Transparent polyolefins

The TPX experimental product of Mitsubishi Petrochemical Ind. (221) is an amorphous, transparent polyolefin with very low water absorption (0.01%) and a glass-transition temperature comparable to that of BPA-PC (ca 150°C). Birefringence (<20 nm/mm), flexural modulus, and elongation at break are on the same level as PMMA (221). The vacuum time, the time in minutes to reach a pressure of 0.13 mPa (10 torr), is similarly short like that of cychc polyolefins. Typical values of TPX are fisted in Table 11. A commercial application of TPX is not known as of this writing. 

Transparent polyolefin systems containing P.R.88 are stable up to 260 to 300°C, depending on the type and on the pigment content. 1/3 SD systems are heat stable up to approximately 240 to 260°C. Some types are recommended only for use in LDPE at low processing temperatures. The lightfastness of such specimens is between step 6 and step 7 on the Blue Scale. P.R.88 considerably affects the shrinkage of injection-molded articles, a feature which somewhat restricts its application in such systems. 

ClearTint, Transparent polyolefin colorants, Milliken Chemical Co. 

Direct UVA IS analysis of plastics may be performed on transparent films or compression moulded plaques, with sample thicknesses usually between 50 and 500 /xm depending on the absorbances of the analytes and the polymer. For purposes of reproducibility it is advised to press several thin films of various polymer granules. In-polymer UV analysis of a UV transparent polyolefin matrix allows detection of phenolic AOs (at 280 nm) or UVAs (at 330-340 nm) down to 25 ppm level. 

Poly 4-metiiylpeiitene-l (TPX) often known by its trade name TPX, this thermoplastic is a transparent polyolefin. 

Impart a bright and intense colour to a substrate by a process which at least temporarily destroys any crystal structure of the colouring substances. Dyes are transparent and easy to disperse and process. Dyes are incompatible with polyolefins, having a tendency to bleed and plate out. Due to the solubility and... 

P.Y.116 is also used in plastics. In plasticized PVC, it shows little tendency to bleed and is thermally stable up to 180°C. The lightfastness of transparent PVC colorations (0.1% pigment) equals step 7-8 in 1/3 SD (with 5% TiOz), it corresponds to step 6 on the Blue Scale. Insufficient heat resistance limits the application of P.Y.116 in polyolefins, polystyrene, and other polymers which are processed at high temperature. 

In polymers, P.R.146 is only used to color rigid PVC. Transparent colorations (0.1 %) afford a lightfastness which matches step 8 on the Blue Scale, while opaque specimens equal between step 6-7 and step 6, depending on the standard depth of shade and on the TiOz content. Insufficient heat resistance in polyolefins (less than 200°C) precludes its use in such media. 

The plastics industry uses P.O.38 primarily to color PVC, polyolefins, and polystyrene. In plasticized PVC, the pigment does not bleed at concentrations up to about 0.3%. Its lightfastness is good. Transparent colorations in rigid PVC (0.1%) equal step 7-8 on the Blue Scale while opaque versions (0.1% pigment+ 0.5% Ti02) equal step 7. 

In white reductions, P.R.208/polyolefin systems only withstand temperatures below 200°C, while transparent specimens (0.1%) are stable up to approximately 240°C. Thus the pigment is a suitable and economical candidate for polypropylene spin dyeing, provided the temperature is kept below 200°C. It is also possible to apply higher temperatures if a color shift towards more yellowish shades is acceptable. In terms of lightfastness, P.R.208 meets the common standards for interior application. 

P.Br.25 also shows excellent lightfastness in polyolefins. Transparent polystyrene samples are heat stable up to 280°C, while specimens reduced considerably with Ti02 withstand up to 240°C. P.Br.25 is also used in polyester, in which it provides an interesting raw material for the manufacture of bottles. 

P.Br.23 shows excellent heat stability in polyolefins. 1/3 SD samples containing 1 % TiOz, as well as transparent colorations at 1/3 SD in HDPE are stable to exposure to 300°C for 5 minutes. In injection molding, P.Br.23 considerably affects the shrinkage of the plastic at 220°C, an effect which diminishes with increasing temperature (Sec. 1.8.3.2). 

Transparent and reduced 1/3 SD polyolefin systems are stable up to 300 to 320°C. 0.25% pigment is required in order to formulate 1/3 SD HDPE samples containing 1% TiOz. P.O.43, incorporated in injection-molded partially crystalline plastics such as HDPE, affects the shrinkage of the medium, which precludes its use in nonrotation symmetrical injection-molded articles (Sec. 1.6.4.3). 

The plastics industry uses these pigments mainly for polyolefins. The tinctorial strength is comparatively moderate. 1/3 SD HDPE colorations (1% TiOz), for instance, require between 0,22 and 0,7% of these pigment grades. Such colorations are heat resistant up to 300°C. Transparent colorations in 1/3 SD are stable up to 250°C. 

New polymer structures allow the control of processability and final characteristics. For example, Mitsui is launching nanostructured metallocene alpha-olefins that have a crystallite size of the order of nanometres instead of microns as for conventional metallocene polyolefins. This yields a better balance of transparency, heat resistance, flexibility and elasticity characteristics. Targeted applications are automotive interior trim, packaging film, construction materials, protective films for electronic and optical parts, sealing products and as polymer modifiers. 

Cast film extrusion of polyolefins has been developed to obtain flexible films with a high level of transparency by freezing the amorphous polymer structure of the melt on a chill roll. Cast films are mono-oriented in extrusion direction. 

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