DE2751378A1 - REINFORCEMENT ELEMENTS - Google Patents

Description

DR. BERG DIPL-ING. STAPF D1PL.-ING. SCHWABE DR. DR. SANDMaIR

PATENT LAWYERS ^ P.O. Box 860245-8000 Munich 86 * / 0 1 O / Q

Attorney File 28,595 November 17, 1977

MONSANTO COMPANY
St. Louis, Missouri / USA

Reinforcement elements

The invention relates to novel reinforcing elements comprising a bundle of fibers of aromatic oxadlazole / N-alkylhydrazide made with a conventional thermoset adhesive mix designed to adhere organic Tire cord is used on rubber, are impregnated.

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1H-54-O269A GW 809821/0890

* (089) 988272 Telegrams: Bmkkonlen: Hrpo-Buik Munich 4410122 * 50

988273 BERCSTAPFPATENT Munich (BLZ 70020011) Swift Code HYPU DE MM

988274 TELEX: kyet Vereinstwnk Munich 453 h '< ' 8LZ 70020270) 98JJ10 0524560 BERG d FMlxbeck Manchen 65.145-808 OLZ 70010080)

The term "aromatic oxadiazole / N-alkylhydrazide" used here denotes a fiber-forming copolymer which essentially has the following repeating structural units:

ti PR

Il Il I

d () A 'C N

0 I.

Ii Il Il I II

(a) - Ar - C C- and (b) - Ar '- C - N - NH - C -

in a molar ratio of 20:80 to or 95 × 5, where Ar and Ar ^{1 are} each a divalent aromatic radical and R is a C to C ^ - alkyl.

There is a need in the tire industry for an inexpensive tire cord that has sufficient fatigue strength and strength has high modulus. Fatigue resistance is usually achieved in an organic cord by twisting, i.e., several bundles of fibers are each rotated in one direction and then folded together with sufficient twist in the opposite direction, to get a symmetrically structured cord. With increasing twist, it increases in a cord fabric In general, the elongation of the cord, the fatigue strength of the cord is improved, but unfortunately the tear strength and the modulus of the cord required for strength and rigidity are decreased. Nevertheless, the Manufacture of traditional tire cords Cost of toughness and modulus of the cord fabric carried out,

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to obtain a cord which has sufficient fatigue strength for tire use.

An object of the present invention is thus to provide an inexpensive reinforcing element containing organic fibers and in which, without twisting, one for use adequate fatigue strength is achieved in tires, while maximizing tensile strength and des Module of the element.

The present invention provides novel reinforcement elements which are particularly advantageous for reinforcing rubber articles such as tires can be used where fatigue strength, Strength and rigidity are important.

In general, the elements of the invention have essentially no twist and contain a bundle of aromatic oxadiazole / N-alkylhydrazide fibers that are thermoset with a Conventional type adhesive mix used for adhering organic tire cord to rubber, impregnated and are preferably separated from each other by this. The used here. ": Term denotes" bundle of fibers "or" fiber bundle " r. several closely spaced or touching parallel fibers that have less than 0.167 twists per inch (2.54 cm; (6.57 twists per meter) of twist, i.e. from 0 - 0.167 twists per inch (2.54 cm) of twist. The inventive

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according to reinforcement elements are characterized by high tear strength and moduli as well as exceptional fatigue strength properties the end. Because the elements contain little or no twist, the elements exhibit due to Their fiber content has at least the same tensile strength and modulus as the fibers from which the elements are made are, while increasing the strength and rigidity of the rubber articles that are reinforced with the help of these elements will.

The manufacture of fibers from aromatic oxadiazole / N-alkylhydrazide relatively inexpensive monomers are disclosed in U.S. Patent 3,886,251 and British Patents 1,407,439 and 1,417,568 described. The aromatic oxadiazole / N-alkylhydrazide copolymers consist essentially of the regularly recurring structural units (a) and (b) defined above, in which Ar and Ar "are each a divalent aromatic radical such as e.g.

and R is an alkyl radical with 1 to 4 carbon atoms, such as -CH, or -CH ^ CH.,. Preferential

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wise are Ar and Ar ¹ \ ^ J / ^ or

R is methyl and is the molar ratio of (a) units to (b) units is between 40:60 and 60:40.

In the manufacture of the elements according to the invention, a bundle of oxadiazole / N-alkylhydrazide fibers of the desired total denier strength, for example 1500 denier , is impregnated with a thermosetting adhesive mixture, ie with an agent that binds cord to rubber, as is conventionally done with nylon - and polyester cords is applied to their. Improve adhesion to rubber. Such binders are well known in the art and are commonly referred to as "dips".

Particularly for the practice of the present invention Advantageous dipping fluids are the "RFL" dipping fluids, which are a dispersion of rubber latex in an aqueous Contains a solution of resorcinol formaldehyde resin. This here The term "resorcinol-formaldehyde resin" used includes this Modifications such as that described in U.S. Patent 3,660,202 and derived from resorcinol, formaldehyde and p-chlorophenol Resin one. The rubber latex is usually a copolymer of vinyl pyridine and a conjugated diolefin with 4 to 6 Carbon atoms such as butadiene-styrene-vinyl-pyridine terpolymer. The RFL immersion liquids and methods for their production are known in the art, and the components of dipping fluids as well as the immersion liquids themselves are in

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Commercially available.

The dipping liquid can be applied to the fiber bundles using conventional dipping or coating equipment. For example, the dipping liquid can be applied to the bundles by introducing the bundles into a bath embodying the dipping liquid, by dipping the bundles in the dipping liquid or by using rollers which bring the dipping liquid from the bath onto the bundles. After the application of the immersion liquid, the bundles are preferably drawn through a nozzle or opening of suitable size with a preferably curved entrance. The opening, the diameter of which is a little larger than that of the bundle, has the function of removing excess ta. Then the bundles, which must not come into contact with any guides that would push the dip liquid out of the bundle, are heated so much that the water is removed from the dip liquid and the dip liquid coagulates in place within the bundle. If desired, the dipping and / or drying processes can be repeated. After the final drying process, the bundles are allowed to pass through a heated environment for a sufficiently long period of time to harden the dipping liquid. The hardening process is carried out in a conventional manner :, by passing the yarn is drawn through a curing oven. Thereafter, feed the so erha. ¹ tenon elements collected and then

809871/089 0 ~ ^/?

conventionally used in the manufacture of composite rubber products such as tires.

According to an embodiment of the invention, the obtained elements wrapped with nylon 66 yarn of low denier number, using a high winding angle and re-immersed to increase the breaking strength of the elements .

The amount of dip liquid applied to the bundle can vary widely, for example from 13 to 40% solids based on the weight of the ribbon and depends on such factors such as the diameter of the opening mentioned above and the solid content, the immersion liquid. The elements preferably contain between 20 and 36% by weight of the thermoset adhesive mixture.

When elements are made according to the method described above, the fiber bundles are not just with. Impregnated adhesive mix, but the individual fibers of the bundle are also separated from one another by the adhesive mixture.

The following examples ^7. ? are intended to further illustrate the invention. In the examples, the stated percentages and parts are parts by weight, unless otherwise stated.

809821/0890

example 1

This example describes the production of typical immersion fluids, the for the production of the reinforcement elements according to the invention ^ a are beneficial.

Dipping liquid A with a solids content of 19.9% was prepared by first mixing 210 cm ^{3 of} HO, 0.63 cm ^{3 of} a 50% strength aqueous solution of NaOH, 9.23 g of resorcinol and 13 cm ^{3 of} formaldehyde, and then mixing it The resulting mixture was allowed to react for 5 hours at room temperature. Then a mixture of 210 cm ³ was a latex (40.8% solids) which styrene-butadiene-vinylpyridine terpolymer containing (a General Tire and Rubber Company under the trademark Gentac latex delivered latex), 50 cm ³ of water and 7 cm ³ NH.OH produced. While stirring the latter mixture, the first mixture was added and carefully stirred.

Dip liquid B with a solids content of 26.8% was prepared in the same way as dip liquid A, with the difference that "instead of 260 cm ^{3 of} water, only 130 cm ^{3 were} used.

Dipping liquid C with a solids content of 2 3.6% was prepared by mixing 116.75 cm ^{3 of} water, 0.65 cm ^{3 of} NaOH (50%), 8.3 g of resorcinol and 7.38 cm ^{3 of} formaldehyde, and that itself the resulting mixture was stirred for 5 minutes. This

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Mixture was added to 122 cm ^{3 of} Gentac latex (40, 8% solids) and the resulting mixture was stirred for 5 minutes then allowed to stand for 4 hours. This mixture was then added to 102.55 cm ^{3 of} a solution of a mixture derived from resorcinol, formaldehyde and p-chlorophenol, which contained 35.8% by weight of 2,6-bis- (2 ¹ , 4'-dihydroxyphenylmethyl) -4 -Chlorophenol in 5N aqueous ammonia, hereinafter referred to as "Solution A". The preparation of solution A is described in US patent 3.G6O.2O2. The resulting mixture was stirred for 5 minutes.

Dip Liquid D, at 28.1% solids, was prepared by adding 62.5 cm * of water to 62.5 cm ^{3 of} Gentac latex (40.8 % solids) and stirring for 5 minutes. After this time, the mixture obtained is added to 125 cm 'of solution A and the mixture obtained is stirred for 10 minutes.

Dip liquid E with a solids content of 33.8% was prepared in the same way as dip liquid A, with the difference that only 130 cm ^{3 of} water instead of 260 cm ³ and only 105 cm ^{3 of} Gentac latex instead of 210 cm ^{3 were} used.

Dip liquid F with a solids content of 32.2% was prepared in the same way as dip liquid C, with the difference that 183 cm ^{3 of} Gentac latex were added instead of 122 cm ³ .

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Dip liquid G with a solids content of 35.2% was prepared exactly like dip liquid C, with the difference that 732 cm ^{3 of} Gentac latex were added instead of 122 cm ³ .

Dip liquid H with a solids content of 36.2% was prepared in the same way as dip liquid C, with the difference that 976 cm ^{3 of} Gentac latex was used instead of 122 cm ³ .

Dip liquid I with a solids content of 36.2% was prepared in the same way as dip liquid C, with the difference that 366 cm ^{3 of} Gentac latex were used instead of 122 cm ³ .

Modifications of the above-described thaw fluid recipes can be achieved by reducing the amount of water used in their production or by adding additional amounts of latex will. The dipping fluids should be in well-sealed containers stored and frozen until used. The immersion liquids should be sealed before use allow to warm to room temperature.

Example 2

This example shows the production of a bundle of para-phenyleneoxadiazole / N-methylhydrazide fibers, those used to manufacture

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elements of the invention are advantageous.

Into a 30 gallon (113.5 liter) glass lined reaction vessel with a motorized spiral stirrer was pumped 4.228 kg of fuming sulfuric acid (22% SO ₃ ) to which 581.5 g (3.5 moles) of terephthalic acid, 679, was pumped. 9 g (3.5 moles) of dimethyl terephthalate and 925 g (7.109 moles) of hydrazine sulfate were added. The reaction mixture was stirred at 6O ⁰ C to prepare a solution, then the temperature was increased and held 18 hours 125 ° C. This highly viscous solution (8.1% polymer solids) was allowed to 8O ⁰ C abkühlen.und they diluted to 5% solids by stirring with 8581 g of fuming sulfuric acid (about 5% SO _3). The polymer solution obtained had a viscosity of 38.720 poise at 25 ° C, which was measured with a Brookfield viscometer (# 6 spindle). This polymeric solution was spun into fibers by extruding it through a 25-hole 6 mil (152.4µ) spinneret into a coagulating bath of 8% aqueous sulfuric acid maintained at 23 ° C. The spinneret was heated to 140 ° C and held 1/2 inch (12.7 mm) above the coagulating liquid. After the fiber had run under a guide located in the bath, it was passed over a water washing roller, a neutralizing roller that rotates in a 4% aqueous solution of sodium carbonate, through a water bath at 90 ° C., via another washing roller, a steam-heated drying roller and finally over one to 365 ° C

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held hot shoe stretched hot and at a speed 1279 feet (389.8 m / min.) wound on a spool core. The 25 fiber yarn obtained had the following Stretch properties:

Tear strength 16.9 gpd (grams per

denier

Elongation 6.9%

Module 265 gpd

Example 3

This example describes a typical method of manufacture of reinforcing elements according to the invention.

Fibers produced as described in example 2, were combined into a 1535 denier fiber bundle with a tear strength (T) of 12.54 gpd (grams per denier), an elongation at break (E) of 6.53%, a maximum modulus (M) of 250 gpd and a toughness (To) of 0.40 gpd and after was made by the following procedure. The bundle was taken from a supply reel around a first set of godet rollers (4 winders) down and under a non-rotating block roller, which is immersed in a basin that the Contains immersion liquid B, then vertically upwards through a Opening, further vertically upwards through the focal line of an infrared heater, which removes the water from the immersion liquid removed, over a rotating block roller and under one

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AS

Tension pulley of the hanging weight type over a second rotating block pulley, horizontally through a hot passage opening from 52 inches (132 cm) without affecting its surface. touch, over another block roll, to a second set of godet rolls (4 winders) around and finally on a conventional reel on which the thermoset, dip liquid containing Bundle is wound up.

The first set of godet rollers was driven at a bundle speed of approximately 7.7 feet (2.35 m / min.), thereby reducing the dwell time of the bundle in the hot passage opening to 33-34 see. amounts to. The temperature in the hot passage opening was 245 ° C. The supply reel tension was maintained at the minimum voltage required in order to prevent the bundle from being thrown around the first set of godet rollers will. The idler pulley and the hanging weights weighed 45 grams, reducing the tension of the bundle between the two Godet role sets was controlled. The reel provided the tension that prevented the bundle from getting around the second Godet roll set was thrown around. The opening was off Epoxy molded and had a 0.25 inch (6.35 mm) diameter passage that expanded exponentially to a Tapered passage of 0.0276 inch (0.7 mm) diameter. The opening was 3/8 in. (9.6 mm) long, with 1.8 in. (3.2 mm) 0.25 inches (6.35 mm) and 1/8 in diameter of their length Inches (3.2 mm) in length was 0.0276 inches (0.070 cm) or 0.0240 inches (0.061 cm) in diameter and 1/8 of an inch

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(3.2 mm) its length tapered exponentially. The bundle was immersed at room temperature. However, there was the plunge pool in an ice bath to create a film on the To prevent immersion liquid.

The T / E / M / To properties of the obtained bundle were 13.47 gpd / 7.92% / -224 gpd / 0.49 gpd. This element is described below designated as 3A.

Example 4

This example describes the production of further inventive Elements. In each case a fiber bundle was made according to the method described in Example 2 and according to the Treated procedures described in Example 3. The immersion liquid used and other treatment conditions as well as the Properties of the untreated bundles (U) and the treated bundles (B) are listed in the following table.

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TABLE I.

Element Denier% E Tgpd Mgpd Togpd Immersion % Solids Size of Cure

fl. opening (inch) temperat. ° C

4A U B. 4B U 4C B. B. 09 4D O B. CO 00 4E * U - * B. O 4P * co B. co O 4G U B.

1550 5.19 11.28 264 0.30

1550 7.53 13.02 207 0.47 B 26.8 0.0276 265

1551 6.61 11.80 23 0.39 1551 7.75 12.56 207 4.47

1551 7.41 12.29 0.44

1551 6.89 12.33 216 0.41

1543 5.93 14.81 283 0.45

1543 7.87 16.54 257 0.62

1543 7.66 16.70 289 0.59

1542 6.34 15.21 274 0.48

1542 7.89 15.36 226 0.59 I 36.2 "0.0276 265

U = untreated bundle * = bundle was dipped twice using one B = treated bundle 0.0240 inch diameter opening after first dip

and a 0.0276 inch diameter opening after

second dive.

E. 33.8 0.0276 245 E. 33.8 0.0276 265 F. 33.8 0.0276 265 G 35.2 0.0240
0.0l76 265 H 36.2 0.0240
Λ Λ * \ "1 ZT 265

Example 5

This example describes the manufacture and the compaction fatigue test typical elements of the invention. The preparation of suitable specimens for testing the fatigue strength the elements requires several steps. The final steps before testing include making a composition Made of epoxy resin - rubber - element measuring 3 χ 1/2 χ 1/2 inches (7.62 χ 1.27 χ 1.27 cm) by 1 χ 1/2 χ 1/2 inches (2.54 χ 1.27 χ 1.27 cm) epoxy on each end and a 1 χ 1/2 χ 1/2 inch (2.54 1.27 χ 1.27 cm) intermediate section Rubber-epoxy resin composite. The elements are arranged in the middle of the rubber-epoxy resin composite, with the Longitudinal axis thereof extends between the epoxy resin end portions.

Preparation of the samples

All test samples were prepared according to the following procedure. First, an element was made into rubber blocks of 1 χ 1/2 χ 1/2. Inches (2.54 1.27 χ 1.27 cm) vulcanized with 1 1/2-2 inches (3.81 - 5.08 cm) of the element across each end of the rubber block protruded. This step was done using a mold capable of vulcanizing 20 samples at a time allowed. Preformed rubber spacer blocks were placed in the mold to create open spaces that could later be used Epoxy resin were used. Uncured rubber was placed in the 1 inch (2.54 cm) sample area. The element

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Sample was pulled through the mold and tied at each end. Additional uncured rubber and spacer half-blocks were placed at the top of the element and then the mold was closed. The cold form was placed in a hot press (202-204 ^e C) at a pressure of 907 kg, and after 8 minutes the pressure was increased to 9070 kg. After about 20 minutes the temperature reached 166 ^° C. and was set to this temperature. After 35 minutes the heating was turned off and the mold was cooled under pressure. The samples were removed from the mold and the item on. cut halfway between each block of rubber. Each element end was cemented to a 7/16 χ 1/8 inch (1.1 0.3 cm) aluminum post and then wrapped around the post in at least two turns and held in place with a rubber ring. The samples were then put back in shape and the mold was heated for 20 minutes from 45 to 50 ⁰ C. Epoxy resin (Shell Epon 815 / Hardener ü) was poured into the open cavities between the rubber blocks. The hardening of the epoxy resin was continued for 40 minutes at 45-5O ⁰ C and a further 60 minutes at 70-80 ⁰ C. The mold was allowed to cool to room temperature. The mold was then disassembled and the test samples removed. For each of the elements described in Examples 3 and 4, five test specimens were produced.

Fatigue test The fatigue strength of the elements was measured using a

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machine specially designed for this purpose. The machine has two vertically mounted rotating steel plates each of which is a few inches thick, and which have one diameter about one foot. These plates are arranged in opposition, at a distance one inch (2.45 cm) inside a thick-walled thermal enclosure. Both plates rotate at the same speed (rpm) (U / Min.) and each rotates around an axis, the other at an angle in the horizontal plane between the plates meets. In the test, a sample is placed between the panels with one epoxy end of the sample well attached to the periphery one plate and the other epoxy end is clamped to the periphery of the other plate. A plate is equipped in such a way that it can tilt the sample in relation to the other plate in order to achieve a specific compression and To ensure voltage stress during the test. Both plates rotate together during the test. So subject the specimen during one revolution of the plates (i.e. in one cycle) first a compaction stress and then a voltage stress or vice versa. This machine has 24 stations, which means that 24 samples can be tested at the same time will. The samples are taken out and in one Instron broken using a hand clamp with serrated sides 1 "(2.54 cm) 2" (5.08 cm). The strenght of the rubber is subtracted from the maximum breaking strength, before the tensile strength and other properties of the

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Elements are calculated.

Using the machine described above for fatigue testing test specimens containing the elements described in Examples 3 and 4 were prepared as described above and checked. During the test, the plates were tilted together to avoid a compression load of 7.5% and a stress stress of 2.5%. The number of cycles given in the table for each set of samples represents a value beyond which a large number of samples from this set failed. The exam results are listed in Table II.

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TABLE II

Samples Element Cycles Tested Failed

Average % held held tear strength tear strength (gpd) ity

Average, number of samples

3A 2 100,000 5 0 2.93 22nd 5 4A .000.000 5 0 1, 96 15th 5 4B 100,000 5 1 2.31 18th 4th m 4C 2 100,000 5 0 2.78 23 5 O
CO
OO
KJ 4D
4E 2 100,000
.000.000 5
5 1
0 2.02
2.68 16
16 4th
5 4F 4th .000.000 5 0 2.49 15th 5 890 4G .000.000 5 0 2.23 14.5 5

The results listed in Table II show the extraordinary Fatigue strength of the elements according to the invention which is achieved without the use of twisting.

Example 6

In this example, commercially available poly (p-phenylene terephthalamide) fibers manufactured and tested according to the procedures described in Examples 3-5.

In Table III are the dipping liquids used as well further treatment conditions and the properties of the untreated (U) and treated (B) bundles are listed.

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TABLE III

QO O CO CD

Element Denier% E T (gpd) M (gpd) To (gpd) immersion fl. % Fixed

U 1536 CA 1536 CB 1536 CC 1536 U 1517 CD* 1517

3.53 17.44

3.85 19.13 0.33

3.45 18.97 209 0.29

3.47 20.48 741 0.31

3.24 16.99 593 0.27

3.20 17.94 527 0.27

E. 33 ,8th 0, 0276 C. 23 , 6 0, 0276 C. 23 , 6 0, 0276

36.2

Opening curing temp. Size (inches) ⁰ C

265 245 265

0.0240
0.0276

265

* Bundle dipped twice using an opening with a diameter of 0.0240 after the first dip and an opening with a diameter of 0.0276 after the second dive.

From each of the above-mentioned elements CA-CD, test samples were produced as described in Example 5 and tested. The results of these tests are given in Table IV. As in Table II represents the number of samples for each set of samples specified cycles represent a value beyond which a large Number of samples from this set failed.

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element Cycles rehearse
Checked Failed 4th CA 10,000 5 4th CB 10,000 5 4th CC 10,000 5 3 CD
O
CO
00
NJ CD 50,000 5 / 0890

Ui

TABLE IV

Average % held # of the samples held tear strength- tear strength avg. ability fgpd)

19.13 4 1

18.97 3 1

20.49 2 1

17.94 10 2

The results in Table IV show that those made from poly (p-phenylene terephthalamide) bundles produced elements compared to the elements according to the invention have a low fatigue strength exhibit.

Example 7

This example demonstrates the fatigue strength of the invention Elements.

Elements according to the invention were incorporated into the belts of two JR78-15 radial tires. Before these elements were used to make the tires, the tires were hemmed in with a low denier nylon yarn at a high winding angle and dipped again. The belts of the tires contained 14 elements per inch (2.54 cm) and the tire body contained conventional polyester cord. During the wheel test in the laboratory, the tires were ^{inflated to 24 psig (1,687 kg / cm 2} ) strength and then at 30 mph (48.3 kph) under a load of 1580 lb (716.7 kg), three Firestone cleats (engl .: cleats) on the bike that delivered 900 crown impacts per mile (1.6093 km). The tires failed between 48oo (7725 km) and 5500 (8851 km) miles because the outer layer of the tire's body came off from beneath the tread, and not because of some defect that could apparently be related to the belt. The results of this test indicate that the elements according to the invention have a fatigue strength

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wise for their use in radial tires and certainly also in bias-belted tires, for the 3,000 miles (4,828 km) found without failure is appropriate.

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Claims (7)

PATENT CLAIMS ₁ 1J reinforcing element, characterized by a bundle of fibers made of an organic polymer, consisting essentially of repeating units of the formula MN "'- ■ *'^'-:;" Ca} Ar-C C and dex formula OR O H I 1 Cb) - Ar ¹ -CN- HH-C- in a Holvarratio of 20:80 to 95: 5, where Ar and Ar * are each a divalent aromatic radical and R is a C. to C. alkyl, and which is with a is a cured resinous adhesive composition comprising a mixture of an elastomer and a resorcinol-formaldehyde resin or modifications thereof and wherein said bundle has less than 0.167 twists per inch (2.54 cm) of twist. 2. Element according to claim 1, characterized in that the said elastomer is a copolymer of polyvinylpyridine, butadiene and styrene and said resin is a resorcinol-formaldehyde resin or a 2,6- to C 2 ·, 4 · dihydroxypheny! methyl) -4 -chlorophenol containing compound. 809821/0890 ORIGINAL INSPECTED * 'Sb 1378 3. Element according to claim 2, characterized in that said copolymer consists essentially of repeating units of the formula HHO CH, 0 I Ii II ³ i (A) - Ar - C C- and (B) - Ar »-C-N-NH-C- ordered, in which Ar and Ar * each come from the -O- existing group can be selected and the Molar ratio of the units (A) to (B) between 60:40 and 4Or60 is located. 4. Element according to claim 3, characterized in that Ar and Ar are " // --Λ. 5. Element according to claim 4, characterized in that the twist of said bundle is zero. 6. The element of claim 2 characterized in that said bundle is between 1000 and 4000 deniers. 7. A flexible rubber article characterized in that it is reinforced by elements according to claim 1. 809821/0890