Transparent resin compositions with near infrared absorption characteristics

Abstract

This invention provides transparent resin compositions of polycarbonate, polyester, methacrylic, styrene, polyvinyl chloride, polyolefin, and polyamide resin, having the advantageous effects of efficiently absorbing near infrared radiation (780-1800 nm) and efficiently transmitting visible light (380-780 nm). The invention provides transparent resin compositions with excellent near infrared absorption characteristics comprising 100 parts by weight of a transparent thermoplastic resin, about 0.01 to about 2 parts by weight of a specific thiuram compound and / or a specific metal dithiocarbamate compound, and about 0.01 to about 2 parts by weight of a specific copper compound. It also provides transparent resin compositions with excellent near infrared absorption characteristics comprising 100 parts by weight of a transparent thermoplastic resin, about 0.01 to about 2 parts by weight of a specific copper dithiocarbamate compound, and about 0 to about 2 parts by weight of a specific copper compound.

Description

[0001] This invention relates to transparent resin compositions that absorb near infrared radiation (with wavelengths in the range of 780-1800 nm). More particularly, it relates to excellent transparent resin compositions capable of both efficiently absorbing near infrared radiation and efficiently transmitting visible light (380-780 nm).BACKGROUND OF THE PRIOR ART[0002] Transparent resin materials with near infrared absorption characteristics possess both clearness and ability of heat radiation shielding by near infrared absorption. These features make them attractive as light-admitting materials for buildings, windows of transport vehicle, ceilings, doors, arcades, garages, sunrooms, greenhouses, etc.[0003] Their ability of absorbing near infrared radiation also promises their uses in such applications as eye-protecting lenses and other safety glasses, infrared-sensitive filters, and photosensitive materials using semiconductor laser beam sources.[0004] As a conventional transpare...

AI Technical Summary

Benefits of technology

[0047] The transparent thermoplastic resin may be mixed with any of various heat stabilizers, infrared absorbers, ultraviolet absorbers, colorants, fluorescent brighteners, mold releasing agents, antiblocking agents (silica, crosslinked polystyrene beads, etc.), softening agents, antistatic agents, and other additives, provided that these materials do not impair the advantageous effects of the invention.

[0048] There is no special limitation to the method of mixing the thiuram compound and / or the metal dithiocarbamate compound and copper compound in the transparent resin composition of the invention. For example, either mixing by means of a conventional mixer such as a tumbler or ribbon blender or melt mixing by an extruder may be used.EXAMPLES

[0049] The following examples illustrate the invention without however limiting it. All parts and % are by weight.Examples1-9 & 12-16 and Comparative Examples 1-5 & 10-14

[0050] As a transparent thermoplastic resin, 100 parts of a polycarbonate resin ("Calibre (trademark of the Dow Chemical Company) 200-3" available from Sumitomo Dow Ltd., with a viscosity-average molecular weight of 28,000) is mixed with various compounds in amounts given in Table 1. The mixtures are each melt mixed by a 40 mm-diameter extruder (a single-screw extruder manufactured by Tanabe Plastics) at 280.degree. C. and at a screw speed of 80 rpm. Various pelletized products are thus obtained.

[0051] The pellets so obtained are molded by an injection molding machine (Model "J-100" manufactured by Japan Steel Works) at 300.degree. C. into flat sheet samples (90.times.50.times.3 mm). Light transmission (.tau..sub..lambda.) at wavelengths in the range of 380-1800 nm through these flat sheet samples is measured using a spectrophotometer (Model "UV3100" manufactured by Shimadzu Seisakusho LTD.). The visible light transmission (.tau..sub.v, 380-780 nm) and the solar radiation transmission .tau..sub.e, 340-1800 nm) values of the heat radiation shielding sheet are determined in conformity with the procedures of Japan Industrial Standard (JIS) R-3106.

[0052] The visible light transmission (.tau..sub.v) is calculated from the light transmission (.tau..sub..lambda.) by the equation 1 v = 380 780D V ( ) 380 780D V

Problems solved by technology

The near infrared-absorbing, transparent resin materials of the prior art have had problems.

For example, the near infrared absorbers of organic type are inferior in durability and have difficulties in sustaining their effect.

Meanwhile, the absorbers of complex type are durable but absorb part of the radiation in the visible region too, and they often are colored and hence limited in use depending on the application.

Another prior art system of tungsten hexachloride and tin chloride is a good absorber of near infrared radiation but presents a problem of fading upon standing for many hours in the dark.

The heat radiation reflecting film obtained by the above-mentioned metal vapor deposition rather than by the addition of a near infrared absorber causes a problem of dimming rooms when it is laminated to window glasses.

Moreover, adhering the film to a transparent resin material with adhesive tends to entrap air between the adhered surfaces.

This can seriously reduce the transmission or cause the film to come off easily.

A further problem is the tendency of metal oxidation with time, which leads to discoloration or diminished heat radiation reflectivity.

An amount of more than about 2 parts by weight is also undesirable since it reduces the visible light transmission.

An amount in excess of about 2 parts by weight is again undesirable because it reduces the visible light transmission.

An amount of less than about 0.01 part by weight results in inadequate absorption of light in the near infrared region.

An amount of more than about 2 parts by weight is undesirable either because it reduces the visible light transmission.

If the amount is below about 0.01 part by weight, the light absorption characteristics in the near infrared region will be inadequate.

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