JP6573190B2 - Hot water supply hose - Google Patents

Description

  The present invention relates to a resin hose for housing equipment, and more particularly to a water supply hot water supply hose that is used for a housing water supply pipe and the like and is also suitable for transporting hot water.

  Conventionally, metal hoses have been used for residential water supply facilities and hot water supply facilities, but resin hoses have been used in recent years from the viewpoints of workability and prevention of rust. Such a hose is composed of a plurality of layers, and is easily deteriorated because the inner layer comes into contact with cold water or hot water. Then, the hose which suppresses deterioration of an inner layer is proposed (refer patent documents 1-3).

  For example, the hose of Patent Document 1 is composed of an inner layer tube composed of an inner layer and an outer layer and a reinforcing layer on the outer side thereof, and different anti-aging agents are contained in the inner layer and the outer layer, respectively. By using a different anti-aging agent, it is possible to promote the diffusion of the anti-aging agent of the outer layer to the inner layer side, so that deterioration of the inner layer can be effectively prevented.

  Further, in Patent Document 2, in a multilayer resin pipe composed of two or more layers, the outer layer contains an oxidation degradation inhibitor in an amount of 1.5 times or more of the oxidation degradation inhibitor contained in the innermost layer. By the said mixing | blending, the oxidative degradation inhibitor of an outer layer can be gradually moved to an innermost layer. In addition, a hindered phenol compound and a hindered amine compound are used as an oxidative degradation inhibitor.

  Furthermore, in patent document 3, in the hot-water supply hot water hose which consists of multiple layers, the outer layer provided on the innermost layer contains multiple types of hindered phenol-based oxidative degradation inhibitors.

Japanese Patent No. 4280281 JP-A-9-170684 Patent No. 5050422

  In the housing market, there is a demand for further long-term compensation of the housing itself, and along with this, there is a demand for extending the life of a hot water supply hot water hose that forms part of the housing. Therefore, it is desirable to provide a hose having a longer life by improving the above-described deterioration resistance of the hose.

  Therefore, an object of the present invention is to provide a hot water / hot water hose having a longer life than that of the prior art.

  The water / hot water supply hose of the present invention includes an inner layer made of crosslinked polyethylene and an outer layer made of a thermoplastic elastomer provided on the outer side of the inner layer, and a phenolic antioxidant and a phosphorus antioxidant in the outer layer. And the content of the phosphorous antioxidant in the outer layer is 2.0 wt% or more.

  According to the present invention, by using a phenolic antioxidant and a phosphorus antioxidant and setting the phosphorus antioxidant to the above content, the outer layer antioxidant is delayed from moving to the inner layer. Can do. Thereby, since an antioxidant can be made to exist in an outer layer and an inner layer over a long period of time, the progress of the oxidation deterioration cycle which could not be suppressed conventionally can be suppressed. As a result, since deterioration of the inner layer and the outer layer can be suppressed, a hose having a longer life than the conventional one can be obtained.

In addition, the phenolic antioxidant in the outer layer is composed of two types of antioxidants having different molecular weights, and the content of the first antioxidant having a large molecular weight among the two types of antioxidants is the second oxidation having a small molecular weight. It has multi than the content of the inhibitor. Since the first antioxidant having a large molecular weight is less likely to pass through the outer layer than the second antioxidant having a small molecular weight, the content of the first antioxidant prevents the first antioxidant in the outer layer from moving to the inner layer. Can be slower. Thereby, since a 1st antioxidant can be made to exist over a long period of time in an outer layer and an inner layer, degradation of an outer layer and an inner layer can be suppressed effectively.

Furthermore, the molecular weight of the phosphorus-based antioxidant in the outer layer, by greater than the molecular weight of the second antioxidant, born the effect of steric hindrance caused by the molecular size is large (movement restraining), antioxidant in the outer layer The agent can be further delayed from moving to the inner layer. Thereby, deterioration of an outer layer and an inner layer can be suppressed more effectively.

  Moreover, it is preferable that content of the said 1st antioxidant in an outer layer is 2.0 wt% or more, and content of the said 2nd antioxidant is 1.0 wt% or more. By setting it as the said content, since it can further slow down that the 1st antioxidant in an outer layer moves to an inner layer, deterioration of an outer layer and an inner layer can be suppressed more effectively.

  According to the present invention, the antioxidant of the outer layer can be moved to the inner layer more slowly than before, so that the antioxidant can be present in the outer layer and the inner layer for a long time. Thereby, since the progress of the oxidation deterioration cycle which could not be suppressed in the past can be suppressed, a hot water / hot water supply hose having a longer life than the conventional one can be obtained.

It is a perspective view which shows the structure of the water supply hot-water supply hose which concerns on embodiment of this invention. It is a schematic diagram which shows the mechanism of the oxidative degradation of the resin material. It is structural formula of the phenolic antioxidant and phosphorus antioxidant which were illustrated by embodiment of this invention. It is a figure which shows the result (relationship between test time and inner layer thickness) by a chlorine circulation test. It is a schematic diagram explaining the movement of antioxidant. It is a structural formula of the phosphorus antioxidant used in the Example and the comparative example. It is a structural formula of the phosphorus antioxidant used in the Example.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  Here, the water supply hot water supply hose which is one Embodiment of this invention is demonstrated below, referring FIGS.

(Water supply hot water hose)
As shown in FIG. 1, the hot water supply / hot water hose 1 includes an inner surface layer tube 2 composed of an inner layer 2 a and an outer layer 2 b, a reinforcing layer 3 formed around the outer layer of the inner surface layer tube 2, and an outer surface covered with the reinforcing layer 3. And a resin layer 4. The inner layer 2a of the inner surface layer tube 2 is made of a crosslinked polyethylene resin, and the outer layer 2b is made of a thermoplastic elastomer having flexibility. The outer layer 2b contains an antioxidant. Details of the inner layer 2a and the outer layer 2b will be described later.

(Reinforcing layer)
The reinforcing layer 3 has an inner reinforcing layer 3a and an outer reinforcing layer 3b. The inner reinforcing layer 3a is formed by winding a plurality of reinforcing yarns so as to intersect the outer peripheral surface of the inner surface layer tube 2 while being knitted. As the reinforcing yarn, it is preferable to use a twisted yarn of a plurality of nylon yarns for strength. The outer reinforcing layer 3b is formed by winding a stainless steel wire that is aligned and woven while intersecting the outer peripheral surface of the inner reinforcing layer 3a. Therefore, the outer reinforcing layer 3b has high strength and rust resistance.

(Outside resin layer)
The outer surface resin layer 4 is a resin layer that protects the outer surface of the water / hot water supply hose 1. Although the material of the outer surface resin layer 4 is not particularly limited, for example, it can be formed by covering the outer peripheral surface of the reinforcing layer 3 with polypropylene or urethane-based thermoplastic elastomer.

  Next, the inner layer 2a and the outer layer 2b constituting the inner surface layer tube 2 will be described in detail.

(Inner layer tube)
<Inner layer>
The cross-linked polyethylene resin constituting the inner layer 2a is obtained by adding a cross-linking agent to reactive polyethylene (PE) and melt-extruding it. The cross-linked polyethylene resin is an ultra-high molecular weight polyethylene having a three-dimensional network structure obtained by bonding portions of chain-structured polyethylene as a thermoplastic plastic. Therefore, when the crosslinking reaction is completed, the polyethylene has a three-dimensional network structure like a thermosetting resin and is excellent in heat aging resistance, chemical resistance, environmental stress cracking performance and creep performance.

  Such a cross-linked polyethylene resin exhibits excellent characteristics in terms of water quality retention and food sanitation due to its excellent chemical stability, and therefore, the water and hot water supply hose 1 can be used as a piping material for drinking water. In addition, the inner layer 2a has not only the chlorine resistance against residual chlorine of sodium hypochlorite contained in tap water, but also a large elongation below freezing point and a good freeze resistance.

  The thickness of the inner layer 2a is preferably 0.1 to 1.0 mm, and more preferably 0.2 to 0.8 mm. This is because the hot and cold water supply hose 1 can be used for a long time in a wide temperature range from room temperature to 95 ° C. If the thickness is less than 0.1, the extrusion process is difficult to perform smoothly, and even if it can be molded into a tube shape, the chlorine resistance against sodium hypochlorite contained in tap water tends to be poor. If the thickness exceeds 1.0 mm, the moldability is likely to deteriorate, and the inner layer tube 2 becomes hard, so that flexibility as a water supply hot water supply hose is easily lost.

<Outer layer>
The thermoplastic elastomer constituting the outer layer 2b of the inner surface layer tube 2 includes the elastomers exemplified in Table 1 below, that is, polyurethane-based thermoplastic elastomer (TPU), polyolefin-based thermoplastic elastomer (TPO), polystyrene-based thermoplastic. Elastomer (TPS), polyester-based thermoplastic elastomer (TPEE), vinyl chloride-based thermoplastic elastomer (TPVC), polyamide-based thermoplastic elastomer (TPAE), and the like can be used.

  Such a thermoplastic elastomer has both the characteristics of a crosslinked elastomer and the processability of the plastic. That is, a thermoplastic elastomer is a rubber elastic body that melts when heated and hardens when cooled. A molded product made of a thermoplastic elastomer exhibits useful properties such as shape retention at high temperature, elastic deformation during stretching and compression, and the like.

  According to the theory of elastomers, the polymer chain of a thermoplastic elastomer includes two types of units or segments. This segment is either a soft segment (soft part) or a hard segment (hard part). It may be. Here, the soft segment exhibits fluidity in an amorphous state above the glass transition temperature. In addition, the hard segment is solid in the operating temperature range and fixes the arrangement of the polymer chains (physical crosslinking). However, at high temperatures, the physical bond is dissociated, and under the same stress as normal thermoplastic To flow.

  Next, the antioxidant contained in the outer layer 2b will be described.

  The outer layer 2b contains a phenol-based antioxidant and a phosphorus-based antioxidant. Moreover, a phenolic antioxidant consists of two types of antioxidants from which molecular weight differs. The content of the phosphorus antioxidant in the outer layer 2b is 2.0 wt% or more.

  By containing 2.0 wt% or more of the phosphorus-based antioxidant together with the phenol-based antioxidant, it is possible to make the antioxidant in the outer layer 2b move to the inner layer 2a later than before. This is because phenolic antioxidants and phosphorus antioxidants interact with each other between molecules, and the effect of suppressing the rate at which these antioxidants move through the layer is born. it is conceivable that. Thereby, antioxidant remains in the outer layer 2b and the inner layer 2a over a longer period than before. Hereinafter, the oxidation degradation mechanism (Cycle I, Cycle II) of the resin material of the inner layer 2a and the outer layer 2b will be described with reference to FIG.

<ＣｙｃｌｅII>

このように、
ラジカル「ＲＯＯ・／ＲＯ・／・ＯＨ」が発生
→発生したラジカルがポリマー（上記(２)式及び(４)式の「Ｒ−Ｈ」）の「・Ｈ」と反応し、新たなラジカル「ＲＯＯ・／ＲＯ・／・ＯＨ」が発生
→新たなラジカルがポリマーの「・Ｈ」と反応し、ラジカル「ＲＯＯ・／ＲＯ・／・ＯＨ」が発生
→・・・
というサイクルが繰り返される。ラジカル「ＲＯＯ・／ＲＯ・／・ＯＨ」が発生すると、上記（２）式及び（４）式が進行することでポリマー（Ｒ−Ｈ）が消費され、内面層チューブ２が酸化劣化する。 It is considered that the oxidative deterioration of the resin material is generally caused by two reactions of Cycle I (primary oxidation) and Cycle II (secondary oxidation) shown in FIG. In Cycle I, reactions of the following formulas (1) and (2) occur, and in Cycle II, reactions of formulas (3) and (4) occur.
<CycleI>

<Cycle II>

in this way,
The radical "ROO./RO./.OH" is generated. The generated radical reacts with ".H" of the polymer ("RH" in the above formulas (2) and (4)) to form a new radical ""ROO · / RO · / · OH" is generated → A new radical reacts with the polymer "· H" to generate the radical "ROO · / RO · / · OH".
The cycle is repeated. When the radical “ROO · / RO · / · OH” is generated, the above formulas (2) and (4) are advanced, so that the polymer (R—H) is consumed and the inner surface layer tube 2 is oxidized and deteriorated.

  When a phenolic antioxidant is present here, the phenolic antioxidant reacts with the radical "ROO./RO./.OH" to cause a "first antioxidant reaction" (see FIG. 2 (b)). , (2) reaction is suppressed. However, since “ROOH” generated in the “first antioxidant reaction” is unstable (see “R′OOH” in FIG. 2B), it is immediately decomposed into “RO.” And “.OH”. (See equation (3)). Thereafter, as the formula (4) proceeds, the polymer (R—H) is consumed, and the oxidative degradation of the inner surface layer tube 2 proceeds. Therefore, only with the phenolic antioxidant, the polymer (R—H) is consumed, and radicals that are degradation factors continue to increase, so that the oxidative degradation of the inner surface layer tube 2 cannot be suppressed.

  However, if a phosphorus-based antioxidant is present, the “second antioxidant reaction” occurs due to the action of the phosphorus-based antioxidant on “ROOH” produced in the “first antioxidant reaction” (FIG. 2 (c). )), The progression of the above equation (3) is suppressed. Thereby, generation | occurrence | production of radical "RO * / * OH" which is a deterioration factor can be suppressed, As a result, progress of (4) Formula can be suppressed. Therefore, the oxidative deterioration of the inner surface layer tube 2 can be suppressed.

  In addition, when only a phosphorus antioxidant is added, since there is no phenolic antioxidant, the progress of the formulas (1) and (2) cannot be suppressed, and the polymer (R—H) continues to be consumed. . Therefore, the oxidative deterioration of the inner surface layer tube 2 cannot be suppressed.

  Thus, when a phenolic antioxidant or phosphorus antioxidant is present alone, the polymer cannot be efficiently protected from radicals that are degradation factors, but when two antioxidants are used in combination, the polymer Can be protected and oxidative degradation can be suppressed. The inventors have found that such an effect can be obtained when the content of the phosphorus-based antioxidant is 2.0 wt% or more.

  Although the said phenolic antioxidant is not specifically limited, For example, 2.6-di-tertiary-butyl-4-methylphenol can be used. Further, as two types of antioxidants having different molecular weights, for example, a commercially available IRGANOX 1330 (manufactured by BASF Japan, molecular weight: 775) is used as an antioxidant (first antioxidant) having a large molecular weight (FIG. 3A). IRGANOX1076 (manufactured by BASF Japan, molecular weight: 531) can be used as an antioxidant (second antioxidant) having a small molecular weight (see FIG. 3B).

  In two types of antioxidants having different molecular weights, the content of the first antioxidant having a large molecular weight is preferably larger than the content of the second antioxidant having a small molecular weight. Since the first antioxidant has a higher molecular weight than the second antioxidant, it is less likely to pass between the polymer chains of the outer layer 2b and the network structure of the inner layer 2a than the second antioxidant. Therefore, by setting it as the above content, the first antioxidant remains in the outer layer 2b even when all of the second antioxidant contained in the outer layer 2b moves to the inner layer 2a. Since the remaining first antioxidant gradually moves to the inner layer 2a, the antioxidant is present in the outer layer 2b and the inner layer 2a over a long period of time. Thereby, since the first antioxidant reaction occurs reliably (see FIG. 2B), the progress of <Cycle I> (see FIG. 2A) can be effectively suppressed.

  Moreover, it is preferable that the content of the first antioxidant is 2.0 wt% or more and the content of the second antioxidant is 1.0 wt% or more. Thereby, since the 1st antioxidant in the outer layer 2b can be moved more slowly to the inner layer 2a, the progress of <Cycle I> (see FIG. 2A) can be more effectively suppressed.

  Furthermore, the phosphorus-based antioxidant is not particularly limited, and for example, tris (nonylphenyl) phosphite can be used. Furthermore, it is preferable that a phosphorus antioxidant has a molecular weight larger than a 2nd antioxidant with a small molecular weight among phenolic antioxidants. This is because the effect of steric hindrance due to the large molecular size is born, and the movement of the phosphorus-based antioxidant from the outer layer 2b to the inner layer 2a can be further delayed. As such a phosphorus-based antioxidant, for example, commercially available ADK STAB HP-10 (manufactured by ADEKA) can be used (see FIG. 3C).

  Next, the effect of the inner surface layer tube 2 of the present invention will be described in comparison with a conventional inner surface layer tube.

In order to test the life of the hot and cold water supply hose at an accelerated rate, the following chemical water (hypochlorous acid aqueous solution) was circulated through the inner surface layer tube at a water pressure of 0.3 kPa (chlorine circulation test). And the thickness change of the inner layer with respect to test time was measured with the microscope. The results are shown in FIG. 4 and Table 2 (Result 1). In addition, Tables 3 and 4 show temporal changes in the concentration of the antioxidant in the inner layer tube (inner layer and outer layer). Table 3 shows the results of the inner surface layer tube of the present invention, and Table 4 shows the results of the conventional inner surface layer tube. FIG. 5 schematically shows the movement of the antioxidant over time (Result 2).
<Chemical water conditions>
・ Chemical water temperature: 80 ℃
・ Residual chlorine concentration: 50ppm
・ Copper ion concentration: 0.6ppm
・ PH: 6.6

  In the above test, the inner layer tube 2 of the present invention includes an outer layer containing IRGANOX 1330 (2.5 wt%), IRGANOX 1076 (1.5 wt%), and ADK STAB HP-10 (2.0 wt%). Using. Moreover, as the conventional inner surface layer tube, an outer layer containing IRGANOX 1330 (2.5 wt%) and IRGANOX 1076 (1.5 wt%) was used (corresponding to Patent Documents 2 and 3).

(Result 1)

  From FIG. 4 and Table 2, the inner surface layer tube 2 of the present invention did not burst even after 17000 hours, and the inner surface layer tube 2 could be used continuously thereafter. The inner layer thickness was about 100 μm even after 15000 hours had passed. On the other hand, the conventional inner surface layer tube burst when 15000 hours had passed. The inner layer thickness at this time was approximately 0 μm. Thus, it turned out that the inner surface layer tube 2 of this invention can suppress the thickness reduction from the conventional inner surface layer tube, and has the outstanding durability.

(Result 2)

  As shown in Table 3, in the present invention, the antioxidant was present in the inner layer and the outer layer even after 10,000 hours. Specifically, IRGANOX 1076 (phenolic antioxidant with a low molecular weight) and ADK STAB HP-10 (phosphorus antioxidant) are all consumed, but IRGANOX 1330 (a phenolic antioxidant with a high molecular weight) It remained in the outer layer.

  On the other hand, in the conventional inner surface layer tube, as shown in Table 4, the antioxidant is substantially consumed after 4000 hours, and all is consumed after 10000 hours, and both the inner layer and the outer layer are antioxidants. Did not remain. Moreover, the antioxidant which exists in an outer layer was less than this invention until 4000 hours after the test start.

Next, the movement of the antioxidant will be described with reference to FIG. As shown in FIG. 5 (a), in the present invention,
(i) Initially, the antioxidant is included only in the outer layer.
(ii) Thereafter, the antioxidant in the outer layer moves to the inner layer, and the antioxidant moved to the inner layer acts on radicals, active oxygen, copper ions, etc. in the chemical solution water. Thereby, the inner layer is hardly deteriorated by suppressing the deterioration of the inner surface layer tube (inner layer and outer layer). At first, IRGANOX 1076 and Adeka Stub HP-10 move mainly to the inner layer, and the movement amount of IRGANOX 1330 is small (see Table 3).
(iii) After that, since the antioxidant in the outer layer moves to the inner layer and this acts on radicals in the chemical solution water, the inner layer is almost deteriorated by suppressing the deterioration of the inner layer tube (inner layer and outer layer). Not.
(iv) Then, as the antioxidants (mainly IRGANOX 1076 and ADK STAB HP-10) in the outer layer decrease, the antioxidant that moves to the inner layer decreases. Thereby, when the inner layer starts to be oxidized and deteriorated, the whitened layer 6 is formed on the inner layer surface, and the thickness of the inner layer starts to decrease. However, since the antioxidant is continuously supplied to the inner layer, deterioration of the inner layer is suppressed.
(V) Thereafter, IRGANOX 1076 and ADK STAB HP-10 disappear from the outer layer first, but IRGANOX 1330 remains and gradually moves to the inner layer. Since the deterioration of the inner layer is suppressed by this antioxidant, the formation of the whitened layer 6 and the decrease in the thickness of the inner layer can be suppressed.
The whitening layer 6 is generally called a brittle layer.

On the other hand, in the conventional inner surface layer tube, as shown in FIG.
(i) Initially, the antioxidant is included only in the outer layer.
(ii) Thereafter, the antioxidant in the outer layer moves to the inner layer, and the antioxidant in the inner layer acts on radicals, active oxygen, copper ions, etc. in the chemical solution water. When consumed, oxidative degradation starts from the surface side of the inner layer. Thereby, the whitening layer 6 is formed on the inner layer surface. Further, the whitening layer 6 is cracked and becomes brittle, and the thickness of the inner layer starts to be reduced by being scraped by the internal fluid.
(iii) Thereafter, the antioxidant in the outer layer moves to the inner layer, but the moved antioxidant is consumed, and the surface side of the inner layer is further oxidized and deteriorated. Thereby, formation of the whitening layer 6 and scraping are repeated, and the thickness of the inner layer further decreases.
(iv) And as the antioxidant in the outer layer decreases, the antioxidant that moves to the inner layer decreases, thereby promoting the deterioration of the inner layer.
(v) After that, when there is no antioxidant in the outer layer and the inner layer, deterioration of the inner layer is further promoted to reduce the wall thickness, and when the inner layer tube cannot withstand the water pressure, the inner layer tube Burst.

  Thus, in the inner surface layer tube 2 of the present invention, the phenolic antioxidant (IRGANOX 1330) continues to be supplied to the inner layer even when the antioxidants IRGANOX 1076 and ADK STAB HP-10 are consumed first. Can also suppress the deterioration of the inner surface layer tube.

  Here, when the antioxidant is contained in the inner layer 2a, before the antioxidant acts on the deterioration of the inner layer 2a, it is extracted into cold water or hot water that is in direct contact. Therefore, by preventing the inner layer 2a from containing an antioxidant, the antioxidant in the inner layer 2a is prevented from being extracted into cold water or hot water that is in direct contact before acting on the deterioration of the inner layer 2a. be able to. Moreover, the deterioration of the physical property and the smoothness of the inner layer 2a can be suppressed by not including other components (antioxidants) that can also become foreign substances.

  As described above, according to the hot water supply hot water hose 1 of the present embodiment, the outer layer 2b contains a phenol-based antioxidant and a phosphorus-based antioxidant, and the phosphorus-based antioxidant is 2.0 wt% or more. Thus, the movement of the antioxidant in the outer layer 2b to the inner layer 2a can be delayed as compared with the conventional case. Thereby, since the antioxidant can be present in the inner layer 2a and the outer layer 2b for a long period of time, it is possible to suppress the progress of the oxidation deterioration cycle (Cycle II (secondary oxidation)) that could not be suppressed conventionally. As a result, since deterioration of the inner layer 2a and the outer layer 2b can be suppressed, a hose having a longer life than that of the conventional one can be obtained.

  Moreover, since the phenolic antioxidant in the outer layer 2b consists of two types of antioxidants having different molecular weights, it is possible to further delay the movement of the antioxidant in the outer layer 2b to the inner layer. That is, even if the antioxidant having a low molecular weight is consumed by moving to the inner layer 2a first, the antioxidant having a high molecular weight remains in the outer layer 2b. Since this moves to the inner layer 2a, oxidation is suppressed, so that an antioxidant can be present in the inner layer 2a and the outer layer 2b for a long period of time. Thereby, deterioration of the inner layer 2a and the outer layer 2b can be suppressed effectively.

  Further, since the molecular weight of the phosphorus antioxidant in the outer layer 2b is larger than the molecular weight of the second antioxidant, the effect of steric hindrance due to the large molecular size is born, so that the phosphorus antioxidant is in the outer layer. It is possible to delay the movement from the inner layer to the inner layer.

  Further, in the outer layer 2b, the first antioxidant content in the outer layer 2b is set to 2.0 wt% or more and the second antioxidant content is set to 1.0 wt% or more. Can be further slowed down to the inner layer 2a, so that the progress of <Cycle I> (see FIG. 2A) can be more effectively suppressed.

[Example]
Next, examples of the present invention will be described.

(Examples 1-4, Comparative Examples 1 and 2)
The presence or absence of deterioration of the outer layer 2b when the content of the phosphorus antioxidant was changed was examined.

The thermoplastic elastomer constituting the outer layer 2b was allowed to contain a phenolic antioxidant (IRGANOX 1330, IRGANOX1076) and a phosphorus antioxidant (ADK STAB HP-10) (see Table 5). And after forming the test piece of predetermined shape and immersing the test piece in the following chemical | medical solution water (hypochlorous acid aqueous solution), the physical property of the test piece was investigated after progress for a predetermined time. Table 5 shows the test results (hardness change, surface change and color change of the test piece).
<Chemical water conditions>
・ Chemical water temperature: 80 ℃
・ Residual chlorine concentration: 50ppm
・ Copper ion concentration: 0.6ppm
・ PH: 6.6

  From Table 5, in Examples 1-4 (phosphorus antioxidant is 2.0 wt% or more), the hardness hardly changed, and the surface change and the color change hardly occurred. On the other hand, in Comparative Examples 1 and 2 (phosphorus antioxidant is 1.5 wt% or less), the resin surface was softened and deteriorated, and colored powder was generated from the surface after 336 hours had passed. Thus, by changing the content of the phosphorus-based antioxidant, the deterioration of the thermoplastic elastomer could be suppressed more effectively in Examples 1 to 4 than in Comparative Examples 1 and 2.

( Reference Examples, Examples 6 to 11, Comparative Examples 3 and 4)
The presence or absence of deterioration of the outer layer 2b when using phosphorus-based antioxidants having different molecular weights was examined.

A phenolic antioxidant (IRGANOX 1330, IRGANOX1076) and a phosphorus antioxidant were mixed into the thermoplastic elastomer constituting the outer layer 2b (see Table 6). And after forming the test piece of predetermined shape and immersing the test piece in the following chemical | medical solution water (hypochlorous acid aqueous solution), the physical property of the test piece was investigated after progress for a predetermined time. Table 6 shows the test results (change in hardness, surface change and color change of the test piece). 6 and 7 show the structural formula of the phosphorus-based antioxidant used in this example.
< Chemical water conditions >
・ Chemical water temperature: 80 ℃
・ Residual chlorine concentration: 50ppm
・ Copper ion concentration: 0.6ppm
・ PH: 6.6

From Table 6, in the reference examples and Examples 6 to 11 (the molecular weight of the phosphorus-based antioxidant having a large molecular weight of 500 or more), the hardness hardly changed, and the surface change and the color change hardly occurred. On the other hand, in Comparative Examples 3 and 4 (phosphorus antioxidants having a relatively small molecular weight around 300 to 400), the resin surface was softened and deteriorated, and colored powder was generated from the surface after 240 hours. As described above, by using the phosphorus-based antioxidant having a large molecular weight, the deterioration of the thermoplastic elastomer could be effectively suppressed in the reference examples and Examples 6 to 11 as compared with Comparative Examples 3 and 4.

(Examples 12 to 16, Comparative Examples 5 and 6)
The presence or absence of deterioration of the outer layer 2b was examined when the contents of two types of phenolic antioxidants having different molecular weights were changed.

The thermoplastic elastomer constituting the outer layer 2b was allowed to contain a phenolic antioxidant (IRGANOX 1330, IRGANOX1076) and a phosphorus antioxidant (ADK STAB HP-10) (see Table 7). And after forming the test piece of predetermined shape and immersing the test piece in the following chemical | medical solution water (hypochlorous acid aqueous solution), the physical property of the test piece was investigated after progress for a predetermined time. Table 7 shows the test results (hardness change, surface change and color change of the test piece).
< Chemical water conditions >
・ Chemical water temperature: 80 ℃
・ Residual chlorine concentration: 50ppm
・ Copper ion concentration: 0.6ppm
・ PH: 6.6

  From Table 7, in Examples 12 to 16 (when the phenolic antioxidant having a large molecular weight is 2.0 wt% or more and the phenolic antioxidant having a low molecular weight is 1.0 wt% or more), the hardness is almost changed. In addition, almost no surface change or color change occurred. On the other hand, in Comparative Examples 5 and 6 (when the phenolic antioxidant having a large molecular weight is less than 2.0 wt% and the phenolic antioxidant having a small molecular weight is less than 1.0 wt%), the resin surface is softened and deteriorated, When 240 hours passed, colored powder was generated from the surface. From the said result, by setting it as content of this invention, in Examples 12-16, deterioration of the thermoplastic elastomer was able to be suppressed more effectively than Comparative Examples 5 and 6.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is indicated not by the above description but by the scope of claims, and includes all modifications within the meaning and scope equivalent to the scope of claims.

  Moreover, in the above-mentioned embodiment, although the phenolic antioxidant in the outer layer 2b of the inner surface layer tube 2 contains two types of antioxidants having different molecular weights, the phenolic antioxidant is one type of antioxidant. It may consist of three or more kinds of antioxidants. Furthermore, in embodiment and the Example mentioned above, it illustrates about the case where there is more content of 1st antioxidant (antioxidant with large molecular weight) than content of 2nd antioxidant (antioxidant with small molecular weight). However, the content of the first antioxidant may be less than the content of the second antioxidant, and these may be the same amount.

  Furthermore, the phenolic antioxidants (first antioxidant and second antioxidant) and phosphorus antioxidants are not limited to those exemplified in the above-described embodiments and examples.

  In addition, although the example in which the antioxidant is not included in the inner layer 2a of the inner surface layer tube 2 is illustrated in the above-described embodiment (FIG. 5), the inner layer may include an antioxidant.

  In addition, the inner layer tube (inner layer, outer layer) may contain a compounding agent for other purposes, for example, an ultraviolet absorber.

  INDUSTRIAL APPLICATION Since this invention can obtain the hot water supply hot-water supply hose longer life than before, it can be utilized for the hose for hot-water supply equipment, and the hose for water supply equipment.

DESCRIPTION OF SYMBOLS 1 Water supply hot water supply hose 2 Inner surface layer tube 2a Inner layer 2b Outer layer 3 Reinforcement layer 4 Outer surface resin layer 6 Whitening layer 7 Crack

Claims (2)

An inner layer made of cross-linked polyethylene, and an outer layer made of a thermoplastic elastomer provided outside the inner layer,
The outer layer contains a phenolic antioxidant and a phosphorus antioxidant,
The phenolic antioxidant in the outer layer comprises two types of antioxidants having different molecular weights,
Of the two types of antioxidants, the content of the first antioxidant having a large molecular weight is greater than the content of the second antioxidant having a small molecular weight,
The molecular weight of the phosphorus antioxidant in the outer layer is greater than the molecular weight of the second antioxidant in the outer layer,
A content of the phosphorus antioxidant in the outer layer is 2.0 wt% or more. The content of the first antioxidant in the outer layer is 2.0 wt% or more,
2. The hot water and hot water supply hose according to claim 1 , wherein the content of the second antioxidant is 1.0 wt% or more.

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