JP2009110842A - Laminated resin body for button switch coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating member for a button switch which is hard to have scratches and is hardly broken. <P>SOLUTION: The laminated resin body in which acrylic resin layer is laminated on at least one of the surfaces of polycarbonate resin layer and the thickness of the polycarbonate resin layer is 50% or more of the total thickness is used as a coating member of a button switch. It is preferable that the polycarbonate resin layer and acrylic resin layer are laminated by coextrusion forming, and the acrylic resin layer is a layer consisting of a methacrylic resin and a rubber-like copolymer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laminated resin body for covering a button switch.

  Button switches such as push button switches and touch sensor button switches used in mobile phones, digital cameras, electronic notebooks, remote controls, personal computer keyboards, industrial and medical precision machines, etc. As a result of the progress of development, it is shifting to small and thin. When the button switch is small, it becomes difficult to adjust the gap between the movable parts, and the button itself is apt to be distorted by continuous use or to enter the inside of the device. Also, recently, in order to make it waterproof, the gap between the button and the main unit is made as small as possible, and processing such as rubber tension inside the device main unit has been devised, but the button does not work early, Due to design reasons, problems such as the main body becoming larger are more likely to occur.

  In order to solve these problems, it has been studied to cover a button switch. For example, Japanese Patent Laying-Open No. 2005-310540 (Patent Document 1) discloses using an acrylic resin film as a covering member for a button switch. Has been.

JP 2005-310540 A

  As disclosed in Patent Document 1, if an acrylic resin film is used as the covering member of the button switch, it is advantageous in that it is difficult to be damaged, but it is easy to break when the device falls or hits it. There is. Accordingly, an object of the present invention is to provide a covering member for a button switch which is not easily damaged and is not easily broken.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by employing a specific laminated resin body as a covering member for a button switch, and have completed the present invention. That is, the present invention relates to a laminated resin for button switch coating, characterized in that an acrylic resin layer is laminated on at least one surface of a polycarbonate resin layer, and the thickness of the polycarbonate resin layer is 50% or more of the total thickness. Provide the body.

  Since the laminated resin body for covering a button switch of the present invention is hardly scratched and hardly cracked, the button switch can be effectively covered.

  The laminated resin body of the present invention comprises an acrylic resin layer laminated on at least one surface of a polycarbonate resin layer, and is used for covering a button switch.

  Examples of the polycarbonate resin constituting the polycarbonate layer include those obtained by reacting a dihydric phenol and a carbonylating agent by an interfacial polycondensation method, a melt transesterification method, or the like, or a carbonate prepolymer by a solid phase transesterification method. And those obtained by polymerizing a cyclic carbonate compound by a ring-opening polymerization method.

  Examples of the dihydric phenol include hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, bis {(4-hydroxy-3,5-dimethyl) phenyl} methane, 1,1- Bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A), 2,2-bis { (4-hydroxy-3-methyl) phenyl} propane, 2,2-bis {(4-hydroxy-3,5-dimethyl) phenyl} propane, 2,2-bis {(4-hydroxy-3,5-dibromo) ) Phenyl} propane, 2,2-bis {(3-isopropyl-4-hydroxy) phenyl} propane, 2,2-bis {(4 Hydroxy-3-phenyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -3-methylbutane, 2,2-bis (4-hydroxyphenyl) -3,3-dimethylbutane, 2,4-bis (4-hydroxyphenyl) -2-methylbutane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) -4 -Methylpentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3 5-trimethylcyclohexane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis {(4-hydroxy 3-methyl) phenyl} fluorene, α, α′-bis (4-hydroxyphenyl) -o-diisopropylbenzene, α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene, α, α′-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 1,3-bis (4-hydroxyphenyl) -5,7-dimethyladamantane, 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenylsulfoxide, 4 , 4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl ester, etc., and if necessary, use two or more of them You can also.

  Among them, bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl)- 3-methylbutane, 2,2-bis (4-hydroxyphenyl) -3,3-dimethylbutane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxyphenyl) ) -3,3,5-trimethylcyclohexane and α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene are preferably used alone or in combination of two or more. In particular, bisphenol A Of 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and bisphenol A, Use in combination with one or more dihydric phenols selected from 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane and α, α'-bis (4-hydroxyphenyl) -m-diisopropylbenzene preferable.

  Examples of the carbonylating agent include carbonyl halides such as phosgene, carbonate esters such as diphenyl carbonate, haloformates such as dihaloformates of dihydric phenols, and two or more of them can be used as necessary.

  As the acrylic resin constituting the acrylic resin layer, methacrylic resin is generally used. The methacrylic resin is preferably a methyl methacrylate resin containing a methyl methacrylate unit as a main component, specifically a methyl methacrylate resin containing usually 50% by weight or more, preferably 70% by weight or more of a methyl methacrylate unit. A homopolymer of methyl methacrylate having a unit of 100% by weight may be used, or a copolymer of methyl methacrylate and another monomer may be used.

  Examples of other monomers copolymerizable with methyl methacrylate include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate. Methacrylic acid esters other than methyl methacrylate, such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate Such acrylic acid esters can be mentioned. Further, styrene and substituted styrenes, for example, halogenated styrenes such as chlorostyrene and bromostyrene, alkyl styrenes such as vinyltoluene and α-methylstyrene, and the like are also included. Furthermore, unsaturated acids such as methacrylic acid and acrylic acid, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide and the like can also be mentioned. These other monomers copolymerizable with methyl methacrylate may be used alone or in combination of two or more.

  The acrylic resin may be used by blending a rubbery polymer. Examples of rubbery polymers include acrylic multilayered polymers and 5 to 80 parts by weight of rubbery polymer with 20 to 95 parts by weight of ethylenically unsaturated monomers such as acrylic unsaturated monomers. Examples include graft copolymers obtained by graft polymerization. The acrylic multi-layered structure polymer should have a rubber elastic layer or an elastomer layer contained in an amount of about 20 to 60% by weight, and should have a hard layer at the outermost layer, and further the innermost layer. A structure including a hard layer may be used.

  The rubber-elastic layer or the elastomer layer is preferably an acrylic polymer layer having a glass transition point (Tg) of less than 25 ° C., and specifically includes lower alkyl acrylate, lower alkyl methacrylate, and lower alkoxyalkyl acrylate. A polymer obtained by crosslinking one or more monofunctional monomers selected from cyanoethyl acrylate, acrylamide, hydroxy lower alkyl acrylate, hydroxy lower alkyl methacrylate, acrylic acid and methacrylic acid with a polyfunctional monomer such as allyl methacrylate. It should be a coalesced layer.

  The hard layer may be an acrylic polymer layer having a Tg of 25 ° C. or more, and specifically, an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms is polymerized alone or as a main component. It should be a thing. When the copolymer is mainly composed of alkyl methacrylate, the copolymer component may be a monofunctional monomer such as other alkyl methacrylate, alkyl acrylate, styrene, substituted styrene, acrylonitrile, or methacrylonitrile. Further, a polyfunctional monomer may be added to form a crosslinked polymer.

  Acrylic multilayer structure polymers are described, for example, in JP-B-55-27576, JP-A-6-80739, JP-A-49-232922, and the like.

  In a graft copolymer obtained by graft polymerization of 20 to 95 parts by weight of an ethylenically unsaturated monomer to 5 to 80 parts by weight of a rubbery polymer, examples of the rubbery polymer include polybutadiene rubber and acrylonitrile / butadiene. Diene rubber such as copolymer rubber, styrene / butadiene copolymer rubber, acrylic rubber such as polybutyl acrylate, polypropyl acrylate, poly-2-ethylhexyl acrylate, ethylene / propylene / non-conjugated diene rubber, etc. It is done. Examples of the ethylenic monomer used for graft copolymerization with the rubbery polymer include styrene, acrylonitrile, and alkyl (meth) acrylate. These graft copolymers are described, for example, in JP-A Nos. 55-147514 and 47-9740.

  When the rubber-like polymer is dispersed in the acrylic resin, the dispersion ratio is usually 3 to 150 parts by weight, preferably 5 to 50 parts by weight with respect to 100 parts by weight of the acrylic resin. If the amount of the rubbery polymer is too large, the surface hardness is lowered, which is not preferable.

  In addition, for each of the polycarbonate resin layer and the acrylic resin layer, for example, a light diffusing agent, a matting agent, a dye, a light stabilizer, an ultraviolet absorber, an antioxidant, a release agent, a flame retardant, a charge One or more additives such as an inhibitor may be added.

  The laminated resin body of the present invention is preferably produced by laminating and integrating a polycarbonate resin layer and an acrylic resin layer by coextrusion molding. In this co-extrusion molding, a polycarbonate resin layer material and an acrylic resin layer material are melted and kneaded using two or three uniaxial or biaxial extruders, respectively, and then a feed block die, a multi-manifold die, etc. The molten laminated resin body that is laminated and integrated may be cooled and solidified using, for example, a roll unit to form a laminated resin body. A laminated resin body produced by coextrusion molding is preferable in that it can be easily formed into a button shape or the like as compared with a laminated resin body produced by bonding using an adhesive or an adhesive.

  The laminated resin body of the present invention may have a two-layer structure in which an acrylic resin layer is laminated on only one side of a polycarbonate resin layer, or an acrylic resin layer is laminated on both sides of a polycarbonate resin layer. It may have a layered structure, but a three-layered structure has a two-layered structure because the surface impact may be reduced and cracking may occur depending on the thickness of the acrylic resin layer and the type of acrylic resin. Those are preferred.

  The laminated resin body of the present invention is usually in the form of a sheet or film, and the thickness is usually 0.2 to 2 mm, preferably 0.3 to 1 mm, more preferably 0.3 to 0.7 mm. In the laminated resin body of the present invention, the thickness of the polycarbonate resin layer is 50% or more, preferably 70% or more, more preferably 80% or more of the total thickness. Thus, by making the thickness of the polycarbonate resin layer a predetermined ratio or more, the laminated resin body becomes more difficult to break. In addition, the thickness of a polycarbonate resin layer is 95% or less normally with respect to the whole thickness, More preferably, it is 90% or less.

  When importance is attached to the surface hardness of the acrylic resin layer, the thickness is preferably 10 μm or more. In the case of a three-layer structure, the thicknesses of both acrylic layers may be the same or different.

  The laminated resin body of the present invention thus obtained is used, for example, as a covering member for a pushbutton switch such as a mobile phone or a portable music player. It is also used as a covering member for touch sensor button switches. Furthermore, it can also be used as a protective covering member for liquid crystal and organic EL panels that also function as these button switch covers.

  In order to use the laminated resin body of the present invention as a covering member for a button switch, for example, if necessary, secondary molding such as thermoforming, printing, drilling, and the like are performed, and cutting into a predetermined shape or size is performed. do it. And if it is a laminated resin body of a two-layer structure, the button switch is usually covered so that the acrylic resin layer is on the front side (outside: the side touched by a person). Further, when the laminated resin body has a three-layer structure and the thicknesses of both acrylic resin layers are different from each other, the button switch is preferably covered so that the acrylic resin layer having the larger thickness is on the front side. Thus, by covering the button switch with the laminated resin body of the present invention, it is possible to form a coating layer on the surface of the button switch which is hard to be scratched and cracked. It also has a waterproof and dustproof effect.

  Examples of the present invention will be described below, but the present invention is not limited thereto. The configuration of the extrusion apparatus and the evaluation method in each example are as follows.

[Configuration of extrusion equipment]
Extruder (1): Screw diameter 65 mm, uniaxial, with vent (manufactured by Toshiba Machine Co., Ltd.).
Extruder (2): Screw diameter 45 mm, uniaxial, with vent (manufactured by Hitachi Zosen).
Feed block: 2 types 3 layers and 2 types 2 layers distribution (manufactured by Hitachi Zosen Corporation).
Die: T-die, lip width 1400 mm, lip interval 1 mm (manufactured by Hitachi Zosen Corporation).
Roll: 3 polishing rolls, horizontal type.

〔Evaluation methods〕
A thermoforming machine manufactured by Fuse Vacuum Co., Ltd. (model: CUPF-1015-PWB) is provided with an opening of 180 x 250 mm and a resin plate cut to 220 x 310 mm (dried at 100 ° C for 20 hours) is clamped Then, push-up molding was performed at a molding temperature of 180 ° C. using a push-molding wooden mold of 100 × 50 mm and a height of 100 mm. At that time, in the case of a two-layer plate, the acrylic resin layer was molded so that it was on the outer side of the top (surface not in contact with the raised wooden mold). The pencil hardness of the top of the obtained push-up molded product was measured with a 1 kg load according to JIS K5400. The top of the resulting molded product is placed on the floor, and a ball drop test is performed by dropping an iron ball of 500 g from a height of 1 m. did.

Reference Example 1 (Production of rubber-like polymer)
In accordance with the method described in JP-B-55-27576, a three-layer acrylic multilayer elastic body was produced. That is, 1700 g of ion-exchanged water, 0.7 g of sodium carbonate and 0.3 g of sodium persulfate were charged into a glass reaction container having an internal volume of 5 L, stirred under a nitrogen stream, and then sodium dioctylsulfosuccinate (manufactured by Kao Corporation). 4.46 g of PELEX OT-P (anionic surfactant), 150 g of ion-exchanged water, 150 g of methyl methacrylate and 0.3 g of allyl methacrylate were added, the temperature was raised to 75 ° C., and stirring was continued for 150 minutes. Next, a mixture of 689 g of butyl acrylate, 162 g of styrene and 17 g of allyl methacrylate, and a mixture of 0.85 g of sodium persulfate, 7.4 g of sodium dioctyl sulfosuccinate (same as above) and 50 g of ion-exchanged water were added over 90 minutes from separate inlets. The polymerization was continued for an additional 90 minutes. Thereafter, a further mixture of 326 g of methyl acrylate and 14 g of ethyl acrylate and 30 g of ion-exchanged water in which 0.34 g of sodium persulfate was dissolved were added from separate inlets over 30 minutes. After completion of the addition, the polymerization was completed by holding for another 60 minutes. The obtained latex was put into a 0.5 wt% aluminum chloride aqueous solution to aggregate the polymer. This was washed 5 times with warm water and then dried to obtain an acrylic multilayer elastic body.

Examples 1-4
Polycarbonate resin [Caliber 301-10 manufactured by Sumitomo Dow Co., Ltd.] was used in the extruder (1), and acrylic resin [methyl methacrylate / methyl acrylate = 98/2 (weight ratio) copolymer] was used as the extruder ( In 2), each is melt-kneaded while heating, laminated and integrated with a feed block, extruded from a T-die in a molten state, cooled with a polishing roll, and a two-layer resin plate having the structure shown in Table 1 is obtained. It was. The evaluation results of the obtained plate are shown in Table 1.

Examples 5-6
Polycarbonate resin [Caliber 301-10 manufactured by Sumitomo Dow Co., Ltd.] was extruded with an extruder (1), and an acrylic resin [methyl methacrylate / methyl acrylate = 96/4 (weight ratio) copolymer (refractive index 1. 49) Melt and knead each of 70 parts by weight of a methacrylic resin composition obtained by blending 30 parts by weight of the acrylic multilayer elastic body obtained in Reference Example 1 with an extruder (2) while heating, respectively. Were laminated and integrated, extruded from a T-die in a molten state, cooled with a polishing roll, and a three-layer resin plate having the structure shown in Table 1 was obtained. The evaluation results of the obtained plate are shown in Table 1.

Comparative Example 1
In Example 2, the acrylic resin and polycarbonate resin of each extruder raw material were replaced, and the 2 layer resin board of the structure shown in Table 1 was obtained. The evaluation results of the obtained plate are shown in Table 1.

Comparative Example 2
In Example 6, the acrylic resin and polycarbonate resin of each extruder raw material were replaced, and the 3 layer resin board of the structure shown in Table 1 was obtained. The evaluation results of the obtained plate are shown in Table 1.

Comparative Example 3
In Example 3, the extruder (1) was stopped to obtain a single-layer plate having only an acrylic resin layer. The evaluation results of the obtained plate are shown in Table 1.

Comparative Example 4
In Example 3, the extruder (2) was stopped to obtain a single-layer plate having only a polycarbonate resin layer. The evaluation results of the obtained plate are shown in Table 1.

  In Table 1, PC represents a polycarbonate resin layer, and PMMA represents an acrylic resin layer.

Claims (3)

  A laminated resin body for covering button switches, wherein an acrylic resin layer is laminated on at least one surface of a polycarbonate resin layer, and the thickness of the polycarbonate resin layer is 50% or more of the total thickness.   The laminated resin body for button switch covering according to claim 1, wherein the polycarbonate resin layer and the acrylic resin layer are laminated by coextrusion molding.   The laminated resin body for button switch covering according to claim 1 or 2, wherein the acrylic resin layer is a layer made of a methacrylic resin and a rubber-like polymer.