A self-reinforced polymeric composition of matter comprising a plurality of hard domains dispersed throughout an elastomeric matrix, wherein the plurality of hard domains are formed by thermodynamic phase separation and crosslinking of at least one thermosettable domain block of a polymeric precursor and are substantially bonded to the elastomeric matrix.

This invention relates to self-reinforced rubbery compositions. These rubbery compositions comprise a rubbery matrix having glassy thermoset domains dispersed therein with covalent bonding between the rubbery matrix and the thermoset domains. The invention also relates to a method for making these compositions.
It is desirable for rubbers used in severe dynamic applications, such as tires, to possess minimal hysteresis loss to provide low rolling resistance and low running temperature. Rubbers however, must be somewhat hysteretic in order to exhibit resistance to crack growth, crack propagation, and abrasion. Generally, when an elastomer is deformed, part of the input energy is stored elastically in the chains and is available as a driving force for fracture (i.e., will be released upon crack growth), while the remainder of the energy is dissipated through molecular motions into heat.
At high crosslink levels, when hysteresis loss is typically low, chain motions become quite restricted and the xe2x80x9ctightxe2x80x9d network cannot dissipate much energy. As a result, these networks, may suffer from brittle fracture at low elongation. Rubbers exhibiting high hysteresis loss, which typically have low crosslink levels, can have high tear strength at room temperature. These rubbers, however, are unsuited for dynamic applications because the substantial heat generation and concomitant temperature rise that occurs during these applications weakens the rubbers. Therefore, the art has generally sought to provide rubbers for dynamic applications that exhibit low hysteresis at small strains and become highly hysteretic at high strains.
One approach has been to disperse particulate filler within the rubber. This creates a rubber having hard domains of particulate filler dispersed within a soft rubber matrix. The addition of particulate fillers tends to reduce abrasion and crack growth rates by increasing high strain modulus and energy dissipation at high strains. The incorporation of particulate filler, however, also increases hysteresis loss at small strains. This results in an unwanted increase in power consumption and heat generation. Therefore, there is a desire in the art to provide reinforcement within a rubber matrix while maintaining low hysteresis loss at small strain.
Limited bonding between rubber and carbon black may be one source of undesirable, low strain hysteresis loss. Much effort has been made to try to lower hysteresis and enhance reinforcement by increasing the interaction of carbon black with rubber. Approaches have included heat treatment of carbon black/rubber mixes, functionalization of carbon black and the diene rubber, and the addition of a carbon black/rubber coupling agent.
More success has been achieved in enhancing filler/rubber interaction in the case of silica-filled rubber. By using a silane coupling agent, e.g., bis-(3-triethoxysilylpropyl)-tetrasulfane, with an extended high temperature mixing cycle, tire tread compounds reinforced with silica can exhibit reduced rolling resistance, while maintaining good wet skid and abrasion resistance.
The approach herein to creating a morphology of hard domains dispersed in a rubbery matrix includes thermodynamic phase separation. The concept of thermodynamic phase separation has been used to prepare many elastomers where the end blocks are thermoplastic. SBS (polystyrene-b-polybutadiene-b-polystyrene), SIS (polystyrene-b-polyisoprene-b-polystyrene), SEBS (styrene-b-ethylene butylene diene-b-styrene), SNBS (styrene-b-nitrile-b-styrene), SAS (styrene-b-acrylic-b-styrene), SCS (styrene-b-chloroprene-b-styrene), and SEPS (styrene-b-ethylene propylene diene-b-styrene) tri-block copolymers are examples. The phase separated polystyrene domains are a few hundred angstroms in size. These elastomers have high hardness, high strength, and high extensibility.
These elastomers, however, are unsuitable for high dynamic loading applications, such as tires, because the end block polystyrene is, by design, a thermoplastic elastomer that creeps and weakens quickly as temperature is increased. It has been found that these problems can be remedied by transforming the end blocks into hard glassy thermosets during the final molding of the elastomers. This structure mimics, in many ways, particulate filled rubber in that both contain non-hysteretic, temperature insensitive, hard domains dispersed within an elastomer matrix. These mesophase separated tri-block elastomers, however, all include rubber chains that are linked to hard domains while in particulate filled compositions the rubber chains either do not interact or interact weakly with the filler.
While attempts have been made to control domain sizes and the degree of bonding between hard domains dispersed within a rubber matrix, the art has not provided a facile means or device by which this can be accomplished. This is especially true where the monomers, pre-polymers, or copolymers are non-polar such as the precursors for hydrocarbon rubbers.
It has now been found that the benefits realized by incorporating reinforcing fillers within polymeric compositions can be achieved by a polymeric composition of matter that includes an elastomeric matrix having dispersed therein reinforcing domains that are chemically bound to the elastomeric matrix. These polymeric compositions may be referred to as self-reinforced elastomeric compositions.
In general the present invention provides a self-reinforced polymeric composition of matter comprising a plurality of hard domains dispersed throughout an elastomeric matrix, wherein the plurality of hard domains are formed by thermodynamic phase separation and selective crosslinking of at least one thermosettable domain block of a polymeric precursor and are substantially bonded to the elastomeric matrix.
The present invention also includes a method for producing a self-reinforced polymeric composition having glassy thermoset domains disbursed in an elastomeric matrix comprising the steps of selecting a thermodynamically separable polymeric precursor having at least one thermosettable domain block and at least one matrix block, and selectively crosslinking the at least one thermosettable domain block of the polymeric precursor with substantially no crosslinking of the at least one matrix block.
The self-reinforced rubbery compositions have glassy thermoset domains dispersed within a rubbery matrix. The thermoset domains are chemically bound to the rubbery matrix, which may be slightly crosslinked. More particularly, the rubber compositions are di-block, tri-block, or star-block copolymers that contain at least one thermoset block. The other blocks remain uncrosslinked or are lightly crosslinked. Thus, the at least one crosslinked block provides the thermoset domains and the other uncrosslinked or lightly crosslinked blocks provide the rubbery matrix. Optionally, other additives may be present in the rubbery compositions including those additives typically employed in rubber compositions, as well as those that may provide desirable characteristics to the self-reinforced rubbery compositions.
The glassy thermoset domains are irreversibly crosslinked and preferably have a high crosslink density sufficient to provide thermoset domains having high glass transition temperature. Preferably, the glass transition temperature of these thermoset domains should be greater than about 100xc2x0 C. and even more preferably greater than about 150xc2x0 C.
The glassy thermoset domains are mesophase separated from the rubbery matrix in which they are dispersed. Mesophase refers to phases that are less than about 100 nanometers in size and preferably about 10 to 90 nanometers in size.
The rubbery matrix can include any rubbery polymer. Non-limiting examples of rubber polymers include those deriving from conjugated diene monomers and copolymers of conjugated diene monomers and vinyl aromatic monomers.
The rubbery polymers preferably have a glass transition temperature below about xe2x88x9225xc2x0 C. and more preferably below about xe2x88x9250xc2x0 C. The number average molecular weight of these rubbery polymers, as determined by GPC with a polystyrene standard, is preferably from about 100,000 to about 700,000, as measured between bonds to the glassy thermoset domain, although the present invention should not be limited thereto or thereby.
The rubbery matrix may be partially crosslinked. The degree of crosslinking, however, should not be so great as to impart a brittle characteristic to the rubbery matrix.
The rubbery polymers of the rubbery matrix are chemically bonded, preferably covalently bonded, to the glassy thermoset domains. This may include a bond at one end of a particular polymer or at both ends of a rubbery polymer.
The self-reinforced rubbery compositions are preferably prepared by selectively crosslinking certain blocks of a polymeric precursor. A polymeric precursor is as a block copolymer or star-block polymer that has at least two thermodynamically-incompatible blocks. Thermodynamically-incompatible blocks are rubbery blocks that will mesophase separate. Thermodynamically incompatible refers to those blocks of the polymeric precursor that will thermodynamically separate such that at least one block will separate from the others to form mesophase domains embedded in a matrix provided by the other blocks of the polymer. Thermodynamically separate refers to a process whereby blocks having distinct thermodynamic characteristics will separate into distinct phases upon the introduction of energy.
The polymeric precursor can include multi-block polymers, such as a di-block, tri-block or star-block polymers, that will thermodynamically separate into mesophases. In the case of tri-block polymers, the blocks can be referred to as end blocks and center-blocks. In the case of a star-block polymers, the phases may be referred to as the core and the arms.
Useful polymeric precursors include at least one domain that is capable of being selectively crosslinked to form a thermoset domain. These thermosettable domain blocks should be capable of being made thermoset by reaction with a crosslinking agent without the occurrence of substantial crosslinking of the matrix blocks of the polymeric precursor. The thermosettable domain block of the polymer precursor is that block that will be selectively crosslinked by the crosslinking agent to form the glassy thermoset domains. It should be understood, however, that the matrix block is likewise thermosettable, but will not be referred to as the thermosettable domain block because it is not the block being targeted for selective crosslinking to form the thermoset domain.
Examples of polymeric precursors include, but are not limited to, tri-block copolymers of 1,2-polybutadiene-b-1,4-polybutadiene-b-1,2-polybutadiene, 1,4-polyisoprene-b- 1,2-polybutadiene-b-1,4 polyisoprene, ethylidene norbornene-b-polydiene-b-ethylidene norbornene, styrene-b-polydiene-b-ethylidene norbornene, 1,2-polybutadiene-Sx-b-1,4-polybutadiene-Sx-b-1,2-polybutadiene wherein x is an integer from about 1 to 10 and S is a polysulfide linkage, styrene-b-butadiene-b-styrene, styrene-b-isoprene-b-styrene, styrene-b-ethylene butylene diene-b-styrene, styrene-b-nitrile-b-styrene, styrene-b-acrylic-b-styrene, styrene-b-chloroprene-b-styrene, styrene-b-ethylene propylene diene-b-styrene; di-block copolymers of 1,2-polybutadiene-b-1,4-polybutadiene, polybutadiene-b-polystyrene, 1,4-polyisoprene-b-1,2-polybutadiene, ethylidene norbomene-b-polydiene, 1,2-polybutadiene-Sx-b-1,4-polybutadiene wherein x is an integer from about 1 to 10 and S is a polysulfide linkage, styrene-b-butadiene, styrene-b-isoprene, styrene-b-ethylene butylene diene, styrene-b-nitrile, styrene-b-acrylic, styrene-b-chloroprene, and styrene-b-ethylene propylene diene; and or star-block copolymers. As is generally known in the art, any of the above-mentioned di-block or tri-block copolymers can be provided as star-block copolymers wherein the core of the star-block copolymer corresponds to one block present in the di-block or tri-block copolymer and the arms of the star-block copolymer correspond to the other block or blocks of the di-block or tri-block copolymer. It should, however, be appreciated that those of ordinary skill in the art will be able to select useful polymeric precursors based upon the characterization of useful polymeric precursors given hereinabove and in light of further disclosures provided hereinbelow.
In one embodiment a block of the polymeric precursor is a polydiene and the other block, or blocks in the case of a tri-block or star-block, is ethylidene norbornene (ENB). The ENB not only introduces unsaturation into the block that will thermoset (the thermosettable domain block) but it also increases the Tg of the resulting hard, glassy thermoset domain. It is also preferred to use in a tri-block a polydiene center-block and end blocks which are styrene/ENB copolymers. Preferred for these systems is polystyrene hydroperoxide. A more in depth discussion of crosslinking agents useful in the present invention is provided hereinbelow.
As should be apparent from the general definition of useful polymeric precursors given hereinabove, the polymeric precursors need not be tri-block copolymers. Indeed, in yet another embodiment, a di-block copolymer is used instead of the tri-block copolymer. As examples, a 1,2-polybutadiene-b-1,4-polybutadiene di-block or a polybutadiene-b-polystyrene di-block, as opposed to the 1,2-PBd-b-1,4-PBd-b-1,2-PBd tri-block of the prior example, can be employed. This embodiment has the advantage of easier phase separations, a reduction of conformational restrictions as compared to a tri-block, and a reduction of instances where the two ends of a tri-block end up in the same hard domain (that is, loop back into the same phase) as opposed to two different domains. In a variation of this embodiment star block copolymers can be used. Star-block copolymers refer to copolymers having three or more functional end blocks.
Selectively crosslinking the thermosettable domain blocks of the polymeric precursor is achieved by using a crosslinking agent. This may include any curative, curing agent, crosslinker, accelerator or catalyst capable of selectively causing the thermosettable domain block of the polymeric precursor to thermoset; that is, irreversibly crosslink into a hard, glassy domain. Exemplary crosslinking agents include peroxides, such as dicumyl peroxide, polystyrene hydroperoxide or 1,2-polybutadiene hydroperoxide. It should be appreciated, however, that crosslinking agents useful for selectively crosslinking a block of a given polymeric precursor will vary depending upon the particular polymeric precursor. Notably, those of ordinary skill in the art will readily be able to choose useful crosslinking agents for a chosen polymeric precursor.
Preferably, the crosslinking agent selectively solubilizes in the glassy domains. This ensures that the crosslinking takes place within the domain that creates the desired thermoset domains. Additionally, solubility of the crosslinking agent within the thermoset domain blocks helps to ensure that substantial crosslinking of the rubbery blocks of the polymeric precursor does not occur.
The crosslinking agent may be directly incorporated into the thermosettable domain blocks of the polymeric precursor such that, upon heating, the crosslinking agent will set. For example, when employing a 1,2-polybutadiene-b-1,4-polybutadiene-b-1,2-polybutadiene polymeric precursor, 1,2-polybutadiene domains are embedded in an elastomeric 1,4-polybutadiene matrix by synthesizing a tri-block that incorporates a crosslinking agent, such as a peroxide, into the 1,2-polybutadiene end blocks. Upon heating, the peroxide decomposes to crosslink and thermosetting of the 1,2-polybutadiene end blocks.
For example, a tri-block copolymer of 1,2-polybutadiene-b-1,4-polybutadiene-b-1,2-polybutadiene having a minor portion of 1,2-polybutadiene end blocks can be employed as the polymeric precursor. This tri-block is synthesized by standard anionic techniques (e.g., sequential polymerization using a difunctional initiator). The 1,2-polybutadiene and 1,4-polybutadiene blocks are thermodynamically incompatible and 1,2-polybutadiene block can be readily made into a hard thermoset by a free radical-chain reaction initiated by peroxide. The 1,4-polybutadiene block will, at most, will only lightly crosslink upon reaction with peroxide.
After crosslinking, the 1,2-polybutadiene domains become hard and glassy while the 1,4-polybutadiene remains uncrosslinked or becomes only lightly crosslinked. The reaction of the peroxide with the 1,2-polybutadiene block is much faster than that with the 1,4-polybutadiene block, and therefore the reaction end products have end blocks that are hard thermosets, while the center blocks remain rubbery. Because the peroxide reacts more readily with the 1,2-polybutadiene blocks, a gradient is believed to form between the 1,2-polybutadiene and 1,4-polybutadiene phases that causes diffusion of peroxide from the 1,4-polybutadiene phase into the 1,2-polybutadiene phase. This causes further crosslinking of the 1,2-polybutadiene blocks relative to the 1,4-polybutadiene phase. The high Tg (about 0xc2x0 C.) for 1,2-polybutadiene also favors its becoming glassy upon crosslinking. Moreover, extensive crosslinking of the 1,2-polybutadiene phase enhances the degree of phase separation between the 1,2-polybutadiene domains and the 1,4-polybutadiene matrix. The resulting structure consists of thermoset, glassy, high Tg hard domains of 1,2-polybutadiene uniformly embedded in, and covalendy linked to, a soft 1,4-polybutadiene matrix. The cured tri-block exhibits high reinforcement like an analogous SBS, but has reduced set, creep and temperature sensitivity due to the extensively crosslinked end blocks.
In another example 1,4-polyisoprene-b-1,2-polybutadiene-b-1,4-polyisoprene (IBI) is employed as the polymeric precursor. Preferably, curing is made with an accelerated sulfur vulcanization agent. As above, the center and end blocks have different rates of vulcanization, that is, they are thermodynamically separable. In this instance, the polyisoprene cures much more readily than the polybutadiene. With sufficient sulfur levels, it is possible to make a self-reinforced, thermoset rubber in which the bound hard domains are ebonite.
A homopolymer miscible with the matrix blocks of the polymeric precursor may be added to the composition before crosslinking. The miscibility of the homopolymer within the matrix blocks creates a soft phase that contains both stronger covalent bonds and weaker physical-adsorption bonds (interactions) with the hard domains subsequently formed in the end product. The matrix block/miscible homopolymer blend simulates bound carbon black filled rubber by containing bound (matrix block portion) and unbound (homopolymer portion) rubber.
For example, when a 1,2-polybutadiene-b-1,4-polybutadiene-b-1,2-polybutadiene polymeric precursor is employed, a homopolymer miscible with the center block, such as 1,4-polybutadiene monomer, may be added to the tri-block polymeric precursor. The miscibility of the 1,4-polybutadiene with the center (matrix) block of the tri-block creates a soft phase that then contains both stronger covalent and weaker physical-adsorption bonds with the hard domains. The center block/homopolymer blend simulates bound carbon black filled rubber by containing bound (at the 1,4-polybutadiene portion of the tri-block) and unbound (1,4-polybutadiene homopolymer) rubber.
It is also possible to tailor the physical properties of the rubbery composition by doing the opposite of the above procedure, i.e., adding to the polymeric precursor a homopolymer that is miscible in the thermosettable domain block or blocks. This is a useful control in optimizing physical properties of the end rubber. The addition of a homopolymer miscible in the thermoset domain block of the polymeric precursor, such as 1,2-polybutadiene in the above example, reduces the density of covalent linkages between phases. Also, the matrix/thermosettable domain interaction may be modified by adding 1,2-polybutadiene-b-1,4-polybutadiene di-block to the tri-block copolymer. Either of these two additions will have the effect of decreasing the interaction between the rubber matrix and the hard glassy thermoset domains. These additions can be adjusted to specifically control the physical properties of the end product and the domain sizes.
In yet another embodiment, a polysulfide linkage, preferably a short linkage, is introduced between the thermoset and matrix blocks of the polymeric precursor. For example a polysulfide linkage could be introduced between the 1,2-polybutadiene end blocks and the 1,4-polybutadiene center block of the 1,2-polybutadiene-b-1,4-polybutadiene-b-1,2-polybutadiene polymeric precursor, i.e., 1,2-polybutadiene-Sx-b-1,4-polybutadiene-Sx-b-1,2-polybutadiene, where x is an integer from about 1 to 10 and S is a polysulfide linkage. Here the hard and soft phases would be joined by polysulfide linkages. Thus, the same benefits realized in the bonding of silica particles to rubber with a coupling agent would be provided.
A potential problem with some polymeric precursors may be the insufficient incompatibility of the matrix block or blocks and thermoset domain block or blocks, i.e., a lack of thermodynamic incompatibility. Thus, in yet another embodiment of the present invention, a comonomer is added to promote phase separation between the matrix blocks and the thermosettable domain block or blocks of the polymeric precursor. With 1,2-PBd-b-1,4-PBd-b-1,2-PBd, styrene may be added to promote phase separation between the 1,2-polybutadiene and 1,4-polybutadiene phases. At low levels, the presence of styrene does not interfere with crosslinking of the end blocks (i.e., thermoset domain blocks). In fact, a comonomer compatible with the end blocks will promote crosslinking of the end blocks if it has an affinity for the crosslinking agent (e.g., peroxide). Conversely, a center block comonomer that inhibits crosslinking can be used. Finally, an end block compatible and a center block compatible comonomer can be used together to increase crosslinking and inhibit crosslinking respectively.
Still further, additives can be used to enhance mesophase separation or selectivity of the crosslinking agent. For example, when using a styrene-containing polymeric precursor such as SBS, SIS, SEBS (styrene-b-ethylene butylene diene-b-styrene), SNBS (styrene-b-nitrile-b-styrene), SAS (styrene-b-acrylic-b-styrene), SCS (styrene-b-chloroprene-b-styrene) or SEPS (styrene-b-ethylene propylene diene-b-styrene) tri-block copolymer, divinyl benzene (DVB), or a dimer or oligomer thereof, can be used in conjunction with a peroxide to facilitate extensive crosslinking with only the end blocks. It is believed that the DVB swells the polystyrene upon heating.
In general, a process for producing polymeric compositions according to the present invention proceeds through the following steps. First, the polymeric precursor is synthesized by standard techniques generally known in the art for producing di-block, tri-block, and star-block polymers, having thermodynamically incompatible blocks. The polymeric precursor is then masticated with a properly selected crosslinking agents that will react with the thermosettable domain blocks of the polymeric precursor to form the thermoset domains. The crosslinking agent should either not react with or should only insubstantially react with the matrix blocks of the polymeric precursor such that substantial crosslinking of the matrix blocks does not occur. If other additives, such as, for example, miscible homopolymers or copolymers are used, they are added before or during mastication of the crosslinking agent with the polymeric precursor.
As disclosed hereinabove, the polymeric precursors may be synthesized with polysulfide linages. Additionally, miscible homopolymers or di-block copolymers and/or additives, such as commoners, for promoting phase separation of the polymeric precursor may be added to the polymeric precursors before crosslinking.

Self-reinforced rubber matrix having high glass transition temperature thermoset domains


A method is described for reducing atmospheric or global warming resulting from the presence of heat-trapping gases in the atmosphere, i.e., from the greenhouse effect. Such gases are relatively transparent to sunshine, but absorb strongly the long-wavelength infrared radiation released by the earth. The method incudes the step of seeding the layer of heat-trapping gases in the atmosphere with particles of materials characterized by wavelength-dependent emissivity. Such materials include Welsbach materials and the oxides of metals which have high emissivity (and thus low reflectivities) in the visible and 8-12 micron infrared wavelength regions.

This invention relates to a method for the reduction of global warming resulting from the greenhouse effect, and in particular to a method which involves the seeding of the earth's stratosphere with Welsbach-like materials.
Global warming has been a great concern of many environmental scientists. Scientists believe that the greenhouse effect is responsible for global warming. Greatly increased amounts of heat-trapping gases have been generated since the Industrial Revolution. These gases, such as CO.sub.2, CFC, and methane, accumulate in the atmosphere and allow sunlight to stream in freely but block heat from escaping (greenhouse effect). These gases are relatively transparent to sunshine but absorb strongly the long-wavelength infrared radiation released by the earth.
Most current approaches to reduce global warming are to restrict the release of various greenhouse gases, such as CO.sub.2, CFC, and methane. These imply the need to establish new regulations and the need to monitor various gases and to enforce the regulations.
One proposed solution to the problem of global warming involves the seeding of the atmosphere with metallic particles. One technique proposed to seed the metallic particles was to add the tiny particles to the fuel of jet airliners, so that the particles would be emitted from the jet engine exhaust while the airliner was at its cruising altitude. While this method would increase the reflection of visible light incident from space, the metallic particles would trap the long wavelength blackbody radiation released from the earth. This could result in net increase in global warming.
It is therefore an object of the present invention to provide a method for reduction of global warming due to the greenhouse effect which permits heat to escape through the atmosphere.

Stratospheric Welsbach seeding for reduction of global warming


This invention relates to preparation of a rubber composition by pre-mixing at least one rubber compounding ingredient with an organic solvent solution of at least one elastomer. The invention also contemplates the use of such rubber composition, or blend of such rubber composition with at least one additional elastomer and/or rubber compounding ingredient, as a component of an article of manufacture. Such article of manufacture may be, for example, a tire. Such article may also be an industrial product such as, for example, a hose or belt such as a conveyor belt or power transmission belt.

This invention relates to preparation of a rubber composition by pre-mixing at least rubber compounding ingredient with an organic solvent solution of at least one elastomer. The invention also contemplates the use of such rubber composition, or a blend of such rubber composition with additional elastomer(s) and/or rubber compounding ingredients, as a component of an article of manufacture. Such article of manufacture may be, for example, a tire. Such article may also be an industrial product such as, for example, a hose or belt such as a conveyor belt or power transmission belt.
Various rubber compounding ingredients, including particulate carbon black reinforcement, is conventionally blended with various elastomers with the aid of various internal mixers, as well as open roll mixers, under high sheer and relative high temperature conditions. Accordingly a considerable amount stress is experienced by the rubber composition as well as expenditure of energy to accomplish the aforesaid mixing.
Alternatively, various rubber compositions have heretofore been prepared by:
(1) first masterbatching various rubber latices with various rubber compounding ingredients which have particularly included rubber reinforcing carbon black under low shear and temperatures followed by
(2) blending the masterbatch with additional elastomer(s) and compounding ingredients under high shear and temperature conditions.
For example, see U.S. Pat. Nos. 3,294,733; 3,298,984; 3,317,458; 3,345,324; 3,491,052; 3,767,605 and 3,923,707.
U.S. Pat. No. 3,317,458, for example, relates to masterbatching a combination of carbon black and silica with a rubber latex.
Various rubber compositions have also heretofore been prepared by mixing an aqueous slurry of carbon black with an organic solvent solution of elastomer(s). For example see U.S. Pat. No. 3,350,342.
U.S. Pat. No. 3,304,281, for example, relates to mixing together a solution of one polymer with a latex of another polymer and then coagulating the rubber crumb from the resulting mixture. the process can be used to incorporate an oil and/or carbon black into the polymer. For example, the oil can be introduced as an aqueous emulsion and the oil emulsion mixed with the latex prior to contact with the solution. Alternatively, all three components can be mixed simultaneously. Alternatively, a carbon black aqueous slurry can be added to the solution-latex mixture or it can be mixed with the latex prior to mixing with the solution.
U.S. Pat. No. 3,491,052 for example, relates to mixing an elastomer in an aqueous latex form with a solution of an elastomer which has been dissolved in a water immiscible organic solvent to form a pseudo-emulsion and recovering the mixed elastomers by adding a latex coagulating agent at a temperature sufficient to vaporize the solvent. Alternatively a rubber pigment (e.g.: carbon black) may be dispersed in the pseudo-emulsion prior to coagulation.
U.S. Pat. No. 3,533,988, for example, relates to blending a hydrocarbon solution of rubber with an aqueous suspension of a rubber reinforcing agent, such as carbon black. In its background discussion, it relates that, theretofore, in order to avoid a disagreeableness of handling dry, dusty carbon black with raw rubber on mixing rolls, a method was developed for producing masterbatch by dispersing carbon black directly into a rubber solution produced by monomer polymerization in the presence of a solvent. It further relates that, theretofore, another method was to disperse carbon black in a hydrocarbon and mix the dispersion with the rubber solution.
In the description of this invention, the term xe2x80x9cphrxe2x80x9d relates to parts by weight of an ingredient per 100 parts by weight of rubber.
The terms xe2x80x9crubberxe2x80x9d and xe2x80x9celastomerxe2x80x9d are used interchangeably unless otherwise specified.
The term xe2x80x9cTgxe2x80x9d relates to a glass transition temperature of an elastomer, normally determined by a differential scanning (DSC) calorimeter with a temperature rise of 10xc2x0 C. per minute.
In accordance with this invention, a process of preparing a rubber composition is provided which comprises:
(A) blending a particulate elastomer-reinforcing filler with an organic solvent solution of a conjugated diene-based elastomer solution and recovering a composition thereof by removing said solvent therefrom wherein said filler is blended therewith in a form of:
(1) particulate elastomer-reinforcing filler exclusive of aqueous or organic dispersion of said filler; and/or
(2) particulate elastomer-reinforcing filler as a dispersion thereof in an organic solvent, or
(B) spraying an organic solvent solution of a conjugated diene-based elastomer solution onto a particulate elastomer-reinforcing filler and recovering a composition thereof by removing said solvent.
In practice, various rubber compounding ingredients may be included with said filler in either of the above said blending process and/or said spraying process.
In practice, said solvent solution of said elastomer may be a polymerizate.
In further accordance with this invention, said particulate filler is comprised of at least one of carbon black, silica, particularly amorphous silica including precipitated silica and/or fumed silica, carbon black and modified carbon black having silanol groups on the surface thereof.
In additional accordance with this invention, a preferred carbon black and silica have a relatively low apparent density prior to said blending in a range of about 3 to about 300, alternatively about 3 to about 140 g/l. This low density is substantially lower than conventional carbon blacks and silicas which more conventionally have an apparent density in a range of about 500 to about 1000 g/l.
Exemplary of more conventional silicas are precipitated silicas and exemplary of conventional carbon blacks are those in which the carbon black powder has been processed to form very small pellets and which have designations such as, for example, N234, N121, N330, etc which are ASTM designations.
Exemplary of silicas and carbon blacks with the said low apparent densities are, for example, fumed silicas and fine carbon black powers prior to their pelletization to form the said N234, N122 and N330 (for example) designated carbon blacks. Such fine carbon black powders are not normally used for rubber reinforcement purposes, although carbon blacks in the aforesaid pelletized form, with attendant higher apparent densities, are conventionally used for rubber reinforcement purposes.
A significant aspect of using the silica and carbon black powder with very low apparent densities for this invention is to utilize the high absorption capacities of such fillers, particularly where it is desired for the filler to have a greater ability to absorb various ingredients onto its surface and to thereby ultimately provide a resulting free flowing rubber composition.
As previously presented, the process of this invention may involve spraying said organic solvent solution comprised of at least one diene-based elastomer onto said particulate filler.
As a feature of said spraying process, said particulate filler is preferably agitated during said spraying of said solvent solution onto said filler.
As an additional feature of said spraying process, the solvent solution of said elastomer(s) is substantially dried upon said particulate filler as it is being agitated.
In additional accordance with this invention, said suspension, or dispersion, of said filler and said solvent solution of elastomer(s) is heat treated by heating the mixture, while agitating the mixture, to a temperature within a range of about 30xc2x0 C. to about 150xc2x0 C., alternatively about 40xc2x0 C. to about 150xc2x0 C., for about 2 to about 30, alternatively about 3 to about 20, minutes prior to drying the said composite. It is to be appreciated that the mixture may need to be contained under pressure in a suitable container or under reflux conditions where evaporating solvent is returned to the solution during the heat treatment operation.
In further accordance with this invention, the silica is an amorphous silica which is pre-treated, prior blending with said organic solvent solution of elastomer(s), by reacting said silica, preferably a precipitated silica, with an organosilane of the general formula (I):
(OR)3xe2x80x94Sixe2x80x94Rxe2x80x2xe2x80x94Snxe2x80x94Rxe2x80x2xe2x80x94Sixe2x80x94(OR)3xe2x80x83xe2x80x83(I)
wherein R is the same or different alkyl radical selected from at least one of ethyl and methyl radicals, preferably the same radicals and preferably an ethyl radical; Rxe2x80x2 is the same or different radical selected from at least one of ethyl, propyl and butyl radicals, preferably the same radical and preferably a propyl radical; and n is a value from 2 to 6 with an average of from 2 to 2.6 or from 3.5 to 4.
Thus, such organosilane may be a bis(3-alkoxysilylalkyl) polysulfide with an average of from 2 to 2.6 or from 3.5 to 4 connecting sulfur atoms in its polysulfidic bridge. Representative thereof is a bis (3-ethoxysilyipropyl) polysulfide.
In one aspect of the invention, said organic solvent solution of elastomer(s) may be composed of at a multiplicity of least two individual organic solvent solutions of elastomers
(i) which are pre-blended prior to addition of said filler(s) or
(ii) which at least one of said of elastomer solutions is blended with at least one additional organic solvent elastomer solution subsequent to said filler addition thereto or
(iii) which at least one of said elastomer solutions is blended with at least one additional organic solvent elastomer solution substantially simultaneously with said filler addition.
In one aspect of the invention, the said organic solvent solution of at least one elastomer may be a polymerizate (an elastomer together with its solvent in which it has been prepared by polymerization reaction of an appropriate monomer in the presence of a catalyst- which is sometimes referred to as a cement).
In practice, said polymerizate may be polymerizate in which the polymerization reaction has not been terminated and which may be referred to as a living polymetizate. In such case, it is envisioned that, as the polymerization continues, the polymer may interact with the filler to create an improved, or more efficient and integral dispersion of the filler within the elastomer host.
For process step (B) of this invention, in addition to the said addition of said particulate filler in step (A), at least one additional rubber compounding ingredient is blended with said organic solvent solution of said elastomer(s), which may be. before, substantially simultaneously with, or subsequent to, said filler addition, which is comprised of at least one of:
(a) microcrystalline waxes in a range of about 0.1 to about 10 phr;
(b) antioxidant(s) selected from amine-based and phenolic-based antioxidants in a range of about 0.1 to about 10 phr;
(c) sulfur vulcanization accelerator(s) in a range of about 0.1 to about 10 phr;
(d) sulfur vulcanization retarder(s) in a range of about 0.01 to about 5 phr;
(e) sulfur vulcanization activator(s) in a range of about 0.1 to about 10 phr;
(f) rubber processing oil(s) selected from at least one of aromatic, paraffinic and naphthenic rubber processing oils in a range of about 1 to about 60 phr; and
(g) sulfur in an amount of about 0.1 to about 3 phr.
Microcrystalline waxes are well known waxes for use in rubber compositions. Such waxes are defined by xe2x80x9cThe Condensed Chemical Dictionary, Ninth Edition (1970), Page 925 as xe2x80x9cA wax, usually branched-chain paraffins, characterized by a crystal structure much small than that of normal wax and also by much higher viscosityxe2x80x9d.
Representative of commercial microcrystalline waxes are, for example, those available as Akrowax from the Akrochem Company; as an Antilux series of waxes from the Rein Chemie Company; as xe2x80x9cBe-Squarexe2x80x9d 175 Amber Wax from the Petrolite Company; as Beesyn White Wax from the International Wax Company; and as an Okerin series of waxes from the Astor-Wax Company.
Representative examples of antioxidants are amine-based and phenolic based antidegradants. Representative of various commercially available antidegradants may be found, for example in the xe2x80x9c1997 Blue Bookxe2x80x9d published by Rubber World, a Lippincott and Peto Publication, Pages 132 through 168, which is intended to incorporated herein by reference.
Representative of such commercially available antidegradants are, for example, diphenyl-p-phenylene-diamine as AgeRite DPPD from the R.T. Vanderbilt Company and octylated diphenyl amines such as AgeRite Statlite from the R.T. Vanderbilt Company.
Additional antidegradants are for example, 2,5-D-t-dibutylhydreoquinone, N-1,3-dimethylbutyl-Nxe2x80x2-phenyl-p-phenylenediamine, polymerized 1,2-dihydro-2,2,4-trimethylquinoline, diaryl-p-phenylene diamine, 4,4xe2x80x2-methyhlene bis 2.6 di tert butylphenol, N,Nxe2x80x2-di-3(5-methyl heptyl)-p-phenylenediamine, 2,2-methylene-bis(4-methyl-6-t-butyl phenol), 4,4xe2x80x2-dicumyldiphenylamine, and N-cyclohexylthiophthal imide.
Representative examples of various sulfur vulcanization accelerators are those found in xe2x80x9cThe Vanderbilt Rubber Handbookxe2x80x9d (1978), pages 354-383 and in the xe2x80x9c1977 Blue Bookxe2x80x9d, infra, Pages 17 through 74, which are intended to be incorporated herein by reference.
Representative of commercial sulfur vulcanization accelerators are, for example dibenzothiazyl disulfide as Altex from the Elastochem Company; 2-mercaptobenaothiazole as Captax from the Elastochem Company; N-oxydiethylene benzothiazole-2-sulfenamide as Amax from the R.T. Vanderbilt Company; 4-morpholinyl-2-benzothiazole disulfide as Morfax from the R.T. Vanderbilt Company; tetramethylthiuram disulfide as Methyl Tuads from the Elastochem Company; and tetramethylthiuram monosulfide as Unads from the Elastochem Company. Additional vulcanization accelerators are, for example, tetrabutylthiuram disulfide, zinc dibutyldithiocarbamate, thiocarbqamuyl sulfenamide, N-cyclohexyl-2-benzothiazolesulfenamide, N-t-butyl-2-benzothiazole sulfenamide, and diphenylguanidine.
Representative examples of various vulcanization retarders are those found in xe2x80x9cThe Vanderbilt Rubber Handbookxe2x80x9d (1978), infra, Page 403 and in the xe2x80x9c1977 Blue Bookxe2x80x9d, infra, Pages 98 through 102, which are intended to be incorporated herein by reference.
Representative of commercial vulcanization retarders is, for example, N-nitrosodiphenylamine from the Sovereign Chemical Company as well as N-cyclohexyl thiophthalimide, magnesium oxide, and N-(cyclohexylthio)-phthalimide.
Representative examples of various vulcanization activators are those found in the xe2x80x9c1977 Blue Bookxe2x80x9d, infra, Pages 75 through 97, which are intended to be incorporated herein by reference.
Representative of commercial vulcanization activators are, for example, zinc oxide from the Akrochem Company and stearic acid-rubber grade from the Akrochem Company.
Representative examples of various plasticizers and softeners are those found in the xe2x80x9c1977 Blue Bookxe2x80x9d, infra, Pages 179 through 216, which are intended to be incorporated herein by reference.
Representative examples of various vulcanizers are those found in the xe2x80x9c1977 Blue Bookxe2x80x9d, infra, Pages 102 through 128, which are intended to be incorporated herein by reference.
Representative of commercial vulcanizers is, for example, sulfur in its different forms as alphasulfur (S8) and/or as insoluble sulfur with or without treatment from the Akrochem Company.
In additional accordance with the process of this invention, particularly where said additional compounding ingredients added to the elastomer solution include zinc oxide, stearic acid, and sulfur, process step (C) is provided which comprises sulfur vulcanizing said recovered rubber composite at a temperature in a range of about 150xc2x0 C. to about 180xc2x0 C.
In further accordance with the process of this invention, the resultant rubber composition is blended with at least one additional diene-based elastomer and/or compounding ingredient then sulfur vulcanized.
In additional accordance with the process of this invention, an article of manufacture is prepared having at least one component of the rubber composition of this invention or as blend with at least one additional elastomer and/or compounding ingredient.
In practice, the article of manufacture of this invention may be, for example, a tire or an industrial product such as, for example a hose or belt such as, for example a conveyor belt or power transmission belt.
In additional accordance with this invention a tire is provided having a component of the rubber composition prepared according with this invention.
In additional accordance with this invention a tire is provided having a tread of the rubber composition prepared according with this invention.
It is a significant aspect of this invention that the diene-based elastomer(s) together with one or more of zinc oxide, sulfur, vulcanization accelerator(s) and reinforcing filler may be all mixed together under controlled shear and controlled temperature conditions without being limited by the conventional high shear mixing accompanied by largely uncontrollable, autogenous, temperature increase as experienced in classical internal rubber mixers. This aspect is considered herein as being novel and significant because
(1) the polymer.in an organic solvent solution is at a very high, and possibly its highest possible, dispersion state; and
(2) various additional compounding ingredients, including particulate reinforcing fillers, particularly said carbon black powder and fumed silica with their aforesaid low apparent densities are also at a very high, and perhaps their highest, dispersion state, namely, as a solution, or dispersion, thereof in an organic solvent.
Particular benefits of the process of this invention are considered herein to be:
(1) A relative minimal amount of additional energy is needed for polymer drying in a case where the polymer is adsorbed onto the filler or the polymer is mixed with the filler.
(2) No additional energy or process step is needed for pelletization of carbon black fillers prior to mixing with the elastomer, namely pellets for carbon black, and granules or small spheres for precipitated silica, especially where the aforesaid carbon black powers, as well as fumed silica, with their low apparent densities are used.
(3) The use of fumed silicas with very low apparent density (ASTM-D1513) may be enabled because such silicas may absorb the solvent and/or elastomer cement solution, thereby transforming the highly dusting silica (due to the silica""s low apparent density) to a compacted and more usable material.
(4) Concerns about flaking or pearling of various ingredients to be mixed with the elastomer should be minimized because the ingredients will be dissolved, or dispersed, in the organic solvent and therefore there is no need for a specific physical dry mixing of the utilized ingredients.
(5) Only a relative minimal energy would normally be necessary for dispersing various compounding ingredients in the elastomer because the mixing of specified ingredients will be reduced to a blending of solutions.
(6) An increased uniformity of dispersion of various compounding ingredients, including particulate reinforcing fillers, particularly where such fillers may be hydrophobic in nature, in the elastomer because such materials, as a solution or dispersion in the organic solvent, will be in their most dispersible state and because the blending/mixing in solution has the highest dispersion/blending and homogenizing capability as compared to dry blending the ingredients.
(7) A reduction in amounts of various compounding ingredients needed for the rubber composition formulation is expected because of better anticipated dispersion of a respective compounding ingredients within the elastomer due to solution blending as compared to dry blending of the ingredients.
(8) Better resistance to abrasion is expected for the resulting vulcanized rubber composition which contains particulate amorphous silica for its reinforcement and which has been blended with the elastomer by organic solution mixing.
(9) Better control of various chemical reactions which typically occur during the mixing of various ingredients is expected where organic solution mixing of the associated ingredients is utilized as compared to simple dry mixing of the ingredients under high sheer and elevated temperature mixing in an internal rubber mixer.
As hereinbefore discussed, in further practice of the invention, said diene-based elastomer may be provided in a form of a polymerizate cement of such elastomer.
Indeed, a preferable process according to this invention is the utilization of a polymerizate cement of the elastomer instead of re-dissolving the elastomer in a volatile organic solvent.
In additional practice of this invention, the rubber composition prepared by the process of steps (A), (C) and optionally (B) may be in a form of a pre-formed rubber composition, or composite, which is subsequently mixed under high shear and temperature conditions with at least one additional compounding ingredient comprised of at least one of
(1) additional diene-based elastomer(s);
(2) zinc oxide;
(3) sulfur;
(4) vulcanization accelerator(s);
(5) microcrystalline waxes;
(6) antidegradants; and
(7) particulate reinforcing filler(s).
In practice, it may be preferable for a particulate reinforcing filler to be mixed with the elastomer solution, including fillers such as, for example fumed silicas and carbon blacks, to have relatively small apparent densities (ASTM method D-1513) within a range of about 10 g/l to about 300 g/l.
The preference toward relatively small apparent densities for the reinforcing filler(s) is for the fillers to more homogeneously disperse within the organic solvent solution and, ultimately, to disperse more homogeneously within the elastomer within the elastomer itself.
A preference herein toward use of relatively low apparent densities for the reinforcing fillers is to utilize the high absorption capacities of such fillers, particularly where it is desired for the filler to have a greater ability to absorb various ingredients onto its surface and to thereby ultimately provide a resulting free flowing rubber composition. For example, the concentration of such filler in the organic solvent solution may be adjusted so that the solvent may be more readily absorbed by the filler thereby generating a dry composite with acceptable handling properties, namely, as a free flowing granular composite or compacted, for example, to form bales thereof.
In practice, it is often desired that the reinforcing filler is carbon black. While the various conventional, pelletized rubber reinforcing carbon blacks might be used, it is, as hereinbefore discussed, preferred to use an unpelletized carbon black powder having a relatively low apparent density (ASTM method D-1513) before mixing with the elastomer in a range of about 3 to about 140, alternately about 3 to about 300, g/l. Representative of conventional pelletized carbon blacks having higher apparent densities, as hereinbefore discussed, for example, the various N-series of carbon blacks referenced in xe2x80x9cThe Vanderbilt Rubber Handbookxe2x80x9d, 13th Edition, 1990, Page 417. It is to be appreciated that desirable carbon black powders for use in this invention are carbon black powders prior to pelletization to form said conventional pelletized carbon blacks.
In practice, it may be desired to use fumed silica with its aforesaid low apparent density.
However, it may sometimes desired to use silicas with the aforesaid higher apparent density such as for example precipitated aluminosilicates, may be used it may sometimes be preferred to use a silica having a relatively high apparent density (ASTM method D-1513) in a range, for example, of about 500 g/l to about 1000 g/l for mixing with the elastomer solution as hereinbefore discussed. Representative of contemplated precipitated silicas are, for example, RP120HD, RP85, Z85MP, Z1165MP, RP240HD and RP200MP from Rhodia; VN2, VN3, and Vetrasil 7000 from Degussa A.G.; Hi-sil 532 from PPG Industries; Zeopol 8745 and 8755 from Huber; Perkasil 233 from Akzo.
In the practice of the invention, various sulfur vulcanizable elastomers may be used, exemplary of which are homopolymers and copolymers of conjugated diene hydrocarbons and copolymers of at least one conjugated diene hydrocarbon with an aromatic vinyl compound selected from styrene and alphamethyl styrene.
Preferred conjugated dienes are isoprene and 1,3-butadiene. Preferred aromatic vinyl compound is styrene.
Representative of various conjugated diene-based elastomers are, for example, cis 1,4-polyisoprene, 1,3-butadiene, styrene/butadiene copolymers, isoprene/ butadiene copolymers, styrene/isoprene/butadiene copolymers and any functionalized versions of them.
Preferably, such conjugated diene-based elastomers are prepared by solvent solution polymerization. In such case, such elastomers may be preferably used in their polymerizate form as hereinbefore discussed, namely in the organic solvent solution in their monomers are polymerized to form the elastomer, so that the elastomers do not have to be re-dissolved in a volatile organic solvent.
Various organic solvents may be used for process step of this invention. Representative of such solvents are, for example, hexane, benzene, toluene, cyclohexane, heptane, and tetrahydrofuran. Preferred solvents are, for example, hexane, cyclohexane and heptane.
The rubber composition prepared by the process of this invention is considered herein as being useful, or advantageous, in the preparation of rubber composition as a component of an article of manufacture, instead of dry-blending, or in combination with dry blending, rubber compounding ingredients with rubber because the expected improved dispersion of dispersed ingredients within the elastomer, including reinforcing fillers, expected improved uniformity of dispersion of respective ingredients within the elastomer; improved energy balance because the typical very high energy needed to dry mixing the ingredients in an internal rubber mixer is replaced by a low energy organic solvent mixing process; more efficient use of respective compounding ingredients within the elastomer, including a reduction of quantity; improved efficiency of mixing ingredients within an elastomer ant therefore improved overall manufacturing efficiency.
As hereinbefore discussed, rubber compositions for this invention may also be prepared by mixing the rubber composition, or composite, prepared by processes (A), (C) and optionally (B) with various sulfur vulcanizable elastomers and/or additional rubber compounding ingredients by compounding by methods generally known in the rubber compounding art, such as mixing in an internal rubber mixer with various commonly used additive materials such as, for example, curing aids, such as sulfur, activators, retarders and accelerators, processing additives, such as oils, resins including tackifying resins, silicas, and plasticizers, fillers, pigments, fatty acid, zinc oxide, waxes, antioxidants and antiozonants, peptizing agents and reinforcing materials such as, for example, carbon black. As known to those skilled in the art, depending on the intended use of the sulfur vulcanizable and sulfur vulcanized material (rubbers), the additives mentioned above are selected and commonly used in conventional amounts.
Typical amounts of tackifier resins, if used, may comprise about 0.5 to about 10 phr, usually about 1 to about 5 phr. Typical amounts of processing aids may comprise 1 to 10 phr, if used. Such processing aids can include, for example, aromatic, naphthenic, and/or paraffinic processing oils. Representative silicas may be, for example, hydrated amorphous silicas. Typical amounts of antioxidants comprise about 1 to about 3 phr. Representative antioxidants may be, for example, diphenyl-p-phenylenediamine and others, such as, for example, those disclosed in The Vanderbilt Rubber Handbook (1978), Pages 344 through 346. Typical amounts of antiozonants for the sidewall composition may comprise about 3 to about 6 phr. Typical amounts of fatty acids, if used, which can include stearic acid comprise about 0.5 to about 3 phr. Typical amounts of zinc oxide comprise about 2 to about 6 phr. Typical amounts of waxes comprise about 1 to about 5 phr. Often microcrystalline waxes are used. Typical amounts of peptizers comprise about 0.1 to about 1 phr. Typical peptizers may be, for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide.
The presence and relative amounts of the above additives are considered to be not an aspect of the present invention which is more primarily directed to the masterbatch preparation, in an organic solvent solution, of a pre-formed composite and the further preparation and use of rubber compositions which contain such pre-formed composite.
The vulcanization is conducted in the presence of a sulfur vulcanizing agent. Examples of suitable sulfur vulcanizing agents include elemental sulfur (free sulfur) or sulfur donating vulcanizing agents, for example, an amine disulfide, polymeric polysulfide or sulfur olefin adducts. Preferably, the sulfur vulcanizing agent is elemental sulfur. As known to those skilled in the art, sulfur vulcanizing agents are used in an amount ranging from about 0.5 to about 4 phr, with a range of from about 0.5 to about 2.25 being preferred.
Accelerators, including primary and optionally secondary accelerators, are used to control the time and/or temperature required for vulcanization and to improve the properties of the vulcanizate. Often accelerators are used in an amount ranging from about 0.5 to about 2.0 phr. Such accelerators may be, for example, various amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates. Preferably, the primary accelerator is a sulfenamide. If a second accelerator is used, the secondary accelerator is preferably a guanidine, dithiocarbamate or thiuram compound.
Sometimes a combination of antioxidants, antiozonants and waxes may be collectively referred to as xe2x80x9cantidegradantsxe2x80x9d.
The presence and relative amounts of the respective compounding ingredients are riot necessarily considered to be an aspect of this invention, except where noted, and except that a practice of this invention is expect to result in a more efficient use of some of the ingredients, as hereinbefore discussed, which may result, in some cases, in a reduction on amounts of use of some ingredients.
A tire can be built, shaped, molded and cured by various methods, which will be readily apparent to those having skill in such art.
The prepared tire of this invention is conventionally shaped and cured by methods known to those having skill in such art.

Preparation of rubber composition by organic solution mixing and articles thereof including tires


A method and apparatus for capturing annotations about database material in a way that allows queries with conditions or predicates on both the database material and the annotations. Database material may be text, computer programs, graphics, audio, spreadsheets, or any other material which may be stored and indexed. Database material may be in one or multiple sources, and annotations may be stored together with the original material or in a separate store. Annotations can be used to capture information such as additional facts about the database material, the opinions and judgments of experts about the database material, and/or links to other related material. Annotations may be captured in a structured form to enhance queryability and semantic interpretation.

The present invention relates to the field of data entry and retrieval. Specifically, the present invention relates to a method and system having the capability to organize an annotation structure and to query both data and annotations in computer systems. More particularly, the present invention enables the annotation of stored information, and permits the capture, sharing, and querying of data and annotations.
Successful planning and decision making in many technical and other industries depends on the expeditious and correct interpretation of complex information. For example, in the drug industry the data may have origins as diverse as high throughput screening experiments, clinical trials, patent information and research journals. In the petroleum industry the data may span seismic measurements, aerial surveys, laboratory data and economic forecasts. A system capable of providing unified access to disparate data sources and applications reduces the time spent finding, accessing, preparing, transforming and reformatting data, and allows professionals to focus on the interpretation and extraction of knowledge for planning and decision making.
However, one complication with providing this type of unified access is that the data inevitably spans several disciplines, with an attendant probability of misinterpretation. Extensive knowledge of multiple domains is required if misuse is to be avoided.
Therefore, there is still an unsatisfied need for an information management system that clarifies the generation, use, and purpose of the data. The information management system can capture knowledge about the genesis and history of the data, how analyses are done, how decisions are made, and what the outcomes are. This xe2x80x9ccorporate memoryxe2x80x9d forms the basis for the analysis required to make better technical and business decisions.
Several attempts have been made to access information based on annotations. Illustrative attempts are described in the following references:
U.S. Pat. No. 5,404,295 to Katz et al.
U.S. Pat. No. 5,600,775 to King et al.
U.S. Pat. No. 5,832,474 to Lopresti et al.
U.S. Pat. No. 5,548,739 to Yung.
For example, U.S. Pat. No. 5,404,295 describes a method and apparatus for computer retrieval of database material. Annotations are provided for selected database subdivisions and are converted to a structured form and stored in that form along with connections to corresponding subdivisions. Searching for relevant subdivisions involves entering a query in natural language or structured form, converting natural language queries to structured form, matching the structured form query against stored annotations, and retrieving database subdivisions connected to matched annotations.
However, the teaching of this patent is limited to a system with the capability to search the annotations to locate the database material. The system does not have the capability to search the stored information based on both the annotations and database material, or to search on database material to retrieve the annotations. As a result, the system is not suitable for directly locating a subset of data where the filter has predicates on both the annotations and database material. Rather, it will locate all database material that corresponds to the annotation predicates and it would require a second step to filter this subdivision and to apply the data predicates.
The present invention contemplates a method and apparatus for capturing annotations about database material in a way that allows queries with conditions or predicates on both the database material and the annotations. Database material may be text, graphics, spreadsheets, relational tables or any other material which may be stored and indexed. An annotatable data item (i.e. the subsection of database material that can be annotated) is any entity referenced by an index (e.g. by an object identifier) or any attribute or subcomponent of such an entity, or any arbitrary set of such items. Examples include a table such as a relational table or spreadsheet, a view such as a relational view, a row within a table, a cell within a table (i.e. the intersection of a column and a row), a column within a table, an object, an attribute of an object, a set of rows or columns from one table, or a set of rows from different tables. The annotatable data items may be in a single source or multiple sources, or span such sources. Multiple annotations may be entered for a single annotatable data item.
The annotations, together with the pointer information that relates them to the original database material, may be stored in a separate source so that the data model and operation of the sources containing the original database material is not affected. It is the pointer information that allows formulation of the queries to retrieve either annotations related to specific database material or database material related to specific annotations.
Annotations may be used to capture information such as additional facts about the database material, the opinions and judgments of experts about the database material, and/or links to other related material. Annotations may be entered manually or automatically by an application. Henceforth, the person or application that enters an annotation will be referred to as an annotation author, and the person or application that retrieves annotation and/or database material will be referred to as the reader.
Annotations may be captured in structured form to enhance queryability and semantic interpretation as well as to provide some order for users to enter this additional information content. The entry of comments in an unorganized and undisciplined way can often lead to more data with little useful content. The structure is comprised of labeled categories, to aid semantic interpretation. The annotation structure could be as simple as a xe2x80x9cheaderxe2x80x9d category containing attributes (or fields) about whom and when the person or application wrote the annotation, together with a xe2x80x9cbusiness meaningxe2x80x9d category containing a single xe2x80x9cCommentxe2x80x9d field for a textual description of the data item being annotated. In this example, the title of the latter category, xe2x80x9cbusiness meaningxe2x80x9d can aid in the interpretation of the xe2x80x9cCommentxe2x80x9d field. An annotation structure may be more complicated than the one illustrated above and contain many categories, each of which contains a number of attributes. Some or all of these attributes may have constraints placed on their values. For example, the constraints may be on the datatype (e.g. numeric, character) and/or on their values, so that users have to enter values consistent with a particular datatype or consistent with an input list or pick-list. The constraints enforce more structure and consistency in the annotation content and also enhance the queryability with today""s query engines.
It is the capture and query of information from experts represents one important feature of the present invention. To this end, the present method offers the capability to allow standardized structure of annotations based on the xe2x80x9cgroupxe2x80x9d to which the author and reader belong, as well as on the data item being annotated. A group can be as small as one person, in which case there can be a personalized annotation structure, or it can contain a xe2x80x9crelatedxe2x80x9d set of people, such as people of a particular discipline or performing a particular role. Henceforth, group will be referred to as a xe2x80x9ccontextxe2x80x9d. There is a context associated with the annotation author as well as the reader. Thus, it is permitted for the structure for the entry of an annotation about any one data item to be different depending on the context of the author, and for this information to be presented differently on retrieval depending on the context of the reader. These structures that are associated with contexts, can be used to give a level of credibility to the annotations. That is, the annotation structure may be set up such that only experts in a given discipline (context) can enter information or advice pertaining to the expertise understood by that discipline. Filtering and transforming the entered annotation content based on the context of the reader can be used to retrieve only relevant information, or to xe2x80x9chidexe2x80x9d information to which this reader context is unauthorised, or to present the information in a form easily understood by the discipline or role of the reader. Multiple annotations from authors with different contexts or within the same context can be attached to a single annotatable data item.
It should be understood that the foregoing capabilities encompass a single annotation structure containing an attribute such as xe2x80x9cCommentxe2x80x9d or xe2x80x9cURLxe2x80x9d for every annotatable data item, wherein annotations of this type are entered and retrieved in the same way by all author/readers.
The method of the present invention is outlined as follows:
The type of annotatable data item is identified and the allowed structures for this type are registered. A type may include, but is not limited to, xe2x80x9cset of rows of table xxe2x80x9d or xe2x80x9cany cell in column y of spreadsheet zxe2x80x9d. This registration step can be done as a preprocessing step or may be done immediately before annotation entry.
For annotation entry, an annotatable data item is chosen (e.g. a 5th cell in column y of spreadsheet z) and an annotation is entered and stored. The annotation is associated with the annotatable data item at the time of entry by including pointer information to the annotatable data item with the annotation. Optionally, the annotation may be xe2x80x9cpropagatedxe2x80x9d or automatically associated with additional annotatable data items using extra information defined in the registration step. Once annotations have been stored, queries may be issued to retrieve both the annotation content and/or the database material.
There are a number of query modes possible. In the first mode, the reader may browse the annotations in the context of the database material. That is, the reader identifies the specific database material of interest and all accompanying annotations are retrieved. This is achieved by issuing a query using the pointer information stored with the annotations. This mode is useful when the reader is perusing database material and wants to read annotations that contain related information or links to related information.
A second mode refers to querying for particular annotations in the context of the data. That is, the reader first identifies the database material of interest. This may include identifying an annotatable data item or a type of annotatable data item. In the case of an annotatable data item, the reader asks for the accompanying annotations with particular characteristics, (e.g. where the author field contains Smith). In the case of a type, the reader may ask for elements of the type whose annotations have particular characteristics. A query is issued that uses the pointer information and specifies a filter on the annotation content.
The reader may alternatively ask for only the elements of the type and their annotations where the elements of the type and their annotations both have filters on their content. In this case, a query is issued that uses the pointer information and specifies a filter on the annotation content and also a filter on the data content.
The second mode is useful when the reader wishes to review only certain annotations that relate to the data (e.g. all those by expert X) or when the reader wishes to focus on particular database material and annotation content (e.g. find all the data and annotations about drug molecules that have biological activity greater than x (data content) and for which the experts said the experimental measurement was reliable (annotation content)).
The third mode involves querying across the full body of annotations, regardless of the database material being annotated. This may be used, for example, for locating all annotations containing a particular category or for locating annotations containing particular content. For example, an exemplary query can be: How many times has Simulation package x been used to generate production estimates?
The fourth mode involves querying for particular data in the context of the annotations, is an extension of the third mode. In this case, the query retrieves not only the annotations of interest but also the database material that they annotate. For example, in the fourth mode, the answer to the above exemplary query: xe2x80x9cHow many times has Simulation package x been used to generate production estimates?xe2x80x9d might include not only how many times the package x has been used but also the values of the production estimates. This mode also uses the pointer information in order to formulate the query to retrieve the appropriate database material.
According to a preferred embodiment, an information management method is implemented by the information management system, whereby one or more users such as administrators, annotation authors, readers, and/or applications, start the information management method of the present invention by setting up an annotation structure. Using the information management system, a user is capable of performing any one or more of the following tasks or processes:
Enter annotations about the data or fields by various input means.
Browse annotations in the context of data.
Simultaneously query for both annotations and data.
Query for particular annotations in the context of data.
Query across the full body of annotations.
Query for particular data in the context of the annotations.
It is therefore clear that the information management system is not domain specific, in that it can be used in combination with any application regardless of the complexities of the underlying technical or professional fields. The data model for the annotations (i.e., the annotation metadata model) is generic, self-describing, and self-contained.
The information management system is adaptable to the user""s query preferences in that the information management system provides the ability to operate in a datacentric mode or in an annotation-centric mode. The data centric-mode will be explained in connection with FIGS. 5 and 6, and allows the user to select desired data items and to subsequently query and retrieve data and annotations based on these data items. The annotation-centric mode will be explained in connection with FIGS. 7 and 8, and allows the user to select the annotation categories and to subsequently query and retrieve data and annotations based on the content of the selected annotation categories. As a result, the information management system allows both data and annotations to be queried, in that queries can be made over the data content, over the annotation content, or over both simultaneously. This provides the ability to query the annotations, or the annotations and the data, and further provides the ability to retrieve the annotations when their associated data is retrieved.
Yet another feature of the information management system is its ability to allow annotations to be targeted to, or associated with data at different levels of granularities, such as: collection/view/table, attribute/column, instance/row, cell, arbitrary combinations thereof, and so forth.
Still another feature of the information management system is its ability to support storage and retrieval of annotations with a generic structure or a more specific structure, where the structure can depend on the nature of the data being annotated and the context of the author of the annotation.
In addition, the information management system is capable of supporting annotations of data in a variety of sources, formats, and/or data models. The information management system can annotate data in multiple sources when coupled with a data integration engine, in only one source, or in any source regardless of the source""s data model (diverse sources). Further, the information management system can annotate views on the data in these sources, without requiring the data sources being annotated to be modified. The information management system can have multiple annotations for the same data object, and different annotations on the same data item can be entered by different people/applications or by the same person/application at different times. Moreover, when the annotations are retrieved, they can be filtered or modified in a way that depends on the context of the reader. The annotations can also be propagated to specific target data items that can be selected from a drop down list, or by entering a free format text, numeric, document, URL, and so forth.

Method and system for organizing an annotation structure and for querying data and annotations

International Business Machine Corporation


A motor operated butterfly valve arrangement, at least one valve element of which is to be brought into a proper extreme position such that water leakage or the like does not occur within the pipe controlled by the valve element, without the necessity to improve dimensional or mounting accuracy of the components and without the need to lock the motor actuating the valve element. An elastically deformable elastic coupling member is provided in a coupling mechanism interconnecting the motor and the valve element. As soon as the valve element reaches the desired extreme position in contact with a stopper, the motor is rotated to deform the elastic coupling member and to improve the contact between the valve element and the stopper. The motor is stopped in the deformed state of the elastic coupling member.

The present invention relates to a motor operated butterfly valve arrangement for controlling the opening state of at least one pipe, comprising at least one valve element movably arranged within the pipe, a motor, and a coupling mechanism between the motor, and the valve element in order to vary the orientation of the valve element in relation to the pipe between different opening states with differing orientations of the valve element. At least one of the opening states is defined by mechanical contact between the valve element and a stopper of the pipe. The invention relates to a motor operated butterfly valve having a valve element arranged within a pipe. The valve element has an orientation thereof varied through operation of a motor to control an opening state of the pipe.
Motor operated butterfly valves can be used for controlling the opening/closing/switching, etc. of hot water piping in an automobile air-conditioner, for example. Generally the orientation of a least one disk-shaped valve element provided inside a pipe is varied by the driving force of a motor to control the opening state of the pipe.
In practice, motor operated butterfly valves are controlled such that the motor simply is stopped at, e.g. an extreme stop position of the valve element. This can be the fully closed position at which the pipe is fully closed. A satisfactory fully closed state often cannot be achieved due to unavoidable errors attributable to dimensional accuracy and mounting accuracy of the components. If the extreme stop position is the fully closed position, then water may still leak through. If the extreme stop position is the fully opened position, said valve element may cause an undesirable flow throttling effect.
In practice it is known to overcome said problems by locking the motor in a state when the valve element remains loaded in its closing direction even at the fully closed position in order to intentionally press said valve element into its fully closed position. This is however, not desirable in view to the durability of the motor.
There are butterfly valve arrangements comprising a plurality of valve elements collectively controlled in parallel with each other. Even if said valve elements are driven to carry out exactly the same opening and closing motions, the respectively achievable opening or closing states may slightly differ among the valve elements due to errors attributable to dimensional accuracy, mounting accuracy, differing slacks in the driving mechanism, etc. Accordingly, in such cases for safety sake for each valve element an own motor is to be provided. This is uneconomical since the cost of parts are high and the mounting space is excessively large.
It is an object of the present invention to provide a motor operated butterfly valve arrangement or butterfly valve, the valve element of which can be brought to a proper stop state at an extreme stop position such that no water leak or the like can occur, and without the need to improve the dimensional accuracy or mounting accuracy of individual components, and also without the need to lock the motor.
The object of the invention is achieved by a motor operated butterfly valve arrangement for controlling the opening state of at least one pipe, having at least one valve element movably arranged within the pipe, a motor, and a coupling mechanism between the motor and the valve element in order to vary the orientation of the valve element in relation to the pipe between different opening states with differing orientations of the valve element. At least one of the opening states is defined by mechanical contact between the valve element and a stopper of the pipe. The coupling mechanism includes an elastic coupling member for elastically taking up by deformation an extra driving motion increment of the motor in relation to the valve element as soon as the valve element is stopped at the stopper, the extra driving motion increment continuing the former motor driving motion.
The motor operated butterfly valve has a valve element arranged within a pipe. The valve element has an orientation thereof varied through operation of a motor to control an opening state of the pipe wherein a driving arm rotated by the motor and a driven arm coupled to the valve element are elastically coupled to each other by an elastic coupling member, the motor being controlled to bring the valve element to a stopped state in contact with a stopper at least one extreme stop position thereof. The motor is controlled further on to rotate the driving arm extra after the valve element comes into contact with the stopper and the motor first is stopped after having fulfilled the extra rotation.
According to the present invention in general the motor carries out an extra driving motion increment as soon as said valve element has reached its extreme position, and then the motor is stopped without being locked. In accordance with a further aspect of the invention the driving arm transmitting the driving motion of said motor via said coupling mechanism containing said elastic coupling member is rotated an extra amount by the motor after the valve element has come into contact with the stopper at the predetermined extreme stop position thereof. After said extra rotation, said motor is stopped. The valve element and the driven arm coupled to said valve element remain stopped while the elastic coupling member elastically coupling the driving arm and the driven arm is elastically deformed by the driving force of the motor and the extra rotation thereof, with the result that the elasticity of the coupling member serves to press said valve element firmly against the stopper, and to keep it in a pressed condition. The reaction force of the deformed elastic coupling member can be set weak enough to avoid locking the motor. Accordingly, even if there is a dimensional error, mounting error or the like among the individual components, the valve element can be brought to a proper stop state such that water leakage or the like cannot occur and without the need to lock the motor.
Resulting from the elastic coupling member provided in said coupling mechanism, the coupling mechanism is designed with a restraint lost motion feature, allowing said elastic coupling member to generate a load pressing said valve element into its extreme position by an extra driving motion increment of said motor in continuation of the former driving motion and for a limited extent. Since there is no rigid connection between the motor and the valve element, the motor can be stopped normally after carrying out this extra driving motion increment, without the need to lock it. Said elastic coupling member takes up the extra driving motion increment and generates the desirable pressing force of the valve element. Due to said elastic pressing force, the valve element reaches its extreme position precisely and reliably irrespective of mounting or dimension tolerances, because it is dragged by said elastic coupling member into the correct extreme stopping position. Said extra driving motion increment caused by the motor is of a larger magnitude than needed. This establishes a broad safety margin within which the valve element reliably can be brought into the desired extreme position without the necessity to lock the motor, because the reaction force on the motor can be weak.
In a preferred embodiment, said valve element may have two different extreme positions each defined by a respective stopper. Said elastic coupling member is acting bi-directionally, i.e. generates its lost motion feature in both driving directions of the motor.
Expediently said elastic coupling member is storing the driving power by elastic deformation and is generating an increased contact pressure between the valve element and its stopper. Said contact pressure may be lower than the driving force or driving torque of the motor.
In another embodiment, a single motor is coupled with a plurality of valve elements via a number of elastic coupling members equal to the number of said valve elements. When said motor has carried out its extra driving motion increment after at least one of said valve elements is contacting its respective stopper, all valve elements coupled to said common motor will be reliably brought in their extreme stop positions. Each elastic coupling member then might be deformed different from another depending on the individual tolerance which has been compensated for.
The elastic coupling member may be a spring member engaging with both the driving arm and the driven arm. As soon as the valve element is in contact with the stopper and the driving arm is rotated extra by the motor, the driven arm and the valve element will remain stopped in the correct extreme position while the elastic coupling member is elastically deformed. The magnitude of the extra rotation of said motor has to be set to a value which reliably covers at least the possible tolerances of said valve element and any slacks within the force transmission path between the motor and the valve element.
In an expedient embodiment, the elastic spring member is a coil spring having a forked portion for holding both arms or lateral pins of both arms. As soon as the driving arm is rotated an extra amount by the motor after the valve element contacts the stopper, the elastic spring member is elastically deformed such that a gap defined by said forked portion is widened. Said forked portion design of said spring member is advantageous because said spring member can act in both moving directions of said valve element.
Said extreme stop position of the valve element may be the position at which the pipe is fully closed. Only then said elastic coupling member is deformed to take up the extra driving motion increment of said motor. In the other extreme position of the valve element, which can be the fully opened position, the motor may stop normally without carrying out any extra driving motion.
In an alternative embodiment the pipe may be a branching pipe. The valve element is located at the location of the branch function. The orientation of the valve element can be varied to alternately interconnect two branch pipes of four branch pipes or to interconnect all branch pipes. Two extreme stop positions of said valve elements can be provided where alternatively two respective branch pipes are fully interconnected. In each extreme position, the motor is rotated extra as soon as the valve element has contacted its stopper. It suffices to provide only one elastic coupling member, which is acting bi-directionally.
In another embodiment, there may be a plurality of valve elements in parallel with each other, driven by a common single motor. An elastic coupling member is provided between each of the driven arms of the plurality of valve elements and the motor. There might even be the same number of driving arms as driven arms. If there are deviations among the respective extreme positions of the valve elements because of errors attributable to dimensional accuracy, mounting accuracy, slack in the transmission, etc., the respective elastic coupling element is compensating for said differences automatically when said motor has been rotated an extra amount after at least one of said valve elements has contacted its stopper. The elastic coupling element of each valve element ensures that the orientations of all valve elements may be controlled collectively by the single motor, and that each valve element reliably reaches its extreme position even if the extreme positions slightly differ from one another.
In order to save mounting space and to avoid power losses during the transmission of the driving force of the motor, the output shaft and the valve element shaft ought to be arranged axially with the driving and driven arms essentially parallel to each other, and the elastic spring member coupling both arms via respective lateral pins. The elastic spring member defining said elastic coupling member can be carried either by the valve element shaft or by the motor output shaft, respectively. If the active lever arm of the driven arm is shorter than the active lever arm of the driving arm, said elastic coupling member can even increase the actuation force for the valve element. In order to achieve a predetermined actuating force a low torque motor can be used. In this case, the swivelling stroke of the driving arm is larger than the swivelling stroke of the driven arm. The arrangement can be inversed as well, in order to achieve a relatively enlarged swivelling stroke for the valve element compared to a shorter swivelling stroke or rotation of the motor and the driving arm. In the first mentioned arrangement, the reaction torque of the deformed elastic coupling member is weaker for the motor than the torque keeping the valve element in contact with its stopper.