GB/T 12028-2026Sodium carboxymethylcellulose for detergents (English PDF)

5.2 Purity

5.2.1 Reagents Unless otherwise specified, only reagents confirmed to be of analytical grade shall be used in the analysis; the water used in the tests shall comply with the requirements of GB/T 6682.Reagents as follows:

a) Potassium iodide (KI);

5.2.2 Procedure Weigh

3.6 g of potassium iodide [5.2.1a)], dissolve it in 20 mL of water, add

1.3 g of iodine [5.2.1b)], dissolve it, and then dilute it with water to the specified concentration. 100 mL. This solution is an iodine test solution. Add 50 mL of water to

0.5 g of sample to dissolve and obtain the sample solution. Take 5 mL of the sample solution, add 1 drop of iodine test solution, and observe the sample. The solution color changes.

5.3 Moisture and volatile matter The moisture and volatile matter content were determined according to the specifications in GB/T 13173.The test sample weighed 4g, and the weighing bottle specifications were as follows: phi60mm×25mm.

5.4 Viscosity

5.4.1 Principle The viscosity of a sodium carboxymethyl cellulose solution was determined using a prescribed rotational viscometer. The viscosity of the solution is related to the rotation of the cylinder of the rotational viscometer in the solution. The shear stress generated by rotation is a function of the applied shear rate.

5.4.2 Reagents Unless otherwise specified, only reagents confirmed to be of analytical grade shall be used in the analysis; the water used in the test shall comply with the requirements of GB/T 6682.

5.4.3 Instruments The required experimental equipment is as follows:

a) A rotational viscometer with a measuring range of 5 mPa·s to 50 mPa·s and a shear rate of 850 s^-1;

b) Super constant temperature water bath, capable of maintaining the temperature at 25°C±1°C;

c) Volumetric flask, 100 mL;

d) Beaker, 100mL.

5.4.4 Procedure The test procedure includes...

a) Preparation of the test solution. Weigh approximately 1 g of the sample (accurate to

0.001

g) (on a dry basis) into a beaker [5.4.3d], add water and stir vigorously to make it flowable. Transfer the turbid solution to a 100 mL volumetric flask [5.4.3c). Rinse the beaker [5.4.3d] and glass rod with a small amount of water each time. Next, add the rinsing solution to the volumetric flask and shake vigorously for 15 minutes.

b) Measurement. Place the test solution [5.4.4a)] in a constant temperature water bath [5.4.3b)] at 25°C±1°C for 20 minutes, then remove and dilute with water to the specified concentration. Shake vigorously for 1 minute. Then place in a constant temperature water bath for 10 minutes, remove and shake well. Select a measurement range of [range to be specified]. For a rotating drum with a pressure of 5 mPa·s to 50 mPa·s [5.4.3a], after wetting and rinsing the rotating drum and measuring container with a small amount of test solution, proceed according to the viscometer... [5.4.3a)] Use the instructions to determine the viscosity of the test solution. Start reading the value 30 seconds after the pointer stabilizes during rotation of the rotating drum, and then repeat every 10 seconds thereafter. Read the value once, until you get five consecutive unchanging readings.

5.4.5 Result Calculation The viscosity (eta) of the sample solution is calculated according to formula (1).

5.4.6 Precision The difference between two independent measurements obtained under repeatability conditions should not exceed 5% of the average value, and in cases where it exceeds 5%, it should not exceed [a certain percentage]. The premise is 5%.

5.6 Degree of etherification

5.6.1 Principle The water-soluble sodium carboxymethyl cellulose was acidified to become insoluble acid carboxymethyl cellulose. After purification, it was treated with an accurately measured amount of excess hydroxide. Sodium chloride is used to convert a known amount of acidic carboxymethyl cellulose back into sodium salt, and then the excess alkali is titrated with a standard hydrochloric acid solution.

5.6.2 Reagents Unless otherwise specified, only reagents confirmed to be of analytical grade shall be used in the analysis; the water used in the tests shall comply with the requirements of GB/T 6682.Reagents as follows:

a) 95% ethanol (CH3CH2OH);

b) Ethanol (CH3CH2OH), 80% solution. Dilute 840 mL of 95% ethanol [5.6.2a)] with water to 1 L;

c) Anhydrous methanol (CH3OH);

d) Nitric acid (HNO3);

e) Hydrochloric acid (HCl) standard titration solution, c(HCl) =

0.4 mol/L, prepared and standardized according to QB/T 2739;

f) Sodium hydroxide (NaOH) standard titration solution, c(NaOH) =

0.4 mol/L, prepared and standardized according to QB/T 2739;

g) Sulfuric acid (H2SO4) solution, prepared according to a volume ratio of concentrated sulfuric acid to water of 9.2;

h) Diphenylamine (C12H11N) reagent. Dissolve

0.5 g of diphenylamine in 120 mL of sulfuric acid solution [5-

6.2 g). This reagent should be colorless and react with sulfuric acid. It turns deep blue when trace amounts of nitrates and other oxidizing agents are present;

5.7 Active Ingredients

5.7.1 Principle Sodium carboxymethyl cellulose is insoluble in 80% ethanol. After dissolving and washing repeatedly, the 80% ethanol residue in the sample was removed, yielding a pure product. Sodium carboxymethyl cellulose.

5.7.2 Reagents Unless otherwise specified, only reagents confirmed to be of analytical grade shall be used in the analysis; the water used in the tests shall comply with the requirements of GB/T 6682.Reagents as follows:

a) 95% ethanol (CH3CH2OH);

b) Ethanol (CH3CH2OH), 80% solution. Dilute 840 mL of 95% ethanol [5.7.2a)] with water to 1 L;

c) Diethyl ether (CH3OCH3).

5.7.3 Instruments The required experimental equipment is as follows:

a) Magnetic heating stirrer, stirring rod approximately 3.5cm long;

b) Filter crucible, 40 mL, pore size 4.5 µm~9 µm;

c) Glass petri dish, Phi10cm, with a hole in the center;

d) Beaker, 400mL;

e) Constant temperature water bath;

f) Oven, capable of controlling the temperature at 105°C±2°C.

5.7.4 Procedure Weigh 3g of the sample (accurate to 0.001g) into a pre-weighed beaker [5.7.3d], and add 80% ethanol at 60°C~65°C [5.7.2b] 150 mL, place a magnetic rod on a magnetically heated stirrer [5.7.3a)], cover with a glass watch glass [5.7.3c)], and insert a thermometer into the center hole. Turn on the heating stirrer, adjust the stirring speed to avoid splashing, maintain the temperature at 60°C~65°C, and stir for 10 minutes. Stop stirring, place the beaker in a constant temperature water bath at 60°C~65°C [5.7.3e], let it stand to allow the insoluble matter to settle, and discard the supernatant as much as possible. It can be completely poured into a pre-weighed filter crucible [5.7.3b). Add 150 mL of 80% ethanol (60°C~65°C) [5.7.2b)] to a beaker, repeat the above stirring and filtering operations, and then use a washing machine... Rinse the beaker, watch glass, stir bar, and thermometer thoroughly with approximately 250 mL of 80% ethanol at 60°C~65°C to ensure complete transfer of insoluble matter. Pour the contents into the crucible and wash the crucible contents further. During this operation, suction filtration can be used, but avoid drying the filter cake; if particles pass through the filter... If the device is used, the suction should be slowed down.

5.7.6 Precision The absolute difference between two independent determinations obtained under repeatability conditions should not exceed 0.3%, and in cases where it exceeds 0.3%, it should not exceed [a certain percentage]. The premise is 5%.

5.8 Total content of various inorganic salts

5.8.1 Preparation of dried samples Weigh approximately 10g of the sample into a dry, flat weighing bottle. After opening the cap, place the bottle in an oven at 105°C±2°C for 2 hours to dry. Remove the bottle, cap it again, and then... Place in a desiccator to cool and store for later use.

5.8.2 Determination of carbonates in sodium carboxymethyl cellulose

5.8.2.1 Principle Weigh a certain amount of sample, dissolve it, and titrate it with hydrochloric acid standard titration solution to the endpoint of the mixed index reagent, and then titrate it with sodium hydroxide standard solution. The solution is titrated back to the endpoint of the mixed indicator, and the carbonate content is calculated.

5.8.2.2 Reagents and Materials Unless otherwise specified, only reagents confirmed to be of analytical grade shall be used in the analysis; the water used in the tests shall comply with the requirements of GB/T 6682.Reagents as follows:

a) Hydrochloric acid (HCl) standard titration solution, c(HCl) =

0.2 mol/L, prepared and standardized according to QB/T 2739;

b) Sodium hydroxide (NaOH) standard titration solution, c(NaOH) =

0.1 mol/L, prepared according to QB/T 2739. Calibration;

c) Phenolphthalein (C20H14O4) indicator solution, 10 g/L ethanol (95%) solution, prepared according to QB/T 2739;

d) Methyl red (C15H15N3O2)-bromocresol green (C21H14Br4O5S) indicator solution, prepared according to QB/T 2739;

e) Anhydrous ethanol (CH3CH2OH).

5.8.2.3 Instruments The required experimental equipment is as follows:

a) Conical flask. 250mL.

5.8.2.4 Procedure Weigh

0.5 g of sample (5.8.1) (accurate to

0.001

g) into an Erlenmeyer flask [5.8.2.3a)], and moisten with a small amount of anhydrous ethanol [5.8.2.2e)]. Add 50 mL of freshly boiled and cooled water, gently stir with a glass rod to break up the clumps, add 2 drops of phenolphthalein indicator [5.8.2.2c] and methyl red. Add 6-7 drops of bromocresol green indicator [5.8.2.2d]. If the solution turns green, adjust it with standard sodium hydroxide titration solution [5.8.2.2b]. The solution should just turn gray; otherwise, titrate with

0.2 mol/L standard hydrochloric acid solution [5.8.2.2a)] until it changes from reddish-purple to gray, and record the result. The volume V1 of hydrochloric acid standard titration solution consumed. Continue titrating with

0.2 mol/L hydrochloric acid standard titration solution [5.8.2.2a)] to the sample solution. The endpoint is reached when the green color reverts to gray. Heat on a hot plate to boiling for 2 minutes. If the gray color disappears, carefully add the standard hydrochloric acid titration solution dropwise. [5.8.2.2a)] The solution should be brought back to its gray color, but not in excess. Record the volume of standard hydrochloric acid solution used as V2 (the total value including V1). Titrate with standard sodium hydroxide solution [5.8.2.2b) until the mixed indicator solution changes from green to light purple, marking the endpoint. Record the hydrogen consumed. The volume of the sodium oxide standard titration solution is V3.

5.8.2.5 Results and Calculations The carbonate content (w1) in sodium carboxymethyl cellulose is calculated according to formula (5).

5.8.2.6 Precision The absolute difference between two independent determinations obtained under repeatability conditions should not exceed 0.5%, and in cases where it exceeds 0.5%, it should not exceed [a certain percentage]. The premise is 5%.

5.8.3 Determination of Silicate in Sodium Carboxymethyl Cellulose

5.8.3.1 Principle Silicates precipitate as orthosilicic acid under acidic conditions, and decompose at high temperatures to form silicon dioxide, which is then determined by gravimetric method.

5.8.3.2 Reagents and Materials Unless otherwise specified, only reagents confirmed to be of analytical grade shall be used in the analysis; the water used in the tests shall conform to GB/T 6682.The reagents are as follows:

a) Hydrochloric acid (HCl);

b) Silver nitrate (AgNO3), 5 g/L solution.

5.8.3.3 Instruments The required experimental equipment is as follows:

a) Volumetric flask. 500mL;

b) Porcelain crucible. 50 mL;

c) Porcelain evaporating dish. 100mL;

d) High-temperature furnace. Temperature controllable at 450°C~500°C, 900°C±10°C;

e) Filter paper. Ash-free quantitative filter paper.

5.8.3.4 Sample preparation and determination Weigh

1.0 g (accurate to

0.001

g) of sample (5.8.1) into a 100 mL porcelain evaporating dish [5.8.3.3c], heat gently, and after carbonization, []. Incinerate at 450°C~500°C for 4 hours [5.8.3.3d). Remove, cool, and add 50mL of water and 10mL of hydrochloric acid [5.8.3.2a]. Heat in a boiling water bath. After evaporating to dryness by heating, continue heating for 30 minutes, add 10 mL of hot water, filter through filter paper [5.8.3.3e], and wash the residue with hot water until clean. The washing solution was tested with silver nitrate [5.8.3.2b)] until no chloride ions (Cl-) were found. The filtrate and washing solution were then combined into a 500 mL volumetric flask [5.8.3.3a)]. (For the determination of sulfates and phosphates). Place the filter paper containing insoluble matter in a pre-weighed porcelain crucible [5.8.3.3b] and heat it on an electric furnace. After drying and carbonization, it is placed in a high-temperature furnace [5.8.3.3d] and ignited at 900°C±10°C for 30 minutes. After removal, it is transferred to a desiccator to cool and then weighed. (Weigh to 0.001g).

5.8.3.5 Result Calculation The content (w2) of silicate (calculated as silicon dioxide SiO2) in sodium carboxymethyl cellulose is calculated according to formula (6).

5.8.3.6 Precision The absolute difference between two independent determinations obtained under repeatability conditions should not exceed 0.2%, and in cases where it exceeds 0.2%, it should not exceed [a certain percentage]. The premise is 5%.

5.8.4 Determination of Sulfate in Sodium Carboxymethyl Cellulose

5.8.4.1 Principle A certain volume of the filtered silicate test solution was taken, and the sulfate present in the solution was precipitated with barium chloride. The precipitate was filtered and washed. The polyester was heated at 900°C and weighed.

6.1 Inspection Classification

6.1.1 Type Testing Type testing includes all items specified in Chapter

3.Type testing shall be conducted in the following circumstances.

a) During formal production, significant changes may occur in raw materials, processes, equipment, and management (including changes in personnel qualifications), which could affect the product. When it comes to quality;

b) During normal production, type testing should be conducted periodically, generally once a month;

c) When production resumes after a long period of shutdown;

d) When the factory inspection results differ significantly from the previous type inspection results;

e) When the quality supervision agency requests a type test.

6.1.2 Factory Inspection The factory inspection items include moisture and volatile matter, viscosity, pH, degree of etherification, and active ingredients (on a dry basis).

6.2 Product Batching and Sampling Rules

6.2.1 Product delivery and sampling acceptance Products are delivered in batches and subject to sampling inspection. Products of the same specification and batch number delivered at one time constitute one delivery batch. Products delivered by the manufacturing unit shall first be inspected by its quality inspection department according to this standard, and shall be certified as conforming to this standard and issued a product quality inspection certificate. A certificate is required before a product can leave the factory. The product quality inspection certificate should include the manufacturer's name, product name, trademark, adopted standard number, batch number, and batch number. Quantity, quality indicators, production date, etc. The receiving party shall inspect the goods upon presentation of the product quality inspection certificate. If necessary, sampling inspection may be conducted within one month in accordance with the following provisions.

6.2.2 Sampling The sample size required for acceptance by the receiving party should be determined according to Table 2 based on the batch size. Both parties should meet at the delivery location to collect the sample from the delivered batch. Randomly select bags of samples from the middle.

6.3 Judgment Rules The test results shall be determined according to the rounding value comparison method of GB/T 8170.If any physicochemical indicator fails to meet the standard, twice the number of bags may be re-tested. If a sample is retested for non-conforming items, and the retest results are still non-conforming, then the batch of products is deemed non-conforming.

7.1 Marking

7.1.1 The packaging markings shall include the following.

a) Product name, trademark, and applicable standard number;

b) Production date or product batch number;

d) It has markings or labels indicating that it is waterproof or moisture-proof;

e) The name, address, and contact number of the manufacturing company.

7.1.2 The printed markings (patterns and text) on the packaging should be clear, aesthetically pleasing, and free from fading.

7.2 Packaging Packaging should be done in woven bags lined with plastic film, and the net content of the package should conform to the nominal weight.

7.3 Transportation During transportation, it should be protected from sunlight, rain, and moisture. Handle with care to avoid damage to the packaging bags.

7.4 Storage Products should be stored in a dry, clean warehouse. If outdoor storage is necessary, appropriate moisture-proof measures should be taken, and the stack height should not exceed the support height. The maximum load on the goods shall be limited, and a covering shall be added to protect them from sun, rain, moisture, and damage to the packaging.

7.5 Shelf life Under the above storage and transportation conditions and without being opened, the product has a shelf life of at least one year from the date of production.