PDF GB/T 1727-2021 English (GB/T 1727-1992: Older version)
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General methods for preparation of coating films
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| GB/T 1727-1992 | English | 279 |
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General preparation of paint film
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| GB/T 1727-1979 | English | RFQ |
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GB/T 1727-2021: PDF in English (GBT 1727-2021) GB/T 1727-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 87.040
CCS G 50
Replace GB/T 1727-1992, GB/T 1765-1979
General Methods for preparation of coating films
ISSUED ON: AUGUST 20, 2021
IMPLEMENTED ON: MARCH 1, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 6
4 Instruments and materials ... 7
5 Samples ... 9
6 Preparation methods of paint films ... 9
Appendix A ... 13
General Methods for preparation of coating films
1 Scope
This document specifies the instruments, materials, samples, and preparation methods
involved in the preparation of paint films.
This document is applicable to the preparation of paint films coated on (test panels and
test pieces) used for the determination of paint film properties. The preparation methods
include commonly-used laboratory methods, such as brushing methods, spraying
methods, dip-coating methods, and scraping-coating methods.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB/T 3186 Paints, varnishes and raw materials for paints and varnishes -- Sampling
GB/T 9271 Paints and varnishes standard panels for testing
GB/T 9278 Temperatures and humidity for conditioning and testing of paint
specimens
GB/T 13452.2 Paints and varnishes -- Determination of film thickness
GB/T 20777 Paints and varnishes -- Examination and preparation of samples for
testing
GB/T 23981.1-2019 Paints and varnishes -- Determination of hiding power -- Part
1: Determination of contrast ratio of white and light paints
GB/T 37356 Paints and varnishes -- Lighting and procedure for visual assessments
of coatings
3 Terms and definitions
There are no terms and definitions that need to be defined in this document.
4 Instruments and materials
4.1 Paintbrushes
Width: 25 mm~35 mm.
4.2 Air spray equipment
It consists of a compressed air source, an oil-water separation device, an air storage
tank, a hose, a spray gun, etc. Unless otherwise specified, the inner diameter of the gun
nozzle is 0.75 mm~2 mm.
4.3 Scraping-coating devices
4.3.1 Putty film doctor-blade coaters
Unless otherwise specified, it consists of mold frames with different thicknesses and a
doctor-blade frame. The thickness of the mold frame is selected according to the
thickness of the putty film.
4.3.2 Wire rod coaters
It is composed of a rod body and a metal wire, all of which are made of stainless steel.
Metal wires of different diameters are tightly wound around the rod to form coaters of
different specifications.
4.3.3 Gap-type Wet Film Preparers
It is precisely machined from corrosion-resistant materials. The working surface’s two
ends are datum planes with the same level, and the middle part has a gap with a certain
depth (relative to the datum plane). The geometry of the working surface and the depth
of the gap are related to the thickness of the wet film produced by scraping-coating, but
the depth of the gap is not equal to the wet film thickness.
4.3.4 Automatic Coaters
A wire rod coater (4.3.2) and a gap-type wet film preparer (4.3.3) can be fixed on the
equipment for automatic coating; the coating stroke and coating speed can be set; the
maximum coating stroke shall meet the requirements of plate making. When preparing
the paint film for polyester film substrate, there shall be a vacuum adsorption device on
the coating platform.
4.4 Viscometers
Tu-4 Viscometer or ISO Outflow Cup, etc.
4.5 Stopwatches
The accuracy shall be at least 0.2 s.
4.6 Ovens
It can be tested under safe conditions and can be maintained within ±2 °C of the
specified or agreed temperature. The oven shall be equipped with a forced ventilation.
4.7 Substrates and treatment of substrates
4.7.1 General requirements
Unless otherwise specified, the substrate material and surface treatment shall be carried
out in accordance with the provisions of GB/T 9271.
4.7.2 Tinplate
Unless otherwise specified, the dimensions shall be 25 mm×120 mm×(0.2 mm~0.3
mm), 50 mm×120 mm×(0.2 mm~0.3 mm) or 70 mm×150 mm×(0.2 mm~0.3 mm).
4.7.3 Cold-rolled steel plates
Unless otherwise specified, the dimensions shall be 50 mm×120 mm×(0.45 mm~0.55
mm), 70 mm×150 mm×(0.45 mm~0.55 mm) or 70 mm×150 mm×(0.8 mm~1.2 mm).
4.7.4 Hot-rolled steel sheets
Unless otherwise specified, the dimensions shall be 70 mm×150 mm×(3 mm~5 mm).
4.7.5 Glass plates
Unless otherwise specified, the dimensions shall be 90 mm×120 mm×(2 mm~3 mm),
100 mm×100 mm×(4 mm~6 mm) or 100 mm×150 mm×(2 mm~3 mm).
4.7.6 Aluminum plates
Unless otherwise specified, the dimensions shall be 70 mm×150 mm×(1 mm~2 mm),
100 mm×100 mm×(1 mm~2 mm) (center opening) or ϕ100 mm (center opening).
4.7.7 Non-asbestos fiber cement slabs
Unless otherwise specified, the dimensions shall be 70 mm × 150 mm × (4 mm~6 mm)
or 150 mm × 430 mm × (4 mm~6 mm).
4.7.8 Polyester films
Unless otherwise specified, the thickness shall be 30 μm ~ 50 μm, and its size shall not
according to the above method.
6.2.5 Scraping-coating methods
6.2.5.1 Putty film doctor-blade coating methods
Put a mold frame with suitable thickness and a doctor-blade frame on the substrate, and
put an appropriate amount of putty in the mold frame; then, use a metal doctor-blade to
spread the putty evenly on the substrate, to form a uniform and flat putty film; finally,
remove the mold frame and the doctor-blade frame.
6.2.5.2 Paint film scraping-coating methods
6.2.5.2.1 Using wire rod coaters or gap-type wet film preparers
Place the substrate on the platform and fix it; if the substrate is a polyester film (4.7.8),
make preparations as the method specified in 5.3.1.1a) or 5.3.1.1b) of GB/T 23981.1-
2019.
Choose a suitable wire rod coater (4.3.2) or a gap-type wet film preparer (4.3.3), and
place it on one end of the substrate; the long side of the wire rod coater or the gap-type
wet film preparer shall be roughly parallel to the short side of the substrate (or place it
in the specified position of the substrate). Then, place an appropriate amount of sample
evenly in front of the wire rod coater or the gap-type wet film preparer; hold the wire
rod coater or the gap-type wet film preparer, press downward with a certain force, and
make it slide across the substrate at a constant speed about 150 mm/s; then, the substrate
will be coated by a paint film of required thickness. When moving the wire rod coater
or the gap-type wet film preparer, it shall not be rotated and laterally moved.
6.2.5.2.2 Using automatic coaters
Place the substrate on the coating platform of the automatic coater (4.3.4) and fix it; if
the substrate is a polyester film (4.7.8), make preparations it by the method specified in
5.3.1.1c) of GB/T 23981.1-2019.
Select an appropriate length of stroke according to the requirements of the product;
apply loads to the two ends of the wire rod coater (4.3.2) or the gap-type wet film
preparer (4.3.3) as specified or agreed; set an appropriate coating speed according to
the characteristics of the sample. If it is to coat on flexible or thin substrates, turn on the
vacuum adsorption device of the automatic coater, to make the substrate attach to the
coating platform flat and tightly.
6.3 Drying and adjustment of paint films
After coating, each painted test panel or test piece shall be dried (or baked) under the
specified conditions and cured according to the specified time. Unless otherwise
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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