Preparation process of water-based protein soft leather

Abstract

The invention provides a preparation process of water-based protein soft leather, belongs to the technical field of leather preparation, and solves the technical problem that an existing leather preparation process cannot realize accurate stripping of the water-based protein soft leather. The method comprises the following steps that unwinding and feeding are conducted; coating for the first time; coating for the second time; coating for the third time; plasticizing and drying; and rolling and collecting materials. The water-based material does not contain acetone, the production process comprises three layers, namely the water-based surface layer, the foaming layer and the adhesive layer, and water-based protein is dried at low temperature and low speed, so that when water-based polyurethane forms a film, pinholes and pits can be generated, the advanced stripping phenomenon is caused, and the water-based polyurethane film has the same effect as existing chamois grain cloth leather. Through the arrangement of the temperature control cooling device, the dried leather can be subjected to accurate temperature control cooling, so that the prepared leather is relatively soft in surface, very strong in skin feeling and exactly similar to baby skin.

Description

Technical Field

[0001] The invention belongs to the technical field of leather preparation, and relates to a leather preparation process, in particular to a water-based protein soft leather preparation process. Background Art

[0002] With the development of science and technology, the strength, wear resistance, moisture absorption, leather feel and other indicators of synthetic leather products have been greatly improved compared with the past, and its performance is getting closer and closer to natural leather. In some aspects, the performance even exceeds that of natural leather. The continuous improvement of performance has made people gradually accept this alternative material to natural leather and apply it to more areas of daily life.

[0003] As a composite material that can replace animal leather, synthetic leather is superior to animal leather in durability and cost-effectiveness, making it highly accepted in the consumer market and widely used in the production of shoes, boots, clothing, luggage, and balls. As consumer demand for high-quality synthetic leather products increases, the softness and comfort of synthetic leather become particularly important. Currently, the water-based synthetic leather on the market generally has a harder leather and is not soft enough.

[0004] After searching, it is found that a Chinese patent document discloses a water-based protein ultra-soft synthetic leather and its production process [Application number: CN202210547720.4; Publication number: CN115094643A]. This synthetic leather and its production process relate to the technical field of synthetic leather. The document discloses a water-based protein ultra-soft synthetic leather, which includes a surface layer, an intermediate layer and a base fabric from the outside to the inside; the intermediate layer is a 2-layer foaming layer or a 1-layer foaming layer and a 1-layer adhesive layer; the surface layer is formed by coating the surface layer slurry; the foaming layer is formed by coating the foaming layer slurry; the adhesive layer is formed by coating the adhesive layer slurry.

[0005] Although the synthetic leather disclosed in the patent improves the stability of low-density foams by combining two foaming agents, making the finished product feel softer, the synthetic leather is coated with slurry and the surface fabric is thick, which leads to a long subsequent drying time, affecting the softness of the leather, and the cooling temperature cannot be accurately controlled, resulting in poor texture forming and peeling effects on the surface of the soft leather, affecting the aesthetics and softness of the leather. Summary of the invention

[0006] The purpose of the present invention is to address the above-mentioned problems in the existing technology and to propose a process for preparing water-based protein soft leather. The technical problem to be solved by the invention is: how to achieve accurate peeling of water-based protein soft leather.

[0007] The purpose of the present invention can be achieved by the following technical solutions: A process for preparing water-based protein soft leather comprises the following steps: S1. Unwinding and loading: placing the centrifugal paper on the bracket of the unwinding equipment; S2, one-time coating: the centrifugal paper enters the first coating device, and the first coating device evenly coats the water-based polyurethane mixture on the centrifugal paper. After the coating is evenly applied, the centrifugal paper enters the first oven to remove the solvent water in the water-based polyurethane mixture, and then the centrifugal paper coated with the water-based polyurethane is cooled and shaped by the cooling roller device; S3, secondary coating: entering the second coating device, the second coating device evenly coats the water-based polyurethane pigment on the water-based polyurethane layer of the centrifugal paper, entering the second oven to evaporate the water, and then passing through the cooling roller device so that the dried centrifugal paper contacts the cooling roller for cooling and shaping; S4, three-time coating: entering the third coating device, the third coating device evenly coats the water-based adhesive on the dried polyurethane layer, and then enters the third oven for pre-baking to a semi-dry state, and then a layer of elastic mesh cloth base is attached, and then cooled and shaped by the cooling roller device; S5, plasticizing and drying: entering the fourth oven, continuing heating and plasticizing to make the cloth base and the polyurethane layer bond more firmly, and then cooling down to room temperature, using a cooling roller device for cooling and shaping; S6, Rolling and gathering: The leather paper after drying and shaping enters the rolling equipment, and the centrifugal paper and leather are separated by the peeling roller.

[0008] In step S2, the first oven is heated in a stepwise manner, increasing by 10°C each time, and the temperature is controlled at 90°C-120°C.

[0009] The temperature of the second oven in step S3 is 90°C-120°C.

[0010] The equipment used in steps S2, S3, S4 and S5 is a leather preparation device, which includes a coating device, a drying box and a temperature control cooling device fixedly installed at the discharge port of the drying box; The temperature control cooling device comprises a workbench, a coolant tank fixedly mounted at the bottom of the workbench, and a plurality of conveying rollers rotatably connected to the inside of the workbench, side plates are fixedly connected to both sides of the surface of the workbench, and a cooling cover is fixedly mounted on the inner side of the side plates, a fixed cooling roller is rotatably connected to the inside of the side plates, and the fixed cooling roller is located below the cooling cover, a temperature control cooling component is arranged on one side of the fixed cooling roller, and the temperature control cooling component is located inside the cooling cover; The temperature control cooling assembly includes a rotating rod, and the rotating rod is rotatably connected to the top of the side plate, the rotating rod is driven by a double-axis motor, and the double-axis motor is fixedly installed on the surface of the cooling cover, both ends of the rotating rod are fixedly connected to a first gear plate, and the first gear plate is located on the outer side of the side plate, the bottom end of the first gear plate is meshedly connected to the second gear plate, and the inside of the second gear plate is fixedly connected to a transmission rod, the transmission rod is rotatably connected to the inside of the side plate, and one side of the transmission rod is transmission-connected to a mounting rod, the mounting rod is arranged in parallel with the transmission rod, and the outer walls of the mounting rod and the transmission rod are fixedly connected to a lifting transmission unit, and two lifting transmission units are symmetrically arranged about the central axis of the workbench; The lifting transmission unit includes a first meshing wheel, and the first meshing wheel is fixedly mounted on the outer wall of the mounting rod, the outer wall of the first meshing wheel is meshingly connected with a meshing belt, and the bottom inner wall of the meshing belt is meshingly connected with a second meshing wheel, the second meshing wheel is rotatably connected to the inside of the side plate, the meshing belt is also meshingly connected to the top end of the first transmission wheel, one side of the first transmission wheel is rotatably connected with a movable block, and the movable block is lifted and lowered and arranged inside the side plate; The surface of the movable block is also rotatably connected to a rotating rod, and a second transmission wheel is fixedly installed on the outer wall of the rotating rod, and an engaging belt is meshingly connected to the outer wall of the second transmission wheel, one end of the rotating rod is fixedly connected to a temperature-controlled cooling roller, and a closing unit is connected to the outside of the temperature-controlled cooling roller, and a cooling unit is installed inside the temperature-controlled cooling roller.

[0011] In the present invention, the dried leather is conveyed to the top of the cooling hood by the conveying roller after being discharged from the drying box. Under the action of the fixed cooling roller rotatably arranged on the inner side of the side plate, the fixed cooling roller can cool down the surface of the leather. In order to achieve cooling of different leather surfaces at different temperatures, the temperature control cooling component is arranged, so that the rotating rod drives the first gear plates on both sides to rotate, and under the meshing action of the first gear plate and the second gear plate, the second gear plate drives the transmission rod, and under the action of the transmission connection between the transmission rod and the mounting rod, the lifting transmission unit rotates synchronously, and a movable block is arranged inside the lifting transmission unit, and the rotation of the screw rod When the gear plate is engaged, the two screw rods are engaged with each other at the bottom ends of the two screw rods, and the two movable blocks are staggered when they are lifted or lowered, so that one movable block rises while the other movable block falls. Moreover, under the action of the meshing belt, the meshing belt always drives the second transmission wheel to rotate, which is convenient for the rotation of the rotating rod, and the rotation effect of the second transmission wheel during height adjustment is achieved, so that the two temperature-controlled cooling rollers with different cooling temperatures can work accurately and alternately according to the cooling requirements, and the rotation effect of the temperature-controlled cooling roller on the leather surface is ensured. At the same time, the rotating rod is used to rotate the second transmission wheel to rotate the second transmission wheel. The outer wall of the gear plate is connected to the rotation of the gear plate, so that the rotating rod drives the temperature-controlled cooling roller to rise and fall synchronously to realize the lifting and lowering of the gear plate, and the gear column is meshed with the outer wall of the gear plate to make the gear column rotate inside the fixed plate, and under the meshing action of the gear column and the gear rod, the gear rod drives the closing plate to rotate horizontally at the bottom end of the fixed plate. Through such an arrangement, the temperature-controlled cooling roller can rise to the inside of the fixed plate when not working. Under the rotation action of the gear column, the closing plate closes the bottom of the fixed plate, thereby avoiding the loss of cold when the temperature-controlled cooling roller is not working. At the same time, in order to ensure the cooling effect of the temperature-controlled cooling roller, an internal gear ring is fixedly connected to the inner wall of the temperature-controlled cooling roller Under the action of, through the meshing of the inner gear ring and the outer gear, and the connecting rod is fixedly connected at both ends of the outer gear, under the fixed connection between the connecting rod and the toothed plate, the outer gear drives the liquid nitrogen roller to rotate inside and below the temperature-controlled cooling roller, and the sealing plate is connected by rotating inside the temperature-controlled cooling roller. Under the fixed action of the second magnetic block, the second magnetic block is magnetically connected to the first magnetic block, so that the sealing plate is always under the temperature-controlled cooling roller to seal the liquid nitrogen roller, thereby ensuring the cooling effect of the liquid nitrogen roller. In addition, in order to achieve precise temperature control of the liquid nitrogen roller when the temperature-controlled cooling roller rotates, it is beneficial to increase the contact area between the bottom of the temperature-controlled cooling roller and the leather, thereby ensuring the cooling quality of the leather.

[0012] The interior of the movable block is connected to a screw rod through a ball nut, and the screw rod is rotatably connected to the interior of the side plate. The outer walls of the two screw rods are fixedly connected to gear plates, and the two gear plates are meshed and connected to each other. One of the screw rods is transmission-connected to the lifting transmission unit on the other side of the workbench.

[0013] By adopting the above structure, the screw rod is rotated, so that the screw rod can drive the movable block to move up and down inside the side plate. Under the action of the staggered meshing of the gear plates at the bottom ends of the two screw rods, the two screw rods rotate in opposite directions, so that the two movable blocks are staggered when they are lifted and lowered, so that one movable block rises while the other movable block falls, so that two temperature-controlled cooling rollers with different cooling temperatures can work according to the cooling requirements, thereby realizing precise cooling of the leather surface and having strong practicality.

[0014] The outer walls of the screw rods on both sides of the workbench are fixedly connected with second synchronous wheels, and the second synchronous wheels are located below the workbench. The outer wall meshing sleeves of the two second synchronous wheels are provided with second synchronous belts, and one of the screw rods is fixedly connected with the output end of the bidirectional motor, and the bidirectional motor is fixedly installed at the bottom end of the workbench.

[0015] With the above structure, the second synchronous wheel and the second synchronous belt are set to make the screws on both sides of the workbench rotate synchronously, ensuring the balance of the temperature-controlled cooling roller through the lifting transmission unit for height adjustment, which is convenient for precise contact cooling of the leather surface.

[0016] The outer walls of the transmission rod and the mounting rod are both fixedly connected with first synchronous wheels, and the outer walls of the two first synchronous wheels are meshedly connected with first synchronous belts.

[0017] With the above structure, through the arrangement of the first synchronous wheel and the first synchronous belt, the two lifting transmission units are made to rotate synchronously, so as to realize the staggered transmission of the two temperature-controlled cooling rollers.

[0018] The closing unit includes two fixed plates, which are fixedly mounted on the inner top wall of the cooling cover, and the two fixed plates are respectively located on both sides of the temperature-controlled cooling roller, a gear column is rotatably connected to the bottom of the fixed plate, and one side of the gear column is meshingly connected to a toothed plate, the toothed plate is rotatably mounted on the outer wall of the rotating rod, and the toothed plate is slidably connected to the inner sides of the two fixed plates, the bottom end of the gear column is meshingly connected to a gear rod, and one side of the gear rod is fixedly connected to a closing plate, and the closing plate is slidably connected to the bottom end of the fixed plate.

[0019] By adopting the above structure and setting the closing unit, when the movable block drives the rotating rod to rise and fall, the rotating rod synchronously drives the tooth plate to rise and fall, and the gear column is meshed and connected with the outer wall of the tooth plate, so that the gear column rotates inside the fixed plate, and under the meshing action of the gear column and the tooth rod, the tooth rod drives the closing plate to rotate laterally at the bottom end of the fixed plate. Through such a setting, the temperature-controlled cooling roller can rise to the inside of the fixed plate when not working, and under the rotation action of the gear column, the closing plate closes the bottom of the fixed plate, which is beneficial to reduce the loss of coldness of the temperature-controlled cooling roller and reduce the use cost of the temperature-controlled cooling roller.

[0020] The outer end of the gear rod is fixedly connected to a side block, and a telescopic spring is fixedly installed on the inner side of the side block, and the other side of the telescopic spring is fixedly connected to the outer wall of the fixed plate; The top end of the tooth plate is fixedly connected with a connecting block, and the outer wall of the connecting block is slidably connected with a sliding groove, and the sliding groove is arranged on the surface of the fixed plate.

[0021] By adopting the above structure, the transmission effect and reset effect of the gear rod are ensured by setting the telescopic spring, and the stability of the gear plate driven by the rotating rod when it is raised or lowered is improved by slidingly connecting the gear plate with the fixed plate, thereby ensuring the transmission effect of the gear plate on the gear column.

[0022] The cooling unit includes an inner gear ring, and the inner gear ring is fixedly installed on the inner wall of the temperature-controlled cooling roller, the inner wall of the inner gear ring is meshedly connected with an outer gear, and a connecting rod is fixedly installed on the outer wall of the outer gear, the other end of the connecting rod is rotatably connected to one side of the toothed plate, and the connecting rod is parallel to the rotating rod, the inner side of the outer gear is fixedly connected with a liquid nitrogen roller, and the liquid nitrogen roller is rotatably installed below the temperature-controlled cooling roller; The temperature-controlled cooling roller is internally rotatably connected with a sealing plate, the sealing plate is sleeved on the outside of the liquid nitrogen roller, and the top end of the sealing plate is embeddedly connected with a first magnetic block; A fixing rod is fixedly installed on the top end of the tooth plate, and a second magnetic block is fixedly connected to the bottom end of the fixing rod, and the second magnetic block is magnetically connected to the first magnetic block; The outer wall of the temperature-controlled cooling roller is provided with a plurality of through holes at equal intervals in an annular shape.

[0023] By adopting the above structure, an inner gear ring is fixedly installed inside the temperature-controlled cooling roller, and the meshing connection between the inner gear ring and the outer gear makes the temperature-controlled cooling roller drive the outer gear to rotate when it rotates. By fixing connecting rods at both ends of the outer gear, and the fixed connection between the connecting rod and the toothed plate, the outer gear drives the liquid nitrogen roller to rotate inside and below the temperature-controlled cooling roller. Through such an arrangement, when the temperature-controlled cooling roller rotates to cool down, the liquid nitrogen roller always rotates inside and below the temperature-controlled cooling roller. At the same time, a sealing plate is rotatably connected inside the temperature-controlled cooling roller, and under the fixed action of the second magnetic block, the second magnetic block and the first magnetic block are magnetically connected, so that the sealing plate always seals the liquid nitrogen roller below the temperature-controlled cooling roller, thereby ensuring the cooling effect of the liquid nitrogen roller. In order to achieve precise temperature control of the liquid nitrogen roller when the temperature-controlled cooling roller rotates, a plurality of through holes are equidistantly opened on the outer wall of the temperature-controlled cooling roller, so that the liquid nitrogen roller can achieve precise cooling of the temperature-controlled cooling roller on the leather surface through the through holes.

[0024] Compared with the prior art, the water-based protein soft leather preparation process of the present invention has the following advantages: 1. In the present invention, the aqueous material component does not contain acetone, and the production process includes three layers, namely, an aqueous surface layer, a foaming layer and an adhesive layer. Moreover, by slowly drying the aqueous protein at a low temperature, pinholes and pits are generated when the aqueous polyurethane is formed into a film, resulting in premature peeling. Like the existing suede-grained cloth leather, the surface texture is beautiful. Moreover, through the setting of the temperature control cooling device, the leather after drying can be accurately temperature-controlled and cooled, so that the surface of the prepared leather is relatively soft, the skin feel is very strong, and it is very similar to baby skin.

[0025] 2. In the present invention, through the temperature-controlled cooling device, under the action of the temperature-controlled cooling rollers, through the setting of the temperature-controlled cooling assembly, the two temperature-controlled cooling rollers can be accurately lowered according to processing requirements, and under the meshing setting of the two gear plates, the two movable blocks are staggered when lifting, so that one movable block rises while the other movable block falls, and under the action of the meshing belt, the meshing belt always drives the second transmission wheel to rotate, which is convenient for the rotating rod to rotate and realize the rotation effect of the second transmission wheel when the height is adjusted, so that the two temperature-controlled cooling rollers with different cooling temperatures can work accurately alternately according to cooling requirements, and the temperature-controlled cooling rollers can accurately control the temperature and cool the surface of the leather.

[0026] 3. In the present invention, under the action of the lifting transmission unit and the closing unit, when the movable block drives the rotating rod to lift, the rotating rod synchronously drives the tooth plate to lift, and the gear column is connected by meshing with the outer wall of the tooth plate, so that the gear column rotates inside the fixed plate, and under the meshing action of the gear column and the gear rod, the gear rod drives the closing plate to rotate horizontally at the bottom end of the fixed plate. Through such an arrangement, the temperature-controlled cooling roller can rise to the inside of the fixed plate when not working, and under the rotation action of the gear column, the closing plate closes the bottom of the fixed plate, which is beneficial to reduce the loss of coldness of the temperature-controlled cooling roller and reduce the use cost of the temperature-controlled cooling roller.

[0027] 4. In the present invention, by arranging a cooling unit inside the temperature-controlled cooling roller, the temperature-controlled cooling roller can synchronously drive the rotation of the liquid nitrogen roller when rotating for cooling, and by arranging the liquid nitrogen roller inside and below the temperature-controlled cooling roller, the liquid nitrogen roller always cools the surface of the leather, thereby improving the cooling quality of the temperature-controlled cooling roller, and through the rotation of the liquid nitrogen roller, the contact area of ​​the liquid nitrogen roller inside the temperature-controlled cooling roller is increased, which is beneficial to improving the cooling effect of the temperature-controlled cooling roller. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a process flow chart of preparing water-based protein soft leather.

[0029] Figure 2 It is a structural schematic diagram of the temperature control cooling device and the drying box in the present invention.

[0030] Figure 3 It is a structural schematic diagram of the temperature control cooling device in the present invention.

[0031] Figure 4 It is a schematic diagram of the cross-sectional structure of the cooling hood and the temperature-controlled cooling roller in the present invention.

[0032] Figure 5 The present invention Figure 2 A is an enlarged structural diagram of FIG.

[0033] Figure 6 It is a side structural schematic diagram of the temperature control cooling device in the present invention.

[0034] Figure 7 It is a structural schematic diagram of the lifting transmission unit in the present invention.

[0035] Figure 8 It is a schematic diagram of the installation structure of the gear plate and the workbench in the present invention.

[0036] Fig. 9 It is a structural schematic diagram of the closed unit in the present invention.

[0037] Fig.10 It is a schematic diagram of the cross-sectional structure of the closed unit in the present invention.

[0038] Fig.11 It is a schematic diagram of the side cross-sectional structure of the cooling unit in the present invention.

[0039] Fig.12 It is a schematic diagram of the connection structure between the outer gear and the inner gear ring in the present invention.

[0040] Fig.13 It is a front view structural schematic diagram of the outer gear and the inner gear ring in the present invention; Fig.14 It is a performance test table of the experimental examples in the present invention.

[0041] In the figure, 1, drying box; 2, workbench; 3, coolant tank; 4, conveying roller; 5, side plate; 6, cooling cover; 7, fixed cooling roller; 8, temperature-controlled cooling roller; 9, fixed plate; 10, rotating rod; 11, first gear plate; 12, second gear plate; 13, transmission rod; 14, first synchronous wheel; 15, first synchronous belt; 16, mounting rod; 17, first meshing wheel; 18, meshing belt; 19, second meshing wheel; 20, first transmission wheel; 21, movable block; 22, rotating rod; 23, first Second transmission wheel; 24, screw rod; 25, gear plate; 26, second synchronous wheel; 27, second synchronous belt; 28, bidirectional motor; 29, gear column; 30, gear plate; 31, connecting block; 32, slide groove; 33, gear rod; 34, closing plate; 35, side block; 36, telescopic spring; 37, connecting rod; 38, external gear; 39, internal gear ring; 40, liquid nitrogen roller; 41, dual-axis motor; 42, sealing plate; 43, first magnetic block; 44, through hole; 45, fixing rod; 46, second magnetic block. DETAILED DESCRIPTION

[0042] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0043] Example 1 like Figure 1 As shown, a process for preparing water-based protein soft leather of the present invention comprises the following steps: S1. Unwinding and loading: placing the centrifugal paper on the bracket of the unwinding equipment; S2, one-time coating: the centrifugal paper enters the first coating device, the first coating device evenly coats the water-based polyurethane mixture on the centrifugal paper, the water-based material component does not contain acetone, and after the coating is evenly applied, it enters the first oven to remove the solvent water in the water-based polyurethane mixture. Specifically, the first oven adopts a step-by-step temperature increase, each time increasing by 10°C, and the temperature is controlled at 90°C, and then the centrifugal paper coated with water-based polyurethane is cooled and shaped by a cooling roller device; S3, secondary coating: entering the second coating device, the second coating device evenly coats the water-based polyurethane pigment on the water-based polyurethane layer of the centrifugal paper, entering the second oven to evaporate water, the temperature of the second oven is 90°C, and then passing through the cooling roller device, so that the dried centrifugal paper contacts the cooling roller for cooling and shaping; S4, three-time coating: entering the third coating device, the third coating device evenly coats the water-based adhesive on the dried polyurethane layer, and then enters the third oven for pre-baking to a semi-dry state, and then a layer of elastic mesh cloth base is attached, and then cooled and shaped by the cooling roller device; S5, plasticizing and drying: entering the fourth oven, continuing heating and plasticizing to make the cloth base and the polyurethane layer bond more firmly, and then cooling down to room temperature, using a cooling roller device for cooling and shaping; S6, Rolling and gathering: The leather paper after drying and shaping enters the rolling equipment, and the centrifugal paper and leather are separated by the peeling roller.

[0044] The equipment used in steps S2, S3, S4 and S5 is a leather preparation device, which includes a coating device, a drying box 1 and a temperature control cooling device fixedly installed at the discharge port of the drying box 1; See also Figure 2-Figure 13 The temperature control cooling device includes a workbench 2, a coolant tank 3 fixedly installed at the bottom of the workbench 2, a plurality of conveying rollers 4 rotatably connected to the inside of the workbench 2, a side plate 5, a cooling cover 6, a fixed cooling roller 7, a temperature control cooling roller 8, a fixed plate 9, a rotating rod 10, a first gear plate 11, a second gear plate 12, a transmission rod 13, a first synchronous wheel 14, a first synchronous belt 15, a mounting rod 16, a first meshing wheel 17, a meshing belt 18, a second meshing wheel 19, a first transmission wheel 20, a movable block 21, a rotating rod 22, a second transmission wheel 23, a screw rod 24, a gear plate 25, a second synchronous wheel 26, a second synchronous belt 27, a bidirectional motor 28, a gear column 29, a tooth plate 30, a connecting block 31, a slide groove 32, a gear rod 33, a sealing The closing plate 34, the side block 35, the telescopic spring 36, the connecting rod 37, the external gear 38, the internal gear ring 39, the liquid nitrogen roller 40 and the double-axis motor 41 are fixedly connected to the side plates 5 on both sides of the surface of the workbench 2, and the inner side of the side plates 5 is fixedly installed with a cooling cover 6, and the inner side of the side plates 5 is rotatably connected with a fixed cooling roller 7, and the fixed cooling roller 7 is located below the cooling cover 6. Through the setting of the conveying roller 4, it is convenient to cool the leather dried by the drying box 1 inside the cooling cover 6, and considering the processing and cooling of the water-based protein leather, the conveying roller 4, the fixed cooling roller 7 and the temperature-controlled cooling roller 8 are all made of stainless steel, which avoids the problem that the solvent water in the water-based material is easy to rust and slag due to the iron material after volatilization, thereby ensuring the production effect of the product; Furthermore, in order to meet different cooling requirements, a temperature control cooling component is provided on one side of the fixed cooling roller 7, and the temperature control cooling component is located inside the cooling cover 6. Specifically, a rotating rod 10 is provided in the temperature control cooling component, and the rotating rod 10 is rotatably connected to the top of the side plate 5. The rotating rod 10 is driven by a dual-axis motor 41, and the dual-axis motor 41 is fixedly installed on the surface of the cooling cover 6. Both ends of the rotating rod 10 are fixedly connected to a first gear plate 11, and the first gear plate 11 is located on the outer side of the side plate 5. The bottom end of the first gear plate 11 is meshedly connected to a second gear plate 12, and the interior of the second gear plate 12 is fixedly connected to a transmission rod 13, and the transmission rod 13 rotates The mounting rod 16 is connected to the inner side of the side plate 5, and one side of the transmission rod 13 is connected to the mounting rod 16 in a transmission manner. Specifically, the outer walls of the transmission rod 13 and the mounting rod 16 are fixedly connected to the first synchronous wheel 14, and the outer walls of the two first synchronous wheels 14 are meshed and connected to the first synchronous belt 15. The mounting rod 16 and the transmission rod 13 are arranged in parallel, and the outer walls of the mounting rod 16 and the transmission rod 13 are fixedly connected to the lifting transmission unit. Through the arrangement of the first synchronous wheel 14 and the first synchronous belt 15, the two lifting transmission units are synchronously rotated, which is convenient for the subsequent staggered transmission of the two temperature-controlled cooling rollers 8, and two lifting transmission units are symmetrically arranged about the central axis of the workbench 2. Further, the lifting transmission unit includes a first meshing wheel 17, and the first meshing wheel 17 is fixedly mounted on the outer wall of the mounting rod 16, the outer wall of the first meshing wheel 17 is meshedly connected with a meshing belt 18, and the bottom inner wall of the meshing belt 18 is meshedly connected with a second meshing wheel 19, the second meshing wheel 19 is rotatably connected to the inside of the side plate 5, the meshing belt 18 is also meshedly connected to the top of the first transmission wheel 20, one side of the first transmission wheel 20 is rotatably connected with a movable block 21, and the movable block 21 is lifted and set on the side plate 5 The interior of the movable block 21 is connected to a screw rod 24 through a ball nut, and the screw rod 24 is rotatably connected to the inside of the side plate 5. The outer walls of the two screw rods 24 are fixedly connected to a gear plate 25, and the two gear plates 25 are meshed and connected with each other. One of the screw rods 24 is transmission-connected to the lifting transmission unit on the other side of the workbench 2. The outer walls of the screw rods 24 on both sides of the workbench 2 are fixedly connected to a second synchronous wheel 26, and the second synchronous wheel 26 is located below the workbench 2. The outer walls of the two second synchronous wheels 26 are fixedly connected to the lifting transmission unit on the other side of the workbench 2. The wall engagement sleeve is provided with a second synchronous belt 27, and one of the screw rods 24 is fixedly connected to the output end of the bidirectional motor 28, and the bidirectional motor 28 is fixedly installed at the bottom end of the workbench 2. Through the setting of the second synchronous wheel 26 and the second synchronous belt 27, the screw rods 24 on both sides of the workbench 2 are rotated synchronously, ensuring the balance of the height adjustment of the temperature-controlled cooling roller 8 through the lifting transmission unit, which is convenient for accurate contact cooling of the leather surface. At the same time, through the setting of the lifting transmission unit, under the rotation of the screw rod 24, the screw rod 24 can drive the movable block 21 to move up and down inside the side plate 5. Under the action of the staggered meshing of the gear plate 25 at the bottom ends of the two screw rods 24, the two screw rods 24 rotate in opposite directions, so that the two movable blocks 21 are staggered when lifting, so that one movable block 21 rises while the other movable block 21 falls, so that the two temperature-controlled cooling rollers 8 with different cooling temperatures can work according to the cooling requirements, and the leather surface is accurately cooled, which is highly practical. The surface of the movable block 21 is also rotatably connected to a rotating rod 22, and a second transmission wheel 23 is fixedly installed on the outer wall of the rotating rod 22, and the outer wall of the second transmission wheel 23 is meshedly connected to a meshing belt 18, one end of the rotating rod 22 is fixedly connected to a temperature-controlled cooling roller 8, and the outer side of the temperature-controlled cooling roller 8 is connected to a closing unit. Specifically, the closing unit includes two fixed plates 9, which are fixedly installed on the inner top wall of the cooling cover 6, and the two fixed plates 9 are respectively located on both sides of the temperature-controlled cooling roller 8, and a gear column 29 is rotatably connected to the lower part of the fixed plate 9, and one side of the gear column 29 is connected to the inner top wall of the cooling cover 6. The side is meshedly connected with a toothed plate 30, which is rotatably mounted on the outer wall of the rotating rod 22, and the toothed plate 30 is slidably connected to the inner sides of the two fixed plates 9. The bottom end of the gear column 29 is meshedly connected with a toothed rod 33, and one side of the toothed rod 33 is fixedly connected to a closing plate 34, and the closing plate 34 is slidably connected to the bottom end of the fixed plate 9. The outer end of the toothed rod 33 is fixedly connected to a side block 35, and a telescopic spring 36 is fixedly mounted on the inner side of the side block 35, and the other side of the telescopic spring 36 is fixedly connected to the outer wall of the fixed plate 9. The arrangement of the telescopic spring 36 ensures that the toothed rod 33 In order to achieve the transmission effect and reset effect, the top of the toothed plate 30 is fixedly connected with a connecting block 31, and the outer wall of the connecting block 31 is slidably connected with a slide groove 32, and the slide groove 32 is arranged on the surface of the fixed plate 9. By slidably connecting the toothed plate 30 with the fixed plate 9, the stability of the toothed plate 30 driven by the rotating rod 22 when it is lifted is improved, and the transmission effect of the toothed plate 30 on the gear column 29 is ensured. Through such a setting, under the action of the closing unit, when the movable block 21 drives the rotating rod 22 to lift, the rotating rod 22 synchronously drives the toothed plate 30 to lift. By meshing the gear column 29 with the outer wall of the toothed plate 30, the gear column 29 is rotated inside the fixed plate 9. Under the meshing action of the gear column 29 and the gear rod 33, the gear rod 33 drives the closing plate 34 to rotate laterally at the bottom end of the fixed plate 9. Through such an arrangement, the temperature-controlled cooling roller 8 can rise to the inside of the fixed plate 9 when not working. Under the rotation action of the gear column 29, the closing plate 34 closes the bottom of the fixed plate 9, which is beneficial to reduce the loss of coldness of the temperature-controlled cooling roller 8 and reduce the use cost of the temperature-controlled cooling roller 8.

[0045] Furthermore, a cooling unit is installed inside the temperature-controlled cooling roller 8, and the cooling unit includes an inner gear ring 39, and the inner gear ring 39 is fixedly installed on the inner wall of the temperature-controlled cooling roller 8, the inner wall of the inner gear ring 39 is meshedly connected with an outer gear 38, and a connecting rod 37 is fixedly installed on the outer wall of the outer gear 38, the other end of the connecting rod 37 is rotatably connected to one side of the toothed plate 30, and the connecting rod 37 is parallel to the rotating rod 22, and the inner side of the outer gear 38 is fixedly connected with a liquid nitrogen roller 40, and the liquid nitrogen roller 40 is rotatably installed below the temperature-controlled cooling roller 8, and the temperature-controlled cooling The roller 8 is rotatably connected to a sealing plate 42, which is sleeved on the outside of the liquid nitrogen roller 40. The top of the sealing plate 42 is engaged with a first magnetic block 43. A fixing rod 45 is fixedly installed on the top of the toothed plate 30, and a second magnetic block 46 is fixedly connected to the bottom of the fixing rod 45. The second magnetic block 46 is magnetically connected to the first magnetic block 43. A plurality of through holes 44 are equidistantly provided in an annular shape on the outer wall of the temperature-controlled cooling roller 8. An inner gear ring 39 is fixedly installed inside the temperature-controlled cooling roller 8. Under the meshing connection between the inner gear ring 39 and the outer gear 38, the temperature-controlled cooling roller 8 is controlled. The temperature-controlled cooling roller 8 drives the outer gear 38 to rotate when it rotates. The connecting rod 37 is fixedly connected to both ends of the outer gear 38. The connecting rod 37 is fixedly connected to the toothed plate 30, so that the outer gear 38 drives the liquid nitrogen roller 40 to rotate inside and below the temperature-controlled cooling roller 8. When the temperature-controlled cooling roller 8 rotates to cool down, the liquid nitrogen roller 40 always rotates inside and below the temperature-controlled cooling roller 8 under the action of the cooling unit. At the same time, the sealing plate 42 is connected to the temperature-controlled cooling roller 8 by rotating it. Under the fixed action of the second magnetic block 46, the second magnetic block 46 is magnetically connected with the first magnetic block 43, so that the sealing plate 42 always seals the liquid nitrogen roller 40 below the temperature-controlled cooling roller 8, thereby ensuring the cooling effect of the liquid nitrogen roller 40. In addition, in order to achieve precise temperature control of the liquid nitrogen roller 40 by the temperature-controlled cooling roller 8 when it rotates, a plurality of through holes 44 are equidistantly provided on the outer wall of the temperature-controlled cooling roller 8, so that the liquid nitrogen roller 40 can achieve precise cooling of the temperature-controlled cooling roller 8 on the leather surface through the through holes 44. Through such an arrangement, the temperature-controlled cooling roller 8 can perform precise discharge cooling on the liquid nitrogen inside the liquid nitrogen roller 40.

[0046] Working principle: When in use, the dried leather is discharged from the drying box 1 and then conveyed by the conveying roller 4 to the top of the cooling cover 6. Under the action of the fixed cooling roller 7 rotating on the inner side of the side plate 5, the fixed cooling roller 7 can cool the surface of the leather. In order to achieve cooling of different leather surfaces at different temperatures, the temperature control cooling component is set to make the rotating rod 10 drive the first gear plate 11 on both sides to rotate. Under the meshing action of the first gear plate 11 and the second gear plate 12, the second gear plate 12 drives the transmission rod 13. Under the action of the transmission connection between the transmission rod 13 and the mounting rod 16, the lifting transmission unit rotates synchronously. The movable block 21 is set inside the lifting transmission unit. Under the rotation action of the screw rod 24, The screw rod 24 can drive the movable block 21 to move up and down inside the side plate 5. Under the action of the staggered meshing of the gear plate 25 at the bottom ends of the two screw rods 24, the two screw rods 24 rotate in opposite directions, so that the two movable blocks 21 are staggered when they are lifted, so that one movable block 21 rises while the other movable block 21 falls, and under the action of the meshing belt 18, the meshing belt 18 always drives the second transmission wheel 23 to rotate, which is convenient for the rotation of the rotating rod 22, and the rotation effect of the second transmission wheel 23 when the height is adjusted is achieved, so that the two temperature-controlled cooling rollers 8 with different cooling temperatures can work accurately and alternately according to the cooling requirements, and the rotation effect of the temperature-controlled cooling roller 8 on the leather surface is ensured. At the same time, by rotating the outer wall of the rotating rod 22 When the tooth plate 30 is connected, the rotating rod 22 drives the temperature-controlled cooling roller 8 to rise and fall synchronously with the tooth plate 30. By meshing the gear column 29 on the outer wall of the tooth plate 30, the gear column 29 is rotated inside the fixed plate 9. Under the meshing action of the gear column 29 and the tooth rod 33, the tooth rod 33 drives the closing plate 34 to rotate horizontally at the bottom end of the fixed plate 9. Through such an arrangement, the temperature-controlled cooling roller 8 can rise to the inside of the fixed plate 9 when not working. Under the rotation action of the gear column 29, the closing plate 34 closes the bottom of the fixed plate 9, thereby avoiding the loss of coldness of the temperature-controlled cooling roller 8 when not working. At the same time, in order to ensure the cooling effect of the temperature-controlled cooling roller 8, under the action of the inner gear ring 39 fixedly connected to the inner wall of the temperature-controlled cooling roller 8 , through the meshing of the inner gear ring 39 and the outer gear 38, and the connecting rod 37 is fixedly connected at both ends of the outer gear 38, under the fixed connection between the connecting rod 37 and the toothed plate 30, the outer gear 38 drives the liquid nitrogen roller 40 to rotate inside and below the temperature-controlled cooling roller 8, and the sealing plate 42 is connected by rotating inside the temperature-controlled cooling roller 8. Under the fixed action of the second magnetic block 46, the second magnetic block 46 is magnetically connected to the first magnetic block 43, so that the sealing plate 42 is always sealed below the temperature-controlled cooling roller 8 to ensure the cooling effect of the liquid nitrogen roller 40, and in order to achieve accurate temperature control of the liquid nitrogen roller 40 when the temperature-controlled cooling roller 8 rotates, it is beneficial to increase the contact area between the bottom of the temperature-controlled cooling roller 8 and the leather, thereby ensuring the cooling quality of the leather.This completes the water-based protein soft leather preparation process.

[0047] Example 2 The difference between this embodiment and embodiment 1 is that: in step S2, the first oven is heated in a stepwise manner, increasing by 10°C each time, and the temperature is controlled at 100°C; The temperature of the second oven in step S3 is 110°C.

[0048] In this embodiment, the equipment used in steps S2, S3, S4 and S5 is a leather preparation device.

[0049] Example 3 The difference between this embodiment and embodiment 1 is that in step S2, the first oven is heated in a stepwise manner, increasing by 10°C each time, and the temperature is controlled at 120°C.

[0050] The temperature of the second oven in step S3 is 120°C; In this embodiment, the equipment used in steps S2, S3, S4 and S5 is a leather preparation device.

[0051] Example 4 The difference between this embodiment and embodiment 1 is that in step S2, the first oven is heated in a stepwise manner, increasing by 10°C each time, and the temperature is controlled at 120°C.

[0052] The temperature of the second oven in step S3 is 120°C; In this embodiment, the equipment used in steps S2, S3, S4 and S5 is the existing coating equipment, drying equipment and cooling equipment.

[0053] Experimental example 200 pieces of the soft leathers prepared in Examples 1-4 were taken, and the same artificial leather was prepared by the existing water-based protein soft leather preparation process. The prepared soft leathers were tested for performance according to GB / T 8948-2008, GB / T 7568.2-2008, QB / T 4043-2010, SATRA TM163-1996 and QB / T 4870-2015. The test results are shown in the attached figure. Fig.14 : By the attached Fig.14 It can be seen that the preparation equipment used in Example 3 and Example 4 is different, but the tensile strength, wear resistance, yellowing resistance and softness of the soft leather in Example 3 are stronger than those in Example 4. Therefore, the use of the leather preparation device in the present invention can improve the tensile strength, wear resistance, yellowing resistance and softness of the soft leather.

[0054] Compared with Example 1, Example 2 and Example 3 only have different processing conditions, and the equipment used in the processing steps are the same. The tensile strength, wear resistance, yellowing resistance and softness of the soft leather in Example 1 and Example 3 are weaker than those in Example 2. It can be seen that different drying temperatures will also affect the tensile strength, wear resistance, yellowing resistance and softness of the soft leather.

[0055] To sum up, the water-based material composition does not contain acetone, and the production process includes three layers, namely, a water-based surface layer, a foaming layer and an adhesive layer. Moreover, by slowly drying the water-based protein at a low temperature, pinholes and pits will be generated when the water-based polyurethane is formed into a film, resulting in premature peeling. Like the existing suede-grained cloth leather, the surface texture is beautiful, and through the setting of the temperature control cooling device, the dried leather can be precisely temperature-controlled and cooled, so that the prepared leather surface is relatively soft and has a very strong skin feel, similar to baby skin. The existing water-based protein soft leather process cannot achieve the technical problem of precise peeling of water-based protein soft leather.

[0056] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A process for preparing water-based protein soft leather, characterized in that: The following steps are involved: S1. Unwinding and loading: placing the centrifugal paper on the bracket of the unwinding equipment; S2, one-time coating: the centrifugal paper enters the first coating device, and the first coating device evenly coats the water-based polyurethane mixture on the centrifugal paper. After the coating is evenly applied, the centrifugal paper enters the first oven to remove the solvent water in the water-based polyurethane mixture, and then the centrifugal paper coated with the water-based polyurethane is cooled and shaped by the cooling roller device; S3, secondary coating: entering the second coating device, the second coating device evenly coats the water-based polyurethane pigment on the water-based polyurethane layer of the centrifugal paper, entering the second oven to evaporate the water, and then passing through the cooling roller device so that the dried centrifugal paper contacts the cooling roller for cooling and shaping; S4, three-time coating: entering the third coating device, the third coating device evenly coats the water-based adhesive on the dried polyurethane layer, and then enters the third oven for pre-baking to a semi-dry state, and then a layer of elastic mesh cloth base is attached, and then cooled and shaped by the cooling roller device; S5, plasticizing and drying: entering the fourth oven, continuing heating and plasticizing to make the cloth base and the polyurethane layer bond more firmly, and then cooling down to room temperature, using a cooling roller device for cooling and shaping; S6, Rolling and gathering: The leather paper after drying and shaping enters the rolling equipment, and the centrifugal paper and leather are separated by the peeling roller.

2. A process for preparing water-based protein soft leather according to claim 1, characterized in that: In step S2, the first oven is heated in a stepwise manner, increasing by 10°C each time, and the temperature is controlled at 90°C-120°C.

3. A process for preparing water-based protein soft leather according to claim 2, characterized in that: The temperature of the second oven in step S3 is 90°C-120°C.

4. A process for preparing water-based protein soft leather according to any one of claims 1 to 3, characterized in that: The equipment used in steps S2, S3, S4 and S5 is a leather preparation device, which comprises a coating device, a drying box (1) and a temperature control cooling device fixedly installed at the discharge port of the drying box (1); The temperature control cooling device comprises a workbench (2), a coolant tank (3) fixedly mounted at the bottom of the workbench (2), and a plurality of conveying rollers (4) rotatably connected to the inside of the workbench (2); side plates (5) are fixedly connected to both sides of the surface of the workbench (2), and a cooling hood (6) is fixedly mounted on the inner side of the side plates (5); a fixed cooling roller (7) is rotatably connected to the inside of the side plates (5), and the fixed cooling roller (7) is located below the cooling hood (6); a temperature control cooling component is provided on one side of the fixed cooling roller (7), and the temperature control cooling component is located inside the cooling hood (6); The temperature control cooling component comprises a rotating rod (10), and the rotating rod (10) is rotatably connected to the top of the side plate (5), the rotating rod (10) is driven by a double-axis motor (41), and the double-axis motor (41) is fixedly mounted on the surface of the cooling cover (6), both ends of the rotating rod (10) are fixedly connected to a first gear plate (11), and the first gear plate (11) is located on the outside of the side plate (5), the bottom end of the first gear plate (11) is meshingly connected to a second gear plate (12), and the inside of the second gear plate (12) is fixedly connected to a transmission rod (13), the transmission rod (13) is rotatably connected to the inside of the side plate (5), and one side of the transmission rod (13) is transmission-connected to a mounting rod (16), the mounting rod (16) and the transmission rod (13) are arranged in parallel, and the outer walls of the mounting rod (16) and the transmission rod (13) are fixedly connected to a lifting transmission unit, and two lifting transmission units are symmetrically arranged about the central axis of the workbench (2); The lifting transmission unit comprises a first meshing wheel (17), and the first meshing wheel (17) is fixedly mounted on the outer wall of the mounting rod (16); the outer wall of the first meshing wheel (17) is meshingly connected with a meshing belt (18), and the bottom inner wall of the meshing belt (18) is meshingly connected with a second meshing wheel (19); the second meshing wheel (19) is rotatably connected to the inside of the side plate (5); the meshing belt (18) is also meshingly connected to the top end of the first transmission wheel (20); one side of the first transmission wheel (20) is rotatably connected with a movable block (21); the movable block (21) is lifted and lowered and arranged inside the side plate (5); The surface of the movable block (21) is also rotatably connected to a rotating rod (22), and a second transmission wheel (23) is fixedly mounted on the outer wall of the rotating rod (22), and a meshing belt (18) is meshingly connected to the outer wall of the second transmission wheel (23), and one end of the rotating rod (22) is fixedly connected to a temperature-controlled cooling roller (8), and a closing unit is connected to the outer side of the temperature-controlled cooling roller (8), and a cooling unit is mounted inside the temperature-controlled cooling roller (8).

5. A process for preparing water-based protein soft leather according to claim 4, characterized in that: The movable block (21) is internally connected to a screw rod (24) via a ball nut, and the screw rod (24) is rotatably connected to the inside of the side plate (5), the outer walls of the two screw rods (24) are fixedly connected to a gear plate (25), and the two gear plates (25) are meshedly connected to each other, and one of the screw rods (24) is drivingly connected to a lifting transmission unit on the other side of the workbench (2).

6. A process for preparing water-based protein soft leather according to claim 5, characterized in that: The outer walls of the screw rods (24) on both sides of the workbench (2) are fixedly connected to second synchronous wheels (26), and the second synchronous wheels (26) are located below the workbench (2). The outer walls of the two second synchronous wheels (26) are meshing sleeves with second synchronous belts (27), and one of the screw rods (24) is fixedly connected to the output end of a bidirectional motor (28), and the bidirectional motor (28) is fixedly installed at the bottom end of the workbench (2).

7. A process for preparing water-based protein soft leather according to claim 4, characterized in that: The outer walls of the transmission rod (13) and the mounting rod (16) are both fixedly connected with a first synchronous wheel (14), and the outer walls of the two first synchronous wheels (14) are meshingly connected with a first synchronous belt (15).

8. The process for preparing water-based protein soft leather according to claim 4, characterized in that: The closing unit comprises two fixed plates (9), the fixed plates (9) are fixedly mounted on the inner top wall of the cooling cover (6), and the two fixed plates (9) are respectively located on both sides of the temperature-controlled cooling roller (8), a gear column (29) is rotatably connected to the bottom of the fixed plate (9), and one side of the gear column (29) is meshingly connected to a toothed plate (30), the toothed plate (30) is rotatably mounted on the outer wall of the rotating rod (22), and the toothed plate (30) is slidably connected to the inner side of the two fixed plates (9), the bottom end of the gear column (29) is meshingly connected to a toothed rod (33), and one side of the toothed rod (33) is fixedly connected to a closing plate (34), and the closing plate (34) is slidably connected to the bottom end of the fixed plate (9).

9. A process for preparing water-based protein soft leather according to claim 8, characterized in that: The outer end of the gear rod (33) is fixedly connected to a side block (35), and a telescopic spring (36) is fixedly installed on the inner side of the side block (35), and the other side of the telescopic spring (36) is fixedly connected to the outer wall of the fixed plate (9); The top end of the tooth plate (30) is fixedly connected to a connecting block (31), and the outer wall of the connecting block (31) is slidably connected to a sliding groove (32), and the sliding groove (32) is provided on the surface of the fixed plate (9).

10. The process for preparing water-based protein soft leather according to claim 4, characterized in that: The cooling unit comprises an inner gear ring (39), and the inner gear ring (39) is fixedly mounted on the inner wall of the temperature-controlled cooling roller (8), the inner wall of the inner gear ring (39) is meshingly connected with an outer gear (38), and a connecting rod (37) is fixedly mounted on the outer wall of the outer gear (38), the other end of the connecting rod (37) is rotatably connected to one side of the toothed plate (30), and the connecting rod (37) and the rotating rod (22) are arranged in parallel, the inner side of the outer gear (38) is fixedly connected with a liquid nitrogen roller (40), and the liquid nitrogen roller (40) is rotatably mounted below the temperature-controlled cooling roller (8); The temperature-controlled cooling roller (8) is rotatably connected to a sealing plate (42) inside, the sealing plate (42) is sleeved on the outside of the liquid nitrogen roller (40), and the top end of the sealing plate (42) is engaged with a first magnetic block (43); A fixing rod (45) is fixedly mounted on the top end of the tooth plate (30), and a second magnetic block (46) is fixedly connected to the bottom end of the fixing rod (45), and the second magnetic block (46) is magnetically connected to the first magnetic block (43); The outer wall of the temperature-controlled cooling roller (8) is provided with a plurality of through holes at equal intervals in an annular manner.

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