JPH083165B2 - Signs - Google Patents

Description

TECHNICAL FIELD The present invention relates to a marker, and more specifically, it relates to a marker having a self-temperature control function, which is provided with a heating element made of a specific resin composition.

[Problems to be Solved by Conventional Techniques and Inventions] In cold regions, traffic signs may lose their functions due to snowfall or icing in winter, and traffic safety and smoothness may not be achieved sufficiently.

For this reason, it has been proposed to melt and remove snow and ice adhering to the signboard by incorporating a sheet heating element in the signboard such as a traffic sign.

For example, in Japanese Utility Model Publication No. 51-34717, a road sign plate having a structure in which a sheet-like heating element, a heat insulating plate, and a waterproof back plate are sequentially attached to the back surface of a metal display plate, and their peripheral edges are sealed with a waterproof material. Is proposed.

However, in this road sign board, the temperature of the sheet heating element is controlled by a thermostat and the fuse is connected as a safety device, so it is structurally complicated and it is not easy to manufacture and maintain it outdoors. There's a problem.

In addition, Japanese Utility Model Publication No. 51-36864 proposes a sign board in which a sheet-like heating element made of graft carbon and a conductive rubber sheet are laminated on a display board similar to the above-mentioned publication, but the temperature control is performed. Since it uses a thermostat, it has the same problems as described above.

Further, as a planar heating element used for general heating, a heating element using a kneading composition capable of controlling a self-temperature, which comprises a crystalline polymer and carbon black, is known (Japanese Patent Publication No. Sho 58-18722). , Japanese Examined Patent Publication No. 59-2693, etc.).

However, the self-temperature-adjustable planar heating element of these technologies has a positive temperature coefficient characteristic (the property that the electric resistance value increases with temperature rise) in a high temperature region where the kneading composition constituting the heating element exceeds 100 ° C. The temperature of the heating element when energized is 60 to 80 ° C.

Therefore, if an attempt is made to heat a large-area marker installed in a cold district with a heating element adjusted to such a high temperature range, an extremely large power consumption will be forced, which is not practical.

An object of the present invention is to provide a marker having a simple structure, which is provided with a heating element capable of self-temperature control in a temperature range lower than that of a conventional positive temperature coefficient characteristic composition, and which is easy to manufacture and maintain and inspect outdoors. To provide.

[Means for Solving the Problems] The present invention for achieving the above object comprises a kneaded composition of a crystalline polymer and carbon black, and the ratio of the maximum electric resistance value to the room temperature electric resistance value is A heating element formed of a composition having a positive temperature coefficient characteristic of 10 ³ or more and having an electric resistance value 10 times the room temperature electric resistance value in the range of 40 to 80 ° C. Is a labeled body.

 Hereinafter, the present invention will be described in detail.

-Heating element-The heating element used in the marker of the present invention can be formed from a resin composition having specific positive temperature coefficient characteristics. That is, the maximum electrical resistance of the composition and room temperature (25
Resin composition having a positive temperature coefficient characteristic of having a ratio with an electric resistance value at 10 ° C.) of 10 ³ or more and having an electric resistance value 10 times as high as a room temperature electric resistance value within a range of 40 to 80 ° C. Can be formed from.

Here, the reason why the ratio of the maximum electric resistance value and the electric resistance value at room temperature is required to be 10 ³ or more is to provide a practically sufficient withstand voltage property. If this ratio is less than 10 ³ , there is a risk of destruction when a large voltage is applied from the outside.

The reason why the temperature at which the electric resistance value is 10 times the electric resistance value at room temperature is 40 to 80 ° C. is necessary.
This is to provide proper heat generation characteristics. Above temperature is 40 ℃
If it is less than 0, the calorific value is insufficient, and it is not suitable for use in snow melting or melting of ice under environmental conditions lower than zero. The above temperature is
If the temperature exceeds 80 ° C, the amount of heat generated is too large, the temperature of the marker becomes unnecessarily high, and the power consumption becomes large, resulting in loss of practicality.

In order to obtain a composition having such a positive temperature coefficient characteristic, it is important to mix a specific crystalline polymer and carbon black in a specific ratio and perform proper kneading.

As the crystalline polymer, those having a crystal melting point in the range of 50 to 100 ° C. are preferably used, and specific examples thereof include ethylene-acrylic acid ester copolymers and ethylene-vinyl acetate copolymers. ing. Among the ethylene-acrylic acid ester copolymers, the ethylene-ethyl acrylate copolymer is particularly preferable.

As the carbon black, acetylene black, oil furnace black, thermal black and the like are preferable, and particularly the particle size thereof is 20 to 200 mμ, and preferably 25 to 200 mμ.
Those having a thickness of 100 mμ are preferably used. This particle size is 20m
If it is less than μ, the temperature coefficient of the sex becomes small, and
If it exceeds 0 mμ, the electric resistance value may become too large.

Next, regarding the blending ratio of these crystalline polymers and carbon black, the crystalline polymer is 50 to 70% by weight, preferably 55 to 65% by weight, and the carbon black is 30 to 50% by weight, preferably 35. ~ 45% by weight. Here, if the blending ratio of the crystalline polymer is less than 50% by weight, the self-temperature control function is not sufficiently exhibited, and if it exceeds 70% by weight, the electric resistance value becomes too large, and it is practically sufficient. May not generate heat.

You may mix | blend a crosslinking agent with the said resin composition which forms a planar heating element. When a cross-linking agent is added, the resin component can be cross-linked to an arbitrary degree, and the mechanical strength of the sheet heating element can be improved.

The cross-linking agent is not particularly limited as long as it is a usual compound used for cross-linking resins, and examples thereof include benzoyl peroxide, lauroyl peroxide, dicumyl peroxide, t-butyl peroxybenzoate,
Organic peroxides such as 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 are preferred.

Further, other types of thermoplastic resins, elastomers, or various additives such as antioxidants and fillers may be added to the resin composition as long as the object of the present invention is not impaired.

The resin composition can be produced by kneading a predetermined amount of the crystal biopolymer and carbon black, or the above-mentioned crosslinking agent and the like, and kneading them with a kneader.

Examples of this kneader include a pressure kneader, a twin screw kneader, an open roll for kneading, a Banbury mixer, a single screw reciprocating screw, a single screw extruder, and a twin screw extruder. The kneading temperature is selected from the temperature range from the melting point of the crystalline polymer to the thermal decomposition temperature. In this kneading, in a state in which a shearing force of 0.05 kwh / kg or more is applied to the kneaded product, a crosslinking reaction of the crystalline polymer is performed to increase the ratio of the maximum electric resistance value and the room temperature electric resistance value. It is valid. The same effect can be obtained when a shearing force is applied during the molding of this kneaded product to carry out the crosslinking reaction.

The kneaded product thus obtained is supplied to a known molding means, for example, an extruder, and molded into a heating element having an arbitrary shape that can be attached to the marker.

Examples of the shape of the heating element include a sheet shape, a film shape, a strip shape, a linear shape, a plate shape, a block shape, a tubular shape, and various irregular shapes (eg, triangle, quadrangle, star shape, etc.). . In addition, a woven or knitted linear heating element can be used as a new heating element.

The heating element is cut into a shape having an appropriate size according to the shape of the marker, or an electrode is attached to the electrode with the shape formed in the shape preset in the forming step. Lead wires are connected. If necessary, the heating element may be covered with a heat-resistant insulating film, or a heat-resistant insulating resin (such as epoxy resin).
Is coated.

The thickness of the heating element used in the present invention is not particularly limited, but it is usually within 2 mm.

Further, it is generally preferable that the size thereof is substantially the same as the size of the marking surface of the marking body described later. However, depending on the severity of the environmental temperature or other circumstances,
The area may be smaller than the labeled area. For example, it may be attached along the lower edge of the marking body.

The heating element has a good positive temperature coefficient characteristic in a low temperature region, the surface temperature of the sign body in a temperature range capable of being maintained at a temperature of about 10 to 20 ° C for melting snow or ice attached to the sign body. , The self-temperature control function can be sufficiently exerted.

-Labeled body-As the labeled body of the present invention, as long as it functions as a label,
The mode is not particularly limited, and a preferable mode is, for example, a road sign board such as a traffic sign, a guide board such as a map guide board or a tourist guide board, an advertising board or a signboard for various advertisements, such as a building roof or An example is a three-dimensional advertising body installed at a store.

Regarding the structure of the sign body, as an example, FIG. 1 shows the case where the sign body is a road sign board.

In FIG. 1, a road sign board 1 is covered with an insulating film 3 on the inner surface on the back side of a sign case 2 which is made of steel, aluminum or the like and has a sign surface on which a road sign is drawn. A rectangular heating element 4 is mounted, and the back side opening of the sign case 2 is sealed with a back plate 5 formed of a heat insulating and waterproof material. The heating element 4 which is covered with the insulating film 3 is fixed to the back surface of the sign case 1 by an appropriate means such as an adhesive or a double-sided adhesive tape.

The heating element 4 has a pair of electrodes 6 on its surface, and a lead wire 7 connected to a power source is connected to the electrodes 6.

The heat insulating / waterproof material may be made of a synthetic resin such as an epoxy resin, a urethane resin, or a silicone resin, or may be made of a foamed material thereof.

An insulating synthetic resin film is usually used for the insulating film 3. Examples of the preferable synthetic resin include polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, polyethylene and polypropylene.

Road signboards with such a configuration generate heat by heating the heating element by energizing the heating element even if snow adheres to the marking surface in cold regions. Thaw the snow immediately. As a result, the marking surface can be always exposed.

Further, since this heating element has the above-mentioned positive temperature coefficient characteristic, the amount of heat generated is constant even if the current is continuously supplied, and it does not overheat.

Since this sign does not require a thermostat or a fuse for temperature control unlike the conventional ones, it is not only easy to manufacture, but also works such as outdoor maintenance and inspection and installation are simplified.

Since the built-in heating element has a positive temperature coefficient characteristic, when the temperature rises during the daytime, the electric resistance value increases and the power consumption is reduced, which is extremely convenient in terms of energy saving.

EXAMPLES Next, the present invention will be described more specifically based on examples.

(Example 1) Ethylene-ethyl acrylate copolymer [EEA resin,
Made by Nippon Unicar Co., Ltd .: NUC-6570] 61 wt% and average particle size
30 mμ of carbon black [Mitsubishi Kasei Co., Ltd .: Diamond Black H] 39% by weight was supplied to a pressure kneader [Moriyama Mfg. Co., Ltd., volume 3], and the mixture was kneaded at 125 ° C. for 20 minutes and then pelletized. Turned into Then, to the pellets of this resin composition was added 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 in an amount corresponding to 0.3 part by weight per 100 parts by weight of the copolymer. Then, this was fed to a uniaxial sheet extruder to be crosslinked and molded into a sheet to obtain a sheet having a wall thickness of 0.5 mm. From this sheet, length 20 cm, width 2
A sheet-shaped molded product having a size of 5 cm was cut out.

A tinned flat copper braided wire (cross-sectional area 0.5 mm ² ) was attached as an electrode and lead wire to both ends of the obtained sheet-shaped molded product, and a polyethylene terephthalate single-sided adhesive film (silicone-based adhesive film) was attached to one side of the sheet-shaped molded product. The agent has been applied.), And a polyethylene terephthalate double-sided adhesive film was laminated on the other side.

Next, using this laminate as a heating element, its temperature-resistance characteristics were examined. That is, this laminate was placed in a constant temperature bath, the resistance value was measured while the temperature was gradually increased, and the rising ratio of the resistance value was determined. As a result, the resistance value at 25 ℃ is 180Ω, the ratio of the maximum resistance value and the resistance value at room temperature (25 ℃) is 10 ^4, which is 10 times the resistance value at room temperature,
That is, the temperature showing 1,800Ω was 70 ° C.

In addition, another laminated body prepared in the same manner was used, and a voltage was applied thereto, and the applied voltage was increased to measure the withstand voltage.

As a result, destruction was not achieved even when 1,000 V AC was applied.

Next, in the center of the aluminum plate (40 cm × 40 cm × 0.2 cm), another laminated body prepared in the same way was pasted with a double-sided adhesive film made of polyethylene terephthalate to make a marking plate with a heating element. It was placed in a tank, and the heating element was energized with 100 V AC, and the surface temperature of the marking plate was measured.

 The results are shown in Table 1.

After the power was turned on, neither the sign board nor the heating element showed any change in appearance.

Next, apply epoxy resin to the back surface of the heating element of this marking plate with heating element to dry it to form a heat insulating and waterproof plate, and also attach a marking film (Sumitomo 3M Scotchrate) to the surface of the heating element. Then, a labeled body was prepared.

This marker exhibits a high effect of melting snow and ice even in cold regions.

(Example 2) The same operation as in Example 1 was carried out except that 61% by weight of ethylene-vinyl acetate copolymer [Tosoh Corp .: UE634] was used as the liquid crystalline polymer to obtain a heating element. Manufactured.

The resistance value of the heating element thus obtained at 25 ° C. is 170Ω, and the ratio of the maximum resistance value to the room temperature resistance value is 10 _3.5.
Met. In addition, the resistance value (1,700
Ω) was 64 ° C.

When the withstand voltage was measured with another heating element manufactured in the same manner, it was not destroyed even when 1,000 V AC was applied.

(Comparative Example 1) 38% by weight of carbon black having an average particle size of 18 mμ [manufactured by Mitsubishi Kasei Corp .: Diamond Black A] with respect to 62% by weight of the same ethylene-ethyl acrylate copolymer as in Example 1
In the same manner as in Example 1, a heating element was obtained.

The resistance value of the heating element thus obtained at 25 ° C. is 160 Ω, and the ratio of the maximum resistance value to the room temperature resistance value is 10 _2.2.
Met. The temperature at which the resistance value was 10 times the room temperature resistance value was 76 ° C.

Next, as a result of measuring the withstand voltage with another heating element manufactured in the same manner as above, it was broken when an AC voltage of 300 V was applied.

EFFECTS OF THE INVENTION According to the present invention, since the marker is formed by using the heating element having the positive temperature coefficient characteristic in the low temperature region, the thermostat or the fuse can generate heat by controlling its own temperature even in the cold district. It is possible to provide a marker having a simple structure in which the installation of the wiring is omitted and the maintenance is easy because of the simplicity of the wiring equipment.

[Brief description of drawings]

FIG. 1 is an assembled perspective view showing an example of the marker of the present invention. 1 ... Road sign plate, 2 ... Sign case, 3 ... Insulating film, 4 ... Heating element, 5 ... Back plate, 6 ... Electrode, 7 ...
Lead.

Claims (1)

[Claims] 1. A kneaded composition of a crystalline polymer and carbon black, wherein the ratio of the maximum electric resistance value to the room temperature electric resistance value is 10 ³ or more, and the electric resistance value is 10 times the room temperature electric resistance value. A marker provided with a heating element formed of a composition having a positive temperature coefficient characteristic in which a temperature showing a resistance value is within a range of 40 to 80 ° C.