GB/T 12008.7-2025Plastics - Polyether polyols for use in the production of polyurethane - Part 7: Determination of basicity (English PDF)

Foreword

This document was drafted in accordance with the rules given in GB/T 1.1-2020

"Directives for standardization - Part 1.Rules for the structure and drafting of

standardizing documents".

This document is Part 7 of GB/T 12008 "Plastics -- Polyether polyols for use in the

production of polyurethane". The following parts of GB/T 12008 have been published.

- Part 1.Designation system;

- Part 2.Specification;

- Part 3.Determination of hydroxyl number;

- Part 4.Determination of sodium and potassium;

- Part 5.Determination of acidity as acid number;

- Part 6.Determination of degree of unsaturation;

- Part 7.Determination of basicity.

The modification of this document adopts ISO 14899.2022 "Plastics -- Polyols for use

in the production of polyurethane -- Determination of basicity".

This document has the following structural adjustments compared to ISO 14899.2022.

- In Chapter 7, 7.1 and 7.2 are added corresponding to 7.1 in ISO 14899.2022; 7.2 in

ISO 14899.2022 is deleted.

The technical differences between this document and ISO 14899.2022 and their reasons

are as follows.

- Changed "polyether polyols in the range of 0 µg/g to 50 µg/g (expressed as KOH)"

to "polyether polyols in the range of 0 CPR units to 26.7 CPR units" (see Chapter

1) to facilitate the application of this document;

- Replaced ISO 6353-1, ISO 6353-2 and ISO 6353-3 by the normative reference

GB/T 601."All reagents shall comply with the specifications of ISO 6353-1, ISO

6353-2 and ISO 6353-3, but other grades may be used, provided that it is first

determined that the reagents have a high enough purity to allow their use without

reducing the accuracy of the determination" was changed to "The grade of the

reagents used shall be analytically pure or above, and the preparation and

calibration of the standard titration solution shall be carried out in accordance

with the provisions of GB/T 601" (see 7.1) to adapt to China's technical conditions

and improve operability;

- Replaced ISO 3696 (see 7.1) by the normatively referenced GB/T 6682 to adapt to

China's technical conditions and improve operability;

- Deleted the reagent "potassium hydrogen phthalate", which is the reference reagent

for the calibration of sodium hydroxide standard titration solution and is not used

in this method;

- Changed the accuracy requirement of the electronic balance from "1 mg" to "0.1

mg" (see 8.3) to ensure the accuracy of sample mass weighing;

- Changed the setting of the automatic potentiometric titrator from "the maximum

titration volume is set to 5 mL" to "the recommended setting value is shown in

Annex A" (see 9.1) to improve the repeatability and reproducibility precision of

the method;

- Added the expression of alkalinity value in µmol/g and the calculation formula (see

10.3) to improve the characterization method of alkaline substance content;

- Add regulations on the number of parallel determinations and the number of digits

to be retained (see 10.4) to ensure that the results are expressed accurately and

uniformly;

- Changed the repeatability precision from 0.2 CPR unit to 0.20 CPR unit (see 11.1.2),

and the reproducibility precision from 0.6 CPR unit to 0.60 CPR unit (see 11.1.3)

to make them consistent with the number of digits retained in the results;

- Added "Alkalinity value is 0.38 µgKOH/g or 0.007 µmol/g" (see 11.1.2) and

"Alkalinity value (in terms of KOH) is 1.13 µg/g or 0.02 µmol/g" (see 11.1.3) to

improve the precision requirements;

- Supplemented the test report with the method of expressing the content of alkaline

substances. "or expressed as the number of micromoles of alkaline substances per

gram of sample, in µmol/g" (see Chapter 12), to make it consistent with the

supplementary method of characterizing the content of alkaline substances.

The following editorial changes were made to this document.

- To be consistent with the scope of the standard, the name of the standard is changed

to "Plastics -- Polyether polyols for use in the production of polyurethane -- Part

7 Determination of basicity";

- The contents of the titration curve notes are supplemented. The instructions for

removing false equivalence points are added (see Note 9.5);

- The explanation of the meaning of constants 1000 and 30 in formula (1) is

supplemented (see 10.1);

- The explanation of the meaning of constant 56.1 in formula (2) is supplemented

(see 10.2);

- NOTE 2 is added to explain the verification test data of this document (see 11.1.1);

- Annex A (informative) "Recommended values for automatic potentiometric titrator

parameter settings" is added.

Attention is drawn to the possibility that some of the elements of this document may be

the subject of patent rights. The issuing authority shall not be held responsible for

identifying any or all such patent rights.

This document was proposed by China Petroleum and Chemical Industry Federation.

This document shall be under the jurisdiction of National Technical Committee on

Plastics of Standardization Administration of China (SAC/TC 15).

The drafting organizations of this document. Shanghai Dongda Chemical Co., Ltd.,

Changhua Chemical Technology Co., Ltd., Wanhua Chemical Group Co., Ltd.,

Zhejiang Huafeng New Materials Co., Ltd., Sinochem Dongda (Zibo) Co., Ltd., Liming

Chemical Research and Design Institute Co., Ltd., Asahikawa Chemical (Suzhou) Co.,

Ltd., Zhejiang Hexin Technology Co., Ltd., Cangzhou Dahua Co., Ltd., Guangzhou

Tianci High-tech Materials Co., Ltd., Huaian Bader Polyurethane Technology Co., Ltd.,

Jiangsu Lihong Technology Development Co., Ltd., Hubei Xiangyuan New Materials

Technology Co., Ltd., Guichuangtongqiao Medical Technology Co., Ltd., Guangdong

Yuanxing Industrial New Materials Co., Ltd., Nantong Deyi New Materials Co., Ltd.,

Zhejiang Batai Medical Technology Co., Ltd., Nanjing Shangqin New Materials

Technology Co., Ltd.

Main drafters of this document. Xu Jun, Li Xueqing, Zhao Zilong, Liu Yanhua, Jin

Meijin, Zhan Xiaotong, Shi Dandan, Zhang Dahua, Xu Jinfang, Qian Cuihua, Li

Zeyong, Zhao Baocheng, Feng Lei, Wang Tai, Chen Hongqiong, Jia Shiqian, Gu

Shenggang, Xu Xinxin, Wei Qiong, Zhao Zhong, Zhang Xinzhao, Chen Qiaojian,

Zhang Xiaohui, Yin Yanhong, Ju Weitan.

1 Scope

This document describes a method for determining the amount of trace alkalinity in

polyether polyols used in polyurethane production. Knowledge of the amount of trace

alkalinity in polyether polyols is important for preventing gelation of the reaction mass

during polyurethane prepolymer production. Controlling the amount of alkalinity in

polyether polyols used in polyurethane production is also important for ensuring the

sustainability and reproducibility of the reaction.

This document is applicable to the quality control of polyether polyols used in

polyurethane production and can also be used as a test method in research. It is

applicable to polyether polyols with a content of alkaline substances ranging from 0

CPR units to 26.7 CPR units. The final result value is in CPR (controlled polymerization

rate) units. The method in this document is not applicable to amine polyols.

2 Normative references

The following referenced documents are indispensable for the application of this

document. For dated references, only the edition cited applies. For undated references,

the latest edition of the referenced document (including any amendments) applies.

GB/T 601, Chemical reagent -- Preparations of reference titration solutions

GB/T 6682, Water for analytical laboratory use -- Specification and test methods

(GB/T 6682-2008, ISO 3696.1987, MOD)

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

Terminology databases for standardization maintained by ISO and IEC.

- ISO online browsing platform. https.//wwwi.so.org/obp;

4 Principle

30 g of polyether polyol specimen is diluted with methanol. Titrate with 0.01 mol/L

hydrochloric acid standard titration solution. The result is calculated by the difference

in titration volume between the specimen and blank.

5 Sampling

Draw the sample from the mixing vessel into a dry, clean borosilicate glass container

(soft glass containers are not acceptable). If sampling through a line or valve, flush the

line thoroughly with product before starting to draw the sample. Seal the sample until analysis.

6 Interference

Any acidic or basic substances accidentally introduced into the sample can cause errors

in the analysis. Substances that can act as buffers may interfere with the titration

endpoint of the analysis. Some samples may contain several different trace compounds.

These trace compounds may cause multiple interruptions in the titration curve, making

the interpretation difficult. This analytical method is not suitable for amino polyols.

7 Reagents

Unless otherwise specified, the grade of the reagents used shall be analytically pure or

above, and the preparation and calibration of the standard titration solution shall be

carried out in accordance with the provisions of GB/T 601.The test water shall comply

with the specifications of Grade 2 water in GB/T 6682.

8 Equipment

9 Test steps

10 Result calculation and presentation

11 Precision and bias

12 Test report

The test report shall include the following.

a) Reference to this document;

b) All necessary details to identify the product analyzed;

c) The test result, expressed in CPR units, accurate to 0.01 CPR unit, or expressed

in micrograms of potassium hydroxide equivalent to the alkaline content per gram

of sample, in µmol/g, or expressed in micromoles of alkaline content per gram of

specimen, in µmol/g;

d) Any factors and details that may have an impact on the result and are not specified

in this document;

e) The date of analysis.

Annex A

(informative)

Recommended values for automatic potentiometric titrator parameter settings

The recommended values for setting the parameters of the automatic potentiometric

titrator are applicable to specimens with a CPR value of 0.00 CPR unit to 3.00 CPR

unit, as shown in Table A.1 and Table A.2.The settings of each parameter can be fine-

tuned according to the actual conditions of the sample without affecting the accuracy

of the test results. When the CPR value is too large, the setting value of the instrument

parameter shall be adjusted according to the CPR value.

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