WO2015081408A1

WO2015081408A1 - Elastomeric composition with barrier property, method for preparing and using same, and pneumatic article

Info

Publication number: WO2015081408A1
Application number: PCT/BR2014/050027
Authority: WO
Inventors: Lucas Agostinelli POLITO; Aguinaldo Jose Osorio DE SOUZA; Glauco GABRIEL
Original assignee: Braskem S.A.
Priority date: 2013-12-04
Filing date: 2014-12-03
Publication date: 2015-06-11
Also published as: TW201538624A; AR098605A1

Abstract

The present invention relates to an elastomeric composition with barrier property, comprising at least one elastomer, low molecular-weight PIB and at least one crosslinking agent. Also described is a method for preparing said elastomeric composition comprising the steps of (i) mixing the elastomer and the low molecular-weight PIB in a mixer; and (ii) adding the crosslinking agent. The elastomeric composition has improved processability without any degradation of mechanical properties, which are particularly essential for use in pneumatic tires.

Description

"ELASTOMIC COMPOSITION WITH BARRIER PROPERTY, PROCESS FOR PREPARATION AND USE, AND PNEUMATIC ARTICLE"

TECHNICAL FIELD

The present invention relates to an elastomeric gas barrier property composition particularly suitable for the tire industry.

DESCRIPTION OF TECHNICAL STATE

Rubber compounds are of particular relevance in the tire industry, and in this area of application it is essential that the material has good gas permeability (barrier) resistance properties such as oxygen. In the state of the art there are several studies that deal with the improvement of this property.

Among the most well-known routes are the use of blends of different types of high molecular weight polymers, for example PIB (polyisobutylene), SBR (styrene and butadiene rubber), NR (natural rubber) and CIIR ( chlorine butyl rubber) as well as the use of mineral fillers of specific properties such as nano clays.

US 2012/0141696 describes an elastomeric composition produced from a thermoplastic copolymer having a high gas barrier. This composition comprises a block copolymer forming segments of polyisobutylene (butyl rubber) and a thermoplastic block having Tg (glass transition temperature) greater than or equal to 100 ° C. The composition is used as a waterproof layer on inflatable objects. Said composition differs from the present invention by utilizing a high molecular weight block copolymer to impart barrier properties. Still, there are restrictions regarding applications, since the composition comprises thermoplastic that has limited temperature range. WO 2005/035637 describes a high barrier coating composition for coating silicone parts. The crosslinked silicone article is coated with a layer of the composition in question, containing polyisobutylene polymer (butyl rubber), a crosslinking agent, a catalyst and an adhesion promoter. Said composition differs from the present invention in that it is a coating composition and is not incorporated into the final composition of the article produced. In addition, the coating undergoes a crosslinking process with the aid of a crosslinking agent. Thus, the application of the composition described in said document is limited to sealing processes and is not indicated for pneumatic articles.

US7425591 describes a nanocomposite elastomer composition comprising elastomer, carbon black, nano clay, low molecular weight PIB (less than 400 Daltons). It is mentioned in the document that the composition has significant gas barrier results, however the improvement in barrier property is attributed to the use of nano composites (ie physical barrier). The PIB oil used in this composition has a lower molecular weight (as compared to the PIB of the present invention) and is used as a flow aid. Due to its low molecular weight, this would not contribute to increase the gas barrier property.

US 2011/0094645 discloses a tire innerliner formulation comprising a functionalized elastomer, polyisobutylene-co-p-methyl styrene, nanometric fillers, and a flow aid. The formulation differs from the present invention in that it is an elastomer which, in addition to being functionalized, has a higher molecular weight than that used in the present invention.

JP 2006/328429 describes a composition of a polyolefin with better elasticity, but without losing barrier properties against carbon dioxide. The composition consists of a polypropylene resin, butyl rubber and / or polyisobutylene rubber (butyl rubber), as well as a low density polypropylene resin copolymerized with an α-olefin, and polyethylene may or may not be used in the composition. The composition differs from the present invention by utilizing a polyisobutylene rubber having a molecular weight much higher than conventional PIB (low molecular weight).

US 2004/0161560, JP 2010/189601, US 4857409, KR 2003/094907 and US 5153039 similarly disclose solutions of high barrier compositions utilizing, among other components, polyisobutylene rubber in your compositions. However, the objects of the listed documents differ from the composition of the present invention by utilizing polyisobutylene rubber (butyl rubber) having a molecular weight above that proposed in the present invention.

Unlike high molecular weight GDP, low molecular weight GDP (PIB oil) is a viscous, clear and transparent liquid obtained by the copolymerization of petrochemical butenes. This material is generally applied as a plasticizer in various polymers such as polyethylene, polypropylene and rubbers. Although PIB oil is similar in structure to butyl rubber (IIR), it is not as bulky as butyl rubber, and it is an amorphous oligomer, so it is not expected that the use of this oligomer will have any effect. gas barrier.

OBJECTIVES OF THIS INVENTION

[00011] The present invention is directed to a barrier property elastomeric composition comprising the following steps:

(A) at least one elastomer,

(B) low molecular weight GDP, and (C) at least one crosslinking agent,

wherein said GDP has a molecular weight ranging from 500 to 20,000 Daltons.

The present invention further provides a process for preparing said elastomeric composition comprising the steps of (i) mixing the elastomer and low molecular weight PIB in a mixer and (ii) adding the crosslinking agent.

Further, the present invention is directed to the use of said barrier property elastomeric composition and a pneumatic article comprised of said elastomeric composition.

The objectives of the present invention are achieved by means of an elastomeric composition with improved gas barrier property without loss of processability and mechanical properties, particularly essential for application to pneumatic articles.

Also, in the composition of the present invention low molecular weight PIB can replace part of the rubber commonly used for barrier purposes (e.g. chlorinated rubber). Thus, the elastomeric composition makes it possible to obtain lighter and less thick innerliners, besides bringing environmental advantages such as energy saving due to the better processability of the composition.

DESCRIPTION OF THE FIGURES

The present invention will be described in more detail below based on the representation of the figures below:

[00017] Figure 1 - Torque evolution as a function of time of white compound and with GDP 1;

[00018] Figure 2 - Torque evolution as a function of time of white compound and with GDP 2; [00019] Figure 3 - Evolution of energy consumption in mixtures as a function of time for white and GDP 1 compounds;

[00020] Figure 4 - Evolution of energy consumption in mixtures as a function of time for white and GDP 2 compounds;

Figure 5 - Variation of Mooney viscosity with the addition of different GDP contents;

[00022] Figure 6 - Rheometric curves obtained for reference sample and compounds containing PIB 1;

Figure 7 - Rheometric curves obtained for reference sample and compounds containing PIB 2;

[00024] Figure 8 - Oxygen permeability of White samples, with GDP 1 and GDP 2;

Figure 9 - Evolution of torque as a function of time for compounds Al, A2, BI and B2; and

[00026] Figure 10 - Evolution of energy consumption in mixtures as a function of time for compounds Al, A2, B I and B2.

DETAILED DESCRIPTION OF THE INVENTION

The improved barrier property elastomeric composition of the present invention comprises (A) at least one elastomer, (B) low molecular weight PIB, and (C) at least one crosslinking agent.

[00028] The presence of PIB in the composition confers improved barrier property in elastomeric compositions without loss of mechanical properties. Thus, PIB can be used as a replacement for part of the commonly used gas barrier rubbers (eg CIIR), resulting in a lighter and / or thicker article when compared to articles produced with traditional elastomeric compositions. In the composition of the present invention PIB acts as part of an elastomer in the formulation, occupying the free volumes of the higher gas permeability elastomers and thus forming a barrier to the passage of smaller molecules such as oxygen or atmospheric gases.

The main components of the elastomeric composition of the present invention as well as their respective properties are detailed below.

(A) ELASTOMER

The elastomer of the present invention has a molecular weight of 1,000 to 5,000,000 Daltons, has a hardness of 10 to 70 Shore A and is preferably selected from the group comprising natural rubber (NR), polyisoprene (IR), isobutylene. -isoprene (IIR), styrene and butadiene rubber (SBR), polybutadiene (BR), nitrile rubber (NBR); polyolefin rubbers - i.e. ethylene propylene rubber (EPDM, EPM, etc); acrylic rubbers (ACM), halogen rubbers - i.e. bromobutyl rubber (BIIR), chlorobutyl (CIIR), brominated isotubylene, polychloroprene; silicone rubbers (i.e., methyl vinyl silicone rubber, dimethyl silicone rubber, among others), sulfur containing rubbers (i.e. polysulfide rubber); fluorinated rubbers; thermoplastic rubbers (TR) - ie, styrene, butadiene, isoprene, ethylene and propylene based elastomers such as styrene / isoprene / styrene block copolymer (SIS), ethylene butylene copolymer (SEBS), styrene-butadiene styrene copolymer ( SBS), etc .; ester based elastomers, elastomeric polyurethane, elastomeric polyamide, among others, and mixtures thereof.

In a first preferred embodiment, the elastomer is selected from NR, IR, SBR, BR, NBR, CIIR, IIR, TR; polyolefin rubbers (EPDM, EPM), and mixtures thereof. In a second preferred embodiment, the elastomer is selected from NR, CIIR, SBR and its mixtures. Optionally, particulate or powdered vulcanized rubber residue may partially or fully replace the elastomer.

The elastomer of the present invention is present in an amount ranging from 60 to 70% based on the total mass of the composition.

(B) GDP

The low molecular weight PIB of the present invention is present in an amount ranging from 2 to 20 phr. Preferably, the GDP is present in an amount ranging from 4 to 15 phr. By 'phr' is meant part by hundread of rubber, or parts per hundred rubber.

In addition, the low molecular weight GDP has a molecular weight ranging from 500 to 20,000 Daltons, preferably from 1,000 to 20,000 Daltons. The viscosity of low molecular weight PIB measured at 25 ° C is preferably from 20 to 900,000 cP, more preferably from 40 to 700,000 cP.

(C) RETICULATION AGENT

The crosslinking agent (curing agent or curing system) of the present invention is present in contents ranging from 0.1 to 12%, preferably from 0.5 to 8% based on the total mass of the composition. In addition, the crosslinking agent is selected from the group comprising sulfur or organic peroxides. Such organic peroxides are preferably selected from the group comprising: 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, α-cumyl peroxyneodecanoate, 2-hydroxy-1,1-dimethylbutyl peroxyneoheptanoate, α-cumyl peroxyneoheptanoate, t-amyl peroxyneodecanoate, butyl peroxyneodecanoate, di (2-ethylhexyl) peroxydicarbonate, di (n-propyl) peroxydicarbonate, di (sec-butyl) peroxydicarbonate, t-butyl peroxyneoheptanoate, t-amyl peroxopivalate, t-butyl peroxypivalate, diisononanoyl peroxide, diisononanoyl peroxide hydroxy-1,1-dimethylbutylperoxy-2-ethylhexanoate, didecanoyl peroxide, 2,2'-azobis (isobutronitrile), di (3-carboxypropionyl) peroxide, 2,5-dimethyl-2,5- di (2-ethylhexanoylperoxy) hexane, dibenzoyl peroxide, t-amylperoxy 2-ethylhexanoate, t-butylperoxy 2-ethylhexanoate, t-butol peroxyisobutyrate, t-butyl peroxy (cis-3-carboxy) propenoate, 1,1-di ( t-amylperoxy) cyclohexane, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t-butylperoxy) cyclohexane, Ot-amyl 0- (2-ethylhexyl) monoperoxycarbonate, ot -butyl o-isopropyl monoperoxycarbonate, Ot-butyl 0- (2-ethylhexyl) monoperoxycarbonate, polyester tetrakis (t-butylperoxycarbonate), 2,5-dimethol-2,5-di (benzoylperoxy) hexane, t-amyl peroxyacetate, t- amyl peroxybenzoate, t-Butyl peroxyisononanoate, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl diperoxyphthalate, 2,2-di (t-butylperoxy) butane, 2,2-di (t-amyloperoxy) propane, n butyl 4,4-di (t-butylperoxy) valerate, ethyl 3,3-di (t-amyloperoxy) butyrate, ethyl 3,3-di (t-butylperoxy) butyrate, dicumyl peroxide, a, a'-bis ( t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, di (t-amyl) peroxide, t-butyl α-cumyl peroxy oxide, di (t-butyl) peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) -3-hexane, 3,6,9-triethyl-3,6,9-trimethyl-1,4 7-triperoxynonane.

The organic peroxides of the present invention preferably have active oxygen content between 0.1% and 30% and a half-life of 1 second to 5000 hours at a temperature of 100 ° C.

Optionally, co-agents may be added to the cross-linking system, these being selected from polyfunctional acrylic monomers.

In a preferred embodiment of the invention, the elastomeric composition comprises crosslinking activators and / or cure accelerators.

Crosslinking activators are preferably selected from the group comprising sulfur, organic peroxides and mixtures thereof, and are present in amounts ranging from 1 to 5% based on the total mass of the elastomeric composition. Such peroxides The organic compounds are preferably selected from the group comprising: 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, α-cumyl peroxyneodecanoate, 2-hydroxy-1,1-dimethylbutyl peroxyneoheptanoate, α-cumyl peroxyneoheptanoate, t-amyl peroxyneodecanoate, peroxyneodecanoate, di (2-ethylhexyl) peroxydicarbonate, di (n-propyl) peroxydicarbonate, di (sec-butyl) peroxydicarbonate, t-butyl peroxyneoheptanoate, t-amyl peroxopivalate, t-butyl peroxypivalate, diisononanoyl peroxyhydroxide, didodecanate -1,1-dimethylbutylperoxy-2-ethylhexanoate, didecanoyl peroxide, 2,2'-azobis (isobutronitrile), di (3-carboxypropionyl) peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, dibenzoyl peroxide, t-amylperoxy 2-ethylhexanoate, t-butylperoxy 2-ethylhexanoate, t-butol peroxyisobutyrate, t-butyl peroxy- (cis-3-carboxy) propenoate, 1,1-di (t-amylperoxy) cyclohexane, 1, 1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t-butylperoxy) cyclohexane, Ot-amyl 0- (2-ethylhexane) xyl) monoperoxycarbonate, ot-butyl o-isopropyl monoperoxycarbonate, Ot-butyl 0- (2-ethylhexyl) monoperoxycarbonate, polyester tetrakis (t-butylperoxycarbonate), 2,5-dimethol-2,5-di (benzoylperoxy) hexane, t- amyl peroxyacetate, t-amyl peroxybenzoate, t-butyl peroxyisononanoate, t-butyl peroxyacetate, t-butyl peroxybenzoate, di-t-butyl diperoxyphthalate, 2,2-di (t-butylperoxy) butane, 2,2-di (t-butyl peroxyacetate) amyloperoxy) propane, n-butyl 4,4-di (t-butylperoxy) valerate, ethyl 3,3-di (t-amyloperoxy) butyrate, ethyl 3,3-di (t-butylperoxy) butyrate, dicumyl peroxide, a, α'-bis (t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, di (t-amyl) peroxide, t-butyl α-cumyl peroxide, di (t-butyl ) peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) -3-hexane, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxinonane.

Curing accelerators may be selected from the group comprising zinc oxide, stearic acid and mixtures thereof, and They are present in amounts ranging from 0.5 to 2%, based on the total mass of the composition.

The elastomeric composition of the present invention may optionally further contain, in addition to the above components (A), (B) and (C), carbon black, silica and / or other mineral fillers, antioxidants, compatibilizers, among others. additives commonly used in rubber and plastic compound compositions. The amounts of these additives may be such as are commonly used in elastomeric compositions, provided that there is no interference with the mechanical and barrier properties of the elastomeric composition of the present invention.

In a preferred embodiment, the process of preparing the composition of the present invention comprises the steps of (i) mixing the elastomer and low molecular weight PIB in a mixer and (ii) adding the crosslinking agent to the mixture. Said process occurs at temperatures ranging from 70 to 100 ° C.

It is emphasized that the crosslinking agent is preferably added in process step (ii) since the temperatures developed in the preparation of the mixture in step (i) could cause premature pre-vulcanization of the elastomeric composition.

The elastomeric composition of the present invention may be prepared in an internal mixer, which may be of the Banbury type, as well as a roller mixer.

When performed, the addition of carbon black, silica, mineral fillers, antioxidants, compatibilizers, and / or mixtures thereof occurs in process step (i).

Optionally, crosslinking activators, cure accelerators and / or mixtures thereof may be added in step (i) and / or step (ii).

Upon completion of process step (ii), the elastomeric composition may be vulcanized and may be autoclaved, press, molding or other methods commonly used for the desired purpose.

The polymeric composition of the present invention is suitable for gas barrier applications, particularly for the tire industry. Also, this composition is indicated for the manufacture of innerliners, tread and tire side, as well as hoses and other pneumatic articles.

EXAMPLE 1 - Elastomeric Composition - NR / CIIR

1.1 Sample Preparation

Typical compounds for natural rubber (NR) and CIIR innerliners have been evaluated, replacing part of CIIR with two types of polybutenes (PIB 1 and PIB 2), contents as shown in Table 1:

Table 1. Typical innerline compounds to study

Polymers used Content of each polymer Number

(CIIR / NR / GDP) of

mixtures

80/20/00

75/20/05

CIIR / NR / GDP 1 4

70/20/10

60/20/20

80/20/00

75/20/05

CIIR / NR / GDP 2 4

70/20/10

60/20/20

The elastomeric composition was prepared in two steps. The first step, with the addition of activators, loads and process aids, was performed in an internal mixer using a rotor type Banbury In the second step, for the addition of the curing system, a roller mixer was used. This procedure was used since the temperature developed in the composition in the first step could result in premature pre-vulcanization of the composition if all components of the composition were added in one step.

The following closed mixer process conditions were used:

- Mixing chamber fill factor: 75%

- rotor speed: 60 rpm

- type of rotor used: tangential

- pylon pressure: 6 kgf / cm2

- initial mixing temperature of compounds: 85 ° C

- approximate discharge temperature: 90-100 ° C

In open mixer, the following conditions were used:

- initial cylinder temperature: 50 ° C

- final temperature: 70 ° C

- friction ratio: 1: 1,2

- total mixing time: 30min.

Rubber compound (elastomeric compound) formulations traditionally known to have gas permeation resistance and suitable for the production of pneumatic artifacts have been tested. These compounds were added with molecular weight PIB on the order of 1000 to 2000 Daltons (PIB 1) and 3000 to 5000 Daltons (PIB 2).

Tables 2 and 3 show the formulations tested:

Table 2. Formulations developed for compounds without GDP and with GDP 1 Type Ingredients White PIB 1 5phr PIB 1 PIB l lOphr 20phr

Polymer Natural Rubber ⁽¹⁾ 20.0 20.0 20.0 20.0

Chlorobutyl Rubber 80.0 75.0 70.0 60.0

(2)

Polybutene GDP 1 - 5.0 10.0 20.0

Activators Zinc Oxide 3.00 3.00 3.00 3.00

Stearic acid 2.00 2.00 2.00 2.00

Loads N660 ⁽³⁾ 55.0 55.0 55.0

Auxiliary Resin 8.0 8.0 8.0 8.0 Hydrocarbon Resin ⁽⁴⁾

process

Sulfur Agents 0.5 0.5 0.5 0.5 Double Curing

ventilated

MBTS ⁽⁵⁾ 1.5 1.5 1.5 1.5

Total 170.0 170.0 170.0 170.0

(1) Type 1 Brazilian Dark Natural Rubber (GEB 1)

(2) Chlorine isobutene isoprene CIIR1066

(3) Carbon black N660

(4) Unilene A80 Hydrocarbon Resin

(5) Benzothiazyl disulfide

Table 3. Formulations developed for compounds without GDP and with GDP 2

(1) Type 1 Brazilian Dark Natural Rubber (GEB 1)

(2) Chlorine isobutene isoprene CIIR1066

(3) Carbon black N660

(4) Unilene A80 Hydrocarbon Resin

(5) Benzothiazyl disulfide The above compositions vary the concentration of GDP of the tested samples from 0% (White) to 20% by mass. Aspects related to compound processing, mechanical properties and gas permeability were evaluated. The specimens were prepared according to ASTM D 3182: 07. Compression vulcanization performed at a temperature of 165 ° C.

1.2 Processing Test

[00057] In this test, torque, total energy of the compounds produced and Mooney viscosity were measured, and viscosity is the torque (force) required for a rotor in contact with the sample to rotate about its axis with velocity. constant angular velocity within a cavity with defined and constant volume and temperature. Money viscosity was measured according to ASTM D 1646: 07, obtained on a Mooney Alpha MV 2000 Viscometer, with 1 minute preheat.

[00058] The first stage (in a closed mixer) of the mixing was performed as described in Table 4. The evaluation of the torque evolution as a function of time for the white mixtures with PIB 1 and PIB 2 is presented in Figures 1 and 2.

Table 4. Mixing steps in closed mixer

Step Time Step Description

1 Up to 2 minutes Addition of polymers and chewing for blending homogenization

2 Up to 3.5 minutes Addition of activators and hydrocarbon resin

3 Up to 5.5 minutes Adding half the amount of carbon black

4 Up to 7.5 minutes Adding the remaining carbon black

5 Up to 10 minutes Torque stabilization, load dispersion and mix completion Through the curves (Figures 1 and 2) it is possible to observe that as the GDP is added, the torque values become smaller, showing a lower viscosity in this compound.

In the analysis of the total energy consumed by the produced compounds (Figures 3 and 4), it is observed that the higher the GDP content, the lower the total energy consumed by the mixture.

Similarly, in Figure 5, a reduction in the viscosity of compounds containing both PIBs relative to white is observed. This behavior is possibly due to the reduction in the viscosity of the compound with higher GDP contents. Thus it is possible to verify the improvement of the processability of the formulations where the GDP was added.

1.3 Healing Test

Test used to measure viscoelastic properties in rubber compounds as well as to determine the vulcanization curve of non-vulcanized elastomeric compounds. Curing properties are important for assessing the influence of PIBs on the curing reaction of compositions.

[00063] The equipment used was the RPA 2000 rheometer according to ASTM D 5289: 2007 ^and AlphaTechonologies. The following parameters were used:

• oscillating arc: ± 0.5 °;

• temperature: 165 ° C;

• time: 15 min;

• frequency: 100 cpm.

Figures 6 and 7, Tables 5 and 6 present the results of the rheometric curves obtained in the evaluated compounds. Table 5. Values obtained in the rheometric curves of the white sample and those with GDP 1

White Property GDP 1 GDP 1 GDP 1

5phr lOphr 20phr

Minimum torque ML.dN.m 1.6 1.3 1.3 1.0

Maximum torque ML.dN.m 7.1 6.2 6.4 6.2

Pre-vulcanization time - ts 1.min 2.3 2.6 2.7 2.9

Optimal cure time t90.min 9.4 9.0 7.0 7.7

Table 6. Values obtained in the rheometric curves of the white sample and those with GDP 2

White Property GDP 2 GDP 2 GDP2

5phr lOphr 20phr

Minimum torque ML.dN.m 1.6 1.3 1.1 0.9

Maximum torque ML.dN.m 7.1 5.8 5.7 5.7

Pre-vulcanization time - ts 1.min 2.3 2.8 2.7 2.7

Optimum cure time t90.min 9.4 6.8 6.6 7.6

A similar cure rate (slope inclination) is observed for all compounds, showing no influence of GDP on the cure rate. As for the torque values, this is observed to decrease as the GDP is added, a behavior already expected considering that the added GDP presents a lower viscosity than CIIR rubber, reducing the viscosity and the creep resistance of the compound.

1.4 Physical and Mechanical Properties

Mechanical properties assess the degree of influence of the replacement of CIIR rubber by GDP. The following analyzes were performed: • Shore A hardness: Test that defines the rigidity of the material, equipment used digital Shore A type durometer. The measurement was obtained with the aid of a durometer support. According to ASTM D2240: 05Reap. 2010, with reading time in ls. Bareiss Manufacturer.

• Tensile Strength and Elongation at Break and 100% Modulus: Test used to define the tensile strength, elongation at break and elastic modulus of the materials, the specimens used were of

Type C according to ASTM D 412: 06aI2. Equipment: EMIC Universal Testing Machine with claw clearance speed of 500 + 50 mm / min.

• Tear Strength: Test used to determine the tear strength of vulcanized elastomers. Test according to ASTM D624-00 (2007), Type C. Equipment used: EMIC Universal Testing Machine with claw clearance speed of 500 + 50 mm / min.

Tables 7 to 10 present the results of the physical-mechanical properties for each rubber compound containing PIB 1 and PIB 2. The addition of PIB had no influence on Shore A hardness and 100% modulus of the compounds.

Table 7. Results of the physical-mechanical properties of the compounds White and with PIB 1 White Property GDP 1 GDP 1 GDP 1

5phr lOphr 20phr

Shore A hardness (median) 54 53 54 55

Stress at Break, MPa 15.7 14.4 13.1 10.0

(median)

Elongation at Break,% 660 690 620 560

(median)

100% module, MPa (median) 2.1 1.7 2.2 2.3

Tear Strength, N / mm 46.7 45.3 50.2 41.7

(median)

Table 8. Results of the physical-mechanical properties of the compounds.

White and with GDP 2

White Property GDP 2 GDP 2 GDP 2

5phr lOphr 20phr

Shore A hardness (median) 54 52 54 55

Stress at Break, MPa 15.7 14.7 12.8 10.0

(median)

Elongation at Break,% 660 690 650 590

(median)

100% module, MPa (median) 2.1 2.0 2.1 2.0

Tear Strength, N / mm 46.7 50.4 46.7 40.3

(median)

Table 9. Properties variation after accelerated greenhouse aging by 70h at 700 C Property after exposure White GDP 2 GDP 2 GDP 2 on heat 5phr lOphr 20phr

Shore A hardness (median) 56 54 57 58

Stress at Break, MPa 14.9 14.2 13.1 11.1

(median)

Elongation at Break,% 600 630 580 550

(median)

100% module, MPa (median) 2.0 2.1 2.4 2.7

Shore A Hardness Range, +2.0 +1.0 +3.0 +3.0 points

Rupture Stress Variation,% -5.10 -1.4 0.0 +11.0

Variation in Elongation at -9.1 -8.7 -6.5 -1.8

Break, %

Variation in modulus 100%,% -4.8 + 23.5 +9.1 +17.4

Table 10. Properties variation after accelerated greenhouse aging by 70h at 700 C

Property after exposure White GDP 2 GDP 2 GDP 2 on heat 5phr lOphr 20phr

Shore A hardness (median) 56 57 57 58

Stress at Break, MPa 14.9 14.3 13.2 10.9

(median)

Elongation at Break,% 600 660 640 530

(median)

100% Module, MPa (median) 2.0 2.4 2.3 2.9

Shore A Hardness Range, +2.0 +5.0 +3.0 +3.0 points

Rupture Stress Variation,% -5.10 -2.7 +3.1 +9.0

Change in Stretching at -9.1 -4.3 -1.5 -10.2

Break, %

Variation in module 100%,% -4.8 +20.0 +9.5 +45.0 1.5 Permeability Test

The permeability test seeks to evaluate the influence of GDP on the permeability of compounds. This test determines the oxygen permeability rate of polymers in the form of films, laminates, coextruded, among others, performed according to ASTM F1927. The permeability is determined by the equipment sensor in automatic mode. The equipment used was the Oxtran 2/21 Mocon Oxygen Trasmission Rate System.

Tables 11 and 12 and Figure 8 show the results of the oxygen permeability test on samples with and without GDP.

Table 11. Results of permeability tests in white sample and with GDP 1

White Property GDP 1 GDP 1 GDP 1

5phr lOphr 20phr

Oxygen transmission rate

[HiGTR],

cm ³ / (m ² .day) 491.30 482.22 278.74 301.34

mol / (m ² s) 2.54E- 2.50E- 1.44E- 1.56E-

07 07 07 07

Permance [ΡΌ ² ], mol / (m ² .s.Pa) 2.53E- 2.47E- 1.43E- 1.56E-

12 12 12 12

Coefficient of Permeability to 3.67E- 3.63E- 2.65E- 1.25E-

Oxygen [P "0 ² ], mol / (msPa) 15 15 15 15

Effective permeation area (cm ² ) = 0.317

Film thickness (mm) = between 1.3 and 1.5 mm

Table 12. Results of permeability tests in white sample and with GDP 2 White Property GDP 2 GDP 2 GDP 2

5phr lOphr 20phr

Oxygen transmission rate

[O2GTR],

cm ³ / (m ² .day) 491.30 233.49 290.06 187.28

mol / (m ² s) 2.54E- 1.21E- 1.50E- 9.67E-

07 07 07 08

Permance [ΡΌ ² ], mol / (m ² .s.Pa) 2.53E- 1.19E- 1.50E- 9.62E-

12 12 12 13

Permeability Coefficient at 3.67E- 1.68E-1, HE6.52E-

Oxygen [P "0 ² ], mol / (msPa) 15 15 IS 16

-?

Effective permeation area (cm2) = 0.317

Film thickness (mm) = between 1.3 and 1.5 mm

Low molecular weight additive elastomeric compositions showed improved gas barrier property when compared to the standard sample. The recorded values demonstrate a permeability value reduction of up to 50% of the standard with results observed from the 5% polybutene additive.

The formulation in which 20 parts (approximately 10.5% of the total mass) of GDP were applied showed the greatest reduction in oxygen permeability compared to the standard formulation.

1.6 Flexural Fatigue Resistance

[00072] Assay used to evaluate vulcanized elastomeric compounds flexible to crack formation and growth when subjected to successive flexions in the equipment called De Mattia Flexometer. This method is able to estimate the ability of flexible elastomeric compounds to withstand dynamic fatigue, and there is no exact correlation with the artifact in service. The test follows ASTM standard D430: 2006 Method B- Assessment of crack appearance. Gear used: Maqtest.

Table 13 presents the results of the De Mattia flexural strength test in the samples tested. After 500,000 bending cycles no rupture or cracking was observed in any of the samples tested.

Table 13. Flexural strength results From Mattia for White and PIB-containing compounds 128

Grade 0: No Cracks

Through the analyzes performed on the typical tire innerliner compound, by adding GDP 1 and GDP 2, the following conclusions could be obtained:

• Compounds with GDP showed a decrease in the energy consumed during the mixing process;

• The addition of GDP resulted in a decrease in the maximum torque on the vulcanization curve without loss or change in cure speed.

• little or no change in hardness properties at 100% modulus were observed with the addition of GDP; • Up to 5phr of GDP replacing CIIR did not result in loss of tensile and elongation resistance, but higher GDP levels resulted in losses in these properties;

• In the tear strength test, only 20phr of GDP resulted in losses in this property;

• In the thermal aging test, the addition of the GDP resulted in a 100% increase in the modulus of the material and in the tensile strength, this behavior can be explained by a possible residual cure of the GDP or its loss, migration or volatilization;

• oxygen permeability decreases with the addition of different GDP levels;

• no loss of flexural fatigue properties in samples containing PIB

EXAMPLE 2 - Elastomeric Composition - NR / CIIR / SBR

2.1 Sample Preparation

Four compounds identified as "Sample Al", "Sample A2", "Sample BI" and "Sample B2" were produced for the evaluation of the influence of CIIR substitution and addition of PIB 2 (3000 to 5000 Daltons) as proportions. of each polymer shown in Table 14.

In this assessment the 70phr CIIR, commonly used for innerliner formulations, has been replaced by SBR as follows:

- 20phr CIIR and 50 phr SBR;

- 45phr from CIIR and 25 phr from SBR.

In addition to this substitution, 5phr of PIB was added to the compounds to evaluate the influence of this polymer on the permeability of the final product. Table 14. Formulation of NR / SBR / CIIR / PIB compounds to be studied

Identification of compounds Polymers (blends)

(NR / SBR / CIIR / GDP)

Compound Al 30/50/20/00

Compound A2 30/50/20/05

Compound B I 30/25/45/00

Compound B2 30/25/45/05

Table 15 shows the proportions of each ingredient used in the 04 samples produced.

Table 15. Formulations developed for compounds A1, A2, BI and B2

Type Ingredients Al A2 BI B2

Polymer Natural Rubber ⁽¹⁾ 30.0 30.0 30.0 30.0

Chlorobutyl Rubber ⁽²⁾ 20.0 20.0 45.0 45.0

SBR ⁽³⁾ 50.0 50.0 25.0 25.0

Polybutene GDP 2 - 5.0 - 5.0

Activators Zinc Oxide 3.00 3.00 3.00 3.00

Stearic acid 2.00 2.00 2.00 2.00

Loads N660 ⁽⁴⁾ 55.0 55.0 55.0

Auxiliary Hydrocarbon Resin 8.0 8.0 8.0 8.0 from (5)

process

Sulfur Agents Double 0.5 0.5 0.5 0.5 Ventilated Curing

MBTS ⁽⁶⁾ 1.5 1.5 1.5 1.5

Total 170.0 175.00 170.0 175.0 (1) Type 1 Brazilian Dark Natural Rubber (GEB 1)

(2) Chlorine isobutene isoprene CIIR1066

(3) Styrene-butadiene rubber - SBR 1502

(4) Carbon black N660

(5) Unilene A80 Hydrocarbon Resin

(6) Benzothiazyl disulfide

The compounds were prepared in two steps. The first step, with the addition of process activators, loads and process aids, was performed in a closed Banbury mixer using a tangential rotor. The second step, for the addition of the curing system, was performed in an open laboratory mixer. This methodology was used because the temperature developed in the compound in the first step could result in premature pre-vulcanization of the compound if the curing system was added in the first step.

The following closed mixer process conditions were used:

- Mixing chamber fill factor: 75%;

- rotor speed of rotors: 60 rpm;

- type of rotor used: tangential;

- pylon pressure: 6 kgf / cm2;

- initial mixing temperature of the compounds: 85 ° C;

- approximate discharge temperature: 120-130 ° C.

In open mixer, the following conditions were used:

- initial cylinder temperature: 50 ° C;

- final temperature: 70 ° C;

- friction ratio: 1: 1.4;

- total mixing time: 30min.

The first stage of mixing (performed in a closed mixer) is described as per Table 16. Table 16. Mixing Steps in Closed Mixer

The specimens were prepared according to ASTM D 3182: 07. Compression vulcanization performed at 165 ° C.

2.2 Rheology and Processing

The evaluation of torque evolution as a function of time and energy consumed during the process for mixtures Al, A2, BI and B2 are shown in Figures 9 and 10. Through the curves it can be observed that as it is added the GDP torque values are lower, showing a lower viscosity in this compound.

In the analysis of the total energy consumed by the produced compounds (Figure 10), it is observed that the addition of GDP reduces the total energy consumed by the mixture. This behavior is possibly due to the reduction in the viscosity of the compound with 5% of GDP.

2.3 Healing Properties

Curing properties are important in assessing the influence of PIBs on the curing reaction of compounds. The properties were determined by the Rheometric Curve Assay, an assay used to measure viscoelastic properties in rubber compounds, as well as to determine the vulcanization curve of rubber compounds. non-vulcanized elastomers. The equipment used is the rheometer RPA 2000, as ASTM D 5289: 2007 ^the brand Alpha Techonologies.

The results are shown in Table 17 using the following parameters:

- arc of oscillation: ± 0,5 °;

- temperature: 165 ° C;

- time: 30 min;

- frequency: 100 cpm.

[00088] The presence of PIB in both formulations decreased the minimum and maximum torque values, not interfering with pre-vulcanization time and optimal cure time.

Table 17. Values obtained in the rheometric curves of samples Al, A2, BI and B2

Al A2 BI B2 Property

Minimum torque - ML, dN.m 1,3 1,1 1,3 1,1

Maximum torque - MH, dN.m 7.7 6.6 8.0 6.9

Pre-vulcanization time - ts 1.min 2.7 3.1 2.7 3.0

Optimum cure time - t90.min 10.1 10.4 10.5 10.6

2.4 Oxygen Permeability

The permeability test aims to determine the oxygen permeability rate of polymers in the form of films, laminates, coextruded, among others, performed according to ASTM F1927. The permeability is determined by the equalizing sensor in automatic mode. Equipment used: Oxtran 2/21 Mocon Oxygen Trasmission Rate System. Table 18 presents the results of the oxygen permeability test on samples A1, A2, BI and B2. Through the obtained results, it was observed that the compound with 25phr of SBR, 45phr of CIIR and 5phr of PIB 2 presented a lower permeability than the compound without the addition of PIB. The compound with 50phr of SBR and 20phr of CIIR showed no decrease in permeability when added the GDP.

Table 18. Permeability Test Results on Al, A2, BI, and B2 Samples

Al A2 BI B2 Property

Oxygen transmission rate [O2GTR],

cm ³ / (m ² day) 1126.0 1115.9 710.0 683.7 mol / (m ² s) 5.82E-7 5.76E-7 3.67E-7 3.53E-7

Permance [ΡΌ ² ], mol / (m ² .s.Pa) 5.78E- 5.72E- 3.62E- 3.48E-

12 12 12 12

Oxygen Permeability Coefficient 5.79E- SAE3.47E- 2.87E-

[P "0 ² ], mol / (msPa) 15 IS 15 15

Effective permeation area (cm ² ) = 0.317

Film thickness (mm) = between 0.7 and 1.2 mm

[00091] The presence of PIB 2 in NR / SBR / IIR based formulations reduced the viscosity of the compounds and consequently the torque and energy values. The addition of PIB 2 reduced the permeability in the compound with 45phr CIIR and 25phr SBR, favoring the gain of barrier properties.

In Example 1, the White compound prepared with 20phr NR and 80phr CIIR with 55phr N660 had an oxygen permeability coefficient of 3.7E-15 mol / (msPa). Thus, it was possible to consider that compound B2, (with oxygen permeability coefficient of 2.87E-15) presented impermeability when compared to the standard or reference compound containing CIIR.

Having described preferred embodiments, it should be understood that the scope of the present invention encompasses other possible variations and is limited only by the content of the present embodiments.

appended claims, including the possible equivalents thereof.

Claims

1. Elastomeric composition with barrier property characterized by the fact that it comprises

(A) at least one elastomer,

(B) low molecular weight GDP, and

(C) at least one crosslinking agent,

wherein said GDP has a molecular weight ranging from 500 to 20,000 Daltons.

Composition according to Claim 1, characterized in that the elastomer (A) is present in an amount ranging from 60 to 70% based on the total mass of the composition.

Composition according to Claim 1 or 2, characterized in that the elastomer (A) has a molecular weight between 1,000 and 5,000,000 Daltons and has a hardness between 10 and 70 Shore A.

Composition according to any one of Claims 1 to 3, characterized in that the elastomer (A) is selected from the group comprising natural rubber (NR), polyisoprene (IR), isobutylene isoprene (IIR), styrene and butadiene rubber (SBR), polybutadiene (BR), nitrile rubber (NBR); polyolefin rubbers; acrylic rubbers (ACM), halogen rubbers; silicone rubbers, sulfur containing rubbers; fluorinated rubbers; thermoplastic rubbers (TR); ester based elastomers, elastomeric polyurethane, elastomeric polyamide, and mixtures thereof.

Composition according to Claim 4, characterized in that the elastomer (A) is preferably selected from the group. which comprises NR, IR, SBR, BR, NBR, CIIR, IIR, TR; polyolefin rubbers (EPDM, EPM), and mixtures thereof.

Composition according to Claim 4 or 5, characterized in that the elastomer (A) can be partially or totally replaced by particulate or powdered vulcanized rubber residues.

Composition according to Claim 1, characterized in that the low molecular weight GDP (B) is present in an amount ranging from 2 to 20 phr, preferably from 4 to 15 phr.

Composition according to Claim 1, characterized in that the low molecular weight GDP (B) preferably has a molecular weight ranging from 1,000 to 20,000 Daltons.

Composition according to Claim 1, characterized in that the low molecular weight GDP (B) has a viscosity of from 20 to 900,000 cP, preferably from 40 to 700,000 cP, measured at 25 ° C.

Composition according to Claim 1, characterized in that the cross-linking agent ranges from 0.1 to 12%, preferably from 0.5 to 8%, based on the total mass of the composition, and is selected from the group. which comprises sulfur or organic peroxides.

Composition according to Claim 1, characterized in that it optionally comprises at least one curing accelerator in an amount ranging from 0.5 to 2%, based on the total mass of the composition, selected from the group comprising oxide. of zinc, stearic acid and mixtures thereof.

Composition according to Claim 1, characterized in that it optionally comprises at least one cross-linking activator in an amount ranging from 1 to 5%, based on mass. total composition, selected from the group comprising sulfur, organic peroxides and mixtures thereof.

Composition according to Claim 10 or 12, characterized in that the organic peroxides are selected from the group comprising 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, α-cumyl peroxyneodecanoate, 2-hydroxy-1,1-hydroxy-peroxide. dimethylbutyl peroxyneoheptanoate, α-cumyl peroxyneoheptanoate, t-amyl peroxyneodecanoate, t-butyl peroxyneodecanoate, di (2-ethylhexyl) peroxydicarbonate, di (n-propyl) peroxydicarbonate, t-butyl peroxydicarbonate, t-butyl peroxydicarbonate peroxypivalate, t-butyl peroxypivalate, diisononanoyl peroxide, didodecanoyl peroxide, 3-hydroxy-1,1-dimethylbutylperoxy-2-ethylhexanoate, didecanoyl peroxide, 2,2'-azobis (isobutronitrile), di (3-carboxypropionyl) peroxide, 2, 5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, dibenzoyl peroxide, t-amylperoxy 2-ethylhexanoate, t-butylperoxy 2-ethylhexanoate, t-butol peroxyisobutyrate, t-butyl peroxy (cis-3-carboxy) propenoate, 1,1-di (t-amylperoxy) cyclohexane, 1,1-di (t-butylperoxy) -3,3,5-t trimethylcyclohexane, 1,1-di (t-butylperoxy) cyclohexane, ot-amyl O- (2-ethylhexyl) monoperoxycarbonate, ot-butyl o-isopropyl monoperoxycarbonate, ot-butyl 0- (2-ethylhexyl) monoperoxycarbonate, polyester tetrakis butylperoxycarbonate), 2,5-dimethol-2,5-di (benzoylperoxy) hexane, t-amyl peroxyacetate, t-amyl peroxybenzoate, t-Butyl peroxybenzoate, t-butyl peroxyacetate, t-butyl peroxybenzoate, di-t-butyl diperoxyphthalate, 2,2-di (t-butylperoxy) butane, 2,2-di (t-amyloperoxy) propane, n-butyl 4,4-di (t-butylperoxy) valerate, ethyl 3,3-di (t- amyloperoxy) butyrate, ethyl 3,3-di (t-butylperoxy) butyrate, dicumyl peroxide, α, α'-bis (t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5-di (t- butylperoxy) hexane, di (t-amyl) peroxide, t-butyl α-cumyl peroxide, di (t-butyl) peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) -3-hexane, 3 , 6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane.

Composition according to Claim 13, characterized in that the organic peroxides comprise active oxygen content between 0.1% and 30% and a half-life of 1 second at 5000 hours at a temperature of 100 ° C.

Composition according to Claim 1, characterized in that the cross-linking agent (C) optionally comprises at least one co-agent selected from polyfunctional acrylic monomers.

Composition according to Claim 1, characterized in that it optionally comprises additives selected from carbon black, silica, mineral fillers, antioxidants, compatibilizers and mixtures thereof.

Process for preparing the elastomeric composition defined in any one of claims 1 to 16, characterized in that it comprises the steps of (i) Mixing the elastomer and low molecular weight PIB in a mixer and (ii) Adding the agent of crosslinking to the mixture.

Process according to claim 17, characterized in that it optionally comprises the addition of carbon black, silica, mineral fillers, antioxidants, compatibilizers, and / or mixtures thereof in step (i).

Process according to Claim 17, characterized in that it optionally comprises the addition of crosslinking activators, curing accelerators and / or mixtures thereof in step (i) and / or (ii).

Process according to Claim 17, characterized in that the mixer is selected from the group comprising internal mixer, Banbury mixer and roller mixer.

Process according to Claim 17, characterized in that the process takes place at temperatures ranging from 70 to 100 ° C.

Process according to claim 17, after step (ii) the elastomeric composition is vulcanized.

Use of the elastomeric composition described in any one of claims 1 to 16, characterized in that it is for the manufacture of pneumatic articles.

Use according to claim 23, characterized in that it is for the manufacture of tire innerliners, tread and sides and pneumatic hoses.

Pneumatic article comprising the elastomeric composition as defined in any one of claims 1 to 16.