CH643279A5 - Thermoplastic, elastomeric composition - Google Patents

Description

This invention relates to a thermoplastic elastomeric composition which contains a mixture of thermoplastic polyolefin resin and monoolefin copolymer rubber which has been vulcanized and at most only a small part of which has remained unvulcanized, and optionally extender oil.

Thermoplastics are preparations which can be deformed by means of pressing processes or in some other way and can be reprocessed at temperatures above their melting or softening point. Thermoplastic elastomers are materials that have both thermoplastic and elastomeric properties, i.e. the materials behave like thermoplastics, but have the physical properties like elastomers. Molded articles can be formed from thermoplastic elastomers by means of extrusion, injection molding or compression molding, without the time-consuming vulcanization step that is required with conventional vulcanizates. The time saved to effect vulcanization creates significant manufacturing advantages. Furthermore, the thermoplastic elastomers can be processed again without regeneration, and many thermoplastics can also be thermally welded.

Block copolymers, which alternately have “hard” and “soft” segments within the copolymer chain, form a generally known class of thermoplastic elastomers. Other classes of thermoplastic elastomers derived from cheaper and readily available raw materials include thermoplastic blends of partially vulcanized mono-olefin interpolymer rubber and polyolefin resin and dynamic partially vulcanized blends of mono-olefin mixed polymer rubber and polyolefin resin, see W.K.

Fischer, US Pat. Nos. 3,758,643 and 3,806,558 products which have the properties as thermoplastics are obtained if the conditions are controlled so that only partial vulcanization is obtained. Although partial vulcanization can increase the strength of the product, the tensile strength is still so low that potential uses for these materials are limited. The present invention encompasses vulcanizates with significantly increased strength, but which are nevertheless thermoplastic.

Thermoplastic elastomeric compositions have now been found which contain mixtures of polyolefin resin and monoolefin mixed polymer rubber, the mono-olefin mixed polymer rubber being vulcanized and at most only a small proportion of it having remained unvulcanised, but the mixtures still remain processable as thermoplastics and have improved physical properties in comparison to the previously known non-vulcanized or partially vulcanized mixtures. It has been found that if the proportion of resin in the mixture is above certain critical limits which change somewhat with the particular resin, the rubber and the selected means for compounding, the compositions according to the invention are elastomeric and yet thermoplastic. The weight Wp of the thermoplastic polyolefin resin makes up 25 to 85%, preferably 30 to 70%, and the weight Wr of the monoolefin copolymer rubber in the non-vulcanized state makes up 75 to 15%, preferably 70 to 30%, of the sum WP + Wr. The weight where of the extender oil

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is 0 to 300% of the aforementioned weight Wr. The quotient (Wo + Wr) / Wp is equal to or greater than 0.33. The compositions according to the invention can be processed as thermoplastics, although they are crosslinked to a point where the rubber components are almost completely insoluble in the customary solvents. Other ingredients may be present. If the masses contain extender oil, the weight WP is preferably 35 to 65% and the weight Wr is preferably 65 to 35% of the total WP + Wr. Regardless of whether the masses contain extender oil or not, they can be processed as thermoplastics.

The suitable method for evaluating the extent of the vulcanization of the rubber depends on the particular constituents present in the mixtures. In this connection, the substantially complete gelation of, for example, 96% or more is not always a necessary criterion for the required degree of vulcanization, because of the differences in molecular weight, the molecular weight distribution and other variables for the different types of monoolefin polymer rubber, that affect gel determination regardless of crosslink density. Determining the crosslink density of rubber is another method of determining the extent of vulcanization, but this must be determined indirectly because the presence of the resin interferes with the determination. The rubber which is present in the mixture is vulcanized separately under the same conditions in terms of time, temperature and amount of the vulcanizing agent as are used in the preparation of the composition according to the invention, after which the crosslinking density is determined. The rubber is thus vulcanized to such an extent that its cross-linking density (number of cross-links divided by the Avogadro number) per ml of rubber is greater than 7 x 10 ~ 5 mol. This results in a very substantial improvement in the tensile strength, and this can serve as a suitable measure of the extent of networking, which is directly related to the practical use of the mass. As a rule, the extent of the crosslinking of the rubber is sufficient if the tensile or The tensile strength of the mass is at least 6 x 106 Pa, preferably 10 x 106 Pa, greater than that of the unvulcanized mass. Surprisingly, the present elastomeric compositions with such high strength are still thermoplastic, in contrast to the thermosetting or thermosetting elastomers.

Although vulcanizable rubbers are thermoplastic in the uncured state, they are normally classified as thermosetting materials because they are exposed to the irreversible process of thermosetting to an unprocessable state. The compositions according to the invention can be processed, although the rubber is largely vulcanized. Surprisingly, they can be made from mixtures of rubber and resin by treatment with vulcanizing agents in such amounts and under such time and temperature conditions that they are known to provide fully vulcanized products in the static vulcanization of the rubber in molds, and indeed the rubber has gelled to an extent that is characteristic of such a vulcanization state. The heat-curing state can be avoided in the compositions according to the invention by simultaneously kneading and vulcanizing the mixtures. Thermoplastic compositions according to the invention are therefore produced by subjecting the unvulcanized monoolefin copolymer rubber, the thermoplastic polyolefin resin and vulcanizing agent to a temperature at which the polyolefin resin is in the softened state

643279

is located, mixed and the mixture is continuously kneaded at the vulcanization temperature, using a conventional kneading device, for example a Banbury mixer, a Brabender mixer or certain mixing extrusion devices, until the vulcanization is complete.

The ingredients without a curing agent can be mixed at a temperature sufficient to soften the polyolefin resin, or more usually at a temperature above its melting point if the resin is crystalline at ordinary temperatures. After the resin and rubber are thoroughly mixed, the vulcanizing agent can be added. Heating up and continuous kneading at vulcanization temperatures are generally suitable to allow the vulcanization reaction to proceed in a few minutes or even faster, but if shorter vulcanization times are desired, higher temperatures can be used. A suitable range of vulcanization temperatures ranges from about the melting temperature of the polyolefin resin (about 120 ° C in the case of polyethylene and about 175 ° C in the case of polypropylene) to 250 ° C or more; typically a range of about 150 to 225 ° C. A preferred range of vulcanization temperatures is about 180 to about 200 ° C. In order to obtain thermoplastic masses, it is essential that the mixing be continued without interruption until the vulcanization has ended. If significant vulcanization occurs after mixing has ceased, a thermoset, non-processable vulcanizate can be obtained.

In addition, the respective results obtained by the dynamic vulcanization process described above are a function of the particular rubber vulcanization system selected. The conventionally used vulcanizing agents and vulcanizing agent systems are useful for vulcanizing mono-olefin mixed polymeric rubbers to produce the improved compositions according to the invention, but it appears that it has not been known hitherto that some vulcanizing agents, especially certain peroxides, have the polyolefin resins during dynamic Vulcanize to such an extent that the desired results are not achieved. Similarly, although commercially available monoolefin copolymers rubbers can be used to make the improved compositions, narrow molecular weight distribution rubbers form thermoplastic compositions with improved strength properties compared to monoolefin copolymer rubbers that are less effectively crosslinked in the vulcanization process . Polydispersity values (weight average molecular weight divided by number average molecular weight) of less than about 3.5, and especially less than 3.0 or 2.6, are desirable for the mono-olefin interpolymer rubber. In addition, for the reproducible production of processable thermoplastic compositions, it is necessary that the weight WP of the thermoplastic polyolefin resin is at least 25% of the total WP + Wr. It is therefore possible to obtain dynamically vulcanized vulcanizates that cannot be processed, even before complete gelation has occurred, or to obtain only minor improvements in tensile strength through vulcanization. A few simple trials by those skilled in the art using available rubbers and vulcanizing agent systems will suffice to test their applicability to making the improved compositions of this invention.

The new masses can all be processed in an internal mixer into products which, after the resin phase is in the

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melted state, after transfer to the rotating rollers of a rolling mill form an essentially continuous skin. The skins can be reprocessed in the internal mixer by being converted back to the plastic state (molten state of the resin phase) after reaching temperatures above the melting points of the resin phases, but again after the molten product has passed through the rollers of the rolling mill, a continuous process takes place Fur forms. In the above sense, “processable” should be understood.

If the determination of extractable materials is a suitable yardstick for the extent of the vulcanization, the improved thermoplastic compositions are produced by vulcanizing the mixtures until the rubber has been vulcanized to such an extent that it contains no more than 3% by weight of cyclohexane are extractable at 23 ° C and preferably less than 2% by weight can be extracted by cyclohexane at 23 ° C. In general, the less extractable rubber there is, the better the properties; Compositions are particularly preferred which have essentially no rubber (less than 0.5% by weight) which can be extracted by cyclohexane at 23 ° C. The gel content, which is given as a percent gel, can be determined by the method of US Pat. No. 3,203,937, in which the amount of insoluble polymer is determined by soaking the sample in cyclohexane at 23 ° C. for 48 hours and weighing the dried residue, making appropriate corrections according to the properties of the mass. Corrected initial and final weights are therefore used, to which end the initial weight is used to subtract the weight of the components that are soluble in cyclohexane, other than rubber, such as extender oils, plasticizers and components that make the resin soluble in cyclohexane. Any insoluble pigments, fillers, etc. are subtracted from both the initial and final weights.

When using the crosslinking density as a measure of the extent of vulcanization, which characterizes the improved thermoplastic compositions, the rubber is vulcanized alone to such an extent that its crosslinking density is greater than 7 x 10-5 mol per ml of rubber, preferably greater than 1 x 10 ~ 4 mol / ml rubber. The mixture of rubber and polyolefin resin is then, under the same conditions, with the same amount of vulcanizing agent, based on the rubber content of the mixture, as was required for the rubber alone.

vulcanized with continuous kneading. The crosslinking density determined in this way can be regarded as a measure of the extent of the vulcanization which provides the improved compositions. However, from the fact that the amount of vulcanizing agent is based on the rubber content of the mixture and that it is the amount that gives the rubber alone the above crosslinking density, it cannot be concluded that the vulcanizing agent does not react with the resin or that there is no reaction between resin and rubber. Very significant reactions can occur here, but to a limited extent. However, the assumption that the crosslink density determined as described provides a useful approximation to the crosslink density of the rubber in the thermoplastic composition is confirmed by the thermoplastic properties and by the fact that a large part of the resin is removed from the composition by solvent el extraction at high temperatures, for example by extraction with decalin at the boiling point.

The crosslink density of rubber is determined according to the Flory-Rehner equation, J. Rubber Chem. And Tech., 30,

Page 929. The Huggins solubility parameter for cyclohexane used in the calculation has a value of 0.315 according to Holly, J. Rubber Chem. And Tech., 39 1455. The crosslink density corresponds to half the network structure chain density v, determined without the resin. The crosslinking density of the rubber in the compositions according to the invention is therefore to be understood below so that it corresponds to the value which was determined in the manner described for the rubber which is contained in the composition. Compositions which are particularly preferred meet both conditions for the extent of the crosslinking of the rubber, namely with regard to the crosslinking density and with regard to the content of rubber which can be extracted by cyclohexane at 23 ° C.

The monoolefin copolymer rubber is a copolymer of ethylene or propylene and at least one other alpha-olefin of the formula CH2 = CHR,

wherein R represents an alkyl group having 1 to 12 carbon atoms, which may additionally, but only in small amounts, contain units of at least one copolymerizable diene. However, a saturated monoolefin copolymer rubber, commonly referred to as "EPM" rubber, for example a copolymer of ethylene and propylene, can be used. Satisfactory examples of monoolefin unsaturated copolymer rubber, commonly referred to as "EPDM" rubber, are the products from the polymerization of monomers comprising two monoolefins, usually ethylene and propylene, and a minor amount of non-conjugated diene. Suitable alpha-olefins of the formula CH2 = CHR, in which R is hydrogen or an alkyl group having 1-12 carbon atoms, are, for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-pentene, 4- Methyl-1-pentene, 3,3-dimethyl-1-butene, 5-methyl-1-hexene, 1,4-ethyl-1-hexene and others include. Satisfactory non-conjugated dienes include straight chain dienes, such as 1,4-hexadiene, cyclic dienes, such as cyclooctadiene, and bridged cyclic dienes, such as ethyl-orborbornene. Grades of EPM and EPDM rubber that are suitable for the practice of this invention are commercially available; see Rubber World Blue Book, 1975 edition, Materials and Compounding Ingrédients for Rubber, pages 403 and 406-410.

Suitable thermoplastic polyolefin resins include crystalline, high molecular weight, solid products from the polymerization of one or more monoolefins, either by high pressure or by low pressure processes. Examples of such resins include isotactic and syndiotactic monoolefin mixed polymer resins, and typical resins of this type are commercially available. Examples of satisfactory clefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl -l-hexene and their mixtures. Commercially available thermoplastic polyolefin resins, preferably polyethylene and polypropylene, can advantageously be used in the practice of the invention, with polypropylene being preferred.

Any vulcanizing agent or system which is suitable for the vulcanization of monoolefin rubber can be used in the practice of the invention, for example peroxide or azide vulcanizing agents and sulfur vulcanizing agents with accelerators. The combination of a maleimide with disulfide accelerator can be used. With regard to satisfactory vulcanizing agents and vulcanization systems, reference is made to columns 3 + 4 of US Pat. No. 3,806,558. As explained above, are so big

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Amounts of the vulcanizing agents are used so that at most a small part of the monoolefin copolymer rubber remains unvulcanized, which can be determined from the increase in tensile strength, the crosslinking density, the sol content (rubber extractable by cyclohexane at 23 ° C.), the crosslinking density or a combination thereof. Peroxide vulcanizing agents are advantageously used in reduced amounts together with other vulcanizing agents, such as sulfur or bismaleimides, the total amount of the vulcanizing agents should be so large that at most a small part of the rubber remains unvulcanized. High energy radiation is also useful as a vulcanizing agent, but vulcanizing systems containing sulfur vulcanizing agents are preferred.

The properties of the thermoplastic compositions of this invention can be modified either before or after vulcanization by adding ingredients which are conventional for compounding mono-olefin mixed polymer rubber, polyolefin resin and mixtures thereof. Examples of such constituents are carbon black, silicon dioxide, titanium dioxide, colored pigments, clay, zinc oxide, stearic acid, accelerators, vulcanizing agents, sulfur, stabilizers, anti-degradation agents, processing aids, adhesives, tackifiers, plasticizers, wax, pre-vulcanization inhibitors, discontinuous fibers such as wood cellulose fibers, and Extender oils. The addition of carbon black, extender oil or both, preferably before dynamic vulcanization, is particularly recommended. Carbon black improves tensile strength, and extender oil can improve oil swell resistance, thermal stability, hysteresis, cost, and permanent deformation of the thermoplastic composition. Aromatic, naphthenic and paraffinic extender oils are satisfactory. The addition of extender oil can further improve processability. With regard to suitable extender oils, reference is made to Rubber World Blue Book, op. Cit., Pages 145-190. The amount of extender oil added depends on the properties desired, the upper limit being dependent on the compatibility of the respective oil and the components of the mixture, the limit being exceeded if the extender oil exits excessively. Typically 5-300 parts by weight of extender oil are added to 100 parts by weight of the mixture of rubber and polyolefin resin. Usually about 30 to 250 parts by weight of extender oil are added to 100 parts by weight of rubber present in the mixture, with amounts of about 70 to 200 parts by weight of extender oil per 100 parts by weight of rubber being preferred. Typical additions of carbon black include about 40-250 parts by weight of carbon black per 100 parts by weight of rubber and typically about 20-100 parts by weight of carbon black per 100 parts of total weight of rubber and extender oil. The amount of soot that can be used depends at least in part on the type of soot and the amount of extender oil used. The amount of extender oil depends at least in part on the type of soot. High viscosity rubbers are more oil expandable.

The thermoplastic elastomeric compositions according to the invention are suitable for the production of a variety of objects such as tires, tubes, belts, seals, molds and molded parts. You are special

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suitable for the production of objects by means of extrusion, injection molding and compression molding. They are also suitable for modifying thermoplastic resins, especially polyolefin resins. The compositions can be mixed with thermoplastic resins using conventional mixing devices. The properties of the modified resin depend on the amount of the compound mixed. In general, the composition is used in an amount such that the modified resin contains about 5 to 25 parts by weight rubber per about 95 to 75 parts total weight resin.

There now follows a description of the preferred embodiments.

To explain the invention, suitable polypropylene with low flowability (specific weight 0.902.11% yield strength) is used in general in the proportions given in Table I with EPDM rubber in a Brabender mixer at 100 rpm with an oil bath temperature of 182 ° C. 4 Minutes after which the polypropylene has melted and a uniform mixture is obtained. Afterwards it can be assumed that the temperature of the Brabender mixer corresponds to the temperature of the oil bath. Zinc oxide (5 parts) and stearic acid (1 part) (parts by weight per 100 parts by weight of rubber) are added and mixing is continued for one minute. The order of mixing can be changed, however, all of the foregoing ingredients should be substantially completely added and mixed before vulcanization begins. Tetramethylthiouram disulfide (TMTD) and 2-bis (benzothiazolyl) disulfide (MBTS) are added and mixing is continued for half a minute. Then add sulfur and continue mixing until the maximum Braender consistency is reached, then mix for another three minutes. The mass is removed, skins are produced on a rolling mill, these are returned to the Brabender mixer and mixed at the temperature specified above for two minutes. The skins are again produced from the mass on a rolling mill and this is then subjected to the compression set at 220 ° C. and cooled under 100 ° C. under pressure before being removed. The properties of the molded skins are measured and recorded, the values of the various masses being given in Table I. The crosslink density is expressed by the symbol v / 2, expressed in mol / ml rubber. Approaches 1, 3, 6 and 10 are controls that do not contain any vulcanizing agents. The approaches 2,4,5,7,8,9 and 11 explain the masses of the invention.

The values show that the compositions according to the invention are characterized in that less than 2% by weight of rubber in cyclohexane can be extracted at 23 ° C, i.e. that the gel content is greater than 98%, and that they have higher crosslinking densities and tensile strengths, which are more than 10 x 106 Pa greater than in the uncured controls. All masses can be processed as thermoplastics and can be reprocessed without requiring any regeneration in contrast to ordinary vulcanizates. All of the masses in Table I are elastomeric, i.e. they have the property of rapidly rebounding into their original shape after being deformed considerably. There is no clear definition of the degree of deformation a product should withstand for an elastomer, but it should generally be at least 100%.

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Table I

Approach no.

l

2nd

3rd

4th

5

6

7

8th

9

10th

il

Ingredients (in addition to zinc oxide and stearic acid)

Parts by weight

EPDM rubber

75 *

75

70

70

65

60

60

55

45

30th

30th

Polypropylene

25th

25th

30th

30th

35

40

40

45

55

70

70

TMTD

-

0.375

-

0.7

0.65

-

0.6

0.55

0.45

-

0.75

MBTS

-

0.188

-

0.35

0.33

-

0.3

0.28

0.23

-

0.38

sulfur

-

0.75

-

1.4

1.3

1.3

-

1.2

1.1

0.9

1.5

Gel, percent

-

99.0

60.0

99.6

99.0

67

98.6

98.9

98.6

93

99.5

Swell percent

-

245

543

187

150

316

145

148

106

91

73

i) / 2xl0s

0

12.3

0

16.4

16.4

0

16.4

16.4

16.4

0

14.5

Tensile strength Pa x 105

11.2

130

19.7

183

256

50.4

248

251

280

145

294

100% module, Pa xl 05

12.6

39.4

20.4

56.9

77.3

49.3

81.6

86.5

115

137

139

Young module, Pax IO5

58.3

133

111

222

318

730

593

835

1656

4697

4436

Elongation at break,%

180

480

180

470

460

190

530

550

560

370

580

It is assumed that it is a terpolymer of 55% by weight of ethylene, 42.5% by weight of propylene and 2.5% by weight of diene, the polydispersity being greater than 20 and the Mooney viscosity 55 (ML- 8.100 ° C). It is assumed that the rubber in batches 2-11 is a terpolymer of 55% by weight of ethylene, 40.6% by weight of propylene, 4.4% of diene, with a polydispersity of 2.5 and a Mooney viscosity of 100 (ML-8.100 ° C).

Thermoplastic compositions containing soot and extender oil are explained in Table II. The ingredients and procedure are the same as for Run 2-11 of Table I, except that carbon black (N-327) and paraffinic extender oil (Sunpar 2280) are mixed with the rubber prior to the addition of the polypropylene. The physical properties of the masses were determined according to ASTM method D-1708-66. Samples were tensioned on an Instron tester at a speed of 2.5 cm / min to 30% elongation and then at 25 cm / min to break. All masses can be processed. The tensile strength rating is the same as for Table I.

The values show that even masses that contain large amounts of extender oil have remarkable tensile strength. The uncured mixtures that make up the

Oil-expanded thermoplastic compositions with a tensile strength value of 2s below 10 x 106 Pa are produced with very low tensile strength values, and the tensile strength values of all compositions significantly exceed the tensile strength of the uncured mixtures 6 x 106 Pa. By changing the ratio of monoolefin copolymer rubber to polyolefin resin and by adding carbon black and extender oil, a range of hardness and tensile strengths can be obtained, all of which are in the improved range. It should be noted that the masses in Table II are economically attractive thermoplastics. At a comparable hardness of 35 bar, the tensile strength values of the thermoplastic compositions according to the invention exceed those of the partially hardened vulcanizates obtained from similar constituents to date.

Table II

Approach No. 12 13 14 15 16 17 18 19 20 21 22 23 24

Ingredients (in addition to zinc oxide and parts by weight of stearic acid)

EPDM rubber

65

65

65

65

65

65

65

45

45

45

45

35

35

Polypropylene

35

35

35

35

35

35

35

55

55

55

55

65

65

Soot

26

-

26

26

52

52

52

36

-

36

36

7

7

Extender oil

-

52

52

104

-

52

104

-

36

36

72

14

42

TMTD

0.65

0.65

0.65

0.65

0.65

0.65

0.65

0.45

0.45

0.45

0.45

0.35

0.

MBTS

0.33

0.33

0.33

0.33

0.33

0.33

0.33

0.23

0.23

0.23

0.23

0.175

O,

sulfur

1.3

1.3

1.3

1.3

1.3

1.3

1.3

0.9

0.9

0.9

0.9

0.7

0.

Tensile strength, Pa x 105

301

95

130

77

311

174

97

316

155

235

155

256

177

100% module, PaxlO5

87

30th

32

18th

110

39

20th

146

65

73

49

109

77

Young's module, Pa x 105

345

73

75

35

285

65

33

1228

482

236

117 1311

666

Strain, %

410

470

470

550

310

400

510

410

550

530

490

570

530

Hardness, Shore A

91

69

70

61

93

76

61

98

89

90

74

97

91

Hardness, Shore D

34

18th

19th

12

39

20th

14

51

29

33

22

46

34

Strain deformation,%

11

7

7

5

13

7

6

30th

19th

16

13

33

24th

(Tension set)

Table III explains the continuation of the vulcanization of partially vulcanized mixtures by further mixing with additional vulcanizing agents, and it further shows that this produces thermoplastic elastomers with a significantly increased tensile strength. The

Control batch 25 is prepared according to the procedure in Table I 65, using the same polypropylene as in Table I, but using only limited amounts of vulcanizing agents which are only sufficient to supply a partially vulcanized vulcanizate. The approach 26 is made

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from the partially vulcanized vulcanizate from batch 25, for which purpose it is mixed again with additional vulcanizing agents in order to bring the total amount of the vulcanizing agents to the stated content, and then further vulcanized while mixing in a Brabender 5 mixer for a total of five minutes at 180 ° C. continues. Batch 27 (a control for Batch 28) is a commercially available thermoplastic rubber (TPR), which is believed to be a dynamically partially cured blend of mono-olefin copolymer rubber and io polypropylene. Approach 28 is made from approach 27,

which is why it is mixed with the specified amounts of vulcanizing agent and then kneaded in a Brabender mixer for a total of five minutes at 180 ° C. The batch 29 (a control for batch 30) is produced from a polyethylene suitable for blow molding with a melt index of 0.6 g / 10 min, a specific weight of 0.960 and an elongation at break of 600%. The batch 30 is produced from the batch 29, for which purpose it is kneaded in a Brabender mixer, vulcanizing agent is added and the mixing is stopped when the vulcanization has ended.

All approaches can be processed as thermoplastics.

The approaches 25 and 26 show that the tensile and tear strength is significantly increased if the mixture of EPDM rubber with high polydispersity is vulcanized to such an extent that the rubber has a crosslinking density which is greater than 7 × 10 ~ Is 5 mol / ml. The approaches 27 and 28 show that the tensile strength is significantly increased by further vulcanization of a partially vulcanized mixture with a gel content of 91% to the extent that

that the gel content exceeds 97%. The batch 30 illustrates a thermoplastic elastomeric mass of high crosslinking density, which contains polyethylene, and shows that both the tensile strength and the modulus are significantly increased compared to the uncured control batch 29.

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A thermoplastic elastomeric composition according to the invention, produced with a non-sulfur-containing vulcanization system which contains a peroxide and phenylene bismaleimide (HVA-2) and consists of the same EPDM rubber as in batch 1, is explained in batch 34 in Table IV. The peroxide is 40% dicumyl peroxide (DiCup 40C). The approaches 31-33, which contain the same type of EPDM, are outside the invention. The batch 31 is a control without vulcanizing agents, and the batches 32 and 33 explain the properties of vulcanized products which are not sufficiently vulcanized. All batches are made in a Brabender mixer at 180 ° C from polypropylene with a specific weight of 0.905, an elongation of 100% and using a total mixing time of four minutes after the addition of the vulcanizing agents. The approach 34 is processable and shows the manufacture of a processable thermoplastic using high levels of a peroxide vulcanization system. The approach is fully vulcanized, as is evident from the much higher tensile strength compared to the undercured and undercured controls.

Table IV

Approach no.

31

32

33

34

Components

Parts by weight

EPMD rubber

62.5

62.5

62.5

62.5

Polypropylene

37.5

37.5

37.5

37.5

DiCup 40 C.

-

1.68

-

1.68

HVA-2

-

-

2.26

2.26

Tensile strength Pa x 105

52.0

51.3

61.9

113.9

100% module, Pax IO5

49.2

45.7

58.4

61.2

Young module, Pa x 105

683

464

987

446

Strain, %

210

190

250

360

Table III

Approach no.

25th

26

27th

28

29

30th

Components

Parts by weight

In stores

100

100

available TPR

EPDM chew

60 *

60 *

-

-

60 "

60 "

chuk

Polypropylene

40

40

-

-

-

-

Polyethylene

-

-

-

-

40

40

zinc oxide

3.0

3.0

-

3.0

-

3.0

Stearic acid

0.6

0.6

-

0.6

-

0.6

TMTD

0.15

0.9

-

0.6

-

0.9

MBTS

0.075

0.45

-

0.3

-

0.45

sulfur

0.3

1.8

-

1.2

-

1.8

Gel, percent

92.5

94.5

91.0

99.3

-

-

u / 2xl05

1.6>

■ 8.5

-

-

0

= 15

tensile strenght

83

144

69

150

54

167

Pax IO5

100% module,

62

72

61

74

46

77

Pax 105

Elongation at break,

390

480

200

420

710

610

percent

'It is assumed that it is a terpolymer of 55% by weight of ethylene, 42.5% of polypropylene and 2.5% of diene; the polydispersity is greater than 20, the Mooney viscosity 90 (ML-8,100 ° C).

It is assumed that the material is similar to the EPDM of batches 25 and 26, except that the terpolymer contains 5% diene and 40% propylene.

The use of thermoplastic elastomeric compositions 40 according to the invention as a modifier for a polyolefin resin is illustrated by approach 37 in Table V, and the achievement of similar properties to form the compositions in situ is illustrated by approach 38. The component called "polypropylene" in 45 batches 35, 36 and 38 is a polypropylene homopolymer with a nominal melt flow of 0.4 g / 10 min, a density of 0.905 g / ccm at 22.7 ° C, 13% elongation up to the elongation at yield and a 200% elongation at break and in batch 37 the homopolymer described above is supplemented by the polypropylene of batch 7. batch 35 is a control using only polypropylene. Batch 36 is a control with polypropylene containing 15% by weight uncured EPDM rubber (the same EPDM rubber as in 55 Batch 7). The batch 37 explains polypropylene which contains sufficient thermoplastic elastomeric composition according to the invention (batch 7 of Table I) to form a preparation which contains a total of about 85 parts of polypropylene and 15 parts of EPDM rubber. About 25.5 parts of 60 batch 7 (corresponding to about 15 parts of EPDM, 10 parts of polypropylene and 0.5 parts of vulcanizing agent) are mixed with an amount of the same polypropylene as in batches 35, 36 and 38 and the total amount of about 85 parts of polypropylene. The mixtures are mixed at 65182 ° C for 8 minutes in a Brabender mixer. The approach 38 explains a preparation similar to that of approach 37, but instead of mixing a mass with polypropylene, the EPDM rubber, the activators and vulcanized

643 279

8th

Caning agent (the same rubber with zinc oxide, stearic acid and vulcanizing agent as in batch 7) are added to the polypropylene and the mass is prepared in situ using the method of Table I. The values show that approaches 37 and 38 have improved toughness and true stress at break shows improved toughness. "*

Table V

Approach no.

35 36

37

38

Components (except zinc oxide and stearic acid in batches 37 and 38)

Weight parts

Polypropylene EPDM rubber hardening agent tensile strength until break, Pax 105 100 module, Pax IO5 rotation, percent full tension until break, Pax IO5 (True stress at break)

"From approach

"Full tension to break is the product of tensile strength to break times the ultimate elongation ratio (ultimate elongation),% / 100) +1]

The preparation of thermoplastic elastomeric compositions according to the invention using only peroxide vulcanizing agents is shown in Table VI. It is assumed that the EPDM rubber of batches 39 and 40 is a polymer of 58% by weight of ethylene, 32.5% by weight of propylene and 9.5% by weight of diene,

having a polydispersity of 2.4 and a Mooney viscosity of 50 (ML-8.100 ° C).

Table VI

Approach no.

39

40

41

42

Components

Parts by weight

Polypropylene

60

60

60

60

EPDM rubber

40

40

40

40

2,5-dimethyl-2,5-

-

0.99

-

0.99

di (t-butylperoxy) -

hexane

Gel, percent

-

98.2

-

95.3

U / 2X105

0

18.17

0

5.0

Tensile strength by

60.4

144.8

47.8

90.0

Bruch, Pax 105

Full tension up

195.5

646.8

131.5

428.9

to break, Pa x 105

Both the crosslink density and the gel content percentage of batch 40 are sufficient to achieve a substantial increase in tensile strength. The EPDM rubber of lugs 41 and 42 is the same as that in lug 25. In the case of lug 42, the rubber is not effectively vulcanized and there is no significant increase in tensile strength since dynamic vulcanization does not take place.

Vulcanizations of the rubber / resin mixtures other than dynamic vulcanizations can also be used to produce the compositions according to the invention. For example, the rubber can be fully vulcanized either dynamically or statically, without the resin, then pulverized and mixed with the resin at a temperature above the melting and softening point of the resin. Provided that the rubber particles are small and well dispersed and in a suitable concentration, the compositions according to the invention are easily obtained by mixing the vulcanized rubber and the resin. Accordingly, the term (blend) should be understood to mean a mixture which contains small rubber particles well dispersed, and a mixture which contains 15 rubber particles which are only slightly dispersed or too large can be ground by cold grinding (to reduce the particle size below approx 50 | im) comminuted or pulverized and thereby regenerated After sufficient comminution or pulverization, a mass can be obtained according to the invention 20. Often, the state of too little dispersion or too large rubber particles is visible to the naked eye and can be observed on a shaped coat In this case, the pulverization 25 and reshaping provide a fur in which aggregates of rubber particles or large particles are not or only slightly visible to the unarmed eye and the mechanical properties are significantly improved .

The principles and methods outlined above for preparing compositions according to the invention by mixing vulcanized rubber with resin are illustrated by the following example. One hundred parts by weight of EPDM rubber from batch 2 are mixed with 5 parts of zinc oxide, 1 part of stearic acid, 1.5 parts of sulfur, 1.0 part of TMTD and 35 0.5 parts of MBTS and vulcanized in a Brabender mixer, which was used during the mixing holds at an oil temperature of 180 ° C. Vulcanization occurs and a vulcanized product is obtained. Mixing continues about 3 minutes after vulcanization. The vulcanized, powdered rubber (which contains zinc oxide, stearic acid and vulcanizing agent) is mixed in a Brabender mixer with melted polypropylene, which is the same polypropylene as in batch 2. The mixture contains 70.8 parts of vulcanized rubber powder and 35 4 parts of polypropylene. It is observed that the molten mass, when pressed between cold plates, contains particles or aggregates of particles of rubber that are visible to the naked eye. This mixture is then crushed into a fine powder by cold milling on a very narrow rolling mill. The powdered mixture is mixed again in the hot Bra-bender mixer. A molten mass forms again, which can be rolled into a fur. The preparation is then compression molded as above at 220 ° C. 55 The properties of the fur formed, which contains very few visible particles or aggregates, are those of batch 43 in Table VII. Batch 44 is an unvulcanized control. The strength of batch 43 is more than 10 x 106 Pa greater than that of the uncured 60 mixture of batch 44. However, the strength of batch 43 is not as great as batch 5 of table 1, although this is a similar batch, but is was produced by means of dynamic vulcanization and which contains 0.5 parts more sulfur per 100 parts of rubber. It can be assumed that the dynamic vulcanization process usually produces smaller dispersed rubber particles (less than 1-10 | im).

From the above it follows that

100

212

203 520 1300

85 15

191

176 570 1270

85 15 * 0.5 270

191 540 1730

85 15 0.5 280

204 570 1870

9

643 279

Crushing heavily pre-vulcanized batches of rejected vulcanized conventional rubber parts in the form of rejects and spent rubber parts results in reusability of products that would otherwise normally be used as waste or at best as fuel. The shredded vulcanized waste or scrap rubber can be mixed with molten resin to form valuable thermoplastic compositions.

Table VII

Approach no.

43

44

Vulcanized EPDM rubber

70.8 *

Non-vulcanized

-

65

EPDM rubber

Polypropylene

35

35

u / 2x 105

approx. 14

0

Tensile strength, Pax 105

147.8

35.9

100% module, Pax IO5

69.2

35.5

Young module, Pa x 105

701

333

Elongation at break,%

423

192

"The vulcanized EPDM rubber contains 65 parts of rubber. The rest is zinc oxide, stearic acid and vulcanizing agent.

As indicated above, the proportions of the components that provide thermoplastic elastomers may change somewhat according to the particular resin, rubber, and compound components selected. The blends from which thermoplastic elastomeric compositions are made in accordance with the invention contain 25 to 85 parts by weight of polyolefin resin and 75 to 15 parts by weight of vulcanized monoolefin copolymer rubber per 100 parts by weight of resin plus rubber and 0-300 parts by weight of extender oil per 100 parts by weight of rubber plus resin. Thermoplastic elastomeric compositions containing vulcanized rubber are obtained whenever (Wo + Wr) / Wp is equal to or greater than 0.33, preferably 0.50 or more, where Wo is the weight of the extender oil, Wr is the weight of the rubber and WP is the weight of the resin. The addition of fillers such as carbon black or rubber extender oil and combinations of the two additives enables compounding according to the invention with a substantially unlimited range of properties. The addition of carbon black usually increases the tensile strength, while the addition of extender oil usually reduces the hardness and permanent set (tension set).

When fillers such as carbon black or silica are compounded with the blends, it is desirable that these additives be intimately mixed with the rubber prior to blending the rubber with the resin. Thus, one embodiment of the invention for making a thermoplastic elastomeric filler comprises mixing at a resin softening temperature of (a) 25 to 85 parts by weight of thermoplastic polyolefin resin, (b) 75 to 15 parts by weight of uncured mono-olefin copolymer rubber and (c) 5- 300 parts by weight of filler per 100 parts of total weight of resin plus rubber in the finished mass, wherein (a) is mixed with a previously formed homogeneous mixture of rubber and filler and the mixture is then kneaded continuously at the vulcanization temperature until the vulcanization is complete. A preferred method comprises mixing in the manner described above from 35-75 parts by weight of resin per 100 parts total weight of resin plus rubber and a preformed homogeneous mixture of 65-25 parts by weight of rubber and about 40-250 parts by weight of filler per 100 parts by weight of rubber. Of course, it is clear that sufficient vulcanizing agent must be present to form a vulcanizable mixture ls. The vulcanizing agent is preferably added to a mixture of (a), (b) and (c), although it can also be added to a pre-formed mixture of (b) and (c) or the rubber alone. An unvulcanized but vulcanizable preparation containing vulcanizing agents is therefore made by mixing the resin with a preformed mixture of rubber and filler and then dynamically vulcanizing the mixture to form a thermoplastic elastomeric filler.

25 Mixing rubber and filler before mixing with the resin provides vulcanizates with improved properties including higher tensile strength and less permanent set compared to similar masses that are made by mixing all three components simultaneously or by using a filler pre-formed mixture of rubber and resin mixes. In order to obtain improved properties, it is advantageous, if extender oil is present in the vulcanizates, to add the resin last. As above, it is important to either mix the filler with the rubber before blending the extender oil or to mix the filler and the extender oil with the rubber at the same time. On the other hand, the rubber can be mixed with the extender oil first, with good results if the rubber has sufficient viscosity. A commercially available oiled-doped EPDM rubber can therefore advantageously be used in the previously described improved method for producing fillers according to the invention.

30th

40

45

Thermoplastic elastomeric compositions according to the invention are made using the same ingredients as in Table II, but using higher proportions of resin, as given in Table VIII. The values show that elastomeric compositions with an amount of resin greater than 75% by weight are obtained when extender oil is present. The approaches 45-48 show that extender oil significantly improves the elasticity of the masses. The ss approaches 49-52 show that the presence of extender oil gives the masses, which contain high proportions of resin, elasticity, whereas masses without extender oil have significantly higher values of permanent deformation.

Table VIII

Approach 45 46 47 48 49 50 51 52

Components (in addition to zinc oxide and stearic acid) parts by weight

EPDM rubber 25 25

Polypropylene 75 75

Soot

25 25 17.5 17.5 17.5 15

75 75 82.5 82.5 82.5 85

37.5 75-26.25 52.5

643279

10th

Table VIII (continued)

approach

45

46

47

48

49

50

51

52

Ingredients (in addition to zinc oxide and stearic acid)

Parts by weight

Extender oil

_

50

37.5

50

26.25

26.25

26.25

30th

TMTD

0.25

0.25

0.25

0.25

0.175

0.175

0.175

0.375

MBTS

0.125

0.125

0.125

0.125

0.088

0.088

0.088

0.188

sulfur

0.375

0.375

0.375

0.375

0.263

0.263

0.263

0.75

Tensile strength, Pax IO5

337

98

146

116

174

160

164

145

100% module, Pax IO5

159

82

107

72

127

132

143

130

Young module, Pa x 105

4078

839

1232

709

1990

1940

1860

1997

Strain, %

630

270

330

160

440

300

230

290

Hardness, Shore D

61

39

45

43

51

54

54

55

Strain Deformation,% (Tension set,%)

57

36

37

44

53

46

48

53

(Wo + Wr) / WFP

0.33

1.0

0.83

1.0

0.53

0.53

0.53

53

Certain compositions according to the invention have, in accordance with the invention, elongation deformation values resistance to hot oil, which are about 20% (tension set) of about 50% or less, which are comparable to the masses known for neoprene vulcanizates the definition for rubber, as in the ASTM

are. For example, the weight percentage swelling is defined in Standard Regulations V. 28, page 756 (Dl 566), in ASTM No. 3 oil at 100 ° C for 70 hours. Particularly preferred compositions have a Shore D formulation 16, 17, 17-24 of Table II, 88 and 96, 84, 73, 73, hardness of 60 or less or a 100% modulus of 61, 61 and 51. In general, it was found that 2s 1, 5xl07Pa or less or one Young's modulus - the higher the crosslinking density of the rubber, the higher the 10x107Pa.

Resistance of the mass to swelling hot as described above, the thermoplastic ela-

Ö1 is. Accordingly, the mixing of polyolefin elastomeric masses by continuous kneading of a vulcanic resin and EPDM rubber and the completely dynamic vulcanizable mixture until the vulcanization is complete, the rubber can be prepared as a process for the preparation. By the term “until the vulcanization of thermoplastic elastomeric masses, which one is finished”, it is to be understood that essentially all vulcanization

Substantial resistance to swelling in oil-keratin constituents has been consumed in such a way that the vulcanized layers, this result being unexpected because the vulcanization reaction has essentially ended, whereby this saturated EPDM rubber alone indicates only poor resistance conditions , has oil swell. 35 that no further change in consistency can be observed

The designation «elastomer», as it should be noted in the description.

and used in the claims refers to a summary, therefore, the present inven composition, which has the property of vigorously within the thermoplastic compositions, the blends of mono from one minute to less than 60% of its initial length includes olefin copolymer rubber and thermoplastic contract after containing 40 olefin resin at room temperature in which the rubber is vulcanized. stretched twice its length and one minute before These vulcanizates have superior physical properties

Release was held. Particularly preferred compositions shade, including improved tensile strength.

B

Claims (11)

643 279 2nd PATENT CLAIMS 1. Thermoplastic elastomeric composition, characterized in that it contains thermoplastic polyolefin resin and monoolefin mixed polymer rubber, which is vulcanized and of which at most a small part has remained uncured, in a mixture with one another and optionally extender oil, that the weight WP of the thermoplastic polyolefin resin contains 25 to 85% and the weight Wr of the monolefin copolymer rubber in the uncured state makes up 75 to 15% of the total WP + Wr, the weight Wo of the extender oil is 0 to 300% of the aforementioned weight Wr, the quotient (Wo + Wr) / Wp is equal to or greater than 0.33 is that the monoolefin copolymer rubber is a copolymer of ethylene or propylene and at least one other alpha-olefin of the formula CH2 = CHR, where R is an alkyl group having 1 to 12 carbon atoms, which is additional, but only to a lesser extent Amount, units of at least one copolymerizable diene, that the mass can be processed in an internal mixer into a product which, after the resin phase is in the molten state, forms an essentially continuous skin after being transferred to the rotating rollers of a rolling mill, and that the rubber is vulcanized to such an extent, that no more than three percent by weight of it can be extracted by cyclohexane at 23 ° C or that its crosslinking density is greater than 7 × 10 ~ 5 mol / ml rubber. 2. Mass according to claim 1, characterized in that Wo is more than 0%, but not more than 300%, preferably 30 to 250%, of Wr. 3. Composition according to claim 1, characterized in that the weight WP of the thermoplastic polyolefin resin 25 to 75% and the weight Wr of the monoolefin mixed polymer rubber in the unvulcanized state makes up 75 to 25% of the total WP + Wr, and that the composition has a tensile strength which is at least 6 x 106 Pa larger than that of the uncured mass, 4. Composition according to claim 3, characterized in that the rubber is vulcanized to such an extent that no more than 3% by weight of it can be extracted by cyclohexane at 23 ° C. 5. Composition according to claim 4, characterized in that the resin is polypropylene or polyethylene and the rubber is EPDM rubber. 6. Composition according to claim 5, characterized in that the resin is polypropylene. 7. Composition according to claim 6, characterized in that the crosslinking density of the EPDM rubber is greater than 7x 10-5 mol / ml rubber. 8. Composition according to claim 7, characterized in that the weight WP of the polypropylene is 30 to 70% and the weight Wr of the EPDM rubber in the uncured state is 70 to 30% of the total WP + Wr. 9. Composition according to claim 8, characterized in that it is vulcanized by means of a sulfur vulcanizing agent. 10. Composition according to claim 9, characterized in that the crosslinking density is greater than 1 x 10-4 mol / ml rubber and the tensile strength is approximately 10 x 106 Pa greater than that of the unvulcanized composition. 11. A process for the preparation of a thermoplastic elastomeric mass according to claim 1, characterized in that the thermoplastic polyolefin resin, the unvulcanized monoolefin copolymer rubber, one or more vulcanizing agents and the extender oil, if such an oil is also used, at a temperature at which the thermoplastic polyolefin resin softens Condition, mixed and kneading the mixture continuously at the vulcanization temperature until the vulcanization is complete.