RU2425073C2 - Polyamide resin-based composition, having excellent expansibility and flexural fatigue, and use thereof in pneumatic tyre and air hose - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a polyamide resin-based composition consisting of a polyamide resin (A) as a matrix and a modifying polymer (C) dispersed in said matrix, having a functional group (B) which reacts with the polyamide resin (A), in which the tensile breaking stress of the modifying polymer (C) is between 30 and 70% of the tensile breaking stress of the polyamide resin (A) and tensile elongation at rapture of polymer (C) between 100 and 500% of the tensile elongation at rapture of the polyamide (A), as well as a pneumatic tyre and air hose made using the said composition.

EFFECT: composition has excellent expansibility and flexural fatigue.

8 cl, 7 tbl, 18 ex

Description

FIELD OF TECHNOLOGY

The present invention relates to a composition based on a polyamide resin and to a pneumatic tire and sleeve using such a resin. More specifically, it relates to a polyamide resin composition having excellent tensile strength and flexural fatigue, and its use for a pneumatic tire and sleeve.

BACKGROUND OF THE INVENTION

Polyamide resin has excellent machinability (or manufacturability), resistance to chemical attack and heat resistance and low gas permeability and, therefore, is widely used for products made by injection molding, extruded products, blown products, films, etc., using these properties. However, since the polyamide resin does not have sufficient impact resistance, fatigue strength, etc., it is necessary to improve these properties under conditions of dynamic deformation in the environment. As a means of improving the impact resistance of a polyamide resin, mixing with a modifier consisting of an elastomeric ingredient is known in the art (see, for example, US Pat. No. 4,174,358 and US Patent No. 4,594,386). However, for fatigue strength, depending on the environment used, the fatigue mechanism is complicated, it is impossible to obtain a sufficient improvement effect only by mixing with an elastomer. Manufacturers have proposed various modifiers for polyamide resins, in particular nylons. However, in environments where tensile and bending fatigue is present, a large load acts on the surface of the polyamide modifier and inside the modifier, as a result of which interfacial fatigue or fatigue of the modifier occurs and a sufficient improvement effect by the modifier cannot be obtained.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a modified polyamide resin composition having excellent tensile strength and flexural fatigue, and a pneumatic tire and sleeve employing such.

In accordance with the present invention, there is provided a polyamide composition comprising a polyamide resin (A) as a matrix and a modifying polymer (C) dispersed therein, having a functional group (B) interacting with a polyamide resin (A) in which tensile stress when the modifying polymer (C) breaks, it is 30 to 70% of the tensile stress when the polyamide resin (A) breaks, and the tensile elongation at the moment of modifying polymer (C) rupture is 100 to 500% of the elongation at p Contraction fracture point of the polyamide resin (A), and the pneumatic tire and the sleeve, applying such.

In the present invention, when a modifying polymer (C) having a functional group (B) capable of sufficiently reacting with a polyamide resin (A) is added to a composition based on a polyamide resin to enhance the interface, that is, by mixing a modifier having a sufficiently high ability to tensile with respect to the polyamide resin (A), the properties of the ability to stretch and bending fatigue are improved.

BEST MODE FOR CARRYING OUT THE INVENTION

The inventors of the present invention solved the above problems and, as a result, succeeded in solving the problem by means of a polyamide resin composition comprising a polyamide resin (A) and a modifying polymer (C) dispersed therein, having a functional group (B) capable of reacting with a polyamide resin (A) having a tensile stress at break of 30 to 70%, preferably 40 to 70% of the tensile stress at break of the polyamide resin (A) and having a tensile elongation in oment break from 100% to 500%, preferably 110 to 500% of the elongation at tensile break point of the polyamide resin (A) is mixed with it.

According to a preferred embodiment of the present invention, by making the bulk fraction of the modifying polymer (C) 40% or more, preferably 40 to 80%, more preferably 50 to 80%, a polyamide resin composition having excellent tensile and fatigue properties can be obtained when bending. As used herein, “volume fraction (%)” means a volume fraction of a modifying polymer (C) included in a polyamide resin composition. Additionally, when the ratio of the volume fraction and the melt viscosity of the modifying polymer (C) and the polyamide resin (A) satisfies the following formula (I) (α> 1), a more uniform dispersion of the modifying polymer (C) in the polyamide resin (A) is possible.

α = (ϕd / ϕm) × (ηm / ηd) <1 (I)

where ϕd means the volume fraction of the modifying polymer (C);

ϕm means the volume fraction of the polyamide resin (A);

ηd means the melt viscosity of the modifying polymer (C) (note: measurement conditions: Toyo Seiki capillary viscometer used to measure capillary viscosity at a measurement temperature of 240 ° C and a shear rate of 1200 sec ^-1 ) and

ηm means the melt viscosity of the polyamide resin (A) (note: measurement conditions: Toyo Seiki capillary viscometer used to measure capillary viscosity at a measurement temperature of 240 ° C and a shear rate of 1200 sec ^-1 ).

As the polyamide resin (A) applicable in the present invention, mention may be made of Nylon 6, Nylon 66, Nylon 66.6, Nylon 612, Nylon 11, Nylon 12, Nylon 46, Nylon 6.66.610, Nylon MXD6, etc. You can use them separately or in any combination of them.

As the functional group (B) interacting with the polyamide resin (A) useful in the present invention, mention may be made, for example, of a carboxylic acid anhydride group, an epoxy group, a halogen group, a carboxyl group, an amino group, a hydroxyl group and other functional groups. Preferred is the use of a carboxylic acid anhydride group, for example maleic acid anhydride group.

As modifying polymers (C) having an anhydride group useful in the present invention, mention may be made of an olefin homopolymer or copolymer. Especially preferred is the use of copolymers of ethylene and at least one α-olefin selected from propylene, butene, hexene and octene, from the point of view of elongation at break and tensile strength at break.

In a polyamide resin composition, as explained above, it is important that the modifying polymer (C) has tensile stress at break and tensile elongation at break (both measured in accordance with JIS K6251 at -20 ° C) from 30 to 70 % and 100 to 500% of the values of the polyamide resin (A), respectively. If the tensile stress at break is lower than the above value, undesirable material destruction of the modifying polymer (C) occurs and the load is undesirable from the side of the polyamide resin matrix (A). Further, if the tensile elongation at the time of fracture is lower than the above value, like tensile stress at break, material destruction of the modifying polymer (C) is undesirable.

A polyamide resin composition in accordance with the present invention may include, in addition to the above ingredients, carbon black, silica or other filler, a curing or crosslinking agent, a curing or crosslinking accelerator, various types of oils, antioxidant, plasticizer, oil, dye and various types other additives, typically miscible with rubber compositions and resin compositions. These additives can be mixed by conventional methods to formulate them. The blended amount can also be made into a traditional, conventional blended amount, as long as this does not oppose the purpose of the present invention.

EXAMPLES

Examples will be given below to further explain the present invention, but the meaning of the present invention is not limited in any way to these Examples.

Examples 1 to 9 and Comparative Examples 1 to 9

Receiving samples

To obtain compositions based on a polyamide resin, the ingredients shown in Tables I to IV were mixed as follows.

Granules of modifying polymers and granules of polyamide resin, shown in Table V to Table VII, were loaded into twin-screw extruders (TEX44 manufactured by Japan Steel Works) and mixed in the melt. The mixing conditions were 220 ° C for 3 minutes and a shear rate of 1200 sec ^-1 . The materials were continuously discharged from the extruder in the form of strands, cooled with water, then cut with knives to obtain compositions based on polyamide resin in the form of granules. To obtain sheets for fatigue tests, the obtained granules of compositions based on polyamide resin were loaded into single-screw extruders equipped with leaf heads and molded to a sheet form.

The polyamide resin compositions thus prepared were then subjected to fatigue tests using the test method described below. The results are presented in Tables I to IV.

Test method for assessing physical properties

Fatigue test: a polyamide resin composition molded by a sheet by means of a leaf head was pressed to form a JIS No. 3 dumbbell, then a dumbbell-shaped sample was attached after a fatigue test and subjected to constant deformation and bending testing. This was carried out under conditions of an interval between clamps of 54 cm, a tensile strain rate of 20%, a compression strain rate of 20%, a repetition rate of 6.67 Hz, and a test temperature of -20 ° C. The test was completed when the sample collapsed.

Rating:

Well ... the repetition rate to failure of more than 500,000 (break at 1000000X).

Bad ... the repetition rate before failure is less than 500000X.

Table 1 Polymer type Example 1 Example 2 Example 3 Example 4 Example 5 Wed Example 1 Wed Example 2 Wed Example 3 Composition (mass parts) BESNOTL (Nylon 11) ^{* 1} 40 45 55 - 45 - 45 - BMNO (Nylon 11) ^{* 1} - - - 45 - 45 - 45 MA8510 (Mah-EB) ^{* 2} 60 - - - - - - - MP0620 (Mah-EP) ^{* 2} - 55 - - - - - - VA1840 (Mah-EO) ^{* 2} - - 45 - - - - - AR201 (Mah-EEA) ^{* 2} - - - 55 - - - - Dumilan C1550 (washed EVA) (ethylene vinyl acetate copolymer) ^{* 2} - - - - 55 " Yokohama IIR rubber (butyl rubber) (Mah-IIR) ^{* 3} - - - - - 55 - - EPDM ^{* 3} - - - - - - 55 - X2 (Br-IIR) ^{* 3} - - - - - - - 55 ENR25 (E-NR) (natural rubber) ^{* 3} - - - - - - - - ϕd / ϕm 1,5 1.22 0.82 1.22 1.22 1.22 1.22 1.22 ηm / ηd 0.27 0.67 0.35 0.77 0.78 0.50 0.63 0.43 α (formula (I)) 0.41 0.82 0.29 0.94 0.95 0.61 0.77 0.53 TBd / TBm ^{* 4} 0.52 0.41 0.53 0.39 0.31 0.04 0,07 0.06 EBd / EBm ^{* 5} 1.3 1.3 1,2 1,5 1.47 1,5 1.47 1,59 Fatigue test 1,000,000 1,000,000 910000 700,000 550000 200,000 20000 5000 interrupted interrupted Rating Good Good Good Good Good poorly poorly poorly ^* 1: see Table V.
^* 2: see Table VI.
^* 3: see Table VII.
^* 4: TBd = stress at break of the polymer modifier (determined in accordance with JIS K6251)
TBm = tensile strength of the polyamide resin (determined in accordance with JIS K6251).
^* 5: EBd = elongation at break of the polymer modifier (determined in accordance with J1S K6251)
EBm = elongation at break of the polyamide resin (determined in accordance with JIS K6251).

Table II Polymer type Comparative Example 4 Composition (mass parts) BESNOTL (Nylon 11) ^{* 1} - BMNO (Nylon 11) ^{* 1} thirty MA8510 (Mah-EB) ^{* 2} - MP0620 (Mah-EP) ^{* 2} - VA1840 (Mah-EO) ^{* 2} - AR201 (Mah-EEA) ^{* 2} - DumilanC1550 (saponified EVA) ^{* 2} - rubber Yokohama IIR (Mah-HR) ^{* 3} - EPDM ^{* 3} - X2 (Br-IIR) ^{* 3} - ENR25 (E-NR) ^{* 3} 70 ϕd / ϕm 2,3 ηm / ηd 0.25 α (formula (I)) 0.58 TBd / TBm ^{* 4} 0.21 EBd / EBm ^{* 4} 1.47 Fatigue test 80,000 Rating poorly ^* 1: see Table V.
^* 2: see Table VI.
^* 3: see Table VII.
^* 4: see Footnote of Table I.

Table III Polymer type Example 6 Example 7 Wed Example 5 Wed Example 6 Composition (mass parts) 3030XA (Nylon 12) ^{* 1} 40 fifty 45 45 MA8510 (Mah-EB) ^{* 2} 60 - - - VA1840 (Mah-EO) ^{* 2} - fifty - - EPDM ^{* 3} - - 55 - ENR25 (E-NR) ^{* 3} - - - 56 ϕd / ϕm 1,5 1,0 1.22 1.22 ηm / ηd 0.30 0.39 0.69 0.703 α (formula (I)) 0.45 0.39 0.84 0.86 TBd / TBm ^{* 4} 0.52 0.41 0,07 0.17 EBd / EBm ^{* 4} 1.19 1.15 1.38 1.25 Fatigue test 1,000,000 1,000,000 3000 50,000 interrupted interrupted Rating Good Good poorly poorly ^* 1: see Table V.
^* 2: see Table VI.
^* 3: see Table VII.
^* 4: see the footnote of Table I.

Table IV Polymer type Example 8 Example 9 Example 10 Example 11 Wed Example 7 Wed Example 8 Composition (mass parts) CM6001FS (Nylon 6.66) ^{* 1} 45 45 - - 55 - CM1017 (Nylon 6) ^{* 1} - - 40 45 - 40 MA8510 (Mah-EB) ^{* 2} 55 - 60 - - - VA1840 (Mah-EO) ^{* 2} - 55 - 55 - - Yokohama IIR rubber (Mah-IIR) ^{* 3} - - - - 45 60 ϕd / ϕm 1.22 1.22 1.5 1.22 0.82 1.5 ηm / ηd 0.42 0.55 0.18 0.29 1.17 0.62 α (formula (I)) 0.51 0.67 0.27 0.35 0.96 0.93 TBd / TBm ^* 4 0.43 0.44 0.43 0.44 0.03 0.03 EBd / EBm ^* 4 1.38 1.33 1.4 1.36 1.47 1.5 Fatigue test 1,000,000 1,000,000 700,000 550000 2000 1000 interrupted interrupted Rating Good Good Good Good poorly poorly ^* 1: see Table V.
^* 2: see Table VI.
^* 3: see Table VII.
^* 4: see the footnote of Table I.

Table VI Strength properties and capillary viscosity of the polymer modifier at -20 ° C Mitsui Chemicals TAFMER MA8510 Mitsui Chemicals TAFMER MH0620 Exxon Mobile Chemicals Exxcelor VA1840 Mitsui Dupont Polychemical HPR AR201 Takeda Chemical Industries Dumilan C1550 Polymer type Maleic Anhydride Modified Ethylene Butene Copolymer Maleic Acid Modified Ethylene-Propylene Copolymer Maleic anhydride copolymer of ethylene and octene Maleic Acid Modified Ethylene Acrylate Copolymer A copolymer of ethylene, vinyl acetate and vinyl alcohol EB (%) * 1 620 660 600 720 630 TV (MPa) * 1 47 37 48 35 28 Capillary viscosity (Pa.s) * 1 350 140 266 81 120 * 1: see table V. footnote

Table VII Strength properties and capillary viscosity of a rubber-based ingredient at -20 ° C rubber Yokohama Mah-IIR * 1 Sumitomo Chemical EPDM Rubber LANXESS BROMOBUTYLX2 Malaysia enr25 Polymer type Maleic Anhydride Modified Butyl Rubber Ethylene Propylene Copolymer Halogenated Butyl Rubber Epoxy Natural Rubber EB (%) * 2 660 720 700 650 TV (MPa) * 2 3,5 6.6 5 17 Capillary viscosity (Pa.s) * 2 125 150 143 250 * 1: Production method: predetermined amounts of brominated butyl rubber, antioxidant, maleic anhydride and magnesium oxide were loaded into an overpressure plasticizer heated to 70 ° C, followed by mixing for a predetermined time (7 minutes) to obtain the desired product. The amount of maleic anhydride introduced into butyl rubber is 1.5 mol%, as determined by ¹ H-NMR analysis.
* 2: See the footnote of Table V.

INDUSTRIAL APPLICABILITY

The polyamide resin composition in accordance with the present invention can be used as internal sealing layers of pneumatic tires, etc., and can additionally be used, for example, as materials for the outer side of the chambers, materials for the inner layer of the inner side of the chambers and materials for outer layer of the inner side of the chambers for sleeves.

Claims (8)

1. A composition based on a polyamide resin, suitable as an inner layer of a pneumatic tire or sleeve, comprising a polyamide resin (A) as a matrix and an ethylene copolymer (C) dispersed in it, having a functional group (B) interacting with a polyamide resin (A), in which the tensile stress at break of the ethylene copolymer (C) is 30 to 70% of the tensile stress at break of the polyamide resin (A), and the tensile elongation at the time of breaking of the ethylene copolymer (C) is 100 to 500% of udl tensile at the time of rupture of the polyamide resin (A), where the ethylene copolymer (C) has a volume fraction of from 40 to 80%, based on 100% of the volume of the resin (A) and ethylene copolymer (C), and the functional group is selected from the group consisting of an acid anhydride, epoxy group, halogen group, carboxyl group, amino group and hydroxyl group. 2. The composition based on a polyamide resin according to claim 1, in which the ethylene copolymer (C) has a volume fraction of from 50 to 80%. 3. A composition based on a polyamide resin according to claim 1, in which the ratio of the volume fraction and the melt viscosity of the ethylene copolymer (C) and polyamide resin (A) satisfies the following formula (I):

in which ϕd is the volume fraction of ethylene copolymer (C);
ϕm is the volume fraction of the polyamide resin (A);
ηd is the melt viscosity of the ethylene copolymer (C);
ηm is the melt viscosity of the polyamide resin (A). 4. The composition based on a polyamide resin according to claim 1, in which the polyamide resin (A) is at least one resin selected from the group consisting of Nylon 6, Nylon 66, Nylon 6/66, Nylon 6/12 , Nylon 11 and Nylon 12. 5. The polyamide resin composition according to claim 1, wherein the functional group (B) is a carboxylic acid anhydride group. 6. The polyamide resin composition according to claim 1, wherein the ethylene copolymer (C) comprises at least one α-olefin selected from propylene, butene, hexene and octene. 7. A pneumatic tire using a polyamide resin composition as an internal sealing layer according to claim 1. 8. A sleeve using, as at least one layer, a composition based on a polyamide resin according to claim 1.