JP2657171B2 - Method of manufacturing cover member for push button switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for casting a liquid resin in a non-pressurized state, curing the liquid resin by heating, and forming a key top portion.
Cover member for push button switch molded integrally with rubber-like elastic body
And a method for producing the same.

[0002]

2. Description of the Related Art Liquid thermosetting resin (hereinafter simply referred to as liquid resin )
When the resin is cast into a mold or the like under no pressure and heated and cured, the liquid resin is exposed to the subtle temperature difference in the mold and the difference in the flow path of the liquid resin. The curing speed is different in each part , and the liquid resin at the outer edge part in contact with the mold starts to cure first, and finally the central part cures. This difference in cure speed causes differential shrinkage of the molded article, resulting in concave warp on the surface without formwork regulations. Therefore, conventionally , when casting and heating and curing liquid resin without pressure ,
By mixing a small amount of thermoplastic resin having a structure similar to this liquid resin, only the thermoplastic resin having flexibility at the time of heating reaches the outer periphery of the mold, and the liquid resin remains at the center , A method of correcting deformation such as warpage immediately before cooling at the time of taking out a molded product, a method of mixing glass fibers into the liquid resin, and the like are used.

[0003]

A small amount of thermoplastic resin similar components in the liquid resin for hand thermosetting THE INVENTION An object you try solving], in the case of the method to be blended, the thermoplastic resin is tinged tacky,
The molded product is easy to adhere to dust, etc.
When the top of the key is formed, the top surface is
The touch was bad. Furthermore, the shape of the mold, not be suppressed warpage to be determined the optimal formulation conditions for each size, realistically difficult to. In the method of mixing glass fibers in a liquid resin, it is impossible to suppress the complete effect thin warp. In this way, the liquid resin is cast without pressure and heated
Even after curing to form the key top,
A concave warp is formed on the surface, the contact feeling is poor, and pressing
It was bad workability.

[0004]

SUMMARY OF THE INVENTION The present invention solves such disadvantages and disadvantages, and provides a cover for a push button switch according to the present invention.
Method of manufacturing a chromatography member top surface area of 300 mm ² or more Kito'
In obtaining a cover member for a push button switch having a locking part,
Injecting liquid thermosetting resin into the mold without pressure
Next, a rigid object that does not deform even under the heating conditions during molding
After placing the liquid thermosetting resin,
Forms a key top part wrapped in thermosetting resin,
Before the curable resin is completely cured, the uncured rubber-like elastic
The raw material is filled and molded, and a rubber-like
Forming a base part and a thin movable part
And integrated key top, base and thin-walled movable part
Is characterized by For pushbutton switch of the present invention
The method of manufacturing the cover member is to apply the liquid resin
In, that is, surrounded by a mold as shown in FIG.
Top open rather than pressurized into cavity
Into the mold that has been
Without interruption or interruption, a rigid object that does not deform even under heating conditions during molding is placed in the mold and integrated with the liquid resin ,
A rigid object is wrapped in a thermosetting resin, and the top surface is in contact with the mold
Forming a key top part with a free surface of touch,
On top of this, uncured rubber-like elastic material is filled and molded,
Base portion consisting of key top portions and the rubber-like elastic material, is to integrally of a thin movable part.

That is, the present inventors have conducted various studies on a method of solving the generation of surface warpage due to uneven shrinkage of the liquid resin for the key top portion during curing. If a resin such as aluminum, iron, or lead, or a rigid object that is not easily deformed such as wood or bamboo is placed and the liquid resin is cast without pressure and molded, this liquid resin is accompanied by uneven shrinkage. We found that the warpage of the molded product was suppressed and that a molded product without such warpage could be obtained, and we proceeded with research on the type, amount and method of rigid objects used here.
The key top portion of the cover member for the push button switch is formed by the above-described method, and the uncured rubber-like
The raw material is filled and molded, and a rubber-like
Base and thin-walled movable parts
If it becomes, the area of the top surface of the key top part exceeds 300 mm ²
Make <br/> sure the cover member for push button switch can be obtained an at large is also no hard fingers touch the warpage or deformation, such as, the key top portion having a rigid object in this way
And a base portion and a thin movable portion made of a rubber-like elastic body.
Before the liquid resin in the key top is completely cured.
Excellent haptic feel without warping
A method of manufacturing a cover member for a push button switch has been completed. This will be described in more detail below.

[0006]

The cover member for a push button switch according to the present invention has the above structure.
As a result, warpage due to non-uniform shrinkage of the liquid resin is prevented by a rigid object surrounded by resin.
The key top part has a good touch feeling,
This provides an advantage that a cover member for a push button switch having elasticity that reacts to crab can be easily obtained.

The cover member for a push button switch of the present invention is used.
The that key top liquid resin for forming property of shrinking when heated molding corresponds clearly thermosetting resin. Specific examples thereof include oligomers and monomers such as polycarbonate and unsaturated polyester, and those obtained by combining styrene and diallyl phthalate, in which the effect of the present invention is remarkable because shrinkage is particularly severe. It is also effective for oligomers and monomers such as acryl, methacryl and urethane, and compounds thereof.
In addition, these liquid resins may be blended with a curing agent, an additive, a colorant, and the like as necessary. Although the shape and size of the mold are arbitrary, it is preferable that the material is usually made of a metal such as iron having excellent heat resistance.

A conventional liquid resin is cast without pressure and cured by heating.
<br/> in FIGS. 3 (a) illustrating an example of a key top portion forming method according to the key top portion forming mold of the mold 13 from the injection device 11 frame 14
Liquid resin 12 injected into the beginning of the cure from the outer peripheral portion, the end to Katawaku central portion is hardened, it the liquid resin in the mold
Unlike curing speed of the liquid resin by the position of, respectively, key
-Non -uniform shrinkage occurs in the top portion 15 (see FIG. 3B),
Irregular warpage was generated concavely on the free surface side where there was no restriction on the mold 14 (see FIG. 3 (c)). In the present invention, this key
In order to prevent uneven shrinkage of the liquid resin when forming the top part, a rigid object that does not deform even under the heating conditions during molding and the liquid resin injected without pressure are integrated in the mold. However, the placement of rigid objects in the mold
With or without interruption during injection
However, due to the ease of placing rigid objects in the
Pause the resin injection, place a rigid object, and then
It is preferable to inject resin. Further, as the material of the rigid object, as long as it is not deformed by the molding conditions for heat curing the liquid resin, specific examples are aluminum, iron, lead, brass, gold, silver, metal such as solder material Ya Examples thereof include rigid natural fibers such as wood and bamboo, and thermosetting resin molded products such as polycarbonate and unsaturated polyester which have been previously processed by pressure molding or cutting without deformation.

The shape of the rigid object may be the same as the shape of the mold and at least one size smaller than the mold, but the shape does not necessarily have to be exactly the same as the shape of the mold. What is necessary is just to arrange | position the thing of a simple shape like a rectangular parallelepiped. However, its size must always be smaller than the formwork. This is because, when a load such as compression is applied to the mold in a later step, the mold may be damaged, and the rigid object may be exposed from the molded product. The timing of installing the rigid object is as described above,
During the injection of the liquid resin into the mold , the injection may be interrupted.
Or it can be placed without interruption.

Next, an example of forming a key top portion according to the present invention is shown in the drawings. FIG. 1 shows a cover for a push button switch according to the present invention .
Fig. 1 shows the method of forming the key top part of the member .
As shown in (a), casting from the casting device 1 a thermosetting shrink material 2 as the liquid resin into a mold 4 of the mold 3. Place
After the fixed quantity injection, the injection is interrupted, and a rigid object 5 which is hardly thermally deformed prepared in advance is put into the mold 4 and further thermoset.
Not good if the injection is heated to cure the sex shrink material 2. This quito
As shown in FIG. 1 (b) , the peripheral portion is made of resin.
Because having a hard rigid object 5 which thermally deformed wrapped, thermoset
Uneven shrinkage in the sexual shrink material 2 of the mold in is corrected by the rigid object, the key top portion, as shown in FIG. 1 (c), given the advantage that it becomes one not warp .

[0011] In this case, the shape of the heat hardly deformed rigid object 5 that yo <br/> to something similar to the shape of the mold bur, it rather than particular limitation, rod-shaped , Or the like , and the number does not need to be limited to one. Also, this size should be close to the size of the mold, but in order to prevent damage to the mold when performing a compression press or the like in a later step, 1-2 mm is attached to the side of the mold.
It is preferable to set the size so that the intervals can be provided.

According to this method, as described above, a key free from warpage is obtained by a pressureless casting method using a thermosetting liquid resin.
Toppu unit as it can be easily obtained, figure Re this 2
As shown in, the rubber-like elastic body is further filled before the liquid resin is completely cured, and the key top portion and the rubber-like elastic body are integrally formed to form the thin movable portion 8 and the base portion 9 .
Key top portion without warpage, Ru advantage is given that the pushbutton switch cover member 10 of the key top portion has a feeling hard can be easily obtained. When the key top portion is formed by a conventional method, the key top portion 16 has a warp as shown in FIG. pushbutton switch cover member 19 of the parts 18 is obtained by bonding and integrating is the key top portion is to have a feeling of hard, becomes one with the disadvantage of becoming to those having the same time chaotic warp.

[0013]

Next, one embodiment of the present invention will be described based on an embodiment.
I will tell. Preliminary experiment; shown in Table 1 before forming the cover member for the push button switch.
Key tops with different top sizes (2 mm depth
Through). Key top section heated to 150 ° C
To use mold, with no pressure, after injection with liquid resin to de I spoke monkey syringe blended with styrene to the unsaturated polyester (Nipro Corp.), from wooden rectangular parallelepiped (the sides both mold size is rigid object 1mm smaller) into the mold
These were cured and integrated to obtain a key top portion. this
It was confirmed that warpage occurred on the top of the key tops .
In Table 1, group A uses a rigid object,
No warpage was observed for any of the top sizes . However, except that this rigid body was not used for comparison, the group B molded in the same manner as the group A
The area of the top surface of the part forming mold is larger than 300 mm ²
And, the occurrence of warping was observed in this.

[0014]

[Table 1]

Example : A liquid resin obtained by combining an acrylic oligomer and an acrylic monomer is placed on a key top portion (key size: 5 mm × 60 mm × 3 mm) of a die for a push button switch to a depth of 1.5 mm using an air dispenser. After injection, stop injection and 2
After arranging a bamboo skewer of mmφ × 55mm , a further 0.5mm deep
After filling an equivalent amount of liquid resin and leaving it for 10 seconds, and confirming that the key top part was in a semi-cured state, silicone rubber / KE-951U [trade name of Shin-Etsu Chemical Co., Ltd.] was added to this mold.
100 parts by weight of a raw material obtained by mixing 2 parts by weight of a vulcanizing agent C-8 [trade name of Shin-Etsu Chemical Co., Ltd.], forming a thin movable portion and a base portion by compression molding, and heating together with a key top portion When a cover member for a push button switch with a hard key top part was made by hardening integral molding, a hard finger touch with no warpage despite the large area of the top surface of the key top part being 300 mm ² A cover member for a push button switch having an excellent key top portion was obtained.

[0016]

By using the production method of the present invention,
Due to non-uniform shrinkage of liquid resin during key top formation
The sled has a key top portion prevented by a rigid object
And the base portion and the thin movable part consisting of rubber-like elastic body and one
An integrated cover member for a push button switch of the present invention is obtained.
This push button switch cover member is
Even if the product has a large key top on the top
It can be a key top part with a hard finger touch,
Furthermore, it has elasticity that responds quickly to pressing operation.

[Brief description of the drawings]

FIG. 1 shows an example of a key top forming method according to the present invention .
(A) is a longitudinal sectional view showing the work of injecting the liquid resin into the mold , (b) is a longitudinal sectional view during thermosetting, and (c) is a longitudinal sectional view of the molded product. It is.

FIG. 2 is a longitudinal sectional view of a cover member for a push button switch having a key top portion made of a liquid resin according to the present invention.

FIG. 3 shows a conventional key formed by a non-pressure casting of a liquid resin.
The method of forming the top part is shown.
FIG. 4B is a longitudinal sectional view showing the operation of injecting grease, FIG. 4B is a longitudinal sectional view during the thermosetting, and FIG. 4C is a longitudinal sectional view of the molded product.

FIG. 4 is a longitudinal sectional view of a cover member for a push button switch having a key top portion made of a liquid resin according to a conventional method.

[Explanation of symbols]

1,11 injection device, 2,12 liquid resin, 3,13 mold, 4,14 mold (cavity), 5 rigid object, 6,15 key top part , 7,16 key top 8,17: Thin-wall movable section, 9,18: Base section, 10, 19: Push button switch cover member.

Claims (1)

(57) [Claims] 1. A key top portion having a top surface area of 300 mm ² or more.
In order to obtain a cover member for a push button switch,
Next, the liquid thermosetting resin is injected without pressure.
And place rigid objects that do not deform even under heating conditions during molding
After that, a liquid thermosetting resin is injected,
Forming a key top part wrapped in a curable resin,
Before the fat is completely cured, the uncured rubber-like elastic material
Fill and mold, and place a rubber-like elastic body on the key top part.
Forming a base part and a thin movable part consisting of
Integrate the key top, base and thin movable part
Method of manufacturing cover member for push button switch
Law.