Pentaerythritol for industrial use (5)

5.

5.

5.

5.

5.

Weigh about 5g of laboratory samples, accurate to 0.

5.

The mass fraction of loss on drying w ₅ , the value is expressed in %, calculated according to formula (5):

Where:

m ₁ —The value of the mass of the sample and the weighing bottle before drying, in grams (g);

m ₂ —The value of the mass of the sample and the weighing bottle after drying, in grams (g);

m—The value of the mass of the sample, in grams (g)

Take the arithmetic average of the two parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not exceed 0.

5.

Weigh about (5-20)g laboratory samples (the amount of sample is determined according to the amount of residue on ignition), accurate to 0.

Take the arithmetic mean of the two parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not exceed 0.

5.

5.

Add phthalic anhydride to the laboratory sample, and compare the color of the resultant with the standard colorimetric solution after heating

5.
7.
2 Reagents

Phthalic anhydride: Take 8g of phthalic anhydride and heat it according to the method of 5.
7.
5.
The color of the obtained phthalic anhydride should be below No.
30 (platinum-diamond color number Hazen unit)
.

5.
7.
3 Apparatus

5.
7.
3.
1 Oil bath: control the temperature at (260～265)℃;

5.
7.
3.
2 Colorimetric tube: colorless, transparent, homogeneous, of the same thickness, and of the same shape, with a volume of 25mL
.

5.
7.
4 Preparation of standard colorimetric solution

5.
7.
4.
1 Preparation of standard colorimetric stock solution: According to the volume ratio of 2:5:1 , mix the following cobalt chloride , ferric chloride , and copper sulfate solutions to obtain a standard colorimetric stock solution;

5.
7.
4.
1.
1 Cobalt chloride solution: Weigh 59.
5g of cobalt chloride (CoCl ₂ ·6H ₂ O), dissolve it with (1+39) hydrochloric acid, and dilute to 1000 mL;

5.
7.
4.
1.
2 Ferric chloride solution: Aged 45.
0g ferric chloride (FeCl ₃ ·6H ₂ O), dissolve it with (1+39) hydrochloric acid, and dilute to 1000 mL;

5.
7.
4.
1.
3 Copper sulfate solution: Weigh 62.
4g of copper sulfate (CuSO ₄ ·5H ₂ O), dissolve it with (1+39) hydrochloric acid , and dilute to 1000 mL;

5.
7.
4.
2 Standard colorimetric solution: Dilute the standard colorimetric stock solution according to the requirements in Table 3, place it in a colorimetric tube, and store it in a sealed, dark place for later use
.

Table 3 Standard colorimetric solution

5.
7.
5 Analysis steps

Weigh 3.
00g laboratory samples and 5.
40g phthalic anhydride , accurate to 0.
01g, and place them in a 25mL colorimetric tube.
Place the colorimetric tube in an oil bath at (260～265)℃ (bath liquid can be used Base silicone oil), heat for 5 minutes while oscillating, and compare the color with the standard colorimetric fluid gradation tube under the scattered light of the white background, and then compare the color with horizontal perspective to obtain the colorimetric result.

5.
8 Determination of final melting point

According to the provisions of 4.
2 in GB/T617-2006
.
First raise the temperature of the instrument quickly, when it is about 20°C from the melting point
.
Reduce the heating rate and continue heating.
When the temperature is 10°C away from the melting point, strictly control the heating rate at (1～1.
5)°C/min
.

Take the arithmetic mean of the two parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not exceed 1°C
.

6 Inspection rules

6.
1 This standard adopts type inspection and factory inspection
.

6.
1.
1 All the items in the technical requirements in Table 1 of this standard are type inspection items
.
Under normal circumstances, type inspection shall be carried out at least once every two weeks, and type inspection shall also be carried out in one of the following situations
.

a) Update key production processes;

b) The main raw materials have changed;

c) Stop production and resume production;

d) There is a big difference between the factory inspection results and the last type inspection:

e) Contract stipulations,

6.
1.
2 The pentaerythritol content, hydroxyl content, drying loss, and ignition residue in the technical requirements of Table 1 of this standard are the factory inspection items
.
Delivery and inspection are carried out for each batch
.

6.
2 Take products of the same quality as a batch, and each batch shall not exceed 601.

6.
3 The number of sampling units of pentaerythritol for industrial use shall be determined in accordance with 7.
6.
1 of GB/T6678-2003
.

6.
4 The sampling method of pentaerythritol for industrial use shall be carried out in accordance with the provisions of GB/T6679-2003
.
Sampling with an open sampling tube, the sample is evenly mixed, and the sample is reduced to about 250g by the quarter method, and divided into two clean and dry ground-mouth bottles.
Labeled, indicating the product name, batch number, sampling date, and sampling Location and name of sampler
.
One bottle is for inspection, and one bottle is kept as a reserve sample for future reference
.
The retention period of the sample is three months
.

6.
5 Pentaerythritol for industrial use should be inspected by the quality supervision and inspection department of the manufacturer
.
The manufacturer shall ensure that each batch of products manufactured meets the requirements of this standard
.
Each batch of products should be accompanied by a certificate of quality of certain formats, including: manufacturer name, product name, manufacturer of mouth or batch number, product type, net content and standard number and so on
.

6.
6 The judgment of the test result shall be carried out according to the rounding value comparison method specified in GB/T1250
.
If one of the inspection results does not meet the requirements of this standard, samples should be taken from twice the number of packaging units for inspection.
Even if only one indicator does not meet the requirements of this standard, the entire batch of products should be downgraded.
Or unqualified processing
.

7 Marking, packaging, transportation and storage

7.
1 The packaging container of pentaerythritol for industrial use should have a firm logo, which includes: product name, manufacturer name, factory address, trademark, batch number or production date, product model, net content, number of this standard and GB/T191-2008 The prescribed "fear of rain" sign
.

7.
2 Industrial pentaerythritol should be packaged in composite plastic woven bags, paper-plastic composite bags or other suitable packaging materials
.
The net content of each bag is 25kg, 500kg, 750kg, or packed according to user requirements
.

7.
3 Avoid sunlight and rain when transporting pentaerythritol for industrial use
.

7.
4 Pentaerythritol for industrial use should be stored in a dry, clean and ventilated warehouse, and should not be stacked in the open or near fire and heat sources
.

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