PVC glue type determination method based on viscosity number detection

Abstract

The invention discloses a PVC glue model determination method based on viscosity number detection, which comprises the following steps: washing a glue sample for multiple times by using absolute ethyl alcohol to obtain high-purity PVC resin, drying the high-purity PVC resin, weighing a small amount of the dried high-purity PVC resin as a PVC resin sample, dissolving the PVC resin sample in cyclohexanone in a heating water bath environment, cooling, determining viscosity number data by using a Ubbelohde viscometer, and determining the model number of the PVC glue according to the viscosity number data. According to the method, special glue cleaning equipment is designed, the PVC resin sample is high in purity and free of residues, the method has the advantages of being accurate in data and scientific in judgment method, the standardized detection method for the viscosity number of the PVC resin in the glue is established, the industry blank is filled, and the method is suitable for popularization and application. And scientific and reasonable use of the PVC glue by enterprises is facilitated.

Description

Technical Field

[0001] This invention relates to the field of adhesive type testing equipment, and more specifically, to a method for determining the type of PVC adhesive based on viscosity number testing. Background Technology

[0002] In recent years, the demand for PVC pipes has grown rapidly in fields such as construction, industrial wastewater treatment, and agricultural irrigation. PVC adhesive, as a single-component transparent solution, has become a core material for cross-bonding PVC pipes with metal / non-metal materials due to its high bonding strength, corrosion resistance, and rapid curing characteristics. With the rapid development of PVC pipe applications, the performance requirements for PVC adhesives are becoming increasingly stringent. In PVC adhesives, the molecular weight difference of PVC resin can affect the flow properties and bonding effect to a certain extent. Based on the viscosity of PVC resin, it can be divided into several grades from SG1 to SG9. Currently, the viscosity grades of PVC adhesives purchased on the market are not clearly specified. Before actual use, it is necessary to determine the grade to ensure that it is used in the appropriate application. Regarding the determination of PVC adhesive grades, the industry currently faces the following technical bottlenecks:

[0003] (1) Lack of standardized testing methods: Existing methods only evaluate the performance of adhesives through experience or simple direct viscosity tests, which cannot quantify the accurate viscosity number (K ​​value) of PVC resin, resulting in a lack of scientific basis for the selection and use of adhesives;

[0004] (2) Residual interference: In the existing viscosity number detection methods, the PVC resin in PVC glue is difficult to refine, resulting in poor purity. At present, there is no special equipment for PVC resin purification on the market. The sample mass required for testing needs to be 0.125g±0.025g, which results in a large sample amount and difficulty in dissolving. In addition, the residual additives and solvents interfere with and affect the final measurement accuracy, leading to errors in the determination of PVC glue type. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for determining the type of PVC adhesive based on viscosity number detection. This invention refines PVC resin by repeatedly washing the PVC adhesive with anhydrous ethylene glycol. The refined PVC resin has no residual interference. The refined PVC resin can be dissolved in cyclohexanone after drying for viscosity measurement. This invention establishes a standardized detection method for the viscosity number of PVC resin in adhesives, filling a gap in the industry.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for determining the type of PVC adhesive based on viscosity number detection includes the following steps:

[0008] S1. Place the glue sample in a container and load the glue sample into the glue cleaning device.

[0009] S2. Use ethylene glycol to clean the glue sample and collect the white solid substance precipitated during cleaning. The white solid substance is PVC resin.

[0010] S3. Take out the PVC resin and place it in the drying oven to dry;

[0011] S4. After drying and cooling the sample, weigh 0.0600±0.0005g of the sample and place it into the container bottle;

[0012] S5. Add 20 mL of cyclohexanone and heat it in a water bath at a constant temperature to dissolve the PVC resin sample in cyclohexanone.

[0013] S6. Cool to a constant temperature in a water bath, and use an Ubbelohde viscometer to measure the viscosity data. Determine the type of PVC adhesive based on the viscosity data.

[0014] Furthermore, the amount of glue sample used in step S1 is 5g.

[0015] Furthermore, the ethylene glycol in step S2 has a purity of ≥99.5%, and the ethylene glycol washing is performed three times.

[0016] Furthermore, the drying temperature of the drying oven in step S3 is set to 105±2℃.

[0017] Furthermore, in step S4, the sample cooling temperature is 25±1℃, and the sample is weighed using a precision balance of 0.01%.

[0018] Furthermore, in step S5, the water bath constant temperature is set to 80-85℃, and the water bath constant temperature duration is set to 1 hour.

[0019] Furthermore, the water bath cooling constant temperature in step S6 is set to 25±1℃.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention refines PVC resin by repeatedly washing PVC glue with anhydrous ethylene glycol. The refined PVC resin has no residual interference. The refined PVC resin can be dissolved in cyclohexanone after drying for viscosity measurement. Due to the high purity of the refined PVC resin, this invention can be used for small sample measurement, shortening the measurement time and improving the measurement accuracy.

[0022] 2. This invention establishes a standardized testing method for the viscosity of PVC resin in adhesives, filling a gap in the industry and helping enterprises to use PVC adhesives scientifically and rationally. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the internal structure of an adhesive cleaning device in this embodiment;

[0024] Figure 2 for Figure 1 Enlarged view of point A in the image.

[0025] Reference numerals: Upper body 1, Cleaning chamber 11, Liquid inlet pipe 12, Liquid collection slope 13, Liquid outlet hole 14, Annular seat 15, Positioning pin 16, Lower body 2, Drainage chamber 21, Drainage outlet pipe 22, Material trough 3, Filter screen 31, Suspension flange 32, Piston 4, Drainage channel 41, Push cylinder 42, Stirring mechanism 5, Stirring blade 51, Stirring shaft 52, Rotary seal 521, Motor 53, Cover 6, Liquid level gauge 61, Observation window 62. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] A method for determining the type of PVC adhesive based on viscosity number detection includes the following steps:

[0028] S1. Take 5g of glue sample and place it in a container. Put the glue sample into the glue cleaning device.

[0029] S2. Use ethylene glycol with a purity of ≥99.5% (called anhydrous ethylene glycol) to clean the glue sample. The cleaning process involves stirring and is repeated three times to ensure that the additives and solvents in the glue are dissolved and removed, leaving only white solids. Collect the white solids that have been precipitated. The white solids are high-purity PVC resin with no additives or solvents remaining.

[0030] S3. Take out the PVC resin and place it in the drying oven to dry it. The drying temperature of the drying oven is set to 105±2℃. Drying is to allow the ethylene glycol residue on the PVC resin to evaporate and be removed quickly.

[0031] S4. Cool the dried PVC resin sample to 25±1℃, and then weigh 0.0600±0.0005g of the sample using a precision balance (0.0001g).

[0032] S5. Add 20mL of cyclohexanone to the container and place it in a water bath for constant temperature heating to promote the dissolution of PVC resin sample in cyclohexanone. Set the water bath temperature to 80-85℃ and the water bath time to 1 hour.

[0033] S6. Cool to a constant temperature in a water bath. The constant temperature of the water bath is set to 25±1℃. Then, use an Ubbelohde viscometer to measure the viscosity data. Determine the type of PVC glue based on the viscosity data (using an Ubbelohde viscometer to measure the viscosity data is an existing technology specified in the current standard, and will not be described in detail here).

[0034] This invention designs and uses an adhesive cleaning device in the above-mentioned method for determining the type of PVC adhesive based on viscosity number detection, specifically in steps S1 and S2.

[0035] In the above method for determining the type of PVC adhesive, the adhesive cleaning process in step S2 is crucial, as it directly affects the accuracy of the final test data. Therefore, as follows... Figure 1 and Figure 2 As shown, this invention designs an adhesive cleaning device, including an upper body 1, a lower body 2, a material tank 3, and a stirring mechanism 5. The lower body 2 is fixedly connected to the lower part of the upper body 1. The upper body 1 is provided with a cleaning working chamber 11, and the lower body 2 is provided with a draining chamber 21. A piston 4 with lifting and lowering motion is installed in the draining chamber 21. The lifting and lowering motion of the piston 4 controls the communication relationship between the cleaning working chamber 11 and the draining chamber 21. The material tank 3 is used to hold adhesive samples and is fixedly installed in the cleaning working chamber 11. Ethylene glycol is added to the cleaning working chamber 11 to immerse the adhesive samples. The stirring mechanism 5 includes a stirring blade 51 rotatably installed below the material tank 3. The stirring blade 51 agitates the ethylene glycol, causing it to wash and clean the adhesive samples in the material tank 3.

[0036] In this invention, the top of the upper body 1 is open to facilitate the handling of the material tank 3. The top of the upper body 1 is closed by a cover 6. A liquid inlet pipe 12 is connected to the side wall of the upper body 1, which is connected to an ethylene glycol inlet pipe. Ethylene glycol with a purity ≥99.5% is introduced for cleaning. During the cleaning operation, the connection between the cleaning chamber 11 and the drain chamber 21 is cut off. As ethylene glycol is continuously introduced, the glue sample in the material tank 3 is submerged. A level gauge 61 is installed in the cleaning chamber 11 (in this invention, it is installed inside the cover 6 and takes effect when the cover 6 is installed). The maximum liquid level is controlled by the level gauge 61. Under the stirring action of the mixing blade 51, ethylene glycol continuously washes and cleans the glue sample in the material tank 3, dissolving and removing the additives and solvents in the glue, leaving the PVC resin component to precipitate. The material tank 3 of this invention contains only 5g of glue sample. A filter screen 31 is installed at the bottom of the material tank 3. The glue sample cannot pass through the filter screen 31, but ethylene glycol can pass through the filter screen 31 and immerse the glue. The components dissolved in ethylene glycol can be carried away by ethylene glycol, while the precipitated PVC resin component is in a white solid state and cannot pass through the filter screen 31. Therefore, after the final cleaning is completed, as long as the material tank 3 is removed, a high-purity PVC resin sample in a white solid state can be easily obtained.

[0037] like Figure 1 As shown, an annular seat 15 is fixedly installed on the inner wall of the cleaning operation chamber 11. Two vertical positioning pins 16 are symmetrically installed on the annular seat 15. The top of the material trough 3 is turned outward to form a ring of suspension flange 32. The material trough 3 is placed on the annular seat 15 through the suspension flange 32. The suspension flange 32 is positioned and inserted with the two positioning pins 16 to ensure reliable installation of the material trough 3.

[0038] like Figure 1As shown, a liquid collection slope 13 is formed at the bottom of the cleaning chamber 11. This slope allows the ethylene glycol cleaning solution to converge towards the lowest point of the bottom of the cleaning chamber 11. Several outlet holes 14 are located at the lowest point of the bottom of the cleaning chamber 11, connecting to the drainage chamber 21 of the lower body 2. The outer diameter of the piston 4 is adapted to the inner diameter of the drainage chamber 21. When the piston 4 moves upward to its upper limit position, all the outlet holes 14 are closed, thus sealing the cleaning chamber 11 and allowing cleaning operations to proceed. After cleaning, the ethylene glycol cleaning solution needs to be drained to obtain a high-purity PVC resin sample. At this point, the piston 4 can be lowered. After the piston 4 descends, the lower end of the outlet holes 14 is no longer closed, allowing ethylene glycol to enter the drainage chamber 21. This invention features a vertically penetrating drainage channel 41 in the center of the piston 4. Ethylene glycol falls into the space below piston 4 through drainage channel 41. Drainage outlet pipe 22 is connected to the bottom of the lower body 2. Ethylene glycol is discharged through drainage outlet pipe 22. During the drainage process, the liquid level in the cleaning chamber 11 drops rapidly, eventually draining all the ethylene glycol. In order to ensure that high-purity PVC resin samples are obtained, the number of ethylene glycol cleaning operations is set to three, and the cleaning time for each operation is set to 15-30 minutes. Only after the last cleaning operation is completed is it allowed to open the cover 6 to remove the material tank 3. In this invention, a push cylinder 42 is installed in the lower body 2. The piston rod end of the push cylinder 42 is connected to a push rod, and the upper end of the push rod is connected to piston 4. The piston 4 is raised and lowered by the extension and retraction of the piston rod of the push cylinder 42. During the cleaning operation, the piston rod of the push cylinder 42 is kept in the maximum extension state so that piston 4 continuously closes the liquid outlet hole 14.

[0039] like Figure 1 As shown, the stirring mechanism 5 also includes a stirring shaft 52 and a motor 53. The motor 53 is installed at the bottom of the lower body 2. The stirring shaft 52 is connected to the output end of the motor 53. The top of the stirring shaft 52 extends to the cleaning operation chamber 11. The stirring blades 51 are installed at the top of the stirring shaft 52. The stirring shaft 52 is driven to rotate by starting the motor 53, which in turn drives the stirring blades 51 to stir the ethylene glycol. The stirring shaft 52 is installed through the bottom of the lower body 2. A rotary seal 521 is installed at the through-hole to prevent liquid leakage without affecting the stirring rotation. The present invention has an observation window 62 installed on the cover 6, through which the cleaning operation can be observed in real time.

[0040] The PVC resin sample cleaned by the glue cleaning device of this invention has the advantage of high purity, with no additives or solvent residues. Therefore, a small sample size can be used for subsequent determination. The amount of PVC resin sample can be reduced to 0.0600±0.0005g, which helps the PVC resin sample to dissolve quickly and completely in cyclohexanone, ensuring the accuracy of subsequent viscosity measurement data.

[0041] The method of this invention can accurately determine the PVC resin viscosity data of the glue sample, thereby determining the specific type of PVC glue. The unit of PVC resin viscosity is mL / g. Common viscosity ranges for different types include SG5 (107-118), SG7 (87-95), and SG8 (73-86).

[0042] In this invention, acetone can be used instead of anhydrous ethanol for cleaning, but acetone is highly volatile and requires more than four cleaning cycles. Tetrahydrofuran (THF) can be used instead of cyclohexanone to dissolve PVC resin samples, but this reagent has a low dissolution rate for PVC resin (requiring an extended dissolution time of up to 90 minutes) and high toxicity (requiring a closed dissolution system for operation).

[0043] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the type of PVC adhesive based on viscosity number detection, characterized in that, Includes the following steps: S1. Place the glue sample in a container and load the glue sample into the glue cleaning device. S2. Use ethylene glycol to clean the glue sample and collect the white solid substance precipitated during cleaning. The white solid substance is PVC resin. S3. Take out the PVC resin and place it in the drying oven to dry; S4. After drying and cooling the sample, weigh 0.0600±0.0005g of the sample and place it into the container bottle; S5. Add 20 mL of cyclohexanone and heat it in a water bath at a constant temperature to dissolve the PVC resin sample in cyclohexanone. S6. Cool to a constant temperature in a water bath, and use an Ubbelohde viscometer to measure the viscosity data. Determine the type of PVC adhesive based on the viscosity data.

2. The method for determining the type of PVC adhesive based on viscosity number detection according to claim 1, characterized in that, The amount of glue sample used in step S1 is 5g.

3. The method for determining the type of PVC adhesive based on viscosity number detection according to claim 1, characterized in that, The ethylene glycol in step S2 has a purity of ≥99.5%, and the ethylene glycol washing is performed three times.

4. The method for determining the type of PVC adhesive based on viscosity number detection according to claim 1, characterized in that, The drying temperature of the drying oven in step S3 is set to 105±2℃.

5. The method for determining the type of PVC adhesive based on viscosity number detection according to claim 1, characterized in that, In step S4, the sample cooling temperature is 25±1℃, and the sample is weighed using a precision balance of 0.01%.

6. The method for determining the type of PVC adhesive based on viscosity number detection according to claim 1, characterized in that, In step S5, the water bath temperature is set to 80-85℃ and the water bath duration is set to 1 hour.

7. The method for determining the type of PVC adhesive based on viscosity number detection according to claim 1, characterized in that, The water bath cooling constant temperature in step S6 is set to 25±1℃.

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