GB/T 12008.7-2025 PDF English
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Plastics - Polyether polyols for use in the production of polyurethane - Part 7: Determination of basicity
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Polyether polyols--Determination of unsaturation
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GB/T 12008.7-2025: Plastics - Polyether polyols for use in the production of polyurethane - Part 7: Determination of basicity
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GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.080.10
CCS G 31
Plastics -- Polyether polyols for use in the production of
polyurethane -- Part 7.Determination of basicity
(ISO 14899.2022, Plastics -- Polyols for use in the production of polyurethane -
- Determination of basicity, MOD)
Issued on. MARCH 28, 2025
Implemented on. OCTOBER 01, 2025
Issued by. State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword... 3
Introduction... 6
1 Scope... 7
2 Normative references... 7
3 Terms and definitions... 7
4 Principle... 8
5 Sampling... 8
6 Interference... 8
7 Reagents... 8
8 Equipment... 9
9 Test steps... 9
10 Result calculation and presentation... 10
11 Precision and bias... 11
12 Test report... 11
Annex A (informative) Recommended values for automatic potentiometric titrator
parameter settings... 13
Bibliography... 15
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;
3.1 polyurethane
A polymer prepared by the reaction of an organic diisocyanate or polyisocyanate with
a compound containing two or more hydroxyl groups.
3.2 CPR value
controlled polymerization rate value
The micro equivalent of the alkaline substance content in 30 g of polyether polyol
specimen (i.e. the milliequivalent of the alkaline substance content in 30 kg of polyether polyol).
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
8.1 Automatic potentiometric titrator. capable of determining multiple endpoints,
equipped with a pair of electrodes or a combined glass calomel electrode, a 5 mL burette
and a recorder.
8.2 Burette. or other automatic dispensing device, capable of dispensing (50±0.1) mL.
8.3 Balance. range is not less than 30 g; accuracy is 0.1 mg.
9 Test steps
9.1 Set up the automatic potentiometric titrator (8.1). Recommended values for
parameter settings are given in Annex A.
9.2 Add 50 mL of methanol (7.2) as blank solvent into a 100 mL titration bottle (8.4).
9.3 Titrate the blank with 0.01 mol/L hydrochloric acid standard titration solution (7.1).
Record the titration volume of hydrochloric acid. The last inflection point on the
titration curve is taken as the end point of this titration. The volume of 0.01 mol/L
hydrochloric acid standard titration solution consumed by the blank shall be less than 0.2 mL.
9.4 In a 100 mL titration bottle, weigh about 30 g of sample, accurate to 1 mg. Add 50
mL of methanol and stir until completely dissolved (also refer to the notes in 9.2).
10 Result calculation and presentation
10.1 Calculate the controlled polymerization rate according to formula (1) and express
it as CPR value.
10.2 Calculate the alkalinity (in KOH) according to formula (2) and express it in μgKOH/g.
10.3 Calculate the base value according to formula (3) and express it in μmol/g.
10.4 Result expression. Each specimen is measured twice in parallel, and VS, VB, and
m are retained to at least three decimal places. The final measurement results C and N1
are retained to two decimal places. N2 is retained to three decimal places. The arithmetic
mean of the two parallel measurement results is taken as the final measurement result.
11 Precision and bias
11.1 Precision
11.1.1 Judge the acceptability of the results using the repeatability and reproducibility
criteria given in 11.1.2 and 11.1.3.
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.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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