FI63040B - FOERFARANDE FOER FRAMSTAELLNING AV VULKANISERADE ELASTOMERER OCH DERAS ANVAENDNING I SLITYTOR OCH / ELLER SIDOR FOER YTTERDAECK - Google Patents

Description

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Patent- och ragiateratyralMn 'AmOkan utttfd odi «L.krtfun publkvrad 31.12.82 (32) (33) (31) Requested Muoikaui -4 · | Μ priorttvt 30.01.75 France-France (FR) 7503001 (71) Michelin & Cie ( Compagnie Generale des Etablissements Michelin), 63 Clermont-Ferrand, France-France (FR) (72) Yves de Zarauz, Gergovie, France-France (FR) (7M Oy Kolster Ab (5M) Method for the production of vulcanised elastomers and their use in treads and tires) and / or on the sides - For the production of volcanic elastomers and for the production of slurry and / or on the other side

The invention relates to a process for the preparation of vulcanized elastomers derived from liquid functional polymers and / or copolymers, and to the use of elastomers produced by this process in new or retreaded treads and / or sides of outer tires.

Studies have been performed to make outer rings having a tread and / or sidewalls formed of vulcanized elastomers made from low molecular weight liquid polymers and / or copolymers that contain reactive functions such as hydroxyl, carboxyl functions, etc. , and are commonly referred to as "liquid functional polymers". "Data Data Bulletin" No: 505, 506, 508 of the trade name "Sinclair Petrochemicals Company" discloses the possibility of using vulcanizates based on polyureas and poly (urea urethane) products prepared by polyhydroxy, 1 1 2 63040 that is, diene polymers and / or copolymers containing more than two reactive functions to react with diisocyanates in the manufacture of outer tires for agricultural and automotive use.

However, the properties obtainable with these vulcanizates are not good enough for such use, as the researchers of the Rubber and Plastics Research Association (RAPRA) have specifically stated in their November-December 1971 communication "Bulletin no: 6, Vol. 25" and in the study report "Liquid Rubber for reinforced Rubber Products, A technical and economic Assessment ", published by the" Rubber and Plastics Research Association of Great Britain ", where Daniel, Needham and Pyne argue that" experiments lead to the assumption that there is only a small chance of success in the chain. elongation and crosslinking by commercially available functional liquid polymers containing terminal carboxyl or hydroxyl functions ". These authors also argue that the production of vulcanizates from such commercially available liquid polymers with high Shore hardness for use in outer rings requires the use of fillers and vulcanizing agents to a very large extent, leading to too poor volcanic page 17) that cannot be used on outer tires.

At a conference organized by the International Union of Pure and Applied Chemistry (IUPAC) in September 1973 in Aberdeen, Great Britain, a representative of RAPRA had stated that the reaction of liquid polyfunctional diene polymers indeed, it has a Shore hardness which is close to that of the previously known, i.e. non-functional, diene elastomers, but whose mechanical properties in combination are insufficient and therefore cannot be used in the manufacture of outer rings.

FR patents 2,187,805, 2,187,806, 2,187,807, 2,187,808, 2,187,809, 2,187,842 disclose the use in the manufacture of treads for outer tires of vulcanizates prepared by incorporating liquid polyfunctional polymers and / or copolymers. that is, containing more than two functions), to react in the same way with polyfunctional polyisocyanates, the reaction components being present to such an extent that both chain elongation and crosslinking, i.e. vulcanization, occur in one and the same phase. Examining the examples presented in these patents based on tests performed on outer tires having a tread made of such vulcanizates, it will be found that these vulcanizates have the same disadvantages as those mentioned above.

A means has now been provided to overcome the above-mentioned disadvantages by surprisingly inventing a process for the preparation of elastomers derived from liquid functional diene polymers which have sufficiently good properties to be used as a main component in blends for making outer rings.

The invention therefore relates to a process for the preparation of vulcanized elastomers. The invention is characterized in that one or more reactive liquid diene prepolymers having a hydroxyl functional group and a degree of functionality of 1.8 to 2.0, alone or in combination with one or more bifunctional non-diene polymers, non-functional liquid polymers or low molecular weight bifunctional compound, and which contains thoroughly mixed reinforcing agents and vulcanizing or crosslinking agents commonly used in the vulcanization of outer rings, is mixed with a bifunctional hydrocarbon chain extender having the number of reactive liquid prepolymer or prepolymers is 1, and that said mixture is brought to a temperature of 20-125 ° C in a first step, thereby providing only an extension of the hydrocarbon chain of the prepolymer, and in a second step to a temperature above 140 ° C to crosslink, i.e. vulcanize, the product obtained in the first step.

4,63040

In order for vulcanizates to be used as treads and / or sidewalls of outer tires, these vulcanizates as such often have to represent a compromise between conflicting properties. It has previously been considered necessary in order for these vulcanizates to be used as the main component in the mixture used to make the treads and / or sides of the outer ring, to use a mixture based on oil-free elastomers with 50 parts of rubber (reference mixture) required: Shore hardness less than 70, elongation at break 100%, 2 measured after the third draw, 12.0 to 25.0 kp / cm, degree of crosslinking at 60 ° C equal to or greater than 55 copolymer of butadiene and styrene with 25% styrene equal to or greater than 60 for a copolymer of butadiene and styrene with 12% styrene equal to or greater than 65 for polybutadiene-cis-1,4, further elongation at break and a tensile strength of 2 equal to or greater than 370% and 120 kp / cm for polybutadiene, 2 equal to or greater than 400% and 160 kp / cm for a copolymer of butadiene and styrene containing 12% styrene, equal to or greater than 2 than 420% and 180 kp / cm for a copolymer of butadiene and styrene with 25% styrene, while the coefficient of friction SRT at 20 ° C is greater than 19 for polybutadiene, 35 for a copolymer of butadiene and styrene with 12% styrene , and is 40 with a copolymer of butadiene and styrene with 25% styrene.

According to the invention, the prepolymers used are liquid polymers having a molecular weight of less than 50,000, and preferably from 1,000 to 20,000, and whose hydrocarbon chain is a homopolymer of conjugated dienes or a copolymer of dienes conjugated to each other or to vinyl aromatic compounds. polybutadiene, polyisoprene, polypiperylene, polychloroprene, polypentadiene, butadiene and congeners of butadiene and isoprene, butadiene or isoprene, a compound belonging to the category of vinyl nitriles, such as a copolymer of butadiene or isoprene and acrylonitrile or methacrylonitrile, 5 63040 terpolymers of dienes conjugated to each other or with vinyl aromatic compounds and / or vinyl nitriles. The monomer units are joined to the chain either statistically or in segments, and the relative amounts of monomers can vary.

The functionality of a prepolymer is determined by dosing the functions it contains, determining the molecular weight of the prepolymer, and performing a coupling reaction to the function in the prepolymer using a suitable bifunctional reagent, i.e., using either a polyaddition or polycondensation reagent. The coupling reaction results in a gelled product that is virtually insoluble if the number of functions contained in the hydrocarbon chain is greater than 2, or if the functionality is equal to or less than 2, to a soluble compound whose molecular weight can be determined by methods known in the art. . Functionality can be readily determined from the known equation presented on page 438 of the Burnett publication, "Mechanism of Polymer Reactions", published by Interscience Publishers.

These functional prepolymers can be used alone or in combination with one or more bifunctional non-diene polymers, such as polyethers, polyesters, polyisobutylene, or in combination with low molecular weight bifunctional compounds, including saturated small alcohols, or saturated dialkyl alcohols. with functional polymers or copolymers such as polybutadiene, polyisoprene, copolymer of butadiene and styrene, etc.

The term "hydrocarbon chain-extending bifunctional compounds" refers to organic compounds having reactive groups that can react with the reactive groups of the prepolymer to form polyaddition or polycondensation products. Examples are compounds with isocyanate functions, e.g. tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate. As reinforcing agents, products known and commonly used for the manufacture of outer tires are used, e.g. carbon black, silica, metal reinforcing elements, glass, 63040, etc., plasticizers and / or filler oil. These additives must be dispersed very homogeneously in the functional prepolymer when applying the process of the invention. The term "vulcanization" or crosslinking agents "refers not only to the actual substances such as sulfur, peroxides, etc., but also to vulcanization accelerators. Such vulcanization accelerators are either compounds which are inert to the chain-extending bifunctional compound, or compounds which are normally reactive with the chain-extending compound by polyaddition or polycondensation at a suitable temperature, but which are made inert in this respect. Thus, all previously known compounds can be used, such as primary and secondary amines, mercapto-benzothiazole sulfeneamides, and especially N-diisopropylmercapobenzothiazole sulfeneamide, such as N-dicyclohexylmercaptobenzo-thiazole sulfeneamide, such as thiocarboxylate, thiocarboxylate - (diisopropylthiophosphoryl) disulfide, bis- (diethylthiophosphoryl) trisulfide, zinc dibutyl dithiophosphate, guanidines, mercaptotriazines, e.g. bis- [α] N-ethylamine, 6-N-diethylamine, 1,3,5-triazine disulfide. When applying the process according to the invention, suitable polyaddition catalysts can also be added.

The invention is illustrated below by means of some examples.

Example 1 In this example, two experiments A1 and B1 were performed to compare the properties of the reaction product of commercially available hydroxylated polybutadiene and diisocyanate with the properties of the reaction product of non-functional polybutadiene (Experiment A), as well as to compare butadiene and styrene -%) of the reaction product between the hydroxylated copolymer and the diisocyanate to the properties of the copolymer of butadiene and non-functional styrene (about 22% by weight) (Experiment B). In both of these experiments, the ratio of the number of NCOs of the reactive groups extending the carbon-hydrogen chain to the number of OHs of the reactive groups of the prepolymer after mixing was equal to 1.

The operating conditions and the results obtained are indicated in Table I below.

6 30 4 0

TABLE I

Test A 1 .......... Test B 1

Elastomers 100 Hydroxylated Comparison "SBR CS 15" Comparison by weight of polybutadiene, "Solprene 200" f = 2.5-2.8 "SBR 1500" "R-15M",

Vulcanizing system- 'S / "Santocure' · S /" Santocure ”as a scaffold, parts by weight - 1 / 1.6 - 1.6 / 1

Stearic acid - 1.5 - 2

Example black "HAF", 55 50 55 50 "40 10 NA" - 1

Toluene diisocyanate 7.7 to 8.1

ZnO 4 - 3 "Sundex 8125" - 8 - 5

Length and temperature of vulcanization treatment, min / ° C 40/140 40/140 60/140 60/140

Elongation at break 100% kp / cm 31.4 19.2 34.6 19.0

Degree of crosslinking at 60 ° C 58 77.9 54 67

Fragility indices according to Scott1

Elongation at break,% 297 420 404 520

Fracture, kp / cm 144 139 190 270

Shore hardness 72 69 75 68 S is sulfur "R-15-M" is liquid hydroxylated polybutadiene sold under the trade name Arco f is the degree of functionality of the prepolymer "Solpr§ne 200" is the polybutadiene "Santocure" marketed by Phillips is the product N-cyclohexyl Trademark of 2-benzothiazole sulfenamide, sold by Monsanto "SBR CS 15" is a copolymer of butadiene and liquid hydroxylated styrene with 25% by weight of styrene, sold by Arco "SBR 1500" is a copolymer of butadiene and styrene with 25 -% styrene, sold by Shell 8 63040 "Sundex, 8125" is 70% aromatic ¢ 51 jy, Mole weight 380, density 0.996, sold by Sun Oil "4010 ΝΑ" is N-isopropyl, N r-phenylparaphenyldiamine. It was immediately found unnecessary to vulcanize the resulting elastomers with sulfur because the modulus and hardness are already too high for the product to be used in the outer rings, whereas the elongation at break was instead far too small for such use. Thus, the properties of polymers prepared from prepolymers having a degree of functionality greater than 2 are insufficient for the production of outer rings even if the NCO / OH ratio is equal to 1.

Example 2 In this example, Experiment A2 was performed, in which a hydroxylated prepolymer of butadiene and styrene (the latter having about 25% by weight) having a functionality f of 1.97 and a molecular weight of 6000 was reacted with methylene diphenyl diisocyanate. The ratio of the number of NCOs of the reactive groups extending the hydrocarbon chain to the number of OHs of the reactive groups of the prepolymer after mixing was equal to 1. The vulcanizing agents were added at the same time as the polyaddition reagent. After stirring, the mixture was heated at 140 ° C for 1 hour to carry out polyaddition and vulcanization reactions in the same step. The experiment was carried out with the following mixture: 100 parts of premix copolymer, 50 parts of carbon black "HAF", 1.7 parts of dicyclohexylamine benzothiazylsulfenamide, 1.5 parts of sulfur, 4 parts of ZnO, 3 parts of iron acetylacetonate 9x10 g of 100 g of prepolymer.

The properties are indicated in the following Table II, where they have been compared with the properties of the non-functional mixed polymer (SBR 1500) used as a reference product.

TABLE II

Features Experience: A2 Comparison: "SBR 1500"

Elongation modulus 100%, kp / cm2 20.1 19.0

Degree of crosslinking at 60 ° C 50.3 67

Fragility Indices, Scott:

Elongation at break,% 503 590 2

Fracture stress, kp / cm 135 270

Shore hardness 68 68 r 5 63040

It is observed that a copolymer having the same properties as the reference mixture cannot be obtained, and it is especially noted that the breaking strength and the degree of bonding are poor. This is because the crosslinking or vulcanization steps cannot be adjusted. Example 3

The procedure of Example 2 was repeated using the same conditions, except that the mixture was heated at 110 ° C for 20 minutes and then at 160 ° C for 20 minutes so that the addition and vulcanization steps were clearly separated. The properties of both elastomers are indicated in the following Table III.

TABLE III

Features Experience: A3 Comparison: SBR 1500

Elongation at break 100%, kp / cm 2 20.9 19.0

Degree of crosslinking at 60 ° C 60.7 67

Fragility Indices, Scott

Elongation at break,% 540 580 2

Fracture stress, kp / cm 256 270

Shore hardness 68 68

Comparing the properties of the copolymer A3 with the properties of the copolymer A2 of Example 2, it is found that the copolymer A3 has a significantly better breaking strength (about 100 kp / cm) and about a 20% higher degree of crosslinking at 60 ° C. In addition, it is noted that the copolymer A3 has approximately the same properties as the previously known copolymer.

Rotation tests were performed on outer tires, some of which had a copolymer A3 according to the invention as the main component in the tread, and others had a previously known copolymer for comparison in order to compare the friction and wear coefficients, i.e. the weight loss due to wear.

The wear factor is expressed by the ratio: weight loss of the "test" outer tire x 100 weight loss of the reference outer tire 63040 10

The coefficient of friction was measured at 20 ° C using a "Skid Resistance Tester" (SRT) marketed by Stanley.

The weight losses were determined after the vehicle had traveled a certain track, and the index value of the reference outer tire was recorded as 100.

The results obtained are marked in the following table purple.

TABLE purple

Properties Copolymer; A3 Comparison: SBR 1500

Friction coefficient index 65 45

Weight loss,% 125 100

It is noted that although the coefficient of friction of the outer ring provided with the tread containing the copolymer A3 was about 40% higher than the coefficient of friction of the reference outer tire, the compromise between wear and adhesion was clearly better than the blood of the beauty tire11a.

Examples 4-9 In this series of examples, copolymers were prepared using 100 parts of a hydroxylated copolymer of butadiene and styrene (the latter used in 12% by weight) having a functionality number f = 1.97 and a molecular weight of 6000 as a pre-copolymer. The experiments were performed using the following additives: "black" 50 parts, methylenediphenyl diisocyanate to such an extent that the NCO / OH ratio of the finished mixture = 1.0 parts of sulfur 1.5 parts, dicyclohexylamine benzothiazylsulfenamide amide 1.7 -3 parts, ZnO 4 parts, iron acetylacetonate 9x10 g / 100 g premix After homogenization, heating was performed at 110 ° C for 20 minutes and then at 160 ° C for 20 minutes. The results obtained are indicated in the following Table IV, in which the properties of the products prepared are compared with those of the copolymer "stereo 700" of butadiene and styrene used as a control, in which the styrene content is about 12% by weight.

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TABLE IV

Comparison

Properties Example No. "StörSon 4 5 6 7 8 9 700"

Elongation at break 100% t7.4 17.2 17.0 16.7 17.2 17.3 21.7 kp / cnr

Degree of crosslinking 62.6 62.6 62.8 62.1 62.2 61.8 70 60 C

Fragility Indices, Scott:

Elongation at break,% 600 620 633 613 603 600 480

Fracture stress, kp / cm2 257 257 268 257 260 242 180 ISO hardness 58 60 59 59 59 59 66

It is found that the properties of the copolymers obtained are approximately identical and that the process according to the invention is very reproducible.

Rotation tests were performed on outer tires containing the copolymer of Example 4 as the main tread component on the one hand and the SBR 1500 copolymer used as a reference on the other hand in order to compare the coefficients of friction and the weight losses due to wear. The results are shown in Table IVa below.

TABLE IVa

Features According to Example 4 Comparison: "SBR 1500"

made of SBR

Friction coefficient index 45 45

Weight loss due to wear,% 80 100

It will be appreciated that the compromise between wear and adhesion of the outer ring provided with the tread containing the elastomer as the main component is better.

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Example 10

An elastomer containing an oil as an additive was prepared using a hydroxylated copolymer of butadiene and styrene having 12% by weight of styrene having a functional number f = 1.97 and a molecular weight of 6,000 as a pre-copolymer, and containing methyl as a hydrocarbon chain extender isocyanate to such an extent that the NCO / OH ratio of the finished mixture = 1.0. The experiment was performed using the following blend formula: 100 parts of premix copolymer, 390 molecular weight naphthenic oil and density of 0.946 ("Circosol 2 XH", sold by Sun Oil), 30 parts, carbon black "ISAF" 65 parts, ZnO 5 parts, iron acetylacetyl -3 nats 45 x 10 g / 100 g of prepolymer, 1.17 parts of sulfur, 1.56 parts of bis- (diisopropylthiophosphoryl disulfide), 0.482 parts of mercaptobenzothiazothiazole monosulfide. Heated at 110 ° C for 20 minutes and then at 155 ° C for 22 minutes. The properties of the product thus prepared were compared with those of a reference copolymer made of butadiene and styrene to which 37.5 parts of the aromatic oil "Solpröne 384", sold by Phillips Petroleum, had been added and vulcanized for 60 minutes at 140 ° C using the following mixture formula: "Solprene 384" 100 parts, carbon black "ISAF" 50 parts, stearic acid 2 parts, ZnO 1 part, 4010 NA 1 part, "Santocure" 1 part, sulfur 1.8 parts. The properties of the obtained volcanic escorts are indicated in Table V below.

TABLE V

Features SBR according to the invention Comparison: "SolprSne _384"

Elongation modulus 100% 195 188 kp / cin

Degree of crosslinking 80 70 at 60 ° C

Fragility Indices, Scott

Elongation at break,% 377 420

Fracture stress, kp / cm ^ 210 200

Shore hardness 63.5 65

It is found that the properties of the oil-containing vulcanizate according to the invention remain superior to the previously known elastomer, which also contains oil as an additive.

Claims (4)

Process for the preparation of vulcanized elastomers, characterized in that one or more reactive liquid diene prepolymers having a hydroxyl functional group and a degree of functionality of 1.8 to 2.0, alone or in combination with one or more non-functional bifunctional non-diene polymers, with a liquid polymer or a low molecular weight bifunctional compound, and which, when thoroughly mixed with reinforcing agents and vulcanizing agents commonly used in the vulcanization of outer rings, is mixed with a bifunctional carbon-carbon chain extender in the ratio of the number of reactive groups to the number of reactive groups of the reactive liquid prepolymer or prepolymers is 1, and that said mixture is brought into the first step; to a temperature of 20 to 125 ° C, whereby only the prolongation of the hydrocarbon chain of the prepolymer is obtained, and in a second step to a temperature of more than 140 ° C to crosslink, i.e. vulcanize, the product obtained in the first step. 1 3 63040 Process according to Claim 1, characterized in that the reactive liquid diene prepolymer has a molecular weight of from 1,000 to 20,000. Process according to Claim 1, characterized in that the reactive liquid diene prepolymer is a hydroxylated copolymer of butadiene and styrene and in that the carbon-hydrogen chain extension compound is a diisocyanate. Use of vulcanized elastomers for the production of new or retreaded treads and / or sidewalls of outer tires, characterized in that the elastomers are prepared by mixing one or more reactive liquid diene prepolymers having a hydroxyl functional group and a degree of functionality of 1.8 to 2.0, alone or in combination with one or more bifunctional non-diene polymers, non-functional liquid polymers or low molecular weight bifunctional compounds and thoroughly mixed with reinforcing agents and vulcanizing agents, i.e. 63040 crosslinking agents commonly used in the vulcanization of outer rings, the bifunctional structure is an isocyanate, in an amount such that the ratio of the number of reactive groups of the carbon chain extender in the finished mixture to the reactive liquid prepolymer or the number of reactive groups in the prepolymers is t, and by subjecting said mixture in a first step to a temperature of 20-125 ° C, providing only an elongation of the hydrocarbon chain of the prepolymer, and in a second step to a temperature above 140 ° C to crosslink the vulcanized product. 1! ,>, - 63040 15