Preparation process of slush molding PVC skin based on modified PVC material

Abstract

The invention relates to the technical field of PVC material preparation, in particular to a slush molding PVC skin preparation process based on a modified PVC material, which comprises the following steps: heating a slush molding mold, conveying a material box containing PVC slush molding powder to the lower part of the slush molding mold, and connecting and coupling the material box and the slush molding mold; turning over the coupled material box and slush molding mold for a plurality of times, separating the material box from the slush molding mold after the redundant PVC slush molding powder falls into the material box, cooling the slush molding mold, and demolding to output a finished product slush molding skin; determining the interval duration between the heating moment and the cooling moment based on the average roughness of the sampling area in the finished product slush molding skin; the first overturning speed of the slush molding mold is determined based on the proportion of the number of defective products in the slush molding skin of the finished product; and the second overturning speed is determined based on the maximum thickness difference quantity of the finished product slush molding skin. According to the invention, the preparation accuracy of the PVC material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of PVC material preparation, in particular to a slush-molded PVC skin preparation process based on modified PVC material. Background Art

[0002] In the prior art, slush molding, also known as rotational molding, is a process for manufacturing hollow parts with thermoplastic and / or thermosetting resins. The products manufactured by this process can have various shapes and have a continuous thickness ranging from 0.5-15mm. During the manufacturing process of the product, the outer surface of the product depends on the shape of the inner surface of the mold. During the rotation process, the powder enters the mold, contacts the hot mold, melts and forms a sheet of uneven thickness on the inner wall of the mold.

[0003] Chinese Patent Publication No.: CN105385071A discloses a slush-molded PVC material for automobile interior skin and a preparation method thereof, comprising the following steps: 1) weighing each reaction substance according to a weight ratio; 2) mixing any three or four of dioctyl sebacate, propylene glycol adipate, trioctyl trimellitate, tridecyl trimellitate, diacetyl epoxy vegetable oil glyceride, and phosphite in a premixing tank for 5 to 20 minutes; 3) heating the materials in the premixing tank to 50 to 70° C., and then adding tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) [propionic acid] pentaerythritol ester is added and stirred until it is completely dissolved; 4) the suspension type polyvinyl chloride resin is put into the reactor, the stirring speed is 100-300 rpm, and the temperature is initially raised to 50-70°C, and then zinc maleopimarate, zinc stearate, calcium stearate, hydrotalcite, oleamide, pentaerythritol, and inorganic pigment are added in sequence; 5) the materials in the premix tank are added to the reactor by spraying; 6) after heating to 110-130°C, the powder in the reactor is discharged to the cooling kettle by 250-350 rpm high-speed stirring centrifugal action, and the material is discharged after stirring and cooling. It can be seen that the slush molding PVC material for automotive interior skin and the preparation method thereof have the problem that part of the PVC slush molding powder cannot be completely fitted with the slush molding mold during the preparation process, resulting in an uneven surface of the finished slush molding skin, which in turn increases the surface roughness of the finished slush molding skin, thereby causing the preparation accuracy of the modified PVC material to decrease. Summary of the invention

[0004] To this end, the present invention provides a slush-molded PVC skin preparation process based on modified PVC material, which is used to overcome the problem in the prior art that part of the PVC slush-molding powder cannot be completely fitted with the slush-molding mold during the preparation process, resulting in an uneven surface of the finished slush-molded skin, which in turn increases the surface roughness of the finished slush-molded skin and causes a decrease in the preparation accuracy of the modified PVC material.

[0005] To achieve the above-mentioned purpose, the present invention provides a slush molding PVC skin preparation process based on modified PVC material, comprising the following steps: heating the slush molding mold, conveying a material box containing PVC slush molding powder to the bottom of the slush molding mold, and connecting and coupling the material box and the slush molding mold; flipping the coupled material box and the slush molding mold several times, separating the material box and the slush molding mold after the excess PVC slush molding powder falls into the material box, cooling the slush molding mold, and then demolding it to output the finished slush molding skin; and performing a time interval between the heating time and the cooling time based on the average roughness of the sampling area in the finished slush molding skin. Determine, or respectively obtain the number of defective products in several finished slush molded skins and the total number of finished slush molded skins; determine a first flipping speed of the slush mold based on the proportion of defective products in the finished slush molded skins, or determine the running speed of the material box based on the proportion of defective products in the finished slush molded skins and the average weight of several finished slush molded skins; obtain the thickness of the finished slush molded skin output after a single cycle of operation at the first flipping speed of the slush mold; determine a second flipping speed based on the maximum thickness difference of the finished slush molded skins; wherein the first flipping speed is less than the second flipping speed.

[0006] Furthermore, the components and mass proportions of the finished slush-molded skin are: 10 parts of PVC base material, 3 parts of plasticizer, 0.4 parts of stabilizer, 0.2 parts of colorant, 0.2 parts of desiccant, and 0.05 parts of internal release agent.

[0007] Furthermore, the step of determining the interval between the heating moment and the cooling moment also includes determining the preparation accuracy of the modified PVC material based on the average roughness of the sampling area in the finished slush molded skin;

[0008] Wherein, if the average roughness of the sampling area in the finished product slush molding surface meets the first roughness condition or meets the second roughness condition, it is determined that the preparation accuracy of the modified PVC material is lower than the allowable range;

[0009] When the average roughness of the sampling area in the finished product slush mold surface meets the trigger condition for determining the interval between the heating moment and the cooling moment, the slush mold is heated and cooled according to the determined interval;

[0010] Among them, the trigger condition is that the average roughness of the sampling area in the finished product plastic skin only meets the second roughness condition, and the interval between the heating moment and the cooling moment is determined by the difference between the average roughness of the sampling area in the finished product plastic skin and the preset second roughness.

[0011] Furthermore, the calculation formula for the average roughness of the sampling area in the finished product slush molding surface is:

[0012]

[0013] Among them, G is the average roughness of the sampling area in the finished plastic surface, K b is the roughness of the bth sampling area in the finished plastic surface, u is the number of sampling areas, and u is a natural number greater than or equal to 1.

[0014] Furthermore, the first roughness condition is that the average roughness of the sampling area in the finished product slush molding surface is greater than the preset first roughness and less than or equal to the preset second roughness; the second roughness condition is that the average roughness of the sampling area in the finished product slush molding surface is greater than the preset second roughness.

[0015] Further, the step of determining the first flipping speed of the slush mold comprises:

[0016] The number of defective products in several finished slush-molded skins and the total number of finished slush-molded skins in a single preparation cycle are obtained respectively, and the proportion of the number of defective products in the finished slush-molded skins is calculated;

[0017] Compare the percentage of defective products in the finished product slush molded skin with the preset first percentage and the preset second percentage respectively;

[0018] If the proportion of defective products in the finished product slush molding surface is greater than the preset first proportion and less than or equal to the preset second proportion, the slush molding mold is controlled to flip the slush molding mold at the first flipping speed.

[0019] Furthermore, the first flipping speed of the slush mold is determined by the difference between the proportion of defective products in the surface of the finished slush molded product and a preset first proportion.

[0020] Furthermore, if the proportion of defective products in the finished product slush molding skin is greater than the preset second proportion, it is preliminarily determined that the effectiveness of the coupling between the material box and the slush molding mold is lower than the allowable range.

[0021] Furthermore, the step of determining the running speed of the feed box further includes secondarily determining the effectiveness of the coupling between the feed box and the slush mold based on the average weight of the plurality of finished slush molded skins.

[0022] If the average weight of the surface of the several finished slush molded products is greater than the preset weight, it is determined that the effectiveness of the coupling between the material box and the slush mold is lower than the allowable range, and the material box is controlled to move according to the running speed of the material box;

[0023] The running speed of the material box is determined by the difference between the average weight of a number of finished slush-molded skins and a preset weight.

[0024] Further, the step of determining the second flipping speed of the slush mold comprises:

[0025] The thickness of the finished product slush-molded surface in a single operation cycle is obtained, and the maximum thickness difference of the finished product slush-molded surface is calculated;

[0026] Comparing the maximum thickness difference of the finished product slush-molded skin with a preset difference;

[0027] If the maximum thickness difference of the finished product slush molded skin is greater than the preset difference, controlling the slush mold to flip the slush mold at the second flipping speed;

[0028] The second flipping speed of the slush mold is determined by the difference between the maximum thickness difference of the finished slush molded skin and a preset difference.

[0029] Compared with the prior art, the beneficial effect of the present invention lies in that the process of the present invention adjusts the interval between the heating moment and the cooling moment according to the average roughness of the sampling area in the finished product slush molding surface. Since part of the PVC slush molding powder cannot be completely fitted with the slush molding mold during the preparation process, the surface of the finished product slush molding surface is uneven, thereby increasing the surface roughness of the finished product slush molding surface. By shortening the interval between the heating moment and the cooling moment, the temperature difference between the PVC slush molding powder and the mold and the stress caused by thermal expansion and contraction are reduced as much as possible, which helps to improve the adhesion, so that the slush molding surface fits the mold surface more closely, and the generation of surface unevenness and roughness is reduced. By adjusting the flipping speed of the slush molding mold according to the proportion of defective products in the finished product slush molding surface, since gas heating is used in the heating process of the slush molding mold, when the heating temperature reaches the predetermined temperature, the heat is not easy to dissipate, resulting in the temperature of the heating area being too high, causing part of the PVC slush molding powder to be more easily adsorbed on the mold surface after melting, thereby causing the quality of the finished product slush molding surface to be unstable, and increasing the defective rate of the product. By reducing the flipping speed of the slush mold, the temperature rise rate of the heating area can be slowed down, which helps to reduce the accumulation of heat in the heating area and reduce the risk of local overheating, which helps to ensure the uniformity and consistency of the slush surface, thereby improving the surface quality stability of the finished slush surface. By adjusting the running speed of the material box according to the average weight of several finished slush skins, due to the aging of the material of the moving structure of the material box, it is impossible to stop in time when reaching the target position of the material box, resulting in deviation, so that it is impossible to couple tightly with the slush mold, resulting in the leakage of some PVC slush powder, and the weight of the finished slush skin is reduced. By reducing the moving speed of the material box, the accuracy of the material box movement is improved, so that the coupling is tighter. By adjusting the first flipping speed of the slush mold according to the maximum thickness difference of the finished slush skin, due to the slow flipping speed, the thickness of the finished slush skin is wavy, resulting in excessive thickness difference. By increasing the flipping speed, the roughness of the slush skin is reduced, and the preparation accuracy and environmental protection of the modified PVC are improved.

[0030] Furthermore, the process of the present invention adjusts the interval between the heating moment and the cooling moment by setting a preset first roughness and a preset second roughness. Since part of the PVC slush molding powder cannot be completely fitted with the slush molding mold during the preparation process, the surface of the finished slush molding skin is uneven, thereby increasing the surface roughness of the finished slush molding skin. By shortening the interval between the heating moment and the cooling moment, the temperature difference between the PVC slush molding powder and the mold and the stress caused by thermal expansion and contraction are minimized, which helps to improve adhesion, so that the slush molding skin fits the mold surface more closely, reduces the generation of surface unevenness and roughness, and further achieves the improvement of the preparation accuracy and environmental protection of the modified PVC.

[0031] Furthermore, the process of the present invention adjusts the flipping speed of the slush mold by setting a preset first ratio and a preset second ratio. Since gas heating is used in the heating process of the slush mold, when the heating temperature reaches a predetermined temperature, the heat is not easy to dissipate, resulting in the temperature of the heating area being too high, causing part of the PVC slush powder to be more easily adsorbed on the mold surface after melting, thereby resulting in unstable quality of the finished slush skin and increasing the defective rate of the product. By reducing the flipping speed of the slush mold, the temperature rise rate of the heating area can be slowed down, which helps to reduce heat accumulation in the heating area, reduce the risk of local overheating, and help ensure the uniformity and consistency of the slush skin, thereby improving the surface quality stability of the finished slush skin, and further achieving the improvement of the preparation accuracy and environmental protection of the modified PVC.

[0032] Furthermore, the process of the present invention adjusts the running speed of the material box by setting a preset weight. Due to material aging of the moving structure of the material box, it is unable to stop in time when reaching the target position of the material box, resulting in deviation, so that it is unable to be tightly coupled with the slush mold, resulting in leakage of part of the PVC slush powder, and reducing the weight of the finished slush skin. By reducing the moving speed of the material box, the accuracy of the movement of the material box is improved, thereby making the coupling tighter, and further achieving the improvement of the preparation accuracy and environmental protection of the modified PVC.

[0033] Furthermore, the process of the present invention adjusts the first flipping speed of the slush mold by setting a preset difference amount. Since the flipping speed is too slow, the thickness of the finished slush molded surface is wavy, resulting in excessive thickness difference. By increasing the flipping speed, the roughness of the slush molded surface is reduced, further achieving the improvement of the preparation accuracy and environmental protection of the modified PVC. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1This is an overall flow chart of a process for preparing a slush-molded PVC skin based on a modified PVC material according to an embodiment of the present invention;

[0035] Figure 2 A specific flow chart of the process of determining the first flipping speed of the slush mold in the slush molded PVC skin preparation process based on the modified PVC material according to an embodiment of the present invention;

[0036] Figure 3 A specific flow chart of the process of determining the second flipping speed of the slush mold in the slush molding PVC skin preparation process based on the modified PVC material according to an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the structure of a rotating component in a process for preparing a slush-molded PVC skin based on a modified PVC material according to an embodiment of the present invention;

[0038] The reference numerals are as follows: 1-material box, 2-slush mold, 3-clamping claw, 4-rotating motor, 5-rotating shaft, 6-vertical pole, 7-slide rail, 8-slide plate, 9-slide rail motor. DETAILED DESCRIPTION

[0039] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with 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.

[0040] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0041] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0042] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] It should be pointed out that the data in this embodiment are obtained by the present invention's slush-molded PVC skin preparation process based on modified PVC materials before the current test based on historical data and data statistics in the corresponding test process, test experiments and comprehensive analysis based on experimental results; the present invention's slush-molded PVC skin preparation process based on modified PVC materials before the current test is based on the average roughness of the sampling area in the finished slush-molded skins of 1684 cases of cumulative statistics, testing and calculation within 95 days, the proportion of defective products in the finished slush-molded skins, the average weight of several finished slush-molded skins and the maximum thickness difference of the finished slush-molded skins, and comprehensively determine the values ​​of various preset parameter standards for the slush-molded PVC skin preparation process based on modified PVC materials. It can be understood by those skilled in the art that the determination method for the slush-molded PVC skin preparation process based on modified PVC materials described in the present invention for a single parameter can be to select the value with the highest proportion as the preset standard parameter according to the data distribution, as long as the process described in the present invention can clearly define different specific situations in the single determination process through the obtained values.

[0044] See also Figure 1 , Figure 2 , Figure 3 as well as Figure 4 As shown, they are respectively an overall flow chart of a slush molding PVC skin preparation process based on a modified PVC material according to an embodiment of the present invention, a specific flow chart of a process for determining a first flipping speed of a slush molding mold, a specific flow chart of a process for determining a second flipping speed of a slush molding mold, and a structural schematic diagram of a rotating assembly. A slush molding PVC skin preparation process based on a modified PVC material according to an embodiment of the present invention comprises the following steps:

[0045] Step S1, heating the slush mold, conveying a material box containing PVC slush powder to the bottom of the slush mold, and connecting and coupling the material box and the slush mold;

[0046] Step S2, the coupled material box and the slush mold are turned over several times, and the excess PVC slush powder falls into the material box, and then the material box and the slush mold are separated, and the slush mold is cooled and demolded to output the finished slush skin;

[0047] Step S3, determining the interval between the heating moment and the cooling moment based on the average roughness of the sampling area in the finished slush molded skin, or obtaining the number of defective products in a number of finished slush molded skins and the total number of finished slush molded skins respectively;

[0048] Step S4, determining a first flipping speed of the slush mold based on the percentage of defective products in the finished slush skin, or determining a running speed of the material box based on the percentage of defective products in the finished slush skin and the average weight of a plurality of finished slush skins;

[0049] Step S5, obtaining the thickness of the finished slush molded product output after running the slush mold for a single cycle at the first flipping speed;

[0050] Step S6, determining the second flipping speed based on the maximum thickness difference of the finished product slush-molded skin;

[0051] Wherein, the first flipping speed is smaller than the second flipping speed.

[0052] Specifically, the formula for calculating the percentage of defective products in the finished plastic skin is:

[0053]

[0054] Among them, P is the proportion of defective products in the finished plastic skin, Z1 is the number of defective products in several finished plastic skins, and Z2 is the total number of finished plastic skins.

[0055] Specifically, the defective product among the finished product slush molded skins is the finished product slush molded skin whose surface roughness is greater than or equal to 15 μm.

[0056] Specifically, the average weight of several finished plastic skins is calculated as follows:

[0057]

[0058] Among them, T is the average weight of several finished plastic skins, S d is the weight of the d-th finished product plastic skin, c is the number of finished product plastic skins, and c is a natural number greater than or equal to 1.

[0059] Specifically, the maximum thickness difference of the finished slush skin is calculated as follows:

[0060] F=E1-E2

[0061] Among them, F is the maximum thickness difference of the finished product slush-molded skin, E1 is the maximum thickness of the same piece of finished product slush-molded skin, and E2 is the minimum thickness of the same piece of finished product slush-molded skin.

[0062] Specifically, the time interval between the heating time and the cooling time means the time interval between the time when the slush mold starts to be heated and the time when the slush mold starts to be cooled.

[0063] Specifically, the ingredients of PVC slush powder include PVC resin, plasticizer, stabilizer and filler.

[0064] Optionally, a preferred embodiment of the plasticizer is diethylhexyl phthalate, a preferred embodiment of the stabilizer is calcium zinc stabilizer, and a preferred embodiment of the filler is talc.

[0065] Specifically, the PVC resin is in granular form with a particle size of 200 μm, diethylhexyl phthalate is an oily liquid, the calcium zinc stabilizer is in powder form with a particle size of 80 μm, and the talc is in powder form with a particle size of 30 μm.

[0066] Specifically, the step of obtaining the roughness of the sampling area in the finished product slush molding skin is to divide the surface of the finished product slush molding skin into a number of equally spaced sampling areas, and use a laser sensor to perform roughness detection on the several equally spaced sampling areas respectively.

[0067] Specifically, the rotating components for coupling and rotating the material box and the slush mold include:

[0068] Material box 1, used for storing PVC slush powder;

[0069] A slide plate 8 connected to the material box 1 to support the material box 1;

[0070] A slide rail 7 connected to the slide plate 8 to provide a moving path for the slide plate 8;

[0071] A slide rail motor 9, which is connected to the slide rail 7 and is used to provide movement power for the material box 1;

[0072] A slush mold 2, which is arranged above the material box 1 and is used to shape the PVC slush powder;

[0073] A clamping claw 3 connected to the slush mold 2 for coupling the material box 1 and the slush mold 2;

[0074] A rotating shaft 5 connected to the clamping claw 3 for rotating the coupled material box 1 and the slush mold 2;

[0075] A rotating motor 4 connected to the rotating shaft 5 to provide rotating power;

[0076] The vertical rod 6 is connected to the rotating shaft 5 to provide a moving path for the rotating shaft 5 in the vertical direction.

[0077] Specifically, the running speed of the material box is adjusted by changing the speed of the slide rail motor.

[0078] Specifically, the flipping speed of the slush mold is adjusted by changing the rotation speed of the rotary motor.

[0079] Specifically, the weight of the finished slush-molded skin is detected by a weight sensor.

[0080] Specifically, the thickness of the finished slush skin is detected by a thickness sensor.

[0081] In implementation, the process of the present invention adjusts the interval between the heating moment and the cooling moment according to the average roughness of the sampling area in the finished product slush molding surface. Since part of the PVC slush molding powder cannot be completely fitted with the slush molding mold during the preparation process, the surface of the finished product slush molding surface is uneven, thereby increasing the surface roughness of the finished product slush molding surface. By shortening the interval between the heating moment and the cooling moment, the temperature difference between the PVC slush molding powder and the mold and the stress caused by thermal expansion and contraction are minimized, which helps to improve adhesion, so that the slush molding surface fits the mold surface more closely, and reduces the generation of surface unevenness and roughness. By adjusting the flipping speed of the slush molding mold according to the proportion of defective products in the finished product slush molding surface, since gas heating is used in the heating process of the slush molding mold, when the heating temperature reaches the predetermined temperature, the heat is not easy to dissipate, resulting in the temperature of the heating area being too high, causing part of the PVC slush molding powder to be more easily adsorbed on the mold surface after melting, thereby causing the quality of the finished product slush molding surface to be unstable, increasing the defective rate of the product, and reducing the slush molding. The flipping speed of the mold can slow down the temperature rise rate of the heating area, help reduce the accumulation of heat in the heating area, reduce the risk of local overheating, and help ensure the uniformity and consistency of the slush-molded skin, thereby improving the surface quality stability of the finished slush-molded skin. By adjusting the running speed of the material box according to the average weight of several finished slush-molded skins, due to material aging of the moving structure of the material box, it is impossible to stop in time when reaching the target position of the material box, resulting in deviations, which makes it impossible to couple tightly with the slush-molding mold, causing some PVC slush-molding powder to leak out, and the weight of the finished slush-molded skin is reduced. By reducing the moving speed of the material box, the accuracy of the material box movement is improved, thereby making the coupling tighter. By adjusting the first flipping speed of the slush-molded mold according to the maximum thickness difference of the finished slush-molded skin, due to the slow flipping speed, the thickness of the finished slush-molded skin becomes wavy, resulting in excessive thickness difference. By increasing the flipping speed, the roughness of the slush-molded skin is reduced, and the preparation accuracy and environmental protection of the modified PVC are improved.

[0082] Specifically, the components and mass proportions of the finished slush-molded skin are: 10 parts of PVC base material, 3 parts of plasticizer, 0.4 parts of stabilizer, 0.2 parts of colorant, 0.2 parts of desiccant, and 0.05 parts of internal release agent.

[0083] Specifically, the step of determining the interval between the heating moment and the cooling moment also includes determining the preparation accuracy of the modified PVC material based on the average roughness of the sampling area in the finished slush molded surface;

[0084] Wherein, if the average roughness of the sampling area in the finished product slush molding surface meets the first roughness condition or meets the second roughness condition, it is determined that the preparation accuracy of the modified PVC material is lower than the allowable range;

[0085] If the average roughness of the sampling area in the finished product slush molding surface only meets the preset first roughness condition, it is preliminarily determined that the contact effectiveness between the PVC slush molding powder and the mold is lower than the allowable range, and a secondary judgment is made on the contact effectiveness between the PVC slush molding powder and the mold based on the proportion of defective products in the finished product slush molding surface.

[0086] Specifically, the first roughness condition is that the average roughness of the sampling area in the finished product slush molding surface is greater than the preset first roughness and less than or equal to the preset second roughness; the second roughness condition is that the average roughness of the sampling area in the finished product slush molding surface is greater than the preset second roughness.

[0087] It can be understood that the three intervals corresponding to the preset first roughness Q1 and the preset second roughness Q2 correspond to three situations respectively. The first interval is Q≤Q1, which corresponds to the situation that the preparation accuracy of the modified PVC material is within the allowable range; the second interval is Q1<Q≤Q2, which corresponds to the situation that the gas heating method is used in the heating process of the slush mold. When the heating temperature reaches the predetermined temperature, the heat is not easy to dissipate, resulting in the temperature of the heating area being too high, causing part of the PVC slush powder to melt and be more easily adsorbed on the mold surface; the third interval is Q>Q2, which corresponds to the situation that part of the PVC slush powder cannot be completely fitted with the slush mold during the preparation process, resulting in the uneven surface of the finished slush skin. In practice, the range of Q1 is generally selected from [13μm, 17μm], and the range of Q2 is generally selected from [18μm, 22μm].

[0088] Preferably, the first roughness Q1 is preset to be 15 μm, and the second roughness Q2 is preset to be 20 μm.

[0089] Specifically, the average roughness of the sampling area in the finished slush skin is recorded as Q.

[0090] In implementation, the process of the present invention determines the preparation accuracy of the modified PVC material by setting a preset first roughness and a preset second roughness, thereby reducing the impact of the inaccurate determination of the preparation accuracy of the modified PVC material on the environmental friendliness of the preparation of the modified PVC material, and further achieving the improvement of the preparation accuracy and environmental friendliness of the modified PVC.

[0091] Specifically, when the average roughness of the sampling area in the finished product slush mold surface meets the trigger condition for determining the interval between the heating moment and the cooling moment, the slush mold is heated and cooled according to the determined interval;

[0092] Among them, the trigger condition is that the average roughness of the sampling area in the finished product plastic skin only meets the second roughness condition, and the interval between the heating moment and the cooling moment is determined by the difference between the average roughness of the sampling area in the finished product plastic skin and the preset second roughness.

[0093] Specifically, the interval between the heating moment and the cooling moment is reduced by the difference between the average roughness of the sampling area in the finished slush molding surface and the preset second roughness. The calculation formula for the reduced interval between the heating moment and the cooling moment is:

[0094]

[0095] Among them, V' is the interval between the heating moment and the cooling moment after the reduction, V is the current interval between the heating moment and the cooling moment, A is the minimum unit roughness for adjusting the interval between the heating moment and the cooling moment, and v is the interval between the heating moment and the cooling moment when the average roughness of the sampling area in the finished plastic surface is the minimum unit roughness.

[0096] In practice, the value of A is generally 23 μm to 27 μm. Preferably, the preferred embodiment of A is 25 μm.

[0097] In practice, the optional range of the value of v is [2min, 4min]. Preferably, when the interval between the heating moment and the cooling moment is longer than 3min, the surface of the finished slush molding may become uneven. Therefore, the preferred embodiment of v is 3min.

[0098] For example, the PVC material is prepared using the slush molding PVC skin preparation process based on modified PVC material, where V = 4min, Q = 30μm, and the calculation is

[0099] In implementation, the process of the present invention adjusts the interval between the heating moment and the cooling moment by setting a preset first roughness and a preset second roughness. Since part of the PVC slush molding powder cannot be completely fitted with the slush molding mold during the preparation process, the surface of the finished slush molding skin is uneven, thereby increasing the surface roughness of the finished slush molding skin. By shortening the interval between the heating moment and the cooling moment, the temperature difference between the PVC slush molding powder and the mold and the stress caused by thermal expansion and contraction are minimized, which helps to improve adhesion, make the slush molding skin fit the mold surface more closely, reduce the generation of surface unevenness and roughness, and further achieve the improvement of the preparation accuracy and environmental protection of the modified PVC.

[0100] Specifically, the calculation formula for the average roughness of the sampling area in the finished slush molding surface is:

[0101]

[0102] Among them, G is the average roughness of the sampling area in the finished plastic surface, K b is the roughness of the bth sampling area in the finished plastic surface, u is the number of sampling areas, and u is a natural number greater than or equal to 1.

[0103] Specifically, the step of determining the first flipping speed of the slush mold includes:

[0104] The number of defective products in several finished slush-molded skins and the total number of finished slush-molded skins in a single preparation cycle are obtained respectively, and the proportion of the number of defective products in the finished slush-molded skins is calculated;

[0105] Compare the percentage of defective products in the finished product slush molded skin with the preset first percentage and the preset second percentage respectively;

[0106] If the proportion of defective products in the finished product slush molding surface is greater than the preset first proportion, it is secondarily determined that the contact effectiveness between the PVC slush molding powder and the mold is lower than the allowable range;

[0107] If the proportion of defective products in the finished product slush molding surface is greater than the preset first proportion and less than or equal to the preset second proportion, the slush molding mold is controlled to flip the slush molding mold at the first flipping speed.

[0108] It can be understood that the three intervals corresponding to the preset first proportion P1 and the preset second proportion P2 correspond to three situations respectively. The first interval is P≤P1, corresponding to the situation that the contact effectiveness between the PVC slush powder and the mold is within the allowable range. The second interval is P1<P≤P2, corresponding to the situation that the gas heating method is used in the heating process of the slush mold. When the heating temperature reaches the predetermined temperature, the heat is not easy to dissipate, resulting in the temperature of the heating area being too high, causing some PVC slush powder to melt and be more easily adsorbed on the mold surface; the third interval is P>P2, corresponding to the situation that the moving structure of the material box has material aging, resulting in the inability to stop in time when reaching the target position of the material box, thereby causing some PVC slush powder to leak out. In practice, the range of P1 is generally selected from [0.03, 0.05], and the range of P2 is generally selected from [0.05, 0.07].

[0109] Preferably, the preferred embodiment of the preset first proportion P1 is 0.04, and the preferred embodiment of the preset second proportion P2 is 0.06.

[0110] Specifically, the percentage of defective products in the finished plastic skin is denoted by P.

[0111] In implementation, the process of the present invention sets a preset first ratio and a preset second ratio. Since the ratio of the number of defective products in the finished product slush molding skin can characterize the contact effectiveness between the PVC slush molding powder and the mold, a secondary judgment is made on the contact effectiveness between the PVC slush molding powder and the mold. This reduces the impact of the reduced preparation accuracy of the modified PVC material due to the inaccurate secondary judgment on the contact effectiveness between the PVC slush molding powder and the mold, thereby further achieving improved preparation accuracy and environmental friendliness of the modified PVC.

[0112] Specifically, the first flipping speed of the slush mold is determined by the difference between the proportion of defective products in the surface of the finished slush molded product and a preset first proportion.

[0113] Specifically, the flipping speed of the slush mold is reduced by the difference between the proportion of defective products in the finished slush mold surface and the preset first proportion. The calculation formula of the first flipping speed of the slush mold after the reduction is:

[0114]

[0115] Among them, H' is the first flipping speed of the slush mold, H is the current flipping speed of the slush mold, B is the minimum unit proportion for adjusting the flipping speed of the slush mold, and h is the flipping speed of the slush mold when the proportion of defective products in the finished slush skin is the minimum unit proportion.

[0116] In practice, the value of B is generally 0.07 to 0.09, and preferably, the preferred embodiment of B is 0.08.

[0117] In implementation, the optional range of h is [25 rpm, 35 rpm]. Preferably, when the flipping speed of the slush mold is greater than 30 rpm, some PVC slush powder may be more easily adsorbed on the mold surface after melting. Therefore, the preferred embodiment of h is 30 rpm.

[0118] For example, the PVC material is prepared using the slush molding PVC skin preparation process based on modified PVC material, where H = 35 rpm, P = 0.08, and the calculation result is RPM.

[0119] In implementation, the process of the present invention adjusts the flipping speed of the slush mold by setting a preset first ratio and a preset second ratio. Since gas heating is used in the heating process of the slush mold, when the heating temperature reaches a predetermined temperature, the heat is not easy to dissipate, resulting in the temperature of the heating area being too high, causing part of the PVC slush powder to be more easily adsorbed on the mold surface after melting, thereby causing the quality of the finished slush skin to be unstable and increasing the defective rate of the product. By reducing the flipping speed of the slush mold, the temperature rise rate of the heating area can be slowed down, which helps to reduce the accumulation of heat in the heating area, reduce the risk of local overheating, and help ensure the uniformity and consistency of the slush skin, thereby improving the surface quality stability of the finished slush skin, and further achieving the improvement of the preparation accuracy and environmental protection of the modified PVC.

[0120] Specifically, if the proportion of defective products in the finished product slush molding skin is greater than the preset second proportion, it is preliminarily determined that the effectiveness of the coupling between the material box and the slush molding mold is lower than the allowable range.

[0121] Specifically, the step of determining the running speed of the feed box further includes secondarily determining the effectiveness of the coupling between the feed box and the slush mold based on the average weight of the several finished slush molded skins;

[0122] If the average weight of the several finished product slush molded skins is greater than the preset weight, it is secondarily determined that the effectiveness of the coupling between the material box and the slush mold is below the allowable range, and the material box is controlled to move according to the running speed of the material box.

[0123] It can be understood that the two intervals corresponding to the preset weight Y0 correspond to two situations. The first interval is Y≤Y0, which corresponds to the situation where the effectiveness of the coupling between the material box and the slush mold is within the allowable range; the second interval is Y>Y0, which corresponds to the situation where the moving structure of the material box ages and cannot stop in time when reaching the target position of the material box, causing some PVC slush powder to leak out. In practice, Y0 is generally selected in the range of [0.3kg, 0.7kg].

[0124] Preferably, a preferred embodiment of the preset weight Y0 is Y0=0.5 kg.

[0125] Specifically, the average weight of several finished slush skins is recorded as Y.

[0126] In practice, the process of the present invention performs a secondary determination on the effectiveness of the coupling between the material box and the slush mold by setting a preset weight, thereby reducing the impact of the inaccurate secondary determination of the effectiveness of the coupling between the material box and the slush mold on the environmental friendliness of the preparation of the modified PVC material, and further achieving improved accuracy and environmental friendliness in the preparation of the modified PVC.

[0127] Specifically, the running speed of the material box is determined by the difference between the average weight of a number of finished slush-molded skins and a preset weight.

[0128] Specifically, the running speed of the material box is reduced by the difference between the average weight of several finished slush skins and the preset weight. The calculation formula of the running speed of the material box after the reduction is:

[0129]

[0130] Among them, L' is the running speed of the material box after reduction, L is the current running speed of the material box, C is the minimum unit weight for adjusting the running speed of the material box, and l is the running speed of the material box when the average weight of several finished plastic skins is the minimum unit weight.

[0131] In practice, the value of C is generally 0.5 kg to 0.7 kg. Preferably, the preferred embodiment of C is 0.6 kg.

[0132] In practice, the optional range of l is [3kg / min, 5kg / min]. When the running speed of the material box is greater than 4kg / min, some PVC slush powder may leak out. Therefore, the preferred embodiment of l is 4kg / min.

[0133] For example, the PVC material is prepared using the slush molding PVC skin preparation process based on modified PVC material, where L = 5kg / min, Y = 0.8kg, and the calculation is

[0134] In practice, the process of the present invention adjusts the running speed of the material box by setting a preset weight. Due to material aging of the moving structure of the material box, it is unable to stop in time when reaching the target position of the material box, resulting in deviation, which makes it impossible to couple tightly with the slush mold, causing some PVC slush powder to leak out, and reducing the weight of the finished slush skin. By reducing the moving speed of the material box, the accuracy of the movement of the material box is improved, so that the coupling is tighter, and the preparation accuracy and environmental protection of the modified PVC are further improved.

[0135] Specifically, the step of determining the second flipping speed of the slush mold includes:

[0136] The thickness of the finished product slush-molded surface in a single operation cycle is obtained, and the maximum thickness difference of the finished product slush-molded surface is calculated;

[0137] Comparing the maximum thickness difference of the finished product slush-molded skin with a preset difference;

[0138] If the maximum thickness difference of the finished product slush molded skin is greater than the preset difference, it is determined that the uniformity of the slush mold flipping is lower than the allowable range, and the slush mold is flipped at the second flipping speed.

[0139] It can be understood that the two intervals corresponding to the preset difference amount R0 correspond to two situations. The first interval is R≤R0, corresponding to the situation where the uniformity of the flipping of the slush mold is within the allowable range, and the second interval is R>R0, corresponding to the situation where the flipping speed is too slow, resulting in the thickness of the finished slush mold surface being wavy, resulting in a large thickness difference. In practice, R0 is generally selected in the range of [4mm, 6mm].

[0140] Preferably, a preferred embodiment of the preset difference amount R0 is R0=5 mm.

[0141] Specifically, the maximum thickness difference of the finished slush skin is recorded as R.

[0142] In practice, the process of the present invention determines the uniformity of the flipping of the slush mold by setting a preset difference amount, thereby reducing the impact of the reduced preparation accuracy of the modified PVC material due to inaccurate determination of the uniformity of the flipping of the slush mold, and further achieving improved preparation accuracy and environmental protection for the modified PVC.

[0143] Specifically, the second turning speed of the slush mold is determined by the difference between the maximum thickness difference of the finished slush molded skin and a preset difference.

[0144] Specifically, the first flipping speed of the slush mold is increased by the difference between the maximum thickness difference of the finished slush molded skin and the preset difference, and the calculation formula of the second flipping speed of the slush mold after the increase is:

[0145]

[0146] Wherein, H" is the second flipping speed of the slush mold, H' is the first flipping speed of the slush mold, D is the minimum unit difference for adjusting the first flipping speed of the slush mold, and h' is the first flipping speed of the slush mold when the maximum thickness difference of the finished slush skin is the minimum unit difference.

[0147] In practice, the value of D is generally 7 mm to 9 mm. Preferably, the preferred embodiment of D is 8 mm.

[0148] In practice, the optional range of h' is [13 rpm, 23 rpm]. When the first flipping speed of the slush mold is less than 18 rpm, it may cause excessive thickness difference. Therefore, the preferred embodiment of h' is 18 rpm.

[0149] For example, the PVC material is prepared using a slush molding PVC skin preparation process based on a modified PVC material, wherein H'=15 rpm, R=9 mm, RPM.

[0150] In implementation, the process of the present invention adjusts the first flipping speed of the slush mold by setting a preset difference amount. Since the flipping speed is too slow, the thickness of the finished slush molded surface is wavy, resulting in excessive thickness difference. By increasing the flipping speed, the roughness of the slush molded surface is reduced, further achieving the improvement of the preparation accuracy and environmental protection of the modified PVC.

[0151] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A process for preparing slush-molded PVC skin based on modified PVC material, characterized in that: The following steps are involved: The slush mold is heated, a material box containing PVC slush powder is conveyed to the bottom of the slush mold, and the material box and the slush mold are connected and coupled; The coupled material box and the slush mold are turned over several times, and the excess PVC slush powder falls into the material box, and then the material box and the slush mold are separated. The slush mold is cooled and then demoulded to output the finished slush skin; Determine the interval between the heating moment and the cooling moment based on the average roughness of the sampling area in the finished product slush molded skin, or obtain the number of defective products in a number of finished product slush molded skins and the total number of finished product slush molded skins respectively; Determining a first flipping speed of the slush mold based on the percentage of defective products in the finished slush skin, or determining a running speed of the material box based on the percentage of defective products in the finished slush skin and the average weight of a number of finished slush skins; Obtaining the thickness of the finished product skin of the slush mold output after running the slush mold for a single cycle at the first flipping speed; The second turning speed is determined based on the maximum thickness difference of the finished product slush molding skin; Wherein, the first flipping speed is smaller than the second flipping speed.

2. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 1, characterized in that: The components and weight proportions of the finished slush-molded skin are: 10 parts of PVC base material, 3 parts of plasticizer, 0.4 parts of stabilizer, 0.2 parts of colorant, 0.2 parts of desiccant, and 0.05 parts of internal release agent.

3. The process for preparing the slush-molded PVC skin based on modified PVC material according to claim 2, characterized in that: The step of determining the interval between the heating moment and the cooling moment also includes determining the preparation accuracy of the modified PVC material based on the average roughness of the sampling area in the finished slush molded surface; Wherein, if the average roughness of the sampling area in the finished product slush molding surface meets the first roughness condition or meets the second roughness condition, it is determined that the preparation accuracy of the modified PVC material is lower than the allowable range; When the average roughness of the sampling area in the surface of the finished slush mold meets the trigger condition for determining the interval between the heating moment and the cooling moment, the slush mold is heated and cooled according to the determined interval; Among them, the trigger condition is that the average roughness of the sampling area in the finished product plastic skin only meets the second roughness condition, and the interval between the heating moment and the cooling moment is determined by the difference between the average roughness of the sampling area in the finished product plastic skin and the preset second roughness.

4. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 3, characterized in that: The calculation formula for the average roughness of the sampling area in the finished product slush skin is: Among them, G is the average roughness of the sampling area in the finished plastic surface, K b is the roughness of the bth sampling area in the finished plastic surface, u is the number of sampling areas, and u is a natural number greater than or equal to 1.

5. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 4, characterized in that: The first roughness condition is that the average roughness of the sampling area in the finished product slush molding surface is greater than the preset first roughness and less than or equal to the preset second roughness; the second roughness condition is that the average roughness of the sampling area in the finished product slush molding surface is greater than the preset second roughness.

6. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 5, characterized in that: The step of determining the first flipping speed of the slush mold comprises: The number of defective products in several finished slush-molded skins and the total number of finished slush-molded skins in a single preparation cycle are obtained respectively, and the proportion of the number of defective products in the finished slush-molded skins is calculated; Compare the percentage of defective products in the finished product slush molded skin with the preset first percentage and the preset second percentage respectively; If the proportion of defective products in the finished product slush molding surface is greater than the preset first proportion and less than or equal to the preset second proportion, the slush molding mold is controlled to flip the slush molding mold at the first flipping speed.

7. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 6, characterized in that: The first turning speed of the slush mold is determined by the difference between the proportion of defective products in the surface of the finished slush molded product and a preset first proportion.

8. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 7, characterized in that: If the proportion of defective products in the finished product slush molding surface is greater than the preset second proportion, it is preliminarily determined that the effectiveness of the coupling between the material box and the slush molding mold is lower than the allowable range.

9. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 8, characterized in that: The step of determining the running speed of the feed box also includes secondarily determining the effectiveness of the coupling between the feed box and the slush mold based on the average weight of the plurality of finished slush molded skins, If the average weight of the several finished product slush molded skins is greater than the preset weight, it is determined that the effectiveness of the coupling between the material box and the slush mold is lower than the allowable range, and the material box is controlled to move according to the running speed of the material box; The running speed of the material box is determined by the difference between the average weight of a number of finished slush-molded skins and a preset weight.

10. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 9, characterized in that: The step of determining the second flipping speed of the slush mold comprises: The thickness of the finished product slush-molded surface in a single operation cycle is obtained, and the maximum thickness difference of the finished product slush-molded surface is calculated; Comparing the maximum thickness difference of the finished product slush-molded skin with a preset difference; If the maximum thickness difference of the finished product slush molded skin is greater than the preset difference, controlling the slush mold to flip the slush mold at the second flipping speed; The second flipping speed of the slush mold is determined by the difference between the maximum thickness difference of the finished slush molded skin and a preset difference.

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