Trimethylolpropane for industrial use (4)

4.

4.

Using rosonic acid as an indicator, titrate the sample solution with sodium hydroxide standard titration solution to a reddish color, and calculate the free acid content in the sample by the amount of sodium hydroxide standard titration solution consumed

4.

4.

4.

4.

Weigh 0.

4.

Weigh about 5g laboratory sample, accurate to 0.

At the same time of the measurement, follow the same steps as the measurement, do a blank test with the same amount of reagent solution without adding laboratory samples

4.

The mass fraction of acidity (calculated as formic acid) w ₆ , the value is expressed in %, calculated according to formula (4):

Where:

V ₁ —The value of the volume of the sodium hydroxide standard titration solution (4.

V ₂ —The value of the volume of the standard titration solution (4.

c—The exact value of the concentration of sodium hydroxide standard titration solution, the unit is moles per liter (mol/L);

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

M— The value of the molar mass of formic acid (HCOOH), in grams per mole (g/mol) (M=46.

Take the arithmetic mean of the two parallel determination results as the report result, and the absolute difference between the two parallel determination results shall not be greater than 40% of the arithmetic mean of the two determination values
.

4.
5 Determination of residue on ignition

Weigh about 30g of laboratory sample (or determine according to the amount of burning residue), accurate to 0.
0002g
.
According to the provisions of GB/T7531-2008
.
Burning temperature (650±25)℃, burning time 1h
.

Take the arithmetic mean of the two parallel determination results as the report result, and the absolute difference between the two parallel determination results shall not be greater than 30% of the arithmetic mean of the two determination values
.

4.
6 Determination of moisture

Weigh 3g laboratory sample, accurate to 0.
0002g
.
According to the regulations of GB/T6283-2008
.

Take the arithmetic average of the two parallel determination results as the report result, and the absolute difference between the two parallel determination results shall not exceed 0.
005%
.

4.
7 Determination of final melting point

Carry out according to the provisions of 4.
2 instrument method in GB/T617-2006
.

The sample does not need to be dried
.
The initial temperature is preset to 50°C, and the heating rate is 1.
0°C/min
.
The result is directly read by the digital melting point meter
.

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

5 Inspection rules

5.
1 This standard adopts type inspection and factory inspection
.

5.
1.
1 The trimethylolpropane content, hydroxyl content, acidity, moisture, and final melting point in the technical requirements in Table 1 of this standard are the factory inspection items
.

The factory inspection is carried out once per batch
.

5.
1.
2 The appearance in the requirements of Chapter 3 of this standard and all the items in the technical requirements in Table 1 are type inspection items
.
Under normal circumstances, type inspection shall be carried out at least once every two weeks
.
Type inspection should 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
.

5.
2 The mass of each batch of industrial trimethylolpropane is not more than 20t
.

5.
3 The number of sampling units for industrial trimethylolpropane is determined in accordance with 7.
6.
1 of GB/T6678-2003
.

5.
4 The sampling method of industrial trimethylolpropane shall be carried out in accordance with the provisions of GB/T6679-2003, and the total amount of sampled products shall not be less than 500g
.
The sample is evenly mixed and reduced to 250g by quartering method.
The samples are divided into two clean and dry sampling bags.
Labels are attached to indicate the product name, batch number, sampling date, sampling location, and the name of the sampler
.
One bag is for inspection, and one bag is kept as a reserve sample for future reference
.
The retention period of the sample is three months
.

5.
5 Trimethylolpropane for industrial use should be inspected by the quality supervision and inspection department of the production plant
.
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, date of production or batch number, product level, net content and standard number and so on
.

5.
6 The test result is judged according to the rounding value comparison method specified in GB/T8170-2008
.
If one of the inspection results does not meet the requirements of this standard, it should be re-sampled from twice the number of packaging units for inspection.
If one indicator of the re-inspection does not meet the requirements of this standard, the entire batch of products is unqualified
.

6 Marking, packaging, transportation and storage

6.
1 The packaging container of trimethylolpropane for industrial use should have a firm mark, which includes: product name, manufacturer name, factory address, batch number or production date, product grade, net content, number of this standard and GB/T191- The "Fear of Rain" sign specified in 2008 and the "No Pyrotechnics" sign specified in GB13495-92
.

6.
2 Industrial trimethylolpropane 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, or it can be packed according to user requirements
.

6.
3 Avoid sunlight and rain when transporting industrial trimethylolpropane
.

6.
4 Trimethylolpropane 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
.
Do not mix with ketones and aldehydes during transportation and storage, and do not contact corrosive gases to avoid damage to the packaging or deterioration of the product
.