Four "adhesive formulations" commonly used in flexible packaging
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Commonly used composite adhesives for flexible packaging: one is aluminum foil composite glue, the other is aluminum-plastic composite glue, the third is water-based paper-plastic composite glue, and the fourth is bismuth-soluble poly-glycol glue. In order to further explain the above adhesive, the application, formulation, composition adjustment and preparation method are briefly introduced.
1. Formulation design of environmentally friendly aluminum foil composite adhesive
(VAC) vinyl acetate vinegar 23.57%
(BA) butyl acrylate 4.71%
(AA)Acrylic 0.34%
(PVA1799) polyvinyl alcohol 4.71%
(APS) ammonium persulfate 0.12%
(emulsifier OP) polyethylene glycol octyl phenyl ether 0.79%
(SDS) sodium lauryl sulfate 0.4%
(DBP) dibutyl phthalate 2.36%
(TDP) Tributyl phosphate 0.16%
Water 62.84%
Component adjustment
Monomer composition: In the composition of the product, acrylic acid and butyl ester account for about 15% of the total amount of comonomer, so that the adhesiveness of the emulsion and the softness of the film are improved. The introduction of acrylic acid can improve the stability of emulsion polymerization, improve the adhesion of the emulsion and the adhesion to the metal. However, if the amount is too large, the water resistance of the film decreases, and the decomposition rate of the initiator is too fast, which hinders the copolymerization reaction. Normally, the amount of acrylic acid added is generally controlled at about 1.5 of the total amount of monomers.
Effect of polyvinyl alcohol: As a protective colloid of copolymer emulsion, the degree of polymerization, solubility and dosage of the material have an effect on the viscosity of the emulsion. The use of 17-99 polyvinyl alcohol increases the viscosity of the emulsion with the increase of its dosage, usually accounting for 5.5% of the total amount, and the viscosity is suitable.
Polyethylene glycol octyl phenyl ether is one kind of emulsifier, and the amount thereof has a great influence on the particle size and stability of the copolymer emulsion. Therefore, sodium lauryl sulfate is often used as a composite emulsifier. Generally, the ratio of the former to the latter is 1:2. However, as the amount increases, the stability of the emulsion will increase, but the fluidity and bond strength of the composite will decrease. After a large number of experiments and use, when the amount of the two accounts for about 5% of the total amount of the copolymer, there is no agglomeration and good stability.
The amount of ammonium persulfate has a certain influence on the conversion rate of the unit and the viscosity of the emulsion. In the production, the amount of the polymerization is incomplete, the solid content is not up to the formula design requirement, the composite adhesive viscosity is low, and the smell is large; Causes explosion, and the polymerization reflects difficulty in control.
Second, the formula design of aluminum-plastic composite adhesive
Vinyl chloride vinyl acetate vinegar (1) 4.6%
104 resin (2) 18.3%
C9 resin (3) 7.5%
Coupling agent TM-P(4) O.6%
Mixed solvent (5) 79%
Total 100%
Component adjustment
The effect of the amount of aluminum-plastic composite rubber on the bonding performance: the formulation is mainly linear 2 resin, 1 is an auxiliary resin, and is dissolved and mixed with a suitable 5 . As the amount of 2 increases, the adhesion will also increase, but when a certain amount is reached, the tendency of the adhesive force will decrease, the brightness of the film will also decrease, and the viscosity will also increase to affect the sizing. The addition of 3 is to improve the holding force. If the dosage is too large, the viscosity will decrease, the cohesion will rise, and the surface tension will become smaller. Wrinkles are easily generated during sizing, resulting in uneven compounding.
The effect of the amount on the heat seal strength: The most ideal coating film state is to form a molecular layer on the surface of the ink aluminum foil to ensure that the ink molecules can be bonded to the aluminum foil and the aluminum foil. Therefore, the amount of 4 has an influence on the bonding strength. Usually, the addition of a coupling agent can significantly improve the performance of the ink, the adhesive on the aluminum foil and the plastic film, and improve the bonding strength. On the other hand, when a coupling agent is used, the corresponding coupling agent should be selected in consideration of various ink colors.
The higher the thickness of the ink film of the ink, the lower the strength of the bond. This is because the ink and the composite adhesive have poor interpenetism, so that the ink and the composite adhesive exhibit different wet affinity to the aluminum foil, resulting in low composite bonding strength.
Third, water-based paper-plastic composite adhesive formula design
Liquid acrylic resin 70%
Vinyl acetate 2O%
Waterborne Rosin Emulsion 4.5%
Styrene emulsion 4.3%
Coupling agent 1%
XH-24 silicone oil 0.2%
The effect of pre-emulsification on the mixing reaction is that the commercially available liquid acrylic resin is relatively stable in the emulsion polymerization, but the time for the secondary emulsion aggregation of water, each emulsion and the acrylic resin is significantly shortened.
The effect of tackifying resin on the properties of the composite rubber: styrene resin is usually the most used. In the adhesive strength around the initial adhesion and adhesion, especially in the direction of peel strength, most of the homemade rosin is used as a tackifier for the composite rubber system, and the cost is low.
Fourth, alcohol soluble polyurethane composite adhesive formula design
Tomley TOMMORROWPUR1010 30%~35%
25% aldehyde ketone or polyvinyl butyral 5%~10%
TU~310 or epoxy resin 1%~3%
Additives 3%~4%
Mixed solvent (ethyl acetate, isopropanol, n-propanol) 50%~60%
Total 100%
Component adjustment
We know that the alcohol-soluble polyurethane composite rubber is composed of a polyisocyanate and a polymer-modified isocyanolic acid, an organic solvent, a modified silane coupling agent and the like. Since the molecular chain contains isocyano and carbamate, it exhibits high activity. High adhesion to a variety of flexible packaging substrates. The polymer can form hydrogen bonds between the macromolecules, has high strength, is resistant to solvents, and is resistant to abrasion. Its shortcomings are poor acid resistance, water resistance and aging resistance.
Characteristics of Alcohol Polyurethane Composite Adhesive
The main feature of PUR1O1O series products is benzene-free and ketone-free, environmentally friendly. The product itself does not contain benzene and ketone solvents, and has good alcohol solubility. It can be dissolved and diluted by using an alcohol solvent during lamination or during the manufacture and use of the ink. Therefore, it can be used as a binder for benzene-free (ketone-free) inks, to produce alcohol-soluble surface printing or printing inks, and to be used for packaging of foods and medicines such as food and medicine.
Typical use of the product
TOM0RR0W PUR 1O1O series products have good adhesion to a variety of films, including PP, PE, PET, nylon, PVC, PVDC, aluminum foil and various aluminized films, with alcohol-soluble aldehydes and ketones and nitrocellulose. The auxiliary resin such as a cellulose resin has good compatibility, and is soluble in various solvents and mixed solvents such as alcohols, esters, ketones, and hydroxyls, and has good dispersibility. Good membranous gloss, high transparency and strong resistance to media.
TOMORROW PUR 1O1O series products are excellent connecting materials for making alcohol-soluble printing inks. They are suitable for compounding adhesives, composite inks, alcohol-soluble inks, transparent inks, PET and NY special inks. The inks can be applied to flexo and concave. Printing and varnishing and other printing types are used, and the printing suitability is excellent, and the light printing effect is particularly excellent. The disadvantage is that it is poorly compatible with other types of polyurethane resins and can only be used alone as a special resin for alcohol-soluble inks.