Chemically resistant polyurethane composite hose and method of making same

Abstract

The present application belongs to the technical field of flexible pipe material for fluid transportation, and discloses a chemical-resistant polyurethane composite hose and a preparation method thereof. The preparation method comprises the steps of reinforcing layer structure design and braiding, polyurethane blend pre-homogenization and dehumidification drying, co-extrusion composite molding, cooling and stress release, and finished product quality determination. Through the matching design of the reinforcing layer braiding parameters and the melt wettability, the inner and outer layer polyurethane, and the bidirectional wettability co-extrusion process, the chemical resistance and flexibility of the hose are improved, and the system stability is ensured through the drying and cooling process, and the residual stress of the finished product is reduced. The hose prepared by the present application has high interlayer bonding strength, excellent hydrolysis resistance and hydrogen sulfide resistance, and is suitable for corrosive medium transportation scenes.

Description

Technical Field

[0001] This invention belongs to the field of flexible tubing technology for fluid transportation, specifically relating to a chemical-resistant polyurethane composite hose and its preparation method. Background Technology

[0002] Polyurethane elastomers, with their excellent flexibility, abrasion resistance, and processability, have become the core material for fluid transport hoses. Among them, polyether-type polyurethane and polycarbonate-type polyurethane are the two most widely used raw materials in industrial applications. Polyether-type polyurethane molecules contain a large number of ether bonds, which endows them with outstanding flexibility, hydrolysis resistance, and low cost advantages, and they are widely used in conventional working condition hoses, seals, and other products. However, the chemical stability of ether bonds is poor, and they are easily corroded by corrosive media such as acids, alkalis, and organic solvents, leading to rapid swelling, cracking, and strength loss of the material, which cannot meet the long-term use requirements of harsh environments such as chemical transportation, medical fluids, and oil and gas extraction. Polycarbonate-based polyurethanes contain rigid carbonate bonds in their main chain, which can significantly improve the material's chemical resistance, mechanical strength, and heat resistance, making them suitable for high-requirement corrosive media transportation scenarios. However, they have some insurmountable application drawbacks: First, the raw material cost is high, 2 to 4 times that of polyether-based polyurethanes, which significantly increases the product's production cost. Second, they have poor processing performance, with high melt viscosity, requiring high temperature and pressure (200-220℃) for extrusion molding, which easily leads to thermal degradation and discoloration of the material, while also aggravating equipment wear and tear, making it difficult to achieve large-scale industrial production.

[0003] There is an irreconcilable contradiction between performance and cost in single polyurethane materials: pure polyether polyurethane has insufficient chemical resistance and cannot be adapted to harsh working conditions; pure polycarbonate polyurethane is limited by cost and processing bottlenecks, making it difficult to replace polyether polyurethane as the mainstream.

[0004] Existing technologies attempt to compensate for the defects of single materials through blending and composite structures, but several technical shortcomings still exist in hose manufacturing and application: First, the blending formulation lacks differentiated design, with the inner and outer layers using the same ratio, resulting in either insufficient overall chemical resistance or excessively high overall rigidity and loss of flexibility; Second, the reinforcing layer is designed with braiding parameters only based on pressure bearing capacity, ignoring the matching between pore structure and melt wetting, preventing the melt from deeply embedding into the reinforcing layer, resulting in low interlayer peel strength and easy delamination and bulging after long-term use; Third, co-extrusion molding only achieves unidirectional coverage, failing to form bidirectional wetting and intersection of inner and outer melts, leading to an imbalance in interfacial bonding force; Fourth, the hose is directly and rapidly cooled after demolding, resulting in inconsistent thermal shrinkage between the inner and outer layers and the reinforcing layer, causing residual stress concentration, making it prone to cracking and dimensional shrinkage during bending. Summary of the Invention

[0005] The technical problems to be solved by the present invention include at least one of the following: the poor matching between the reinforcing layer and the melt wetting of existing polyurethane hoses, poor dispersion uniformity of the blended system, resulting in insufficient batch stability, poor interlayer bonding stability, inability to balance chemical resistance and flexibility, and high residual stress leading to short service life.

[0006] To address the aforementioned technical problems, the present invention provides the following technical solutions.

[0007] A chemical-resistant polyurethane composite hose comprises, from the inside out, an inner rubber layer, a reinforcing layer, and an outer rubber layer, wherein the inner rubber layer, the reinforcing layer, and the outer rubber layer are formed into an integrated structure by co-extrusion bidirectional impregnation and embedding; the inner rubber layer and the outer rubber layer adopt the same physical blending ratio of polyether polyurethane and polycarbonate polyurethane, wherein the mass proportion of polycarbonate polyurethane is 10% to 40%; the reinforcing layer is a tubular skeleton layer formed by cross-weaving of warp and weft yarns.

[0008] A method for preparing a chemical-resistant polyurethane composite hose includes the following steps:

[0009] Step 1: Design and weave a tubular reinforcing layer, wherein the weaving structure of the reinforcing layer matches the wetting depth of the subsequent co-extrusion melt;

[0010] Step 2: The blends of polyether polyurethane and polycarbonate polyurethane with the same ratio are pre-homogenized and uniformly dehumidified and dried.

[0011] Step 3: The treated blend is co-extruded and composite molded to control the viscosity of the inner and outer melts so that the inner and outer melts are bidirectionally impregnated and combined in the reinforcing layer.

[0012] Step four: Perform segmented cooling and shaping on the co-extruded hose and release internal residual stress.

[0013] In one embodiment of the present invention, the warp and weft of the reinforcing layer (2) are made of one or more of polyester filament, nylon filament, and aramid.

[0014] In one embodiment of the present invention, the interlayer peel strength between the inner adhesive layer and the reinforcing layer, and between the outer adhesive layer and the reinforcing layer, is not less than 80 N / 25 mm.

[0015] In one embodiment of the present invention, step one specifically includes: determining the braiding angle and braiding density of the reinforcing layer according to the inner diameter, working pressure and minimum bending radius of the hose; forming a tubular reinforcing layer by braiding selected warp and weft yarns; and performing low-tension sizing treatment and surface cleaning treatment on the braided reinforcing layer, wherein the low-tension sizing treatment is based on maintaining the natural fluffiness of the yarns.

[0016] In one embodiment of the present invention, polyether-type polyurethane masterbatch and polycarbonate-type polyurethane masterbatch are directly mixed in a set ratio, and then the mixture is subjected to uniform dehumidification and drying treatment, wherein the uniform drying process is maintained at 80°C to 95°C for 4 to 6 hours.

[0017] In one embodiment of the present invention, in step two, the inner layer blend and the outer layer blend are materials with the same proportion, and the mass percentage of polycarbonate-type polyurethane in the blend is 10% to 40%.

[0018] In one embodiment of the present invention, step three specifically includes: inserting the reinforcing layer through the outer periphery of the core of the co-extrusion die with constant tension, and molten extruding the blended material with the same proportion, so that an inner melt layer is formed on the surface of the core and an outer melt layer is formed on the outside of the reinforcing layer, and the melt penetrates into the pores of the reinforcing layer in both directions and merges and combines.

[0019] In one embodiment of the present invention, step four specifically includes: passing the co-extruded hose through a mild cooling zone and a reinforced cooling zone for segmented cooling; during the cooling process, a light support and shaping device is used to maintain the roundness of the hose cross-section; and the cooled hose is operated under low tension to redistribute internal stress.

[0020] In one embodiment of the present invention, step five is further included: quality assessment of the cooled and shaped hose.

[0021] Compared with the prior art, the present invention has the following significant advantages:

[0022] By employing a design with the same ratio for both inner and outer layers, and leveraging the chemical stability of carbonate bonds, the hose's resistance to corrosive media such as acids, alkalis, organic solvents, hydrolysis, and hydrogen sulfide is significantly enhanced. Experimental data shows that the hose of this invention retains up to 89.5% of its hydrolytic tensile strength and up to 95.7% of its hydrogen sulfide tensile strength, both significantly better than pure polyether polyurethane hoses, allowing for stable long-term use in harsh chemical environments.

[0023] By optimizing the formula, the overall proportion of polycarbonate-type polyurethane is controlled to within 40%. While ensuring that the chemical resistance meets the standards, the cost is significantly reduced compared to pure polycarbonate-type polyurethane materials. This balances the contradiction between high performance and low cost, and has economic advantages for large-scale industrial applications.

[0024] After blending with the same ratio, the melt flow rate (MFR) increases to 8~15g / 10min, which is much higher than that of pure polycarbonate polyurethane (MFR<10g / 10min). The melt flow is compatible with conventional extrusion processes, eliminating the need for high-temperature and high-pressure processing above 200℃, avoiding material thermal degradation and excessive equipment wear, and significantly improving processing stability and yield.

[0025] The braiding parameters of the reinforcing layer are precisely matched with the melt wetting depth. Combined with single co-extrusion and bidirectional wetting, the melt intersects and embeds within the reinforcing layer. The interlayer peel strength is ≥80N / 25mm, with no braid texture development or interlayer peeling issues. The segmented cooling and low-tension stress release process eliminates internal residual stress, resulting in stable hose dimensions, bend resistance, and no shrinkage or cracking after long-term use.

[0026] The unified dehumidification, drying, and pre-homogenization process solves the phase separation and processing fluctuation problems caused by differences in thermal history and moisture content between the two types of polyurethane. The product has small performance deviation between batches and is suitable for continuous industrial production. Attached Figure Description

[0027] Figure 1 A schematic diagram of the cross-sectional structure of the chemical-resistant polyurethane composite hose provided by the present invention.

[0028] The labels for each figure are as follows: 1: outer adhesive layer; 2: reinforcing layer; 3: inner adhesive layer. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] In a first embodiment of the present invention, a method for preparing a chemical-resistant polyurethane composite hose is provided, the method comprising the following steps:

[0032] Step 1: Design the structure and braided tubular shape of the reinforcement layer.

[0033] Step two: process the blended material according to the same ratio, pre-homogenize and uniformly dry it.

[0034] Step 3: Single co-extrusion composite molding and control of the viscosity relationship between the inner and outer layers.

[0035] Step four: Cool and shape the hose and release residual stress.

[0036] Preferably, the method further includes step five: performing a quality assessment.

[0037] In the above steps, step one determines the pore structure of the reinforcing skeleton and the basic conditions for being wetted by the melt; step two determines the moisture content of the blend, the stability of the melt viscosity, and the uniformity of the phase distribution; step three is the key to achieving the integral molding of the outer adhesive layer, the reinforcing layer, and the inner adhesive layer; step four is used to stabilize the dimensions and prevent stress concentration at the interface; and step five is used to verify whether the aforementioned steps have jointly achieved the expected effect.

[0038] The following provides a detailed explanation of each step and its sub-steps.

[0039] The purpose of step one is to construct a tubular reinforcing skeleton that can provide compressive strength and form a stable anchor with the polyurethane melt of the same proportion.

[0040] Step one further includes the following steps:

[0041] Step 1-1: Select the warp and weft materials according to the hose's intended use. The warp and weft can be made of one or more of polyester filament, nylon filament, and aramid fiber. For hoses where flexibility and cost control are paramount, polyester or nylon filament is preferred; for hoses requiring higher pressure resistance and fatigue resistance, aramid fiber can be introduced into the weft. The linear density of the reinforcing filaments should ideally be controlled within a relatively stable range, ensuring that after weaving, the melt does not penetrate excessively due to an overly loose skeleton, nor does the melt fail to enter the gaps between the filaments due to an overly dense skeleton.

[0042] Steps 1-2: Determine the braiding density and braiding angle, and perform braiding. Based on the hose's inner diameter, working pressure, and minimum bending radius, calculate and determine the braiding angle and braiding density of the reinforcing layer. The braiding angle should be controlled within a range that allows the reinforcing layer to simultaneously possess axial stability and circumferential pressure resistance. If the braiding angle is too small, the axial rigidity is too high, but the circumferential pressure resistance is insufficient; if the braiding angle is too large, the circumferential pressure resistance is improved, but it is prone to causing local wrinkling during bending. To ensure wettability, the number of intersections per unit length of the reinforcing layer should not be too dense; otherwise, the polyurethane melt will have difficulty forming continuous penetration channels.

[0043] Schematic, the braiding angle is selected based on the hose's inner diameter Dᵢ, working pressure P, and minimum bending radius R. min Interlayer peel strength ≥80N / 25mm.

[0044] First, calculate the required fiber cross-sectional density A′ per meter of axial direction. f =η·P·Dᵢ / (2·σ f,ult ), where η is the pressure distribution coefficient, taken as 0.7, σ f,ult It represents the ultimate tensile strength of a single fiber.

[0045] Subsequently, the geometric relationship λ=2·A′ woven in two directions ±α was used. f / (a f·tanα), where λ is the total number of intersections per meter, a f The cross-sectional area of ​​a single fiber is given, and λ is converted to the number of intersections per 10 mm (λ / 10).

[0046] Given that 35% ≤ C = 2·n·a f ·cosα / (π·D o Provided that λ ≤ 55%, adjust α to make λ fall within the target range for the corresponding working condition. Where, D o is the outer diameter of the hose (target diameter), and n is the total number of yarns in the circumferential direction of the hose (i.e., the total number of fiber yarns evenly distributed along the circumference of the hose when weaving the reinforcing layer).

[0047] The following is an illustrative scenario:

[0048] Small-diameter low-pressure flexible (D) i =10mm, P=0.6MPa, R min =20mm): A′ f ≈8mm² / m, taking α=52° (50°~55°), we get λ≈8~10 / 10mm, the intersections are sparse, the pore size is ≈1mm, the hose is flexible and has good permeability.

[0049] Medium caliber, medium pressure general purpose (D) i =25mm, P=1.6MPa, R min =50mm): A′ f With a diameter of approximately 15 mm² / m, the equilibrium angle α is calculated to be 54°44′ (approximately 54.7°), λ is approximately 10⁻¹² / 10 mm, the axial stiffness is basically equal to the circumferential bearing capacity, the pore size is approximately 0.9 mm, and the PU melt can continuously penetrate.

[0050] Large-diameter high-pressure rigid (D) i =50mm, P=4.0MPa, R min =150mm): A′ f With a diameter of approximately 30 mm² / m, and α = 58° (55°~60°), and λ ≈ 12~14 / 10 mm, sufficient circumferential bearing strength is provided, while the pore size remains approximately 0.7 mm, ensuring continuous permeation channels.

[0051] Subsequently, using selected warp and weft threads, the threads are woven according to calculated parameters to form a tubular reinforcing layer with a specific pore structure.

[0052] Steps 1-3: Low-tension sizing treatment of the braided reinforced tube. The braided tubular reinforcing layer undergoes pre-shaping to ensure consistent roundness, straightness, and initial tension. Pre-shaping can be performed using low-tension sizing, prioritizing maintaining the natural fluffiness of the filament bundle rather than hot compaction. This is because if the braided layer is over-compacted before entering the co-extrusion die, its internal pores will be significantly reduced, hindering the subsequent mechanical interlocking of the inner and outer melts.

[0053] Steps 1-4: Perform surface cleaning treatment on the reinforcing layer to remove residual oil, dust, and loose fiber debris from the weaving process. Cleaning can be achieved by wiping with a mild solvent, hot air blowing, or low-temperature drying.

[0054] Step two further includes the following steps:

[0055] Step 2-1: Set the same ratio for the inner and outer layers: 60%~90% polyether polyurethane, 10%~40% polycarbonate polyurethane, and 0%~2% color masterbatch.

[0056] Step 2-2: Add polyether polyurethane masterbatch and polycarbonate polyurethane masterbatch directly into the mixing equipment according to the set ratio for pre-homogenization. After pre-homogenization, send the mixture into a dehumidifying dryer for unified dehumidification and drying treatment.

[0057] Preferably, after pre-homogenization, the material is sent to a dehumidifying dryer for uniform drying at a temperature of 80℃~95℃ for 4h~6h.

[0058] The drying process of color masterbatch is related to the properties of its carrier resin. In this invention, the carrier resin of the color masterbatch is preferably consistent with the type of the main polyurethane resin, such as polyether-type TPU. In this case, the color masterbatch and the main masterbatch are processed simultaneously at the same drying temperature of 80°C to 95°C, which ensures that no color spots or bubbles caused by water vapor precipitation occur during the subsequent co-extrusion molding, while also ensuring pigment dispersion and resin compatibility.

[0059] Steps 2-3: Add the pre-dried masterbatch to the mixer in sequence. First, mix the base material at low speed, then add the color masterbatch and increase the speed to mix evenly.

[0060] Instead of adding all materials at once, sequential feeding is performed in a high-speed mixer. Preferably, the polyether-type polyurethane masterbatch is first slowly added to the high-speed mixer, and stirring is started at a low speed (300-600 r / min) to form a continuous and stable circulating material flow in the mixing chamber, quickly establishing a uniform mixed matrix. Subsequently, polycarbonate-type polyurethane masterbatch is added slowly at the same speed, utilizing the already formed circulating material flow to disperse, coat, and impregnate the components layer by layer, thereby avoiding local agglomeration. After the two matrices are uniformly distributed, the color masterbatch is finally added, and the mixing intensity is increased to medium-high speed within a short time, allowing the color masterbatch to quickly distribute in the already uniform matrix, preventing overheating during prolonged shearing and resulting in dull color.

[0061] During the above-mentioned feeding process, it is necessary to judge the adequacy of pre-homogenization in real time. The adequacy of pre-homogenization refers to the degree of dispersion of different particles in a unit volume. The operator takes samples at three locations: the feed inlet, the middle section, and the discharge outlet of the mixer, and measures the mass proportion of polycarbonate-type polyurethane masterbatch in each sample. Then, the differences between these three proportions are compared. If the difference between them does not exceed the set tolerance (preferably not more than 5% in this invention), and this tolerance condition is observed for three consecutive samplings, the pre-homogenization is considered sufficient, and the mixing can proceed to the next process. If the proportion deviation at any sampling point exceeds the tolerance, the stirring speed is maintained at low speed until the tolerance requirement is met for three consecutive samplings, and then the speed is increased to add color masterbatch.

[0062] Steps 2-4: The pre-homogenized mixture is directly fed into a dehumidifying dryer to perform a uniform dehumidifying and drying process. The drying temperature is controlled at 80℃~95℃, and the drying time is 4h~6h. A constant air volume is used throughout the process to reduce the residual moisture of the mixture to below 15ppm.

[0063] Steps 2-5: Transfer the dried blended material of the same proportion directly into the hopper of the single co-extrusion extruder.

[0064] Step three further includes the following steps:

[0065] Step 3-1: The reinforcing layer prepared in Step 1 is smoothly inserted into the outer periphery of the co-extrusion die core under constant tension. The tension is controlled so that the reinforcing layer is slightly tensioned without compressing the pores of the filament bundle, so as to ensure that the melt can penetrate smoothly in both directions.

[0066] Step 3-2: Start the single-screw extruder and melt and plasticize the blend with the same ratio in a progressive temperature range of 160℃~210℃ to form a stable and uniform melt flow.

[0067] Step 3-3: The same proportion of melt is split through a co-extrusion die to form an inner layer melt and an outer layer melt respectively: the inner layer melt is uniformly formed along the die core surface and penetrates into the inner pores of the reinforcing layer, while the outer layer melt covers the outer side of the reinforcing layer and penetrates into the remaining pores. The two melts naturally converge and are seamlessly combined in the middle to outer area of ​​the reinforcing layer thickness direction.

[0068] Steps 3-4: Start the traction machine synchronously, matching the traction speed with the extrusion rate to ensure that the melt fully wets the reinforcing layer before demolding; immediately after demolding, fix the hose shape with a coaxial sizing device to complete the initial locking shape.

[0069] Step four further includes the following steps:

[0070] Step 4-1: The co-extruded hoses are sequentially cooled in a mild cooling zone and an enhanced cooling zone. The mild cooling zone prevents the outer layer from shrinking due to sudden cooling, while the enhanced cooling zone completes the final dimension fixation and coordinates the thermal shrinkage rates of the inner and outer layers and the reinforcing layer.

[0071] Step 4-2: The entire cooling process uses a light support and shaping device to maintain the roundness of the hose cross-section and prevent elliptical deformation.

[0072] Step 4-3: After cooling, the hose runs at a constant speed under low tension, allowing the internal residual stress to be released and redistributed naturally.

[0073] The aforementioned step also uses a blend of polyether-type polyurethane and polycarbonate-type polyurethane to confirm whether the foregoing steps have achieved the expected technical effects of the present invention. This step is a preferred but not essential step in the present invention.

[0074] Step five further includes the following steps:

[0075] Step 5-1: After cooling and shaping, let the hose stand in a clean environment at room temperature for 24 hours. After the performance is fully stable, carry out the test.

[0076] Step 5-2: Appearance and dimensional inspection: Check the smoothness of the hose surface, the uniformity of the wall thickness, and the roundness. It is considered qualified if there are no braided patterns, bubbles, or pits.

[0077] Step 5-3: Interlayer peel strength test: Test the peel strength of the inner adhesive layer-reinforcing layer and the outer adhesive layer-reinforcing layer according to the standard. The peel strength of both should not be less than 80N / 25mm to be considered qualified.

[0078] Step 5-4: Chemical resistance test: Conduct hydrolysis resistance and hydrogen sulfide immersion test, test the tensile strength retention rate, and verify that the chemical resistance meets the standards.

[0079] Step 5-5: If the product passes the inspection, it is considered a finished product. If the product fails the inspection, the same mixing ratio parameters or drying and co-extrusion process parameters are adjusted in reverse.

[0080] This invention also provides a chemical-resistant polyurethane composite hose, prepared by the above method. For example... Figure 1 As shown, the composite hose adopts a three-layer integrated composite structure, consisting of an inner adhesive layer 3, a reinforcing layer 2, and an outer adhesive layer 1 from the inside out. The three layers are deeply interlocked to form a stable whole that is non-peeling and non-recognizable.

[0081] The inner and outer rubber layers use the same blended formulation of polyether polyurethane and polycarbonate polyurethane. This blended formulation gives the hose excellent chemical resistance, flexibility and processing stability, and can effectively resist corrosion from acid, alkali, organic solvents, hydrolysis, hydrogen sulfide and other corrosive media, while ensuring the hose is resistant to bending and dimensional stability.

[0082] The reinforcing layer is a tubular skeleton layer formed by the cross-weaving of warp and weft yarns. It is made of polyester filament, nylon filament or aramid filament. Under the bidirectional impregnation and embedding of the melt with the same ratio, it forms a high-strength integrated structure with the inner and outer adhesive layers.

[0083] To further illustrate the technical effects of the present invention, a control group was set up for comparative testing with Examples 1-3. The raw material ratios for each group were expressed as mass fractions, as detailed in Table 1:

[0084] Table 1: Raw material ratios of the control group and the example

[0085]

[0086] After the formulation is mixed at high speed and dried uniformly, it is made into hoses under the same co-extrusion conditions, and standard samples are cut from the finished hoses for subsequent performance testing.

[0087] Performance testing methods and results:

[0088] According to national standards, the peel strength, hydrolysis resistance, hydrogen sulfide resistance, and melt flow rate (MFR) of each group of samples were tested to verify the interlayer bonding stability and chemical resistance of the present invention.

[0089] 1. Peel strength test

[0090] According to the GB / T532 standard method, standard samples were cut from the finished hose for testing, and the results are shown in Table 2.

[0091] Table 2: Peel Strength Test Results

[0092]

[0093] As shown in Table 2, the peel strength of both the inner and outer layers in the embodiments of the present invention remains at a high level. In Example 3, the peel strength of the inner and outer layers is the most consistent, and the interlayer bonding is stable.

[0094] 2. Hydrolysis resistance test

[0095] The inner rubber layer was made into a standard sample and immersed in an aqueous solution for 7 weeks. The tensile strength before and after immersion was tested according to the GB / T528 standard method, and the tensile strength retention rate was calculated. The results are shown in Table 3.

[0096] Table 3: Results of Hydrolysis Resistance Test

[0097]

[0098] As shown in Table 3, the tensile strength retention rate of the examples with added polycarbonate-type polyurethane was higher than that of the control group, and the hydrolysis resistance was significantly improved.

[0099] 3. Hydrogen sulfide resistance test

[0100] The inner rubber layer was made into a standard sample and immersed in an acidic aqueous solution containing hydrogen sulfide for 7 days. The tensile strength before and after immersion was tested according to the GB / T528 standard method, and the tensile strength retention rate was calculated. The results are shown in Table 4.

[0101] Table 4: Results of Tensile Strength Retention Rate Test for Hydrogen Sulfide Immersion

[0102]

[0103] As shown in Table 4, the hydrogen sulfide resistance of the embodiments of the present invention is better than that of the control group, among which Example 2 has the highest tensile strength retention rate and the best chemical resistance effect.

[0104] 4. Melt Flow Rate (MFR)

[0105] The testing standard was GB / T3682.1-2018 "Determination of melt mass flow rate (MFR) and melt volumetric flow rate (MVR) of thermoplastic plastics - Part 1: Standard method"; the testing instrument was a melt flow rate tester; the testing conditions were: temperature 190℃ and nominal load 5kg (routine testing conditions for thermoplastic polyurethane). Sample preparation: All polyurethane raw materials were uniformly dehumidified and dried before being used as test samples.

[0106] The test steps are as follows: preheat the instrument and keep it at a constant temperature for 30 minutes, add the sample, keep it at a constant temperature for 4 minutes, apply the load, cut the sample segment, weigh and calculate, and take the average value of each group of parallel tests.

[0107] Control group A: 100% pure polyether polyurethane (PE-PU).

[0108] Control group B: 100% pure polycarbonate polyurethane (PC-PU).

[0109] Table 5: Melt Flow Rate (MFR) Test Data

[0110]

[0111] The units for tests 1-4 are all g / 10min.

[0112] As shown in Table 5, the average MFR of pure polycarbonate polyurethane (control group B) was 7.7 g / 10 min, which meets the characteristic of MFR < 10 g / 10 min; the average MFR of the blends in Examples 1 to 3 of this invention was 8.8 to 14.6 g / 10 min, which completely fell within the target range of 8 to 15 g / 10 min; the melt flow rate of the blends was significantly higher than that of pure PC-PU.

[0113] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0114] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A chemical-resistant polyurethane composite hose, characterized in that, From the inside out, it includes an inner adhesive layer (3), a reinforcing layer (2), and an outer adhesive layer (1). The inner adhesive layer (3), the reinforcing layer (2), and the outer adhesive layer (1) are co-extruded and bidirectionally impregnated to form an integrated structure. The inner adhesive layer (3) and the outer adhesive layer (1) are made of polyether polyurethane and polycarbonate polyurethane with the same physical blending ratio, wherein the mass proportion of polycarbonate polyurethane is 10% to 40%. The reinforcing layer (2) is a tubular skeleton layer formed by cross-weaving of warp and weft yarns.

2. A method for preparing a chemical-resistant polyurethane composite hose, characterized in that, Includes the following steps: Step 1: Design and weave a tubular reinforcing layer, wherein the weaving structure of the reinforcing layer matches the wetting depth of the subsequent co-extrusion melt; Step 2: The blends of polyether polyurethane and polycarbonate polyurethane with the same ratio are pre-homogenized and uniformly dehumidified and dried. Step 3: The treated blend is co-extruded and composite molded to control the viscosity of the inner and outer melts so that the inner and outer melts are bidirectionally impregnated and combined in the reinforcing layer. Step four: Perform segmented cooling and shaping on the co-extruded hose and release internal residual stress.

3. The chemical-resistant polyurethane composite hose according to claim 1, characterized in that, The warp and weft of the reinforcing layer (2) are made of one or more of polyester filament, nylon filament, and aramid.

4. The chemical-resistant polyurethane composite hose according to claim 1, characterized in that, The interlayer peel strength between the inner adhesive layer (3) and the reinforcing layer (2), and between the outer adhesive layer (1) and the reinforcing layer (2), is not less than 80. N / 25 mm .

5. The method for preparing the chemical-resistant polyurethane composite hose according to claim 2, characterized in that, Step one specifically includes: determining the braiding angle and braiding density of the reinforcing layer based on the inner diameter, working pressure and minimum bending radius of the hose; forming a tubular reinforcing layer by braiding selected warp and weft yarns; and performing low-tension sizing treatment and surface cleaning treatment on the braided reinforcing layer, wherein the low-tension sizing treatment is based on maintaining the natural fluffiness of the yarns.

6. The method for preparing the chemical-resistant polyurethane composite hose according to claim 2, characterized in that, Polyether-type polyurethane masterbatch and polycarbonate-type polyurethane masterbatch are directly mixed in a set ratio, and then the mixture is subjected to uniform dehumidification and drying treatment. The uniform drying process is to maintain a temperature of 80°C to 95°C for 4 hours. h Up to 6 h .

7. The method for preparing the chemical-resistant polyurethane composite hose according to claim 2, characterized in that, In step two, the inner layer blend and the outer layer blend are materials with the same proportion, and the mass ratio of polycarbonate polyurethane in the blend is 10% to 40%.

8. The method for preparing the chemical-resistant polyurethane composite hose according to claim 2, characterized in that, Step three specifically includes: inserting the reinforcing layer through the outer periphery of the core of the co-extrusion die with constant tension, and molten extruding the blended material with the same proportion, so that an inner melt layer is formed on the surface of the core and an outer melt layer is formed on the outside of the reinforcing layer, and the melt penetrates into the pores of the reinforcing layer in both directions and merges and combines.

9. The method for preparing the chemical-resistant polyurethane composite hose according to claim 2, characterized in that, Step four specifically includes: passing the co-extruded hose through a mild cooling zone and an enhanced cooling zone for segmented cooling; using a light support and shaping device to maintain the roundness of the hose cross-section during the cooling process; and running the cooled hose under low tension to redistribute internal stress.

10. The method for preparing the chemical-resistant polyurethane composite hose according to claim 2, characterized in that, It also includes step five: quality assessment of the hose after cooling and shaping.

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