JP2020100027A - Resin filling method - Google Patents

Abstract

To provide a resin filling method that can effectively suppress deformation of a concavo-convex pattern shape of a base material, and can favorably charge a thermoplastic resin with respect to the base material.SOLUTION: The resin filling method for filling a resin to the base material having a concavo-convex pattern using a resin sheet, comprises in this order: a decompression process in which a sheet is directly laminated on the concavo-convex pattern of the base material to form a laminated body and a reduced pressure atmosphere; and a hot pressing process in which the sheet is heated at a sheet heating temperature Hs°C and is pressed without heating the base material or with heating the base material at a base material heating temperature Hb°C, wherein Hs°C in the hot pressing process is equal to or higher than a Vicat softening temperature of the sheet, and Hb°C is equal to or lower than Hs°C and is equal to or lower than the Vicat softening temperature of the base material. Here, the Vicat softening temperature of the base material is higher than the Vicat softening temperature of the sheet.SELECTED DRAWING: None

Description

The present invention relates to a resin filling method. In particular, the present invention relates to a resin filling method using a thermoplastic resin sheet.

A resin molded body obtained by molding a resin material into a desired shape has excellent functionality and is therefore applied to various uses. In recent years, heat resistance and optical characteristics that can be achieved by resin materials have been remarkably improved. Therefore, instead of the glass optical element that has been conventionally used in the imaging optical system, an optical element formed of a resin molding is used. The use of elements is under consideration.

Among imaging optical systems, in recent years, an imaging device capable of forming an image or an image in "in the air" without a reflecting object such as a screen has been attracting attention. An optical element having a special structure is used in such an imaging device.

For example, in Patent Document 1, the first and second light control panels provided with a large number of strip-shaped light reflection surfaces that are arranged in parallel with each other in an upright state are viewed in plan view of the strip-shaped light reflection surfaces. A method of manufacturing a three-dimensional image forming apparatus that is formed orthogonally and superposed is disclosed. In the manufacturing method according to Patent Document 1, on the front side of the transparent plate material, a groove having a triangular cross section having an inclined surface and a vertical surface, and a ridge having a triangular cross section formed by adjacent grooves are arranged in parallel, respectively. A molding base material for the second light control panel is obtained, and a mirror surface is selectively formed only on the vertical surface of the groove of the molding base material. Thereafter, a transparent resin sheet having a melting point lower than that of the transparent plate material is formed on the ridge. The grooves can be filled with the transparent resin by sandwiching them in a state of facing each other, heating and pressing in a vacuum state.

Patent No. 6203978

Here, in the manufacturing method according to Patent Document 1, the melting point of the transparent plate material is set to be higher than the melting point of the transparent resin sheet as a selection criterion for the transparent resin sheet and the transparent plate material. Then, in the manufacturing method according to Patent Document 1, when the groove is filled with the transparent resin sheet, the transparent resin sheet is heated and heated to a temperature at which the transparent plate material is not melted. However, Patent Document 1 does not disclose detailed conditions of heating and pressure when the groove is filled with resin using a transparent resin sheet. The aspect of applying heat and pressure when the groove is filled with the resin using the resin sheet is a highly related factor in that the deformation rate of the ridge is suppressed and the filling rate of the groove with the resin is increased. .. Therefore, in the method for manufacturing a stereoscopic image forming apparatus according to Patent Document 1, it is possible to suppress the deformation of the pattern formed by the convex stripes having a triangular cross section and to increase the filling rate of the resin into the groove at a high level. There was room for improvement in terms of compatibility.

Therefore, the present invention provides a resin filling method capable of effectively suppressing the deformation of the concavo-convex pattern shape of the base material and satisfactorily filling the base material with the thermoplastic resin. The purpose is to do.

The present inventor has made earnest studies for the purpose of solving the above problems. Then, the present inventor has a predetermined mode after the Vicat softening temperature of the resin forming the concavo-convex pattern and the Vicat softening temperature of the resin sheet satisfy a predetermined relationship, and these are laminated in a reduced pressure state. It is possible to effectively suppress deformation of the concavo-convex pattern shape of the base material and heat the thermoplastic resin to the base material well by heating with and hot pressing. Newly found and completed the present invention.

That is, the present invention is intended to advantageously solve the above problems, the resin filling method of the present invention, with respect to the concave portion of the substrate having a concave and convex pattern on one side A resin filling method for filling a thermoplastic resin using a thermoplastic resin sheet, wherein the base material is a thermoplastic resin base material, and the Vicat softening temperature of the thermoplastic resin base material is the thermoplastic resin. It is higher than the Vicat softening temperature of the sheet, and the thermoplastic resin sheet is directly laminated on the concavo-convex pattern of the base material to form a laminated body, and the laminated body is placed in a chamber and the chamber is in a reduced pressure state. Depressurizing step and heating the thermoplastic resin sheet of the laminate at a sheet heating temperature Hs° C. in the chamber without heating the base material of the laminate, or A heat pressing step of pressing the laminate while heating at a base material heating temperature Hb° C. in this order, wherein the sheet heating temperature Hs° C. in the hot pressing step is the thermoplastic resin sheet Of the Vicat softening temperature or higher, and the base material heating temperature Hb° C. is not higher than the sheet heating temperature Hs° C. and is not higher than the Vicat softening temperature of the base material. Thus, the Vicat softening temperature of the thermoplastic resin base material is lower than the Vicat softening temperature, and the thermoplastic resin sheet having a lower Vicat softening temperature is further used. By hot pressing, it is possible to effectively suppress deformation of the uneven pattern shape of the base material, and it is possible to satisfactorily fill the base material with the thermoplastic resin.
The "Vicat softening temperature" can be measured by the method described in Examples.

Further, in the resin filling method of the present invention, it is preferable that the Vicat softening temperature of the base material is 30° C. or more higher than the Vicat softening temperature of the thermoplastic resin sheet. If the Vicat softening temperature of the base material is higher than the Vicat softening temperature of the thermoplastic resin sheet by 30° C. or more, it is possible to more effectively suppress the change in the pattern shape of the uneven pattern provided on the thermoplastic resin base material. You can

Furthermore, in the resin filling method of the present invention, it is preferable that the sheet heating temperature Hs° C. in the hot pressing step is higher than the Vicat softening temperature of the thermoplastic resin sheet by 40° C. or more and 180° C. or less. When the sheet heating temperature Hs° C. satisfies the above condition, the filling rate of the base material concave portion with the thermoplastic resin derived from the thermoplastic resin sheet can be effectively increased, and the concavo-convex pattern of the base material is deformed. This can be effectively suppressed.

Furthermore, in the resin filling method of the present invention, in the depressurizing step, it is preferable that the pressure in the chamber is −70 kPa or less in gauge pressure. By reducing the pressure within the pressure range in the pressure reducing step, it is effective that bubbles are included in the interface between the base material and the thermoplastic resin derived from the thermoplastic resin sheet filled in the recesses of the base material. Can be suppressed.

Furthermore, it is preferable that the resin filling method of the present invention includes changing a press pressure for pressing the laminate from a low pressure to a high pressure in the hot pressing step. By changing the pressing pressure in the hot pressing step in this manner, it is possible to more effectively suppress the deformation of the concavo-convex pattern shape provided on the substrate.

According to the resin filling method of the present invention, it is possible to effectively prevent the uneven pattern shape of the base material from being deformed, and it is possible to satisfactorily fill the base material with the thermoplastic resin.

A schematic structure of an example of a base material that can be used in the present invention, and a view showing a state where a thermoplastic resin sheet is arranged on the base material (upper view of FIG. 1 ), and further, a concave portion of the base material having the general structure. FIG. 2 is a diagram additionally showing an image diagram (lower diagram of FIG. 1) of a state in which a thermoplastic resin is filled with a thermoplastic resin sheet. FIG. 3 is a schematic diagram for explaining a resin filling method according to an example of the present invention. It is a schematic diagram which shows an example of the aspect when the uneven|corrugated pattern of a base material deform|transforms. It is a schematic diagram which shows another example of the aspect when the uneven|corrugated pattern of a base material deform|transforms. It is a figure for demonstrating a joining process. It is a schematic diagram of an example of an optical element which can be formed through the resin filling method of the present invention. It is a figure for demonstrating the evaluation method at the time of evaluating the change of the shape of the uneven|corrugated pattern of the base material in the filling structure obtained through the resin filling method of this invention. It is a figure for demonstrating the evaluation method at the time of evaluating the porosity of the recessed part of the base material in the filling structure obtained through the resin filling method of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that each drawing is merely a schematic diagram, and the scale of each drawing is not limited to this. In addition, in each drawing, the same components are denoted by the same reference numerals.
The resin filling method of the present invention can be suitably used when manufacturing an optical element having a special structure, which can be provided in an imaging device capable of forming an image or an image in the air.

The resin filling method of the present invention is a resin filling method in which a thermoplastic resin sheet is used to fill a thermoplastic resin into a concave portion of a base material having a concave-convex pattern including concave portions and convex portions on one side. Then, in the resin filling method of the present invention, a thermoplastic resin base material is used as the base material, and the Vicat softening temperature of the thermoplastic resin base material needs to be higher than the Vicat softening temperature of the thermoplastic resin sheet. .. Then, the resin filling method of the present invention, a thermoplastic resin sheet is directly laminated on the concavo-convex pattern of the base material to form a laminated body, the laminated body is placed in a chamber, and the inside of the chamber is depressurized. Depressurizing step", the thermoplastic resin sheet of the laminate is heated at the sheet heating temperature Hs°C in the chamber, and the base material of the laminate is not heated or the base material heating temperature is The method is characterized by including, in this order, a “hot pressing step” of pressing the laminate while heating at Hb° C. Further, in the hot pressing step, the sheet heating temperature Hs° C. is equal to or higher than the Vicat softening temperature of the thermoplastic resin sheet, and the base material heating temperature Hb° C. is equal to or lower than the sheet heating temperature Hs° C. It is characterized by being below the Vicat softening temperature of the material.

In the resin filling method of the present invention, the Vicat softening temperature of the thermoplastic resin substrate is lower than the Vicat softening temperature, and a thermoplastic resin sheet having a lower Vicat softening temperature is further used. By hot pressing in a predetermined manner, it is possible to effectively suppress the deformation of the concave-convex pattern shape of the base material, and to satisfactorily fill the base material with the thermoplastic resin.
Hereinafter, the substrate, the thermoplastic resin sheet, and each step included in the resin filling method of the present invention that can be used in the resin filling method of the present invention will be described in detail.

(Base material)
The base material needs to have a concave-convex pattern composed of concave portions and convex portions on one side. The “one side” of the base material refers to one of the main surfaces (front surface and back surface) of the base material. Then, the surface of the base material on the side having no uneven pattern may be a flat surface. Here, the convex portion can be formed by, for example, convex stripes of various shapes. The recess can be configured as a gap between adjacent protrusions (ridges) in a state where the plurality of protrusions (ridges) are arranged in parallel on the main surface of the base material.

Here, the shape of the convex portion (ridge) is not particularly limited, and may be, for example, a shape in which a cut surface obtained along the parallel arrangement direction of the ribs has a triangular shape or a substantially triangular shape. FIG. 1 shows a schematic structure of an example of a base material that can be used in the resin filling method of the present invention, and a view showing a state in which a thermoplastic resin sheet is arranged on the base material of the general structure (upper drawing of FIG. 1), Shows also an image diagram (lower diagram of FIG. 1) of a state in which a thermoplastic resin sheet is used to fill the concave portion of the base material having such a schematic structure. As shown in FIG. 1, the base material 10 has ridges 11 each having a triangular cross section on one main surface, and has recesses that are gaps 12 between the ridges 11. The ridges (projections) 11 and the gaps (recesses) 12 together form an uneven pattern. The other main surface 14 of the base material 10 is a flat surface. As will be described later, in the resin filling method of the present invention, the thermoplastic resin sheet 20 is laminated on the base material 10 having such a shape immediately above the concave/convex pattern, and after a reduced pressure state, a predetermined hot pressing step is performed. By doing so, it is possible to obtain a structure in which the gap (recess) 12 is filled with the thermoplastic resin 20 ′ derived from the thermoplastic resin sheet 20. The ridge (protrusion) 11 has a vertical surface 13 that is perpendicular (substantially perpendicular) to the main surface of the substrate 10, and the vertical surface 13 can be arbitrarily configured as a mirror surface. When the vertical surface 13 is configured as a mirror surface, the structure obtained by using the substrate 10 is a light control for forming an optical element having a special shape as described later with reference to FIG. It can be used favorably as a panel.

When the shape of the ridge is “triangular”, a more detailed shape is a right-angled triangular shape as shown in FIG. 1, and the shorter side of the two sides forming a right angle. The shape may be such that is aligned with one main surface of the substrate. Further, as the “substantially triangular shape”, the corner portion corresponding to the apex of the right triangle has a shape as if chamfered (for example, C chamfer, R chamfer, and other random shapes). Case; and the case where the shape is crushed and bent. Furthermore, examples of the "substantially triangular shape" include the case where the side corresponding to the hypotenuse of the right triangle is not a straight line but a curved line or a polygonal line having one or more bending points. It should be noted that when they are curved lines or polygonal lines, these lines may be concave rather than convex.

The thermoplastic resin constituting the base material is "thermoplastic", that is, it is not particularly limited as long as it has the property of becoming soft when heat is applied to the resin and becoming hard when cooled, any resin Can be used. Preferably, the thermoplastic resin constituting the base material of the present invention may be amorphous. In addition, that the resin is "amorphous" means that the melting point cannot be measured using a differential scanning calorimeter (DSC).
Specifically, examples of the thermoplastic resin constituting the base material include alicyclic structure-containing resins, and among them, norbornene-based resins can be preferably used, and in particular, a resin formed of a norbornene-based ring-opening polymer is used. It can be preferably used. It is preferable that at least one of the thermoplastic resin forming the base material and the thermoplastic resin sheet described below is a transparent resin. This is because it is possible to enhance the transparency of products such as optical elements obtained through the resin filling method of the present invention. The term "transparent" means that the total light transmittance measured by using an injection molded piece having a thickness of 3 mm according to JIS K7375:2008 is 80% or more.

The Vicat softening temperature of the base material made of a thermoplastic resin, that is, the thermoplastic resin base material, needs to be higher than the Vicat softening temperature of the thermoplastic resin sheet described below. By selecting the material so that the Vicat softening temperature of the thermoplastic resin substrate is higher than the Vicat softening temperature of the thermoplastic resin sheet, the pattern shape of the concavo-convex pattern provided on the thermoplastic resin substrate is changed. It can be effectively suppressed. Further, from the viewpoint of further enhancing such effects, the Vicat softening temperature of the thermoplastic resin substrate is preferably 30° C. or higher, more preferably 45° C. or higher, more preferably higher than the Vicat softening temperature of the thermoplastic resin sheet. It is even more preferable that the temperature is larger than 0°C.

Further, the Vicat softening temperature of the thermoplastic resin substrate is preferably 100° C. or higher, more preferably 110° C. or higher, further preferably 120° C. or higher, particularly 140° C. or higher. preferable. Since such a base material has excellent heat resistance, the performance of products such as optical elements obtained through the resin filling method of the present invention can be improved as a result.

The thermoplastic resin substrate having the shape and properties as described above is not particularly limited as long as it is possible to favorably mold a predetermined uneven pattern on a desired one side, and an injection molding method, a press It can be manufactured according to a known molding method such as a molding method and a roll molding method. Optionally, the method for forming at least a part of the concavo-convex pattern of the base material (for example, the vertical surface 13 as described with reference to FIG. 1) as a mirror surface is not particularly limited, and sputtering and A known mirror surface forming method such as metal vapor deposition may be used (see, for example, Japanese Patent No. 6203978).

(Thermoplastic resin sheet)
The thermoplastic resin sheet used in the resin filling method of the present invention is not particularly limited as long as it has a Vicat softening temperature lower than the Vicat softening temperature of the above-mentioned base material (thermoplastic resin base material), and any thermoplastic resin It can be a sheet. As the thermoplastic resin sheet, as with the above-mentioned base material, a sheet made of any resin can be used as long as it is thermoplastic. Furthermore, the Vicat softening temperature of the thermoplastic resin sheet is preferably less than 105°C, more preferably less than 100°C, more preferably less than 90°C, and even more preferably less than 80°C. ..
The refractive index of the thermoplastic resin sheet is preferably 0.8 times or more and 1.2 times or less, and 0.9 times or more and 1.1 times or less, that of the thermoplastic resin constituting the base material. More preferably. The "refractive index" can be measured by the method described in Examples.
The thickness of the thermoplastic resin sheet can be appropriately selected according to the size of the recesses of the uneven pattern of the base material.

The method for producing the thermoplastic resin sheet is not particularly limited, and thermoplastic resin pellets satisfying desired properties can be prepared or obtained, and a known molding method such as a melt extrusion molding method can be adopted. .. By appropriately changing the molding conditions by such a molding method, a thermoplastic resin sheet having a desired thickness can be obtained. Of course, as the thermoplastic resin sheet, it is also possible to use a marketed product satisfying desired properties.

(Preparation process)
In addition, prior to each step constituting the resin filling method of the present invention described below, optionally including a step of producing a substrate and/or a step of producing a thermoplastic resin sheet as described above. But good.

(Decompression process)
In the depressurizing step, the thermoplastic resin sheet is directly laminated on the concavo-convex pattern of the base material to form a laminated body, and the laminated body is placed in a chamber and the chamber is depressurized. The chamber for disposing the laminated body inside is not particularly limited as long as it has hermeticity, and any chamber can be used. Specifically, the "chamber" may be a vacuum compartment provided in the vacuum press device. Note that both this step and the subsequent hot pressing step can be performed using a vacuum pressing device.

The term "depressurized state" means that the state is lower than the pressure state (usually atmospheric pressure) of the atmosphere before starting the depressurizing step, and specifically, the gauge pressure is -70 kPa or less. The pressure is preferably, and more preferably, the gauge pressure is −90 kPa or less. By reducing the pressure within the pressure range in the pressure reducing step, it is effective that bubbles are included in the interface between the base material and the thermoplastic resin derived from the thermoplastic resin sheet filled in the recesses of the base material. Can be suppressed.

With reference to FIG. 2, a specific operation from the depressurizing step to the subsequent hot pressing step and its effect will be described in more detail. FIG. 2 is a schematic diagram for explaining the flow from the pressure reducing step to the hot pressing step included in the resin filling method according to the example of the present invention. As shown in FIG. 2, an upper release sheet 31 and a lower release sheet 32, and an upper support plate 41 and a lower side are arranged in ascending order with respect to the laminated body including the base material 10 and the thermoplastic resin sheet 20. The support plate 42 is arranged in this order. Note that, in FIG. 2, each element other than the laminated body of the base material 10 and the thermoplastic resin sheet 20 is illustrated as being separated from each other in the pressing direction indicated by an arrow in the drawing for the sake of clarity. In the actual arrangement, these elements may be adjacent to each other. Although not shown, all the elements shown in FIG. 2 are arranged in the chamber. As long as the upper release sheet 31 and the lower release sheet 32, the laminate functions to prevent the laminate from sticking to other elements and can exhibit releasability with respect to various thermoplastic resins that can form the laminate, The material is not particularly limited and is made of any material such as polyimide. In addition, the upper support plate 41 and the lower support plate 42 function to support the laminated body so that the laminated position of the laminated body is displaced and that the heat and pressure inputs to the laminated body are made uniform. Function. The upper support plate 41 and the lower support plate 42 can be, for example, SUS plates or the like.

In actual operation, first, the lower release sheet 32 (optional), the substrate 10, the thermoplastic resin sheet 20, the upper release sheet 31 (optional), and the upper support plate 41 are first placed on the lower support plate 42 (optional). (Arbitrary) can be arranged in this order.
Here, it is important that the upper press plate 51 and the thermoplastic resin sheet 20 are sufficiently separated from each other so that the heat of the upper press plate 51 is not conducted to the thermoplastic resin sheet 20 in this step. .. That is, in the depressurizing step, it is important not to heat the thermoplastic resin sheet, more specifically, to prevent the thermoplastic resin sheet from being heated at the sheet heating temperature Hs°C. By performing the depressurization step prior to the subsequent hot pressing step, bubbles are included in the interface between the base material and the thermoplastic resin derived from the thermoplastic resin sheet filled in the recesses of the base material. This can be effectively suppressed.

From the viewpoint of increasing the filling rate of the concave portions of the base material 10 with the thermoplastic resin derived from the thermoplastic resin sheet 20 by effectively reducing the pressure of the concave portions of the concave and convex pattern of the base material, It is preferably placed in the chamber.
Further, the atmosphere in the chamber, which has been decompressed in the depressurizing step, is maintained at substantially the same pressure in the hot pressing step.

(Heat press process)
In the heat pressing step, the thermoplastic resin sheet of the laminate is heated in the chamber at the sheet heating temperature Hs° C., and the base material of the laminate is not heated or the base material heating temperature is set. The laminate is pressed while being heated at Hb°C. At this time, the sheet heating temperature Hs° C. needs to be equal to or higher than the Vicat softening temperature of the thermoplastic resin sheet. When the sheet heating temperature Hs° C. is lower than the Vicat softening temperature of the thermoplastic resin sheet, the thermoplastic resin sheet does not soften, and the concave portion of the base material cannot be filled with the thermoplastic resin. Further, the sheet heating temperature Hs° C. is preferably higher than the Vicat softening temperature of the thermoplastic resin sheet by 40° C. or higher and 180° C. or lower, more preferably 60° C. or higher and 130° C. or lower. When the sheet heating temperature Hs° C. is equal to or higher than the preferable lower limit value, the filling rate of the base material concave portion with the thermoplastic resin derived from the thermoplastic resin sheet can be effectively increased, and the uneven pattern of the base material is deformed. Can be effectively suppressed. Further, when the sheet heating temperature Hs° C. is equal to or lower than the preferable upper limit value, it is possible to effectively prevent the uneven pattern of the base material from being deformed.

On the other hand, in the hot pressing step, the base material side is not heated at all or is heated at the base material heating temperature Hb°C. At this time, the base material heating temperature Hb° C. is not higher than the sheet heating temperature Hs° C. and is not higher than the base material Vicat softening temperature. When the base material heating temperature Hb° C. is equal to or lower than the upper limit value, it is possible to effectively prevent the uneven pattern of the base material from being deformed.

As described above, when the sheet heating temperature Hs°C is too low and too high, and when the substrate heating temperature Hb°C is too high, the uneven pattern of the substrate may be deformed. When the heating temperature Hs° C. of the sheet is too low, pressing is performed in the hot pressing step in a state where the thermoplastic resin sheet has not been sufficiently softened, and therefore the pressing pattern is applied to form the uneven pattern on the substrate side. The apex of the convex portion may be deformed. FIG. 3 schematically shows an example of a modification of the concavo-convex pattern in such a case. In FIG. 3, it can be seen that the ridges of the ridges (projections) 11 are crushed and bent. Further, if the sheet heating temperature Hs° C. is too high, or if the base material heating temperature Hb° C. is too high, the base material may be excessively softened in the hot pressing step. FIG. 4 schematically shows an example of a modification of the concavo-convex pattern in such a case. In FIG. 4, it can be seen that the apexes of the ridges (projections) 11 are melted and rounded, and are deformed.

The above-mentioned sheet heating temperature Hs° C. and base material heating temperature Hb° C. are not the temperature of the heated sheet/base material itself, but means for inputting heat to the sheet/base material, for example, This means temperature setting when heating the upper press plate 51/lower press plate 52 shown in FIG.
The timing of adjusting the upper press plate 51/the lower press plate 52 to the predetermined temperature as described above is not particularly limited, and may be, for example, the previous stage of the depressurizing step.

Then, in the hot pressing step, a heat source (for example, a pressing plate in a vacuum pressing device) is brought close to the base material and/or the thermoplastic resin sheet to be heated prior to pressing (that is, applying a pressing pressure). Alternatively, the base material and optionally the thermoplastic resin sheet can be heated and softened by contacting (in a manner that does not apply pressure). After at least the substrate is sufficiently heated and softened, the upper press plate 51 is pressed and pressed/the lower press plate 52 is pushed up and pressed, whereby the laminate can be hot pressed. The time required for such heating and softening can be arbitrarily set according to the properties of the thermoplastic resin sheet, and can be, for example, 1 minute or more and 10 minutes or less.

Furthermore, in the hot pressing step, it is preferable to change the pressing pressure for pressing the laminate from low pressure to high pressure. Preferably, the press pressure on the low pressure side is 2 MPa or less and the press pressure on the high pressure side is 2 MPa or more. The press pressure on the high pressure side is higher than that on the low pressure side. By changing the pressing pressure in the hot pressing step in this manner, it is possible to more effectively suppress the deformation of the concavo-convex pattern shape provided on the substrate. The press pressure on the low pressure side is usually 0.1 MPa or more, and the press pressure on the high pressure side can be usually 10 MPa or less. The press pressure is a gauge pressure.

Further, the pressing time in the hot pressing step can be appropriately adjusted according to the properties of the thermoplastic resin sheet 20 used. For example, as described above, when the operation of changing the press pressure from the low pressure to the high pressure is performed, the low pressure press and the high pressure press can be performed for 10 seconds to 5 minutes, respectively. When the low-pressure pressing time and the high-pressure pressing time are within the respective ranges, it is possible to suppress deformation of the concavo-convex pattern of the base material and effectively increase the filling rate of the base material concave portion.

Then, after the lapse of the high pressure pressing time, the pressure in the chamber is returned to the atmospheric pressure. After that, the upper press plate 51 is raised/the lower press plate 52 is lowered to hold the structure in which the concave portions of the concavo-convex pattern of the base material are filled with the thermoplastic resin derived from the thermoplastic resin sheet. Release and remove from chamber.

A structure (hereinafter, also referred to as a “filling structure”) in which the recesses of the concavo-convex pattern of the base material, which are thus obtained, are filled with the thermoplastic resin derived from the thermoplastic resin sheet is optional. By being subjected to the following bonding process, it can function as an optical element having a special shape. In this case, the “base material” may be one in which the vertical surface of each convex portion included in the concave-convex pattern of the base material has a mirror surface. It should be noted that the end of the filling structure may be optionally cut off to shape it into a desired shape.

(Joining process)
An optional joining step will be described with reference to FIG. In FIG. 5, elements other than the two filling structures are the same as those in FIG. The two filling structures shown in FIG. 5 have the same configuration, size, and the like, but are arranged so as to have different orientations at the time of joining. Hereinafter, for the sake of convenience, the filling structure arranged on the upper side of the drawing will be referred to as an upper filling structure 100, and the filling structure arranged on the upper and lower sides of the drawing will be referred to as a lower filling structure 200.

In the joining step, first, the upper filling structure 100 and the lower filling structure 200 are aligned and stacked, and are arranged in the chamber. At the time of "alignment", the alignment direction of the ridges in the upper filling structure 100 and the alignment direction of the ridges in the lower filling structure 200 are orthogonal in a plan view (range of 88°C to 92°C). Thus, the upper filling structure 100 and the lower filling structure 200 are arranged. More specifically, in the optical element that is aligned as described above, it is formed on the mirror surface formed on the vertical surface of the convex line of the upper filling structure 100 and on the vertical surface of the convex line of the lower filling structure 200. A spatial arrangement is obtained in which the mirror surfaces formed are orthogonal to each other (in the range of 88° C. to 92° C.) when seen in a plan view. The optical element having such a spatial arrangement of mirror surfaces can be suitably used for an imaging device capable of forming an image or an image in the air.

Next, in the joining step, the inside of the chamber is depressurized in the same manner as the above-mentioned (depressurizing step). A suitable pressure for depressurizing the inside of the chamber in the joining step is also the same as the pressure described above in the item of (depressurizing step).

Then, the upper press plate 51 is pushed down/the lower press plate 52 is pushed up to heat press the stack of the upper filling structure 100 and the lower filling structure 200. The heating temperature of the upper press plate 51 and the lower press plate 52 is particularly limited as long as it is equal to or higher than the Vicat softening temperature of the used thermoplastic resin sheet and lower than the Vicat softening temperature of the used thermoplastic resin substrate. Can be at any temperature without. The timing of adjusting the upper press plate 51/the lower press plate 52 to the predetermined temperature as described above is not particularly limited and may be, for example, a stage before the joining process.

In the hot pressing in the joining step, it is preferable to change the pressing pressure from low pressure to high pressure, as in the above-mentioned (hot pressing step). Further, it is preferable that the low-pressure pressing time and the high-pressure pressing time also satisfy the preferable range described above in the item of (hot pressing step).

Then, after the hot pressing according to the predetermined mode is completed, the pressure in the chamber is returned to the atmospheric pressure. After that, by raising the upper press plate 51 and lowering the lower press plate 52, the holding of the upper filling structure 100 and the lower filling structure 200 joined to each other is released and taken out from the chamber.

FIG. 6 shows a schematic view of an example of a structure of an “optical element” including two bonded filling structures (light control panel) that can be obtained through such an optional bonding process. The optical element 300 shown in FIG. 6 is a structure in which the filling structures 100 and 200 are bonded to each other via a thermoplastic resin derived from a thermoplastic resin sheet. The filling structure 100 includes a ridge (projection) 101, a mirror surface 103 formed on a vertical surface of the ridge 101, and a recess 102 defined by a gap between adjacent ridges 101. Further, the filling structure 200 includes a ridge (projection) 201, a mirror surface 203 formed on a vertical surface of the ridge, and a recess 202 defined by a gap between adjacent ridges (projections) 201. .. In the figure, the broken lines show the contours of the ridges (projections) 101 and 201 provided as the internal structure of the filling structure 100. The alignment direction of the ridges (projections) 101 in the filling structure 100 and the alignment direction of the ridges (projections) 201 in the filling structure 200 are orthogonal to each other in the plane direction. Therefore, the directions of the mirror surface 103 and the mirror surface 203 are also orthogonal to each other in the plane direction. The optical element having such a structure can be suitably used for an imaging device capable of forming an image or an image in the air.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, in the following description, “part” indicating the amount is based on mass unless otherwise specified. The pressure is a gauge pressure. The measurement and evaluation in each example were performed by the following methods.

<Vicat softening temperature>
An injection-molded piece having a thickness of 3 mm was prepared using each resin that is a material for forming the thermoplastic resin substrate and the thermoplastic resin sheet, and used as a test sample. Using this test sample, the Vicat softening temperature was measured using an HDT tester S-3M (manufactured by Toyo Seiki Seisakusho Co., Ltd.) according to the B50 method of JISK7206:2016.
<Refractive index>
It was measured by the V-block method using a Kalnew refractometer (KPR-200 manufactured by Kalnew Optical Co., Ltd.). A resin molded body having a size of 40 mm×40 mm×3.0 mm was used using each resin that is a material for forming the base resin layer and the filled resin layer, and the refractive index at a wavelength of 587.6 nm was measured at 25° C.

<Deformation of uneven pattern shape of base material>
-Evaluation method-
In evaluating the deformation of the concavo-convex pattern of the base material, the value of the perpendicularity parameter of the vertical surface of the convex portion was calculated according to the following formula (1).
H1/H0...(1)
(In the formula (1), H1 represents the length (height) of the portion of the vertical surface of the substantially triangular convex portion that is perpendicular to the main surface of the base material, and H2 is the approximately triangular convex surface. The straight line corresponding to the slope of the section is the height at the position where it intersects with the normal line of the main surface of the base material along the vertical surface.. To clarify the relationship between H0 and H1, FIG.
FIG. 7 is a cross-sectional view in the alignment direction of the plurality of protrusions 11 provided on one main surface of the base material. In FIG. 7, the right-angled triangular protrusion 11 has a vertical surface 13. The vertical surface and the hypotenuse (slope) 15 of the protrusion 11 define at least a part of the gap (recess) 12 between the protrusions 11. Then, the straight line Lv that is the normal line of the main surface Ms that matches the vertical surface of the convex portion 11 and the straight line Lh that matches the hypotenuse (slope surface) 15 of the convex portion 11 intersect at the intersection point C. In this case, the height of the highest point where the vertical surface 13 and the straight line Lv coincide corresponds to the above H1, and the height of the intersection C corresponds to the above H0.
Such a cross section was obtained for each section obtained by dividing the light control panels produced in Examples and Comparative Examples into 9 equal parts in the main surface direction, and each section was obtained using a digital microscope (VHX-1000 manufactured by Keyence Corporation). The verticality parameter (VI) value was calculated by observing 10 convex portions per cross section. The average value of the 90 obtained values was evaluated according to the following criteria.
-Evaluation criteria-
A: 0.85 or more B: 0.7 or more, less than 0.85 C: less than 0.7

<Porosity of recesses in the uneven pattern of the substrate>
-Evaluation method-
The "porosity", which indicates the proportion of the concave portions in the concavo-convex pattern of the base material not filled with the thermoplastic resin derived from the thermoplastic resin sheet, was calculated according to the following formula (2).
L1/L0...(2)
(In the formula (2), L1 represents the height of the gap not filled with the thermoplastic resin, and L0 represents the height of the convex portion. In order to clarify the relationship between L1 and L0, FIG. Indicates.)
FIG. 8 is a cross-sectional view in the alignment direction of the plurality of convex portions 11 provided on one main surface of the base material. In FIG. 8, the right triangular protrusion 11 has a vertical surface 13. At least a part of the gap (recess) between the protrusions 11 is defined by the vertical surface and the oblique side (slope) 15 of the adjacent protrusions 11. The thermoplastic resin 20′ derived from the thermoplastic resin sheet 20 fills a part of the gap (recess), and a part of the gap (recess) remains as the gap G. In such a case, the height from the main surface Ms of the base material to the highest point of the gap G is L1, and the highest point of the convex portion is L0.
Such a cross section was obtained for each section obtained by dividing the light control panels produced in Examples and Comparative Examples into 9 equal parts in the main surface direction, and each section was obtained using a digital microscope (VHX-1000 manufactured by Keyence Corporation). The value of "porosity" was calculated by observing 10 recesses per cross section. The average value of the 90 obtained values was evaluated according to the following criteria.
-Evaluation criteria-
A: less than 0.01 B: 0.01 or more, less than 0.1 C: 0.1 or more

<Preparation of substrate>
Using a thermoplastic resin (ZEONEX (registered trademark) K26R manufactured by Nippon Zeon Co., Ltd., amorphous, total light transmittance 92%, refractive index 1.534 according to JIS K7375:2008 in an injection molded piece having a thickness of 3 mm) Then, a base material having a concavo-convex pattern of the following dimensions was molded by an injection molding method according to the following conditions to obtain a prism plate as the base material. The Vicat softening temperature of the substrate measured according to the above method was 147°C.
Prism size: 100mm x 100mm
Prism mold shape: width 500μm, height 500μm
Molding equipment: Injection molding equipment (J450EL II manufactured by Japan Steel Works, Ltd.)
Molding conditions: injection speed 50 mm/sec, holding pressure 50 MPa
Then, a mirror surface was formed by metal deposition on the vertical surface of the obtained prism plate.

<Preparation of thermoplastic resin sheet>
<<Preparation of Thermoplastic Resin Sheet 1>>
Thermoplastic resin (ZEONEX (registered trademark) 5000, amorphous, injection molded piece having a thickness of 3 mm, a total light transmittance of 92% and a refractive index of 1.531 according to JIS K7375:2008 was applied to a film extrusion molding machine (GSI). A thermoplastic resin sheet 1 (Vicat softening temperature measured according to the above method was 69° C.) was obtained by molding into a sheet according to the following film forming conditions using a single-screw extruder (φ=20 mm, manufactured by Clios). ..
Film-forming conditions: A thermoplastic resin as a material was melted at 220° C., and the melted thermoplastic resin was extruded from a T die, cooled, and cut to obtain a sheet having a thickness of 300 μm and a width of 280 mm.
<<Preparation of Thermoplastic Resin Sheet 2>>
As the thermoplastic resin, ZEONOR (registered trademark) 1060R (amorphous, injection molded piece having a thickness of 3 mm, total light transmittance of 92% according to JIS K7375:2008, refractive index of 1.531) was used, and melting temperature was set. The same operation as in the preparation of the thermoplastic resin sheet 1 was performed except that the temperature was changed to 230° C. to obtain a thermoplastic resin sheet 2 (Vicat softening temperature measured according to the above method was 104° C.).
<<Preparation of Thermoplastic Resin Sheet 3>>
As the thermoplastic resin, ZEONEX (registered trademark) K26R was used, and the same operation as in the preparation of the thermoplastic resin sheet 1 was performed except that the melting temperature was changed to 250° C. And a Vicat softening temperature of 147° C.) was obtained.

(Example 1)
Using the base material prepared as described above and the thermoplastic resin sheet 1 (Vicat softening temperature: 69° C.), the following steps are performed by a vacuum press device (vacuum heat press device “VS30-3030” manufactured by Mikado Technos Co., Ltd.). I went. Prior to the depressurization step, the lower press plate of the vacuum press device is set to 30° C. (base material heating temperature Hb° C.) and the upper press plate is set to 170° C. (sheet heating temperature Hs° C.), and the temperature is raised to the set temperature. Let it warm.
<Decompression process>
First, the lower support plate, the lower release sheet, the base material, the thermoplastic resin sheet 1, and the upper release sheet are arranged in this order on the lower press plate, and the base material-thermoplastic is placed on the upper release sheet side. The upper support plate was arranged so that no pressure was applied to the laminated body of the resin sheets 1. The laminated body was introduced into the vacuum chamber while maintaining this positional relationship.
Then, the inside of the vacuum chamber was depressurized to -100 kPa with a gauge pressure.
<Hot press process>
In the hot pressing step, first, the upper press plate was lowered, stopped at a position 10 mm away from the substrate, and held for 5 minutes. After that, the upper press plate was lowered, the laminate was pressurized at a pressure of 1 MPa and held for 1 minute, and then the upper press plate was further lowered, the pressure was raised to 5 MPa, and held for 1 minute. Then, after returning the inside of the vacuum chamber to atmospheric pressure, the upper press plate was raised and the resin-filled prism plate as the filling structure was taken out from the vacuum chamber.
Various evaluations were performed on the obtained prism plate according to the above. The results are shown in Table 1.

(Examples 2-3, 5-6)
A resin-filled prism plate as a filling structure was obtained in the same manner as in Example 1 except that the sheet heating temperature Hs° C. was changed as shown in Table 1, and various types were obtained in the same manner as in Example 1. An evaluation was made. The results are shown in Table 1.

(Example 4)
A resin-filled prism plate as a filling structure was obtained in the same manner as in Example 1 except that the sheet heating temperature Hs° C. and the base material heating temperature Hb° C. were changed as shown in Table 1. Then, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
As the thermoplastic resin sheet, the thermoplastic resin sheet 2 having a Vicat softening temperature of 104° C. was used, and the sheet heating temperature Hs° C. was changed as shown in Table 1, in the same manner as in Example 1, A resin-filled prism plate as a filling structure was obtained, and various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 8)
A resin-filled prism plate as a filling structure was obtained in the same manner as in Example 1 except that the pressure in the chamber in the depressurization step was changed to -80 kPa with a gauge pressure, and in the same manner as in Example 1. Various evaluations were performed. The results are shown in Table 1.

(Example 9)
In the hot pressing step, the resin-filled prism plate as the filling structure was carried out in the same manner as in Example 1 except that the pressing pressure for pressing the laminate was not changed from low pressure to high pressure and was kept constant at 5 MPa. Then, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
A resin-filled prism plate as a filling structure was obtained in the same manner as in Example 1 except that the thermoplastic resin sheet 3 having a Vicat softening temperature of 147° C. was used as the thermoplastic resin sheet. Various evaluations were performed in the same manner as 1. The results are shown in Table 1.

(Comparative example 2)
As the thermoplastic resin sheet, the thermoplastic resin sheet 3 having a Vicat softening temperature of 147° C. was used, and the sheet heating temperature Hs° C. was changed as shown in Table 1, and the same filling structure as in Example 1 was used. A resin-filled prism plate as a body was obtained, and various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative example 3)
Instead of the same <pressure reduction step> and <hot pressing step> as in Example 1, various operations according to the following order were performed, and the resin filling as the filling structure was performed in the same manner as in Example 1. A prism plate was obtained.
First, similarly to the example, the lower press plate of the vacuum press device is set to 30° C. (base material heating temperature Hb° C.) and the upper press plate is set to 170° C. (sheet heating temperature Hs° C.), and the set temperature is set. The temperature was raised to.
Then, the lower support plate, the lower release sheet, the base material, the thermoplastic resin sheet 1, and the upper release sheet are arranged in this order on the lower press plate, and the base material-thermoplastic is placed on the upper release sheet side. The upper support plate was arranged so that no pressure was applied to the laminated body of the resin sheets 1. The laminated body was introduced into the vacuum chamber while maintaining this positional relationship.
Here, the upper press plate was lowered, stopped at a position 10 mm away from the substrate, and held for 5 minutes. Then, the inside of the vacuum chamber was depressurized to -100 kPa with a gauge pressure. That is, in this example, the hot pressing step was started before the depressurization step.
Then, the upper press plate was lowered, the laminated body was pressurized at a pressure of 1 MPa and held for 1 minute, and then the upper press plate was further lowered, the pressure was increased to 5 MPa, and held for 1 minute. Then, after returning the inside of the vacuum chamber to atmospheric pressure, the upper press plate was raised to take out the resin-filled prism plate, which is the filling structure, from the vacuum chamber.
Various evaluations were performed on the obtained prism plate in the same manner as in Example 1. The results are shown in Table 1.
When the cross section of the obtained filling structure was visually observed, bubbles were included in the interface between the base material and the thermoplastic resin derived from the thermoplastic resin sheet 1 which was filled in the recesses of the base material. It was

(Comparative Example 4)
A thermoplastic resin sheet 2 having a Vicat softening temperature of 104° C. was used as the thermoplastic resin sheet, and the sheet heating temperature Hs° C. and the base material heating temperature Hb° C. were changed as shown in Table 1, respectively. In the same manner as in Example 1, a resin-filled prism plate as a filling structure was obtained, and various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative example 5)
A resin-filled prism plate as a filling structure was obtained in the same manner as in Example 1 except that the base material heating temperature Hb° C. was changed as shown in Table 1, and various types were obtained in the same manner as in Example 1. An evaluation was made. The results are shown in Table 1.

From Table 1, a thermoplastic resin sheet having a Vicat softening temperature lower than the Vicat softening temperature of the thermoplastic resin base material is used, and further, the base material and the thermoplastic resin sheet are laminated in a depressurized state and then in a predetermined mode. In the hot-pressed Examples 1 to 9, it was possible to effectively suppress the deformation of the concave-convex pattern shape of the base material, and to satisfactorily fill the base material with the thermoplastic resin. I understand. On the other hand, Comparative Examples 1 and 2 in which the Vicat softening temperature of the base material and the Vicat softening temperature of the thermoplastic resin sheet were the same, and the atmosphere in which the laminate of the base material and the thermoplastic resin sheet was placed was depressurized. Comparative Example 3 in which the hot pressing step was performed before, Comparative Example 4 in which the thermoplastic resin sheet was heated at a heating temperature lower than the Vicat softening temperature, and further, a base material heating temperature Hb° C. exceeding the Vicat softening temperature of the base material. In Comparative Example 5 in which the base material is heated by, it is possible to both suppress the deformation of the uneven pattern shape of the base material and satisfactorily fill the base material with the thermoplastic resin. I know there wasn't.

According to the resin filling method of the present invention, it is possible to effectively prevent the uneven pattern shape of the base material from being deformed, and it is possible to satisfactorily fill the base material with the thermoplastic resin.

10 Base Material 11 Convex Line (Convex Part)
12 Gap (recess)
13 Vertical surface 14 Main surface (flat surface)
15 hypotenuse (slope)
20 Thermoplastic Resin Sheet 31 Upper Release Sheet 32 Lower Release Sheet 41 Upper Support Plate 42 Lower Support Plate 51 Upper Press Plate 52 Lower Press Plate 100 Upper Filling Structure 200 Lower Filling Structures 101, 201 Part)
102, 202 recesses 103, 203 mirror surface 300 optical element MS main surface

Claims (5)

A resin filling method of filling a thermoplastic resin using a thermoplastic resin sheet, with respect to the concave portion of a base material having a concave-convex pattern composed of concave portions and convex portions on one side,
The substrate is a thermoplastic resin substrate, the Vicat softening temperature of the thermoplastic resin substrate is higher than the Vicat softening temperature of the thermoplastic resin sheet,
A depressurizing step in which the thermoplastic resin sheet is directly laminated on the concavo-convex pattern of the base material to form a laminated body, and the laminated body is placed in a chamber and the chamber is depressurized.
In the chamber, the thermoplastic resin sheet of the laminated body is heated at a sheet heating temperature Hs° C. and the base material of the laminated body is not heated, or a base material heating temperature is set. A hot pressing step of pressing the laminate while heating at Hb° C.,
In this order,
In the hot pressing step, the sheet heating temperature Hs°C is equal to or higher than the Vicat softening temperature of the thermoplastic resin sheet, and the base material heating temperature Hb°C is equal to or lower than the sheet heating temperature Hs°C. Along with the Vicat softening temperature of the substrate, a resin filling method. The resin filling method according to claim 1, wherein the Vicat softening temperature of the base material is 30° C. or more higher than the Vicat softening temperature of the thermoplastic resin sheet. The resin filling method according to claim 1, wherein the sheet heating temperature Hs° C. in the hot pressing step is 40° C. or more and 180° C. or less higher than the Vicat softening temperature of the thermoplastic resin sheet. The resin filling method according to claim 1, wherein in the depressurizing step, the pressure inside the chamber is set to be −70 kPa or less in gauge pressure. The resin filling method according to any one of claims 1 to 4, which comprises changing a press pressure for pressing the laminate from a low pressure to a high pressure in the hot pressing step.

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