Glass fiber impregnating compound for SMC (Sheet Molding Compound) as well as preparation method, product and application thereof

Abstract

The invention discloses a glass fiber impregnating compound for SMC (Sheet Molding Compound). The glass fiber impregnating compound comprises effective components and water, the solid content of the impregnating compound is 11.3 to 18.8 percent; the impregnating compound comprises the following effective components in percentage by mass: 14.0 to 19.5 percent of coupling agent, 47.0 to 67.5 percent of film-forming agent, 9.5 to 15.0 percent of plasticizer, 5.0 to 10.5 percent of lubricant and 4.0 to 8.0 percent of antistatic agent, wherein the mass of the coupling agent accounts for 14.0 to 19.5 percent of the total mass of the impregnating compound; wherein the film-forming agent is a mixture of a first film-forming agent and a second film-forming agent, the mass ratio of the first film-forming agent to the second film-forming agent is 1: 1-1: 3.3, and the first film-forming agent is internal crosslinking waterborne polyurethane emulsion; and the second film-forming agent is hyperbranched water-based polyester emulsion. Glass fiber yarns produced by coating the impregnating compound are good in surface smoothness, good in wear resistance and ultrahigh in stiffness, so that fibers are excellent in immersion penetrating performance and mold pressing flowing performance in SMC (Sheet Molding Compound) production; the compatibility with polyester resin is good, the interface bonding is strong, and the mechanical property of a product can be obviously improved.

Description

Technical Field

[0001] This application relates to the field of sizing agents for glass fiber coating, and particularly to a glass fiber sizing agent for ultra-high stiffness SMC, as well as the preparation method, product and application of the sizing agent. Background Technology

[0002] With the continuous expansion of the SMC market, many application fields have placed high demands on the appearance quality of SMC products. Traditional SMC products require multiple post-processing steps, including repeated manual grinding, polishing, painting, and secondary coating, to achieve a beautiful surface. This not only significantly reduces production efficiency but also increases production costs. Therefore, Grade A surface SMC materials have emerged and are widely used. Meanwhile, to obtain lighter materials, the addition of fillers such as hollow glass microspheres increases the viscosity of the resin paste. For this type of material, glass fiber needs better dispersibility, impregnation, and molding flowability. Therefore, developing an SMC yarn with ultra-high stiffness and good resin compatibility has become particularly important. Summary of the Invention

[0003] This application aims to solve the above-mentioned technical problems and provides a glass fiber impregnating agent for SMC. The glass fiber produced by coating with this impregnating agent has good surface smoothness, good wear resistance, and ultra-high stiffness, which makes the fiber have excellent impregnation performance and molding flow performance in SMC production; and it has good compatibility with polyester resin and strong interfacial bonding, which can significantly improve the mechanical properties of the product.

[0004] To achieve the above technical effects, this application adopts the following technical solution:

[0005] According to one aspect of this application, a glass fiber impregnating agent for SMC is provided, characterized in that the impregnating agent comprises an effective component and water; the solid content of the impregnating agent is 11.3% to 18.8%; the effective component comprises a coupling agent, a film-forming agent, a plasticizer, a lubricant, and an antistatic agent; the percentage of the solid mass of each effective component of the impregnating agent to the total solid mass of the impregnating agent is expressed as follows:

[0006]

[0007]

[0008] Wherein, the film-forming agent is a mixture of a first film-forming agent and a second film-forming agent; the first film-forming agent is an internally crosslinked waterborne polyurethane emulsion; the second film-forming agent is a hyperbranched waterborne polyester emulsion; and the mass ratio of the first film-forming agent to the second film-forming agent is 1:1 to 1:3.3.

[0009] The percentage of the solid mass of each effective component of the wetting agent to the total solid mass of the wetting agent is expressed as follows:

[0010]

[0011] The lubricant is triethanolamine borate.

[0012] The plasticizer is an adipic acid polyester plasticizer.

[0013] The coupling agent is a silane coupling agent containing methacryloyloxy group.

[0014] The antistatic agent is citrate.

[0015] The adipic acid polyester plasticizer is a mixture of straight-chain fatty dicarboxylic acids synthesized by esterification of adipic acid with straight-chain n-octanol or n-decanol, dispersed in water.

[0016] The internally crosslinked aqueous polyurethane emulsion is an aqueous polyurethane emulsion synthesized using trimethylolpropane, diethylenetriamine, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane as internally crosslinking monomers.

[0017] The hyperbranched waterborne polyester emulsion is obtained by dispersing the product of the reaction of trimellitic anhydride, trimethylolpropane and glycidyl tert-carbonate as raw materials, N,N-dimethylacetamide as solvent and triphenylphosphine as catalyst in water.

[0018] The functions and contents of each component in the SMC glass wetting agent of this application are explained as follows:

[0019] The coupling agent used in this application is a silane coupling agent (general structural formula YSiX3). In this formula, Y is an organic terminus, typically an olefin or a hydrocarbon group with functional groups such as amino, mercapto, epoxy, azide, or isocyanate groups at the end; X is a hydrolyzable group, such as chlorine or alkoxy. Due to this unique chemical structure, the silane coupling agent can serve as a bridge between inorganic glass fibers and organic polymer film-forming agents, allowing the entire sizing agent film to be fixed to the glass fiber surface through chemical bonds, thereby maintaining good bundle structure, toughness, and stiffness of the glass fiber during processing or cutting. Preferably, the coupling agent used in this application is a silane coupling agent containing methacryloyloxy. The coupling agent containing acryloyloxy can form a stable bond with the film-forming agent selected in this application through chemical bonds, effectively improving the performance of the glass fiber. For example, the coupling agent used in this application can be γ-methacryloyloxypropyltrimethoxysilane coupling agent. Simultaneously, the amount of coupling agent used must be controlled within an appropriate range. Studies have found that if the coupling agent content is too low, it cannot effectively act as a bridge between the inorganic glass fiber and the organic polymer film-forming agent; if the content is too high, it will interfere with the film-forming agent and hinder its proper function. Therefore, this application controls the percentage of the solid mass of the coupling agent to the total solid mass of the wetting agent to be 14.0% to 19.5%; preferably 14.5% to 19.0%; more preferably 15.0% to 18.5%.

[0020] Film-forming agents are the main components of glass fiber sizing agents, playing a crucial role in protecting glass fibers, improving their cutability, bundle properties, and compatibility with the matrix resin. They have a decisive impact on the continuous production and subsequent applications of glass fibers. Therefore, the selection of film-forming agents is one of the key aspects of this application. In this application, the amount of film-forming agent used needs to be controlled within a suitable range. Insufficient film-forming agent can easily damage the glass fibers through mechanical friction, causing fuzzing and reducing compatibility with the matrix resin; excessive film-forming agent will slow down the resin impregnation of the yarn, leading to impregnation problems in the yarn within the sheet. Therefore, this application controls the percentage of the solid mass of the film-forming agent to the total solid mass of the sizing agent to be 47.0%–67.5%, preferably 49.0%–66.0%, and more preferably 51.0%–63.5%.

[0021] The film-forming agent used in this application is a combination of a first film-forming agent and a second film-forming agent, and the film-forming agent used in this application is in the form of an emulsion. The first film-forming agent is an internally crosslinked waterborne polyurethane emulsion, which is an waterborne polyurethane emulsion synthesized using trimethylolpropane, diethylenetriamine, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane as internally crosslinking monomers (Reference: Synthesis and Properties of Different Internally Crosslinked Waterborne Polyurethanes [J]. Gao Qiang et al. Guangdong Chemical Industry. 2023(20)). Compared with ordinary polyurethane emulsions, the internally crosslinked waterborne polyurethane emulsion has a higher degree of crosslinking, better water resistance and surface hardness after film formation, and its coating on the glass fiber surface gives it higher stiffness. Preferably, the solid content of the internally crosslinked waterborne polyurethane emulsion is 25.0% to 42.0%.

[0022] The second film-forming agent in this application is a hyperbranched waterborne polyester emulsion, which is obtained by dispersing the product of the reaction of trimellitic anhydride, trimethylolpropane and glycidyl tert-carbonate as raw materials, N,N-dimethylacetamide as solvent and triphenylphosphine as catalyst in water (Reference: Synthesis of hyperbranched polyester and its application in waterborne coatings [J]. Sun Jinpeng et al. Surface Technology. 2025(6)). Experiments have shown that the hyperbranched polyester film has high gloss, excellent adhesion, hardness and impact resistance. At the same time, it has good interfacial bonding with the target reinforcing matrix - unsaturated resin, which can effectively improve the mechanical properties of glass fiber composite products.

[0023] Furthermore, this application requires control over the dosage relationship between the first film-forming agent and the second film-forming agent. Studies have found that when the mass ratio of the first film-forming agent to the second film-forming agent is controlled at 1:1 to 1:3.3, the yarn exhibits better bundle properties, higher stiffness, better compatibility with unsaturated resin, and higher mechanical strength of the product. When the proportion of the first film-forming agent is too high, it can easily cause slower resin impregnation in the glass fiber product and a decrease in the mechanical properties of the product; while when the proportion of the second film-forming agent is too high, it can easily cause increased brittleness in the glass fiber product, making the film formation easily damaged, and resulting in a significant decrease in stiffness during use. Preferably, the mass ratio of the first film-forming agent to the second film-forming agent is 1:1.1 to 1:2.7; more preferably, it is 1:1.3 to 1:2.2.

[0024] Plasticizers are substances that can increase the plasticity of film-forming agents. Thermosetting resin emulsion film-forming agents, such as polyester emulsions, are brittle after curing. When the bonded parts of the glass fiber are subjected to external force, cracks are easily generated and rapidly propagated, leading to film cracking and the generation of a large number of glass fiber fuzz, which ultimately reduces the stiffness of the glass fiber. Therefore, this application uses plasticizers to reduce the brittleness of the film, increase its toughness, and improve the strength of the glass fiber film against external force. Preferably, the plasticizer is adipic acid polyester plasticizer, which is a mixture of straight-chain fatty dicarboxylic acid esters synthesized by esterification of adipic acid with straight-chain n-octanol and n-decanol dispersed in water (Reference: Development and application of the latest adipic acid polyester plasticizer [J]. Wang Duoren et al. Rubber and Plastics Technology and Equipment. 2025(51)). At the same time, the amount of plasticizer also needs to be controlled within a suitable range. Too much plasticizer will destroy the film-forming agent system, while too little plasticizer will lead to excessive glass fiber fuzz. Therefore, this application controls the percentage of the solid mass of the plasticizer to the total solid mass of the wetting agent to be 9.5-15.0%, preferably 10.0-14.5%, and more preferably 10.5-14.0%.

[0025] In this application, the lubricant is mainly used to ensure the lubrication effect of glass fibers during processes such as drawing, winding, and SMC production. Preferably, the lubricant is triethanolamine borate. Simultaneously, the amount of lubricant used must be controlled within a suitable range. Too little content will not achieve the desired lubrication effect, while too much content will cause the glass fiber surface to become sticky and clump together, affecting the cutting and dispersibility of the glass fibers and negatively impacting the mechanical properties of the glass fiber composite material. Therefore, this application controls the percentage of the solid mass of the lubricant to the total solid mass of the sizing agent to be 5.0–10.5%, preferably 5.5–10.0%, and more preferably 6.0–9.5%.

[0026] Because glass fibers are highly susceptible to static electricity during cutting, leading to uneven dispersion, this application employs an antistatic agent to enhance the antistatic properties of the glass fibers. Preferably, the antistatic agent is citrate, more preferably sodium citrate. Simultaneously, the amount of antistatic agent must be controlled within a suitable range; excessive dosage will damage the film-forming agent system, while insufficient dosage will cause static electricity problems in the glass fibers. Therefore, this application controls the percentage of the solid mass of the antistatic agent to the total solid mass of the sizing agent to be 4.0–8.0%, preferably 4.0–7.5%, and more preferably 5.0–7.0%.

[0027] In this application, water is the dispersed phase of each component in the wetting agent. Preferably, the water is deionized water.

[0028] According to a second aspect of this application, a method for preparing the aforementioned glass fiber impregnating agent for SMC is provided, comprising the following steps:

[0029] S1: Add the coupling agent to water for pre-dispersion to obtain a coupling agent solution;

[0030] S2: Dissolve the lubricant and antistatic agent separately in water to prepare lubricant solution and antistatic agent solution respectively. Then mix the two solutions evenly and add them to the solution obtained in step S1.

[0031] S3: Dilute the first film-forming agent with 5 to 10 times its volume of water; dilute the second film-forming agent with 6 to 12 times its volume of water, and then add them to the solution obtained in step S2, mix and stir evenly;

[0032] S4: After pre-dissolving the plasticizer, add it to the solution obtained in step S3, mix and stir until homogeneous.

[0033] According to a third aspect of this application, a glass fiber product produced by coating the SMC with a glass fiber sizing agent is provided.

[0034] According to the fourth aspect of this application, the glass fiber product is provided for use in the automotive and construction sectors.

[0035] The glass fiber reinforced resin matrix produced by coating the SMC with glass fiber impregnating agent is an unsaturated polyester resin.

[0036] The glass fiber yarn produced by coating with the sizing agent described in this application has good surface smoothness, good wear resistance, and high stiffness, which makes the fiber have excellent impregnation performance in SMC production; and it has good compatibility with unsaturated polyester resin and strong interfacial bonding, which can significantly improve the mechanical properties of the product. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0038] The beneficial effects of selecting the above-mentioned content ranges of each component in the glass fiber impregnating agent for SMC in this application will be illustrated by specific experimental data provided through examples.

[0039] Below are examples of preferred value ranges for the components included in the glass fiber composition according to this application.

[0040] Preferred Example 1

[0041] The glass fiber impregnating agent for SMC according to this application comprises an effective component and water, wherein the solid content of the impregnating agent is 11.3% to 18.8%; the effective component comprises a coupling agent, a film-forming agent, a plasticizer, a lubricant, and an antistatic agent; the percentage of the solid mass of each effective component of the impregnating agent to the total solid mass of the impregnating agent is expressed as follows:

[0042]

[0043] The plasticizer is an adipic acid polyester plasticizer;

[0044] The film-forming agent is a mixture of a first film-forming agent and a second film-forming agent; the first film-forming agent is an internally crosslinked waterborne polyurethane emulsion; the second film-forming agent is a hyperbranched waterborne polyester emulsion; the mass ratio of the first film-forming agent to the second film-forming agent is 1:1 to 1:3.3.

[0045] Preferred Example 2

[0046] The glass fiber impregnating agent for SMC according to this application comprises an effective component and water, wherein the solid content of the impregnating agent is 12.8% to 17.8%; the effective component comprises a coupling agent, a film-forming agent, a plasticizer, a lubricant, and an antistatic agent; the percentage of the solid mass of each effective component of the impregnating agent to the total solid mass of the impregnating agent is expressed as follows:

[0047]

[0048] The plasticizer is an adipic acid polyester plasticizer;

[0049] The film-forming agent is a mixture of a first film-forming agent and a second film-forming agent; the first film-forming agent is an internally crosslinked aqueous polyurethane emulsion; the second film-forming agent is a hyperbranched aqueous polyester emulsion; the mass ratio of the first film-forming agent to the second film-forming agent is 1:1.1 to 1:2.7.

[0050] Preferred Example 3

[0051] The glass fiber impregnating agent for SMC according to this application comprises an effective component and water, wherein the solid content of the impregnating agent is 12.8% to 17.8%; the effective component comprises a coupling agent, a film-forming agent, a plasticizer, a lubricant, and an antistatic agent; the percentage of the solid mass of each effective component of the impregnating agent to the total solid mass of the impregnating agent is expressed as follows:

[0052]

[0053] The plasticizer is an adipic acid polyester plasticizer;

[0054] The film-forming agent is a mixture of a first film-forming agent and a second film-forming agent; the first film-forming agent is an internally crosslinked aqueous polyurethane emulsion; the second film-forming agent is a hyperbranched aqueous polyester emulsion; the mass ratio of the first film-forming agent to the second film-forming agent is 1:1.1 to 1:2.7.

[0055] The lubricant is triethanolamine borate.

[0056] Preferred Example 4

[0057] The glass fiber impregnating agent for SMC according to this application comprises an effective component and water, wherein the solid content of the impregnating agent is 12.8% to 17.8%; the effective component comprises a coupling agent, a film-forming agent, a plasticizer, a lubricant, and an antistatic agent; the percentage of the solid mass of each effective component of the impregnating agent to the total solid mass of the impregnating agent is expressed as follows:

[0058]

[0059] The plasticizer is an adipic acid polyester plasticizer;

[0060] The film-forming agent is a mixture of a first film-forming agent and a second film-forming agent; the first film-forming agent is an internally crosslinked aqueous polyurethane emulsion; the second film-forming agent is a hyperbranched aqueous polyester emulsion; the mass ratio of the first film-forming agent to the second film-forming agent is 1:1.1 to 1:2.7.

[0061] The lubricant is triethanolamine borate;

[0062] The coupling agent is a silane coupling agent containing methacryloyloxy group.

[0063] Preferred Example 5

[0064] The glass fiber impregnating agent for SMC according to this application comprises an effective component and water, wherein the solid content of the impregnating agent is 13.8% to 17.3%; wherein the percentage of the solid mass of each component of the effective component to the total solid mass of the impregnating agent is expressed as follows:

[0065]

[0066] The plasticizer is an adipic acid polyester plasticizer;

[0067] The film-forming agent is a mixture of a first film-forming agent and a second film-forming agent; the first film-forming agent is an internally crosslinked aqueous polyurethane emulsion; the second film-forming agent is a hyperbranched aqueous polyester emulsion; the mass ratio of the first film-forming agent to the second film-forming agent is 1:1.3 to 1:2.2.

[0068] Preferred Example Six

[0069] The glass fiber impregnating agent for SMC according to this application comprises an effective component and water, wherein the solid content of the impregnating agent is 13.8% to 17.3%; wherein the percentage of the solid mass of each component of the effective component to the total solid mass of the impregnating agent is expressed as follows:

[0070]

[0071] The plasticizer is an adipic acid polyester plasticizer;

[0072] The film-forming agent is a mixture of a first film-forming agent and a second film-forming agent; the first film-forming agent is an internally crosslinked aqueous polyurethane emulsion; the second film-forming agent is a hyperbranched aqueous polyester emulsion; the mass ratio of the first film-forming agent to the second film-forming agent is 1:1.3 to 1:2.2.

[0073] The antistatic agent is citrate.

[0074] The adipic acid polyester plasticizer is a mixture of straight-chain fatty dicarboxylic acids synthesized by esterification of adipic acid with straight-chain n-octanol or n-decanol, dispersed in water.

[0075] Preferred Example 7

[0076] The glass fiber impregnating agent for SMC according to this application comprises an effective component and water, wherein the solid content of the impregnating agent is 13.8% to 17.3%; wherein the percentage of the solid mass of each component of the effective component to the total solid mass of the impregnating agent is expressed as follows:

[0077]

[0078] The plasticizer is an adipic acid polyester plasticizer;

[0079] The film-forming agent is a mixture of a first film-forming agent and a second film-forming agent; the first film-forming agent is an internally crosslinked aqueous polyurethane emulsion; the second film-forming agent is a hyperbranched aqueous polyester emulsion; the mass ratio of the first film-forming agent to the second film-forming agent is 1:1.3 to 1:2.2.

[0080] The antistatic agent is sodium citrate;

[0081] The adipic acid polyester plasticizer is a mixture of straight-chain fatty dicarboxylic acid esters synthesized by esterification of adipic acid with straight-chain n-octanol or n-decanol, dispersed in water.

[0082] The internally crosslinked waterborne polyurethane emulsion is a waterborne polyurethane emulsion synthesized using trimethylolpropane, diethylenetriamine, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane as internally crosslinking monomers.

[0083] Preferred Example 8

[0084] The glass fiber impregnating agent for SMC according to this application comprises an effective component and water, wherein the solid content of the impregnating agent is 13.8% to 17.3%; wherein the percentage of the solid mass of each component of the effective component to the total solid mass of the impregnating agent is expressed as follows:

[0085]

[0086] The plasticizer is an adipic acid polyester plasticizer;

[0087] The film-forming agent is a mixture of a first film-forming agent and a second film-forming agent; the first film-forming agent is an internally crosslinked aqueous polyurethane emulsion; the second film-forming agent is a hyperbranched aqueous polyester emulsion; the mass ratio of the first film-forming agent to the second film-forming agent is 1:1.3 to 1:2.2.

[0088] The antistatic agent is sodium citrate;

[0089] The adipic acid polyester plasticizer is a mixture of straight-chain fatty dicarboxylic acid esters synthesized by esterification of adipic acid with straight-chain n-octanol or n-decanol, dispersed in water.

[0090] The internally crosslinked aqueous polyurethane emulsion is an aqueous polyurethane emulsion synthesized with trimethylolpropane, diethylenetriamine and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane as internally crosslinking monomers;

[0091] The hyperbranched waterborne polyester emulsion is obtained by dispersing the product of the reaction of trimellitic anhydride, trimethylolpropane and glycidyl tert-carbonate as raw materials, N,N-dimethylacetamide as solvent and triphenylphosphine as catalyst in water.

[0092] The following are some specific embodiments of the glass fiber impregnating agent for SMC in this application.

[0093] Example

[0094] Table 1 shows the percentage of solid mass of each component in the total solid mass of the glass fiber impregnating agent for SMC in the embodiments of this application.

[0095] Table 1 Formulations of glass fiber impregnating agents for SMC (Simplified Chinese Fiber Optic Mixing)

[0096]

[0097] Table 1 (continued) Examples of glass fiber impregnating agents for SMC

[0098]

[0099] The preparation methods of Examples 1-12 are as follows:

[0100] S1: Add the coupling agent to water for pre-dispersion to obtain a coupling agent solution;

[0101] S2: Dissolve the lubricant and antistatic agent separately in water to prepare lubricant solution and antistatic agent solution respectively. Then mix the two solutions evenly and add them to the solution obtained in step S1.

[0102] S3: Dilute the first film-forming agent with 5 to 11 times its volume of water; dilute the second film-forming agent with 4 to 10 times its volume of water, and then add them to the solution obtained in step S2, mix and stir evenly;

[0103] S4: After pre-dissolving the toughening agent, add it to the solution obtained in step S3, mix and stir until homogeneous.

[0104] To further illustrate the beneficial effects of this application, two commonly used glass fiber sizing agents (Comparative Example 1 and Comparative Example 2) and a glass fiber sizing agent with different formulations (Comparative Example 3) were selected for performance testing and comparison. The percentage of the solid content of each effective component in the comparative examples relative to the total solid content of the sizing agent is expressed as follows, with the balance being water:

[0105] Comparative Example 1

[0106]

[0107]

[0108] Comparative Example 2

[0109]

[0110] Comparative Example 3

[0111]

[0112] Table 2 shows the performance test results of glass fiber ply yarns produced using the sizing agents shown in Examples 1-12 and Comparative Examples 1-3. To ensure the comparability of the test results, the combustible content of the glass fibers prepared in each example and comparative example was kept essentially the same during sample preparation (control range 1.8-2.2, center value 2.00), meaning that the percentage of solid mass of the sizing agent coating the glass fiber surface to the total mass of the glass fiber was essentially consistent in both examples and comparative examples. Furthermore, the other raw materials and production process parameters used in the mechanical property tests of the glass fibers prepared in each example and comparative example were kept consistent to allow for parallel comparison of the glass fiber performance.

[0113] The impregnation time test method involves taking a certain amount of chopped yarn and spreading it evenly on a glass plate. A certain amount of unsaturated resin is then poured into a confined area, and timing begins simultaneously. The resin impregnation rate of the glass fiber ply yarn is measured by testing the time required for the resin to penetrate the yarn and reach the surface of the glass plate.

[0114] Among them, the glass fiber reinforced unsaturated polyester resin samples used for mechanical property testing (including flexural strength and lateral compressive strength) are prepared by SMC (sheet molding compound).

[0115] Table 2. Performance test results of glass fibers produced by sizing agent coating in the examples and comparative examples.

[0116]

[0117]

[0118] Table 2 (continued) Performance test results of glass fibers produced by sizing agent coating in the examples and comparative examples

[0119]

[0120]

[0121] Note:

[0122] From the above test results, we can see that the stiffness and penetration time of the glass fiber coated with the sizing agent of this application have significant advantages over the comparative example. The mechanical properties of the fiber-reinforced unsaturated polyester resin prepared are also significantly better than those of the comparative example, such as the glass fibers prepared with the sizing agents of Examples 6 and 7, which show particularly outstanding performance.

[0123] Therefore, it can be seen that the glass fiber sizing agent formulation and process provided in this application are scientific and reasonable. The glass fiber coated with the sizing agent has better compatibility with the unsaturated polyester resin, can form a stronger interfacial bond, and the surface properties of the product are also improved.

[0124] Finally, it should be noted that in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0125] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A glass fiber impregnating agent for SMC, characterized in that, The wetting agent comprises an effective component and water; the solid content of the wetting agent is 11.3% to 18.8%; the effective component comprises a coupling agent, a film-forming agent, a plasticizer, a lubricant, and an antistatic agent; the percentage of the solid mass of each effective component of the wetting agent to the total solid mass of the wetting agent is expressed as follows: Wherein, the film-forming agent is a mixture of a first film-forming agent and a second film-forming agent; the first film-forming agent is an internally crosslinked waterborne polyurethane emulsion; the second film-forming agent is a hyperbranched waterborne polyester emulsion; and the mass ratio of the first film-forming agent to the second film-forming agent is 1:1 to 1:3.

3.

2. The glass fiber impregnating agent for SMC according to claim 1, characterized in that, The percentage of the solid mass of each effective component of the wetting agent to the total solid mass of the wetting agent is expressed as follows: The lubricant is triethanolamine borate.

3. The glass fiber impregnating agent for SMC according to claim 1 or 2, characterized in that, The plasticizer is adipic acid polyester plasticizer.

4. The glass fiber impregnating agent for SMC according to claim 1 or 2, characterized in that, The coupling agent is a silane coupling agent containing methacryloyloxy group; the antistatic agent is citrate.

5. The glass fiber impregnating agent for SMC according to claim 3, characterized in that, The adipic acid polyester plasticizer is a mixture of straight-chain fatty dicarboxylic acids synthesized by esterification of adipic acid with straight-chain n-octanol and n-decanol, dispersed in water.

6. The glass fiber impregnating agent for SMC according to claim 1 or 2, characterized in that, The internally crosslinked waterborne polyurethane emulsion is a waterborne polyurethane emulsion synthesized using trimethylolpropane, diethylenetriamine, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane as internally crosslinking monomers.

7. The glass fiber impregnating agent for SMC according to claim 1 or 2, characterized in that, The hyperbranched waterborne polyester emulsion is obtained by dispersing the product of the reaction of trimellitic anhydride, trimethylolpropane and glycidyl tert-carbonate as raw materials, N,N-dimethylacetamide as solvent and triphenylphosphine as catalyst in water.

8. A method for preparing a glass fiber impregnating agent for SMC as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Add the coupling agent to water for pre-dispersion to obtain a coupling agent solution; S2: Dissolve the lubricant and antistatic agent separately in water to prepare lubricant solution and antistatic agent solution respectively. Then mix the two solutions evenly and add them to the solution obtained in step S1. S3: Dilute the first film-forming agent with 5 to 10 times its volume of water; dilute the second film-forming agent with 6 to 12 times its volume of water, and then add them to the solution obtained in step S2, mix and stir evenly; S4: After pre-dissolving the plasticizer, add it to the solution obtained in step S3, mix and stir until homogeneous.

9. A glass fiber product produced by coating SMC with a glass fiber impregnating agent as described in any one of claims 1 to 7.

10. An application of the glass fiber product as described in claim 9 in the automotive and construction fields.

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