WO2014133050A1

WO2014133050A1 - Method for manufacturing molded heat-curable resin sheets with through hole

Info

Publication number: WO2014133050A1
Application number: PCT/JP2014/054788
Authority: WO
Inventors: 龍太木部; 一郎末廣
Original assignee: 日東電工株式会社
Priority date: 2013-02-27
Filing date: 2014-02-27
Publication date: 2014-09-04

Abstract

A heat-curable resin composition (X1) having a sheet form and in a semi-cured state is disposed between a pressing die (1), which is provided with protrusions (12) for forming through holes, and a substrate (2), and through holes (Y) are formed in the semi-cured heat-curable resin composition (X1) by pressing the pressing die (1) on the substrate (2) (pressing process). A semi-cured sheet with through holes is obtained from said process. The heat-curable resin composition (X1) is heated to the curing temperature and completely cured with the pressing die (1) still pressed against the substrate (2) (curing process) to obtain a molded heat-curable resin sheet (X2) with through holes (Y).

Description

Method for producing sheet-like thermosetting resin molded product having through holes

The present invention relates to a method for producing a sheet-like molded product made of a thermosetting resin, and more particularly to a method for producing a sheet-like resin molded product having a through hole.

In the case of a reflector for an LED chip or a panel portion having a through hole for attaching a vibrating portion of a small speaker, a thermosetting resin sheet having a small aperture and a through hole with high dimensional accuracy is required. May be.
For example, in the embodiment shown in FIG. 8A, a large number of fine through holes 110 are provided on the main surface of the sheet 100 made of a thermosetting resin. Further, in the embodiment shown in FIG. 8B, as the reflector for the LED chip, the reverse frustoconical through-hole 210 is provided in the resin sheet 200, and the LEDs mounted in an array on the circuit board S10. The light L10 emitted from the chip C10 in the lateral direction is reflected and directed upward in the figure.

Generally, in the thermosetting resin molding process, since the thermosetting resin material injected into the molding die is in a liquid state, the material is not easily handled.
On the other hand, Patent Document 1 discloses a method in which a thermoplastic resin material sheet is placed in a mold, the sheet is heated to a flow start temperature or higher, and the sheet is pressed and molded with a pressing mold ( A so-called sheet forming method) is described. However, since this method is a technique related to the processing of thermoplastic resins, it cannot be applied to the processing of thermosetting resins that are cured by heating to high temperatures.

On the other hand, in Patent Document 2, a base material composed of a kneaded product of an inorganic filler, a thermosetting resin and a pregelling agent is heated to the curing temperature of the pregelling agent to be in a semi-cured state, and punched with a punch. A method of forming a through hole is described. However, in this method, a three-layer substrate (copper foil / resin layer / copper) is sandwiched between both sides of the semi-cured resin layer with copper foil so that the semi-cured resin can be punched out with a punch. Foil) and all three layers are punched.
However, in such a method, the preparation of the three-layer base material requires copper foil and processing, and it also takes time to remove the copper foil from both sides of the obtained product. Becomes higher. Further, since punching waste is generated in the punching process, there is a problem in that a means and equipment for recovering this are required, and the punch waste becomes a material loss, resulting in a higher manufacturing cost. Furthermore, there is a problem that the through holes obtained by punching are limited to straight holes (columnar holes) having the same hole shape from one opening to the other opening.

Also, in the method of forming a through hole by simply punching out a cured thermosetting resin sheet with a punch, the opening diameter of the through hole after removing the punch from the through hole is caused by the elasticity of the resin material. When a more flexible and elastic resin material is punched out, shearing occurs only when the resin sheet is largely compressed and deformed by the punch. In some cases, a phenomenon may occur in which the through hole when the original shape is restored does not become a straight hole having an intended shape, and it is difficult to form a through hole with high dimensional accuracy.

JP 2006-142711 A JP 2005-193348 A

An object of the present invention is to provide a new manufacturing method capable of forming a through hole with high dimensional accuracy in the manufacture of a molded product made of a thermosetting resin and having a through hole.

As a result of earnest research to solve the above problems, the present inventors have arranged a sheet-like material made of a thermosetting resin in a semi-cured state in a molding die, and a protrusion for forming a through hole By pressing the pressing mold with the sheet-like material into a semi-cured sheet, or by further heating the resin to the curing temperature in that state to cure the resin without causing punching residue The inventors have found that the target through-hole can be formed with high dimensional accuracy, and have completed the invention.

The main configuration of the present invention is as follows.
(1) A method for producing a sheet-like thermosetting resin molded article having a through-hole,
A thermosetting resin composition that is in the form of a sheet and is semi-cured is disposed between a pressing die having a protrusion for forming the through hole and a substrate facing the pressing die. Pressing the substrate to form a through hole in the semi-cured thermosetting resin composition,
The manufacturing method.
(2) After the pressing step, further comprising a curing step in which the semi-cured thermosetting resin composition is completely cured by heating to a curing temperature while the pressing die is pressed against the substrate. (1) The manufacturing method as described.
(3) The above-mentioned (1), which is a silicone resin sheet having a property of being in a semi-cured state until the thermosetting resin composition in a sheet-shaped and semi-cured state is heated to a curing temperature Or the manufacturing method of (2) description.
(4) The thermosetting resin composition having a sheet shape and in a semi-cured state is further accompanied by a sheet base material, and the semi-cured thermosetting resin composition is formed on the sheet base material. By laminating the material layer, it is provided to the pressing step as a sheet-like laminate,
By placing the semi-cured thermosetting resin composition layer between the pressing mold and the substrate so that the sheet base material is on the substrate side, in the pressing step and the curing step, the protruding portion of the pressing mold The manufacturing method according to any one of (1) to (3), wherein the sheet base material is interposed between the tip of the substrate and the substrate.
(5) The substrate is a laminate having a surface layer and a buffer layer under the surface layer,
The production method according to any one of (1) to (4), wherein the surface layer is thinner than the buffer layer.
(6) The shape of the through hole is a shape having a funnel-shaped portion in which the area of the cross section decreases as it moves from the surface on the mold side of the thermosetting resin composition to the substrate side. (5) The manufacturing method in any one of.
(7) The manufacturing method according to (6), wherein the shape of the through-hole is a shape having a straight tubular portion having a constant cross-sectional area on the substrate side of the funnel-shaped portion.
(8) The manufacturing method according to (6), wherein the shape of the funnel-shaped portion is a truncated cone or a truncated pyramid, and the shape of the straight tubular portion is a columnar shape or a prismatic shape.

In the following description, a “sheet-shaped and semi-cured thermosetting resin composition” disposed in a mold as a molding material in the present invention is also referred to as “semi-cured material sheet” or simply “material sheet”. A “sheet-like thermosetting resin molded product having a through-hole” that is a product to be manufactured is also referred to as a “sheet-like product having a through-hole” or simply a “sheet-like product”.
One of the important features of the production method of the present invention is that a molding material supplied into a molding die (a die having a pressing die and a substrate facing it) is a semi-cured material sheet. Can be mentioned.
Here, the semi-cured thermosetting resin composition has a property of maintaining a semi-cured state at a room temperature of about 5 ° C. to 35 ° C. (it remains in a semi-cured state until it is heated to the curing temperature). A thermosetting resin composition having a property of being completely cured by being heated to a curing temperature.
Once the thermosetting resin composition is in a semi-cured state, the curing is once stopped and formed into a sheet, and the material sheet at this stage is punched in the mold and used as a product in the semi-cured sheet. There has never been a technique or a technique of performing a hole forming process on a semi-cured material sheet in a mold and heat-curing it with the mold closed.
By this method, first, handling of the material at the molding site becomes easier as compared with the case of injecting a liquid thermosetting resin material into the mold. In addition, while using a sheet-like material, since it is in a semi-cured state, it is possible to form a through-hole by pushing the molding material to the periphery, and there is an advantage that no punching residue is generated.
In addition, since the projections for forming the through holes push in the material sheet and enter, the bubbles are not included, and the uniform material distribution does not cause molding defects such as sink marks, and the through holes with high dimensional accuracy are formed. There is also an advantage that it can be obtained.
Moreover, the semi-cured sheet is inferior in mechanical strength and electrical characteristics to the fully cured sheet, but has adhesiveness. Therefore, it can be used for applications that do not require mechanical strength and electrical characteristics, and applications that particularly require adhesiveness to the substrate surface.
Furthermore, deformation that occurs in the punching process (the material after removing the protrusions) is performed by heating the semi-cured material sheet in a state where the protrusions of the pressing mold are pressed and completely curing the material sheet. Deformation due to the restoration of the original shape of the sheet) is suppressed, and the target through-hole to be formed can be formed with high dimensional accuracy. With the above effects, for example, after complete curing, it is possible to form through holes having a minute hole diameter of 10 μm to 1000 μm in a thermosetting resin sheet with high accuracy.
Further, a sheet molded product using a thermoplastic resin is known as a conventionally known molded product, but the sheet molded product obtained by the thermoplastic resin cannot be used at a temperature higher than the glass transition temperature of the thermoplastic resin. There is a problem that the solvent resistance, weather resistance, light resistance and the like are not sufficient, and there is a limit to the use to be used. On the other hand, in the case of a sheet molded product using a thermosetting resin in a semi-curable state as in the present invention, the above problem does not occur.

FIG. 1 is a cross-sectional view for explaining the manufacturing method of the present invention. Fig.1 (a) is sectional drawing which shows the state which has arrange | positioned the material sheet of the semi-hardened state in the press process between the stamping die and the board | substrate. FIG. 1B is a cross-sectional view showing a state in which the pressing die is pressed against the substrate in the pressing step to form the material sheet through hole, and a state in which the material sheet is heated and cured in the curing step. FIG.1 (c) is sectional drawing which shows the structure of the sheet-like product which has the through-hole taken out from between a stamping die and a board | substrate. FIG. 2 is a cross-sectional view showing another example of a state in which a material sheet through-hole is formed by pressing a pressing die against a substrate in the pressing step of the present invention. FIG. 3 is a cross-sectional view illustrating the shape of the through hole of the sheet-like product manufactured according to the present invention. FIG. 4 is a diagram illustrating the shape of the through-hole and the cross-section (cross-section when cut perpendicular to the central axis of the through-hole) of the sheet-like product manufactured according to the present invention. It is a figure when the main surface of a product is seen. FIG. 5 is a diagram illustrating an aspect of arrangement of the through holes in the sheet-like product manufactured according to the present invention, and is a view when the main surface of the sheet-like product is viewed. FIG. 6 is a perspective view illustrating a part of a pressing die for manufacturing the sheet-like product of FIG. FIG. 7 is a cross-sectional view for explaining a preferred embodiment of the production method of the present invention. FIG. 8 is a diagram illustrating an example of a conventionally used thermosetting resin sheet having a through hole.

Hereinafter, the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1 (a), the manufacturing method of the present invention is semi-cured between a pressing die 1 provided with a projection 12 for forming a through hole and a substrate 2 facing the pressing die. By placing a material sheet in a state (a sheet-like and semi-cured thermosetting resin composition) X1 and pressing the pressing die 1 against the substrate 2 as shown in FIG. Has a pressing step of forming a through hole Y as a state of penetrating the material sheet X1 and reaching the substrate 2. If the sheet is taken out from the mold at the time of this pressing step, a semi-cured material sheet having a through hole is obtained.
The aspect of using a thermosetting resin composition as a product in a semi-cured state has never existed in the past.
Furthermore, in this invention, it has the hardening process which heats this material sheet | seat X1 completely and makes it the sheet-like product X2 in the state which pressed the press die 1 to the board | substrate 2. FIG.
The “sheet-shaped and semi-cured thermosetting resin composition” as used in the present invention is a semi-cured sheet-like article that is stable in a semi-cured state until heated to a complete curing temperature. The thermosetting resin composition in a state where it can be handled. Details of the semi-cured state will be described later. The sign “X1 (→ X2)” in FIG. 1B suggests that the semi-cured material sheet X1 is completely cured by heating to become a sheet product X2.
By having at least the above-mentioned steps, as described in the explanation of the effect of the invention, handling of the material before molding becomes easier, stamping debris does not occur at the time of molding, deformation after molding is suppressed, As shown to 1 (c), the sheet-like thermosetting resin molded product X2 which has the through-hole Y can be obtained preferably. Further, when not completely cured, a sticky sheet product is obtained.

First, a thermosetting resin composition that can be used as a material sheet in the present invention and can be in a semi-cured state will be described in detail.
The thermosetting resin composition is a resin composition in which a monomer or oligomer (prepolymer) is irreversibly polymerized (crosslinked) and cured.
Examples of thermosetting resin compositions that can be in a semi-cured state include silicone resins, epoxy resins, diallyl phthalate resins, phenol resins, unsaturated polyester resins, polyimide resins, polyurethane resins, melamine resins, urea resins, etc. The composition containing is mentioned. Among them, from the viewpoint of the accuracy of the through-hole formed, a composition containing a silicone resin, an epoxy resin, a phenol resin, or an unsaturated polyester resin is suitable, and is excellent in chemical resistance, weather resistance, light resistance, and heat resistance. From the viewpoint, a silicone resin composition is particularly preferable.
Therefore, a sheet made of a silicone resin composition having a property that remains in a semi-cured state until heated to the curing temperature is a preferable material sheet.

The thermosetting resin composition contains a monomer or oligomer (prepolymer) that can be polymerized (crosslinked) as a main component. Moreover, in addition to this, you may contain the reaction inhibitor, catalyst, etc. for controlling superposition | polymerization (crosslinking) reaction. In addition, it may contain a solvent such as toluene, xylene, ethylbenzene, hexane, isopropanol, methyl isobutyl ketone, cyclopentanone, propylene glycol monomethyl ether acetate, or a known additive. Or you may contain 2 or more types.

The silicone resin composition that can be in a semi-cured state, or the material sheet that is in a semi-cured state using the silicone resin composition may be a commercially available product or may be formed according to a known method.
Among known material sheets, the semi-cured silicone resin sheet described in Japanese Patent Application Laid-Open No. 2010-159411 includes a silicon compound having a substituent capable of condensation reaction and a substituent capable of addition reaction. It is obtained by condensation reaction of a silicone resin composition containing a silicon compound (sometimes abbreviated as “mixed silicone resin composition” hereinafter), exhibits a stable semi-cured state, and has light resistance. Since it is excellent in heat resistance, it is a particularly preferable material sheet for the production method of the present invention.
The semi-cured silicone resin sheet of the above publication is cured from an uncured state called A stage to a semi-cured state called B stage (curing in the first stage), and from B stage (semi-cured state) to C stage ( Curing to the fully cured state (second stage curing) is performed by separate reactions.
That is, by performing the first-stage curing by a condensation reaction and the second-stage curing by an addition reaction, the reaction is controlled using the fact that the reaction temperature conditions of both reactions are different, and each curing proceeds in stages. Thus, a semi-cured resin sheet that has been cured in the first stage is obtained.
Furthermore, since the second stage curing reaction proceeds not by natural factors but by external factors, it is possible to maintain the state at the time when the first stage curing is completed, that is, the semi-cured state. Yes.
Furthermore, by controlling the density of the functional groups involved in each reaction, it is possible to control physical properties such as viscoelasticity, toughness, and tack of the semi-cured product and the fully cured product.
In this publication, a semi-cured product, that is, a product in a semi-cured state (B stage), is a state between a solvent-soluble A stage and a completely cured C stage, which is cured and gelled. Means a product that swells slightly in the solvent but does not dissolve completely, and is softened by heating but not melted. The fully cured product (completely cured product) is completely cured and gelled. Means an object in a state of progressing].
Further, the mixed silicone resin composition preferably contains a compound capable of reacting with both a silicon compound having a substituent capable of condensation reaction and a silicon compound having a substituent capable of addition reaction.
In addition to the silicone resin sheet of the above publication, SYLGARD 184 (registered trademark) (manufactured by Toray Dow Corning Co., Ltd.) and the like can be mentioned as preferred silicone resin compositions. SYLGARD 184 (registered trademark) is an addition reaction type silicone resin composition to which a reaction inhibitor is added in order to obtain a semi-cured state. (Silicon compound having hydrosilyl group), 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (reaction inhibitor), platinum catalyst (reaction catalyst), xylene, ethylbenzene, etc. including.

Each curing temperature (temperature at which the resin is completely cured) of each semi-cured thermosetting resin composition described above varies depending on each resin composition, but the thermosetting resin composition normally used by those skilled in the art is completely What is necessary is just the temperature used when making it harden | cure, What is necessary is just to set based on the property of resin.

The size and shape of each part of the sheet-like product manufactured according to the present invention are not particularly limited, and may be a dimension or shape according to demand. The present invention is characterized by a special process of performing a molding process on a semi-cured material sheet. From the viewpoint that the material to be placed in the mold is a sheet, the sheet thickness is suitable for molding. The size (the dimension indicated by reference sign t2 in FIG. 1B) is preferably in the range of about 50 μm to 1000 μm.
In particular, when forming a sheet-like product in which a large number of fine through-holes are formed on a very thin sheet having a thickness of 70 μm to 700 μm and further to a thickness of about 100 μm to 500 μm, the variation in dimensions is small. The feature of the present invention that there are few penetrations (molding defects) is sufficiently exerted, and quality problems peculiar to the case where many fine through holes are formed are solved.
For example, even a fine molding defect that is acceptable in normal resin molding cannot be permitted when a fine through hole is formed, which causes a problem. In conventional resin molding methods such as injection molding, a large number of projections are provided in the mold in order to form a large number of fine through-holes, so that the molding resin is sufficiently distributed between the numerous projections. In other words, various deformations and dimensional defects are generated in the through-holes, such as missing due to bubbles or deformation due to sink marks.
On the other hand, according to the manufacturing method using the above-described semi-cured material sheet, since the heat-curing is performed in a state in which the protrusion of the pressing mold is pushed into the material sheet, the material does not spread, Deformation due to air bubbles and sink marks is suppressed, and as a result, the dimensional accuracy of the through holes and each part is improved. Due to such processing into a semi-cured material sheet, the diameter error of each through hole is within ± 10%, especially within ± 5%, and the through hole having a residual film in the opening The abundance ratio is 5% or less, especially 1% or less.
Moreover, the following various advantages are also obtained by the present invention. Since it is in the form of a sheet, it is easier to store the material in the stage before molding than in the liquid state. When the amount of material to be inserted into the mold is a liquid material, it is weight management or volume management, whereas in the case of a sheet, it can be managed by thickness. It is easy to develop into a continuous process and can improve productivity. Unlike injection molding, a mold with a complicated structure is not required.
The sheet surface of the sheet-like product (the main surface of the sheet on which the opening of the through hole is present) is a typical and preferred embodiment, but it is a stepped surface even if it is a curved surface according to demand. It may be. What is necessary is just to form the surface of a main body part of a below-mentioned die and a substrate surface so that such a sheet surface can be obtained.

The number of through holes in the sheet-like product manufactured according to the present invention may be one or more. However, as described above, the present invention is applied to a fine structure in which a large number of fine through holes are arranged on a thin sheet surface. The usefulness of becomes particularly remarkable.
The shape of the through hole may be a straight tubular hole (straight hole) Y having a constant cross-sectional area as shown in FIG. 3 (a), but the cured product can be easily peeled off from the mold. From the point of doing, it is good also as a through-hole which provided the required draft. Moreover, as shown in FIG. 3B, if the shape includes a funnel-shaped portion Y1 in which the area of the cross section decreases as it moves from the surface on the pressing die side of the sheet-like product to the substrate side, FIG. It is preferable because it meets various demands that require a funnel-like portion like the reflector shown in FIG.
In the example of FIG. 1 (c), the entire through hole is a funnel-shaped portion, and in the example of FIG. 3 (b), the straight tubular portion Y2 is connected directly below the funnel-shaped portion Y1 (ie, on the substrate side). ing. In the example of FIG. 3C, the sheet-like product has a structure having a straight tubular portion Y3, a funnel-shaped portion Y1, and a straight tubular portion Y2 in order from the surface on the pressing die side.

Examples of the opening shape and the cross-sectional shape of the through hole include a circle, a quadrangle, a polygon, and an irregular shape. When the through-hole has a funnel-shaped part and a straight tubular part as shown in FIGS. 3B and 3C, the shape of the cross-section of each part is selected and combined according to demand. It's okay.
In the example of FIG. 4A, the shapes of the cross sections of the funnel-shaped portion Y1 and the straight tubular portion Y2 are circular, and the through hole is a shape in which a truncated cone shape and a cylindrical shape are connected. In the example of FIG. 4B, the shape of the cross section of the funnel-shaped portion Y1 and the straight tubular portion Y2 is a square, and the through hole has a shape connecting a truncated pyramid shape and a prism shape. In the example of FIG. 4C, the shape of the cross section of the funnel-shaped portion Y1 is square, and the shape of the cross section of the straight tubular portion Y2 is circular. These are merely examples of combination, and various cross-sectional shapes may be combined.
Among the above combination examples, as shown in FIG. 4C, the through-hole in which the truncated pyramid-shaped funnel-shaped portion Y1 and the cylindrical straight tubular portion Y2 are used in a reflector for LED lighting, for example. In addition, the light from the LED can be effectively reflected, resulting in high efficiency and low power consumption.
Further, as illustrated in FIG. 5, when a large number of through holes are arranged adjacent to each other in a matrix, the light can be efficiently reflected and the amount of resin can be reduced by making them adjacent to each other as described above. Can be economical.
In addition, the structure in which the through holes in which the pyramidal trapezoidal funnel-shaped portion Y1 and the cylindrical straight tubular portion Y2 are combined as shown in FIG. 5 are densely arranged in an array is divided for each through-hole. There is also an advantage that the product is easy to produce and there is little variation in the pressure distribution during pressing in the mold.

The size of the through hole is not particularly limited. For example, when the fine through hole is formed in a very thin sheet having a thickness of 50 μm to 1000 μm (more preferably about 100 μm to 500 μm) as described above, FIG. The opening diameter d1 of the funnel portion of the through hole and the length w1 of one side of the opening shown in (b) are preferably about 100 μm to 1000 μm, and the opening diameter d2 of the straight pipe portion and the length of one side of the opening The length w2 is preferably about 90 μm to 900 μm.
Further, the opening angle of the funnel portion (angle θ shown in FIG. 3B) is preferably 30 to 120 degrees, and more preferably 45 to 90 degrees.

The arrangement form of the through holes in the case of forming a plurality of through holes is not particularly limited, but for example, a lattice arrangement form (a form arranged at the intersection of lattices), a concentric arrangement form, an equilateral triangle In a network having a minimum mesh shape, a form in which a through hole is arranged at the apex of the equilateral triangle, an arrangement along a character, a pattern or a symbol, an irregular arrangement, an arrangement combining them, and the like are shown in FIG. In this way, adjacent through holes may be formed adjacent to each other, or may be formed at intervals.

In the pressing step according to the present invention, as shown in FIG. 1B, when the pressing die 1 is pressed against the substrate 2, the material portion of the material sheet X1 is pushed out by the pressing die projections 12 and excluded around the projections. Then, the material is brought into close contact between the tip surface of the pressing die and the substrate surface so that the material does not remain in the form of a film. And as it is, in the curing step, the material sheet is heated and cured. As a result, as shown in FIG. 1 (c), the sheet thickness t2 of the product X2 can be controlled with high accuracy in accordance with the height h of the protrusion of the pressing mold, and a thermosetting sheet having a uniform and uniform thickness is obtained. This is preferable.
On the other hand, as shown in FIG. 2, when the pressing die 1 is pressed against the substrate 2, the protrusion 12 penetrates the material sheet X1, but the pressing die main body portion 11 does not compress the material sheet X1. Heat curing may be performed in such a state.
As shown in FIGS. 1 and 2, the thickness t1 of the material sheet X1 may be appropriately determined according to how much material is pushed out by the pressing die in the pressing process to the curing process as described above. For example, in order to reduce the amount of protrusion of the resin, the thickness t2 of the sheet-like product X2 after pressing and curing is almost determined by the projection height h of the projection 12, so the thickness t1 of the material sheet is determined by the projection It is preferable to make it thinner than the projection height h of 12 by a necessary amount (by taking into account the volume of the projection). Also, as shown in FIG. 2, if the material sheet is not properly compressed at the time of heat curing, is the thickness t1 of the material sheet equal to the thickness t2 of the sheet-like product X2 after pressing by the pressing mold to curing? Alternatively, it is preferable that the thickness is reduced by an amount corresponding to the expected swelling of the material.
For example, the thickness t1 of the material sheet is 10 to 95% of the thickness in the state where the pressing die is pressed against the substrate (the material is pushed away by the protrusions, the state shown in FIGS. 1 and 2). The thickness is preferably 20% to 90%, and more preferably 20% to 90%.

Hereinafter, in the case of forming as shown in FIG. 1, the pressing die, the substrate, the pressing step, the curing step, etc. will be described in detail, but also in the case shown in FIG. Except for this, the description of FIG. 1 may be referred to.

As shown in FIG. 1A, the pressing die may be a thermosetting resin forming die having at least a pressing body portion 11 and a protrusion 12.
The material constituting each part of the die has at least mechanical strength (tensile strength, rigidity, hardness, etc.) and heat resistance that can be used as a mold for thermosetting resin, and further has chemical resistance, Any material may be used as long as it has processability for forming the pressing mold, repeated durability, wear resistance, and the like. Examples of such a material include metal materials such as nickel, nickel alloy, and carbon steel, and ceramics such as alumina, zirconia, and silicon carbide.

The main body portion 11 and the protruding portion 12 may be integrally formed of the same material, or may be one in which a pin-like object that becomes a protruding portion is embedded in the main body portion. As described above, when forming a sheet-shaped product having a fine structure in which a large number of fine through-holes are formed in a very thin sheet, the protrusion of the pressing die also becomes a fine pin-like product, which can be formed as a separate part or mold. Assembling becomes difficult. Therefore, in such a case, a pressing die in which the main body portion and the protruding portion are integrally formed is preferable.
In a fine stamping die for forming a fine-structured sheet-like product, the method for integrally forming the main body portion and the protrusion is not particularly limited, and various conventionally known pattern forming techniques and fine processing are used. Technology may be used.

The shape of the protrusion of the pressing die may be a shape having a shape and a dimension capable of forming the above-described through hole. The description of the shape of the through hole described above with reference to FIGS. 3 to 5 is also a description of the shape of the protrusion as it is (the concavo-convex shape is inverted with respect to each other). However, in consideration of draft angle and shrinkage after manufacturing, only a small amount of correction necessary for the dimension of the through hole may be added.
As shown in FIG. 6, the shape of the protrusions for forming the through-holes illustrated in FIG. 3B and FIG. 5 is such that each of the protrusions 12 includes a truncated pyramid part y1 and a cylindrical part y2. It becomes a three-dimensional shape combined.

The main body portion of the pressing die only needs to have a surface as a mold for forming the main surface of the sheet-like product, and a protrusion is provided on the surface. What is necessary is just to determine suitably the thickness of this main-body part, the attachment structure part to the press apparatus for shaping | molding, etc. according to the surrounding apparatus structure at the time of use. For example, the main body portion may be a sufficiently thick plate having a thickness of about 5 mm to 100 mm, or a thickness of about 500 μm to 3 mm formed or bonded as a surface layer to a sufficiently thick plate-like support. It may be a thin plate.

The substrate has at least a surface that forms a sheet surface of a semi-cured material sheet, has mechanical strength capable of receiving a pressing force from the pressing die, and heat resistance that can be used as a molding die for a thermosetting resin. Any material having at least properties may be used.
In a preferred embodiment of the manufacturing method, an embodiment in which a buffer layer having relatively large elasticity is provided on the substrate, the back surface of the pressing die, or both is recommended. For example, due to a dimensional error in the thickness direction of the pressing die or the substrate, an error in the distance between the installation surfaces of the upper and lower die installation plates of the molding press apparatus, a plurality of Some protrusions cannot come into contact with the substrate, and defective through holes (penetration defects) occur. The influence of such an error appears more prominently when the product sheet is thinner and the through holes are finer.
On the other hand, as illustrated in FIG. 7, by providing the buffer layer 22 having relatively large elasticity on the substrate 2, the buffer layer 22 absorbs the dimensional error as described above, so that the pressure is dispersed. In addition, all the protrusions of the pressing die 1 can come into contact with the substrate surface, and occurrence of poor penetration can be suppressed.
On the other hand, according to the study by the present inventors, if a buffer layer is simply provided on the surface of the substrate, protrusions enter the buffer layer, causing irregularities on the sheet surface of the sheet-like product, or in-plane pressure distribution. As a result, there arises a problem that non-through holes are formed. Therefore, it is preferable that the substrate receiving the pressing mold is a layer made of a hard material that does not cause unevenness and undulation.
As shown in FIG. 7, the substrate 2 has a surface layer 21 made of a hard material and a relatively large elasticity, as shown in FIG. It is a preferable embodiment that the laminate has the buffer layer 22 having the same.

The buffer layer only needs to have heat resistance with respect to the complete curing temperature in the curing step, and for example, a layer made of plastic, rubber, or the like can be used. Examples of the rubber used for the buffer layer include silicone rubber, fluorine rubber, ethylene / vinyl acetate rubber, and acrylic rubber.
The thickness of the buffer layer is not particularly limited, but when the sheet is thinner and the through holes are finer, the thickness is preferably about 100 μm to 2000 μm, more preferably 300 μm to 1000 μm. Thereby, the in-plane pressure distribution can be made more uniform, the formation of the through hole is facilitated, and the penetration failure is also reduced.

The surface layer (or the substrate itself when the substrate is a single layer without providing a buffer layer) is appropriately subjected to pressure from the projections in order to prevent deformation of the projections of the pressing mold due to pressure. Preferably, the material is plastically deformed, and is made of, for example, a metal (eg, aluminum, copper, stainless steel, etc.) having a hardness lower than that of the protrusion, plastic (eg, polyimide, silicone resin, polyester, polycarbonate, etc.), etc. Can be suitably used.
Further, even if the surface layer is made of a metal having high hardness, if the surface layer is a thin surface layer provided on the buffer layer, it can be deformed by an appropriate amount when the pressing projection is pressed. In addition, it also serves as a surface layer made of a hard material.

The thickness of the substrate is not particularly limited, but the thickness of the surface layer in the case of the laminate is preferably 50 μm to 500 μm, more preferably 100 μm to 300 μm. Thereby, pressurization distribution can be made more uniform and formation of a through-hole becomes easy.

The laminate composed of the surface layer 21 and the buffer layer 22 described above may be provided as the surface layer 13 and the buffer layer 14 also behind the stamping die 1 as shown in FIG. Accordingly, absorption of dimensional errors by the buffer layer and uniformity of the applied pressure are more preferable.

As described above, the semi-cured thermosetting resin composition used in the present invention is a sheet (material sheet) formed at the time of molding, and is disposed between the pressing die and the substrate.

The material sheet may be a sheet-like material composed only of the above-mentioned semi-cured thermosetting resin composition. However, from the viewpoint of arrangement in the mold and handleability, as shown in FIG. A mode in which the material sheet X1 is provided to the pressing step as a semi-cured thermosetting resin composition layer X1 laminated on the sheet substrate S with the sheet substrate S as a support is preferable.
In the case of this aspect, as shown in FIG. 7, the semi-cured thermosetting resin composition layer X <b> 1 is disposed between the mold 1 and the substrate 2 so that the sheet base S is on the substrate 2 side. By doing so, in the pressing step and the curing step, the sheet base material S is interposed between the tip of the protrusion of the pressing die and the substrate. Although the through-hole is not formed in the sheet base material S, a pressing mark due to the protrusion of the pressing die may remain.

The sheet base material may be any material having rigidity useful as a support and heat resistance against the curing temperature of the thermosetting resin composition. For example, polyester (eg, polyethylene terephthalate (PET)) , Polyimide, polycarbonate, polyolefin and the like.
The thickness of the sheet base material is not particularly limited, but is preferably about 10 μm to 300 μm, and more preferably about 30 μm to 200 μm.

When using the said base material for sheets, you may give a peeling process to the surface of this base material for sheets so that it may peel easily after hardening a material sheet | seat.
The peeling treatment may refer to a mold release treatment in a known thermosetting resin molding, and examples thereof include fluorine treatment and silicone treatment.

A conventionally known apparatus may be used as the molding press apparatus for carrying out the production method of the present invention. The example shown in FIG. 7 shows a configuration example in which the material sheet X1 is pressed between the pressing die 1 and the substrate 2 with a predetermined pressure by the molding press device. In FIG. 7, only the upper and lower parallel plate stages 10 and 20 are shown, and the drive unit is omitted. Further, in the example of the figure, the substrate 2 is a laminate having a surface layer 21 made of a hard material and a buffer layer 22 having a relatively large elasticity, and the surface layer 13 is also behind the die 1. A laminated body including the buffer layer 14 is provided.
The parallelism of the opposing surfaces of the upper and lower parallel plate stages 10 and 20 may be within a range that can be suppressed within the variation in pressure distribution that is allowed by the buffer layer or the like. When the substrate is composed of a buffer layer and a surface layer, the pressure distribution variation is preferably ± 10% or less, and more preferably ± 5% or less.

Further, as a molding press device, for example, if a pressurizing means having followability with respect to the target shape, such as a diaphragm of a vacuum pressurizing laminator, is used, it is possible to reduce variation in pressure distribution, which is preferable. .

The heating method for heating the material sheet, such as heating to the curing temperature in the curing step and preheating in the pressing step, is not particularly limited, but is provided on the upper and lower parallel plate stages of the above-described molding press device. The parallel plate stage is heated by a heating means (heater), thereby heating the pressing die and the substrate, thereby heating the material sheet, or by directly attaching the heating means to the pressing die and the substrate. The method of heating is mentioned.

Hereinafter, the processing content will be illustrated in more detail along each step of the manufacturing method of the present invention.
First, as shown in FIG. 1A or 7, the material sheet X <b> 1 is disposed between the pressing die 1 and the substrate 2.
Next, as shown in FIG. 1B, in the pressing step, a pressing die is pressed against the substrate to form a through hole in the material sheet X1. At this time, the material sheet is deformed and / or flows, and the protrusion 12 of the pressing die 1 penetrates the material sheet X1 and reaches the substrate.
Hereinafter, pressing the pressing die against the substrate is also referred to as pressurization. At the time of pressurization, pressure is also applied to the material sheet, and a through hole is formed in the material sheet, resulting in a state as shown in FIG. Since the sheet material is a thermosetting resin and hardly melts like a thermoplastic resin, its flow is limited. If the volume of the material sheet is excessively larger than the volume of the space between the protrusions of the pressing mold, the resin may be restored by elasticity after molding, and the accuracy of the through hole may not be obtained. Therefore, it is preferable to accurately adjust the conditions (particularly, the relationship between the volume of the space between the protrusions of the pressing die and the volume of the material sheet), and in particular, the material sheet greatly related to the fluctuation of the volume of the material sheet. It is preferable to adjust the thickness of the film accurately.

Although the pressure at the time of pressurization in the pressing step is not particularly limited, from the viewpoint of suppressing the generation of non-through holes (residual film formed as a result of the formation of a gap between the protrusion and the substrate surface). 1 MPa or more is preferable, and 3 MPa or more is more preferable. Moreover, it is preferable that it is 60 Mpa or less, and it is more preferable that it is 40 Mpa or less from the point of suppressing the failure | damage of the press die 1 and the deformation | transformation of the board | substrate 3. FIG.
When a hardening process is provided, the pressurization in a press process is performed continuously and continuously until a hardening process is complete | finished from a press process.

The variation in pressure distribution during pressurization in the pressing step is usually preferably ± 5% or less. When the substrate is composed of a buffer layer and a surface layer, the variation in pressure distribution that can be tolerated due to the effect of the buffer layer. Is spread and is preferably ± 10% or less, more preferably ± 5% or less.

The pressing time in the pressing process (the time from when the protrusion reaches the substrate until the heating in the curing process starts) may be set according to the properties of the material sheet to be processed, etc. It is about 30 seconds to 600 seconds. For example, in the case of the mixed silicone resin composition in a semi-cured state, it is preferably 60 seconds to 500 seconds, and more preferably 100 seconds to 300 seconds. In this invention, a hardening process is performed with the state pressurized in the press process.

In the pressing step, preheating may be applied to the material sheet before pressing for the purpose of mitigating thermal shock to the resin due to a rapid temperature change and improving productivity.
The preheating temperature may be any temperature that does not cure the semi-cured material sheet, and varies depending on the material. However, in the mixed silicone resin composition in the semi-cured state, it is preferably about 40 ° C. to 130 ° C., 50 More preferably, the temperature is from about 0 to 120 ° C.
The preheating may be performed temporarily or continuously through the pressing process.
The preheating may be performed before the pressing step, may be performed after the material sheet is brought into contact with the substrate, or may be performed after sandwiching the material sheet.
The preheating may be performed by a heating means (for example, a known heater) installed directly or indirectly on one or both of the pressing die and the substrate.

When placing a semi-cured material sheet between the pressing mold and the substrate, it should be performed under vacuum conditions to prevent the material sheet from floating and mixing of bubbles between the mold and the material sheet. Alternatively, the material sheet may be arranged on the substrate in advance, and the die may be set after sufficiently floating and eliminating bubbles.
Further, a laminate of a sheet substrate and a semi-cured material sheet (thermosetting resin composition layer) is wound as a roll, and the sheet substrate and the semi-cured material sheet are substrated from the roll. It is also possible to suppress floating and air bubbles by adopting a continuous method in which the product sheet after being supplied is wound up and wound up as a roll.

In the curing step, as shown in FIG. 1B, the material sheet is heated to the curing temperature and completely cured while the pressing die is pressed against the substrate.
The curing temperature is not less than the minimum temperature at which a semi-cured material sheet can be completely polymerized (crosslinked) and completely cured, and the temperature does not degrade the quality of the resin composition Good. The curing temperature may be a temperature used when a thermosetting resin composition usually used by those skilled in the art is completely cured, and may be set based on the properties of the resin.

In the curing step, the time for raising the temperature from the temperature condition in the pressing step to the curing temperature (temperature raising time) is not particularly limited, but generally ranges from about 30 seconds to 900 seconds. In the case of the mixed silicone resin composition described above, it is preferably in the range of 40 seconds to 600 seconds, and more preferably in the range of 60 seconds to 300 seconds.

The time for holding the complete curing temperature after the temperature rise (holding time) is not particularly limited as long as it is set based on the properties of the resin, and generally includes about 30 seconds to 900 seconds. It is preferably in the range of seconds to 600 seconds, and more preferably in the range of 60 seconds to 300 seconds.

The pressurizing condition in the curing process may be the same as the pressurizing condition in the pressing process, and may be changed within the range of the pressurizing condition in the pressing process described above. The pressurization in the curing process may be performed continuously and continuously from the pressing process until the curing process is completed.

The pressing step and the curing step are preferably performed in a vacuum atmosphere from the viewpoint of removing foreign substances and filling the thermosetting resin composition.

As shown in FIG. 1 (c), the fully cured sheet product may be taken out at a high temperature after the curing step, or may be taken out after being cooled to room temperature.

As shown in FIG. 7, when the substrate 2 is a laminate having a surface layer 21 and a buffer layer 22, the surface layer 21 may be deformed every time a through hole is formed. In that case, it is preferable to replace the surface layer as appropriate every time the pressing step and the curing step are performed. Therefore, it is preferable that the surface layer 21 and the buffer layer 22 have an adhesion or attachment structure so that they can be easily attached and detached.
The buffer layer can be used repeatedly longer than the surface layer.

Hereinafter, although an example is given and the present invention is explained still more concretely, the present invention is not limited to these.
In the following examples, the manufacturing method of the present invention was carried out by using the same type of stamping die, changing materials and conditions, and the quality of the sheet-like product was evaluated.

As shown in part of the perspective view in FIG. 6, the structure of the pressing mold is such that the total protrusion height is formed on the main surface of the plate-like main body portion (the outer peripheral shape is a square with a side of 10 mm and a thickness of 1 mm) 11. The protrusions 12 having a thickness of 500 μm are arranged in a square matrix of 20 rows × 20 columns at a center-to-center pitch (a dimension corresponding to the symbol P in FIG. 5) of 500 μm.
As shown in FIG. 6, the shape of each protrusion 12 of the pressing die is a square pyramid-shaped portion (the bottom surface is a square having a side of 500 μm) y1, and a cylindrical portion on the tip side (diameter 270 μm). This is a shape in which y2 is connected in a continuous manner. The plan view of the push-type projection portion viewed from the side is as shown in FIG. 5 although the number of projection portions is different, and the base portions of adjacent projection portions are in contact with each other on the bottom surface.

The material of the stamping die is nickel, and a non-conductive master is formed using a photocurable resin by stereolithography, followed by conducting a conductive process, forming a conductive master, performing an electroforming process, and conducting It was produced by removing the sex master.

The substrate is a laminate composed of a surface layer and a buffer layer.
The surface layer is a 125 μm thick polyimide film (trade name: Kapton 500V, manufactured by Toray DuPont Co., Ltd.), and the outer peripheral shape is a square with a side of 15 mm.

The buffer layer is a 1 mm thick silicone rubber sheet (SR rubber sheet) (trade name: SR-70, manufactured by Tigers Polymer Co., Ltd.), and the outer peripheral shape is a square with a side of 15 mm. The Shore A hardness of the buffer layer was 70.

A precision heating and pressing device (trade name: CYPT-10, manufactured by Shinto Kogyo Co., Ltd.) was used as the molding press.

Example 1
[Production of semi-cured material sheet]
In this example, an addition reaction type silicone resin composition was used as the semi-cured silicone resin composition.
An uncured addition reaction type silicone resin composition (trade name: SYLGARD 184, manufactured by Toray Dow Corning Co., Ltd.) on a biaxially stretched polyester film (manufactured by Mitsubishi Plastics Co., Ltd.) having a thickness of 50 μm to a thickness of 250 μm. Apply and heat at 150 ° C. for 3 minutes to obtain a semi-cured and sheet-like (250 μm thick) addition-reactive silicone resin composition, processed into an outer shape of 10 mm × 10 mm, and semi-cured material A sheet was obtained.

[Pressing process to curing process]
Next, in order from the lower layer side, the buffer layer, the surface layer, the semi-cured material sheet, and the stamping die are set in this order, and this is set in a precision heating and pressing device that has been set to a preheating temperature of 50 ° C. And maintained for 60 seconds to perform preheating.
Next, the pressing die was lowered with the temperature kept at 50 ° C., and held at a pressure of 10 MPa for 300 seconds, and a pressing step was performed to form a through hole.
In a separate manufacturing test, a semi-cured material sheet is obtained by removing the material sheet from the mold at the stage after the pressing step, and does not have a large mechanical strength. It was found that a pressure-sensitive adhesive sheet was obtained.
After the pressing step, while maintaining the pressure, the temperature is raised from 50 ° C. to 150 ° C., which is the curing temperature, over 300 seconds. A sheet-like product having a completely cured state was obtained.

[Evaluation]
In the obtained sheet-like product, through holes having a diameter of 270 μm in the cylindrical portion were formed at a pitch of 500 μm. The machining accuracy was ± 10 μm, and it was found that machining was realized with high accuracy.
Further, there was no penetration failure (a hole in which a remaining film remained).

Example 2
[Production of semi-cured material sheet]
In this example, a mixed silicone resin composition was used to prepare a semi-cured silicone resin composition.
100 g of both-end silanol type silicone oil having an average molecular weight of 11500 (trade name: x-21-5842, manufactured by Shin-Etsu Chemical Co., Ltd.), vinyltrimethoxysilane (trade name: KBM-1003, manufactured by Shin-Etsu Chemical Co., Ltd.) After stirring and mixing 86 g and 10 mL of 2-propanol, 0.16 mL of tetramethylammonium hydroxide aqueous solution (concentration: 10% by weight) was added as a condensation catalyst, and the mixture was stirred at room temperature (25 degrees) for 2 hours.
To the obtained oil, 0.090 g of organohydrogenpolysiloxane (trade name: KF-99, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.26 mL of platinum-carbonyl complex solution (platinum concentration 2% by weight) as a hydrosilylation catalyst Was added to obtain an uncured mixed silicone resin composition.

The uncured mixed silicone resin composition was applied to a thickness of 500 μm on a 50 μm thick biaxially stretched polyester film (Mitsubishi Resin Co., Ltd.), heated at 80 ° C. for 10 minutes, A mixed silicone resin composition in a cured state and in a sheet form (thickness: 500 μm) was obtained and processed into an outer peripheral shape of 10 mm × 10 mm to obtain a semi-cured material sheet.

[Pressing process to curing process]
Next, in order from the lower layer side, the buffer layer, the surface layer, the semi-cured material sheet, and the stamping die are set in this order, and this is set in a precision pressure heating device that has been set to a preheating temperature of 50 ° C. And maintained for 60 seconds to perform preheating.
Next, the pressing die was lowered with the temperature kept at 50 ° C., and held at a pressure of 10 MPa for 300 seconds, and a pressing step was performed to form a through hole.
As in the above example, in a production test separately conducted in the same manner, a material sheet in a semi-cured state can be obtained by removing the material sheet from the mold at the stage after the pressing step, and does not have a large mechanical strength. It was found that an adhesive sheet having through-holes was obtained.
After the pressing step, while maintaining the pressure, the temperature is increased from 50 ° C. over 300 seconds to 180 ° C. which is the curing temperature, and kept at 180 ° C. for 300 seconds to thermally cure the material sheet, and through holes A sheet-like product having a completely cured state was obtained.

Example 3
In the pressing process to the curing process, except that the surface layer is not used as the substrate and only the buffer layer is used, the material sheet in a semi-cured state is molded in the same manner as in Example 2, and a completely cured state having through holes is formed. A sheet-like product was formed.

[Evaluation]
When the through-holes of the obtained sheet-like product were examined, penetration defects (holes with remaining film) existed in some of the holes, but the sheet-like product having the desired through-holes was obtained. It was.

Example 4
Except that the buffer layer is not used as the substrate and only the surface layer is used as the substrate in the pressing process to the curing process, the semi-cured material sheet is molded in the same manner as in Example 2, and a completely cured state having through holes is obtained. A sheet-like product was formed.

[Evaluation]
When through holes of the obtained sheet-like product were examined, there was a penetration failure in some of the holes (holes in which the remaining film remained), but a sheet-like product having the desired through-hole was obtained. I was able to. This is considered to be a result of the variation in pressure distribution becoming larger due to the influence of the stage parallelism (40 μm) of the pressurizer.

By the method for producing a resin molded product according to the present invention, a molded product made of a thermosetting resin in which through holes having various shapes are formed with high accuracy can be produced at a low cost without generating a punching residue. became. As a result, high quality LED reflectors, speaker housings, inkjet printer nozzles, ultrafine filler filters, medical nebulizer nozzles, and the like can be manufactured at low cost.

This application is based on Japanese Patent Application No. 2013-037630 filed in Japan (filing date: February 27, 2013), the contents of which are incorporated in full herein.

Claims

A method for producing a sheet-like thermosetting resin molded article having a through-hole,
A thermosetting resin composition that is in the form of a sheet and is semi-cured is disposed between a pressing die having a protrusion for forming the through hole and a substrate facing the pressing die. Pressing the substrate to form a through hole in the semi-cured thermosetting resin composition,
The manufacturing method.
After the pressing step, further including a curing step of completely curing the semi-cured thermosetting resin composition by heating to a curing temperature while the pressing die is pressed against the substrate.
The manufacturing method according to claim 1.
The manufacturing method according to claim 1, wherein the thermosetting resin composition having a sheet shape and being in a semi-cured state is a silicone resin sheet having a property of remaining in a semi-cured state until heated to a curing temperature. .
The thermosetting resin composition having a sheet shape and in a semi-cured state is further accompanied by a sheet base material, and the semi-cured thermosetting resin composition layer is formed on the sheet base material. By laminating, it provides the pressing process as a sheet-like laminate,
By placing the semi-cured thermosetting resin composition layer between the pressing mold and the substrate so that the sheet base material is on the substrate side, in the pressing step and the curing step, the protruding portion of the pressing mold The manufacturing method according to claim 1, wherein the sheet base material is interposed between the tip of the substrate and the substrate.
The substrate is a laminate having a surface layer and a buffer layer below the surface layer,
The manufacturing method according to claim 1, wherein the surface layer is thinner than the buffer layer.
The manufacturing method according to claim 1, wherein the shape of the through-hole is a shape having a funnel-shaped portion in which the area of the cross section decreases as it moves from the surface of the thermosetting resin composition to the substrate side.
The manufacturing method according to claim 6, wherein the shape of the through-hole is a shape having a straight tubular portion having a constant cross-sectional area on the substrate side of the funnel-shaped portion.
The manufacturing method according to claim 6, wherein the shape of the funnel-shaped portion is a truncated cone or a truncated pyramid, and the shape of the straight tubular portion is a columnar shape or a prismatic shape.