Finishing - Binders

What leather finishing binders are

Finishing binders are aqueous polyacrylate dispersions that form the film in leather finish: impregnation, base coat and, with modifiers, parts of the top. They decide softness, tack, adhesion, rub fastness and how the grain breaks. Dyna Glycols offers VENRES BINDER 10 (very soft, low tack), VENRES BINDER 20 (medium soft, low tack) and VENRES BINDER 76 (very soft, elastic, slightly tacky, finer particle impregnation).

A finish season is never the binder alone. Pigment, wax, protein, PU dispersion, feel modifiers and lacquer sit on top of the acrylic. The VENRES series is specified by film hardness and particle size so a finishing chemist can build shoe upper, upholstery and garment seasons, including combinations with PU for upgraded articles.

How Dyna Glycols manufactures leather finishing binders

Acrylic emulsions are produced to agreed solids, pH and film character. Binders 10 and 20 are typically 35–37% solids at pH 6.5–7.5. Binder 76 is a lower-solids (about 21–23%) anionic dispersion at a slightly higher pH, designed for fine impregnation and elastic films.

Batches are released as bluish-white translucent emulsions. Freeze–thaw and mechanical stability should be respected in transport and in the finishing shop; do not let finishing mixes stand with rust or hard-water shock if the TDS advises against it.

Typical grades in this range

Pick film softness first, then whether the duty is impregnation, base or a PU blend.

• VENRES BINDER 10 — very soft acrylic film, low tack; impregnation and top smoothness
• VENRES BINDER 20 — medium-soft acrylic film, low tack; shoe upper and upholstery seasons
• VENRES BINDER 76 — very soft, elastic, slightly tacky; fine-particle impregnation and suede pad/spray

Where leather finishing binders are used

Grain impregnation on buffed and full-grain leather: Binders 10 and 20 at about 150–200 g/m² by spray for grain tightening. Binder 76 is preferred when a fine grain break and deep impregnation are required, including some suede pad and spray work.

Shoe upper and upholstery base coats: pigment + VENRES 10 or 20 + water + modifiers, optionally blended with PU dispersion for adhesion and rub. Binder 20 is the medium-soft workhorse; Binder 10 when a softer, smoother touch is wanted.

Garment and upholstery that will be plated or embossed should be trialled with the wax emulsion (VENWAX S) in the same season. Binders supply the film; wax supplies slip, fill and plate.

How to specify leather finishing binders

State the article, whether the leather is full grain or corrected, the required film hardness, tack limit, and whether PU will be co-used. Share solids and pH of the current binder if a match is required.

For impregnation, mention particle-size need (Binder 76) versus a standard base-coat acrylic (10/20). For automotive or high rub, describe the rub-fastness test so a PU blend can be suggested.

Quality, documents and supply

Lots are released against appearance, pH and solids. SDS and COA follow verification. Film feel and tack should be checked on a glass plate or on crust at the finishing shop, not only by viscosity of the drum.

Store frost-free, typically six months. Mix before taking from the drum. Do not dilute with strongly hard water without checking coagulation.

Practical notes on leather finishing binders

Softness ranking in this range: Binder 76 (elastic, slightly tacky) and Binder 10 (very soft, low tack) versus Binder 20 (medium). Tack and softness are not the same: 76 can be tackier; 10 is positioned as very soft with low tack.

Impregnation binders must be finely divided. Binder 76 is the impregnation specialist; 10 and 20 also list grain-tightening impregnation but are equally at home in coats.

Combining with PU is the usual upgrade path for adhesion and wet rub. The acrylic still provides economy and fill; PU provides toughness. Ratio belongs in the customer’s season, not as a fixed factory blend unless requested.

Anionic binders can clash with strongly cationic toppings. If the crust was after-treated with a cationic dye fixer, check finish penetration before blaming the binder.

Spray solids, gun settings and drying temperature change the same binder’s appearance. A laboratory spray-out on the customer leather is the specification, not a viscosity number alone.

Dyna Glycols can sample 10, 20 and 76 as a set with VENOLAC lacquers and VENWAX S so a complete water-borne season can be built in one evaluation.

Ordering and evaluating leather finishing binders

Dyna Glycols supports leather finishing binders with laboratory samples, current SDS, TDS and COA from the Kandla SEZ manufacturing network. Tell us the intended application, the substrate, the required moles or molecular weight, and any limits on colour, odour, cloud point, hydroxyl value, pH or residual feedstock. A matching catalogue grade of leather finishing binders in the Leather Chemicals family can then be confirmed, or a custom batch can be planned on the ethoxylation, esterification or related plant.

When you evaluate leather finishing binders, send the competitor grade if one exists, the bath or emulsion conditions, and the tests your receiving laboratory will run. Pack options for leather finishing binders typically include drums, IBCs and bulk where the viscosity and melting point of the selected grade allow safe handling from the Leather Chemicals manufacturing line.

A first order of leather finishing binders is easier when the purchase specification lists identity tests, not only a local trade name. Hydroxyl value, saponification value, acid value, cloud point, pH, water, colour and appearance are the numbers the Kandla QA laboratory can lock. If your QC uses a different solvent or a different cloud-point electrolyte for leather finishing binders, write that method on the order so the COA speaks the same language.

Custom lots of leather finishing binders are quoted after the hydrophobe or acid/alcohol pair, the target analytical window, the annual volume and the pack. Pilot batches are available when a catalogue point in the Leather Chemicals range is close but not exact. Once a trial lot is approved, that TDS should be frozen so the tenth delivery of leather finishing binders matches the first approved drum.

Storage of leather finishing binders should follow the SDS: keep containers closed, protect hygroscopic grades from moisture, and warm high-melt or high-mole grades until uniform before sampling. FIFO rotation protects colour and odour. If a drum of leather finishing binders has frozen or separated in transit, homogenise it before charging a batch; do not decant only the liquid layer.

Application advice for leather finishing binders is given against the process you describe, not as a universal recipe. Share machine type, temperature, pH, electrolytes, fibre or hide type, and any ban on APEO, formaldehyde or food-contact lists. Dyna Glycols can then sample leather finishing binders alone or as a pair with a sister grade from the same Leather Chemicals family so compatibility is checked in one evaluation.