Ceramic Industry

Additives & Specialty Chemicals Roundup

October 1, 2005
From anti-setting agents and binders to deflocculants, lubricants and specialty minerals, a variety of additives and chemicals are used to improve production efficiency and enhance the quality and performance of today's ceramic, glass and brick products. Following is a sampling of some new and widely used additives and chemicals available on the market.

Magnesium Alumino Silicate

Active Minerals Co. LLC

In natural and frit glaze suspensions, Acti-Gel® 208 is designed to improve adhesive strength by more than 80%, which helps to reduce surface defects and glaze chipping during handling and shipping. The product eliminates the need for other mineral thickeners and reduces cellulose ethers in glaze formulations, and it allows the glaze to dry rapidly without cracking. According to the company, Acti-Gel 208-based glazes are highly stable and can sit without settling or hard packing for more than three months. The additive also aids in glaze removal from the ball mill, and it is designed to work efficiently in suspensions from 25-80% solids. The product is added directly to the mill for ease of dispersion and contains no sulfates. It should be used without phosphate dispersants such as SHMP or STPP, which chelate excess ions and deactivate the product. However, by using the material to reduce cellulose ethers and phosphate dispersants, the negative effects of sodium are greatly reduced, allowing for increased adhesion strengths and reduced surface defects.

Call (410) 825-2920 or visit www.Acti-Gel.com.



Hectorite

American Colloid Co., Industrial SpecialtiesGroup/Smectite Clay Mineral Group

Hectalite® 200, a magnesium-rich hectorite, reportedly exhibits unique properties that allow it to perform several functions in the production of floor/wall tile at low addition levels. These properties include a small particle size, swelling ability of up to 35 times its weight, thixotropic behavior and a white fired color. Minimal addition levels (0.5-1.5%) of a classified Hectalite 200 to a tile body can greatly increase the green strength due to the high surface area of hectorite, which enables greater ionic bonding to other raw materials, as well as hydroxyl bonding to water molecules in the batch. Additions of hectorite also allow for production of larger tiles without breakage (i.e., reduced losses), and more screen printing glaze application without warping on the edges. The product also acts as a lubricant to ease extrusion, which reduces wear on the dies and lowers energy consumption during extrusion. A non-migratory binder, the product will not migrate to the surface of the tile to cause scumming.

Call (800) 426-5564, e-mail cory.ashburn@colloid.com or visit www.colloid.com/isg.

Borates

U.S. Borax Inc.

This company has developed Evansite®, a microfine sodium pentaborate in a sugar suspension that is specifically designed to meet the heavy clay industry's economic and technical needs. The sugar prevents the borate from migrating to the surface during drying, and it transforms sodium pentaborate's high solubility from a disadvantage to an advantage by allowing the borate to dissolve in the relatively low moisture content of the clay body. This ensures optimum distribution in the body and even vitrification. Once the clay body is dried, the sugar is burned off during firing, and the borate can begin fluxing. The new borate can help heavy clay manufacturers save fuel through both reduced firing temperatures and increased push rates. Product benefits include improved durability, compressive strength, abrasion resistance, reduced efflorescence, leaching resistance and reduced porosity. Additionally, manufacturers can make more efficient use of other raw materials by adding the new borate to their batch.

Call (44) 1483-242032 or e-mail adrian.stubbs@borax.com.

Mineral Dispersants

Kemira

This company's COLLOID 211 sodium polyacrylate polymer is used as a mineral dispersant in the ceramic industry. These and other polyacrylate polymer and copolymer dispersants are available with varying molecular weights, degrees of neutralization (pH range 2.5 to 13.5), neutralizing agents (sodium hydroxide, ammonium hydroxide and others), and a low sodium content. A series of specialty blends under the TC product line is used for the dispersion of ceramic material in applications such as floor and decorative tile. The company also supplies AMA® Biocides for the preservation of mineral slurries, as well as the INDUFOAM® Defoamer line of water-based and mineral-oil-free concentrated defoamers for wastewater treatment, manufacturing process applications, and various product applications.

Call (800) 347-1542, e-mail front-desk@kemira.com or visit www.kemira.com.

Barium Carbonate

Kraft Chemical Co.

Barium carbonate is available in many different grades and has a variety of uses in the ceramic and glass industries. For example, barium carbonate powder is used in the production of specialty glasses such as crystal and television glass to decrease solubility, increase density and improve brilliance. Barium carbonate is also used to remove sulfates in the brick, tile and ferrite industries, as well as in phosphoric acid production and chlorine alkali electrolysis. The product can also be used to purify tartaric acid.

Call (708) 345-5200, e-mail kraftchemnancy@aol.com or visit www.kraftchemical.com.

PVOH and PVB

Kuraray America, Inc.

Mowiol® and Kuraray Poval® polyvinyl alcohols (PVOHs) are used as temporary binders in a range of ceramic applications. Polyvinyl butyrals (PVBs) based on PVOH, such as Mowital®, are also used as temporary binders in ceramic and foundry products and a variety of other laminated products (e.g., printed circuit boards and multilayer ceramic capacitors [MLCCs]), as well as films for laminated safety glass. Since PVB contains only carbon, hydrogen and oxygen, it can be disposed of in an environmentally friendly way. Under controlled conditions, the product combusts into carbon dioxide and water without leaving any residue. As a binding agent, PVB provides controlled shrinkage of high-performance ceramic parts during sintering.

Call (212) 986-2230, ext.140, e-mail heiko_mack@kuraray-am.com or visit www.kuraray-am.com.

Bentonite

Laguna Clay Co.

Bentonite improves plasticity in additions of 2.5%, compared to the 10% often required with any ball clay addition.

Bentonite also helps overcome settling problems in glazes, and its stickiness can improve a clay body's workability. This company's 325-mesh bentonite is a standard glaze and clay additive. Bentolite L-10, its whitest bentonite, is designed for use in clay bodies, especially in conjunction with Macaloid in porcelains. HPM-20 is an ultra-fine, ground, air-purified bentonite recommended when a finer grade than 325 mesh is needed for glaze applications. Macaloid, which is similar to a very clean, white type of bentonite, is a suspension agent that increases the drying rate of water-suspended glazes, and it is also used as a plasticizer in fine porcelain. Vee Gum-T is a Macaloid bentonite suspension agent for glazes that is also used as a surface hardener. It is an extremely plastic, hydrous magnesium silicate used to give plasticity to non-plastic whiteware and refractory bodies. The company also supplies carboxymethyl cellulose (CMC) powder, an organic cellulose gum that functions as a thickener, binder and suspending agent in glazes, especially when combined with Vee Gum-T.

Call (800) 452-4862, e-mail info@lagunaclay.com or visit www.lagunaclay.com.

Lignin-Based Additives

LignoTech USA

Additive-A® lignin-based clay conditioners provide lubricating, binding and anti-scumming properties in a variety of applications. Depending on the specific body composition and plant configuration, the product can add strength, increase production rates, improve recovery and, in general, improve production conditions and profitability. Specialized Additive-A products can be used in clays where scumming is a problem. These products provide strength and lubricity benefits, and can also eliminate the need to add barium carbonate powder. Other lignin-based products-including Marasperse, Ultrazine and Borresperse-are used as binders and dispersants (deflocculants) in refractory and structural ceramic applications, as well as some ceramic coatings. As binders, they are designed to provide cost-effective enhancement of green strength to protect unfired pieces from the damage that can occur in machine-handling prior to firing. When used as dispersants, these products allow inorganic slurries to be maintained at high concentrations and low viscosities for extended periods of time.

Call (908) 429-6660, e-mail ceramics@borregaard.com or visit www.lignotech.com.

Wollastonite

NYCO Minerals Inc.

This company has developed new wollastonite grades that take advantage of this material's unique crystal acicularity to offer a non-toxic, low-cost reinforcing mineral fiber for fine ceramics, whiteware and structural clay bodies. For fine ceramics, NYGLOS® grades range from 2-12 µm in diameter and double as a green strength reinforcement for the fabrication of complex shapes (near-net or rapid prototypes) and a sintering accelerant (especially with zirconia and alumina ceramics). In whiteware bodies, 20-40 µm diameter products have been successfully added in major sanitaryware plants to increase first fired yields by up to 10%. Major advances in green strength and drying/casting rates are also achievable with less than a 5% addition. Additionally, a new acicular product, HARRP(tm), has been developed for structural clay products requiring improved green strength, crack resistance and dimensional stability over a long service life.

Call (403) 260-8111, e-mail info@nycominerals.com or visit www.nycominerals.com.

Editor's note: This report was compiled from information submitted by industry suppliers. All statements are manufacturers' claims, and Ceramic Industry does not endorse any of the products mentioned. Additional new product information can be found online at www.ceramicindustry.com, and in print issues of Ceramic Industry.