Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 20314-2006 Thin Float Glass for LCD Applications in whole. The following technical changes have been made with respect to GB/T 20314-2006 (the previous edition):
——Terms and definitions are modified (see Chapter 3; Chapter 3 of 2006 edition);
——Classification based on quality grade in the former standard is modified to grading based on quality requirements (see Chapter 4; 4.1 of 2006 edition);
——Thickness classification is modified (see 5.2; 4.3 of 2006 edition);
——Thickness difference grading is cancelled, index requirements for thickness deviation and thickness difference are modified (see 5.2; 5.2 of 2006 edition);
——Index requirements for dimension deviation and diagonal difference are modified (see 5.1; 5.2 of 2006 edition);
——Edge defects are added to appearance quality requirements (see 5.3; 5.3 of 2006 edition);
——As for appearance quality, sheet specification is modified; hot end dust and tin point are incorporated into spot defects; scrub is incorporated into scratch; thread is added (see 5.3; 5.5 of 2006 edition);
——Micro-waveness grading is cancelled and index requirements for micro-waveness of 0.55mm-thick glass are modified (see 5.4; 5.4 of 2006 edition);
——Index requirements for warp degree of 0.55mm-thick glass are modified (see 5.5; 5.4 of 2006 edition);
——Test methods for appearance quality, micro-waveness and warp degree are modified (see 6.5, 6.6 and 6.7; 6.2, 6.4, 6.6 and 6.7 of 2006 edition);
——Inspection classification clauses are added, acceptance quality limit clauses for sampling and some required items are modified (see Chapter 7; Chapter 7 of 2006 edition);
——Annex A is deleted (see Annex A of 2006 edition).
This standard was proposed by China Building Materials Federation.
This standard is under the jurisdiction of National Technical Committee on Industrial Glass and Special Glass of Standardization Administration of China (SAC/TC 447).
The previous edition of the standard replaced by this standard is as follows:
——GB/T 20314-2006.
Thin Float Glass for Liquid Crystal Display (LCD) Applications
1 Scope
This standard specifies terms and definitions, grading, requirements, test methods, inspection rules, packaging, marking, transportation and storage of thin float glass for liquid crystal display (LCD) applications.
This standard is applicable to soda-lime-silica thin float glass for TN-LCD and STN-LCD with thickness not greater than 1.10mm.
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 1216 External Micrometer
GB/T 2680 Determination of Light Transmittance, Solar Direct Transmittance, Total Solar Energy Transmittance and Ultraviolet Transmittance for Glass in Building and Related Glazing Factors
GB/T 2828.1-2012 Sampling Procedures for Inspection by Attributes - Part 1: Sampling Schemes Indexed by Acceptance Quality Limit (AQL) for Lot-by-lot Inspection
GB/T 8170 Rules of Rounding Off for Numerical Values & Expression and Judgment of Limiting Values
GB/T 9056 Metal Ruler
GB 11614-2009 Flat Glass
GB/T 15764 Standard Terminology of Flat Glass
GB/T 18680-2002 The Transparent Conductive Glass with Indium-in Oxide Films Used in Liquid Crystal Display
JB/T 2369 Reading Microscope
SJ/T 10793 Terms for Glass Used in Electronic Applications
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in GB 11614-2009, GB/T 15764, GB/T 18680-2002 and SJ/T 10793 and the following apply.
3.1
TN-LCD
twisted nematic liquid crystal display
3.2
STN-LCD
super-twisted nematic liquid crystal display
3.3
edge defects
phenomena such as section crack, protruding or mutilation of glass sheet, etc., including defects like broken edge, edge unevenness, broken corner, etc.
3.4
micro-waveness
minor unevenness degree of glass surface
3.5
warp
noncoincidence between glass surface and reference plane, expressed by warp degree
4 Grading
The glass is classified into Grade A and Grade B according to different quality requirements.
5 Requirements
5.1 Dimension deviation and diagonal difference
Thin float glass for liquid crystal display (LCD) applications shall be cut into rectangle with dimension deviation of length and width not exceeding ±2mm and diagonal difference not greater than 0.2%.
5.2 Thickness deviation and thickness difference
Common thicknesses of thin float glass for liquid crystal display (LCD) applications are 1.10mm, 0.70mm, 0.55mm, 0.40mm, 0.33mm, 0.25mm, 0.20mm, 0.15mm and 0.10mm. Thickness deviation and thickness difference shall meet those specified in Table 1.
Table 1 Thickness Deviation and Thickness Difference mm
Thickness (D) Thickness deviation Thickness difference
1.10≥D≥0.55 ±0.050 ≤0.050
0.55>D≥0.20 ±0.030 ≤0.030
0.20>D≥0.10 ±0.020 ≤0.020
5.3 Appearance quality
Appearance quality of thin float glass for liquid crystal display (LCD) applications shall meet those specified in Table 2.
Table 2 Appearance Quality
Defect type Quality requirements
Spot defects Grade A Grade B
Defect dimension (L)
mm Permissible quantity limit of each sheet
Pcs Defect dimension (L)
mm Permissible quantity limit of each sheet
Pcs
0.050.20 0 L>0.30 0
Intensity of spot defects Spacing between any two spot defects shall not be less than 10mm
Scratch Scratch width (W)
mm Permissible total length limit of each sheet
mm
0.030.07 0
Spot distortion Not allowed
Thread Not allowed
Surface crack Not allowed
Surface stain The surface shall be free of stain which cannot be washed
Edge defects Single broken edge: length <2mm, width <1mm, depth <1/2 the thickness of glass sheet
Total length of broken edge is less than 15% the side length of glass sheet
Edge unevenness, broken corner, crack, etc. are not allowed
The sheet specification in this table is 406mm×356mm, converted into 0.144 536m2. Permissible quantity limit of spot defects and total scratch length limit for the glass of other specification: the quotient of area and 0.144 536m2 is respectively multiplied by the permissible quantity limit of spot defects with sheet specification of 406mm×356mm as well as the total scratch length limit. The results shall be rounded off to integer according to GB/T 8170.
Except edge defects, other appearance defects within 5mm of original sheet edge are not considered.
5.4 Micro-waveness
Micro-waveness of thin float glass for liquid crystal display (LCD) applications shall meet those specified in Table 3.
?
Table 3 Micro-waveness
Thickness (D)
mm Micro-waveness
μm/20mm
1.10≥D>0.70 ≤0.15
0.70≥D>0.55 ≤0.20
0.55≥D>0.40 ≤0.25
0.40≥D≥0.33 ≤0.30
0.33>D≥0.20 ≤0.35
0.20>D≥0.10 ≤0.40
5.5 Warp degree
Warp degree of thin float glass for liquid crystal display (LCD) applications shall meet those specified in Table 4.
Table 4 Warp Degree
Thickness (D)
mm Warp degree
%
Grade A Grade B
1.10≥D>0.55 ≤0.05 ≤0.10
0.55≥D≥0.10 ≤0.15 ≤0.15
Glass shall be free from Type S warp through visual observation.
5.6 Visible light transmittance
Visible light transmittance of thin float glass for liquid crystal display (LCD) applications shall not be less than 91%.
Foreword i
1 Scope
2 Normative References
3 Terms and Definitions
4 Grading
5 Requirements
6 Test Methods
7 Inspection Rules
8 Packaging, Marking, Transportation and Storage
