FROM A POLYURETHANE FORMULATION INCLUDING AN

ORGANO-METALLIC CATALYST AND A TERTIARY AMINE CATALYST

This application claims the benefit of U.S. Provisional Application No. 60/017,770 filed May 15, 1997.

This invention relates to polyurethane foam. This invention particularly relates to mechanically frothed polyurethane foam useful for preparing attached cushion carpets and carpet underlays.

It is known in the art of preparing textile articles, such as carpet, to use polyurethanes as backings in various forms. For example, U.S. Patent No. 4,296,159 to Jenkmes, et al., discloses preparing a tufted or woven article having a unitary backing prepared by applying a polyurethane forming composition to the underside of the tufted or woven article. A different form of polyurethane backing is disclosed in U.S. Patent No. 5,102,714, to Mobley, et al. , wherein the polyurethane backing is a tacky adhesive. It is also known to use polyurethane foam as a cushioning textile backing, as in, for example, U.S. Patent No. 4,853,280.

There are several properties of polyurethane foams which are important for determining their usefulness in carpet applications.

These properties include but are not limited to dimensional stability, roll set, and cost. Cost is a very important property because of the highly competitive nature of the carpet industry. However, if a carpet does not properly install or rolls up after installation, the carpet is not desirable to purchasers.

One means of preparing polyurethane foams at a lower cost is to reduce the density of the polyurethane foam. Polyurethane foams are generally prepared by admixing an "A" component, a polyisocyanate, with a "B" component, an active hydrogen containing material, wherein a gas is either mechanically introduced or produced chemically, the gas forming bubbles which in turn form a cell-like structure in the cured polyurethane. The process of introducing gas into a

polyurethane formulation is known as "blowing" the formulation. The greater the amount of gas introduced into a polyurethane formulation, the lower the density of the resultant foam produced therewith. But with polyurethane foams generally, and with polyurethane foams used in carpet applications in particular, reducing foam density can also decrease or reduce the properties of the polyurethane foam which can make it a less desirable material for use in carpet applications. Therefore, it would be desirable in the art of preparing polyurethane foam for carpet applications to prepare such foam with a substantially lower density than conventional polyurethane carpet foams and yet retain the physical properties of conventional polyurethane foams which make them desirable in carpet applications.

In one aspect, the present invention is a process for preparing a polyurethane foam useful for preparing attached cushion carpets comprising admixing, with frothing, a polyurethane formulation including a polyisocyanate component, an active hydrogen containing component and a catalyst component, wherein the catalyst component includes at least two catalysts, at least one being an organo-metallic catalyst and at least one other being a tertiary amine catalyst.

In another aspect the present invention is a polyurethane foam comprising a polyurethane foam prepared by admixing, with frothing, a polyurethane formulation including a polyisocyanate component, an active hydrogen containing component and a catalyst component, wherein the catalyst component consists of at least two catalysts, at least one being an organo-metallic catalyst and at least one other being a tertiary amine catalyst.

In still another aspect, the present invention is a textile having an attached cushion comprising a textile and a polyurethane foam adherent thereto wherein the polyurethane foam is prepared by admixing, with frothing, a polyurethane formulation including a polyisocyanate component, an active hydrogen containing component and a catalyst component, wherein the catalyst component consists of at

least two catalysts, at least one being an organo-metallic catalyst and at least one other being a tertiary amine catalyst.

In one embodiment, the present invention is a polyurethane foam pad integral to a polyurethane backed textile, known as an attached cushion carpet. Preferably the polyurethane backed textile is a carpet or carpet tile having at least one polyurethane foam layer. This application of a polyurethane layer in a carpet is disclosed in, for example, U.S. Patent No. 4,853,054, to Turner, et al., which is incorporated herein by reference, and U.S. Patent No. 5,104,693 to Jenkmes, et al., also incorporated herein by reference.

In another embodiment, the present invention is a polyurethane foam for use as a carpet underlay. Carpet underlays are prepared in a manner similar to attached cushion carpet except that the polyurethane foam is applied to a substrate, usually a woven substrate prepared from polypropylene. After the polyurethane foam has cured, the underlay can be used to supplement cushioning to attached cushion carpets or as a cushioning support for unpadded carpets.

The polyurethane foams of the present invention are similar to conventionally prepared foams except that they are prepared from formulations having both an organo-metallic and an amme catalyst. The polyurethane foams so produced have sufficiently low densities to be less expensive to produce than conventional polyurethane foams for carpet applications, yet the foams have sufficient dimensional stability and roll set properties to be desirable for use in carpet applications. In addition, foam formulations of the present invention can have improved foaming properties.

The desirable combination of good physical properties and low density of the present invention results from the use of the dual catalysts of the present invention. The foam formulations used to prepare the polyurethane foams of the present invention have from 0.5 to 3 parts water per hundred parts polyol, from 0.02 to 0.25 parts organo-metallic and amine catalyst per hundred parts polyol, and from

0.4 to 2 parts surfactant per hundred parts polyol. The resultant polyurethane foams have densities of from 8 to 13 pounds per cubic foot (lb. /ft ³ ) (from 128 to 208 kg/M ³ ) . Preferably, the foams of the present invention will have a density of about 9 lb. /ft ³ (144 kg/M ³ ) . Conventional polyurethane foams useful for carpet applications, when prepared under similar conditions to the polyurethane foams of the present invention can have densities of from 13 to 16 lb. /ft ³ (from 192 to 256 kg/M ³ ) .

In formulations of the present invention, the polyisocyanate can be any polyisocyanate in an amount to provide an isocyanate index of 90 to 130. An isocyanate index is a value calculated by dividing the equivalents of isocyanate by the equivalents of isocyanate reactive components in a polyurethane formulation and then multiplying by 100. For example, in a formulation where both isocyanate and isocyanate reactive components are present in a stoichiometric amount, such a formulation would have an isocyanate index of 100. In formulations of the present invention, a polyisocyanate can be used as is or it can be first combined with less than a stochiometric amount of a polyol to form a prepolymer. If a prepolymer is used, preferably, the prepolymer is at least 30 percent by weight of the total polyisocyanate and is a soft segment prepolymer which is the reaction product of a stoichiometric excess of MDI or an MDI derivative and an isocyanate reactive organic polymer having an equivalent weight from 500 to 5,000, the prepolymer having an isocyanate group content of 10 to 30 percent by weight. The underlay is prepared by frothing the reactants with air.

Foam formulations of the present invention include a polyol component . The polyol component of the foam formulation can be any polyol or polyol mixture which can be used to prepare a foam which can withstand the rigorous physical property and handling requirements of foams used in carpet applications. For example, the polyol component can preferably be a polyol mixture having as one part of the mixture a polyol based on a C ₃ -C ₈ alkylene oxide, which has an equivalent weight of 1000 to 5000, and an internal poly(ethylene oxide) block or a

terminal ethylene oxide cap constituting 15 to 30 percent of the weight of the polyol, or mixture of such polyols wherein the polyol or mixture thereof has an average functionality of 1.8 to 2.2 The other portion of the polyol mixture is preferably a minor amount of a low equivalent weight compound having about 2 active hydrogen containing groups per molecule.

The polyurethane foams of the present invention are prepared with at least two catalysts. One catalyst is an organo-metallic catalyst, preferably an organo-tm such as: dimethyltm dilaurate, dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, dibutyl tin sulfide, dibutyltin dnsooctylmercaptoacetate, dioctyltin dnsoctylmercaptoacetate. Other cations besides tin can also be used with the present invention. For example, ferric acetylacetonate and nickel acetylacetonate can be used.

At least one other catalyst besides an organo-metallic catalyst is used to prepare the urethane foams of the present invention. The second catalyst is a tertiary amme catalyst such as triethylenediamine, acid blocked pentamethyldipropylenetnamine, 1,8- dιazabιcyclo-5,4, 0-undecene-7 unblocked or blocked with phenolic acid or 2-ethylhexanoιc acid or oleic acid or formic acid, N-methyl morpholine, N-ethyl morpholine, diethyl ethanolamine, N-cocoa morpholine, l-methyl-4-dιmethylamιnoethyl piperazine, bis (dimethylammoethyl) ether, 3-methoxy-N-dιmethylpropylamιne, N,N- dιethyl-3-dιethyl aminopropylamine, dimethylbenzyl amine.

The foams of the present invention are prepared using blowing agents. The blowing agent is preferably air, however, other gases, such as carbon dioxide, nitrogen can be used. The blowing agent is most preferably introduced into the polymer by frothing. A frother is a device which injects the blowing agent, usually compressed air, into an admixture as it agitates the admixture. Frothing a polyurethane formulation is often facilitated by using a surfactant to stabilize the foam, that is, to enhance the ability of the foam to retain blowing gasses, and to improve cell structure. One advantage of the

present invention is that foams of the present invention can have an inherently finer, more uniform cell structure. Therefore, surfactants which have maximum frothing efficiency can be used with the formulations of the present invention, regardless of their impact on the ability of the formulation to retain cell structure, so long as the surfactants are not foam destabilizers.

The foams of the present invention are prepared from formulations including fillers. The fillers are preferably aluminum oxide trihydrate (alumina), calcium carbonate, barium sulfate or mixtures thereof. Other fillers can be used instead of or in addition to the preferred fillers. The formulations used to prepare the polyurethane foams of the present invention include fillers at a level of from about 40 parts per hundred parts of polyol to about 250 parts per hundred parts of polyol.

While the above polyisocyanates, fillers, and polyols are examples of useful materials which can be included in the formulations of the present invention, other materials can also be used. The polyisocyanate component of the formulations of the present invention can be advantageously selected from organic polyisocyanates, modified polyisocyanates, isocyanate-based prepolymers, and mixtures thereof. These can include aliphatic and cycloaliphatic isocyanates, but aromatic and especially multifunctional aromatic isocyanates are preferred. Preferred polyisocyanates are 2,4- and 2,6- toluenednsocyanate and the corresponding isomeπc mixtures; 4,4'-, 2,4'- and 2,2' -diphenyl-methanednsocyanate and the corresponding isomeric mixtures; mixtures of 4,4'-, 2,4'- and 2,2'- diphenylmethanednsocyanates and polyphenyl polymethylene polyisocyanates PMDI; and mixtures of PMDI and toluene dnsocyanates. Also useful for preparing the polyurethanes of the present invention are aliphatic and cycloaliphatic isocyanate compounds such as 1,6- hexamethylene-dnsocyanate; l-ιsocyanato-3, 5, 5-trιmethyl-l-3- lsocyanatomethyl-cyclohexane; 2, 4- and 2, 6-hexahydrotoluene- dnsocyanate, as well as the corresponding isomeric mixtures; 4,4'-,

2,2'- and 2, 4 '-dicyclohexylmethanednsocyanate, as well as the corresponding isomeric mixtures.

Also advantageously used for the polyisocyanate component of the formulations of the present invention are the so-called modified multifunctional isocyanates, that is, products which are obtained through chemical reactions of the above dnsocyanates and/or polyisocyanates. Exemplary are polyisocyanates containing esters, ureas, biurets, allophanates and preferably carbodiimides and/or uretonimmes; isocyanurate and/or urethane group containing dnsocyanates or polyisocyanates. Liquid polyisocyanates containing carbodnmide groups, uretonimme groups and/or isocyanurate rings, having isocyanate groups (NCO) contents (42/polyιsocyanate mwt.) of from 10 to 40 weight percent, more preferably from 20 to 35 weight percent, can also be used. These include, for example, polyisocyanates based on 4,4'-, 2,4'- and/or 2, 2'-diphenylmethane diisocyanate and the corresponding isomeric mixtures, 2,4- and/or 2,6- toluenednsocyanate and the corresponding isomeric mixtures; mixtures of diphenylmethane dnsocyanates and PMDI and mixtures of toluenednsocyanates and PMDI and/or diphenylmethane dnsocyanates.

Suitable prepolymers also useful with the present invention are prepolymers having NCO contents of from 5 to 40 weight percent, more preferably from 15 to 30 weight percent. These prepolymers are prepared by reaction of the di- and/or poly-isocyanates with materials including lower molecular weight diols, triols, but also they can be prepared with multivalent active hydrogen compounds such as di- and tπ-amines and di- and tri-thiols. Individual examples are aromatic polyisocyanates containing urethane groups, preferably having NCO contents of from 5 to 40 weight percent, more preferably 20 to 35 weight percent, obtained by reaction of dnsocyanates and/or polyisocyanates with, for example, lower molecular weight diols, triols, oxyalkylene glycols, dioxyalkylene glycols or polyoxyalkylene glycols having molecular weights up to about 800. These polyols can be employed individually or in mixtures as di- and/or polyoxyalkylene glycols. For example, diethylene glycols, dipropylene glycols,

polyoxyethylene glycols, polyoxypropylene glycols and polyoxypropylenepolyoxyethylene glycols can be used.

Particularly useful in the present invention are: (1) polyisocyanates having an NCO content of from 8 to 40 weight percent containing carbodnmide groups and/or urethane groups, from 4,4'- diphenylmethane diisocyanate or a mixture of 4,4'- and 2,4'- diphenylmethane dnsocyanates; (ii) prepolymers containing NCO groups, having an NCO content of from 20 to 35 weight percent, based on the weight of the prepolymer, prepared by the reaction of polyoxyalkylene polyols, having a functionality of preferably from 2 to 4 and a molecular weight of from 800 to 15,000 with 4, 4 '-diphenylmethane diisocyanate or with a mixture of 4,4'- and 2, 4 ' -diphenylmethane dnsocyanates and mixtures of (1) and (ii); and (m) 2,4- and 2,6- toluene-dnsocyanate and the corresponding isomeric mixtures. PMDI in any of its forms can also be used and is preferred. In this case it preferably has an equivalent weight between 125 and 300, more preferably from 130 to 175, and an average functionality of greater than about 2. More preferred is an average functionality of from 2.5 to 3.5. The viscosity of the polyisocyanate component is preferably from 25 to 5,000 centipoise (cps) (0.025 to about 5 Pa's), but values from 100 to 1,000 cps at 25°C (0.1 to 1 Pa's) are preferred for ease of processing. Similar viscosities are preferred where alternative polyisocyanate components are selected. Still, preferably, the polyisocyanate component of the formulations of the present invention is selected from the group consisting of MDI, PMDI, an MDI prepolymer, a PMDI prepolymer, a modified MDI and mixtures thereof.

Polyfunctional active hydrogen containing materials useful with the present invention can include materials other than those already described hereinabove. Active hydrogen containing compounds most commonly used in polyurethane production are those compounds having at least two hydroxyl groups. Those compounds are referred to herein as polyols. Representatives of suitable polyols are generally known and are described in such publications as High Polymers, Vol. XVI,

"Polyurethanes, Chemistry and Technology" by Saunders and Frisch,

Interscience Publishers, New York, Vol. I, pp. 32-42, 44-54 (1962) and Vol. II, pp. 5-6, 198-199 (1964); Organic Polymer Chemistry by K. J. Saunders, Chapman and Hall, London, pp. 323-325 (1973); and Developments in Polyurethanes, Vol. I, J. M. Burst, ed. , Applied Science Publishers, pp. 1-76 (1978) . However, any active hydrogen containing compound can be used with the present invention. Examples of such materials include those selected from the following classes of compositions, alone or in admixture: (a) alkylene oxide adducts of polyhydroxyalkanes; (b) alkylene oxide adducts of non-reducing sugars and sugar derivatives; (c) alkylene oxide adducts of phosphorus and polyphosphorus acids; and (d) alkylene oxide adducts of polyphenols. Polyols of these types are referred to herein as "base polyols". Examples of alkylene oxide adducts of polyhydroxyalkanes useful herein are adducts of ethylene glycol, propylene glycol, 1,3- dihydroxypropane, 1, 4-dihydroxybutane, and 1, 6-dihydroxyhexane, glycerol, 1, 2, 4-trihydroxybutane, 1, 2, 6-trihydroxyhexane, 1,1,1- trimethylolethane, 1, 1, 1-trimethylolpropane, pentaerythritol, polycaprolactone, xylitol, arabitol, sorbitol, mannitol. Preferred herein as alkylene oxide adducts of polyhydroxyalkanes are the ethylene oxide adducts of trihydroxyalkanes. Other useful adducts include ethylene diamine, glycerin, ammonia, 1, 2, 3, 4-tetrahydroxy butane, fructose, and sucrose.

Also preferred are poly(oxypropylene) glycols, triols, tetrols and hexols and any of these that are capped with ethylene oxide.

These polyols also include poly (oxypropyleneoxyethylene)polyols. The oxyethylene content should preferably comprise less than about 80 weight percent of the total polyol weight and more preferably less than about 40 weight percent. The ethylene oxide, when used, can be incorporated in any way along the polymer chain, for example, as internal blocks, terminal blocks, or randomly distributed blocks, or any combination thereof.

Polyamines, amine-terminated polyols, polymercaptans and other isocyanate-reactive compounds are also suitable in the present invention. Polyisocyanate polyaddition active hydrogen containing

compounds (PIPA) are particularly preferred for use with the present invention. PIPA compounds are typically the reaction products of TDI and triethanolamine. A method for preparing PIPA compounds can be found in, for example, United States Patent 4,374,209, issued to Rowlands.

Another preferred class of polyols are "copolymer polyols", which are base polyols containing stablely dispersed polymers such as acrylonitrile-styrene copolymers. Production of these copolymer polyols can be from reaction mixtures comprising a variety of other materials, including, for example, catalysts such as azobisisobutyro- nitrile; copolymer polyol stabilizers; and chain transfer agents such as isopropanol.

It is often preferable to premix all of the components except the polyisocyanate (and the blowing agent when a gas is used) to form a "B" component. The polyisocyanate and the B component are admixed and then the blowing agent gas is blended into the admixture using, for example, an OAKES FROTHER* (*OAKES FROTHER is a trade designation of the E.T. Oakes Corporation) . The composition is preferably applied to a textile or other substrate prior to any significant level of curing using equipment such as a doctor knife, air knife, or extruder to apply and gauge the layer. In the alternative, the polyurethane formulation can be applied by forming it into a layer using a moving belt, allowing it to partially cure, and then marrying it to the textile using equipment such as a double belt laminator. After application of the foam layer, the polyurethane is cured by applying heat by means of an infrared oven, open flame forced draft convection impingement oven, heated plates or the like.

The polyurethane foam carpet underlays of the present invention can be prepared in a single step or in two or more steps. In a single step process, the A and B polyurethane components are all admixed in a frother at the same time and applied to a textile or other substrate. In a two step process, some or all of the water, catalyst, and optionally other components of the polyurethane formulation are added

to the formulation after it has been frothed. Preferably, this is done using a static mixer, but any means of adding and mixing the components which does not substantially remove or reduce the level of entrapped gasses added by frothing can be used.

Textiles useful with the present invention include broadloom carpet, automotive carpet, fabrics for automotive trim and automotive trunk liners. In addition, the textiles useful with the present invention can include synthetic playing surfaces, woven polymeric scrim, non woven polymeric scrim, wall coverings, sheet polymers, furniture covers. One preferred embodiment of the present invention is carpet tile prepared by incorporating the catalysts of the present invention into a carpet tile production process such as that disclosed in U.S. Patent No. 4,657,790 to Wing, et al. The '790 Wing, et al . patent is incorporated herein by reference.

The following examples are provided to illustrate the present invention. The examples are not intended to limit the scope of the present invention and should not be so interpreted. Amounts are in weight parts or weight percentages unless otherwise indicated.

EXAMPLE 1

88.5 parts of a 18 percent ethylene oxide capped propylene oxide polyol havmg di-hydroxy functionality and a molecular weight of 4,000 and an OH number of 29.4; 1.5 parts of an propoxylated ammo aminoethylethanolamine; 10 parts of diethylene glycol; 40 parts calcium carbonate; 40 parts of alumina trihydrate; 0.6 parts L5600*; 0.1 parts L-5440* (*L5600 and L5440 were silicone surfactants and were trade designations of the OSI Specialties, Inc.); 1 part water; 0.045 parts of a 20 percent solution of dibutyl tin sulfide in a 2000 molecular weight poly(propylene oxide) polyol having 12 percent ethylene oxide end-capping and an OH number of 55.1; and 0.0033 parts of 2 ethylhexanoic acid salt of 1,8 diazobicyclo [5, 4, 0) undecene 7 were admixed to form a master batch. The admixture was then mixed and heated to 120°F (48.9°C) and then allowed to cool to about 60°F (15.5°C) and was hereinafter referred to as the master batch.

The master batch and a 2.3 functional PMDI having an NCO content of about 32% and an average molecular weight of 290 were pumped to a 2 inch (5.1 cm) OAKES FROTHER* (*OAKES FROTHER was a trade designation of the E.T. Oakes Corporation) and frothed using compressed air. The Master batch was fed to the frother at a rate of 181 7 g/minute and the PMDI was fed at a rate of 42.5 g/minute The resulting froth had a density of about 284g/l. The froth was applied using a knife with a gap of 0.25 inches (0.64 cm) onto one side of a 2 8 oz/yd^ (95 g/m ² ) woven polypropylene carrier material. The resultant polyurethane foam backed textile was cured at 270°F (132°C) for about 6 minutes trimmed and rolled and cut for testing. Upon examination, the foam backed textile had satisfactory foam appearance and tactile properties.

Example 2

A second master batch was prepared as follows. 100 parts of a 46:46:8 mixture of a 2,000 molecular weight poly(propylene oxide) diol having about 10 percent ethylene oxide end capping, a 3,000 molecular weight 8 weight percent ethylene oxide poly(propylene oxide ethylene oxide) hetero-tπol, and diethylene glycol were admixed with 190 parts of calcium carbonate, heated to 120°F (48.9°C) and cooled to 72°F (22.2°C) .

290 parts of the second master batch was mixed with: 1.8 parts of a of 1.25 percent solution of UL-6* (* UL-6 was a trade designation the Witco Chemical Corp. and was dibutyltin dnsooctylmercaptoacetate) in the diol described above, 9 parts of a 20 percent mixture of water and the diol described above, 7.5 parts of a 20 percent mixture of L5614* silicone surfactant in the diol described above, and 73.0 parts of a prepolymer having a percent NCO content of 27.5 percent, prepared by reacting a 1:1 a prepolymer having an NCO content of 23 percent made by reacting a 45:55 mixture of dipropylene glycol and tripropylene glycol with MDI and a 2.3 functional PMDI having about 14 percent of the 0',P' isomer. The materials were fed into an OAKES FROTHER and frothed therein with compressed air and applied by knife with a gap of 0.48cm (190 mils) onto one side of a polypropylene

carrier material. The resultant carrier and polyurethane foam were heated 177°C (350°F) until the foam was cured (about 8 minutes) . The resulting carpet underlay was trimmed, cut and rolled. The underlay had a density of 12.1 lb./ft ³ (194 g/1), excellent surface appearance and fine cell structure.

Examples 3-7 and Comparative Examples 8-9

Examples 3-7 and Comparative Examples 8-9 were prepared substantially identically to Examples 1 except that the components listed in the table were used. The resulting carpet underlay was trimmed, cut, and rolled. The samples were subjected to physical testing, including the bend split test, the results of which were reported in the Table. The Bend Split test was done by taking a 1 inch by 2 inch (2.5 cm x 5.1 cm ) foam sample and bending it over a 0.25 inch (0.64 cm) plastic dowel and securing the foam to the dowel with a binder clip. The foam was then submerged in a 97°F (36.1°C) water bath observed to determine the length of time required for the foam to split completely across the 1 inch diameter (2.5 cm) down to the primary backing with the maximum reportable time being 3 minutes.

TABLE

* Not an Example of the present invention

¹ VORANOL 9420 was a trade designation of The Dow Chemical Company and was a

4,000 molecular weight poly(propylene oxide) diol prepared from a 4 functional initiator, having an OH number of 29.4 and 18 ethylene oxide capping.

^ VORANOL 9800 was a trade designation of The Dow Chemical Company and was a

Propoxylated ammo aπunoethylethanolamine having a nominal functionality of 4 and an OH number of 812.

³ Surfactant

⁴ Surfactant

⁵ A solution of 20 parts dibutyl tmsulfide in 70 parts VORANOL 9287 and 10 parts VORANOL 9543 which were polyol carriers and trade designations of The Dow Chemical Company.

° POLYCAT SA-102 was a trade designation of Air Products and Chemicals, Inc., and was a 53 percent solution of 1,8 diaza-bicyclo- 5, 4, O-undecene-7, blocked with 2-ethylehexanocι acid, in water.

PAPI-7940 was a trade designation of The Dow Chemical Company and was s a PMDI having an NCO content of 32 percent and an average molecular weight of 290.

° The isocyanate index of a formulation was calculated by dividing the number of isocyanate equivalents by the number of isocyanate reactive equivalents and multiplying by 100. ⁹ ASTM D-3676-78

10 ASTM D-3574-86 11 ASTM D-3574-86 12 ASTM D-3574-86

¹³ ASTM D-3574-86