HK1069408B - Silica-filled elastomeric compounds - Google Patents

Description

Elastomeric compounds filled with silica

Technical Field

The present invention relates to silica-filled halobutyl elastomers, in particular bromobutyl elastomers (BIIR).

Background

It is well known that reinforcing fillers such as carbon black and silica can significantly improve the strength and fatigue properties of elastomeric compounds. The chemical interactions that occur between elastomers and fillers are also well known. For example, good interaction between carbon black and highly unsaturated elastomers such as polybutadiene (BR) and styrene-butadiene copolymers (SBR) occurs because of the large number of carbon-carbon double bonds present in these copolymers. The carbon-carbon double bonds in butyl elastomers are only one tenth or less of those in BR or SBR, and it is well known that compounds made from butyl elastomers rarely interact with carbon black. For example, compounds prepared by mixing carbon black with a combination of BR and butyl elastomers result in BR domains containing most of the carbon black and butyl domains containing little carbon black. The poor antiwear strength of butyl compounds is also well known.

Canadian patent application 2,293,149 discloses that it is possible to prepare filled butyl elastomer compositions with greatly improved properties by combining halobutyl elastomers with silica and specific silanes. These silanes act as dispersants and linking agents between the halobutyl elastomer and the filler. One disadvantage of using silanes, however, is that there is volatilization of the alcohol during the manufacturing process and possibly during the use of the article made by the above-described method. In addition, silanes substantially increase the cost of the articles produced.

Co-pending Canadian patent application 2,339,080 discloses that filled halobutyl elastomer compounds including organic compounds containing at least one basic nitrogen-containing group and at least one hydroxyl group enhance the interaction of halobutyl elastomers with carbon black and mineral fillers to improve the properties of the compounds, such as tensile strength and abrasion resistance (DIN).

Co-pending Canadian application CA-2,368,363 discloses filled halobutyl elastomer compositions comprising halobutyl elastomer and at least one mineral filler in the presence of an organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group and at least one silazane compound. However, said application does not describe mineral fillers pre-modified with organic and silazane compounds containing at least one basic nitrogen-containing group and at least one hydroxyl group.

Disclosure of Invention

The invention provides a process for preparing a composition comprising a halobutyl elastomer and at least one mineral filler which has been reacted with at least one organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group and optionally with at least one silazane compound before mixing the (pre-reacted) filler with the halobutyl elastomer. In particular, the present invention provides a method of making the filler composition without alcohol volatilization and at a substantially reduced cost as compared to methods known in the art.

It has been found that the interaction of halobutyl elastomers with the pre-reacted filler is enhanced, resulting in enhanced compound properties such as tensile strength and abrasion resistance (DIN). Compounds of this type are believed to assist in dispersing and linking silica to the halogenated elastomer.

Accordingly, in another aspect, the present invention provides a process comprising mixing and curing a filled halobutyl elastomer prepared by mixing a halobutyl elastomer with at least one mineral filler, said mineral filler having been reacted with at least one organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group and optionally with at least one silazane compound, prior to mixing said (pre-reacted) filler with said halobutyl elastomer.

The halobutyl elastomer mixed with the pre-reacted mineral filler (i.e. the filler which has been reacted with at least one organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group and optionally with at least one silazane compound) may be a mixture with other elastomers or elastomeric compounds. The halobutyl elastomer should comprise more than 5% of any of the above mixtures. Preferably, the halobutyl elastomer comprises at least 10% of any one of the above mixtures. More preferably, the halobutyl elastomer comprises at least 50% of any one of the above mixtures. In most cases, it is preferred not to use mixtures, but to use halobutyl elastomers as the sole elastomer. However, if mixtures are used, the other elastomer may be, for example, natural rubber, polybutadiene, styrene-butadiene or polychloroprene or an elastomeric compound containing one or more of the above elastomers.

The filled halobutyl elastomer may be cured to obtain a product having improved properties such as abrasion resistance, rolling resistance and traction (i.e., traction, but hereinafter "traction" is used collectively) properties. Vulcanization may be achieved with sulfur. Preferably, the amount of sulfur is in the range of 0.3 to 2.0 parts by weight per 100 parts by weight of rubber. An activator, such as zinc oxide, may also be used in an amount of 0.5 to 2 parts by weight. Other components such as stearic acid, antioxidants or catalysts (or accelerators, accelerators) may also be added to the elastomer prior to vulcanization. Vulcanization of the sulfur is then effected by known methods. See, for example, chapter 2 "Synthesis and Vulcanization of Rubber" of "Rubber technology" (3 rd edition, Chapman & Hall publication, 1995), The disclosure of which is incorporated herein by reference, which relates to this step.

Other known curatives for curing halobutyl elastomers may also be used. Many compounds are known to cure halobutyl elastomers such as bis dienophiles (e.g., m-phenyl-di-maleamide, HVA2), phenolic resins, amines, amino acids, peroxides, zinc oxide, and the like. Combinations of the above vulcanizing agents may also be used.

The mineral-filled halobutyl elastomer of the present invention may be mixed with other elastomers or elastomeric compounds before it is cured with sulfur.

Detailed description of the preferred embodiments

The term "halobutyl elastomer" as used herein refers to a chlorinated and/or brominated butyl elastomer. Brominated butyl elastomers are preferred, and the invention is illustrated herein by the examples utilizing such brominated butyl elastomers. It will be appreciated, however, that the invention extends particularly to the use of chlorinated butyl elastomers.

By brominating butyl rubber, which is an isoolefin, usually isobutylene, and a comonomer, usually C₄-C₆Copolymers of conjugated diene comonomers, preferably isoprene- (brominated isobutylene-isoprene-copolymer BIIR)) to obtain brominated butyl elastomers. However, comonomers other than conjugated dienes may be used, and alkyl-substituted vinyl aromatic comonomers mentioned, for example C₁-C₄-alkyl substituted styrene. An example of such an elastomer that is commercially available is brominated isobutylene methylstyrene copolymer (BIMS) in which the comonomer is p-methylstyrene.

Typically, the brominated butyl elastomer comprises from 0.1 to 10 weight percent of repeating units derived from a diene, preferably isoprene, and from 90 to 99.9 weight percent of repeating units derived from an isoolefin, preferably isobutylene, based on the hydrocarbon content of the polymer, and from 0.1 to 9 weight percent bromine, based on the brominated butyl polymer. Typical brominated butyl polymers have a molecular weight expressed as Mooney viscosity in accordance with DIN53523(ML1+8, 125 ℃), which is in the range of 25-60.

For use in the present invention, the brominated butyl elastomer preferably contains from 0.5 to 5 weight percent of repeat units derived from isoprene (based on the hydrocarbon content of the polymer) and from 95 to 99.5 weight percent of repeat units derived from isobutylene (based on the hydrocarbon content of the polymer) and from 0.2 to 3 weight percent, preferably from 0.75 to 2.3 weight percent, of bromine (based on the brominated butyl polymer).

Stabilizers may be added to the brominated butyl elastomer. Suitable stabilizers include calcium stearate and hindered phenols, preferably used in amounts ranging from 0.5 to 5 parts by weight per 100 parts by weight of brominated butyl rubber (phr).

Examples of suitable bromobutyl elastomers include Bayer Bromobutyl elastomer available from Bayer corporation2030，Bayer Bromobutyl2040(BB2040), and Bayer BromobutylX2. Bayer BB2040 has a Mooney viscosity (ML1+8@ 125 ℃ C.) of 39. + -.4, a bromine content of 2.0. + -. 0.3 wt.% and a weight average molecular weight of about 500,000 g/mole.

The brominated butyl elastomer used in the process of the present invention may also be a graft copolymer of brominated butyl rubber and a polymer based on conjugated diene monomers. Our co-pending Canadian patent application 2,279,085 relates to a process for the preparation of such graft copolymers by mixing solid brominated butyl rubber with a solid polymer based on conjugated diene monomers which also contain some C-S- (S) n-C bonds, where n is an integer between 1 and 7, at a temperature above 50 ℃ for a time sufficient to effect grafting. The disclosure of which is incorporated herein by reference to this step. The brominated butyl elastomer of the graft copolymer can be any of the foregoing. The conjugated dienes that may be incorporated into the graft copolymer generally have the formula:

wherein R is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R1 and R11 may be the same or different and are selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 4 carbon atoms. Some representative, but non-limiting, examples of suitable conjugated dienes include 1, 3-butadiene, isoprene, 2-methyl-1, 3-pentadiene, 4-butyl-1, 3-pentadiene, 2, 3-dimethyl-1, 3-pentadiene, 1, 3-hexadiene, 1, 3-octadiene, 2, 3-dibutyl-1, 3-pentadiene, 2-ethyl-1, 3-butadiene, and the like. Preferred conjugated diene monomers contain 4 to 8 carbon atoms, with 1, 3-butadiene and isoprene being particularly preferred.

The polymer based on a conjugated diene monomer may be a homopolymer, or a copolymer of two or more conjugated diene monomers, or a copolymer of the same vinyl aromatic monomer.

The vinyl aromatic monomer to be used is selected so as to be copolymerizable with the conjugated diene monomer to be used. In general, any of the well-known vinyl aromatic monomers that are polymerizable with organo alkali metal initiators can be used. Such vinyl aromatic monomers generally contain from 8 to 20 carbon atoms, preferably from 8 to 14 carbon atoms. Examples of some vinyl aromatic monomers that can be so copolymerized include styrene, alpha-methylstyrene, various alkylstyrenes including p-methylstyrene, p-methoxystyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 4-vinyltoluene, and the like. Preferably, styrene is copolymerized with 1, 3-butadiene alone or with 1, 3-butadiene and isoprene to produce a trimerization.

The halobutyl elastomer may be used alone or in combination with other elastomers such as:

BR-polybutadiene

ABR-butadiene/C₁-C₄Alkyl acrylate copolymers

CR-polychloroprene

IR-polyisoprene

SBR-styrene/butadiene copolymer with a styrene content of 1 to 60% by weight, preferably 20 to 50% by weight

IIR-isobutylene/isoprene copolymer

NBR-butadiene/acrylonitrile copolymer, wherein the acrylonitrile content is 5 to 60% by weight, preferably 10 to 40% by weight

HNBR-partially or completely hydrogenated NBR

EPDM-ethylene/propylene/diene copolymers

The filler is composed of mineral particles, examples of which include silica, silicates, clays (e.g., bentonite), gypsum, alumina, titanium dioxide, talc, and the like, and mixtures thereof.

Examples may also be:

highly dispersible silicas, prepared, for example, by precipitation of silicate solutions or by pyrohydrolysis of silicon halides, with specific surface areas of 5 to 1000m²A/g, preferably from 20 to 400m²(ii)/g (BET specific surface area) and a primary particle size of 10 to 400nm, optionally in the form of a mixed oxide with other metal oxides such as Al, Mg, Ca, Ba, Zn, Zr and Ti;

synthetic silicates, such as aluminum silicate and alkaline earth metal silicate;

magnesium or calcium silicate having a BET specific surface area of 20 to 400m²A/g and a primary particle diameter of 10 to 400 nm;

natural silicates, such as kaolin and other naturally occurring silicas;

glass fibers and glass fiber products (matting, extrudates) or glass microspheres;

metal oxides, such as zinc oxide, calcium oxide, magnesium oxide and aluminum oxide;

metal carbonates, such as magnesium carbonate, calcium carbonate and zinc carbonate;

metal hydroxides, such as aluminum hydroxide and magnesium hydroxide; or a combination thereof.

The above mineral particles have hydroxyl groups on their surface, so that they have hydrophilicity and oleophobicity. This exacerbates the difficulty of obtaining good interaction between the filler particles and the butyl elastomer. For many applications, the preferred mineral is silica, particularly silica prepared by carbon dioxide precipitation of sodium silicate.

According to the present invention, it is suitable to use dried amorphous silica particles having an average agglomerate particle size of from 1 to 100 microns, preferably from 10 to 50 microns, most preferably from 10 to 25 microns. Preferably the volume percentage of agglomerated particles having a size of less than 5 microns and greater than 50 microns is less than 10. Furthermore, suitable dried amorphous silicas have BET surface areas of from 50 to 450 m/g, measured in accordance with DIN (Deutsche Industrie norm) 66131; DBP adsorption of 150-400 g/100 g of silica according to DIN53601 and a drying loss of 0-10% by weight according to DIN ISO 787/11. Suitable silica fillers are available commercially from PPG Industries Inc. under the HiSil trademark210、HiSil233 and HiSil243, respectively. Also suitable is Vulkasil from Bayer AGS and VulkasilN.

The mineral fillers may also be used in combination with known non-mineral fillers such as;

-carbon black; the carbon blacks used here are prepared by the lamp black, furnace black or gas black process, for example SAF, ISAFHAF, FEF or GPF, and the BET specific surface area of the carbon black is 20 to 200m²/g；

Or

Rubber gels, in particular those based on polybutadiene, butadiene/styrene copolymers, butadiene/acrylonitrile copolymers and polychloroprene (polychloroprene).

Non-mineral fillers are generally not used as fillers in the halobutyl elastomer compositions of the present invention, but in some embodiments they may be present in amounts up to 40 phr. In these cases, the mineral filler preferably constitutes at least 55% by weight of the total weight of the filler. If the halobutyl elastomer composition of the present invention is blended with another elastomer composition, the other composition may include mineral and/or non-mineral fillers.

The silazane compound can have one or more silazane groups, such as disilazane. Organosilicon azane compounds are preferred. Examples include, but are not limited to, Hexamethyldisilazane (HDMZ), heptamethyldisilazane, 1, 3, 3-tetramethyldisilazane, 1, 3-bis (chloromethyl) tetramethyldisilazane, 1, 3-divinyl-1, 1, 3, 3-tetramethyldisilazane, and 1, 3-diphenyltetramethyldisilazane.

The organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group is not limited to a specific type of compound. Examples include proteins, aspartic acid, 6-aminocaproic acid and other compounds containing amino and alcohol functional groups, such as diethanolamine and triethanolamine. Preferably, the organic compound comprising at least one basic nitrogen-containing group and at least one hydroxyl group comprises one primary alcohol group and one amino group separated by a methylene bridge, which may be branched. Such compounds have the general formulA HO-A-NH₂Wherein A represents C₁-C₂₀The alkenyl group of (a), which is linear or branched.

More preferably, the number of methylene groups between the two functional groups should be in the range of 1 to 4. Examples of preferred additives include ethanolamine and N, N-Dimethylaminoethanol (DMAE).

The amount of pre-reacted filler to be added to the halobutyl elastomer may vary between wide ranges. The fillers are typically used in amounts of 20 to 250 parts by weight per 100 parts by weight of elastomer, preferably 30 to 100 parts by weight per 100 parts by weight of elastomer, more preferably 40 to 80 parts by weight per 100 parts by weight of elastomer. The amount of silazane compound contained in the filler, in the presence of a silazane compound, is generally from 0.3 to 10 parts by weight per 100 parts by weight of elastomer, preferably from 0.5 to 6 parts by weight per 100 parts by weight of elastomer, more preferably from 1 to 5 parts by weight per 100 parts by weight of elastomer. The amount of the hydroxyl-and amino-group-containing compound contained in the filler is usually 0.5 to 10 parts by weight per 100 parts by weight of the elastomer, preferably 1 to 3 parts by weight per 100 parts by weight of the elastomer. Before mixing the pre-reacted filler with the elastomer, the mineral filler is reacted with at least one organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group and optionally with at least one silazane compound. The mineral filler (e.g. silica, such as HiSil) is stirred rapidly233) Suspended in an organic diluent (for example hexane) to effect the reaction between the filler and said organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group and optionally with said silazane compound (derivatization of the filler). Once a stable suspension is obtained, the organic substance containing at least one basic nitrogen-containing group and at least one hydroxyl group and optionally a silazane compound and/or other additives may be added in suitable amounts. After completion of the reaction (preferably after 8 hours), the pre-reacted filler is separated from the organic phase and dried (optionally to constant weight in vacuo).

Furthermore, up to 40 parts by weight per 100 parts by weight of elastomer, preferably 5 to 20 parts by weight per 100 parts by weight of processing oil, may be present in the final mixture containing the pre-reacted filler and elastomer. Furthermore, lubricating oils, such as fatty acids (e.g., octadecanoic acid), may be present in amounts of up to 3 parts by weight, more preferably up to 2 parts by weight.

Suitably, the halobutyl elastomer, the pre-reacted filler and optionally other fillers are mixed together at a temperature in the range of from 25 to 200 ℃. Preferably, the temperature of one of the mixing steps is above 60 ℃, with a temperature in the range of 90-150 ℃ being particularly preferred. Typically, the mixing time does not exceed 1 hour, and a time of 2 to 30 minutes is generally suitable. The mixing is suitably carried out in a two-roll roller mixer which disperses the filler well into the elastomer. Mixing can also be carried out in a Banbury mixer or a Haake or Brabender miniature internal mixer. The extruder may also provide good mixing and also has the further advantage of allowing shorter mixing times. Mixing in two or more steps is also possible. Furthermore, the mixing can be carried out in different apparatuses, for example in an internal mixer in one stage and in an extruder in another stage.

The enhanced interaction between the filler and the halobutyl elastomer results in enhanced improvement in the properties of the filled elastomer. These enhanced and improved properties include higher tensile strength, higher abrasion resistance, lower permeability, and better dynamic properties. This makes the filled elastomers particularly suitable for many applications including, but not limited to, use in automotive outer belts and wheel station sidewalls, tire innerliners, tank liners, hose, rollers, conveyor belts, curing bladders, gas masks, pharmaceutical enclosures and liners.

In a preferred embodiment of the invention, the bromobutyl elastomer, the pre-reacted silica particles, and optionally the processing oil additive are mixed in a two-roll mill at the nominal milling temperature (25 ℃), and then the mixed compound is placed in a two-roll mill and mixed at a temperature above 60 ℃. It is preferred that the temperature of mixing is not too high, more preferably not more than 150 c, because higher temperatures can lead to over-vulcanization, thereby preventing subsequent processing. The product obtained by mixing the above four ingredients at a temperature not exceeding 150 ℃ is a compound having good stress/strain characteristics and which is easily further processed in heated rolls to which a vulcanizing agent is added.

The filled halobutyl rubber compositions of the present invention, and particularly the filled bromobutyl rubber compositions, have many uses, but particular mention is made of their use in automotive out-of-band compositions.

The invention is further illustrated by the following examples.

Examples

Description of the test

Abrasion resistance strength:

DIN53-516(60 coarse grinding sand paper)

Dynamic property test:

RPA was measured by using Alpha Technologies, and RPA2000 was operated at 6cpm frequency at 100 ℃. Strain scans were measured at strains of 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50 and 90 °. Stress strain samples were prepared by vulcanizing a large sheet at 170 ℃ for tc90+5 minutes, after which the appropriate samples were dried. The test was carried out at 70 ℃.

Vulcanization rheometry:

ASTM D52-89 MDR2000E rheometer, 1 ° radian and 1.7Hz

Description of the Components and Total mixing procedure

Hi-Sil233-silica-PPG product

Sunpar2280-Sun Oil-made StoneWaxy oil

MagliteMagnesium oxide prepared by D-CP Hall

Brominated butyl elastomer (commercial Bayer in all cases)Bromobutyl 2030), silica, oil, and pre-reacted filler are mixed in any of the following ways:

i) the tangential Banbury internal mixer was operated at 77rpm while the temperature was set to 40 ℃ using Mokon. The total time to mix the compounds was 6 minutes. The final rubber temperature was 140 ℃ and 180 ℃.

ii) one of 10¹¹×20¹¹The rollers of the two-roller mill of (1) were operated at 24rpm and 32 rpm. The grinding roll was set at 25 ℃ and the total time of the synthesis was 10 minutes. The mixed compounds were then "heat treated" for an additional 10 minutes with the roller temperature at 110 ℃. The final rubber temperature was 125 ℃.

The vulcanizing agent was then added to the cooled sample, the mill temperature being 25 ℃.

Examples 1a and 1b (comparative examples)

The following examples illustrate the use of HMDZ functionalized silica in bromobutyl composition (1a) as compared to the use of non-functionalized silica in bromobutyl composition (1 b). Suspending HiSi in hexane by rapid stirring233 to prepare functionalized silica. Once a stable suspension was obtained, a defined amount of HMDZ was added with a disposable syringe. The functionalization reaction was allowed to proceed for 8 hours with stirring. At this point, the silica was separated from the organic phase and dried to constant at 60 ℃And (4) weight. Use 10¹¹×20¹¹The mill of (1) was mixed with the brominated butyl compositions (1a) and (1b) subsequently prepared by functionalizing (1a) silica and non-functionalizing (1b) silica. The synthetic procedure involved mixing butyl bromide (BB2030) with silica at 10 deg.C¹¹×20¹¹In a mill. Once the silica entered the BB2030, the composition was heat treated in a mill at a temperature of 110 ℃. Then use 10¹¹×20¹¹Mill, add vulcanising agents (sulphur, octadecanoic acid and zinc oxide) at room temperature. Details regarding the preparation of silica and subsequent bromobutyl compositions are given in table 1.

The physical properties of the resulting composition are listed in table 2. As can be seen from these data, the use of HMDZ functionalized silica (1a) greatly reduced the DIN abrasion volume loss of the comparative composition (1b) prepared in a similar manner but using unmodified HiSil 233. Interestingly, the composition prepared using the HMDZ functionalized silica was found to have a longer t03 time compared to the comparative composition (Mooney scorch indicates that the greater the t03 time, the better the scorch safety).

RPA analysis (fig. 1) of the composition prepared using HMDZ functionalized silica shows a significant enhancement in the distribution of filler compared to the comparative composition based on unmodified HiSil 233, as evidenced by the lower value of G at low strain. The stress-strain diagram (fig. 2) shows that there is little difference between the composition and the comparative composition.

Examples 2a (according to the invention) and 2b (comparative example)

The following examples illustrate the use of DMAE functionalized silica in bromobutyl composition (2a) as compared to the use of non-functionalized silica in bromobutyl composition (2 b). Suspending HiSi in hexane by rapid stirring233 to prepare functionalized silica. Once a stable suspension has been obtained, the suspension is usedA disposable syringe added a defined amount of DMAE. The functionalization reaction was allowed to proceed for 8 hours with stirring. At this point, the silica was separated from the organic phase and dried to constant weight at 60 ℃. Use 10¹¹×20¹¹The mill of (2) mixes a bromobutyl composition subsequently prepared by the functionalized silica (2a) and the non-functionalized silica (2 b). The synthetic procedure involved mixing butyl bromide (BB2030) with silica at 10 deg.C¹¹×20¹¹In a mill. Once the silica entered the BB2030, the composition was heat treated in a mill at a temperature of 110 ℃. Then use 10¹¹×20¹¹Mill, add vulcanising agents (sulphur, octadecanoic acid and zinc oxide) at room temperature. Details regarding the preparation of silica and subsequent bromobutyl compositions are given in table 3.

The physical properties of the resulting composition are listed in table 4. As can be seen from these data, the use of DMAE functionalized silica greatly reduced the DIN abrasion volume loss of the comparative composition and composition (1a) prepared in a similar manner but using unmodified HiSil 233. Importantly, the composition prepared using DMAE functionalized silica was found to have a t03 time only slightly lower than the comparative composition. However, the t03 time was much longer than for the composition where DMAE was added to a mixture of BB2030 and HiSil 233 via conventional mixing methods (see co-pending canadian patent application 2,339,080).

RPA analysis (fig. 3) of a composition prepared using DMAE-functionalized silica shows a significant enhancement in the distribution of filler as compared to a comparative composition based on unmodified HiSil 233, as is G at low strain^*As evidenced by the lower values. The stress-strain plot (fig. 4) shows that the degree of enhancement is greatly increased compared to the comparative composition.

Examples 3a (according to the invention) and 3b (comparative example)

The following examples illustrate the use of non-functionalized silica in bromobutyl compositions (3b)Use of HMDZ/DMAE functionalized silica in composition (3a) (used in an amount corresponding to 1.45phr of HMDZ and 2.8phr of DMAE in the final bromobutyl compound). Functionalized silica was prepared by suspending HiSil 233 in hexane with rapid stirring. Once a stable suspension was obtained, the prescribed amounts of HMDZ and DMAE were added with a single-use syringe. The functionalization reaction was allowed to proceed for 8 hours with stirring. At this point, the silica was separated from the organic phase and dried to constant weight at 60 ℃. Use 10¹¹×20¹¹The mill of (3) mixes a bromobutyl composition subsequently prepared by the functionalized silica (3a) and the non-functionalized silica (3 b). The synthetic procedure involved mixing butyl bromide (BB2030) with silica at 10 deg.C¹¹×20¹¹In a mill. Once the silica entered the BB2030, the composition was heat treated in a mill at a temperature of 110 ℃. Then use 10¹¹×20¹¹Mill, add vulcanising agents (sulphur, octadecanoic acid and zinc oxide) at room temperature. Details regarding the preparation of silica and subsequent bromobutyl compositions are given in table 5.

The physical properties of the resulting composition are listed in table 6. As can be seen from these data, the use of HMDZ/DMAE functionalized silica greatly reduced the DIN abrasion volume loss of the compound compared to the comparative composition and compositions 1a and 2a prepared in a similar manner but using unmodified HiSil 233. Importantly, the composition prepared using HMDZ/DMAE functionalized silica was found to have a longer t03 time as compared to the comparative composition. As with the previous examples, the t03 time was much longer than for the composition in which HMDZ and DMAE were added to a mixture of BB2030 and HiSil 233 via conventional mixing methods (see co-pending canadian patent application 2,339,080).

RPA analysis (fig. 5) of a composition prepared using HMDZ/DMAE functionalized silica shows a significant enhancement in the distribution of filler as compared to a comparative composition based on unmodified HiSil 233, as is G at low strain^*As evidenced by the lower values. Importantly, silica that had been modified by HMDZ and DMAE (comparative example 1 and example 2)The degree of filler distribution is enhanced. The stress-strain plot (fig. 6) shows that the degree of enhancement is greatly increased compared to the comparative composition.

Examples 4a (according to the invention) and 4b (comparative example)

The following examples illustrate the use of HMDZ/DMAE functionalized silica in bromobutyl composition (4a) (used in an amount equivalent to 1.45phr of HMDZ and 3phr of DMAE in the final bromobutyl compound) as compared to the use of non-functionalized silica in bromobutyl composition (4 b). Functionalized silica was prepared by suspending HiSil 233 in hexane with rapid stirring. Once a stable suspension was obtained, the prescribed amounts of HMDZ and DMAE were added with a single-use syringe. The functionalization reaction was allowed to proceed for 8 hours with stirring. At this point, the silica was separated from the organic phase and dried to constant weight at 60 ℃. Use 10¹¹×20¹¹The mill of (4) mixes a bromobutyl composition prepared subsequently by means of functionalized silica (4a) and non-functionalized silica (4 b). The synthetic procedure involved mixing butyl bromide (BB2030) with silica at 10 deg.C¹¹×20¹¹In a mill. Once the silica entered the BB2030, the composition was heat treated in a mill at a temperature of 110 ℃. Then use 10¹¹×20¹¹Mill, add vulcanising agents (sulphur, octadecanoic acid and zinc oxide) at room temperature. Details regarding the preparation of silica and subsequent bromobutyl compositions are given in table 7.

The physical properties of the resulting composition are listed in table 8. As can be seen from these data, the use of HMDZ/DMAE functionalized silica greatly reduced the DIN abrasion volume loss of the compound compared to the comparative composition and compositions 1a and 2a prepared in a similar manner, but using unmodified HiSil 233. Importantly, the composition prepared using HMDZ/DMAE functionalized silica was found to have a longer t03 time as compared to the comparative composition. As with the previous examples, the t03 time was much longer than for the composition in which HMDZ and DMAE were added to a mixture of BB2030 and HiSil 233 via conventional mixing methods (see co-pending canadian patent application 2,339,080).

RPA analysis (fig. 7) of the composition prepared using DMAE functionalized silica shows a significant enhancement in the distribution of filler compared to the comparative composition based on unmodified HiSil 233, as evidenced by the lower value of G at low strain. Importantly, the silica that has been modified with HMDZ and DMAE (comparative example 1 and example 2) provides an enhanced degree of filler distribution. The stress-strain plot (fig. 8) shows that the degree of enhancement is greatly increased compared to the comparative composition.

The detailed examples above serve to illustrate the advantages of using pre-functionalized silica in bromobutyl compounds. Compositions prepared with HMDZ functionalized silica were found to have enhanced levels of filler dispersion, abrasion resistance (DIN), and scorch safety. However, the best results were obtained with compositions prepared with DMAE or HMDZ/DMAE functionalized silica. In particular, the best balance of properties is obtained with silicas modified with DMAE or HMDZ/DMAE.

TABLE 1

BB2030	100	100
			Silica	60	60
Sulfur	0.5	0.5
			Stearic acid	1	1
Zinc oxide	1.5	1.5

TABLE 3

TABLE 5

Sulfur	0.5	0.5
			Stearic acid	1	1
Zinc oxide	1.5	1.5

TABLE 7

TABLE 2

TABLE 4

TABLE 6

TABLE 8

Claims (11)

1. A process for preparing a filled halobutyl elastomer comprising mixing at least one halobutyl elastomer with at least one mineral filler which has been reacted with at least one organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group and with at least one silazane compound, wherein said silazane compound is an organosilicon azane compound, prior to mixing said mineral filler with said halobutyl elastomer.

2. The method of claim 1, wherein the organic compound comprising at least one basic nitrogen-containing group and at least one hydroxyl group comprises a primary alcohol group or a carboxylic acid group.

3. The method of claim 1, wherein the organic compound comprising at least one basic nitrogen-containing group and at least one hydroxyl group comprises one primary alcohol group and one amino group separated by a methylene bridge which may be branched.

4. The process of claim 1, wherein the organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group comprises one carboxylic acid group and one amino group separated by a methylene bridge which may be branched.

5. The method of any one of claims 1-4, wherein the organic compound comprising at least one basic nitrogen-containing group and at least one hydroxyl group is selected from the group consisting of: monoethanolamine, N-dimethylaminoethanol, natural or synthetic amino acids, natural or synthetic proteins.

6. The method of any of claims 1-4, wherein the silazane compound is a disilazane compound.

7. The method of any of claims 1-4, wherein the mineral filler is selected from the group consisting of ordinary or highly dispersible silica, silicates, clay, gypsum, alumina, titanium dioxide, talc, and mixtures thereof.

8. The process of any one of claims 1-4, wherein the halobutyl elastomer is a brominated butyl elastomer.

9. The process according to any one of claims 1 to 4, wherein the amount of the organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group is in the range of 0.5 to 10 parts by weight per 100 parts by weight of elastomer.

10. The process as claimed in any of claims 1 to 4, wherein the silazane is present in an amount in the range from 0.5 to 10 parts by weight per 100 parts by weight of elastomer.

11. A method of enhancing the abrasion resistance of a filled, cured elastomer composition comprising at least one halobutyl elastomer, said method comprising mixing said halobutyl elastomer with said at least one mineral filler, and said mineral filler having been reacted prior to mixing with said halobutyl elastomer with at least one organic compound and with a silazane compound, said organic compound containing at least one basic nitrogen-containing group and at least one hydroxyl group, and said silazane compound being an organosilicon azazane compound, and curing said elastomer composition.