CN115464937A

CN115464937A - Household rubber pipe suitable for hydrogen-doped natural gas and preparation method

Info

Publication number: CN115464937A
Application number: CN202210832524.1A
Authority: CN
Inventors: 姜鑫; 王馨培; 蔡昊; 丁斌; 肖倩; 王维婷
Original assignee: Beijing Gas Group Co Ltd
Current assignee: Beijing Gas Group Co Ltd
Priority date: 2022-07-15
Filing date: 2022-07-15
Publication date: 2022-12-13

Abstract

The invention belongs to the technical field of rubber pipes, and discloses a household rubber pipe suitable for hydrogen-doped natural gas, which sequentially comprises an inner layer adhesive, a middle layer adhesive and an outer layer adhesive from inside to outside; the inner layer rubber comprises chlorohydrin rubber, the middle layer rubber comprises nitrile rubber, and the outer layer rubber comprises chloroprene rubber/chlorinated polyethylene; or the inner layer rubber is a nylon coating, the middle layer rubber comprises nitrile rubber, and the outer layer rubber comprises nitrile rubber/polyethylene. The rubber tube has long service life and is suitable for natural gas.

Description

Household rubber pipe suitable for natural gas doped with hydrogen and preparation method

Technical Field

The invention relates to the technical field of rubber pipes, in particular to a household rubber pipe suitable for hydrogen-doped natural gas and a preparation method thereof.

Background

The description of the background of the invention pertaining to the related art to which this invention pertains is given for the purpose of illustration and understanding only of the summary of the invention and is not to be construed as an admission that the applicant is explicitly or implicitly admitted to be prior art to the date of filing this application as first filed with this invention.

The development of the hose industry in various foreign countries is closely related to automobiles, machine tools, construction industry, underground mining, oil exploitation and offshore oil drilling, and attracts people's attention. The hose industry has undoubtedly gained a great deal of development, from the first limited variety and specification to the numerous fields of hydraulic engineering machinery, oil drilling, aerospace, automobiles, ships, coal mining, agriculture and water conservancy, etc., which are related today, the variety of the hose used is hundreds, and the hose specification is thousands. According to the statistics of the technical committee of SCI hose classification of ISO/T C45 (technical committee of international organization for standardization) there are as many as 77 hose standards that have been formulated, and there are 20 international standards relating to the hose test method. In recent years, due to the rising call of environmental protection, the hose is required to adopt rubber materials meeting the requirements to meet the requirement of environmental protection, and people pay more attention to the application of flame-retardant and flame-retardant hoses. With the advent of more sophisticated mechanical devices, higher demands are also placed on the hoses used, such as smaller bending radii and smaller masses. ISO/DIS 11237 "Hydraulic Steel wire tightly braided reinforced rubber hose and hose Assembly" has made explicit provisions for this. It is also desirable that the hose industry be able to recycle waste hose as well as the tire industry to avoid environmental pollution. With the advent of new materials and widespread use of thermoplastic elastomers, it is reasonable to believe that the hose industry will use mature production techniques to produce products that meet the requirements of the 21 st century.

In recent years, foreign hose production plants all use a vacuum pumping cold feed extruder and are provided with a rubber filtering device (and start to adopt granulated rubber), so that the internal diameter, the external diameter, the wall thickness and the eccentricity of the hose can meet the specified requirements, and impurities can be eliminated. Companies such as Acetotrix, the United states of America, entered the nineties, have implemented laser technology to measure hose size, achieving full automation of measurement, feedback, and adjustment. In addition, the application of the shearing machine head extruder, the composite extrusion process and the extrusion process of short fiber reinforced rubber materials further improves the continuous production degree of hose production plants in the United states and Europe.

The hose industry has been in China for 50 years and is now one of the main industries in the rubber industry of China. In recent years, the demand for hoses is gradually increased along with the rapid development of automobile manufacturing, oil exploitation, agricultural water conservancy, marine chemical industry and construction industry in China. Meanwhile, the method is close to the international standard, so that the continuous improvement of the traditional hose process, production method, standard and structure is promoted, and a batch of hose backbone enterprises with advanced equipment and strong comprehensive strength are developed.

With the continuous and high-speed development of national economy in China in recent years, the demand for energy is also increased year by year. As a new clean energy, the natural gas plays a good role in adjusting the energy structure, improving the environmental pollution, facilitating the life of people, saving the energy, reducing the environmental pollution and the like. With the implementation of 'gas transmission from west to east' in China, the construction pace of local natural gas pipelines in China is accelerated, natural gas pipe networks are developed and extended continuously, unsafe factors in the aspect of gas safety are increased when various applications are applied to the pipe networks and facilities, and the guarantee of the safety of town gas projects is the key point of gas work.

The indoor hose matched with the natural gas of the household pipeline is a fabric reinforced PVC composite pipe matched with pipeline gas, and the gas pipe has low raw material cost, mature production technology and low product price. PVC or PE and the like are used for producing the materials of the pipe, the materials have good aging resistance and medium resistance, and the material is suitable for various engineering pipelines. PVC or PE and other materials are hard, and when the material is used for household hoses, a large amount of plasticizer is required to be added in order to ensure that the gas pipe has certain softness. The plasticizer has good compatibility with various fuel gases, so that the plasticizer continuously migrates out along with the passage of time in the use process, and the fuel gas pipe becomes hard. The air tightness of the gas pipe is reduced due to the hollow space left after the plasticizer is migrated out. The existing plastic pipe or reinforced plastic composite pipe is difficult to solve the problems of aging and hardening of the gas pipe and the like in long-term use through formula matching or improvement of a processing technology.

From the use condition of foreign domestic gas hoses, most of the gas hoses are rubber-plastic multilayer composite hoses or stainless steel metal corrugated pipes. The rubber-plastic multilayer composite hose has a multilayer composite structure, provides requirements for different layer performances of a gas hose, gives full play to the advantages of various materials, selects a rubber material with good air tightness and gas resistance as an inner layer material to be directly contacted with a gas medium, and provides long-term anti-aging performance for the rubber hose through optimization of a plasticizing system and an anti-aging system on the premise of ensuring that the air tightness and the gas resistance are not reduced. The rubber gas hose has good flexibility, small bending radius and simple and convenient installation, and the use of the rubber gas hose is not influenced even in a place with a narrow space. Can be compatible with various gas interfaces. The using length can be intercepted according to the needs, and the assembly pipe with the joints at the two ends can be made according to the needs, so that the assembly pipe is convenient to install. The rubber gas hose is cheap.

In recent years, with the emphasis and improvement of environmental protection problems, the attention to environmental protection performance is paid more to the rubber gas hose on the basis of ensuring safety. In the aspect of the selective use of rubber compounding agents, particularly vulcanizing agents and vulcanization accelerators, the frequently contained nitrosamines (or nitrosamines) and o-toluidines and other potential carcinogenic substances and substances harmful to personnel, ecology and environment are strictly restricted, and the European Union also passes through REACH regulations in order to reduce and eliminate the possible harm of these substances to operators of rubber processing enterprises and users, ecology and environment of rubber products. Therefore, some rubber compounding ingredient manufacturers have developed some new compounding ingredients; in addition, some companies have developed various water-based mold release agents that are free of nitrosamines and other harmful substances, to replace the conventionally used compounding agents and mold release agents that are harmful to humans and the environment. This has become a trend in the rubber processing industry worldwide. The elimination of the potential production of nitrosamine accelerators has now become a first element in the current development of vulcanization accelerators.

Disclosure of Invention

The embodiment of the invention aims to provide a household rubber pipe suitable for natural gas doped with hydrogen, which is long in service life and suitable for the natural gas doped with hydrogen.

The purpose of the invention is realized by the following technical scheme:

a household rubber tube suitable for natural gas doped with hydrogen sequentially comprises an inner layer rubber, a middle layer rubber and an outer layer rubber from inside to outside;

the inner layer rubber comprises chlorohydrin rubber, the middle layer rubber comprises nitrile rubber, and the outer layer rubber comprises chloroprene rubber/chlorinated polyethylene;

or the like, or a combination thereof,

the inner layer rubber is a nylon coating, the middle layer rubber comprises nitrile rubber, and the outer layer rubber comprises nitrile rubber/polyethylene.

Further, the inner layer rubber comprises chlorohydrin rubber and comprises the following components in parts by weight:

further, the middle layer glue comprises the following components in parts by weight:

further, the nylon coating adopts a nylon 66 (PA 66) coating.

Further, the outer layer rubber comprises the following components in parts by weight:

the preparation method of the household rubber tube suitable for the natural gas doped with hydrogen comprises the following steps:

rubber mixing: respectively carrying out two-stage mixing on the inner layer rubber raw material, the middle layer rubber raw material and the outer layer rubber raw material to obtain rubber compound;

and (3) extrusion molding: putting the inner layer rubber compound and the pipe tire into an extruder for extrusion to obtain an inner layer rubber pipe blank, putting the inner layer rubber pipe blank and the middle layer rubber compound into the extruder for extrusion to obtain a middle layer rubber pipe blank, and putting the middle layer rubber pipe blank and the outer layer rubber compound into the extruder for extrusion to obtain a rubber pipe blank;

vulcanizing the rubber tube: vulcanizing the rubber tube blank to obtain the household rubber tube suitable for the hydrogen-doped natural gas: the vulcanization pressure is 4-6kg. Vulcanization conditions are as follows: 160 ℃; the vulcanization time is 60-70 min.

The embodiment of the invention has the following beneficial effects:

the rubber tube structure of the invention is a household gas hose with three layers of rubber, namely chlorohydrin rubber/nitrile rubber/(chloroprene rubber/chlorinated polyethylene) and nylon coating/nitrile rubber/(nitrile rubber/polyvinyl chloride) which are made of two different materials. The newly developed gas hose mainly uses rubber materials, exerts the advantages of different rubber varieties, provides different service performances for the hose through a multilayer composite structure, and has excellent oil resistance, flame resistance, air tightness, aging resistance and other performances. The rubber hose fundamentally overcomes the potential safety hazard that the polyvinyl chloride plastic hose is hard and brittle after long-term use and the joint is easy to leak air.

Drawings

FIG. 1 is a flow chart of an extrusion molding process of a scheme A of a rubber tube production processing flow in the embodiment of the invention:

FIG. 2 is a flow chart of extrusion molding process of the rubber tube production processing flow B scheme in the embodiment of the invention:

Detailed Description

The present application is further described below with reference to examples.

In the following description, different "one embodiment" or "an embodiment" refers to different embodiments, but not necessarily the same embodiment, in order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art. Various embodiments may be replaced or combined, and other embodiments may be obtained according to the embodiments without creative efforts for those skilled in the art.

A household rubber pipe suitable for natural gas doped with hydrogen sequentially comprises an inner layer rubber, a middle layer rubber and an outer layer rubber from inside to outside;

or the like, or, alternatively,

In some embodiments of the present invention, the inner layer rubber comprises chlorohydrin rubber, and comprises the following components in parts by weight:

in some embodiments of the present invention, the middle layer adhesive comprises the following components in parts by weight:

in some embodiments of the present invention, the middle layer glue comprises an outer layer glue comprising neoprene/chlorinated polyethylene, and the outer layer glue comprises the following components in parts by weight:

in some embodiments of the present invention, the nylon coating is a nylon 66 (PA 66) coating.

In some embodiments of the present invention, the outer layer rubber comprises an outer layer rubber of nitrile rubber/polyethylene, which comprises the following components in parts by weight:

The rubber tube structure of the invention is a household gas hose with three layers of rubber, namely chlorohydrin rubber/nitrile rubber/(chloroprene rubber/chlorinated polyethylene) and nylon coating/nitrile rubber/(nitrile rubber/polyvinyl chloride) which are made of two different materials. The newly developed gas hose mainly uses rubber materials, exerts the advantages of different rubber varieties, provides different service performances for the hose through a multilayer composite structure, and has excellent oil resistance, flame resistance, air tightness, aging resistance and other performances. The rubber hose fundamentally overcomes the potential safety hazard caused by the fact that the polyvinyl chloride plastic hose is hard and brittle after long-term use and the joint is easy to leak air.

The scheme of the invention is further described by combining specific experiments as follows:

the rubber-plastic composite gas pipe compounds rubber and plastic together, fully exerts the advantages of respective materials, selects rubber materials with good air tightness and gas resistance as inner layer materials to directly contact with gas media, and provides long-term ageing resistance for the rubber pipe through the optimization of a plasticizing system and an anti-aging system on the premise of ensuring that the air tightness and the gas resistance are not reduced, thereby being the basis for realizing the development of the long-life gas rubber pipe. The outer layer of the rubber material is coated with a plastic material or a rubber material with high cost performance, so that the inner rubber layer is protected from being damaged externally, the strength and the thermo-oxidative aging resistance of the gas pipe are improved, and the gas pipe is well adhered and matched with the inner rubber layer in hardness. The surface smoothness is increased, the appearance is attractive, and the printing of characters is facilitated. The composite multilayer rubber tube can meet different performance requirements according to the use environment and the use conditions of the rubber tube, and simultaneously, the cost of raw materials can be reduced, and a product with higher cost performance is obtained.

The raw materials used in the test and the production are optimized and the quality is controlled, so that the overall quality of the rubber tube is ensured. The raw rubber is the preferred raw rubber provided by each company, and other raw materials (rubber auxiliaries) are common raw materials for industrial production. Table 1 lists the various raw materials used in the hose development.

Table 1 raw materials for formulation

Main apparatus and equipment

An open mill: XK-160A, shanghai rubber machinery plant

A plate vulcanizing machine: 100TQLB, zhejiang Huzhou and Fu rubber plant

Rubber rotor-free vulcanizer: C2000E, yongshen electronics Co., ltd of Beijing City

A tensile machine: T2000E, yongshen electronics Co., ltd, beijing

A hardness meter: LX-A Shanghai Liuling instruments factory

General physical Performance execution Standard

The main criteria on which the physical properties were tested in the test were as follows:

rubber mixing, GB/T6038-2006 rubber test sizing material batching, mixing and vulcanizing equipment and operation program

Determination of initial vulcanization characteristics of Mooney scorch, GB/T1233-2008 unvulcanized rubber was performed with a disk shear viscometer

Determination of tensile stress-strain property of GB/T528-2009 vulcanized rubber or thermoplastic rubber, determination of GB/T529-2008 vulcanized rubber or thermoplastic rubber tear strength

Hardness, GB/T531.1-2008 vulcanized rubber or thermoplastic rubber indentation hardness test method part 1: shore durometer method (Shore hardness)

Test mixing and vulcanizing process

Mixing process

An open mill:

the charging sequence is as follows: raw rubber-filling reinforcing agent, white carbon black-small material (anti-ageing agent, talcum powder, pottery clay and stearic acid), vulcanizing agent-thinly-passing-lower sheet.

The operation key points are as follows: the storage temperature of the rubber material is proper, the self-vulcanization is prevented, and the Mooney viscosity and the density of the rubber compound are strictly controlled to ensure the quality of the rubber compound.

And (3) vulcanization molding:

vulcanized rubber vulcanization conditions of physical properties measured during rubber compound formula development are as follows: x 50min at 160 deg.C

Gas hose structure

According to present domestic rubber tube processing technology and equipment current situation, the structure and the material cooperation of foreign like product are used for reference simultaneously, and the long-life indoor gas rubber tube of this project research and development adopts the three-layer to accord with structural style, and its structural design is:

(1) inner layer glue (2), middle layer glue (3) and outer layer glue

Two different material schemes were employed:

scheme A:

(1) inner layer glue: chlorohydrin rubber

(2) Middle layer glue: nitrile rubber

(3) Outer glue: neoprene/chlorinated polyethylene

Scheme B:

(1) inner layer glue: nylon coating

(2) Middle layer glue: nitrile rubber

(3) Outer glue: nitrile rubber/polyethylene

Gas hose formulation system research

The rubber or plastic material of each layer of the gas pipe provides the gas pipe with main corrosion resistance, aging resistance, air tightness and certain flexibility, and is directly related to the cost of the gas pipe. The choice of rubber or plastic material and rubber aids is therefore of great importance.

Study on inner layer adhesive formula system

Formula design of inner layer rubber of scheme A

Adopts homopolymerized chlorohydrin rubber with low air permeability, oil resistance and good heat resistance as a main raw rubber system. The metal oxide vulcanization system is used as a main vulcanization system, and the anti-aging agent is added to improve the anti-aging performance of the rubber. The polyester plasticizer softener is adopted, and fillers such as argil and talcum powder are added as fillers to ensure that the rubber material has good extrusion performance. A certain amount of formula tests are carried out to ensure that the performance of the rubber material meets the use requirement of the rubber tube.

Selection of inner rubber system

The rubber of the inner layer rubber positioned at the innermost layer of the rubber tube is directly contacted with a gas medium, and mainly plays a role in sealing and gas corrosion resistance, and the selected rubber variety has the main characteristics of good self-gas tightness, good gas corrosion resistance, good aging resistance and the like besides good comprehensive physical properties. Therefore, the chlorohydrin rubber with low air permeability, oil resistance and heat resistance is selected for the formula design, so that the air tightness, the gas resistance and the service life of the rubber tube are improved. The epichlorohydrin rubber imported from abroad and the epichlorohydrin rubber imported from China are selected for performance comparison tests.

In the same formula, chlorohydrin rubber with different brands is used as a crude rubber system, and the influence of different rubber systems on the performance of rubber compound, the physical performance of vulcanized rubber and the dielectric resistance is inspected, so that the chlorohydrin rubber which is suitable for rubber tubes and has high cost performance is screened out.

Table 2 lists the experimental formulations for selecting the chlorohydrin rubber grades. Table 3 shows the properties of the mixes of different formulations and table 4 shows the main physical properties of the vulcanised stocks of different formulations.

As can be seen from Table 3, the effect of domestic and imported epichlorohydrin rubbers on the vulcanization behaviour of the rubber mixtures was substantially similar in the two different formulations. There was no significant difference.

As can be seen from Table 4, the main physical properties of the domestic epichlorohydrin rubber and the imported epichlorohydrin rubber vulcanized rubber are close to the hardness, tensile strength, elongation at break and aging resistance of the epichlorohydrin rubber vulcanized rubber in two different formulations.

The home-made chlorohydrin rubber is similar to imported chlorohydrin rubber in performance, and home-made chlorohydrin rubber has better performance and can be used as inner rubber of a rubber tube. The selection of the home-made epichlorohydrin rubber can meet the performance requirement of the rubber tube and reduce the production cost of the rubber tube.

Epichlorohydrin rubber grade selection formula

TABLE 3 vulcanization characteristics of the mixes

Recipe number	t ₁₀ /min	t ₉₀ /min	M _L /N.m	M _H /N.m
					RQG-1	4.51	24.6	0.70	3.13
RQG-2	4.43	23.9	0.68	3.28
					RQG-3	4.21	26.0	0.72	3.17
RQG-4	4.27	26.3	0.75	3.26

TABLE 4 vulcanizate physical Properties

Selection of inner rubber vulcanization system

Metal oxides are used as the vulcanization system. And (3) investigating the influence of different vulcanization systems on the performance of the rubber compound, the vulcanization characteristic performance, the vulcanized rubber performance and the medium resistance performance. Respectively selecting vulcanizing agents such as ZnO, mgO, NA-22, DM, CZ, TT, ethylene glycol, triethanolamine and the like and accelerators, and preferably selecting a vulcanizing system suitable for the gas rubber hose.

Table 5 shows the recipe for the selection of the curing system, table 6 shows the curing characteristics of the rubber compound, and Table 7 shows the main physical properties of the vulcanizate.

It can be seen from the formulation of table 7 that, due to the particularity of the chlorohydrin rubber structure, the main chain of the polymer has no double bond, and the vulcanization system is greatly different from that of the common rubber, and the metal oxide is used as the main vulcanization system. The selection of the vulcanizing system is mainly realized by changing the dosage of the vulcanizing agent and changing the type and dosage of the accelerator. Respectively selecting magnesium oxide, zinc oxide and magnesium oxide/zinc oxide as vulcanizing agents, using NA-22 as a main accelerator and using DM, CZ, TT, ethylene glycol, triethanolamine and the like as auxiliary accelerators.

Of the six formulas, the formula RQG-8 has better comprehensive performance, namely magnesium oxide/zinc oxide is used together with a vulcanizing agent, and an accelerator is NA-22, ethylene glycol and triethanolamine are used together with relatively best vulcanizing performance. The vulcanization system thus selected is: 3 parts of magnesium oxide, 5 parts of zinc oxide, NA-22.5 parts and 2 parts of ethylene glycol.

TABLE 5 selection of cure system formulations

TABLE 6 vulcanization characteristics of the mixes

Recipe number	t ₁₀ /min	t ₉₀ /min	ML/N.m	MH/N.m
					RQG-8	4.06	23.5	0.54	3.10
RQG-9	4.13	13.10	0.53	2.57
					RQG-10	4.22	12.84	1.43	3.69

TABLE 7 physical Properties of the vulcanizates

Selection of anti-aging System

The key for prolonging the service life of rubber products is that firstly, a rubber variety with good aging resistance is selected; and secondly, an anti-aging system is optimized, and the anti-aging performance of the rubber product is improved. The selection mainly takes the protection of factors in thermal-oxidative aging into consideration. The anti-aging agents with different protection functions and different anti-aging functions such as short, medium and long-term effects are selected and used together to form a composite protection system, so that the rubber tube inner layer rubber has long-term anti-aging performance, and the service life of the rubber tube is prolonged. RD, 4020, MB, NBC and the like are selected for scientific proportioning, and a protective system with excellent performance is screened out.

Table 8 shows the formulations for which the antioxidant system was selected and Table 9 shows the main physical properties of the vulcanizates.

TABLE 8 anti-aging System selection recipe

As can be seen from Table 8, the combination of different functional antioxidants is adopted in the formula of the designed anti-aging system, and the main physical properties show that the anti-aging system has no significant influence on hardness, tensile strength at break and elongation at break, but has a large influence on the change of mechanical properties after thermo-oxidative aging, the anti-aging systems used in the formulas 15 and 17 have a small change of mechanical properties after thermo-oxidative aging, and the composite systems of 4020, MB and NBC are selected by comprehensive consideration and the addition of 1 part of each system. 4020 is p-phenylenediamine-type antioxidant with chemical name of N- (1, 3-dimethylbutyl) -N' -phenyl-p-phenylenediamine, and has good protection effect on thermal, oxygen and light aging, and can inhibit catalytic aging of harmful metals such as copper and manganese. MB is heterocyclic anti-aging agent, the chemical name is 2-mercaptobenzimidazole, which has good protection effect on thermal oxidation aging and weathering aging, and usually adopts other anti-aging agents to enhance the protection effect, NBC is light aging agent, the chemical name is nickel dibutyl dithiocarbamate, which also has obvious protection effect on solar aging. The heat resistance of the chlorohydrin rubber can be improved. NBC, MB and an anti-aging agent 4020 are used in combination in the formula 17, and excellent thermal-oxidative-aging resistance is shown.

TABLE 9 physical Properties of the vulcanizates

Selection of plasticizing systems

The rubber tube is developed by adopting an ester plasticizer or a liquid butyronitrile softener to ensure the extrusion performance of rubber compound.

Table 10 lists the plasticizing system selection formulations and Table 11 lists the major physical properties of the compounds.

TABLE 10 selection of plasticized systems

TABLE 11 physical Properties of the vulcanizates

As can be seen from Table 11, the compounds of both formulations 18 and 19 have a good overall performance, comparable to each other, and the plasticizers used in formulations 18 and 19 were chosen accordingly. Dioctyl phthalate (DOP) and dibutyl phthalate (DBP) are common plasticizers in the rubber industry, particularly in the rubber product industry, have good plasticizing effect, improve processing performance and low production cost, and can be used as plasticizers for inner layer rubber of gas rubber tubes.

3.1.1.5 rubber tube inner layer rubber formula optimization design

Through the optimization of each system of the rubber compound formula, the optimal formula of the rubber compound of the rubber hose is determined as shown in table 12, the physical performance test of vulcanized rubber is carried out on the optimal formula, and the test result is shown in table 13.

As can be seen from the experimental results in Table 13, the preferred compound has a moderate Mooney viscosity, which meets the Mooney viscosity requirements of industrial production. The vulcanized rubber has better tensile strength, elongation at break, low air permeability and good ageing resistance. Experiments prove that: the optimized inner layer rubber formula has better rubber compound performance and vulcanized rubber comprehensive physical performance, and can meet the performance requirements of the inner layer rubber of the household gas hose.

TABLE 12 preferred formulation for inner layer rubber

TABLE 13 physical Properties of the vulcanizates

B scheme inner layer design

In the scheme B, the inner layer adopts a nylon 66 (PA 66) coating as the inner layer material of the rubber tube, and the PA66 has a higher melting point. It is a semi-crystalline material. PA66 also retains greater strength and stiffness at higher temperatures. PA66 is the one with the highest mechanical strength and the widest application in the PA series. The high-strength thermoplastic elastomer has high crystallinity, so that the rigidity, the hardness and the heat resistance are high, the yield strength is higher than that of PA6, the friction coefficient is small, the wear resistance is good, the stress cracking resistance is good, and particularly the creep resistance is one of the strongest varieties in thermoplastic plastics.

The PA66 is used as the inner layer material of the rubber tube, does not need other ingredients, directly uses the PA66 for slicing, extrudes on an extruder at about 200 ℃ and is attached on the tube core.

Formula design of middle layer rubber of gas rubber hose

The middle layer rubber of the gas rubber pipe is mainly used for further improving the air tightness and medium resistance of the rubber pipe. Synthetic rubber nitrile rubber with good solvent resistance is selected as the middle layer rubber of the rubber tube, and the scheme A and the scheme B adopt the same formula of the middle layer rubber. The specific formulation is shown in Table 14. Table 15 shows the data of the rubber compound and vulcanizate properties. The test result shows that: the middle layer rubber of the gas rubber hose has good comprehensive physical properties and excellent extrusion performance, and can meet the requirements of the middle layer rubber performance of the rubber hose.

Table 14 formula table for middle layer glue of gas rubber pipe

TABLE 15 middle layer rubber sizing Properties

Formula design of outer rubber of gas rubber hose

The outer glue layer mainly functions to protect the inner glue layer from being damaged by the outside. It has high physical and mechanical performance, high ageing resistance and high ozone resistance. Rubber or plastic with good ageing resistance is selected as a main material of the rubber tube, and simultaneously, anti-aging agents capable of providing different anti-aging effects are selected to jointly form an anti-aging system, so that the ageing resistance of the rubber tube is improved.

Meanwhile, the strength of the gas pipe is improved, and the gas pipe is adhered to the inner layer of adhesive and matched with the hardness of the inner layer of adhesive. The surface of the outer adhesive layer has high smoothness and attractive appearance, different color masterbatches can be added according to needs to change the appearance color, and characters are convenient to print on the surface.

Formula design of outer layer rubber of scheme A

The scheme A adopts chloroprene rubber with good heat resistance, good weather resistance and good flame retardance to be used together with chlorinated polyethylene, and the rubber tube outer layer rubber has good comprehensive performance by matching with a proper vulcanization system, a reinforcement system, an anti-aging system and the like. Through the adjustment of the vulcanization system, the co-vulcanization of the middle and outer rubber layers is realized in the vulcanization process, and the problem of adhesion between the rubber layers is solved. The specific test formulation is shown in Table 16, and the test results are shown in Table 17.

Table 16 outer layer rubber test formula

TABLE 17 performance of outer layer rubber

As can be seen from the test results, the Chlorinated Polyethylene (CPE) is used in the outer layer rubber alone, the Mooney viscosity of the rubber compound is higher, and the extrusion performance in the rubber compound processing process is adversely affected; the vulcanized rubber has higher hardness, and the middle layer rubber has larger hardness difference, which is not beneficial to the matching of the hardness of the rubber materials. Therefore, the Chlorinated Polyethylene (CPE) is not used alone.

The outer layer rubber is prepared by combining Chlorinated Polyethylene (CPE) and Chloroprene Rubber (CR), and the CPE and the CR are used together, so that the Mooney viscosity of the rubber compound and the hardness of vulcanized rubber can meet the extrusion performance requirement of the rubber pipe and can be matched with the hardness of the middle layer rubber. The ageing resistance is good, and the physical properties of vulcanized rubber are good. And (3) synthesizing the cost performance, selecting a formula with CPE/CR and using the ratio of 40/60, and preparing a formula for the outer layer rubber in a trial mode.

Scheme B outer layer adhesive formula design

NBR and PVC which have similar polarity with the NBR of the inner layer adhesive and better bonding performance are selected and used as the outer layer adhesive material. The weather resistance, the heat aging resistance and the flame retardance of the rubber tube are ensured, and the medium resistance of the rubber tube is improved. The specific formulation is shown in Table 18. The experimental data are shown in Table 19.

Table 18 outer layer glue formula

Sizing performance of outer layer rubber of surface 19

Rubber tube sizing material formula

Through the optimization of rubber raw materials in the early stage and different formula system tests, the rubber hose sizing formula is determined. The gas rubber tube product is trial-manufactured by adopting the formula, and the performance of the rubber tube trial-manufactured product is detected. The test results show that the performance of the two rubber pipe finished products can meet the requirement of the service performance of the gas rubber pipe. The hose trial-manufacturing formula is shown in a table 20, the performance of the finished hose is shown in a table 21, and the performance of the hose material is shown in a table 22.

Table 20 rubber compound formula table

Watch 21 rubber pipe finished product performance meter

Remarking: the thickness of each layer can be 1+ -0.3 mm.

TABLE 22 hose material Performance test

Rubber tube finished product manufacturing process

Rubber mixing: rubber mixing is carried out by adopting a two-stage mixing process

First-stage mixing: 35L internal mixer

Crude rubber-white carbon black, si-69, etc. -softener, antiager, etc. -lifting block cleaning-rubber discharging-parking

And (3) second-stage mixing: 20' open mill

First-stage mother rubber-stearic acid, zinc oxide-sulfur, accelerator-thinly-opened-parked

Attention is paid to the following points:

the number of thin passing is not less than 6 times when in two-stage rubber mixing;

standing the rubber compound for more than 2-8 hours; wherein the parking time of the inner layer adhesive of the scheme A is not less than 4 hours.

The rubber tube production and processing flow comprises the following steps:

scheme A extrusion molding process:

an extrusion device: extruder NT001-4

Extrusion temperature: barrel 1:60 ℃; barrel 2:65 ℃; screw rod: 65 ℃; a machine head: at 80 ℃. The production process is carried out according to the current rubber tube factory, and three times of extrusion molding is needed because no composite extrusion equipment is available.

Vulcanizing the rubber tube: and putting the processed rubber tube blank into a vulcanizing tank, and vulcanizing according to the following conditions.

The vulcanizing tank carries out steam vulcanization, and the vulcanization pressure is 4-6kg. Vulcanization conditions are as follows: 160 ℃; the vulcanization time is 60-70 min.

Scheme B extrusion molding process:

extrusion equipment: extruder NT001-4

Extrusion temperature: barrel 1: at 40 ℃; barrel 2:50 ℃; screw rod: 40 ℃; a machine head: at 70 ℃.

It should be noted that the above embodiments can be freely combined as necessary. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A household rubber tube suitable for natural gas doped with hydrogen is characterized by sequentially comprising an inner layer rubber, a middle layer rubber and an outer layer rubber from inside to outside;

or the like, or, alternatively,

2. The household rubber tube suitable for the natural gas doped with hydrogen as claimed in claim 1, wherein the inner rubber comprises the inner rubber of chlorohydrin rubber, and comprises the following components in parts by weight:

3. the household rubber tube suitable for natural gas doped with hydrogen as claimed in claim 1, wherein the middle layer rubber comprises the following components in parts by weight:

4. the household rubber tube suitable for the natural gas doped with hydrogen as claimed in claim 1, wherein the middle layer rubber comprises neoprene/chlorinated polyethylene as the following components in parts by weight:

5. the household rubber hose suitable for natural gas-laden hydrogen as claimed in claim 1, wherein the nylon coating is nylon 66 (PA 66) coating.

6. The household rubber tube for natural gas loaded with hydrogen as claimed in claim 1,

the outer layer rubber comprises the following components in parts by weight:

7. a method for preparing the household rubber tube suitable for the natural gas loaded with hydrogen as claimed in any one of claims 1 to 6, which comprises the following steps: