GB/T 5761-2018Suspension polyvinyl chloride resins of general purpose (English PDF)

6.1 Appearance

Visually observe under natural light or carry out in accordance with the provisions of GB/T 2913 agreed by the supplier and the purchaser.

6.2 Determination of viscosity number, K value and average degree of polymerization

6.2.1 Description of determination method

Select one of the methods for measuring viscosity number, K value and average degree of polymerization. Of which, GB/T 3401 is the arbitration method.

6.2.2 Determination of viscosity number

According to the provisions of GB/T 3401.

6.2.3 Determination of K value

According to the provisions of GB/T 3401.

6.2.4 Determination of average degree of polymerization

According to the provisions of Annex A.

6.3 Determination of the number of impurity particles

According to the provisions of GB/T 9348. It can also be measured by instrumental method. Of which, GB/T 9348 is the arbitration method.

6.4 Determination of volatile matter (including water)

According to the provisions of GB/T 2914. The sample heating temperature is (110±2)°C. The time is 1h. Calculate the result according to the weight loss of 1h.

6.5 Determination of apparent density

According to the provisions of GB/T 20022.

6.6 Determination of sieve residues

According to the provisions of GB/T 2916 or GB/T 21843. Of which, GB/T 2916 is the arbitration method.

6.7 Determination of "fisheyes" number

According to the provisions of GB/T 4611.

6.8 Determination of absorption of 100g of resin plasticizer

According to the provisions of GB/T 3400.

6.9 Determination of whiteness (160°C, 10min)

According to the provisions of GB/T 15595. The sample is heated at (160±1)°C for 10min.

6.10 Determination of conductivity of water extracts

According to the provisions of GB/T 2915.

6.11 Determination of residual vinyl chloride monomer

According to the provisions of GB/T 29874.

6.12 Determination of dry flow

According to the provisions of GB/T 21060.

7.1 Inspection classification and inspection items

7.1.1 Inspection classification

Inspection classification: exit-factory inspection and type inspection.

7.1.2 Exit-factory inspection

The appearance, viscosity number (or K value, average degree of polymerization), number of impurity particles, volatile matter (including water), apparent density, and number of "fisheyes" specified in this Standard are the exit-factory inspection items. They shall be inspection in batches.

7.1.3 Type inspection

All the inspection items specified in this Standard are type inspection items. Under normal production conditions, type inspection shall be conducted at least once every three months.

In one of the following situations, type inspection shall also be carried out:

- when the key production process has changed;

- when the main raw materials have changed;

- when the production is resumed after production is shut downed;

- when production equipment has significant fluctuations / is adjusted.

When the type inspection does not meet the requirements of this Standard, it shall be inspected for each batch. The normal inspection can only be carried out until the inspection results of five consecutive batches meet the standard requirements.

7.2 Rules for determination and reinspection

7.2.1 Rules for determination

7.2.1.1 The product quality index shall be determined according to the "rounding-off value comparison method" stipulated in GB/T 8170.

7.2.1.2 Products shall be inspected by the quality inspection department of the manufacturer according to the provisions of this Standard. Make quality judgments on products based on inspection results and standard requirements. Provide proof of quality.

7.2.1.3 When the products leave the factory, each batch of products shall be accompanied by a quality certificate. The content of the quality certificate includes manufacturer name, product name, model, grade, batch number or production date, batch size, product quality certificate of compliance with this Standard, implementation standard number. Stamp with the enterprise quality inspection seal.

7.2.2 Reinspection rules

If one of the indicators in the inspection results does not meet the requirements of this Standard, it shall be re-inspected by sampling from the batch of products with double the number of sampling units. Even if one of the indicators in the re-inspection results does not meet the requirements of this Standard, the batch of products is unqualified.

8.1 Marks

There shall be a firm and obvious mark on the outer packaging of the exit-factory products, indicating manufacturer name, address, product name, model, net content, batch number or production date, and the serial number of this Standard. The packaging shall also have the sign of "Afraid of Rain" stipulated in GB/T 191.

A.3 Preparation of sample solution

Weigh (200±0.1)mg of sample. Place in a 50mL volumetric flask with a glass stopper.

Add about 40mL of nitrobenzene. Heat the volumetric flask in a glycerin bath at (100±2)°C. Shake the volumetric flask intermittently to dissolve the sample completely.

Take out the volumetric flask. Cool to room temperature. Then put it in a constant temperature water bath at (30±0.05)°C for about 20min. Dilute to the mark with nitrobenzene at the same temperature. Shake well for future use.

A.4 Test steps

A.4.1 Determination of solvent flowing time

A.4.1.1 Connect latex tubes to viscometer tube 2 and tube 3 respectively. Place the viscometer vertically in a constant temperature water bath at (30±0.05)°C. Make the liquid level exceed ball C of the viscometer.

A.4.1.2 Use a glass sand core funnel to filter the solvent nitrobenzene (hereinafter referred to as solvent) through tube 1 into ball A of the viscometer, until the liquid level of the solvent is between the two scale lines of ball A. Keep at constant temperature for about 10min.

A.4.1.3 Close tube 3 and pipette 2 to allow the solvent to slowly enter ball B through the capillary. When the solvent level rises to half of ball C, stop aspiration. Open tube 3. Measure the elapsed time from the upper scale line to the lower scale line of the solvent ball B.

A.4.1.4 Repeat the measurement of flowing time three times. Take the arithmetic mean value as the flowing time of the solvent.

A.4.2 Determination of flowing time of sample solution

A.4.2.1 Suck out the above solvent. Filter about 15mL of the sample solution (A.3) into the viscometer through a glass sand core funnel. Rinse the sample solution through ball B three times and then suck it out. Then filter the remaining sample solution into the viscometer ball A through the glass sand core funnel through tube 1. Keep at the constant temperature for about 10min.

A.4.2.2 Measure the flowing time of the sample solution according to A.4.1.3.

A.4.2.3 Repeat the measurement of the sample solution flowing time twice. Take the arithmetic mean value as the flowing time of the sample solution. […]