Adhesion resin

The aerodynamic wheel cover of claim 1 wherein said adhesive means comprises an adhesive selected from the group consisting of velcro, adhesive tape, or an adhesive resin. 

The adhesive resins are of the novolak type and generally hardened by paraformaldehyde (which may be supplied mixed with coconut shell flour or diatomaceous earth) in conjunction with an accelerator such as magnesium oxide. 

Extensive use of the three-dimensional solubility parameters for predicting adhesion seems not to have been made, although its additional flexibility should make it successful over a wider range of conditions than the single-parameter approach. Some recent studies involving dental adhesion employed the method with success. Asmussen and Uno fl40 successfully correlated the shear bond strength of various dental adhesive resins, characterized in terms of their three-... 

When an adhesive solidifies and the joint is loaded through such an interface, stress is transferred from the substrate to the adhesive through these attachment points, and the adhesive resin adjacent to these attachment points is loaded. The strain energy in this system is expressed by the following equation [53] ... 

Hydrocarbon resins, rosin, rosin ester, coumarone indene resins, and terpene resins can be directly added to solvent-borne adhesives. For latex adhesives, resin emulsification must be produced before addition. 

Absorption and wetting. Generally, it is necessary for the adhesive resin to wet the substrate surfaces. The surface energy of the composite substrate must be greater than the surface energy or surface tension of the resin in order for effective wetting to occur. 

The second observation is that the EB-curable adhesive resins show no change in adhesive properties from liquid helium temperatures up to temperatures Just below their service temperatures. This can be seen for the adhesives, EB2000 and 1 1L. At this time there is no explanation for this behavior. 

Both the wood-based panel industry and the adhesive industry show a high commitment to and great capability towards innovation. The best evidence for this is the considerable diversity of types of adhesives used for the production of wood-based panels. Well-known basic chemicals have been used for a long time for the production of the adhesives and their resins, the most important ones being formaldehyde, urea, melamine, phenol, resorcinol and isocyanate. The greater portion of the currently used adhesive resins and adhesives for wood-based panels is produced with these few raw materials. The how to cook the resins and the how to formulate the adhesive become more and more complicated and sophisticated and are key factors to meet today s requirements of the wood-based panel industry. 

Adhesives and resins are one of the most important raw materials in wood-based panels. Thus, each question concerning the life cycle assessment and the recycling of bonded wood panels does bring into question the adhesive resins used. This includes, for example, the impact of the resin on various environmental aspects such as waste water and effluents, emission of noxious volatile chemicals during production and from the finished boards, or the reuse for energy generation of wood panels. The type of resin has also a crucial influence on feasibility and efficiency for several material recycling processes. 

The so-called El-emission class describes a wood panel presenting formaldehyde emission which is low enough to prevent any danger, irritation or inflammation of the eyes, nose and mouth mucous membranes. However, it is important that not only the boards themselves, but also the veneering and carpenter s adhesive resins, laquers, varnishes and other sources of formaldehyde are under control, since they also might contribute to the mixture steady state formaldehyde concentration [9]. Table 3 gives an overview on some European regulations. However, it is necessary here to introduce the principal types of composite wood products, especially panels, that are produced in this industry ... 

Medium-density fiberboard (MDF) a flat pressed wood composite panel composed of randomly oriented wood fibers obtained by thermomechanical wood pulping and bonded by hot-pre.ssing by using thermosetting adhesive resins. The panel has generally a density of approximately 850 kg/m- and the average amount of resin solids in the board core section is between 11 % and 14% on dry wood. 

Reactivity and hardening reactions of aminoplastic adhesive resins... 

In order to increase the capacity of a production line especially by reducing the necessary press times, adhesive resins with a reactivity as high as possible should be used. This includes two parameters (1) a short gelation time and (2) a rapid bond strength increase, and this even at a low degree of chemical curing. 

Only a small amount of work has been done up to now concerning the prediction of bond strengths and other properties based on the results of the analysis of the resin. Ferg et al. [59] worked out correlation equations evaluating the chemical structures in various UF-resins with different F/U molar ratios and different types of preparation on the one hand and the achievable internal bond as well as the subsequent formaldehyde emission on the other hand. These equations are valid only for well defined series of resins. The basic aim of such experiments is the prediction of the properties of the wood-based panels based on the composition and the properties of the resins used. For this purpose various structural components are determined by means of - C NMR and their ratios related to board results. Various papers in the chemical literature describe examples of such correlations, in particular for UF, MF, MUF and PF resins [59-62]. For example one type of equation correlating the dry internal bond (IB) strength (tensile strength perpendicular to the plane of the panel) of a particleboard bonded with PF adhesive resins is as follows [17]... 

The target of the development of adhesive resins is to achieve high reactivities mitigated by consideration of the storage stability of the resin or the pot life of the glue mix. The reactivity of a glue resin and of a glue mix is determined by various parameters ... 

The contact angles of water and adhesive resin on wood are higher in the case of freshly harvested wood compared to stored chips. This means that the surface of particles from this fresh wood is more hydrophobic. This influences the wetting and the penetration negatively and with this the gluability. Reason for this lower wettability of freshly harvested wood is a higher content of some wood chemical components, or wood extractives, as has been determined by water extraction. This result, however, must not be confused with the better wettability of a freshly cut surface, independently if it is freshly harvested or stored wood. 

In the chemical industry, simple aldehydes and ketones are produced in large quantities for use as solvents and as starting materials to prepare a host of other compounds. For example, more than 1.9 million tons per year of formaldehyde, H2C=0, is produced in the United States for use in building insulation materials and in the adhesive resins that bind particle hoard and plywood. Acetone, (CH.3)2C"0, is widely used as an industrial solvent approximately 1.2 million tons per year is produced in the United States. Formaldehyde is synthesized industrial ) by catalytic oxidation of methanol, and one method of acetone preparation involves oxidation of 2-propanol. 

About 8,000 metric tons of peroxides were consumed in 1972. This consumption was strongly stimulated by the rapid growth in reinforced plastics (Ref 23). The largest volume product is benzoyl peroxide which is used in polystyrene and polyester markets for such items as toys, automobiles, furniture, marine, transportation and mil requirements. Also, methyl ethyl ketone peroxide is used in large volumes to cure (as a catalyst) styrene-unsatur-ated polyester adhesive resins used in mil ammo adhesive applications, as well as in glass fiber reinforced plastic products such as boats, shower stalls, tub components, automobile bodies, sports equipment, etc. The monoperesters are growing slowly because of some substitution of the peroxydicarbonates and azo compds (Refs 8,9 23)... 

The difference between the pH profiles of the two stages of urea-formaldehyde resin synthesis is taken advantage of in the production of these resins (Figure 19.2). In general, the commercial production of urea-formaldehyde adhesive resins is carried out in two major steps. The first step consists of the formation of methylolureas under basic conditions (pH 8 to 9), to allow the methylo-lation reactions to proceed in the absence of reactions involving the condensation of the methylolureas. 

Adhesive bonds, 1 501-502 breaking, 1 513-517 practical strength of, 1 517-521 Adhesive compositions, 1 524-525 Adhesive joints, 1 501-502 Adhesive polychloroprene grades, 19 852 Adhesive resins, amino acid resins,... 

Epibond Epoxy adhesive resin Furane Plastics... 

Figure 3.25 — Electrolytic flow-cell of the tubular type. (A) Whole cell. (B) Detail of working micro-electrode 1 Working electrode 2 reference electrode (Ag/AgCl) 3 counter-electrode (Pt wire) 4 acrylic tube 5 rubber cup 6 electrolyte solution (mobile phase) 7 fused-silica tube (50- or 100-/tm ID) 8 Ni wire (diameter 25 or 50 im, length 5 mm) 9 PTFE tube (0.1-mm ID, 2-mm OD) 10 hole 11 adhesive resin 12 glass pipette 13 silver paste 14 insulator 15 electric wire, (Reproduced from [184] with permission of Elsevier Science Publishers).

Evaluation of Adhesive Bond Strength. Since the cured product of LP-A was brittle, probably due to the low level of formaldehyde charged, LP-B and LP-C were selected as adhesive resins. In order to increase their cure rate, the pH s of LP-B and LP-C resins were adjusted to around 11.2 and 12.0, respectively, prior to adhesive formulation. For the purpose of comparison, the bond strength of the methylolated SEL resin adhesive was examined as well. 

Another large use of normal butenes in the petrochemical industry is in the production of 1,3-butadiene (CH2 = CH = CH = CH2). In the process, a mixture of n-butenes, air, and steam is passed over a catalyst at a temperature of 500°C to 600°C. Butadiene is used extensively to produce synthetic rubbers (see Isoprene) in polymerization reactions. The greatest use of butadiene is for styrene-butadiene rubber, which contains about a 3 1 ratio of butadiene to styrene. Butadiene is also used as a chemical intermediate to produce other synthetic organics such as chloroprene, for adhesives, resins, and a variety of polymers. 

Exposures to dimethylformamide occur during its production and during the production of inks, adhesives, resins, fibres, pharmaceuticals, synthetic leather, and its use as a purification or separation solvent in organic synthesis. It has been detected in ambient air and water. 

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