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LY/T 3147-2019Coating materials (paints and varnishes) for exterior wood: classification and weathering performance specification (English PDF)

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Issued by

State Forestry and Grassland Administration

Level / Type

National · Recommended

Issue date

October 23, 2019

Implementation date

April 1, 2020

Scope

LY/T 3147-2019 (Coating materials (paints and varnishes) for exterior wood: classification and weathering performance specification) is available as an English-translated PDF.

LY/T 3147-2019 — This standard specifies the terms and definitions, classification, performance requirements, testing and evaluation methods of coatings for outdoor wood. This standard applies to outdoor wood varnishes and colored paints.

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Document preview — LY/T 3147-2019

National Standard of the People's Republic of China

ICS: 91.080.20
Classification: P 23

Issued by: State Forestry and Grassland Administration

Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Grade
4.1 Classification according to the appearance of the paint film
5 Requirements
5.1 Test items and methods
5.2 Performance
6 Coating Performance Report

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard was proposed and managed by the National Timber Standardization Technical Committee Structural Timber Subcommittee (SAC/TC41/SC4).

This standard was drafted. Northeast Forestry University, Institute of Wood Industry, Chinese Academy of Forestry.

1 Scope

This standard specifies the terms and definitions, classification, performance requirements, testing and evaluation methods of coatings for outdoor wood.

This standard applies to outdoor wood varnishes and colored paints.

2 Normative references

The following documents are essential for the application of this document. For dated references, only the dated version applies to this document.

For undated references, the latest version (including all amendments) applies to this document.

GB/T 1741-2007. Determination of mold resistance of paint films GB/T 1766-2008. Paints and varnishes. rating methods for coating ageing GB/T 3181-2008. Paint film color standards GB/T 3186-2006. Sampling of paints, varnishes and raw materials for paints and varnishes GB/T 4893.4-2013. Physical and chemical properties of paint films on furniture surfaces. Part 4. Cross-cut determination method for adhesion GB/T 4893.6-2013. Physical and chemical properties test of paint film on furniture surface. Part 6. Determination of gloss GB/T 4893.9-2013. Physical and chemical properties test of furniture surface paint film Part 9. Impact resistance test of furniture surface paint film GB/T 5206-2015/ISO 4618.:2004. Paints and varnishes. terms and definitions GB/T 9276-1996. Test method for natural weather exposure of coatings GB/T 13452.2-2008. Paints and varnishes. Determination of paint thickness GB T 17657-2013 Test methods for physical and chemical properties of wood-based panels and facing wood-based panels GB/T 33568-2017 Weathering grade and evaluation method for outdoor wood finishing surface GB/T 33569-2017 Test method for artificial aging of wood-coated surfaces for outdoor use ISO 16053-2018 Paints and Varnishes-Outdoor Coatings and Coating Systems for Wood-Natural Aging Test Methods

3 Terms and definitions

The terms and definitions defined in GB/T 5206-2015 and the following apply to this document. For ease of use, the following GB/T is repeatedly listed 5206-2015 some terms and definitions 3.1 Coating materials for exterior wood Paint for outdoor decoration on the surface of wood for decoration and protection.

Biocide

Coating system

A combination of all single coatings formed by a coating to be applied or already applied to a substrate.

Note. The actual system can be characterized by the number of single coatings included.

[GB/T 5206-2015, definition 2.54] 3.3

Table paint finishing coat; top coat

The last single coat in a coating system.

[GB/T 5206-2015, definition 2.112] 3.4 Intermediate coating;

Any layer of coating between the primer and the topcoat.

Priming coat

The first single coat in a coating system.

[GB/T 5206-2015, definition 2.207] 3.6 Film formation the process of changing the applied paint from liquid to solid. For powder coatings, a process from liquid phase to solid phase is required.

Note. Film formation is caused by drying and/or hardening, both of which can occur simultaneously.

[GB/T 5206-2015, definition 2.110] 3.7 Ageing Over time, one or more properties of the paint film gradually change from the initial state.

[GB/T 5206-2015, definition 2.11].

Flexibility

The ability of a dry paint film or single coating to deform without breaking with its substrate.

[GB/T 5206-2015, definition 2.120] 3.9 Hiding power the ability of a coating to cover the color or chromatic aberration of a substrate.

[GB/T 5206-2015, definition 2.138] 3.10 Water permeability the ability of liquid water or water vapor to penetrate the finishing system.

3.11

Water absorption

The ability of the painted surface area to absorb liquid water.

3.12

Chalking

Due to the degradation of one or more components in the paint film or single coating, the appearance of loosely adhered powder on the surface is exhibited.

[GB/T 5206-2015, definition 2.41] 3.13 Adhesion strength at the interface between a solid surface and another material, the phenomenon of adhesion occurs by molecular force.

[GB/T 5206-2015, definition 2.7]

4 Grade

4.1 Classification according to the appearance of the paint film

The appearance classification of paint film includes the following characteristics.

1) Dry film thickness of paint film;

2) Covering ability;

3) Gloss

4.1.1 Paint film thickness

The dry paint film thickness is measured in accordance with 5.2 Method 6A in GB/T 13452.2-2008, and the unit is expressed in micrometers (µm). Measured the paint film should be coated on a smooth and flat substrate, and the thickness part is above the surface of the wood, and the paint penetrating into the wood is not included. paint the film thickness is divided into four grades of ultra-thin, low-thickness, medium-thickness, and ultra-thickness. See Table 1.

Table 1 Grades of paint film thickness

Classification thickness value (average value) Ultra thin less than 5µm Low thickness between 5µm and 20µm Medium thickness between 20µm and 60µm Ultra-thickness greater than 60 µm

4.1.2 Covering ability of paint film

There are three types of opaque, translucent and transparent according to the covering ability of the paint film. See Table 2 for the description of the covering effect.

Table 2 Grading ability of paint film

Classification cover effect description Opaque finish system completely covers the color and pattern of the substrate, but does not cover the surface contour of the substrate Translucent finish system does not completely cover the surface color and pattern of the substrate Transparent through the coating system, the color and texture of the substrate surface are clearly visible 1.1.1 4.1.3 Gloss of paint film According to GB/T 4893.6-2013, the reflectance of the paint film is measured at 60 °. Film gloss is divided into matt, semi-matt, semi-gloss, and bright Five levels of light and high light, see Table 3.

Table 3 Classification of coatings according to film gloss

Classification According to GB/T 4893.6-2013, the reflectance measured at 60 ° Matte below 10 Semi-matt between 10 and 35 Semi-gloss between 35 and 60 Light between 60 and 80 High light above 80

1.1.2 Note. The gloss of the paint film is affected by environmental conditions, the nature of the substrate itself, test methods and application conditions. See Appendix A for specific information.

1.1.3 4.2 According to the requirements of use Based on the different dimensional stability requirements of different wooden members in wooden structures, the water permeability requirements of coatings coated on wooden members are also different.

different. According to the requirements of the dimensional stability of wood components for different purposes, the applicable coatings are divided into three levels. stable, relatively stable and unstable, see table 4.

Table 4 Classification by coating application

Dimensional stability of paint-grade wood members Only small changes in the size of the stabilizing wood members are required.

Good water resistance Wooden doors and windows the size of the relatively stable wood member allows some variation, the coating has Certain waterproof ability Wooden component wall panels, wooden structure houses, outdoor furniture Unsteady dimensional change of unstable wood members, coating waterproof Unlimited ability Laminate wall panels, fences, shacks

1.1.4 Note. The coatings applied to outdoor wood should meet the requirements for the dimensional change of components made of the wood and wood under moisture absorption and desorption.

The purpose of the substrate is to control the substrate's ability to absorb and desorb external moisture. Wood that is easily deformed under moisture absorption and desorption (such as pine and spruce) is divided into 3 according to the table There are two grades of non-deformable wood.

1.1.5 4.3 According to the exposure conditions 1.1.6 4.3.1 Composition of exposure conditions the applicable exposure conditions for paints are composed of two parts in this standard, see Appendix A.

1) External weather conditions. compass orientation of the coated wooden member (see Figure 1)

2) The surrounding state of the coated wooden members in the wooden structure. the oblique angle of the cover, half cover or full cover and installation (see Figure 1) 1.1.7 4.3.2 Grading of exposure conditions the applicable exposure conditions of the paint film are divided by the comprehensive score of three factors. the orientation of the coated wooden structure, the degree of cover of the wooden member, and the installation tilt.

Wait. The exposure conditions of the paint film used on outdoor substrates are 3 levels according to the requirements and scoring methods in Table 5.

1) Moderate

2) Medium

3) bad

Figure 1 Distribution of scores and coverage of wood components in the direction of exposure

Table 5 Classification of paint exposure conditions

Influencing factors

Corresponding score of each factor Total score exposure conditions rating Coated wood Component orientation Northwest to northeast (Climatic factors Loud) Northeast to southeast Mid-west to north-west direction (Climate factors have a greater impact) Southeast to northwest (climate Factors have a great impact)

3 Moderate

Covering degree Fully covered Partially covered Uncovered 4-6 Medium Tilt vertical tilt about 45° horizontal 7-9 harsh Note. 1 The application environment of coatings on outdoor wood is affected by various climatic factors, such as. light, temperature, humidity and so on. These factors affect the size mainly by wood the orientation and direct exposure of the position of the wood members determine the intensity of light, moisture changes and the growth of microorganisms such as the wall of the coating.

The light level, temperature, and moisture change on the south side are greater than those on the north side. The calculation method of the exposure conditions in Table 5 is as follows.

Exposure conditions. 1) Orientation with a score of 1; 2) No cover, a score of 3; 3) Vertical, a score of 1. The total score is 1 3 1 = 5, that is, the exposure conditions are medium.

5 Requirements

5.1 Test items and methods

The outdoor use performance test items of the coating are divided into mandatory test items and optional test items. The mandatory and optional items are implemented as follows.

1) Mandatory items are items that must be tested for outdoor wood coatings, and the results are used as the basis for assessing the level of paint use. test the method is performed as shown in Table 6.

2) The optional test items are formulated by the product supplier according to some special requirements of customers, and one or more of them can be selected. Optional the test item results are not used as a criterion for determining whether the performance of the coating meets the requirements.

Supplementary proof.

Table 6 Requirements for coating test items

Test item test method Coating grade (see 4.2) Stable and stable Base material made of pine Waiting performance test Must test must test according to Appendix A of this standard the water permeability test shall be performed in accordance with Appendix B of this standard.

Other tree species as substrate Natural aging test Optional according to Appendix B of this standard Artificial aging test GB/T 33569-2017 Outdoor Wood Finishing Table Surface artificial aging test method Optional Optional Anti-mildew test GB/T 1741-2007. Determination of mold resistance of paint film Antibacterial and moss optional Dry adhesion test GB/T 4893.4-2013. Physical and chemical paint film of furniture surface Performance testing-Part 4. Adhesive cross cutting Assay Optional Optional Paint film impact test GB/T 4893.9-2013. Physical and chemical paint film of furniture surface Performance test Part 9. Resistance of paint film on furniture surface Impact test Optional Optional

5.2 Performance

5.2.1 Weatherability

The weathering performance testing indicators of the coatings are performed in accordance with the natural aging performance testing method in Appendix A. The test results are classified according to Table 7 for coating applications.

Table 7 Weatherability requirements

Detection Indicator

Coating use

Stable and stable

Blister 0.3 0.7 1

Cracking 0.7 1.7 3

Exfoliation 0.3 0.7 1.3 Adhesion 1 1 1 Note. 1) The values of blistering, cracking, peeling and adhesion in the table are the average values of the results of the three outdoor aging test panels in each group.

begging.

5.2.2 Water permeability

The water permeability of coatings is implemented in accordance with the test method for water permeability of coatings in Appendix B, and the test results are classified according to Table 8 for coating applications.

Table 8 Water permeability of coatings

Coating use

Test items

Stable and stable

Water absorption 30g/m2 ~ 175g/m2 175g/m2 ~ 250g/m2 More than 250g/m2

5.2.3 Performance of optional test items

The test results of the optional test items are obtained as additional properties of the coating by the optional test methods in Table 6.

Standards are required to be obtained and expressed in the law. Additionality cannot be used as a condition for judging whether the performance of outdoor coatings meets the requirements, but only as coating performance the supplementary instructions are used.

6 Coating Performance Report

In addition to the general information provided by the outdoor wood coating supplier to the demand-side coating product, the outdoor use information of the coating product must be given, see Appendix C. The report contains the following.

1) Coating thickness, hiding power and gloss level (measurement of coatings according to the methods listed in 4.1, 4.2 and 4.3);

2) Use level of coatings (by the test method of natural aging performance of coatings in Appendix A and water permeability of Appendix B in this standard) the test method is used to determine the coating application according to 6.2.1 and 6.2.2 of this standard);

3) Additional performance information (performance results measured according to the optional test standards in Table 6) Appendix A (Normative appendix) Test method for natural aging performance of paint film

1.1.8 A.1 Substrate

The board used to prepare the test coating substrate is consistent with the requirements of 7.1 of ISO 16053-2018 and should meet the following requirements.

1) The texture is straight, no knots, no cracks, no signs of fungal or bacterial infection, and abnormal holes. Normal growth wheels (such as 3-8 Growth wheels, each with a width of 10 mm), the inclination angle of the growth wheels is 5 ° to 45 ° (Table A.1).

2) When comparing the natural aging performance of different coatings, choose pine as the substrate.

Table A.1 End face selection of sheet samples

The base material of the annual ring and the heartwood is "sqrt".

"×" is not desirable There is no heartwood on the exposed surface. The distance between the heartwood and the exposed surface is greater than 10mm.

5 °-45 ° to the exposed surface sqrt Heartwood is less than 10mm from the exposed surface the annual rings of the plate are not between 5 °-45 °. Annual rings on the left side of the plate the slope is -10 ° and 30 ° on the right. The surface of this sheet contains annual rings Tends to 0 °, easy to crack Annual ring orientation is not between 5 °-45 °

1.1.9 A.2 Test piece size the sample is processed into a size of (375 ± 2) mm × (78 ± 2) mm × (20 ± 2) mm (L × T × R), the surface is smooth and flat without opening (Figure A.1A) to ensure that the coating is evenly distributed on the surface of the substrate. Before finishing, the surface of the substrate should be polished with a mesh size of not less than 150 mesh, and then Use an air gun to remove wood powder from the surface. After sanding and cleaning, the substrate is finished immediately.

1.1.10 A.3 Base coating the finishing steps and requirements of the substrate are consistent with the requirements in ISO 16053-2018 7 as follows.

1) Prior to finishing, the substrate is adjusted to a constant quality under the conditions of temperature (20 ± 2) °C and relative humidity (65 ± 5)%. After finishing, coating Keep the panel under the same conditions during drying.

2) For each group of experiments, four substrates are randomly selected for coating and used as coating test samples. Three paint test specimens for natural aging outdoor exposure for light experiments, a block was stored indoors as an unaged control.

3) The annual ring convex surface of each substrate is coated with paint as the test surface. The sides are also painted with paint. Back and end protection of substrate Keep clean and uncoated (Figure A.1C).

4) The thickness of the coating is ± 20% of the reference usage provided by the coating supplier. Record the amount of paint on each test board and calculate the average of four test board coatings. Coating dosage is expressed in units of g/m². Wet film thickness (micron) can also be used.

As a unit.

Explanation.

A-- Schematic of substrate plus size;

B-- Dimensional drawing of finishing and capping C-- Finished board

Figure A.1 Schematic of substrate size, finishing and capping

A.4 Test sample capping After the test coating is completely dry, use a flexible, moisture-proof and water-impermeable white coating (such as long oil alkyd resin) to test the plate.

The ends are sealed, and at least 2 layers are completely sealed. The sealing coating should be able to withstand 2 years of natural exposure without cracking. Sealant can be applied by brush or dip. The five surfaces (section, top, bottom, and side) of the two ends of the plate are sealed with a sealant for at least two layers (Figure A.1B).

The seal width of a section is 50mm, which is used to mark the test piece number and the test piece is fixed on the aging rack, and the other end is 20mm. The seal coating part is used for Fix it on the aging rack (Figure A.2).

A.5 Equipment

A.5.1 Aging rack aging site requirements shall be implemented in accordance with GB/T 9276-1996. The aging rack shall be placed on grass with storage humidity (see figure) A.2). When the aging rack test piece is placed in the exposure area, it is inclined at an angle of 45 ° to the horizon. There is no obstruction around the test piece.

Guarantee the test piece can get the longest light in a day. The aging rack partition should be slightly larger than the size of the test piece, and the test piece is fixed by the fixing bar on the rack without damage.

live. There should be spacers between the fixed specimens to separate each specimen. The aging frame should be made of stainless steel.

A.5.2 The gloss tester is prepared according to the requirements of GB/4893.6-2013. The incident angle is 60 °. The gloss of the aged surface is measured with a gloss meter A.5.3. The colorimeter refers to GB/T 11186.1-1989, GB/T 11186.2-1989 and GB/T 11186.3-1989 require the preparation of three-color A colorimeter or spectrophotometer that measures color and calculates the color difference in CIE 1976 (L * a * b *) coordinates.

A.5.4 Tapes and cutting tools are prepared in accordance with the requirements of GB/T 9286-1996, and tapes and cutting tools for measuring the adhesion of paint films are prepared.

A.5.5 Stereo microscope can observe surface defects at a magnification of more than 10 times.

A.5.6 Micrometer is prepared according to the requirements of GB/T 13452.2-2008. Refer to Method 4A to measure the coating thickness using a micrometer.

A.5.87 Self-adhesive and scotch tape are prepared in accordance with the requirements of 3.5 in GB/T 4893.4-2013, and are used to evaluate the chalking rating after aging of paint film.

Figure A.2 Schematic diagram of the aging rack

A.6 Test and detection methods A.6.1 Detection before exposure After the paint on the test board and the capping paint are dry, the test board is balanced at a temperature of (20 ± 2) ° C and a relative humidity of (65 ± 5)%. 7 Days before testing.

A.6.1.1 Initial defects After the test sample has completed all pre-exposure finishes, the test sample should be inspected for defects again. If minor defects are found, such as for small cracks, knots, etc., detailed defect types, sizes, and position markings are made and continuously observed in the experiment. If the test piece defect is exposed If there is no abnormal change, you can continue to use this test sample to collect data. Special analysis is required for the results analysis.

A.6.1.1 Paint film thickness the dry film thickness of the coating was measured using a test panel placed indoors as a control. According to 5.2 Method 6A of GB/T 13452.2-2008 the specified test film thickness in micrometers. The coating that penetrates the wood substrate is not within the measurement range of the coating thickness.

The coating thickness on the surface of the material is the dry film thickness.

A.6.1.2 Other parameters A.5.1.2.1 Quality of the test sample Use a balance to weigh out the mass of the test sample after the balance in B.5 with an accuracy of 0.01 g.

A.5.1.2.2 Gloss The gloss of paint film shall be tested in accordance with GB/T 4893.6-2013. Each test sample is equally spaced along the width and length of the test piece Six points were selected for detection, and the average value containing the standard deviation was finally taken as the gloss value of the test sample.

A.5.1.2.3 Color Determine the color of paint film before aging according to the method specified in 4.32 of GB/T 17657-2013. Each test sample follows the test Six points of the width and length of the piece are taken at regular intervals for testing. Finally, the average value containing the standard deviation is taken as the chromaticity value of the test sample.

A.5.2 Outdoor exposure methods Fix 3 pieces of each group of test samples after collecting the parameters on the outdoor aging rack. Use the spacer block to level each test sample during the fixing process.

Separated (see Figure A.3). All test pieces were evaluated for aging performance after 12 months of outdoor exposure. Record start-stop outdoor exposure time.

Store indoor reference samples in a room with a temperature of (20 ± 2) ° C and a relative humidity of (65 ± 5)%.

A.5.3 Inspection after exposure A.5.3.1 Inspection on aging rack when the test sample has finished the 12-month outdoor aging test, the test sample on the aging rack should be tested for its appearance and recorded immediately outdoors.

record.

A.5.3.2 Test sample balance After finishing the test on the aging rack, remove the test sample intact and place it at a temperature of (20 ± 2) ° C and a relative humidity of (65 ± 5)%.

Condition for 7 days before testing.

A.5.3.3 Detection of aged paint film A.5.3.3.1 Changes in appearance According to the requirements of 4.1 of GB/T 33568-2017, visually observe the aged paint film surface and evaluate the paint film surface.

The degree of change in surface damage, the number and size of damage areas, and the assessment results are in accordance with Table 1, Table 2 and Table 3.2 of GB/T 1766-2008.

Table 3 is used for classification. Finally, the average value containing the standard deviation is taken as the appearance change value of the test sample.

A.5.3.3.2 Foaming According to the requirements of 4.4.9 in GB/T 33568-2017, observe the bubble density and size on the surface of the paint film. Each test sample the test piece is divided into three zones at equal intervals along the width and length of the test piece. The density and size of the bubbles are in accordance with GB/T the values in Tables 17 and 18 of 4.9 i...

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.

Referenced standards

Normative references

ISO 4618 · ISO 16053-2018

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