A method for quality control of silicone products

Abstract

The present invention relates to the technical field of quality control, and discloses a method for quality control of siloxane products, comprising the following steps: S1: Dissolve the sample, the same type of low molecular weight siloxane, and the same type of ultra-high molecular weight siloxane in low-viscosity dimethyl silicone oil respectively; S2: Taking the viscosity curves of the low molecular weight siloxane and the ultra-high molecular weight siloxane as standards, calculate the parameters respectively by the Kraemer equation method and the Huggins equation method, and compare them with the viscosity curve after dilution of the sample. If the sample is obtained by mixing two raw materials with a large difference in molecular weight, although the viscosities are the same, its viscosity-average molecular weight is greater than the requirement of the production raw materials, so that the viscosity curve of the sample changes, and the calculated intrinsic viscosity and molecular weight are greater than the predicted values. According to the deviation degree of this data, it can be judged whether the sample meets the raw material requirements. The present invention solves the problem that it is difficult to identify the raw material components.

Description

Technical Field

[0001] The present invention relates to the technical field of quality control, and particularly to a method for quality control of siloxane products. Background Art

[0002] Siloxanes have a very wide range of applications. Siloxanes can be used to manufacture various different types of chemical products and materials, including silicone rubber, silicone, diatomaceous earth, silicone oil, silicone gel, and so on. When siloxanes are used as waterproof agents, lubricants, and surface treatment agents, the quality of the raw materials is crucial for the final products. Siloxane raw materials such as dimethyl silicone oil, hydroxyl silicone oil, and vinyl silicone oil are sold by viscosity in the market. However, since the siloxane production process is mainly batch production, each batch has the same viscosity, and the market demand ranges from a viscosity of 50 to 500,000. Most manufacturers do not produce a batch of products for each viscosity. Therefore, a large amount of siloxane raw materials are mixed and blended from high and low viscosity raw materials. The randomness of such blending is extremely high. They may be of similar viscosities or have a large viscosity difference. For waterproof agents, lubricants, and surface treatment agents, their surface hydrophobicity depends on the component with the largest molecular weight (siloxanes have a characteristic that as long as a suitable solvent, temperature is provided, the molecular chain with the lowest surface energy will automatically enrich on the surface), and the durability depends on the component with the largest content. Using such blended raw materials is equivalent to changing the formula, making the product unable to achieve the ideal performance. However, the characterization of high molecular weight and molecular weight distribution is very difficult and requires a professional laboratory equipped with a gel permeation chromatography and a laser light scattering device. How to quickly analyze and detect on-site is crucial for the quality control of products.

[0003] Therefore, we have proposed a method for quality control of siloxane products to solve the problem. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] In view of the deficiencies of the prior art, the present invention provides a method for quality control of siloxane products, which solves the problems raised in the above background art.

[0006] (2) Technical Solutions

[0007] To achieve the above object, the present invention provides the following technical solutions: A method for quality control of siloxane products, comprising the following steps:

[0008] S1: Dissolve the sample, the same type of low molecular weight siloxane, and the same type of ultra-high molecular weight siloxane in low viscosity dimethyl silicone oil respectively;

[0009] S2: Taking the viscosity curves of low molecular weight siloxane and ultra-high molecular weight siloxane as standards, calculate the parameters by the Kraemer equation method and the Huggins equation method respectively, and compare them with the viscosity curve of the diluted sample. If the sample is obtained by mixing two raw materials with a large difference in molecular weight, although the viscosities are the same, its viscosity-average molecular weight is greater than the requirement of the production raw material, resulting in a change in the viscosity curve of the sample. The calculated intrinsic viscosity and molecular weight are greater than the predicted values. According to the deviation degree of this data, it can be judged whether the sample meets the raw material requirements.

[0010] Preferably, the sample can be one of siloxane products such as dimethylpolysiloxane, hydrogen-containing polysiloxane, hydroxyl-terminated polysiloxane, vinyl polysiloxane, etc.

[0011] Preferably, when the same type of low molecular weight siloxane and the same type of ultra-high molecular weight siloxane refer to the dimethylsiloxane of the sample to be measured, the same type of low molecular weight siloxane is the dimethylsiloxane with a viscosity lower than that of the sample to be measured, and the same type of ultra-high molecular weight siloxane is the dimethylsiloxane with a viscosity higher than that of the sample to be measured.

[0012] Preferably, the same type of low molecular weight siloxane generally selects siloxane with a viscosity of 1000 cs or 2000 cs, and the ultra-high molecular weight siloxane generally selects siloxane with a viscosity of 10000 - 20000 cs. It is necessary to ensure that the viscosity of the sample to be measured is between the two.

[0013] Preferably, the viscosity curve is prepared with concentrations of 1 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L. Using low-viscosity dimethylsiloxane as the solvent, 5 samples are made, and the efflux times of the solvent and the 5 samples are measured using an Ubbelohde viscometer; calculate according to the efflux times;

[0014] The efflux time of the pure solvent is t0, and the efflux times of the 1 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L samples are t1, t2, t3, t4, and t5 respectively. ηr = t / t0, ηsp = ηr - 1,

[0015] Using the Huggins formula:

[0016] Plot ηsp / c against the concentration c, and then extrapolate to c → 0. The intercept on the vertical axis is the Huggins intrinsic viscosity.

[0017] Using the Kraemer formula:

[0018] Plot lnηr / c against the concentration c, and then extrapolate to c → 0. The intercept on the vertical axis is the Kraemer intrinsic viscosity.

[0019] Preferably, according to the Mark-Houwink equation, [η] = KM η α , first take α as 0.66, calculate the K value using the Huggins intrinsic viscosity respectively, and calculate the deviation ΔK1 of the two K values. Calculate the K value using the Kraemer intrinsic viscosity respectively, and calculate the deviation ΔK1 of the two K values. If the deviation is within 5%, use the set of K values with the smaller deviation, and take the average to obtain K0. If the deviation is greater than 5%, then take α as 0.60 and 0.70 respectively, recalculate the K value according to the above process, and take the average of the set of K values with the smallest deviation to obtain K0.

[0020] Preferably, according to the Mark-Houwink equation, [η] = K0M η α , the value of the sample intrinsic viscosity is taken from the same source as K0, α is taken as 0.66, calculate the predicted value M2 of the molecular weight data corresponding to the molecular weight M1 of the sample. If the deviation between the two is within 5%, it is considered to meet the production requirements; if it exceeds 5%, it is considered that the sample may be a product of mixing high and low molecular weight raw materials. According to different types of samples and specific process requirements, the requirement of 5% can be increased or decreased to achieve the purpose of optimal quality control.

[0021] (III) Beneficial effects

[0022] Compared with the prior art, the present invention provides a method for quality control of silicone products, which has the following beneficial effects:

[0023] The present invention solves the problem that it is difficult to identify the raw material components, and can be adjusted according to different types of samples and specific process requirements, and finally can achieve the purpose of optimal quality control. Specific embodiments

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] A method for quality control of silicone products includes the following steps:

[0026] S1: Dissolve the sample, the same type of low molecular weight silicone, and the same type of ultra-high molecular weight silicone in low-viscosity dimethyl silicone oil respectively;

[0027] S2: Taking the viscosity curves of low-molecular-weight siloxane and ultra-high-molecular-weight siloxane as standards, calculate the parameters by the Kraemer equation method and the Huggins equation method respectively, and compare them with the viscosity curve of the diluted sample. If the sample is obtained by mixing two raw materials with a large difference in molecular weight, although the viscosities are the same, its viscosity-average molecular weight is greater than the requirement of the production raw material, thus causing a change in the viscosity curve of the sample. The calculated intrinsic viscosity and molecular weight are greater than the predicted values. According to the deviation degree of this data, it can be judged whether the sample meets the raw material requirements.

[0028] Among them, the sample is dimethylpolysiloxane;

[0029] When the same type of low-molecular-weight siloxane and the same type of ultra-high-molecular-weight siloxane refer to the case where the sample to be measured is dimethylsiloxane, the same type of low-molecular-weight siloxane is dimethylsiloxane with a viscosity lower than that of the sample to be measured, and the same type of ultra-high-molecular-weight siloxane is dimethylsiloxane with a viscosity higher than that of the sample to be measured;

[0030] Generally, the same type of low-molecular-weight siloxane with a viscosity of 1000 cs or 2000 cs is selected, and the ultra-high-molecular-weight siloxane with a viscosity of 10000 - 20000 cs is generally selected. It is necessary to ensure that the viscosity of the sample to be measured is between the two;

[0031] The viscosity curve is prepared with concentrations of 1 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L. Using low-viscosity dimethylsiloxane as the solvent, 5 samples are made, and the efflux times of the solvent and the 5 samples are measured using an Ubbelohde viscometer; calculated according to the efflux time;

[0032] The efflux time of the pure solvent is t0, and the efflux times of the 1 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L samples are t1, t2, t3, t4, and t5 respectively. ηr = t / t0, ηsp = ηr - 1,

[0033] Using the Huggins formula:

[0034] Plot ηsp / c against the concentration c, and then extrapolate to c→0. The intercept on the vertical axis is the Huggins intrinsic viscosity,

[0035] Using the Kraemer formula:

[0036] Plot lnηr / c against the concentration c, and then extrapolate to c→0. The intercept on the vertical axis is the Kraemer intrinsic viscosity;

[0037] According to the Mark-Houwink equation, [η] = KM η α, first take the value of α as 0.66, calculate the K value using the Huggins intrinsic viscosity respectively, and calculate the deviation ΔK1 of the two K values. Calculate the K value using the Kraemer intrinsic viscosity respectively, and calculate the deviation ΔK1 of the two K values. If the deviation is within 5%, use the set of K values with the smaller deviation, and take the average to obtain K0. If the deviation is greater than 5%, then take the values of α as 0.60 and 0.70 respectively, recalculate the K value according to the above process, take the set of K values with the smallest deviation, and take the average to obtain K0;

[0038] According to the Mark-Houwink equation, [η] = K0M η α , the value of the sample intrinsic viscosity is taken from the same source as K0, the value of α is taken as 0.66, calculate the predicted value M2 of the molecular weight corresponding to the molecular weight M1 of the sample. If the deviation between the two is within 5%, it is considered to meet the production requirements; if it exceeds 5%, it is considered that the sample may be a product mixed with high and low molecular weight raw materials. According to different types of samples and specific process requirements, the requirement of 5% can be increased or decreased to achieve the purpose of optimal quality control.

[0039] Experimental example:

[0040] Quality control method for hydroxy silicone oil

[0041] The purpose is to test whether the hydroxy silicone oil sample with a viscosity of 5000 cs is a blended product.

[0042] Take hydroxy silicone oil with viscosities of 1000 cs and 10000 cs as low molecular weight siloxane and extremely high molecular weight siloxane;

[0043] Using 1000 cs hydroxy silicone oil, 10000 cs hydroxy silicone oil, and the hydroxy silicone oil sample as solutes, and 50 cs silicone oil as the solvent, prepare corresponding solutions with concentrations of 1 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L respectively;

[0044] Use an Ubbelohde viscometer to measure the outflow times of the solvent and 15 samples. The outflow time of the pure solvent is t0, and the outflow times of the 1 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L samples are t1, t2, t3, t4, and t5 respectively. ηr = t / t0, ηsp = ηr - 1,

[0045] Use the Huggins formula:

[0046] Plot ηsp / c against the concentration c, and then extrapolate to c → 0. The intercept on the vertical axis is the Huggins intrinsic viscosity,

[0047] Use the Kraemer formula:

[0048] Plot lnηr / c against the concentration c and then extrapolate to c→0. The intercept on the vertical axis is the Kraemer intrinsic viscosity.

[0049] The Kraemer intrinsic viscosities of the 2000 cs hydroxyl silicone oil, 10000 cs hydroxyl silicone oil, and the hydroxyl silicone oil sample were calculated to be 25.1, 41.8, and 39.8 respectively.

[0050] According to the Mark-Houwink equation, [η] = KMηα. The molecular weight of the 2000 cs hydroxyl silicone oil was found to be 28000, the molecular weight of the 10000 cs hydroxyl silicone oil was 62700, and the predicted molecular weight of the hydroxyl silicone oil sample was 49300 in Table 1.

[0051] Taking α as 0.66 first, the K values were calculated to be 0.0291 and 0.0285 respectively, and the deviation of 2.2% was within the range. The average value was taken as 0.288.

[0052] According to the Mark-Houwink equation, [η] = K0Mηα, where K0 = 0.288 and α = 0.66.

[0053] The molecular weight of the hydroxyl silicone oil sample was 57321, with a 15% deviation compared to the predicted value of 49300. This sample may be a blended product and does not meet the production requirements.

[0054] Viscosity Molecular weight 20 2,000 50 3800 100 6,000 200 9,400 350 13,700 500 17,300 1,000 28,000 5,000 49,300 10,000 62,700 12,500 67,700 30,000 91,700 60,000 116,500 100,000 139,000 300,000 204,000 600,000 260,000 4,000,000 400,000 20,000,000 550,000

[0055] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for quality control of polysiloxane products, characterized in that, Including the following steps: S1: Dissolve the sample, the same type of low molecular weight polysiloxane, and the same type of ultra-high molecular weight polysiloxane in low-viscosity dimethyl silicone oil respectively; S2: Taking the viscosity curves of the low molecular weight polysiloxane and the ultra-high molecular weight polysiloxane as standards, calculate the parameters respectively by the Kraemer equation method and the Huggins equation method, and compare them with the viscosity curve of the diluted sample. If the sample is obtained by mixing two raw materials with a large difference in molecular weight, although the viscosities are the same, its viscosity-average molecular weight is greater than the requirement of the production raw material, so the viscosity curve of the sample changes, and the calculated intrinsic viscosity and molecular weight are greater than the predicted values. Judge whether the sample meets the raw material requirements according to the deviation degree of this data; The viscosity curve is prepared by using low-viscosity dimethyl silicone as a solvent, making 5 samples with concentrations of 1 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L, measuring the efflux times of the solvent and the 5 samples using an Ubbelohde viscometer, and calculating η based on the efflux times. r and η sp , The efflux time of the pure solvent is t0, and the efflux times of the samples with concentrations of 1 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L are t1, t2, t3, t4, and t5 respectively. η r = t / t0, η sp = η r - 1, Using the Huggins formula: ; Using η sp Plot η / c against the concentration c and then extrapolate to c → 0. The intercept on the vertical axis is then the Huggins intrinsic viscosity, Using Kraemer's formula: ; Plot with ln ηr / c against concentration c and then extrapolate to c → 0. The intercept on the vertical axis is then the Kraemer intrinsic viscosity; According to the Mark-Houwink equation, [η] = KM η α , first take the value of α as 0.66, calculate the K value using the Huggins intrinsic viscosity respectively, and calculate the deviation ΔK1 of the two K values. Calculate the K value using the Kraemer intrinsic viscosity respectively, and calculate the deviation ΔK1 of the two K values. If the deviation is within 5%, use the set of K values with the smaller deviation, and take the average to obtain K0. If the deviation is greater than 5%, then take the values of α as 0.60 and 0.70 respectively, recalculate the K value according to the above process, and take the average of the set of K values with the smallest deviation to obtain K0; According to the Mark-Houwink equation, [η] = K0M η α , the intrinsic viscosity value of the sample is taken from the same source as K0, α is taken as 0.66, and the predicted value M2 of the molecular weight corresponding to the molecular weight M1 of the sample is calculated. If the deviation between the two is within 5%, it is considered to meet the production requirements; if it exceeds 5%, the sample may be a product of mixing high and low molecular weight raw materials. According to different types of samples and specific process requirements, the requirement of 5% is adjusted up or down to achieve the purpose of optimal quality control.

2. The quality control method of a polysiloxane product according to claim 1, characterized in that, The sample is one of the products of polydimethylsiloxane, hydroxy-terminated polysiloxane, and vinyl polysiloxane.

3. A method for controlling the quality of a polysiloxane product according to claim 1, characterized in that, When the sample to be tested is polydimethylsiloxane, the same type of low molecular weight polysiloxane is polydimethylsiloxane with a viscosity lower than that of the sample to be tested, and the same type of ultra-high molecular weight polysiloxane is polydimethylsiloxane with a viscosity higher than that of the sample to be tested.

4. A method for controlling the quality of a polysiloxane product according to claim 1, characterized in that, The same type of low molecular weight polysiloxane selects polysiloxane with a viscosity of 1000 cs or 2000 cs, and the ultra-high molecular weight polysiloxane selects polysiloxane with a viscosity of 10000 - 20000 cs. It is necessary to ensure that the viscosity of the sample to be tested is between the two.

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