Adhesives

Adhesives – Hot Melt & Water-based

        Hot melt adhesives are 100% solid adhesives that are heated to temperatures above their melting point and applied to at least one substrate in the molten state. These adhesives can be very rigid materials or soft "tacky" materials depending on the ingredients used which are in turn dictated by the end use of the adhesive.

       Hot melts are well established in most of the adhesive markets we serve, including packaging, converting, bookbinding, non-woven, footwear, and others, due primarily to the advantage of fast processing. Unlike water-based or solvent-based adhesives, hot melt adhesives do not require drying. Hot melts set up as quickly as they can cool down to their solidification point. This fast solidification is ideal for use on highly automated manufacturing lines that require rapid bond formation.

        Water-based adhesives are made up of materials or compounds that can be dissolved or dispersed in water. These adhesives generally develop a bond by losing water through evaporation or penetration into the substrates. At least one substrate must be absorbent or porous in order to form a strong bond.

Water-based adhesives come in a variety of chemistries and compositions, and can be categorized as either natural or synthetic polymers. Following is a breakdown of water-based adhesives by composition

Solvent based products are noted for their fast bond strength development, versatile adhesion to a wide variety of substrates, good heat resistance, as well their tolerance of a wide range of production conditions, including low temperatures or high humidity. Solvent based contact adhesives offer excellent “auto adhesion” which results in an instant bond, thus allowing assembled components to undergo downstream processing without clamping or fixturing

Our line of packaging adhesives, a new breakthrough in hot melt technology, are literally raising adhesive standards to a higher level. From case and carton sealing to tray forming and more, multi-purpose  packaging adhesives are proving their value in a wide range of packaging applications. Very simply, adhesives provide superior performance at the lowest overall adhesive cost of any hot melt on the market today.

Substantial savings result from mileage improvements made possible because of the adhesive's lower density and aggressive bonding characteristics--factors that help packagers achieve similar or better bonding performance using less adhesive. Plus, our hot melts produce absolutely no gel or char, even after up to 500 hours in the melting pot. Their amazing stability not only contributes to better mileage, it also eliminates clogged nozzles and other costly sources of maintenance and equipment downtime. The most technologically advanced adhesives available today, packaging hot melts offer a unique combination of value-added features that bring higher total value to your entire packaging line.

Hot Melt Composition Types

EVA Hot Melts
EVA based adhesives are very versatile adhesives that can be formulated for a wide variety of applications. The type and amount of wax and resin used with the EVA copolymer can control the set time and the residual tack of the adhesive. In some instances, filler may be added to EVA adhesives for special applications. EVA adhesives are widely used in the following industries:


 Bookbinding
 
 Case and Carton Sealing
 
 General Packaging
 
 Appliance
 
 Doors and Millwork
 
 Furniture
 
 Multi-wall and Specialty Bag
 

Polyethylene Hot Melts
Polyethylene adhesives are good, general purpose adhesives. They perform well in moderate temperature ranges and are well suited for porous substrates where flexibility is not required. Polyethylene adhesives have excellent pot life stability, as they are not prone to charring. They also exhibit good resistance to acid, grease, and other oily compounds. PE hot melts are commonly used in the following industries:

 Multi-wall and Specialty Bag
 
 Case and Carton Sealing
 
 General Packaging
 
 Appliance

 Doors and Millwork
 
 Furniture
 

APAO Hot Melts
APAO's are often used when a low cost adhesive with good acid or fuel resistance and moderate heat resistance is needed. These non-crystalline adhesives are soft, tacky, and flexible. This gives them longer open times and good adhesion. APAO's are used in the following industries:

 Appliance
 
 Doors and Millwork
 
 Furniture
 
 Case and Carton Sealing
 
 General Packaging
 
 Diaper
 
 Feminine Hygiene
 
 Dress Shoes
 
 Athletic Shoes
 

Block Copolymer Hot Melts
Block copolymer based hot melt adhesives (also known as styrene copolymer adhesives and rubber based adhesives) are best known for their low temperature flexibility combined with high heat resistance. Most are used for pressure sensitive applications where the substrates can be mated after the adhesive has cooled. However, they are also used in adhesives and sealants that lose their tack when cooled so the substrates must be mated while the adhesive is hot. Industries supplying block copolymer adhesives are:

 Bookbinding
 
 Diaper
 
 Feminine Hygiene
 
 Appliance
 
 Doors and Millwork
 
 Furniture
 
 Case and Carton Sealing
 
 General Packaging
 
 Dress Shoes
 
 Athletic Shoes
 

Unique Polymer for Hot Melts
This unique polymer provides our hot melt adhesives with superior bonding performance at a wider service-temperature range compared to traditional EVA hot melt adhesives. They also have a very light color and are clear and odorless. These adhesives have excellent thermal stability that has changed the industry norm in packaging. In addition, our hot melt products have excellent machining characteristics required for high-speed lines. The low density and the excellent adhesion of these products results in the reduction of adhesive consumption for our customers. Our customers enjoy the reduced maintenance costs and reduced downtime that results from the excellent thermal stability which includes viscosity stable products that are char-free. They are commonly used in the following industries:

 Case and Carton Sealing
 
 General Packaging
 
 Bookbinding
 
 Multi-wall and Specialty Bag
 

Polyamide Hot Melts
Polyamides are high performance hot melts that are used when bonds need to resist high temperatures (up to 350°F) and fuels or solvents. They are also among the strongest hot melt adhesives. These can be formulated to be soft and tacky or hard and rigid depending on the polymer and the resin used. Polyamides are used in the following industries:

 Appliance
 
 Doors and Millwork
 
 Furniture
 
 Dress Shoes
 
 Athletic Shoes
 
Water-Based Composition/Application Types

Polyvinyl Acetates
Polyvinyl acetate (PVAc) is a synthetic polymer and a member of the vinyl ester family. PVAc emulsion adhesives first gained market share by replacing hide glues in the 1940’s. Today, vinyl acetate adhesives are the most widely used adhesives on the market, but vinyl acetate emulsions are also heavily used in paints, textile sizing and non woven binders. Vinyl acetate emulsion adhesives can be broadly classified as homopolymer or copolymer. Each of these two types can be further classified as self-cross linking or non-cross linking.

Homopolymer Emulsion (PVA)
PVAc homopolymers were the first polyvinyl acetate emulsions developed. These polymers are hard and brittle with high molecular weight, high tensile strength and rapid speed of set. Today these homopolymers are still the “workhorses” of the industry due to their excellent adhesion to a wide variety of “polar” substrates, particularly cellulosic-based substrates such as paper and wood.

PVA adhesives have the following characteristics:

 Fast speed of set
 
 High strength
 
 Excellent adhesion to cellulosic substrates, ceramics, concrete, and glass
 
 High molecular weight
 
 Cost effective
 

Copolymer emulsion (VAE, VAA)
Compared to PVAc homopolymers, vinyl acetate copolymer emulsions offer the advantage of being able to bond difficult-to-bond substrates such as plastic films, coated papers, and metal surfaces. Vinyl acetate copolymer emulsions are internally flexibilized with a comonomer such as ethylene (VAE) or an acrylate (VAA). The increased polymer flexibility provides for increased polymer mobility and, therefore, better adhesion.

Applications for PVAc copolymers include:

 Textiles
 
 Construction
 
 Packaging
 
 Graphic Arts
 

Acrylics: Polymers & Copolymers
Acrylics are available as emulsions and dispersions as well as liquids containing 100% polymer. Acrylic emulsions are often used as a multipurpose adhesive. Dispersions provide an excellent paper-to-paper bond and are used in many laminating processes. A wide variety of acrylic and methacrylic monomers are available for manufacturing specific acrylic adhesives.

Acrylic based water-base adhesives are usually used in PSA applications. The heat seal coatings and flame spread resistance of acrylics is very good for PSA’s and are used in many UL applications. Most acrylics used in the textile industry are crosslinkable giving the final product weather and aging resistance as well as resistance to water, laundry detergents and solvents. They are FDA approved and are used in some edible oils and milk filters. Some of the largest structural bonding applications for acrylics include medical devices, electrical components, flexible ducts, window seals, and various home uses. They are also used on some private label diapers and other sanitary products.

Polyurethane Dispersions
Polyurethane is a synthetic polymer derived from isocyanate reactions. Environmentally friendly water-based polyurethane adhesive was developed in the late 1960’s. Polyurethanes are polymerized in water to produce a thermoplastic polyurethane emulsion. It then becomes thermoplastic and crosslinkable. Polyurethane dispersions are used in some of the most demanding applications because of their weatherability and resistance to plasticizers and solvents.

Generally, water-based polyurethane dispersions can be used in most of the same applications in which solvent-based polyurethane is used. Here are the major markets using polyurethane dispersions.

 Textiles-cloth fibers, backing coats, foam backed carpets, carpet cushioning
 
 Construction-windows, cabinet doors, furniture, glass fibers, paint applicators
 
 Automotive- plastic to glass
 
 Packaging-film to film, film to foil
 
Polychloroprene Adhesives
Polychloroprene, developed in the 1930’s as a substitute for natural rubber, is an extremely versatile synthetic elastomer that offers a unique combination of adhesive properties. Polychloroprene-based adhesives provide outstanding toughness, chemical resistance, weathering resistance, heat resistance, oil and chemical resistance, as well as very rapid bond strength development. In contact adhesive applications, they develop an “instant bond” which allows assembled components to be immediately processed without clamping or fixturing.

Typical applications for polychloroprene-based adhesives include:

 Footwear construction
 
 Lamination of furniture, kitchen cabinets and countertops, interior and exterior panels
 
 Automotive trim attachment
 
 Aluminum foil laminates for food packaging and HVAC
 

Casein
Casein is a natural polymer from skim milk proteins used in some water-based adhesives. It represents a small but important percentage of all natural polymers used in water-based adhesives. The casein formulations are highly soluble in alkaline and water, they thus wash very cleanly off of the glass containers. Casein can be cross-linked to give excellent water resistance which can be required when the glass containers are filled with a product that is chilled by means of soaking in ice-water. This cross-linking does not interfere with the casein ability to be washed off cleanly in alkaline water.

Casein - Common Applications
Casein is now used as:


 An adhesive in construction for wood working applications
 
 Packaging industries for breweries, wineries and packagers where refrigerated products are packaged
 
 A binder in paints
 
 An additive in other adhesives
 

Dextrine/Starch-Based Adhesives
Starch-based adhesives are made from natural polymers derived from roots, tubers and seeds of higher plants such as maize, potatoes, wheat, rice and tapioca. A starch-based adhesive is either cold or warm water-soluble depending on the application specifications. Starch granules are slurred in water. The mixture is heated until the granules burst. The granules absorb water and swell increasing in viscosity forming the paste or adhesive. The starch source depends on performance, machining and economics.

There are two types of starches borated and unborated.

 Is an ancient adhesive
 
 Became widely used during the industrial revolution
 

Dextrin is a type of dry roasted starch. A wide range of gums and pastes can be developed by controlling acidity, moisture content, and roasting temperature, varying levels of solubility and viscosity can be produced:

Dextrine/Starch-Based Adhesives Common Applications
Common applications for dextrine/starch-based systems include:


 Corrugated board
 
 Paper products
 
 Lamination applications
 
 Tube winding
 
 Labeling and envelopes
 
 Bookbinding
 

Natural Rubber Latex
Natural rubber latex is a water-based adhesive in which rubber particles are protected or stabilized by proteins and fatty acid soaps. Natural rubber comes from the sap of the Hevea Brasiliensis tree, collected at 35% solids. The formulation with natural latex will vary depending on the final application of the adhesive.

 First used in South and Central America
 
 Today, most comes from the Far East
 

Natural Latex Applications

 Graphic arts
 
 Engineered Systems
 
 Packaging
 
 Converting