A high impregnation continuous long glass fiber reinforced polypropylene material and preparation method thereof

Abstract

The present invention relates to the technical field of composite materials, and in particular to a high-impregnation continuous long glass fiber reinforced polypropylene material and a preparation method thereof, comprising: mixing and melting polypropylene resin and additives to plasticize; pulling glass fibers to a pre-dispersing roller device for dispersion and widening; judging the pore type between glass fibers according to the volume content of glass fibers, and adjusting the initial pulling speed; mixing and impregnating glass fibers and molten polypropylene resin in a long glass fiber impregnator; detecting the pore volume of the impregnated mixture, judging the impregnation degree and permeability of the molten resin in the glass fiber bundle, and judging the flow type of the molten resin; judging the reason for the poor permeability according to the flow type, and adjusting the impregnation parameters and screw speed; adjusting the initial pulling speed according to the production efficiency, and increasing the initial tension of the pre-dispersing roller. The present invention adjusts the impregnation parameters according to the pore type of the glass fiber bundle, and increases the impregnation degree of the polypropylene resin and the glass fiber bundle.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, and in particular to a high-impregnation continuous long glass fiber reinforced polypropylene material and a preparation method thereof. Background Art

[0002] With the advancement of technology and the continuous improvement of material performance requirements, continuous long fiber reinforced thermoplastic composites (LFRT) have gradually replaced short fiber reinforced materials due to their better reinforcement effect. It is of great significance to study the preparation and performance of LFRT. The key to affecting the performance of LFRT products is how to make the fibers better impregnated, that is, to improve the interface bonding between the resin matrix phase and the fiber reinforcement phase.

[0003] Chinese Patent Publication No.: CN103707435A discloses a melt infiltration device and infiltration method for the production of continuous long glass fiber reinforced polypropylene, including a shell, a reaction tank, a reaction tank glass fiber inlet at the front end, a reaction tank glass fiber outlet at the rear end, and a compatibilizer in the reaction tank; an infiltration tank, including a mold cavity, a resin introduction channel inlet, a glass fiber inlet, a glass fiber outlet, and a glass fiber dispersion infiltration roller, the resin introduction channel inlet, the glass fiber inlet, and the glass fiber outlet are respectively connected to the mold cavity, the glass fiber dispersion infiltration roller is placed in the mold cavity, and the mold cavity is filled with molten polypropylene resin. Compared with the prior art, the present invention can reduce the friction and breakage of glass fiber filaments; improve the infiltration speed, increase the production capacity, and reduce the processing cost; pre-treat the glass fiber with a compatibilizer to improve the bonding force and infiltration effect between the glass fiber and the resin, and finally greatly improve the product performance. It can be seen that the melt infiltration device and infiltration method for the production of continuous long glass fiber reinforced polypropylene have the following problems:

[0004] The pores between the individual glass fibers in the glass fiber bundle are small, and it is difficult for the molten resin to be impregnated into the glass fiber bundle. When the glass fiber bundles are fully impregnated, the glass fibers in the glass fiber bundle are not fully impregnated. Summary of the invention

[0005] To this end, the present invention provides a high-impregnation continuous long glass fiber reinforced polypropylene material and a preparation method thereof, so as to overcome the problem in the prior art that the pores between the single glass fibers in the glass fiber bundle are small, the molten resin is difficult to impregnate into the glass fiber bundle, and when the glass fiber bundles are fully impregnated, the glass fibers in the glass fiber bundle are not fully impregnated.

[0006] To achieve the above object, the present invention provides a method for preparing a high-impregnation continuous long glass fiber reinforced polypropylene material, comprising:

[0007] Step S1, mixing polypropylene resin and additives in a certain proportion and sending them into a screw extruder for melt plasticization;

[0008] Step S2, the traction device draws the glass fiber out of the automatic control untwisting device at an initial traction speed and sends it to the pre-dispersion roller device for dispersion and widening at an initial tension;

[0009] Step S3, judging the type of pores between glass fibers in the glass fiber bundle according to the volume content of the glass fibers in the glass fiber bundle, and adjusting the initial pulling speed;

[0010] Step S4, mixing and impregnating the pre-dispersed glass fibers and molten polypropylene resin in a long glass fiber impregnator;

[0011] Step S5, detecting the pore volume inside the impregnated mixed material, determining the degree of impregnation of the glass fiber bundle in the molten resin and the permeability of the molten resin, and determining the flow type of the molten resin according to the melt flow rate of the molten resin;

[0012] Step S6, judging the reason for the poor permeability of the molten resin according to the flow type of the molten resin, and adjusting the impregnation parameters of the impregnator and the screw speed of the screw extruder;

[0013] Step S7, adjusting the initial pulling speed according to the production efficiency to increase the initial tension of the pre-dispersing roller on the glass fiber bundle;

[0014] Step S8, the impregnated mixture is extruded from the long glass fiber impregnator, cooled by a cooling device and pulled by a pulling device, processed and formed by a blow dryer, and then enters a pelletizer to be cut into pellets.

[0015] Further, the volume content of the glass fibers in the glass fiber bundle is calculated according to the diameter of the glass fiber bundle, the glass fiber diameter of the glass fibers, and the number of glass fibers in the glass fiber bundle.

[0016] If the volume content is less than the critical content, it is judged that the pores between the glass fibers in the glass fiber bundle are in the first pore category;

[0017] If the volume content is greater than or equal to the critical content, it is determined that the pores between the glass fibers in the glass fiber bundle are in the second pore category, and the molten resin is difficult to impregnate into the glass fiber bundle, thereby increasing the impregnation time of the glass fiber bundle in the molten resin.

[0018] Further, the process of increasing the immersion time of the glass fiber bundle in the molten resin includes:

[0019] Detect the initial pulling speed of the glass fiber bundle, and calculate the initial impregnation time of the glass fiber bundle in the molten resin according to the initial pulling speed and the length of the impregnation chamber in the impregnation machine.

[0020] When the pores between the glass fibers are in the second pore category, the initial pulling speed is reduced according to the ratio of the critical content to the volume content, and the actual immersion time after reducing the initial pulling speed is calculated.

[0021] Further, the process of determining the degree of impregnation of the glass fiber bundle in the molten resin includes:

[0022] After reducing the initial pulling speed, the pores inside the impregnated mixture are detected and the actual permeability of the molten resin inside the glass fiber bundle is calculated.

[0023] If the actual permeability is greater than or equal to the standard permeability, it is judged that the impregnation degree of the mixed material meets the standard, the actual permeability of the molten resin in the impregnator meets the production requirements, and the mixed material is in the first production category;

[0024] If the actual permeability is less than the standard permeability, it is judged that the impregnation degree of the mixed material does not meet the standard, the permeability of the molten resin in the impregnation machine is poor, and the mixed material is in the second production category.

[0025] Further, when the mixed material is in the second production category, the melt flow rate of the molten resin extruded from the screw extruder is detected.

[0026] If the melt flow rate is greater than or equal to the standard flow rate, the fluidity of the extruded molten resin is judged to be in the first flow category;

[0027] If the melt flow rate is less than the standard flow rate, the fluidity of the extruded molten resin is judged to be in the second flow category.

[0028] Further, when the molten resin is in the first flow category, it is determined that the molten resin meets the preparation requirements, and the reason for the poor permeability is that the impregnation parameters inside the impregnation machine are poor, and the impregnation temperature in the impregnation chamber is increased;

[0029] When the molten resin is in the second flow category, it is determined that the molten resin does not meet the preparation requirements. The reason for the poor permeability is that the fluidity of the molten resin is low. Adjust the ratio of the molten resin, add a compatibilizer, or increase the screw speed of the screw extruder.

[0030] Further, the process of increasing the impregnation temperature in the impregnation chamber includes,

[0031] Detecting the impregnation temperature in the impregnation mold, drawing a curve of permeability changing with the impregnation temperature according to the change of the impregnation temperature, calculating the increasing trend of the permeability changing with the increasing of the impregnation temperature in the permeability changing curve, and calculating the predicted impregnation temperature corresponding to the standard permeability in the permeability changing curve according to the increasing trend;

[0032] If the predicted immersion temperature is less than or equal to the critical immersion temperature, it is determined that the predicted immersion temperature is within the temperature range, and heating is stopped when the immersion temperature in the immersion chamber increases to the predicted immersion temperature;

[0033] If the predicted immersion temperature is greater than the critical immersion temperature, it is determined that the predicted immersion temperature exceeds the temperature range, and when the immersion temperature in the immersion chamber increases to the critical immersion temperature, heating is stopped and the immersion pressure in the immersion chamber is increased;

[0034] The temperature interval is a preset interval set according to the material properties of the thermoplastic polypropylene resin that vary with temperature, and the critical immersion temperature is the maximum value of the temperature interval.

[0035] Further, the process of increasing the impregnation pressure in the impregnation chamber includes:

[0036] The impregnation pressure in the impregnation chamber is increased by increasing the melt pressure of the molten resin in the impregnation machine where the glass fiber bundle is located, and the impregnation pressure in the impregnation chamber and the porosity in the impregnated mixed material are continuously collected according to the initial detection period;

[0037] The actual decrease and historical decrease of porosity are calculated based on the actual porosity of the current detection cycle and the historical porosity of the adjacent initial detection cycle.

[0038] If the difference between the actual decline and the historical decline is less than the difference evaluation value, it is judged that the decline of the porosity with the increase of the immersion pressure in the current detection period is moderate, and the immersion pressure in the immersion chamber continues to be increased;

[0039] If the difference between the actual decrease amplitude and the historical decrease amplitude is greater than or equal to the amplitude difference evaluation value, it is judged that the decrease amplitude of the porosity with the increase of the immersion pressure in the current detection cycle is small, and the increase of the immersion pressure in the immersion cavity is stopped, and the immersion pressure corresponding to the actual porosity of the current detection cycle is marked as the pressure characteristic point.

[0040] Furthermore, when the mixed material is in the first production category, the production efficiency is calculated according to the actual number of pellets produced per unit time, and the production efficiency is equal to the ratio of the actual number of pellets produced per unit time to the unit time, and the demand efficiency is the ratio of the preset demand number of pellets to the unit time;

[0041] If the production efficiency is greater than or equal to the demand efficiency, it is determined that the production efficiency after reducing the initial traction speed meets the demand;

[0042] If the production efficiency is less than the required efficiency, it is determined that the production efficiency after reducing the initial traction speed does not meet the demand.

[0043] Furthermore, when the production efficiency after reducing the initial traction speed does not meet the demand, the difference between the initial immersion time and the actual immersion time is calculated.

[0044] If the time difference between the initial immersion time and the actual immersion time is less than the time difference evaluation value, the initial traction speed is increased according to the ratio of the time difference evaluation value to the time difference;

[0045] If the time difference between the initial impregnation time and the actual impregnation time is greater than the time difference evaluation value, the initial traction speed is increased according to the ratio of the demand efficiency to the production efficiency, and the initial tension of the pre-dispersing roller on the glass fiber bundle is increased;

[0046] The time difference evaluation value is 2.5% of the initial immersion time.

[0047] A high impregnation continuous long glass fiber reinforced polypropylene material, characterized in that:

[0048] The high-impregnation continuous long glass fiber reinforced polypropylene material is prepared by mixing polypropylene resin and auxiliary agents to form a molten resin, wherein the auxiliary agents include flame retardants and fillers.

[0049] Compared with the prior art, the beneficial effect of the present invention is that, generally speaking, the more glass fibers there are in a glass fiber bundle, the larger the diameter and volume of the glass fibers, the smaller the glass fiber pores between the glass fibers inside the glass fiber bundle, the more difficult it is for the polypropylene resin to be impregnated into the interior of the glass fiber bundle, and the longer the time required for the polypropylene resin to be completely impregnated into the interior of the glass fiber bundle. The present invention determines the type of pores between the glass fibers in the glass fiber bundle according to the volume content of the glass fibers in the glass fiber bundle, and adjusts the impregnation time of the glass fiber bundle in the molten resin before the glass fiber bundle enters the impregnation machine for impregnation with the molten polypropylene resin, thereby reducing the impact of insufficient impregnation time on production efficiency and ensuring that the production process of the polypropylene material is more flexible and efficient.

[0050] Furthermore, the residence time of the glass fiber in the impregnator is determined by the pulling speed of the pulling glass fiber bundle. The longer the impregnation time of the glass fiber in the long glass fiber impregnator head is, the closer it is to the time required to completely impregnate the fiber bundle. Therefore, when the pulling speed is low, the glass fiber is impregnated for a longer time, and the molten resin is more fully impregnated, which helps to form a uniform fiber / resin interface, improves the interface bonding strength between the molten resin and the glass fiber, and improves the mechanical properties and durability of the composite material.

[0051] Furthermore, in the preparation process of long glass fiber reinforced polypropylene material, the impregnation parameters of the impregnator and the fluidity of the polypropylene resin are the determining factors of the impregnation process of the resin and the glass fiber. The present invention calculates the permeability of the molten resin in the glass fiber bundle by detecting the pores inside the impregnated mixture, judges whether the impregnation degree of the mixture meets the standard, and judges the reason for the poor permeability of the molten resin according to the impregnation degree, and takes corresponding measures. When the fluidity of the molten resin is low, adding a compatibilizer to increase the PP-g-MAH content can increase the interface bonding ability between the resin matrix and the glass fiber; increasing the screw speed can enhance the shearing effect between the polypropylene resin and the additives between the screw and the barrel, increase the mixing effect of the polypropylene resin and the additives, reduce the resin viscosity from the source, increase the fluidity of the molten resin, and improve the accuracy of adjusting the production and preparation process.

[0052] Furthermore, the temperature of the impregnation chamber inside the impregnation machine cannot be too high. Too high a temperature will cause the thermoplastic resin to undergo thermal oxidation degradation, and the surface of the obtained product will turn yellow. Therefore, the temperature of the impregnation chamber should not be too high, and a suitable temperature range needs to be selected. The present invention predicts the impregnation temperature required when the mixed material reaches the standard permeability by judging the increasing trend of the permeability as the impregnation temperature rises, and adopts different adjustment measures according to the relationship between the impregnation temperature and the temperature range, thereby avoiding the adverse effects of excessive temperature on the preparation process and further improving the accuracy of adjustment for the production preparation process.

[0053] Furthermore, the effect of pressure on the fiber impregnation efficiency is very significant. The higher the surrounding melt pressure, the shorter the time required to completely impregnate the fiber. However, after the pressure is higher than a certain value, the reduction in impregnation time is not significant. For an actual impregnation head, it is usually difficult to obtain a high melt pressure. Therefore, the impregnation efficiency can be improved by appropriately increasing the pressure. The present invention increases the impregnation pressure by increasing the molten resin pressure, determines the pressure characteristic point where the effect of the impregnation pressure on the fiber impregnation efficiency becomes smaller according to the decrease in the porosity in the mixed material, improves the permeability of the molten resin in the glass fiber bundle, and minimizes unnecessary losses in the preparation process to the greatest extent, reduces the cost of production and preparation, and further improves the accuracy of adjusting the preparation process.

[0054] Furthermore, too low a pulling speed will lead to a decrease in production efficiency, which is not conducive to industrial production, so it is necessary to adopt a suitable pulling speed, which is conducive to the impregnation of glass fiber and can improve production efficiency. The present invention determines the degree of adjusting the pulling speed according to the production efficiency, and adjusts the pulling force of the glass fiber bundle to increase the fiber widening when the pulling speed is too slow, increases the glass fiber diameter and is not easy to deform, maintains the porosity, is conducive to resin impregnation, reduces the porosity inside the glass fiber bundle, improves the dispersion / fluffiness of the glass fiber bundle, and reduces the influence of adjusting the pulling speed on the production efficiency and the impregnation degree of the mixed material. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic flow chart of a method for preparing a high-impregnation continuous long glass fiber reinforced polypropylene material according to an embodiment of the present invention;

[0056] Figure 2 This is a schematic diagram of a preparation process of a high-impregnation continuous long glass fiber reinforced polypropylene material according to an embodiment of the present invention;

[0057] Figure 3 This is a schematic diagram of the cross-sectional structure of the mixed material in an embodiment of the present invention;

[0058] Figure 4 It is a schematic diagram of a process for determining the production category of a mixed material according to permeability in an embodiment of the present invention;

[0059] In the figure: 1-glass fiber bundle, 2-pre-dispersion roller device, 3-long glass fiber impregnation machine, 4-screw extruder, 5-cooling device, 6-traction device, 7-mixing material, 8-pelletizer, 9-pellet, 10-molten resin, 11-glass fiber, 12-glass fiber pores. DETAILED DESCRIPTION

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] See also Figure 1-Figure 4 As shown, Figure 1 It is a schematic flow chart of a method for preparing a high-impregnation continuous long glass fiber reinforced polypropylene material according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a preparation process of a high-impregnation continuous long glass fiber reinforced polypropylene material according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the cross-sectional structure of the mixed material in an embodiment of the present invention; Figure 4 It is a schematic diagram of a process for determining the production category of a mixed material according to permeability in an embodiment of the present invention.

[0065] The present invention provides a high-impregnation continuous long glass fiber reinforced polypropylene material and a preparation method thereof, comprising:

[0066] Step S1, mixing polypropylene resin and additives in a certain proportion and sending them into a screw extruder 4 for melting and plasticization;

[0067] Step S2, the traction device 6 draws the glass fiber 11 out of the automatic control untwisting device at an initial traction speed and sends it to the pre-dispersion roller device 2 for dispersion and widening with an initial tension;

[0068] Step S3, judging the type of pores between glass fibers in the glass fiber bundle 1 according to the volume content of the glass fibers 11 in the glass fiber bundle 1, and adjusting the initial pulling speed;

[0069] Step S4, the pre-dispersed glass fibers 11 are mixed and impregnated with molten polypropylene resin in a long glass fiber impregnator 3;

[0070] Step S5, detecting the pore volume inside the impregnated mixed material 7, determining the degree of impregnation of the glass fiber bundle 1 in the molten resin 10 and the permeability of the molten resin 10, and determining the flow type of the molten resin 10 according to the melt flow rate of the molten resin 10;

[0071] Step S6, judging the reason why the permeability of the molten resin 10 is poor according to the flow type of the molten resin 10, and adjusting the impregnation parameters of the impregnator and the screw speed of the screw extruder 4;

[0072] Step S7, adjusting the initial pulling speed according to the production efficiency, and increasing the initial tension of the pre-dispersing roller on the glass fiber bundle 1;

[0073] Step S8, the impregnated mixed material 7 is extruded from the long glass fiber impregnator 3, cooled by the cooling device 5 and pulled by the pulling device 6, processed and formed by the blow dryer, and then enters the pelletizer 8 to be cut into pellets 9.

[0074] In this embodiment, the pre-dispersing roller device 2 adjusts the fiber width of the glass fiber bundle 1 by the height of the device and its own covering angle.

[0075] The volume content of the glass fiber 11 in the glass fiber bundle 1 is calculated according to the diameter of the glass fiber bundle 1, the glass fiber diameter of the glass fiber 11, and the number of the glass fibers 11 in the glass fiber bundle 1.

[0076] If the volume content is less than the critical content, it is determined that the pores between the glass fibers in the glass fiber bundle 1 are in the first pore category;

[0077] If the volume content is greater than or equal to the critical content, it is determined that the pores between the glass fibers in the glass fiber bundle 1 are in the second pore category, and the molten resin 10 is difficult to impregnate into the glass fiber bundle 1, thereby increasing the impregnation time of the glass fiber bundle 1 in the molten resin 10.

[0078] In practice, the critical content is 70%.

[0079] Specifically, when the fiber content is below 60%, the resin matrix can complete the process of impregnating the fibers in a shorter time. However, when the fiber volume content exceeds 70%, the time required for the polypropylene melt to impregnate the fibers increases dramatically. In particular, when the fiber content reaches more than 80%, the time required for complete melt impregnation will exceed 3 minutes, and it is usually difficult to achieve a continuous extrusion impregnation process.

[0080] Specifically, generally speaking, the more glass fibers there are in the glass fiber bundle 1, the larger the glass fiber diameter and the larger the volume, the smaller the glass fiber pores 12 between the glass fibers inside the glass fiber bundle 1, the more difficult it is for the polypropylene resin to be impregnated into the glass fiber bundle 1, and the longer the time required for the polypropylene resin to be completely impregnated into the glass fiber bundle 1. The present invention determines the type of pores between the glass fibers in the glass fiber bundle 1 according to the volume content of the glass fibers 11 in the glass fiber bundle 1, and adjusts the impregnation time of the glass fiber bundle 1 in the molten resin 10 before the glass fiber bundle 1 enters the impregnation machine for impregnation with the molten polypropylene resin, thereby reducing the impact of insufficient impregnation time on production efficiency and ensuring that the production process of the polypropylene material is more flexible and efficient.

[0081] The initial pulling speed of the glass fiber bundle 1 is detected, and the initial impregnation time of the glass fiber bundle 1 in the molten resin 10 is calculated according to the initial pulling speed and the length of the impregnation chamber in the impregnator.

[0082] When the pores between the glass fibers are in the second pore category, the initial impregnation time of the glass fiber bundle 1 in the impregnator is increased, the initial traction speed is reduced according to the ratio of the critical content to the volume content, and the actual impregnation time after reducing the initial traction speed is calculated.

[0083] Specifically, the residence time of the glass fiber in the impregnator is determined by the pulling speed of the glass fiber bundle 1. The longer the impregnation time of the glass fiber in the long glass fiber impregnator 3 is, the closer it is to the time required for complete impregnation of the fiber bundle. Therefore, when the pulling speed is low, the glass fiber is impregnated for a longer time, and the molten resin 10 is more fully impregnated, which helps to form a uniform fiber / resin interface, improves the interface bonding strength between the molten resin 10 and the glass fiber 11, and improves the mechanical properties and durability of the composite material.

[0084] After reducing the initial pulling speed and increasing the impregnation time, a scanning electron microscope or an ultrasonic detector is used to detect the pore volume inside the impregnated mixed material 7 to determine the degree of impregnation of the glass fiber bundle 1 in the molten resin 10;

[0085] The pore volume per unit length of the mixed material 7 after impregnation in the impregnator is detected. The larger the pore volume, the lower the impregnation degree and the lower the permeability. The actual permeability of the molten resin 10 inside the glass fiber bundle 1 is calculated.

[0086] In implementation, the actual permeability is calculated based on the ratio of the difference between the volume of the mixed material 7 per unit length and the pore volume to the volume of the mixed material 7 per unit length;

[0087] If the actual permeability is greater than or equal to the standard permeability, it is judged that the impregnation degree of the mixed material 7 meets the standard, the actual permeability of the molten resin 10 in the impregnator meets the production requirements, and the mixed material 7 is in the first production category;

[0088] If the actual permeability is less than the standard permeability, it is determined that the impregnation degree of the mixed material 7 does not meet the standard, the permeability of the molten resin 10 in the impregnator is poor, and the mixed material 7 is in the second production category.

[0089] When the mixed material 7 is in the second production category, the melt flow rate of the molten resin 10 extruded from the screw extruder is detected.

[0090] If the melt flow rate is greater than or equal to the standard flow rate, the fluidity of the extruded molten resin 10 is judged to be in the first flow category;

[0091] If the melt flow rate is less than the standard flow rate, the fluidity of the extruded molten resin 10 is judged to be in the second flow category;

[0092] The standard flow velocity and the standard permeability are preset values ​​set according to historical data of the mixed material 7 that has passed the qualification test.

[0093] When the molten resin 10 is in the first flow category, it is determined that the molten resin 10 meets the preparation requirements, and the reason for the poor permeability is that the impregnation parameters inside the impregnation machine are poor, and the impregnation temperature in the impregnation chamber is increased;

[0094] When the molten resin 10 is in the second flow category, it is determined that the molten resin 10 does not meet the preparation requirements. The reason for the poor permeability is that the fluidity of the molten resin 10 is low. The proportion of the molten resin 10 is adjusted, a compatibilizer is added, or the screw speed of the screw extruder 4 is increased.

[0095] Specifically, in the preparation process of long glass fiber reinforced polypropylene material, the impregnation parameters of the impregnator and the fluidity of the polypropylene resin are the determining factors of the impregnation process of the resin and the glass fiber. The present invention calculates the permeability of the molten resin 10 in the glass fiber bundle 1 by detecting the pores inside the impregnated mixed material 7, judges whether the impregnation degree of the mixed material 7 meets the standard, and judges the reason for the poor permeability of the molten resin 10 according to the impregnation degree, and takes corresponding measures. When the fluidity of the molten resin 10 is low, adding a compatibilizer to increase the PP-g-MAH content can increase the interface bonding ability between the resin matrix and the glass fiber 11; increasing the screw speed can enhance the shearing effect between the polypropylene resin and the additives between the screw and the barrel, increase the mixing effect of the polypropylene resin and the additives, reduce the resin viscosity from the source, increase the fluidity of the molten resin 10, and improve the accuracy of adjusting the production preparation process.

[0096] When the impregnation temperature in the impregnation cavity is increased, the impregnation temperature in the impregnation mold is detected.

[0097] A permeability change curve is drawn according to the change of the immersion temperature, an increasing trend of the permeability in the permeability change curve as the immersion temperature increases is calculated, and a predicted immersion temperature corresponding to the standard permeability in the permeability change curve is calculated according to the increasing trend;

[0098] If the predicted immersion temperature is less than or equal to the critical immersion temperature, it is determined that the predicted immersion temperature is within the temperature range, and heating is stopped when the immersion temperature in the immersion chamber increases to the predicted immersion temperature;

[0099] If the predicted immersion temperature is greater than the critical immersion temperature, it is determined that the predicted immersion temperature exceeds the temperature range, and when the immersion temperature in the immersion chamber increases to the critical immersion temperature, heating is stopped and the immersion pressure in the immersion chamber is increased;

[0100] In practice, the impregnation pressure in the impregnation chamber is increased by increasing the melt pressure of the molten resin 10 in the impregnation machine where the glass fiber bundle 1 is located.

[0101] The temperature interval is a preset interval set according to the material properties of the thermoplastic polypropylene resin that vary with temperature, and the critical immersion temperature is the maximum value of the temperature interval.

[0102] Specifically, the temperature of the impregnation chamber inside the impregnation machine cannot be too high. Too high a temperature will cause the thermoplastic resin to undergo thermal oxidation degradation, and the surface of the obtained product will turn yellow. Therefore, the temperature of the impregnation chamber should not be too high, and a suitable temperature range needs to be selected. The present invention predicts the impregnation temperature required when the mixed material 7 reaches the standard permeability by judging the increasing trend of the permeability as the impregnation temperature rises, and adopts different adjustment measures according to the relationship between the impregnation temperature and the temperature range, thereby avoiding the adverse effects of excessive temperature on the preparation process and further improving the accuracy of adjustment of the production preparation process.

[0103] When the impregnation pressure in the impregnation chamber is increased, the pressure characteristic point is determined.

[0104] Continue to increase the melt pressure of the molten resin 10 in the impregnation machine where the glass fiber bundle 1 is located, continuously collect the impregnation pressure in the impregnation chamber according to the initial detection cycle, use an ultrasonic detector to detect the porosity of the mixed material 7 after impregnation, calculate the actual decrease in porosity based on the actual porosity of the current detection cycle and the historical porosity of the adjacent historical detection cycle, and calculate the historical decrease based on the historical porosity and the historical porosity of the previous historical detection cycle.

[0105] In implementation, the actual decline is the ratio of the absolute value of the actual porosity minus the historical porosity to the initial detection period, and the historical decline is the ratio of the absolute value of the historical porosity minus the historical porosity of the previous historical detection period to the initial detection period.

[0106] If the difference between the actual decline and the historical decline is less than the difference evaluation value, it is judged that the decline of the porosity with the increase of the immersion pressure in the current detection period is moderate, and the immersion pressure in the immersion chamber continues to be increased;

[0107] If the difference between the actual decrease amplitude and the historical decrease amplitude is greater than or equal to the amplitude difference evaluation value, it is judged that the decrease amplitude of the porosity with the increase of the immersion pressure in the current detection cycle is small, and the increase of the immersion pressure in the immersion cavity is stopped, and the immersion pressure corresponding to the actual porosity of the current detection cycle is marked as the pressure characteristic point.

[0108] In this embodiment, the immersion pressure corresponding to the pressure characteristic point is 2 bar.

[0109] Specifically, the effect of pressure on the fiber impregnation efficiency is very significant. The higher the surrounding melt pressure, the shorter the time required to completely impregnate the fiber. However, after the pressure is higher than a certain value, the reduction in impregnation time is not significant. For an actual impregnation head, it is usually difficult to obtain a high melt pressure. Therefore, the impregnation efficiency can be improved by appropriately increasing the pressure. The present invention increases the impregnation pressure by increasing the molten resin pressure, determines the pressure characteristic point where the effect of the impregnation pressure on the fiber impregnation efficiency becomes smaller according to the decrease in the porosity in the mixed material 7, improves the permeability of the molten resin 10 in the glass fiber bundle, and minimizes unnecessary losses in the preparation process to the greatest extent, reduces the cost of production and preparation, and further improves the accuracy of the adjustment preparation process.

[0110] When the mixed material 7 is in the first production category, the production efficiency is calculated according to the actual number of pellets 9 produced per unit time, and the production efficiency is equal to the ratio of the actual number of pellets produced per unit time to the unit time, and the demand efficiency is the ratio of the preset demand number of pellets to the unit time;

[0111] If the production efficiency is greater than or equal to the demand efficiency, it is determined that the production efficiency after reducing the initial traction speed meets the demand;

[0112] If the production efficiency is less than the required efficiency, it is judged that the production efficiency after reducing the initial traction speed does not meet the demand, the dipping time is too long and the traction speed is too slow;

[0113] When the production efficiency after reducing the initial traction speed does not meet the demand, calculate the difference between the initial immersion time and the actual immersion time.

[0114] If the time difference between the initial immersion time and the actual immersion time is less than the time difference evaluation value, the initial traction speed is increased according to the ratio of the time difference evaluation value to the time difference;

[0115] If the time difference between the initial immersion time and the actual immersion time is greater than the time difference evaluation value, the initial traction speed is increased according to the ratio of the demand efficiency to the production efficiency, and the initial tension of the pre-dispersing roller on the glass fiber bundle 1 is increased.

[0116] The time difference evaluation value is 2.5% of the initial immersion time.

[0117] Specifically, too low a pulling speed will lead to a decrease in production efficiency, which is not conducive to industrial production, so it is necessary to adopt a suitable pulling speed, which is conducive to the impregnation of glass fiber and can improve production efficiency. The present invention determines the degree of adjusting the pulling speed according to the production efficiency, and adjusts the pulling force of the glass fiber bundle 1 to increase the fiber widening when the pulling speed is too slow, increases the glass fiber diameter and is not easy to deform, maintains the porosity, is conducive to resin impregnation, reduces the porosity inside the glass fiber bundle 1, improves the dispersion / fluffiness of the glass fiber bundle 1, and reduces the influence of adjusting the pulling speed on the production efficiency and the impregnation degree of the mixed material 7.

[0118] When the glass fiber leaves the factory, it is gathered into a bundle due to the limitation of process and packaging. In this embodiment, the glass fiber used is 362K glass fiber of Jushi Group, with a linear density of 2400TEX, a width of a single fiber bundle of 5mm, and the number of single filaments in a fiber bundle is calculated to be 4400, so the fiber bundle is effectively dispersed, the interface bonding area between the resin matrix and the fiber is increased, and the time of completely impregnating the fiber bundle is reduced, which has a great influence on the interface bonding between the two phases.

[0119] A high impregnation continuous long glass fiber reinforced polypropylene material, characterized in that:

[0120] The high impregnation continuous long glass fiber reinforced polypropylene material is prepared by mixing polypropylene resin and additives to form a molten resin 10, wherein the additives include flame retardants and fillers.

[0121] 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.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a high impregnation continuous long glass fiber reinforced polypropylene material, characterized in that: include: Step S1, mixing polypropylene resin and additives in a certain proportion and sending them into a screw extruder for melt plasticization; Step S2, the traction device draws the glass fiber out of the automatic control untwisting device at an initial traction speed and sends it to the pre-dispersion roller device for dispersion and widening at an initial tension; Step S3, judging the type of pores between glass fibers in the glass fiber bundle according to the volume content of the glass fibers in the glass fiber bundle, and adjusting the initial pulling speed; Step S4, mixing and impregnating the pre-dispersed glass fibers and molten polypropylene resin in a long glass fiber impregnator; Step S5, detecting the pore volume inside the impregnated mixed material, determining the degree of impregnation of the glass fiber bundle in the molten resin and the permeability of the molten resin, and determining the flow type of the molten resin according to the melt flow rate of the molten resin; Step S6, judging the reason for the poor permeability of the molten resin according to the flow type of the molten resin, and adjusting the impregnation parameters of the impregnator and the screw speed of the screw extruder; Step S7, adjusting the initial pulling speed according to the production efficiency to increase the initial tension of the pre-dispersing roller on the glass fiber bundle; Step S8, the impregnated mixture is extruded from the long glass fiber impregnator, cooled by a cooling device and pulled by a pulling device, processed and formed by a blow dryer, and then enters a pelletizer to be cut into pellets.

2. The method for preparing a high impregnation continuous long glass fiber reinforced polypropylene material according to claim 1, characterized in that: The volume content of glass fiber in the glass fiber bundle is calculated according to the diameter of the glass fiber bundle, the glass fiber diameter of the glass fiber and the number of glass fibers in the glass fiber bundle. If the volume content is less than the critical content, it is judged that the pores between the glass fibers in the glass fiber bundle are in the first pore category; If the volume content is greater than or equal to the critical content, it is judged that the pores between the glass fibers in the glass fiber bundle are in the second pore category, and the molten resin is difficult to impregnate into the glass fiber bundle, thereby increasing the impregnation time of the glass fiber bundle in the molten resin.

3. The method for preparing a high impregnation continuous long glass fiber reinforced polypropylene material according to claim 2, characterized in that: The process of increasing the immersion time of the glass fiber bundle in the molten resin includes, Detect the initial pulling speed of the glass fiber bundle, and calculate the initial impregnation time of the glass fiber bundle in the molten resin according to the initial pulling speed and the length of the impregnation chamber in the impregnation machine. When the pores between the glass fibers are in the second pore category, the initial pulling speed is reduced according to the ratio of the critical content to the volume content, the actual impregnation time after the initial pulling speed is reduced is calculated, and the degree of impregnation of the glass fiber bundle in the molten resin after increasing the impregnation time is determined.

4. The method for preparing a high impregnation continuous long glass fiber reinforced polypropylene material according to claim 3, characterized in that: The process of determining the degree of impregnation of the glass fiber bundle in the molten resin after increasing the impregnation time includes: After reducing the initial pulling speed, the pores inside the impregnated mixture are detected and the actual permeability of the molten resin inside the glass fiber bundle is calculated. If the actual permeability is greater than or equal to the standard permeability, it is judged that the impregnation degree of the mixed material meets the standard, the actual permeability of the molten resin in the impregnator meets the production requirements, and the mixed material is in the first production category; If the actual permeability is less than the standard permeability, it is judged that the impregnation degree of the mixed material does not meet the standard, the permeability of the molten resin in the impregnation machine is poor, and the mixed material is in the second production category.

5. The method for preparing a high impregnation continuous long glass fiber reinforced polypropylene material according to claim 4, characterized in that: When the mixed material is in the second production category, the melt flow rate of the molten resin extruded from the screw extruder is detected. If the melt flow rate is greater than or equal to the standard flow rate, the fluidity of the extruded molten resin is judged to be in the first flow category; If the melt flow rate is less than the standard flow rate, the fluidity of the extruded molten resin is judged to be in the second flow category.

6. The method for preparing a high impregnation continuous long glass fiber reinforced polypropylene material according to claim 5, characterized in that: When the molten resin is in the first flow category, it is judged that the molten resin meets the preparation requirements. The reason for the poor permeability is that the impregnation parameters inside the impregnation machine are poor, and the impregnation temperature in the impregnation chamber is increased; When the molten resin is in the second flow category, it is determined that the molten resin does not meet the preparation requirements. The reason for the poor permeability is that the fluidity of the molten resin is low. Adjust the ratio of the molten resin, add a compatibilizer, or increase the screw speed of the screw extruder.

7. The method for preparing a high impregnation continuous long glass fiber reinforced polypropylene material according to claim 6, characterized in that: The process of increasing the impregnation temperature in the impregnation chamber includes, Detecting the impregnation temperature in the impregnation mold, drawing a curve of permeability changing with the impregnation temperature according to the change of the impregnation temperature, calculating the increasing trend of the permeability changing with the increasing of the impregnation temperature in the permeability changing curve, and calculating the predicted impregnation temperature corresponding to the standard permeability in the permeability changing curve according to the increasing trend; If the predicted immersion temperature is less than or equal to the critical immersion temperature, it is determined that the predicted immersion temperature is within the temperature range, and heating is stopped when the immersion temperature in the immersion chamber increases to the predicted immersion temperature; If the predicted immersion temperature is greater than the critical immersion temperature, it is determined that the predicted immersion temperature exceeds the temperature range, and when the immersion temperature in the immersion chamber increases to the critical immersion temperature, heating is stopped and the immersion pressure in the immersion chamber is increased; The temperature interval is a preset interval set according to the material properties of the thermoplastic polypropylene resin that vary with temperature, and the critical immersion temperature is the maximum value of the temperature interval.

8. The method for preparing a high impregnation continuous long glass fiber reinforced polypropylene material according to claim 7, characterized in that: The process of increasing the impregnation pressure in the impregnation chamber includes, The impregnation pressure in the impregnation chamber is increased by increasing the melt pressure of the molten resin in the impregnation machine where the glass fiber bundle is located, and the impregnation pressure in the impregnation chamber and the porosity in the impregnated mixed material are continuously collected according to the initial detection period; The actual decrease and historical decrease of porosity are calculated based on the actual porosity of the current detection cycle and the historical porosity of the adjacent initial detection cycle. If the difference between the actual decline and the historical decline is less than the difference evaluation value, it is judged that the decline of the porosity with the increase of the immersion pressure in the current detection period is moderate, and the immersion pressure in the immersion chamber continues to be increased; If the difference between the actual decrease amplitude and the historical decrease amplitude is greater than or equal to the amplitude difference evaluation value, it is judged that the decrease amplitude of the porosity with the increase of the immersion pressure in the current detection cycle is small, and the increase of the immersion pressure in the immersion cavity is stopped, and the immersion pressure corresponding to the actual porosity of the current detection cycle is marked as the pressure characteristic point.

9. The method for preparing a high impregnation continuous long glass fiber reinforced polypropylene material according to claim 4, characterized in that: When the mixed material is in the first production category, the production efficiency is calculated based on the actual number of pellets produced per unit time, where the production efficiency is equal to the ratio of the actual number of pellets produced per unit time to the unit time, and the demand efficiency is the ratio of the preset demand number of pellets to the unit time; If the production efficiency is greater than or equal to the demand efficiency, it is determined that the production efficiency after reducing the initial traction speed meets the demand; If the production efficiency is less than the required efficiency, it is judged that the production efficiency after reducing the initial traction speed does not meet the demand; When the production efficiency after reducing the initial traction speed does not meet the demand, calculate the difference between the initial immersion time and the actual immersion time. If the time difference between the initial immersion time and the actual immersion time is less than the time difference evaluation value, the initial traction speed is increased according to the ratio of the time difference evaluation value to the time difference; If the time difference between the initial impregnation time and the actual impregnation time is greater than the time difference evaluation value, the initial traction speed is increased according to the ratio of the demand efficiency to the production efficiency, and the initial tension of the pre-dispersing roller on the glass fiber bundle is increased; The time difference evaluation value is 2.5% of the initial immersion time.

10. A high impregnation continuous long glass fiber reinforced polypropylene material, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 9, The high-impregnation continuous long glass fiber reinforced polypropylene material is prepared by mixing polypropylene resin and auxiliary agents to form a molten resin, wherein the auxiliary agents include flame retardants and fillers.

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