TPX is an abbreviation with several distinct meanings depending on the field. It most commonly refers to the Tokyo Stock Price Index (TOPIX) in finance, a specialized plastic material made by Mitsui Chemicals, or a suffix in the Pantone color matching system. Here’s what each one means and why it matters.
TPX as a Stock Market Index (TOPIX)
In finance, TPX is the ticker abbreviation for TOPIX, the Tokyo Stock Price Index. It’s one of the most important benchmarks for the Japanese stock market, functioning much like the S&P 500 does for U.S. equities. TOPIX covers a broad swath of Japanese publicly traded companies, making it a go-to measure for investors tracking the overall health of Japan’s economy.
TOPIX is a free-float adjusted market capitalization-weighted index, which means larger companies have more influence on the index’s movement, and only shares available for public trading (not locked up by insiders) count toward the weighting. The index was set at a base value of 100 points on January 4, 1968, and official calculation began in July 1969. It’s maintained by the Japan Exchange Group (JPX), which operates the Tokyo Stock Exchange.
If you see “TPX” on a financial news site or trading platform in the context of Japanese markets, it almost certainly refers to TOPIX.
TPX as a Plastic Material
TPX is also the brand name for polymethylpentene (PMP), a specialty thermoplastic manufactured by Mitsui Chemicals. It stands out from other plastics for a combination of unusual properties that make it useful in industries ranging from food packaging to medical devices.
The most notable characteristic is its transparency. TPX transmits more than 93% of visible light with very low haze, putting it on par with glass or acrylic. It actually outperforms both glass and other transparent plastics in the ultraviolet range, which matters for applications where UV transmission is needed. Its refractive index is just 1.463, one of the lowest among clear plastics.
TPX is also the lightest thermoplastic resin available, with a density of just 830 kg/m³. For comparison, water is 1,000 kg/m³, so TPX actually floats. Despite being lightweight, it handles heat well. Its high melting point makes it suitable for steam sterilization, which is why it shows up in medical and laboratory settings.
Key Properties
- Gas permeability: About 10 times higher than polyethylene, making it ideal for gas separation membranes, permeable films, and hollow fibers used in devices like artificial lungs.
- Chemical resistance: Holds up well against acids, alkalis, and alcohol, outperforming polycarbonate and acrylic in this area.
- Low surface tension: At just 24 mN/m, TPX releases easily from other materials. This “releasability” makes it valuable as a mold release film or coating in manufacturing.
- Steam and water resistance: Extremely low water absorption means it doesn’t warp, swell, or break down even in boiling water.
- Low dielectric constant: With a dielectric constant of 2.1, it works well as an insulator in electronics and high-frequency applications.
Common Uses
You’ll find TPX in microwavable food containers, food wraps, baking cartons, and heat-resistant tableware. In healthcare, it’s used for medical packaging, labware, animal cages, and device components that need repeated sterilization. Manufacturers use it as a release film for circuit boards, synthetic leather production, LED molds, and rubber hose manufacturing. It also appears in water treatment membranes, wire and cable insulation, cosmetic packaging, and experimental lab equipment.
TPX in the Pantone Color System
If you work in design, fashion, or printing, you may encounter TPX as a suffix on Pantone color codes. A Pantone reference number in the Fashion, Home + Interiors system uses a format like two digits, a dash, and four digits followed by either TPX or TC. The TPX suffix indicates that the color reference was printed on paper. TC, by contrast, means the swatch is on cotton fabric. So “18-1664 TPX” and “18-1664 TC” refer to the same color, but reproduced on different materials.
This distinction matters because the same pigment can look slightly different on paper versus fabric. If you’re specifying a color for textile production, you’d want the TC version. For printed materials or general color communication, TPX is the standard reference.
Other Uses of the Abbreviation
TPx Communications is a U.S. provider of managed IT services, primarily serving the healthcare, financial, and retail industries. The company offers managed IT, unified communications, network connectivity, and cybersecurity services. If you searched “TPx” in a business or tech context, this may be what you were looking for.
TPXimpact Holdings PLC is a separate company, a UK-based technology services firm that provides digital transformation consulting to commercial, government, and nonprofit clients. Its shares trade under the ticker symbol TPX on the London Stock Exchange.