Injection dip process for glass fiber reinforced polyurethane profiles with reduced die interface resin retention

Abstract

This application relates to an injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles that reduces resin retention at the mold interface. It belongs to the field of glass fiber reinforced polyurethane profile processing technology, and includes: glass fiber entering a mold; polyurethane material reacting with the glass fiber during impregnation and pultrusion molding; the mold has a front section, a middle section, and a rear section, with the front section temperature at 20-30℃, the middle section temperature at 100-130℃, and the rear section temperature at 150-190℃; the polyurethane material includes components A and B, with a mass ratio of A to B of 100:(60-100). Component A includes liquefied MDI, and component B includes 100 parts of polyether polyol, 5-10 parts of siloxane-modified polyol, 3-5 parts of fluorinated polyether polyol, 2-10 parts of 1,4-butanediol, 0.1-0.5 parts of dimethylcyclohexylamine, 0.01-0.1 parts of organotin catalyst, and 0.1-0.8 parts of nonionic surfactant. This process can reduce resin retention at the mold interface.

Description

Technical Field

[0001] This application relates to an injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles that reduces resin retention at the mold interface, and belongs to the field of glass fiber reinforced polyurethane profile processing technology. Background Technology

[0002] In recent years, glass fiber reinforced composite materials have been widely used in building profiles, transportation, and industrial structural components. Among these, pultrusion molding has become an important technical route for preparing long-length composite profiles due to its continuous production, high efficiency, and stable product performance. Commonly used matrix resins in pultrusion systems include epoxy resins, vinyl ester resins, and polyurethane resins.

[0003] Compared to epoxy or vinyl ester resin systems, polyurethane-based composites offer advantages such as faster reaction speed, better wettability, and superior toughness during pultrusion molding. However, they also exhibit higher system viscosity and reactivity. During in-mold curing, especially in the curing front area, incompletely cured resin systems are prone to localized adhesion on the mold cavity surface. In continuous pultrusion production, due to the continuous flow and rapid curing of the resin system, tiny resin residues or cured debris can gradually form at the mold front and curing zone entrance. Under long-term operating conditions, some of these residues may be carried out of the mold cavity with the product, while others will continue to adhere and accumulate. When resin residues accumulate to a certain extent in the mold, they can easily alter the effective space size and surface condition of the local mold cavity, thereby affecting resin flow and curing uniformity, leading to local curing environment instability. This can result in problems such as surface defects, dimensional deviations, or increased demolding resistance, and in severe cases, even mold cavity blockage, causing production line shutdown.

[0004] Therefore, how to effectively suppress resin adhesion and accumulation on the mold surface, reduce mold cavity contamination and mold blockage risk, and improve continuous production stability and mold service life during the pultrusion molding of polyurethane-based fiber-reinforced composites has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] Because polyurethane-based composite materials have high reactivity and low initial viscosity during the addition reaction, they quickly become sticky during the reaction, resulting in strong wetting and adhesion to the mold surface. The viscosity controllability is poor. In the early stage of the curing zone of the mold, the resin has just started to react but has not yet fully cured. At this time, some resin is prone to separate from the system and stick to the mold wall to form small resin blocks. If these small resin blocks cannot be carried away by the product as the subsequent pultrusion continues, they will block the mold cavity in the mold, causing production interruption and requiring the machine to be stopped and the mold cleaned.

[0006] The main reason for this problem is that polyurethane undergoes premature gelation and interfacial retention in the early stage of the mold, leading to the accumulation of small resin clumps. To solve this problem, an injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles is provided to reduce resin retention at the mold interface. A dynamic interfacial surface energy control system is constructed using siloxane-modified polyols and fluorinated polyether polyols. With the addition of other components and optimization of the reaction temperature, the resin system can be prevented from rapidly gelling in the early stage of the mold, effectively avoiding the formation of a high-adhesion state in the early stage. Rapid heating in the middle stage allows the system to quickly pass through the high viscoelastic zone. Furthermore, optimization in the middle stage continuously improves the interfacial surface energy. Combined with rapid curing in the later stage, this effectively improves the problem of polyurethane adhesion and accumulation in the early stage of the mold.

[0007] This application provides an injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles that reduces resin retention at the mold interface. The injection impregnation pultrusion molding process includes the following steps: S1. Prepare continuous glass fiber, arrange it under the traction of the traction machine through the guide plate, and then enter the molding die; S2. Simultaneously, the syringe injects polyurethane material into the pultrusion mold. While the polyurethane material is impregnated with the glass fiber, it undergoes a polymerization reaction and, under the continuous traction of the glass fiber, completes the pultrusion process. The pultrusion die is provided with three temperature zones along its length: a front section, a middle section, and a rear section. The temperature of the front section is 20~30℃, the temperature of the middle section is 100~130℃, and the temperature of the rear section is 150~190℃. The syringe includes syringe A and syringe B. The polyurethane material includes component A and component B, and the injection mass ratio of component A to component B is 100:(60~100). Component A includes liquefied MDI. Component B, by weight, includes: 100 parts of polyether polyol, 5~10 parts of siloxane-modified polyol, 3~5 parts of fluorinated polyether polyol, 2~10 parts of 1,4-butanediol, 0.1~0.5 parts of dimethylcyclohexylamine, 0.01~0.1 parts of organotin catalyst, and 0.1~0.8 parts of nonionic surfactant. Syringe A and syringe B respectively contain component A and component B.

[0008] Optionally, the inner wall of the middle section is provided with microgrooves extending along the pultrusion direction, and the roughness Ra of the middle section is 1.0~2.0μm; Neither the front nor the rear section has the microgrooves. The front section is a tapered flow channel, the roughness Ra of the rear section is 0.5~1.0μm, and the inner surface of the rear section is provided with a 3~6μm PTFE coating.

[0009] PTFE possesses excellent wear resistance, low friction, and high temperature resistance, making it more suitable for the application scenarios described in this application compared to PVDF, PFA, and ETFE. It should be noted that those skilled in the art can choose appropriate processes to prepare the PTFE coating; for example, the most common method is spraying.

[0010] Optionally, the depth of the microgrooves in the middle section is 1~5μm, the width is 5~20μm, and the spacing is 10~50μm.

[0011] Optionally, the roughness Ra of the middle section is 1.2~1.6μm.

[0012] Optionally, the roughness Ra of the rear end is 0.8~1.0μm.

[0013] Optionally, the traction speed of the glass fiber is 0.6~0.8m / min, and the mold cavity pressure is 1.5~2.0MPa.

[0014] Optionally, the glass fiber accounts for 60-70 vol% of the volume of the glass fiber reinforced polyurethane profile.

[0015] Optionally, the syringe further includes a premixer C, which is disposed after the syringe A and syringe B. Components A and B are mixed in the premixer C to form a polyurethane material before entering the molding die. The syringe A, syringe B, and premixer C are heat-insulated so that the temperature of the polyurethane material is 20~30°C when the polyurethane material is impregnated with the glass fiber.

[0016] Optionally, the liquefied MDI is a polymethylene polyphenyl isocyanate; The siloxane-modified polyol is a hydroxyl-terminated polydimethylsiloxane; The fluorinated polyether polyol is a perfluorinated polyether diol; The nonionic surfactant is an organosilicon surfactant.

[0017] Optionally, component B may further include 1 to 5 parts of nano-silica, wherein the nano-silica has a particle size of 300 to 500 nm.

[0018] This application provides glass fiber reinforced polyurethane composite profiles prepared by the above-mentioned injection impregnation pultrusion molding process for reducing resin retention at the mold interface.

[0019] This application provides the application of the aforementioned fiberglass reinforced polyurethane composite profiles in building door and window products.

[0020] The beneficial effects of this application include, but are not limited to: 1. According to the injection impregnation pultrusion molding process of glass fiber reinforced polyurethane profiles with reduced resin retention at the mold interface, the present application optimizes the composition of component B by introducing siloxane-modified polyols and fluorinated polyether polyols with low surface energy segments, which are combined with nonionic surfactants. On the one hand, they participate in the reaction during curing and are anchored in the resin network. On the other hand, due to their low surface energy characteristics, they migrate to the mold interface, thereby forming a stable enriched layer at the interface, which plays a regulatory role in the resin-mold interface, continuously replenishing the low-energy layer at the interface and weakening the interfacial adhesion, thereby effectively inhibiting the wetting and spreading of resin on the mold surface. In addition, the use of 1,4-butanediol, organotin catalyst, and slow-reaction amine catalyst dimethylcyclohexylamine can reduce the front-end reaction rate and delay the gel point, which can avoid the situation where the resin has already adhered to the mold wall when it becomes a semi-cured adhesive, thereby reducing resin accumulation. By constructing an interface dynamic regulation system, the problem of local premature gelation and retention of polyurethane at the interface in the front of the pultrusion mold can be significantly improved, thereby effectively avoiding the formation and accumulation of resin accumulation.

[0021] 2. According to the injection impregnation pultrusion molding process of glass fiber reinforced polyurethane profiles with reduced resin retention at the mold interface as described in this application, the curing temperature of the pultrusion mold has also been optimized to match the polyurethane system. The low temperature zone in the early stage can suppress the reaction, the rapid temperature rise in the middle stage can cross the high viscosity zone, and the temperature in this stage is suitable for the reaction of siloxane-modified polyol and fluorinated polyether polyol while migrating to the mold interface, effectively regulating the interface between the resin and the mold, continuously replenishing the low-energy layer at the interface and weakening the interfacial adhesion, while the later stage mainly completes curing quickly, which can effectively shorten the residence time of the resin in the easily adhesive state, especially effectively avoiding the formation of adhesion cores in the early stage of the mold. By optimizing the temperature, it is possible to suppress resin retention in the early stage of the mold, effectively prevent the formation and accumulation of resin blocks in the middle stage, and achieve rapid curing in the later stage, thereby improving the stability of continuous production and extending the downtime.

[0022] 3. According to the injection impregnation pultrusion molding process of glass fiber reinforced polyurethane profiles for reducing resin retention at the mold interface in this application, the pultrusion mold is optimized. In the later stage, the resin adhesion problem is improved by adding a PTFE coating. For the middle stage, which mainly produces semi-cured adhesion, microgrooves extending along the pultrusion direction are set in the structure. In addition, since it is not convenient to add a PTFE coating by setting microgrooves, siloxane-modified polyols and fluorinated polyether polyols with low surface energy segments are added to component B. In combination with nonionic surfactants, the low-energy layer at the interface can be continuously replenished and the interfacial adhesion can be weakened. The dual improvement of structure and composition can effectively inhibit the wetting and spreading of resin on the mold surface. In addition, the roughness of the middle and later stages is optimized, which can significantly improve the amount of resin residue in the mold.

[0023] 4. According to the injection impregnation pultrusion molding process of glass fiber reinforced polyurethane profile with reduced resin retention at the mold interface of this application, by controlling the temperature of the polyurethane material when it is impregnated with glass fiber, the resin can be prevented from reacting prematurely and becoming highly viscous. Furthermore, by optimizing the matching of traction speed and reaction rate, resin retention can be prevented. Optimizing the mold cavity pressure can control the degree of resin adhesion to the mold wall. Controlling the amount of glass fiber can improve the resin carry-out effect and reduce the accumulation of excess resin on the mold wall. Attached Figure Description

[0024] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This pertains to the resin retention at the mold interface in existing technologies. Figure 2 This refers to the product damage caused by resin retention at the mold interface in existing technologies. Figure 3 This describes the cornering of the product obtained using the process described in Example 1 of this application. Figure 4 The surface of the product obtained by using the process of Example 1 of this application is shown. Detailed Implementation

[0025] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments. Unless otherwise specified, the raw materials and reagents in the embodiments of the present application are all purchased through commercial channels.

[0026] like Figure 1 and Figure 2 These are examples of resin retention at the mold interface that occurs when using existing technologies and processes, and the resulting product damage, such as... Figure 3 and Figure 4 The images show the improved process after adopting the proposed solution, and the corners and surface of the resulting products. As can be seen from the images, the products obtained by the proposed solution have a smooth surface and a strong gloss, and are less prone to damage. The proposed process can not only operate continuously for a long time, but also ensure a high product yield.

[0027] The present application and its beneficial effects are illustrated below through specific embodiments.

[0028] Example 1 In this embodiment, the polyurethane material is composed of a mixture of component A and component B. The syringe structure in the processing equipment includes syringe A, syringe B, and premixer C. Syringe A and syringe B respectively contain component A and component B. Component A and component B enter premixer C and mix to form the polyurethane material. Then, the polyurethane material is injected into a molding die to complete the impregnation with glass fiber. Syringe A, syringe B, and premixer C are heat-insulated to ensure that the temperature of the polyurethane material is maintained at 25°C during the impregnation with glass fiber.

[0029] Component A is polymethylene polyphenyl isocyanate (purchased from McCarthy Reagents, catalog number M089896), and component B, by weight, includes: 100 parts of polyether polyol (purchased from Jiangyin Youbang Chemical Co., Ltd., catalog number YB). 3028), hydroxyl-terminated polydimethylsiloxane (purchased from Shanghai Yuanye Biotechnology Co., Ltd., item number V30227) 8 parts, perfluoropolyether diol (purchased from Fuzhou Taipuda New Material Co., Ltd., average molecular weight M w 4 parts of 2000), 6 parts of 1,4-butanediol, 0.2 parts of dimethylcyclohexylamine, 0.05 parts of organotin catalyst (purchased from Xindian Chemical Materials (Shanghai) Co., Ltd., item number organotin-t12), and 0.3 parts of organosilicon surfactant (purchased from Jiangsu Yake Technology Co., Ltd., item number SilGuard YK-1102).

[0030] The pultrusion die in the processing equipment has three temperature zones along its length: a front section (200 mm), a middle section (350 mm), and a rear section (700 mm). The front section has a tapered, tapered flow channel with a compression ratio of 1.02 to 1.05. The inner wall of the middle section has microgrooves extending along the pultrusion direction, with a depth of 3 μm, a width of 10 μm, and a spacing of 30 μm. The surface roughness Ra of the middle section is maintained at 1.2 to 1.6 μm. The temperature of the front section is 25℃, the temperature of the middle section is 115℃, and the temperature of the rear section is 180℃. The inner surface of the rear section has a 5 μm PTFE coating, and the surface roughness Ra of the rear section is maintained at 0.8 to 1.0 μm.

[0031] The processing technology for glass fiber reinforced polyurethane profiles includes the following steps: S1. Prepare continuous glass fiber, arrange it under the traction of the traction machine through the guide plate, and then enter the molding die; S2. Simultaneously inject polyurethane material into the pultrusion mold using an syringe, controlling the injection mass ratio of component A to component B to be 100:80, ensuring the NCO / OH equivalent ratio is between 1.05 and 1.10, and controlling the injection amount of polyurethane material so that the glass fiber accounts for 60-70 vol% of the volume fraction of the glass fiber reinforced polyurethane profile. The polyurethane material undergoes a polymerization reaction while being impregnated with the glass fiber, and under the continuous traction of the glass fiber, pultrusion molding is completed. The traction speed of the glass fiber is 0.7 m / min, and the mold cavity pressure is 1.8 MPa. After the pultruded product cools, the glass fiber reinforced polyurethane profile is obtained.

[0032] Example 2 In this embodiment, the polyurethane material is composed of a mixture of component A and component B. The syringe structure in the processing equipment includes syringe A, syringe B, and premixer C. Syringe A and syringe B respectively contain component A and component B. Component A and component B enter premixer C and mix to form the polyurethane material. Then, the polyurethane material is injected into a molding die to complete the impregnation with glass fiber. Syringe A, syringe B, and premixer C are heat-insulated to ensure that the temperature of the polyurethane material is maintained at 20°C during the impregnation with glass fiber.

[0033] Component A is polymethylene polyphenyl isocyanate (purchased from McCarthy Reagents, catalog number M089896), and component B consists of the following components by weight: 100 parts polyether polyol (purchased from Jiangyin Youbang Chemical Co., Ltd., catalog number YB). 3028), 5 parts of hydroxyl-terminated polydimethylsiloxane (purchased from Shanghai Yuanye Biotechnology Co., Ltd., item number V30227), and perfluoropolyether diol (purchased from Fuzhou Taipuda New Material Co., Ltd., average molecular weight M). w 3 parts of 2000), 2 parts of 1,4-butanediol, 0.1 parts of dimethylcyclohexylamine, 0.01 parts of organotin catalyst (purchased from Xindian Chemical Materials (Shanghai) Co., Ltd., item number organotin-t12), and 0.1 parts of organosilicon surfactant (purchased from Jiangsu Yake Technology Co., Ltd., item number SilGuard YK-1102).

[0034] The pultrusion die in the processing equipment is configured with three temperature zones along its length: a front section (200 mm), a middle section (350 mm), and a rear section (700 mm). The front section is a tapered, tapered flow channel with a compression ratio of 1.02–1.05. The inner wall of the middle section has microgrooves extending along the pultrusion direction, with a depth of 1 μm, a width of 5 μm, and a spacing of 10 μm. The surface roughness Ra of the middle section is maintained at 1.2–1.6 μm. The temperature of the front section is 20°C, the temperature of the middle section is 130°C, and the temperature of the rear section is 190°C. The inner surface of the rear section is coated with a 3 μm PTFE coating, and the surface roughness Ra of the rear section is 0.8–1.0 μm.

[0035] The processing technology for glass fiber reinforced polyurethane profiles includes the following steps: S1. Prepare continuous glass fiber, arrange it under the traction of the traction machine through the guide plate, and then enter the molding die; S2. Simultaneously inject polyurethane material into the pultrusion mold using an syringe, controlling the injection mass ratio of component A to component B to be 100:80, ensuring the NCO / OH equivalent ratio is between 1.05 and 1.10, and controlling the injection amount of polyurethane material so that the glass fiber accounts for 60-70 vol% of the volume fraction of the glass fiber reinforced polyurethane profile. The polyurethane material undergoes a polymerization reaction while being impregnated with the glass fiber, and under the continuous traction of the glass fiber, pultrusion molding is completed. The traction speed of the glass fiber is 0.8 m / min, and the mold cavity pressure is 2.0 MPa. After the pultruded product cools, the glass fiber reinforced polyurethane profile is obtained.

[0036] Example 3 In this embodiment, the polyurethane material is composed of a mixture of component A and component B. The syringe structure in the processing equipment includes syringe A, syringe B, and premixer C. Syringe A and syringe B respectively contain component A and component B. Component A and component B enter the premixer C and mix to form the polyurethane material. Then, the polyurethane material is injected into a molding die to complete the impregnation with glass fiber. Syringe A, syringe B, and premixer C are heat-insulated to ensure that the temperature of the polyurethane material is maintained at 30°C during the impregnation with glass fiber.

[0037] Component A is polymethylene polyphenyl isocyanate (purchased from McCarthy Reagents, catalog number M089896), and component B consists of the following components by weight: 100 parts polyether polyol (purchased from Jiangyin Youbang Chemical Co., Ltd., catalog number YB). 3028), 10 parts of hydroxyl-terminated polydimethylsiloxane (purchased from Shanghai Yuanye Biotechnology Co., Ltd., item number V30227), and perfluoropolyether diol (purchased from Fuzhou Taipuda New Material Co., Ltd., average molecular weight M) w5 parts of 2000), 10 parts of 1,4-butanediol, 0.5 parts of dimethylcyclohexylamine, 0.1 parts of organotin catalyst (purchased from Xindian Chemical Materials (Shanghai) Co., Ltd., item number organotin-t12), and 0.8 parts of organosilicon surfactant (purchased from Jiangsu Yake Technology Co., Ltd., item number SilGuard YK-1102).

[0038] The pultrusion die in the processing equipment has three temperature zones along its length: a front section, a middle section, and a rear section. The front section is 200 mm long, the middle section is 350 mm long, and the rear section is 700 mm long. The front section is a tapered, tapered flow channel with a compression ratio of 1.02~1.05. The inner wall of the middle section has microgrooves extending along the pultrusion direction, with a depth of 5 μm, a width of 20 μm, and a spacing of 50 μm. The surface roughness Ra of the middle section is maintained at 1.2~1.6 μm. The temperature of the front section is 30℃, the temperature of the middle section is 100℃, and the temperature of the rear section is 150℃. The inner surface of the rear section is coated with a 6 μm PTFE coating, and the surface roughness Ra of the rear section is 0.8~1.0 μm.

[0039] The processing technology for glass fiber reinforced polyurethane profiles includes the following steps: S1. Prepare continuous glass fiber, arrange it under the traction of the traction machine through the guide plate, and then enter the molding die; S2. Simultaneously inject polyurethane material into the pultrusion mold using an syringe, controlling the injection mass ratio of component A to component B to be 100:80, ensuring the NCO / OH equivalent ratio is between 1.05 and 1.10, and controlling the injection amount of polyurethane material so that the glass fiber accounts for 60-70 vol% of the volume fraction of the glass fiber reinforced polyurethane profile. The polyurethane material undergoes a polymerization reaction while being impregnated with the glass fiber, and under the continuous traction of the glass fiber, pultrusion molding is completed. The traction speed of the glass fiber is 0.6 m / min, and the mold cavity pressure is 1.5 MPa. After the pultruded product cools, the glass fiber reinforced polyurethane profile is obtained.

[0040] Example 4 This embodiment is basically the same as that of Embodiment 1, except that component B also includes 3 parts of nano-silica particles with a particle size range of 300~500nm.

[0041] Example 5 This embodiment is basically the same as Embodiment 1, except that the inner wall of the middle section does not have microgrooves extending along the pultrusion direction.

[0042] Example 6 This embodiment is basically the same as Embodiment 1, except that the inner surface of the rear section is not coated with PTFE.

[0043] Example 7 This embodiment is basically the same as Embodiment 1, except that the roughness Ra of the middle section is maintained at 0.3~0.8μm.

[0044] Example 8 This embodiment is basically the same as Embodiment 1, except that the roughness Ra of the latter part is maintained at 1.2~1.6μm.

[0045] Example 9 This embodiment is basically the same as Embodiment 1, except that the mold cavity pressure is 2.2 MPa.

[0046] Example 10 This embodiment is basically the same as Embodiment 1, except that the traction speed of the glass fiber is 0.5 m / min.

[0047] Comparative Example 1 This comparative example is basically the same as Example 1, except that component B does not contain hydroxyl-terminated polydimethylsiloxane.

[0048] Comparative Example 2 This comparative example is basically the same as Example 1, except that component B does not contain perfluoropolyether diol.

[0049] Comparative Example 3 This comparative example is basically the same as Example 1, except that component B does not contain hydroxyl-terminated polydimethylsiloxane and perfluoropolyether diol.

[0050] Comparative Example 4 This comparative example is basically the same as Example 1, except that the temperature of the front section of the pultrusion die is 25°C, the temperature of the middle section is 90°C, and the temperature of the rear section is 180°C.

[0051] Comparative Example 5 This comparative example is basically the same as Example 1, except that the temperature of the front section of the pultrusion die is 35°C, the temperature of the middle section is 140°C, and the temperature of the rear section is 180°C.

[0052] Test Example 1 The researchers tested and compared the effects of the above process conditions on improving resin retention at the mold interface. The test items included the amount of residual resin in the mold and the contact angle of the inner surface of the mold.

[0053] In the mold resin residue test, the mold section (front section + middle section + rear section) was disassembled after running continuously for 12 hours using the processing technology of each embodiment or comparative example. The mass was directly weighed and recorded as m1. After being calculated with the mold mass m0 before production, the mold resin residue Δm (mg) can be calculated. Δm = m1 - m0.

[0054] In the contact angle test of the inner surface of the mold, the wettability of the mold surface (front / middle section) is evaluated to reflect the change in surface energy of the inner surface of the mold after production. The test environment is 20℃. The unreacted PU mixture (polymethylene polyphenyl isocyanate + polyether polyol, which has been stored at 10~15℃ before mixing and the mixing time is controlled within 30s) is dropped onto the inner surface of the mold after production using a micro-syringe. The contact angle is obtained by taking pictures with a contact angle meter and automatically fitting the angle with software. Five points are measured for each sample and the average value is taken as the contact angle. The test of each point is completed within 1 minute after the polymethylene polyphenyl isocyanate and polyether polyol are mixed in the PU mixture.

[0055] The test results are shown in Table 1 below.

[0056] Table 1. Test results of residual resin in the mold and contact angle of the inner surface of the mold.

[0057] According to the results in Table 1, the proposed solution can effectively reduce the amount of residual resin in the mold. Furthermore, the contact angle of the inner surface of the mold in the middle section is significantly increased compared to the front section. This indicates that the surface energy of the middle section is effectively reduced during the processing, making it less likely for the resin to spread on the mold and causing sticking.

[0058] Researchers found that adding an appropriate amount of nano-silica particles as a microfiller to component B can regulate the interface between the mold and the resin, reducing resin spreading on the mold surface and thus reducing the occurrence of wall adhesion. In addition, researchers found that the organosilicon surfactant added to component B is crucial for the interface regulation effect of nano-silica particles.

[0059] In this application, a microgroove structure is incorporated into the middle section of the pultrusion die, and a PTFE coating is applied to the inner surface of the rear section, which significantly reduces the amount of residual resin in the die. Furthermore, researchers discovered that the roughness range of the middle and rear sections has a significant impact on the amount of residual resin in the die. Surprisingly, the roughness of the middle section needs to be maintained within a suitable range; excessively small roughness can significantly increase the amount of residual resin. Conversely, the roughness of the rear section needs to be kept within a relatively small range; excessive roughness is detrimental to reducing the amount of residual resin. Based on experience, researchers speculate that this result may be due to the dynamic nature of the resin during the pultrusion process, with different curing stages exhibiting different characteristics. Therefore, differentiated design and optimization of the structure and curing conditions of the front, middle, and rear sections are particularly important.

[0060] Researchers also tested a process where the inner wall of the middle section lacked microgrooves extending along the pultrusion direction but was coated with a PTFE coating of the same thickness as the rear section. They found that the residual resin in the mold was as high as 218 mg. This shows that simply improving the surface energy of the middle section can have a certain improvement effect, but the effect is not sustainable. The solution in this application targets the middle section, a high-viscosity stage that requires special attention. Through structural improvements combined with the continuous introduction of low-surface-energy siloxane-modified polyols and fluorinated polyether polyols in the resin system, the low-energy layer at the interface can be continuously replenished and the interfacial adhesion can be weakened. This effectively inhibits the wetting and spreading of the resin on the mold surface, which has significant advantages over simply coating with a PTFE coating.

[0061] Based on the results of Examples 9 and 10, it is evident that excessive mold cavity pressure alters the resin interface flow and reaction state, making it easier for the resin to remain and adhere to the mold wall. Conversely, a slower glass fiber traction speed can lead to resin accumulation, increasing the amount of residual resin in the mold. Furthermore, researchers found that controlling the glass fiber volume percentage to 60-70% of the glass fiber reinforced polyurethane profile is more conducive to balancing strength performance requirements, cost factors, and residual resin in the mold. If the glass fiber volume percentage decreases, the ability to traction and remove resin weakens, leading to easier resin accumulation and increased residual resin in the mold.

[0062] According to the results of Comparative Examples 1, 2 and 3, the synergistic effect of hydroxyl-terminated polydimethylsiloxane and perfluoropolyether diol in this application can participate in the polymerization reaction and migrate to the interface between the resin and the mold, thus playing a good role in controlling the interface. In the case where it is inconvenient to coat PTFE coating in the middle section due to the microgrooves, the hydroxyl-terminated polydimethylsiloxane and perfluoropolyether diol in component B can effectively improve the surface energy of the middle section and significantly reduce the amount of residual resin in the mold.

[0063] Based on the results of Comparative Examples 4 and 5, it is evident that if the temperature of the pultrusion mold is too high, especially in the front and middle sections, the resin will cure prematurely instead of primarily curing in the middle section. This results in an early increase in resin viscosity in the front section, leading to an increase in resin residue in the mold. Conversely, if the temperature is too low, especially in the middle section, it hinders the migration of hydroxyl-terminated polydimethylsiloxane and perfluoropolyether diol to the resin-mold interface, resulting in a poorer effect on altering the surface energy in the middle section. This, in turn, leads to a significant increase in resin residue in the mold.

[0064] Test Example 2 The experimenters conducted continuous production using the process of Example 1. If mold cavity blockage occurred, the machine was immediately stopped for cleaning and the test was stopped. The test results are shown in Table 2 below.

[0065] Table 2 Results of continuous production test of the process in Example 1

[0066] As shown in Table 2, the proposed solution can produce continuously for at least 10 days without mold cavity blockage, and features stable operation and convenient maintenance, which is of great significance for industrial applications.

[0067] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. An injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles that reduces resin retention at the mold interface, characterized in that, The injection molding process includes the following steps: S1. Prepare continuous glass fiber, arrange it under the traction of the traction machine through the guide plate, and then enter the molding die; S2. Simultaneously, the syringe injects polyurethane material into the pultrusion mold. While the polyurethane material is impregnated with the glass fiber, it undergoes a polymerization reaction and, under the continuous traction of the glass fiber, completes the pultrusion process. The pultrusion die is provided with three temperature zones along its length: a front section, a middle section, and a rear section. The temperature of the front section is 20~30℃, the temperature of the middle section is 100~130℃, and the temperature of the rear section is 150~190℃. The syringe includes syringe A and syringe B. The polyurethane material includes component A and component B, and the injection mass ratio of component A to component B is 100:(60~100). Component A includes liquefied MDI. Component B, by weight, includes: 100 parts of polyether polyol, 5~10 parts of siloxane-modified polyol, 3~5 parts of fluorinated polyether polyol, 2~10 parts of 1,4-butanediol, 0.1~0.5 parts of dimethylcyclohexylamine, 0.01~0.1 parts of organotin catalyst, and 0.1~0.8 parts of nonionic surfactant. Syringe A and syringe B respectively contain component A and component B.

2. The injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles with reduced resin retention at the mold interface according to claim 1, characterized in that, The inner wall of the middle section is provided with microgrooves extending along the pultrusion direction, and the roughness Ra of the middle section is 1.0~2.0μm; Neither the front nor the rear section has the microgrooves. The front section is a tapered flow channel, the roughness Ra of the rear section is 0.5~1.0μm, and the inner surface of the rear section is provided with a 3~6μm PTFE coating.

3. The injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles with reduced resin retention at the mold interface according to claim 2, characterized in that, The depth of the microgrooves in the middle section is 1~5μm, the width is 5~20μm, and the spacing is 10~50μm.

4. The injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles with reduced resin retention at the mold interface according to claim 1, characterized in that, The traction speed of the glass fiber is 0.6~0.8m / min, and the mold cavity pressure is 1.5~2.0MPa.

5. The injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles with reduced resin retention at the mold interface according to claim 1, characterized in that, The glass fiber accounts for 60-70 vol% of the volume of the glass fiber reinforced polyurethane profile.

6. The injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles with reduced resin retention at the mold interface according to claim 1, characterized in that, The syringe also includes a premixer C, which is located after the syringe A and syringe B. Components A and B are mixed in the premixer C to form a polyurethane material before entering the molding die. The syringe A, syringe B and premixer C are heat-insulated so that the temperature of the polyurethane material is 20~30°C when it is impregnated with the glass fiber.

7. The injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles with reduced resin retention at the mold interface according to claim 1, characterized in that, The liquefied MDI is polymethylene polyphenyl isocyanate; The siloxane-modified polyol is a hydroxyl-terminated polydimethylsiloxane; The fluorinated polyether polyol is a perfluorinated polyether diol; The nonionic surfactant is an organosilicon surfactant.

8. The injection impregnation pultrusion molding process for glass fiber reinforced polyurethane profiles with reduced resin retention at the mold interface according to claim 1, characterized in that, Component B also includes 1 to 5 parts of nano-silica, wherein the nano-silica has a particle size of 300 to 500 nm.

9. The glass fiber reinforced polyurethane composite profile prepared by the injection impregnation pultrusion molding process for reducing resin retention at the mold interface as described in any one of claims 1 to 8.

10. The application of the glass fiber reinforced polyurethane composite profile as described in claim 9 in building door and window products.

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