JPS5845763B2 - switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switch using a flame-retardant resin composition with excellent tracking resistance as a support material for a live part, and is applicable to switches that may get wet with water, such as a washing machine 1.
Improving the tracking resistance of insulating plastics used to support live parts of switches used in dishwashers, dryers, and Sendai cooking appliances, etc.
The purpose is to improve heat resistance.

In general, plastic materials are often used to insulate and support live parts.

Plastic materials for electrical insulation are required to have heat resistance and tracking resistance in addition to insulation performance.

In particular, power switches used in washing machines, etc., are often used outdoors, so the washing machine body is exposed to wind and rain, and can be exposed to direct sunlight in summer or frozen in winter.53! exposed to boundaries.

Therefore, in terms of heat resistance, the temperature at which plastic molded products begin to deform is 80°C or higher, and in terms of cold resistance, it is required that plastic molded products do not break or crack at 120°C. .

Further, washing machines are often placed in high humidity environments such as in bathrooms, and as for moisture resistance, materials that have extremely low hygroscopicity and do not absorb moisture and cause insulation deterioration are required.

In addition, there is a risk that the power switch may get wet due to water from wind and rain, dew condensation during high humidity, or when water is spilled directly into the washing machine due to a mistake in operating the washing machine. There is a risk of tracking between metal parts, causing the plastic to ignite and causing a fire.

In addition, in order to prevent the product from catching fire even if the plastic ignites, the plastic material must be flame resistant, such as vertical combustible material specified by Underwriters Laboratories Inc. Item 94 (UL No. 94). It is required to have flame resistance rated at 94V-1 class or higher by testing.

As detailed above, a power switch such as a washing machine that is likely to get wet with water is required to have tracking resistance, flame retardancy, and heat resistance.

The present invention provides an electrically insulating plastic material that satisfies these strict requirements, and by using the material of the present invention as a supporting material for a live part, a high-performance switch can be obtained.

Various studies have been conducted on methods for making thermoplastic resins flame retardant, and many proposals have been made.

Generally, flame retardants include halogen compounds, inorganic compounds,
A method is used in which flame retardancy is imparted using a single phosphorus compound or a combination of two or more.

However, due to the additives added to these flame-retardant thermoplastic resins to impart flame retardancy, it is inevitable that the electrical performance of these flame-retardant thermoplastic resins will be lower than before flame retardancy.

In particular, the wet tracking performance deteriorated significantly, and many restrictions had to be placed on product design that was possible with conventional flame-retardant resins.

Furthermore, since these additives reduce heat resistance performance,
For the purpose of improving heat resistance, plastics are often blended with 5 to 30% glass fiber.

However, when thermoplastics containing glass fibers are combusted, the glass fibers act as a wick in a candle and assist in the combustion of the plastic.

That is, when glass fiber is blended to improve heat resistance, flame retardant performance tends to decrease.

From this point of view, the present inventors conducted extensive research to prevent the deterioration in tracking resistance of flame-retardant thermoplastic resins, which had hitherto been unavoidable. The inventors have found that tracking resistance is significantly improved and heat resistance is also improved by adding 1 to 50 parts by weight per part, and this has led to the present invention.

The flame-retardant resin used in the present invention must have a flame retardancy of 94V-1 or higher in the flame-retardant test under UL94. As a resin! .

Acrylonitrile-butadiene-styrene terpolymer resin (ABS), acrylonitrile-styrene copolymer resin (AS), methyl methacrylate and its copolymer resin, polypropylene, modified polyphenylene oxide, polybutylene terephthalate, vinyl chloride and its copolymer resin Polymer resins and polymer blends containing these as main components can be used.

In addition, as other blend fractions, thermoplastic resins other than those mentioned above, such as polycarbonate, polyethylene terephthalate, polyamide, polyarylene ester, etc., and thermosetting resins, such as epoxy resin, are used.

In order to increase the flame retardancy of these resins to 94V-1 or higher in the flame resistance rating measured by UL94, there is a method of adding commonly used flame retardants, such as halogen compounds, inorganic compounds, phosphorus compounds, etc. Flame retardance can be imparted by a single substance or a combination of two or more types.

Further, the glass beads referred to in X are small, true spherical glasses, and those whose particle sizes are mostly distributed in the range of 3 to 500 microns are suitable.

If it is more than 500 μm, the physical properties of the molded product, especially the impact resistance, will be deteriorated, so it is not preferable.

Further, the glass beads may be surface-treated by a known method using a silane coupling agent, an organic titanate coupling agent, or the like in order to improve the bonding with the glass stick.

The effect of the combination of glass beads according to the present invention is remarkable, and although the details of its mechanism of action are not currently clear, it is probably due to the following reasons.

(1) Due to the spherical beads, molding distortion of the molded product is reduced compared to glass fiber blends.

(2) Molded products containing glass fibers have the ends of the glass fibers protruding from the surface, which are thinly coated with resin.

In other words, the surface of the molded product becomes finely porous.

If an arc strikes the surface of the molded product in this state, the thin film-like resin on the surface of the glass fiber is likely to carbonize, and it is thought that the tracking resistance will therefore decrease.

On the other hand, when glass beads are blended, the surface of the molded product is relatively smooth when the blending amount is up to 50 parts by weight, and therefore it is thought that carbonization of the surface resin due to arcing is reduced.

The blending amount of the glass beads is 1 to 50 parts by weight based on the ioo parts by weight of the flame-retardant thermoplastic resin knitted material, and if it is less than 1 part by weight, the tracking resistance will not be improved sufficiently; If it exceeds this, the properties of the thermoplastic resin, particularly the impact resistance and fluidity during molding, will be significantly reduced, which is not preferable.

The most preferred amount is 1 to 30 parts by weight.

The method for preparing the composition of the present invention is not particularly limited, and any suitable compounding method may be employed, such as a method using a tumbler mixer, a super mixer, a Nauta mixer, a Banbury mixer, a kneader, etc., a method using a roll, a method using a melt extrusion, etc. .

Of course, various additives used in ordinary thermoplastic resins, such as ultraviolet absorbers, plasticizers, colorants, fillers, lubricants, stabilizers, etc., may be added to the composition of the present invention, if necessary. .

Further, a small amount of glass fiber may be added for the purpose of improving heat deformation resistance and rigidity.

The present invention will be explained in more detail below with reference to Examples and Comparative Examples, but the scope of the present invention is not limited thereby.

Note that the performance evaluation of the molded samples was carried out by the following method.

(1) Flame resistance test Underwriters Laboratory Item 94 (UL94
A flame resistance test was conducted according to the standards of

However, the dimensions of the test piece are 127 mm x 12.7 mm x 1.
Using 6 mm (wall thickness 1/16 inch), measurements were made on five test pieces, and flame resistance was graded according to the criteria specified in UL94.

(2) Tracking resistance test A tracking resistance test was conducted in accordance with IEC Publication 112.

However, the selection switch of the washing machine (Figures 1 and 2)
Assuming that the material is used in
Although the electrolyte was dropped between the electrodes at intervals of seconds, the electrolyte concentration was set to 2% and the dropping interval was shortened to 15 seconds in order to exhibit a promoting effect.

Evaluation was made based on the time it took for the test piece to ignite.

(3) Heat resistance test The heat distortion temperature was measured according to the test method specified in ASTM D648.

However, the test piece is 127gX 12.7BHX 6.4M
Fabricless 18.6 Kf/crt
It was set as t.

Also, the specimens were not annealed before measurement.

Examples 1 to 5 and Comparative Examples 1 to 2 High rigidity ABS resin (Sevian V12 manufactured by Daicel Corporation)
0) Predetermined amounts of a halogenated organic compound, chlorinated polyethylene, and antimony trioxide were blended with 100 parts by weight in the proportions shown in Table 1, and after mixing in a drum-type blender, the cylinder diameter was 40T.

The mixture was kneaded and pelletized using an extruder at a cylinder temperature of 220°C.

Next, test pieces were prepared using an injection molding machine with an injection capacity of 3.5 ounces at a cylinder temperature of 220'C.

The test pieces were subjected to a flame resistance test and a tracking resistance test.

The results are shown in Table 1.

Example 6 The structure of a switch using the material of Example 2 is shown in FIG. 1D, and this switch is connected as shown in FIG.

In FIG. 1, reference numeral 1 denotes a base which is an insulating support supporting a fixed spring plate 2 and a movable spring plate 3. As shown in FIG.

Reference numeral 4 denotes a button for insulating the movable splash plate 3, and this button 4 is interlocked with opening and closing of a lid (not shown) or the like.

5 and 6 are contacts fixed to fixed and movable spring plates 2.3, forming the main part of the live part.

2a and 3a are terminals of fixed and movable spring plates 2 and 3;
7 is a lead wire of the switch.

FIG. 2 is a circuit diagram for connecting the switches, where 8 is an outlet for turning on the power, 9 is a switch having the above structure, and 10 is a load such as a motor or a heater.

In the above configuration, when an AC voltage of 200 V is applied to the power supply outlet 8, the current flowing through the load 10 is set to 2 when the switch 9 is closed, and then the switch 9 is opened, the tracking resistance is as follows. .

First, one drop (approximately 0.1 to 0.2 CC) of ammonium chloride solution having a concentration of 2% is dropped onto the surface A of the base 1 of the switch 90 facing the spring plates 2 and 3 every 15 seconds.

As a result, base 1
If it forms, it will ignite in about 0.1 to 1 hour, but
According to the composition of Example 2, although carbonization occurred, ignition did not occur.

As described above, according to the present invention, by molding glass beads in a resin, tracking resistance and heat resistance can be significantly improved, and the molded surface is evenly glossy.

In addition, by applying such a composition as a support material that supports the live part of the switch, even if the switch is exposed to dew condensation or wetting due to water, the support surface will not be damaged due to tracking, and furthermore, this will prevent damage to the support surface due to tracking. It is possible to prevent the occurrence of ignition, etc., resulting in significant improvements in safety and reliability, and it is also possible to make the switch flame retardant.

[Brief explanation of drawings]

FIG. 1 is an external perspective view of a switch according to an embodiment of the present invention, and FIG. 2 is an electrical circuit diagram showing an example of its use. 1... Base (insulating support), 5, 6...
...Contact (main part of live part).

Claims (1)

[Claims] 1 Acrylonitrile-butadiene-styrene ternary copolymer resin, acrylonitrile-styrene copolymer resin, methyl methacrylate and its copolymer resin, polypropylene, modified polyphenylene oxide, polybutylene terephthalate, vinyl chloride and its copolymer resin, and mainly these 100 parts by weight of a flame retardant resin with a flame resistance rating of 94V-1 or higher as measured by UL94, which is obtained by blending a flame retardant with a resin selected from a polymer blend as a component, and has a particle size of 3 to 500μ 1 to 50 spherical glass beads
1. A switch comprising an insulating support for supporting a live part formed of a resin composition containing parts by weight.