A sizing agent for glass fiber cloth for prepreg and a method for preparing the same

Abstract

The application provides a sizing agent for glass fiber cloth for prepreg and a preparation method thereof, which comprises a film forming agent and a functional additive; the film forming agent comprises polyvinyl alcohol and starch; the functional additive comprises polyethylene glycol, a foaming agent and nanoparticles; and the mass ratio of the film forming agent to the functional additive is (2.7-8):(0.5-2.6). The sizing agent for glass fiber cloth for prepreg provided by the application can form a sizing film capable of protecting the glass fiber cloth from abrasion during the preparation process, is easy to desize, and the glass fiber cloth has a high strength retention rate after heat cleaning.

Description

Technical Field

[0001] This invention relates to the field of glass fiber post-treatment technology, and in particular to a sizing agent for glass fiber cloth used in prepregs and its preparation method. Background Technology

[0002] Glass fiber is produced by spinning molten glass into filaments, bundling thousands of these filaments into a single strand, cutting it into short fibers 3-6 mm in length, or further aggregating dozens of strands into roving. During the manufacturing process, a glass fiber sizing agent is used to prevent filament breakage and fuzzing caused by friction, thus protecting the filaments. Glass fiber yarn undergoes high-speed, repeated bending and friction on a loom. Furthermore, high-performance glass fiber cloth has strict requirements for surface fuzz and warp and weft strength, while also ensuring production efficiency. The use of a sizing agent increases the strength and abrasion resistance of the warp yarns and simultaneously covers the fuzz.

[0003] Currently, polyvinyl alcohol (PVA)-based sizing agents are commonly used to sizing glass fiber warp yarns. While the resulting sizing film exhibits excellent toughness, abrasion resistance, and flexural strength, desizing is difficult. Incomplete PVA combustion often occurs during the curing process, resulting in incomplete desizing. To achieve better desizing, the curing temperature or time needs to be increased to fully decompose the sizing agent on the warp yarns, but this increases costs. Incomplete decomposition leaves residual carbides on the fiber surface, affecting the subsequent application of the fiber. Furthermore, prepreg glass fiber cloth requires higher strength than electronic cloth, and the processing of electronic cloth significantly damages yarn strength, resulting in poor fabric strength in desizing prepreg glass fiber cloth, sometimes even failing to meet the requirements for prepreg use. Summary of the Invention

[0004] This invention provides a sizing agent for glass fiber cloth used in prepregs and its preparation method. The sizing film formed by the sizing agent can protect the glass fiber cloth from wear during the preparation process, is easy to desizing, and the glass fiber cloth still has a high strength retention rate after hot cleaning.

[0005] In a first aspect, the present invention provides a sizing agent for glass fiber cloth used in prepregs, comprising a film-forming agent and functional additives; the film-forming agent comprises polyvinyl alcohol and starch; the functional additives comprise polyethylene glycol, a foaming agent and nanoparticles; the mass ratio of the film-forming agent to the functional additives is (2.7-8):(0.5-2.6).

[0006] Preferably, the molecular weight of the polyethylene glycol is 4000 to 8000.

[0007] Preferably, the polyvinyl alcohol is polyvinyl alcohol 16-99 or polyvinyl alcohol 17-99.

[0008] Preferably, the starch is esterified modified starch, which includes amylose and amylopectin.

[0009] Preferably, the foaming agent is azodicarbonamide.

[0010] Preferably, the nanoparticles are nano-zinc oxide.

[0011] More preferably, the particle size of the nanoparticles is 30 to 300 nm.

[0012] Preferably, the mass ratio of the polyvinyl alcohol to the amylopectin is (4-12):(1-3).

[0013] Preferably, the mass ratio of the amylose to the amylopectin is (0.4-1):(1-3).

[0014] Preferably, the ratio of the sum of the masses of the amylose and the amylopectin to the mass of the foaming agent is (7-20):(1-5).

[0015] Preferably, the sizing agent for the prepreg glass fiber cloth comprises the following components in parts by weight: 2-6 parts polyvinyl alcohol, 0.2-0.5 parts amylose, 0.5-1.5 parts amylopectin, 0.5-2 parts polyethylene glycol, 0.1-0.5 parts foaming agent, 0.01-0.05 parts nanoparticles, and 90-98 parts water.

[0016] In a second aspect, the present invention also provides a method for preparing a sizing agent for prepreg fiber cloth based on the first aspect described above, the preparation method comprising the following steps:

[0017] (1) Add starch to water to gelatinize it, and obtain starch slurry;

[0018] (2) Add the foaming agent and nanoparticles to water and disperse them by ultrasonication, then add them to the starch slurry and mix well to obtain a dispersion.

[0019] (3) Add polyvinyl alcohol to an aqueous solution containing polyethylene glycol and mix well to obtain a mixture;

[0020] (4) Mix the dispersion and the mixture to obtain the glass fiber cloth sizing agent for the prepreg.

[0021] Preferably, in step (1), the gelatinization temperature is 87-97°C and the gelatinization time is 12-24 hours.

[0022] Preferably, in step (2), the mixing is carried out by sealing and stirring at 60-80°C for 30-60 minutes.

[0023] More preferably, the ultrasonic dispersion has a power of 40W, a frequency of 30-50Hz, a stirring speed of 100-200rpm, and a time of 5-20min.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] The sizing agent for prepreg fiberglass cloth of the present invention includes polyvinyl alcohol, linear starch, amylopectin, polyethylene glycol, a foaming agent, and nanoparticles. The introduction of a starch film-forming agent improves the relaxation of the sizing film and reduces the density of the film structure. The use of amylopectin improves the relaxation of the sizing film structure, preventing the sizing film structure from becoming too dense and causing yarn stiffness, leading to yarn breakage and difficulty in cleaning during hot washing. The introduction of linear starch and nanoparticles improves the toughness of the sizing film. Linear starch can alleviate the structural density after polyvinyl alcohol film formation, ensuring the yarn's textile performance while also opening pathways with the auxiliary gas, improving the aerobic decomposition efficiency of the sizing film during hot washing, thereby reducing the damage to the fibers from thermal shock during heat treatment. Introducing a foaming agent into the sizing agent, along with the addition of activating nanoparticles that lower the decomposition temperature of the foaming agent, and introducing a starch film-forming agent to improve the toughness of the sizing film while maintaining a certain degree of relaxation in the sizing film structure, and controlling the decomposition temperature of the foaming agent to the range where starch converts to dextrin, better promotes the formation of a porous structure. The high-temperature thermal decomposition of starch molecules into dextrin further relaxes the sizing film structure, causing the gas released from the foaming agent decomposition to increase the internal pressure. This allows the gas to escape within the relaxed film, opening pathways and transforming the sizing film structure from a compact to a porous structure. The increased porosity allows more oxygen to enter the membrane structure, preventing the formation of cavities due to an overly compact structure that would hinder gas flow. This increased porosity leads to a larger contact area between organic matter and oxygen during thermal cleaning, causing the organic matter to decompose from the inside of the sizing film. This reduces the energy required for complete oxidation and decomposition of the sizing film, thereby reducing thermal shock damage to the fiber body, preventing strength loss in the fiber fabric due to thermal cleaning, and improving the retention rate of fiber strength. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] This invention provides a sizing agent for glass fiber cloth used in prepregs, comprising a film-forming agent and functional additives; the film-forming agent comprises polyvinyl alcohol, amylose and amylopectin; the functional additives comprise polyethylene glycol, foaming agent and nanoparticles; the mass ratio of film-forming agent to functional additives is (2.7-8):(0.5-2.6).

[0028] According to some preferred embodiments, the starch is esterified modified starch, which includes amylose and amylopectin.

[0029] The sizing agent for prepreg fiberglass cloth of the present invention includes polyvinyl alcohol, amylose, amylopectin, polyethylene glycol, a foaming agent, and nanoparticles. The introduction of a starch film-forming agent improves the relaxation of the sizing film and reduces the density of the film structure. The use of amylopectin increases the relaxation of the sizing film structure, preventing an overly dense structure and yarn stiffness that could lead to breakage and difficulty in cleaning during heat treatment. The introduction of amylose and nanoparticles improves the toughness of the sizing film, ensuring yarn spinning performance while increasing the aerobic decomposition efficiency of the sizing film during heat treatment, thereby mitigating thermal shock damage to the fibers. By introducing a foaming agent into the sizing agent and adding activating nanoparticles that lower the decomposition temperature of the foaming agent, the sizing film structure maintains a certain degree of relaxation while the starch film-forming agent improves the toughness of the sizing film. The dextrin produced by the high-temperature thermal decomposition of starch molecules further relaxes the sizing film structure, allowing the gas from the decomposition of the foaming agent to escape and open pathways, resulting in a transformation of the sizing film structure from a dense structure to a porous structure. Thus, the increased porosity of the membrane structure leads to a larger contact area between organic matter and oxygen during the hot cleaning process. The decomposition of organic matter begins from the inside of the membrane, reducing the energy required for complete oxidation and decomposition of the membrane. This reduces the damage to the fiber body caused by thermal shock, avoids the loss of fiber fabric strength due to hot cleaning, and improves the retention rate of fiber strength.

[0030] Specifically, for (2.7~8):(0.5~2.6), it is any ratio from 2.7:2.6 to 8:0.5, for example, it can be 2.7:2.6, 2.7:2, 2.7:1.5, 2.7:1, 2.7:0.5, 3:2.6, 3:2, 3:0.5, 4:2.6, 4:0.5, 6:2.6, 6:0.5, 8:2.6 or 8:0.5.

[0031] It should be noted that the sizing agent provided in this embodiment of the invention is for secondary sizing, that is, the sizing agent is applied to the secondary sizing step after the glass fiber has been sized once using conventional sizing agents.

[0032] According to some preferred embodiments, the molecular weight of polyethylene glycol is 4,000 to 8,000 (e.g., it can be 4,000, 4,500, 5,000, 5,500, 6,000, 6,500, 7,000, 7,500 or 8,000).

[0033] In this invention, polyethylene glycol (PEG) exhibits good water solubility, serving as an excellent lubricant, antistatic agent, and moisturizer. Furthermore, PEG has a low decomposition temperature during heat treatment, preventing the formation of residual carbon that could affect the appearance of the glass fiber fabric. Moreover, above 160°C, PEG undergoes etherification and dehydration as the temperature rises; the vaporization of these water molecules helps the foaming agent open the pores in the film. Thus, by limiting the molecular weight of PEG to 4000–6000, the aforementioned functions can be fully realized.

[0034] According to some preferred embodiments, the polyvinyl alcohol is polyvinyl alcohol 16-99 or polyvinyl alcohol 17-99.

[0035] According to some preferred embodiments, the amylopectin is an esterified modified starch, which includes amylose and amylopectin.

[0036] According to some preferred embodiments, the foaming agent is azodicarbonamide.

[0037] In this embodiment of the invention, the foaming agent azodicarbonamide has the largest gas generation, the best performance, and an adjustable foaming temperature. After its introduction, it can transform the solid structure of the slurry film into a porous structure through the gas decomposed by the foaming agent during the heat treatment process.

[0038] According to some preferred embodiments, the nanoparticles are nano-zinc oxide.

[0039] According to some preferred embodiments, the particle size of the nanoparticles is 30 to 300 nm (e.g., it can be 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 120 nm, 150 nm, 160 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm or 300 nm).

[0040] According to some more preferred embodiments, the mass ratio of the foaming agent to the nanoparticles is (0.1 to 0.5):(0.01 to 0.05) (for example, it can be 0.1:0.01, 0.2:0.01, 0.3:0.01, 0.4:0.01, 0.5:0.01, 0.1:0.05, 0.2:0.05, 0.3:0.05 or 0.4:0.05).

[0041] In this embodiment of the invention, nanoparticles facilitate full contact with various raw material components, while nano-zinc oxide can further reduce the decomposition temperature of the foaming agent azodicarbonamide. Simultaneously, by limiting the mass ratio of the foaming agent to nanoparticles, the decomposition temperature of the foaming agent azodicarbonamide can be further adjusted to be slightly lower than the temperature at which starch is converted to dextrin. This promotes relative consistency of the foaming agent at the starch-to-dextrin temperature, allowing the film to rapidly transform from a dense structure to a porous structure upon reaching the decomposition temperature. This further reduces the temperature of the heat treatment or heat cleaning process, thus reducing energy consumption.

[0042] According to some preferred embodiments, the mass ratio of polyvinyl alcohol to amylopectin is (4-12):(1-3) (for example, it can be 4:1, 4:2, 4:3, 6:1, 6:2, 6:3, 8:1, 8:2, 8:3, 10:1, 10:2, 10:3 or 12:1).

[0043] In this embodiment of the invention, the main film-forming agent is polyvinyl alcohol, which is soluble in water at 80–90°C. Its aqueous solution has excellent adhesion and film-forming properties, exhibiting superior film-forming performance and good film toughness. Simultaneously, starch is used as an auxiliary film-forming agent. Amylopectin can improve the relaxation of the film structure, while the cross-linking of amylose and polyvinyl alcohol can improve the toughness of the film and prevent excessively loose film from detaching. Experiments have confirmed that by limiting the mass ratio of starch to polyvinyl alcohol within the above-mentioned range, the density and relaxation of the film can be further increased, meeting the requirements of yarn spinning performance.

[0044] According to some preferred embodiments, the mass ratio of amylose to amylopectin is (0.4 to 1):(1 to 3) (for example, it can be 0.4:1, 0.4:2, 0.4:3, 0.5:1, 0.5:2, 0.5:3, 0.8:1, 0.8:2, 0.8:3, 1:1, 1:2 or 1:3).

[0045] In this embodiment of the invention, the auxiliary film-forming agent is composed of amylose and amylopectin, which not only has certain molding properties but is also easily degradable. Experiments have shown that if too much amylose is used, the film formed by starch itself has relatively poor toughness, and excessive amylose will lead to a poorer coupling effect with PVA, resulting in poorer yarn spinnability. If too little amylose is used, the PVA coating will be too tight, preventing gas from escaping and opening pathways after foaming, thus forming bubbles inside and affecting the efficiency of subsequent heat treatment. Therefore, the mass ratio of amylose to amylopectin is limited to (0.4–1):(1–3).

[0046] According to some preferred embodiments, the ratio of the sum of the masses of amylose and amylopectin to the mass of the foaming agent is (7-20):(1-5) (for example, it can be 7:1, 7:2, 7:3, 7:4, 7:5, 10:1, 10:2, 10:3, 10:4, 2:1, 15:1, 15:2, 15:3, 15:4, 15:5, 20:1, 20:3 or 4:1).

[0047] In this embodiment of the invention, the fibers treated with the sizing agent form a dense sizing film on the fiber surface. During the desizing heat treatment, as the temperature rises, the foaming agent decomposes into gases such as CO2 and NH3. At this time, starch is heated and converted into dextrin, causing the dense structure of the sizing film to become loose. The gas inside the film begins to escape as the pressure increases, opening pathways and forming pores, resulting in the dense structure becoming a porous structure. This porous structure increases the contact area between organic matter and oxygen, promoting more aerobic decomposition of organic matter and reducing the heat required for the decomposition of organic matter on the fiber surface, thereby reducing energy consumption. On the other hand, reducing the treatment time or temperature during the heat treatment process reduces the damage of thermal shock to the fiber itself, slows down the formation of microcracks on the fiber surface, and improves the fiber strength retention rate. Experiments have confirmed that by limiting the ratio of the sum of the masses of amylose and amylopectin to the mass of the foaming agent, problems such as low porosity of the porous structure or the formation of air bubbles inside can be avoided when the amount of starch film-forming agent or foaming agent is too small.

[0048] According to some preferred embodiments, the sizing agent for prepreg fiberglass cloth comprises the following components in parts by weight: 2 to 6 parts of polyvinyl alcohol (e.g., 2, 2.5, 3, 3.5, 4, 4.5, 5, or 6 parts), 0.2 to 0.5 parts of amylose (e.g., 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, or 0.5 parts), 0.5 to 1.5 parts of amylopectin (e.g., 0.5, 0.8, 1, 1.2, or 1.5 parts), and 0.5 to 2 parts of polyethylene glycol (e.g., 0.5, 0.8, 1, 1.2, or 1.5 parts). 8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts or 2 parts), 0.1 to 0.5 parts of foaming agent (e.g., 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts or 0.5 parts), 0.01 to 0.05 parts of nanoparticles (e.g., 0.01 parts, 0.015 parts, 0.02 parts, 0.025 parts, 0.03 parts, 0.035 parts, 0.04 parts, 0.045 parts or 0.05 parts), and 90 to 98 parts of water (e.g., 90 parts, 92 parts, 94 parts, 96 parts or 98 parts).

[0049] In this embodiment of the invention, experiments have confirmed that, when the dosage of other components remains constant, if the dosage of amylose is too low, the sizing film will have fewer openings and lower porosity during desizing; if the dosage of amylose is too high, the sizing film will have poor coating properties. When the dosage of other components remains constant, if the dosage of amylopectin is too high, the sizing film will have poor toughness and density; conversely, if the dosage of amylopectin is too low, the sizing film will have excessively tight coating, resulting in stiff yarn that is prone to breakage. When the dosage of other components remains constant, if the dosage of foaming agent is too low, the sizing film will have low porosity during desizing; conversely, if the dosage of foaming agent is too high, the foaming agent will not disperse evenly due to poor dispersion, which may even lead to poor coating properties. When the dosage of other components remains constant, if the dosage of nanoparticles is too low, the sizing film will have poor toughness and will not effectively reduce the decomposition temperature of the foaming agent; if the dosage of nanoparticles is too high, the foaming agent will not be able to foam at the ideal temperature, thus failing to achieve the purpose of accelerating the thermal decomposition of organic matter on the fiber surface.

[0050] This invention also provides a method for preparing a sizing agent for glass fiber cloth used in prepregs, the method comprising the following steps:

[0051] (1) Add starch to water to gelatinize it and obtain starch slurry;

[0052] (2) Add the foaming agent and nanoparticles to water and disperse them by ultrasonication, then add them to starch slurry and mix well to obtain a dispersion.

[0053] (3) Add polyvinyl alcohol to an aqueous solution containing polyethylene glycol and mix well to obtain a mixture;

[0054] (4) Mix the dispersion and the mixture to obtain the sizing agent for glass fiber cloth prepreg.

[0055] According to some preferred embodiments, in step (1), the gelatinization temperature is 87-97°C (e.g., 87°C, 88°C, 90°C, 92°C, 95°C, 96°C or 97°C), and the gelatinization time is 12-24h (e.g., 12h, 15h, 16h, 18h, 20h, 22h or 24h).

[0056] According to some preferred embodiments, in step (2), the mixing is carried out by sealing and stirring at 60-80°C (for example, 60°C, 65°C, 70°C, 75°C or 80°C) for 30-60 minutes (for example, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes or 60 minutes).

[0057] In this embodiment of the invention, sealing and heat preservation are used to prevent starch from forming a film and peeling.

[0058] According to some preferred embodiments, the ultrasonic dispersion power is 40W, the frequency is 30-50Hz (e.g., 30Hz, 35Hz, 40Hz, 45Hz or 50Hz), the stirring speed is 100-200rpm (e.g., 100rpm, 120rpm, 150rpm, 180rpm or 200rpm), and the time is 5-20min (e.g., 5min, 6min, 10min, 15min or 20min).

[0059] In this invention, the starch slurry and the foaming agent are first mixed evenly, which enables the two to bond through hydrogen bonds and to be fully and evenly mixed. This makes it more beneficial for the starch slurry and the foaming agent to work synergistically during the subsequent heat treatment process, so as to transform the dense slurry film into a porous slurry film.

[0060] To more clearly illustrate the technical solution and advantages of the present invention, the following describes in detail a sizing agent for prepreg glass fiber cloth and its preparation method through several embodiments.

[0061] In the following examples and comparative examples, polyvinyl alcohol 1799 was selected, azodicarbonamide was selected as the foaming agent, and the ultrasonic power was 40W and the frequency was 50Hz.

[0062] Example 1

[0063] The sizing agent for prepreg fiberglass cloth comprises the following components in parts by weight: 3 parts polyvinyl alcohol, 0.3 parts linear starch, 1 part amylopectin, 0.6 parts polyethylene glycol (molecular weight 4000), 0.3 parts foaming agent, 0.03 parts nano zinc oxide, and 94.77 parts deionized water.

[0064] The preparation method of sizing agent for prepreg glass fiber cloth includes:

[0065] 1) Dissolve 0.6 parts of polyethylene glycol in 40 parts of deionized water at 50°C.

[0066] 2) Add 3 parts of polyvinyl alcohol to the solution in step 1) and heat to 90°C for 30 minutes to dissolve, thus obtaining a mixed solution;

[0067] 3) Add 0.3 parts of amylose and 1 part of amylopectin to 40 parts of deionized water and gelatinize at 95°C for 12 hours to obtain starch slurry;

[0068] 4) Add 0.3 parts of foaming agent and 0.03 parts of nano zinc oxide to the starch slurry in step 3) and ultrasonically disperse for 15 min, then seal and keep warm (60℃) at 200 rpm for 30 min.

[0069] 5) Add the solutions prepared in steps 2) and 4) to the stirring device, and then add 14.77 parts of deionized water and mix thoroughly.

[0070] The prepared sizing agent is added to the sizing device to sizing the glass fiber yarn, and then dried at 130°C to obtain a sizing film that can change its structure with temperature.

[0071] Example 2

[0072] The sizing agent for prepreg fiberglass cloth comprises the following components in parts by weight: 5 parts polyvinyl alcohol, 0.3 parts linear starch, 1 part amylopectin, 0.6 parts polyethylene glycol (molecular weight 4000), 0.3 parts foaming agent, 0.03 parts nano zinc oxide, and 92.77 parts deionized water.

[0073] The preparation method of sizing agent for prepreg glass fiber cloth includes:

[0074] 1) Dissolve 0.6 parts of polyethylene glycol in 40 parts of deionized water at 50°C.

[0075] 2) Add 5 parts of polyvinyl alcohol to the solution in step 1) and heat to 90°C for 30 minutes to dissolve, thus obtaining a mixed solution;

[0076] 3) Add 0.3 parts of amylose and 1 part of amylopectin to 40 parts of deionized water and gelatinize at 95°C for 12 hours to obtain starch slurry;

[0077] 4) Add 0.3 parts of foaming agent and 0.03 parts of nano zinc oxide to the starch slurry in step 3) and ultrasonically disperse for 15 min, then seal and keep warm (60℃) at 200 rpm for 30 min.

[0078] 5) Add the solutions prepared in steps 2) and 4) to the stirring device, and then add 12.77 parts of deionized water and mix thoroughly.

[0079] The prepared sizing agent is added to the sizing device to sizing the glass fiber yarn, and then dried at 130°C to obtain a sizing film that can change its structure with temperature.

[0080] Example 3

[0081] The sizing agent for prepreg fiberglass cloth comprises the following components in parts by weight: 3 parts polyvinyl alcohol, 0.5 parts linear starch, 1 part amylopectin, 0.6 parts polyethylene glycol (molecular weight 4000), 0.3 parts foaming agent, 0.03 parts nano zinc oxide, and 94.57 parts deionized water.

[0082] The preparation method of sizing agent for prepreg glass fiber cloth includes:

[0083] 1) Dissolve 0.6 parts of polyethylene glycol in 40 parts of deionized water at 50°C.

[0084] 2) Add 3 parts of polyvinyl alcohol to the solution in step 1) and heat to 90°C for 30 minutes to dissolve, thus obtaining a mixed solution;

[0085] 3) Add 0.5 parts of amylose and 1 part of amylopectin to 40 parts of deionized water and gelatinize at 95°C for 12 hours to obtain starch slurry;

[0086] 4) Add 0.3 parts of foaming agent and 0.03 parts of nano zinc oxide to the starch slurry in step 3) and ultrasonically disperse for 15 min, then seal and keep warm at 60℃ for 30 min at 200 rpm;

[0087] 5) Add the solutions prepared in steps 2) and 4) to the stirring device, and then add 14.57 parts of deionized water and mix thoroughly.

[0088] The prepared sizing agent is added to the sizing device to sizing the glass fiber yarn, and then dried at 130°C to obtain a sizing film that can change its structure with temperature.

[0089] Example 4

[0090] The sizing agent for prepreg fiberglass cloth comprises the following components in parts by weight: 3 parts polyvinyl alcohol, 0.3 parts linear starch, 0.5 parts amylopectin, 0.6 parts polyethylene glycol (molecular weight 4000), 0.3 parts foaming agent, 0.03 parts nano zinc oxide, and 95.27 parts deionized water.

[0091] The preparation method of sizing agent for prepreg glass fiber cloth includes:

[0092] 1) Dissolve 0.6 parts of polyethylene glycol in 40 parts of deionized water at 50°C.

[0093] 2) Add 3 parts of polyvinyl alcohol to the solution in step 1) and heat to 90°C for 30 minutes to dissolve, thus obtaining a mixed solution;

[0094] 3) Add 0.3 parts of amylose and 0.5 parts of amylopectin to 40 parts of deionized water and gelatinize at 95°C for 12 hours to obtain starch slurry;

[0095] 4) Add 0.3 parts of foaming agent and 0.03 parts of nano zinc oxide to the starch slurry in step 3) and ultrasonically disperse for 15 min, then seal and keep warm at 60℃ for 30 min at 200 rpm;

[0096] 5) Add the solutions prepared in steps 2) and 4) to the stirring device, and then add 15.27 parts of deionized water and mix thoroughly.

[0097] The prepared sizing agent is added to the sizing device to sizing the glass fiber yarn, and then dried at 130°C to obtain a sizing film that can change its structure with temperature.

[0098] Example 5

[0099] The sizing agent for prepreg fiberglass cloth comprises the following components in parts by weight: 3 parts polyvinyl alcohol, 0.3 parts linear starch, 1 part amylopectin, 0.6 parts polyethylene glycol (molecular weight 4000), 0.1 parts foaming agent, 0.01 parts nano zinc oxide, and 94.99 parts deionized water.

[0100] The preparation method of sizing agent for prepreg glass fiber cloth includes:

[0101] 1) Dissolve 0.6 parts of polyethylene glycol in 40 parts of deionized water at 50°C.

[0102] 2) Add 3 parts of polyvinyl alcohol to the solution in step 1) and heat to 90°C for 30 minutes to dissolve, thus obtaining a mixed solution;

[0103] 3) Add 0.3 parts of amylose and 1 part of amylopectin to 40 parts of deionized water and gelatinize at 95°C for 12 hours to obtain starch slurry;

[0104] 4) Add 0.1 parts of foaming agent and 0.01 parts of nano zinc oxide to the starch slurry in step 3) and ultrasonically disperse for 15 min, then seal and keep warm at 60℃ for 30 min at 200 rpm;

[0105] 5) Add the solutions prepared in steps 2) and 4) to the stirring device, and then add 14.99 parts of deionized water to mix thoroughly.

[0106] The prepared sizing agent is added to the sizing device to sizing the glass fiber yarn, and then dried at 130°C to obtain a sizing film that can change its structure with temperature.

[0107] Comparative Example 1

[0108] The sizing agent for prepreg fiberglass cloth comprises the following components in parts by weight: 3 parts polyvinyl alcohol, 0.3 parts linear starch, 1 part amylopectin, 0.6 parts polyethylene glycol (molecular weight 4000), 0.03 parts nano zinc oxide, and 95.07 parts deionized water.

[0109] The preparation method of sizing agent for prepreg glass fiber cloth includes:

[0110] 1) Dissolve 0.6 parts of polyethylene glycol in 40 parts of deionized water at 50°C.

[0111] 2) Add 3 parts of polyvinyl alcohol to the solution in step 1) and heat to 90°C for 30 minutes to dissolve, thus obtaining a mixed solution;

[0112] 3) Add 0.3 parts of amylose and 1 part of amylopectin to 40 parts of deionized water and gelatinize at 95°C for 8 hours to obtain starch slurry;

[0113] 4) Add 0.03 parts of nano zinc oxide to the starch slurry in step 3) and ultrasonically disperse for 15 min, then seal and keep warm (60℃) for 5 min;

[0114] 5) Add the solutions prepared in steps 2) and 4) to the stirring device, and then add 15.07 parts of deionized water and mix thoroughly.

[0115] The prepared sizing agent is added to the sizing device to sizing the glass fiber yarn, and then dried at 130°C to obtain the sizing film.

[0116] Comparative Example 2

[0117] Comparative Example 2 is basically the same as Example 1, except that the sizing agent for the prepreg glass fiber cloth includes the following components in parts by weight: 3 parts polyvinyl alcohol, 1 part linear starch, 0.3 parts amylopectin, 0.6 parts polyethylene glycol (molecular weight 4000), 0.3 parts foaming agent, 0.01 parts nano zinc oxide, and 94.79 parts deionized water.

[0118] Comparative Example 3

[0119] The sizing agent for prepreg fiberglass cloth comprises the following components in parts by weight: 3 parts polyvinyl alcohol, 0.3 parts linear starch, 1 part amylopectin, 0.6 parts polyethylene glycol (molecular weight 4000), 0.3 parts foaming agent, and 94.8 parts deionized water.

[0120] The preparation method of sizing agent for prepreg glass fiber cloth includes:

[0121] 1) Dissolve 0.6 parts of polyethylene glycol in 40 parts of deionized water at 50°C.

[0122] 2) Add 3 parts of polyvinyl alcohol to the solution in step 1) and heat to 90°C for 30 minutes to dissolve, thus obtaining a mixed solution;

[0123] 3) Add 0.3 parts of amylose and 1 part of amylopectin to 40 parts of deionized water and gelatinize at 95°C for 8 hours to obtain starch slurry;

[0124] 4) Add 0.3 parts of foaming agent to the starch slurry in step 3) and ultrasonically disperse for 15 minutes, then seal and keep warm (60℃) for 5 minutes;

[0125] 5) Add the solutions prepared in steps 2) and 4) to the stirring device, and then add 14.8 parts of deionized water to mix thoroughly.

[0126] The prepared sizing agent is added to the sizing device to sizing the glass fiber yarn, and then dried at 130°C to obtain the sizing film.

[0127] Glass fiber cloth with a roll weight of 500m was prepared from the glass fibers with a slurry film on the surface prepared in Examples 1 to 5 and Comparative Examples 1 to 3. The glass fiber cloth was subjected to heat cleaning treatment and relevant performance tests, and the data are shown in Table 1. The heat treatment process was pre-desizing at 200℃ for 15min and simmering at 380℃ for several hours. The specific time varied according to the experiment.

[0128] Specifically, the performance tests include: the combustible content is determined according to GB / T9914.2 Test Methods for Reinforced Products Part 2: Determination of Combustible Content in Glass Fibers; the sizing rate can be calculated based on the change in combustible content before and after sizing of the yarn; the hairiness index is determined according to the method of FZ / T01086-2000; and the abrasion resistance is determined according to the standard test method of ASTM D 3885-2004 Abrasion Resistance of Textile Fibers.

[0129] Table 1

[0130]

[0131]

[0132] It should be noted that the complete decomposition time refers to the total time of burning at 380℃ when the combustible content of the sizing film is ≤0.05%, and the strength retention rate is the warp and weft strength retention rate obtained after the combustibles on the fabric surface have been completely decomposed; the 24h combustible content refers to the test obtained after pre-desizing at 200℃ for 15 minutes and burning at 380℃ for 24 hours.

[0133] As shown in Table 1, the glass fiber cloth sizing agent for prepreg prepared in this embodiment of the invention not only has good abrasion resistance, high sizing rate, and low hairiness, but also retains excellent fabric strength and has lower combustible content, higher sizing film removal rate, and better desizing effect compared with the comparative example under the same heat treatment conditions. Furthermore, the glass fiber cloth sizing agent for prepreg prepared in this embodiment of the invention has a shorter complete decomposition time, further confirming that by shortening the heat treatment process time, the damage of thermal shock to the fiber itself can be significantly reduced, and the generation of microcracks on the fiber surface can be slowed down, thus improving the fiber strength retention rate.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention 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 the present invention. The parts of the present invention not described in detail are techniques known to those skilled in the art.

Claims

1. A sizing agent for glass fiber cloth used in prepregs, characterized in that, The product includes a film-forming agent and functional additives; the film-forming agent includes polyvinyl alcohol and starch; the functional additives include polyethylene glycol, a foaming agent, and nanoparticles; the mass ratio of the film-forming agent to the functional additives is (2.7~8):(0.5~2.6); the starch is esterified modified starch, which includes amylose and amylopectin; the foaming agent is azodicarbonamide; and the nanoparticles are nano-zinc oxide. It comprises the following components in parts by weight: 2-6 parts polyvinyl alcohol, 0.2-0.5 parts amylose, 0.5-1.5 parts amylopectin, 0.5-2 parts polyethylene glycol, 0.1-0.5 parts foaming agent, 0.01-0.05 parts nanoparticles, and 90-96 parts water.

2. The sizing agent for prepreg fiberglass cloth according to claim 1, characterized in that, The molecular weight of the polyethylene glycol is 4000~8000; The polyvinyl alcohol is polyvinyl alcohol 16-99 or polyvinyl alcohol 17-99.

3. The sizing agent for prepreg fiberglass cloth according to claim 1, characterized in that, The nanoparticles have a particle size of 30~300nm.

4. The sizing agent for prepreg fiberglass cloth according to claim 1, characterized in that, The mass ratio of the polyvinyl alcohol to the amylopectin is (4~12):(1~3).

5. The sizing agent for prepreg fiberglass cloth according to claim 1, characterized in that, The mass ratio of the amylose to the amylopectin is (0.4~1):(1~3).

6. The sizing agent for prepreg fiberglass cloth according to claim 1, characterized in that, The mass ratio of the starch to the foaming agent is (7~20):(1~5).

7. The method for preparing the sizing agent for prepreg glass fiber cloth according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: according to the stated component ratio. (1) Add starch to water to gelatinize it, and obtain starch slurry; (2) Add the foaming agent and nanoparticles to water and disperse them by ultrasonication, then add them to the starch slurry and mix well to obtain a dispersion; (3) Add polyvinyl alcohol to an aqueous solution containing polyethylene glycol and mix well to obtain a mixture; (4) Mix the dispersion and the mixture to obtain the glass fiber cloth sizing agent for the prepreg.

8. The preparation method according to claim 7, characterized in that, In step (1), the gelatinization temperature is 87~97℃ and the gelatinization time is 12~24h.

9. The preparation method according to claim 7 or 8, characterized in that, In step (2), the mixing is carried out by sealing and stirring at 60~80℃ for 30~60 minutes.

10. The preparation method according to claim 7 or 8, characterized in that, In step (2), the ultrasonic dispersion power is 40W, the frequency is 30~50Hz, the stirring speed is 100~200rpm, and the time is 5~20min.

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