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What are the key formulating techniques for optimizing an elastomeric weather-barrier formulation based on UCAR Latex 123?
UCAR 123 is a high performance styrene-acrylic latex for use in elastomeric weather-barrier coatings. Elastomeric coatings based on UCAR 123 are resistant to wind driven rain and alkaline conditions, have excellent adhesion to a variety of substrates, and have proven exterior durability both on the UESM test fence and in commercial use. Good formulating techniques are vital to achieving maximum performance with UCAR 123.

Formulating with UCAR 123:

1. Optimum PVC range is 40-46%.
2. Dirt pickup resistance is minimized at the high end of the PVC range, 45-46%. Also, plasticizers should be omitted from the formulation to minimize dirt pickup.
3. Adhesion over urethane foam typically can be improved by the use of "Booster" latexes such as UCAR Latex 6046 and urethane rheology modifiers.
4. To obtain the best low temperature elongation and flexibility, formulate at a PVC of 40-42% and use 5% plasticizer such as Santicizer 160 based on polymer solids.
5. Some UCAR Latex 123 can be used in the pigment grind. Avoid high temperatures (>125°F) in the grind and keep pH in the 8-9 range to insure good stability of the latex in the grind.

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How do I make a good Direct-To-Metal (DTM) Coatings for Interiors and Exteriors?
Direct-to-Metal (DTM) coatings are applied to metal substrates. While usually applied over a primer, they may be applied directly to the metal surface and are expected to perform well in either situation. They are generally high gloss coatings (80-85, 60° gloss). Within the UESM line, UCAR DM166 offers the best all around properties for DTM applications. Latex 481 makes an effective DTM with good flow and leveling, high gloss, block resistance, and good flash rust resistance. For primers, Latex 461 is recommended formulated with flash rust additive and inhibitive pigment. Latex 461 shows good humidity resistance, Prohesion corrosion resistance, and fair salt fog resistance. Latex 471 can be used where high block resistance is required.

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How do I make an intumescent coating or sealant?
UCAR Latex 367 has been used for years in intumescent systems. Because of the additives used in these coatings and sealants a very stable binder system is needed. Intumescent paints need to include three basic components:

1. A source of carbon (carbonific): dipentaerythitol is an example. To work correctly, you need to have hydroxyl groups and an abundance of carbon. This carbonific must also be more thermally stable than the catalyst.
2. A catalyst: This is a source of phosphoric acid and subsequently, must have a high level of phosphorous. The catalyst decomposes to form the phosphoric acid. This should happen before the carbonific decomposes. Phos Chek P/30, from Solutia, is a well known source for phosphorus.
3. A blowing agent: This is used to expand the carbon char into a foam structure. It must be a product that will release a non-flammable gas. Urea and melamine have been used as blowing agents.

If only resistance to flame is required there are a number of formulating variations that can be tried including:

1. Maintain a high pigment to binder ration and low organic level. Calcium carbonate will not burn. This will limit both the flame spread and the smoke development.
2. Try adding functional fillers. Under high temperature conditions gypsum will release two molecules of water, aluminum trihydrate will release three molecules of water. The release of water will enhance the product's resistance to flame spread. A good starting point is with a basic high P/B painter caulk. Substitute one of the functional fillers mentioned above for the calcium carbonate in the formula.

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How can I improve color float?
We found that a sepiolite clay, Pangel S-9, played an important role in reducing the in-can heat-aged color float of three pastel tint base formulations: flat, eggshell, and semigloss. Color float of the paints without Pangel S-9 was rated as heavy; with Pangel S-9 added at a level of 2# per 100 gallons, the color float improved and was rated from slight to moderate. Universal Colortrend 888 type B, C, and E colorants were utilized.

The Pangel S-9 clay is distributed by J.M. Huber Corp.

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How can I improve the substrate wetting and recoatability of the NEOCAR™ Acrylic 820 sealer formulations?
NEOCAR Acrylic 820 and 850 based sealers produce outstanding, hydrophobic films. While unsurpassed for water resistance, this very property can be a problem when attempting to apply a second coat. The hydrophobic surface of the first coat may be very difficult to wet out with a second coat of a water based paint.

To improve the wetting ability of formulations based on NEOCAR Acrylic 820 we recommend trying one of the following:

• For better wetting the addition of an anionic surfactant is recommended. Byk 346 at a level of 1.5% - 3.0% on latex solids has been shown to provide good wetting properties. A 24 hours equilibration is recommended before testing.
• Use Butyl CELLOSOLVE™ as the coalescent at a level of 10% on latex solids. No equilibration period is required.

With either of these modifications to Formulation Suggestion E-2493, this sealer can be brushed over a sealed Leneta Chart with no crawling. Recoatability is also enhanced.

Testing indicates that these modifications do not compromise the performance properties of the NEOCAR 820 sealers. However, we would recommend that if either of these modifications were used that the resulting product be qualified before approval.

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How can I balance low, mid and high shear viscosities when utilizing hydrophobic coalescent aids?
In developing a low odor interior semigloss formulation containing UCAR Latex 626 we used the low odor coalescent Velate 262 made by Velsicol. This solvent is very hydrophobic and results in extremely efficient and high viscosity response with associative thickeners. In our initial formula, thickened entirely with associative thickeners, we obtained an unacceptably high mid-shear (KU) viscosity and unacceptable low- shear (Brookfield) and high-shear (ICI) viscosities.

To offset the hydrophobicity of the Velate 262 and allow more formulating latitude with the associative thickeners, the dispersants and surfactants were replaced with more hydrophilic alternatives. We also found that adding 1.25# per 100 gallons CELLOSIZE™ QP-4400 improved the rheology of the paint with increased Brookfield viscosity. We were then able to use UCAR POLYPHOBE TR-117 to build the ICI viscosity to an acceptable level while maintaining the proper KU viscosity. Another benefit of the added CELLOSIZE QP-4400 was improved color float.

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What wax emulsion additive works well in NEOCAR Acrylic 820 sealer formulations?
Michem Lube 270R is a water based, anionic emulsion with 39% total solids. It was found to have excellent performance when evaluated in the Formulation Suggestion E-2498, a Semi-Transparent Stain from the NEOCAR Acrylic 820 bulletin.

Michem Lube 270R has a great affinity with NEOCAR Acrylic 820 and imparts superior properties to the system inlcuding:

• Diminished pigment settling.
• Increased hydrophobicity of the system, imparting excellent water repellency properties by swellometer and gravimetric measures.
• Increases the contact angle of the system - another measure of the water resistance and water beading characteristics.
• Good gloss development

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What hydroxyl/isocyanate ratio works best for two component acrylic/urethane systems?
Latex/urethane blend results:

• Rhodocoat WT-2100 and WT-2102 at low levels were found to be compatible with UCAR Latex 451, 452, 462, 462S and 9176.
• The addition of the urethane improved MEK rubs of all the latexes tested.
• UCAR Latex 451 was the most responsive to the addition of urethane of all the latexes tested.

The following ratios were tested on a stoichiometric basis:

Rhodocoat WT-2100 and WT2102 are from Rhodia, Inc. Rhodia literature states that potlifes of 3 - 4 hours are obtainable with these systems. In latex systems, crosslinking can occur within the latex particle so potlifes are best determined by dry film properties (such as gloss or solvent resistance). Dry films of 4 dry mils are obtainable without gassing defects. Gassing occurs via the reaction of the isocyanate group and water. (Reaction biproduct of CO₂).

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Why is checking the density and percent total solids of new latexes important when experimenting with new formulations?
When using a new sample of latex in a formulation it is best to check the density and the percent total solids against the literature before making calculations based on this information. A small variance in either parameter can have significant effects on the formulating process. Oftentimes, both the published density and latex total solids vary from the actual sample.

If the latex has been sitting unused for an extended period of time, the latex total solids and density may have changed due to settling. Again, it is beneficial to verify the physical properties before completing formulations.

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How can I improve mud-cracking in a low VOC system?
We have found that by changing the extender pigments, mud-cracking and low temperature coalescence can be improved without adding coalescent or glycol. In particular, some diatomaceous earth pigments, added for rheology control and durability, decrease a paints ability to form a film at low temperature. Diatomaceous earths have a high oil absorption (o.a. value = 120 as per ASTM-281). The high oil absorption may contribute to mud-cracking. Substituting lower absorbing fillers can improve mud-cracking significantly! We found these results to be consistent in formulations based on several commercially available vinyl acrylics.

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I just substituted another latex in my formulation but now have color problems. How can I improve the color acceptance and color development of my paint?
Differences in color acceptance and color development can occur when substituting one latex for another in many formulations. Changes in tint strength or some pigment flocculation may be apparent. This is often the result of a surfactant imbalance. The type of flocculation, either colorant or titanium, is formulation dependent. Nonetheless, this can be improved by substituting the current surfactant package with a 50/50 solids blend of TERGITOL™ NP-40 (70% solids, HLB = 17.8) and TRITON™ N-57 (100% solids, HLB = 10.0). The combination of a low and high HLB surfactant improves the tint strength and flocculation issues to within 98-102% of the control system. This surfactant combination has improved color acceptance issues in several systems ranging from economical flats to high gloss paints.

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How can I enhance tannin stain resistance of a paint?
The tannin blocking of a coating can be enhanced by using the functional pigments zinc oxide and/or barium phosphosilicate pigment(s). The cedar tannin resistance of a solid hide stain (Suggested Formulation E-2499) based on UCAR 627was enhanced with the following substitutions:

• Substituting 20#'s of zinc oxide for Minex 4.
• Substituting 50#'s of barium phosphosilicate for Minex 4
• Substituting 10#'s of zinc oxide and 25#'s of barium phosphosilicate for Minex 4

All substitutions were made on an equal volume solids basis. The stains were tested on cedar boards as two coat, self-priming systems. The formulation containing 50#'s of barium phosphosilicate had the best tannin resistance and was significantly better than the control, a formulation made according to Formulation Suggestion E-2499 with no functional pigment modification. The formulation containing 10#'s of zinc oxide and 25#'s of barium phosphosilicate was a close second in performance and is the best choice for cost-effectiveness combined with tannin resistance. The formulation containing 20#'s of zinc oxide was third for tannin resistance.

In a study performed on another formulation (E-2490A) based on UCAR 627, liquid tannin blocking additives were evaluated as zinc oxide replacements. These were utilized, as supplied, at 2.5% on total formulation weight. The additive Stainban 185 was found to be an effective replacement for zinc oxide.

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How can I Improve the Block Resistance of semigloss coatings?
The anionic phosphate-ester surfactants Strodex PK-0VOC and Strodex PK-90 (both from Dexter Chemical Corp.) can improve the early block resistance of semi gloss formulations. Improvements were seen with both surfactants but the PK-0VOC is recommended over the PK-90 because of its following properties:

• Zero VOC
• Much lower viscosity for easier handling
• Slightly better block improvement at equal actives level
• Caused no increase in dissipation time of foam in the applied paint

Strodex PK-0VOC, used at a level of 2.5#/100 gallons (as supplied), improved the 1 day block resistance of a semi gloss formulation from a rating of 0 to a rating of 8 at ambient conditions. The 1 day elevated block resistance improved from a 0 to a 6 rating. The PK-0VOC had a small detrimental effect on adhesion, mainly on wet adhesion to gloss alkyd. No other properties were affected, included colorant compatibility, freeze-thaw resistance, and heat stability.

Other anionic surfactants such as Triton GR7M, have also been shown to improve block resistance. It is thought that anionic surfactants impart a charge to the surface of the film. Due to like charge repulsion, blocking is reduced.

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What effect does coalescent have on the water resistance of NEOCAR 850 Clear Sealer?
The effect of varying either or both type and level of coalescing solvent on the water resistance of the NEOCAR 850 Clear Sealer for Masonry Formulation Suggestion E-2528 was tested. The substrate used was smooth cement blocks. Sealers were made following Formulation Suggestion E-2528. The only variation from this formulation was the type of coalescent, UCAR Filmer IBT or Butyl CARBITOL™; and the coalescent level, 10%, 15%, and 20% based on resin solids. One coat was applied by brush to the cement blocks and allowed to cure overnight. Water resistance was tested by placing cotton pads saturated with water on the surface of the sealers. The test duration was four hours. Water penetration into the cement causes darkening of the cement surface.

• Clearly the best system for water resistance was NEOCAR 850 coalesced with UCAR Filmer IBT at 15%.
• The coalescent, Butyl CARBITOL, had poor - fair water resistance at all three use levels and at the 15% and 20% levels showed poor surface wetting properties.

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What is the best way to prevent microbial contamination of my finished products based on UCAR latexes?
The first line of defense is keeping storage and manufacturing areas clean. Potential sources of contamination include raw materials, mixing tanks, hoses, and measuring containers. Cleaning equipment on a regular basis goes a long way towards preserving product life.

In addition to keeping conditions clean, biocides are also an important part of preventing product spoilage. There are many preservatives that are commercially available.

As with any formulation change, a full evaluation should be done before implementation.

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How can I improve scrub resistance of an interior flat wall paint.
There are several answers to this question. Scrub resistance of a paint is a function of several properties of the paint including the resin type, resin hardness, pigment type (oil absorption) and level (PVC), additives and other paint raw materials. A very simple approach to improving scrub resistance is simply to lower the PVC of the paint. A related approach is to use pigments with lower oil absorption properties. Both of these approaches result in better pigment binding. This makes the coating tougher and more resistant to the physical scrubbing action of a scrub test.

Another approach is to use high scrub vehicles. Vinyl acrylics are well known to have superior scrub resistance as compared to acrylic technology. Vinyl acrylic technology has advanced further in the last 10 years to enhance the scrub properties of these polymers even more. High molecular weight products such UCAR Latex 357, UCAR Latex 379G, and UCAR Latex 300 (for low VOC applications) have incorporated in them a functionality which enhances scrub resistance well above that of conventional vinyl acrylics. They bind pigment much more efficiently, and typically can be substituted into formulations for conventional vinyl acrylics with only minor adjustments to the formulation.

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What is touch up and what formulation parameters affect this property?
Touch up of a paint refers to how well mars; scratches or other imperfections in small areas of a previously coated surface can be repaired. Poor touch up is typically seen as differences in sheen or gloss and/or color differences. Even when using the same batch of paint a few days later, touch up problems can occur. Touch up issues can be caused by several phenomena, including shear instability, color instability (flocculation), poor titanium dioxide dispersion or flocculation, and poor cold temperature coalescence. Many times wall coatings are spray applied and later touched up by brush. The difference in shear of the brush application and the shear of the spray application can cause differences in either sheen and/or color development. Many of these types of touch up issues can be resolved by improving the wetting and/or dispersant system of the paint. The shearing action of brush application may be different enough from the shear of spray application to cause further dispersion of either TiO2 or colorant. This can lead to either a lighter color in the first case or a darker color in the latter case.

Another common cause of touch up problems is poor film formation of the paint. Typically, paints that may be under-coalesced will show touch up problems when the paint is touched up at a different temperature compared to when it was originally painted. A higher or more efficient coalescent package is an easy fix.

Over about the last ten years flat paints have grown flatter and flatter through the use of very high oil absorbing extender pigments and higher PVC paints. These paints are more attractive to consumers and especially builders because flatter paints hide imperfections in walls much better than higher sheen paints. These pigments, however, have had a negative impact on touch up properties. Recent lab work has shown that using extender pigments with just slightly lower oil absorption can sometimes tip the scale and solve some sheen oriented touch up problems.

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What is the best way to make a water-based semi-transparent stain or clear sealer for wood?
Semi-transparent stains and clear coatings that exhibit long term durability over wood are difficult to make. Even the most UV resistant polymers have problems. UV impervious polymers allow UV radiation to pass through the polymer with little hindrance. The UV subsequently degrades the wood underneath the coating film. The result is flaking of the coating film from the wood because of the degradation of the coating-substrate interface. (It's important to note that this is not because the coating degraded but because of the degradation of the wood). When formulating clears and semi-transparent stains for wood, it is very important to include ingredients that absorb or reflect UV radiation from attacking the wood substrate. For stains, utilizing transparent iron oxide pigments work very well in absorbing UV radiation. These pigments can be utilized in fairly high levels without imparting too much opacity.

Absorbing UV radiation in a clear coating is much more difficult. You must use materials that do not impart any opacity or color to the film. There are a number of UV absorbing additives available from various suppliers. They are typically used at a level of 5 - 10 pounds per 100 gallons.

For lower cost semi-transparent stains, our test fence program has revealed that vinyl acrylics, specifically, UCAR Latex 379G, perform extremely well. It seems that vinyl acrylics act sacrificially in protecting the wood. The polymer apparently erodes away rather than flake away as an unprotected acrylic would. The erosion process of vinyl acrylics are much more attractive then the flaking process that acrylic based products go through.

Water resistance of the polymer in clears and stains is also very important. NEOCAR Acrylic 820, a branched ester based polymer, is ideally suited for this application. With the hydrophobicity of styrene acrylics but the UV resistance of a 100% acrylic, this polymer is best suited for both clears and semi-transparent coatings. As with acrylics, UV absorbing pigments or additives are required to increase the longevity of the coating.

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