Phenolic resin laminate

Yellow Phenol, burnt paper Phenolic resin laminates... 

Nitrile rubber/phenolic resin produces one of the most durable and toughest elastomeric materials developed in the adhesive industry. Further, its resistance to water as to organic solvents is excellent. For these reasons, the nitrile rubber/phenolic resin laminates are used in printed circuit board manufacturing, to bond metallic substrates between themselves (aluminium, steel) and to bond rubber to magnesium. Films of nitrile rubber/phenolic blends have also been used in the aircraft industry for bonding metal-to-metal surfaces in both plain and honeycomb sandwich constructions. 

Fabrics of cotton or linen are used as reinforcement in several grades of laminates—usually impregnated with a phenolic resin. Laminates with these fabrics have better water resistance than paper-based laminates. They machine well and have good physical properties, especially impact strength and abrasion resistance. Their electrical properties are poor. They are used for gears and pulleys. 

Phenolic resin-laminated mats and sheet made from glass fiber and other mineral fiber materials are among the most important noise damping and thermal insulation materials. The liquid resins used to manufacture these insulation materials provide both excellent mechanical strength and good thermal and moisture resistance. 

Fig. 13. Effect of moisture on electric strength of (a) paper—phenolic resin laminate and (b) glass cloth-melamine laminate. A, At 25°C and 96% rh B, 50°C and 96% rh C, in distilled water at 25°C D, in seawater at 25°C E, in distilled water at 50°C and F, in seawater at 50°C.

Fig. 25. Resistivity of laminate, 6.2 mm thick, at 96% rb and 23°C. A, Volume resistivity perpendicular to laminations B, surface resistivity in machine direction C, surface resistivity across machine direction D, volume resistivity along laminations in machine direction E, volume resistivity along laminations across machine direction, (a) Paper-phenolic resin laminate (b) cotton cloth-phenolic resin laminate (c) coarse glass cloth-silicone resin laminate and (d) fine-weave, glass cloth-silicone resin laminate.

Fig. 47. Effect of diying a 6.3-mm paper-phenolic resin laminate on dissipation factor, tan S (solid lines), and capacitance, C (broken lines), at 50 Hz. A, 4 h at 105°C B, 16 h at 105°C C, 96 h at 105°C and D, 192 h at 105°C before test. The laminate initially contained some residual water as pressed.

Fig. 48. Effect of voltage stress on dissipation factor of A, paper-phenolic resin, laminate at 23° after 1 wk at 90% rh and B, after 1 wk at 50% rh C, dry glass-cloth-silicone laminate.

Phenol—formaldehyde resins are used as mol ding compounds (see Phenolic resins). Their thermal and electrical properties allow use in electrical, automotive, and kitchen parts. Other uses for phenol—formaldehyde resins include phenoHc foam insulation, foundry mold binders, decorative and industrial laminates, and binders for insulating materials. 

Phenolic Resins. PhenoHc resins [9003-35 ] (qv) are thermosets prepared by the reaction of phenol with formaldehyde, through either the base-cataly2ed one-stage or the acid-cataly2ed two-stage process. The Hquid intermediate may be used as an adhesive and bonding resin for plywood, particle board, ftberboard, insulation, and cores for laminates. The physical properties for typical phenoHc laminates made with wood are Hsted in Table 1. 

For the lubricated machines, vanes are made of a laminated material impregnated with phenolic resin. For a non-lubricated design, carbon is used. The vane number influences the differential pressure between adjacent vane cells. This influence becomes less as the number of vanes increases. 

From the above comments it will be seen that it is rather difficult to quote typical figures for laminates based on phenolic resins. Thus the figures given in Table 23.3 can be considered only as a general guide. 

Table 23.3 Average physical properties of phenolic resin-based laminates...

Although phenolic resins are too dark for use in the surface layers of decorative laminates these resins are employed in impregnating the core paper. In the.se cases a melamine-formaldehyde resin is used for impregnating the top decorative layer. Phenolic laminates have also been used in aircraft construction and in chemical plant. 

Decorative laminates have a core or base of Kraft paper impregnated with a phenolic resin. A printed pattern layer impregnated with a melamine-formaldehyde or urea-thiourea-formaldehyde resin is then laid on the core and on top of this a melamine resin-impregnated protective translucent outer sheet. The assembly is then cured at 125-150°C in multi-daylight presses in the usual way. 

Phenolic resins are adaptable to many applieations. The list is very long, however, the major uses are wood binders, glass insulation binders, molding compounds, laminates, foundry binders, coatings, friction linings, abrasives, and oil well propants [59-66]. They have found their way into a number of new, high technology uses such as rocket motor wear parts, military armor, sports equipment. 

The highest mechanical strengths are usually obtained when the fibre is used in fine fabric form but for many purposes the fibres may be used in mat form, particularly glass fibre. The chemical properties of the laminates are largely determined by the nature of the polymer but capillary attraction along the fibre-resin interface can occur when some of these interfaces are exposed at a laminate surface. In such circumstances the resistance of both reinforcement and matrix must be considered when assessing the suitability of a laminate for use in chemical plant. Glass fibres are most commonly used for chemical plant, in conjunction with phenolic resins, and the latter with furane, epoxide and, sometimes, polyester resins. 

Phenolic resins Good acid resistance, good electrical properties (except arc resistance), high heat resistance Compression molding, continuous lamination... 

Deconvolution technique, 14 237 Decoration, gold, 12 693-694, 703 Decorative cosmetics, 7 860-862 Decorative laminates, phenolic resins in, 18 789-790... 

In order to impregnate paper, wood and other fillers, nearly 10-15 per cent of the phenolic resins is produced as alcoholic solutions. These find use for decorative purposes for counter tops and wall coverings and industrial laminates of electrical parts. 

Elastomers Solutions of NR have been used for laminating textiles for over a century. The Macintosh raincoat, invented in 1825, consisted of two sheets of cotton adhered by an inner layer of natural rubber. SBR is used as an adhesive in carpet backing and packaging. Neoprene (polychloroprene) may be blended with a terpene or phenolic resin and used as a contact adhesive for shoes and furniture. 

It has been demonstrated that red oak OSL could be used to replace 35% to 40% of the phenol (or phenolic resin solids) in phenol-formaldehyde resins used to laminate maple wood and to bond southern pine flake boards (wafer-board and/or strandboard) without adversely affecting the physical bond properties. While this pulping process and by-product lignin do not commercially exist at this time in the United States, lignins from such processes are projected to cost 40% to 50% less than phenol as a polymer raw material. 

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