White sidewall tires

When I saw Professor Dickinson s car, I exclaimed to John, Look at that car Have you ever seen such a beautiful car It was 1938 Buick convertible coupe with a rumble seat, black canvas cover, solid bright red color, white sidewall tires, and a classic radiator grill. Dickinson put the box with the S-10 in the rumble seat and closed the lid. As he drove off, I said to myself, I hope he ll let me ride in it sometimes. ... 

Let us consider white-sidewall tires. These are formed by placing a layer of white rubber over a carcass of dark rubber. Under normal conditions, molecules of color in the carcass migrate and bleed through to stain the white-sidewall. This staining can be prevented by incorporating activated carbon in carcass rubber. Then the colored molecules will migrate only until they reach a particle of activated carbon, whereupon they become adsorbed and anchored. 

Chlorobutyl provides flex resistance in the blend chlorobutyl rub-ber/EPDM rubber/NR for white sidewall tires and white sidewall cov-erstrips.22 An important application of chlorobutyl rubber in automotive hose is extruded air conditioning hose to provide barrier properties to reduce moisture gain and minimize refrigerant loss. The polymer is used in compounds for fuel line and brake line hoses. Brominated isobutylene-p-methylstyrene (BIMS) was shown to have... 

In 2010, about 12 billion pounds of titanium dioxide was produced in the world however, only about 1% of this output was used in rubber. In the 1970s about 3% of tbe titanium dioxide produced was used in rubber when white sidewall tires were popular. However, while raised white letter tires are still popular, white sidewalls have dropped in popularity. Titanium dioxide is also the premium white colorant for many nontire rubber products as well. 

Clays. Clay, which is generally considered a mild reinforcing filler, is used sparingly in tires. It is most often used in white sidewalls or in low performance tires. Clay toimage in tires worldwide is estimated at 36,000 t annually. Clay can also be coupled to mbber with silanes, and this is the more popular version used in tires. Even with silane coupling, clays are still a weak reinforcing filler compared to both carbon black and siUca. 

Blends of diene and backbone-saturated mbbers are frequently used in appHcations where discoloration by chemical antiozonants caimot be tolerated, yet where cost is stiH a primary consideration (eg, white sidewalls of tires). Disadvantages are that physical properties have to be compromised and the two mbbers usually differ greatly in their rates of vulcanization. Usually, at least a 25% replacement by the ozone-resistant mbber is needed for an appreciable enhancement in ozone protection (6). 

Because of its extreme insolubiUty, barium sulfate is not toxic the usual antidote for poisonous barium compounds is to convert them to barium sulfate by administering sodium or magnesium sulfate. In medicine, barium sulfate is widely used as an x-ray contrast medium (see Imaging TECHNOLOGY X-RAY technology). It is also used in photographic papers, filler for plastics, and in concrete as a radiation shield. Commercially, barium sulfate is sold both as natural barite ore and as a precipitated product. Blanc fixe is also used in making white sidewall mbber tires or in other mbber appHcations. 

Plasticizers. These materials are added to reduce the hardness of the compound and can reduce the viscosity of the uncured compound to facilitate processes such as mixing and extruding. The most common materials are petroleum-based oils, esters, and fatty acids. Critical properties of these materials are their compatibility with the rubber and their viscosity. Failure to obtain sufficient compatibility will cause the plasticizer to diffuse out of the compound. The oils are classified as aromatic, naphthenic, or paraffinic according to their components. Aromatic oils will be more compatible with styrene-butadiene rubber than paraffinic oils, whereas the inverse will be true for butyl rubber. The aromatic oils are dark colored and thus cannot be used where color is critical, as in the white sidewall of a tire. The naphthenic and paraffinic oils can be colorless and are referred to as nonstaining. 

Halobutyl rubber (HIIR) is used primarily in tire innerliner and white sidewalls. These elastomers are best for tire air retention owing to lower air permeability as well as aging and fatigue resistance. The chlorinated (CIIR)... 

In addition to the four primary components in a rubber formulation—the polymer system, fillers, stabilizer system, and vulcanization system—there are a range of secondary materials such as processing aids, resins, and coloring agents (e.g., titanium dioxide used in tire white sidewalls). These are briefly discussed to establish a guideline for the use of the materials in practical rubber formulations. 

Like halobutyl rubber (HHR), ethylene propylene rubber (EPR) has a fully saturated backbone and has only unsaturation points available for vulcanization crosslinking in very small percentages of the pendent diene modifier (EPDM). It has good aging resistance and resistance to fatigue even when heavily loaded with fillers and is utilized in passenger tire white sidewalls. 

TAPDT [2,4,6-tris-(A(-l,4-dimethylpentyl-p-phenylenediamino)-l,3,5-triazine. Table 15 provides reduced discoloration as a result of its increased molecular size which imparts reduced mobility in the rubber matrix (91). Discoloration results from bloom of ozonation by-products of the antidegradant to the rubber surface. PPD containing compounds will stain adjacent compounds in a composite structure because of migration of the PPD. An example is a black sidewall protected by PPD staining the white sidewall of a tire. TAPDT does not... 

Talc is used in tires in white sidewall compounds to provide a smooth appearance to the buffed sidewall. The large platelets of talc provide a barrier to gas and moisture permeability in compounds, which allows talc to be used in applications such as hydraulic and automotive hoses, barrier films, and tire innerliners. 

Titanium dioxide itself is found in three crystalline forms rutile, anatase, and brookite. Titanium dioxide as a final product for use in rubber is commonly used in the rutile form where no chalking is desired and in the anatase form where chalking characteristics are desired, as with a tire white sidewall application. 

EPDM is the fourth highest volume general purpose elastomer used today in the ruhher industry. At 2.7 hillion pounds of global annual production in 2010, EPDM represents about 10% of the total synthetic rubber production. However, unlike NR, SBR, and BR, this synthetic rubber is mostly used in the nontire sector (only a small amount of EPDM may be used in tire white sidewall compound, cover strip, and bicycle tires). EPDM is commonly used in single-ply roofing, in automotive weatherstrips, and hundreds of other applications. 

Anatase is the softer form and will chalk in the compound, which can be good for self-cleaning the surface of a tire s white sidewall. 

The first silane applications in mbber tires used mercaptosilane to modify siliea and clay fillers. Commercial applications were limited to specialty areas, such as white sidewall components, some tread stocks, and some off-road tires, but processing and physical property deficiencies limited commercial applications. However, Degussa Corporation, which... 

Antioxidants used in rubber compounds often are classified as staining or nonstaining depending on whether or not they develop color in use. In a carbon black-loaded tire tread, a staining material has no drawback. But in the white sidewalls, it is important to use additives that are colorless to start with and stay colorless as they protect against oxidation. Phenylenediamine derivatives are very effective antioxidants but discolor (stain) severely. Where light colors must be preserved, a sulfur-cross-linked, hindered phenol that does not discolor is preferable ... 

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