JP2003138124A - Plastic sheet and laminated product and film key - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film key improved durability and affording somewhat softer touch than that of a polycarbonate (PC)/polybutylene terephthalate (PBT) copolymer alloy. SOLUTION: This film key 1 is molded from a plastic sheet 2 consisting essentially of the PC/flexible PBT copolymer alloy resin prepared by melt blending 40-70 wt.% of the PC with 60-30 wt.% of the flexible PBT copolymer. The plastic sheet 2 has a pencil scratch value measured by the method of the JIS K 5400 tester within the range of B to 3B and <=1,000 MPa flexural modulus of elasticity of the flexible PBT copolymer alone measured by ASTM D790. The flexible PBT copolymer is modified by substituting 10-40 mol% of terephthalic acid in the PBT with an aliphatic dicarboxylic acid.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a plastic sheet material (plastic film or plastic sheet).
The present invention also relates to a laminated molded product and a film key, and more particularly to a plastic sheet material, a laminated molded product and a film key that are not easily damaged even when a shocking pressing force is repeatedly applied.

[0002]

2. Description of the Related Art Conventionally, as a film key, a laminated body (laminated sheet) in which a soft plastic layer is laminated on the surface of a hard plastic layer is thermoformed to form a convex pressing portion on the soft plastic layer side. is there. This film key has a hard plastic layer that retains the required rigidity, while a soft plastic layer provides cushioning, a soft tactile sensation, or a non-slip effect.

Further, in Japanese Patent Laid-Open No. 2000-263659, a hard resin film such as polycarbonate or polyethylene terephthalate and a soft resin film such as urethane are laminated, and then the film is heated and placed on a working mold. A method of manufacturing a key top plate (film key) in which a large number of convex portions are formed by drawing a vacuum and resin is filled inside the convex portions is disclosed.

[0004]

However, when a polyurethane type (urethane rubber) is used for the soft layer,
When used at low temperatures, the flexibility and elasticity deteriorate. Further, urethane rubber is easily colored by ultraviolet rays. Therefore, there is a problem when used for a film key of a device such as a mobile phone which is often used outdoors.

Further, in the case of a laminated body in which a hard resin film such as polycarbonate or polyethylene terephthalate is bonded to a soft resin film such as urethane, the molding conditions for heating and softening the laminated body for pressure molding are narrow. However, there is a drawback that only a product having a relatively low molding ratio can be satisfactorily manufactured. Furthermore, when polycarbonate is used as a hard plastic layer, it has high tensile strength and impact strength and good dimensional stability, but it is weak against fatigue and causes brittle fracture, so it is durable when repeatedly loaded like a film key. Becomes worse.

Further, in recent years, the development of mobile phones has been remarkable, and with the multi-functionalization of mobile phones, one key plays many roles, the frequency of keystrokes greatly increases, and the durability of buttons is expected to improve. It is rare. In addition, since the frequency of keystrokes increases, a film key with a soft touch is preferred.

The present invention has been made in view of the above problems, and a first object thereof is to process a film key into a film key.
It is an object of the present invention to provide a plastic sheet material suitable as an in-mold molding film or sheet that has improved durability and a softer feel than polycarbonate. A second object is to provide a laminated molded product using the plastic sheet material, and a third object is to provide a film key using the plastic sheet material.

[0008]

In order to achieve the first object, according to the invention of claim 1, 40 to 70% by weight of polycarbonate and 60 to 30% by weight of soft polybutylene terephthalate copolymer are used. A film or sheet containing a polycarbonate / soft polybutylene terephthalate copolymer alloy resin alloyed by melt blending as a main component, and having a pencil scratching value of B to 3B measured by a JIS K 5400 tester method. .

According to the first aspect of the present invention, when processed into a film key, the durability is improved and the tactile feel is softer than that of polycarbonate or polycarbonate / polybutylene terephthalate alloy resin, and bending load is repeatedly applied. The durability of the case is improved.

According to a second aspect of the present invention, in the soft polybutylene terephthalate-based copolymer according to the first aspect, 10 to 40 mol% of terephthalic acid of polybutylene terephthalate is an aliphatic dicarboxylic acid. It has been replaced and modified. In this invention, the plastic sheet material of the invention described in claim 1 can be easily obtained.

In order to achieve the second object, in the invention described in claim 3, polycarbonate 50 to 80 is provided on one side of the plastic sheet material according to claim 1 or 2.
Wt% and polybutylene terephthalate 50 to 20 wt%
And a hard plastic layer consisting of The polybutylene terephthalate is not limited to the homopolymer, and may be a copolymer such as isophthalic acid modified as long as it has rigidity close to that of the homopolymer. According to the present invention, as compared with the case where the hard plastic layer is formed of polycarbonate or polyethylene terephthalate alone, the deep drawability is excellent, the air pressure moldability is improved, and the durability of the product is improved.

According to a fourth aspect of the present invention, a printing layer is formed on the plastic sheet material according to the first or second aspect, and a molten resin is injection-molded from the printing layer side to form a backing layer. It becomes. In the present invention, the printed layer is covered with the backing layer, so that abrasion of the printed layer is reliably prevented.

According to a fifth aspect of the present invention, a convex portion is formed on the plastic sheet material according to the first or second aspect, and a molten resin is injection-molded in the concave portion on the back surface corresponding to the convex portion. To form a backing layer. In the present invention, due to the presence of the resin backing layer provided on the back side of the convex portion, the plastic sheet-like material alone contributes less of the force applied to the convex portion, and appropriate flexibility is imparted.

In order to achieve the third object, according to the invention of claim 6, a printing layer is formed on one side of the plastic sheet material according to claim 1 or 2, and the side opposite to the printing layer is formed. Then, a convex portion for a push button that is convex was formed, and a molten resin was injection-molded in the concave portion on the back surface of the convex portion for a push button to form a backing layer. The film key of the present invention is used as a switch component of an electronic device having a large number of switches.
Since a film having excellent flexibility and flexural modulus is used as a material, when used as a film key of a mobile phone, the durability is improved and the feel of a finger is excellent. In addition, there is no risk of fingers touching the print layer, and there is no risk of wear of the print layer due to button operation.

According to a seventh aspect of the invention, a printed layer is formed on the hard plastic layer side of the laminated molded body according to the third aspect, and a convex portion for a push button is formed on the opposite side of the printed layer. Then, a molten resin was injection-molded in the concave portion on the back surface of the convex portion for the push button to form a backing layer. In this invention, since the hard plastic layer is present, the restoring force when the pressing force on the convex portion for the push button is released is improved and the operability of the film key is improved, as compared with the invention according to claim 7. To do.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in a film key will be described below with reference to the drawings.

FIG. 1A is a schematic perspective view of the film key 1 viewed from the front side, FIG. 1B is a schematic perspective view viewed from the back side, and FIG. 1C is a partial schematic sectional view. Figure 1 (a),
As shown in (c), in the film key 1, a printing layer 3 is formed on one surface of a plastic sheet material 2 and the printing layer 3 is formed.
A push button convex portion 4 that is convex on the opposite side is formed. The backing layer 6 is provided in the concave portion 5 on the back surface of the convex portion 4 for the push button.
Are formed. The backing layer 6 is formed by injection-molding a molten resin, and a convex portion 7 for pressing a switch contact (shown in FIG. 2) projects in the central portion thereof on the side opposite to the convex portion 4 for a push button. Is formed. The print layer 3 is provided with patterns such as numbers, letters, and symbols indicating the role of each push button protrusion 4 at a position corresponding to each push button protrusion 4. In FIG. 1A, only numbers are shown.

The plastic sheet material 2 is composed of 40 to 70% by weight of polycarbonate (PC) and a soft polybutylene terephthalate copolymer (soft PBT copolymer) 6
It is composed of a film or sheet containing PC / soft PBT copolymer alloy resin as a main component, which is alloyed by melt blending with 0 to 30% by weight. The plastic sheet material 2 is a film when the thickness is less than 0.1 mm, and a sheet when the thickness is 0.1 mm or more. The thickness of the plastic sheet material 2 is preferably 50 to 300 μm, and 100 to 200 in consideration of strength during processing and use.
μm is more preferable.

The plastic sheet material 2 is JIS K
The pencil scratch value measured by the 5400 tester method is B to 3
It is the range of B. If the hardness is harder than B, the feel becomes harder,
It is inferior in keystroke durability. If it is softer than 3B, nail marks are liable to be formed, the sheet becomes fluffy, and the handling property during processing is poor. In addition, if the composition is softer than 3B, there is a problem that the resin for the lining is deformed by the heat when it is injected. In addition, when the soft PBT copolymer alone used in the PC / soft PBT copolymer alloy resin is
The flexural modulus measured by STM D790 is 50 MPa or more and 1000 MPa or less. The soft PBT copolymer is a polybutylene terephthalate terephthalic acid 10
-40 mol% is modified by substitution with an aliphatic dicarboxylic acid. As the aliphatic dicarboxylic acid, for example, adipic acid or sebacic acid is used.

The film key 1 constructed as described above
Is mounted so as to cover a predetermined position of a switch board of a mobile phone or a small information device, for example. As shown in FIG. 2, the switch substrate 8 includes a printed circuit board 9 on which switch electrodes 9a are formed in a matrix, and an insulating material spacer 10 having holes 10a formed at positions corresponding to the electrodes 9a.
And an electrode 11a that constitutes a switch in cooperation with the electrode 9a.
Of the insulating sheet 11 formed in a matrix.

When the convex portion 4 for a button as the depressing operation portion of the film key 1 is pressed with a fingertip, the convex portion 7 is formed into the insulating sheet 1.
1 is deflected to the printed board 9 side, the electrode 11a formed on the insulating sheet 11 is held in contact with the electrode 9a formed on the printed board 9, and the switch is brought into a conductive state (on state). When the pressing of the push button convex portion 4 is released, the plastic sheet material 2 returns to its original state due to its rigidity, and the switch is turned off. The user confirms the symbols and characters provided on the push button convex portion 4 and presses the desired push button convex portion 4.

Next, a method of manufacturing the film key 1 will be described. When the film key 1 is manufactured, a plastic sheet material 2 having a print layer 3 provided with a pattern such as numbers, letters and symbols showing the role of each push button protrusion 4 at a predetermined position on one side is used. To do. Then, the side of the plastic sheet material 2 on which the printing layer 3 is formed is subjected to an adhesive treatment if necessary, and then, as shown in FIG. Printing layer 3 with plastic sheet material 2
Is set on the side of the mold 20. Then, the plastic sheet material 2 is heated by a heating device (not shown) to a temperature that softens it, air in the recess 20a of the mold 20 is exhausted, and a cover (not shown) that covers the plastic sheet material 2 is provided. The compressed air is supplied from the supply unit to the surface side of the plastic sheet material 2, that is, the upper side in FIG. 3A, and the plastic sheet material 2 is pressed against the mold 20. As a result, as shown in FIG. 3B, the plastic sheet material 2 is stretched and shaped into a shape faithful to the shape of the die surface of the die 20.

After the molded product 21 is cooled, the molded product 21 is moved to the mold 2
0, and as shown in FIG. 4 (c), the molded product 21 is placed in a mold 22 for injection molding in which concave portions 22a are formed corresponding to the convex portions 4 for push buttons. 4 is stored in the recess 22a. Next in FIG.
As shown in (d), the molding resin is injected into each of the recesses 5 of the molded product 21, and the protrusions 7 are formed on the back surface side (the upper side in FIG. 4D) of the molded product 21. Then, after the molded product 21 is cooled, the molded product 21 is taken out from the mold 22 and, if necessary, the outer shape is processed to complete the film key 1.

(Examples and Comparative Examples) With the compositions shown in Table 1,
PC / soft PBT copolymer alloy resin PC and soft P
Using an alloy resin in which the compounding ratio with the BT-based copolymer or the modification ratio of the soft PBT-based copolymer is changed, a thickness of 1 is obtained.
A 25 μm sheet was prepared, printed with a urethane-based two-component curing type ink from the back side of the sheet, dried and cured, and then molded into a button shape of a mobile phone by die press molding.
The obtained molded product was mounted in a mold and a polycarbonate resin was injected from the concave side of the button to obtain a so-called film key.

At this time, in the case of deformation and breakage due to the heat of injection, the moldability was evaluated as x, and the other cases were evaluated as o. The following evaluation of durability was not carried out for those marked with X at this stage.

<Surface Hardness> The pencil scratch value was measured by the JIS K 5400 tester method. <Durability test> After assembling the obtained film key into the cell phone, press the "5" button located almost in the center of the key with 9N force at a speed of 3 times per second for 500,000 times in a row The film key was taken out, and it was observed whether or not a crack was generated around the "5" button. When the crack was generated even a little, the "durability" was evaluated as x, and the others were evaluated as o.

[0027]

[Table 1] From Table 1, a film or sheet containing, as a main component, an alloy resin obtained by alloying 40 to 70% by weight of PC and 60 to 30% by weight of a soft PBT copolymer by melt blending, is a JIS K 5400 testing machine. It was confirmed that the durability was improved when the pencil scratch value measured by the method was in the range of B to 3B. At this time, the flexible PBT-based copolymer alone has a flexural modulus of 50 measured by ASTM D790.
It becomes above MPa and below 1000MPa. Also, soft P
The BT copolymer is 10 to 40 of terephthalic acid of PBT.
It was confirmed that the desired durability was obtained when mol% was modified by substitution with an aliphatic dicarboxylic acid.

This embodiment has the following effects. (1) A film or sheet containing 40 to 70% by weight of PC and 60 to 30% by weight of a soft PBT-based copolymer as an alloy by melt-blending, which contains PC / soft PBT-based copolymer alloy resin as a main component. JIS K 540
The pencil scratch value measured by the No. 0 tester method is in the range of B to 3B. Therefore, when processed into a film key, the durability is improved and the feel is softer than that of polycarbonate or polycarbonate / polybutylene terephthalate alloy resin.

(2) PC / soft PBT copolymer A of soft PBT copolymer alone used for alloy resin
When the flexural modulus measured by STM D790 is 50 MPa or more and 1000 MPa or less, the durability when repeatedly subjected to a bending load is improved.

(3) 10 to 4 of terephthalic acid of PBT
By using the soft PBT-based copolymer modified by substituting 0 mol% with an aliphatic dicarboxylic acid, the plastic sheet material 2 having desired durability and flexibility can be easily obtained.

(4) The printing layer 3 is formed on one surface of the plastic sheet material 2, and the convex portion 4 for the push button is formed on the opposite side of the printing layer 3, and the concave portion on the back surface of the convex portion for the push button is formed. A molten resin was injection-molded into the backing layer 5 to form a backing layer 6 to obtain a film key 1. Therefore, when used as a film key of a mobile phone, the durability is improved and the tactile sensation of the fingers is excellent. In addition, there is no risk of fingers touching the print layer 3, and there is no risk of wear of the print layer 3 due to operation of the button protrusion 4.

The embodiment is not limited to the above, but may be embodied as follows, for example. A soft PBT-based copolymer can be obtained by using a soft copolymerization component or by reducing the crystallinity by copolymerization. Therefore, the terephthalic acid, which is an acid component of the PBT constituent material, is not limited to the one in which a part of the terephthalic acid is replaced with an aliphatic dicarboxylic acid, and it is a glycol component of 1,4.
A part of butanediol is diethylene glycol or 1,6
It may be replaced with hexanediol, polytetramethylene glycol or the like. Moreover, you may perform the modification which combined the said substitution. Also, aliphatic dicarboxylic acid and isophthalic acid modification may be combined. The ratio of each modification is not particularly limited.
It is desirable that the flexural modulus measured by TM D790 is 50 MPa or more and 1000 MPa or less.

On one side of the plastic sheet material 2,
A laminated molded body may be formed by laminating a hard plastic layer composed of 50 to 80% by weight of polycarbonate and 50 to 20% by weight of polybutylene terephthalate. In this case, P
Compared to the case of forming a hard plastic layer with C or polyethylene terephthalate alone, it has excellent deep drawability,
The air-pressure moldability is improved and the durability of the product is improved.

The film key 1 may be formed by using the laminated molded body. For example, as shown in FIG. 4, the plastic sheet material 2 and the hard plastic layer 12 are
The printed layer 3 is formed on the hard plastic layer 12 side of the laminated molded body 13 composed of. Then, the convex portion 4 for the push button that is convex on the side opposite to the printed layer 3 is formed, and the convex portion 4 for the push button is formed.
The molten resin is injection-molded in the concave portion 5 on the back surface of the backing layer 6
To form the film key 1. In this case, since the hard plastic layer is present, as compared with the case where the hard plastic layer is not present, the restoring force when the pressing force on the push button convex portion 4 is released is improved, and the operability of the film key 1 is improved. improves.

The plastic sheet material 2 is not limited to being used as the material of the film key 1, but may be used as an interior material of an automobile, for example. In this case, a convex portion is formed on the plastic sheet material 2, and a molten resin is injection-molded in the concave portion of the back surface corresponding to the convex portion to form a backing layer. Unlike the case of the film key, the recess is formed as a curved surface having a small curvature as a whole. Due to the presence of the resin backing layer provided on the back side of the convex portion, the plastic sheet material 2 is less responsible for the force applied to the convex portion,
Appropriate flexibility is imparted. Plastic sheet material 2
You may form a printing layer on the back surface of.

Instead of forming the printed layer 3 on the surface of the hard plastic layer 12, it may be formed between the plastic sheet material 2 and the hard plastic layer 12. In this case, there is no possibility of being disturbed when the printed layer 3 comes into contact with the molten resin having a high temperature.

The push button convex portions 4 are not limited to those arranged in a matrix, and may be appropriately changed depending on the arrangement of the switches of the electric device used. The shape of the push button protrusion 4 is not limited to an ellipse or a quadrangle, and may be changed to an appropriate shape such as a triangle.

The technical idea which can be understood from the above-mentioned embodiment will be described below. (1) In the invention according to claim 2, the aliphatic dicarboxylic acid is adipic acid or sebacic acid.

(2) In the invention described in any one of claims 1 to 7, the pencil scratching value is 2B. (3) In the invention of claim 1, the flexural modulus of the soft polybutylene terephthalate copolymer alone used in the polycarbonate / soft polybutylene terephthalate copolymer alloy resin measured by ASTM D790. Is 50 MPa or more and 1000 MPa or less.

[0040]

As described in detail above, according to the inventions of claims 1 and 2, when processed into a film key, the durability is improved and the tactile feel is better than that of a polycarbonate / polybutylene terephthalate alloy resin. It becomes soft. According to the inventions of claims 3 to 5, the durability is improved and the feel is softer than the polycarbonate / polybutylene terephthalate alloy resin even when bending stress is repeatedly applied. According to the sixth and seventh aspects of the invention, the durability is improved and the feel is softer than that of the polycarbonate / polybutylene terephthalate alloy resin.

[Brief description of drawings]

1A is a schematic perspective view of a film key according to an embodiment as seen from the front side, FIG. 1B is a schematic perspective view as seen from the back side, and FIG. 1C is a partial schematic cross-sectional view.

FIG. 2 is a partial schematic cross-sectional view of a state in which a film key is attached to a switch board.

FIG. 3 is a schematic cross-sectional view showing a manufacturing process of a film key.

FIG. 4 is a partial schematic sectional view of a film key according to another embodiment.

[Explanation of symbols]

1 ... film key, 2 ... plastic sheet material, 3 ...
Printed layer, 4 ... Push button convex portion, 6 ... Backing layer, 7 ... Recessed portion.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F071 AA45 AA50 AF25Y AH12                       BC01                 4F100 AK42A AK42B AK45A AK45B                       AL01A AL05A AL05B AL07A                       BA02 BA10B BA10C DD01A                       EJ39 EJ392 EJ48 EJ482                       GB41 HB31C JK13A YY00A                       YY00B                 4J002 CF07X CG00W GF00 GQ00

Claims (7)

[Claims] 1. Polycarbonate 40 to 70% by weight,
Soft polybutylene terephthalate copolymer 60 to 30
A film or sheet having a polycarbonate / soft polybutylene terephthalate copolymer alloy resin as a main component, which is alloyed by melt blending with wt%, and has a pencil scratching value of B to B measured by a JIS K 5400 tester method. 3B is a plastic sheet material. 2. The plastic sheet form according to claim 1, wherein the soft polybutylene terephthalate-based copolymer is modified by substituting 10 to 40 mol% of terephthalic acid of polybutylene terephthalate with an aliphatic dicarboxylic acid. Material. 3. Polycarbonate 50-80 on one surface of the plastic sheet material according to claim 1 or 2.
Wt% and polybutylene terephthalate 50 to 20 wt%
A laminated molded body obtained by laminating a hard plastic layer consisting of 4. A laminate formed by forming a printing layer on the plastic sheet material according to claim 1 or 2 and forming a backing layer by injection molding a molten resin from the printing layer side. 5. The plastic sheet material according to claim 1 or 2, wherein a convex portion is formed, and a molten resin is injection-molded in a concave portion of the back surface corresponding to the convex portion to form a backing layer. Laminated molded product. 6. A printing layer is formed on one surface of the plastic sheet material according to claim 1 or 2, and a projection for a push button is formed on the opposite side of the printing layer, and the push button is formed. Film key with a backing layer formed by injection molding molten resin in the recess on the back of the projection. 7. The laminated layered product according to claim 3, wherein a printed layer is formed on the hard plastic layer side, a convex portion for a push button is formed on the opposite side of the printed layer, and a convex portion for the push button is formed. A film key with a backing layer formed by injection molding molten resin into the recess on the back of the unit.