WOOD COATINGSTrim Paints and Exterior Joinery

Protect wood against UV radiation, moisture and microbial attackPossible avenues include chemical treatment, impregnation and surface coatingsUse of Synthomer‘s waterborne binders in coatings boosts drying time and colour retentionWaterbased polymers are catching up due to the European VOC-directive 2004/42/EC Wide variety of polymers and convenient starting formulations as a service to your business

Example for the stable end use category:windows and doors (joinery)

Saving the wood(s): coatingsWood coatings in exterior settingsWWood has been used as a renewable building material for thousands of years. The wood species used are generally divided into softwood (e.g. pine, spruce, and larch) and hardwood (e.g. oak, meranti and merbau). The different woods show a big variety in component levels – lignin, cellulose / hemi-cellulose and wood extractives. Due to their biological origin these materials are susceptible to dedeterioration through environmental impacts like weather (UV-light, freeze-thaw and humidity), insects, microorganisms (fungi and algae) or fire.

Another specific challenge is the thermomechanical stress created by short-term temperature cycles (heating up to 80°C of dark brown colour-shades in the sun and cooling down over night; delta T= ca. 70°C) in combination with swelling and shrinking of the wood caused by moisture take up and release. Exterior wood coatings are needed to protect the wood by means of chemical treatment, impimpregnation and surface coating.

“Coating materials and coating systems for exterior wood” - EN 927In EN 927-1 “Classification and selection” the end-use categories are defined regarding their permitted dimensional movement:

• Stable - windows and doors (joinery)• Semi-stable - cladding, wooden houses and garden furniture • Non-stable - fences, garden sheds and terrace decking

InIn EN 927-2 “Performance specification” the necessary criteria for passing the classifications are defined. The detailed tests are described in EN 927-3 “Natural weathering test”, EN 927-4 “Assessment of water-vapour permeability”, EN 927-5 “Assessment of liquid water permeability” and EN 927-6 “Artificial weathering using fluorescent lamps and water (QUV-A)”.

OtherOther important triggers to determine the correct coating system:

• Exposure conditions (mild, medium and severe) determined by climate and construction (sheltered / not sheltered)• Hiding power: Opaque, semi-transparent, transparent• Film build: minimal (< 5 µm DFT ) to high ( >60 µm DFT)•• Gloss 60°: Matt (<10GU) to high gloss (>80 GU)

Finding the magic formulaRequested properties of exterior wood coatingsExcellent performance regarding:

• exterior durability (min. 5Y, preferably 10Y maintenance-free)• early water-resistance (resistance to white-blushing)• low water absorption and permeability•• blocking resistance at RT and 50°C• elasticity at low temperature (<0°C)• hailstorm resistance• wet adhesion• no / low coalescent demand (compliant with 2004/42/EC – VOC-directive)

AdAdvantages of Synthomer acrylic dispersions vs. SB alkyds and alkyd-emulsions:

• quick physical drying and hardness development• no yellowing• good colour retention• permanent elasticity AdAdvantages of SB alkyds and alkyd-emulsions vs. acrylic dispersions:

• haze free high gloss > 80 GU @ 20° achievable• longer open-time• better wet-edge• better levelling• better penetration properties

Formulation of exterior wood coatingsIn Europe SB alkyds still cover approx. 70% of exterior wood coatings mainly in trim paints. However driven by legislation e.g. European VOC-directive 2004/42/EC water-borne binder technologies are now more catching up.

WWaterborne binder technologies for exterior wood coatings comprise alkyd-emulsions, acrylics, PUD / PUD-acrylic hybrids and VACOs. Alkyd-emulsions are used preferentially in penetrating primers or AE / Acrylic hybrid top-coats. PUD / PUD-acrylic hybrids are high priced products used where high permanent elasticity is required e.g. extra durable Joinery. VACOs are mainly used in cheap non-stable applicationsapplications e.g. for fences. Acrylic dispersions show the biggest formulation latitude and cover approx. 15 % of the market.

Formulation recommendations for WB exterior wood coatings:

• UV-protection: For opaque top-coats use acrylics or pure-acrylics, for translucents solely pure- acrylics. Good UV-protection level is established if more than 98 % of wavelengths 280 – 440 nm is absorbed before reaching the substrate. In case of opaque coatings the substrate is already protected and only 0.5 % HALS should be added to protect the binder. In translucent top-coats preferably transparent iron oxide red and yellow should be used. A level of 2 % w/w is usually sufficient. Otherwise use a combination 1-2 % UV-Absorber, preferably 2-hydroxyphenyl-s-triazine (HPT) and 0.5 % HALS.

In preparation for the coating • Thickener: For optimal early water resistance PU thickeners are preferred. If high sagging resistance is required e.g. 300 µm wet with Joinery topcoats, acrylic thickeners can be used, preferably HASE. Classical ASE-thickeners should be used sparingly due to poor early-water / white blushing resistance

•• Defoamers: For air-mix/spray application deaerators e.g. Tego Airex 902 W are recommended. For brush and roller application a combination of a defoamer to control microfoam e.g. Tego Foamex 810 and a mild defoamer e.g. Tego Foamex 825 are recommended

•__Coalescents: In general mixtures are recommended which consist of faster evaporating types e.g. Dowanol DPM, PnB or Butyl glycol. Slower evaporating types like DPnB or Butyl diglycol should only be used as little as possible to achieve a MFFT of 0°C. Furthermore propylene glycol in a level of up to 3 % can be used to increase open-time in trim-paints.

Preparation of the substratesTheThe substrate should be smooth (sanded or planed), clean and free of dust and free water. The relative humidity of the wood should be in the range of 12-15 %. Softwood is especially susceptible to discoloring (Blue Stain) and wood destroying fungi. Therefore it has to be protected by biocidal impregnations (BPR), either applied by vacuum or dipping / flow-coat.

Application example:Trim paint applied by brush

If the wood species releases wood extractives e.g. knot-staining of pine or gallic acid of oak, it has to be sealed upfront with a stain-blocking primer (e.g. based on Plextol R 5530).

HaHardwoods e.g. meranti generally have bigger pores of up to 300 µm, which have to be wetted or covered completely. Otherwise insufficient adhesion or flaking-off can occur. A well penetrating primer or a binder with excellent wetting properties is required e.g. Plextol R 5530.

ApplicationsTheThe application depends whether it is factory applied or on-site. Typical application for trim paints and translucents on-site is by brush or roller. In factory application, especially joinery, the primers are applied by dipping or flow-coat. Top-coats are applied by conventional air spraying or air-mix.

Our broad portfolio for wood coatings

Product Solid Content [%] Tg [°C]EN 927End-use categoryMFFT [°C]

Plextol R 825

Plextol R 5335

Plextol R 5530

Plextol R 5441

Notes: *Data describe typical properties - not product specifications

47.0

46.0

46.0

49.0

15/65

22

33

-10/10/55

Stable

Semi-Stable

Not applicable

Semi-Stable

10

14

19

0

Emulsion properties*

Polymers for exterior wood coatings

Product

Plextol R 825

Plextol R 5335

Plextol R 5530

Plextol R 5441

Application Recommended use

High gloss potential (85GU 60°), good blocking resistance, self-crosslinking

Excellent exterior durability, high flexibility, excellent wet adhesion

Excellent wetting and stain-blocking

MFFT 0°C, excellent durability, ADH-free

Opaque trim-paints

Translucent primer and top-coat

Primer / stain-blocking

Exterior joinery translucent

Our starting formulations

1

2

3

4

5

6

77

8

9

10

11

12

13

1414

Starting formulation 2012-2526: Gloss paint (85 GU 60°) on Plextol R 825

Ingredients

Water

Dowanol DPM

Acticide MV

Drewplus S4288

Edaplan 482

Tiona 595

RheolaRheolate 244

Propylene glycol

Water demi.

Plextol R 825 (47 % S.C.)

Water demi.

Dowanol DPM

Dowanol DPnB

RheolaRheolate 244

Instruction: Grind Pos. 1-7 for 20 min at 4000rpm.

Pre-mix Pos. 8-9, add to Grind at slower speed, then add to binder.

Pre-mix Pos. 11-14, add to mixture, mix till homogeneous.

Supplier

Dow Chemical

THOR

Drew Ameroid

Münzing

Cristal

Elementis Specialties

SSynthomer

Dow Chemical

Dow Chemical

Elementis Specialties

Role

Coalescent

Biocide

Defoamer

Surfactant

Pigment

Thickener

WWet edge extender

Binder

Coalescent

Coalescent

Thickener

3.50

1.00

0.20

0.30

1.00

21.70

1.501.50

2.90

3.70

60.30

0.70

0.80

1.70

0.700.70

100.00

pbw

1

2

3

4

5

6

77

8

9

10

Starting formulation 2012-1416: Exterior woodstain based on Plextol R 5335

Ingredients

Water

Acticide DW

Foamaster NXZ

Coatex BR100

Propylene Glycol

Luconyl Red 2817

Acticide Acticide LG

Michemlube 270

Butyl diglycol

Plextol R 5335 (46 % S.C.)

Incorporate Pos. 1-10 under stirring then mix 20 min at medium speed.

Supplier

THOR

BASF

Coatex

THOR

BASF

THOR

MichelmanMichelman

Synthomer

Role

Biocide

Defoamer

Thickener

Coalescent

Colorant

Biocide

Matt Matt Wax

Coalescent

Binder

20.60

0.50

0.10

0.40

4.00

4.00

0.200.20

3.00

2.00

65.20

100.00

pbw

Additional starting formulations available on request through our Technical Service team.

America, Europe and South East Asia. In March 2017, we acquired the coalescing agents and Butyl Ethyl Propanediol (BEPD) business from Perstorp Oxo Belgium AB. The newly acquired businesses significantly improve our footprint to a number of speciality markets which we will continue to serve through a strong network of local technical service and sales branches, supported by regional application dedevelopment and production in our key markets. We deliver the right formula, globally, individually.

Synthomer is one of the world’s leading suppliers of emulsion and speciality polymers supporting leadership positions in many market segments including coatings, construction, technical textiles, adhesives, paper and synthetic latex gloves. The company has its Head Office in London (UK) and provides customer focused services from operational centres in Harlow (UK), Marl (Germany), Kuala LumpurLumpur (Malaysia), Shanghai (China) and Dubai (UAE). In June 2016 we have acquired the Monomers, Dispersions and Powders business (MDP) from Hexion with dedicated production sales and customer service facilities in North

Disclaimer: This information and any other advice or recommendations given or made by us (collectively “Information”), are provided in good faith and are not intended to, nor do they, constitute professional advice or services. Information is provided “AS IS” and on an “AS AVAILABLE” basis and without warranty. We do not warrant or accept responsibility for the accuracy, timeliness or completeness of the Information, or for the suitability of the Information for a particular purpose. We do not accept responsibility, and exclude all liability (including(including under any implied warranties), for any matters arising out of or in connection with your reliance on the Information (including as to infringement of third party intellectual property rights) to the fullest extent permitted by law. Any Information concerning any possible use or application of Synthomer products is given by us in good faith; we do not warrant the fitness of any Synthomer products for any particular purpose and it is entirely for you to satisfy yourself fully as to the suitability of Synthomer products for any particular purpose. purpose. Synthomer products are sold in accordance with Synthomer’s standard terms and conditions of sale which are available from www.synthomer.com/tc.

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info@synthomer.com

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www.synthomer.com

Leading in emulsionsand speciality polymers