NL2014547A

NL2014547A - A high abrasion resistant shoe sole.

Info

Publication number: NL2014547A
Application number: NL2014547A
Authority: NL
Inventors: Willem Van Der Waal Arie
Original assignee: Kraton Polymers Us Llc
Priority date: 2015-03-30
Filing date: 2015-03-30
Publication date: 2016-10-10
Also published as: NL2014547B1

Abstract

The present invention relates to a curable rubber composition comprising: • Component (a): from 35-50 wt% of one or more isoprene polymers; • Component (b): from 35-50 wt% of one or more polymers different from isoprene polymers; • Components (c) and (d): from 0.05-4.0 wt% of a curing agent optionally with a co-agent, and • Component (e): from 0.01-20 wt% of additives, characterized in that the composition further comprises: • Component (f): from more than 4-30 wt% of one or more polyalkenamers, wherein all amounts are in percentages by weight on the total composition. The invention further relates to a cured rubber composition made thereof, and a manufacturing process for the cured composition. The present invention also relates to an article including the rubber composition, in particular shoes with highly abrasion resistant soles.

Description

P32326N LOO/M KO (A0077b)

Title: A high abrasion resistant shoe sole Technical Field

The present invention relates to a high abrasion resistant shoe sole, a curable rubber composition therefore, and a manufacturing process for the cured composition.

Background

Excellent rubber compositions have for instance been described in WO2014132718. Even though in this application an improved balance has been found between rubber properties such as hardness and strength, there is still a need for further improvement, in particular with respect to abrasion resistance. This requirement is particularly important for sport shoes, where lower abrasion resistance is required as compared to ordinary shoes (e.g., < 120 mm3 according to ISO 4649, method A). Now a new composition has been found that can be used for shoe soles and other applications.

Summary of Invention

Accordingly a curable rubber composition is provided, comprising: • Component (a): from 35-50 wt% of one or more isoprene polymers; • Component (b): from 35-50 wt% of one or more polymers different from isoprene 1 polymers; • Components (c) and (d): from 0.05-8.0 wt% of a curing agent optionally with a coagent, and • Component (e): from 0.01-20 wt% of additives, characterized in that the composition further comprises: • Component (f): from more than 4-30 wt% of one or more polyalkenamers, wherein all amounts are in percentages by weight on the total composition.

The present invention also provides a cured rubber composition, based on the curable composition mentioned above. The present invention also provides a process for manufacturing a cured rubber composition, wherein the process comprising the acts of: • mixing components (a), (b) and (e) to obtain a mixture thereof; • adding a curing agent (c) and co-agent (d) to the mixture; and • uniformly kneading the mixture.

Finally, the invention provides highly abrasion resistant shoe soles that are of particular use in sport shoes, safety shoes and hiking shoes and the like.

Description of the Invention

The term of "Type A Durometer Hardness" or "Hs" means the hardness of a rubber composition measured according to ASTM D2240. The value of Hs is determined, in the present specification, from the following procedure: constantly pushing a plunger onto a test article, and measuring the depth of the pushed plunger in the article at 0 sec or 30 sec after the pushing.

The term of "tear strength" means the tear strength of a rubber composition measured according to ASTM D624. The value of tear strength is determined, in the present specification, by using 2 mm-thick sheet of a test material, and converted in N/mm unit.

The term of "vinyl content" refers to the amount of a conjugated diene which is polymerized via 1,2-addition (in the case of butadiene-it would be 3,4-addition in the case of isoprene). Although a pure "vinyl" group is formed only in the case of 1,2-addition polymerization of 1,3-butadiene, the effects of 3,4-addition polymerization of isoprene (and similar addition for other conjugated dienes) on the final properties of the block copolymer will be similar. The result of the addition above, a pendant vinyl group on the polymer skeleton will be produced. The vinyl content in a polymer may be measured using a conventional technique in the art such as proton NMR.

The vinyl content is effectively controlled by varying the relative amount of the distribution agent. As will be appreciated, the distribution agent serves two purposes - it creates the controlled distribution of the mono alkenyl arene and conjugated diene, and also controls the microstructure of the conjugated diene. Suitable ratios of distribution agent to lithium are disclosed and taught in U.S. Pat. No. Re 27,145, which disclosure is incorporated by reference.

The terms of "plasticizer oil", "plasticizer", and "softener" mean a (oil-based) compound known as an additive for changing properties of a material in the art. The plasticizer may include, but not limited to, paraffin oil, mineral oil, ester oil, hydrocarbon-based synthetic lubricating oils, naphthenic oils, and vegetable oils.

As used herein, unless otherwise noted, the term "molecular weight(s)" refers to the true molecular weight in g/mole of the polymer or block of the copolymer. The molecular weights referred to in this specification and claims can be measured with gel permeation chromatography (GPC) using polystyrene calibration standards, such as is done according to ASTM 3536. GPC is a well-known method wherein polymers are separated according to molecular size,· the largest molecule eluting first. The chromatograph is calibrated using commercially available polystyrene molecular weight standards. The molecular weight of polymers measured using GPC so calibrated are styrene equivalent molecular weights, also known as apparent molecular weights. The styrene equivalent molecular weight may be converted to true molecular weight when the styrene content of the polymer and the vinyl content of the diene segments are known. The detector used is preferably a combination ultraviolet and refractive index detector. The molecular weights expressed herein are measured at the peak of the GPC trace, converted to true molecular weights, and are commonly referred to as "peak molecular weights". When expressed as apparent molecular weights they are similarly determined with the exception that consideration of the block copolymer composition and the subsequent conversion to true molecular weights is not done.

The words of "comprising", "including", and "containing" mean in the present specification, unless otherwise noted, that an article or component connotes or has an element(s). The spirit of the words may embraces both an internal and external additions.

In the case that the word of "about", "around", or "appropriately" is prefixed to a value, in the present specification, the value can include a tolerance of at least plus/minus 10 percent.

Component (a)

Isoprene polymers are known. This definition includes homopolymers and copolymers of isoprene, wherein at least 50 mole% of the polymer backbone is based on isoprene. Homopolymers are often referred to as Isoprene Rubber, or IR. The isoprene polymer can be an anionically produced IR, IR produced by Ziegler-Natta catalysis, or with a neodymium catalyst. Natural rubber (NR) is likewise a homopolymer of isoprene. Copolymers include polymers comprising isoprene and another conjugated diene and/or olefinically unsaturated monomer in the polymer backbone. Examples include copolymers of butadiene and isoprene, or isoprene and styrene, and the like. Copolymers may be random, tapered, block or otherwise structured. Isoprene polymers may be linear or branched. Moreover, they may be functionalized.

To achieve better tear strength, the isoprene polymers preferably have a molecular weight greater than 250,000, more preferably greater than 500,000. Moreover, in term of isoprene homopolymers, they preferably have a cis content of greater than 80 %. The high cis content is believed to be beneficial to the flexibility of the composition. Then again, the cis content is not the only factor influencing the flexibility, and isoprene homopolymers with a flexibility below 80 % may still be useful.

Component (a) is present in an amount of 35 - 50 wt%, preferably in an amount of 40 - 45 wt%.

Component (b)

Component (b) is preferably a butadiene polymer, more preferably polybutadiene. Nonetheless, other polymers may be used instead or in combination with a butadiene polymer. Such polymers include polymers made from C4 to C20 olefins; thermoplastic elastomers (TPEs), styrene-butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), hydrogenated nitrile rubber (HNBR), chloroprene rubber (CR), butyl rubber (MR), fluorine rubber (FKM), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), urethane rubber, and any other polymer which is referred to as rubber in the prior art.

Silicone rubber may also be used.

Particularly suitable is syndiotactic 1,2-polybutadiene provided by JSR, e.g., grades RB810, RB820, RB830 or RB840.

Component (b) is present in an amount of 35 - 50 wt%, preferably in an amount of 40 - 45 wt%.

Components (c) and (d)

The curing agent may include, for instance, sulfur, sulfur-containing compounds, radical curing agents, and peroxides. The curing agent is preferably peroxide in view of low contamination in a resulted product. Excellent results have been achieved with peroxides selected from the group consisting of 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, dicumyl peroxide, benzoyl peroxide, 1,1-bis-(t-butylperoxy)-3,5,5-trimethylcyclohexane, diisobutyryl peroxide, cumylperoxy neodecanoate, di-n-propylperoxy dicarbonate, di-isopropyl peroxy dicarbonate, di-sec-butylperoxy dicarbonate, 1,1,3,3-tetramethyl-butylperoxy neodecanoate, di-(4-t-butylcyclohexyl)peroxy dicarbonate, di(2-ethylhexyl)peroxy dicarbonate, t-hexylperoxy neodecanoate, t-butylperoxy neodecanoate, t-butylperoxy neoheptanoate, t-hexylperoxy pivalate, t-butylperoxy pivalate, di(3,5,5-trimethyl-hexanoyl) peroxide, dilauroyl peroxide, 1,1,3,3-tetramethyl-butylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, di(4-methyl-benzoyl) peroxide, t-butylperoxy-2-ethylhexanoate, di(3-methyl-benzoyl) peroxide, benzoyl(3-methyl-benzoyl) peroxide, dibenzoyl peroxide, 1,1-di(t-butylperoxy)-2-methyl-cyclohexane, 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(4,4-di(t-butylperoxy)cyclohexyl)propane, t-hexyïperoxyisopropyl monocarbonate, t-butylperoxy maleic acid, t-butylperoxy-3,5,5-trimethyl hexanoate, t-butylperoxy laurate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxy benzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxy acetate, 2,2-di-(t-butylperoxy)butane, t-butylperoxy benzoate, n-butyl-4,4-di-(t-butylperoxy) valerate, di(2-t-butylperoxyisopropyl)benzene, di-t-hexyl peroxide, t-butylcumyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5- dimethyl-2,5-di(t-butylperoxy)hexyne-3, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethyl-butyl hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide.

More preferably, the peroxide is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (e.g., Trigonox® 101 from AKZO or Perhexa® 25B, Perhexa 25B-40, or Perhexa 25B-40MB by NOF Corporation), in order to suppress malodour and residue amount.

As co-agent any one or more selected from the group consisting of ethylene glycol methacrylate (EGDMA), trimethylolpropane methacrylate, triallyl isocyanurate, triallyl cyanurate, diethylene glycol diacrylate, and neophenylene glycol diacrylate may be used. The curing agent and the co-agent are preferably used in a weight ratio (c) to (d) of 1:2-10, more preferably 1:3-7. A particularly preferred combination is (2,5-dimethyl-2,5-di(t-butylperoxy)hexane with EGDMA.

Additives (e)

The composition of the present embodiments may further include additional components. The additional component may include, but is not limited to, colorants, modifiers, finishing agents (e.g., zinc laurate), antioxidants (e.g., monophenol, bisphenol, polyphenol, sulfur, phosphorus-based compounds such as Irganox® 1010, Irgafos® 168, Irganox® 1726 and Irganox PS800 manufactured by BASF), reducing agents, oxygen scavengers, light stabilizers, antacids, pH stabilizers, surface treatment agents, heat stabilizers, colorants, fillers, surfactants, gelling agents, biocides, UV absorbents (e.g., salicylic acid, benzophenone, benzotriazole, cyanoacrylate, and hindered amine), dusting agents (e.g., polyolefin such as polyethylene, silica, talc, calcium carbonate powder), flame retardants, and polyphosphoric acid. In particular large amount of fillers, dusting agents, and similar additives should be avoided, and is preferably kept to at most 5 wt%, preferably at most 2 wt%.

Preferably, the present composition is substantially free of oil as a softener to avoid oil bleeding.

The colorant may include any conventional colorants used in the art, such as color pigments, extender pigments, anti-corrosive pigments, and functional pigments (e.g., phthalocyanine green, titanium, iron blue, iron oxide, lead suboxide, and zinc sulfide).

Component (ft

Polyalkenamers are known. This is a class of unsaturated polymer formed by so-called ringopening methathesis-polymerization (ROMP) of cyclopentene, cyclooctene, cyclopentadiene and/or norbonene, etc. The most common representative of this class is trans-polyoctenamer, generally abbreviated to TOR and commercially available as Vestenamer® from Evonik Degussa GmbH. The properties of TOR are for instance described in “A New Rubber: trans-Polyoctenamer”, by Adolf Draxler in Elastomerics, February 1983, pp. 16-20. Vestenamer is available in 2 grades, 8012 with a trans content of about 80%, and 6213 with a trans content of about 60%. The former is preferred. The product is a mixture of two inseparable components:

Although this reference describes TOR blends, nothing was disclosed with respect to blends of a polyalkenamer, and TOR in particular, in a curable rubber composition, further comprising one or more isoprene polymers having a refractive index of between 1.500 to 1.525 at 23 °C. As illustrated in the examples, the novel composition provides excellent mechanical properties, in combination with a significantly increased abrasion resistance.

Component (f) is present in an amount of more than 4- 30 wt%, preferably in an amount of 4.5 - 25 wt%, more preferably in an amount of 8 - 16 wt%.

The composition of the present embodiments may preferably have 35 or more of Type A Durometer hardness measured at 30 seconds, more preferably from 35 to 70, more further preferably from 40 to 70, still more further preferably from 50 to 70. In the case that the present composition is incorporated to a product to be used under a severe environment, such as footwear (e.g., shoe sole) and rubber tire, the Type A Durometer hardness may preferably be around 60 to 70.

Preferably, the composition has 10 N/mm or more, preferably 10 N/mm to 50 N/mm, more preferably 10 N/mm to 40 N/mm of tear strength measured by 2 mm-thick sheet (and converted in N/mm unit) according to ASTM D624. If the tear strength is less than 10 N/mm, the composition may lack durability.

Preferably, the composition has 120 mm3 or less, preferably 100 mm3 or less, more preferably 50 mm3 or less of abrasion resistance according to ISO 4649, method A. If the abrasion resistance is more than 120 mm3, a shoe sole made therefrom cannot be used for sport shoes.

Manufacturing Procedure

The present invention also provides a process for manufacturing a cured rubber composition, wherein the process comprising the acts of: • mixing components (a), (b) and (f) to obtain a mixture thereof; • adding a curing agent (c) and co-agent (d) to the mixture; and uniformly kneading the mixture and curing the same.

The conditions for mixing and for curing are well-known to a person skilled in the art and depends on the equipment used . It is recommended for curing to use a temperature between 130 and 180 °C at a curing time of 8 to 3 minutes.

Application

The composition of the present embodiments may be used in particular for high abrasion resistant shoe soles.

Examples

Embodiments of the present invention will now be further illustrated with reference to the following examples, however, without restricting its scope to these embodiments.

Table 1

Example 1 (Comparative)

Components (a), (b), and (e) were uniformly kneaded in an open roller at a temperature of ±120°C. Components (c) and (d) were added in an open roller at a temperature of ±75°C and again the mixture was uniformly kneaded. The kneaded rubber was cut off from the roller to a sheet having 2 mm to 3 mm thickness. The sheet was maturated at room temperature for one day and night.

The matured rubber was cured or vulcanized by heating press machine (manufactured by Fontijne Grotnes BV) at the temperature of 150 °C and the pressure of 15 MPa for 6 minutes to obtain a test sample which was subjected under the test procedures discussed hereinbefore to measure the physical and chemical properties. The results are listed in Table 2.

Example 2 (Comparative) 3-5

Example 1 was repeated, now with addition of component (f) in the listed amounts. The results are likewise listed in Table 2.

Example

Example 3 was repeated, but now with neodymium IR as component (a) The results are listed in Table 2.

Table 2

EMBODIMENTS 1. A curable rubber composition, comprising: • Component (a): from 35-50 wt% of one or more isoprene polymers; • Component (b): from 35-50 wt% of one or more polymers different from isoprene polymers; • Components (c) and (d): from 0.05-8.0 wt% of a curing agent optionally with a coagent, and • Component (e): from 0.01-20 wt% of additives, characterized in that the composition further comprises: • Component (f): from more than 4-30 wt% of one or more polyalkenamers, wherein all amounts are in percentages by weight on the total composition. 2. The composition according to claim 1, wherein component (a) is a homopolymer of isoprene. 3. The composition according to claim 1, wherein component (a) is a homopolymer of isoprene, made by anionic polymerization. 4. The composition according to any one of claims 1-3, wherein component (a) is present in an amount of 40-45 wt% 5. The composition according to any one of claims 1-4, wherein component (b) is selected from one or more of the group comprising butadiene polymer, polymers made from C4 to C20 olefins; thermoplastic elastomers (TPEs), styrene-butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), hydrogenated nitrile rubber (HNBR), chloroprene rubber (CR), butyl rubber (MR), fluorine'rubber (FKM), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), urethane rubber. 6. The composition according to claim 5, wherein component (b) is a syndiotactic 1,2-polybutadiene rubber. 7. The composition according to any one of claims 1 to 6, wherein component (b) is present in an amount of 40-45 wt% 8. The composition according to any one of claims 1 to 7, wherein component (c) is a peroxide, preferably 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane. 9. The composition according to claim 8, wherein a co-agent (d) is used in a weight ratio (c) to (d) of 1:2-10, preferably 1:3-7. 10. The composition according to any one of claims 1-9, wherein component (f) is a trans-polyoctenamer, preferably having a trans content of about 80%. 11. The composition according to any one of claims 1-10, having at least one of the following properties:

• A Type A Durometer hardness (30 sec) of 25 or more, measured according to ASTM D2240; • A Tear Strength of 10 N/mm or more, measured according to ASTM D624, and • An abrasion resistance of 120 mm3 or less, measured according to ISO 4649, method A. 12. A process for manufacturing a cured rubber composition from the composition according to any one of claims 1-11, wherein the process comprises the steps of: • mixing components (a), (b) and (f) to obtain a mixture thereof; • adding a curing agent (c) and optionally aco-agent (d); and uniformly kneading the mixture and curing the same. 13. An article based on the composition according to any one of claims 1 to 11 or a having a composition prepared by the process according to claim 12. 14. The article according to claim 13, wherein the article is a shoe sole, preferably a shoe sole for sport shoes, safety shoes, or hiking shoes.

Claims

A curable rubber composition comprising: Component (a) 35-50% by weight of one or more isoprene polymers; Component (b): 35-50% by weight of one or more polymers other than isoprene polymers; Components (c) and (d): 0.05-8.0% by weight of a curing agent, optionally with a co-agent, and • Component (e) 0.01-20% by weight of additives, characterized in that the The composition further comprises: Component (f) of more than 4-30% by weight of one or more polyalkylene chambers, all amounts being weight percentages of the total composition.

The composition of claim 1, wherein component (a) is a homopolymer of isoprene.

The composition of claim 1, wherein component (a) is a homopolymer of isoprene made by anionic polymerization.

The composition of any one of claims 1-3, wherein component (a) is present in an amount of 40-45% by weight

The composition of any one of claims 1-4, wherein component (b) is selected from one or more of the group comprising butadiene polymers, polymers from C4 to C20 olefins; thermoplastic elastomers (TPE), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), hydrogenated nitrile rubber (HNBR), chloroprene rubber (CR), butyl rubber (IIR), fluorine rubber (FKM), ethylene-propylene rubber (EPM ), ethylene-propylene-diene rubber (EPDM), urethane rubber.

The composition of claim 5, wherein component (b) is a syndiotactic 1,2-polybutadiene rubber.

The composition of any one of claims 1 to 6, wherein component (b) is present in an amount of 40-45% by weight

A composition according to any one of claims 1 to 7, wherein component (c) is a peroxide, preferably 2,5-dimethyl-2,5-di (t-butyl peroxy) hexane.

The composition of claim 8, wherein a co-agent (d) is used in a weight ratio (c) to (d) of 1: 2-10, preferably 1: 3-7.

The composition of any one of claims 1-9, wherein component (f) is a trans-polyoctenamer, preferably with a trans content of about 80%.

A composition according to any one of claims 1-10, with at least one of the following properties: • A type A Durometer hardness (30 sec) of 25 or more, measured according to ASTM D2240; • A tear strength of 10 N / mm or more, measured according to ASTM D624, and • A wear resistance of 120 mm3 or less, measured according to ISO 4649, method A.

A method of manufacturing a cured rubber composition from the composition of any one of claims 1 to 11, wherein the method comprises the steps of: mixing components (a), (b) and (f) to obtain a mixture thereof; • adding a curing agent (c) and optionally a co-agent (d); and • uniformly kneading the mixture and curing the same.

An article based on the composition of any one of claims 1 to 11 or having a composition prepared by the method of claim 12.

An article according to claim 13, wherein the article is a shoe sole, preferably a shoe sole for sports shoes, work shoes, or hiking shoes.