FI58931C - ELASTOMERKOMPOSITION FOER DAECKSLITYTOR - Google Patents

Description

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Paterit noddel.it ^ 'r ~ ^' (51) Kv.ik? /Int.ci.3 C 08 F 232 / 04-, 210/00, 236/04, B 60 C 1/00 FINLAND —FINLAND (il ) Mwttlliil («M» -htt «cweknln | 751908 (22) HtktmitpUvi - AittMinlngtdag 27.06.75 ^ ^ (23) AlkupUvt — Gtttlfh« t * dag 27.06.7 5 (41) Tullut JulklMktl - Bltvlt 75 offtntllg 29 I »r« kilt * Hh «Hlttis___

Patent- och ragistoratyrelaen 'Ana6kan utiagd och uti. * Krift «n pubiicarad 30.01.8l (32) (33) (21) Pyy *> ** ty« uoikeu »—Begird priority 28.06. Ik France-France (FR) 7 ^ / 22809 (71) Michelin & Cie (Compagnie Generale des Etablissements Michelin), Clermont-Ferrand, France-France (FR) (72) Yves de Zarauz, Gergovie - 63Le Cendre, France-France (FR) (7 ^) Oy Kolster Ah (54) Elastomer composition for treads of outer tires -Elastomerkomposition för däckslitytor

The invention relates to an elastomeric composition consisting of an ethylene-propylene-diene tetrapolymer-type elastomer together with components known per se, for use in the production of treads for an outer tire.

Elastomers of the ethylene-propylene thermonomer type, also called "EPT" or "EPDM", are known to be copolymers of ethylene, propylene and an unconjugated diene. The function of the conjugated cyclic or straight-chain diene is to form double bonds which cause the ethylene-propylene-type elastomers to be vulcanized with sulfur; the diene may be, for example, dicyclopentadiene, 1,5-cyclooctadiene, 1,4-hexadiene, ethylidene norbornene, methylene norbornene, tetrahydroindene, methyltetrahydroindene, etc., or another diene copolymerizable with ethylene and propylene.

EPDMs are elastomers made from starting materials such as ethylene and propylene, which are less expensive than butadiene and styrene because they are less processed products than the latter.

/ 2 58931 These elastomers have certain advantages, in particular their resistance to aging and oxidation, combined with their low number of double bonds on the one hand and the position of double bonds in the hydrocarbon chain on the other hand.

As a result, their use in the rubber industry, especially in the manufacture of outer tubes, may be of interest. However, while their general properties are satisfactory compared to those of conventional diene elastomers, EPDM elastomers have a major drawback which has hitherto limited their field of application; they have a weak slip resistance, which makes them difficult to use as a tread for outer tires. Various solutions have been proposed to remedy this shortcoming. Attempts have been made to modify the nature and content of the thermonomers or the composition of the monomers, but in contrast to conventional elastomeric dienes, the softening and coefficient of friction of which can be modified by the nature and composition of the polymer. the coefficient of friction would be adequate in use and have satisfactory mechanical properties.

Thus, modifications of EPDM-type elastomers do not provide an elastomer with a high enough slip resistance for the tread of outer tires that have satisfactory adhesion to all road conditions and any degree of tire wear. Attempts have also been made to increase the concentration of carbon black and / or oil. But by improving the slip resistance by increasing the carbon black and / or oil content, this simultaneously causes a considerable deterioration of the hysteresis and mechanical properties.

It has now been found that the above-mentioned drawbacks can be avoided in a surprising and economically advantageous manner, and an EPDM-type elastomer can be produced for a tread of outer tires having slip resistance and normal hysteresis properties compared to classical EPDM types.

The invention is characterized in that the tetrapolymer is an ethylene-propylene unconjugated diene modified from 3 to 30% by weight of a norbornene derivative of the formula h r6 358931 wherein R 1, R 8, R 8, R 2, R 2, R 8 , R 1 and R 8 all represent a hydrogen atom, or R 8 and R 2 represent an alkyl group having 1 to U carbon atoms which may be substituted by halogen, or a phenyl group which may be substituted by an alkyl group having 1 to 1 carbon atoms, or R 1, R 2, Rg and R6 together represent a cycloaliphatic group having 5 or 6 carbon atoms, and R and R8 may further represent an alkyl group having 1 to 1 carbon atoms, or a mixture of such norbornene derivatives. The norbornene derivative or mixture of derivatives acting as a steric barrier in the elastomer, when used in a small amount, raises the glass transition temperature of the tetrapolymer.

According to the invention, the flexibility of the macromolecular chains of elastomers has been reduced by adding an ether barrier. These elastomers have improved softening properties and, in particular, improved slip resistance, which do not cause a significant deterioration of the hysteresis properties.

Examples of tetrapolymers used include: ethylene-propylene-1,1-hexadiene-norbornene ethylene-propylene-1,1-hexadiene-5-methyl-norbornene ethylene-propylene-1,1-hexadiene-5-phenyl-norbornene ethylene-propylene -1,1-hexadiene-5-chloromethyl-norbornene ethylene-propylene-ethylidene-norbornene-norbornene ethylene-propylene-ethylidene-norbornene-5-methyl-norbornene ethylene-propylene-ethylidene-norbornene-5-phenyl-norbornene and ethylene-ethylene

These polymers are prepared by methods known per se. They can be obtained by reacting them in a catalytic system consisting of: a) a transition metal compound belonging to groups IV-VIII of the Mendeleev Periodic Table of Elements, b) compounds of elements belonging to the main groups I-III of the Periodic Table of the Elements. Preferred elements of groups I-III are aluminum compounds of the formula AIRX ^ X ^, where R is a hydrocarbon radical, a hydrogen atom and X1 and X ^, which may be the same or different, have the same meaning as R or halogens. Particular mention may be made of: alkylaluminum sesquichlorides, dialkylaluminum halides, monoalkylaluminum dihalides, trialkyl or triarylaluminum.

Suitable compounds of metals of groups IV-VIII of the Periodic Table of the Elements include titanium tetrachloride, esters of chlorotitanic acids, vanadium derivatives such as vanadium tetrachloride, vanadium oxychloride, vanadium esters such as vanadyl butylate, vanadyl isopropylate, vanadium triacetate, vanadium triacetate, vanadium triacetate.

>. 58931

The copolymerization can be carried out in liquid monomers, optionally under pressure, in the presence of inert diluents such as optionally halogen-substituted cycloaliphatic or aromatic hydrocarbons and at a temperature ranging from a wide range of -20 ° C to + 60 ° C. The reaction is stopped by classical methods and the polymers are recovered after removal of the diluent by steam.

The invention is illustrated in the examples below. In these examples, the properties of the polymers have been determined as follows: the propylene content has been determined by infrared spectrography, the content of steric barrier monomers has been determined by NMR; logarithmic viscosity values are determined in ethylene tetrachloride at a concentration of 0.1 g / 100 ml, the coefficient of friction SRT at 20 ° C corresponds to the wet skid index measured with a "skid resistance Tester" (SRT) marketed by Societe Stanley; the higher the number, the better the coefficient of friction. The vulcanization is performed at about 150 ° C for approximately 20 minutes.

Example 1 This example compares various classical ethylene-propylene thermonomer type elastomers to the reference compound in terms of their properties. The polymerization of the elastomers EPDM 1/1 and 1/2 is carried out continuously in an 8 liter reactor, keeping the following flow rates 1 / h constant: EPDM 1/1 EPDM 1/2

Heptane 15.5 Toluene 15.5

Ethene 270 Ethylene 300

Propylene 700 Propylene 675 1,4-hexadiene 0.12 Ethylidene norbornene 0.4 (4 wt% solution in toluene)

Catalyst concentrations VO (OBu) ^: 0.21 mmol / l heptane 0.047 ramol / l toluene 2.1 mmol / l heptane 0.47 mmol / l toluene

The properties are shown in Table I.

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Table I

Test No. EPDM EPDM NOKDEL 1070 * ..

1/1 1 / 2_1 / 3__Comparison

Weight- # of propylene from the amount of polymer k2 UO li

Logarithmic viscosity number dl / g 2.58 2.85 3.32

Iodine value 5.2 6.3 8.6

Mooney plasticity ML (1 + U) at i30 ° C 6θ 83 70

Composition and properties

Polymer 100 100 100 100 Oil ItO Uo 55 38

Black HAF 70 70 80 70

Venymämoduli

(100 #), kg / cm 6 14, V

Hysteresis loss at 60 ° C, # 32.6 37 37 31 * SRT at 20 ° C 87 82 83 100

Thermonomer 1, 4-hex-Ethylidene-1,1-hexadadiene norbornene diene * Nordel 1070 is an ethylene-propylene-1,1 + -hexadiene copolymer marketed

Du Pont de Nemours.

The reference compound consists of a mixture of 65 wt.% # SBR 1500 and 35 wt.% Polybutadiene.

It is noted that for use as a tread on outer tires, these polymers have insufficient slip resistance of less than 90.

Example 2 This example compares the properties of various elastomers of the classical EPDM type with the properties of conventional diene elastomers. The properties are shown in Table II.

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Table II

_Elastomer_SBR 1,500 Natural rubber NordelX 1 0 ^ 0 Nordel 1,070

Vulcanization method_S / Santocure S / Santocure S / TMTMS / MBT_S / TMTMS / MBT ___

Composition:

Carbon black 50 50 50 70 Oil 5 0 8 1 + 0

Polymer_1_00_100_ 100_1_00_

Elongation modulus p (100%), kg / cm_19 ^ 7_2 (7 * 5_18_13.5

Hysteresis loss at 60 ° C,% _32_22 ^ 5_31 * 5_33.5

Friction coefficient SRT

At 20 ° C_100_70_Jk_j6_

It is noted that the coefficient of friction of the EPDM types is low compared to the butadiene-styrene copolymer (SBR 1,500) marketed by Shell. It is insufficient to use these types of EPDM as a tread. * Nordel 1 0l + 0 is ethylene-propylene-1, U-hexadiene marketed by Du Pont de Nemours.

Santocure (n-cyclohexyl mercaptohenzothiazole monosulphide) is marketed by Societe Monsanto.

TMTMS (tetramethylthiuram monosulfide) is marketed by Societe Naugatuck Chemical Cy under the name Μ0ΝΕΧ.

MBT (mercaptobenzothiazole) is marketed by Societe Vanderbilt Company, Inc. as CAPTAX.

Example 3 This example illustrates the preparation of a tetrapolymer of the invention: ethylene-propylene-ethylidene norbornene-5-phenyl-2-norbornene. The polymerization is carried out continuously in a reactor charged with toluene at 20 ° C, which is then saturated for 25 minutes with constant stirring with a premixed stream of ethylene and propylene. The ethylene feed is 1.2 l / min and the propylene 0.6 l / min.

Then add: 1.5 ml of ethylidene-norbornene, varying amounts of 5-phenyl-2-norbornene, 0.25 mmol of V to 1.6 1 / min and 0.8 1 / min, respectively.

The reaction is stopped after 20 min by the addition of acetone and the polymers are recovered.

7 58931 The following composition is used (by weight): polymer 100 carbon black 65 oil 25

ZnO 5 stearic acid 1 sulfur 2.2 TMTMS 0.6 MBT 0.2

The properties are shown in Table III.

Table III

_Example No_III / 1 III / 2 III / 3_III / U_

5-Phenyl-2-norbornene added to the reaction was 0 g_3 g_5 g_8 g

Weight of polymer obtained_28 g _27 g 26, g 25, h g ___

Weight- $ 5,5-phenyl-2-norbornene in modified EPDMr_0_6_9_12__

Weight-, propylene in modified EPDM_37_35_3k_32__

Logarithmic viscosity number, dl / g_2 ^ 50_2 ^ 63 2_J + 7 2_j53_

Lasiutumislämpötila_ ~ 51 ° C_ ~ ^ 6 ° C_ G_-UU °-HO ° C__

Elongation modulus (100%), kg / cm ^ _2k, 5_25_22_23,5__

Hysteresis loss at 60 ° C,% _27.7_30.1_29, ^ _ 32.6__

Scott fracture: breaking force (kg / cm 2) 207 236 2h8 260

Fracture length (%) _ Vf5_512_5 ^ 0_5 ^ 0__

Coefficient of friction (SRT) at 20 ° C 100 112 118 126

It is found that the modified EPDM of the present invention has a significantly improved slip resistance without deteriorating the hysteresis properties. In addition, it is noted that the improvement in the coefficient of friction depends on the phenyl-5-norbornene content of the polymer.

Example k This example deals with ethylene-propylene-1,1-hexadiene-5-phenyl-2-norbornene with varying concentrations of steric hindrance.

The polymerization is carried out continuously at the following feeds in 1 / min: heptane 15.5 ethylene 175 propylene k ^ 0 1, i + -hexadiene 0.160 and the following catalyst concentrations: 8 58931 VCKOBu) ^: 0.1U2 mmol / l in heptane, 1.1¾ mmol / l in heptane .

The composition of the mixtures is the same as in Example 3.

The properties are shown in Table IV.

Table IV

_Test No._IV / 1 IV / 2 IV / 3 IVA IV / 5_

5-Phenyl-2-nornene 0.5 3.75 5 in 10 grams_% by weight, 5-phenyl-norborene in modified 057 9 16 EPDM_, propylene in modified EPDM added to the reaction mixture : ssä_32_39_37_35_35_

Logarithmic viscosity number, dl / g_2.08 2, lU 2.20 2.25 2.1 * 6_

Elongation modulus (100%), kg / cm2 29.5 28.7 28.7 27.9 25.3_

Hysteresis loss at 60 ° C,% 28.7 29 »5_29 * 8_29.7_29.8_

Scott fracture: 2 fracture force kg / cm 180 197 203 211+ 250 fracture length,% _370_393_UU3_k6o_UlO_

Coefficient of friction (SRT) at 20 ° C_100 108_1_lU_12J_] k2_

A significant improvement in the coefficient of friction is observed without a significant deterioration of the hysteresis properties. Mechanical properties, especially Scott fracture, have also improved.

Figure 1 shows the coefficient of friction (SRT) (ordinate) as a function of the combined 5-phenyl-2-norbornene content (abscissa).

Figure 2 shows the hysteresis loss at 60 ° C (ordinate) as a function of 5-phenyl-3-norbornene content (abscissa).

The hysteresis loss factor at 60 ° C is defined as follows: hysteresis loss of the tetrapolymer at 60 ° C_ hysteresis loss of the reference polymer without norbornene phenyl

The higher the loss factor, the worse the hysteresis properties of the polymer.

9,58931

Figure 3 shows the coefficient of friction (SET) (in ordinate) as a function of hysteresis loss at 60 ° C (abscissa). The trade-off between adhesion and loss of hysteresis has been achieved as follows: a) with ethylene-propylene-1,1-hexadiene-5-phenyl-2-norbornene polymers (curve a); the loss factor has the same determination as above, b) by classical 1, U-hexadiene-containing EPDM (Nordel 1 660), by modifying the percentages of carbon black (curve b) with a composition containing 100 parts of polymer and 75 parts of oil.

TT_ hysteresis loss of the test mixture at 60 ° C

The treatment chromium is the hysteresis loss of the 100 x reference mixture at 60 ° C (SRT = 100).

It is stated that the higher the loss factor, the worse the hysteresis properties and that the best adhesion-hysteresis compromise is obtained with the polymers according to the invention.

Example 5 This example relates to ethylene-propylene-ethylidene-norbornene-norbornene. Operate under the same conditions as in Example 1, Experiment V / 1 and add 2-norbornene 6 g / l. The following composition is used by weight: polymer 100, carbon black 70, oil Uo, ZnO U, stearic acid 1, sulfur 2, TMTDS 0.6, MBT 0.2. The properties are shown in Table V below:

Table V

_Koe_V / J_V / 2_

Weight #, norbornene in modified EPDM_0_1J_

Weight #, propylene in modified EPDM_Ui_38_

Logarithmic viscosity number, dl J & _3.02_2 ^ 98_ o

Elongation modulus (100 #), kg / cm 1U, U_1_U_

Hysteresis loss at 60 ° C, # _37_U0_

Scott fracture value: ^ fracture force, kg / cm 202 230 fracture elongation, # _823_8 # 0_

Coefficient of friction (SRT) at 20 ° C 100_116_

Example 6 This example deals with ethylene-propylene-1, U-hexadiene-norbornene in Experiment VI / 1. The conditions are the same as in Example 1. In experiments VI / 2 and VI / 3, norbornene is added in U g / l and 5.3 g / l, respectively. This example demonstrates the effect of weight percentages of oil and carbon black. Composition a) polymer 100, carbon black 100, oil 75, ZnO 3, stearic acid 0.5, sulfur 1, MBT 0.5, TMTDS 1.

10 5 89 31

Composition b) polymer 100, carbon black 70, oil 1 (0, ZnO 5, stearic acid 1, sulfur 1, TMTMS 5, MBT 0.5.

The properties are shown in Table VI.

Table VI

_Example No._ VI / 1_ VI / 2 VI / 3_

Weight-, norbornene in modified EPDM __________ 0__6,5__9,5_

Weight-, propylene in modified EPDM ____ h2__39_

Logarithmic viscosity number, dl / g__2.65 2.57 2.55

Elongation modulus a) b) a) b) a) b) (100%) s kg / cm2__13 16.1 12.7 lU, U 12, H lU, 5

Hysteresis loss at 60 ° C,% __ Ui? 3 32.6 UU, 1 35.5 1 * 5, ^ 37.3

Coefficient of friction (SET) at 20 ° C__11U 100 125 111__13 ^ 118

Scott fracture: 2 fracture force kg / cm 179 203 179 216 181 233 fracture length,% _ 693 6 ^ 0 730 726 7bj 737_

It can be seen that the invention is applicable to all types of modified EPDM, regardless of the composition of the products to be vulcanized, assuming that the nature of the polymers is modified.

Example 7 This example describes the properties of tetrapolymers prepared by the method described in Example U and containing the following norbornene derivatives (Table VII): 5-chloromethyl-2-norbornene 5,6-dimethyl-2-norbornene-2 5-hexyl-2-norbornene P & tricyclo (5,2,1,0 ') -8-decene.

"58931

Table VII

_Example No._VII / 1 VII / 2 VII / 3_VIIA_VII / 5

As a steric hindrance 5 ~ chloro- tricyclo- .ς. 5,6-Di-hexylmethyl-2- (5,2,1,0'-methyl-2-nornorborneeo-decene 2-norborne homene) enene

Weight #, monomer acting as a steric barrier_0_10_8_9_9

Logarithmic viscosity number, dl / g_2.86 2.75 2.67_2 ^ 7_2.65

Elongation modulus (100 #), kg / cm 2 - _2h, 5_21.8_26.5_23_22.3

Hysteresis loss at 60 ° C,% _28.2_31 Λ_30 A_31, 5_30.5

Scott-fracture: P

breaking force, kg / cm 206 25 ^ 232 19 ^ 195 breaking length,% _392_1 * 58_1432_h20_Ul7

Coefficient of friction (SRT) at 20 ° C_100_1_l6_1_l8_120_110

All of these polymers contain 2% 1,1-hexadiene and 35% propylene. The composition of the vulcanizable products studied was: polymer 100, black 65, oil 25, stearic acid 1, sulfur 2.2. TMTMS 0.6, MBT 0.2.

A significant improvement in the coefficient of friction (wet slip index) associated with satisfactory mechanical and hysteresis properties is noted.

Claims (2)

58931 Elastomer composition consisting of an elastomer of the ethylene-propylene-diene tetrapolymer type together with components known per se for use in the production of treads, characterized in that the tetrapolymer is an ethene-propylene-unconjugated diene modified with 3 to 3% w / w with a norbornene derivative of the formula hi V <r * R6 wherein R1, R2> R1, R1, R1, R8, R8. and R 8 represent all hydrogen atoms, or R 8 and R 6 represent an alkyl group having 1 to 4 carbon atoms which may be substituted by halogen, or a phenyl group which may be substituted by an alkyl group having 1 to U carbon atoms, or R 1, R 2, R 8 and R 4 represent together a cycloaliphatic group having 5 or 6 carbon atoms and R 1 and R 8 may further represent an alkyl group having 1 to 4 carbon atoms, or a mixture of such norbornene derivatives. Elastomer composition according to Claim 1, characterized in that the norbornene derivative or a mixture of norbornene derivatives is present in the polymer in an amount of 5 to 15% by weight.