Characteristics, Applications, and Differences of Redispersible Latex Powder and Resin Adhesive Powder
Release Time:
2016-05-18
Source:
Characteristics, Applications, and Differences of Redispersible Latex Powder and Resin Adhesive Powder
In recent years, the market has seen the emergence of numerous resin-based adhesive powders—such as high-strength, water-resistant adhesive powders—at remarkably low prices, intended to replace traditional redispersible latex powders that are primarily formulated with VAE emulsions (vinyl acetate–ethylene copolymers) and produced via spray drying. So, resin-based adhesive powders and Redispersible Latex Powder What are the differences, and can resin latex powder replace redispersible latex powder? Below is a brief analysis of the differences between the two for your reference:
I. Redispersible Latex Powder
Currently, the most widely used redispersible latex powders worldwide include: vinyl acetate–ethylene copolymer latex powder (VAC/E), ethylene–vinyl chloride–vinyl laurate terpolymer latex powder (E/VC/VL), and vinyl acetate–ethylene–higher fatty acid vinyl ester terpolymer latex powder (VAC/E/VeoVa). These three types of redispersible latex powders dominate the global market, with vinyl acetate–ethylene copolymer latex powder (VAC/E) holding a leading position worldwide and epitomizing the technical characteristics of redispersible latex powders. From the perspective of technical experience in polymer applications for mortar modification, it remains the optimal technical solution:
1. It is one of the most widely used polymers in the world;
2. Possesses the most extensive application experience in the construction industry;
3. It can meet the rheological properties required of mortar (i.e., the desired workability);
4. It exhibits low volatile organic compound (VOC) emissions and low irritant gas generation compared with other monomeric polymeric resins;
5. Exhibits excellent UV resistance, good heat resistance, and long-term stability;
6. Exhibits high resistance to saponification;
7. Possesses the widest glass transition temperature (Tg) range;
8. Exhibits relatively excellent comprehensive adhesion, flexibility, and mechanical properties;
9. Possesses the longest-standing experience in chemical production processes for consistently producing high-quality products and maintaining storage stability;
10. Easily combines with the protective colloid (polyvinyl alcohol) to enhance performance.
II. Resin Adhesive Powder
Most “resin” adhesive powders on the market contain DBP, a chemical whose harmful effects have been well documented—it can impair male sexual function. Large quantities of such adhesive powders are often stockpiled in warehouses and laboratories, where they exhibit a certain degree of volatility. In Beijing’s markets, renowned for their abundant production of “adhesive powder,” a new trend has emerged: solvent-extracted “adhesive powder” marketed under a wide array of names, such as “high-strength water-resistant adhesive powder” and “resin adhesive powder.” Their typical characteristics are:
1. Poor dispersion: some feel damp, others feel flocculent (likely due to porous materials such as sepiolite); some of the white batches are slightly dry but still have a strong, unpleasant odor.
2. It has a very pungent odor.
3. Some have been colored; the colors currently available include white, yellow, gray, black, red, and others.
4. The dosage increase is minimal, with an addition of 5–12 kilograms per ton.
5. The early strength is astonishingly high—after only three days, when the cement hasn’t even developed any significant strength yet, it can already corrode and bond the insulation boards.
6. It is said that XPS boards do not require a bonding agent.
Based on the samples currently available, it can be concluded that the resin is a solvent-based type adsorbed onto a lightweight, porous material. However, the supplier deliberately avoids using the term “solvent” and instead refers to it as “adhesive powder.”
Disadvantages:
1. The weather resistance of the solvent is a major issue: under sunlight, it evaporates relatively quickly; even in the absence of direct sunlight, the bonding interface—due to its cavity construction—also degrades rather rapidly.
2. Aging resistance: solvents are not temperature-resistant, as everyone knows.
3. Since the bonding mechanism involves dissolving the interface of the insulation board, conversely, it also destroys that very interface. If this issue arises at a later stage, the consequences can be catastrophic.
4. There is no precedent for its application abroad; given the mature foundational chemical engineering expertise available internationally, it is inconceivable that this material would have gone unnoticed.
Summary:
Redispersible latex powder:
1. Redispersible latex powder is a water-soluble, redispersible powder composed of a copolymer of ethylene and vinyl acetate, with polyvinyl alcohol serving as the protective colloid.
2. VAE redispersible latex powder exhibits film-forming properties: a 50% aqueous solution forms an emulsion, and after being left on glass for 24 hours, it develops a plastic-like film.
3. The formed film exhibits a certain degree of flexibility and water resistance, meeting national standards.
4. Redispersible latex powder exhibits high performance: it boasts high bonding capacity, unique properties, and outstanding water resistance; it provides excellent bond strength and imparts superior alkali resistance to mortars. In addition to enhancing the mortar’s adhesion, flexural strength, workability, wear resistance, and ease of application, it also confers enhanced flexibility, particularly in crack-resistant mortars.
Resin adhesive powder:
1. Resin adhesive powder is a novel product that serves as a modifier for materials such as rubber, resins, polymeric polymers, and finely ground adhesive powders.
2. Resin adhesive powder exhibits typical durability and wear resistance, but its dispersibility is poor. Some samples feel flocculent (likely porous materials such as sepiolite), while others appear as a white powder (though they emit a pungent odor reminiscent of kerosene).
3. Some resin-based adhesive powders exhibit a certain degree of corrosivity toward the substrate, and their water resistance is also less than ideal. 4. Both the weather resistance and water resistance of resin-based adhesive powders are inferior to those of latex-based powders. In particular, weather resistance is a significant issue: under direct sunlight, these materials tend to volatilize relatively quickly; even in shaded conditions, the bonded interface—due to its hollow-structure construction—also degrades rather rapidly.
5. Resin adhesive powder lacks moldability and exhibits no flexibility; according to the testing standards for exterior wall external thermal insulation mortar, only the failure rate of polystyrene boards meets the requirements, while all other performance indicators fail to comply.
6. Resin adhesive powder is only suitable for bonding polystyrene boards and must not be used for bonding vitrified microbeads or fire-resistant boards.
This demonstrates that the exterior wall external thermal insulation industry must steadfastly promote the use of redispersible polymer powders, vigorously support policies for quality control of raw materials in this sector, and prioritize quality to ensure sustainable, long-term development.
