Polyvinyl acetate - a sign in every home
PVA adhesive( polyvinyl acetate) is a product obtained as a result of the polymerization of vinyl acetate with the participation of an initiator, as well as a protective colloid in an aqueous medium. In appearance it is a white viscous liquid without foreign inclusions and lumps. It is produced on an industrial scale and on industrial equipment.
In industry, this glue is prepared in a mortar mixer: first a polyvinyl acetate dispersion and a filler are loaded into the container, then the resulting mixture is thoroughly mixed for half an hour.
To check the consistency, use a wooden pestle: the correctly prepared adhesive passes the pestle no more than 25 mm. If the density of the glue is higher than normal, the solution is diluted with water and again thoroughly mixed.
There are following types:
- clerical - non-waterproof, non-frost-resistant;
- glue PVA for wallpaper( household), can withstand up to 6 cycles of thawing / freezing at temperatures down to -40 ° C;
- brand MB( universal), frost-resistance is 6 cycles at temperatures up to -20 ° C;
- grade M( super), frost-resistance - 6 cycles at -40 ° C;
- dispersion of PVA.
The advantages of the adhesive include:
- chemical resistance;
- rapid setting;
- faint odor;
- excellent physical properties in various temperature modes;
- mechanical stability;
- non-toxicity;
- fire and explosion safety.
The disadvantages of this material for a long time attributed a low water resistance, but at the moment, due to the use of various additives, increased water resistance of some species of this material.
Adhesive PVA - the breadth of application
In modern production, as well as in home use, everyone has heard at least once what a PVA glue, its application is very wide. This material is very often needed in the field of construction and repair work. It is used to glue wallpapers, add to the masonry solution for tiling, PVA glue primer allows you to prepare surfaces for finishing, it is also irreplaceable when gluing wood fiber and wood parts.
In the printing industry it is used for stitching book blocks and books. In the production of packaging material it is necessary for gluing cardboard, combined materials, multi-layer paper bags, cardboard drums and other.
In the pulp and paper industry, in order to improve the stiffness, color and resistance of the paper to various impurities, an emulsion of PVA glue is applied to its surface. This glue spread widely in the woodworking and furniture industries. Due to its properties, it does not affect the color of wood, which is important for maintaining its characteristics and aesthetic appearance.
In the textile industry, polyvinyl acetate is widely used to cover the back surface of carpets to impart elasticity, stiffness, and density to the product. In addition, it serves to fix carpet fibers. This material is also used for gluing the tissue itself.
Polyvinyl acetate also finds its application in the shoe, tanning, glass industry, in the manufacture of household chemicals, water-based paints, etc.
Preparation and use of PVA
adhesive Before using this adhesive, dust and contaminants must be removed from the work surfaces. Porous base is better to prime, the surface with old paint should be carefully sanded and degreased. Before use PVA is well mixed and applied in a thin layer on the glued parts, after which they are firmly pressed.
The shelf life of this material is 6 months from the date of manufacture. Open glue should be stored in a sealed container, at t + 10 ° C.At temperatures below zero, polyvinyl acetate is stored for no longer than 1 month.
For homemade analog PVA , the following ingredients are required:
- distilled water - 1 l;
- gelatin photographic - 5 g;
- glycerin - 4 g;
- wheat flour - 100 g;
- ethyl alcohol - 20 ml.
All these components can be purchased near the house, at the grocery store and pharmacy. The problem may become gelatin, because it is photographic. To prepare, you will need very little time and effort, especially if you prepare gelatin. Gelatine must be soaked in water for 24 hours.
When the time to soak gelatin has passed, turn on the water bath or build it from improvised means. All ingredients, except alcohol and glycerin, put into a container and cook on a water bath until the required consistency( thick sour cream) with constant stirring.
Now that everything has got the desired look, it's time for the remaining alcohols. After obtaining a stable mass without lumps, alcohol and glycerin are added to it. Properly mix them into a thick mass, this can not happen immediately. So, carefully mix, do not spare the time when it will be impossible to distinguish heterogeneities at all, you can finish. The glue is ready, for use you need to let it cool.