Additives Value beyond chemistry

Enhanced Processing and Service Life for Polyurethane Products

Additives for Polyurethane

1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Polymer Degradation and Stabilization . . . . . . . . . . . . . . . . . . . . . . . .4Thermo-oxidative Degradation . . . . . . . . . . . . . . . . . . . . . . .4

Antioxidants Interrupt the Degradation Process . . . . . . . . . . .5

Photodegradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Light Stabilizers Counter Photodegradation . . . . . . . . . . . . . .7

Additives for Polyurethane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Thermoplastic Polyurethane (TPU) . . . . . . . . . . . . . . . . . . . .9

Reaction Injection Molded (RIM) Polyurethane . . . . . . . . . . .12

Polyurethane Foams . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Polyurethane Adhesives and Sealants . . . . . . . . . . . . . . . . .20

Polyurethane Fiber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Additives Data Bank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24Chemical Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Chemical Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

FDA Clearance Summary . . . . . . . . . . . . . . . . . . . . . . . . . .28

Solubility Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Table of Contents

2

3Polyurethanes are among the most versatile polymers.They are used in a wide variety of applications includingadhesives, sealants, coatings, fibers, reaction-injectionmolded components, thermoplastic parts, elastomers andboth rigid and flexible foams.

Polyurethanes offer an impressive range of performancecharacteristics and the use of appropriate stabilizers canextend the service life of polyurethane products. Selectingthe best stabilization system depends on specific produc-tion conditions, end-use environment and a knowledge ofthe fundamental degradation mechanisms of thepolyurethane components.

Degradation of both the polyol and urethane componentswill cause changes in the physical or mechanical propertiesof the polyurethane. Urethanes are susceptible to degrada-tion by free radical pathways induced by exposure to heator ultraviolet light. The use of primary antioxidants, suchas Irganox, suppresses the formation of free radicalspecies and hydroperoxides in polyols both during storageand conversion. UV absorbers and hindered amine stabilizers, such as Tinuvin and ChimassorbTM, protectpolyurethanes from UV light-induced oxidation.

Ciba Additives offers a variety of additives for improvingthe processing and service life of polyurethane products.For detailed information about individual products, specificapplication or performance requirements, please contactyour local Ciba technical representative or regional agent.

Introduction

4RH (Polymer)

ROORO + HO

Reacts with primaryantioxidants(hindered phenols,hindered aminestabilizers)

R

Reacts with secondary antioxidants(phosphites, hydroxylamines)to yield inactive products

Reacts withanother RH

Reacts withanother RH

Oxygen

Energy,Catalyst residues,Light

Cycle II Cycle I

Energy,Catalyst residues,Light

React with primaryantioxidants(hindered phenols,hindered aminestabilizers)to yield inactive products(ROH and H2O)

RROOH +

Carbon centeredradicals react withLactone basedstabilizers

R Alkyl radicalsRO Alkoxy radicalsROO Peroxy radicals Path of degradationROOH Hydroperoxide Path of stabilization

Polymer Degradation and Stabilization

Thermo-oxidative DegradationPolyurethanes, like other organic materials,react with molecular oxygen in a processcall autoxidation. This degradationprocess results in product discoloration andloss of physical properties.

Autoxidation may be initiated by heat, highenergy radiation (UV light), mechanicalstress, catalyst residues, or through reactionwith other impurities. Free radicals (Figure 1) are generated which react rapidlywith oxygen to form peroxy radicals. Theseperoxy radicals may further react with thepolymer chains leading to the formation ofhydroperoxides (ROOH). On exposure toheat or light, hydroperoxides decompose toyield more radicals that can reinitiate thedegradation process.

Figure 1. Polymer Degradation and Stabilization

Microwave Scorch Test. Sample on rightstabilized with Irganox antioxidants showmuch less exotherm discoloration thanthe other commercial system on the left.See complete test procedure on page 16.

5Antioxidants Interruptthe Degradation ProcessAntioxidants interrupt the degradation processin different ways according to their structure.The major classifications of antioxidants are listed below.

Primary Antioxidants, mainly acting in Cycle Iof Figure 1 as chain-breaking antioxidants, aresterically hindered phenols. Primary antioxidantsreact rapidly with peroxy radicals (ROO) tobreak the cycle. Irganox1010, Irganox 1076,Irganox 1098, Irganox 1135 and Irganox 245are examples of primary antioxidants.

Secondary arylamines, another type of primaryantioxidant, are more reactive toward oxygen-centered radicals than are hindered phenols.Synergism between secondary arylamines and hindered phenols leads to regeneration ofthe amine from the reaction with the phenol.Irganox 5057 is an example of a secondary arylamine.

Secondary Antioxidants, acting in Cycle II ofFigure 1, react with hydroperoxide (ROOH) toyield non-radical, non-reactive products and are,therefore, frequently called hydroperoxidedecomposers. Secondary antioxidants are par-ticularly effective in synergistic combinationwith primary antioxidants. Phosphite stabilizers,Irgafos 168 (a component of Irganox B Blends),Irgafos 12 (a component of Irganox LC Blends)and Irgafos 38 (a component of Irganox LMBlends) are secondary antioxidants.

Multifunctional Antioxidants have specialmolecular design and optimally combine primaryand secondary antioxidant functions in onecompound. Hindered amine stabilizers (HAS)and dialkylhydroxylamine are prime examples ofmultifunctional antioxidants. Irganox 565 isanother example of a multifunctional antioxidant.

Hindered amine stabilizers can in some casesprovide radical trapping effectiveness similar tohindered phenols. Traditionally used as light stabilizers, hindered amine stabilizers can alsocontribute to long-term thermal stability.Examples are Tinuvin 765, Tinuvin 123,Tinuvin 622 and Tinuvin 770.

Dialkylhydroxylamines, a component of FS Systems, function as radical traps as well ashydroperoxide decomposers and reducingagents.

Lactones, a component of our Irganox HP prod-ucts, function as carbon-centered radical scav-engers which inhibit autoxidation as soon as itstarts and are further capable of regeneratingphenolic antioxidants to provide new levels ofoverall processing stability.

Oxygen-Centered Radical TrapsOO OOH

Ar2NH +-O-CH-CH2 Ar2N + -O-CH-CH2

Ar2N + ArOH Ar2NH + ArO

J. Pospisil in Developments in PolymerStabilization, Vol. 1, Ch, 1, ed. G. Scott, AppliedScience Publ., London, 1979.

6Photodegradation is really two distinct pro-cesses. The first is photolysis, a complex processoccurring in several steps, which involves theabsorption of UV radiation, followed by the formation of free radicals due to the breaking ofthe absorbing species molecular bonds. Thesecond is autoxidation. Here, the free radicalsformed during photolysis interact with oxygento form peroxy radicals.

There are five separate steps during photodegra-dation. In the following schematic, R representsthe polymer or UV absorbing component.

Step 1

R R*

Here, the polymer absorbs UV radiation. Theenergy from the absorbed UV radiationexcites the absorbing species (either polymermolecules or impurities) and raises them to ahigher energy level (R*). These excited statemolecules are very reactive and may undergo a wide range of processes. Two commonprocesses are returning to the ground state orhomolytic bond cleavage.

Step 2

R* R

If the molecule cannot be brought to its groundstate, homolytic bond cleavage and the forma-tion of free radicals (R) will occur.

O2 R'HRR*RROOROOHRO+OHStep 1 Step 2 Step 3 Step 4 + Step 5

R'Photodegradation

Step 3

O2R ROO

In Step 3, the free radicals formed during pho-tolysis readily react with oxygen to form peroxyradicals. This is called autoxidation.

Step 4

R'H

ROO ROOH + R'

In Step 4, the peroxy radicals attack the poly-mer backbone (R'H) via hydrogen abstraction,forming hydroperoxides and more free radicals.These free radicals (R') again readily react withoxygen in Step 3 to form additional peroxyradicals.

Step 5

ROOH RO + OH

Finally in Step 5, the hydroperoxides, which arevery unstable to both UV radiation and heat,fragment and form additional free radicals. Asthe processes continue, more and more molecu-lar bonds break, leading to a deterioration ofthe desired properties.

Photolysis Autoxidation

7Light Stabilizers CounterPhotodegradationPolyurethanes are subject to degradation whenexposed to ultraviolet light from natural and/orartificial sources. Degradation results in discol-oration and/or loss of physical properties.

The main classes of light stabilizers are:

Ultraviolet Light Absorbers (UVAs)

Hindered Amine Light Stabilizers (HALS)

During Step 1

UV absorbers protect against photodegradationby competing with the polymer for absorptionof ultraviolet light.

As shown in Figure 2, the excitation energy ofUV absorbers is rapidly and efficiently deacti-vated by the process of tautomerization.

An ideal UVA should be very light stable, andshould have high absorption over the UV rangefrom 290 to 400 nanometers. Ciba Additives pioneered the development of benzotriazoleultraviolet light absorbers. Tinuvin P, Tinuvin 213,Tinuvin 326, Tinuvin 327, Tinuvin 328, andTinuvin 571 belong to this class of UVAs.

During Step 3

Hindered amine light stabilizers (HALS) repre-sent an alternative chemistry in light stabiliza-tion technology. Several theories have beenadvanced to explain the mechanism of stabiliza-tion by HALS, of which the most widely heldinvolves efficient trapping of free radicals withsubsequent regeneration of active stabilizer moieties, represented in Figure 3. Examples ofHALS are Tinuvin 123, Tinuvin 144, Tinuvin 622,Tinuvin 765, Tinuvin 770, and Chimassorb 944. R'OH + R=O

R

R'OO

N-ORN-ON-CH3[O]

N

O O

RO

R'

Figure 3. Regenerative Mechanism of HALS*

Figure 2. Schematic of Tautomerism

Molecule A absorbs UV energy, resulting in an electronicrearrangement to form molecule B which, through the dissi-pation of heat energy, reverts to the original form, moleculeA. This process is repeated indefinitely.

H O

N

N+

UV-

N

N

N

N

H O

* P.P. Klemchuk, M.E. Gande, Polymer Degradation and Stabilization,1988, 22, 241; 1990, 27, 65

(A) (B)

8Ciba Additives for Polyurethanes

Irganox 245Irganox 1010Irganox 1076Irganox 1098Irganox 1135Irganox 5057

Tinuvin PTinuvin 213Tinuvin 326Tinuvin 327Tinuvin 328Tinuvin 571

Tinuvin 123Tinuvin 144Tinuvin 622Tinuvin 765Tinuvin 770

0.0

0.2

0.4

0.6

0.8

1.0

270 290 310 330 350 370 390 410

Wavelength (nm)

A

Tinuvin 327Tinuvin 328Tinuvin 571Tinuvin 213

60 110Temperature (C)

160 210 260 310 360

Weight loss (%)

0

20

40

60

80

100

BHTIrganox 1135Irganox 5057Irganox 1076Irganox 245Irganox 1010

Additives for Polyurethanes

Antioxidants

UVAs

HALS

Figure 4. UV Absorption Spectra (20 mg/l Ethyl Acetate) Figure 5. Weight Loss of Antioxidants TGA, 20C/min (air)

Uvitex OBOptical Brightener

9Thermoplastic Polyurethane (TPU)

Applications

Thermoplastic polyurethanes are among themost versatile elastomeric materials. During themanufacture of TPUs, processing stabilizers suchas Irganox 245, Irganox 1010 or Irganox 1098are used to protect the polymer from degrada-tion. Due to their versatility, TPUs are used in awide range of applications that may requireboth thermal and/or light stability.

For enhanced end-use stability, thermal stabi-lizers including Irganox 1135, Irganox 245 or Irganox 1010 are used. Light stability can be achieved using hindered amines alone (Tinuvin 765 or Tinuvin 123) or in conjunctionwith UV absorbers (Tinuvin 571 or Tinuvin 213).Also available is Tinuvin B75, a liquid blend of all three stabilizer functionalities - antioxidant(Irganox 1135) plus hindered amine (Tinuvin 765) plus UV absorber (Tinuvin 571).Tinuvin B 75 provides long term stability, ease ofhandling and outstanding end-use performance,all in one liquid product.

To accommodate TPU processors, both liquidand solid stabilizers are available.

10

Table 2. Ovenaging of Thermoplastic Polyurethane

Days to YI=20At 120C

Unstabilized 30.3% Irganox 1010 6.50.3% Irganox 245 6.5

Sample: 2 mm injection molded dumb-bellsTest Criterion: Ovenaging time at 120C till

discoloration increases 20 Yellowness-Index units.

Table 1 shows the impact oxidation has onthe initial color of polyurethane materials.Oxidation is measured by the peroxide con-centration in the polyol. The resulting colordevelopment is measured by YellownessIndex of the final polyurethane.

Table 1. Effect of Peroxide Concentration on Polyurethane* Initial Color

Peroxide Conc. PUR(ppm in the polyol) Yellowness Index

1 5

25 13

50 42

100 52

* Shoe sole formulation, non-pigmented, PUR is polyether based.

100 20 30 40E

0.5% Tinuvin 327

0.5% Tinuvin 328

0.5% Tinuvin 571

Control

Figure 6. Discoloration of TPU Plaques (1.5 mm)

Exposure: 500 Hours Light Exposure. Dry Xenon CI 35: b.P. TC = 63C, 0.35W/m2 Irradiance

Base Stabilization: 0.25% Irganox 1135/0.25% Tinuvin 765

200 40 60 80% Retention

Control0.5% Tinuvin 571

Elongation

Tensile Strength

100 120

0.5% Tinuvin 3280.5% Tinuvin 327

Figure 7. Tensile Strength and Elongation Retention of TPU Plaques (1.5 mm)

Exposure: 500 Hours Light Exposure. Dry Xenon CI 35: b.P. TC = 63C, 0.35W/m2 Irradiance

Base Stabilization: 0.25% Irganox 1135/0.25% Tinuvin 765

Figures 6 and 7 demonstrate the dramaticimpact of stabilizers in thermoplasticpolyurethanes. All formulations include Irganox 1135 antioxidant and Tinuvin 765 hindered amine stabilizer. After 500 hours Dry Xenon exposure, all three UV absorbers(Tinuvin 571, Tinuvin 328, and Tinuvin 327)show significant protection of color andretention of original elongation and tensileproperties.

Antioxidants are needed to protect TPU during processing. Both Irganox 1010 andIrganox 245 have been used in commercialproduction successfully for many years. Thestabilized TPU samples were able to sustaintwo times longer ovenaging exposure thanthe sample without an antioxidant (Table 2).

11

0 100 200 300 400 500

Unstabilized

0.3% Tinuvin 328

0.3% Tinuvin 213

0.4% Tinuvin 328+ 0.4% Tinuvin 765

0.4% Tinuvin 213+ 0.4% Tinuvin 765

Hours to delta YI of 20

37

174

132

269

443

Figure 8. Accelerated Weathering, TPU Film

Sample: TPU Film, 6 mmExposure: Xenotest 450

Substantial improvement in performance can beachieved using a UVA/HALS combination vs UVAalone, as demonstrated in Figure 8.

Table 3. Comparison of Light Stability of Aromatic and Aliphatic Polyurethane FilmXenon Weather-Ometer Exposure

Hours to 50% Retention of Elongation

Aromatic Aliphatic

Control 170 3,200

0.5% Tinuvin P + 390 4,5000.5% Irganox 1010

0.5% Chimassorb 944 900 11,500

0.5% Tinuvin 622 670 11,500

0.5% Tinuvin 765 850 13,900

Table 4. Effect of Nitrogen Oxides* on Polyester-Based Polyurethane

Yellowness IndexAfter 334 Hours

Unstabilized 53

1% Tinuvin P 50

1% BHT 34

1% Tinuvin 770 15

1% Tinuvin P + Tinuvin 770 (1:1) 13

1% Tinuvin 770 + Irgafos 168 (1:1) 10

1% Tinuvin 765 9

* PUR plaques were maintained in an enclosed chamberwith nitrogen oxides present for 334 hours at 60C.PUR is a non-pigmented shoe sole type formulation.

Table 3 compares the light stability of aromaticvs. aliphatic based polyurethanes. Although sta-bilizers do provide some improvement in lightstability for aromatic polyurethane, light stabiliz-ers are particularly effective in aliphaticpolyurethane.

During storage and end use, TPUs can be exposed to nitrogen oxides that may cause thepolymer to discolor. This discoloration can beminimized using a hindered amine (Tinuvin 765or Tinuvin 770) or a combination of stabilizers asshown in Table 4.

12

0 250

Time (Hours)

500 750 1000

E

0

3

6

9

12

Control1.5% Tinuvin B 751% Irganox 1010+1% Tinuvin 770+1% Tinuvin P

15

Figure 9. Light Stability of Black RIM Polyurethane Plaques (2 mm)

Test Criterion: Discoloration after WOM CI 65: b.P. TC = 63, r.H. = 60%

Reaction Injection Molded (RIM)PolyurethanePolyurethane parts can be made by the RIM(reaction injection molding) process. Raw materi-als are injected into a mold where the polymer-ization occurs. Depending on the end use of theproduct, enhanced light or long-term thermalstability may be required. In particular, automo-tive parts have stringent performance require-ments for which a combination of UV absorbers(Tinuvin 571, Tinuvin 213, Tinuvin 328), hin-dered amine stabilizers (Tinuvin 765, Tinuvin123, Tinuvin 770), and/or antioxidants (Irganox1135, Irganox 1010, Irganox 245) are used.

Figure 9 shows the strong performance of UVabsorbers with hindered amine stabilizers andantioxidants in a black PUR RIM exposed in theWeather-Ometer.

13

50 100

Exposure Time (hours)

150 200 3000

20

40

60

70

250

Yellowness Index

50

30

10

Unstabilized (Total conc. 0%)Irganox 245 + Tinuvin 328 + Tinuvin 765 (1% conc. 1:2:2 ratio)Irganox 245 + Tinuvin 571 + Tinuvin 765 (1% conc. 1:2:2 ratio)Irganox 1135 + Tinuvin 571 + Tinuvin 765 (1% conc. 1:2:2 ratio is

Tinuvin B 75)

20 40

Exposure Time (hours)

60 800

20

40

60

70

Unstabilized (Total conc. 0%)Irganox 245 + Tinuvin 328 + Tinuvin 765 (1% conc. 1:2:2 ratio)Irganox 245 + Tinuvin 571 + Tinuvin 765 (1% conc. 1:2:2 ratio)Irganox 1135 + Tinuvin 571 + Tinuvin 765 (1% conc. 1:2:2 ratio is

Tinuvin B 75)

Yellowness Index

50

30

10

Figure 11. PUR White Integral Foams Discoloration

Exposure: Weather-Ometer, Wet CycleBP = 45C; Wet Cycle 112/18

Figure 10. PUR White Integral Foams Discoloration

Exposure: Xenotest 450, Dry CycleBP = 45C; Relative Humidity = 65%

Figure 10 shows the reduction in yellownesswhen light stabilizers are used. Tinuvin B 75, aliquid blend of three stabilizer functionalities,provides good control of color development ina white integral skin polyurethane foam sampleeven after hundreds of hours of dry light expo-sure. Figure 11 is the sample exposed in a wetcycle. Despite the more severe conditions,Tinuvin B 75 provides excellent light stability.

14

Polyurethane Foams

Polyurethane can be foamed and shaped intoflexible, rigid and integral skin configurations.Each of these types of applications will have specific stabilizer requirements. When producingflexible slabstock foams, the exotherm from thepolyol/isocyanate reaction can cause discol-oration, called scorch, in the center of the foam.This phenomenon is most common in flexibleslabstocks because of the size of the foam. Sincepolyurethane foam is a good insulator, the interior of the foam stays hot for many hours,increasing the risk of scorching. Because of theirlimited size, rigid and integral skin foams tendnot to be as prone to scorching as flexible slab-stock foams.

Hindered phenolic antioxidants (Irganox 1076,Irganox 1135) with alkylated diphenyl amines(Irganox 5057) in the polyol provide good pro-tection against scorch. Selection of the additivepackage will be determined by a number of fac-tors including foaming technique and end-usecharacteristics. Many processors prefer Irganox1076 and Irganox 1135 due to their lowervolatility relative to BHT.

Antioxidants are used to protect the urethanefrom processing and end-use degradation andprotect polyol from oxidation during storageand transport. Many end-use applications forrigid and integral skin foams are subject to out-door exposure requiring light stabilizers to pro-vide ultraviolet protection.

15

Polyol and Flexible Polyurethane Foam Stabilization Test Methods

Polyetherpolyol Isocyanate

Analytical Determination of

Antioxidant content Peroxide formation

(long-term storage)

Differential Scanning Colorimetry DSC

Exotherm peak of oxidation reactions(effectiveness of antioxidants)

Foaming Formulation

Scorch Test

Microwave/Humidity exposure Static ALU-Block Test Dynamic ALU-Block Test

(discoloration, YI)Differential Scanning Colorimetry (DSC)

Exotherm peak of oxidation reactions(effectiveness of antioxidants)

Gasfading Test with NOx

Yellowing of foam Yellowing of textiles

a. Volatility of antioxidants b. Reactivity with NOxc. Identification of reaction products

Polyurethane Flexible Foams/Textile Staining Test

Swiss Federal Laboratories for Materials Testing and Research (EMPA)St. Gallen, Switzerland

Sample preparation

Two foam samples of each formulation areexposed for 3 hours to air containing 50 ppmand 5 ppm NOx gas respectively. The samplesare then covered with two layers of cotton textile (MOLTON), which has been previouslywashed with a softener, and wrapped with aluminium film.

Samples aging

1)The samples are put into an air-circulatingoven at 40C.

2)Another series of samples, covered with onelayer of textile, is exposed for one month inair. These samples, under exclusion of directsun radiation, are not wrapped in aluminiumfilm and not gassed.

Measurement of the textile discoloration

1)Samples gassed with 50 ppm NOx gas.The first textile layer is evaluated after 24 hours.The second textile layer is evaluated after 48 hours.

2)Samples gassed with 5 ppm NOx gas.The first textile layer is evaluated after 48 hours.The second textile layer is evaluated after 96 hours.

3)Samples exposed in air.The textile layer is evaluated after 1 month.

The textile discoloration is measured by comparing the color difference between theexposed and the unexposed textile sample.

Polyurethane Foam Test Methods

16

Microwave Scorch Test Procedure

1. A master batch is prepared containing surfactant,water and amine catalyst.

2. An appropriate amount of the master batch isadded to 150 g polyol, along with the antioxidantpackage.

3. The mixture is stirred for 10 seconds at 2600 rpm.The tin catalyst is added and the mixture is stirredfor 18 seconds at 2600 rpm. The TDI is thenadded and the mixture stirred for an additional 5 seconds at 2600 rpm.

4. The mixture is poured into an 8x8x4 cake box.Cream times are typically 9-12 seconds, and risetimes 87-94 seconds.

5. After 2 minutes 14 seconds, a 4x4 piece of thetop skin is removed. This piece is removed with a4x4 piece of cardboard supported by a pencil toa 3M double-sided Scotch Brand Tape.

6. After 5 minutes, the sample is placed inside amicrowave oven with 1 cup water in a separatecontainer, then microwaved at 50% power for 5minutes 15 seconds. This microwave time is cho-sen so that a delta E value of about 20 is obtainedfor a standard formulation (e.g. 0.40% Irganox1135 + 0.10% Irganox 5057).

17

160 170 180 190 200

Temperature (C) to reach Yellowness Index = 25

Total additive concentration = 3000 ppm

Unstabilized

BHT

Irganox 1135

BHT + Irganox 5057(ratio 2:1)

Irganox 1135 +Irganox 5057(ratio 2:1)

Unstabilized = 89C

190 195 200 205 210

Temperature (C) to reach Yellowness Index = 25

Total additive concentration = 3500 ppm

Unstabilized

Irganox 1135

Irganox 1135 +Irganox 5057(ratio 1:1)

Figure 13. Polyether Flexible Foams Stabilization

Exposure: Dynamic Heat Test, Ovenaging for 30 Minutes

Figure 14. Polyester Flexible Foams Stabilization

Exposure: Dynamic Heat Test, Ovenaging for 30 Minutes

Processing Stabilization ofPolyurethane FoamsFor polyol producers and foamers seeking lowervolatility alternatives to BHT for scorch protection,both Irganox 1135 and Irganox 1076 are excellentchoices. Irganox 1135 in combination with Irganox 5057 is the ideal liquid stabilizer system for polyurethane flexible forms. Irganox 1135 haslower volatility than BHT (see TGA data on page 8)and the liquid nature of Irganox 1135 and Irganox5057 provides ease of incorporation for liquidbased processing.

Figure 12 demonstrates the outstanding scorchprotection provided by a 2:1 ratio of Irganox 1135and Irganox 5057. A 4:1 ratio of Irganox 1076 andIrganox 5057 also provides equal performance tothe BHT system in the microwave scorch test.

In ovenaging tests carried out in an aluminum-block oven, the foam sample stabilized with 3000ppm of a combination of Irganox 1135 andIrganox 5057 at 2:1 ratio showed the longest timeto reach a Yellowness Index of 25 (Figure 13).

For polyester foam samples, ovenaging tests in analuminum-block oven show improvement in sta-bility, whether testing Irganox 1135 alone or in combination with Irganox 5057 (Figure 14).

100 20 30 40E

0.5% BHT/Irganox 5057

50

4:1 Ratio2:1 Ratio1:1 Ratio

17 18 29

2417 20

17 32 44

0.5% Irganox 1135/Irganox 5057

0.5% Irganox 1076/Irganox 5057

Figure 12. Microwave Scorch Testing of Polyether Polyurethane Cake Box Forms

Foam Formulation: 150.00 g Polyether Polyol, 1.50 g Surfactant, 6.75 g Water, 0.375 g Amine Catalyst, 0.12 g Tin Catalyst, 92.40 g Toluene Diisocyanate

18

20 4 8 10E

6

24 hours48 hours

50 ppm NOx

0.24 % Irganox 1076+ 0.06% Irganox 5057

0.7 1

0.24 % Irganox 1135+ 0.06% Irganox 5057

0.80.7

0.24 % BHT+ 0.06% Irganox 5057

8.84.4

ControlBHT-free polyether polyol 0.7

1.1

10 2 3 4E

48 hours96 hours

5 ppm NOx

0.24 % Irganox 1076+ 0.06% Irganox 5057

1.41.2

0.24 % Irganox 1135+ 0.06% Irganox 5057

0.90.9

0.24 % BHT+ 0.06% Irganox 5057

2 2.6

Control(BHT-free polyether polyol) 1.2

1.2

50 10 20 25

E15

0.24 % Irganox 1076+ 0.06% Irganox 5057 0.7

0.24 % Irganox 1135+ 0.06% Irganox 5057

1.1

0.24 % BHT+ 0.06% Irganox 5057

20.7

Control(BHT-free polyether polyol) 3

Stabilization Minimizes Textile StainingIn many applications such as automotive interiors,furniture, mattresses, carpeting and shoulder pads polyurethane flexible foams come in contact with tex-tiles. Proper stabilizers are needed to prevent scorch-ing of the foam and subsequent staining of the textile. Figures 15, 16, and 17 show how the proper selection of scorch inhibitors can minimize gas fade discoloration in textiles. Irganox 1135 or Irganox 1076 limits the discoloration associated withNOx exposure vs. BHT. Figure 15 is an air exposedsample. Whereas, the sample in Figure 16 wasexposed to 5 ppm NOx for 48 and 96 hours. Figure 17shows a more severe exposure of 50 ppm NOx.

Figure 16. Gasfade Discoloration of PUR Flexible Foam

Exposure: MOLTON Textile Ovenaging at 40C (EMPA-Test)

Figure 17. Gasfade Discoloration of PUR Flexible Foam

Exposure: MOLTON Textile Ovenaging at 40C (EMPA-Test)

50 10 20 25

E15

0.24 % Irganox 1076+ 0.06% Irganox 5057 0.7

0.24 % Irganox 1135+ 0.06% Irganox 5057

1.1

0.24 % BHT+ 0.06% Irganox 5057

20.7

Control(BHT-free polyether polyol) 3

Figure 15. Gasfade Discoloration of PUR Flexible Foam

Exposure: MOLTON Textile 1 Month Storage in Air(EMPA-Test)

19

The micrographs in Figure 18 show that a combi-nation of a hindered amine (Tinuvin 765) andultraviolet absorber (Tinuvin 328) can help protectthe cell structure of a polyether polyurethane foam

Figure 18. Surface microcrazing of Foamed Polyether Urethane

Light Stabilization of Polyurethane Foams

during exposure to light. Note that the cell structure of the stabilized foam looks similar to theunexposed foam even after l50 hours of Xenonexposure.

Exposure: 150 hours in Xenon Weather-OmeterMagnification: 1,000XStabilization System: 0.5% Tinuvin 328 + 0.5% Tinuvin 765

Exposure: 150 hours in Xenon Weather-OmeterMagnification: 1,000XUnstabilized

UnexposedMagnification: 1,000X

20

Polyurethane Adhesives and SealantsPolyurethanes are widely used for formulatingadhesives and sealants. Polyurethane adhesiveformulations include both solvent-based as wellas hot-melt. In some cases, high-performanceadhesives can replace standard mechanicalbonding methods such as nuts and bolts,screws and welding. Appropriate stabilizers areimportant in retarding degradation and main-taining physical properties for production ofhigh quality adhesives. Antioxidants, such asIrganox 1010 or Irganox 245 provide goodprocessing stability, and Tinuvin B 75, Tinuvin571, Tinuvin 765 or Tinuvin 123 can provideenhanced light stability.

Figure 19 shows that light stabilizers in combi-nation with antioxidants (Tinuvin B 75 or acombination of Irganox 245 and Tinuvin 571)provide the best overall protection in this solvent-based polyurethane adhesive.

0 1

Yellowness Index

2 3 4 5Days

0

5

10

Unstabilized0.75% Irganox 245 + Tinuvin 571, 1:20.75% Irganox 245 + Tinuvin 765, 1:20.75% Tinuvin B 750.50% Tinuvin 5710.50% Tinuvin 765

15

20

25

Figure 19. Stabilization of Solvent-Based Polyurethane Adhesives

Sample: 100p PUR, 30% MEK, 50p toluene, 10p hardnerTest Criterion: Yellowness Index after exposure in Xenon 150

21

0 500

Hours, Carbon Arc Weather-Ometer

1000 1500 2000

Degree of Crazing

0

1

2

3

4

5

Unstabilized0.50% Tinuvin 765 + Irganox 245, 1:10.75% Tinuvin 765 + Irganox 245, 2:10.75% Tinuvin 765 + Tinuvin 328 + Irganox 245, 1:1:11.50% Tinuvin 765 + Tinuvin 328 + Irganox 245, 1:1:1

Degree of Surface Crazing:0 = no crazing1 = very slight crazing2 = slight crazing

3 = moderate crazing4 = significant crazing5 = severe crazing

5 10 15 20E

1.25% Irganox 245+ Tinuvin 328+ Tinuvin 765, 1:2:2

Unstabilized

100 hours XAW exposure250 hours XAW exposure

1.25% Irganox 245+ Tinuvin 213+ Tinuvin 765, 1:2:2

1515

11 12

9 10

Figure 20. 2-Part Polyurethane Sealant with Amine Curative

Test Criterion: Degree of crazing after Carbon Arc Weather-Ometer exposure

Figure 21. Light Stabilization of Polyurethane Sealant

Delta E: ASTM D1925, D65 Illuminant, 10 observer, LAVTest Criterion: Color Development (Delta E) after Dry Xenon Arc

Weather-Ometer Exposure

In a 2-part polyurethane sealant, all stabilizationformulations show significant improvement overthe unstabilized control. After 2000 hours ofCarbon Arc exposure, the ternary blend ofIrganox 245 + Tinuvin 328 + Tinuvin 765 showsthe best performance (Figure 20).

Figure 21 shows the effects of various light stabi-lizer/antioxidant combinations for stabilizing apolyurethane sealant formulation. A 1:2:2 ratio ofIrganox 245:Tinuvin 213:Tinuvin765 results in thelowest color development after Xenon exposure.

22

Polyurethane FiberPolyurethane fiber commonly known asspandex is a synthetic elastomeric fiber. It isstrong with very high extensibility and recover-ability characteristics (elasticity) making it idealfor such textile applications as swimsuits, hosieryand fitness garments. Production of polyure-thane fiber typically requires antioxidants, suchas Irganox 245 or Irganox MD1024.

For enhanced performance demanded by consumers, light stability for exterior exposure is provided by combinations of ultraviolet lightabsorbers (Tinuvin 328, Tinuvin 234 or Tinuvin 327) with hindered amines (Tinuvin 765,Chimassorb 944 or Tinuvin 622).

Figure 22 shows a polyurethane fiber sample inwhich Tinuvin 213 and Tinuvin 234 used incombination with Tinuvin 765 showed no signsof failure even after 800 hours of dry Xenonexposure. In the same test, the unstabilizedsample failed shortly after 200 hours, while thesample with Tinuvin 328 in combination withTinuvin 765 failed after 496 hours. This failure isprobably because of the loss of Tinuvin 328 dueto its volatility. However, the same stabilizercombination of Tinuvin 328 and Tinuvin 765showed good gas fade resistance (Figure 23).

Light stability of polyurethane fibers is key formany outdoor applications. The Xenotest datain Figure 24 shows that a processing stabilizerwith a hindered amine light stabilizer (Tinuvin622) does provide some protection, but withthe addition of a UV absorber (Tinuvin 234),the time to a YI of 20 was increased by a factor of three.

23

Figure 23. Gas Fading of Polyurethane Fiber

Exposure: NOx ChamberTest Criterion: Color Development (YI) after NOx Exposure

Figure 22 Light Stabilization of Polyurethane Fiber

Test Criterion: Color Development (YI) after Dry Xenon Exposure

0 100 200 300Hours

0.5% Cyanox 1790+ 0.5% Tinuvin 622+ 0.5% Tinuvin 234

0.5% Cyanox 1790+ 0.5% Tinuvin 622

0.5% Cyanox* 1790

Control

100

300

80

78

* Cyanox is a registered trademark of Cytec Corporation

Figure 24. Stabilization of Polyurethane Fiber

Test Criterion: Time to reach YI = 20 after Xenotest 1200

200 400 600 800Hours

Yellowness Index

Unstabilized1.0% Tinuvin 328 + Tinuvin 765, 1:11.0% Tinuvin 213 + Tinuvin 765, 1:11.0% Tinuvin 234 + Tinuvin 765, 1:1

20

15

10

5

0

6.9

25

21.7*

5.4* 6

* Physical Property Failure

50 10 15 20

0 hours50 hours

1.0% Tinuvin 328+ Tinuvin 765, 1:1

0.3

6.1

Unstabilized 1.4

18.6

Yellowness Index

24

Chemical Structures of Ciba Additives for Polyurethane

Data Bank

OH

O

Irganox 245

CH2 CH2CO(CH2CH2O)32

Irganox 1010

OH

O

O

C

4

OH

CH2CH2COC18H37

O

Irganox 1076

Irganox 5057

N

H

R R1

R, R1 = H, C4H9, or C8H17and other alkyl chains.

NN OO (CH2)8CO

CO

H17C8O OC8H17

Tinuvin 123

Tinuvin 326

N

N

NHO

CICH3

N

N

NHO

Tinuvin 327

CI

NN OO CH3CH3 (CH2)8CO

CO

Tinuvin 765

CH2HO

NH

H3C

H3C

CH3

CH3

CH3

CH2CH2CH2 O CO

CO

O

Tinuvin 622

n

N

N

NHO

Tinuvin P

CH3

25

N

N

NOH

Tinuvin 213

CH2CH2CO(CH2CH2O)N

in 13% Polyethyelene glycol

O

HN OO C COO

NH(CH2)8

Tinuvin 770

N

N

NHO

C(CH3)2CH2CH3

C(CH3)2CH2CH3

Tinuvin 328

N

N

NOH

Tinuvin 571

CH3

C12H25

CH2HO

Irganox 1135

CH2 OC

O

R

R = C 7-9 Branched Alkyl Esters

SO

N

O

N

Uvitex OB

HO

Irganox 1098

CH2CH2CNH(CH2)3

2

O

NH3C

NH3C

O C

O C

C

OHCH2

C4H9

O

O

Tinuvin 144

26

Chemical Names of Ciba Additives for PolyurethanesAdditive Chemical Name CAS No.

Irganox 245 Ethylene bis (oxyethylene) bis(3-tert-butyl-4-hydroxy- 36443-68-25(methylhydrocinnamate)

Irganox 1010 Tetrakis[methylene(3,5-di-tert-butyl-4-hydroxy 6683-19-8hydrocinnamate)]methane

Irganox 1076 Octadecyl 3,5-di-tert-butyl-4-hydroxyhyrocinnamate 2082-79-3

Irganox 1098 N,N-Hexamethylene-bis 23128-74-7(3,5-di-tert-butyl-4-hydroxyhyrocinnamamide)

Irganox 1135 3,5-Di-tert-butyl-4-hydroxyhydrocinnamic acid,C7-9 125643-61-0branched alkyl esters

Irganox 5057 N-phenylbenzen amine, reaction products with 2,4, 68411-46-14-trimethylpentene

Tinuvin P 2-(2-Hydroxy-5-methylphenyl)-benzotriazole 2440-22-4

Tinuvin 123 bis-(1-Octyloxy-2,2,6,6,tetramethyl-4- piperidinyl) sebacate 129757-67-1(trivial name)

Tinuvin 144 n-Butyl-(3,5-di-tert-butyl-4-hydroxybenzyl)bis-(1,2,2,6- 6384-3-89-0pentamethyl-4piperridinyl)malonate

Tinuvin 213 Poly (oxy-1,2-ethanediyl), (,(3-(3-(2H-benzotriazol-2-yl)-5- 104810-48-2(1,1-dimethylethyl)-4-hydroxyphenyl)-1-oxopropyl)--hydroxy;

Poly (oxy-1,2-ethanediyl), (-(3-(3-(2H-benzotriazol-2-yl)-5- 104810-47-1(1,1-dimethylethyl)-4-hydroxyphenyl)-1-oxopropyl--(3-(3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphenyl)-1-oxopropoxy)

Tinuvin 326 2-(5-Chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4- 3896-11-5methylphenol

Tinuvin 327 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole 3864-99-1

Tinuvin 328 2-(2H-Benzotriazol-2-yl)-4,6-bis(1,1-dimethylpropyl)phenol 25973-55-1

Tinuvin 571 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methylphenol, 125304-04-3branched and linear

Tinuvin 622 Dimethyl succinate polymer with 4-hydroxy-2,2,6,6-tetramethyl- 65447-77-01-piperidineethanol

Tinuvin 765 bis(1,2,2,6,6,-Pentamethyl-4-piperidinyl) sebacate 41556-26-7(major component)

Tinuvin 770 bis(2,2,6,6-Tetramethyl-4-piperidinyl) sebacate 52829-07-0

Uvitex OB 2,2-(2,5-thiophenediyl)bis[5-tert-butylbenzoxazole] 7128-64-5

Physical Properties of Ciba Additives for Polyurethanes

27

Additive Molecular Melting Specific TGA, in air at 20C/min. Appearance*Weight Point (C) Gravity

at 20C Temp. at Temp at1% Wt. Loss 10% Wt. Loss

Irganox 245 587 76-79 1.14 290 330 white powder

Irganox 1010 1178 110-125 1.15 310 355 white powder

Irganox 1076 531 50-55 1.02 230 290 white powder

Irganox 1098 640 156-161 1.04 290 330 white crystalline powder

Irganox 1135 391 liquid 0.95-1.0 160 200 clear to slight yellow liquid

Irganox 5057 330 0 - 5 (liquid) 0.98 130 200 pale yellow liquid

Tinuvin P 225 128 1.38 180 205 light yellow crystallinepowder

Tinuvin 123 737.2 liquid 0.97 160 265 pale yellow liquid

Tinuvin 144 685 146-150 1.07 250 290 off-white powder

Tinuvin 213 637 (comp.1) liquid 1.17 140 280 yellow to light 975 (comp. 2) amber liquid

Tinuvin 326 316 138-141 1.32 200 245 light yellow powder

Tinuvin 327 358 154-158 1.26 180 235 pale yellow powder

Tinuvin 328 352 79-87 1.17 190 230 off-white powder

Tinuvin 571 394 liquid 1.0 170 245 pale yellow liquid

Tinuvin 622 >2500 55-70 1.18 290 320 off-white powder

Tinuvin 765 509 liquid 0.99 225 275 clear to slight yellow liquid

Tinuvin 770 481 82-86 1.05 200 260 white powder

Uvitex OB 431 196-202 1.26 300 340 yellow powder

* Many products are available in product forms other than powders 10C/min in nitrogen

20C/min in nitrogen 10C/min in air

28

Solubilities of Ciba Additives for Polyurethanes Additive Solubility @ 20C, Wt. %

Water n-Hexane Methanol Acetone Ethyl Acetate

Irganox 245 50 >50

Tinuvin P 100

Tinuvin 144

SAFETY AND HANDLINGRead and understand the respective Material SafetyData Sheet (MSDS) before handling.

Some of these products are considered to be hazardouschemicals under the OSHA Hazard CommunicationStandard (29 CFR1910.1200).

For Industrial Use Only

IMPORTANTThe following supercedes Buyers documents. SELLERMAKES NO REPRESENTATION OR WARRANTY,EXPRESS OR IMPLIED, INCLUDING OF MER-CHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. No statements herein are to be construed asinducements to infringe any relevant patent. Under nocircumstances shall Seller be liable for incidental, conse-quential or indirect damages for alleged negligence,breach of warranty, strict liability, tort or contract arisingin connection with the product(s). Buyers sole remedyand Sellers sole liability for any claims shall be Buyerspurchase price. Data and results are based on controlledor lab work and must be confirmed by Buyer by testingfor its intended conditions of use. The product(s) hasnot been tested for, and is therefore not recommendedfor, uses for which prolonged contact with mucousmembranes, abraded skin, or blood is intended; or foruses for which implantation within the human body isintended.

Ciba Specialty Chemicals Inc.

Additives

Ciba Specialty Chemicals

Head Office

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