Textile and Paper Chemistry and Technology

18 Improved Polyester Radial Tire Yarn for Material,

Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on March 11, 2018 | https://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0049.ch018

Pollution, and Energy Savings MICHAELJ.COLLINS Celanese Fibers Marketing Co., Charlotte, NC

A new polyester tire yarn which significantly reduces energy, pollution, and dip costs during fabric treating has been developed for carcass reinforcement of passenger radial tires. This product, designated T-865, i s adhesive activated and dimensionally stabilized. It is designed to give good adhesion to rubber with conventional RFL dipping at temperatures as low as 420°F. Standard, non-adhesive activated polyester typically requires either an isocyanate pre-dip or RFL dip additives to achieve acceptable adhesion. These adhesion promoters are expensive, require high treating temperatures and, in most cases, produce polluting by-products. The combination of adhesive activation and dimensional stability offers the potential for significant energy savings by allowing the use of lower treating temperatures and fewer zones. The dimensional stability of this product allows standard modulus -shrinkage properties to be achieved at these lower treating temperatures. One zone treatments at temperatures of 420°F are feasible, resulting in energy savings of well over 50%. This product can also be utilized to obtain improved radial tire uniformity, using standard treating temperatures. Review of Standard Polyester Tire Cord Treating General Description. High tenacity polyester fiber i s sold to the tire industry in yarn form. This yarn i s single and ply twisted into specific cord constructions and woven into fabric. The fabric is adhesive dipped and heat treated under controlled conditions of temperature, time, and tension. The specific treating conditions used are determined by the adhesive system and the final fabric physical properties which are required. Normally, polyester requires treating temperatures in the range of 465 480°F to achieve desired adhesion levels and shrinkage/elongation (heat set) properties. Standard, non-adhesive activated polyester requires special dip systems to obtain satisfactory adhesion. Rayon and nylon f i bers have traditionally used resorcinol - formaldehyde latex dip 280 Arthur; Textile and Paper Chemistry and Technology ACS Symposium Series; American Chemical Society: Washington, DC, 1977.


18.

COLLINS

Improved

Polyester

Radial

Tire

Yarn

281

systems (RFL) f o r adhesion t o rubber. The r e s o r c i n o l formaldehyde (RF) forms a r e s i n network which p r o v i d e s adhesion between the f i b e r s u r f a c e and the l a t e x . The l a t e x rubber adhesion i s then formed d u r i n g the a c t u a l c u r i n g o f the t i r e . Because p o l y e s t e r has a much l e s s r e a c t i v e s u r f a c e and fewer s i t e s a v a i l a b l e f o r hydrogen bonding than rayon or n y l o n , standard RFL d i p s do not g i v e good adhesion w i t h non-adhesive a c t i v a t e d p o l y e s t e r . S p e c i a l d i p systems were developed f o r p o l y e s t e r to overcome t h i s problem. These systems i n v o l v e d e i t h e r an i s o c y a n a t e p r e - d i p o r RFL d i p a d d i t i v e s used to achieve a c c e p t a b l e adhesion. The most commonly used dip systems are d e s c r i b e d i n more d e t a i l . D-417/RFL Dip System. The D-417/RFL ( l ) d i p system i s a two dip system developed s p e c i f i c a l l y f o r p o l y e s t e r by DuPont. The p r e - d i p , designated D-417, c o n t a i n s an epoxy and a phenol b l o c k e d i s o c y a n a t e , Hylene MP, ( F i g u r e 1 ) , which i s d i s p e r s e d i n water. Dip s o l i d s t y p i c a l l y range from 4 to 6% w i t h a t o t a l dip pick-up o f 1 to 2.5%. A f t e r the f a b r i c i s dipped i n the D-417 bath, i t i s cured a t high temperature to unblock and a c t i v a t e the i s o c y a nate. Curing temperatures o f 460°F are normally r e q u i r e d t o achieve a c c e p t a b l e adhesion. During c u r i n g , phenol i s l i b e r a t e d as a by-product. Phenol represents 43% o f the t o t a l weight o f Hylene MP. At a dip pick-up l e v e l o f 2.0%, t h i s means t h a t approximately .8 l b s o f phenol i s l i b e r a t e d per 100 l b s o f t r e a t e d f a b r i c . O b v i o u s l y , t h i s phenol represents a s i g n i f i c a n t p o l l u t a n t which must be managed i n u s i n g t h i s system. The D-417/RFL was one o f the o r i g i n a l systems developed f o r p o l y e s t e r and has been used f o r many y e a r s . I t g i v e s e x c e l l e n t i n i t i a l adhesion; but i t i s expensive, p o l l u t a n t , and very s e n s i t i v e to t r e a t i n g c o n d i t i o n s . RFL Dip + A d d i t i v e s . Two RFL d i p a d d i t i v e s which a r e most commonly used with p o l y e s t e r are chemicals designated N3 (2) and H7 ( 3 ) . These substances, a g a i n , were designed s p e c i f i c a l l y f o r p o l y e s t e r adhesive t r e a t i n g . Both a d d i t i v e s are designed to improve the adhesion between the RF r e s i n and the f i b e r s u r f a c e to achieve good o v e r a l l adhesion. F a i r l y high l e v e l s o f these a d d i t i v e s (20 - 30%) and high t r e a t i n g temperatures (465 - 480°F) are r e q u i r e d to o b t a i n s a t i s f a c t o r y r e s u l t s . Other a d d i t i v e s used w i t h RFL dips f o r p o l y e s t e r i n c l u d e c e r t a i n i s o c y a n a t e s ( 4 ) . In a l l cases, these a d d i t i v e s are very expensive compared to the RFL dip and add s i g n i f i c a n t l y to the overa l l d i p c o s t . A l s o , each o f these a d d i t i v e s generate p o l l u t a n t by-products during f a b r i c heat treatment which, i n some cases, present major p o l l u t i o n c o n t r o l problems. T r e a t i n g C o n d i t i o n s . As i n d i c a t e d e a r l i e r , a f t e r the f a b r i c i s adhesive dipped, i t i s heat t r e a t e d under c o n d i t i o n s o f cont r o l l e d temperature, time, and t e n s i o n . These c o n d i t i o n s are designed t o achieve s p e c i f i c adhesion l e v e l s and f a b r i c p h y s i c a l properties. Typical treating conditions required for polyester are shown as f o l l o w :

Arthur; Textile and Paper Chemistry and Technology ACS Symposium Series; American Chemical Society: Washington, DC, 1977.

TEXTILE AND PAPER CHEMISTRY AND TECHNOLOGY

POLYESTER

TIRE

CORD

YARN I

SINGLE PLY

FIRST

FIRST

CORD WEAVE

J


GREIGE FABRIC I

ADHESIVE DIP

I

HEAT SET

TREATED CALENDER with RUBBER

FABRIC I

J

CALENDERED

FABRIC

TIRES

GENERAL DESCRIPTION 1. 2. 3. 4.

System Developed By DuPont D-417 Predip - Isocyanate (Hylene M P ) & Epoxy Hylene MP Activates ( U n b l o c k s ) at 4 6 5 ° F Hylene MP Liberates 43% Phenol When Activated Figure!.

D-417 RFL dip system.

Hylene

MP.


18.

COLLINS

Improved Polyester Radial Tire Yarn


Temperature (°F) Time (Seconds) S t r e t c h (%)

Zone Ί 300 50 +2

283

Zone 2 Zone 3 "365 465" 50 50 0 -2

The f a b r i c goes from the f i r s t d i p tank i n t o Zone 1 where i t must be d r i e d . Zones 2 and 3 a t the h i g h e r temperatures are used t o heat s e t the f a b r i c to reduce shrinkage and o b t a i n the d e s i r e d dimensional s t a b i l i t y . The s t r e t c h - r e l a x c o n d i t i o n s o r t e n sions are a d j u s t e d to achieve s p e c i f i c modulus/shrinkage proper t i e s a t given t r e a t i n g temperatures. The r e l a t i o n s h i p between t r e a t i n g temperature and shrinkage f o r standard p o l y e s t e r i s shown i n F i g u r e 2. The modulus/shrinkage r e l a t i o n s h i p at a given t r e a t i n g temperature i s shown i n F i g u r e 3. G e n e r a l l y , t r e a t e d cord shrinkage must be i n the range o f 7 - 8% @ 350°F, thus r e q u i r i n g minimum t r e a t i n g temperatures o f 460°F f o r standard p o l y ester. Most t r e a t i n g u n i t s p r e s e n t l y use n a t u r a l gas as the primary energy source. R e c e n t l y , some o f these u n i t s have been m o d i f i e d to use e i t h e r f u e l o i l o r n a t u r a l gas due to the concern about a v a i l a b i l i t y o f n a t u r a l gas. A l s o , due t o concerns about energy a v a i l a b i l i t y and c o s t , most o f these companies have i n i t i a t e d major e f f o r t s aimed at energy c o n s e r v a t i o n i n t h e i r f a b r i c t r e a t ing p r o c e s s e s . O b v i o u s l y , t o t a l energy r e q u i r e d f o r f a b r i c t r e a t ing i s a f u n c t i o n o f t r e a t i n g temperatures and dwell times. With standard p o l y e s t e r and e x i s t i n g adhesive systems, t h e r e i s very l i t t l e f l e x i b i l i t y i n terms o f energy c o n s e r v a t i o n . T-865 P o l y e s t e r T i r e Cord General D e s c r i p t i o n . A new p o l y e s t e r t i r e yarn which s i g n i f i c a n t l y reduces energy, p o l l u t i o n , and d i p c o s t s d u r i n g f a b r i c t r e a t i n g has been developed f o r c a r c a s s r e i n f o r c e m e n t o f passen ger r a d i a l t i r e s . T h i s product, d e s i g n a t e d T-865, i s adhesive a c t i v a t e d and d i m e n s i o n a l l y s t a b i l i z e d . I t i s a s u r f a c e a c t i v a ted product designed t o g i v e good adhesion t o rubber w i t h con v e n t i o n a l RFL d i p p i n g a t temperatures as low as 420 F. The com b i n a t i o n o f adhesive a c t i v a t i o n and dimensional s t a b i l i t y o f f e r s the p o t e n t i a l f o r s i g n i f i c a n t energy savings by a l l o w i n g the use o f lower t r e a t i n g temperatures and fewer t r e a t i n g zones. The dimensional s t a b i l i t y o f t h i s product allows standard modulus/ shrinkage p r o p e r t i e s t o be achieved a t these lower t r e a t i n g tem peratures ( 5 ) . One (1) zone treatments a t temperatures o f 420°F are f e a s i b l e r e s u l t i n g i n energy savings o f w e l l o v e r 50%. T-865 t r e a t i n g i s d e s c r i b e d i n more d e t a i l below. "RFL Only" Dip System. T-865 p o l y e s t e r i s s u r f a c e a c t i v a t e d t o e l i m i n a t e the need f o r the adhesion promoters which are r e q u i r e d with s t a n d a r d p o l y e s t e r . The recommended RFL d i p formu l a t i o n i s shown i n Table I ( 6 ) . As i n d i c a t e d , i t i s b a s i c a l l y a standard RFL d i p s i m i l a r t o those used with rayon and n y l o n . 9


284

TEXTILE AND PAPER CHEMISTRY AND TECHNOLOGY T Y P I C A L P O L Y E S T E R T I R F CORD T R E A T I N G S Y S T E M S

SYSTEM NUMBER


DIP

(1)

TEMP.

(°F)

TIME

(SEC.)

STRETCH

DIP

1

2

D-417

RFL + ADDITIVES

465

300

50

50

+1

+1

(%)

(2)

RFL

ZQNL2 TEMP.

(°F)

300

470

TIME

(SEC.)

50

50

0

0

STRETCH

CD

ZONE 3 TEMP.

(°F)

440

470

TIME

(SEC.)

50

50

-1

-1

STRETCH

Figure

2.

Shrinkage

(%)

vs. treating

temperature

for standard

polyester


Improved

COLLINS

Polyester

Radial

Tire

Yarn

8


ο ο

"'••ft

7

10 CO

6

LU

5 4

Ζ QC Χ LU LU QC

3 2 1 3.0

E Figure 3.

E

10

1 0

vs. shrinkage

7.0

(%)

far standard

TARLE

RFCOMMFNDED RFI

RESIN

6.0

5.0

4.0

polyester

I

BIP

FORMULATION

SOLUTION 365.0

WATER NAOH (50%)

2.6

RESORCINOL

16.6

FORMALIN (37%) TOTAL

AGE

FOR 1 3 / 4 HR. a

398.9

75°F

LATEX

V I N Y L P Y R I D E N E T Y P E (GENTAC 41%) SBR T Y P E ( P L I O L I T E

2000

215.0 53.8

41%)

AfiF D I P ?A HRS. B E F O R E USING

DESCRIPTION DIP

SOLIDS

- 20%

F/R

RATIO

-

RESIN/LATEX VP L A T E X / S B R DIP

1.2:1

- .20 LATEX -

SHELF L I F E

80/20

- TWO ( 2 ) WEEKS



286

TEXTILE AND PAPER CHEMISTRY AND TECHNOLOGY

G e n e r a l l y , t h e RFL f o r m u l a t i o n i s n o t c r i t i c a l although lower F/R r a t i o (1.2:1) and non-ammoniated dips a r e recommended. In some c a s e s , i t may be necessary t o o p t i m i z e the d i p f o r m u l a t i o n f o r the p a r t i c u l a r rubber compound being used t o o b t a i n good r e s u l t s . The r e l a t i o n s h i p between d i p pick-up and adhesion i s shown i n Figure 4. Based on trade e x p e r i e n c e , a d i p pick-up l e v e l o f 5 t o 6% i s recommended t o achieve the optimum combination o f adhesion and f a t i g u e p r o p e r t i e s . O b v i o u s l y , h i g h e r p i c k up l e v e l s can be used i f h i g h e r adhesion i s r e q u i r e d . T r e a t i n g C o n d i t i o n s . The s e n s i t i v i t y o f adhesion t o t r e a t i n g temperature f o r T-865 u s i n g an "RFL o n l y " d i p i s shown i n F i g u r e 5. As i n d i c a t e d , adhesion i s very i n s e n s i t i v e t o t r e a t i n g temperature i n the range 420 t o 480°F. T h i s means t h a t good adhesion can be achieved w i t h T-865 a t t r e a t i n g temperatures as low as 420°F as compared t o standard p o l y e s t e r t r e a t i n g which norm a l l y r e q u i r e s much h i g h e r temperatures (465 - 480°F) t o o b t a i n good adhesion. F i g u r e 6 shows a comparison o f shrinkage ( a t cons t a n t modulus) versus t r e a t i n g temperature f o r T-865 and standard p o l y e s t e r . T h i s comparison shows t h a t , due t o the improved d i mensional s t a b i l i t y o f T-865, standard shrinkage l e v e l s can be achieved a t much lower t r e a t i n g temperatures (410°F) than a r e norm a l l y r e q u i r e d f o r n o n - s t a b i l i z e d p o l y e s t e r . Thus, the combinat i o n o f adhesion a c t i v a t i o n and improved dimensional s t a b i l i t y a l l o w T-865 t o be t r e a t e d a t temperatures as low as 420°F w h i l e s t i l l a c h i e v i n g adhesion and p h y s i c a l p r o p e r t i e s ( s h r i n k a g e / modulus) which a r e e q u i v a l e n t t o standard p o l y e s t e r t r e a t e d a t h i g h e r temperatures (465 - 480°F). A l s o , s i n c e T-865 r e q u i r e s much l e s s heat t o achieve standard p r o p e r t i e s , the number o f t r e a t i n g zones can be reduced. At t r e a t i n g temperatures as low as 420°F, i t a c t u a l l y becomes f e a s i b l e t o e l i m i n a t e the d r y i n g zone and use a one (1) zone treatment. Comparative t r e a t i n g s y s tems f o r T-865 and standard p o l y e s t e r are shown i n Table I I . Advantages o f T-865 T r e a t i n g . There are three major advantages o f T-865 t r e a t i n g versus standard p o l y e s t e r . These advantages are savings i n energy, p o l l u t i o n , and m a t e r i a l c o s t s , each o f which are d i s c u s s e d i n more d e t a i l below. M a t e r i a l Savings. T-865 t i r e c o r d t r e a t i n g o f f e r s s i g n i f i cant d i p c o s t savings by e l i m i n a t i n g the need f o r the adhesion promoters normally r e q u i r e d with p o l y e s t e r . These adhesion promoters are very expensive r e l a t i v e t o standard RFL d i p and thus s i g n i f i c a n t savings can be r e a l i z e d by e l i m i n a t i n g t h e i r use. A d i p c o s t comparison o f "RFL o n l y " system versus the most commonly used systems with standard p o l y e s t e r i s shown i n Table I I I . As i n d i c a t e d , d i p c o s t savings o f 3

Textile and Paper Chemistry and Technology

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