RU2316569C2 - Thermoplastic elastomer composition and improved rubber granulation process - Google Patents

Abstract

FIELD: polymer materials.

SUBSTANCE: invention relates to thermoplastic elastomer composition for manufacturing products such as films, which composition contains dynamically curable mixture of (A) halogenated isobutylene/p-methylstyrene copolymer, (B) polyamide, and (C) antioxidant having melting point above 70°C and below 200°C, granulated elastomer (A) obtained by granulation in presence of antioxidant (C) as granulator being dispersed as a domain in the continuous phase of polyamide (B) and composition containing (A) and (B) components being dynamically cured. Thus obtained film is characterized by better stretching than film made from composition containing curing agent as granulator and by excellent durability and stability at low temperature as compared to film made from talc-containing composition.

EFFECT: increased durability, heat resistance, elasticity and air impermeability.

7 cl, 3 tbl, 5 ex

Description

FIELD OF TECHNOLOGY

The present invention relates to an improved thermoplastic elastomeric composition having excellent durability, heat resistance and elasticity, while also having excellent airtightness. In particular, the present invention relates to a thermoplastic elastomeric composition using an antioxidant as an anti-caking agent, where the antioxidant used has a melting point of more than 70 ° C and less than 200 ° C.

BACKGROUND OF THE INVENTION

EP722850B1 discloses a low permeability thermoplastic elastomeric composition that is excellent as a gas barrier layer in pneumatic tires. This thermoplastic composition includes a low permeability thermoplastic matrix, such as polyamides or polyamide mixtures, into which low permeability rubber is dispersed, such as brominated poly (isobutylene-co-p-methylstyrene) (i.e. BIMS). Further, in both EP857761A1 and EP969039A1, the viscosity ratio between the thermoplastic matrix and the rubber dispersion is defined as a function of the ratio of volume fractions and independently approaches unity to achieve phase continuity in thermoplastic and thin rubber dispersions, respectively. The critical state of smaller rubber dispersions is recognized in EP969039A1 in these thermoplastic elastomers to achieve satisfactory durability, especially for their use as internal sealing layers in pneumatic tires.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a thermoplastic elastomeric composition having enhanced durability, heat resistance and elasticity, while also having excellent airtightness.

In accordance with the present invention, there is provided a thermoplastic elastomeric composition having increased durability, heat resistance and elasticity, comprising a dynamically vulcanizable mixture of (A) halogenated isobutylene elastomer, (B) polyamide and (C) antioxidant having a melting point of more than 70 ° C and less than 200 ° C, in which the elastomer (A) is dispersed as a domain in the continuous phase of component (B), and components (A) and (B) are dynamically cured in the presence of an antioxidant as an anti-caking agent .

SUMMARY OF THE INVENTION

In this description and in the following claims, the unit forms "a", "an" and "the" include multiple references until the context clearly shows otherwise.

The present invention relates to a thermoplastic elastomeric composition, more particularly relates to a thermoplastic elastomeric composition, excellent in durability and impermeability. This thermoplastic elastomer contains rubber particles resulting from an improved method of granulating rubber. More specifically, rubber compounds are granulated using antioxidants as an anti-caking agent, the antioxidants used having a melting point of more than 70 ° C. and less than 200 ° C.

Most specifically, rubber compounds and polyamides are dynamically cured in the presence of an antioxidant, such as triphosphite antioxidants, hindered phenolic antioxidants, alone, or in combination with other antioxidants (s), preferably 5 mass. hours per hundred (ie mass parts per 100 parts of rubber) or less, more preferably 4 mass. including one hundred or less, further more preferably 3 mass. including one hundred or less, even more preferably 2 mass. including one hundred or less, most preferably 1 mass. hours for a hundred or less.

Typical examples of triphosphite antioxidants are tris (di-tert-butylphenyl) phosphite, tris-nonylphenyl phosphite; and typical examples of hindered phenolic antioxidants are 4,4'-butylidene-bis- (3-methyl-6-tert-butylphenol), 2-4-bis [(octylthio) methyl] -o-cresol.

The thermoplastic elastomeric composition is a mixture of halogenated isobutylene and polyamide elastomer, which is subjected to dynamic vulcanization.

The term "dynamic vulcanization" is used herein to mean a vulcanization process in which a technical resin and a vulcanizable elastomer are vulcanized under high shear conditions. As a result, the vulcanizable elastomer is simultaneously crosslinked and dispersed in the form of fine dispersed particles of the “microgel" in the matrix of technical resin.

Dynamic vulcanization is affected by mixing the ingredients at a temperature equal to or higher than the vulcanization temperature of the elastomer in equipment such as roller mills, Banbury ^® mixers, continuous mixers, plasticizers or mixing extruders, for example twin screw extruders. A unique characteristic of dynamically vulcanizable compositions is that despite the fact that the elastomeric component can be fully vulcanized, the compositions can be processed and recycled by conventional methods for producing thermoplastic resins such as extrusion, injection molding, compression molding, etc. Waste can be collected and recycled.

In a preferred embodiment, the elastomeric component of the halogenated isobutylene comprises copolymers of isobutylene and para-alkyl styrene such as those described in European Patent Application 0344021. The copolymers preferably have a substantially homogeneous composite distribution. Preferred alkyl groups for a para-alkylstyrene moiety include alkyl groups containing from 1 to 5 carbon atoms, primarily haloalkyl, second haloalkyl having from 1 to 5 carbon atoms, and mixtures thereof. A preferred copolymer includes isobutylene and para-methyl styrene.

Suitable elastomeric components of halogenated isobutylene include copolymers (such as brominated isobutylene and para-methyl styrene copolymers) having a number average molecular weight Mn of at least about 25,000, preferably at least about 50,000, preferably at least about 75,000, preferably at least about 100,000 preferably at least about 150,000. The copolymers may also have a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio, i.e. Mw / Mn is less than about 6, preferably less than about 4, more preferably less than about 2.5, most preferably less than about 2.0. In another embodiment, suitable elastomeric components of halogenated isobutylene include copolymers (such as copolymers of brominated isobutylene and para-methyl styrene) having a Mooney viscosity (1 + 4) at 125 ° C (as measured according to ASTM D 1646-99) 25 or more, preferably 30 or more, more preferably 40 or more.

Preferred brominated copolymers of isobutylene and para-methylstyrene include those with 5 to 12% by weight. para-methylstyrene, 0.3 to 1.8 mol%. brominated para-methylstyrene and Mooney viscosity from 30 to 65 (1 + 4) at 125 ° C (as measured according to ASTM D 1646-99).

The elastomeric component of halogenated isobutylene (A) in accordance with the present invention can be obtained from isobutylene and about 0.5 to 25 wt.%, Preferably 2 to 20 wt.%, In relation to the total number of comonomers, p-alkylstyrene, preferably p-methylstyrene followed by halogenation. The halogen content (e.g., Br and / or Cl, preferably Br) is preferably less than about 10% by weight, more preferably about 0.1 to about 7% by weight. in relation to the total amount of copolymer.

The copolymerization can be carried out in a known manner, as described, for example, in European patent application No. 034402 / A, published November 29, 1989, and halogenation can be carried out in a known manner, as described, for example, in U.S. patent No. 4548995.

The halogenated isobutylene elastomer preferably has a number average molecular weight (Mn) of at least about 25,000, more preferably at least about 100,000, and a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio, i.e. Mw / Mn is preferably less than about 10, more preferably less than about 8.

The polyamides useful in the present invention are thermoplastic polyamides (nylons), include crystalline or resinous solid polymers with high molecular weight, including copolymers and terpolymers having repeating amide units within the polymer chain. Polyamides can be obtained by polymerizing one or more epsilon-lactams such as caprolactam, pyrrolidion, laurillactam and aminoundecanoic acid amino acids, or by condensation of dibasic acids and diamines. Both fiber-forming and extruded nylon grades are suitable. Examples of such polyamides are polycaprolactam (Nylon 6), polylauryl lactam (Nylon 12), polyhexamethylene adipamide (Nylon 66), polyhexamethylene azelamide (Nylon 69), polyhexamethylene sebacamide (Nylon 610), polyhexamethylene isophthalamide (Nylon 6 IP) amide-condensation Nylon 11). You can also use Nylon 6 (N6), Nylon 11 (N11), Nylon 12 (N12), copolymer Nylon 6/66 (N6 / 66), Nylon 610 (N610), Nylon 46, Nylon MXD6, Nylon 69 and Nylon 612 ( N612). You can also use their copolymers in their any mixtures. Further examples of satisfactory polyamides (especially those having a softening point below 275 ° C.) are described in Kirk-Othmer, Encyclopedia of Chemical Technology, v. 10, page 919 and Encyclopedia of Polymer Science and Technology, v. 10, pages 392-414. Commercially available thermoplastic polyamides can be advantageously used in the practice of this invention, with linear crystalline polyamides having a softening point or melting point between 160-230 ° C. being more preferred.

The amounts of elastomer (A) and polyamide (B) used in the present invention are preferably 95 to 25 mass. parts and 5 to 75 mass. parts, more preferably 90 to 25 mass. parts and 10 to 75 mass. parts, respectively, providing that the total number of components (A) and (B) is 100 mass. parts.

A method of producing a thermoplastic elastomeric composition of the present invention consists in melting and plasticizing a halogenated isobutylene elastomer (A), polyamide (B) and antioxidant (C) using a biaxial plasticizer / extruder, etc. for dispersing elastomer (A) in polyamide (B) to obtain a continuous phase. When vulcanizing the elastomer (A), a vulcanizing agent is added during mastication, and the elastomeric component is dynamically vulcanized. Further, various compounding agents (other than a curing agent) for the elastomer and polyamide can be added during the above plasticization, but it is preferable to mix them well in advance of the plasticization. The plasticizer used to plasticize the polyamide and elastomer, in particular, is not limited. Examples thereof are a screw extruder, a plasticizer, a Banbury mixer, a biaxial plasticizer / extruder and the like. Among them, it is preferable to use a biaxial plasticizer / extruder to plasticize the thermoplastic resin and elastomer and to dynamically vulcanize the elastomer. You can then use two or more types of plasticizers for successful plasticization. As conditions for melting and mastication, the temperature should be at least the temperature at which the polyamide melts. Further, the shear rate at the time of plasticization is preferably 500 to 7500 sec ^-1 . The time for complete plasticization is from 30 seconds to 10 minutes. Further, when the vulcanizing agent is added, the vulcanization time after the addition is preferably 15 seconds to 5 minutes. The elastomeric composition obtained by the above method is then extruded or calendared into a film. The film forming method may be a conventional film forming method from a thermoplastic resin or a thermoplastic elastomer.

The elastomeric composition in accordance with the present invention may contain, in addition to the aforementioned basic ingredients, a vulcanizing or crosslinking agent, a vulcanization or crosslinking accelerator, various types of oils, an antioxidant, a reinforcing filler, a plasticizer, a softener or other various additives, mainly mixed with ordinary rubbers. The components are mixed and vulcanized by conventional methods to obtain a composition that can then be used for vulcanization or crosslinking. The amounts of these added additives may be at the level of those usually added to the extent that this does not conflict with the purpose of the present invention.

EXAMPLES

The invention will now be illustrated by the following Examples, not limited in any way.

1. Resin component

Nylon (Nylon 6/66): Ube Nylon (Ube Kousan)

Additives: antioxidant: Irganox 1098 - sterically hindered N, N′-hexane-1,6-diyl-bis- (3- (3,5-ditretbutyl-4-hydroxyphenylpropionamide)) No. CAS 23128-74-7;

Tinuvin 622LD is an oligomeric hindered amine light stabilizer, a polymer of succinic acid dimethyl ester with 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol, CAS No. 65447-77-0; and

CuI - copper iodide

2. The elastomeric component

BIMS: A brominated isobutylene-para-methyl styrene copolymer sold under the trade name EXXPRO 89-4 by ExxonMobil Chemical Company, having a Mooney viscosity of about 45, about 5% by weight. para-methylstyrene and about 0.75 mol%. bromine.

ZnO: Vulcanizing Zinc Oxide

St-acid: vulcanizing stearic acid

ZnSt: Vulcanizing Zinc Stearate

DM16D: tertiary amine - hexadecylamine ARMEEN DM16D (AKZO NOBEL)

3. Granulator

Talc: NIPPON TALC K.K.

IRGAFOS 168: Tris (2,4-Ditretbutylphenyl) Phosphite Antioxidant Available on Ciba

Vulcanizing agent: ZnO, St-acid and ZnSt (see Table 1)

The test methods used to evaluate the Examples and Comparative Examples were as follows:

A) Durability (Fatigue Cycles at Low Temperature)

The film and frame compound were laminated together with adhesive and cured at 190 ° C for 10 minutes. Then dumbbell-shaped JIS No. 2 was stamped and used for durability testing at -20 ° C at 6.67 Hz and a strain of 40%.

B) Strength Mechanical Properties

All strength tests are based on JIS K6251 "Vulcanized Rubber Strength Test Methods".

For Examples 1, 2, 4 and 5, the ingredients (weights, parts), with the exception of Nylon and the additives shown in Table 1, were plasticized in a Banbury mixer (discharge temperature = 120 ° C) for 2 min, followed by granulation of the resulting composition with conventional granulated coating method. For Example 3 (Comparative), Exxpro 89.4 was plasticized in a Banbury mixer, followed by granulation in a conventional manner with a granulator coating. After that, the obtained granules and Nylon and the additives shown in Table 1 were dynamically vulcanized using a biaxial extruder at 230 ° C and a shear rate of 1000 C ^-1 .

Table 1: COMPOSITION (mass parts) Ingredient Example one 2 3 ^{* 1} four 5 Exxpro one hundred one hundred one hundred one hundred one hundred 89.4 Zno 0.15 0.15 0.15 0.15 0.15 St-acid 0.6 0.6 0.6 0.6 0.6 Znst 0.3 0.3 0.3 0.3 0.3 DM16D - - - 1,0 1,0 Granulator Talc IRGAFOS 168 Vulcanizing agent Talc IRGAFOS 168 Nylon 98 98 98 98 98 Additives 1.23 1.23 1.23 1.23 1.23 Total 200,28 200,28 199.23 201.28 201.28 * 1: Comparative Example

Table 2: Mechanical properties Example one 2 3 TV at -20 ° C (MPa) 44,2 43.6 38.1 EB at -20 ° C 320 320 290 Durability × 10 ⁶ times 1.0-1.5 1.0-1.5 0.1

Films having the composition shown in Table 1 were blown using the same blow mold. The mechanical properties are presented in Table 2.

A film using an antioxidant as a granulator has good tensile properties compared to a film having a vulcanizing agent as a granulator.

Also, a film using an antioxidant as a granulator has the same excellent durability at low temperature and stability at a low temperature as a film using talc.

Table 3: Mechanical properties Example four 5 TV at -20 ° C (MPa) 49.0 45.6 EB at -20 ° C (%) 375 370 Durability × 10 ⁶ times 1,0 1,2

Films having the composition shown in Table 1 were blown using the same blow mold. Their mechanical properties are presented in Table 3. The mechanical properties of a thermoplastic elastomer containing rubber particles obtained by an improved method of granulating rubber are good. The film has the same mechanical properties. A film using an antioxidant as a granulator has the same stretch as when using talc as a granulator. Also, a film using an antioxidant as a granulator has the same excellent durability at low temperatures.

Claims (7)

1. Thermoplastic elastomeric composition for the manufacture of products, such as films, having air tightness, increased durability, heat resistance and elasticity, containing a dynamically vulcanizable mixture of (A) a halogenated copolymer of isobutylene and para-methyl styrene, (B) polyamide and (C) an antioxidant having a temperature melting more than 70 ° C, and less than 200 ° C, and the granular elastomer (A) obtained by granulation in the presence of an antioxidant (C) as a granulator is dispersed as a domain in the continuous phase of polyamide (B), wherein the composition containing components (A) and (B) is dynamically vulcanized. 2. The thermoplastic elastomeric composition according to claim 1, in which the amount of halogenated isobutylene copolymer is 95 to 25 parts by weight and the amount of polyamide is 5 to 75 parts by weight 3. The thermoplastic elastomeric composition according to claim 1 or 2, in which the amount of antioxidant is 5 wt., Parts or less with respect to 100 wt. parts of a halogenated isobutylene copolymer. 4. The thermoplastic elastomeric composition according to claim 1 or 2, in which the halogenated isobutylene copolymer is a brominated isobutylene copolymer and para-methylstyrene. 5. The thermoplastic elastomeric composition according to claim 1 or 2, in which the polyamide is at least one component selected from the group consisting of Nylon 6, Nylon 66, Nylon 11, Nylon 12, Nylon 69, Nylon 610, Nylon 46 , Nylon MXD6, Nylon 6/66, and their copolymers, and mixtures thereof. 6. The thermoplastic elastomeric composition according to claim 1 or 2, in which the antioxidant is at least one component selected from the group consisting of triphosphite antioxidant, either alone or in combination with other antioxidant (s). 7. The thermoplastic elastomeric composition according to claim 1 or 2, wherein the antioxidant is added during the granulation process.