Glass fiber reinforced polyolefin material and preparation method thereof

Abstract

The invention discloses a glass fiber reinforced polyolefin material and a preparation method thereof, and belongs to the field of high polymer materials. The material is composed of polypropylene, regenerated glass fiber subjected to surface modification by an impregnating compound and an auxiliary agent. The impregnating compound is designed according to the surface characteristics of the glass fiber solid waste and comprises the following components: 3-8 parts of a compound coupling agent, 1-5 parts of a composite film-forming agent, 0.5-2 parts of a lubricant, 0.1-0.5 part of an antistatic agent, 0.01-0.5 part of a pH regulator and 80-95 parts of deionized water. The problem of poor interfacial compatibility of the glass fiber solid waste and the polypropylene matrix is effectively solved, the mechanical property of the prepared composite material is improved by more than two times compared with that of a material using untreated glass fiber solid waste, the performance of the composite material can reach more than 95% of that of a raw glass fiber material, high-value utilization of the solid waste is realized, and the composite material has remarkable environmental protection and economic benefits.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high polymer materials, and particularly relates to a glass fiber reinforced polyolefin material and a preparation method thereof. BACKGROUND

[0002] Glass fiber is widely used as a reinforcing phase of composite materials due to its high strength, high modulus and excellent thermal stability. However, a large amount of glass fiber solid waste (hereinafter referred to as "glass fiber solid waste") is generated in the production process of glass fiber and the processing process of downstream composite products, including broken ends, loose threads, unqualified products and offcuts. At present, the mainstream treatment method for these glass fiber solid waste is landfill or stacking. This treatment method not only occupies a large amount of land resources and has environmental risks, but also is a serious waste of valuable inorganic non-metallic reinforcing materials, which is not in line with the "double carbon" target and circular economy development policy vigorously promoted by the country.

[0003] In the prior art, there is an attempt to simply crush the glass fiber solid waste and directly use it as a filler or reinforcing material of a polymer-based composite material. However, this method has little effect and has a fundamental technical bottleneck: first, the original infiltration agent on the surface of the glass fiber solid waste, which is intended to combine with a specific resin, has been deactivated, decomposed or unevenly remained after the initial processing; second, its surface is inevitably contaminated with oil stains, has microcracks and other physical defects during production and recycling, and is accompanied by some solidified residual resin. These factors together result in poor interfacial bonding between the glass fiber solid waste, especially with a non-polar polyolefin (such as polypropylene) matrix. The composite material prepared directly using such recycled glass fiber often has serious phase separation, resulting in a sharp drop in its mechanical properties (such as tensile strength, bending strength and impact toughness) compared to the material using virgin glass fiber, which cannot meet the basic requirements of materials performance in the fields of automobiles, home appliances and the like.

[0004] It is generally recognized in the industry that effective surface modification of recycled glass fiber is the key to improving its interfacial bonding with resin. However, the current conventional surface treatment technology (especially the silane coupling agent treatment method) is mainly designed for virgin glass fiber with clean surface and high chemical activity. For glass fiber solid waste with complex surface chemical state, shielded or reduced active hydroxyl sites and physical damage, the traditional single-component coupling agent is difficult to effectively cover and bond to its heterogeneous surface, and the modification effect is limited, which cannot fundamentally repair the surface defects and rebuild a firm interfacial layer.

[0005] In summary, the prior art lacks a surface modification technology and a dedicated material system that is specifically targeted at the surface characteristics of glass fiber solid waste, can systematically repair its physical defects, and restore and enhance its interfacial bonding strength with a polyolefin matrix. Therefore, developing an efficient glass fiber solid waste resurfacing modification technology and the corresponding composite material preparation process to realize the high-value utilization of solid waste has become a core problem that needs to be solved in the field, with significant environmental value and economic benefits. SUMMARY

[0006] The purpose of the present application is to provide a glass fiber reinforced polyolefin material and a preparation method thereof. The core purpose is to restore or even enhance the surface activity of glass fiber solid waste through a dedicated sizing agent system and a supporting process, so that it can achieve the same reinforcing effect as virgin glass fiber when it is compounded with polypropylene.

[0007] The specific technical solutions to achieve the above-mentioned purposes of the application are as follows: In a first aspect, the present application provides a sizing agent for resurfacing of glass fiber solid waste, characterized in that it is composed of the following components by weight: 3-8 parts of a compounded coupling agent, 1-5 parts of a composite film forming agent, 0.5-2 parts of a lubricant, 0.1-0.5 parts of an antistatic agent, 0.01-0.5 parts of a pH adjuster, 80-95 parts of deionized water; wherein the amount of the pH adjuster is to adjust the deionized water to an acidic aqueous solution with a pH value of 4-6 to promote the hydrolysis of the compounded coupling agent; the compounded coupling agent is a compound of amino silane coupling agent and epoxy silane coupling agent, and the weight ratio of the amino silane coupling agent to the epoxy silane coupling agent is 1:1 to 1:2; the composite film forming agent is a compound of water-based epoxy resin emulsion and POE-g-MAH, and the weight ratio of the water-based epoxy resin emulsion to the POE-g-MAH is 2:1 to 3:1; the molecular weight of the water-based epoxy resin emulsion is 1000-3000.

[0008] Preferably, the amino silane coupling agent is KH-550.

[0009] Preferably, the epoxy silane coupling agent is KH-560.

[0010] Preferably, the water-based epoxy resin emulsion is a cationic water-based epoxy resin emulsion.

[0011] The complex coupling agent is a bidirectional bonding complex coupling agent, which strengthens the chemical combination of the interface. In view of the problem of few active sites of glass fiber solid waste, the traditional single coupling agent is abandoned, and a KH-550 and KH-560 complex system is adopted to construct a "glass fiber-coupling agent-matrix" bidirectional covalent bond network: the amino group (-NH2) of KH-550 reacts with the hydroxyl group (-OH) of the residual resin on the surface of the solid waste first, and occupies the surface site of the residual resin; the epoxy group (-C2H3O) of KH-560 is crosslinked with the carboxyl group (-COOH) of the polypropylene grafted maleic anhydride, and the silicon hydroxyl groups (-SiOH) generated by the hydrolysis of the two are all formed into Si-O-Si covalent bonds with the hydroxyl groups on the surface of the glass fiber; through precise pH control (4-6), the complete hydrolysis rate of the coupling agent is more than 95%, which is 30% higher than that of natural hydrolysis, and interface defects caused by premature polymerization are avoided. This design solves the defect that the traditional single-component coupling agent can only be combined in one direction, and the interface bonding strength is close to the level of the original glass fiber.

[0012] The composite film forming agent is a targeted repair type composite film forming agent system, which breaks through the bottleneck of repairing physical defects of solid waste. Different from the limitation of the single film forming agent in the prior art which can only form a protective film, the present application innovatively uses a "water-based epoxy emulsion + POE-g-MAH" composite film forming agent to realize double repair of the surface micro-cracks and residual resin defects of the glass fiber solid waste: the water-based epoxy emulsion has a low molecular weight (1000-3000) and can penetrate into the micro-cracks with a depth of ≥5 μm, and after curing, a rigid support structure is formed to fill the crack defects, so that the recovery rate of the tensile strength of the glass fiber is improved to more than 85% (the traditional scheme is only 60%-70%); the maleic anhydride groups in POE-g-MAH can react with the hydroxyl groups of the residual resin to form chemical bonds, and the polyolefin segment is compatible with the matrix resin, solving the interface bonding obstacle caused by the residual resin, and the interface shear strength is improved by 35% compared with the system without POE-g-MAH. The design of the composite film forming agent is different from the nano-modified film forming agent of CN202011417761.9 (aiming at the strength improvement of the original glass fiber) and the three-component epoxy film forming agent of CN202311140224.8 (aiming at the aging resistance requirement), and is a customized solution specially for the defect repair of glass fiber solid waste.

[0013] In a second aspect, the present application provides a preparation method of the infiltration agent, comprising the following steps: Under stirring conditions, slowly add the silane coupling agent into the acidic aqueous solution prepared from deionized water and a pH adjuster, and perform pre-hydrolysis, and continuously stir for 30-60 minutes; Add the composite film forming agent, the lubricant and the antistatic agent in sequence, and stir after adding each component to mix uniformly.

[0014] Preferably, each component is stirred for 10-15 minutes after being added to ensure uniform mixing.

[0015] In a third aspect, the present application provides a method for resurfacing waste glass fiber, comprising the following steps: a) Pretreatment: sorting and pre-cutting the waste glass fiber into glass fibers with a length of 20-30 cm; b) Surface modification: using the sizing agent as claimed in claim 1 to uniformly coat the surface of the glass fibers obtained in step a); The glass fibers are continuously fed into a surface modification treatment equipment, which includes a closed cavity with a high-speed vortex spraying system and a high-temperature airflow drying system. The prepared sizing agent is uniformly atomized and sprayed onto the surface of the glass fibers in a suspended and dispersed state through the spraying system.

[0016] c) Cutting: cutting the coated glass fibers of step b) to obtain chopped glass fibers; d) Drying and curing: drying and curing the chopped glass fibers prepared in step c), and obtaining regenerated glass fibers after cooling.

[0017] Preferably, the coating in step b) is carried out by atomization spraying.

[0018] Preferably, in step b), the coating amount of the sizing agent is controlled so that the combustible content of the coated glass fibers is 0.48wt% to 0.6wt%.

[0019] Preferably, in step c), the length of the chopped glass fibers is 3.5-4.5mm.

[0020] Preferably, in step d), the drying and curing temperature is 120-180°C, and the time is 1-3 minutes.

[0021] In a fourth aspect, the present application provides a regenerated glass fiber prepared according to the resurfacing method.

[0022] In a fifth aspect, the present application provides a glass fiber reinforced polyolefin material prepared from the following weight percentages of raw materials: Polyolefin 62-81.4%, Said regenerated glass fiber 15-30%, Polypropylene grafted maleic anhydride 3-8%, Antioxidant 0.1-0.5%, Calcium stearate 0.5-2%.

[0023] Preferably, the polyolefin is polypropylene.

[0024] In a sixth aspect, the present application provides a method for preparing the glass fiber reinforced polyolefin material, comprising the following steps: mixing raw materials, melt blending, extruding, cooling and granulating through a double screw extruder to obtain the glass fiber reinforced polyolefin material.

[0025] Preferably, a high-speed mixer is used to mix the raw materials; the extrusion temperature of the double screw extruder is 180-220°C.

[0026] The technical principle of the present application is that: 1. Surface defect repair principle The microcracks and residual resin on the surface of glass fiber waste are the core inducements leading to performance degradation. In the present application, the composite film-forming agent plays a triple role of "penetration - filling - bonding": the low molecular weight water-based epoxy emulsion enters the microcracks by the penetration force of atomization spraying, and crosslinking reaction occurs during the hot air curing process to form a rigid resin phase, achieving physical filling of the cracks; POE-g-MAH esterifies the hydroxyl groups of the residual resin through the maleic anhydride groups, converting the inert residual layer into an active transition layer, and its polyolefin chain segment forms intermolecular forces with the matrix, eliminating the interface barrier effect of residual resin; the film-forming agent and coupling agent form a "coupling agent - film-forming agent" composite coating on the surface of glass fiber through intermolecular hydrogen bonding, repairing physical defects and building a chemical bonding basis.

[0027] 2. Interface enhancement principle Based on the "chemical bond theory" and "intermolecular force theory", a multi-level interface bonding system is constructed: bottom layer bonding: condensation reaction occurs between the silicon hydroxyl groups generated by the hydrolysis of the composite coupling agent and the hydroxyl groups on the surface of the glass fiber, forming Si-O-Si covalent bonds, which constitute the chemical basis of interface bonding; middle layer transition: the organic functional groups (amino, epoxy) of the coupling agent react with the active groups of the film-forming agent and the carboxyl groups of the compatibilizer, respectively, forming a crosslinked network to enhance the cohesion of the coating; top layer bonding: the POE-g-MAH chain segment in the film-forming agent and the compatibilizer (polypropylene grafted maleic anhydride) are combined with the polyolefin matrix through molecular entanglement and compatibility, achieving efficient connection between inorganic glass fiber and organic matrix. This multi-level bonding system increases the interface shear strength from 18 MPa to 28 MPa, close to that of virgin glass fiber (30 MPa).

[0028] 3. Processing synergy principle Functional additives and equipment design form process synergy: Antistatic agent reduces the surface resistivity of glass fiber, avoiding electrostatic agglomeration during suspension spraying and extrusion, ensuring uniform coating of the wetting agent and dispersion of the fiber; The lubricant improves the lubricity of the fiber, cooperates with the high-speed vortex suspension system of special equipment, makes the coating uniformity reach 98%, and reduces the shear damage in the double-screw extrusion; Synchronous cutting-curing process shortens the modification period (from 60min to 3min), avoids moisture absorption and coating aging caused by long-time storage of the fiber, and ensures batch stability.

[0029] Compared with the prior art, the present application has the following beneficial effects: 1. High value of solid waste: the recovery rate of the mechanical properties of the glass fiber solid waste is more than 95%, the tensile strength of the modified glass fiber reinforced polyolefin material reaches 100MPa, which is 2.8 times of the untreated solid waste, and is close to the level of virgin glass fiber composite material; 2. Significant cost advantage: the raw material cost of the infiltrant is reduced by 40% compared with the high-end virgin glass fiber infiltrant, and the overall cost of the composite material is reduced by 20%-30% due to the recycling of the solid waste; 3. Environmental protection and performance: the solid waste is recycled, the landfill pollution is reduced, the mechanical properties and processing performance of the composite material meet the requirements of the automobile and household appliance fields, and the floating fiber defect is significantly improved; 4. High industrialization feasibility: the modification process is compatible with the existing extrusion equipment, without the need for large-scale modification, the efficiency of the spraying-cutting-curing integrated equipment is improved by 20 times, and it is suitable for batch production. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present application, the present application will be described more fully below. The present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not used to limit the present application. The term "and / or" used in the present application includes any and all combinations of one or more related listed items.

[0031] The raw materials used in the embodiments of the present application are as follows: Solid waste glass fiber: the recovered glass fiber is derived from the solid waste after use, and the brand is ORINKOECS-04-866; Virgin alkali-free glass fiber: giant stone 508A; Cationic water-based epoxy resin emulsion: Jida Chemical H119, molecular weight 1500g / mol; POE-g-MAH: Jia Yirong SOG-03; Lubricant: Dow Corning MB50-001; Antistatic agent: Rhodiasolv ATMER 129; pH regulator: Wacker BS168; Polypropylene: Sinopec S1003; Compatibilizer: polypropylene grafted maleic anhydride, Kao Tong KT-1; Antioxidant: antioxidant 1010, BASF; Calcium stearate, Hanwei Technology CV500.

[0032] Example 1: Preparation of special infiltrant In a container equipped with a stirrer, 90 parts of deionized water were added, and the pH was adjusted to 5.0 with acetic acid. Under high-speed stirring, 4 parts of a compounded coupling agent obtained by compounding KH-550 and KH-560 at a mass ratio of 1:1 was slowly added, and the hydrolysis was continued for 40 minutes. Then 2 parts of a composite film-forming agent obtained by compounding water-based epoxy resin emulsion and POE-g-MAH at a ratio of 3:1, 1 part of polyethylene wax emulsion (lubricant), and 0.2 parts of antistatic agent were added in sequence, and each was stirred for 15 minutes to obtain a uniform and stable special infiltrant.

[0033] Example 2: Preparation and modification of recycled glass fiber After washing and drying, the solid waste glass fiber was pre-cut into an average length of 20-30 cm, and was continuously fed into the surface modification equipment. The infiltrant prepared in Example 1 was uniformly sprayed on the surface of the suspended and dispersed glass fiber in the form of atomization. By adjusting the liquid spraying rate of the atomization spraying system and the glass fiber conveying speed, the amount of infiltrant adhered to the surface of the glass fiber reached the predetermined target. The combustible content of the obtained recycled glass fiber was 0.52% confirmed by sampling and thermogravimetric analysis, and then the glass fiber was sheared into a length of 3.5-4.5 mm, and was fed into a drying bed by a conveyor belt, and was treated in hot air at 150°C for 2 minutes, and then cooled to obtain the surface-modified recycled glass fiber.

[0034] Example 3: Preparation of environmentally friendly reinforced polypropylene composite material The raw materials were prepared in the following weight percentages: polypropylene 65%, recycled glass fiber obtained in Example 2 30%, compatibilizer 5%, antioxidant 1010 0.3%, and calcium stearate 0.7%. All the raw materials were mixed in a high-speed mixer for 3 minutes, and then were melt-extruded, cooled, and pelletized in a co-rotating twin-screw extruder (length-diameter ratio 40:1) at a processing temperature of 185-210°C to obtain an environmentally friendly reinforced polypropylene composite material.

[0035] Comparative Example 1 Compared with Example 3, the difference is that the same specification glass fiber waste, i.e. the solid waste glass fiber is cut into 3.5-4.5 mm in length after being washed and dried, is used without any surface modification treatment. The rest of the raw materials and the preparation process are exactly the same.

[0036] Comparative Example 2 Compared with Example 3, the difference is that the same amount of virgin alkali-free glass fiber (the glass fiber is treated with a conventional silane coupling agent before leaving the factory) with a length of 3.5-4.5 mm is used. The rest of the raw materials and the preparation process are exactly the same.

[0037] Performance test and results The particles obtained in Example 3 and Comparative Examples 1 and 2 are injection molded into standard test bars, and their mechanical properties are tested according to national standards, and the results are shown in Table 1.

[0038] Table 1

[0039] Conclusion: From the above data, it can be seen that the performance of the material prepared in Example 3 of the present application is far superior to the untreated control sample (Comparative Example 1), and the tensile, bending and impact strengths are all increased by more than 2 times. At the same time, its performance reaches more than 95% of the use of virgin glass fiber material (Comparative Example 2), and the specific data is: the tensile strength is 95.2%, the bending strength is 97.8%, and the impact strength is 95.6%, fully proving the effectiveness and advancement of the present application.

[0040] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which are all within the scope of the present application. Therefore, the scope of protection of the present application patent should be subject to the appended claims.

Claims

1. A wetting agent for surface modification of glass fiber solid waste, characterized in that, By weight, it consists of the following components: 3-8 doses of the couple's combination drug. 1-5 parts of composite film-forming agent, Lubricant 0.5-2 parts, 0.1-0.5 parts of antistatic agent, pH adjuster 0.01-0.5 parts, 80-95 parts deionized water; The amount of pH adjuster used is such that the deionized water is adjusted to an acidic aqueous solution with a pH of 4-6 to promote the hydrolysis of the complex coupler. The complex coupling agent is a mixture of an aminosilane coupling agent and an epoxysilane coupling agent, wherein the weight ratio of the aminosilane coupling agent to the epoxysilane coupling agent is 1:1 to 1:

2. The composite film-forming agent is a mixture of aqueous epoxy resin emulsion and POE-g-MAH, wherein the weight ratio of the aqueous epoxy resin emulsion to the POE-g-MAH is 2:1 to 3:

1. The molecular weight of the aqueous epoxy resin emulsion is 1000-3000.

2. A method for preparing the wetting agent as described in claim 1, characterized in that, Includes the following steps: Under stirring conditions, the complex coupler is slowly added to an acidic aqueous solution prepared with deionized water and a pH adjuster for pre-hydrolysis, and stirring is continued for 30-60 minutes. The composite film-forming agent, lubricant, and antistatic agent are added sequentially, and the mixture is stirred after each component is added until homogeneous.

3. A method for resurfacing glass fiber solid waste, characterized in that, Includes the following steps: a) Pretreatment: The glass fiber solid waste is sorted and pre-cut into glass fibers with a length of 20-30cm; b) Surface modification: Using the wetting agent as described in claim 1, uniformly coat the glass fiber surface obtained in step a); c) Cutting: Cut the glass fiber coated in step b) to obtain chopped glass fiber; d) Drying and curing: The chopped glass fibers prepared in step c) are dried and cured, and then cooled to obtain regenerated glass fibers.

4. The resurfacing modification method according to claim 3, characterized in that, In step b), the coating is performed using atomized spraying; in step c), the length of the chopped glass fiber is 3.5-4.5 mm; in step d), the drying and curing temperature is 120-180°C and the time is 1-3 minutes.

5. The resurfacing modification method according to claim 3, characterized in that, In step b), the coating amount of the sizing agent is controlled so that the combustible content of the coated glass fiber is 0.48wt% to 0.6wt%.

6. A type of recycled glass fiber, characterized in that, Prepared by the resurfacing modification method according to any one of claims 3-5.

7. A glass fiber reinforced polyolefin material, characterized in that, It consists of the following raw materials by weight percentage: Polyolefins 62-81.4%, The recycled glass fiber as described in claim 6 comprises 15-30%. Polypropylene grafted with 3-8% maleic anhydride Antioxidant 0.1-0.5%, Calcium stearate 0.5-2%.

8. The glass fiber reinforced polyolefin material according to claim 7, characterized in that, The polyolefin is polypropylene.

9. A method for preparing the glass fiber reinforced polyolefin material as described in claim 7 or 8, characterized in that, Includes the following steps: After mixing the raw materials, the mixture is melt-blended, extruded, cooled, and pelletized using a twin-screw extruder to obtain the glass fiber reinforced polyolefin material.

10. The preparation method according to claim 9, characterized in that, The raw materials are mixed using a high-speed mixer; the extrusion temperature of the twin-screw extruder is 180-220°C.

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