WO2019160166A1 - Mold production method, and molded article production method using same - Google Patents

Abstract

Provided is a mold production method whereby it is possible to mold a UV-curable composition with excellent accuracy by means of photoimprinting. This mold production method is a production method for a mold comprising an elastic body and used in molding a UV-curable composition, and is characterized in that deformation accompanying curing of the UV-curable composition is simulated using finite element analysis taking into consideration curing shrinkage [1] of the UV-curable composition and deformation [2] of the mold accompanying the shrinkage, and the mold is designed on the basis of the simulation results.

Description

Mold manufacturing method and molded body manufacturing method using the same

The present invention relates to a method for producing a mold made of an elastic body used for molding an ultraviolet curable composition, and a method for producing a molded body using the mold produced by the above method. This application claims the priority of Japanese Patent Application No. 2018-27432, filed in Japan on February 19, 2018, and Japanese Patent Application No. 2018-174162, filed in Japan on September 18, 2018, and its contents Is hereby incorporated by reference.

Imprint is a microfabrication technology that can transfer nano-sized patterns with a very simple process. If imprint is used, it can be mass-produced at low cost, and has been put to practical use in various fields such as semiconductor devices and optical members.

For example, a micromirror array is an optical member in which a large number of three-dimensional shapes of quadrangular columns and pyramids with sides of 100 to 1000 μm are arranged in a lattice shape, and two adjacent side surfaces of the four side surfaces of the three-dimensional shape are used as orthogonal mirrors. Therefore, an accurate angle and high flatness (that is, high surface accuracy) are required.

Imprint includes thermal imprint that is transferred to a thermoplastic composition and optical imprint that is transferred to an ultraviolet curable composition. In particular, in a field where transfer accuracy is required, such as a micromirror array, a change in shape (expansion or contraction) during solidification or curing is required to be small.

Thermoplastic compositions that use thermoplastic compositions are excellent in terms of transferability because the shape change of the thermoplastic composition is extremely small, but it takes a long time to solidify and the work efficiency is poor. The problem is that the cost increases because of the use of a molded mold.

On the other hand, the ultraviolet curable composition is economical because a resin mold such as a mold can be used. In addition, since it has fast curability, the working efficiency is also good. However, there is a problem when a high-accuracy three-dimensional transfer shape is desired with a high cure shrinkage rate. Further, various studies have been made on the composition in order to suppress the curing shrinkage of the ultraviolet curable composition, but this is also a limit.

Patent Document 1 describes that a reduction in line width due to resin shrinkage can be corrected by a specific function for a mold used for forming a wiring pattern by molding a resin by an imprint method.

JP 2012-183692 A

However, in Patent Document 1, no consideration is given to the fact that the side surface of the wiring is curved, and even if a mold corrected using the above function is used, the side surface of the obtained wiring pattern is not curved. It was found that the surface accuracy was low.

Accordingly, an object of the present invention is to provide a mold manufacturing method capable of accurately molding an ultraviolet curable composition by photoimprinting.
Another object of the present invention is to provide a mold capable of reliably producing a molded article having excellent shape accuracy (particularly excellent in surface accuracy).
Another object of the present invention is to provide a method for producing a highly accurate (particularly excellent in surface precision) molded article comprising a cured product of an ultraviolet curable composition using the mold. .
Another object of the present invention is to provide a highly accurate (particularly excellent in surface accuracy) molded article made of a cured product of an ultraviolet curable composition.
Another object of the present invention is to provide a simulation apparatus that can accurately predict curing shrinkage of an ultraviolet curable composition and accompanying mold deformation.
Another object of the present invention is to provide a mold manufacturing apparatus for reliably manufacturing a molded body excellent in shape accuracy (particularly excellent in surface accuracy).
Another object of the present invention is to provide a molded body production apparatus capable of producing a highly accurate molded body (particularly excellent in surface accuracy) made of a cured product of an ultraviolet curable composition. is there.

As a result of intensive studies to solve the above problems, the present inventors have found that when performing a photoimprint molding using a mold, the mold and the ultraviolet curable composition are in close contact during curing. The ultraviolet curable composition filled in the mold gradually increases in hardness with the progress of the curing reaction, and finally becomes harder than the mold. Therefore, the elastic mold is a deformation of the cured product that is in close contact with the mold wall surface. It was found that the molded body obtained was deformed following the movement of the mold, and the deformation of the mold was transferred to the cured product, so that the obtained molded body had a curved side surface and a low surface accuracy.

In order to improve the surface accuracy of the molded body, the mold is designed so as to compensate for the deformation in consideration of the curing shrinkage of the ultraviolet curable composition and the accompanying deformation of the mold, and manufactured according to the design. It has been found that if an ultraviolet curable composition is molded by an imprint method using the molded mold, a molded body having a desired shape can be produced with high accuracy, efficiency and low cost. The present invention has been completed based on these findings.

That is, the present invention relates to a method for producing a mold made of an elastic material used for molding an ultraviolet curable composition, wherein the deformation accompanying the curing of the ultraviolet curable composition is caused by curing shrinkage of the ultraviolet curable composition [ 1) and a deformation [2] of the mold associated therewith are simulated by a finite element analysis method, and a mold is designed based on the simulation, and a mold manufacturing method is provided.

The present invention also replaces the curing shrinkage [1] of the ultraviolet curable composition with the shrinkage accompanying cooling of the thermoviscoelastic body, and the model is obtained by increasing the thermal expansion coefficient of the thermoviscoelastic body and the viscosity relaxation time accompanying cooling. A method for producing the mold is provided.

The present invention also provides a method for manufacturing the mold, wherein the deformation [2] of the mold is modeled by a superelastic body.

The present invention also provides a mold obtained by the above-described mold manufacturing method.

The present invention also provides a mold comprising the cured product of the ultraviolet curable composition through a step of producing a mold by the mold production method and molding the ultraviolet curable composition using the obtained mold. Provided is a method for producing a molded body to obtain a body.

The present invention also provides a method for producing the molded body, wherein the molded body is a micromirror array.

The present invention also provides a molded body obtained by the method for producing a molded body.

The present invention also simulates the deformation accompanying the curing of the ultraviolet curable composition by a finite element analysis method considering the curing shrinkage [1] of the ultraviolet curable composition and the accompanying mold deformation [2]. Providing equipment.

The present invention is also an apparatus for producing a mold used for molding an ultraviolet curable composition, wherein the deformation accompanying the curing of the ultraviolet curable composition is caused by the curing shrinkage [1] of the ultraviolet curable composition and the accompanying deformation. There is provided a mold manufacturing apparatus characterized by simulating by a finite element analysis method considering the deformation [2] of a mold, and designing and manufacturing the mold based on the simulation.

The present invention also simulates the deformation accompanying the curing of the ultraviolet curable composition by a finite element analysis method considering the curing shrinkage [1] of the ultraviolet curable composition and the accompanying mold deformation [2]. There is provided an apparatus for producing a molded body, wherein the ultraviolet curable composition is molded using a mold designed and manufactured based on the mold.

According to the mold manufacturing method of the present invention, it is possible to predict the deformation by simulation and reflect the necessary correction to the design, which has been done in the past by repeating trial manufacture and spending enormous time and cost. Can be done faster and more reliably. Specifically, the ultraviolet curable composition is analyzed as a thermo-viscoelastic body, and the curing and shrinkage (hereinafter sometimes referred to as “curing behavior”) of the UV-curable composition are determined for each thermoviscoelastic body. Modeling by replacing with shrinkage and solidification due to cooling (hereinafter sometimes referred to as “solidification behavior”) enables quantitative analysis of mold deformation, such as side curvature, caused by the curing behavior of the UV-curable composition. The mold shape can be optimized in consideration of the curvature in advance.
In addition, since the mold obtained by the mold manufacturing method of the present invention has a shape corrected so as to cancel out the expected deformation, if the mold is used, the shape accuracy is excellent, especially the surface accuracy is excellent. A molded body can be obtained efficiently and inexpensively.
Therefore, the mold obtained by the mold manufacturing method of the present invention is required to have high surface accuracy such as an optical member such as a micromirror array, semiconductor lithography, polymer MEMS, flat screen, hologram, waveguide, and precision mechanical parts. It is suitably used for applications in which a fine structure is produced by optical imprinting.

It is the schematic diagram which showed the viscoelasticity of the shear direction by the generalized Maxwell model. It is an analysis area mesh division diagram (total number of nodes: 12434, total number of elements: 7574), (2-a) is an ultraviolet curable composition part, (2-b) is an ultraviolet curable composition part and a mold part. is there. It is the two-dimensional sectional view which cut | disconnected the three-dimensional finite element analysis model by the plane perpendicular | vertical to a y-axis. It is a figure which shows the method of a shape change in optimization of a mold shape. It is a cross-sectional schematic diagram of a micromirror array. It is a 3D image by scanning white interference microscope observation of the side surface of the molded body obtained in Experimental Example 1. It can be seen that the side surface is curved and displaced. It is a figure which shows the bending displacement of the micromirror side surface after mold release by finite element analysis. It is a figure which shows the x direction displacement in the cut surface perpendicular | vertical to a y-axis in the time t = 50s of Step2 of the molded object obtained in Example 1. FIG. It is a figure which shows the x direction displacement in the cut surface perpendicular | vertical to a y-axis in the time t = 100s of Step2 of the molded object obtained in Example 1. FIG. It is a figure which shows the x direction displacement in the cut surface perpendicular | vertical to a y-axis in the time t = 100s of Step2 of the molded object obtained in Example 2. FIG. The figure (a) which shows the z-axis direction displacement in the cross section perpendicular | vertical to a y-axis in the time t = 100s of Step2 of the molded object obtained in Example 3, The y-axis direction displacement in the cross section perpendicular | vertical to a y-axis. FIG. 5B is a diagram illustrating the displacement of the side surface in the y-axis direction. The figure which shows the z-axis direction displacement in the cross section perpendicular | vertical to a y-axis in the time t = 100s of Step2 of the molded object obtained in Example 4 (a), The y-axis direction displacement in the cross section perpendicular | vertical to a y-axis FIG. 5B is a diagram illustrating the displacement of the side surface in the y-axis direction. The figure which shows the z-axis direction displacement in the cross section perpendicular | vertical to a y-axis in the time t = 100s of Step2 of the molded object obtained in Example 5 (a), The y-axis direction displacement in the cross section perpendicular | vertical to a y-axis. It is a figure (b) which shows, and the figure (c) which shows the y-axis direction displacement of a side surface. It is a figure which shows the relationship between the time after ultraviolet irradiation of the ultraviolet curable composition in Example 6, and a gap change rate. It is a figure which shows the relationship between the time after ultraviolet irradiation of the ultraviolet curable composition in Example 6, and a storage transverse elastic modulus. It is a figure which shows the relationship between the time after ultraviolet irradiation of a ultraviolet curable composition in Example 6, and a loss transverse elastic modulus. It is a figure which shows the relationship between the temperature of the ultraviolet curable composition in Example 6, and a linear expansion coefficient. It is a figure which shows the storage transverse elastic modulus master curve in the reference temperature of the ultraviolet curable composition in Example 6. It is a figure which shows the loss transverse elastic modulus master curve in the reference temperature of the ultraviolet curable composition in Example 6. It is a figure which shows the relationship between the shift factor and temperature of the ultraviolet curable composition in Example 6. FIG. It is a figure which shows the storage transverse elastic modulus master curve represented by the Prony series identified in the reference temperature of the ultraviolet curable composition in Example 6. FIG. It is a figure which shows the loss transverse elastic modulus master curve represented by the Prony series identified in the reference temperature of the ultraviolet curable composition in Example 6. FIG. It is a figure which shows the curvature displacement distribution of the mirror surface in the analysis result before mold shape optimization of the ultraviolet curable composition in Example 6. FIG. It is a figure which shows the outline of the physical-property measurement experiment of the ultraviolet curable composition by a rotational vibration type rheometer.

[Mold manufacturing method]
The mold production method of the present invention is a method for producing a mold made of an elastic material, which is used for molding an ultraviolet curable composition. Simulation is performed by a finite element analysis method that takes into account hardening shrinkage [1] and accompanying mold deformation [2], and a mold is designed based on this (for example, mold correction is performed based on this and the mold gold The mold is designed, and a mold is manufactured using the design).

The mold in the present invention is a mold made of an elastic body. That is, it is a mold having elasticity and a property of being deformed by an external force. The material of the mold is not particularly limited as long as it has elasticity, and examples thereof include silicone (for example, polydimethylsiloxane), acrylic polymer, cycloolefin polymer, and fluorine-based polymer.

The curing behavior by irradiating the ultraviolet curable composition of [1] with ultraviolet rays is, for example, the temperature dependence of the thermal expansion coefficient of a thermo-viscoelastic body (for example, thermoplastic resin) and the viscosity accompanying cooling. Can be modeled by increasing relaxation time.

The deformation of the mold of [2] can be modeled by, for example, a super elastic body (for example, a neo-hook elastic body).

In this analysis, a rectangular parallelepiped region containing only one solid pattern is taken out and examined, and a periodic boundary condition is set on the side surface.

The curing reaction that proceeds by UV irradiation of the ultraviolet curable composition can be modeled by replacing it with a solidification reaction by cooling the thermoviscoelastic body (for example, cooling from 100 ° C. to 0 ° C.).
The progress of the curing reaction of the ultraviolet curable composition can replace the increase in the integrated UV irradiation amount per unit volume with the temperature decrease of the thermoviscoelastic body.
Further, the shrinkage rate of the ultraviolet curable composition depending on the integrated UV irradiation amount can be replaced with the thermal expansion coefficient of the thermo-viscoelastic material depending on the temperature.
The thickening of the ultraviolet curable composition that depends on the integrated UV irradiation amount can be replaced with an increase in the viscosity relaxation time of the thermoviscoelastic body that depends on the temperature.

The time dependence of the thermoviscoelastic body can be expressed by a generalized Maxwell model (see FIG. 1). The shear elastic modulus having time dependence of the thermo-viscoelastic body based on the generalized Maxwell model is expressed by the following equation.

Here, _g∞ is the long-term shear elastic modulus, and g _i and τ _i are the i-th shear elastic modulus and relaxation time in FIG. 1, respectively.

The bulk modulus K is treated as the following equation as a constant having no viscosity. However, K ₀ is an immediate bulk modulus, K _∞ represents the long-term bulk modulus.
K = K ₀ = K _∞

Furthermore, the temperature dependence of the thermoviscoelastic body can be expressed by the WLF rule. WLF law the time first temperature conversion rule is expressed using a shift factor A _theta represented by the following formula. Θ represents temperature. Further, θ ₀ , C ₁ and C ₂ are model parameters of the WLF rule, and in particular, θ ₀ indicates a reference temperature.

When the glass transition temperature of the material is θ _g , θ ₀ can be set to about θ _g ≦ θ ₀ ≦ θ _g +50 (° C.). For example, when θ ₀ = θ _g +50, C ₁ and C ₂ can be set to approximately C ₁ = 8.86 and C ₂ = 101.6, respectively.

When more detailed simulation is required, the curing behavior by irradiating the ultraviolet curable composition used in the molded product with ultraviolet rays is measured, and the physical properties (temperature-dependent thermal expansion coefficient, temperature-dependent Shift factors, Prony series coefficients, immediate transverse (or longitudinal) elastic modulus and immediate Poisson's ratio can also be identified and used.

For example, a rotational vibration rheometer can be used to measure the curing behavior of the ultraviolet curable composition. More specifically, a transverse viscoelasticity is obtained by sandwiching an ultraviolet curable composition in a gap of about several hundred microns between a glass plate and a cylinder rod, and irradiating ultraviolet rays from the glass plate side and at the same time vibrating the rod slightly. The time history of characteristics is measured (see FIG. 24). In addition, the time history of the shrinkage characteristics of the ultraviolet curable composition is also measured by making the vertical position of the rod follow the change in the gap due to the shrinkage of the ultraviolet curable composition. It is desirable to adjust the UV irradiation condition so that it is almost the same as the molding condition of the molded body, and always keep it constant, and the characteristics according to the frequency of each rotational vibration by changing the frequency of the rotational vibration in various ways A physical property value can be identified by measuring the value.

The finite element analysis can be performed, for example, by the following procedure using, for example, an ABAQUIS / Standard tetrahedral secondary modified hybrid element (C3D10MH).

Fig. 2 shows a mesh division diagram of the tetrahedral element used in the analysis, and Fig. 3 shows a two-dimensional sectional view.

Based on the results obtained by the above analysis method, for example, the mold shape is optimized by the following means (for example, one direction on the horizontal plane is the x axis, the direction perpendicular to the x axis on the horizontal plane is the y axis, x When the z-axis is a direction perpendicular to the axis and the y-axis, and the quadrangular pyramid shaped molded body is placed on a horizontal plane and cut by a plane including the x-axis and the z-axis (FIG. 3), the left side is the z-axis The mold shape can be optimized so as to be parallel straight lines (FIG. 4).
1. From the analysis result, the x-direction coordinate x ⁽ⁱ⁾ of each node i on the left side of the molded body after mold release is obtained.
2. An auxiliary line parallel to the y-axis is drawn from the reference point of curvature. A signed distance d ⁽ⁱ⁾ (= x ⁽ⁱ⁾ −x ⁽⁰⁾ ) in the x direction with respect to the auxiliary line of each node i is calculated.
3. When the following equation holds, the optimization loop is terminated. Where ε represents the maximum allowable bending depth.
d ⁽ⁱ⁾ <ε∀i.
4). The mold shape correction amount Δx ⁽ⁱ⁾ is calculated from the following equation.
Δx ⁽ⁱ⁾ = − αd ⁽ⁱ⁾ (0 <α <1)
5. Sub-analysis (static analysis for mold shape change) is performed. Δx ⁽ⁱ⁾ is given to the node i as a forced displacement in the x direction. At this time, no displacement is applied in the y direction.
6). The coordinates of all nodes are acquired from the results of the sub-analysis, and are substituted and updated as initial coordinates of the main analysis.

Curing shrinkage of an ultraviolet curable composition is a complicated phenomenon including a phase transition and is difficult to analyze. However, according to the mold manufacturing method of the present invention, the curing behavior of an ultraviolet curable composition is changed to a thermoviscoelastic body. The deformation of the UV curable composition can be simulated by a finite element analysis method, and the mold for manufacturing the mold is designed based on this. Filling the mold obtained on the basis of a liquid mold forming material (for example, silicone resin such as polydimethylsiloxane) and curing it, the desired shape can be obtained in an extremely short time compared to the conventional case. A mold capable of reliably forming a molded body can be manufactured.

[Simulation equipment]
The simulation apparatus of the present invention simulates the deformation accompanying the curing of the ultraviolet curable composition by a finite element analysis method considering the curing shrinkage [1] of the ultraviolet curable composition and the mold deformation [2] associated therewith. (Or implement a simulation).

The apparatus of the present invention has a particularly limited configuration as long as it has a function of simulating by a finite element analysis method in consideration of cure shrinkage [1] of the ultraviolet curable composition and accompanying mold deformation [2]. However, it is preferable to provide a computer type (eg, CPU, memory, hard disk, etc.) as a hard wafer, an operating system as software, and a finite element analysis software (solver, preprocessor, postprocessor), for example.

If the simulation apparatus of the present invention is used, it is possible to accurately predict the curing shrinkage of the ultraviolet curable composition, which is a complicated phenomenon including a phase transition, and the deformation of the mold associated therewith. Accurate prediction of deformation obtained using the simulation apparatus of the present invention is very useful because a molded body having a desired shape can be reliably manufactured if a mold is manufactured based on this.

[mold]
The mold of the present invention is obtained by the above-described mold manufacturing method. In the mold of the present invention, deformation due to curing shrinkage of the ultraviolet curable composition is predicted in advance by simulation, and this is reflected in the design. Therefore, if the mold of the present invention is used, it is possible to reliably produce a molded body made of a cured product of an ultraviolet curable composition and having excellent shape accuracy (particularly excellent surface accuracy). it can.

[Mold manufacturing equipment]
The mold manufacturing apparatus of the present invention is a mold manufacturing apparatus used for molding an ultraviolet curable composition, and the deformation accompanying the curing of the ultraviolet curable composition is cured by shrinkage of the ultraviolet curable composition [1]. And a mold is designed and manufactured based on the simulation by the finite element analysis method considering the deformation [2] of the mold associated therewith.

The mold manufacturing apparatus of the present invention simulates the deformation accompanying the curing of the ultraviolet curable composition by a finite element analysis method considering the curing shrinkage [1] of the ultraviolet curable composition and the mold deformation [2] associated therewith. Then, mold is designed and manufactured based on this (for example, the mold is designed by making necessary corrections based on this, and the mold is manufactured using the obtained mold) The configuration is not particularly limited as long as it has a function. For example, it is a computer type as a hard wafer (eg, CPU, memory, hard disk, etc.), an operating system as software, and a finite element analysis software (solver, preprocessor) , A post processor).

If the mold manufacturing apparatus of the present invention is used, the shrinkage of the ultraviolet curable composition, which is a complicated phenomenon including phase transition, and the deformation of the mold accompanying it are accurately predicted. In order to manufacture, a mold with deformation compensation can be manufactured. The mold thus obtained is very useful since it can reliably produce a molded body having a desired shape.

[Method for producing molded article]
Moreover, if the ultraviolet curable composition is molded using the mold obtained by the mold production method, a molded body having a desired shape can be obtained with certainty.

Examples of the molded body include a micromirror array. The micromirror array is an optical member in which a large number of three-dimensional patterns such as a quadrangular column, a truncated pyramid, and a quadrangular pyramid having a height of 10 to 1000 μm are arranged in a grid pattern (for example, arranged in a grid pattern at intervals of 10 to 1000 μm) (See FIG. 5).

As a mold for manufacturing a micromirror array, it is preferable to have a configuration in which a large number of concave portions having a reversed shape of a quadrangular prism or a quadrangular pyramid are arranged in a lattice shape.

Examples of the method for molding the ultraviolet curable composition include the following methods (1) and (2).
(1) A method in which an ultraviolet curable composition is applied to a mold, a substrate is pressed thereon to cure the ultraviolet curable composition, and then the mold is peeled off. (2) An ultraviolet curable composition applied on the substrate. A method of releasing a mold after pressing the mold against an object to form and curing the ultraviolet curable composition

As the substrate, a substrate having a light transmittance of a wavelength of 400 nm of 90% or more is preferably used, and a substrate made of quartz or glass can be suitably used. In addition, the light transmittance of the said wavelength is calculated | required by using the board | substrate (thickness: 1 mm) as a test piece, and measuring the light transmittance of the said wavelength irradiated to the said test piece using a spectrophotometer.

The method for applying the ultraviolet curable composition is not particularly limited, and examples thereof include a method using a dispenser or a syringe.

Curing of the ultraviolet curable composition can be performed by irradiating with ultraviolet rays. A high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, or the like is used as a light source for ultraviolet irradiation. Although the irradiation time varies depending on the type of light source, the distance between the light source and the coating surface, and other conditions, it is several tens of seconds at the longest. The illuminance is about 5 to 200 mW. After the irradiation with ultraviolet rays, curing may be promoted by heating (post-cure) as necessary.

(UV curable composition)
The ultraviolet curable composition in the present invention includes a cationic curable composition and a radical curable composition. In the present invention, among them, a cationic curable composition is preferable in that it does not undergo curing inhibition by oxygen.

The cationic curable composition is a composition containing a cationic curable compound and is excellent in curability. In particular, a composition containing an epoxy resin as a cationic curable compound is preferable in that a cured product having excellent curability and optical characteristics (particularly transparency), high hardness, and heat resistance can be obtained.

As the epoxy resin, a known or commonly used compound having one or more epoxy groups (oxirane ring) in the molecule can be used. For example, an alicyclic epoxy compound, an aromatic epoxy compound, an aliphatic epoxy compound, etc. Can be mentioned. In the present invention, among them, an alicyclic epoxy compound having an alicyclic structure and an epoxy group as a functional group in the molecule is capable of forming a cured product excellent in heat resistance and transparency. Particularly preferred are polyfunctional alicyclic epoxy compounds.

Specifically, as the polyfunctional alicyclic epoxy compound,
(I) A compound having an epoxy group (that is, an alicyclic epoxy group) composed of two adjacent carbon atoms and oxygen atoms constituting the alicyclic ring (II) An epoxy group bonded directly to the alicyclic ring with a single bond Compound (III) having an alicyclic ring and a glycidyl group.

Especially as a polyfunctional alicyclic epoxy compound, the compound (I) which has an alicyclic epoxy group is preferable at the point from which the cure shrinkage rate is low and the hardened | cured material excellent in the shape precision and the optical characteristic is obtained.

As compound (I) which has the above-mentioned alicyclic epoxy group, the compound represented by following formula (1) is mentioned, for example.

Representative examples of the compound represented by the above formula (1) include 3,4-epoxycyclohexylmethyl (3,4-epoxy) cyclohexanecarboxylate, (3,4,3 ′, 4′-diepoxy) biphenyl. Cyclohexyl, bis (3,4-epoxycyclohexylmethyl) ether, 1,2-epoxy-1,2-bis (3,4-epoxycyclohexane-1-yl) ethane, 2,2-bis (3,4-epoxy) Cyclohexane-1-yl) propane, 1,2-bis (3,4-epoxycyclohexane-1-yl) ethane and the like.

The ultraviolet curable composition in the present invention may contain other curable compounds in addition to the epoxy resin as the curable compound. For example, one or two cationic curable compounds such as oxetane compounds and vinyl ether compounds may be used. More than one species can be contained.

The ultraviolet curable composition in the present invention preferably contains an epoxy resin as a curable compound, and particularly 50% by weight (particularly preferably 60% by weight or more, most preferably 70% by weight or more) of the total amount of the curable compound. Is preferably an epoxy resin containing a polyfunctional alicyclic epoxy compound.

The ultraviolet curable composition preferably contains one or more photopolymerization initiators together with the curable compound. The content of the photopolymerization initiator is, for example, in a range of 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the curable compound (particularly, cationic curable compound) contained in the ultraviolet curable composition. . When content of a polymerization initiator is less than the said range, there exists a possibility of causing a curing defect. On the other hand, when the content of the polymerization initiator exceeds the above range, the cured product tends to be colored.

The ultraviolet curable composition in the present invention comprises the curable compound, a photopolymerization initiator, and other components as necessary (for example, a solvent, an antioxidant, a surface conditioner, a photosensitizer, an antifoaming agent, And a leveling agent, a coupling agent, a surfactant, a flame retardant, an ultraviolet absorber, a colorant, and the like). The blending amount of the other components is, for example, 20% by weight or less, preferably 10% by weight or less, particularly preferably 5% by weight or less, based on the total amount of the ultraviolet curable composition.

[Molded product manufacturing equipment]
The molded body manufacturing apparatus of the present invention uses a finite element analysis method that takes into account the deformation accompanying the curing of the ultraviolet curable composition by taking into account the curing shrinkage [1] of the ultraviolet curable composition and the accompanying mold deformation [2]. The ultraviolet curable composition is molded using a mold that is simulated and designed and manufactured based on the simulation.

The molded body manufacturing apparatus of the present invention uses a finite element analysis method that takes into account the deformation accompanying the curing of the ultraviolet curable composition by taking into account the curing shrinkage [1] of the ultraviolet curable composition and the accompanying mold deformation [2]. The structure is not particularly limited as long as it has a function of forming the ultraviolet curable composition using a mold that is simulated and designed and manufactured based on the simulation. It is preferable to include an operating system (such as a CPU, a memory, and a hard disk), and finite element analysis software (solver, preprocessor, postprocessor) as software.

If the manufacturing apparatus of the molded body of the present invention is used, the curing shrinkage of the ultraviolet curable composition, which is a complicated phenomenon including phase transition, and the deformation of the mold accompanying it are accurately predicted, and the manufacturing is based on this. Since an ultraviolet curable composition is shape | molded using the formed mold, the molded object of a desired shape can be manufactured reliably.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Experimental example 1
The mold contains an ultraviolet curable composition (trade name “CELVENUS OUH106”, a cationic curable compound and a photocationic polymerization initiator, and 80% by weight of the total amount of the cationic curable compound is epoxy resin (polyfunctional alicyclic epoxy). (Including a compound), manufactured by Daicel Corporation), and the mold was closed with a transparent substrate from above. Thereafter, UV irradiation (80 mW × 30 seconds) was performed, followed by release to obtain a molded body (FIG. 6). The obtained molded body was bent and displaced from the central part of the side surface to the central lower part.

Example 1 (examination of the curve from the center to the bottom of the side of the molded body)
Curing shrinkage caused by irradiating the ultraviolet curable composition with ultraviolet rays was replaced with shrinkage solidification caused by cooling the thermo-viscoelastic body.
<Physical properties of thermoviscoelastic body>
Thermal expansion coefficient: 0.0001K ^-1
Immediate Young's modulus: 250 MPa
Immediate Poisson's ratio: 0.3
Generalized Maxwell model:
g ₁ = 0.99999
τ ₁ = 1.0 sec.
Time-temperature conversion law (WLF law):
θ ₀ : 25 ° C.
C ₁ = 10
C ₂ : 100 ° C.

The mold was modeled with a neo-hook elastic body.
<Physical properties of neo-hook elastic body>
Initial Young's modulus: 5Mpa
Initial Poisson's ratio: 0.49

A finite element analysis using an ABAQUIOS / Standard tetrahedral quadratic modified hybrid element (C3D10MH) was performed according to the following procedure.
<Step 1: Stationary (1 second)>
Static analysis Non-slip contact start <Step 2: Solidification shrinkage (100 seconds)>
Semi-sexual analysis The temperature of the thermo-viscoelastic body is lowered from 100 ° C. to 0 ° C. at 1 ° C./second <Step 3: Release (10 seconds)>
Quasi-sexual analysis Contact removal Pull up mold at 400μm

From the cross-sectional view of the molded body reproduced by numerical analysis (FIG. 7), it was found that the curvature from the center to the center lower part quantitatively coincided with the result of the above experimental example.
8 and 9, it can be quantitatively explained that the curvature of the central part and the central lower part is caused by independent factors. That is, from FIG. 8 showing the displacement in the x direction at time t = 50 s of Step 2, the resin is hardly cured in the first half of Step 2, and internal flow occurs due to shrinkage, but the left mold wall surface due to adhesive contact It was found that was bent by being pulled toward the center. At this time, since the right mold wall is also pulled in the center direction, the left and right molds are pulled through the periodic boundary conditions, but the mold has an asymmetrical shape, and the volume of the left half resin is larger. Large, and the shrinkage associated with it is large, so the pulling force of the left mold becomes larger and bends to the center. This is the cause of the curvature at the lower center of the side surface of the molded body.
On the other hand, the cross-sectional view (FIG. 9) perpendicular to the y-axis at the time t = 100 s in Step 2 shows that the bulge progresses in the mold center as compared with FIG. Since shrinkage continues at a constant speed even after the flow stops due to resin curing, the mold will fill up the shrinkage space due to ballering. To do.

Example 2
Finite element analysis was performed under the same conditions as in Example 1 except that the initial Young's modulus of the mold was changed to 1000 Gpa. As a result, in the cross-sectional view perpendicular to the y-axis at the time t = 100 s in Step 2 (FIG. 10), no curvature of the central portion of the side surface of the molded body was observed.
From this, it was confirmed that the valering due to the softness of the mold is involved in the expression of the curvature at the center of the side surface of the molded body.

From the results of Examples 1 and 2 and Experimental Example 1, it was confirmed that the curving from the central part to the central lower part of the side surface of the molded body involved the hardening shrinkage of the resin and the accompanying mold deformation. did it. Further, it was confirmed that the deformation of the molded body can be accurately simulated by performing a calculation in consideration of the curing shrinkage of the resin and the accompanying deformation of the mold by the finite element analysis method.

Example 3 (Examination of residual film layer thickness)
Finite element analysis was performed under the same conditions as in Example 1 except that the thickness of the remaining film layer was 100 μm. As a result, from the cross-sectional view perpendicular to the y-axis at the time t = 100 s of Step 2 (FIG. 11), almost the entire remaining film layer is involved in the flow, and the flow is somewhat restricted due to interference with the fixed boundary of the bottom surface. The situation was seen. Moreover, since the thickness of the remaining film layer was thin, the flow to be drawn from both sides to the central part was large.

Example 4 (Examination of residual film layer thickness)
Finite element analysis was performed under the same conditions as in Example 1 except that the thickness of the remaining film layer was 200 μm. As a result, from the cross-sectional view perpendicular to the y-axis at the time t = 100 s in Step 2 (FIG. 12), the bending was hardly changed from the case where the thickness of the remaining film layer was 100 μm. The upper part (100 μm thick part) of the remaining film layer was mainly involved in the flow, and the flow amount at the lower part (100 μm thick part) was limited.

Example 5 (Examination of remaining film layer thickness)
Finite element analysis was performed under the same conditions as in Example 1 except that the thickness of the remaining film layer was 300 μm. As a result, from the cross-sectional view perpendicular to the y-axis at the time t = 100 s in Step 2 (FIG. 13), the curvature was hardly changed from the case where the thickness of the remaining film layer was 100 μm. The upper part (100 μm thick part) of the remaining film layer was mainly involved in the flow, the flow amount of the middle part (100 μm thick part) was limited, and the lower part (100 μm thick part) hardly flowed.

From the results of Examples 3 to 5, it was confirmed that the thickness of the remaining film layer had little influence on the transfer accuracy. More specifically, if the thickness of the remaining film layer is less than 100 μm, the flow resistance may increase and the curvature may be affected. However, the remaining film layer may have a thickness of 100 μm or more. It has been found that the effect of improving the transfer accuracy cannot be obtained even if the thickness of the layer is increased to 200 μm or more. Therefore, it was confirmed that it was not necessary to add the element of the residual film layer thickness to the simulation by the finite element analysis method.

Example 6 (Examination using physical property value identification method by measurement of curing behavior)
Curing behavior (gap change rate, storage lateral elasticity) of the ultraviolet curable composition (trade name “CELVENUS OUH106”, manufactured by Daicel Corporation) used in Experimental Example 1 using an Anton Paar rheometer (MCR-301). The rate (G ′) and the loss transverse elastic modulus (G ″)) were measured for each rotational vibration frequency (0.1 to 10 Hz).

The UV irradiation conditions in the measurement were adjusted to be the same as in Experimental Example 1 (80 mW × 30 seconds). The UV irradiation conditions are always constant, and the gap change rate does not depend on the frequency. A typical result of the gap change rate is shown in FIG. On the other hand, since the results of the transverse elastic modulus differ for each frequency, the results of three typical conditions (10 Hz, 1 Hz, and 0.1 Hz) are shown in FIGS. The ultraviolet curable composition used in this measurement continues to shrink and cure even after 30 seconds of UV irradiation, indicating that dark curing proceeds.

The curing reaction that proceeds by UV irradiation of the UV curable composition is modeled by replacing it with a solidification reaction by cooling the thermoviscoelastic body (for example, cooling from 100 ° C. to 0 ° C.). Prior to this, temperature must be set as a measure of reaction progress. Here, the time history of temperature was set as θ (t) = − t. The “temperature” set here is a virtual value that is not related to the actual temperature.

The temperature-dependent thermal expansion coefficient was identified from the time history of the gap change rate obtained by the measurement. Note that the volume expansion coefficient β is three times the linear expansion coefficient α, and when the linear expansion coefficient α (θ) depending on the temperature is obtained from the initial state as a reference, the graph of FIG. As obtained.

The shift factor of the time-temperature conversion rule was identified using the time history of the transverse elastic modulus obtained by the measurement. The shift factor A (θ) depending on the temperature is varied so that the master curve (ω: angular frequency) of G ′ (ω) and G ″ (ω) becomes a smooth function after the reference temperature θ ^ref is determined. It can be obtained by determining the shift factor at various sample temperatures.

In this embodiment, the time-temperature conversion does not use the WLF rule or the like, and performs conversion using table data that can be applied more generally. Master curves of G ′ (ω) and G ″ (ω) obtained by shifting based on FIGS. 15 and 16 with the reference temperature θ ^ref = −1800 are shown in FIGS. For this reason, only data at six sample temperatures are shown, and plotting the determined shift factor as a function of temperature A (θ) yielded FIG.

Furthermore, the coefficient of the Prony series was identified using the obtained master curve. As in the case of many thermoviscoelastic bodies, it is considered that the bulk modulus is not viscous and only the transverse modulus is viscous. Since an ultraviolet curable composition undergoes a phase change from a fluid to a solid, it is necessary to identify Prony series coefficients over a wide range of time constants in order to accurately reproduce its deformation behavior. The immediate transverse elastic modulus, the immediate Poisson's ratio, and the like are obtained by conducting a material test on the bulk specimen after being completely cured. On the other hand, the long-term transverse elastic modulus is a physical property value that is difficult to obtain experimentally. Therefore, the behavior close to the fluid was reproduced by setting the long-term lateral elastic modulus to a value that can be regarded as sufficiently small in light of the measurement range with the rheometer (for example, a value of immediate lateral elastic modulus × 10 ⁻⁶ or so).

FIGS. 21 and 22 show master curves of G ′ (ω) and G ″ (ω) at the reference temperature θ ^ref = −1800 obtained by identifying the coefficient of the Prony series with respect to FIGS. 20 terms of 10 ⁻³ , 10 ⁻² ,... 10 ¹⁶ (s) were used as the time constant τ of the series.

The physical property values thus obtained (temperature-dependent thermal expansion coefficient, temperature-dependent shift factor, Prony series coefficient, immediate transverse (or longitudinal) elastic modulus, and immediate Poisson's ratio) are the material physical properties of the ultraviolet curable composition, Furthermore, numerical analysis can be performed by giving a temporal change in temperature (θ (t) = − t) as a region condition. The physical property value data of the mold was the same as in Example 1, and finite element analysis was performed. From the cross-sectional view of the molded body reproduced by numerical analysis (FIG. 23), it was found that the curvature from the center to the center lower part quantitatively coincided with the result of the above experimental example.

From the above results, it can be seen that by the method of the present invention, curing shrinkage of the ultraviolet curable composition and accompanying mold deformation can be predicted by simulation. Therefore, if the method of the present invention is used, the necessary correction can be obtained by calculation, and the correction obtained by calculation is reflected in the design, so that a high-precision molded body can be obtained more quickly, reliably and inexpensively. A mold that can be manufactured is obtained. Moreover, if this mold is used, a highly accurate molded object can be obtained efficiently.

According to the mold manufacturing method of the present invention, it is possible to predict the deformation by simulation and reflect the necessary correction to the design, which has been done in the past by repeating trial manufacture and spending enormous time and cost. Can be done faster and more reliably.
Further, since the mold obtained by the above method has a shape corrected so as to cancel out the expected deformation, a molded body having excellent shape accuracy can be obtained efficiently and inexpensively by using the mold. Therefore, it is suitably used for the purpose of producing a fine structure such as a micromirror array that requires high surface accuracy by optical imprinting.

1 Micromirror array 2 Solid pattern 3 Remaining film layer

Claims (10)

1. A method for producing a mold made of an elastic body, which is used for molding an ultraviolet curable composition, wherein the deformation accompanying the curing of the ultraviolet curable composition is caused by curing shrinkage [1] of the ultraviolet curable composition and the mold accompanying it. A method for manufacturing a mold, characterized by simulating by a finite element analysis method taking into account the deformation [2] and designing a mold based on the simulation.
2. The cure shrinkage [1] of the ultraviolet curable composition is replaced with the shrinkage accompanying cooling of the thermoviscoelastic body, and is modeled by the thermal expansion coefficient of the thermoviscoelastic body and the increase in the viscosity relaxation time accompanying cooling. A method for producing the mold according to 1.
3. The method for producing a mold according to claim 1 or 2, wherein the deformation [2] of the mold is modeled by a superelastic body.
4. A mold obtained by the mold manufacturing method according to any one of claims 1 to 3.
5. A mold is produced by the method for producing a mold according to any one of claims 1 to 3, and a step of forming an ultraviolet curable composition using the obtained mold is performed. A method for producing a molded body, which obtains a molded body comprising a cured product.
6. The method for producing a molded body according to claim 5, wherein the molded body is a micromirror array.
7. A molded product obtained by the method for producing a molded product according to claim 5 or 6.
8. A simulation apparatus for simulating the deformation accompanying the curing of the ultraviolet curable composition by a finite element analysis method in consideration of the curing shrinkage [1] of the ultraviolet curable composition and the accompanying mold deformation [2].
9. An apparatus for producing a mold used for molding an ultraviolet curable composition, wherein the deformation accompanying the curing of the ultraviolet curable composition is caused by curing shrinkage of the ultraviolet curable composition [1] and accompanying mold deformation [2]. A mold manufacturing apparatus characterized in that a mold is designed and manufactured based on a simulation by a finite element analysis method considering the above.
10. The deformation accompanying the curing of the UV curable composition is simulated by a finite element analysis method considering the curing shrinkage [1] of the UV curable composition and the mold deformation [2] associated therewith, and designed based on this. An apparatus for producing a molded body, wherein the ultraviolet curable composition is molded using a manufactured mold.

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