Spectacle frames

Today the principal outlets are knife handles, table-tennis balls and spectacle frames. The continued use in knife handles is due to the pleasant appearance and the ability of the material to after-shrink around the extension of the blade. Table-tennis balls continue to be made from celluloid since it has been difficult to match the bounce and handle of the celluloid ball, the type originally used, with balls fabricated from newer polymers. Even here celluloid is now meeting the challenge of synthetic polymers. Spectacle frames are still of interest because of the attractive colour. There are, however, restrictions to their use for this application in certain countries and cellulose acetate is often preferred. 

Carlsen L, Andersen KE, Egsgaard H. 1986. Triphenyl phosphate allergy from spectacle frames. 

The bluish white, hard, yet ductile, metal is inert to all acids and highly non-abrasive. Used for heavy-duty parts in electrical contacts and spinning jets. Reflectors are prepared from the mirror-smooth surfaces (e.g. head mirrors in medicine). Thin coatings provide a corrosion-resistant protective layer, for example, for jewelry, watches, and spectacle frames. The metal is a constituent of three-way catalysts. Rhodium complexes are used with great success in carbonylations (reactions with CO) and oxidations (nitric acid) in industry. Platinum-rhodium alloys are suitable thermocouples. 

In one report, a woman with dermatitis from the plastic nose pads of her spectacle frames was found on patch testing to react to 1% butyl acrylate but not to ethyl or methyl acrylate. The sensitization was attributed to butyl acrylate, which might have been present in the plastic nose pads. 

Hambly EM, Wilkinson DS Contact dermatitis to butyl acrylate in spectacle frames. Contact Dermatitis 4 5, 1978... 

Oliwiecki S, BeckMH, Chalmers RJG Contact dermatitis from spectacle frames and hearing aid containing diethyl phthalate. Contact Derm 25 264—265, 1991... 

Another magical titanium material is the alloy nitinol, which can remember a previous shape and return to it. Nitinol consists of 55% nickel and 45% titanium, a combination which corresponds to one atom of nickel for each atom of titanium. This alloy was developed in the US in the 1960s at the Nickel Titanium Naval Ordnance Laboratory which gave rise to the name Ni-Ti-NOL. This alloy is best known as spectacle frames which can be twisted in a way that would be permanently deformed were they to be made of any other metal but, because they are made of nitinol, they will jump back to their original shape when the pressure is removed. 

The sheets were sold for many different purposes, an important one in terms of tonnage and value being the manufacture of spectacle frames. In this application the requirement might a plain colour, a laminate of transparent with translucent or coloured material, or special effects such as tortoise-shell. 

For routine examinations most clinicians dilate patients pupils only after most other examination procedures have been performed. Complete ocular and medical histories, visual acuities, external examination, pupillary examination, refraction, biomicroscopy, tonometry, and other routine evaluations precede instilling the mydriatic (Figure 20-1). This approach ensures that dilation does not interfere with the refraction, assessment of accommodation or binocularity, or any other refractive finding. In addition, the predilation examination procedures allow the clinician to identify any cautions or contraindications to dilation. In most routine cases ophthalmoscopy or fundus biomicroscopy is the only procedure remaining after dilation. After drops have been instilled for dilation, the patient may proceed to the reception area, the dilation room, or the dispensary for spectacle frame selection while the pupils dilate. While the patient s pupils dilate, the practitioner can examine the next scheduled patient. In 20 to 30 minutes, after all procedures except dilation have been performed on the second patient and the mydriatic drops instilled, the first... 

Thou still rare and expensive, tortoiseshell was a vourite material in Europe by the twentieth century. It was made into dressing table sets, mounted in silver and inlaid with piqu6 work. Card cases were sometimes made of the pressed material, and sometimes finely carved. Cane and umbrella handles, small boxes, spectacle frames and cases, frns, opera sses, and many other similar objects could be made from, or adorned with, this attractive material. 

Metal ions. Copper ions act as catalysts to accelerate deterioration reactions of many polymers, particularly synthetic rubbers. Spectacle frames constructed from cellulose nitrate are often more degraded in the area around copper-containing screws and around the wires in the arms, than... 

Some metals, notably copper, accelerate the rate of degradation of cellulose nitrate. Copper screws and arm wires of cellulose nitrate spectacle frames... 

The high inflammability and relatively poor chemical resistance of celluloid severely restrict its use in industrial applications. Consequently the material is used because of its desirable characteristics, which include rigidity, dimensional stability, low water absorption, reasonable toughness, after-shrinkage around inserts, and ability of forming highly attractive colored sheeting. Today the principal outlets of celluloid are knife handles, table-tennis balls, and spectacle frames. Celluloid is marketed as Xylonite (BX Plastics Ltd.) in UK. 

Photographic film, packaging films, graphic tracing films, display boxes, spectacle frames, hair brushes, combs. 

Up to the 1950s photographic film, bicycle parts (mudguards, pump covers), shadow puppets, dolls, spectacle frames. 

Source of sample Degraded spectacle frames from the 1920s Sample preparation None. ATR accessory used to run FTIR spectrum... 

Cellulose acetate is the most important cellulose ester and various processing techniques for forming shaped bodies exist for this polymer. The mixed esters discussed above, CAP and CAB, are used predominantly for injection moulding applications in suitably plasticized form and are marketed as pellets. This is done for CA as well, but additionally, alternative processing routes are available where solution methods play an important role. This is in particular the case for fibre spinning and (thinner) film manufacture where cellulose diacetate (CDA) is dissolved in acetone and dry spun or solvent cast. Moreover, the traditional solventusing block process is employed for obtaining sophisticated, multicoloured thick sheets for applications like spectacle frames. 

Cellulose acetate (CA), cellulose acetobutyrate (CAB) cellulose propionate (CP), Thermoplastics manufactured from cellulose by esterification with acetic acid (CA), acetic acid and butyric acid (CAB), or propionic acid (CP). Their products are characterized by high impact strength, transparency (without filler), and oil resistance. Examples of applications consumer goods, toys, combs, keys for music instruments and business machines, spectacle frames, photographic films. CA fibres are used for underwear, neckties, etc. Trade names Cellidor (FRG), Setilithe (B), Tenite (USA). 

Vibration welding is nsed extensively by the automotive industry in the manufacture of components snch as car bumpers, air intake manifolds, fuel pumps, instrument panels, parcel shelves, inner door panels and for the hermetic sealing of air ducting to the internal surface of the dashboard. Other applications include spectacle frames, typewriter covers, filter housings, motor saw housings and heating valves. 

Other polymers of the mono(meth)acrylate type are mostly used in industry. Leather finishes, adhesives, paints, printing inks and coatings are examples of practical applications. Butyl acrylate is sometimes used in spectacle frames. Often, 2-ethylhexyl acrylate is used in the manufacture of pressure-sensitive adhesives, but a wide range of other acrylates are also used in this field. 

Verdich J, Skoven I (1979) Allergic dermatitis from Desmophen, a polyether alcohol. Contact Dermatitis 5 120 Vilaplana J, Romaguera C, Grimalt F (1987) Allergic contact dermatitis from aliphatic isocyanate on spectacle frames. Contact Dermatitis 16 113... 

Sonnex TS, Rycroft RJG (1986) Dermatitis from phenylsali-cylate in safety spectacle frames. Contact Dermatitis 14 268-270... 

Allergic and irritant contact dermatitis to various additives are briefly mentioned in connection with various plastics by other authors. In spite of the fact that phthalates are the most widely used additives, there are only a few reports in the literature of contact dermatitis caused by phthalates. Allergic contact dermatitis from dibutyl phthalate has been reported when used in a plastic watch strap, an anti-perspirant spray and a steroid cream [1-4]. Contact dermatitis from diethyl phthalate has been reported from spectacle frames, and a hearing aid was reported to cause contact dermatitis from cellulose-ester plastics [5, 6]. Two cases of contact allergy to the dimethyl phthalate in computer mice have been reported by Capon et al. [7]. 

An outbreak of dermatitis that occurred in an aircraft factory was caused by o-diglycidyl phthalate, among other chemicals [8]. Burrows and Rycroft have reported contact allergy to tricresyl ethylphthalate in a plastic-nail adhesive [9]. Phthalates can also appear in deodorant formulations, perfumes, emollients and insect repellents [10]. Triphenylphosphate allergy from spectacle frames has been reported [11,12]. 

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