Creep resistant glass fiber sizing and method of making same

Abstract

The present application belongs to the technical field of glass fiber sizing agent, and particularly relates to an anti-creep glass fiber sizing agent and a preparation method thereof. The anti-creep glass fiber sizing agent comprises effective components and water, and the solid content of the anti-creep glass fiber sizing agent is 3-12%. The effective components comprise the following components according to weight percentage: maleic anhydride modified long-chain branched polyolefin wax 65.5-86.9 wt.%, coupling agent 5-10 wt.%, nucleating agent 1-8 wt.%, physical cross-linking component 5-12 wt.%, initiator 0.1-0.5 wt.%, and surfactant 2-4 wt.%. The present application can effectively solve the problem of insufficient anti-creep ability of the glass fiber reinforced polypropylene material in the prior art, and at the same time, the material has good mechanical properties and fatigue resistance, which plays an important role in improving the long-term dimensional stability of the polypropylene material.

Description

Technical Field

[0001] This invention belongs to the field of glass fiber sizing agent technology, specifically relating to an anti-creep glass fiber sizing agent and its preparation method. Background Technology

[0002] Polypropylene resin is one of the five major general-purpose plastics and is also one of the most widely used plastics in terms of both quantity and application. Because polypropylene molecules contain side methyl groups, they can be classified into atactic polypropylene, syndiotactic polypropylene, and isotactic polypropylene based on the arrangement of these side methyl groups on both sides of the molecular backbone. In most industries, the polypropylene resin used primarily refers to isotactic polypropylene, which has a regular molecular structure. This type of polypropylene has excellent crystallinity, and therefore often achieves higher mechanical properties and rigidity during use.

[0003] Although isomeric polypropylene has good crystallinity (around 70%), the polymer is difficult to fully crystallize. A significant amount of amorphous regions (also known as non-crystalline regions) exist within the polypropylene matrix. Under constant external force and during internal stress relaxation, these non-crystalline regions cause irreversible deformation and displacement of the polypropylene molecular chains. Macroscopically, this manifests as irreversible deformation, or creep, in components made from polypropylene. In fields requiring precise dimensional fits (such as the automotive and electronics industries), these irreversible deformations severely impact product performance. Furthermore, the rate of irreversible deformation in polypropylene increases rapidly with time, ambient temperature, and external stress. Creep makes it difficult for polypropylene to maintain good dimensional stability under continuous stress. Even with modifications and reinforcements such as glass fiber, the creep resistance of polypropylene cannot be effectively improved, significantly limiting its application in fields with stringent long-term dimensional requirements.

[0004] Chinese patent CN113549291A discloses a creep-resistant polypropylene, its preparation method, and a plastic tray. The creep-resistant polypropylene is made from the following raw materials in parts by weight: 45-76 parts polypropylene, 3-8 parts maleic anhydride, 1-4 parts initiator, 0.8-2 parts polytetrafluoroethylene particles, 0.02-0.2 parts 2,2,6,6-tetramethyl-1-(1-phenylethoxy)piperidine, 11-23 parts glass fiber, 1-3 parts dispersant, and 13-21 parts creep-resistant modifier; the creep-resistant modifier is composed of barium sulfate, carbonate, and carbon black in a weight ratio of 1-3:4-7:2-3. A creep-resistant polypropylene material sample with dimensions of 120×10×4mm prepared by this method, under a test temperature of 23℃ and a stress of 23MPa, showed a creep deformation of 5.5-7.5% in the outermost layer after 48 hours. The patented method for improving the creep resistance of polypropylene is mainly through the addition of inorganic fillers. The resulting polypropylene material is used in the pallet industry, but its creep resistance is still relatively high. The creep resistance performance cannot meet the requirements of the current automotive, electronics and electrical appliance industries for long-term dimensional stability of materials. In addition, the filler contains carbon black, which has a serious impact on the color.

[0005] Chinese patent CN105504500A discloses a creep-resistant polypropylene composite material and its preparation method. The creep-resistant polypropylene composite material is composed of the following raw materials by weight percentage: homopolymer polypropylene 0-65%, copolymer polypropylene 30-95%, toughening agent 0-20%, inorganic filler 0-40%, cooling masterbatch 0.3-2%, stabilizer 0.2-2%, and other additives 0-5%. The cooling masterbatch is a peroxide masterbatch for the polypropylene carrier. A creep-resistant polypropylene material sample with dimensions of 120×10×4mm prepared by this method, under a test temperature of 23℃ and a stress of 30MPa, showed a creep deformation of 1.6-3.5% in the outermost layer after 48 hours. This patent uses cooling masterbatch as a way to improve the creep resistance of polypropylene. The peroxide in the cooling masterbatch randomly initiates the generation of free radicals in the polypropylene molecular chains, thereby reacting and cross-linking. The cross-linked polypropylene, due to the formation of a chemical bond cross-linking network, restricts the movement of the molecular chains, thus reducing the creep of the polypropylene material and playing a creep-resistant role. However, this patent has the following shortcomings: 1. The peroxide crosslinking agent has high activity and will remove hydrogen from saturated molecules during the crosslinking process, causing the polypropylene to undergo a high degree of crosslinking, which is not conducive to the recycling of materials. At the same time, the product will emit a strong pungent odor after the peroxide crosslinking agent is used; 2. The creep resistance of polypropylene improved by peroxide and inorganic reinforcing fillers alone is still insufficient to meet current usage requirements; 3. The addition of toughening agents will increase the deformation ability of polypropylene composites, resulting in a decrease in creep resistance.

[0006] In summary, the creep resistance modification of polypropylene is usually achieved by adding nucleating agents, crosslinking agents and other additives to prepare composite materials. There are a variety of additives added during the preparation process, and the raw material preparation and preparation process are cumbersome. Moreover, the creep resistance of the modified polypropylene is still insufficient to meet the requirements of high dimensional stability. Currently, the glass fiber industry is facing the development transformation of functionalization and refinement. Glass fibers can be evenly dispersed in the resin matrix, and through the formulation design of the sizing agent, it can become an excellent carrier for improving the various properties of polypropylene materials. Summary of the Invention

[0007] The purpose of the present invention is to provide a creep-resistant glass fiber sizing agent, which can effectively solve the problem of insufficient creep resistance of glass fiber reinforced polypropylene materials in the prior art, and at the same time endow the materials with good mechanical properties and fatigue resistance, which plays an important role in improving the long-term dimensional stability of polypropylene materials and has great significance in promoting the application and development of polypropylene materials; the present invention also provides a preparation method of the creep-resistant glass fiber sizing agent.

[0008] The creep-resistant glass fiber sizing agent described in the present invention includes active components and water, and the solid content of the creep-resistant glass fiber sizing agent is 3-12%; the active components are calculated by weight percentage and include the following components:

[0009] Maleic anhydride modified long-chain branched polyolefin wax 65.5-86.9wt.%

[0010] Coupling agent 5-10wt.%

[0011] Nucleating agent 1-8wt.%

[0012] Physical crosslinking component 5-12wt.%

[0013] Initiator 0.1-0.5wt.%

[0014] Surfactant 2-4wt.%.

[0015] The maleic anhydride modified long-chain branched polyolefin wax is maleic anhydride modified long-chain branched polypropylene wax or maleic anhydride modified long-chain branched polyethylene wax.

[0016] The maleic anhydride modified long-chain branched polyolefin wax is a graft-modified polymer obtained by graft modification of highly branched polypropylene or polyethylene with long branched chains with maleic anhydride.

[0017] The relative molecular weight of the maleic anhydride modified long-chain branched polyolefin wax is 2000-50000, and the maleic anhydride grafting rate of the maleic anhydride modified long-chain branched polyolefin wax is 0.8-1.5%.

[0018] The maleic anhydride modified long-chain branched polyolefin wax is made from raw materials with the following weight percentages:

[0019] Long-chain branched polyolefin wax 93.5 - 97.9 wt.%

[0020] Maleic anhydride 2 - 6 wt.%

[0021] Dicumyl peroxide 0.1 - 0.5 wt.%.

[0022] The preparation method of the maleic anhydride modified long-chain branched polyolefin wax includes the following steps:

[0023] (1) Mix maleic anhydride and dicumyl peroxide (DCP), and completely dissolve them with acetone to obtain a mixed solution;

[0024] (2) Heat and stir the mixed solution with the long-chain branched polyolefin wax to obtain a mixture;

[0025] (3) Add the mixture to a twin-screw extruder for melt blending and pelletizing to obtain the maleic anhydride modified long-chain branched polyolefin wax.

[0026] The heating and stirring time in step (2) is 5 - 10 min, and the heating and stirring temperature is 80 - 110 °C. [[ID=2,6]]

[0027] The temperatures of the barrels of the twin-screw extruder from the feeding port to the head in step (3) are 160 - 175 °C, 170 - 185 °C, 170 - 190 °C, 170 - 190 °C, 170 - 190 °C, 170 - 190 °C, 170 - 190 °C, 180 - 200 °C, 180 - 200 °C, 180 - 205 °C respectively, the screw speed is 200 - 400 revolutions per minute, the feeding rate is 10 - 200 kg / h, and the vacuum degree is -0.1 - 0 MPa.

[0028] The coupling agent includes vinyl silane coupling agents.

[0029] The coupling agent also includes one or more of acryloxy silane coupling agents, epoxy silane coupling agents, amino silane coupling agents or long-chain alkyl silane coupling agents.

[0030] The vinyl silane coupling agent is one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, vinyltris(β-methoxyvinyl)silane, vinyltri-tert-butoxysilane, vinyltri-tert-butylperoxysilane, vinyltriacetoxysilane or styreneethyltrimethoxysilane. [[ID=3,8]]

[0031] The acryloyloxysilane coupling agent is one of γ-(acryloyloxy)propyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, γ-(methacryloyloxy)propyltriethoxysilane or γ-(methacryloyloxy)propyltriisopropoxysilane.

[0032] The epoxy silane coupling agent is one of γ-(epoxypropoxy)propyltrimethoxysilane, γ-(epoxypropoxy)propyldimethoxysilane, γ-(epoxypropoxy)propyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, or β-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

[0033] The aminosilane coupling agent is one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, p-aminophenyltrimethoxysilane, m-aminophenyltrimethoxysilane, γ-aminopropyltris(methoxyethoxyethoxy)silane, or γ-aminopropyldimethoxyethoxysilane.

[0034] The long alkyl silane coupling agent is one of dodecyltrimethoxysilane, dodecyltriethoxysilane, dodecylmethyldimethoxysilane, hexadecyltrimethoxysilane, or octadecyltrimethoxysilane.

[0035] The nucleating agent is one or more of sodium fluoroborate, ammonium fluoroborate, potassium fluoroborate, sodium glutarate, lithium benzoate, sodium cinnamate, sodium β-naphthoate, phosphate metal salt, sorbitol benzylidene derivative, dibenzylidene sorbitol (DBS), or di(p-methylbenzylidene)sorbitol (PM-DBS).

[0036] The physical crosslinking component is one or more of SBS, SEBS, or SEEPS, preferably SBS.

[0037] The initiator is an azo initiator, preferably one or more of AIBN, ABVN, CABN, ACCN, or AIBME.

[0038] The surfactant is one or more of anionic surfactants, cationic surfactants, nonionic surfactants, or amphoteric surfactants.

[0039] The anionic surfactant is one of alkylbenzene sulfonate, alkyl sulfonate salt, alkyl sulfonate, alkyl sulfate, fluorinated fatty acid salt, polysiloxane, fatty alcohol sulfate, fatty alcohol polyoxyethylene ether sulfate, α-alkenyl sulfonate, fatty alcohol polyoxyethylene ether phosphate, alkylolamide, alkyl sulfonate acetamide, alkyl succinate sulfonate, alkanolamine alkylbenzene sulfonate, naphthenate, alkylphenol sulfonate, or polyoxyethylene monolaurate.

[0040] The cationic surfactant is one of hexadecyl dimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, cationic guar gum, cationic panthenol, cationic silicone oil, or dodecyl dimethylamine oxide.

[0041] The nonionic surfactant is one of polyoxyethylene (9) nonylphenyl ether, alkyl alcohol amide, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, C13 isopropanol amide, essential oil emulsifier or secondary alcohol.

[0042] The zwitterionic surfactant is one of dodecyl dimethyl betaine, carboxylate imidazoline, or organic amine ester.

[0043] The preparation method of the anti-creep glass fiber impregnating agent of the present invention includes the following steps:

[0044] (1) Prepare a coupling agent solution by mixing the coupling agent with water;

[0045] (2) Maleic anhydride-modified long-chain branched polyolefin wax, physical crosslinking components, surfactants and water are stirred and reacted. After the reaction is completed, the mixture is immediately quenched with cold water to obtain a mixed wax emulsion.

[0046] (3) The nucleating agent and the initiator are diluted with water and then mixed to obtain a diluted solution;

[0047] (4) Mix the mixed wax emulsion, diluent and coupling agent solution, then add the remaining water and stir to obtain the anti-creep glass fiber impregnating agent.

[0048] The mass ratio of the coupling agent to water in step (1) is 1:10-50, and the water temperature is 23-30℃.

[0049] The mass ratio of maleic anhydride-modified long-chain branched polyolefin wax to water in step (2) is 1:10-100.

[0050] The stirring reaction temperature in step (2) is 170-200℃, the stirring reaction pressure is 7-9 atm, the stirring reaction speed is 50-100 rpm, and the stirring reaction time is 30-45 min.

[0051] The dilution ratio mentioned in step (3) is 10-100 times, and the water temperature is 23-30℃.

[0052] The mixing speed described in step (4) is 50-100 rpm.

[0053] Glass fibers produced by coating with the anti-creep glass fiber impregnating agent of the present invention can be used in reinforced polypropylene resin composites.

[0054] The mechanism of action of glass fibers produced by coating with the anti-creep glass fiber impregnating agent of the present invention within the polypropylene matrix is ​​described below. Figure 1 After polypropylene 1 is reinforced with glass fiber 2 produced by coating with the anti-creep glass fiber sizing agent of the present invention, the following interactions exist to improve its mechanical properties, creep resistance, and fatigue resistance: the long branches of maleic anhydride modified long-chain branched polyolefin wax 3 are entangled with the molecular chains of polypropylene 1 and participate in the crystallization of polypropylene 1, effectively restricting the movement of molecular chains and improving the mechanical properties, creep resistance, and fatigue resistance of the material; the hard segments 4 of polystyrene in the physical crosslinking component, due to their large molecular volume and poor mobility, anchor the glass fiber 2 in the polypropylene 1 matrix, while the soft segments 5 act as a connector between the glass fiber 2 and polypropylene 1, and the unsaturated bonds 6 on the soft segments 5 undergo chemical crosslinking with polypropylene 1 under the action of the initiator, ultimately improving the mechanical properties, creep resistance, and fatigue resistance of the material; the unsaturated bonds in the vinyl silane coupling agent 7 also undergo chemical crosslinking with polypropylene 1 under the action of the initiator.

[0055] The combustible content (i.e., the percentage of the amount of sizing agent coated on the glass fiber to the mass of the glass fiber) of the glass fiber prepared by this invention is generally controlled at 0.4-0.7%. The combustible content should not be too high, otherwise it will not be conducive to the dispersion of the glass fiber bundles, thus affecting the subsequent wetting with resin; if it is too low, the protective effect will be reduced, it will not be wear-resistant, and the mechanical properties will also be difficult to meet the requirements.

[0056] The beneficial effects of this invention are as follows:

[0057] (1) This invention uses maleic anhydride-modified long-chain branched polyolefin wax for molecular chain entanglement. The maleic anhydride-modified long-chain branched polyolefin wax acts as a film-forming agent in the glass fiber impregnating agent, which can effectively bond glass fiber monofilaments into bundles, reduce fuzz, and the highly branched molecular chains can form a high degree of physical entanglement with the polypropylene matrix and partially participate in polypropylene crystallization, increasing the bonding effect between the glass fiber and the surrounding polypropylene matrix, and ultimately playing a role in resisting deformation and resisting creep. The maleic anhydride-modified long-chain branched polyolefin wax can also increase the compatibility between polypropylene and glass fiber, and at the same time has the functions of molecular chain entanglement and compatibilization.

[0058] (2) The present invention uses physical crosslinking components such as SBS, SEBS and SEEPS to construct physical crosslinking points. The hard segment of the physical crosslinking component is polystyrene. The polystyrene molecular chain has weak mobility and can effectively fix the polypropylene matrix when the polypropylene undergoes creep, so that the glass fiber can anchor the polypropylene matrix through the hard segment of the physical crosslinking component, reduce the degree of creep and improve fatigue resistance.

[0059] (3) In this invention, a nucleating agent is added to regulate the crystallization state of polypropylene. The addition of the nucleating agent helps to induce crystallization of polypropylene during the processing and molding process, so that the crystallization state of polypropylene changes from large-sized spherulites to small-sized spherulites and increases the crystallinity, thereby increasing the proportion of crystalline part in polypropylene, and ultimately making the polypropylene material have higher creep resistance, mechanical properties and fatigue resistance.

[0060] (4) The present invention creates chemical bonding by initiating the reaction of unsaturated double bonds in coupling agent and physical crosslinking components through initiator. Compared with the prior art, which directly initiates the crosslinking of polypropylene as a whole, the present invention has a lower degree of crosslinking. However, by using glass fiber as a dispersion and reaction carrier, good anti-creep and fatigue resistance can be achieved with only a low degree of crosslinking.

[0061] (5) This invention does not use highly active peroxide crosslinking agents for chemical crosslinking. Instead, it only stimulates the components with unsaturated double bonds to generate free radicals and crosslink with the surrounding polypropylene matrix. This avoids the problem of excessive crosslinking, which makes the material difficult to recycle and reuse. At the same time, it avoids the irritating odor caused by the use of peroxide crosslinking agents, which is beneficial to expanding the application of the material in fields such as automotive interiors where environmental odor requirements are important.

[0062] (6) The nucleating agent used in this invention works synergistically with maleic anhydride-modified long-chain branched polyolefin wax to improve the degree of crystallization of maleic anhydride-modified long-chain branched polyolefin wax in polypropylene. Vinyl silane coupling agent and physical crosslinking component jointly participate in anchoring and restricting molecular motion, and the unsaturated double bonds in the physical crosslinking component also participate in chemical crosslinking, which can ultimately greatly improve the creep resistance of glass fiber to polypropylene material. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the mechanism of action of glass fiber produced by coating with the anti-creep glass fiber impregnating agent of the present invention in a polypropylene matrix. In the figure, 1 is polypropylene; 2 is glass fiber; 3 is maleic anhydride modified long-chain branched polyolefin wax; 4 is polystyrene hard segment; 5 is soft segment; 6 is unsaturated bond; and 7 is vinyl silane coupling agent. Detailed Implementation

[0064] The present invention will be further described below with reference to embodiments.

[0065] The raw materials used in the examples and comparative examples are as follows:

[0066] Long-chain branched polypropylene wax, WAYMAX EX6000 from Japan Polypropylene Corporation;

[0067] Polypropylene wax, BYK AG, Germany, AQUACER 593;

[0068] Maleic anhydride, Wuhan Jixin Yibang Biotechnology Co., Ltd.;

[0069] Vinyltrimethoxysilane, Momentive Advanced Materials Group, USA, A171;

[0070] Vinyltriethoxysilane, Momentive Advanced Materials Group, USA, A151;

[0071] Octadecyltrimethoxysilane, Hangzhou Jessica Chemical Co., Ltd. KH-1831;

[0072] γ-aminopropyltriethoxysilane, Momentive Advanced Materials Group A1100 (USA);

[0073] SBS, Dongguan Shenghao Plastic Raw Materials Co., Ltd. SH600;

[0074] SEEPS, Kuraray Corporation of Japan, SEPTON4044;

[0075] Ammonium fluoroborate, Shandong Kepler Biotechnology Co., Ltd., kpl57892;

[0076] Dibenzyl sorbitol, Chenghe Technology NA98;

[0077] Di(p-methylbenzyl)sorbitol, Hainan Chaoxinda Industrial Co., Ltd.;

[0078] AIBN, Shandong Chuangyi Chemical Co., Ltd.

[0079] AIBME, Tianmen Hengchang Chemical Co., Ltd. V601;

[0080] DCP, Wuhan Adomai New Energy Co., Ltd.

[0081] Polyoxyethylene (9) nonylphenyl ether, Solvay Group lgepalco630.

[0082] Examples 1-7

[0083] Maleic anhydride-modified long-chain branched polypropylene wax is made from the following raw materials by weight percentage:

[0084] Long-chain branched polypropylene wax 93.7 wt.%

[0085] Maleic anhydride 6 wt.%

[0086] 0.3 wt.% dicumyl peroxide

[0087] The preparation method of maleic anhydride modified long-chain branched polypropylene wax includes the following steps:

[0088] (1) Mix maleic anhydride with dicumyl peroxide and dissolve completely in acetone to obtain a mixture;

[0089] (2) Pour the mixture and long-chain branched polypropylene wax into a high-speed mixer, heat and stir at 90°C for 10 min to obtain the mixture;

[0090] (3) The mixture was added to a twin-screw extruder for melt blending and granulation to obtain maleic anhydride modified long-chain branched polypropylene wax with a relative molecular weight of 12,000 and a maleic anhydride grafting rate of 1.2%. The temperatures of each barrel from the feed port to the die head of the twin-screw extruder were 160℃, 170℃, 180℃, 190℃, 190℃, 190℃, 200℃, 200℃, and 205℃, respectively. The screw speed was 300 rpm, the feed rate was 20 kg / h, and the vacuum degree was -0.1 MPa.

[0091] The preparation method of the anti-creep glass fiber impregnating agent includes the following steps:

[0092] (1) Prepare a coupling agent solution with a mass ratio of coupling agent to water of 1:50 and a water temperature of 23℃;

[0093] (2) Maleic anhydride-modified long-chain branched polyolefin wax, physical crosslinking components, surfactants and water were added to a high-pressure reactor. The mass ratio of maleic anhydride-modified long-chain branched polyolefin wax to water was 1:50. The mixture was stirred continuously at 100 rpm for 30 min at 175 °C and 8.2 atm pressure. After the reaction was completed, it was immediately quenched with cold water to obtain a mixed wax emulsion.

[0094] (3) The nucleating agent and the initiator were diluted with water and then mixed. The dilution ratio was 100 times and the water temperature was 23°C to obtain a diluted solution.

[0095] (4) Mix the mixed wax emulsion, diluent and coupling agent solution, then add the remaining water, and continue stirring at 50 rpm to obtain the anti-creep glass fiber impregnating agent.

[0096] The raw materials used in Comparative Examples 1-5 are different from those in Example 1, but the other steps are the same as in Example 1.

[0097] The addition amounts of each component in Examples 1-7 and Comparative Examples 1-5 are shown in Tables 1, 2 and 3. The values ​​are all percentages of the solid mass of each component to the total solid mass of the wetting agent.

[0098] Performance testing:

[0099] The sizing agents obtained in Examples 1-7 and Comparative Examples 1-5 were respectively coated for the production of glass fibers. The corresponding glass fibers were then baked and chopped to produce chopped glass fibers. The glass type was boron-free and fluorine-free glass, the fiber diameter was 13 μm, and the chopped length was 3 mm. Then, the corresponding chopped glass fibers were melt-blended with polypropylene resin and extruded and granulated to finally obtain glass fiber reinforced polypropylene resin granules (glass fiber content was 30%). The performance test results are shown in Tables 1, 2, and 3.

[0100] The performance of glass fiber reinforced polypropylene composites was evaluated using the following methods:

[0101] Tensile strength was tested according to ISO 527-2-2012 standard;

[0102] Bending strength was tested according to ISO 178-2-2010 standard;

[0103] The notched impact strength of simply supported beams was tested according to ISO 179-1-2016 standard;

[0104] The creep resistance was tested according to GB6095-85. The sample size was 120×10×4mm, the test temperature was 23℃, the stress was 30MPa, and the strain of the outermost layer of the sample was recorded after 48 hours.

[0105] Fatigue resistance was tested according to ISO 527-2-2012 and ISO 13003-2003, with a sample size of 150×10×4mm and a frequency of 5Hz. The fatigue resistance was tested at 23℃ and 80℃ respectively. The maximum periodic stress at 23℃ was 60MPa, and the stress ratio was 0.1. The maximum periodic stress at 80℃ was 40MPa, and the stress ratio was 0.1.

[0106]

[0107]

[0108]

[0109] As shown in Tables 1 and 2, the reinforced polypropylene materials of Examples 1-7 have excellent mechanical properties, creep resistance, and fatigue resistance.

[0110] Compared with Example 3, Comparative Example 1 did not use maleic anhydride-modified long-chain branched polypropylene wax as a film-forming agent, but instead used polypropylene wax. The degree of molecular chain entanglement of polypropylene wax was much lower than that of maleic anhydride-modified long-chain branched polypropylene wax. This resulted in a weakened interaction between the glass fiber and the polypropylene matrix, a significant reduction in creep resistance, and the fact that the polypropylene wax was not modified by maleic anhydride grafting resulted in poor compatibility between the glass fiber and polypropylene, and the mechanical properties were also much lower than those of Example 3.

[0111] Compared with Example 3, Comparative Example 2 uses a different type of coupling agent. Comparative Example 2 uses an aminosilane coupling agent, while Example 3 uses a vinyl silane coupling agent and a long-chain alkylsilane coupling agent. There is no chemical interaction between the aminosilane coupling agent and polypropylene, and the non-valent bond interactions such as hydrogen bonding are also very weak. Therefore, Comparative Example 2 is inferior to Example 3 in both chemical bonding and non-valent bond interactions, resulting in lower mechanical properties, creep resistance, and creep tolerance.

[0112] Compared with Example 3, Comparative Example 3 did not add ammonium fluoroborate as a nucleating agent. This resulted in a lower degree of participation of the maleic anhydride-modified long-chain branched polypropylene wax on the glass fiber surface in polypropylene crystallization, and the crystallinity of the polypropylene matrix was also not high. The ability of crystallization to restrict the movement of molecular chains was relatively weak, which ultimately resulted in a decrease in tensile strength and flexural strength, but an increase in impact strength, and a decrease in creep resistance and fatigue resistance.

[0113] Compared with Example 3, Comparative Example 4 did not include physical crosslinking components such as SBS. This resulted in a reduction in the number of sites where the initiator could initiate the crosslinking of glass fiber and polypropylene to form chemical bonds, and a lower degree of crosslinking between glass fiber and polypropylene. This led to a decrease in the tensile strength, flexural strength, creep resistance and fatigue resistance of Comparative Example 4. Furthermore, since the soft segments of SBS can absorb energy during impact, the absence of this function significantly reduced the impact strength of Comparative Example 4.

[0114] Compared with Example 3, no initiator was added to Comparative Example 5. This directly resulted in most of the unsaturated bonds in vinyltrimethoxysilane and SBS failing to open and undergo cross-linking reactions, which greatly affected the number of bonds between the glass fiber and the polypropylene matrix. This led to a decrease in the tensile strength, flexural strength, creep resistance and fatigue resistance of Comparative Example 5. However, the reduced degree of cross-linking is beneficial to the movement of molecular chains. During the impact process, the molecular chains and chain segments can absorb energy through deformation movement, thereby improving the impact strength of Comparative Example 5.

Claims

1. An anti-creep glass fiber impregnating agent, characterized in that... The anti-creep glass fiber impregnating agent contains 3-12% solids, including active ingredients and water; the active ingredients, by weight percentage, include the following components: Maleic anhydride modified long-chain branched polyolefin wax 65.5-86.9 wt.% Coupling agent 5-10 wt.% nucleating agent 1-8 wt.% Physically cross-linked components 5-12 wt.% Initiator 0.1-0.5 wt.% Surfactant 2-4 wt.%; The physical crosslinking component is one or more of SBS, SEBS, or SEEPS.

2. The anti-creep glass fiber impregnating agent according to claim 1, characterized in that... The maleic anhydride-modified long-chain branched polyolefin wax is maleic anhydride-modified long-chain branched polypropylene wax or maleic anhydride-modified long-chain branched polyethylene wax. The relative molecular weight of the maleic anhydride-modified long-chain branched polyolefin wax is 2000-50000, and the maleic anhydride grafting rate of the maleic anhydride-modified long-chain branched polyolefin wax is 0.8-1.5%.

3. The anti-creep glass fiber impregnating agent according to claim 1, characterized in that... The maleic anhydride-modified long-chain branched polyolefin wax is made from the following raw materials in weight percentages: Long-chain branched polyolefin waxes 93.5-97.9 wt.% Maleic anhydride 2-6 wt.% Dicumyl peroxide 0.1-0.5 wt.%.

4. The anti-creep glass fiber impregnating agent according to claim 3, characterized in that... The preparation method of the maleic anhydride-modified long-chain branched polyolefin wax includes the following steps: (1) Mix maleic anhydride with dicumyl peroxide and dissolve completely in acetone to obtain a mixture; (2) The mixture is heated and stirred with long-chain branched polyolefin wax to obtain a mixture; (3) The mixture is added to a twin-screw extruder for melt blending and granulation to obtain maleic anhydride modified long-chain branched polyolefin wax.

5. The anti-creep glass fiber impregnating agent according to claim 1, characterized in that... The coupling agents include vinyl silane coupling agents.

6. The anti-creep glass fiber impregnating agent according to claim 5, characterized in that... The coupling agent also includes one or more of acryloyloxysilane coupling agents, epoxysilane coupling agents, aminosilane coupling agents, or long-chain alkylsilane coupling agents.

7. The anti-creep glass fiber impregnating agent according to claim 1, characterized in that... The nucleating agent is one or more of sodium fluoroborate, ammonium fluoroborate, potassium fluoroborate, sodium glutarate, lithium benzoate, sodium cinnamate, sodium β-naphthoate, phosphate metal salt, sorbitol benzylidene derivative, dibenzylidene sorbitol, or di(p-methylbenzylidene)sorbitol.

8. The anti-creep glass fiber impregnating agent according to claim 1, characterized in that... The initiator is an azo initiator, and the surfactant is one or more of anionic surfactants, cationic surfactants, nonionic surfactants, or amphoteric surfactants.

9. A method for preparing an anti-creep glass fiber impregnating agent according to any one of claims 1-8, characterized in that... Includes the following steps: (1) Prepare a coupling agent solution by mixing the coupling agent with water; (2) Maleic anhydride-modified long-chain branched polyolefin wax, physical crosslinking component, surfactant and water are stirred and reacted. After the reaction is completed, the mixture is immediately quenched with cold water to obtain a mixed wax emulsion. (3) The nucleating agent and the initiator are diluted with water and then mixed to obtain a diluted solution; (4) Mix the mixed wax emulsion, diluent and coupling agent solution, then add the remaining water and stir to obtain the anti-creep glass fiber impregnating agent.

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