Thermoplastic polyurethane conveyor belt framework material dipping solution as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of industrial textiles, and particularly relates to a thermoplastic polyurethane conveyor belt framework material dipping solution as well as a preparation method and application thereof. The thermoplastic polyurethane conveyor belt framework material impregnation liquid is prepared from the following components in parts by weight: 30 to 70 parts of blocked isocyanate, 30 to 70 parts of waterborne polyurethane and 260 to 340 parts of deionized water, and the total amount of the blocked isocyanate, the waterborne polyurethane and the deionized water is 400 parts; anionic polyester type polyurethane is adopted as the waterborne polyurethane, and waterborne aliphatic blocked isocyanate is adopted as the blocked isocyanate. When the novel polyurethane impregnated canvas produced by the impregnation liquid is used for manufacturing a conveying belt, blocked isocyanate is used as an adhesive, and an impregnated layer capable of being adhered with thermoplastic polyurethane is formed on the surface of a framework material, so that the requirement of adhesion of the conveying belt is met.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial textiles, and specifically relates to a thermoplastic polyurethane conveyor belt skeleton material dipping solution and a preparation method and application thereof. Background Art

[0002] Conveyor belts are widely used to transport various solid block, powder materials or finished items. Conveyor belts can transport continuously, efficiently and at a large angle. They have the advantages of safe operation, easy use, easy maintenance and low freight. They can also shorten the transportation distance, reduce the project cost, save manpower and material resources, and are of great significance in the steel, metallurgy, ports, coal mines and other industries.

[0003] Thermoplastic polyurethane elastomers, with their excellent properties and wide applications, have become one of the important thermoplastic elastomer materials. Their molecules are basically linear, with little or no chemical crosslinking. There are many physical crosslinks formed by hydrogen bonds between the linear polyurethane molecular chains, which strengthen their morphology, thus giving them many excellent properties, such as high modulus, high strength, excellent wear resistance, chemical resistance, hydrolysis resistance, high and low temperature resistance, and mold resistance.

[0004] Since conventional dipped canvas cannot effectively bond with polyurethane, the thermoplastic polyurethane conveyor belts available on the market are usually made by adding chemical reagents to thermoplastic polyurethane elastomers. Although this method can achieve the bonding problem between polyurethane and skeleton materials, the overall production process is relatively cumbersome. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a thermoplastic polyurethane conveyor belt skeleton material dipping solution and its preparation method and application. When the conveyor belt is made of the new polyurethane dipped canvas produced by the dipping solution of the present invention, a layer of dipping layer that can be bonded with thermoplastic polyurethane is formed on the surface of the skeleton material using blocked isocyanate as an adhesive, thereby meeting the requirement of conveyor belt bonding. Since there are no special requirements for the polyurethane covering layer of the conveyor belt, the requirements for the polyurethane raw materials in the conveyor belt are lower, the scope of use is wider, and the storage time of the polyurethane raw materials is longer than that of the traditional polyurethane prepared by chemical reagents. At the same time, low temperature is used in the production of the skeleton material dipping, which reduces energy consumption and prevents the blocked isocyanate from being unblocked, thereby achieving the effect of long-term storage.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the embodiment of the present invention is:

[0007] In a first aspect, an embodiment of the present invention provides a thermoplastic polyurethane conveyor belt skeleton material dipping solution, which comprises the following components by weight: 30-70 parts of blocked isocyanate, 30-70 parts of waterborne polyurethane, and 260-340 parts of deionized water, wherein the total amount of the blocked isocyanate, the waterborne polyurethane and the deionized water is 400 parts;

[0008] The waterborne polyurethane is an anionic polyester polyurethane, and the blocked isocyanate is a waterborne aliphatic blocked isocyanate.

[0009] In a second aspect, an embodiment of the present invention provides a method for preparing the thermoplastic polyurethane conveyor belt skeleton material dipping solution described in the first aspect, comprising the following steps:

[0010] By weight, add 260-340 parts of deionized water into a mixing kettle, then add 30-70 parts of blocked isocyanate, stir for 20-30 minutes, then add 30-70 parts of waterborne polyurethane, stir for 20-30 minutes, and obtain a dipping solution.

[0011] In a third aspect, an embodiment of the present invention provides an application of the thermoplastic polyurethane conveyor belt skeleton material dipping solution described in the first aspect for preparing canvas, comprising the following steps:

[0012] The surface of the canvas of the thermoplastic polyurethane conveyor belt skeleton material is evenly coated with dipping liquid, and the amount of adhesive on the surface of the canvas is controlled at 4%-5%. After dipping, the canvas enters a drying oven for drying, the drying temperature is controlled at 90-110°C, hot air drying is adopted, the residence time in the oven is 300-360s, and the tension is controlled at 4-5N / mm; then the canvas enters a high-temperature oven for baking treatment, the oven temperature is 100-110°C, the baking time is 300-360s, and the tension is controlled at 8-10N / mm; cooling is performed so that the surface temperature of the canvas drops below 30°C to obtain a finished canvas.

[0013] Furthermore, the skeleton material of the thermoplastic polyurethane conveyor belt includes one or more of polyester fiber, nylon fiber, aramid fiber, vinyl fiber, polyarylate fiber and PVO fiber.

[0014] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0015] When the new polyurethane dipped canvas produced by the present invention is used to make a conveyor belt, a blocked isocyanate is used as an adhesive to form a dipped layer on the surface of the skeleton material that can be bonded with the thermoplastic polyurethane, thereby meeting the requirement of conveyor belt bonding. Since there are no special requirements for the polyurethane covering layer of the conveyor belt, the requirements for the polyurethane raw materials in the conveyor belt are lower, the scope of use is wider, and the storage time of the polyurethane raw materials is longer than that of the traditional polyurethane prepared by using chemical reagents. At the same time, low temperature is used in the production of the skeleton material dipped, which not only reduces energy consumption, but also ensures that the blocked isocyanate is not unblocked, thereby achieving the effect of long-term storage. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] Example 1

[0018] A thermoplastic polyurethane conveyor belt skeleton material dipping solution comprises the following components by weight: 50 parts of blocked isocyanate (mass fraction 40%), 50 parts of waterborne polyurethane (mass fraction 40%), 300 parts of deionized water, a total of 400 parts, wherein the solid content is 10%.

[0019] The preparation method of the above-mentioned thermoplastic polyurethane conveyor belt skeleton material dipping solution comprises the following steps: adding deionized water required for the total amount into a mixing kettle, then adding blocked isocyanate into the mixing kettle and stirring for 30 minutes; then adding water-based polyurethane and stirring for 30 minutes to obtain the dipping solution.

[0020] Example 2

[0021] A thermoplastic polyurethane conveyor belt skeleton material dipping solution comprises the following components by weight: 30 parts of blocked isocyanate (mass fraction 40%), 30 parts of waterborne polyurethane (mass fraction 40%), 340 parts of deionized water, a total of 400 parts, wherein the solid content is 6%.

[0022] The preparation method of the above-mentioned thermoplastic polyurethane conveyor belt skeleton material dipping solution comprises the following steps: adding deionized water required for the total amount into a mixing kettle, then adding blocked isocyanate into the mixing kettle and stirring for 30 minutes; then adding water-based polyurethane and stirring for 30 minutes to obtain the dipping solution.

[0023] Example 3

[0024] A thermoplastic polyurethane conveyor belt skeleton material dipping solution comprises the following components by weight: 70 parts of blocked isocyanate (mass fraction 40%), 70 parts of waterborne polyurethane (mass fraction 40%), 260 parts of deionized water, a total of 400 parts, wherein the solid content is 15%.

[0025] The preparation method of the above-mentioned thermoplastic polyurethane conveyor belt skeleton material dipping solution comprises the following steps: adding deionized water required for the total amount into a mixing kettle, then adding blocked isocyanate into the mixing kettle and stirring for 30 minutes; then adding water-based polyurethane and stirring for 30 minutes to obtain the dipping solution.

[0026] Example 4

[0027] A thermoplastic polyurethane conveyor belt skeleton material dipping solution comprises the following components by weight: 60 parts of blocked isocyanate (mass fraction 40%), 60 parts of waterborne polyurethane (mass fraction 40%), 280 parts of deionized water, a total of 400 parts, wherein the solid content is 12%.

[0028] The preparation method of the above-mentioned thermoplastic polyurethane conveyor belt skeleton material dipping solution comprises the following steps: adding deionized water required for the total amount into a mixing kettle, then adding blocked isocyanate into the mixing kettle and stirring for 30 minutes; then adding water-based polyurethane and stirring for 30 minutes to obtain the dipping solution.

[0029] Comparative Example

[0030] A thermoplastic polyurethane conveyor belt skeleton material dipping solution comprises the following components by weight: 100 parts of blocked isocyanate (mass fraction 40%), 100 parts of waterborne polyurethane (mass fraction 40%), 200 parts of deionized water, a total of 400 parts, wherein the solid content is 20%.

[0031] The preparation method of the above-mentioned thermoplastic polyurethane conveyor belt skeleton material dipping solution comprises the following steps: adding deionized water required for the total amount into a mixing kettle, then adding blocked isocyanate into the mixing kettle and stirring for 30 minutes; then adding water-based polyurethane and stirring for 30 minutes to obtain the dipping solution.

[0032] The composition of the thermoplastic polyurethane conveyor belt skeleton material dipping solution in Examples 1-2 of the present invention and Comparative Example 1 is shown in Table 1:

[0033] Table 1 Composition of the dipping solution of thermoplastic polyurethane conveyor belt skeleton material in Examples 1-4 and Comparative Examples

[0034] Compare Projects Example 1 Example 2 Example 3 Example 4 Comparative Example Water-based blocked isocyanate (parts) 50 30 70 60 100 Waterborne polyurethane (parts) 50 30 70 60 100 Deionized water (parts) 300 340 260 280 200 Total weight (parts) 400 400 400 400 400 Solid content 10％ 6％ 15％ 12％ 20％

[0035] The commodity information of the main materials in Examples 1-4 and Comparative Examples is shown in Table 2:

[0036] Table 2 Commodity information of main materials in Examples 1-4 and Comparative Examples

[0037]

[0038] The dipping solutions prepared in Examples 1-4 and the comparative example are used to prepare SW1000 type dipped canvas.

[0039] The preparation method of the dipped canvas for SW1000 thermoplastic polyurethane conveyor belt comprises the following steps:

[0040] After the canvas is unwound, it passes through an impregnation tank filled with dipping solution, and then is squeezed by a pair of squeezing rollers. The excess dipping solution is sucked off with a vacuum glue suction device to make the canvas surface evenly coated with the dipping solution. The amount of glue attached to the canvas surface is controlled at 5%. After dipping, it enters the drying oven for drying. The drying temperature is controlled at 95°C. Hot air drying is used. The residence time in the oven is 360 seconds, and the tension is 5N / mm; then it enters the high-temperature oven for heat treatment. The temperature of the heat treatment oven is controlled at 105°C, the heat treatment time is controlled at 360 seconds, and the tension is controlled at 10N / mm. After the first bath dipping is completed, the canvas surface temperature drops to below 30°C after cooling, and the SW1000 type finished dipped canvas is obtained.

[0041] Since the heat exchange efficiency of the experimental oven is generally 1 / 3 of the efficiency of the production line oven, the drying and heat treatment time is extended three times. That is, when producing SW1000 dipped canvas in the laboratory, the dipped canvas is sent to the oven for drying at 103°C for 20 minutes and heat treated at 110°C for 20 minutes. The remaining steps are the same as the preparation steps of the above-mentioned production line.

[0042] SW1000 finished canvas and molten thermoplastic polyurethane TPU (brand: BF85NAT 021, Lubrizol) was pressurized at 190°C for 5 minutes and then cooled to make a small sample. The cooled sample was cut into 25cm×2.5cm strips along the warp of the canvas. The force value of the bonding interface between the thermal polyurethane TPU and the canvas was tested on an electronic tensile testing machine, as shown in Table 3.

[0043] Table 3 Adhesive properties of samples obtained from Examples 1-4 and Comparative Examples

[0044] Compare Projects Example 1 Example 2 Example 3 Example 4 Comparative Example Adhesion performance (peel strength) 21.5N / mm 20N / mm 20.3N / mm 21.2N / mm 18.1N / mm

[0045] By comparing the bonding properties of the finished dipped canvases obtained in Examples 1-4 and the comparative example, it was found that the concentration change of the solid content of the dipping solution has a certain influence on the bonding properties of the finished canvas. Too low a concentration will reduce the peel strength of the bonding interface, while too high a concentration will increase the production cost and will not have a better effect. The solid content concentration of the dipping solution of the present application is 6%-15%. The bonding performance data of the dipped canvases obtained in Examples 1-4 are all greater than the bonding strength values ​​required by the national standard GB / T7984, and when the solid content is 10%, the bonding performance of the dipped canvas reaches the optimal level.

[0046] The present invention adopts a single-bath dipping process to impregnate the canvas, wherein one bath adopts the dipping solution prepared in Examples 1-3 of the present invention. After the surface of the thermoplastic polyurethane conveyor belt skeleton canvas is impregnated with the dipping solution of Examples 1-3, a heat setting and curing treatment is performed, thereby forming a dipping layer with blocked cyanate and water-based polyurethane on the surface of the thermoplastic polyurethane conveyor belt skeleton canvas.

[0047] Mechanism: Isocyanate contains highly reactive -NCO bonds, which can react with the epoxy groups on the surface of activated canvas, and can also react with the hydroxyl groups in waterborne polyurethane.

[0048] After the blocked isocyanate is unblocked at the unblocking temperature, two free -NCO groups are generated. Ideally, one end reacts with the epoxy group of the active layer on the fabric, and the other end reacts with the hydroxyl group in the waterborne polyurethane to obtain a dipping layer that can bond with the molten TPU.

[0049] Reaction mechanism of isocyanate and hydroxyl group: RNCO+R′OH→RNHCOOR′

[0050] Reaction mechanism of isocyanate and epoxy group:

[0051]

[0052] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A thermoplastic polyurethane conveyor belt skeleton material dipping solution, characterized in that: The composition comprises the following components by weight: 30-70 parts of blocked isocyanate, 30-70 parts of waterborne polyurethane, and 260-340 parts of deionized water, wherein the total amount of the blocked isocyanate, the waterborne polyurethane and the deionized water is 400 parts; The waterborne polyurethane is an anionic polyester polyurethane, and the blocked isocyanate is a waterborne aliphatic blocked isocyanate.

2. The method for preparing the thermoplastic polyurethane conveyor belt skeleton material dipping solution according to claim 1, characterized in that: The following steps are involved: By weight, add 260-340 parts of deionized water into a mixing kettle, then add 30-70 parts of blocked isocyanate, stir for 20-30 minutes, then add 30-70 parts of waterborne polyurethane, stir for 20-30 minutes, and obtain a dipping solution.

3. The application of the thermoplastic polyurethane conveyor belt skeleton material dipping solution described in claim 1 is characterized in that: The following steps are involved: The surface of the canvas of the thermoplastic polyurethane conveyor belt skeleton material is evenly coated with dipping liquid, and the amount of adhesive on the canvas surface is controlled at 4%-5%. After dipping, it enters the drying oven for drying, the drying temperature is controlled at 90-110°C, hot air drying is adopted, the residence time in the oven is 300-360s, and the tension is controlled at 4-5N / mm; then it enters the high-temperature oven for baking treatment, the oven temperature is 100-110°C, the baking time is 300-360s, and the tension is controlled at 8-10N / mm; cooling makes the surface temperature of the canvas drop below 30°C to obtain the finished canvas.

4. The application of the thermoplastic polyurethane conveyor belt skeleton material dipping solution according to claim 1, characterized in that: The skeleton material of the thermoplastic polyurethane conveyor belt includes one or more of polyester fiber, nylon fiber, aramid fiber, vinyl fiber, polyarylate fiber and PVO fiber.

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