DE2354642A1 - BONDING A URETHANE POLYMERISATE TO A RUBBER - Google Patents

Description

Dr. Ing.Waiter Afete Dr. Dieter F.-Merf Dr. Hans-Α. Brown·

I MQociiu BB ₁ PlMZMUMfItA f |

October 31, 1973 CASE: Walt- 4

E. II DU ΡΟΝΐ DE NEMORS AND COMPANY Wilmington, Delaware, USA.

Bonding of a urethane polymer with a rubber.

It is known to make a composite article from a cast urethane elastomer and an uncured rubber, by touching the uncured rubber with a selected isocyanate, which in turn with a molded urethane elastomer is brought into contact. The urethane and the rubber will then both be in place hardened. .

One such technique is for some uses of the composite useful, but there are still many important applications for such a composite material, which not easily adapted to such a procedure. For example, the technique mentioned above would not be suitable for

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qene uses where one can make use of a rubber want to make that does not flow and does not deform. The un-. Usefulness would therefore refer to uses such as composite— "tires, industrial belts, coated rollers and covering τοπ floors with mats extend.

There is therefore a need for a method by which Help one make a urethane chewing composite article lcann, whereby in the manufacture of the article the rubber does not flow, is free from deformation and thereby a precise outline or shape can be given;

According to the invention it was surprisingly found that a "Composite article made of" urethane and rubber, with a polyisocyanate glued together, can be made in such a way that the rubber does not flow during processing and does not reject itself. This is achieved by a cured rubber is used in the process of making the composite article of urethane and rubber. ' The rubber can be broadly defined as an unsaturated elastomer. Typical ones falling into this category Rubbers are styrene - butadiene rubber, natural rubber and polybutadiene rubber. The surface of the rubber will mechanically roughened by rubbing. Mechanical roughening is essential as it creates a large surface area, which facilitates the gluing of the urethane.

The cured, mechanically roughened rubber is then treated with a solution of the selected polyisocyanates in which it can be aliphatic or aromatic, coated.

Particularly preferred isocyanates are the diisocyanates, such as 2,4> -Tolylene diisocyanate or isomers or mixtures thereof.

It is very preferred to use the polyisocyanate in solution ; in a volatile solvent. Any such solvent that is preferably volatile, non-flammable, inert

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is compared with polyisocyanate and of low toxicity, can be used _t v / ground. Chlorinated organic solvents such as trichlorethylene or dichloromethane are preferably used.

The cured rubber is coated with the isocyanate solution, the solvent evaporated, and the treated rubber is then contacted with a tetraethane prepolymer and curing agent. The hardening agent can be a poly oil or a polyamine. Curing is carried out at elevated temperature, eg at 80-120 ⁰ C. After about 0.5 - 6 Stunden obtained an article or laminate in which the rubber adheres to the polyurethane polymer, by the Polyisoeyanatbehandlung.

The rubber to be connected with the urethane can be unsaturated Elastomer can be characterized. A wide variety of known rubbers fall within those identified above Category. These include styrene-butadiene rubber, natural rubber, Polybutadi enkairtsch.uk, EPDMs and polychloroprene, * polymers.

The preferred composite articles produced according to the invention Processes are made from styrene-butadiene rubber, natural rubber or polybutadiene rubber here. It is important for the present invention that every rubber used in the process according to the invention before coating with polyisocyanate and combining is cured with the urethane polymer. The surface the cured rubber is mechanically roughened; any suitable technique can be used for such roughening v / earth. Preferably, however, the surface of the rubber is roughened in the following way: Rubbing with a fine Emory — line that creates shallow grooves about 0.01-0.1 mm. Deep. After rubbing, the rubber becomes with • Wiping off solvent to remove particulate matter.

The roughened rubber surface is coated with polyisocyanate. The group of diisocyanates, in particular aromatic diisocyanates, is preferably used. Some preferred aromatic diisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, mixtures of these "two isocyanates, 4,4'-methylene-bis (phenyl- isocyanate) and 1,3-phenylene diisocyanate. Aromatic or aliphatic triisocyanates can also be used, e.g. bisisocyanatocyclohexylmethylcyclohexane isocyanate and bisisocyanatophenylmethylphenyl isocyanate. The polyisocyanate is preferably in a volatile solvent. The solvent is preferably not only volatile but also non-flammable, inert to the polyisocyanate and of low toxicity. Chlorinated solvents are acceptable, and in particular _j sondere solvent such as methylene chloride, perchlorethylene · and trichlorethylene. Preferably, it is a relatively thin Polyisöcyanatschicht ago, a would be uneconomical to thick layer and the adhesion would not increase. Ge The polyisocyanate solutions are usually about 10-30% by weight / volume, preferably about 25%. The polyisocyanate solution is applied as a coating to the rubber in the usual way. This can be done by dipping, spraying the solution onto the surface of the rubber, brushing on or coating with rollers. The method of application of the polyisocyanate is not critical provided that a substantially uniform coating is obtained and the volatile solvent is allowed to evaporate.

After coating the rubber with the polyisocyanate the urethane prepolymer, which contains a curing agent, is applied to the surface treated with the polyisocyanate upset. Since the prepolymer is liquid, it can be sprayed on or dipped or any other suitable Application technique that results in a polymer coating with essentially complete coverage of the pretreated Substrate to be applied.

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The polyurethane prepolymers are produced by reacting a polyisocyanate with a polyol. The preferred polyisocyanates are diisocyanates, which in turn can be aromatic, aliphatic or cycloaliphatic. Suitable aromatic diisocyanates are the Cg-Coc aromatics. The aliphatic diisocyanates are the 0p-C ₁ g compounds and the cycloaliphatic are the C ^ -Cpc

Representative aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-methylenebis (phenyl isocyanate) and 1,3-phenylene diisocyanate.

Representative aliphatic polyisocyanates include hexamethylene diisocyanate, Xylylene diisocyanate, 1,12-dodecane diisocyanate, Iiysin ethyl ester diisocyanate and tri-N ^ ET ', U' '- (6-isocyanatohexyl) biuret. . ·

Representative cyoloaliphatic polyisocyanates include 4 f 4 ^r -methylene bis (cyclohexyl isocyanate), 1,4-cyclohexylene diisocyanate, 1-methyl-2,4-cyclohexylene diisocyanate and 2,4-bis (4th isocyanatocyclohexylmethyl) cyclohexyl isocyanate.

The above-mentioned diisocyanate is reacted with glycol to form the prepolymer; the glycols have a molecular weight of about 500 - 5000, preferably 800 - 2000. i Man several different Glycolarten may use, for example, those derived from saturated and non-saturated polyhydrocarbons, polychloroprene, polyformals, Polyalkylenäthern, polyesters etc.. Polyalkylene ether glycols or polyester glycols are preferably used. The preferred polyalkylene ether glycols have the general formula HO (RO) _n H, where R is an alkylene radical having about 2-10 carbon atoms, which need not be the same in every case. Representative glycols include polyethylene ether glycol, polypropylene ether glycol, polytrimethylene ether glycol, polytetraethylene ether glycol, polypenta

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methylene ether-glyc oil, polydecamethylene ether-glycol and poly-1,2 ~ dimethylethylene ether-glycol. Desired failures can also mixtures of two or more polyalkylene ether glycols be used.

The following polyester-glycols can be used: Polyester-glycols made by polymerizing cyclic lactones, such as 6-caprolactone, which is terminated with diols blocked, or by the condensation polymerization of dicarboxylic acids or their condensation equivalents and a molar excess of an organic diol. Too representative. Diacids include succinic acid, glutaric acid, and adipic acid and representative organic diols are ethylene glycol, Propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, Neopentyl glycol and their mixtures. Adipic acid ester of the lower alkyl polyols are preferred.

The isocyanate and the glycol at a temperature of about 50 - 9O ⁰ C reacted - 110 ° C, preferably at about the 70th The reaction takes place in the course of about 0.5 to 10 hours, preferably for about 1 to 5 hours. The molar ratio of isoeyanate group to hydroxyl group is about 1-2.5 NCO / OH, preferably about 1.5-2.2.

The prepolymer mixture also contains a curing agent or Crosslinking agents. The crosslinking or hardening agents are usually non-polymeric hydroxyl or amino compounds containing 2 or more active hydrogen atoms.

The non-polymeric hydroxyl compounds that are aliphatic, alicyclic. or aromatic, contain 2-8 hydroxyl groups. Typical aliphatic, non-polymeric hydroxyl compounds are ethylene glycol, propane-1,2- and -1,3-diols, butane-1 _t 2-diol, butane-1,3-diol, butane-1,4-diol, butane 2,3-diol, monomethyl diethanolaiiiin, diethanolamine, the pentanediols, the

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Hexanediols, the heptanediols, the octanediols, diethylene glycol, Dipropylene glycol, hexanetriols, glycerine, triethanolamine, ' Sorbitol and pentaerythritol. To alicyclic not polymeric Hydroxy compounds include the cyclohexanediols and sugars with 4, 5, or 6 carbon atoms; e.g. xylose, glucose and Galactose. To aroma.table.non polymeric hydroxy! Compounds include di- and trihydroxyphenols, e.g. Ms-phenol A. Propylene oxide adducts of the above aromatic polyols can also be used, as can mixtures of the above Polyols. '-

The non-polymeric hydroxy compounds preferably have Equivalent weights of about 30-80, most preferably about 45-60.

Other suitable crosslinkers are aromatic polyamines. The term "aromatic polyamine" as used herein denotes a compound in which each of 2 or more amino groups on the same or different benzene residues or related polycyclic aromatic hydrocarbon radicals is bonded. Representative polyamines include derivatives of tolylenediamines, metaphenylenediamines and phenylenediamines, e.g. 2,5-dichlorophenylene-1,4-diamine. Methylene-bis-o-chloroaniline and methylenedianiline can also be used as curing agents will. Other useful hardening agents are complexes of 4,4'-methylene-dianiline and certain salts, including HaCl and IiCl as disclosed in U.S. Patent 3,459,683.

The isocyanate-terminated prepolymer, which contains the curing agent, is applied as a liquid prepolymer to the Coating applied. If the prepolymer is not blocked or encapsulated at the ends, the usual ones are used Precautions to keep the prepolymer in a dry environment and the prepolymer mixture should be in the generally be used for casting no later than about 12 hours after manufacture.

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The crosslinking agent should be in a proportion of active H / NGO = 0.7-1.3, preferably 0.9-1.1-, be present.

The composite material is at a temperature of 70-150 C, preferably 90-120 ⁰ C, and bevorzugtesten cured at about 100 ⁰ C. The curing time can vary between 0.5 and 24 hours, preferably between 1 and 3 hours.

After curing, a composite article is obtained made from a cured rubber with a cured urethane polymer connected is. Such an article is used for various purposes, e.g. for composite tires, industrial belts, coated Y-folds and as a floor covering.

The following examples serve as a further illustration of the present invention, the parts and percentages given represent parts by weight and percentages by weight, respectively, unless otherwise stated:

example 1 Variation of the solvents used for Toluo 1-2,4-diisocyanate dissolving.

15.2 χ 15.2 cm strips of treated SBR rubber are prepared by curing one structure of a layer of technical SBR nylon Carcassengewebe between two 0.101 cm thick webs SBR tread material under pressure for 30 minutes at 150 ⁰ C. One surface of each strip is wiped with acetone, buffed by sanding with # 240 Emory fabric, and again wiped with acetone. A strip of scotch tape about 3.8 cm wide is placed along one edge of the strip to create a grip strip for the adhesion test. Another narrow strip of tape is placed lengthways along the center of the strip to divide it into two 7.6 15.2 cm areas for evaluating two adhesives at the same time. The strips are then mixed with 20% solutions of toluene-2,4-diisocyanate in the following

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Solvents: (a) methylene chloride,. (tr) trichlorethylene, (c) benzene and (d) acetone, coated. Approximately 1 ml of the solution is brushed onto a 7.6 x 12.7 cm area of the strip. The "coated strips are heated ^{under nitrogen" at TOO 0 C for 20 minutes.}

75 g of a Prepolymerisates of 1 mol with a Polytetramethylenätherglyeol Mcügewicht of about 1000 and 2 moles of toluene-2,4-diisocyanate are degassed under vacuum at 9O ⁰ O. Melted methylene-bis-o-chloroaniline (NHg / NCO = 1.05) is quickly added to the prepolymer, the mixture is stirred briefly, degassed again and poured onto the 'SBR strip in the recess of a 15.2 χ 15, 2 χ 1.9 cm piston mold. The mold is heated in an open press at 10O ⁰ C starts to gel until the tlrethankautschuk '(about 5-7 minutes). A piece of coarse cotton fabric is placed on top of the urethane rubber and the porm is closed. The joint is cured at 910 kg total pressure (approximately 2.8 kg / cm) for 1 hour at 100 ° C.

Two 2.54 cm wide strips are cut from each half of the strip and, after aging for more than 1 day, tested in a 180 degree peel adhesion test on an Instron tensile tester at a pull speed of 5.08 cm / min. None of the strips could be separated at room temperature and 100 ^° C. without tearing into the SBR rubber at the values given in the table below. ·.

Peel adhesion - kg / cm

I.
1
i at room temperature - "9 - at 100 ° a 17.6 10.5 . "b 19.6. 8.5 i C ■ 18.9 10.0 a • 20 ^ 6 11.6

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example Variation of the concentration of the toluene-2,4-diisocyanate.

Cured SBR strips (as in Example 1) are made with solutions of toluene-2,4-diisocyanate in methylene chloride in the following Concentrations treated: · (a) $ 10, (b) $ 20, (c) $ 50 and (d) $ 100 (no solvent). The solutions are applied and liquid urethane caustic school is poured on and the structure are cured as in Example 1. The peel adhesion tests are carried out as in Example 1. None of the stripes failed in the peel adhesion tests at room temperature and 100 ° C can be separated without entering the SBR rubber at the tear down the values given in the table below.

'Deduction Liability - - kg / cm at room temperature at 100 ° 19.2 8.5 - 18.9 12.5 '20.6 11.4 18.1 10.3

a
b
c
d

Example 5

Effect of SBR aging after treatment with toluene-2,4- diisocyanate.

Cured SBR strips (as in Example 1) are treated with a 20% solution of toluene-2,4-diisocyanate in methylene chloride. After the solution is brushed onto the SBR rubber, the strips are left in the air for (a) 30 minutes, (b) 2 hours, (c) 6 hours), (d) 24 hours, (e) 3 days , (f) 5 days and (g) 7 days before the liquid urethane is poured on and cured as in Example 1. The peel adhesion tests are carried out according to Example 1. None of the strip was at the peel adhesion test at room temperature and 100 ⁰ C are separated without specified in the SBR rubber in the in the following table

To tear down values.

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a "b c d e f

If 2354642 16.4 Peel adhesion - kg / cm 12.1. at room temperature at 100 17.8 27.1 17.8 30.6 '15.1 30.6 17.8 29.2 15.8 23.5 27.9 27.8

Note: The SBR strips used in these tests had a 0.203 cm thick tread section.

Example 4 Variation in the composition of the polyisocyanates.

Cured SBR strips (as in Example 1) are treated so that you have about 1 - 1.5 ml of 20 $ solutions in methylene chloride isocyanates specified in the following table. As in Example 1, these strips are cast with Urethane rubber connected. The peel adhesion tests will be carried out according to Example 1.

Peel adhesion - kg / cm

Isocyanate at Clears emp erature at 19.9 SBR at 100 ^° C 12.1 Toluene-2,4-diisocyanate SBR torn Il 21.7 Il torn at 13.2 $ 80, 2.4 TDI + $ 20 2.6TDI Il Il 1! 21.7 Il Il Il 12.1 65 # 2.4 TDI + 35 $ 2.6 TDI ti Il Il 23.2 Il It 4,4'-methylene-bis-cyclo-
hexyl isocyanate Il Il 11 23.5 SBR 2.0 16.5 4,4'-methylene-bis-phenyl-
isocyanate I! It Il 20.3 It torn at 11.6 Polymethylene polyphenyl
isocyanate 11 Il Il Il

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A,

Example 5

Variations in terms of solvent and concentration of the 2,4-bis (p-isocyanatobenzyl) phenyl isocyanate.

Solutions of 2,4-bis (p-isocyanatobenzyl) phenyl isocyanate are used in methylene chloride and trichlorethylene for coating of cured SBR strips to which cast urethane rubber is adhered, as in Example 2. The Peel Adhesion Tests are carried out as in Example 1, the results are given in the following table:

Peel adhesion - kg / cm conc. Solvent at room temperature at 10O ⁰ C

Methylene chloride SBR broke at 17.8 5.2, methylene chloride """17.4 2.8 trichlorethylene". "" ¹ 7.8 SBR broke at 9.6 trichlorethylene """18.5 5.7

example Adhesion of other urethane rubber to SBR.

Cured SBR- ^ strips (Example 1) are coated with a 20 # solution of toluene-2,4-diisocyanate in methylene chloride and produces adhesion test strips by applying liquid ITretharil cautery mixtures to the coated strips various prepolymers and methylene-bis-o-chloroaniline or methyl en-dianil in with a ML / NCO ratio of 1.00 pours and then cures as in Example 1. The peel adhesion tests are carried out as in Example 1. You get the the following adhesion test results:

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Peel adhesion - kg / cm Prepolymers sat

Polytetramethylene ether glycol with a molecular weight of "980 +80/20 mixture of 2,4- and 2,6-TDI, # NCO = 3.25

Poly t e tr amethylene ether glycol with a molecular weight of 1000 + 4,4'-methylene-biscyclohexyl-isocyanate, JS NCO = 5.52. Hardened with methylene dianiline.

Polyester glycol from ethylene and propylene glycols and adipic acid with a molecular weight of 1270 + 2,4-TDI, £ NCO = 4.83

Polyester glycol from ethylene and propylene glycols and adipic acid with a molecular weight of 2250 + 2,4-TDI, £ NCO = 2.71

"at room temperature

at 100 ^° C

SBR torn at 24.2 SBR torn at 10.1

22.8

17.8

9.8 thin layer peeled off the urethane

4.1 some of the urethane surface will be demolished

5.3 tear in thin _j Ürethans ^J chicht

4.1 Tear in thin urethane layer

Example 7

Changes to the hardened rubber. ·

Hardened strips of 15.2 15.2 χ 0.25 cm made of elastomers With a backside made of coarse cotton fabric, carbon black-reinforced compounds are made from (a) natural rubber, (b) ethylene-propylene-diene terpolymer and (c) polychloroprene. These strips are wiped with acetone by grinding roughened with 240 Emory linen and wiped off again with acetone. You will with 20 # strength methylene chloride solutions of Toluene-2,4-diisocyanate and 2,4-bis- (isocyanato-cyclohexylmethyl) -cyclohexane isocyanate coated and a liquid urethane rubber mixture is poured onto the strips, the whole thing is after

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cured according to the procedure of Example 1. The peel hardening Tests are carried out according to Example 1, the adhesion test results are indicated in the following table:

Peel adhesion - kg / cm

Elastomer Isocyanate Toluene-2,4-diiso-
cyanate at room temperature hot 100 ° C of
at More natural
rubber no C vcloali-Dhatisch.es 5.9 1.4 Toluene-2,4-diiso-
cyanate Ripping the
Materials at 24.2 5.3 Cycloaliphatic
Triisocyanate Ripping the
Materials hot 25.8 Tear
Materials
. 12.4 of
hey EPM no 1.2 - Toluene-2,4-diiso-
cyanate 4.3 0.9 of
hey Cycloaliphatic
Triisocyanate 3.9 Tear
Materials
5.0 of Polychloro- no 1.8 0.9 pren 3.6 Tear
Materials
4.5 Ripping the Tear

Triisocyanate

Materials hot 7.5 Materials hot

3.6

The cured elastomeric materials used in the preceding examples contained the following ingredients and were cured as addressed.

Natural rubber material Smoked sheet rubber Phenyl-oG-naphthylamine zinc oxide

Stearic acid

HAP soot Pine tar 2-benzothiazole di sulfide

Tetramethyl thiuram monosulfide

sulfur

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20 min, hardened at 155 C 100
1.5 5
2

50
1.5 0.2 0.2

2.5

2354642 EPEM material> 30 min cured at 155 ^{° C} E / P / 1,4-hexadiene polymer (42% wt. 100 P, 3.2 hexadiene, Mooney-Yiskositat 70) Zinc oxide 5 Stearic acid 1 FEF soot 100 aj
Naphthenic.es Process Oil ' 50 "' Sulfur. ··. ".- 1.5 Zinc dibutyl dithiocarbamate 2 Tetrataethylthiuramdi sulfide 0.5 2-mercaptobenzothiazole 1 Polychloroprene material 20 min hardened at 155 ^{0 O.} Polychloroprene ' 100 Stearic acid 0.5 Phenyl-oC-naphthylamine 2 Magnesia. ' 4th SRF soot " .58 C)
Napthenic Light Rubber Process Oil ' 10 Zinc oxide 1
5 2-mercaptoimidazoline 0.5 SBR material 30 min hardened at 150 ^{0 O} Styrene-butadiene-rubber masterbatch '' 183.74 Es-cis-polybutadiene polymerizes in solution 25.00 ZnO 3.00 Stearic acid 1.00 HAP soot. . 18.13 N-isopropyl-N'-phenyl-p-phenylene-diamine
Naphthenic.es Process Oil ^a ' 2.00. wax 5.68 N-t-Buttyl-2-benzothiazolesulfenamide 2.00 sulfur 1.25 2.25

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a) Specific gravity = $ 0.949 »$ 47.5 aromatics; Viscosity = 2525 SUS at 38 ^° C; Flash Point = 221 ⁰ C

"b) Manufactured according to Example 6 of US Pat. No. 2,494,087.

c) specific gravity = 0.9194; $ 42.9 aromatics; Viscosity = 156 "at 38 ° C, plash point = 166 ° C

d) 23.5 ^ styrene / butadiene chewing material mixed with 82.5 parts ISAF carbon black per 100 parts and 62.5 parts highly aromatic oil per 100 parts.

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Claims (1)

CASE: Walter- PATENT CLAIM Process for bonding a urethane polymer to a rubber with the aid of a polyisocyanate, wherein the surface of the rubber is coated with the polyisocyanate solution ", then a urethane prepolymer containing a curing agent applied to the polyisocyanate and the Urethane prepolymer to form a composite article hardened from a polyurethane bonded to the rubber is characterized in that a hardened rubber with a roughened surface is used will. - "17 4098 2 5/099 6