Method for detecting content of unbonded silane and derivatives thereof on surface of glass fiber

Abstract

The invention belongs to the technical field of analysis and testing. The invention particularly relates to a method for detecting the content of unbonded silane and derivatives thereof on the surface of glass fiber. The method comprises the following steps: fully extracting unbonded silane and derivatives thereof in glass fibers by using a composite extraction solvent, carrying out segmented microwave digestion and constant volume dilution on an extract, and detecting the content of a silicon element by using an ICP-MS (Inductively Coupled Plasma Mass Spectrometry), and finally, comparing a result with a standard working curve of silicon, and converting to obtain content data of unbonded silane and derivatives thereof on the surface of the glass fiber. The method is suitable for detecting the content of unbonded silane and derivatives thereof on the surface of the glass fiber, and has the advantages of low detection limit, high detection precision up to ppb level and high detection efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of analytical testing technology. Specifically relates to a kind of glass fiber surface unbound silane and its derivative content detection method. BACKGROUND

[0002] Glass fiber is a kind of engineering plastics, has not burning, corrosion resistance, high temperature resistance, small hygroscopicity, small elongation and other excellent performance, also has very excellent characteristics in electrical, mechanics, chemistry and optics, etc., application field is spread in electronics, electrical appliances, transportation, building, aviation, aerospace, environmental protection and national defense and military industry and other fields.In the glass fiber production process, it is necessary to coat a kind of surface treatment agent with organic emulsion as main body on the surface of glass fiber, this coating can effectively lubricate the surface of glass fiber, also can integrate hundreds of even thousands of glass fiber filaments into a bundle, also can change the surface state of glass fiber, so as to not only meet the processing performance requirements of glass fiber filaments in subsequent processes, but also can promote the combination of glass fiber and the material to be reinforced in composite materials, these organic coatings are collectively referred to as glass fiber sizing agent, and silane coupling agent is one of the most important components in glass fiber sizing agent, the main chemical components of silane coupling agent are silicon, oxygen, carbon and hydrogen, generally represented as the structure of alkyl and some functional groups connected by silicon-oxygen bond, using in the sizing agent of glass fiber can improve the interaction between inorganic glass fiber material and plastic resin matrix, thereby improving the compatibility of the two types of materials, finally making the product obtain better performance and appearance.

[0003] However, unreacted silane and its derivatives can cause mechanical performance reduction, interface weakening, electrical performance problems, chemical durability reduction, and processing problems in glass fiber composites. In the mid-1970s, Yoshmura et al. of Jateishi Electronics Company in Japan found that a small amount of low molecular siloxane remained in the silicone rubber and gradually volatilized to fill the electrical contact space. Electric contact often produces electric arc and electric spark, and low molecular siloxane produces silicon dioxide and silicon carbide under the action of electric arc. When used for a long time, the silicon dioxide and silicon carbide will deposit in the conductive part to form an insulating layer, resulting in electrical contact failure. Low molecular exists in RTV, and is slowly released in the form of gas during and after product curing. In a closed system, it will eventually remain on the PCB surface, components, connectors, switches, optical mirrors, etc., causing obvious or potential hazards such as electrical connection point failure, LED and automobile lamp shade mirror fogging, switch short circuit, and printing ink adhesion failure. In the field of electronics and electrical appliances, the electrical insulation performance of the material has an important influence on the use of the product. In order to ensure the long-term stable operation of electrical components, the content of unbound silane and its derivatives in glass fiber reinforced materials is required to be as low as possible. However, there is currently no effective method for detecting the content of unbound silane on the surface of glass fibers.

[0004] Patent 201310225698 discloses a method for measuring the content of free silicon in silicon carbide refractory material. The invention converts free silicon in the sample into soluble silicate by immersing the silicon carbide sample in sodium hydroxide solution, while the silicon carbide and silicon nitride in the sample do not dissolve. After filtering and separating the precipitate, the filtrate is dissolved, concentrated, and diluted to obtain a test sample solution, and then the free silicon concentration is detected by inductively coupled plasma atomic emission spectrometry. However, this invention cannot be used to detect the content of unbound silane and its derivatives on the surface of glass fibers, because glass fibers themselves are not resistant to sodium hydroxide, and using sodium hydroxide solution will cause the structure silicon in the glass fibers to precipitate. In addition, the unbound silane and its derivatives in the glass fibers are mainly silane coupling agents, silanols, and their polycondensates, and sodium hydroxide solution cannot react with the above-mentioned substances to generate silicate, which leads to the fact that the method of this patent cannot obtain a suitable sample for silicon element detection.

[0005] Patent 202111554191 discloses a method for determining the content of free silicon in SiC composite material, which directly takes the milled silicon carbide composite material, adds sodium nitrate solution, nitric acid and hydrofluoric acid, heats and dissolves, cools, adds aluminum chloride solution, and mixes uniformly. After standing, the upper clear liquid is taken, diluted, and then the indicator is added, neutralized with ammonia water, and then hydrochloric acid and ammonium molybdate solution are added, placed, and then a mixture of oxalic acid and sulfuric acid is added, and the reducing agent is diluted with water. The absorbance is determined with water as the reference, and the content of free silicon in the silicon carbide composite material is calculated by using the standard curve and the determined absorbance value. However, the detection precision of free silicon in this patent is low, the detection limit is as high as 2.4ppm, and the lower limit of detection is as high as 10ppm, which cannot meet the testing requirements of the content of unbound silicon in glass fiber. In addition, the patent directly uses mixed acid solution containing hydrofluoric acid for sample dissolution, which will cause the reaction between glass fiber and hydrofluoric acid, so that the silicon element in the glass fiber is dissolved in ionic state, which will finally affect the accuracy of the test results.

[0006] Currently, there is no effective method for detecting unbound silane and its derivatives on the surface of glass fiber, which is not conducive to the adjustment of glass fiber sizing agent formula and process and the performance prediction of downstream composite products. Therefore, developing a test method for accurately detecting the content of unbound silane and its derivatives on the surface of glass fiber has important guiding significance for the development of glass fiber industry and downstream application fields such as electronic and electrical appliances. In order to promote the improvement of glass fiber products and the development of related electronic and electrical industries, the present application discloses a method for detecting the content of unbound silane and its derivatives on the surface of glass fiber. SUMMARY

[0007] The present application provides a method for detecting the content of unbound silane and its derivatives on the surface of glass fiber to solve the technical problems raised in the background art.

[0008] The present application provides a method for detecting the content of unbound silane and its derivatives on the surface of glass fiber, characterized by comprising the following steps: S1, weighing 10-100g of glass fiber to be measured and placing in a container; S2, weighing 2-5 times the weight of the glass fiber of the composite extraction solvent and adding to the container to obtain an extraction solution; S3, stirring the extraction solution at a temperature of 40-80℃ for 12-48h, and the stirring speed is 300-500rpm, to obtain a mixed solution; S4, filtering the glass fiber in the mixed solution obtained in the previous step to obtain an unbound silane extraction solution; S5, transfer 0.2-0.8ml un-bonded silane extraction solution to the digestion tank using a pipette, and weigh 5-8ml nitric acid, 1-2ml hydrochloric acid, 1-2ml hydrofluoric acid into the digestion tank, pre-digest at 100-120℃ for half an hour to obtain a pre-digested sample; S6, after pre-digestion, transfer the digestion tank to the microwave digestion equipment, set the microwave digestion process as follows: 120-130℃, heating time 5min, stable time 3min; 140-160℃, heating time 3min, stable time 10min; 170-180℃, heating time 3min, stable time 30min; S7, start the microwave digestion program, microwave digest the pre-digested sample, and cool to 60℃ after microwave digestion is completed to obtain a digestion solution; S8, transfer 5-10ml digestion solution to a colorimetric tube for dilution and constant volume using a pipette, the dilution multiple is 2-50, and the diluted digestion solution is obtained; S9, place the diluted digestion solution into the ICP-MS sample introduction system for silicon element concentration detection; S10, compare the silicon element signal results obtained by ICP-MS testing with the standard working curve of silicon to obtain the silicon element content in the diluted digestion solution, convert the results, and finally obtain the content results of un-bonded silane and its derivatives in the glass fiber.

[0009] Further, the composite extraction solvent is a mixture of two or more of water, isopentane, cyclopentane, n-hexane, cyclohexane, heptane, octane, isooctane, trimethylpentane, methanol, ethanol, ethylene glycol, n-propanol, isopropanol, glycerol, n-butanol, isobutanol, acetic acid, acetonitrile, benzene, toluene, p-xylene, m-xylene, vinyl toluene, butyl toluene, styrene, phenol, aniline, petroleum ether, decaline, diethyl ether, isopropyl ether, pentane, acetone, methyl butanone, methyl ethyl ketone, cyclohexanone, cyclohexanedione, ethylene glycol diethyl ether, diethanol monoethyl ether, monochloromethane, dichloromethane, trichloromethane, chloroform, carbon tetrachloride, tetrafluoroethylene, trichloroethylene, dichloroethane, trichloropropane, 1-chlorobutane, chlorobenzene, o-dichlorobenzene, carbon disulfide, phosphoric acid tri-o-cresol, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, tetrahydrofuran, dioxane, pyridine, acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide.

[0010] Further, the composite extraction solvent must contain at least one solvent capable of forming a hydrogen bond with un-bonded silane and its derivatives and at least one solvent having good solubility for the glass fiber film former.

[0011] Further, the funnel filtration method or centrifugal filtration method is used in S4.

[0012] Further, the digestion tank is a high-pressure digestion tank or a polytetrafluoroethylene digestion tank.

[0013] Further, the mixed acid solution is one of hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, hydrofluoric acid, and hydrobromic acid or a mixture of two or more thereof.

[0014] Further, the dilution factor of the dilution and constant volume is 2-10 times.

[0015] Further, the standard working curve of silicon is prepared by the following steps: (1) Preparation of a silicon standard solution: (1) A, commercially available reference pure silicon dioxide is calcined at 1000 DEG C for 1 h, cooled and dried; (1) B, 1.0698 g of the dried silicon dioxide is weighed according to the amount of 10 g of mixed flux / g sample, added to 10.7 g of a mixed flux of anhydrous sodium carbonate and boric acid, heated and melted at 950 DEG C for 15 min, cooled, and a fused block is obtained, wherein the mixed flux is in the following mass ratio: anhydrous sodium carbonate: boric acid = 2:1, finely ground and uniformly mixed; (1) C, the fused block of step (1) B is put into water until completely dissolved, cooled to room temperature, and then diluted with water to obtain a 500 ug / mL silicon solution, and a silicon standard solution is obtained; (1) D, the silicon standard solution of step (1) C is removed, diluted with water to obtain a 25 ug / mL silicon solution, and then removed into a plastic bottle for storage.

[0016] (2) Preparation of a silicon standard working solution: (2) A, 0.00 mL, 0.50 mL, 1.00 mL, 2.00 mL, 3.00 mL, 4.00 mL and 5.00 mL of the silicon standard solution prepared in step 1D are removed, respectively, and the mass fraction is 0.00%, 0.25%, 0.50%, 1.00%, 1.50%, 2.00% and 2.50%, respectively, and then placed in 7 50 mL volumetric flasks, respectively, 5 mL of hydrochloric acid solution is added, diluted with water to the mark, mixed, and 7 portions of 50 mL weakly acidic silicon standard solutions are obtained, and the hydrochloric acid solution is: commercially available hydrochloric acid and water in a volume ratio of 1:1; (2) B, the silicon spectral line intensity in the seven standard solutions of step (2) A is determined by a conventional inductively coupled plasma atomic emission spectrometry in the prior art, and the determination working condition is shown in Table 1; (2) C, the mass fraction of the silicon standard solution listed in step (2) A is taken as the abscissa, and the silicon intensity in the standard solution obtained in step (2) B is taken as the ordinate, and a standard working curve of silicon is drawn.

[0017] Compared with the prior art, the present application has the following beneficial effects: 1、The method for detecting the content of unbound silane and its derivatives on the surface of glass fiber of the present application extracts the unbound silane and its derivatives in the glass fiber through a composite extraction solution, which has good interaction with the unbound silane and its derivatives, and thus can effectively dissolve the unbound silane and its derivatives. 2、The composite extraction solution used in the method for detecting the content of unbound silane and its derivatives on the surface of glass fiber of the present application is neutral and does not react with the glass fiber body, avoiding the interference of the structural silicon reaction in the glass fiber to generate silicate and other substances on the detection result. 3、The composite extraction solution in the method for detecting the content of unbound silane and its derivatives on the surface of glass fiber of the present application can effectively dissolve the film-forming agent component as the main component in the glass fiber surface sizing agent, thereby effectively releasing the unbound silane and its derivatives covered by the sizing agent. 4、The method for detecting the content of unbound silane and its derivatives on the surface of glass fiber of the present application has high detection precision and low detection limit, which can reach ppb level, and can effectively determine the content of unbound silane and its derivatives on the surface of different glass fibers in the case of low silane coupling agent concentration in the glass fiber. DETAILED DESCRIPTION

[0018] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase that an embodiment in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combinable with other embodiments.

[0019] As introduced in the background, there is no effective method for detecting the content of unbound silane and its derivatives on the surface of glass fiber at present. In order to promote the improvement of the evaluation means of glass fiber products and the performance of electronic and electrical products, it is urgent to explore a new method to realize the accurate and reliable measurement of the content of unbound silane and its derivatives on the surface of glass fiber.

[0020] In order to solve the above technical problems, the present application provides a method for detecting the content of unbound silane on the surface of glass fiber. The glass fiber is weighed and placed in a container, a composite extraction solvent is measured and added to the container, after heating and stirring extraction for 24 hours, the unbound silane extraction liquid is separated from the glass fiber by funnel filtration method, the unbound silane extraction liquid is obtained, the unbound silane extraction liquid is weighed and added to an appropriate amount of mixed acid solution for stepwise digestion, then it is cooled to 60℃, the digestion liquid is transferred to a colorimetric tube and diluted with deionized water to obtain a test liquid, then the content of silicon element in the test liquid is detected by ICP-MS to obtain the content data of unbound silane on the surface of glass fiber.

[0021] The specific embodiments of the present application are further described below in conjunction with examples, and the present application is not limited in the scope of the described examples.

[0022] The raw materials used in the following examples and comparative examples include the following components: Unless otherwise specified, the reagents used in the analysis are analytical pure reagents meeting the national standard, and the water used for analysis is deionized water meeting the national laboratory standard of first grade water.

[0023] Reference pure silicon dioxide, Shanghai Zhan Yun Chemical Co., Ltd.; Anhydrous sodium carbonate, Tianjin Jin Yao Xiang Cheng Technology Co., Ltd.; Boric acid, Zhengzhou Deli Boron Industry Chemical Co., Ltd.; Hydrochloric acid, Maoming Xiongda Chemical Co., Ltd.; Ethylene glycol, Jinan Xilin Chemical Co., Ltd.; Cyclohexanone, Shandong Chuangli New Material Co., Ltd.; Glycerol, Jinan Zesheng Chemical Co., Ltd.; Dimethyl sulfoxide, Tianjin Xinsuoer Technology Co., Ltd.; Nitric acid, Maoming Xiongda Chemical Co., Ltd.; Hydrofluoric acid, Shandong Maojun Chemical Technology Co., Ltd.; Sodium hydroxide, Tianjin Jinhui Taiya Chemical Reagent Co., Ltd.; 2,4-dinitrophenol, Shandong Xiyachemical Co., Ltd.; Anhydrous ethanol, Cangzhou Zhuoya Chemical Co., Ltd. Examples

[0024] Glass fiber: brand ECS10-3.0-T436H, manufacturer Taishan Glass Fiber Co., Ltd., and the chopped length is 3mm; The method for detecting the content of unbound silane and its derivatives on the surface of glass fiber includes the following steps: S1, 50g of glass fiber to be measured is weighed and placed in a container; S2, mixing ethylene glycol and cyclohexanone according to a ratio of 3:1 to obtain a composite extraction solvent, weighing 3 times the weight of the glass fiber to obtain the composite extraction solvent, and adding the composite extraction solvent to the container to obtain an extraction solution to be extracted; S3, stirring the extraction solution to be extracted at a temperature of 80℃ for 48h, and the stirring speed is 500rpm, to obtain a mixed solution; S4, filtering the glass fiber by using a funnel filtration method or a centrifugal method to obtain an unbound silane extraction solution; S5, using a pipette to transfer 0.2ml of the unbound silane extraction solution to a digestion tank, weighing 8ml of nitric acid, 1ml of hydrochloric acid, and 1ml of hydrofluoric acid into the digestion tank, and pre-digesting at 120℃ for half an hour to obtain a pre-digested sample; S6, after pre-digestion, transferring the digestion tank to a microwave digestion device, and setting the microwave digestion process as follows: 130℃, heating time 5min, stable time 3min; 150℃, heating time 3min, stable time 10min; 180℃, heating time 3min, stable time 30min; S7, starting the microwave digestion program, and microwave digesting the pre-digested sample, and after the microwave digestion is completed, cooling to 60℃ to obtain a digestion solution; S8, using a pipette to transfer 5ml of the digestion solution to a colorimetric tube for dilution and constant volume, and the dilution multiple is 20 times, that is, to obtain a diluted digestion solution; S9, placing the diluted digestion solution into an ICP-MS sample injection system for silicon element concentration detection; S10, comparing the silicon element signal result obtained by ICP-MS test with a standard working curve of silicon to obtain the content of silicon element in the diluted digestion solution, converting the result to obtain the silicon element concentration in the unbound silane extraction solution, and finally obtaining the content result of free silicon in the glass fiber through conversion. Embodiment

[0025] The glass fiber: the brand ECS10-3.0-T436H, the manufacturer is Taishan Glass Fiber Co., Ltd., and the chopped length is 3mm; Further, the detection method of the content of unbound silane and its derivatives on the surface of the glass fiber comprises the following steps: S1, weighing 50g of the glass fiber to be measured and placing it in a container; S2, mixing dimethyl sulfoxide and glycerol according to a ratio of 5:1 to obtain a composite extraction solvent, weighing 3 times the weight of the glass fiber to obtain the composite extraction solvent, and adding the composite extraction solvent to the container to obtain an extraction solution to be extracted; S3, stirring the extraction solution to be extracted at a temperature of 80℃ for 24h, and the stirring speed is 300rpm, to obtain a mixed solution; S4, the funnel filtration method or centrifugal method is used to filter the glass fiber, and an unbound silane extraction solution is obtained; S5, 0.2ml of the unbound silane extraction solution is transferred to a digestion tank by using a pipette, 8ml of nitric acid, 2ml of hydrochloric acid, and 2ml of hydrofluoric acid are weighed into the digestion tank, and pre-digestion is performed at 120°C for half an hour to obtain a pre-digested sample; S6, after pre-digestion, the digestion tank is transferred to a microwave digestion device, and the microwave digestion process is set as follows: 130°C, 5min for temperature rising, 3min for stabilization; 150°C, 3min for temperature rising, 10min for stabilization; 180°C, 3min for temperature rising, 30min for stabilization; S7, the microwave digestion program is started, and the pre-digested sample is subjected to microwave digestion, and after the microwave digestion is completed, it is cooled to 60°C to obtain a digestion solution; S8, 5ml of the digestion solution is transferred to a colorimetric tube for dilution and constant volume by using a pipette, and the dilution multiple is 50, that is, a diluted digestion solution is obtained; S9, the diluted digestion solution is placed into an ICP-MS sample injection system for silicon element concentration detection; S10, the silicon element signal result obtained by ICP-MS testing is compared with a standard working curve of silicon, the silicon element content in the diluted digestion solution is obtained, the result is converted, the silicon element concentration in the unbound silane extraction solution is obtained, and finally the content result of free silicon in the glass fiber is obtained through conversion. Embodiment

[0026] The glass fiber: the brand ECS10-3.0-T436CP, the manufacturer is Taishan Glass Fiber Co., Ltd., and the chopped length is 3mm; Further, the detection method of the unbound silane and derivative content on the surface of the glass fiber comprises the following steps: S1, 50g of the glass fiber to be measured is weighed and placed in a container; S2, dimethyl sulfoxide and glycerol are mixed according to a ratio of 5:1 to obtain a composite extraction solvent, and the composite extraction solvent with a weight of 3 times that of the glass fiber is weighed and added to the container to obtain an extraction solution; S3, the extraction solution is stirred at 80°C for 24h, and the stirring speed is 400rpm, to obtain a mixed solution; S4, the funnel filtration method or centrifugal method is used to filter the glass fiber, and an unbound silane extraction solution is obtained; S5, 0.2ml of the unbound silane extraction solution is transferred to a digestion tank by using a pipette, 8ml of nitric acid, 2ml of hydrochloric acid, and 2ml of hydrofluoric acid are weighed into the digestion tank, and pre-digestion is performed at 120°C for half an hour to obtain a pre-digested sample; S6, after pre-digestion, the digestion tank is transferred to the microwave digestion equipment, and the microwave digestion process is set as: 130℃, 5min for temperature rising, 3min for stabilization; 150℃, 3min for temperature rising, 10min for stabilization; 180℃, 3min for temperature rising, 30min for stabilization; S7, start the microwave digestion program, and microwave digestion is performed on the pre-digested sample. After the microwave digestion is completed, it is cooled to 60℃ to obtain a digestion solution; S8, use a pipette to transfer 5ml of the digestion solution to a colorimetric tube for dilution and constant volume. The dilution factor is 50 times, and the diluted digestion solution is obtained; S9, the diluted digestion solution is placed into the ICP-MS sample injection system for silicon element concentration detection; S10, compare the silicon element signal results obtained by ICP-MS test with the standard working curve of silicon to obtain the silicon element content in the diluted digestion solution. The results are converted to obtain the silicon element concentration in the unbound silane extract solution, and finally the content of free silicon in the glass fiber is obtained through conversion.

[0027] Comparative Example 1 Glass fiber: brand ECS10-3.0-T436H, manufacturer Taishan Glass Fiber Co., Ltd., and the chopped length is 3mm; Further, the content of unbound silane and its derivatives on the surface of the glass fiber is detected by the following steps: S1, weigh 50g of the glass fiber to be measured and place it in a container; S2, weigh 3 times the weight of the glass fiber and add a sodium hydroxide solution with a concentration of 10g / L to the container. Cover the surface and immerse it in a water bath at 105℃ to obtain a dissolution solution. The sodium hydroxide solution is prepared by the following method: weigh 1g of commercially available analytical pure sodium hydroxide and add it to 50ml of water. Stir with a stirring rod until it is completely dissolved. Cool and dilute with deionized water to 100ml. Mix well; S3, take the dissolution solution, filter it with a slow quantitative filter paper after cooling, and collect the liquid in a beaker to obtain a filtrate; S4, add 2 drops of 2,4-dinitrophenol indicator with a concentration of 10g / L to the filtrate to make the filtrate yellow. Adjust the filtrate to colorless with a hydrochloric acid solution with a volume ratio of 1:1 of hydrochloric acid and water to obtain a neutralization solution. The 2,4-dinitrophenol indicator is prepared by the following method: weigh 1g of commercially available analytical pure 2,4-dinitrophenol and dissolve it in 30ml of commercially available analytical pure anhydrous ethanol. Then dilute it with the anhydrous ethanol to 100ml and mix well. The hydrochloric acid solution is prepared by mixing commercially available analytical pure hydrochloric acid and deionized water in a volume ratio of 1:1; S5, transfer 0.2ml of the neutralizing solution to the digestion tank using a pipette, and weigh 8ml of nitric acid, 2ml of hydrochloric acid, and 2ml of hydrofluoric acid into the digestion tank, and pre-digest at 120℃ for half an hour to obtain a pre-digested sample; S6, after pre-digestion, transfer the digestion tank to a microwave digestion device, and set the microwave digestion process as follows: 130℃, heating time 5min, stabilization time 3min; 150℃, heating time 3min, stabilization time 10min; 180℃, heating time 3min, stabilization time 30min; S7, start the microwave digestion program, and microwave digest the pre-digested sample, and after microwave digestion is completed, cool to 60℃ to obtain a digestion solution; S8, transfer 5ml of the digestion solution to a colorimetric tube using a pipette for dilution and constant volume, and the dilution factor is 50 times, that is, a diluted digestion solution is obtained; S9, place the diluted digestion solution into an ICP-MS sample injection system for silicon element concentration detection; S10, compare the silicon element signal results obtained by ICP-MS testing with a standard working curve of silicon to obtain the silicon element content in the diluted digestion solution, convert the results to obtain the silicon element concentration in the unbound silane extract, and finally obtain the content of free silicon in the glass fiber.

[0028] Example and comparative example data Silicon detection limit and method determination lower limit: element under test standard deviation detection limit ug / L method detection limit ug / L Si 2.3 28 44 Example and comparative example silicon element concentration test data:

[0029] As can be seen from the example and comparative example data, the detection method of the content of unbound silane and its derivatives on the surface of the glass fiber can effectively avoid damaging the structure of the glass fiber, reduce the interference of silicon elements in the glass fiber matrix on the test, and finally realize the detection of the content of unbound silane and its derivatives on the surface of the glass fiber. The detection precision of the method can reach ppb level, the standard deviation obtained by multiple detection results is small, the implementation steps are clear and convenient, and it is conducive to popularization and implementation.

[0030] The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation in the specification of the present application, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for detecting the content of unbonded silanes and their derivatives on the surface of glass fibers, characterized in that... Includes the following steps: S1. Weigh 10-100g of the glass fiber to be measured and place it in a container; S2. Weigh 2-5 times the weight of the glass fiber in the composite extraction solvent and add it to the container to obtain the extraction solution; S3. Stir the solution to be extracted at 40-80℃ for 12-48h at a stirring speed of 300-500rpm to obtain a mixed solution; S4. Filter out the glass fibers from the mixed solution obtained in the previous step to obtain unbonded silane extract; S5. Use a pipette to transfer 0.2-0.8 ml of unbonded silane extract into the digestion vessel, and weigh 5-8 ml of nitric acid, 1-2 ml of hydrochloric acid, and 1-2 ml of hydrofluoric acid into the digestion vessel. Pre-digest at 100-120℃ for half an hour to obtain the pre-digested sample. S6. After pre-digestion, transfer the digestion vessel to the microwave digestion equipment and set the microwave digestion process as follows: 120-130℃, heating time 5min, stabilization time 3min; 140-160℃, heating time 3min, stabilization time 10min; 170-180℃, heating time 3min, stabilization time 30min. S7. Start the microwave digestion program to digest the pre-digested sample using microwave. After microwave digestion is complete, cool to 60°C to obtain the digestion solution. S8. Use a pipette to transfer 5-10 ml of the digestion solution to a colorimetric tube for dilution and volume adjustment. The dilution factor is 2-50 times to obtain the diluted digestion solution. S9. Place the diluted digestion solution into the ICP-MS injection system to detect the silicon element concentration; S10. Compare the silicon element signal result obtained by ICP-MS test with the standard working curve of silicon to obtain the silicon element content in the diluted digestion solution. Convert the result to finally obtain the content result of unbonded silane and its derivatives in glass fiber.

2. The method for detecting the content of unbonded silanes and their derivatives on the surface of glass fiber according to claim 1, characterized in that, The composite extraction solvent is water, isopentane, cyclopentane, n-hexane, cyclohexane, heptane, octane, isooctane, trimethylpentane, methanol, ethanol, ethylene glycol, n-propanol, isopropanol, glycerol, n-butanol, isobutanol, acetic acid, acetonitrile, benzene, toluene, p-xylene, m-xylene, vinyltoluene, butyltoluene, styrene, phenol, aniline, petroleum ether, decahydronaphthalene, diethyl ether, isopropyl ether, pentane, acetone, methyl butyl ketone, methyl ethyl ketone, cyclohexanone, and cyclohexanone. A mixture of two or more of the following: hexanedione, ethylene glycol ether, diethanol monoethyl ether, chloromethane, dichloromethane, trichloromethane, chloroform, carbon tetrachloride, tetrachloroethylene, trichloroethylene, dichloroethane, trichloropropane, 1-chlorobutane, chlorobenzene, o-dichlorobenzene, carbon disulfide, tri-o-cresol phosphate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, tetrahydrofuran, dioxane, pyridine, acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide.

3. The method for detecting the content of unbonded silanes and their derivatives on the surface of glass fiber according to claim 1, characterized in that, The composite extraction solvent must contain at least one solvent that can form hydrogen bonds with unbonded silanes and their derivatives, and at least one solvent that has good solubility for glass fiber film-forming agents.

4. The method for detecting the content of unbonded silanes and their derivatives on the surface of glass fiber according to claim 1, characterized in that, The S4 method employs either funnel filtration or centrifugal filtration.

5. The method for detecting the content of unbonded silanes and their derivatives on the surface of glass fiber according to claim 1, characterized in that, The digestion vessel is a high-pressure digestion vessel or a polytetrafluoroethylene digestion vessel.

6. The method for detecting the content of unbonded silanes and their derivatives on the surface of glass fiber according to claim 1, characterized in that, The mixed acid solution is a mixture of one or more of the following: hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, hydrofluoric acid, and hydrobromic acid.

7. The method for detecting the content of unbonded silanes and their derivatives on the surface of glass fiber according to claim 1, characterized in that, The dilution factor for the dilution and volume adjustment is 2-10 times.

8. The method for detecting the content of unbonded silanes and their derivatives on the surface of glass fiber according to claim 1, characterized in that, The steps for creating the standard operating curve for silicon are as follows: (1) Preparation of silicon standard solution: (1) A. Burn commercially available standard pure silica at 1000°C for 1 hour, then cool and dry; (1) B. Weigh 1.0698g of the above-mentioned dried silica according to the amount of 10 g mixed flux / g sample and add it to 10.7g of anhydrous sodium carbonate and boric acid mixed flux. Heat and melt the sample at 950℃ for 15min, cool it, and obtain a molten block. The mixed flux has the following mass ratio: anhydrous sodium carbonate: boric acid = 2:

1. Grind and mix it evenly. (1) C. Place the molten block from step (1) B into water until it is completely dissolved, cool it to room temperature, and then dilute it with water to make a silicon solution of 500 ug / mL to obtain a silicon standard solution. (1) D. Take the silicon standard solution from step (1) C, dilute it with water to a silicon solution of 25 μg / mL, and store it in a plastic bottle; (2) Preparation of silicon standard working solution: (2) A. Take 0.00 mL, 0.50 mL, 1.00 mL, 2.00 mL, 3.00 mL, 4.00 mL and 5.00 mL of silicon standard solution prepared in step 1D respectively, with mass fractions of 0.00%, 0.25%, 0.50%, 1.00%, 1.50%, 2.00% and 2.50% respectively, and put them into seven 50 mL volumetric flasks. Add 5 mL of hydrochloric acid solution to each flask, dilute with water to the mark, mix well, and obtain seven 50 mL weakly acidic silicon standard solutions. The hydrochloric acid solution is commercially available hydrochloric acid with a volume ratio of 1:1 to water. (2)B. Using conventional inductively coupled plasma atomic emission spectrometry (ICP-AES) in the existing technology, the silicon spectral intensity in the seven standard solutions of step (2)A was determined. The working conditions for the determination are shown in Table 1. (2) C. Plot the standard working curve of silicon with the mass fraction of the silicon standard solution listed in step (2) A as the abscissa and the silicon strength in the standard solution obtained in step (2) B as the ordinate.

9. The method for detecting the content of unbonded silanes and their derivatives on the surface of glass fiber according to claim 8, characterized in that, The measurement conditions in step (2) are: pump speed 20 rpm, atomization speed 1 L / min, auxiliary gas 1 L / min, sample rinsing time 40 s, and radio frequency power 1550 W.

Images