Thermoplastic adhesive

Goextrusions. In coextmsion, two or more thermoplastic resin melts are extruded simultaneously from the same die. Coextmsion permits an intimate layering in precisely the quantities required to function. Incompatible plastic materials are bonded with thermoplastic adhesive layers. Coextmded films may be made by extmsion-blowing or slot-casting of two, three, or more layers, eg, AB or ABA. Slot-casting is capable of combining up to 11 layers. 

The aerodynamic wheel cover of claim 4, wherein said thermoplastic adhesive comprise a pressure sensi- 55 tive adhesive. 

Monomeric MDI Pure 4,4 -MDI 2.0 Solid (MP = 37 C) Flexible prepolymers Liquid 1-K adhesive Thermoplastic adhesives Curing hot melts Solvent-borne adhesives... 

The market for polyurethane thermoplastic adhesives is small, but growing. TPU s are used to produce some solvent-borne adhesives and also are used in laminating textiles and films for labels and emblems. In addition, they are being considered as an alternative to solvent-borne adhesives in the shoe market. 

At the same time, natural adhesives such as casein glues, animal glue and polysaccharide gums have gradually been replaced by synthetic adhesives vinyl thermoplastic adhesives [poly(vinyl acetate)], adhesives obtained by reticulation in situ of two components (as epoxy resins), represent very important materials in this field. 

Dual-cure resins for wood composites. These resins (heat and EB irradiation systems) are based on urethane-acrylate thermoplastic adhesive demonstrate efficacy to bond wood. Eow amounfs of EB radiation were needed to produce a wood bond that survived shipping and that improved the composite modulus. The system demonstrated promise and a new direction for wood adhesives. 

Finally, a large variety of hot-melt or thermoplastic adhesives have been developed in recent years. These are solid at normal temperatures, but melt and flow if heated and re solidity when cooled. A wide range of melting points and bond strengths are available, depending on the requirements of the application. These adhesives are widely used in furniture and cabinet construction and have largely replaced the hide/bone glues formedy used in these applications. 

Heat-Sensitive or Thermoplastic Adhesive-Based Labels Activated by Heat. Two types are in use, instant tack and delayed tack. Both are based on synthetic resins. The former has to have heat and pressure applied to effect the transfer, but sets immediately after the source heat is removed. 

The choice of the thermoplastic adhesive and the solvent used to remove it from the coal are important for obtaining thin sections of coal which are only minimally affected by the preparation process. Some considerations in choosing the adhesive are listed below. (1) The adhesive should have reasonably good adhesion to the coal and to the glass slide. 

A thermoplastic adhesive that is applied in a molten state and forms a bond on cooling to a solid state. 

Ultrahigh-molecular-weight epoxy resins can be used directly as a thermoplastic adhesive. The hydroxyl groups and good wetting characteristics provide for good adhesion to many surfaces. These adhesives are prepared in film form by solvent casting or extrusion. 

The base polymer, of course, is a key ingredient in a high-temperature epoxy adhesive system. For an adhesive to withstand elevated temperatures, it must have a high melting or softening point and resistance to oxidation. Materials with a low melting point, such as many of the thermoplastic adhesives, may prove excellent adhesives at room temperature ... 

Some of the more interesting and innovative work has occurred in areas combining aspects of more than one chemistry type. For instance, moisture-curable thermoplastic adhesives have received much attention. Hot melt adhesives have been developed that contain active, moisture-curable isocyanate groups. The compositions provide rapid processing on assembly lines because a reasonable bond is formed as soon as the thermoplastic adhesive cools from the melt. However, bond strength and performance improve with time as the composition is slowly crosslinked to a thermoset by reaction of the isocyanates with atmospheric moisture.96,97... 

Thermoplastic Adhesives. The polymer adhesives described in the following sections are not used as extensively with wood as the thermosetting adhesives discussed earlier. However, they do illustrate many interesting principles of the chemistry of adhesion through organic polymers. 

Joe Groeger has more than 25 years of practical experience in development, selection, formulation, testing, and analysis of rubber, thermoplastics, adhesives, foams, composites and polymer coatings. 

Since in the final state these are thermoplastic adhesives, the utilization temper-atiue of the adhesive bonds is Umited to approx. 80°C. Some adhesive types are heat-stable up to 130°C, although the adhesive strength at this temperature is greatly reduced since in this case the inherent strength of the cyanaciylate determines the stability of the plastic bond. 

The peeling off of a hook fitted with a pressure sensitive adhesive and attached to a ceramic or glass surface can be regarded as a typical example for the creep behavior of an adhesive layer. In particular, thermoplastic adhesives that, to a great extent, also include pressure-sensitive adhesives (Section 5.6) tend to creep under high strain. A reason for this behavior is the time-related failure of individual bonds between the polymer molecules due to the strain imposed from outside. The application of adhesives with a higher crosslink ratio can reduce the adhesive layers tendency to creep. 

Poly(ester-imide)s are a class of polymers known for more than 35 years. They are used today in large tonnage as electrical insulating materials. The patent literature reviewed shows that predominant research activities in the past were focused on improving the electrical, thermal and mechanical properties. In recent times new applications for these polymers have been found, such as engineering thermoplastics, adhesives, printed circuit boards and membranes. Excellent properties and easy processing will probably lead to a continuous growth of poly(ester-imide) business. 

Heat sensitive or thermoplastic adhesive-based labels activated by heat... 

Thermoplastic adhesive labels generally find a special usage and are now meeting increasing competition from self-adhesive... 

Thermoplastic adhesives have to be used with limited product resistance. Some layer combinations do not require adhesives or tie layers. 

BARTZ, KENNETH W. HIGGINS, JOHN J. BEREJKA, ANTHONY J. DICRESCE, AMERIGO J. Thermoplastic Adhesive Compositions. US Patent 3,868,433 (1975) and US Patent 3,987,122 (1976). 

The polymerization of allyl esters of saturated monobasic acids, e.g., allyl acetate and allyl laurate, yields linear thermoplastic polymers containing 5-20 monomer units per molecule. These homopolymers and copolymers with vinyl monomers such as vinyl acetate, vinyl chloride, and vinylidene cliloride have been used as thermoplastic adhesives and plasticizers. 

Recycling of industrially produced material is important from the environmental point of view. For the recycling of materials bonded with adhesives, dismantlement of the products is necessary to separate them, although that is quite difficult. Therefore, a novel technique by which adherends can be dismantled easily has to be established. A conventional way to solve the problem is the use of thermoplastic adhesives because they soften at high temperature and joints bonded with them can be separated by applying small forces. Recently, a new kind of adhesive including thermally expansive microcapsuies has been proposed as an alternative method [1]. A joint bonded with such an adhesive can be dismantled by heating, as shown in Fig. 34.1. 

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