Process for the production of continuous fiber reinforced polypropylene round solid rods

Abstract

This invention provides a method for preparing continuous fiber reinforced polypropylene circular solid rods. The method involves directly pultruding prepreg sheets to obtain circular solid rods. A preheating device is added to ensure adequate venting and enhance interfacial bonding, resulting in solid rods with good impregnation effect and high strength, while also improving production efficiency. First, the required fiber content of the rods is determined, and prepreg sheets with consistent fiber content are selected. Based on the rod diameter, the width and thickness of the prepreg sheet are calculated. The relationship between the rod diameter and the width and thickness of the prepreg sheet is: w = d * h, where w is the width of the prepreg sheet, d is the rod diameter, and h is the thickness of the prepreg sheet. Then, the entire prepreg sheet is cut online to form multiple sheets. Next, the cut sheets are preheated, fed into a pultrusion die, heated within the die, and pultruded. Finally, the sheets are cooled in a water bath and cut into solid rods of the appropriate length.

Description

Technical Field

[0001] This invention relates to the field of continuous fiber reinforced thermoplastic composite molding technology, specifically to a method for preparing continuous fiber reinforced polypropylene round solid rods. Background Technology

[0002] In recent years, the continuous fiber reinforced thermoplastic composite materials industry has experienced rapid development both domestically and internationally. The composite materials industry encompasses many highly vertical markets (such as aerospace, automotive, shipping, consumer goods, and wind energy), which consume composite materials in various ways. The extent of use is determined by component performance requirements, cost thresholds, local regulations, and customer needs. For example, the material, process, and cost parameters in the commercial aerospace manufacturing industry differ significantly from those in the recreational shipbuilding industry.

[0003] Continuous fiber reinforced thermoplastic composites are inherently diverse, enabling them to meet a wide range of complex needs. The availability of fibers, resins, tools, processes, and optional specialized finishing methods makes it possible to manufacture a variety of composite parts suitable for virtually any application. Due to their inherent superior strength, stiffness, durability, and lightweight properties, they can completely replace metallic or thermosetting materials in certain aspects, leading to their widespread use in industries such as machinery, construction, automotive, and transportation.

[0004] Continuous fiber-reinforced polypropylene round solid rods can serve as lightweight structural reinforcements in applications such as construction, bridges, shipbuilding, transportation, and electrical appliances. Previous attempts have been made to form rods from thermoplastic polymers in other types of applications. For example, Bryant et al.'s US Patent Publication No. 2005 / 0186410 explored the use of carbon fibers embedded in thermoplastic resin to form composite cores for power transmission cables. However, Bryant et al. noted that these cores exhibited cracks and dry spots due to insufficient fiber wetting, leading to poor durability and strength. Another problem with such cores is the inability to operate thermoplastic resins at high temperatures. The invention patent CN103501986B addresses the need for fiber-reinforced rods with desired strength, durability, and temperature characteristics for specific applications, but the process is cumbersome and inefficient. Utility model patent CN216466314U involves an external spiral winding process to wind hybrid fibers onto the surface of a core material. The fibers used for winding are composed of a hybrid high-toughness fiber primarily composed of high-strength carbon fibers.

[0005] The development of continuous fiber reinforced polypropylene round solid rods is of great significance: 1. Continuous fibers can ensure high rigidity and strength to meet specific performance requirements; 2. Compared with metal or thermosetting materials, it has a significant weight reduction effect; 3. It is recyclable and reusable, and its matrix material is polypropylene, which can realize waste recycling and is more environmentally friendly. Summary of the Invention

[0006] This invention provides a method for preparing continuous fiber reinforced polypropylene round solid rods. The method involves directly pultruding prepreg sheets to obtain round solid rods. A preheating device is added to fully vent air and enhance interfacial bonding, resulting in solid rods with good impregnation effect and high strength, while also improving production efficiency.

[0007] The specific method of this invention is as follows: First, determine the required fiber content of the rods, select prepreg tapes with consistent fiber content, and calculate the width and thickness of the prepreg tape sheet based on the diameter of the rods. The relationship between the rod diameter and the width and thickness of the prepreg tape sheet is as follows: Where w is the width of the prepreg sheet, d is the diameter of the rod, and h is the thickness of the prepreg sheet. The entire prepreg sheet is then cut online to produce multiple sheets. Next, the cut sheets are preheated, fed into a pultrusion die, heated inside the die, and pultruded. Finally, they are cooled in a water bath and cut into solid rods of the appropriate length.

[0008] The specific technical solution of this invention is as follows: Step 1: Determine the diameter d and fiber type content of the solid rod; Furthermore, the diameter of the solid rod is 10mm~20mm, the fiber type is glass fiber, and the glass fiber content is 50%~80%.

[0009] Step 2: Determine the thickness h and width w of the prepreg sheet; Furthermore, the thickness h of the prepreg sheet is 0.3mm~0.5mm, and the width... .

[0010] Step 3: Design a cutting tool for cutting prepreg sheets; Furthermore, the cutting tool contains 6 to 10 cutting blades, evenly distributed, and the blades can be blade-shaped or conical, preferably conical.

[0011] Step 4: Design a preheating device for preheating the prepreg sheet; Furthermore, the heating temperature of the preheating device is 100℃~140℃.

[0012] Step 5: Design a pultrusion die with a progressively changing circular cavity; Furthermore, the gradually changing diameter of the circular hole is designed according to the size of the prepreg sheet after cutting. The diameter of the mold exit hole is consistent with the diameter of the solid rod, and the diameter of the mold inlet hole is consistent with the width of the prepreg sheet after cutting.

[0013] Furthermore, the cavity contains four temperature zones: a front zone of 140℃~160℃, a middle zone 1 of 170℃~200℃, a middle zone 2 of 160℃~180℃, and a rear zone of 120℃~150℃.

[0014] Step 6: Design a water tank to cool the solid rods; Furthermore, the water tank includes two water tanks to ensure the straight pultrusion of solid bars and to provide sufficient cooling.

[0015] Step 7: Set up a cutting device for cutting round solid bars of the corresponding length.

[0016] The advantages of this invention are that the prepreg sheet is directly pultruded into round solid rods, which greatly improves the fiber impregnation effect, shortens the layout space of the entire production line, and allows for flexible control of the size and material type of the round solid rods to meet the needs of different applications, thus having market economic benefits. Attached Figure Description

[0017] Figure 1 Overall process diagram Figure 2 Mold structure diagram Figure 3 Schematic diagram of preheating and drainage device Figure 4 Schematic diagram of prepreg tape guiding device Figure 5 Schematic diagram of a concentrated circular ring Figure 6 Schematic diagram of blade-shaped cutting tool Figure 7 Schematic diagram of a conical cutting tool Detailed Implementation

[0018] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0019] A method for preparing continuous fiber reinforced polypropylene round solid rods: Step 1: Determine the diameter d and fiber type content of the solid rod; Furthermore, the diameter of the solid rod is 10mm~20mm, the fiber type is glass fiber, and the glass fiber content is 50%~80%.

[0020] Step 2: Determine the thickness h and width w of the prepreg sheet; Furthermore, the thickness h of the prepreg sheet is 0.3mm~0.5mm, and the width... .

[0021] Step 3: Design a cutting tool for cutting prepreg sheets; Furthermore, the cutting tool contains 6 to 10 cutting blades, evenly distributed.

[0022] Step 4: Design a preheating device for preheating the prepreg sheet; Furthermore, the heating temperature of the preheating device is 100℃~140℃.

[0023] Step 5: Design a pultrusion die with a progressively changing circular cavity; Furthermore, the gradually changing diameter of the circular hole is designed according to the size of the prepreg sheet after cutting. The diameter of the mold exit hole is consistent with the diameter of the solid rod, and the diameter of the mold inlet hole is consistent with the width of the prepreg sheet after cutting.

[0024] Furthermore, the cavity contains four temperature zones: a front zone of 140℃~160℃, a middle zone 1 of 170℃~200℃, a middle zone 2 of 160℃~180℃, and a rear zone of 120℃~150℃.

[0025] Step 6: Design a water tank to cool the solid rods; Furthermore, the water tank includes two water tanks to ensure the straight pultrusion of solid bars and to provide sufficient cooling.

[0026] Step 7: Set up a cutting device for cutting round solid bars of the corresponding length.

[0027] The present invention will be further illustrated below with reference to four embodiments.

[0028] The continuous fiber reinforced polypropylene material used in the following examples has the following composition: Polypropylene (EA5076) 24.4wt% Fiberglass (4305PM) 70wt% MAH-g-PP 5wt% 1010 0.3wt% 168 0.3wt%. Example 1

[0029] Step 1: Determine the diameter d and fiber type content of the solid rod: The diameter of the solid rod is 10mm, the fiber type is glass fiber, and the glass fiber content is 70%. Step 2: Determine the thickness h and width w of the prepreg sheet: The thickness h of the prepreg sheet is 0.3 mm, and the width w is... ; Step 3: Design a cutting tool for cutting prepreg sheets: The cutting tool contains 9 evenly distributed blades, which can cut into 10 sheets with a width of 26.18mm. The blades are blade-shaped, and the machine stops 1 to 2 times per shift (8 hours).

[0030] Step 4: Design a preheating device for preheating the prepreg sheet: the heating temperature of the preheating device is 100℃; Step 5: Design a pultrusion die with a progressively changing circular cavity: The progressively changing circular cavity size is designed based on the dimensions of the prepreg sheet after cutting. The die exit hole diameter is the same as the diameter of the solid bar, which is 10mm, and the die inlet hole diameter is the same as the width of the prepreg sheet after cutting, which is 26.18mm. The cavity contains four temperature zones: a front zone of 140℃, a middle zone 1 of 180℃, a middle zone 2 of 160℃, and a rear zone of 120℃. Step 6: Design a water tank for cooling solid bars: The water tank includes two water tanks to ensure that the solid bars are pultruded in a straight line and have sufficient cooling effect; Step 7: Set up a cutting device to cut round solid rods of the corresponding length, thereby obtaining continuous fiber-reinforced polypropylene round solid rods with a certain length and a diameter of 10mm. Example 2

[0031] Step 1: Determine the diameter d and fiber type content of the solid rod: The diameter of the solid rod is 10mm, the fiber type is glass fiber, and the glass fiber content is 70%. Step 2: Determine the thickness h and width w of the prepreg sheet: The thickness h of the prepreg sheet is 0.3 mm, and the width w is... ; Step 3: Design a cutting tool for cutting prepreg sheets: The cutting tool contains 4 evenly distributed blades, which can cut into 5 sheets with a width of 52.36mm. The blades are blade-shaped, and the machine stops 1 to 2 times per shift (8 hours).

[0032] Step 4: Design a preheating device for preheating the prepreg sheet: the heating temperature of the preheating device is 100℃; Step 5: Design a pultrusion die with a progressively changing circular cavity: The progressively changing circular cavity size is designed based on the dimensions of the prepreg sheet after cutting. The die exit hole diameter is the same as the diameter of the solid bar, which is 10mm, and the die inlet hole diameter is the same as the width of the prepreg sheet after cutting, which is 52.36mm. The cavity contains four temperature zones: a front zone of 140℃, a middle zone 1 of 180℃, a middle zone 2 of 160℃, and a rear zone of 120℃. Step 6: Design a water tank for cooling solid bars: The water tank includes two water tanks to ensure that the solid bars are pultruded in a straight line and have sufficient cooling effect; Step 7: Set up a cutting device to cut round solid rods of the corresponding length, thereby obtaining continuous fiber-reinforced polypropylene round solid rods with a certain length and a diameter of 10mm. Example 3

[0033] Step 1: Determine the diameter d and fiber type content of the solid rod: The diameter of the solid rod is 15mm, the fiber type is glass fiber, and the glass fiber content is 70%. Step 2: Determine the thickness h and width w of the prepreg sheet: The thickness h of the prepreg sheet is 0.3 mm, and the width w is... ; Step 3: Design a cutting tool for cutting prepreg sheets: The cutting tool contains 9 evenly distributed blades, which can cut into 10 sheets with a width of 58.91mm. The blades are blade-shaped, and the machine stops 1 to 2 times per shift (8 hours).

[0034] Step 4: Design a preheating device for preheating the prepreg sheet: the heating temperature of the preheating device is 100℃; Step 5: Design a pultrusion die with a progressively changing circular cavity: The progressively changing circular cavity size is designed based on the dimensions of the prepreg sheet after cutting. The die exit hole diameter is the same as the diameter of the solid bar, which is 15mm, and the die inlet hole diameter is the same as the width of the prepreg sheet after cutting, which is 58.91mm. The cavity contains four temperature zones: a front zone of 140℃, a middle zone 1 of 180℃, a middle zone 2 of 160℃, and a rear zone of 120℃. Step 6: Design a water tank for cooling solid bars: The water tank includes two water tanks to ensure that the solid bars are pultruded in a straight line and have sufficient cooling effect; Step 7: Set up a cutting device to cut round solid rods of the corresponding length, thereby obtaining continuous fiber-reinforced polypropylene round solid rods with a certain length and a diameter of 15mm. Example 4

[0035] Step 1: Determine the diameter d and fiber type content of the solid rod: The diameter of the solid rod is 20mm, the fiber type is glass fiber, and the glass fiber content is 70%. Step 2: Determine the thickness h and width w of the prepreg sheet: The thickness h of the prepreg sheet is 0.3 mm, and the width w is... ; Step 3: Design a cutting tool for cutting prepreg sheets: The cutting tool contains 9 evenly distributed blades, which can cut into 10 sheets with a width of 104.72mm. The blades are blade-shaped, and the machine stops 1 to 2 times per shift (8 hours).

[0036] Step 4: Design a preheating device for preheating the prepreg sheet: the heating temperature of the preheating device is 100℃; Step 5: Design a pultrusion die with a progressively changing circular cavity: The progressively changing circular cavity size is designed based on the dimensions of the prepreg sheet after cutting. The die exit hole diameter is the same as the diameter of the solid bar, which is 20mm, and the die inlet hole diameter is the same as the width of the prepreg sheet after cutting, which is 104.72mm. The cavity contains four temperature zones: a front zone of 140℃, a middle zone 1 of 180℃, a middle zone 2 of 160℃, and a rear zone of 120℃. Step 6: Design a water tank for cooling solid bars: The water tank includes two water tanks to ensure that the solid bars are pultruded in a straight line and have sufficient cooling effect; Step 7: Set up a cutting device to cut round solid rods of the corresponding length, thereby obtaining continuous fiber-reinforced polypropylene round solid rods with a certain length and a diameter of 20mm. Example 5

[0037] Step 1: Determine the diameter d and fiber type content of the solid rod: The diameter of the solid rod is 20mm, the fiber type is glass fiber, and the glass fiber content is 70%. Step 2: Determine the thickness h and width w of the prepreg sheet: The thickness h of the prepreg sheet is 0.3 mm, and the width w is... ; Step 3: Design a cutting tool for cutting prepreg sheets: The cutting tool contains 9 evenly distributed blades, which can cut into 10 sheets with a width of 104.72mm. The blades are conical, and the machine stops 4 to 5 times per shift (8 hours).

[0038] Step 4: Design a preheating device for preheating the prepreg sheet: the heating temperature of the preheating device is 100℃; Step 5: Design a pultrusion die with a progressively changing circular cavity: The progressively changing circular cavity size is designed based on the dimensions of the prepreg sheet after cutting. The die exit hole diameter is the same as the diameter of the solid bar, which is 20mm, and the die inlet hole diameter is the same as the width of the prepreg sheet after cutting, which is 104.72mm. The cavity contains four temperature zones: a front zone of 140℃, a middle zone 1 of 180℃, a middle zone 2 of 160℃, and a rear zone of 120℃. Step 6: Design a water tank for cooling solid bars: The water tank includes two water tanks to ensure that the solid bars are pultruded in a straight line and have sufficient cooling effect; Step 7: Set up a cutting device to cut round solid rods of the corresponding length, thereby obtaining continuous fiber-reinforced polypropylene round solid rods with a certain length and a diameter of 20mm.

[0039] By analyzing the above embodiments, it is not difficult to find that by using the method of the present invention, the embodiment adopts the method of pultruding solid rods by prepreg tape sheets, and the corresponding tool and die size distribution can be flexibly changed to obtain solid rods of the corresponding diameter. The material used in the embodiment of the present invention is continuous glass fiber reinforced PP with a glass fiber content of 70%. In addition, the present invention is also applicable to continuous glass fiber reinforced PA, PPT, etc.

[0040] The equipment used in the method of this invention is simple, easy to implement and operate, reduces design and processing costs, greatly improves production efficiency, and has broad application prospects.

[0041] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for preparing continuous fiber reinforced polypropylene circular solid rods, characterized in that, Continuous fiber reinforced thermoplastic composite prepreg sheets are cut online, preheated and degassed by a specific temperature device, and then formed into round solid rods by a pultrusion die with a gradually changing circular cavity. Finally, they are cooled by a composite water tank to obtain round solid rods of the corresponding length and density.

2. A method for preparing continuous fiber reinforced polypropylene circular solid rods, characterized in that, Includes the following steps: Step 1: Determine the diameter d and fiber type content of the solid rod; Step 2: Determine the thickness h and width w of the prepreg sheet; Step 3: Design a blade for cutting prepreg sheets; Step 4: Design a preheating device for preheating the prepreg sheet; Step 5: Design a pultrusion die with a progressively changing circular cavity; Step 6: Design a water tank to cool the solid rods; Step 7: Set up a cutting device for cutting round solid bars of the corresponding length.

3. The method for preparing continuous fiber reinforced polypropylene round solid rods according to claim 1, characterized in that, The continuous fiber reinforced thermoplastic composite is a continuous glass fiber reinforced thermoplastic composite, wherein the mass percentage of glass fiber in the continuous fiber reinforced thermoplastic composite is 50~80wt%.

4. The method for preparing a continuous fiber reinforced polypropylene circular solid rod according to claim 1, characterized in that, The matrix resin of continuous glass fiber reinforced composites is a thermoplastic such as polypropylene or nylon.

5. The method for preparing a continuous fiber reinforced polypropylene circular solid rod according to claim 1, characterized in that, The diameter of the round solid bar is 10mm~20mm.

6. The method for preparing a continuous fiber reinforced polypropylene circular solid rod according to claim 1, characterized in that, The glass fiber content of the round solid rods is the same as that of the continuous fiber reinforced thermoplastic composite prepreg sheet.

7. The method for preparing a continuous fiber reinforced polypropylene circular solid rod according to claim 1, characterized in that, The initial width of the continuous fiber reinforced thermoplastic prepreg sheet is calculated from the initial thickness of the continuous fiber reinforced thermoplastic prepreg sheet and the diameter of the round solid rod: (where w is the width of the continuous fiber reinforced thermoplastic prepreg sheet, d is the diameter of the round solid rod, and h is the thickness of the continuous fiber reinforced thermoplastic prepreg sheet).

8. The method for preparing continuous fiber reinforced polypropylene round solid rods according to claim 1, characterized in that, The dimensions of the continuous fiber reinforced thermoplastic composite prepreg sheet after online cutting and the dimensions of the pultrusion die cavity are as follows: the gradually changing dimensions of the circular cavity are designed according to the dimensions of the prepreg sheet after cutting; the diameter of the die exit hole is consistent with the diameter of the solid rod; and the diameter of the die inlet hole is consistent with the width of the continuous fiber reinforced thermoplastic composite prepreg sheet after cutting.

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