JP2009009735A - Manufacturing method of keytop member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a keytop member which has a high surface hardness, and in which the edge of the keytop can be maintained sharp. <P>SOLUTION: This is a manufacturing method of a keytop member which has one or two or more keytops and a connecting part for connection at the bottom of the keytops, and comprises an arrangement process (step S102) to arrange a substrate sheet on a first aperture of a mold frame of silicon rubber having a first aperture for forming the connecting part and a second aperture which is inside the first aperture and further recessed and forms the keytop, a resin injection process (step S103) in which resin containing at least acrylate based resin is injected in each aperture of the mold frame, and a hardening process (step S104) to harden the resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a key top member.

  Conventionally, in order to improve the wear resistance of the surface of a key top used in a mobile phone or the like, a hard coat layer having a hardness higher than that of the key top is formed on the surface of the key top. As a method for forming a hard coat layer, a method of spray-coating a hard coat material on the surface of a key top is generally known (see Patent Document 1).

JP 2000-182468 A (Detailed Description of the Invention)

  However, as disclosed in Patent Document 1, when the hard coat layer is formed by spray coating, a liquid reservoir of the hard coat material is likely to be formed on the edge of the key top. As a result, the edge of the key top is rounded and the sharp shape is lost. In spray coating, the hard coat material is not uniformly cured or contracted during curing, and residual stress is generated. As a result, cracks (cracks) occur in the hard coat layer after curing, or the hard coat layer is easily peeled off from the surface of the key top. Therefore, it is difficult to obtain a hard coat layer having a uniform thickness by spray coating.

  Furthermore, a method of forming a key top by embossing the resin sheet for forming the key top after performing a hard coating treatment is also conceivable. However, in this method, it is difficult to perform embossing when the resin sheet is too thick. Moreover, when the thickness of a resin sheet is too thin, the one part will be extended extremely and the intensity | strength of a part of the said resin sheet will fall.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for manufacturing a key top member that has a high surface hardness and can hold the edge of the key top sharply. is there.

  In order to solve the above-described problems, the present invention provides a method for injecting an acrylic resin, which is a hard coat material, into a mold without applying a hard coat material to a key top member or embossing a resin sheet. The member is manufactured. At this time, molding is performed using a silicone rubber mold. Specifically, the key top member manufacturing method according to the present invention is a method for manufacturing a key top member comprising one or more key tops and a connecting portion connected to the bottom of the key top, A silicone rubber mold having a first opening for forming a connecting portion and a second opening for forming a key top which is in the first opening and is further recessed. An arrangement step of arranging the base sheet on the first opening, a resin injection step of injecting a resin containing at least an acrylate resin into each opening of the mold, and a curing step of curing the resin And.

  When such a manufacturing method is adopted, the key top member itself is formed of a hard coat material, and thus the conventional hard coat layer is not peeled off or cracked. In addition, since there is no process of applying a hard coat material, the process can be simplified and the edge of the key top can be kept sharp as long as the edge of the opening in the silicone rubber mold is sharpened. be able to. Moreover, since embossing is not employed, a high-strength key top member can be obtained. Furthermore, since a silicone rubber mold is used without using a metal mold, the key top member after resin curing can be easily removed from the mold without using a release agent.

  According to another aspect of the present invention, the mold is an opening for forming a convex portion on the top surface of the key top, and the third opening is further recessed in the second opening. Or it is a protrusion part for forming a recessed part in the top | upper surface of a keytop, Comprising: It shall have in the 2nd opening part the protrusion part which protrudes from the bottom face.

  When a keytop member is manufactured using such a formwork, even if there is a very small portion with a difference in height, such as a convex portion or a concave portion formed on the top surface of the keytop, it is sharp without causing cracks. It can be manufactured in a form having an edge.

  In another aspect of the present invention, the base sheet is a transparent resin sheet, the resin includes at least an acrylate resin and a photopolymerization initiator, and a curing process is performed by irradiating the resin with light through the base sheet. The process of curing the resin.

  Thus, when a keytop member is manufactured using a photocurable resin, since the curing rate is high, the manufacturing period can be shortened. Also, normal pressure molding can be realized easily.

  Further, according to another aspect of the present invention, in the resin injecting step, a resin having a viscosity at 23 ° C. in the range of 10 mPa · S to 300,000 mPa · S is injected into each opening of the mold.

  In this way, when a photocurable resin having a specific range of viscosity is used, the resin can be filled into every corner of the mold, and it becomes easy to manufacture a key top member having a sharp edge even under normal pressure molding. . When the viscosity is 10 mPa · S or more, even a thin key top member can be easily manufactured. On the other hand, when the viscosity is 300000 mPa · S or less, a sharp edge can be formed even with a key top member having fine irregularities.

  Further, in the present invention, in the resin injection step, a resin having a value indicating thixotropy at 23 ° C. in the range of 0.5 to 3.0 is injected into each opening of the mold. .

  As described above, when a photocurable resin having a specific range of thixotropy is used, it becomes easy to manufacture a key top member having a uniform strength and a sharp edge. When the value indicating thixotropy is 0.5 or more, a plurality of materials (including additives, fillers, etc.) constituting the resin can be uniformly dispersed, so that the key top has less strength variation depending on the location. The member can be easily manufactured. On the other hand, when the value indicating thixotropy is 3.0 or less, since the resin can be injected without entraining bubbles, a key top member having fine irregularities can be easily manufactured.

  According to the present invention, a key top member having a high surface hardness and capable of holding the key top edge sharply can be manufactured.

  Hereinafter, the manufacturing method of the key top member which concerns on one embodiment of this invention is demonstrated based on FIGS. In the following description, the arrow X1 direction shown in FIGS. 2 to 4 is up, the arrow X2 direction is down, the arrow Y1 direction is left, the arrow Y2 direction is right, the arrow Z1 direction is table and arrows. The direction indicated by Z2 is defined as the back.

  FIG. 1 is a flowchart showing each step of a method for manufacturing a keytop member according to an embodiment of the present invention.

  As shown in FIG. 1, the manufacturing method of the key top member according to the present embodiment includes a decoration process (S101), an arrangement process (S102), a resin injection process (S103), and a curing process (S104). And each step of a mold release step (S105).

  FIG. 2 is a perspective view of the mold 10 used in the method for manufacturing a keytop member according to one embodiment of the present invention, and shows a state in which the mold 10 is viewed from the opening side. FIG. 3 is a view for explaining a method for manufacturing a keytop member according to an embodiment of the present invention, (A) is a view for explaining an arrangement step (S102), and (B). These are figures for demonstrating a resin injection | pouring process (S103). FIG. 4 is a diagram for explaining a method for manufacturing a keytop member according to an embodiment of the present invention following FIG. 3, and FIG. 4A is a diagram for explaining a curing step (S 104). (B) is a cross-sectional view of the key top member after the mold release step (S105).

  As shown in FIG. 1, first, the decoration layer 28 is formed on one side of the base sheet 26 (step S101). Examples of the method for forming the decorative layer 28 include printing methods such as gravure printing, silk printing, letterpress printing, offset printing, hot stamping, and flexographic printing using UV-curable and thermosetting screen inks. The method for forming the layer 28 is not particularly limited to these methods. Alternatively, full-color on-demand printing using a computer image and a printer may be used. In addition, before forming the decorating layer 28, after performing surface treatments, such as UV treatment, a corona discharge process, or a sputtering process, once to the base material sheet 26 as needed, when the decorating layer 28 is formed, One layer makes it easier to form the decorative layer 28.

  Next, as shown in FIG. 3A, the base sheet 26 is arranged on the silicone rubber mold 10 so that the surface on which the decorative layer 28 is formed faces inward of the mold 10 ( Step S102). As shown in FIG. 2, the mold 10 has one first opening 11 having a substantially rectangular parallelepiped space. Twelve second openings 13 having a substantially rectangular parallelepiped space that is recessed in the back direction are formed in the bottom 12 of the first opening 11. On the bottom surface 14 of each second opening 13, a third opening 15 that is further recessed in the back direction is formed. The 1st opening part 11 is the space for forming the flat connection part which connects the bottom part of each keytop in a keytop member. The second opening 13 is a space for forming each key top. The third opening 15 is a space for forming convex numbers, characters, or symbols (convex portions) on the top surfaces of the key tops. Specifically, the third opening 15 is a concave portion in which a total of 12 numbers and symbols of numbers “0” to “9”, asterisk (*) and sharp (#) are inverted.

  The base sheet 26 is a resin plate having an area slightly smaller than the opening surface of the first opening 11 in the mold 10. For this reason, in the resin injection process (step S103) described later, the resin is injected from a gap existing between the base sheet 26 and the opening surface of the first opening 11.

  The base sheet 26 is a thin resin sheet having translucency. As the base material sheet 26, a sheet made of a thermoplastic resin can be suitably employed. As the thermoplastic resin, for example, polyvinyl polymers such as polyvinyl chloride, polyvinylidene chloride, vinyl acetate-vinyl chloride copolymer, polyvinyl fluoride, polyvinyl butyral, polyvinylidene fluoride, polystyrene, acrylic Styrene resins such as ABS, styrene resins such as polyethyl methacrylate, polymethyl methacrylate, and acrylic resins such as polyacrylonitrile (PMMA resins), polyolefins such as polyethylene, polypropylene, and polymethylpentene Polyester resins and polyester resins such as resins, cellulose acetates such as cellulose acetate and nitrocellulose, polyamide resins, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate-isophthalate copolymer Sutoma, butadiene rubber, chloroprene rubber, a rubber-based resin such as silicone rubber, vinylon, polyvinyl alcohol or the like of the polyvinyl alcohol-based resin and urethane-based, PC resins. Examples of the thermosetting resin include epoxy resins, polyurethane resins, polyimide resins, polyamide imide resins, urea resins, and melamine resins. Among these, in particular, PMMA-based resins, PC-based resins, and ABS-based resins are suitable as materials for the base sheet 26 because of their high transparency and excellent workability and dimensional stability. Moreover, it is preferable that the thickness of the base material sheet 26 shall be 20 micrometers or more and 2000 micrometers or less. When the thickness is 20 μm or more, a click feeling of the key top is easily obtained, and when the thickness is 2000 μm or less, machining is easy and the key top member can be thinned. The thickness is more preferably 50 μm or more and 1000 μm or less, and most preferably 200 μm or more and 700 μm or less.

  Next, as shown in FIG. 3B, uncured photocurable resin 23 is injected into the first opening 11, the second opening 13, and the third opening 15 of the mold 10. (Step S103). The photocurable resin 23 is injected from the gap between the opening surface of the first opening 11 and the base sheet 26. As the photocurable resin 23, it is preferable to use a colorless or translucent resin in consideration of illuminating from the back side of the key top member. As the photocurable resin 23 used in the manufacturing method according to the present embodiment, an ultraviolet curable (UV curable) resin is preferably used. In particular, it is preferable to employ an acrylate resin as the main component of the photocurable resin 23. Here, as the acrylate resin, for example, urethane acrylate or urethane methacrylate composed of polyester, polyether, polycarbonate (PC), aliphatic, etc., bisphenol A type, bisphenol F type, bisphenol AD Type, water-added bisphenol A type, dimer acid-modified epoxy acrylate resin or epoxy methacrylate resin, polyester acrylate resin, polyester methacrylate resin, silicone acrylate resin, silicone methacrylate resin Etc.

  Moreover, the photocurable resin 23 contains a photopolymerization initiator in addition to the main agent. As the photopolymerization initiator, for example, benzophenone-based, benzoin ether-based, acetophenone-based, and thioxanthone-based photopolymerization initiators can be suitably used. In particular, a photopolymerization initiator having an absorption wavelength region of 365 nm to 400 nm is preferably employed. The addition amount of the photopolymerization initiator is preferably 0.2 or more and 15 or less, and more preferably 0.5 or more and 10 or less when the weight of the acrylate resin is 100. More preferably, the weight is 1 or more and 5 or less. When such an addition amount is employed, it becomes possible to impart deep part curability to the photocurable resin 23, and the photocurable resin 23 can be completely cured. In addition, when the photocurable resin 23 is cured, the photocurable resin 23 can be prevented from shrinking excessively and yellowing can be prevented.

  Further, the viscosity of the photocurable resin 23 used in the manufacturing method according to the present embodiment is preferably 10 mPa · S or more and 300000 mPa · S or less, and 100 mPa · S or more and 100000 mPa · S at a temperature of 23 ° C. More preferably, it is 200 mPa * S or more and 10000 mPa * S or less. In addition, the thixotropic property of the photocurable resin 23 (the property that the apparent viscosity is low when rocking and the viscosity becomes high when stationary) is a value measured by a rotational viscometer method at a temperature of 23 ° C. is 0.5. It is preferably from 3.0 to 3.0, more preferably from 0.7 to 2.5, and most preferably from 0.8 to 2.0.

  Further, in order to improve the mechanical strength, water resistance or adhesion after the photocurable resin 23 is cured, various fillers, silane coupling agents or titanate series are added to the photocurable resin 23 as necessary. A coupling agent or the like may be added. Examples of the filler include various silica fillers such as colloidal silica, finely pulverized silica, crystalline silica, and fused silica, precipitated barium, sericite, mica, aluminum hydroxide, various whiskers, and various glass beads. However, it is not particularly limited to these. Examples of the silane coupling material include amino functional, epoxy functional, vinyl functional, mercapto functional, unsaturated functional, and the like, but are not particularly limited thereto. In addition to the above, an antistatic agent, an antioxidant, a flame retardant, an antiaging agent, a blooming agent for suppressing yellowing, or the like may be added as necessary.

  In order to adjust the viscosity and / or thixotropic property, it is preferable to select a monofunctional monomer, a bifunctional monomer, or a polyfunctional monomer as the main component of the photocurable resin 23. These can be appropriately used depending on the solubility parameter (SP value) of the main agent used or the application.

Next, as shown in FIG. 4 (A), ultraviolet light (UV) is irradiated from the front side of the base sheet 26 (that is, the side opposite to the surface on which the decorative layer 28 is formed), and photocuring in an uncured state. The functional resin 23 is cured (step S104). By continuing this curing process, it is possible to improve the wear resistance, chemical resistance, water resistance and other characteristics of the key top member. The UV irradiance (mW / cm ² ) and the integrated irradiation amount (mJ / cm ² ) applied to the photocurable resin 23 take into consideration the main agent and type of the photocurable resin 23 to be used, the thickness of the key top member, and the like. It is necessary to decide. Instead of the photocurable resin 23, an electron beam curable resin may be employed. In this case, it is necessary to cure the resin by irradiating an electron beam.

  Next, the key top member is removed from the mold 10 (step S105). As a result, as shown in FIG. 4B, the key top in which the convex portions 32, the key tops 30, and the flat connecting portions 31 connected to the bottoms of the key tops 30 are made of the photocurable resin 23. The member 1 is completed.

  In the keytop member manufacturing method configured as described above, since the keytop member 1 itself is formed of the photocurable resin 23, the conventional hard coat layer is not peeled off or cracked. Further, since there is no process of applying a hard coat material, the process can be simplified, and each key top 30, as long as the edges of the openings 11, 13, 15 in the mold 10 are sharpened. The edges of the connecting part 31 and the convex part 32 can be kept sharp. Moreover, since embossing is not employed, a high-strength key top member 1 can be obtained. Further, since the silicone rubber mold 10 is used without using a metal mold, the resin-cured key top member 1 can be easily removed from the mold 10 without using a release agent. Can do. In addition, since the third opening 15 is provided in the mold 10, cracks are generated even if there is an extremely small portion with a height difference such as the convex portion 32 formed on the top surface of the key top. And can be manufactured in a form having sharp edges. Further, the key-top member 1 is manufactured by irradiating the photocurable resin 23 with UV. For this reason, the curing rate is increased, and the manufacturing period can be shortened. Also, normal pressure molding can be realized easily.

  Moreover, in the manufacturing method of the key top member, in the resin injecting step, the photocurable resin 23 having a viscosity at 23 ° C. in the range of 10 mPa · S to 300,000 mPa · S is applied to each opening 11, 13, 15 of the mold 10. Injecting. For this reason, the photocurable resin 23 can be filled to every corner in the mold 10, and it becomes easy to manufacture the key top member 1 having a sharp edge even under normal pressure molding. When the viscosity is 10 mPa · S or more, even the thin key top member 1 can be easily manufactured. On the other hand, when the viscosity is 300000 mPa · S or less, even the key top member 1 having fine irregularities can form a sharp edge.

  Moreover, in the manufacturing method of a key top member, in the resin injection | pouring process, the photocurable resin 23 whose value which shows the thixotropy of 23 degreeC is the range of 0.5-3.0 is used for each opening part 11 of the mold 10. , 13 and 15. For this reason, it becomes easy to manufacture the key top member 1 with uniform strength and sharp edges. When the value indicating thixotropy is 0.5 or more, a plurality of materials (including additives, fillers, etc.) constituting the photocurable resin 23 can be uniformly dispersed. The key top member 1 with a small amount can be easily manufactured. On the other hand, when the value indicating thixotropy is 3.0 or less, since the resin can be injected without entraining bubbles, a key top member having fine irregularities can be easily manufactured.

  Moreover, in the manufacturing method of a key top member, the photoinitiator whose absorption wavelength is 365 nm or more and 400 nm or less is used. When a photopolymerization initiator having an absorption wavelength of 365 nm or more is used, it is possible to impart deep curability to the photocurable resin 23, and the decorative layer 28 blocks the absorption wavelength so that a part of the photocurable resin 23 is formed. An uncured state can be prevented. In addition, when a photopolymerization initiator having an absorption wavelength of 400 nm or less is used, the cured key top member 1 does not turn yellow, and high transparency can be secured.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the above-mentioned form, It can implement in the form variously deformed.

  In the above-described embodiment, the UV curable resin 23 is used as the photocurable resin 23. Instead, an electron beam curable resin, a thermosetting resin, or another resin that can be cured at room temperature is used. May be.

  Further, in the above-described embodiment, the convex portion 32 is formed on the top surface of the key top 30, but the top surface of the key top 30 is made of silicone rubber so as to form a concave portion having a number, character, or symbol shape. In the mold 10, a protrusion may be provided on the bottom surface 14 of the second opening 13. Further, the base sheet 26 may be arranged after the order of Step S102 and Step S103 shown in FIG. 1 is changed and the photocurable resin 23 is injected into the mold 10.

  Examples of the present invention and comparative examples will be described below. Table 1 shows the production conditions and the results obtained for each example and each comparative example.

Example 1
1. Manufacture of sample: Teflon (registered trademark) beaker for 500cc (manufactured by Nichiyasu Co., Ltd.), urethane oligomer (manufactured by Negami Industrial Co., Ltd., product name: Art Resin UN-9000 PEP), urethane oligomer (Nippon Synthesis) Chemical Industry Co., Ltd., product name: purple light UV-1700B) 10 parts by weight, acrylate (Osaka Organic Chemical Co., Ltd., product name: V # 150) 30 parts by weight and acrylate (Osaka Organic Chemical Co., Ltd., product name: HEA) 70 parts by weight were put, and the beaker was heated to 60 ° C. on a digital hot stirrer (manufactured by As One, product name: DP-1M) while being coated with fluorine-coated stainless ointment spatula (manufactured by As One, product name: These were uniformly dissolved using FP-12) while stirring for 30 minutes. Then, the beaker was removed from the digital hot stirrer and allowed to cool to room temperature. Next, 1 part by weight of an amino-based silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBM603) and 3 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, Inc., product name: Irgacure 1700) In addition to each of the above beakers, a stainless ointment spatula was used and mixed uniformly while stirring in a greenhouse to obtain a blend in which the above materials were mixed. Next, the mixture is transferred to a 500 ml brown bottle (manufactured by As One, product name: Goodboy brown bottle), covered, and left overnight in a room at a temperature of 23 ° C. and humidity of 50% RH. As a result, Sample-1 was obtained. In addition, the viscosity and IT value (viscosity ratio at a rotation speed of 1 rpm and 10 rpm) of Sample-1 were measured using a rotary viscometer (manufactured by Tokimec Co., Ltd., product name: B-type rotary viscometer). The temperature for measuring the viscosity and the rotational speed of the rotary viscometer were 23 ° C. and 20 rpm, respectively.

2. Next, as a base material sheet, a PC resin sheet (manufactured by Teijin Chemicals Ltd., product name: Panlite film PC-3555, size: A4, thickness: 0.25 mm) was prepared. Next, in order to form a decoration layer, the base material sheet was set in a sublimation thermal transfer printer (manufactured by Victor Co., Ltd., product name: Color printer Trueprint 3500). A receiving layer (manufactured by Victor Co., Ltd., product name: JP-D304F) made of vinyl chloride resin for receiving the dye was set in the same printer, and the receiving layer was printed on a base sheet. Next, a pattern was printed on the base material sheet using a sublimation type color ink ribbon (manufactured by Victor Co., Ltd., product name: JP-D304I). Finally, a protective layer was printed on the base sheet using an overcoat ink ribbon (manufactured by Victor Co., Ltd., product name: JP-T340I). In addition, when the total light transmittance of the decoration layer was measured using a haze meter (Nippon Denshoku Industries Co., Ltd., model: NDH2000 type) under the condition of room temperature 23 ° C. according to JIS K7361, the decoration layer The total light transmittance of was 40%. Next, the base material sheet thus obtained was cut into a size of 150 mm × 100 mm using an NT cutter to obtain a base material sheet with decoration. Next, 100 parts by weight of silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KE1600) and 10 parts by weight of silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., product name: Cat-1600) are made of Teflon (registered trademark). Place in a 500 ml beaker, mix evenly with stirring using a stainless ointment spatula, pour the mixture into a stainless steel mold (size: 152 mm x 102 mm x 20 mm) and leave it overnight at room temperature of 23 ° C. Cured. Next, Arabic numerals 0-9 and Arabic letter # were carved on the surface of the cured silicone rubber to obtain a mold made of silicone rubber. The dimensions of Arabic numerals and letters carved on the formwork are as follows. Arabic numeral 0 (character width: 0.5 mm, character height: 0.5 mm), Arabic numeral 1 (character width: 0.5 mm, character height: 0.5 mm), Arabic numeral 2 (character width: 0.5 mm, character height: 1.0 mm), Arabic numeral 3 (character width: 0.5 mm, character height: 1.0 mm), Arabic numeral 4 (character width: 0.2 mm, character height: 1.5 mm), Arabic numeral 5 (character width: 0.2 mm, character height: 1.5 mm), Arabic numeral 6 (character width: 1.0 mm, character height: 1.0 mm), Arabic numeral 7 (character width: 1.0 mm, character height: 1.0 mm), Arabic numeral 8 (character width: 0.2 mm, character height: 0.5 mm), Arabic numeral 9 (character width: 0.2 mm) , Character height: 0.5 mm), Arabic character # (character width: 0.2 mm, character height) 0.5mm). Next, Sample-1 was cast into this mold at a temperature of 23 ° C. Furthermore, the decorated base sheet was placed in the mold so that its printed surface was in contact with Sample-1. In this state, a weight of 2 kg was placed on the decorated base sheet for 30 seconds, and then the weight was removed. Next, the mold frame on which the decorated base sheet was placed was placed in a UV irradiation apparatus so that UV was applied from the printing surface side of the decorated base sheet. Next, UV was irradiated so that the height from the converter of the UV lamp was 14 cm, the irradiance was 150 mW / cm ² , and the cumulative irradiation amount was 2500 mJ / cm ² . In addition, a metal hydride lamp (Iwasaki Electric Co., Ltd., product name: M04-L41) is used as a UV lamp when irradiating UV, and a conveyor type UV irradiation apparatus (Iwasaki Electric Co., Ltd., Product name: Eye Mini Grantage (4 kW) ECS-401GX) was used. After completion of UV irradiation, the mold was removed from the UV irradiation apparatus, and the mold was cooled to 23 ° C. Then, the base material sheet with a decoration was removed from the formwork, and the test piece-1 was obtained.

3. Evaluation Method and Acceptance Criteria (1) Viscosity: Sample-1 has a viscosity of 10 to 300,000 mPa · S using a rotary viscometer (product name: B-type rotary viscometer manufactured by Tokimec Co., Ltd.) If it was confirmed, it was considered acceptable. The measurement conditions were a temperature of 23 ° C. and a rotation speed of 20 rpm.

(2) Viscosity: When it can be confirmed that the viscosity of Sample-1 is in the range of 10-350,000 mPa · S using a rotary viscometer (manufactured by Tokimec Co., Ltd., product name: B-type rotary viscometer). And passed. The measurement conditions were a temperature of 60 ° C. and a rotation speed of 20 rpm.

(3) TI value: Using a rotary viscometer (manufactured by Tokimec Co., Ltd., product name: B-type rotary viscometer), the viscosity ratio of sample-1 when the rotational speed is 1 rpm and 10 rpm (1 / 10 rpm) was determined to be acceptable when it was confirmed that it was in the range of 0.5 to 0.3. The measurement temperature was 23 ° C. or 60 ° C.

(4) Possibility of casting: When sample-1 is placed on the mold surface, and it can be visually confirmed that sample-1 enters the concave portion of the Arabic numerals and characters carved on the mold surface, Passed.

(5) Irregularities of Arabic numerals and letters: Using a binocular stereomicroscope (manufactured by Carlton Co., Ltd., product name: DST 44FT type), fine irregularities of Arabic numerals and letters are uniformly formed on specimen-1. When it was confirmed that it was The measurement conditions were a temperature of 23 ° C. and a binocular stereomicroscope with a magnification of 20 times.

(6) Arabic numerals and letters edges: The corners of Arabic numerals and letters are sharply formed on the test piece 1 using a binocular stereomicroscope (product name: DST 44FT type, manufactured by Carlton Co., Ltd.). When we were able to confirm that, we passed. The measurement conditions were a temperature of 23 ° C. and a binocular stereomicroscope with a magnification of 20 times.

  In this example, for the evaluation of viscosity, the evaluation method (2) was not adopted, and only the evaluation method (1) was adopted. Moreover, about the evaluation method of (3), the pass determination was performed only in the case of 23 degreeC.

4). Result (1) Viscosity: 50 mPa · S (23 ° C.). : ○ (pass), (3) TI value: 1.1 (23 ° C.). : ○ (Accepted), (4) Castability: Sample-1 smoothly entered the recesses engraved with Arabic numerals and letters. : ○ (Accepted), (5) Irregularities of Arabic numerals and letters: Fine irregularities of Arabic numerals and letters were uniformly formed. : (Circle) (pass), (6) Edges of Arabic numerals and letters: The edges of the corners of Arabic numerals and letters were sharp. : ○ (pass)

(Example 2)
1. Sample Preparation The formulation of Example 1 was transferred again to the beaker used in Example 1, and 100 parts by weight of spherical silica (product name: FB-40S, manufactured by Denki Kagaku Kogyo Co., Ltd.) was added as a filler. Using a Lee mixer (manufactured by Inoue Seisakusho Co., Ltd., model: PLM-5), the mixture was stirred at a rotation speed of 1000 rpm for 30 minutes to obtain a blend in which each material was uniformly mixed. After putting this blend into the brown bottle used in Example 1, Sample-2 was prepared in the same manner as in Example 1.

2. Manufacture of test piece Test piece-2 was produced in the same manner as in Example 1 using Sample-2.

3. Evaluation Method and Acceptance Criteria The same evaluation method and acceptance criteria as in Example 1 were adopted. In this example, for the evaluation of viscosity, the evaluation method (2) was not adopted, and only the evaluation method (1) was adopted. Moreover, about the evaluation method of (3), the pass determination was performed only in the case of 23 degreeC.

4). Result (1) Viscosity: 30000 mPa · S (23 ° C.). : ○ (pass), (3) TI value: 0.8 (23 ° C.). : ○ (Accepted), (4) Castability: Sample-2 smoothly entered the recesses engraved with Arabic numerals and letters. : ○ (Accepted), (5) Irregularities of Arabic numerals and letters: Fine irregularities of Arabic numerals and letters were uniformly formed. : (Circle) (pass), (6) Edges of Arabic numerals and letters: The edges of the corners of Arabic numerals and letters were sharp. : ○ (pass)

(Example 3)
1. Sample Production Sample A-3 was produced in the same manner as in Example 2 except that the amount of spherical silica added in Example 2 was 120 parts by weight.

2. Manufacture of Test Specimen Test Specimen-3 was produced in the same manner as in Example 1 using Sample-3.

3. Evaluation Method and Acceptance Criteria The same evaluation method and acceptance criteria as in Example 1 were adopted. In this example, for the evaluation of viscosity, the evaluation method (2) was not adopted, and only the evaluation method (1) was adopted. Moreover, about the evaluation method of (3), the pass determination was performed only in the case of 23 degreeC.

4). Result (1) Viscosity: 15000 mPa · S (23 ° C.). : ○ (pass), (3) TI value: 0.6 (23 ° C.). : ○ (Accepted), (4) Castability: Sample-3 smoothly entered the recesses engraved with Arabic numerals and letters. : ○ (Accepted), (5) Irregularities of Arabic numerals and letters: Fine irregularities of Arabic numerals and letters were uniformly formed. : (Circle) (pass), (6) Edges of Arabic numerals and letters: The edges of the corners of Arabic numerals and letters were sharp. : ○ (pass)

Example 4
1. Production of Sample In the beaker used in Example 1, 60 parts by weight of urethane oligomer (manufactured by Negami Industrial Co., Ltd., product name: Art Resin UN-9000H), urethane oligomer (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name: 30 parts by weight of purple light UV-3200B) and 10 parts by weight of epoxy-based ogomer (manufactured by Kyoeisha Chemical Co., Ltd., epoxy ester 3002A) are stirred and heated to 60 ° C. as in Example 1 and dissolved uniformly. It was. Next, 10 parts by weight of acrylate (product name: V # 150, manufactured by Osaka Organic Chemical Co., Ltd.) and 70 parts by weight of acrylate (product name: HEA, manufactured by Osaka Organic Chemical Co., Ltd.) used in Example 1 were mixed. A formulation was obtained. Then, sample-4 was produced by the same method as Example 1 using the compound.

2. Manufacture of Test Specimen Test Specimen-4 was produced using Sample-4 in the same manner as in Example 1.

3. Evaluation Method and Acceptance Criteria The same evaluation method and acceptance criteria as in Example 1 were adopted. In this example, for the evaluation of viscosity, the evaluation method (2) was not adopted, and only the evaluation method (1) was adopted. Moreover, about the evaluation method of (3), the pass determination was performed only in the case of 23 degreeC.

4). Result (1) Viscosity: 20000 mPa · S (23 ° C.). : ○ (pass), (3) TI value: 1.2 (23 ° C.). : ○ (Accepted), (4) Castability: Sample-4 smoothly entered the recesses engraved with Arabic numerals and letters. : ○ (Accepted), (5) Irregularities of Arabic numerals and letters: Fine irregularities of Arabic numerals and letters were uniformly formed. : (Circle) (pass), (6) Edges of Arabic numerals and letters: The edges of the corners of Arabic numerals and letters were sharp. : ○ (pass)

(Example 5)
1. Sample Production To the formulation of Example 4, 300 parts by weight of precipitated barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd., product name: # 100) was added as a filler, and a plaretary mixer was used as in Example 2. And stirred for 30 minutes at a rotation speed of 1000 rpm. Thereafter, Sample-5 was produced in the same manner as in Example 1. Moreover, the viscosity and IT value of Sample-5 were measured using a rotary viscometer (manufactured by Tokimec Co., Ltd., product name: B-type rotary viscometer). Viscosity and IT value were measured in a state where Sample-5 was placed in a 500 cc brown bottle and heated to 60 ° C. for 1 hour using a hot air oven (manufactured by Yamato Co., Ltd., model: DK600 type). I went there. The temperature was measured by measuring the surface temperature of Sample-5 using a radiation thermometer (Horiba, Ltd., product name: IT-550). The rotational speed of the rotary viscometer when measuring the viscosity was 20 rpm.

2. Next, as a base sheet, a PMMA resin sheet (manufactured by Sumitomo Chemical Co., Ltd., product name: Technoloy S001, size: A4, thickness: 0.4 mm) was prepared. Thereafter, a decorative layer was formed on the base sheet by the same method as in Example 1, and a mold similar to that in Example 1 was prepared. Next, the mold was heated to 60 ° C. using the digital hot stirrer used in Example 1, and Sample-5 was cast in the same manner as in Example 1. Then, UV irradiation was performed on the conditions similar to Example 1, and the test piece-5 was produced. In addition, the radiation thermometer used at the time of the measurement of a viscosity and IT value was employ | adopted for the temperature measurement of a mold.

3. Evaluation Method and Acceptance Criteria The same evaluation method and acceptance criteria as in Example 1 were adopted. In this example, both the evaluation methods (1) and (2) were adopted for the evaluation of the viscosity. Moreover, in the evaluation method of (3), the pass determination was performed about the case of both 23 degreeC and 60 degreeC.

4). Results (1) Viscosity: 2980000 mPa · S (23 ° C.). : ○ (pass), (2) Viscosity: 30000 mPa · S (60 ° C.). : ○ (pass), (3) TI values: 2.9 (23 ° C.) and 2.7 (60 ° C.). : (Circle) (pass), (4) Possibilities of casting: Sample-5 smoothly entered the recesses engraved with Arabic numerals and letters. : ○ (Accepted), (5) Irregularities of Arabic numerals and letters: Fine irregularities of Arabic numerals and letters were uniformly formed. : ○ (pass), (6) Arabic numeral and letter edge: The edge of the corner of Arabic numeral and letter was sharp. : ○ (pass)

Next, a comparative example of the present invention will be described.
(Comparative Example 1)
1. Production of sample As epoxy resin, 100 parts by weight of bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., product name: iER828), as reactive diluent for epoxy resin, alkyl monoglycidyl ether (manufactured by Japan Epoxy Resin Co., Ltd., Product name: YDE111N) 20 parts by weight, 100 parts by weight of spherical silica used in Example 2 as a filler and 1 part by weight of an amino-based silane coupling agent used in Example 1 as a silane coupling agent were added. Using the planetary mixer used in No. 2, the mixture was stirred under the same conditions as in Example 2 to obtain a blend. This blend was placed in the brown bottle used in Example 1 and allowed to stand overnight under the same conditions as in Example 1. At this time, as a curing agent for the epoxy resin, a polyamine curing agent (manufactured by Japan Epoxy Resin Co., Ltd., product name: LV11) was placed in the same room with a 1 kg square can purchased. On the next day, 55 parts by weight of the epoxy resin curing agent was added to the brown bottle, and stirred uniformly with a metal ointment spatula to obtain Sample-6. The mixing ratio of the epoxy equivalent of the epoxy resin and the amine equivalent of the curing agent for epoxy resin of the curing agent for epoxy resin was set to 1: 1.

2. Manufacture of a test piece Similarly to the case of Example 1, sample-6 was cast in a mold, and the base material sheet with a decoration was arrange | positioned in the mold. In this state, a weight of 2 kg was placed on the decorated base material sheet, placed at a temperature of 23 ° C. for 3 days, and then removed. Thereafter, the decorated base sheet was removed from the mold to obtain a test piece-6.

3. Evaluation Method and Acceptance Criteria The same evaluation method and acceptance criteria as in Example 1 were adopted. In this comparative example, for the evaluation of the viscosity, the evaluation method (2) was not adopted, and only the evaluation method (1) was adopted. Moreover, about the evaluation method of (3), the pass determination was performed only in the case of 23 degreeC.

4). Result (1) Viscosity: 100 mPa · S (23 ° C.). : ○ (pass), (3) TI value: 0.3 (23 ° C.). : X (failed), (4) castability: In sample-6, spherical silica as a filler separated from the resin and settled. Therefore, when Sample-6 was cast, only the resin was cast in most of the concave portions of Arabic numerals and letters. : X (failed), (5) Irregularities of Arabic numerals and letters: Fine irregularities of Arabic numerals and letters were not uniformly formed. : X (failed), (6) Arabic numeral and letter edge: Arabic numeral and letter corner edges did not become sharp. : X (failed)

(Comparative Example 2)
1. Sample Production To 100 parts by weight of the epoxy resin used in Comparative Example 1, 700 parts by weight of precipitated barium sulfate used in Example 5 and 33 parts by weight of the polyamine type curing agent used in Comparative Example 1 were added, respectively. Sample-7 was produced in the same manner as in Example 5.

2. Manufacture of Test Specimen Test -7 was prepared in the same manner as in Comparative Example 1 using Sample-7. In addition, the same PMMA resin sheet as Example 5 was employ | adopted as a base material sheet.

3. Evaluation Method and Acceptance Criteria The same evaluation method and acceptance criteria as in Example 1 were adopted. In this comparative example, for the evaluation of the viscosity, the evaluation method (2) was not adopted, and only the evaluation method (1) was adopted. Moreover, about the evaluation method of (3), the pass determination was performed only in the case of 23 degreeC.

4). Results (1) Viscosity: 500,000 mPa · S (23 ° C.). : X (failed), (3) TI value: 3.5 (23 ° C.). : X (failed), (4) castability: Sample-7 could not be cast because the TI value was high. : X (failed), (5) Irregularities of Arabic numerals and letters: Fine irregularities of Arabic numerals and letters were not uniformly formed. : X (failed), (6) Arabic numeral and letter edge: Arabic numeral and letter corner edges did not become sharp. : X (failed)

(Comparative Example 3)
1. Sample Preparation Sample-8 was prepared in the same manner as in Example 5 using the formulation of Comparative Example 2.

2. Manufacture of Test Specimen Sample -8 was prepared in the same manner as in Comparative Example 1 using Sample-8. The temperature of the mold when casting Sample-8 was set to 60 ° C.

3. Evaluation Method and Acceptance Criteria The same evaluation method and acceptance criteria as in Example 1 were adopted. In this comparative example, for the evaluation of the viscosity, the evaluation method (1) was not adopted, and only the evaluation method (2) was adopted. Moreover, about the evaluation method of (3), the pass determination was performed only in the case of 60 degreeC.

4). Result (1) Viscosity: 50000 mPa · S (60 ° C.). : X (failed), (3) TI value: 3.3 (60 ° C.). : X (failed), (4) castability: Sample-8 could not be cast because the TI value was high. : X (failed), (5) Irregularities of Arabic numerals and letters: Fine irregularities of Arabic numerals and letters were not uniformly formed. : X (failed), (6) Arabic numeral and letter edge: Arabic numeral and letter corner edges did not become sharp. : X (failed)

  The method for manufacturing a keytop member of the present invention can be used in industries that manufacture or use electronic devices such as mobile phones, remote controllers, electronic calculators, and smart keys.

It is a flowchart which shows each process of the manufacturing method of the key top member which concerns on one embodiment of this invention. It is a perspective view of the formwork used for the manufacturing method of the key top member concerning one embodiment of the present invention, and is a figure showing the state where the formwork was seen from the opening side. It is a figure for demonstrating the manufacturing method of the key top member which concerns on one embodiment of this invention, (A) is a figure for demonstrating an arrangement | positioning process, (B) demonstrates the resin injection | pouring process. It is a figure for doing. FIG. 4 is a diagram for explaining a method for manufacturing a key top member according to an embodiment of the present invention, following FIG. 3, (A) is a diagram for explaining a curing process, and (B) is a diagram. It is sectional drawing of the keytop member obtained after the mold release process of the manufacturing method of the keytop member which concerns on one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Key top member 10 ... Formwork 11 ... 1st opening part 13 ... 2nd opening recessed part 15 ... 3rd opening part 23 ... Photocurable resin (resin)
26 ... Base sheet 30 ... Key top 31 ... Connection part 32 ... Convex part

Claims (5)

A method of manufacturing a key top member comprising one or more key tops and a connecting portion connected to the bottom of the key top,
Made of silicone rubber having a first opening for forming the connecting portion and a second opening for forming the key top in the first opening and further recessed. An arrangement step of arranging a base sheet on the first opening of the mold,
A resin injection step of injecting a resin containing at least an acrylate resin into each opening of the mold,
A curing step for curing the resin;
A method for manufacturing a key top member, comprising:   The mold is an opening for forming a convex portion on the top surface of the key top, and the third opening that is further recessed in the second opening, or the top surface of the key top 2. The method for manufacturing a key top member according to claim 1, wherein the second opening has a protruding portion that protrudes from a bottom surface thereof. The base sheet is a transparent resin sheet,
The resin includes at least an acrylate resin and a photopolymerization initiator,
The method of manufacturing a key top member according to claim 1, wherein the curing step is a step of irradiating the resin with light through the base sheet to cure the resin.   4. The key top member according to claim 3, wherein in the resin injecting step, the resin having a viscosity of 23 ° C. in a range of 10 mPa · S to 300,000 mPa · S is injected into each opening of the mold. Manufacturing method.   The said resin injection | pouring process WHEREIN: The said resin whose value which shows the thixotropy of 23 degreeC is the range of 0.5-3.0 is injected into each opening part of the said mold. A method for producing the key top member according to claim 1.

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