Synthetic Latex

What Synthetic Latex Is and Why It Remains a Critical Colloidal Material

Synthetic latex is a stable aqueous dispersion of polymer particles produced by emulsion polymerization of one or more monomers. Unlike rubber supplied in briquettes, latex retains the polymer as a colloidal system and enables the formation of thin elastic films without dissolving the polymer and without organic solvents. This determines its key role in dip-molding processes and as a binder for paints, adhesives, impregnants and coatings.

For procurement and process teams, synthetic latex matters primarily as a material with a tunable property set: the copolymer type determines elasticity, oil resistance and adhesion; solids content governs rheology and film thickness; pH and colloidal stability affect compatibility with fillers and pigments. Unlike natural rubber latex, synthetic latexes contain no allergy-causing proteins, making them preferable for medical articles and hygiene products.

The range of synthetic latexes covers styrene-butadiene, nitrile-butadiene, carboxylated, polyisoprene, polychloroprene and acrylic types. Each type occupies its own niche: styrene-butadiene latexes dominate in paper, paints and carpets; nitrile-butadiene latexes in oil-resistant gloves and industrial articles; carboxylated grades provide increased adhesion and stability.

Chemical Identification and Procurement Data

Identification of synthetic latex in specifications and customs documents relies on the copolymer type, trade name of the grade and the normative document.

• Chemical name: aqueous dispersion of a copolymer of butadiene and styrene (SBR), butadiene and acrylonitrile (NBR), carboxylated copolymer (XSBR, XNBR) and others.
• Synonyms: synthetic latex, SBR latex, NBR latex, styrene-butadiene latex, nitrile-butadiene latex, carboxylated latex.
• CAS number: 9003-55-8 for styrene-butadiene latex; 9003-18-3 for nitrile-butadiene latex.
• HS code: 4002110000 for styrene-butadiene rubber latex; 4002510000 for nitrile-butadiene rubber latex.
• Commercial form: milky-white or slightly cream-colored liquid, in 200 L drums, 1000 L IBC containers, rail tank cars.

In the Russian regulatory system, GOST 10564-75 (SKS-65GP) and GOST 14053-78 (SKS-50GPS) apply to styrene-butadiene latexes. For specific grades and specialty types, technical specifications apply. The supplier confirms batch conformity to the applicable normative document and provides a certificate of quality with actual values for each indicator.

Physical and Chemical Parameters Relevant to Processing

The properties of latex as a colloidal system are determined by a set of parameters that must be controlled during incoming inspection and taken into account when developing formulations.

• Solids content: 40-52 percent for typical grades; high-concentration latexes reach 65-70 percent.
• pH: typically 8-11 depending on emulsifier and stabilizer type; for carboxylated latexes pH may be lower.
• Brookfield viscosity: 20 to 200 mPa·s for standard grades; depends on solids content and particle size.
• Particle size: 60-300 nm; a narrow particle size distribution ensures stability and film quality.
• Surface tension: 30-50 mN/m.
• Coagulum content: not more than 0.05-0.1 percent.
• Glass transition temperature (Tg): from minus 50 to plus 20 degrees Celsius depending on monomer ratio; for styrene-butadiene latexes with 30 percent styrene, Tg is typically about minus 40 degrees Celsius.
• Residual monomer: standardized for medical and hygiene grades.

For the processor, pH stability and colloidal stability are critical: deviations in these parameters can cause separation, coagulation and film formation on equipment. Viscosity and particle size determine latex behavior during dipping, spraying and application to a substrate.

Technical Grades and Supply Forms

The grade range of synthetic latexes is classified by copolymer type and intended use.

Styrene-Butadiene Latexes (SBR, SKS)

The largest-tonnage group. SKS-30Sh latex (tire grade) is used for tire cord impregnation and provides adhesion between rubber and textile. SKS-50GPS latex with a butadiene-to-styrene ratio of 50:50 is used in the production of latex table oilcloth, film materials and artificial leather. SKS-65GP latex with a high styrene content is used in the paper and board industry, as well as in adhesives.

Nitrile-Butadiene Latexes (NBR, BNKS)

Contain acrylonitrile, which imparts oil and gasoline resistance to films. Used for medical, examination and industrial gloves, oil-resistant articles, artificial leather and technical films. Carboxylated nitrile-butadiene latexes (XNBR) provide increased strength and adhesion.

Carboxylated Latexes (XSBR, XNBR)

Contain carboxyl groups that increase colloidal stability, adhesion to polar substrates and film strength. Used in paper coating, carpet backing, nonwovens, adhesives and cement-latex compositions.

Polyisoprene and Polychloroprene Latexes

Polyisoprene latex is close in properties to natural rubber and is used for medical gloves, condoms and dip-molded articles. Polychloroprene latex is used for oil-resistant and weather-resistant coatings, adhesives and gloves.

Supply forms: 200 L drums, 1000 L IBC containers, rail tank cars. Latex must be stored above zero and below 30 degrees Celsius, protected from direct sunlight.

Regulatory Framework for Incoming Inspection

• GOST 10564-75 - synthetic latex SKS-65GP. Specifications.
• GOST 14053-78 - synthetic latex SKS-50GPS. Specifications.
• GOST 11138-78 - styrene-butadiene latex SKS-30 ARKM-15.
• GOST 19809-74 - determination of pH of aqueous dispersions.
• GOST 27876-88 - determination of solids content.
• ASTM D1076 - standard test methods for synthetic latex.
• ISO 976 - determination of latex pH.
• ISO 124 - determination of solids content.

For imported batches, the specification is based on manufacturer standards and harmonized ASTM and ISO methods. The batch specification is confirmed by the manufacturer certificate of quality and the results of incoming laboratory control by the recipient.

Mechanism of Action and Functional Role

The functional value of latex is determined by the ability of polymer particles to form a continuous elastic film as water evaporates. This process, known as film formation, occurs through particle approach, deformation and mutual diffusion of polymer chains. The rate of film formation and film quality depend on the glass transition temperature of the polymer, particle size and the presence of coalescing agents.

In tire cord impregnating compositions, latex provides adhesion between textile and rubber by forming a film on the fibers and subsequently interacting with the rubber vulcanization system. In paper coatings, latex binds pigments and fibers, imparting strength, gloss and abrasion resistance to paper. In adhesive compositions, latex forms an adhesive layer that provides strong bonding of materials after drying.

Applications by Industry

Medical and Industrial Gloves

This is one of the largest directions. Nitrile-butadiene and polyisoprene latexes are used for examination, surgical and industrial gloves. Synthetic latexes contain no natural rubber proteins, reducing the risk of allergic reactions.

Paper and Board

Styrene-butadiene and carboxylated latexes are used for surface sizing, pigment coating and impregnation of paper and board. They improve strength, smoothness, gloss and moisture resistance.

Paints and Coatings

Latexes serve as binders in water-based paints, primers, anti-corrosion coatings and sealants. Carboxylated latexes provide stability and adhesion to various substrates.

Adhesives and Bonding Agents

Styrene-butadiene and nitrile-butadiene latexes are used in adhesives for leather, textiles, paper and packaging, as well as in cold-curing adhesive compositions.

Carpets and Nonwovens

Latex is used for impregnating and bonding fibers in carpets, nonwovens, geotextiles and artificial leather. Carboxylated latexes provide softness and fiber bond strength.

Construction and Cement Systems

Carboxylated styrene-butadiene latexes are used in cement-latex mortars, putties, waterproofing membranes and repair compounds, improving adhesion and elasticity.

Comparison with Alternative Binders and Dispersions

Compared with natural latex, synthetic latexes offer more consistent quality, independence from crop yields and no allergenic proteins. Compared with organic polymer solutions, latexes eliminate solvents, reducing fire hazard and volatile organic compound emissions.

Compared with acrylic dispersions, styrene-butadiene latexes provide higher elasticity and low-temperature flexibility but are inferior in weathering resistance and transparency. Nitrile-butadiene latexes surpass acrylics in oil resistance but are inferior in UV resistance. The choice of latex type is determined by requirements for elasticity, adhesion, oil resistance and cost of the final composition.

Supplier Selection Criteria and Specification Development

The specification for synthetic latex must include the copolymer type, solids content, pH, viscosity, particle size, coagulum and residual monomer content, and intended use (gloves, paper, paint, adhesive). For medical grades, biocompatibility and the absence of allergenic proteins are additionally important.

The supplier confirms batch-to-batch consistency, colloidal stability during transport and storage, and readiness to support import procedures. When choosing between grades from different regions, not only price but also property reproducibility, packaging availability and delivery times are taken into account.

Typical Handling and Processing Errors

• Freezing of latex. At temperatures below zero, the colloidal system is irreversibly destroyed, leading to coagulation. Transport and storage must be carried out at positive temperatures.
• Overheating and prolonged light exposure. UV radiation and high temperature accelerate polymer aging and reduce latex stability.
• Incompatibility with fillers and pigments. Addition of electrolytes or oppositely charged additives can cause coagulation. Preliminary compatibility testing is required.
• pH deviation during storage. A decrease in pH below the optimum leads to loss of colloidal stability. pH control before use is recommended.
• Use of contaminated containers. Residues of acids, salts or solvents in containers cause latex coagulation.
• Expecting full equivalence of grades from different manufacturers. Even with matching certificate parameters, particle morphology and molecular weight distribution may differ; confirmation in the target formulation is required.

Quality Control and Laboratory Methods

Incoming inspection of synthetic latex includes determination of solids content, pH, viscosity, particle size and coagulum content. For medical grades, residual monomer and the absence of allergenic proteins are additionally controlled. Sampling is performed by standardized methods, and the combined sample is analyzed in the plant laboratory. To confirm suitability for a specific process, a control run is recommended.

Storage and Transportation Conditions

Synthetic latex is not classified as a hazardous good but requires temperature control. Storage is carried out in closed warehouses at temperatures from plus 5 to plus 30 degrees Celsius, protected from direct sunlight and atmospheric precipitation. The shelf life is typically 6-12 months from the date of manufacture depending on latex type. Transportation is by rail, road and sea in sealed packaging, protected from freezing.

Finding Analogues and Interchangeability

When replacing latex, a grade with a similar copolymer type, solids content, pH and particle size is selected. Direct substitution of one manufacturer grade with another is possible but requires confirmation of colloidal stability and film properties in the target formulation. Replacement of styrene-butadiene latex with acrylic or polyisoprene is possible only in applications where the specific properties of the original type are not required. The decision is based on laboratory testing and control runs.

Supply Routes: Russia, China and Other Regions

Domestic supply of synthetic latexes is provided by petrochemical complexes with appropriate capacities. Products are supplied to the domestic market and for export.

Chinese producers of synthetic latexes have large capacities and a wide grade range, including carboxylated and nitrile types. Supplies are delivered by sea with subsequent transfer to rail or road transport. Other global producers are located in Japan, Korea, Europe and Southeast Asia. Suppliers from these regions are engaged when required, taking into account logistical and regulatory factors.

Logistics and Customs Clearance

Transportation is carried out in drums, IBC containers and rail tank cars. Customs clearance includes HS code classification, preparation of a safety data sheet and conformity declaration. The portal provides customs broker services and supports all clearance stages.

Risk Factors and Safety Measures

The main risks are associated with freezing, overheating, contamination and loss of colloidal stability. Maintaining the temperature regime, packaging integrity and pH control minimize these risks.

FAQ: Common Questions from Procurement and Process Specialists

How does synthetic latex differ from rubber in briquettes

Latex is an aqueous dispersion of polymer particles, whereas rubber in briquettes is a dry polymer. Latex allows film formation without dissolving the polymer and is used in dipping, impregnation and coating processes; rubber is processed into rubber compounds on mixing equipment.

Which latex grade is suitable for medical gloves

Nitrile-butadiene (NBR), polyisoprene and carboxylated nitrile (XNBR) latexes are used for medical gloves. They contain no allergenic natural rubber proteins and provide the required elasticity and strength.

Why should latex not be frozen

Freezing causes water in the dispersion to crystallize, leading to irreversible coagulation of polymer particles. After thawing, the latex loses its properties and cannot be used to produce a quality film.

What is the shelf life of synthetic latex

The shelf life is typically 6-12 months from the date of manufacture under proper temperature conditions and protection from direct sunlight. After this period, the latex is subject to incoming inspection.

What documents are required for latex import

Import requires a contract, invoice, packing list, manufacturer certificate of quality, safety data sheet, transport documents and a declaration of conformity (if required). The portal organizes the preparation of the document set and interaction with the customs broker.

Conclusion

Synthetic latex remains a demanded material for gloves, paper, paints, adhesives and carpet products due to its ability to form elastic films without solvents and its quality consistency compared to natural latex. The choice of latex type is determined by requirements for elasticity, oil resistance, adhesion and colloidal stability. For procurement teams, the practical task reduces to confirming batch conformity to the normative document, controlling solids content, pH and viscosity, and organizing supplies with observance of the temperature regime.

Contact Us

For procurement inquiries and supply chain organization, contact the portal team at info@apptrade.ru.