Anruijie
Beijing organic chemical plant
VAE emulsion, namely vinyl acetate-ethylene poly emulsion, is an excellent adhesive. VAE emulsion is nontoxic, odorless and moderately priced, and has excellent adhesion effect on various surfaces made of different materials. Therefore, this adhesive has a wide range of applications in many fields.
VAE emulsion is a kind of water dispersion system, which avoids the influence of solvents on the environment and potential safety hazards. Ethylene endows polymers with flexibility, which is permanent and unaffected by environment and climate. VAE emulsion can not only be used as an excellent adhesive for bonding paper products, wood, plastics and synthetic cloth. But also can be easily mixed with various components such as thickener, surfactant, PH regulator, plasticizer, solvent, preservative and filler to make various special adhesives.
1, adding thickener
Water-soluble polymer thickener can increase the viscosity of continuous phase between dispersed polymer particles, thus increasing the viscosity of VAE emulsion. Sodium polyacrylate is an effective thickener for VAE emulsion. When the amount of thickener is below 1%, it has little effect on peel strength. When 7% was added, the bond strength decreased obviously.
Carboxyl styrene-butadiene emulsion can significantly increase the viscosity of VAE emulsion and improve the adhesive strength to PVC, PP and other substrates. However, attention should be paid to controlling the addition amount to prevent the viscosity from being too high.
Step 2 add surfactant
Surfactants such as alkyl polyoxyethylene ether and MS- 1 were added to VAE emulsion to improve the wettability of hard-to-wet surfaces (such as PVC films). The effective concentration of surfactant is 0. 1 ~ 1.0% per 100 parts of emulsion.
Adhesives made from VAE emulsion usually do not need to add defoamers. If there is foam, add 0. 1 ~ 0.2% defoamer 70 10 or F69 1.
3. Add PH regulator
VAE emulsion is generally stable in the range of pH 3.0 ~ 8.5. If the PH value of the mixture containing VAE emulsion is adjusted below 3.0, the synergistic viscosity will be too high, and it will hydrolyze faster in wet state, thus making the PH value lower and lower. When VAE emulsion is mixed with a dispersion system with completely different PH values (such as PH 9.0), the PH value of VAE emulsion should be adjusted to above 7 with alkaline substances. Minimize the influence caused by different PH values. Ammonia and sodium hydroxide are commonly used PH regulators in VAE emulsion.
4. Adding plasticizer and solvent
Adding plasticizer can reduce the formulation cost, because higher synergistic viscosity can be obtained. This thickening allows the viscosity to be adjusted to the required viscosity with water, thereby reducing the viscosity. Adding plasticizer and solvent can also improve the performance of the substrate which is difficult to bond in construction. Figure 1 shows that several plasticizers have been added: dibutyl phthalate, butylbenzene phthalate, dipropylene glycol phthalate and dioctyl phthalate, with the concentration of 15%, for thickening BJ-705.
Solvents compatible with VAE emulsion include 3- methoxybutyl acetate, butyl acetate, isobutyl acetate, isophorone, toluene, xylene, methyl isobutyl ketone, methanol, Texaco alcohol ester, etc. Adding solvent can not only affect the viscosity of emulsion, but also wet the surface of the adherend and improve the adhesion to the surface of the adherend. For example, adding 1 ~ 10 toluene to every hundred parts of emulsion is helpful to wet the oily surface like a plasticized PVC film, and even if a small amount of plasticizer oozes from the surface of this PVC film, it will make adhesion difficult. Therefore, the addition of solvent can promote the adhesion of this surface.
Table 1 lists the typical adhesive strength values of VAE emulsion modified by adding 10% dibutyl phthalate.
Table 1 peel strength of laminated adhesive of plasticized VAE emulsion in air drying
Adding plasticizer can improve the adhesive strength of VAE emulsion to polyester film and K-type cellophane. In this case, the increased adhesive strength of dibutyl phthalate is greater than the decreased adhesive strength.
Adding 15% ~ 25% isocyanate adhesion promoter to BJ-705 can usually improve the adhesion to polyester. Because this adhesive is crosslinked on the surface of "polyester film". This mechanism is the same as adding plasticizer. In both cases of adding plasticizer and isocyanate, polar substances are added to VAE emulsion to improve the adhesion to polar matrix. Adding plasticizer into nonpolar matrix can not only improve the bonding strength, but also reduce the bonding strength.
Step 5 add filler
In adhesives based on VAE emulsion, low-cost fillers such as clay and calcium carbonate can be added as fillers or fillers. Adding dry filler can obviously increase the viscosity of emulsion. If the filler is first dispersed with water, a large amount of filler can be added without making the operable viscosity too high. BJ-707 can accept more fillers than other varieties.
6, wet strength additives
Generally speaking, the water resistance of VAE emulsion is satisfactory. When improvement is needed, dialdehyde, water-soluble urea-formaldehyde resin (UF), melamine resin (MF) or phenolic resin can be added. Excellent water resistance can be obtained by heating and curing.
The application of VAE emulsion is mainly manifested in the following aspects:
1. Adhesive for surface bonding
Compared with vinyl acetate homopolymer emulsion, VAE emulsion and adhesive based on VAE emulsion have better adhesion to difficult-to-adhere composites. In the furniture industry, VAE emulsion can be used to bond PVC decorative film with laminated board, particleboard, hard fiberboard or fiberboard; Bonding of refractory veneer to laminated board, particleboard, hard fiberboard or fiberboard; Similar to the bonding of wood (such as beech and Fraxinus mandshurica). ) veneer with particleboard, cardboard or fiberboard. In recent years, with the rapid development of China's packaging industry, paper-plastic composites have been widely used in commodity packaging. VAE emulsion can be made into excellent laminating adhesive by adding a small amount of additives, which can be used for laminating PVC film, oriented polypropylene film, polyolefin film, color printing paper, kraft paper and so on. VAE emulsion can be used as an adhesive between polystyrene foam board and concrete wall in wall insulation in construction industry. Due to the excellent adhesion of VAE emulsion to fibers, VAE emulsion is also widely used in the production and bonding of non-woven fabrics. VAE emulsion can be used as an adhesive for hard non-woven fabrics, carpet back glue, etc.
2. Adhesives for particle bonding
VAE emulsion can bind cheap fillers in a high proportion and maintain sufficient adhesion, thus balancing the cost well. VAE emulsion can be used as joint sealant between gypsum boards. In some special fields, VAE emulsion also has extraordinary performance: for example, the flame retardant antimony oxide, halide or phosphide is bonded to the substrate to increase the flame retardancy; Barite (barium sulfate) is bonded to the substrate to achieve the purpose of noise reduction. Based on VAE emulsion, high-grade interior and exterior wall coatings can be produced. The waterproof coating based on VAE emulsion has excellent weatherability, acid and alkali resistance and ultraviolet resistance, and can be used for waterproof treatment of special-shaped roofs, restoration of old roofs and construction of colored roofs, and also for waterproof painting of toilets. Adding VAE emulsion to cement can not only greatly improve the strength of cement, but also reduce the void after cement curing and prevent leakage. Therefore, VAE emulsion can be used for concrete repair and reservoir seepage control treatment, and can achieve excellent results. VAE emulsion is mixed with cement and used to bond ceramic tiles and wall tiles. The powerful hydraulic power of emulsion can prevent the water in cement mortar from losing too fast, and finally obtain excellent bonding strength and durability. In addition, VAE emulsion can also be used as a high-quality interface agent and widely used in buildings and road and bridge construction.
3, used for high-speed bonding
Continuous production requires fast and effective welding. BJ-705 and 706 are specially designed for high-speed welding. When the water in the emulsion adhesive is not only evaporated but also absorbed into the porous matrix, the bonding speed is very fast. "Fiber tearing and bonding" occurs before the last bit of water leaves the adhesive. BJ-705 can be used as seam adhesive for high-speed cigarettes, carton and rapid prototyping adhesive after proper adjustment.
4, used for disposable tableware and food packaging
According to the relevant regulations of FDA, VAE milk 705 and 707 are safe in the process of food production, manufacturing, packaging, transportation and storage, and belong to the exclusion inspection stipulated by FDA. These varieties of VAE emulsions can be used not only for the separation of adhesive from food, but also for the contact between adhesive and food. Therefore, VAE emulsion as an adhesive can be used in disposable tableware, paper cups and food packaging industries.
The purpose of the above VAE emulsion is only a general introduction to VAE emulsion. Because of the wide adaptability of VAE emulsion, users can develop VAE deep-processed varieties suitable for their own purposes according to actual needs.
As the first manufacturer of VAE emulsion in China, Beijing Organic Chemical Plant took the lead in introducing VAE emulsion production from the United States. At present, it has an annual production capacity of 60,000 tons of VAE emulsion, and is the largest VAE emulsion adhesive manufacturer in China. In recent years, while expanding production scale and improving product quality, we have continuously developed new varieties of VAE emulsion to meet the needs of users from all walks of life and repay the support and care of new and old users for Beijing Organic Chemical Plant for many years.