Water heater inner tank, and preparation method therefor and use thereof

Abstract

Disclosed in the present disclosure are a water heater inner tank, and a preparation method therefor and the use thereof. The water heater inner tank comprises: a metal pressure-bearing layer, a polyethylene bonding layer and a heat-resistant organic polymer anti-corrosion layer, wherein the polyethylene bonding layer is arranged on the inner side of the metal pressure-bearing layer, and the polyethylene bonding layer is formed by using a polyethylene blend, the polyethylene blend comprising: 80-120 parts by weight of a polyethylene basic resin, 2-15 parts by weight of a polar material and 0.1-1 part by weight of an antioxidant; and the heat-resistant organic polymer anti-corrosive layer is arranged on the side away from the metal pressure-bearing layer of the polyethylene bonding layer. The polyethylene bonding layer and the heat-resistant organic polymer anti-corrosive layer of the water heater inner tank of the present disclosure have no pungent smell and can satisfy the safety and sanitation requirements for bath water. In addition, the cohesiveness between the metal pressure-bearing layer and the polyethylene bonding layer of the water heater inner tank is relatively high, thereby avoiding a delamination phenomenon during a usage process, such that requirements for the service life of the water heater inner tank are satisfied.

Description

Water heater liner and its preparation method and application

[0001] Priority information

[0002] This application claims priority and benefits of patent application No. 202311394319.2 filed with the State Intellectual Property Office of China on October 24, 2023, and the entire text of which is incorporated herein by reference. Technical Field

[0003] The present disclosure belongs to the technical field of water heater materials, and particularly relates to a water heater inner tank and a preparation method and application thereof. Background Art

[0004] The inner tanks of most current electric water heaters and solar water heaters use enamel inner tanks. Since the steel plate of the enamel inner tank is prone to hydrogen evolution and fish scale explosion, it leads to poor surface adhesion, and problems such as shrinkage holes or sand holes may occur at the welds. In addition, the material of the enamel inner tank itself is relatively brittle and easily damaged during transportation, so a magnesium rod is needed to protect the inner tank. However, the magnesium rod is prone to produce magnesium slag during use, which will accelerate the formation of scale and pollute the water quality. Long-term use will also cause irritation to the user's skin. In order to solve the above problems, the prior art uses peroxide cross-linked polyethylene (PEX a )Rotational molding of steel-plastic composite liner, which has both the pressure-bearing capacity of steel and the properties of PEX a The corrosion resistance of the lining does not require magnesium rod protection, and the water quality is better. However, it is currently used for steel-lined rotational molding PEX a The raw materials have the following problems: 1) The raw materials have poor polarity. Even if the steel surface is subjected to complex surface treatments such as phosphating, the steel plastic and PEX a The bonding strength between the linings is still low and easy to delaminate; 2) Traditional rotational molding PEX a The peroxide cross-linking agent used in the cross-linking process of the lining will decompose and produce a pungent odor after the cross-linking reaction. This problem is currently a pain point in this field.

[0005] Summary of the Invention

[0006] The present disclosure aims to solve, at least to a certain extent, one of the technical problems in the related art. To this end, the purpose of the present disclosure is to provide a water heater liner, a preparation method thereof, and an application thereof. The polyethylene adhesive layer and the heat-resistant organic polymer anti-corrosion layer of the water heater liner disclosed herein have no irritating odor and can meet the safety and sanitation requirements for bathing water. At the same time, the metal pressure-bearing layer and the polyethylene adhesive layer of the water heater liner have strong adhesion, and delamination will not occur during use, thereby meeting the service life requirements of the water heater liner.

[0007] In one aspect of the present disclosure, a water heater liner is provided. According to an embodiment of the present disclosure, the water heater liner includes:

[0008] Metal pressure-bearing layer;

[0009] A polyethylene adhesive layer, the polyethylene adhesive layer being disposed on the inner side of the metal pressure-bearing layer, the polyethylene adhesive layer being formed by a polyethylene blend comprising: 80-120 parts by weight of a polyethylene base resin, 2-15 parts by weight of a polar material, and 0.1-1 parts by weight of an antioxidant;

[0010] A heat-resistant organic polymer anti-corrosion layer is provided on a side of the polyethylene adhesive layer away from the metal pressure-bearing layer.

[0011] According to the water heater liner of the embodiment of the present disclosure, it is avoided to add a cross-linking agent to the polyethylene adhesive layer, thereby solving the problem of the prior art in the PEX a The problem of pungent odor caused by adding peroxide cross-linking agent in the layer is solved, so that the polyethylene adhesive layer meets the sanitary and safety requirements of the water heater inner tank. At the same time, the present invention sets a heat-resistant organic polymer anti-corrosion layer on the inner side of the polyethylene adhesive layer. The heat resistance of the heat-resistant organic polymer anti-corrosion layer can meet the use standards of the water heater, and the heat-resistant organic polymer anti-corrosion layer also meets the sanitary and safety requirements of the water heater inner tank. The present invention adopts a polyethylene adhesive layer with good bonding performance as the bonding layer, which is connected between the metal pressure-bearing layer and the heat-resistant organic polymer anti-corrosion layer, ensuring the bonding strength between the metal pressure-bearing layer and the heat-resistant organic polymer anti-corrosion layer, and avoiding the delamination phenomenon of the polyethylene adhesive layer and the heat-resistant organic polymer anti-corrosion layer during use. In addition, the present invention adds polar materials to the polyethylene blend, which improves the adhesion between the polyethylene adhesive layer and the metal pressure-bearing layer, so that the metal pressure-bearing layer only needs to undergo a simple degreasing step, without the need for complex sandblasting, pickling, phosphating, etc. to achieve the required bonding strength for use. The peel strength between the metal pressure-bearing layer and the polyethylene adhesive layer reaches 285N / cm-380N / cm, and delamination will not occur during use, thereby meeting the service life requirements of the water heater inner tank.

[0012] In addition, the water heater inner tank according to the above embodiment of the present disclosure may also have the following additional technical features:

[0013] In some embodiments of the present disclosure, the material of the heat-resistant organic polymer anti-corrosion layer includes at least one of polypropylene, polybutylene and polycarbonate.

[0014] In some embodiments of the present disclosure, the thickness ratio of the polyethylene adhesive layer to the heat-resistant organic polymer anti-corrosion layer is (0.5-1.5):(1-2).

[0015] In some embodiments of the present disclosure, the polyethylene adhesive layer has a thickness of 0.5-1.5 mm.

[0016] In some embodiments of the present disclosure, the thickness of the heat-resistant organic polymer anti-corrosion layer is 1-2 mm.

[0017] In some embodiments of the present disclosure, the thickness of the metal pressure-bearing layer is 1-2 mm.

[0018] In some embodiments of the present disclosure, the polar material includes at least one of isocyanate, acrylate, unsaturated carboxylic acid, polyolefin grafted with anhydride or ester derivative, epoxy resin, and unsaturated polyester resin.

[0019] In some embodiments of the present disclosure, the antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxy-phenyl)propionate and 4,4′-thiobis(6-tert-butyl-3-methyl)phenol.

[0020] In some embodiments of the present disclosure, the peel strength between the metal pressure-bearing layer and the polyethylene adhesive layer is 285 N / cm-380 N / cm.

[0021] In another aspect of the present disclosure, a method for preparing the above-mentioned water heater inner tank is provided. According to an embodiment of the present disclosure, the method comprises:

[0022] (1) Pre-treating the metal pressure-bearing layer;

[0023] (2) placing the polyethylene blend into the inner side of the metal pressure-bearing layer, placing the blend in a rotational molding machine, and rotationally molding the blend to form a polyethylene adhesive layer on the inner side of the metal pressure-bearing layer;

[0024] (3) The material of the heat-resistant organic polymer anti-corrosion layer is loaded into the inner side of the polyethylene adhesive layer, placed in the rotational molding machine, and rotationally molded to form the heat-resistant organic polymer anti-corrosion layer on the inner side of the polyethylene adhesive layer.

[0025] According to the method for preparing the water heater liner described above, the polyethylene adhesive layer and heat-resistant organic polymer anti-corrosion layer of the prepared water heater liner are odorless, meeting safety and sanitation requirements for bathing water. Furthermore, the strong adhesion between the metal pressure-bearing layer and the polyethylene adhesive layer prevents delamination during use, thus meeting the required service life of the water heater liner. This preparation method is also simple and easy to implement.

[0026] In addition, the method for preparing a water heater inner tank according to the above embodiment of the present disclosure may also have the following additional technical features:

[0027] In some embodiments of the present disclosure, in step (2), the rotational molding temperature is 220° C.-280° C., and the rotational molding time is 15 min-35 min.

[0028] In some embodiments of the present disclosure, in step (3), the rotational molding temperature is 220° C.-280° C., and the rotational molding time is 15 min-35 min.

[0029] In the third aspect of the present disclosure, the present disclosure proposes a water heater. According to the embodiment of the present disclosure, the water heater has the water heater inner tank of the above embodiment or the water heater inner tank prepared by the method described in the above embodiment. As a result, the water heater has all the advantages of the water heater inner tank of the above embodiment. Specifically, the polyethylene adhesive layer and the heat-resistant organic polymer anti-corrosion layer of the water heater inner tank of the water heater have no irritating odor and can meet the safety and sanitation requirements for bathing water; at the same time, the metal pressure-bearing layer and the polyethylene adhesive layer of the water heater inner tank have strong adhesion, and there will be no delamination during use, thereby meeting the service life requirements of the water heater inner tank, thereby further meeting the needs of consumers.

[0030] Additional aspects and advantages of the present disclosure will be given in part in the description that follows and, in part, will be obvious from the description that follows, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and / or additional aspects and advantages of the present disclosure will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0032] FIG1 is a schematic structural diagram of a water heater inner tank according to an embodiment of the present disclosure;

[0033] FIG2 is a schematic flow chart of a method for preparing a water heater tank according to an embodiment of the present disclosure.

[0034] Detailed Description of the Invention

[0035] The embodiments of the present disclosure are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present disclosure, and should not be understood as limiting the present disclosure.

[0036] In one aspect of the present disclosure, a water heater inner tank is provided. According to an embodiment of the present disclosure, referring to FIG1 , the water heater inner tank comprises: a metal pressure-bearing layer 10; a polyethylene adhesive layer 20, which is disposed on the inner side of the metal pressure-bearing layer 10 and is formed by heating a polyethylene blend comprising 80-120 parts by weight of a polyethylene base resin, 2-15 parts by weight of a polar material, and 0.1-1 parts by weight of an antioxidant; and a heat-resistant organic polymer anti-corrosion layer 30, which is disposed on the side of the polyethylene adhesive layer 20 away from the metal pressure-bearing layer 10. Thus, the present disclosure avoids adding a crosslinking agent to the polyethylene adhesive layer, thereby resolving the problem of irritating odor caused by adding a crosslinking agent to the PEX layer in the prior art, and ensuring that the polyethylene adhesive layer meets the hygienic and safety requirements of the water heater inner tank. At the same time, the present invention sets a heat-resistant organic polymer anti-corrosion layer on the inner side of the polyethylene adhesive layer. The heat-resistant performance of the heat-resistant organic polymer anti-corrosion layer can meet the use standards of the water heater, and the heat-resistant organic polymer anti-corrosion layer also meets the hygienic and safety requirements of the water heater liner. The present invention adopts a polyethylene adhesive layer with good bonding performance as the bonding layer, which is connected between the metal pressure-bearing layer and the heat-resistant organic polymer anti-corrosion layer, ensuring the bonding strength between the metal pressure-bearing layer and the heat-resistant organic polymer anti-corrosion layer, and avoiding the delamination phenomenon between the polyethylene adhesive layer and the heat-resistant organic polymer anti-corrosion layer during use. In addition, the present invention adds polar materials to the polyethylene blend to improve the bonding between the polyethylene adhesive layer and the metal pressure-bearing layer, so that the metal pressure-bearing layer only needs to undergo a simple degreasing step, without the need for complex sandblasting, pickling, phosphating, etc. to achieve the bonding strength required for use, so that the peel strength between the metal pressure-bearing layer and the polyethylene adhesive layer reaches 285N / cm-380N / cm, and no delamination will occur during use, thereby meeting the service life requirements of the water heater liner.

[0037] The following is a detailed description of the principle by which the water heater inner tank proposed in this disclosure can achieve the above beneficial effects:

[0038] In the prior art, peroxide cross-linked polyethylene (PEX a )Rotational molding of steel-plastic composite liner, which has both the pressure-bearing capacity of steel and the properties of PEX a The anti-corrosion performance of the lining. aDuring the formation of the lining, since the heat resistance of the polyethylene basic resin does not meet the use standards of the water heater, a cross-linking agent is required to promote the cross-linking reaction of the polyethylene basic resin under certain conditions to form a cross-linked polyethylene lining. In this field, peroxide system cross-linking agents are generally used. After the heating reaction, the cross-linking agent will decompose and produce a pungent odor. For example, DCP is easily decomposed into gases such as acetophenone, methane, and 2-phenylisopropanol. In particular, acetophenone can cause severe irritation to the human eyes or respiratory tract, and BIBP is easily decomposed into vapors such as tert-butanol and acetone. This problem is currently a pain point in this field. People in this field have tried many methods, but none of them can effectively solve the problem of pungent odor.

[0039] In order to solve the above technical problems, the present invention avoids adding a crosslinking agent to the polyethylene adhesive layer, thereby solving the problem in the prior art of PEX a The problem of pungent odor caused by adding cross-linking agents in the layer is solved, so that the polyethylene adhesive layer meets the sanitary and safety requirements of the water heater inner tank. At the same time, in order to solve the problem that the heat resistance of the polyethylene basic resin does not meet the use standards of the water heater, the present invention sets a heat-resistant organic polymer anti-corrosion layer on the inner side of the polyethylene adhesive layer. The long-term temperature resistance of the heat-resistant organic polymer anti-corrosion layer reaches 95°C, which meets the requirement of long-term use at 80-85°C, and its heat resistance can meet the use standards of the water heater. The heat-resistant organic polymer anti-corrosion layer plays a role in blocking water from penetrating and contacting the metal pressure-bearing layer, providing better corrosion resistance for metal parts. Moreover, no cross-linking agent is used in the heat-resistant organic polymer anti-corrosion layer, and there is no problem of pungent odor caused by the cross-linking agent. Therefore, the heat-resistant organic polymer anti-corrosion layer also meets the sanitary and safety requirements of the water heater inner tank. However, the adhesion between the heat-resistant organic polymer anti-corrosion layer and the metal pressure-bearing layer is poor. In order to solve this problem, the present invention adopts a polyethylene adhesive layer with good bonding performance as the adhesive layer, which is connected between the metal pressure-bearing layer and the heat-resistant organic polymer anti-corrosion layer, ensuring the bonding strength between the metal pressure-bearing layer and the heat-resistant organic polymer anti-corrosion layer, and avoiding the delamination phenomenon of the polyethylene adhesive layer and the heat-resistant organic polymer anti-corrosion layer during use.

[0040] In order to further ensure the bonding strength between the metal pressure-bearing layer and the heat-resistant organic polymer anti-corrosion layer, the present invention adds a polar material to the polyethylene blend. The polar material contains polar groups, and the polar groups in the polar material can react with the hydroxyl groups on the metal pressure-bearing layer to generate chemical bonds, thereby improving the bonding between the polyethylene adhesive layer and the metal pressure-bearing layer. The metal pressure-bearing layer only needs to undergo a simple degreasing step, without the need for complicated sandblasting, pickling, phosphating, etc. to achieve the bonding strength required for use. The peel strength between the metal pressure-bearing layer and the polyethylene adhesive layer reaches 285N / cm-380N / cm, and delamination will not occur during use, thereby meeting the service life requirements of the water heater inner tank.

[0041] In the embodiments of the present disclosure, the material of the above-mentioned heat-resistant organic polymer anti-corrosion layer is not particularly limited, as long as its heat resistance and sanitary and safety performance can meet the use standards of the water heater inner tank. According to some specific embodiments of the present disclosure, the material of the heat-resistant organic polymer anti-corrosion layer includes at least one of polypropylene, polybutylene and polycarbonate. The heat-resistant organic polymer anti-corrosion layer formed by the above-mentioned types of materials can not only meet the use standards of the water heater inner tank for heat resistance, but also meet the sanitary and safety requirements of the water heater inner tank.

[0042] According to some further specific embodiments of the present disclosure, the thickness ratio of the polyethylene adhesive layer to the heat-resistant organic polymer anti-corrosion layer can be (0.5-1.5):(1-2), thereby further ensuring the bonding strength between the metal pressure-bearing layer and the heat-resistant organic polymer anti-corrosion layer, and further avoiding delamination between the metal pressure-bearing layer and the heat-resistant organic polymer anti-corrosion layer.

[0043] As some specific examples, the thickness of the polyethylene adhesive layer can be 0.5-1.5 mm (for example, 0.5 / 0.7 / 0.9 / 1.0 / 1.2 / 1.3 / 1.5 mm). As some specific examples, the thickness of the heat-resistant organic polymer anti-corrosion layer can be 1-2 mm (for example, 1 / 1.2 / 1.4 / 1.6 / 1.8 / 2 mm). As some specific examples, the thickness of the metal pressure-bearing layer can be 1-2 mm (for example, 1 / 1.2 / 1.4 / 1.6 / 1.8 / 2 mm).

[0044] In the embodiments of the present disclosure, the specific types of the above-mentioned polar materials are not particularly limited. As some specific examples, the polar materials include but are not limited to at least one of polyolefins, epoxy resins and unsaturated polyester resins grafted with isocyanates, acrylates, unsaturated carboxylic acids, anhydrides or ester derivatives. Among them, epoxy resins and unsaturated polyester resins both contain polar groups, which can react with the hydroxyl groups on the metal pressure-bearing layer to form chemical bonds, thereby improving the adhesion between the PE liner and the metal pressure-bearing layer. The polar materials formed by grafting isocyanates, acrylates, unsaturated carboxylic acids, anhydrides or ester derivatives on polyolefins also contain polar groups, which can also react with the hydroxyl groups on the metal pressure-bearing layer to form chemical bonds, thereby improving the adhesion between the polyethylene adhesive layer and the metal pressure-bearing layer. The grafting rate on the polyolefin is also not particularly limited and is generally selected between 1% and 10%.

[0045] In the embodiments of the present disclosure, the antioxidant is used to prevent oxidation and aging of the polyethylene adhesive layer. The specific type of the antioxidant is not particularly limited. As some specific examples, the antioxidant includes but is not limited to at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxy-phenyl)propionate]pentaerythritol and 4,4'-thiobis(6-tert-butyl-3-methyl)phenol.

[0046] In the embodiments of the present disclosure, the specific material of the metal pressure-bearing layer is not particularly limited, and may be, for example, a carbon steel pressure-bearing layer.

[0047] In another aspect of the present disclosure, a method for preparing the above-mentioned water heater inner tank is provided. According to an embodiment of the present disclosure, with reference to FIG2 , the method comprises:

[0048] S100: Pre-treating the metal pressure-bearing layer.

[0049] In this step, the metal pressure-bearing layer is pretreated to remove oil and rust on the surface of the metal pressure-bearing layer so that the polyethylene adhesive layer can be better bonded to the metal pressure-bearing layer.

[0050] S200: The polyethylene blend is loaded into the inner side of the metal pressure-bearing layer, placed in a rotational molding machine, and rotationally molded to form a polyethylene adhesive layer on the inner side of the metal pressure-bearing layer.

[0051] According to some specific embodiments of the present disclosure, in this step, the rotational molding temperature can be 220°C-280°C (for example, it can be 220 / 230 / 240 / 250 / 260 / 270 / 280°C, etc.), and the rotational molding time can be 15min-35min (for example, it can be 15 / 20 / 25 / 30 / 35min), after which the inner liner is cooled.

[0052] Before the polyethylene blend is loaded into the inner side of the metal pressure-bearing layer, the polyethylene basic resin, polar material and antioxidant are first melt-blended at 130-150° C. (for example, melt-blended in a twin-screw extruder), and then granulated to obtain the polyethylene blend.

[0053] S300: The material of the heat-resistant organic polymer anti-corrosion layer is loaded into the inner side of the polyethylene adhesive layer, and the material is placed in a rotational molding machine for rotational molding to form the heat-resistant organic polymer anti-corrosion layer on the inner side of the polyethylene adhesive layer.

[0054] According to some specific embodiments of the present disclosure, in this step, the rotational molding temperature can be 220°C-280°C (for example, it can be 220 / 230 / 240 / 250 / 260 / 270 / 280°C, etc.), and the rotational molding time can be 15min-35min (for example, it can be 15 / 20 / 25 / 30 / 35min), after which the inner liner is cooled.

[0055] According to the method for preparing the water heater liner described above, the polyethylene adhesive layer and heat-resistant organic polymer anti-corrosion layer of the prepared water heater liner are odorless, meeting safety and sanitation requirements for bathing water. Furthermore, the strong adhesion between the metal pressure-bearing layer and the polyethylene adhesive layer prevents delamination during use, thus meeting the required service life of the water heater liner. This preparation method is also simple and easy to implement.

[0056] In the third aspect of the present disclosure, the present disclosure proposes a water heater. According to the embodiment of the present disclosure, the water heater has the water heater inner tank of the above embodiment or the water heater inner tank prepared by the method described in the above embodiment. As a result, the water heater has all the advantages of the water heater inner tank of the above embodiment. Specifically, the polyethylene adhesive layer and the heat-resistant organic polymer anti-corrosion layer of the water heater inner tank of the water heater have no irritating odor and can meet the safety and sanitation requirements for bathing water; at the same time, the metal pressure-bearing layer and the polyethylene adhesive layer of the water heater inner tank have strong adhesion, and there will be no delamination during use, thereby meeting the service life requirements of the water heater inner tank, thereby further meeting the needs of consumers.

[0057] Specifically, the water heater may be an electric water heater, a solar water heater, or the like.

[0058] The following examples of the present disclosure are described in detail. It should be noted that the following examples are illustrative and are intended only to explain the present disclosure and are not to be construed as limiting the present disclosure. In addition, unless otherwise expressly stated, all reagents used in the following examples are commercially available or can be synthesized according to methods described herein or known methods. Reaction conditions not listed are also readily available to those skilled in the art.

[0059] Example 1

[0060] This embodiment provides a water heater inner tank, the preparation method of which includes:

[0061] 1) 80 g of linear low-density polyethylene (LLDPE1802), 5 g of unsaturated polyester resin (HS8706), and 0.1 g of antioxidant (Irganox 1010) were extruded and granulated by a twin-screw extruder at 140° C. and 75 rpm, and then ground into powder to obtain a polyethylene blend.

[0062] 2) Degreasing and rust removal of the carbon steel welded liner with a thickness of 1.4 mm.

[0063] 3) The polyethylene blend is loaded into the inner side of the carbon steel pressure-bearing layer and placed in a rotational molding machine for rotational molding. The rotational molding temperature is 230° C., the heating time is 25 minutes, and the cooling time is 15 minutes, so as to form a polyethylene bonding layer with a thickness of 1.5 mm on the inner side of the carbon steel pressure-bearing layer.

[0064] 4) The polypropylene powder is loaded into the inner side of the polyethylene adhesive layer and placed in a rotational molding machine for rotational molding. The rotational molding temperature is 230° C., the heating time is 25 minutes, and the cooling time is 15 minutes, so as to form a heat-resistant organic polymer anticorrosive layer with a thickness of 2 mm on the inner side of the polyethylene adhesive layer.

[0065] Example 2

[0066] This embodiment provides a water heater inner tank, the preparation method of which includes:

[0067] 1) 120 g of linear low-density polyethylene (LLDPE1802), 8 g of epoxy resin E12, and 0.8 g of antioxidant Irganox 1010 were extruded and granulated by a twin-screw extruder at 140° C. and 75 rpm, and then ground into powder to obtain a polyethylene blend.

[0068] 2) Degreasing and rust removal of the carbon steel welded liner with a thickness of 1.5 mm.

[0069] 3) The polyethylene blend is loaded into the inner side of the carbon steel pressure-bearing layer and placed in a rotational molding machine for rotational molding. The rotational molding temperature is 230° C., the heating time is 25 minutes, and the cooling time is 15 minutes, so as to form a polyethylene bonding layer with a thickness of 1.2 mm on the inner side of the carbon steel pressure-bearing layer.

[0070] 4) The polybutene powder is loaded into the inner side of the polyethylene adhesive layer and placed in a rotational molding machine for rotational molding. The rotational molding temperature is 230° C., the heating time is 25 minutes, and the cooling time is 15 minutes, so as to form a heat-resistant organic polymer anticorrosive layer with a thickness of 1.8 mm on the inner side of the polyethylene adhesive layer.

[0071] Example 3

[0072] This embodiment provides a water heater inner tank, the preparation method of which includes:

[0073] 1) 100 g of linear low-density polyethylene (LLDPE1802), 10 g of epoxy resin E12, and 0.5 g of antioxidant Irganox 1010 were extruded and granulated and ground into powder by a twin-screw extruder at 140° C. and 75 rpm to obtain a polyethylene blend.

[0074] 2) Degreasing and rust removal of the carbon steel welded liner with a thickness of 1.65 mm.

[0075] 3) The polyethylene blend is loaded into the inner side of the carbon steel pressure-bearing layer and placed in a rotational molding machine for rotational molding. The rotational molding temperature is 230° C., the heating time is 25 minutes, and the cooling time is 15 minutes, so as to form a polyethylene bonding layer with a thickness of 1 mm on the inner side of the carbon steel pressure-bearing layer.

[0076] 4) The polycarbonate powder is loaded into the inner side of the polyethylene adhesive layer and placed in a rotational molding machine for rotational molding. The rotational molding temperature is 230° C., the heating time is 25 minutes, and the cooling time is 15 minutes, so as to form a heat-resistant organic polymer anticorrosive layer with a thickness of 2 mm on the inner side of the polyethylene adhesive layer.

[0077] Example 4

[0078] This embodiment provides a water heater inner tank, the preparation method of which includes:

[0079] 1) 100 g of linear low-density polyethylene (LLDPE) 1802, 8 g of maleic anhydride-grafted polyolefin (MA-LLDPE) (grafting rate: 1.2 wt%), and 0.1 g of antioxidant (Irganox 1010) were extruded and granulated by a twin-screw extruder at 140° C. and 75 rpm, and then ground to obtain a polyethylene blend.

[0080] 2) Degreasing and rust removal of the carbon steel welded liner with a thickness of 1.8 mm.

[0081] 3) The polyethylene blend is loaded into the inner side of the carbon steel pressure-bearing layer and placed in a rotational molding machine for rotational molding. The rotational molding temperature is 230° C., the heating time is 25 minutes, and the cooling time is 15 minutes, so as to form a polyethylene bonding layer with a thickness of 1.2 mm on the inner side of the carbon steel pressure-bearing layer.

[0082] 4) The polypropylene powder is loaded into the inner side of the polyethylene adhesive layer and placed in a rotational molding machine for rotational molding. The rotational molding temperature is 230° C., the heating time is 25 minutes, and the cooling time is 15 minutes, so as to form a heat-resistant organic polymer anticorrosive layer with a thickness of 1.5 mm on the inner side of the polyethylene adhesive layer.

[0083] Comparative Example 1

[0084] 1) 100 g of linear low-density polyethylene (LLDPE) 1802, 1 g of peroxide crosslinking agent (DCP), 10 g of epoxy resin (E12), and 0.5 g of antioxidant (Irganox 1010) were extruded and granulated by a twin-screw extruder at 140° C. and 75 rpm, and then ground into powder to obtain a crosslinkable polyethylene blend.

[0085] 2) Degrease and rust the carbon steel welded liner.

[0086] 3) The cross-linkable polyethylene blend is placed inside the carbon steel pressure-bearing layer and placed in a rotational molding machine for rotational molding. The rotational molding temperature is 230°C, the heating time is 25 minutes, and the cooling time is 15 minutes, so as to form PEX inside the carbon steel pressure-bearing layer. a Lining layer.

[0087] Comparative Example 2

[0088] In this comparative example, epoxy resin E12 was not added, and other contents were the same as those in Example 3.

[0089] The peel strength (N / cm) of the composite anti-corrosion layer (i.e., polyethylene adhesive layer and heat-resistant organic polymer anti-corrosion layer) of Examples 1-4 and Comparative Examples 1-2 peeled off from the carbon steel pressure-bearing layer is determined according to GB / T23257-2017. The test method is as follows: scratch a 1 cm wide strip on the composite anti-corrosion layer of the liner product, the length of which is greater than 20 cm, and the scratch depth reaches the metal part. Peel one end of the strip off from the metal part by at least 2 cm, and use a tensile testing machine to pull up the peeled strip at a speed of 10 mm / min; read the stress value of the tensile testing machine, and after the tension stabilizes, take the average value after stabilization as the peel strength.

[0090] The odor detection method is as follows: 5 odor testers test the odor of the liner just produced N0, the odor after being placed in the air for 24 hours Ng 24 、Odor after being placed in the air for 48 hours Ng 48 , the smell after water treatment N w The odor rating is divided into six levels: 1 = no odor, 2 = slight odor, 3 = odor but not irritating, 4 = irritating odor, 5 = strong irritating odor, and 6 = unbearable odor. The average odor rating obtained by the five odor testers was then calculated: odor rating N = (N1 + N2 + N3 + N4 + N5) / 5. The test results are shown in Table 1.

[0091] Table 1

[0092] As can be seen from Table 1, the peel strength of Examples 1-4 is all above 289.5N / cm, the odor N0 of the liner just produced is all below 1.5 level, and the odor Ng after being placed in the air for 24 hours is 24 All are below 1.3 level, and the odor after being placed in the air for 48 hours is Ng 48 All are below 1.2 level, and the odor after water treatment is N w All are below level 1.1, meeting the hygiene and safety requirements for the water heater tank.

[0093] Compared with Comparative Example 1, the odor of the inner container prepared in Example 3 is significantly reduced in various states. It can be seen that the odor is significantly reduced after avoiding the addition of the cross-linking agent in Example 3.

[0094] Compared with Comparative Example 2, the peel strength of the polyethylene adhesive layer prepared in Example 3 is significantly improved. It can be seen that the addition of polar materials significantly improves the peel strength of the polyethylene adhesive layer, meeting the service life requirements of the water heater inner tank.

[0095] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0096] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present disclosure. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present disclosure.

Claims

1. A water heater tank, wherein: include: Metal pressure bearing layer; A polyethylene adhesive layer, the polyethylene adhesive layer is arranged on the inner side of the metal pressure-bearing layer, the polyethylene adhesive layer is formed by a polyethylene blend, and the polyethylene blend includes: 80-120 parts by weight of a polyethylene base resin, 2-15 parts by weight of a polar material and 0.1-1 parts by weight of an antioxidant; A heat-resistant organic polymer anti-corrosion layer is provided on a side of the polyethylene adhesive layer away from the metal pressure-bearing layer.

2. The water heater inner tank according to claim 1, wherein: The material of the heat-resistant organic polymer anti-corrosion layer includes at least one of polypropylene, polybutylene and polycarbonate.

3. The water heater inner tank according to claim 1 or 2, wherein: The thickness ratio of the polyethylene adhesive layer to the heat-resistant organic polymer anti-corrosion layer is (0.5-1.5):(1-2).

4. The water heater inner tank according to any one of claims 1 to 3, wherein: The thickness of the polyethylene adhesive layer is 0.5-1.5 mm.

5. The water heater inner tank according to any one of claims 1 to 4, wherein: The thickness of the heat-resistant organic polymer anti-corrosion layer is 1-2 mm.

6. The water heater inner tank according to any one of claims 1 to 5, wherein: The thickness of the metal pressure-bearing layer is 1-2 mm.

7. The water heater inner tank according to any one of claims 1 to 6, wherein: The polar material includes at least one of isocyanate, acrylate, unsaturated carboxylic acid, polyolefin grafted with anhydride or ester derivative, epoxy resin and unsaturated polyester resin.

8. The water heater inner tank according to any one of claims 1 to 7, wherein: The antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxy-phenyl) propionate and 4,4'-thiobis(6-tert-butyl-3-methyl)phenol.

9. The water heater inner tank according to any one of claims 1 to 8, wherein: The peel strength between the metal pressure-bearing layer and the polyethylene adhesive layer is 285N / cm-380N / cm.

10. A method for preparing a water heater tank according to any one of claims 1 to 9, wherein: include: (1) Pretreatment of the metal pressure-bearing layer; (2) placing the polyethylene blend inside the metal pressure-bearing layer, placing the blend in a rotational molding machine, and rotationally molding the blend so as to form a polyethylene adhesive layer inside the metal pressure-bearing layer; (3) The material of the heat-resistant organic polymer anti-corrosion layer is loaded into the inner side of the polyethylene adhesive layer, placed in the rotational molding machine, and rotationally molded to form the heat-resistant organic polymer anti-corrosion layer on the inner side of the polyethylene adhesive layer.

11. The method according to claim 10, wherein: In step (2), the rotational molding temperature is 220° C.-280° C., and the rotational molding time is 15 min-35 min.

12. The method according to claim 10 or 11, wherein: In step (3), the rotational molding temperature is 220°C-280°C, and the rotational molding time is 15min-35min.

13. A water heater, wherein: A water heater inner tank according to any one of claims 1 to 9 or a water heater inner tank prepared by the method according to any one of claims 10 to 12.

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