A polyurethane composite material and preparation method thereof

Abstract

The present invention provides a polyurethane composite material and a preparation method thereof. The composite material uses polyimide fiber as a core, and polyurethane covers the polyimide fiber to form a composite material of polyurethane and polyimide fiber; before forming the composite material of polyurethane and polyimide fiber, the polyimide fiber is subjected to surface sizing grafting treatment. The polyurethane composite material of the present invention uses polyimide fiber as a core and is composited with polyurethane. Compared with the prior art, the strength of the polyurethane composite material can be significantly improved, and the deficiency of polyimide wear resistance can be made up. In addition, the polyimide fiber is subjected to surface sizing grafting treatment, which can increase the surface polarity, has good bonding with polyurethane, and is not easy to peel off.

Description

Technical Field

[0001] The invention relates to a polymer composite material, in particular to a polyurethane composite material and a preparation method thereof. Background Art

[0002] Polyurethane can be divided into thermoplastic polyurethane (TPU) and thermosetting polyurethane (CPU), which can also be called particles (solid) and liquid. The core of conventional high-performance thermoplastic polyurethane (TPU) composite materials is mainly composed of silk or cotton thread. A layer of polyurethane material is wrapped on the outer surface of the core to obtain a polyurethane composite material, which can be wound into a coil or directly made into a textile.

[0003] Referring to Chinese patent application CN107780222A, the production process of the polyurethane composite material includes: firstly, extruding the polyurethane material by an extruder, and then coating the polyurethane on a silk thread or a cotton thread by a coating technology, so as to obtain the polyurethane composite material.

[0004] The core of the conventional polyurethane composite material is mainly silk thread or cotton thread, which is formed by extruding the polyurethane material through an extruder. The use of silk thread and cotton thread as the core limits the strength of the polyurethane composite material, thereby limiting the scope of use of the material.

[0005] Polyimide is a type of polymer containing an imide ring in the polymer chain. The rigid aromatic ring structure and imide group in the main chain of polyimide give it excellent mechanical properties, high and low temperature resistance, flame retardancy, radiation resistance and high insulation properties. High-strength and high-modulus polyimide fiber is being studied as a composite material reinforcement due to its excellent mechanical properties and low water absorption. However, polyimide has the disadvantage of insufficient wear resistance. Summary of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a novel polyurethane composite material and a preparation method thereof, which can at least solve the problems of low strength of the polyurethane composite material and insufficient wear resistance of the polyimide in the prior art.

[0007] According to the purpose of the present invention, on the one hand, the present invention provides a polyurethane composite material, which uses polyimide fiber as the core, and the polyurethane is a thermoplastic polyurethane, and the polyimide fiber is coated with polyurethane to form a composite material of polyurethane and polyimide fiber; before forming the composite material of polyurethane and polyimide fiber, the polyimide fiber is subjected to surface sizing grafting treatment.

[0008] The polyurethane composite material of the present invention uses polyimide fiber as the core and is composited with thermoplastic polyurethane. Compared with the prior art, the strength of the polyurethane composite material can be significantly improved, and the wear resistance of polyimide can be made up. In addition, the polyimide fiber is subjected to surface sizing grafting treatment, which can increase the surface polarity, has good bonding with polyurethane, and is not easy to peel off.

[0009] The composite material of polyurethane and polyimide fiber in the present invention is a core-skin structure composite fiber (also called composite yarn), with polyimide fiber as the core layer and polyurethane as the skin layer.

[0010] Preferably, the polyimide fiber is a high-strength and high-modulus polyimide fiber with a linear density of 200D to 1500D, a fiber breaking strength greater than 17.5 cN / dtex, and an initial modulus greater than 110 GPa.

[0011] By using high-strength and high-modulus polyimide fibers, the strength of polyurethane composite materials can be greatly improved.

[0012] In another aspect, the present invention provides a textile made of the polyurethane composite material. The polyurethane composite material can be wound into a roll, or can be made into various textiles using a textile machine.

[0013] In another aspect, the present invention provides a method for preparing a polyurethane composite material, wherein the polyurethane composite material is a composite material of polyurethane and polyimide fiber, and the polyurethane is thermoplastic polyurethane, and the preparation method comprises the following steps:

[0014] 1) Using the polyimide fiber as the core, using a sizing agent to perform surface sizing grafting treatment on the polyimide fiber;

[0015] 2) Add polyurethane pellets into the hopper, seal the hopper, dry and dehumidify at 80°C to 90°C for 2 to 4 hours, and start the extruder;

[0016] 3) The die preheating temperature is set to 190° C. to 200° C., the extruder is started, and the traction is turned on to allow the polyimide fiber to pass through the die die, and the polyurethane pellets enter the screw extruder. The pellets are pushed toward the die and are heated for 4 to 5 stages to make the temperature of the pellets at the die outlet reach 200° C. to 210° C., exceeding the melting point of the pellets. The pellets enter the extruder head in a molten viscous flow state and are coated on the outer periphery of the polyimide fiber to obtain the polyurethane composite material.

[0017] By adopting the preparation method of the present invention, the polyimide fiber can be used as the core and the thermoplastic polyurethane can be coated on the outer periphery of the polyimide fiber, thereby obtaining a composite material of polyurethane and polyimide fiber, which can significantly improve the strength of the polyurethane composite material and make up for the lack of wear resistance of polyimide. In addition, before the polyimide fiber and the polyurethane are composited, the fiber surface is firstly subjected to sizing and grafting treatment, which can increase the surface polarity, have good bonding with the polyurethane, and is not easy to peel off.

[0018] Preferably, the polyimide fiber is a twisted polyimide fiber or an untwisted polyimide fiber, and the twist of the twisted polyimide fiber is 50 to 600 twists / meter.

[0019] In the present invention, whether to twist the polyimide fiber can be selected according to actual needs such as product use. If twisted fiber is selected, the twist degree of the twisted fiber is 50 to 600 twists / meter.

[0020] Preferably, the polyimide fiber is a high-strength and high-modulus polyimide fiber with a linear density of 200D to 1500D, a fiber breaking strength greater than 17.5 cN / dtex, and an initial modulus greater than 110 GPa. By using high-strength and high-modulus polyimide fibers, the strength of the polyurethane composite material can be greatly improved.

[0021] Preferably, the sizing agent is a water-based sizing agent, and the water-based sizing agent is selected from a water-based silicone sizing agent, a water-based epoxy sizing agent, a water-based cyanate sizing agent, and a water-based polyamic acid sizing agent. More preferably, the water-based sizing agent is a water-based silicone sizing agent.

[0022] The sizing grafting treatment includes sizing and drying. Preferably, the sizing agent concentration should be 3% to 20%, the sizing temperature is room temperature, and the drying temperature should be determined according to the curing temperature of the sizing agent, but shall not be higher than 320°C. By setting the sizing agent concentration, sizing temperature, and drying temperature in this way, it can be better ensured that the polyimide fiber and the polyurethane that have undergone sizing grafting treatment have a close bond. As a preferred embodiment of the present invention, the concentration of the water-based silicone sizing agent is 15%, the sizing temperature is room temperature, and the drying temperature is 150°C.

[0023] In the present invention, before being compounded with polyurethane, the polyimide fiber is subjected to surface sizing grafting treatment to promote better combination of the fiber and polyurethane.

[0024] Preferably, before step 3, the coating amount of the polyurethane is controlled by adjusting the distance between the upper and lower dies of the extruder head, or by adjusting the unwinding speed, the winding speed of the polyimide fiber and the rotation speed of the extruder screw.

[0025] In the present invention, the desired coating effect can be achieved by appropriately controlling the amount of polyurethane coating. The amount of polyurethane coating can be controlled by adjusting the distance between the upper and lower dies of the extruder head; it can also be achieved by adjusting the unwinding speed, winding speed of the fiber, and the rotation speed of the extruder screw.

[0026] Preferably, after step 3, the polyurethane composite material is wound into a roll and made into a textile using a textile machine.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) Using polyimide fiber, especially high-strength and high-modulus polyimide fiber with a linear density of 200D to 1500D as the core, compared with using silk thread and cotton thread as the core, under the same linear density conditions, the mechanical properties of polyimide fiber are more excellent, which greatly improves the strength of the obtained polyurethane composite material.

[0029] 2) Whether to twist the fiber can be flexibly selected according to the actual needs such as product use;

[0030] 3) Before compounding with polyurethane, the polyimide fiber is subjected to surface sizing grafting treatment to increase the surface polarity, so that it has good bonding with polyurethane and is not easy to peel off;

[0031] 4) The polyimide fiber used as the core is brightly colored and has excellent flame retardancy (limiting oxygen index ≥ 38%), high and low temperature resistance (glass transition temperature ≥ 320°C), and UV resistance. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific examples, but the present invention is not limited to the following examples. If the specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially. The polyimide fiber used in the examples is provided by Jiangsu Xiannuo.

[0033] Example 1: Take 200D polyimide fiber a with a breaking strength of 20.8 cN / dtex and an initial modulus of 115 GPa, use the polyimide fiber a as the core, use a water-based silicone sizing agent SH9608-A to perform surface sizing grafting treatment on the polyimide fiber, wherein the sizing agent concentration is 15%, the sizing temperature is room temperature, and the drying temperature is 150°C; add polyurethane pellets into a hopper, seal the hopper, dry and dehumidify at 80°C to 90°C for 2 to 4 hours When the extruder is started; the die preheating temperature is set to 190°C to 200°C, the extruder is started, and the traction is turned on to allow the polyimide fiber to pass through the die die, and the polyurethane pellets enter the screw extruder. The pellets move toward the die under the push of the screw, and after 4 to 5 stages of heating, the temperature of the pellets at the die outlet reaches 200°C to 210°C, exceeding the melting point of the pellets. The pellets enter the extruder head in a molten viscous flow state and are coated on the outer periphery of the polyimide fiber, thereby obtaining the polyurethane composite material A.

[0034] Example 2: 200D polyimide fiber b with a breaking strength of 20.8 cN / dtex and an initial modulus of 115 GPa was twisted at S80 twists / m, sizing and grafting, and then composited with polyurethane to obtain a polyurethane composite material B. Other than that, the process is the same as Example 1.

[0035] Example 3: 500D polyimide fiber c with a breaking strength of 20.8 cN / dtex and an initial modulus of 115 GPa is sized and grafted, and then composited with polyurethane to obtain a polyurethane composite material C. Other than that, the process is the same as Example 1.

[0036] Example 4: 500D polyimide fiber d with a breaking strength of 20.8 cN / dtex and an initial modulus of 115 GPa was twisted at S80 twists / m, sizing and grafting, and then composited with polyurethane to obtain a polyurethane composite material D. Other than that, the process is the same as Example 1.

[0037] A total of 8 samples of the above 4 kinds of fibers and 4 kinds of composite materials were tested for breaking strength, initial modulus, elongation at break, and wear resistance. The test standards for breaking strength, initial modulus, and elongation at break are: GB / T 19975-2005 "Test method for tensile properties of high-strength fiber filaments"; the wear resistance test is yarn-yarn wear resistance: the test sample is knotted 3 times under a load of 100g, and the sample itself is tested for wear resistance. The results are shown in Table 1 below.

[0038] As can be seen from the results in Table 1, the polyurethane composite material of the present invention has significantly more wear resistance times than the polyimide fiber, and the breaking strength and initial modulus are significantly improved. Since the breaking strength of polyurethane is significantly lower than that of polyimide, this indicates that after the polyimide fiber is surface treated and combined with polyurethane, it can play a synergistic role in improving strength and has excellent wear resistance. In addition, after the polyimide fiber is twisted, the breaking strength and initial modulus of the composite material can be further improved.

[0039] Table 1

[0040]

[0041] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a polyurethane composite material for textiles, characterized in that: The polyurethane composite material is a composite material of polyurethane and polyimide fiber, which is a composite fiber with a core-skin structure, with polyimide fiber as the core, and the polyurethane is a thermoplastic polyurethane, which is a composite material of polyurethane and polyimide fiber formed by only polyurethane covering the polyimide fiber; Before forming the composite material of polyurethane and polyimide fiber, a water-based silicone sizing agent is used to perform surface sizing grafting treatment on the polyimide fiber, the sizing temperature is room temperature, and the drying temperature is ≤320°C and ≥150°C; The polyimide fiber is a twisted polyimide fiber or an untwisted polyimide fiber, and the twist of the twisted polyimide fiber is 50 to 80 twists / meter; The preparation method comprises the following steps: 1) Using the polyimide fiber as the core, using a sizing agent to perform surface sizing grafting treatment on the polyimide fiber, the sizing temperature is room temperature, and the drying temperature is ≤320° C. and ≥150° C.; 2) Add polyurethane pellets into the hopper, seal the hopper, dry and dehumidify at 80°C to 90°C for 2 to 4 hours, and start the extruder; 3) The die preheating temperature is set to 190° C. to 200° C., the extruder is started, the traction is turned on, the polyimide fiber passes through the die die, the pellets enter the screw extruder, the pellets move toward the die under the push of the screw, and after 4 to 5 stages of heating, the temperature of the pellets at the die outlet reaches 200° C. to 210° C., exceeding the melting point of the pellets, and the pellets enter the extruder head in a molten viscous flow state, and are coated on the outer periphery of the polyimide fiber to obtain the polyurethane composite material.

2. The preparation method according to claim 1, characterized in that: The polyimide fiber is a twisted polyimide fiber or an untwisted polyimide fiber, and the twist of the twisted polyimide fiber is 50 to 80 twists / meter.

3. The preparation method according to claim 1, characterized in that: The polyimide fiber is a high-strength and high-modulus polyimide fiber with a linear density of 200D to 1500D, a fiber breaking strength greater than 17.5 cN / dtex, and an initial modulus greater than 110 GPa.

4. The preparation method according to claim 1, characterized in that: Before step 3, the coating amount of the polyurethane is controlled by adjusting the distance between the upper and lower dies of the extruder head, or by adjusting the unwinding speed, the winding speed of the polyimide fiber and the rotation speed of the extruder screw.

5. The preparation method according to claim 1, characterized in that: After step 3, the polyurethane composite material is wound into a roll and made into a textile using a textile machine.

6. A polyurethane composite material for textiles, prepared by the method according to any one of claims 1 to 4.

7. The polyurethane composite material for textiles according to claim 6, characterized in that: The polyimide fiber is a high-strength and high-modulus polyimide fiber with a linear density of 200D to 1500D, a fiber breaking strength greater than 17.5 cN / dtex, and an initial modulus greater than 110 GPa.

8. A textile made from the polyurethane composite material for textiles according to claim 6.

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