JPH10273148A - Electric water-heating appliance made of plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the small of a raw material at the time of manufacture to improve working environments by forming a plastic electric water-heating appliance of three layers including an innermost first layer of a thermoplastic resin layer, a second layer external thereto of a thermoplastic resin layer containing continuous long fibers and a third layer of a foaming heatinsulating layer. SOLUTION: A laminated container of a plastic electric water-heating appliance incorporating a sheath heater is formed by laminating, from inner to outer layers, a first layer 6, a second layer 7 and a third layer 8. A thermoplastic resin layer used in the first layer 6 is of a heat distortion temperature of 110 deg.C or higher, preferably one kind selected from polyethylene, crosslinked polyethylene, etc., for use. The second layer 7 which is a reinforcing layer comprises composite resin containing continuous long fibers, wherein used long fibers are selected among glass fibers, carbon fibers, silicon carbonate fibers, etc. The third layer 8 is a heat-insulating material layer, wherein a foaming mold is used for this and polyisocyanurate is preferably used for cast-foaming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic electric water heater used for home use or the like.

[0002]

2. Description of the Related Art Conventionally, an electric water heater is made of steel and is manufactured by welding from a flat plate, so that intergranular corrosion in a welded portion is apt to occur during long-term use, and the electric water between a copper heater and stainless steel is used. There is a problem that corrosion is likely to occur, and this has been solved by adopting ferritic stainless steel, but it is still insufficient. In addition, since it is a metal, it has a disadvantage in that it has no resilience when deformed, and remains deformed particularly when a negative pressure is applied when the water heater is used. Further, there is a limit to increasing the welding speed in tank production, and there is an economic problem that productivity is low and production cost is high. Further, since a metal having good heat conductivity is used, it is protected by a heat insulating material, but has insufficient heat retention, and has a disadvantage that the temperature is easily lowered during hot water storage and use, thereby increasing operating costs.

As a plastic electric water heater, a heater is provided in a laminated container in which a first layer is made of a thermoplastic resin, a second layer is made of a thermosetting resin reinforced by glass fiber, and a third layer is made of a heat insulating material layer. Installed electric water heater is extraordinary 6
-105119. As the thermosetting resin, unsaturated polyester, epoxy resin, and the like are known, and when a water heater is manufactured by using these to produce glass fiber reinforced filament winding, the raw material being manufactured has a strong smell, and the working environment is reduced. However, there is an economic problem that it is necessary to install an exhaust device to improve the environment and a curing furnace is required to completely cure the resin.

[0004]

The object of the present invention is to improve the corrosion resistance, the resistance to negative pressure, the heat retention and the reduction of the production cost, which are the problems of the metal water heater, and to remove the odor of the raw material during the production of the plastic container. The goal is to improve the environment.

[0005]

According to the present invention, a laminated container of a plastic electric water heater is formed of at least three layers from an inner layer to an outer layer, and a first innermost layer is a thermoplastic resin layer, The outer second layer is formed of a thermoplastic electric water heater formed of a thermoplastic resin layer containing continuous filaments, and the third layer is formed of a plastic electric water heater formed of a foamed heat insulating layer. It is composed of a plastic electric water heater having a softening preventing material layer provided as an intermediate layer. In that case, as the first layer, a thermoplastic resin having a heat deformation temperature of 110 ° C. or more is used, and as the thermoplastic resin of the first layer, at least one selected from the group consisting of polyethylene, cross-linked polyethylene, polypropylene, and polybutylene is used. .

[0006] As the continuous long fiber of the second layer, at least one selected from the group consisting of glass fiber, carbon fiber, silicon carbide fiber, and wholly aromatic polyamide fiber is used.
At least one selected from the group consisting of polypropylene, polybutylene, polyamide, and polyester is used as the thermoplastic resin of the second layer.

[0007] When the third heat insulating material layer is made of polyurethane and an intermediate layer is used between the first and second layers, the softening material used as the softening material layer has a melting point of 1%.
A thermoplastic resin having a temperature of 30 ° C. or higher is used, and as the softening preventing material, specifically, at least one selected from the group consisting of polyester, crosslinked polyethylene, and polyvinyl chloride is used.

Further, an outer tank made of a thermoplastic resin is used outside the laminated container, and specifically, polyethylene is used. The present invention is configured as described above.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of a plastic electric water heater used in the present invention, a laminated container 1 shown in FIG.
As shown in FIGS. 2 and 3, the container is composed of a number of layers, a sheathed heater 2 is provided in a laminated container 1, and a water supply pipe 3 is suspended from above. And a hot water supply pipe 4 and a drainage pipe 5
Are mounted on the upper and lower sides, respectively.

The present invention relates to such an electric water heater, and in particular, has a feature in a laminated material constituting the laminated container 1. Specifically, the laminated container is formed from a layer having a cross section as shown in FIGS. And has the following general configuration.
The laminated container 1 of the present invention includes a first embodiment including a first layer, a second layer, and a third layer from an inner layer to an outer layer,
It comprises a second embodiment consisting of a layer, an intermediate layer, a second layer, and a third layer. An outer container 9 is provided on the outermost side of the laminated container 1 as required.

As described above, the laminated containers of the plastic electric water heater of the present invention are made of the following materials, respectively. The thermoplastic resin layer used for the first layer in direct contact with the warm water is:
It has a heat deformation temperature of 110 ° C. or more according to JIS K7207. The hot water storage temperature of the electric water heater is 85 ° C., and it is desirable that the electric water heater has the above-mentioned heat deformation temperature in order to withstand boiling at an abnormal time. It is desirable that the resin has a relatively high tensile yield point elongation or a material which exhibits little yield point and shows large elongation until breakage. When deformed by negative pressure, a brittle material with small elongation may generate cracks when deformed, so a thermoplastic resin having the above properties is
It has resilience to deformation due to repeated negative pressure. Among the thermoplastic resins, a resin that is hydrolyzed by hot water or swells when supplied with water, and a resin that is affected by chlorine, fluorine, or the like, which is a germicide in water, is not used in the water heater of the present invention. In addition, toxic substances that dissolve and dissolve in water cannot be used. As thermoplastic resins meeting these conditions, polyethylene, especially high-density polyethylene, cross-linked polyethylene, polypropylene, polyolefins such as polybutylene, modified polyphenylene ether,
Engineering plastics such as nylon 610, polyarylate, a blend of modified polyphenylene ether and nylon 6, are preferred. The tank for forming the first layer is formed by either blow molding or rotational molding. Among them, polyolefin, modified polyphenylene ether and a nylon blend thereof are preferably used from the viewpoint of blow moldability at the time of tank molding. Crosslinked polyethylene and polybutylene are particularly preferably used from the viewpoint of restorability at the time of deformation.

When the water heater is used, the first layer has a thickness of 0.85 kgf /
A ^second layer, which is a reinforcing material layer, is provided in order to maintain pressure resistance when heated with water filled with cm ² pressure. The long fiber used in the composite resin containing the continuous long fiber used in the second layer is selected from glass fiber, carbon fiber, silicon carbide fiber, and wholly aromatic polyamide. As the glass fiber, a so-called E glass long fiber produced from borosilicate containing 1% of an alkali component is preferably used. As the carbon fiber, any one of acrylic fiber, pitch, rayon and lignin can be used, but a fiber having a higher tensile modulus is preferably used. The silicon carbide fibers include not only silicon carbide fibers made of dimethyldichlorosilane as a raw material, but also tyrano fibers obtained by reacting titanium. Since these have higher strength than carbon fibers, they can be made thinner. Aromatic polyamide fibers are so-called aramid fibers, homopolymers,
Although it is also used as a copolymer, poly-para-phenylene-terephthalamide, which is a para-type homopolymer, is preferably used because of its high elastic modulus and excellent heat resistance.

The thermoplastic resin of the tape, which is a matrix reinforced and reinforced by continuously orienting these fibers without cutting them in the longitudinal direction, is preferably polyethylene, polypropylene, polybutylene, polyamide or polyester. Fiber blending ratio is 50% by volume
Can be compounded. The first layer and the second layer are laminated by thermal fusion using a filament winding machine,
In order to improve the adhesion between the two, it is desirable that the matrix resin of the first layer and the matrix resin of the second layer are the same, and polybutylene and polyethylene are preferably used. However, moderate viscosity is required for the production of tapes that orient long fibers in high concentrations,
Since polypropylene and polyamide are suitable, these resins are often used practically.

When the first layer is a low-melting-point resin and the second layer is a high-melting-point resin, polyester,
First, use a shrink film or stretch film made of cross-linked polyethylene or polyvinyl chloride.
The container of the layers can be wrapped and then protected from softening by filament winding.

[0015] A third method for imparting heat retention to the electric water heater.
As the heat insulating material layer, a foam molded product is used. The thermal insulation layer should have as low a thermal conductivity as possible and be able to withstand the compressive stresses on the thermal insulation when the electric water heater is filled with water. Cast foaming is most desirable for providing a foamed heat insulating material layer in the first and second laminated tanks. Cast foams include polyurethane, phenol-aldehyde, urea-formaldehyde, melamine-formaldehyde, silicone, epoxy, unsaturated polyester foam and the like. Both polyurethane and polyisocyanurate are preferably used because they have very low thermal conductivity and are excellent in heat resistance at 85 ° C. during use. Polyisocyanurate is most preferably used because it imparts flame retardancy in addition to heat insulation and heat resistance.

When the electric water heater is installed outdoors, an exterior tank made of a thermoplastic resin having a higher impact resistance is used as an exterior for beautiful appearance, impact resistance due to flying objects, measures against earthquakes, maintenance of weather resistance, and the like. Can be provided. As the thermoplastic resin, polyethylene, polybutylene, polyolefin of polypropylene, copolymer of ethylene and vinyl acetate, acrylic acid, methyl methacrylate, and the like are preferable.
As the molding of the outer tank, any of a hollow molding method and a rotational molding method is used. In the hollow molding, high-density polyethylene and low-density polyethylene are preferably used. High-molecular-weight, high-density polyethylene is particularly preferably used for forming a water heater having a large full capacity. In rotational molding, linear low-density polyethylene is preferably used.

A method of mounting a heater as a means for heating water is as follows. An opening is provided in a laminate composed of the thermoplastic resin and the reinforced thermoplastic resin, and a control unit including a heater and an overheat prevention device is provided. A method in which a heating unit is separately provided and heated water is sent to a water heater may be adopted. As the heater, a sheath heater, a ceramic heater, or the like is preferably used.

The present invention also relates to a first layer for preventing the thermoplastic resin from being deformed by softening when the thermoplastic resin as the first layer and the thermoplastic resin reinforced by the continuous long fibers by the second layer are multilayered by heating. Anti-softening layer 1 as an intermediate layer between
0 was provided. [Examples] The results of the examples are as shown in Table 1.

[0019]

[Table 1]

The materials, molding methods, and performance evaluation methods used in the examples are shown below. Materials 1st layer Polybutylene and cross-linked polyethylene 2nd layer Tape in which glass fiber, carbon fiber, and Tyranno fiber are impregnated with PP and PA6 matrices by 50% by volume, respectively. 1150 tex.

Third layer Polyurethane exterior tank High-density polyethylene heater Seeds heater 4.4 KW Molding method First layer Blow molding method, 380 liter tank molding Second layer The above-mentioned material tape is wound around the first layer tank by filament winding method.

The tape is preheated and molded by a gas burner. PA
In the case of winding a 6 matrix tape, a shrink film was wound in advance in a first layer tank as a softening preventive material and then wound. Helical 4-ply, hoop 2-ply winding. In the filament winding with the thermosetting resin in the comparative example, the glass fiber was continuously wound while passing through a tank filled with unsaturated polyester. The number of turns was helical 4 plies and hoop 2 plies as in the example. After the tank was formed, it was cured by heat treatment in a curing oven at 65 ° C.

Third layer Polydiphenylmethane diisocyanate (MDI) and a polyol containing a foaming agent are mixed and injected into a mold in a high-pressure foaming machine. Exterior tank Blow molding method Electric water heater assembly First and second layers laminated by filament winding
An opening was opened in the tank composed of layers, a sheath heater and a control unit were attached, and a third layer or an outer tank was assembled to obtain a water heater. Performance evaluation Pressure test: 1.0 kg in a water heater heated to 85 ° C
Pressure was applied at a rate of f / cm ² / min, and the pressure at which breakage occurred was measured.

Cycle test: 0 to 10 kgf / cm at 1.5 kgf / cm ² / sec in a water heater heated to 85 ° C.
100,00 cycle test with repeated pressure up to ²
Performed 0 times and checked for water leaks. Hot water sampling test: After the temperature reached 85 ° C according to JIS C9219 to evaluate the heat retention, the power was turned off and left for 13 hours.
The hot water was continuously taken and the temperature of the hot water corresponding to 1/2 of the capacity was measured, and the difference from 85 ° C. was shown.

Negative pressure test: After filling with water, all valves were closed, and water was discharged at a head pressure of the product level to make a negative pressure state. Then, deformation of the tank was observed. Chlorine water test: Chlorine concentration 3 using sodium hypochlorite
95 ° C for promotion while replenishing water adjusted to ~ 5ppm
The water was stored for six months and the surface condition of the tank was observed. Examples 1 to 4 and Comparative Examples 1 and 2 Examples 1 to 3 show examples in which the first layer was made of polybutylene and the second layer was replaced with reinforcing fibers impregnated with a polypropylene matrix. Shows an example of a stainless steel tank.

All of the examples were not deformed by the cycle test and the negative pressure test. The thing of a comparative example has leaked or deformed. In the hot water sampling test showing the heat retention, the temperature difference between the comparative example and the set temperature is smaller in the example. The pressure resistance of the example was large, and particularly the examples 2 and 3 had sufficient pressure resistance.

Comparative Example 2 shows the result of filament winding with unsaturated polyester using glass fiber for the second layer. This had an emission of styrene in the environment, but no outgassing was observed for the example.

Example 4 shows the case where the first layer was changed to crosslinked polyethylene. This product also did not deform, had excellent heat retention, and did not release gas to the environment. [Examples 5 to 7 and Comparative Examples 1 and 2] In Examples 5 to 7, glass fiber reinforced polyamide 6 matrix was used for the second layer, and no intermediate layer, polyethylene terephthalate shrink film, and cross-linked polyethylene shrink film were used. The ones wound on one layer and then tape-winded are shown. Each of the examples has a sufficient pressure resistance of 20 kg or more, and has not been deformed in the cycle test and the negative pressure test. It can withstand the chlorine water test. There is no outgassing to the environment. In the case of Example 5, the glass fiber was immersed in the first ply in contact with the surface layer of the polybutylene tank during filament winding, but did not affect practical strength, deformation, and the like. Examples 6 and 7 in which shrink wrapping was performed did not have this phenomenon and could be molded. Comparative Example 1 had water leakage during the cycle test and deformation in the negative pressure test, and Comparative Example 2 had gas released to the environment.

[0029]

According to the present invention, it is possible to provide an inexpensive plastic electric water heater which is energy-saving because of its excellent heat retaining property, is excellent in negative pressure resistance, is hardly corroded, and is inexpensive. It is possible to obtain a plastic electric water heater which has no odor of the raw material during production and does not require an exhaust device.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a plastic electric water heater of the present invention.

FIG. 2 is a partial cross-sectional view of the laminated container according to one embodiment of the present invention.

FIG. 3 is a partial sectional view of a laminated container according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Laminated container 6 1st layer (thermoplastic resin layer) 7 2nd layer (thermoplastic resin layer containing continuous long fiber) 8 3rd layer (heat insulation layer material) 9 Outer tank 10 Intermediate layer (softening prevention material layer)

Claims (11)

[Claims] 1. A laminated container of a plastic electric water heater is formed of at least three layers from an inner layer to an outer layer, a first innermost layer being a thermoplastic resin layer, and an outer second layer being a continuous layer. A plastic electric water heater comprising a thermoplastic resin layer containing long fibers, and a third layer formed of a heat insulating material layer. 2. A laminated container for a plastic electric water heater comprising at least four layers from the inner layer to the outer layer, wherein the first innermost layer is a thermoplastic resin layer and the outer second layer is continuous. A plastic electric water heater formed of a thermoplastic resin layer containing long fibers, then formed of a third layer of a heat insulating material, and further provided with a softening preventing layer as an intermediate layer between the first and second layers. . 3. The plastic electric water heater according to claim 1, wherein a thermoplastic resin layer having a heat deformation temperature of 110 ° C. or higher is used as the first layer. 4. The plastic electric water heater according to claim 1, wherein at least one selected from the group consisting of polyethylene, cross-linked polyethylene, polypropylene, and polybutylene is used as the thermoplastic resin of the first layer. 5. The continuous long fiber uses at least one selected from the group consisting of glass fiber, carbon fiber, silicon carbide fiber, and wholly aromatic polyamide fiber.
A plastic electric water heater according to claim 1. 6. The plastic electric water heater according to claim 1, wherein at least one selected from the group consisting of polypropylene, polybutylene, polyamide, and polyester is used as the thermoplastic resin of the second layer. 7. The plastic electric water heater according to claim 1, wherein the third heat insulating material layer is made of polyurethane. 8. The plastic material according to claim 2, wherein a thermoplastic resin having a melting point of 130 ° C. or more is used for the softening preventing material used for the softening preventing material layer as the intermediate layer. Electric water heater. 9. The softening-preventing material used in the softening-preventing material layer as an intermediate layer is at least one selected from the group consisting of polyester, cross-linked polyethylene, and polyvinyl chloride. The plastic electric water heater according to 6, 7, or 8. 10. The method according to claim 1, wherein an outer tank made of a thermoplastic resin is used outside the laminated container.
10. The plastic electric water heater according to 7, 8, or 9. 11. The method according to claim 1, wherein an outer tank made of polyethylene is used outside the laminated container.
The plastic electric water heater according to 7, 8, 9 or 10.