independently an aryl having 6 to 60 carbon atoms substituted with one or more hydroxyl groups,
R ₉ and R ₁₀ are each independently deuterium, halogen, cyano, nitrile, nitro, amino, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, al having 1 to 40 carbon atoms kenyl, aryl having 6 to 60 carbon atoms, or heteroaryl having 1 to 40 carbon atoms including at least one of O, N, Si and S;
m and n are each independently an integer from 0 to 4.
According to claim 1,
The curing shrinkage of the curable composition is 15% or less, a method of manufacturing a plastic substrate.
According to claim 1,
The thickness deviation of the plastic substrate is 1% or less, a method of manufacturing a plastic substrate.
According to claim 1,
The refractive index of the plastic substrate is 1.65 or more,
The transmittance of the plastic substrate is 85% or more,
The haze value of the plastic substrate is 1% or less,
The degree of yellowness of the plastic substrate is 5 or less, a method of manufacturing a plastic substrate.
According to claim 1,
The plastic substrate is a material for a diffractive light guide lens of a wearable device, a method of manufacturing a plastic substrate.

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