Rubber & Plastics News ● January 28, 2013 17www.rubbernews.com

Technical

Using predispersed fibers to improve OTR tiresBy Steven Monthey

Rhein Chemie Corp.

Santoweb-treated cellulose fiber prod-uct provides reinforcement for both curedand uncured rubber compounds.

Unlike spherical reinforcements suchas carbon black or silica that rely onchemical or van der Waal’s forces tostrengthen the rubber compound, fiberreinforcements have an aspect ratio thatgive them a directional value to theirstrengthening of the compound.

The aspect ratio is the length of thefiber divided by the diameter of the fiber

and reinforces the rubber compoundmuch like that of rods or wire meshes inconcrete. This type of reinforcement isquite efficient so even a small amount offiber reinforcement can give a signifi-cant increase to low elongation modulusand tear strength.

Aramid fiber can also be used toachieve similar reinforcement. The twodifferences with aramid fiber are itsheat resistance and its ability to be splitinto almost infinitely smaller fibers.Since aramid has an extremely high ten-sile strength, these very small fibers arestill capable of giving significant rein-forcement resulting in a noticeable high-er surface area and aspect ratio thanconventional fibers can achieve.

Types of Santoweb productsThere are five types of Santoweb prod-

ucts:Santoweb D is treated with a black

styrene-butadiene rubber binder, modi-fied for bonding and designed for use innatural rubber, SBR, butadiene rubber,polyisoprene and polychloroprene com-pounds.

It contains a resorcinol formaldehydetreatment which requires a methylenedonor such as HMMM or HMT toachieve maximum reinforcement. San-toweb D is usually recommended forloadings above 10 percent.

Santoweb DX also is treated with ablack SBR binder but is not modified forbonding. It also is designed for use inNR, SBR, butadiene rubber, polyiso-prene and polychloroprene compounds.

Unlike Santoweb D, Santoweb DXdoes not require a methylene donor for

to achieve maximum reinforcement. San-toweb W usually is recommended for load-ings higher than 10 percent.

Santoweb WB also is treated with anon-black polyvinyl chloride binder mod-ified for bonding and designed for use innitrile and silicone compounds. It, too,requires both a resorcinol and a methyl-ene donor to achieve maximum reinforce-ment. Santoweb WB usually is recom-mended for loadings below 10 percent.

For the purpose of this paper we willonly deal with Santoweb DX.

Types of aramid fiber masterbatches

Aramid fibers are categorized by theirfiber type and the polymer type in theirbinder. Their nomenclature consists ofRhenogran trademark followed by thefiber type (either P91 high surface areaor P95 normal surface area) then thepercentage activity and finally the bind-er polymer type.

Since the majority of this type of fibermaster batch goes into power transmis-sion belts, the most common types areRhenogran P95-40/EPDM and RhenogranP91-40/EPDM. Other binders includepolychloroprene, natural rubber, nitrile,

maximum reinforcement. Santoweb DXis usually recommended for loadings be-low 10 percent.

Santoweb H is treated with a blackEPDM binder, modified for bonding anddesigned for use in EPDM and butylcompounds.

It contains a resorcinol for-maldehydetreatment which requires a methylenedonor such as HMMM or HMT to achievemaximum reinforcement. Santoweb Hcan be used at any loading.

Santoweb W is treated with a non-black polyvinyl chloride binder modifiedfor bonding and designed for use in ni-trile and silicone compounds. It requiresboth a resorcinol and a methylene donor

Executive summaryOne of the major causes of premature failure for off-the-road tires is the pen-

etration of a cut so deep in either the tread or sidewall that it reaches the airchamber and flattens the tire.

Predispersed fibers have long been used to improve the performance proper-ties of industrial products such as power transmission belts. Now testing showsthat predispersed fibers significantly can improve the cut and chip resistance ofoff-the-road and other tires that operate in harsh environments

This paper will present data on both cellulose and aramid predispersed fibersshowing their advantages when added to OTR tread or sidewall compounds.

See Fibers, page 18

TECHNICAL NOTEBOOKEdited by Harold Herzlichh

Fig. 1. Effect of non-bonded Santoweb DX at low loading level on tear strength ofan NR compound.

Fig. 2. Effect of 5 phr and 10 phr loadings of Santoweb DX on the green strength ofan NR compound.

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pulp are difficult to disperse unless theyare predispersed in a polymer matrix.This is particularly true with aramidfiber.

Aramid fiber has a linear moleculethat is very polar in nature, making itextremely difficult to disperse withoutsome kind of binder. The inherent aro-matic linear chain gives the fiber aspring-like nature when processed into apulp. These microscopic aramid springs

aggregate with each other and take ex-treme energy to separate each individ-ual to be dispersed into the resultingcompound.

Being polar, aramid pulp is easier toincorporate into polymers like NBR orHNBR but significantly more difficult toincorporate into polymers like EPDM,NR and polybutadiene. As with manyother ingredients which have disper-

The authorSteven Monthey is a technical service chemist at Rhein Chemie Corp.

He has 41 years of experience in the rubber industry, withGoodyear, Bandag, Dayco, Cabot and Hercules before joiningRhein Chemie.

Monthey’s background includes work in product design forhose and belt applications, tires and retreads, vibration isola-tion, medical components and many other rubber segments. AtRhein Chemie in Chardon, Ohio, he currently is involved in thedevelopment and marketing of company products used in auto-motive, tire and medical applications.

He graduated with a bachelor’s degree from Washburn Uni-versity in Topeka, Kan.

Monthey can be reached at steven.monthey@rheinchemie.com.

18 Rubber & Plastics News ● January 28, 2013 www.rubbernews.com

Many rubber, plastic and silicone based products can be dramatically improved with fibers. Adding treated or untreated cotton, polyester, pan carbon, aramids and/or nylon boosts performance in a multitude of ways. Characteristics such as coefficient of friction, abrasion resistance, compression set, tensile modulus, temperature control, green strength, cut and tear resistance, noise reduction and many others can be positively altered.

Contact the fiber professionals at Finite Fiber. We will provide feasibility studies and work with you through implementation to completion.

330-773-6654www.finitefiber.com

Technical

and hydrogenated nitrile. Unlike some of the Santoweb prod-

ucts, aramid fiber master batches do nothave any adhesion enhancement. Usual-ly no more that 10 phr loading is recom-mend for aramid fiber masterbatches.

Proper mixing of fibersTo get the maximum benefit from ei-

ther Santoweb products or an aramidfiber masterbatches, certain steps mustbe taken to ensure proper dispersion.

First, for off-the-road tire tread com-pounds, only 2 to 10 phr loading is rec-ommended. This loading gives the best

resistance to cut and chip growth whilekeeping the tread wear and processingproperties as consistent as possible witha normal compound.

Next, the fiber should be added asearly as possible into the compound withthe other reinforcements. This is impor-tant with both the Santoweb productsand the aramids to get as much disper-sion as possible.

In the case of aramid fibers, they mayneed to be added into a masterbatch sothat additional mixing time can be spentif necessary. All mixing should be donein an internal mixer as mills do not dis-perse these products in a reasonable pe-riod of time.

Why use a polymer bound fiber?Chopped cellulose fiber and aramid

FiberContinued from page 17

See Fiber, page 21

Monthey

Table I. NR compound with 10 phr polymer-bound aramid pulp versus a controlwith no fiber added.

Fig. 3. Low elongation modulus effect for NR.

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Rubber & Plastics News ● January 28, 2013 21www.rubbernews.com

sions issues, pre-dispersing the aramidpulp into a polymer bound medium priorto mixing is one of the most cost-effi-cient ways to achieve the bonuses of thearamid pulp without the extra expenseof multiple mixing passes to achieve theproper distribution and alignment of thefibers.

Santoweb fiber is much easier to dis-perse but still needs a polymer binder tohelp it incorporate easily into the com-pound matrix.

Advantages of short fiber rein-forcement in OTR tire treads

Since short fibers act like wire rein-forcement in concrete, they provide sev-eral advantages in rubber compounds.

First, they provide a stopping pointfor cut growth, preventing a cut or crackfrom penetrating the entire depth of the

tread or sidewall. Next, they provide ad-ditional reinforcement at low elonga-tions when tearing occurs. This increasein low elongation modulus is quite dra-matic even at low loadings.

Finally, the fibers provide additionalgreen strength which can assist in thebuilding process and prevent compo-nents over-stretching during the con-struction of the tire. We will look atthese advantages in detail.

Tear strength improvementFig. 1 is an NR compound showing

the improvement of tear strength usingonly 2 phr of Santoweb DX.

We see the noticeable improvement intear strength from adding 2 phr of San-toweb DX to this compound. This sameimprovement can be achieved with al-most any compound by adding just asmall amount of Santoweb DX.

Using the same compound, Fig. 2shows the improvement in the greenstrength as the amount of the Santowebfiber is increased.

Similar results can also be obtainedwhen using aramid fiber. Data in TableI and Fig. 3 show how the low elonga-tion modulus increases dramaticallywhen 5 phr of aramid pulp is added tothe compound. Since the pulp had an-other 5 phr of a polymer binder, the to-tal phr of the Rhenogran P95-50/NR is10 phr.

ConclusionCutting and chipping long have been

a problem in OTR and other tires thatperform in extremely jagged environ-ments. Now, with the addition of a smallamount of Santoweb DX or RhenogranP95-50/NR, OTR and other componentcompounds can be improved to resist thecutting and chipping resulting in im-proved wear and longer performancelife.

This paper originally was presented atthe International Tire Exhibition & Con-ference in September 2012, in Cleve-land.

Continued from page 18

Fiber

“We wanted our people to have as muchwarning as possible,” Seketa said.

Meanwhile, Zhongding Sealing, formedby its parent company in 2008, is ex-panding its noise, vibration and harsh-ness product distribution center in Mon-roe, Mich., by about 70,000 square feet,increasing its size to about 150,000square feet, he said. The center servesthe North American market. The projectis expected to be complete in July.

Included in the addition is a 10,000-sq.-ft. NVH technical center and about15,000 square feet for the firm’s admin-istrative operation. The majority of thesite will be used as a distribution centerfor the company’s products from Chinaand other plants.

The firm’s U.S. headquarters ulti-mately will move to the Monroe facilityfrom Strasburg.

Zhongding Sealing is closing theStrasburg facility principally because itmirrors the parent company’s produc-tion complex in China, Seketa said. “It’s

the only plant we operate that actuallycompetes with our operation in China.The others are all complementary.”

Layoffs at the factory—which producesnumerous rubber parts, including bushingsand isolators—should begin in March andwill continue in stages into July, he said.

Parts production slowly will shift fromStrasburg to the company’s plants inNingguo, China; Cadillac, Mich.; andHannibal, Mo., the executive said.

The job loss will impact all employeesin all job classifications at the site, in-cluding the operation’s general manager,plant manager, production supervisor,production employees and other per-sonnel, he said.

Zhongding Sealing’s parent steppedinto the U.S. market in 2008 when itbought Allied-Baltic Rubber Inc. and theStrasburg plant for $4.5 million. It re-named the operation Zhongding SealingParts USA and set up its Americanheadquarters at the facility.

A year later it ac-quired Buckhorn Rub-ber Products Inc. andMichigan Rubber Prod-ucts Inc. for $8.5 millionfrom Akron-based My-ers Industries Inc. toboost its presence in theU.S. The company hascontinued to grow sincethen, with its last acqui-sition coming in Octoberwhen it purchased Pre-

cix Inc., a producer of about 1 billionparts a year based in New Bedford,Mass.

Legally know as Acushnet Rubber Co.but operating as Precix since 2001, thefirm produces high-performance sealingproducts—primarily for the automotive,aerospace, energy and industrial indus-tries—at the company’s 305,000-sq.-ft.plant in New Bedford.

looking to add more tire builders andother staff, the executive said.

By year end, he said, the Charles Cityplant is expected to have 237 employeesand production capacity of about 13,500metric tons of tires a year. Approximate-ly 24 U.S. employees are undergoingtraining at plants operated by MitasA.S. in Europe.

The company selected Charles City,

located in the U.S. agricultural heart-land, as the site of its U.S. factory forseveral important reasons, Charvatsaid, including “its Midwestern location,vicinity of OEMs, high work ethics, andthe forthcoming approach of local andstate authorities.”

It’s also a good place to manufacture itsproducts, he said, because the market inNorth America is one of the largest foragricultural radial tires both for theOEM and aftermarket segments, he said.

Charvat anticipates the U.S. opera-tion will continue to improve “as long asthe American farmer’s business grows.

Besides, the radial farm tire offers bet-ter characteristics when compared withthe diagonal tire and when mounted onpowerful tractors. So the share of radialtires on the farm tire market will begrowing.”

Mitas Tires North America focuses onmanufacturing large radial tires, weigh-ing up to half a ton, in Charles City.Parent Mitas A.S., a business unit ofCzech Republic-headquartered CGS A.S.Holding Group, makes a wide range ofindustrial and motorcycle tires, operatesthree factories in the Czech Republicand another in Serbia.

Mitas

Zhongding

Continued from page 1

Continued from page 1

“It’s the only plant weoperate that actuallycompetes with our oper-ation in China.”

Steve Seketa

Teahen chronicled auto industry for 57 yearsBy Dave Versical

Automotive News

DETROIT—John K. Teahen Jr., whochronicled the auto industry’s biggest sto-ries and most powerful players for Automo-tive News with a unique blend of tenacityand grace for more than five decades, diedJan. 8 after a long illness.

Teahan—whose columns have appearedin Rubber & Plastics News, which like Au-tomotive News is published by Crain Com-munications—had his first byline in theauto industry newspaper on Nov. 14, 1955.His last was posted on the website au-tonews.com on Sept. 18 of last year, amonth after he turned 87.

In between, he enhanced hundreds of

columns, news stories and editorials with apeerless writing touch, mentored genera-tions of reporters and editors, and providedvaluable perspective on the industry’s tri-umphs and failures.

He created what have become staples ofindustry scorekeeping, including an annu-al dealer census and tallies of auto makers’sales per dealership.

And he enlivened the Automotive Newsnewsroom with barbed comments aboutsuch things as recalcitrant computers andauto makers that failed to see the folly ofabandoning cars in favor of SUVs.

To his colleagues he was the ever-gra-cious gentleman, always ready with kindwords delivered with the elegant Teahentouch. To a favorite editor temporarily awayfrom the office, he wrote: “I await the daythat you are again the brow-beating domi-natrix we all love.”

For her help in his epic battles with “theabomination”—the newspaper’s computersystem—he annually awarded her a box ofpremium chocolates.

Teahen was inducted into the MichiganJournalism Hall of Fame, received a Distin-guished Service Citation from the Automo-tive Hall of Fame and a Lifetime Achieve-ment Award from the Detroit Chapter ofthe Society of Professional Journalists. Jack Teahen

OBITUARY

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