CN116787867B - Multilayer flexible pipe lined with fluorine-containing layer and preparation method thereof - Google Patents

Multilayer flexible pipe lined with fluorine-containing layer and preparation method thereof Download PDF

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CN116787867B
CN116787867B CN202311070872.0A CN202311070872A CN116787867B CN 116787867 B CN116787867 B CN 116787867B CN 202311070872 A CN202311070872 A CN 202311070872A CN 116787867 B CN116787867 B CN 116787867B
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layer
fluorine
carbonization
flexible pipe
polymer
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CN116787867A (en
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耿煜
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Suzhou Yingnawei Technology Co ltd
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Suzhou Yingnawei Technology Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B32B27/322—Layered products comprising a layer of synthetic resin comprising polyolefins comprising halogenated polyolefins, e.g. PTFE
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D23/00—Producing tubular articles
    • B29D23/001—Pipes; Pipe joints
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B1/00—Layered products having a general shape other than plane
    • B32B1/08—Tubular products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/302—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/304—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/24—All layers being polymeric
    • B32B2250/246—All polymers belonging to those covered by groups B32B27/32 and B32B27/30
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B32B2307/306—Resistant to heat
    • B32B2307/3065—Flame resistant or retardant, fire resistant or retardant
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/714—Inert, i.e. inert to chemical degradation, corrosion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2597/00—Tubular articles, e.g. hoses, pipes

Abstract

The invention discloses a multilayer flexible pipe lined with a fluorine-containing layer and a preparation method thereof, wherein the multilayer flexible pipe comprises a fluorine-containing polymer lining layer a, a polymer bonding layer b and a polyolefin outer layer c, and the surfaces of the fluorine-containing polymer lining layer a and the polymer bonding layer b are respectively carbonized; the preparation method comprises the steps of sequentially preparing a fluorine-containing polymer lining layer a, a carbonization layer d, a polymer bonding layer b, a pre-carbonization layer e and a polyolefin outer layer c, and rolling to obtain a multi-layer flexible pipe finished product. According to the invention, the fluorine-containing lining layer is added in the flexible pipe, the processable and meltable fluorine-containing polymer bonding layer b is added between the fluorine-containing lining layer and the base material, and carbonization treatment of fluorine-containing materials is introduced into the flexible pipe for the first time, so that wettability of the fluorine-containing layer is improved, bonding property of the fluorine-containing layer and the base material is improved, and meanwhile, flame resistance of the flexible pipe is improved, and the obtained multilayer flexible pipe product has corrosion resistance, high mechanical property, no layering and longer service life, and has popularization significance.

Description

Multilayer flexible pipe lined with fluorine-containing layer and preparation method thereof
Technical Field
The invention relates to the technical field of flexible pipes and production thereof, in particular to a multilayer flexible pipe with a fluorine-containing lining layer and a preparation method thereof.
Background
Flexible tubing is widely used in a variety of industrial and household products. Such as filling flexible tubing for the food and beverage industry, fuel delivery flexible tubing for motor and motor of automobiles and portable tools, food contact, drinking water and liquid dairy product delivery flexible tubing, laboratory fluid delivery applications, peristaltic pump tubing applications, biopharmaceutical applications, medical tubing, and other medical tubing. Particularly for peristaltic pump tubing applications widely used in the above-mentioned fields, such peristaltic pump tubing is difficult to achieve in combination with good mechanical properties and chemical resistance during use. In particular, it is difficult to achieve both excellent mechanical properties such as rebound resilience, permanent compression set and tear resistance, and excellent chemical resistance, particularly acid and alkali resistance, soap and detergent resistance, and chemical solvent resistance such as fuel oil and lubricant resistance.
Fluid conduits having low surface energy inner surfaces are used in these industries because such fluid conduits are easy to clean, resistant to chemical attack and resistant to contamination. Generally, such low surface energy materials are mostly fluoropolymers. These fluoropolymers are used as liners for fluid conduits. However, these fluoropolymers are expensive and difficult to melt process. Many fluoropolymers that can be used as the inner surface of flexible tubing are difficult to adhere to other polymer surfaces. For example, delamination between the fluoropolymer and the substrate typically occurs when exposed to certain solvents, such as fuels. In addition, many fluoropolymers also lack flexibility, making such materials unsuitable for applications where requirements such as stress, bending radius, pressure, etc. are required. This also limits the wide range of applications of such materials in the above-mentioned fields to a large extent.
Disclosure of Invention
The invention aims to solve the defects of layering and damage caused by poor adhesion between a fluorine-containing lining layer and a base material in a flexible pipe (such as a peristaltic pump pipe) in the prior art, and provides a multilayer flexible pipe with a fluorine-containing lining layer and a preparation method thereof.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a multilayer flexible pipe lined with a fluorine-containing layer comprising, in order from the inside to the outside:
the fluoropolymer lining layer a is at least one of Polytetrafluoroethylene (PTFE) and a copolymer (THV) of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride;
a polymer adhesive layer b including a copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV) and a copolymer of tetrafluoroethylene, hexafluoropropylene and perfluoro (ethyl vinyl ether) (THP);
and a polyolefin outer layer c comprising at least one of polyolefin, styrene block copolymer and polyvinyl chloride, wherein the Shore A hardness of the polyolefin outer layer c is smaller than the Shore A hardness of the fluoropolymer lining layer a.
Preferably, the weight ratio of the polyolefin outer layer c, the polymer adhesive layer b and the fluoropolymer backing layer a is 1:0.05-0.2:0.1-0.6, and screening according to the use requirements (hardness and flexibility).
Preferably, the blend weight ratio of Polytetrafluoroethylene (PTFE) to the copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV) in the fluoropolymer backing layer a is 0-1:1, in the copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV), the weight ratio of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride is 1:0.1-0.12:0.04-0.05.
Polytetrafluoroethylene (PTFE) was purchased from Sigma-Aldrich and the copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV) was Dyneon THV 815GZ fluoroplastic.
Preferably, the weight ratio of the copolymer (THV) of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride to the copolymer (THP) of tetrafluoroethylene, hexafluoropropylene and perfluoro (ethyl vinyl ether) in the polymer adhesive layer b is 1/9 to 9, the weight content of Hexafluoropropylene (HFP) in the copolymer (THP) of tetrafluoroethylene, hexafluoropropylene and perfluoro (ethyl vinyl ether) is 6.5%, and the weight content of PEVE is 1.8%.
Preferably, the weight ratio of polyolefin, styrene block copolymer and polyvinyl chloride in the polyolefin outer layer c is 1:0-0.1:0-0.2;
the polyolefin comprises a homopolymer, copolymer, terpolymer, alloy, or any combination thereof formed from at least one olefin monomer (such as ethylene, propylene, butene, pentene, methylpentene, hexene, octene, or any combination thereof), such as polypropylene, polyethylene, ethylene copolymers, polyolefin elastomers (POE), polyolefin plastomers (POP), or combinations thereof;
styrene block copolymers, in particular at least one of styrene-ethylene-propylene-styrene block copolymers (SEPS), styrene-ethylene-propylene block copolymers (SEP), styrene-ethylene- (ethylene-propylene) -styrene block copolymers (SEEPS), styrene-isoprene-styrene block copolymers (SIS) or styrene-ethylene-butylene-styrene block copolymers (SEBS), KRATON, SEPTON, HYBRAR and sibtar are commercially available under the trademark sibtar, can provide flexible tubing with flow stability, the ethylene block copolymers being at least partially miscible with the polypropylene of the continuous phase (broadening or suppressing the Tg of either component).
Preferably, the polyolefin outer layer c of the multilayer flexible pipe also comprises mineral oil, wherein the mineral oil accounts for 20% -30% of the total weight of the polyolefin outer layer c, plays a role in lubrication and dilution, and is convenient for molding.
Preferably, a carbonized layer d is further provided between the fluoropolymer backing layer a and the polymer bonding layer b, the carbonized layer d being prepared by the following process:
1) Preparing sodium naphthalene solution:
introducing dry nitrogen into a drying container, maintaining the temperature at 15-16 ℃, adding dehydrated tetrahydrofuran, dripping distilled naphthalene, stirring for dissolution, taking out metallic sodium from kerosene, sucking the kerosene with oil absorbing paper to remove surface oxidation parts, putting into the container, stirring for 1.5-2h, and obtaining sodium naphthalene solution with the concentration of 1.2mol/L when the solution is dark green clear suspension;
2) Carbonizing:
polishing the outer surface of the fluorine-containing polymer lining layer a, cleaning the surface, drying, cooling the outer surface of the fluorine-containing polymer lining layer a to 13+/-2 ℃, coating sodium naphthalene solution, dipping for 5-7min, then flushing with high-pressure water, wherein the surface layer of the fluorine-containing polymer lining layer a is gradually changed from yellow to black, namely a carbonized layer d, the thickness is about 4-6 mu m, the water contact angle is 56-60 degrees, and the contact angle with water is gradually reduced along with the gradual increase of the carbonization degree, so that the wettability is improved. 113.5 deg. -58.4 deg..
Preferably, a pre-carbonization layer e is arranged between the polymer bonding layer b and the polyolefin outer layer c, and the carbonization treatment process of the pre-carbonization layer e is as follows: the outer surface of the polymer bonding layer b is polished, cleaned and dried, the outer surface of the polymer bonding layer b is cooled to 13+/-2 ℃, sodium naphthalene solution is smeared and soaked for 2-3min, then high-pressure water is used for washing, the surface layer of the polymer bonding layer b is gradually changed from yellow to light brown, namely a pre-carbonized layer e, the thickness is about 1-1.5 mu m, the water contact angle is 49-52 degrees, the carbonization degree of the pre-carbonized layer e is smaller than that of the carbonized layer d, but the polymer bonding layer b has better compatibility with olefin, and the surface layer after carbonization treatment is slightly alkaline (sodium hydroxide is generated by the reaction of sodium and water), so as the carbonization degree gradually increases, the contact angle firstly increases and then decreases, the final test is from 92.2 DEG to 49.5 DEG, and then increases to 54.1-57.9 DEG, namely the wettability of the carbonized surface itself has a limit, and partial carbonization is found to be more favorable for the adhesiveness of the polyolefin outer layer c and the polymer bonding layer b in the treatment process.
The invention also provides a preparation method of the multilayer flexible pipe suitable for the lining fluorine-containing layer, which comprises the following steps:
s1, mixing Polytetrafluoroethylene (PTFE) and tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride copolymer (THV) powder, melting into fluid at 270+/-5 ℃, carrying out melt extrusion, preserving heat for 10-15min after molding, cooling to 80 ℃ at room temperature, cooling by water at 25 ℃, and drying to obtain a fluoropolymer lining layer a;
s2, polishing, blowing and cleaning, sodium naphthalene solution impregnation, aqueous solution impregnation and high-pressure water flushing are sequentially carried out on the outer wall of the fluoropolymer lining layer a, the pH is tested to be 10-11 under the wet condition, and a black carbonized layer d is obtained after hot air drying;
s3, blending tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride copolymer (THV) and tetrafluoroethylene, hexafluoropropylene and perfluoro (ethyl vinyl ether) copolymer (THP) powder on the outer wall of the carbonization layer d, melting the mixture into fluid at 260+/-5 ℃, carrying out melt extrusion, preserving heat for 10-15min after molding, cooling to 80 ℃ at room temperature, cooling by water at 25 ℃, and drying to obtain a polymer bonding layer b;
s4, sequentially polishing, blowing and cleaning, impregnating with sodium naphthalene solution, impregnating with aqueous solution and flushing with high-pressure water on the outer wall of the polymer bonding layer b, testing pH at 10-11 under the wet condition, and drying with hot air to obtain a light brown transparent pre-carbonized layer e;
s5, blending the polyolefin, the styrene segmented copolymer and the polyvinyl chloride powder, melting the mixture at 120-220 ℃ (according to the adjustment of the melting point of the polymer), extruding the mixture on the outer wall of the precarbonized layer e, cooling the mixture with water at 25 ℃ after molding, drying the mixture with hot air to obtain a polyolefin outer layer c, and rolling the polyolefin outer layer c to obtain the multilayer flexible pipe finished product.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, the fluorine-containing lining layer is added in the flexible pipe of the traditional polyolefin elastomer, and the processible and meltable fluorine-containing polymer bonding layer b is added between the fluorine-containing lining layer and the base material, so that the adhesiveness between the fluorine-containing lining layer and the base material is increased;
2. furthermore, the carbonization treatment of the fluorine-containing material is introduced into the flexible pipe for the first time, the carbonization layer d and the pre-carbonization layer e are sequentially added inside and outside the fluorine-containing polymer bonding layer b by controlling carbonization parameters, so that the wettability of the fluorine-containing layer is further improved, the fluorine-containing layer can be better bonded with a base material during fluid extrusion, and the flame resistance of the flexible pipe is simultaneously improved, and the obtained multi-layer flexible pipe product has corrosion resistance, high mechanical property and longer service life and has popularization significance.
Drawings
FIG. 1 is a schematic view of a multilayer flexible pipe lined with a fluorine-containing layer according to the present invention;
fig. 2 is a schematic structural diagram of a carbonization apparatus used in the method for preparing a multilayer flexible tube lined with a fluorine-containing layer according to the present invention shown in fig. 1.
In the figure: a fluoropolymer lining layer a, a polymer bonding layer b, a polyolefin outer layer c, a carbonization layer d and a pre-carbonization layer e; a grinding cylinder 1, a blower 2, a carbonization cylinder 3, V-shaped annular grooves 301, -shaped annular grooves 302, a sodium naphthalene solution supply pipe 303, a pure water solution supply pipe 304, a high-pressure water spray head 4 and a core rod 5.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments.
1. Preparation of a multilayer flexible tube:
referring to fig. 1, a multilayer flexible pipe lined with a fluorine-containing layer comprises, in order from the inside to the outside:
the fluoropolymer lining layer a is at least one of Polytetrafluoroethylene (PTFE) and a copolymer (THV) of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride;
a polymer adhesive layer b including a copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV) and a copolymer of tetrafluoroethylene, hexafluoropropylene and perfluoro (ethyl vinyl ether) (THP);
and a polyolefin outer layer c comprising at least one of polyolefin, styrene block copolymer and polyvinyl chloride, wherein the Shore A hardness of the polyolefin outer layer c is smaller than the Shore A hardness of the fluoropolymer lining layer a.
Wherein, the weight ratio of the polyolefin outer layer c to the polymer bonding layer b to the fluorine-containing polymer lining layer a is 1:0.05-0.2:0.1-0.6, and screening according to the use requirements (hardness and flexibility).
Wherein the weight ratio of polyolefin, styrene block copolymer and polyvinyl chloride in the polyolefin outer layer c is 1:0-0.1:0-0.2;
the polyolefin comprises a homopolymer, copolymer, terpolymer, alloy, or any combination thereof formed from at least one olefin monomer (such as ethylene, propylene, butene, pentene, methylpentene, hexene, octene, or any combination thereof), such as polypropylene, polyethylene, ethylene copolymers, polyolefin elastomers (POE), polyolefin plastomers (POP), or combinations thereof;
the styrene block copolymer is specifically at least one of styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-propylene block copolymer (SEP), styrene-ethylene- (ethylene-propylene) -styrene block copolymer (SEEPS), styrene-isoprene-styrene block copolymer (SIS) or styrene-ethylene-butylene-styrene block copolymer (SEBS), KRATON, SEPTON, HYBRAR and sibtar trademarks are commercially available.
Wherein the weight ratio of copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV) to copolymer of tetrafluoroethylene, hexafluoropropylene and perfluoro (ethyl vinyl ether) (THP) in the polymer adhesive layer b is 1/9-9, the weight content of Hexafluoropropylene (HFP) in the copolymer of tetrafluoroethylene, hexafluoropropylene and perfluoro (ethyl vinyl ether) (THP) is 6.5%, the weight content of PEVE is 1.8%, the MFR is 22g/10min as measured by the method of ASTM D1238 at 372 ℃ and 5kg load, the "melt processible fluoropolymer composition" of patent publication No. CN1553935A is referred to prepare "TFE/HFP-3", i.e. "TFE/HFP-3 is a terpolymer of TFE, HFP and PEVE";
wherein the blend weight ratio of Polytetrafluoroethylene (PTFE) to the copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV) in the fluoropolymer lining layer a is 0-1:1.
wherein, a carbonization layer d is arranged between the fluoropolymer lining layer a and the polymer bonding layer b, and the carbonization layer d is prepared by the following steps:
1) Preparing sodium naphthalene solution:
introducing dry nitrogen into a drying container, maintaining the temperature at 15-16 ℃, adding dehydrated tetrahydrofuran, dripping distilled naphthalene, stirring for dissolution, taking out metallic sodium from kerosene, sucking the kerosene with oil absorbing paper to remove surface oxidation parts, putting into the container, stirring for 1.5-2h, and obtaining sodium naphthalene solution with the concentration of 1.2mol/L when the solution is dark green clear suspension;
2) Carbonizing:
polishing the outer surface of the fluorine-containing polymer lining layer a, cleaning the surface, drying, cooling the outer surface of the fluorine-containing polymer lining layer a to 13+/-2 ℃, coating sodium naphthalene solution, dipping for 5-7min, then flushing with high-pressure water, wherein the surface layer of the fluorine-containing polymer lining layer a is gradually changed from yellow to black, namely a carbonized layer d, the thickness is about 4-6 mu m, the water contact angle is 56-60 degrees, and the contact angle with water is gradually reduced along with the gradual increase of the carbonization degree, so that the wettability is improved. 113.5 deg. -58.4 deg..
Wherein, be equipped with between polymer adhesive linkage b and the polyolefin skin c and pre-carbonize layer e, pre-carbonize layer e's carbonization treatment process is: the outer surface of the polymer bonding layer b is polished, cleaned and dried, the outer surface of the polymer bonding layer b is cooled to 13+/-2 ℃, sodium naphthalene solution is smeared and soaked for 2-3min, then high-pressure water is used for washing, the surface layer of the polymer bonding layer b is gradually changed from yellow to light brown, namely a pre-carbonized layer e, the thickness is about 1-1.5 mu m, the water contact angle is 49-52 DEG, the carbonization degree of the pre-carbonized layer e is smaller than that of the carbonized layer d, but the polymer bonding layer b has better compatibility with olefin, and the surface layer after carbonization treatment is slightly alkaline (sodium hydroxide is generated by the reaction of sodium and water), so as the carbonization degree gradually increases, the contact angle is firstly increased and then reduced, the final test is sequentially changed from 92.2 DEG, 49.5 DEG, 54.1 DEG to 57.9 DEG, namely the wettability of the carbonized surface itself is limited, and partial carbonization is found to be more favorable for the adhesiveness of the polyolefin outer layer c and the polymer bonding layer b in the treatment process.
The invention also provides a preparation method of the multilayer flexible pipe suitable for the lining fluorine-containing layer, which comprises the following steps:
s1, mixing Polytetrafluoroethylene (PTFE) and tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride copolymer (THV) powder, melting into fluid at 270+/-5 ℃, carrying out melt extrusion, preserving heat for 10-15min after molding, cooling to 80 ℃ at room temperature, cooling by water at 25 ℃, and drying to obtain a fluoropolymer lining layer a;
s2, polishing, blowing and cleaning, sodium naphthalene solution impregnation, aqueous solution impregnation and high-pressure water flushing are sequentially carried out on the outer wall of the fluoropolymer lining layer a, the pH is tested to be 10-11 under the wet condition, and a black carbonized layer d is obtained after hot air drying;
s3, blending tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride copolymer (THV) and tetrafluoroethylene, hexafluoropropylene and perfluoro (ethyl vinyl ether) copolymer (THP) powder on the outer wall of the carbonization layer d, melting the mixture into fluid at 260+/-5 ℃, carrying out melt extrusion, preserving heat for 10-15min after molding, cooling to 80 ℃ at room temperature, cooling by water at 25 ℃, and drying to obtain a polymer bonding layer b;
s4, sequentially polishing, blowing and cleaning, impregnating with sodium naphthalene solution, impregnating with aqueous solution and flushing with high-pressure water on the outer wall of the polymer bonding layer b, testing pH at 10-11 under the wet condition, and drying with hot air to obtain a light brown transparent pre-carbonized layer e;
s5, blending the polyolefin, the styrene segmented copolymer and the polyvinyl chloride powder, melting the mixture at 120-220 ℃ (according to the adjustment of the melting point of the polymer), extruding the mixture on the outer wall of the precarbonized layer e, cooling the mixture with water at 25 ℃ after molding, drying the mixture with hot air to obtain a polyolefin outer layer c, and rolling the polyolefin outer layer c to obtain the multilayer flexible pipe finished product.
2. Recipe test:
according to the preparation methods described above, examples 1 to 13 and comparative examples 1 to 9 were each subjected to a single-factor test as shown in Table 1:
TABLE 1 formulation table for multilayer flexible tube
3. Performance test:
comparative example 10 was set: the polymer adhesive layer b and the fluoropolymer lining layer a are abandoned, and a polyolefin outer layer c with the same thickness as the finished product of the multi-layer flexible pipe in the embodiment 4 is directly used as a blank product of the flexible pipe;
set example 14: mineral oil is added into the polyolefin outer layer c of the example 4, wherein the mineral oil accounts for 20 percent of the total weight of the polyolefin outer layer c, and the other polymer components in the polyolefin outer layer c are reduced in equal proportion;
setting example 15: mineral oil is added into the polyolefin outer layer c of the example 4, the mineral oil accounts for 25 percent of the total weight of the polyolefin outer layer c, and the equal proportion of other polymer components in the polyolefin outer layer c is reduced;
set example 16: mineral oil is added into the polyolefin outer layer c of the example 4, wherein the mineral oil accounts for 30 percent of the total weight of the polyolefin outer layer c, and the equal proportion of other polymer components in the polyolefin outer layer c is reduced;
the flexible tubes of examples 1-16 and comparative examples 1-10 were prepared as peristaltic pump tubes, respectively, standard No. 17 tube having a length of 40 cm, an inner diameter of 6.35 mm and an outer diameter of 9.53 mm was used, 2000 ml of aqueous sodium hydroxide solution having a pH of 13.5 was used as a medium, and the tube was run on a peristaltic pump using a YZ15 standard pump head at 600rpm at room temperature and an outlet pressure of 1.5 bar, and the flow rate attenuation, the service life, the running time in which delamination occurred between the polymer adhesive layer b or the fluoropolymer liner layer a and the polyolefin outer layer c were tested, and flame retardant properties were tested;
service life, according to the foregoing conditions, a standard number 17 tube with a length of 40 cm, an inner diameter of 6.35 mm and an outer diameter of 9.53 mm is taken, under the condition that a sodium hydroxide aqueous solution with a pH value of 13.5 is used as a medium, the outlet pressure is 1.5 bar and the back pressure is 1 bar, the flow attenuation change result is tested after the peristaltic pump with a YZ15 standard pump head at 600rpm is operated for 500 hours, and the service life is considered to be expired when the flow attenuation is below 20% of the initial flow.
Flame retardant performance test: the external wall of the flexible pipe of examples 1-16 and comparative examples 1-10 is subjected to open flame combustion performance test by reference to GB/T8626-88 method for testing the flammability of building materials, and the obtained grades are A (incombustible), B1 (nonflammable), B2 (flammable) and B3 (flammable) respectively from high to low; the polyolefin outer layer c in each example and comparative example was tested for the B2 flammability rating, i.e., the flame resistance of the polymer adhesive layer B or fluoropolymer backing layer a, which reached the a flammability rating due to the presence of the carbonized layer d and pre-carbonized layer e, and even if the tube was exposed to an open flame, it would not leak out and cause corrosive fluid to overflow and destroy the workshops;
since the flexible tubes of examples 1-16 and comparative examples 1-10 all use the polyolefin outer layer c as the outer layer, the shore hardness a is 65-75, so the significance of the test of shore hardness is not great, and the test of tear strength (according to standard astm d624B/23 ℃/t=2mm) and permanent compression set (astm d395, 22h after 70 ℃);
examples 1-16 were run continuously at 600r/min peristaltic pump speed for 200 hours without delamination and without cracking of each layer.
The specific properties are shown in table 2 below:
TABLE 2 Performance test of multilayer Flexible tubes
In comparison with examples 1 to 6 and comparative example 1, the PTFE content in the fluoropolymer backing layer a gradually increases, and when the specific gravity of PTFE is too high, the meltability is poor, and PTFE powder is not uniformly distributed in the extrusion liquid, resulting in poor mechanical properties, wherein in example 4, PTFE: THV is 0.4:1, the obtained product has the highest performance.
From comparative examples 2, 7, 8, 4, 9, 10 to 3, the THV content of the polymer adhesive layer b gradually increased, and the products obtained in comparative examples 2 and 3 still had delamination and the rest did not delaminate, wherein the peeling resistance was optimized in example 4;
the blended products of PP-SEPS-PVC from examples 11-12 have better flexibility than example 4;
compared with comparative examples 4-5 and example 4, the lack of SEPS and PVC greatly reduces the toughness strength of the polyolefin outer layer c, and simultaneously greatly increases the permanent compression set, which is unfavorable for normal peristaltic pump operation;
in example 4, the weight ratio of the polyolefin outer layer c, the polymer adhesive layer b, and the fluoropolymer backing layer a was 1:0.1:0.45, wherein the thickness of the fluorine-containing polymer lining layer a can be curled into a pipe (the hardness is 75 Shore A, the deflection is smaller than that of a PP pipe), and the subsequent extrusion process is immediately carried out after the fluorine-containing polymer lining layer a is molded; when the polymer adhesive layer b is completely removed, as in comparative example 6, the pre-carbonized layer e is not provided correspondingly, the adhesive effect is poor, the peeling resistance coefficient is low, and delamination is easy to occur; when the fluoropolymer lining layer a is reduced at least, as in comparative example 7, the fluoropolymer lining layer a is thinner, is easy to break and is unfavorable for subsequent processing, so the weight ratio of the fluoropolymer lining layer a to the polyolefin outer layer c is more than or equal to 0.1:1 (example 13); however, when the fluoropolymer lining layer a is added to a plurality of layers (the weight ratio of the fluoropolymer lining layer a to the polyolefin outer layer c is more than 0.6:1), the flexibility of the flexible pipe is seriously affected, so that the flexible pipe is not adopted;
the absence of the carbonized layer d and the pre-carbonized layer e caused the decrease in the adhesiveness of the polyolefin outer layer c to the fluoropolymer backing layer a, which was liable to occur delamination in use, compared with example 4 from comparative examples 8 to 9.
4. Improvement of carbonization equipment:
example 17:
for the special carbonization equipment provided in the embodiments 1-16, referring to fig. 2, the special carbonization equipment comprises a polishing cylinder 1, a blower 2, a carbonization cylinder 3, a high-pressure water spray nozzle 4 and a core rod 5, wherein the polishing cylinder is arranged outside a fluorine-containing polymer lining layer a, the core rod 5 is arranged in the fluorine-containing polymer lining layer a, the inner wall of the carbonization cylinder 3 is attached to the fluorine-containing polymer lining layer a, V-shaped annular grooves 301 and -shaped annular grooves 302 are formed in the inner wall of the carbonization cylinder 3, the V-shaped annular grooves 301 are communicated with a sodium naphthalene solution supply pipe 303 to form a relatively airtight carbonization reaction cavity, the -shaped annular grooves 302 are communicated with a pure water solution supply pipe 304 to form a relatively airtight sodium water reaction cavity, and dangers are avoided.
The outer wall of the fluorine-containing polymer lining layer a is polished by rotating the polishing cylinder 1 (axial reciprocating motion can be added), sodium naphthalene solution enters the V-shaped annular groove 301 to carry out surface carbonization reaction on the fluorine-containing polymer lining layer a, and aqueous solution enters the -shaped annular groove 302 to react with residual sodium naphthalene solution on the surface of the fluorine-containing polymer lining layer a.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims (2)

1. A multilayer flexible pipe lined with a fluorine-containing layer, comprising, in order from the inside to the outside:
a fluoropolymer lining layer a, which is formed by mixing 1.48kg of PTFE and 3.7kg of THV;
the polymer adhesive layer b is formed by mixing 0.57kg of THV and 0.57kg of THP;
a polyolefin outer layer c which is formed by mixing 10kg of PP, 0.5kg of SEPS and 1kg of PVC, wherein the Shore A hardness of the polyolefin outer layer c is smaller than that of the fluoropolymer lining layer a;
a carbonization layer d is further arranged between the fluoropolymer lining layer a and the polymer bonding layer b, the thickness of the carbonization layer d is 5.37 mu m, and the carbonization layer d is prepared through the following process:
1) Preparing sodium naphthalene solution:
introducing dry nitrogen into a drying container, maintaining the temperature at 15-16 ℃, adding dehydrated tetrahydrofuran, dripping distilled naphthalene, stirring for dissolution, taking out metallic sodium from kerosene, sucking the kerosene with oil absorbing paper to remove surface oxidation parts, putting into the container, stirring for 1.5-2h, and obtaining sodium naphthalene solution with the concentration of 1.2mol/L when the solution is dark green clear suspension;
2) Carbonizing:
polishing the outer surface of the fluorine-containing polymer lining layer a, cleaning the surface, drying, cooling the outer surface of the fluorine-containing polymer lining layer a to 13+/-2 ℃, coating sodium naphthalene solution, dipping for 5-7min, and then flushing with high-pressure water, wherein the surface layer of the fluorine-containing polymer lining layer a is gradually changed from yellow to black to obtain a carbonized layer d;
the carbonization equipment used for carbonization treatment comprises a polishing cylinder (1), a blower (2), a carbonization cylinder (3) and a high-pressure water spray head (4) which are arranged outside a fluorine-containing polymer lining layer a, a core rod (5) which is arranged in the fluorine-containing polymer lining layer a, wherein the inner wall of the carbonization cylinder (3) is attached to the fluorine-containing polymer lining layer a, a V-shaped annular groove (301) and a -shaped annular groove (302) are formed in the inner wall of the carbonization cylinder (3), the V-shaped annular groove (301) is communicated with a sodium naphthalene solution supply pipe (303) to form a relatively airtight carbonization reaction cavity, and the -shaped annular groove (302) is communicated with a pure water solution supply pipe (304) to form a relatively airtight sodium water reaction cavity, so that dangers are avoided;
the outer wall of the fluoropolymer lining layer a is polished by rotating the polishing cylinder (1), sodium naphthalene solution enters a V-shaped annular groove (301) to carry out surface carbonization reaction on the fluoropolymer lining layer a, and aqueous solution enters a -shaped annular groove (302) to carry out reaction on the residual sodium naphthalene solution on the surface of the fluoropolymer lining layer a;
a pre-carbonization layer e is arranged between the polymer bonding layer b and the polyolefin outer layer c, the thickness of the pre-carbonization layer e is 1.33 mu m, and the carbonization treatment process of the pre-carbonization layer e is as follows: polishing the outer surface of the polymer bonding layer b, cleaning the surface, drying, cooling the outer surface of the polymer bonding layer b to 13+/-2 ℃, coating sodium naphthalene solution, soaking for 2-3min, and then flushing with high-pressure water, wherein the surface layer of the polymer bonding layer b gradually changes from yellow to light brown, namely the pre-carbonized layer e.
2. A method of preparing a multilayer flexible pipe lined with a fluorine-containing layer as claimed in claim 1, comprising the steps of:
s1, mixing PTFE and THV powder, melting into fluid at 270+/-5 ℃, performing melt extrusion, preserving heat for 10-15min after molding, cooling to 80 ℃ at room temperature, cooling by water at 25 ℃, and drying to obtain a fluoropolymer lining layer a;
s2, polishing, blowing and cleaning, sodium naphthalene solution impregnation, aqueous solution impregnation and high-pressure water flushing are sequentially carried out on the outer wall of the fluoropolymer lining layer a, the pH is tested to be 10-11 under the wet condition, and a black carbonized layer d is obtained after hot air drying;
s3, blending THV and THP powder on the outer wall of the carbonized layer d, melting the mixture into fluid at 260+/-5 ℃, performing melt extrusion, preserving heat for 10-15min after molding, cooling to 80 ℃ at room temperature, cooling by water at 25 ℃, and drying to obtain a polymer bonding layer b;
s4, sequentially polishing, blowing and cleaning, impregnating with sodium naphthalene solution, impregnating with aqueous solution and flushing with high-pressure water on the outer wall of the polymer bonding layer b, testing pH at 10-11 under the wet condition, and drying with hot air to obtain a light brown transparent pre-carbonized layer e;
s5, blending PP, SEPS and PVC powder, melting at 120-220 ℃, extruding the mixture on the outer wall of the pre-carbonized layer e, cooling the mixture with water at 25 ℃ after molding, drying the mixture with hot air to obtain a polyolefin outer layer c, and rolling the polyolefin outer layer c to obtain the multi-layer flexible pipe finished product.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005188739A (en) * 2004-10-26 2005-07-14 Mitsuboshi Co Ltd Multilayer tube
CN101074298A (en) * 2007-05-28 2007-11-21 陈仕明 Formulation of naphthalene-sodium treating fluid and treatment of polytetrafluoroethylene product
CN113785150A (en) * 2019-05-22 2021-12-10 美国圣戈班性能塑料公司 Multilayer flexible pipe and method for manufacturing same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005188739A (en) * 2004-10-26 2005-07-14 Mitsuboshi Co Ltd Multilayer tube
CN101074298A (en) * 2007-05-28 2007-11-21 陈仕明 Formulation of naphthalene-sodium treating fluid and treatment of polytetrafluoroethylene product
CN113785150A (en) * 2019-05-22 2021-12-10 美国圣戈班性能塑料公司 Multilayer flexible pipe and method for manufacturing same

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