A preparation method of polyurethane elastomer

Abstract

The present invention belongs to the technical field of polyurethane elastomer processing, and specifically, is a method for preparing a polyurethane elastomer; the method comprises the following steps: step 1: reacting a polyester or polyether diol oligomer having hydroxyl groups at both ends with diisocyanate to obtain a mixture of a prepolymer having isocyanate as the end group and an excess of diisocyanate; step 2: reacting the product obtained in step 1 with a low-molecular-weight diol or diamine as a chain extender to obtain a polyurethane thermoplastic elastomer; step 3: filling the polyurethane thermoplastic elastomer into molds I and II, and pressing to obtain a polyurethane elastomer with an annular structure; step 4: guiding the product to a positioning frame and subjecting it to natural cooling treatment; after the polyurethane elastomer is pressed and formed, the polyurethane elastomer is automatically discharged, the position of the polyurethane elastomer is then restricted, and the polyurethane elastomer is automatically picked up and clamped, thereby reducing the need for manual operation.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane elastomer processing, and specifically relates to a method for preparing a polyurethane elastomer. Background Art

[0002] Polyurethane thermoplastic elastomer, referred to as TPU, is divided into two types: polyester type and polyether type, and mainly appears as white irregular spherical or columnar particles;

[0003] The outstanding features of polyurethane thermoplastic elastomers are excellent wear resistance, excellent ozone resistance, high hardness, high strength, good elasticity, low temperature resistance, good oil resistance, chemical resistance and environmental resistance;

[0004] TPU synthesis methods can be divided into two categories based on whether or not solvents are used: solvent-free bulk polymerization and solvent-based solution polymerization. The solvent-free bulk polymerization method includes a one-step method and a prepolymer method. The prepolymer method involves first reacting oligomer diols and diisocyanates, and then synthesizing them with a dry chain extender in the presence of a small amount of catalyst. The prepolymer method has a more complex production process, high energy consumption, and high viscosity of the prepolymer, which increases the difficulty of process operation. However, the prepolymer has fewer side reactions, and the product performance is better than that of the one-step method.

[0005] After the polyurethane elastomer is polymerized and molded, the semi-finished product needs to be trimmed. Summary of the Invention

[0006] In order to achieve the purpose of trimming the polyurethane elastomer and reducing the need for manual operation, the present invention adopts the following technical solutions:

[0007] The purpose of the present invention is to provide a solution that can automatically discharge the polyurethane elastomer after it is press-formed, limit the position of the polyurethane elastomer, automatically pick up and clamp the polyurethane elastomer, and trim the edge position of the polyurethane elastomer.

[0008] In order to achieve the above object, the present invention provides a method for preparing a polyurethane elastomer, comprising the following steps:

[0009] Step 1: reacting a polyester or polyether diol oligomer having a double terminal hydroxyl group with a diisocyanate to obtain a mixture of a prepolymer having an isocyanate terminal group and an excess of diisocyanate;

[0010] Step 2: reacting the product obtained in step 1 with a chain extender low molecular weight diol or diamine to obtain a polyurethane thermoplastic elastomer;

[0011] Step 3: Filling the polyurethane thermoplastic elastomer into mold I and mold II, and pressing to obtain a polyurethane elastomer with a ring structure;

[0012] Step 4: Lead the polyurethane elastomer to the positioning frame and allow it to cool naturally.

[0013] Among them, mold I and mold II can open and close each other in a horizontal state, so that the polyurethane elastomer can slide onto the positioning frame, and then the clamping assembly is passed through the middle of the polyurethane elastomer with an annular structure to clamp and position the polyurethane elastomer, thereby facilitating the trimming of the edges of the polyurethane elastomer. During this process, the polyurethane elastomer is automatically positioned and picked up to reduce the need for manual operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following drawings are intended only to illustrate and explain the present invention, wherein:

[0015] Figure 1 is a process flow chart of the method for preparing the polyurethane elastomer of the present invention;

[0016] Figure 2 1. A material composition diagram of the polyurethane elastomer of the present invention;

[0017] Figure 3 It is a structural schematic diagram of the platform, guide groove and positioning frame of the present invention;

[0018] Figure 4 It is a structural schematic diagram of the scraper and the limiting arm of the present invention;

[0019] Figure 5 It is a structural schematic diagram of the hollow frame, the supporting arm and the T-shaped insert of the present invention;

[0020] Figure 6 It is a structural schematic diagram of the scraper, the limiting arm and the tightening device of the present invention;

[0021] Figure 7 It is a structural schematic diagram of the positioning frame, positioning block and tightening device of the present invention;

[0022] Figure 8 Schematic diagram of the structure of the T-shaped insert, mold I and T-shaped plunger of the present invention;

[0023] Figure 9 Schematic diagram of the structure of the T-shaped insert and mold II of the present invention;

[0024] Figure 10 It is a structural schematic diagram of the scraper of the present invention;

[0025] Figure 11 Schematic diagram of the structure of the limiting arm of the present invention;

[0026] Figure 12 It is a structural schematic diagram of the movable frame, the first rotation driver and the screw rod of the present invention;

[0027] Figure 13 Schematic diagram of the structure of the hollow arm, the pressing pestle and the pressing plate of the present invention;

[0028] Figure 14 It is a structural schematic diagram of the tightening device, the sliding block and the driving groove of the present invention.

[0029] In the figure: platform 1; guide groove 11; positioning frame 12; scraper 13; limiting arm 14; first telescopic driver 15; hollow frame 21; supporting arm 22; T-shaped insert 23; mold I 24; feeding pipe 25; T-shaped plunger 26; mold II 27; moving frame 31; first rotary driver 32; screw 33; hollow arm 34; through rod 41; gear ring 42; positioning block 43; tightener 51; slider 52; drive groove 53; pressing pestle 54; pressure plate 55. DETAILED DESCRIPTION

[0030] In order to achieve the purpose of trimming a polyurethane elastomer and reducing the need for manual operation, the present invention provides a method for preparing a polyurethane elastomer, comprising the following steps:

[0031] Step 1: reacting a polyester or polyether diol oligomer having a double terminal hydroxyl group with a diisocyanate to obtain a mixture of a prepolymer having an isocyanate terminal group and an excess of diisocyanate;

[0032] Step 2: reacting the product obtained in step 1 with a chain extender low molecular weight diol or diamine to obtain a polyurethane thermoplastic elastomer;

[0033] Step 3: Fill the polyurethane thermoplastic elastomer into the mold I 24 and the mold II 27, and press the polyurethane elastomer into a ring-shaped structure;

[0034] Step 4: Control the mold to open and guide the polyurethane elastomer to the positioning frame 12 for natural cooling.

[0035] During the natural cooling stage of the polyurethane elastomer, the annular polyurethane elastomer is clamped by a clamping assembly, and then the clamping assembly is controlled to rotate around its own axis. Under the action of the scraper 13, the circumference of the annular polyurethane elastomer is trimmed.

[0036] The specific embodiments of the present invention are described below.

[0037] Reference Figure 3-5 As shown, the preparation method of the polyurethane elastomer provided by the present invention is described, and an embodiment of the polyurethane elastomer product with an annular structure is processed:

[0038] A platform 1 is provided in the processing workshop, and a plurality of guide grooves 11 and positioning frames 12 are installed on the platform 1 .

[0039] A hollow frame 21 is mounted on each guide slot 11 , and the hollow frame 21 is mounted on the top lower side of the guide slot 11 through fasteners.

[0040] Mold I 24 and mold II 27 are respectively slidably connected to the hollow frame 21 through a supporting arm 22. When mold I 24 and mold II 27 are horizontally opened to each other, space can be provided for the molded polyurethane elastomer to be removed.

[0041] A filling pipe 25 is provided on the mold I 24 , and a T-shaped plunger 26 is detachably fixedly connected to the filling pipe 25 . By pulling out the T-shaped plunger 26 , the polyurethane elastomer raw material can be poured into the mold I 24 and the mold II 27 .

[0042] The mold I 24 and the mold II 27 can be made of breathable steel.

[0043] Among them, mold I 24 and mold II 27 are respectively installed with column structures and electric heating platforms on the inner and outer sides, so that after mold I 24 and mold II 27 are pressed together, a polyurethane elastomer product with an annular structure can be processed.

[0044] Reference Figure 5 As shown, the preparation method of the polyurethane elastomer provided by the present invention is described, and an embodiment of controlling the opening and closing operation of the mold I 24 and the mold II 27 is described:

[0045] Hydraulic rods for driving the supporting arms 22 to slide are respectively installed on both sides of the hollow frame 21 through fasteners, and the movable ends of the hydraulic rods are fixedly connected to the supporting arms 22 through fasteners;

[0046] Start the extension and retraction of the hydraulic rod to control the opening and closing operations of mold I 24 and mold II 27.

[0047] The ends of the two supporting arms 22 are respectively fixedly connected to the mold I 24 and the mold II 27 via fasteners.

[0048] Reference Figure 4 and Figure 11 , which illustrates an embodiment of a method for preparing a polyurethane elastomer provided by the present invention, using a pair of limiting arms 14 to limit the position of the formed polyurethane elastomer:

[0049] The guide groove 11 is tiltedly arranged on the upper side of the platform 1 , and a plurality of intercepting posts on the positioning frame 12 form openings near the guide groove 11 for the annular polyurethane elastomer product to enter the positioning frame 12 .

[0050] A plurality of first telescopic actuators 15 are installed at the lower end of the platform 1, and a limiting arm 14 that can be inserted into the gap between a plurality of intercepting columns is installed on the movable end of the first telescopic actuator 15. The limiting arms 14 cooperate with each other to limit the molded polyurethane elastomer so that it can be placed upright between the plurality of intercepting columns in the positioning frame 12.

[0051] Reference Figure 3-4 and Figure 12-13 As shown, the preparation method of the polyurethane elastomer provided by the present invention is described, and the through-rod 41 is controlled to penetrate the middle of a plurality of polyurethane elastomer products placed upright on the intercepting column to complete the embodiment of automatically clamping the polyurethane elastomer products:

[0052] A movable frame 31 is installed in the middle of the platform 1 for horizontal sliding. A through-rod 41 is rotatably connected to the movable frame 31. A circular hole for the through-rod 41 to pass through is provided on the positioning frame 12. The through-rod 41 can pass through the middle of multiple polyurethane elastomer products placed upright on the intercepting column.

[0053] A first rotary driver 32 is installed on the platform 1. The output shaft of the first rotary driver 32 is connected to a screw rod 33 through a coupling. The other end of the screw rod 33 is rotatably connected to the support seat on the platform 1. The screw rod 33 is connected to the movable frame 31 through a threaded transmission.

[0054] The rotary driver in the present application can be a stepper motor or a servo motor. The first rotary driver 32 is started to drive the through rod 41 to penetrate the middle of multiple polyurethane elastomer products placed on the intercepting column to complete the automatic clamping of the polyurethane elastomer products.

[0055] Reference Figure 6-7 and Figure 13-14 , which illustrates the method for preparing the polyurethane elastomer provided by the present invention, and an embodiment of tightening the polyurethane elastomer from the inner side of the polyurethane elastomer:

[0056] The core rod 41 is hollow inside, and a plurality of tighteners 51 are slidably mounted on the circumference thereof. The plurality of tighteners 51 slide out of the core rod 41 synchronously to tighten the polyurethane elastomer from the inner side thereof.

[0057] Among them, the tensioner 51 is stuck in the groove on the side of the through rod 41;

[0058] The round rod body of the tightener 51 is slidably mounted in the positioning blocks 43 at both ends of the inner side of the through rod 41;

[0059] A slider 52 is mounted on one end of the round rod extending to the outside of the through rod 41 .

[0060] Reference Figure 13-14 FIG. 1 is a diagram illustrating a method for preparing a polyurethane elastomer according to the present invention, wherein a plurality of tightening devices 51 are used to tighten the polyurethane elastomer from the inner side thereof while the through rod 41 is freely rotating.

[0061] The movable frame 31 is fixedly connected to two hollow arms 34 by fasteners, and a pressing rod 54 and a pressing plate 55 are slidably mounted on the hollow arms 34 on both sides, and the arc surfaces on the pressing rod 54 and the pressing plate 55 respectively abut against the driving grooves 53 on both sides of the slider 52.

[0062] The hollow arms 34 on both sides are respectively equipped with a second telescopic driver and a third telescopic driver for driving the pressing pestle 54 and the pressing plate 55 to slide;

[0063] The second telescopic driver and the third telescopic driver are activated alternately to drive the pressing rod 54 and the pressure plate 55 to slide in their respective corresponding hollow arms 34, so that the arc surfaces on the pressing rod 54 and the pressure plate 55 abut against the slider 52, thereby controlling the position of the tightening device 51 and adjusting the tightening force of the multiple tightening devices 51 on the polyurethane elastomer.

[0064] The arc surface setting on the pressing pestle 54 and the pressing plate 55 can enable the through rod 41 to rotate freely. The polyurethane elastomer is tightened from the inside of the polyurethane elastomer by multiple tightening devices 51, and the outer edge of the polyurethane elastomer is trimmed using a scraper 13, reducing the need for manual operation, improving the degree of automation of the processing equipment, and making it easy to perform trimming operations when the polyurethane elastomer is not completely cooled.

[0065] Reference Figure 4 、 Figure 6 and Figure 10 As shown, the method for preparing the polyurethane elastomer provided by the present invention, the position setting of the scraper 13, and the embodiment of trimming the side of the polyurethane elastomer products with different diameters are described:

[0066] A scraper 13 is slidably mounted on the upper side of the positioning frame 12 , and the scraper 13 can abut against the outer edge of the polyurethane elastomer to trim the edge of the polyurethane elastomer.

[0067] An L-shaped piece is installed on each side of the scraper 13. The L-shaped piece is fastened to the positioning frame 12 through a fastener. The vertical position of the scraper 13 can also be controlled by a separate hydraulic component.

[0068] Reference Figure 4 、 Figure 6 and Figure 13 As shown, the preparation method of the polyurethane elastomer provided by the present invention is described, and an embodiment of the clamping and rotating treatment of the polyurethane elastomer product with an annular structure is described:

[0069] A gear ring 42 is installed at one end of the through rod 41, and a second rotary driver is installed on the movable frame 31. The output shaft of the second rotary driver is connected to a driving gear via a flat key or a wedge key, and the driving gear is meshed with the gear ring 42 through a belt.

[0070] The second rotary driver is started to rotate, driving the through rod 41 to rotate, and under the action of the scraper 13, the side of the polyurethane elastomer product is automatically trimmed.

[0071] Reference Figure 4-5 and Figure 8-9 As shown, the preparation method of the polyurethane elastomer provided by the present invention is described, and examples of polyurethane elastomer products with different thicknesses are processed:

[0072] The column structure is movably installed on mold I 24 and mold II 27 so that the thickness of the polyurethane elastomer product can be adjusted. T-shaped blocks 23 are slidably installed on the two supporting arms 22. The two T-shaped blocks 23 are welded and fixedly connected to the outer side surfaces of mold I 24 and mold II 27 with tension springs. The ends of the two T-shaped blocks 23 located on the inner sides of mold I 24 and mold II 27 are abutted and fitted.

[0073] The two T-shaped inserts 23 are separated from each other after the mold I 24 and the mold II 27 are opened to a certain distance, providing space for the polyurethane elastomer product to be removed.

[0074] Among them, mold I 24 is provided with an extended sealing edge, which can be inserted into mold II 27, so that it is easy to process polyurethane elastomer products of different thicknesses. During this process, the two T-shaped inserts 23 can maintain abutment state on the side close to each other within a certain range.

Claims

1. A method for preparing a polyurethane elastomer, characterized in that: The following steps are involved: Step 1: reacting a polyester or polyether diol oligomer having a double terminal hydroxyl group with a diisocyanate to obtain a mixture of a prepolymer having an isocyanate terminal group and an excess of diisocyanate; Step 2: reacting the product obtained in step 1 with a chain extender low molecular weight diol or diamine to obtain a polyurethane thermoplastic elastomer; Step 3: Filling the polyurethane thermoplastic elastomer into mold I (24) and mold II (27), and pressing to obtain a polyurethane elastomer with a ring structure; Step 4: Control the mold to open, guide the polyurethane elastomer to the positioning frame (12), and perform natural cooling treatment; Step 5: During the natural cooling stage of the polyurethane elastomer, trimming the peripheral side of the annular polyurethane elastomer; The positioning frame (12) is installed on a platform (1) in a processing workshop. A guide groove (11) is also installed on the platform (1). The mold I (24) and the mold II (27) are connected to the hollow frame (21) on the guide groove (11) through the supporting arm (22). The mold I (24) and the mold II (27) are horizontally opened to each other to provide a space for the polyurethane elastomer to be removed after molding. The guide groove (11) is obliquely arranged on the upper side of the platform (1), and a plurality of intercepting columns of the positioning frame (12) form openings at positions close to the guide groove (11); The lower end of the platform (1) is equipped with a plurality of first telescopic actuators (15), and the movable ends of the first telescopic actuators (15) are equipped with limiting arms (14) capable of being inserted into the gaps between the plurality of interception columns. The limiting arms (14) cooperate with each other to limit the position of the molded polyurethane elastomer, so that the polyurethane elastomer can be placed upright on the plurality of interception columns. A mobile frame (31) is slidably mounted in the middle of the platform (1), and a through-rod (41) is rotatably connected to the mobile frame (31), and the through-rod (41) can penetrate the middle of a plurality of polyurethane elastomers placed upright on the intercepting columns; The core-penetrating rod (41) is hollow inside, and a plurality of tighteners (51) are slidably mounted on the circumferential side. The plurality of tighteners (51) slide out of the core-penetrating rod (41) synchronously to tighten the polyurethane elastomer from the inner side of the polyurethane elastomer.

2. The method for preparing a polyurethane elastomer according to claim 1, wherein: A scraper (13) is slidably mounted on the upper side of the positioning frame (12), and the scraper (13) can abut against the outer edge of the polyurethane elastomer to trim the edge of the polyurethane elastomer.

3. The method for preparing a polyurethane elastomer according to claim 1, wherein: The tightener (51) is stuck in the groove on the side of the through-core rod (41), and the round rod body of the tightener (51) is slidably installed in the positioning blocks (43) at both ends of the inner side of the through-core rod (41), and a slider (52) is installed on one end of the round rod extending to the outer side of the through-core rod (41).

4. The method for preparing a polyurethane elastomer according to claim 3, wherein: Two hollow arms (34) are fixedly connected to the movable frame (31), and a pressing rod (54) and a pressing plate (55) are slidably mounted on the hollow arms (34) on both sides, and the arc surfaces on the pressing rod (54) and the pressing plate (55) respectively abut against the driving grooves (53) on both sides of the slider (52).

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