JPH0118344B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar heat collector for a water heater made of ethylene/α-olefin/polyene copolymer rubber.

BACKGROUND ART In recent years, from the perspective of saving energy and resources, there have been many attempts to install heat collectors on the roofs of houses, etc., and use solar heat to produce hot water for use in baths, space heating, hot water supply, etc. Such heat collectors, for example, have a structure in which a large number of polyethylene water pipes are arranged in the heat collecting part, and these polyethylene water pipes have weather resistance, algae prevention, and heat collection effects. Carbon black is added in an amount of 2 to 3% by weight to improve the quality. However, when using such polyethylene water pipes, there is a problem in that the innermost inner wall of the water channel that is in contact with the tap water is eroded and peeled off due to the chlorine contained as a disinfectant in the tap water. Another problem is that at the connection between a water pipe and a metal part such as a tank, even if the mold is clamped with a band, the polyethylene often creeps, causing water leakage over time, which can lead to corrosion, contamination, etc. causing problems such as

In order to address these problems, the present inventor investigated various materials and found that the innermost layer that comes into contact with tap water and forms a water passageway is an ethylene/α-olefin/polyene copolymer rubber that does not contain carbon black. The outermost layer, which is composed of vulcanizate and receives sunlight, is made of ethylene and carbon black.
The above-mentioned problems could be effectively solved by inventing a solar heat collector having a multilayer structure composed of an α-olefin/polyene copolymer rubber vulcanizate.

The present invention will be explained in detail below.

The heat collector of the present invention is used for solar water heaters,
It includes a water passage part and a heat collecting part, and includes heat collecting pipes, heat collecting plates, etc., and is not limited in shape. Figure 1 shows one of the heat collecting pipes (water supply pipes, water conduction pipes) consisting of the innermost layer 2 and the outermost layer 3 that are in contact with the water passage 1.
An example was given. FIG. 2 also shows an example of the heat collecting plate.

In the present invention, both the innermost layer and the outermost layer are ethylene/α
- Consists of a vulcanized product of olefin/polyene copolymer rubber.

The α-olefin components of this copolymer rubber include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-tetradecene, 1-octadecene, etc. Propylene is particularly preferred.

Further, the polyene components of the copolymer rubber of the present invention include 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, and 7-methyl-1. ,
Chain nonconjugated dienes such as 6-octadiene, cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2- norbornene, 6-chloromethyl-5-
Cyclic non-conjugated dienes such as isopropenyl-2-norbornene, 2,3-diisopropylidene-5-
Norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-
Typical examples include trienes such as 2,2-norbornadiene, 1,3,7-octatriene, and 1,4,9-decatriene.
-Hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene and the like are preferred.

The copolymer rubber of the present invention has a molar ratio of ethylene units to α-olefin units of about 60/40 to 85/
15. Iodine value as a guide for polyene unit content is approximately 3-30, Mooney viscosity as a guide for molecular weight
Preferably, the ML ₁₊₄ (at 100°C) is about 20 to 120.

Of course, the copolymer rubber used for the outermost layer and the copolymer rubber used for the innermost layer may be the same or different.

Vulcanizing agents used to vulcanize such copolymer rubber include sulfur; sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, selenium dimethyldithiocarbamate. Sulfur-based compounds such as dicumyl peroxide, 2,
5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy) ) Organic peroxides such as hexyne-3, di-tert-butyl peroxide, di-tert-butyl peroxy-3,3,5-trimethylcyclohexane, and tert-butyl hydroperoxide can be mentioned. Among them, sulfur and organic peroxides are preferably used, especially sulfur, dicumyl peroxide, ditert-butyl peroxide, ditert-butyl peroxide-3, 3, 5
-Trimethylcyclohexane is preferred.

Sulfur is usually 0.1 per 100 parts by weight of copolymer rubber.
It is used in a proportion of from 10 to 10 parts by weight, preferably from 0.5 to 5 parts by weight. The organic peroxide is usually 0.1 to 15 parts by weight per 100 parts by weight of the copolymer rubber.
It is preferably used in a proportion of 0.5 to 8 parts by weight.

Further, when sulfur or a sulfur-based compound is used as a vulcanizing agent, a vulcanization accelerator and a vulcanization aid are used in combination, if necessary.

As a vulcanization accelerator, N-cyclohexyl-2
-Benzothiazole-sulfenamide, N-oxydiethylene-2-benzothiazole-sulfenamide, N,N-diisopropyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole, 2-(2,4-dinitrophenyl)mercaptobenzothiazole ,2-(2,
Thiazoles such as 6-diethyl-4-morpholinothio)benzothiazole and dibenzothiazyl-disulfide; guanidines such as diphenylguanidine, triphenylguanidine, diorthotolylguanidine, orthotolyl biguanide, and diphenylguanidine phthalate ; acetaldehyde-aniline reaction product, butyraldehyde-aniline condensate, hexamethylenetetramine,
Aldehyde amine or aldehyde-ammonia type such as acetaldehyde ammonia; imidazoline type such as 2-mercaptoimidazoline; thiourea type such as thiocarbanilide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea; tetramethylthiuram monosulfate Thiuram-based compounds such as hydrofluoride, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide; zinc dimethyldithiocarbamate, zinc diethylthiocarbamate, di-n- Zinc butylphenyl dithiocarbamate, zinc ethyl phenyl dithiocarbamate, zinc butylphenyl dithiocarbamate, sodium dimethyl dithiocarbamate,
Examples include dithiocarbamate salts such as selenium dimethyldithiocarbamate and tellurium diethyldithiocarbamate; xanthate salts such as zinc dibutylxanthate; and the like. These vulcanization accelerators are used in an amount of 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the copolymer rubber.

Examples of the vulcanization aid include metal oxides such as magnesium oxide and zinc white, but it is preferable to use zinc white. Usually, these vulcanization aids are used in an amount of 3 to 20 parts by weight per 100 parts by weight of the copolymer rubber.

In addition, when crosslinking with peroxide, sulfur, P
- Quinone dioximes such as quinone dioxime,
A methacrylate type such as polyethylene glycol dimethacrylate, an allyl type such as diallyl phthalate and triallyl cyanurate, other crosslinking aids such as maleimide type and divinylbenzene may be used.

However, when vulcanizing the copolymer rubber of the innermost layer, sulfur is used as the vulcanizing agent from the viewpoint of hygiene, and thiuram-based and dithiocarbamate-based vulcanization accelerators are used, or organic peroxide is used as the vulcanizing agent. It is preferable to use a methacrylate-based crosslinking agent as a crosslinking aid.

In the present invention, carbon black is blended into the outermost layer. Carbon black includes SRF, GPF,
There are various types such as FEF, HAF, ISAF, SAF, FT, and MT, and any of them can be used. These carbon blacks are usually made from copolymer rubber 100%
About 5 to 150 parts by weight are blended.

Carbon black is not added to the innermost layer. If carbon black is added, the chlorine water resistance will be inferior. Note that white fillers such as silica, clay, talc, and calcium carbonate can be optionally added to the innermost layer for reinforcing purposes.
From the viewpoint of hygiene, it is preferable to use silica or clay, if it is not added at all or if it is added.

In the present invention, in both the outermost layer and the innermost layer,
A softener can be added as an optional component to improve processability and to impart flexibility to the heat collector. Examples of softeners that can be used include process oils, lubricating oils, paraffin, liquid paraffin, and vaseline.

In molding the heat collector of the present invention, an unvulcanized compounded rubber is once produced. For example, use a mixer such as a Banbury mixer at 90 to 150℃.
After kneading the copolymer rubber, filler, softener, etc. for about 4 to 10 minutes, using rolls such as oven rolls, roll temperature is 40 to 100℃.
A vulcanizing agent and, if necessary, a vulcanization accelerator or vulcanization aid are further mixed at a temperature of

The heat collector of the present invention is produced from the unvulcanized compounded rubber thus prepared by the following method. For example, in the case of a double-layered rubber tube, (a) the inner layer is extruded using an extruder and then vulcanized, the resulting inner layer rubber tube is coated with the outer layer using an extruder, and the outer layer is vulcanized to form a double-layered rubber tube. (b) Using two extruders, the outer layer is extruded and coated at the same time as the inner layer to obtain a double-structured rubber tube. (c) The inner layer and outer layer are separately formed. It is manufactured by extrusion vulcanization and inserting the inner layer into the resulting outer layer to obtain a double-layered rubber tube.

In addition to the double structure, the multilayer structure may include a cloth sandwiched between the inner layer and the outer layer to increase pressure resistance.

This will be explained below using examples.

Examples 1 and 2 and Comparative Examples 1 and 2 As the copolymer rubber used for the inner layer portion, those having the compositions shown in Table 1 were used. The copolymer rubber used for the outer layer had the following composition.

EPDM ⁽¹⁾ 100 parts by weight Zinc white 5 parts by weight Stearic acid 1 part by weight Carbon black 120 parts by weight Calcium oxide (defoaming agent) 10 parts by weight Naphthenic oil 70 parts by weight Vulcanization accelerator MBT ⁽²⁾ 1.0 parts by weight Vulcanization Sulfur accelerator ZnBDC ⁽³⁾ 1.0 parts by weight Vulcanization accelerator TMTD ⁽⁴⁾ 0.5 parts by weight Sulfur 1.5 parts by weight Note (1): The molar ratio of ethylene units and propylene units is
71/29, iodination 14, Mooney viscosity
Ethylene-propylene-ethylidenenorbornene copolymer rubber with ML ₁₊₄ (100℃) of 85 (2): Mercaptobenzothiazole (3): Zinc n-butyldithiocarbamate (4): Tetramethylthiuram disulfide Inner layer extrusion For use, a rubber extruder with a deaerator is used.
For extrusion of the outer layer, a general rubber extruder was used to extrude the inner layer and the outer layer at the same time, and the outer layer was coated on the inner layer. Inner layer thickness 0.2mm, outer layer thickness 0.8mm, outer diameter
It was set to 10mm. Then put it in a hot air vulcanization tank and heat it at 200℃.
The vulcanization operation was performed for 10 minutes. The resulting double-structured rubber tube was tested for chlorine water resistance and water leakage.
The results are shown in the table.

Chlorine water resistance was determined by cutting the above rubber tube into a length of 50 mm and dividing the sample into two vertically.
The pipe was immersed in 0.1% by weight chlorine water at 60°C for 3 weeks, and the peeling condition on the inner surface of the pipe was observed.

Also, regarding the presence or absence of water leakage, as shown in Figure 3,
Steel pipe 6 (outer diameter 8 mm) with pressure gauge 4 and valve 5
Attach the previously formed test object (rubber double tube, PE single layer tube) 7 to the tube, and tighten it to 10 kg cm with a 5 mm wide metal band 8 using a torque wrench. Insert the blank 9 into the other end of the test object 7 and tighten it to 10 kg/cm.

Then, pour hot water at a pressure of 3 Kg/cm ² G and 70°C into the injection port 1.
Inject from 0 and close the valve.

Furthermore, the entire rubber double tube and PE single layer tube 7 are immersed in hot water at 70°C, and the magnitude of the pressure drop is observed for two weeks.

The length of the test object shall be 200mm.

Comparative example 3 Melt index (190℃) 0.15, density 0.952
When a water leakage test was conducted on a pipe made of high-density polyethylene having the same shape as the double pipe of Example 1, the reading on the pressure gauge was zero after two weeks.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a heat collecting tube, and FIG. 2 is a perspective view of a heat collecting plate. FIG. 3 is an explanatory diagram of the water leak test method. 1... Water passageway, 2... Innermost layer, 3... Outermost layer,
4...Pressure gauge, 5...Valve, 6...Steel pipe, 7...
... Test object, 8 ... Metal band, 9 ... Blind,
10... Inlet.

【table】

Claims (1)

[Claims] 1. In a solar heat collector, the innermost layer of the water passage is
Made of ethylene/α-olefin/polyene copolymer vulcanizate without carbon black,
A solar heat collector characterized by having a multilayer structure in which the outermost layer that receives sunlight is made of ethylene/α-olefin/polyene copolymer rubber vulcanizate mixed with carbon black. 2. The solar heat collector according to claim 1, wherein the α-olefin is propylene. 3. The solar heat collector according to claim 1, wherein the heat collector is a heat collection tube. 4. The solar heat collector according to claim 1, wherein the heat collector is a heat collection plate. 5 Multi-layered structure with cloth sandwiched between the inner layer and outer layer 3
The solar heat collector according to claim 1, which has a layered structure.