A flexible circuit electronic package including a heat sink, a flexible circuit having a semiconductor chip positioned thereon and electrically coupled thereto, and a quantity of heat shrunk adhesive securing the flexible circuit to the heat sink such that the flexible circuit is planar. This package is then adapted for being positioned on and electrically coupled to a circuitized substrate such as a printed circuit board. A method of making this package is also provided.

Flexible (or "flex") circuit electronic packages typically include one or more flex circuit members each including at least one thin layer of dielectric (e.g., polyimide) with a pattern of conductors (e.g., copper pads) positioned on a surface thereof designed to accommodate a semiconductor chip (also referred to herein simply as a chip) thereon which is electrically connected to the conductors (e.g., using solder balls) and thereby to other circuitry of the flex circuit which is also coupled to the conductors. This flex circuit in turn is designed for being mounted on another circuitized substrate, typically in the form of a multilayered printed circuit board (also referred to herein simply as a PCB). The printed circuit board in turn typically includes a dielectric substrate (e.g., organic resin material reinforced by fibers, also referred to in the PCB industry as "FR-4" material) and multiple layers of electrically conductive circuit traces as well as ground and power layers. Many flex circuit electronic packages utilize solder balls to also couple the flex circuit to the respective conductors of the host PCB.
When positioning and electrically coupling a chip to a flex circuit using solder balls, some amount of flex circuit warping will occur, which is undesirable from both manufacturing and product functioning standpoints. This warping occurs because the flex circuit is of an extremely thin (e.g., sometimes having an overall thickness of only about 8 mils (a mil being a thousandths of an inch) to 25 mils) polymer dielectric material, and is thus very susceptible to bending from the heat generated during the solder reflow process required to form the chip-flex bond. Various attempts, some defined in greater detail below, have been undertaken to prevent such warping. One particular example of such an attempt is to use what is referred to as a "stiffener" or "lid", which are typically of rigid metal construction and usually secured to the flexible circuit at some location (e.g., about the outer periphery). Adding these members to such packages also often necessitates usage of additional processing fixtures, thereby adding to the cost of the final package. As flexible circuits become thinner and thus more flexible (due to increased demands for miniaturization in today's products using these packages), it is desirable to increase planarity of the flexible circuit without the need for such added members and processing.
As understood from the following, the present invention represents what is believed is a significant improvement in approaches to assuring effective planarity of the flex circuit relative to the coupled chip, and thus also relative to a host PCB to which it is to be coupled. Such planarity is essential to assuring a sound connection between the many conductors of the flex and those of the underlying host PCB when solder ball connections are being used, especially when highly dense patterns of such conductors are utilized. In some of today's patterns, for example, the conductors of a flex circuit and those of the accommodating PCB may be so closely spaced that the center-to-center spacings between such conductors is only from about 12 mils to 50 mils. As defined herein, the invention is able to provide such planarity without the need for a "stiffener" or "lid" as required in many prior art products.
The following U.S. Patents describe various approaches to providing desired spacings between electronic package and the like structures. The citation of these patents is not an admission that any are prior art to the present invention.
In U.S. Pat. No. 5,045,921, there is described an electronic pad array carrier device for mounting on a printed circuit board or flex circuit substrate, the device having a thin, flexible "tape" substrate having a plurality of traces. The substrate may be polyimide or other material that can withstand relatively large lateral mechanical displacement. An integrated circuit die is mounted in proximity with or on the substrate and electrical connections between the integrated circuit chip and the traces are made by any conventional means. The substrate traces are provided at their outer ends with solder balls or pads for making connections to the PCB. A package body covers the die, which body may be optionally used to stand off the package a set distance from the PCB so that the solder balls will form the proper concave structure. Alternatively, a carrier structure may be provided around the periphery of the substrate to add rigidity during handling, testing and mounting, but which may also provide the stand-off function. The thin, flexible substrate can absorb a relatively large lateral or even vertical mechanical displacement over a rather large package area. The substrate may be optionally transparent or translucent to permit inspection of the bonds after mounting to the PCB. The PCB or flex circuit may also be transparent or translucent for bond inspection purposes. The solder pads or balls may be joined to a via through the substrate at least partially filled with electrically conductive material to permit back side testing of the carrier before or after mounting of the package to the PCB. Additionally, a heat sink structure may be directly bonded to the die in the pad array carrier IC device.
In U.S. Pat. No. 5,170,931, there is described a method and apparatus for mounting a flexible film semiconductor chip carrier on a second level electronic package. The resulting electronic packaging structure includes electrically conductive spacers, such as solder balls or solder coated copper balls, which electrically interconnect outer lead bonding pads on the flexible film semiconductor chip carrier and corresponding bonding pads on the second level electronic package, and which physically support the flexible film of the semiconductor chip carrier substantially in a plane above the surface of the second level electronic package. This electronic packaging structure is made using a special assembly fixture comprising a base plate, a pressure insert with a resilient member, and a top plate. The flexible film semiconductor chip carrier with the spacers attached thereto is placed over the resilient member of the pressure insert which is clamped together with the second level electronic package between the top and base plates. Then, this assembly is heated to reflow the solder of the spacers, and the assembly fixture is disassembled, leaving the flexible film semiconductor chip carrier mounted on the second level electronic package with the flexible film of the carrier having a planar geometry as desired. The spacers may be attached to the flexible film semiconductor chip carrier using a special template having a pattern of openings corresponding to the pattern of outer lead bonding pads on the flexible film semiconductor chip carrier.
In U.S. Pat. No. 5,562,517, there is described a spacer for use in a field emission device which comprises a comb-like structure having a plurality of elongated filaments joined to a support member. The filaments, which may be glass, are positioned longitudinally in a single layer between the facing surfaces of the anode structure and the electron emitting structure. Support member is positioned entirely outside the active regions of anode structure and emitting structure. The spacer provides voltage isolation between the anode and cathode structures, and also provides standoff of the mechanical forces of vacuum within the assembly.
In U.S. Pat. No. 5,673,479, and in U.S. Pat. No. 5,896,651 (a divisional of U.S. Pat. No. 5,673,479), there is described a Tape-Automated-Bonding (TAB) package which includes a resilient polyimide layer that supports a metal lead-frame. A microelectronic circuit die is mounted in a hole in the polyimide layer and interconnected with inner leads of the lead-frame. The TAB package is adhered to a support member having spacers that abut against the surface of a printed circuit board on which the package is to be mounted and provide a predetermined spacing between the lead-frame and the surface. Outer leads that protrude from the lead-frame are bent into a shape so as extend, in their free state, toward the surface at least as far as the spacers. The package and support member assembly is placed on the PCB surface, and the combination of the weight of the assembly, the resilience of the leads and the preset standoff height enable the leads to resiliently deform so that the spacers abut against the surface and the leads conformably engage with the surface for soldering or other ohmic connection to conjugate bonding pads on the surface. The support member can be formed with lead retainers around which the leads extend to form loops that resiliently and conformably engage with the surface as the assembly is lowered thereon. The support member maintains co-planarity, adds weight to the package, pre-sets the standoff to protect the formed outer leads during surface mounting and enables the package to be shipped without a separate carrier.
In U.S. Pat. No. 5,796,590, and in U.S. Pat. No. 5,930,889 (a divisional of U.S. Pat. No. 5,796,590), there is described an apparatus and method for surface-mounting ball grid array integrated circuit (IC) devices to printed circuit boards. A thin single- or multi-layer sheet of nonconductive material having a plurality of apertures corresponding to the leads of the IC device to be mounted is interposed between the ball grid array and the circuit board prior to solder processing to facilitate solder application, device alignment, and solder retention. An assembly guide is located on the top surface of the aid to assist in the orientation and placement of the IC device during assembly. In a further aspect, the disclosed assembly aid helps compensate for non-planarity in the IC device array or circuit board, and maintains a minimum standoff distance between the IC package and the circuit board to preclude undue solder joint deformation. The assembly aid also allows for reworking of the surface mount by facilitating localized placement of the solder prior to reflow processing without masking or other additional processing steps.
In U.S. Pat. No. 5,805,427, there is described a surface mount package to encapsulate one or more semiconductor devices which has a standoff that maintains the thickness of solder columns bonding the package to an external circuit. The standoff either extends over or circumscribes a central portion of the package base. To enhance the thermal performance of the standoff, a solderable layer enhances soldering of the standoff to the external circuit. In alternative embodiments, the standoff contains a flange having a plurality of apertures useful for either mechanically locking an adhesive or for enabling irradiation of an adhesive by a light source. The standoff may contain protrusions for alignment, strength or circuit routing.
In U.S. Pat. No. 6,152,756, there is described a socket for interconnecting an electronic package with a circuit board which comprises a base, a cover slidably attached to the base, and supporting means downwardly extending from the base. The base comprises a pair of extension plates diagonally extending there-from. The supporting means in the form of a pair of standoffs is formed on the respective extension plates. Since each standoff has a height slightly smaller than that of solder balls formed on a lower surface of the base, the standoffs rest on the circuit board after the socket is soldered thereto. By such a design, the external force employed to actuate the cover to slide along the base is transferred from the base to the standoffs. Hence, deformation of the base and damage to the solder joint are obviated to ensure a reliable connection between the PGA package and the circuit board.
In U.S. Pat. No. 6,411,513, there is described a compliant, thermally conductive interface device for use between two surfaces, such as a component and a heat sink surface, that can accommodate a range of gap distances and angular misalignment (tilt). The device is comprised of a plurality of foils stacked in a densely-packed, nested fashion. The foils may extend between the surfaces. Embodiments are described for use with flat, two-dimensionally curved, three-dimensionally curved, and cylindrical surfaces (such as heat pipes). Preferably, the foils are pre-formed in a shape corresponding to their fully compressed shape in a device and stacked directly against each other. After bonding the plurality of adjacent foil proximal edges together and the plurality of adjacent foil distal edges together, the assembly is extended to produce interstitial separation distances between adjacent foil flexing sections to accommodate future flexing and the height to accommodate future compression and tilt.
In U.S. Pat. No. 6,414,849, there is described a low stress, low profile, cavity down wire bond or flip-chip BGA package which is formed by injection molding or thermosetting of liquid crystal plastic (LCP) to form a die carrier including a polymer solder grid array (PSGA) of standoff posts formed during molding of the die carrier. The standoff posts are coated with copper during plating of the die carrier, on the surfaces of which conductive traces are etched from the standoff posts into a die cavity, including on the sidewalls of the die cavity, to wire bond sites or small solderable areas at the bottom of the cavity. After mounting of a wire bond or flip-chip integrated circuit die within the die cavity of the die carrier, the packaged integrated circuit is mounted on a main printed circuit board substrate utilizing conductive paste to electrically connect the standoff posts to conductive solderable areas on the main PCB substrate. The high aspect ratio and/or large height of the plated standoff posts reduces stress on the solder joints and, combined with the flexibility of the LCP die carrier, improves solder joint reliability after reflow and during operation.
In U.S. Pat. No. 6,444,563, there is described a ball grid array or chip scale package integrated circuit which is manufactured by first identifying the most unreliable solder ball joints in the IC. These worst case joints, or joints in the vicinity of the worst case joints, are changed in pad dimension and exposed to more ball/bump conductive material than the other more robust joints in the IC to create a ball on a larger pad that is larger than the normal sized ball. The larger balls are formed by placing multiple smaller balls together on a single pad to form one larger ball during a reflow operation. The larger ball improves the overall IC reliability by improving the reliability of the weakest joints in the IC design. In addition, the standoff of both the larger balls and the smaller balls are engineered to be substantially equal.
In U.S. Pat. No. 6,560,122, there is described an integrated circuit chip package which includes an integrated circuit chip that is mounted on a substrate by a reflow process and by a plurality of solder bumps. At least one standoff is located between the circuit chip and the substrate to maintain a distance between the circuit chip and the substrate during the reflow process. A mold compound is used for under-filling air gaps between the chip and the substrate. The integrated circuit chip package is formed by placing the chip and substrate within a mold cavity and pressing a transfer mold compound into the mold cavity. Air spaces between the integrated circuit chip and the substrate are under-filled by the mold compound as it is pressed in between the integrated circuit chip, the standoffs and the substrate. Air is allowed to escape from between the chip and the substrate during the under-filling through a vent which extends through the substrate. The under-filling material may also be used to encapsulate the chip at the same time that under-filling is performed.
In U.S. Pat. No. 6,631,078, there is described a heat dissipating flexible or resilient standoff which is mechanically clamped between an electronic module and substrate, such as, PCB. The clamping arrangement comprises a heat sink compressing a thermally conductive flexible interface pad over the upper surface of the electronic module by way of mechanical linkage to the PCB. The heat dissipating flexible standoff provides a force opposing the compression force to thereby reduce stress on solder ball connections between electronic module and PCB. Thermally conductive flexible standoffs in the form of spring arrangements, such as a wire mesh, act to provide heat dissipation by both thermal conduction and thermal convection. A thermally conductive flexible polymer pad and a layer of porous metal foam may also act as thermally conductive standoffs.
In U.S. Pat. No. 6,986,454, there is described an electronic package which includes a circuit board having a substrate and circuitry and a surface mount device having a contact terminal. A mounting pad is formed on the circuit board. The electronic package also includes a solder joint connecting the contact terminal of the surface mount device to the mounting pad on the circuit board. The solder joint includes a reflowable solder and a plurality of stand-off members. The stand-off members provide a separation distance (H) between the circuit board and surface mount device in the range of about 0.01 mm to 0.10 mm.
In U.S. Pat. No. 7,118,940, there is described an electronic package having a controlled standoff height between a surface mount device and a circuit board. The electronic package includes a circuit board having a substrate and circuitry including mounting pads and a surface mount device having circuitry and contact terminals. Solder joints connect the contact terminals of the surface mount device to the mounting pads on the circuit board. A dielectric under-fill is disposed between the circuit board and the surface mount device, and a plurality of standoff members are disposed in the under-fill material to provide a separation distance between the circuit board and the surface mount device.
As defined herein, the present invention is able to assure effective planarity of the flex circuit relative to the chip bonded thereto (and to other components of the package, if necessary). The invention is able to accomplish this without using a stiffener or similar member which has heretofore been essential in many electronic packages, such a stiffener being bonded directly to the flex (e.g., along a large portion of the outer periphery). Still further, the invention is able to accomplish this without using complex and costly elements and/or processing equipment, thus allowing the manufacturer of the invention to pass on cost savings to the package consumer. It is believed that such a package will represent a significant advancement in the art.

Flexible circuit electronic package with standoffs

Endicott Interconnect Technologies, Inc.


A process for alkylating aromatics comprises:

The present invention relates to a process for alkylating aromatics.
Zeolite and other porous crystalline molecular sieve catalysts are increasingly being used in low temperature, liquid phase aromatic alkylation processes including ethylbenzene, cumene, and linear polyalkylbenzene (LAB) synthesis. Operation at lower temperatures improves process economics and, in many cases, product selectivity. However, trace feed impurities such as low molecular weight nitrogen, sulfur, and oxygen compounds, which are not strongly adsorbed in higher temperature vapor phase alkylation processes, are more problematic in the liquid phase processes. The affinity of these compounds for the active sites in the molecular sieve catalyst can cause rapid deactivation by displacing or neutralizing the acid site.
There are numerous methods known for reactivating catalysts. U.S. Pat. No. 2,541,044 to Daugherty discloses catalytic alkylation with simultaneous restoration of the alkylation catalyst activity by contacting the catalyst with an alkylatable hydrocarbon while interrupting the flow of alkylating agent. U.S. Pat. No. 3,148,155 to Schwartz describes removing metal poisons from cracking catalysts by contacting the poisoned catalyst with an aqueous solution of sulfurous acid, a water-soluble salt of sulfurous acid or a water-soluble salt of hyposulfurous acid. U.S. Pat. No. 4,418,235 to Haag discloses aromatic alkylation in the presence of steam to enhance or preserve zeolite catalyst activity. U.S. Pat. No. 4,550,090 to Degnan et al. describes a method for displacing high molecular weight poisons from ZSM-5 catalysts, such as those used in dewaxing, by in-situ treatment with more easily desorbed compounds such as ammonia or by treatment with alkali or alkaline metal cations to effect ion exchange. U.S. Pat. No. 4,276,149 to Chester et al. describes passivating metal contaminants on zeolite cracking catalysts by contacting with steam for limited periods. U.S. Pat. No. 4,678,764 to Le et al. discloses reactivation of noble metal-containing zeolites poisoned with sulfur oxides by contacting with aqueous acid solutions, e.g., nitric, carbon, acetic and formic acids. U.S. Pat. No. 4,319,057 to Kiser discloses regenerating molecular sieve dehydration materials with methanol or acetone. U.S. Pat. No. 5,425,934 to Malla et al. teaches treating zeolites with methanol, ethanol or propanol plus nitric or sulfuric acid for the removal of organic templates. U.S. Pat. Nos. 4,365,104 and 4,477,585 to Kaeding disclose enhancing para-selectivity of zeolite alkylation catalysts by treatment with hydrogen sulfide or carbon dioxide. U.S. Pat. 4,490,570 to Forward et al. discloses para-selective alkylation of a monoalkylbenzene wherein water in the form of steam can be co-fed with the reactants. U.S. Pat. No. 5,077,445 to Le discloses a process for liquid-phase synthesis of an alkylbenzene, such as ethylbenzene, using MCM-22 zeolite catalyst hydrated with liquid water. U.S. Pat. No. 5,191,135 to Dwyeret al. discloses preparing long chain alkyl substituted aromatic compounds by alkylating naphthalenes with C6+ alkylating agent in the presence of large pore size zeolite such as USY and MCM-22 in the presence of 0.5 to 3.0 wt % co-fed water to increase selectivity to monoalkyl-substituted products.
All of the above patents are incorporated in their entirety herein by reference.
It would be desirable to provide a process for reactivating liquid phase alkylation catalysts which have been contaminated by trace quantities of strongly sorbed poisons. It would be especially useful to provide a method for reactivating such catalysts in-situ by treatment with species that are introduced along with the liquid phase or vapor phase feed streams.
In one aspect, the present invention relates to a process for alkylating aromatics which comprises:
i) contacting a feed containing alkylatable aromatic under liquid phase alkylating conditions with an alkylating agent of no greater than 5 carbon atoms in the presence of an alkylation catalyst comprising a porous crystalline material, to provide an alkylated aromatic product during which contacting said catalyst becomes at least partially deactivated by sorbing catalyst poisons present in said feed;
ii) treating said catalyst in situ by contacting with at least one polar compound having a dipole moment of at least 0.05 Debyes under conditions of temperature and pressure employed in said liquid phase alkylating conditions which are sufficient to at least partially desorb said catalyst poison from said catalyst; and
iii) collecting said alkylated aromatic product.
In another aspect, the present invention relates to a process for alkylating aromatics which comprises:
1) contacting a feed containing alkylatable aromatic under liquid phase alkylating conditions with alkylating agent in the presence of an alkylation catalyst comprising a porous crystalline material to provide an alkylated aromatic product during which contacting said catalyst becomes at least partially deactivated by sorbing catalyst poisons present in said feed;
2) treating said catalyst in situ by contacting with at least one non-aqueous polar compound having a dipole moment of at least 0.05 Debyes under conditions of temperature and pressure employed in said liquid phase alkylating conditions which are sufficient to at least partially desorb said catalyst poison from said catalyst; and
3) collecting said alkylated aromatic product.
The above and other objects, features and advantages of the present invention will be better understood from the following detailed descriptions, all of which are given by illustration only, and are not limitative of the present invention.
Alkylation Catalysts
Acidic solid oxides which may be used to catalyze the present alkylation reaction include PSH-3, SSZ-25, MCM-22, MCM-36, MCM49 and MCM-56. PSH-3 is described in U.S Pat. No. 4,439,409. SSZ-25 and its use in aromatics alkylation is described in U.S. Pat. No. 5,149,894. MCM-22 and its use to catalyze the synthesis of alkylaromatics, including ethylbenzene, is described in U.S. Pat. Nos. 4,992,606; 5,077,445; and 5,334,795. MCM-36 is described in U.S. Pat. Nos. 5,250,277 and 5,292,698. U.S. Pat. No. 5,258,565 describes the synthesis of alkylaromatics, including ethylbenzene, using a catalyst comprising MCM-36. MCM-49 is described in U.S Pat. No. 5,236,575. The use of MCM49 to catalyze the synthesis of alkylaromatics, including ethylbenzene, is described in U.S. Pat. Nos. 5,493,065 and 5,371,310. MCM-56 is described in U.S. Pat. No. 5,362,697. The use of MCM-56 to catalyze the synthesis of alkylaromatics including ethylbenzene is described in U.S. Pat. Nos. 5,557,024 and 5,453,554. A preferred group of catalysts for use in the present invention is selected from the group consisting of MCM-22, MCM-36, MCM-49 and MCM-56, and most preferably, MCM-22.
Alternative catalysts suitable for use herein include medium pore zeolites having a Constraint Index of 2-12 (as defined in U.S. Pat. No. 4,016,218), such as ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, and ZSM-48. ZSM-5 is described in detail in U.S. Pat. No. 3,702,886. ZSM-11 is described in detail in U.S. Pat. No. 3,709,979. ZSM-12 is described in U.S. Pat. No. 3,832,449. ZSM-22 is described in U.S. Pat. No. 4,556,477. ZSM-23 is described in U.S. Pat. No. 4,076,842. ZSM-35 is described in U.S. Pat. No. 4,016,245. ZSM48 is more particularly described in U.S. Pat. No. 4,234,231.
In addition, large pore zeolites, including those zeolites having a Constraint Index less than 2, are suitable for use as the catalyst in the process of the invention. Suitable large pore zeolites include zeolite Beta, zeolite Y, Ultrastable Y (USY), Dealuminized Y (Deal Y), mordenite, offretite, ZSM-3, ZSM-4, ZSM-18, and ZSM-20. Zeolite ZSM-4 is described in U.S. Pat. No. 3,923,636. Zeolite ZSM-20 is described in U.S. Pat. No.3,972,983. Zeolite Beta is described in U.S. Pat. Nos. 3,308,069, and Re. No. 28,341. Low sodium Ultrastable Y molecular sieve (USY) is described in U.S. Pat. Nos. 3,293,192 and 3,449,070. Dealuminized Y zeolite (Deal Y) may be prepared by the method found in U.S. Pat. No. 3,442,795. Zeolite UHP-Y is described in U.S. Pat. No. 4,401,556.
The zeolite crystals employed in the present invention can be shaped into a wide variety of particle sizes. Generally speaking, the particles can be in the form of a powder, a granule, or a molded product such as an extrudate having a particle size sufficient to pass through a 2 mesh (Tyler) screen and be retained on a 400 mesh (Tyler) screen. In cases where the catalyst is molded, such as by extrusion, the crystals can be extruded before drying or partially dried and then extruded.
The crystalline material may be composited with another material which is resistant to the temperatures and other conditions employed in the alkylation process of this invention. Such materials include active and inactive materials and synthetic or naturally occurring zeolites as well as inorganic materials such as clays and/or oxides such as alumina, silica or silica-alumina. The latter may be either naturally occurring or in the form of gelatinous precipitates or gels including mixtures of silica and metal oxides. Use of a material in conjunction with the zeolite, i.e., combined therewith or present during its synthesis, which itself is catalytically active may change the conversion and/or selectivity of the catalyst. Inactive materials suitably serve as diluents to control the amount of conversion so that alkylation products can be obtained economically and in an orderly manner without employing other means for controlling the rate of reaction These materials may be incorporated into naturally occurring clays, e.g., bentonite and kaolin, to improve the crush strength of the catalyst under commercial alkylation operating conditions and function as binders or matrices for the catalyst. The relative proportions of finely divided crystalline material and inorganic oxide matrix vary widely, with the crystal content ranging from about 1 to about 90 percent by weight and more usually, particularly when the composite is prepared in the form of beads, in the range of about 2 to about 80 weight percent of the composite.
The stability of the catalyst used in the present process may be increased by steaming. U.S. Pat. Nos. 4,663,492; 4,594,146; 4,522,929; and 4,429,176, describe conditions for the steam stabilization of zeolite catalysts which can be utilized to steam-stabilize the catalyst. Reference is made to these patents for a detailed description of the steam stabilization technique for use with the present catalysts. The steam stabilization conditions typically include contacting the catalyst with, e.g., 5-100% steam at a temperature of at least about 300xc2x0 C. (e.g., 300xc2x0-650xc2x0 C.) for at least one hour (e.g., 1-200 hours) at a pressure of 101-2,500 kPa. In a more particular embodiment, the catalyst can be made to undergo steaming with 75-100% steam at 315xc2x0-500xc2x0 C. and atmospheric pressure for 2-25 hours. The steaming of the catalyst can take place under conditions sufficient to initially increase the Alpha Value of the catalyst, the significance of which is discussed below, and produce a steamed catalyst having an enhanced Alpha Value. If desired, steaming can be continued to subsequently reduce the Alpha Value from the higher Alpha Value to an Alpha Value which is substantially the same as the Alpha Value of the unsteamed catalyst.
Reactants
The reactants used in the process of the invention include an alkylatable aromatic compound and an alkylating agent.
The term xe2x80x9caromaticxe2x80x9d in reference to the alkylatable compounds that are useful herein is to be understood in accordance with its art-recognized scope that includes alkyl substituted and unsubstituted mono- and polynuclear compounds. Compounds of an aromatic character, which possess a heteroatom, are also useful provided they do not act as catalyst poisons under the reaction conditions selected.
Substituted aromatic compounds that can be alkylated herein must possess at least one hydrogen atom directly bonded to the aromatic nucleus. The aromatic rings can be substituted with one or more alkyl, aryl, alkaryl, alkoxy, aryloxy, cycloalkyl, halide, and/or other groups that do not interfere with the alkylation reaction.
Suitable aromatic hydrocarbons include benzene, toluene, naphthalene, anthracene, naphthacene, perylene, coronene, and phenanthrene, with benzene being preferred.
Generally the alkyl groups that can be present as substituents on the aromatic compound contain from about 1 to 22 carbon atoms, usually from about 1 to 8 carbon atoms, and most usually from about 1 to 5 carbon atoms.
The alkylating agents that are useful in the process of this invention generally include any aliphatic or aromatic organic compound having one or more available alkylating aliphatic groups capable of reaction with the alkylatable aromatic compound. Examples of suitable alkylating agents are C2-C16 olefins such as C2-C5 olefins, viz., ethylene, propylene, the butenes, and the pentenes; C1-C12 alkanols (inclusive of monoalcohols, dialcohols, trialcohols, etc.), preferably C1-C5 alkanols, such as methanol, ethanol, the propanols, the butanols, and the pentanols; C2-C20 ethers, e.g., C2-C5 ethers including dimethylether and diethylether; aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, and n-valeraldehyde; and alkyl halides such as methyl chloride, ethyl chloride, the propyl chlorides, the butyl chlorides, and the pentyl chlorides, and so forth. It is generally preferred that the alkylating agent has no greater than 5 carbon atoms, more preferably no greater than 3 carbon atoms. Thus the alkylating agent can preferably be selected from the group consisting of C2-C5 olefins and C1-C5 alkanols.
Mixtures of light olefins are especially useful as alkylating agents in the alkylation process of this invention. Accordingly, mixtures of ethylene, propylene, butenes, and/or pentenes which are major constituents of a variety of refinery streams, e.g., fuel gas, gas plant off-gas containing ethylene, propylene, etc., naphtha cracker off-gas containing light olefins, refinery FCC propane/propylene streams, etc., are useful alkylating agents herein. For example, a typical FCC light olefin stream possesses the following composition:
The feed comprising reactants of the present process can contain catalyst poisons. Such materials while present in trace amounts can cause deactivation of the alkylation catalyst over time. Catalyst poisons which are strongly sorbed to the alkylation catalyst under liquid phase alkylation conditions include nitrogen compounds, sulfur compounds and oxygen compounds of low molecular weight, say, no greater than 500, preferably no greater than 300. Such catalyst poison compounds can include ammonia, alkylamines, e.g., methylamine and n-propylamine, N-formyl morpholine and N-methyl pyrrolidine. These catalyst poisons can make up to 100 ppm of the total feed to the process, e.g., 0.001 to 100 ppm.
Products
Suitable alkyl substituted aromatic compounds which can be prepared from the alkylation process of the present invention include toluene, xylene, isopropylbenzene (cumene), normal propylbenzene, alpha-methylnaphthalene, ethylbenzene, mesitylene, durene, cymenes, butylbenzene, pseudocumene, o-diethylbenzene, m-diethylbenzene, p-diethylbenzene, isoamylbenzene, isohexylbenzene, pentaethylbenzene, pentamethylbenzene; 1,2,3,4-tetraethylbenzene; 1,2,3,5-tetramethylbenzene; 1,2,4-triethylbenzene; 1,2,3-trimethylbenzene, m-butyltoluene; p-butyltoluene; 3,5-diethyltoluene; o-ethyltoluene; p-ethyltoluene; m-propyltoluene; 4-ethyl-m-xylene; dimethyinaphthalenes; ethylnaphthalene; 2,3-dimethylanthracene; 9-ethylanthracene; 2-methylanthracene; o-methylanthracene; 9,10-dimethylphenanthrene; and 3-methyl-phenanthrene. Preferably, the alkylated aromatic product comprises monoalkylbenzene. Higher molecular weight alkylaromatic hydrocarbons can also be used as starting materials and include aromatic hydrocarbons such as are produced by the alkylation of aromatic hydrocarbons with olefin oligomers. Such products are frequently referred to in the art as alkylate and include hexylbenzene, nonylbenzene, dodecylbenzene, pentadecylbenzene, hexyltoluene, nonyltoluene, dodecyltoluene, pentadecyltoluene, etc. Very often alkylate is obtained as a high boiling fraction in which the alkyl group attached to the aromatic nucleus varies in size from about C6 to about C16.
Reaction Conditions
In general, the alkylation reactions of the present invention take place under liquid phase conditions, i.e., at least one of the reactants being in the liquid phase. The liquid phase alkylating conditions can comprise temperatures ranging from 100xc2x0 to 400xc2x0 C., preferably from 100xc2x0 to 300xc2x0 C., pressures ranging from 0.2 to 25 atmospheres, preferably ranging from 1 to 5 atmospheres, a WHSV of from 0.1 to 10, preferably from 0.5 to 5 and an alkylatable aromatic compound to alkylating agent mole ratio of from about 0.1:1 to 50:1, preferably from 0.5:1 to 5:1.
More specifically, liquid phase alkylation of benzene with ethylene may be carried out at temperatures between 300xc2x0 and 650xc2x0 F. (150xc2x0 to 340xc2x0 C.) usually in the range of 400xc2x0 to 520 F. (205xc2x0 to 270xc2x0 C.). Pressures during the liquid phase alkylation of benzene with ethylene may be as high as about 3000 psig (20875 kPa) although generally will not exceed 1000 psig (7000 kPa). The reaction may be carried out in the absence of hydrogen and accordingly the prevailing pressures are those of the reactant species. The space velocity may be from about 0.1 to 20 WHSV, based on the ethylene feed. Preferred space velocities for the liquid phase alkylation of benzene with ethylene include ranges, for example, from about 0.5 to about 3 WHSV, e.g., from about 0.75 to 2.0 WHSV, (ethylene). The ratio of the benzene to the ethylene in the alkylation reactor may be from 1:1 to 30:1 molar, normally about 5:1 to 20:1 molar, say from about 5:1 to 10:1 molar.
Polar Compound Reactivating Agent
Polar compounds suited for use in the present invention exhibit a dipole moment of greater than 0.05 Debyes (D), preferably greater than 0.1 Debyes. The polar compounds employed in the present process can be selected from the group consisting of water, carbon monoxide, carbon dioxide, hydrogen sulfide, dimethyl disulfide, sulfuric acid, carbonic acid, acetic acid, methanol, ethanol, 1-propanol, 2-propanol, n-butanol, nitric acid, formic acid, and acetone. Preferably, the polar compound is selected from the group consisting of water, acetic acid, carbonic acid, nitric acid and sulphuric acid. The polar compound can be a non-aqueous compound. Alternatively, the polar compound can be selected from the group of inorganic compounds, e.g., non-aqueous inorganic compounds.
The polar compound suited to use in the present invention is capable of displacing sorbed catalyst poisons from active sites of the alkylation catalyst under conditions, e.g., temperatures and pressures, encountered during alkylation. The displacing polar compound has a less deleterious effect upon catalyst activity and/or selectivity than the catalyst poison, producing a net improvement in catalyst activity and/or selectivity. The displaced poisons may remain on the catalyst in a less problematic state or, preferably, they may be expelled from a catalyst bed as the added polar compound permeates the catalyst bed.
Inasmuch as the catalyst is exposed to the polar compound in situ, the present invention can permit reactivation of catalysts without removal of the catalyst from the process vessel, ideally while the catalyst is still at temperature and processing feed. The feed contacting step and catalyst treatment step can be carried out simultaneously by cofeeding the feed and the polar compound. Thus, the present invention permits reactivation of catalysts while the alkylation process is still operating, and eliminates the need for costly shutdown to effect catalyst regeneration.
The present invention can also utilize polar compounds as xe2x80x9coff-linexe2x80x9d reactivation agents when it is desired to shut the unit down and reactivate the catalyst in situ, i.e., while the catalyst is in the reactor. Thus the feed contacting step and catalyst treatment step can be carried out serially, i.e., the feed contacting step and catalyst treatment step are carried out one after the other, non-simultaneously.
The polar compound to effect catalyst reactivation should be added in an amount sufficient to displace catalyst poison under liquid phase alkylation conditions. During simultaneous cofeeding of reactants and polar compound, the polar compound should be added in amounts of at least 0.01 ppm, preferably 0.1 ppm, say 0.1 to 100 ppm of total feed to the alkylation process. During serial operation, polar compound should be added in amounts of at least 0.01 wt. % of total catalyst weight, preferably at least 0.05 wt. %, e.g., 0.05 to 5 wt. % of total catalyst weight. Such an amount can be added over periods ranging from 0.1 to 72 hours, preferably from 0.2 to 24 hours.
All of the patents noted above are incorporated herein by reference in their entirety.

Process for liquid phase aromatics alkylation comprising in-situ catalyst reactivation with polar compounds

Abstract: i) contacting a feed containing alkylatable aromatic, e.g., benzene, under liquid phase alkylating conditions with an alkylating agent, e.g., ethylene, in the presence of an alkylation catalyst comprising a porous crystalline material, e.g., MCM-22, to provide an alkylated aromatic product during which contacting said catalyst becomes at least partially deactivated by sorbing catalyst poisons present in said feed;

Abstract: ii) treating said at least partially deactivated catalyst in situ by contacting with at least one polar compound, e.g., water or acetic acid, having a dipole moment of at least 0.05 Debyes under conditions of temperature and pressure employed in said liquid phase alkylating conditions which are sufficient to at least partially desorb said catalyst poison from said catalyst; and


A non-silicone, form-in-place gasket produced using automated placement followed by curing of a pattern of an extrudable thixotropic material comprising a liquid polyolefin oligomer a reactive diluent a thixotropic filler and a curative. The form-in-place gasket, after curing, has a compression set of about 7% to about 20%, a level of outgassing components of about 10 xcexcg/g to about 45 xcexcg/g and a Shore A hardness from about 45 to about 65.

1. Field of the Invention
The invention relates to gasket materials used for attaching and sealing covers to enclosures. More particularly, the invention relates to form-in-place gaskets, applied to surfaces of containers for sensitive electronic components. Gasket compositions, according to the present invention, are substantially free from deleterious effects of outgassing and ion contamination.
2. Discussion of the Related Art
Conventional methods for gasket manufacture substantially comprise either die-cutting the gasket out of an elastomeric sheet material, or shaping the gasket by injection-molding of an elastomeric mix or the like. Both these methods require expensive tools such as punches and molds, which add cost to the final product. Newer manufacturing methods deposit a bead or thread of a fluid elastomer from a nozzle onto a substantially planar surface. The pattern adopted by the fluid elastomer thread may be controlled using automated equipment, programmed according to selected coordinates to provide a gasket having a desired shape. After forming to a desired gasket pattern, the fluid elastomer thread may be cured, either at ambient temperature or in an oven, with or without accelerators or other additives.
Fluid elastomer compositions, suitable for form-in-place gaskets, include condensation-reaction curing silicone rubbers and addition-reaction curing silicone rubbers. These compositions have viscosities suitable for application using robot applicators which apply a sealing bead of material to at least one surface of at least one of the joining members. According to U.S. Pat. Nos. 4,643,863 and 4,643,864, fluid elastomers, suitable for controlled automated dispensing from a nozzle, include polyurethane, monocomponent or bicomponent silicone, and even polyvinylchloride compositions. An apparent disadvantage, of previously cited, nozzle-dispensed materials, is the need to provide support for the extruded bead of fluid elastomer. This problem was overcome with the development of a silicone rubber composition described in U.S. Pat. No. 5,684,110. Upon application of this silicone rubber composition to a substrate, it exhibits excellent resistance to distortion, under pressure, immediately after being applied and while curing to a highly pressure-resistant and strongly adhering silicone rubber gasket. In this case the silicone gasket composition cures via a combination of condensation-reaction curing and addition-reaction curing, the latter catalyzed with a platinum catalyst. The Patent (U.S. Pat. No. 5,684,110) further reveals that the silicone rubber composition is a two-part formulation requiring a first silicone containing fluid to be added to a second fluid, comprising a silicone and catalyst, with intimate mixing immediately before robot application.
Another two-part silicone formulation, disclosed in U.S. Pat. No. 5,679,734, relates to compositions, which can be crosslinked by hydrosilylation at room temperature, in the presence of a metal compound catalyst. Crosslinking proceeds via an addition reaction involving hydrogen substituents and alkenyl radicals of the vinyl type. Storage stability is achieved by providing a system having at least two component parts. Upon mixing the component parts, a gel forms between a few minutes to 1 hour 30 minutes depending on the cure temperature which may be between room temperature and 180xc2x0 C.
Silicone materials, of the type previously discussed, meet the needs of a variety of applications including use as sealants, shock-absorbing elements, anti-vibration elements and gaskets in electrical and electronic components. One special and particularly interesting form of gasket is the electromagnetic interference (EMI) shielding gasket. EMI shielding gaskets perform the dual protective function of sealing cover assemblies and enclosures to prevent ingress of contaminants and, at the same time, exerting control over interference from electromagnetic energy. Protective sealants, effective in controlling EMI, may be used as gaskets that typically require a flexible, elastomeric, rubber-like matrix filled with a conductive material that is readily distributed throughout the flexible matrix. The conductive material may take the form of particles, flakes or fibers having intrinsic conductivity, or electrically conductive surface coatings. U.S. Pat. No. 5,641,438 discloses conductive sealant materials for application using form-in-place methods, which accomplish accurate positioning of the sealant bead. Similar compositions and methods are revealed in related published European applications, EP 0643551 and EP 0653552. Each reference describes EMI shielding sealant compositions, consisting of two or more components, requiring storage in separate containers and mixing just before applying and curing the gasket in place.
The previous discussion addressed primarily silicone-based fluid elastomer compositions suitable for use in a variety of applications including form-in-place gaskets. One disadvantage of using silicone elastomers is the presence of relatively low molecular weight siloxane contaminants in cured materials. Such contaminants tend to deposit on surfaces of an electronic assembly with the potential to cause device failure. Problems of contamination may be avoided using fluoroelastomer gaskets. Since they are subject to formation by injection molding, fluoroelastomer gaskets represent a costly approach for preventing contamination. Difficulties associated with non-fluid gaskets and fluid silicone elastomers, for gasket formation, suggests the need for a non-silicone, dispensable, fluid material for contaminant-free, low cost, sealing of containers of electronic components and associated devices.
The present invention provides fluid elastomer compositions having reactive functionality, preferably in the form of epoxy groups. Dispensable elastomer compositions provide dispensable, form-in-place gaskets designed for containers such as enclosures for hard disk drives. For accuracy of dimensions, placement and final positioning, various patterns of form-in-place gaskets, according to the present invention, require the dispensing of elastomer compositions using automated liquid dispensing followed by in-place curing to soft, resilient gaskets, exhibiting moisture resistance, minimal compression set, and adhesion to selected substrates. The elastomer composition, before curing, should have sufficiently low viscosity to be readily dispensed. Curable compositions may be prepared as one-part formulations that include a curative or as two-part formulations requiring addition of a curative before curing. Regardless of the components included in an uncured gasket composition, the curing process may be initiated thermally, photonically, a combination of both, and/or, in the case of two part formulations, by simply combining the parts under ambient conditions. Preferably uncured formulations provide non-slumping dispensed beads of gasket material having good dimensional stability, as applied, with essentially no change in shape or position during and after curing.
For electronics grade cleanliness, properties of these elastomer compositions, after curing, include low outgassing and low extractable ionics. These properties surpass those of commercially available, silicone-based form-in-place gaskets which, as previously discussed, typically contain low molecular weight siloxanes that can damage electronic components following contamination of device surfaces. Since this invention utilizes a flexible epoxy based material, possible damage due to siloxane contamination is avoided.
More particularly the present invention provides a non-silicone composition for form-in-place gaskets comprising a liquid polyolefin oligomer, a reactive diluent, a thixotropic filler, and a curative. The non-silicone composition, after curing, has a compression set of about 7% to about 20%, preferably about 10% to about 15%, a level of outgassing components of about 10 xcexcg/g to about 45 xcexcg/g and a Shore A hardness from about 45 to about 65 preferably from about 50 to about 60.
Non-silicone compositions according to the present invention may be dispensed using a variety of methods and equipment including commercially available fluid dispensing equipment. Gasket dispensing and placement may involve a variety of different methods. Speedline Technologies Inc. offers suitable commercial liquid dispensing equipment under the tradename CAMALOT, e.g. CAMALOT 1414 and CAMALOT 1818.
The present invention further includes a non-silicone, form-in-place gasket produced using automated placement, followed by curing, of a pattern of an extrudable thixotropic non-silicone composition. The extrudable composition comprises, a liquid polyolefin oligomer, a reactive diluent, a thixotropic filler, and a curative. The form-in-place gasket, after curing, has a compression set from about 7% to about 20%, preferably from about 10% to about 15%, a level of outgassing components from about 10 xcexcg/g to about 45 xcexcg/g, and a Shore A hardness between about 45 and about 65, preferably between about 50 and 60.
The term xe2x80x9cdispensablexe2x80x9d means that low viscosity elastomer compositions may be conveniently extruded from tubes, such as needles, attached to pressurized reservoirs, to provide small diameter (xcx9c1 mm) beads of sealant following the contours of a required gasket pattern.
The combination of terms xe2x80x9cone-part, cure-in-placexe2x80x9d refers to fluid elastomer compositions containing a curative that responds to heat or actinic radiation to promote crosslinking and curing of the one-part formulation, once dispensed onto its substrate.
The term xe2x80x9cnon-slumpingxe2x80x9d refers to the properties of an elastomer composition, including yield stress and viscosity that deter sagging or slumping during dispensing and curing. A non-slumping material is important for maintaining cross-sectional profile stability of a dispensed bead, of elastomer composition, before and during curing.
The term xe2x80x9caspect ratioxe2x80x9d indicates the slumping tendency or dimensional stability of a gasket composition according to the present invention by measuring the height and width of a cross-section through a cured, extruded bead of the composition. A cross sectional height divided by the corresponding width provides a value of xe2x80x9caspect ratioxe2x80x9d of a cured gasket bead.
The term xe2x80x9chydrophobicxe2x80x9d relates to the water repellency of elastomer compositions, which provide sealing gaskets with moisture barrier properties.
The term xe2x80x9celectronics-grade cleanlinessxe2x80x9d means that cured elastomeric compositions for form-in-place gaskets satisfy electronics industry requirements such as low levels of outgassing and extractable ionic contaminants. Experimental investigation by dynamic headspace gas chromatography (GC)/mass spectrometry shows a total outgassing of about 10 xcexcg/g to about 45xcexcg/g for cured elastomer compositions, according to the present invention, when held at 85xc2x0 C. for three hours.
The term xe2x80x9cflowabilityxe2x80x9d of uncured gasket material, as used herein, refers to the amount of material passing through an opening of fixed diameter under a fixed pressure for a selected time interval. xe2x80x9cFlowabilityxe2x80x9d is expressed as the weight of material exiting through the orifice during the time that pressure was applied.
The term xe2x80x9coutgassingxe2x80x9d relates to the collection of volatile components produced by evacuation of cured non-silicone gasket compositions according to the present invention. Established criteria require microgram (xcexcg) quantities of volatile components for each ram (g)of composition evaluated.
Dispensable elastomeric formulations, according to the present invention, provide form-in-place gaskets designed for containers such as enclosures for hard disk drives. Suitable elastomeric formulations may be applied to such containers using automated liquid dispensing followed by in-place curing to soft, resilient gaskets, exhibiting moisture resistance, minimal compression set, and adhesion to selected substrates. The primary use for resilient gaskets, after curing is to provide sealed interfaces between surfaces of protective containers. An effective seal prevents access of contaminants to protected structures.
The present invention provides epoxy-functional, form-in-place gasket formulations that overcome the disadvantages associated with commercially available silicone-based materials. Cured silicone- containing gaskets have low molecular weight siloxane contaminants that may deposit on device surfaces with resultant damage to sensitive electronic components. The cured flexible epoxy-based gaskets of the present invention are free of siloxane-containing species, being formed from dispensable fluid formulations comprising linear hydrocarbon oligomers having epoxy functionality for crosslinking using anhydride curing agents. Selection of liquid oligomers, also referred to herein as prepolymers, as a component of a sealing gasket, requires inherent properties of hydrophobicity and low ionic content. The reactive functionality, e.g. epoxy substituents, preferably promote crosslinking of gasket formulations by heat activation.
When used for sealing containers of electronic components, the cured, form-in-place gasket becomes compressed under the mechanical force applied to close the container. Design criteria control the allowable closure force and gasket hardness for secure seating of one part of the container relative to another. Cured gasket materials have Shore A durometer values from about 45 to about 65, preferably from about 50 to about 60 to enable full closure with a reasonable amount of force. To accommodate the possible use of electronic assemblies in differing climatic regions, cured gaskets, according to the present invention, maintain their elastomeric properties over a temperature range extending from about xe2x88x9240xc2x0 C. to about 100xc2x0 C. The possibility of re-entry into the container, for re-work, requires that the cured gasket has a low permanent compression set. Suitable form-in-place gasket formulations exist in a range, of permanent compression set, from about 7% to about 20% of the original deflection, measured by ASTM D395B. Low values of permanent compression set assure the resiliency of the gasket material for maintaining an adequate seal during the lifetime of the container and facilitating gasket reuse if the container is reopened for rework of protected electronic assemblies.
While mechanical force increases the contact between a cured gasket and surfaces of the container, the physical properties of the gasket itself also prevent access of environmental contaminants, such as moisture vapor, into the container. A key property is hydrophobicity that may be attributed to the use of a liquid prepolymer that includes an epoxidized polyolefin backbone. Hydrophobic liquid prepolymers impart hydrolytic stability and minimal moisture absorption to cured gaskets. In addition to repelling external contaminants, the gasket itself should not represent a potential source of contamination. This requires that the hydrophobic gasket material shows remarkable stability and freedom from volatile components that could escape, via outgassing, to deposit on electronic components in the container with resultant potential for corrosion or other damaging conditions. Stringent cleanliness is a requirement of electronics manufacturers, particularly in the hard disk drive industry. Therefore, the cured gasket should contain minimal amounts of impurities and volatile components. Gasket formulations typically require cure times of about two hours at 160xc2x0 C. Additional reduction of outgassing can occur via a post-bake process after curing.
For optimum performance in a designated application, form-in-place gaskets preferably possess a balance of properties. Uncured gasket formulations should be liquid with a low enough viscosity for easy dispensing, yet remain non-slumping, after dispensing, to maintain the shape and dimensions of a selected gasket pattern. After curing, softness properties, low compression set, and minimal outgassing are required. Property adjustment in the uncured and cured state is a function of reactants, relative stoichiometry of reactants, concentration and type of filler and curing conditions. Low filler concentrations favor lower viscosity formulations for improved dispensability. Unfortunately, formulations with insufficient filler amounts typically result in gasket beads that slump excessively after being dispensed. Softer materials can also be obtained by making the matrix resin softer. However, softening the matrix resin material usually leads to some sacrifice in compression set. Each property may vary depending upon material selection and stoichiometry, filler type and concentration, and conditions used for crosslinking a formulation to yield the cured gasket. The balance of properties will vary in response to the specific requirements of a given application for form-in-place gaskets. Custom formulating becomes an essential task for satisfying the many applications for gasket formulations according to the present invention.
Considering the need to provide custom, application-specific formulations, the focus of the present invention is form-in-place gaskets as seals for containers of hard disk drive assemblies. The properties of gasket formulations, suitable for use with hard disk drive containers, include good sag resistance of uncured material after being dispensed, low compression set, ready compressibility with normal closure forces, substantial freedom from contaminants, and good adhesion to target surfaces. Table 1 shows typical properties for preferred gasket formulations used with hard disk drive containers. The formulations adhere well to aluminum and stainless steel, while exhibiting moisture resistance, with low moisture vapor transport, as required for an environmental seal.
Suitable liquid oligomers, include substantially linear polyolefins such as L 207, a commercially available epoxidized Kraton from Shell Chemical Company. This dual functional polyolefin consists of a poly(ethylene/butylene) backbone with hydroxyl functionality at one end and a multiple epoxidized polyisoprene functionality at the other end. The flexible aliphatic portion imparts low temperature flexibility as well as hydrophobicity. The multiple-epoxidized end allows for epoxy-type curing and network formation.
Preferred curing agents, according to the present invention, are liquid anhydrides (available from Lonza Inc.), such as AC39-polypropylene glycol di(dodecenyl succinate); dodecenyl succinic anhydride (DDSA); methyl tetrahydro-phthalic anhydride (MTHPA); methyl-5-norbornene-2,3,-dicarboxylic anhydride (AC methyl); methylhexahydro-phthalic anhydride (MHHPA) and combinations thereof. Liquid maleic anhydride grafted polybutadiene (available from Ricon Chemicals) may also be used as a curing agent.
Addition of a reactive diluent, such as PRIPOL 2033, a polyolefin diol, reduces viscosity of the overall formulation and also maintains performance properties by reacting into the network structure. Other reactive diluents include hydroxyl functional compounds, such as hydroxyl terminated poly(ethylene/butylene), available as L-2203 from Shell Chemical; hydroxyl terminated polybutadiene resin available as R-20 LM from Elf Atochem; low viscosity epoxy functional compounds, such as diglycidyl ether of 1,4-butanediol available as HELOXY MODIFIER 67 from Shell Chemical; and diglycidyl ether of neopentyl glycol available as HELOXY MODIFIER 68 from Shell Chemical.
Preferably, non-slumping form-in-place gasket formulations include filler particles known to produce thixotropic materials. After dispensing in a pre-determined pattern, these filled formulations maintain their profile and dimensions through thermal curing. Suitable fillers according to the present invention include clays, a variety of forms of silica, depending upon particle size and surface treatment, and organic fillers such as cellulose, castor-oil wax, and polyamide-containing fillers. Particulate fillers, imparting thixotropy, include fumed silica, clay, and carbon black. Suitable fumed silicas include AEROSIL R812; and AEROSIL R805 (both available from Degussa); CAB-O-SIL TS 610; and CAB-O-SIL T 5720 (both available from Cabot Corp.). Preferred clays include GARAMITE 1958, available from Southern Clay Products. Carbon blacks, such as COLOUR BLACK FW 18 (Degussa); and PRINTEX 55 also contribute to thixotropy. Fumed silicas generally represent the most preferred fillers although this is somewhat formulation dependent.
Optimum rheological performance occurs with proper dispersion of the filler. Shear conditions, during mixing of form-in-place gasket formulations, approach an optimum state to produce material for uncured gaskets that hold their shape after dispensing. High shear mixing can permanently disrupt the network structure of the thixotropic particles with resultant loss of shape by increased slumping of dispensed gasket beads. A low-shear mixer reduces this problem to a minimum, and is preferred for preparing formulations according to the present invention.
Zinc catalysts have been used successfully to catalyze the anhydride-epoxy cure. Suitable zinc catalysts include zinc ethyl hexanoate (ZnHex), zinc neodecanoate, zinc undecylenate, and zinc stearate (ZnSt).
Details of form-in-place gasket formulations, disclosed herein, are merely exemplary of the invention that may be subject to other variations that also depend upon the introduction of characteristics, such as improved vibration dampening, thermal cycling, low outgassing etc. to liquid polymers having a flexible backbone and terminal reactive functionality. Additional advantages and modifications will readily occur to those skilled in the art. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
L207xe2x80x94Epoxy functional olefin available from Shell Chemical Company. Its structure includes an epoxy functional end group separated from a primary hydroxyl functionality by a poly(ethylene/butylene) backbone. L207 has an epoxy equivalent weight (EEW) of 590 and a hydroxyl equivalent weight of 6,600.
PRIPOL 2033, a dimer diol (Unichema), has an hydroxyl equivalent weight (HEW) of 278.
L-2203 is a hydroxyl functional poly(ethylene/butylene) having a hydroxyl equivalent weight of 1700 as supplied by Shell Chemical Company.
AC-39 is a polypropylene glycol di(dodecenylsuccinate) from Lonza Inc.
DDSA (AEW 266) is dodecenyl succinic anhydride (M.Wt. xe2x80x94350) available from Milliken Chemical.
BYK052 is an organic defoamer from BYK-Chemie USA.
Zinc stearate (ZnSt) is available from Alfa Aesar and Zinc 2-ethylhexanoate is available from Strem Chemicals.
R805 is a hydrophobic treated fumed silica available from Degussa-Huls.
Form-In-Place-Gasket Material Compounding
Raw materials were mixed together in a double planetary vacuum mixer. After mixing was completed, the material was discharged into 30 cc syringes and stored in a freezer at a temperature of xe2x88x9240xc2x0 C. until needed. Prior to using material from a syringe, the frozen material was thawed at room temperature for about two hours.

Form-in-place gasket for electronic applications


A high foaming, light duty, liquid detergent with desirable cleansing properties and mildness to the human skin comprising at least one surfactant selected from the group consisting of water soluble nonionic surfactant, an anionic sulfate surfactants and a sulfonate anionic surfactants, a stably suspended oil containing gelatin beads, a polyacrylate polymeric thickener and water.

The present invention relates to novel light duty liquid cleaning compositions with high foaming properties and having the appearance of suspended beads therein which contains a sulfonate surfactant, an ethoxylated alkyl ether sulfate surfactant, a nonionic surfactant, gelatin beads containing an oil, a crosslinked polyacrylate type polymer, an inorganic magnesium salt, a polyethylene glycol and the balance being water.
Nonionic surfactants are in general chemically inert and stable toward pH change and are therefore well suited for mixing and formulation with other materials. The superior performance of nonionic surfactants on the removal of oily soil is well recognized. Nonionic surfactants are also known to be mild to human skin. However, as a class, nonionic surfactants are known to be low or moderate foamers. Consequently, for detergents which require copious and stable foam, the application of nonionic surfactants is limited. There have been substantial interest and efforts to develop a high foaming detergent with nonionic surfactants as the major ingredient. Yet, little has been achieved.
The prior art is replete with light duty liquid detergent compositions containing nonionic surfactants in combination with anionic and/or betaine surfactants wherein the nonionic detergent is not the major active surfactant, as shown in U.S. Pat. No. 3,658,985 wherein an anionic based shampoo contains a minor amount of a fatty acid alkanolamide. U.S. Pat. No. 3,769,398 discloses a betaine-based shampoo containing minor amounts of nonionic surfactants. This patent states that the low foaming properties of nonionic detergents renders its use in shampoo compositions non-preferred. U.S. Pat. No. 4,329,335 also discloses a shampoo containing a betaine surfactant as the major ingredient and minor amounts of a nonionic surfactant and of a fatty acid mono- or di-ethanolamide. U.S. Pat. No. 4,259,204 discloses a shampoo comprising 0.8-20% by weight of an anionic phosphoric acid ester and one additional surfactant which may be either anionic, amphoteric, or nonionic. U.S. Pat. No. 4,329,334 discloses an anionic-amphoteric based shampoo containing a major amount of anionic surfactant and lesser amounts of a betaine and nonionic surfactants.
U.S. Pat. No. 3,935,129 discloses a liquid cleaning composition based on the alkali metal silicate content and containing five basic ingredients, namely, urea, glycerin, triethanolamine, an anionic detergent and a nonionic detergent. The silicate content determines the amount of anionic and/or nonionic detergent in the liquid cleaning composition. However, the foaming property of these detergent compositions is not discussed therein.
U.S. Pat. No. 4,129,515 discloses a heavy duty liquid detergent for laundering fabrics comprising a mixture of substantially equal amounts of anionic and nonionic surfactants alkanolamines and magnesium salts, and, optionally, zwitterionic surfactants as suds modifiers.
U.S. Pat. No. 4,224,195 discloses an aqueous detergent composition for laundering socks or stockings comprising a specific group of nonionic detergents, namely, an ethylene oxide of a secondary alcohol, a specific group of anionic detergents, namely, a sulfuric ester salt of an ethylene oxide adduct of a secondary alcohol, and an amphoteric surfactant which may be a betaine, wherein either the anionic or nonionic surfactant may be the major ingredient. The specific class of anionics utilized in this patent is the very same group of anionic detergents expressly excluded in present invention in order to eliminate the alkanol ethoxylate sulfation process and the potential dioxane toxicity problem. Furthermore, this patent finds heavily foaming detergents undesirable for the purpose of washing socks.
The prior art also discloses detergent compositions containing all nonionic surfactants as shown in U.S. Pat. Nos. 4,154,706 and 4,329,336 wherein the shampoo compositions contain a plurality of particular nonionic surfactants in order to effect desirable foaming and detersive properties despite the fact that nonionic surfactants are usually deficient in such properties.
U.S. Pat. No. 4,013,787 discloses a piperazine based polymer in conditioning and shampoo compositions which may contain all nonionic surfactant or all anionic surfactant.
U.S. Pat. No. 4,450,091 discloses high viscosity shampoo compositions containing a blend of an amphoteric betaine surfactant, a polyoxybutylene polyoxyethylene nonionic detergent, an anionic surfactant, a fatty acid alkanolamide and a polyoxyalkylene glycol fatty ester. But, none of the exemplified compositions contains an active ingredient mixture wherein the nonionic detergent is present in major proportion, probably due to the low foaming properties of the polyoxybutylene polyoxyethylene nonionic detergent.
U.S. Pat. No. 4,595,526 describes a composition comprising a nonionic surfactant, a betaine surfactant, an anionic surfactant and a C12-C14 fatty acid monoethanolamide foam stabilizer.
U.S. Pat. No. 5,866,529 teaches a light duty liquid cleaning composition containing gelatin beads and a Laponite clay, wherein this patent specifically excludes polyacrylic acid polymeric thickeners.
However, none of the above-cited patents discloses a high foaming, liquid detergent composition containing a nonionic surfactant, two high foaming anionic surfactants, an inorganic magnesium salt, polyethylene glycol, an oil containing gelatin bead, a crosslinked polyacrylate polymer and water wherein the composition does not contain any polymeric thickeners such as cellulosics or xanthan gum or a Laponite clay.
It has now been found that a high foaming liquid light duty liquid cleaning composition has desirable cleaning properties, mildness to the human skin and improved aesthetics. Accordingly, one object of the invention is to provide novel, high foaming, light duty liquid detergent compositions containing a nonionic surfactant, suspended oil containing gelatin beads and a polyacrylate type polymeric thickener.
Another object of this invention is to provide novel, liquid detergent compositions containing a nonionic surfactant, two anionic surfactants, an inorganic magnesium salt, a polyacrylate type polymer, suspended oil containing gelatin beads and water, wherein the composition does not contain any builder salts, polymeric thickeners such as cellulosics or xanthan gum, alkyl glycine surfactant, Laponite clay, cyclic imidinium surfactant, N-polyvinyl pyrrolidone homopolymer, copolymer of N-polyvinyl pyrrolidone and dimethyl-aminoethyl methacrylate, or abrasives.
Still another object of this invention is to provide a novel, liquid detergent with desirable high foaming and cleaning properties which is mild to the human skin.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the Instrumentalities and combinations particularly pointed out In the appended claims.
To achieve the foregoing and other objects and In accordance with the purpose of the present invention, as embodied and broadly described herein the novel, high foaming, light duty liquid cleaning compositions of this invention comprises at least one surfactant selected from the group consisting of water soluble, ethoxylated, nonionic surfactants and anionic surfactants such as water soluble organic sulfates and organic sulfonates, a polymeric thickener, suspended oil containing gelatin beads and water wherein the composition does not contain any formate, HETDA, abrasives, builder salts, polymeric thickeners such as cellulosics or xanthan gum, a Laponite clay, fatty acids, alkyl glycine surfactant or cyclic imidinium surfactant.
The present Invention relates to a light duty liquid cleaning composition which comprises approximately by weight:
(a) 1% to 45%, more preferably 2% to 40% of at least one surfactant selected from the group consisting of nonionic surfactants, sulfonate surfactants and sulfate surfactants and mixtures thereof;
(b) 0.5% to 5%, more preferably 2.4% to 4% of a polyacrylate type polymeric thickener;
(c) 0.01% to 2% of an alkali metal hydroxide, preferably potassium hydroxide and/or triethanol amine;
(d) 0.05% to 4%, more preferably 0.1% to 2% of oil containing gelatin beads which are stably suspended within the liquid composition as discrete particles; and
(e) the balance being water, wherein the composition has a pH of about 3.0 to 7.5, preferably 5.5 to 7, wherein the composition does not contain any polymeric to cellulosic thickeners, xanthan gum thickeners or Laponite clay.
The water soluble nonionic surfactants utilized In this invention at a concentration of 0 to 40%, preferably 2% to 35% by weight are commercially well known and include the primary aliphatic alcohol ethoxylates, secondary aliphatic alcohol ethoxylates, alkylphenol ethoxylates and ethylene-oxide-propylene oxide condensates on primary alkanols, such a Plurafacs (BASF) and condensates of ethylene oxide with sorbitan fatty acid esters such as the Tweens (ICI). The nonionic synthetic organic surfactants generally are the condensation products of an organic aliphatic or alkyl aromatic hydrophobic compound and hydrophilic ethylene oxide groups. Practically any hydrophobic compound having a carboxy, hydroxy, amido, or amino group with a free hydrogen attached to the nitrogen can be condensed with ethylene oxide or with the polyhydration product thereof, polyethylene glycol, to form a water-soluble nonionic detergent. Further, the length of the polyethenoxy chain can be adjusted to achieve the desired balance between the hydrophobic and hydrophilic elements.
The nonionic surfactant class includes the condensation products of a higher alcohol (e.g., an alkanol containing about 8 to 18 carbon atoms in a straight or branched chain configuration) condensed with about 5 to 30 moles of ethylene oxide, for example, lauryl or myristyl alcohol condensed with about 16 moles of ethylene oxide (EO), tridecanol condensed with about 6 to moles of EO, myristyl alcohol condensed with about 10 moles of EO per mole of myristyl alcohol, the condensation product of EO with a cut of coconut fatty alcohol containing a mixture of fatty alcohols with alkyl chains varying from 10 to about 14 carbon atoms in length and wherein the condensate contains either about 6 moles of EO per mole of total alcohol or about 9 moles of EO per mole of alcohol and tallow alcohol ethoxylates containing 6 EO to 11 EO per mole of alcohol.
A preferred group of the foregoing nonionic surfactants are the Neodol ethoxylates (Shell Co.), which are higher aliphatic, primary alcohol containing about 9-15 carbon atoms, such as C9-C11 alkanol condensed with 8 moles of ethylene oxide (Neodol 91-8), C12-13 alkanol condensed with 6.5 moles ethylene oxide (Neodol 23-6.5), C12-15 alkanol condensed with 12 moles ethylene oxide (Neodol 25-12), C14-15 alkanol condensed with 13 moles ethylene oxide (Neodol 45-13), and the like. Such ethoxamers have an HLB (hydrophobic lipophilic balance) value of about 8-15 and give good O/W emulsification, whereas ethoxamers with HLB values below 8 contain less than 5 ethyleneoxide groups and tend to be poor emulsifiers and poor detergents.
Additional satisfactory water soluble alcohol ethylene oxide condensates are the condensation products of a secondary aliphatic alcohol containing 8 to 18 carbon atoms in a straight or branched chain configuration condensed with 5 to 30 moles of ethylene oxide. Examples of commercially available nonionic detergents of the foregoing type are C11-C15 secondary alkanol condensed with either 9 EO (Tergitol 15-S-9) or 12 EO (Tergitol 15-S-12) marketed by Union Carbide.
Other suitable nonionic surfactants include the polyethylene oxide condensates of one mole of alkyl phenol containing from about 8 to 18 carbon atoms in a straight- or branched chain alkyl group with about 5 to 30 moles of ethylene oxide. Specific examples of alkyl phenol ethoxylates include nonyl phenol condensed with about 9.5 moles of EO per mole of nonyl phenol, dinonyl phenol condensed with about 12 moles of EO per mole of dinonyl phenol, dinonyl phenol condensed with about 15 moles of EO per mole of phenol and di-isoctylphenol condensed with about 15 moles of EO per mole of phenol. Commercially available nonionic surfactants of this type include Igepal CO-630 (nonyl phenol ethoxylate) marketed by GAF Corporation.
Condensates of 2 to 30 moles of ethylene oxide with sorbitan mono- and tri-C10-C20 alkanoic acid esters having a HLB of 8 to 15 also may be employed as the nonionic detergent Ingredient in the described shampoo. These surfactants are well known and are available from Imperial Chemical Industries under the Tween trade name. Suitable surfactants include polyoxyethylene (4) sorbitan monolaurate, polyoxyethylene (4) sorbitan monostearate, polyoxyethylene (20) sorbitan trioleate and polyoxyethylene (20) sorbitan tristearate.
The anionic sulfonate surfactants used at a concentration of 0 to 40 wt. %, more preferably 2 wt. % to 36 wt. %, are water soluble such as triethanolamine and include the sodium, potassium, ammonium and ethanolammonium salts of linear C8-C16 alkyl benzene sulfonates and C10-C20 paraffin sulfonates, wherein the preferred salt is potassium.
The alkyl ether sulfate surfactants used at a concentration of 0 to 10 wt. %, more preferably 0.25 wt. % to 8 wt. % in the Instant compositions have the structure
wherein n is about 1 to about 22 more preferably 1 to 3 and R is an alkyl group having about 8 to about 18 carbon atoms, more preferably 12 to 15 and natural cuts, for example, C12-14 or C12-16 and M Is an ammonium cation or a metal cation, most preferably sodium.
The ethoxylated alkyl ether sulfate may be made by sulfating the condensation product of ethylene oxide and C8-10 alkanol, and neutralizing the resultant product. The ethoxylated alkyl ether sulfates differ from one another in the number of carbon atoms in the alcohols and in the number of moles of ethylene oxide reacted with one mole of such alcohol. Preferred ethoxylated alkyl ether polyethenoxy sulfates contain 12 to 15 carbon atoms in the alcohols and in the alkyl groups thereof, e.g. sodium myristyl (3 EO) sulfate.
Ethoxylated alkylphenyl ether sulfates containing from 2 to 6 moles of ethylene oxide in the molecule are also suitable for use in the invention compositions. These detergents can be prepared by reacting an alkyl phenol with 2 to 6 moles of ethylene oxide and sulfating and neutralizing the resultant ethoxylated alkylphenol.
The instant composition can optionally contain 0 to 8 wt. %, more preferably 0.1 wt. % to 6 wt. % of a polyethylene glycol having a molecular weight of 100 to 10,000.
The oil containing gelatin beads which are stably suspended as discrete particles in the instant cleaning composition is composed typically of gelatin and arabeo gum. The composition microencapsulated within the gelatin bead comprises approximately by weight 30 to 50% of a mineral oil, 30 to 50% of phytocancentrol algas, 10 to 30% of silicone oil and 1 to 3% of a silver pigment. A typical gelated bead is HC774 manufactured by Hallcrest of Dorset, England.
These particles have a density generally very close to that of water, 1 gm/cm3, for case of suspension and stability. A preferred density range is about 0.92 to about 1.05 gm/cm3 more preferred, about 0.97 to about 1.02 gm/cm3. A further desired attribute of the particle is that is has optimal visual impact to the composition user. Generally the size of the particle can vary from about 200 to about 2500 micron.
Preferably the particle size is about 400 to about 2000 micron and even more preferably about 800 to about 1800 micron and most preferably about 1000 to about 1500 microns. The material comprising the particle should be compatible with water.
Generally such materials can include gelatins, arabic gums, collagens, polypeptides from vegetable or animal origin, alginates, polyamides, glycosamino glycans, mucopolysaccharides, ethylcellulose and the like. Through coacervation, multicoating protein deposition, or reticulation technologies microcapsules can be formed which enclose the oil.
When applied to the surface being cleaned during normal cleansing procedures, these particles are abraded, released and deposit their contents on the surface being cleaned. Examples of xe2x80x9coilyxe2x80x9d materials which can be within the microcapsule are vitamins, provitamins; mineral oils, vegetable oils, emolients or animal extracts and the like. These oil bearing particles are available from Hallcrest Liquid Crystal Technology Ltd. a UK company having offices in Glenview, III, U.S.A. and from LIPO Chemicals. Other materisl which can be employed are oil Impregnated particles available as Elespheres from Laboratories Serobiologiques, France. Also collagen spheres and glucose amino glycans xe2x80x9cGAGxe2x80x9d spheres from Coletica (France) called Collaspheres or Thalaspheres. The preferred particles are the microcapsules from Hallcrest, most preferably the green, silver and iridescent colors.
The magnesium inorganic salt which can optionally be used in the Instant composition at a concentration of 0 to 8 wt. %, more preferably 0.25 wt. % to 5 wt. % is selected from the group consisting of magnesium chloride, magnesium oxide and magnesium sulfate and mixture thereof, wherein the preferred magnesium inorganic salt is magnesium sulfate heptahydrate.
The polyacrylate type polymeric thickener is Carbopol Aqua(trademark) 30 manufactured by B.F. Goodrich Company. Carbopol Aqua(trademark) 30 is a non-associate lightly crosslinked (0.03 to 3 wt. % of crosslinker) acrylate copolymer consisting of a mixture of a copolymer of methacrylic acid and a C1-C4 alkyl ester of the methacrylic acid and a copolymer of acrylic acid and a C1-C4 alkyl ester of the acrylic acid, wherein the weight ratio of the methacrylic acid copolymer to the acrylic acid copolymer is about 2:1 to 1:2 and the molecular weight of the Carbopol Aqua(trademark) 30 is about 500,000 to 1,500,000. The use of the Carbopol Aqua(trademark) 30 in the instant composition provides the formation of viscoelastic properties while maintaining acceptable flowability thereby permitting the stable suspension of the gelation beads as discrete particles.
Gxe2x80x2 and Gxe2x80x3 values which are obtained with Carbopol Aqua(trademark) 30 cannot be expressed independently of the composition of the liquid base. The profiles of these rheological parameters are given in examples 1-B, 1-A and 1-C for increasing levels (i.e. 2.0, 2.5 and 3.0% respectively) of Carbopol Aqua(trademark) 30 incorporated in the same surfactant base. In these conditions, Gxe2x80x2 varies at 25xc2x0 C. from 10 to 63 Pa and Gxe2x80x3 varies from 14 to 43 Pa (for a frequency of 1 Hertz and a strain of 1%).
In addition to the previously mentioned essential and optional constituents of the light duty liquid detergent, one may also employ normal and conventional adjuvants, provided they do not adversely affect the properties of the detergent. Thus, there may be used various coloring agents and perfumes; sequestering agents such as ethylene diamine tetraacetates; pearlescing agents and opacifiers; pH modifiers; etc. The proportion of such adjuvant materials, in total will normally not exceed 15% of weight of the detergent composition, and the percentages of most of such individual components will be about 0.1 to 5% by weight and preferably less than about 2% by weight. Sodium bisulfite can be used as a color stabilizer at a concentration of about 0.01 to 0.2 wt. %. Typical preservatives are dibromodicyano-butane, citric acid, benzylic alcohol and poly (hexamethylene-biguamide) hydrochloride and mixtures thereof. Other ingredients can be added to the compositions at concentrations of about 0.1 to 4.0 wt. percent are perfumes, preservatives, color stabilizers, sodium bisulfite, ETDA, and proteins such as lexine protein.
The instant composition can optionally contain 0 to 5 wt. %, more preferably 0.1 wt. % to 3 wt. % of a proton donating agent, wherein the proton donating agent is selected from the group consisting of inorganic acids such as hydrochloric acid or phosphoric acid and hydroxy containing organic acids such as lactic acid, citric acid, salicylic acid and ortho hydroxy benzoic acid and mixtures thereof.
The instant compositions can contain about 0 to about 14 wt. percent, more preferably 0.5 to 10 wt. percent of an alkyl polysaccharide surfactant. The alkyl polysaccharides surfactants, which are used in conjunction with the aforementioned surfactant have a hydrophobic group containing from about 8 to about 20 carbon atoms, preferably from about 10 to about 16 carbon atoms, most preferably from about 12 to about 14 carbon atoms, and polysaccharide hydrophilic group containing from about 1.5 to about 10, preferably from about 1.5 to about 4, most preferably from about 1.6 to about 2.7 saccharide units (e.g., galactoside, glucoside, fructoside, glucosyl, fructosyl; and/or galactosyl units). Mixtures of saccharide moieties may be used in the alkyl polysaccharide surfactants. The number x indicates the number of saccharide units in a particular alkyl polysaccharide surfactant. For a particular alkyl polysaccharide molecule x can only assume integral values. In any physical sample of alkyl polysaccharide surfactants there will be in general molecules having different x values. The physical sample can be characterized by the average value of x and this average value can assume non-integral values. In this specification the values of x are to be understood to be average values. The hydrophobic group (R) can be attached at the 2-, 3-, or 4-positions rather than at the 1-position, (thus giving e.g. a glucosyl or galactosyl as opposed to a glucoside or galactoside). However, attachment through the 1-position, i.e., glucosides, galactoside, fructosides, etc., is preferred. In the preferred product the additional saccharide units are predominately attached to the previous saccharide unit""s 2-position. Attachment through the 3-, 4-, and 6-positions can also occur. Optionally and less desirably there can be a polyalkoxide chain joining the hydrophobic moiety (R) and the polysaccharlde chain. The preferred alkoxide moiety is ethoxide.
Typical hydrophobic groups include alkyl groups, either saturated or unsaturated, branched or unbranched containing from about 8 to about 20, preferably from about 10 to about 18 carbon atoms. Preferably, the alkyl group is a straight chain saturated alkyl group. The alkyl group can contain up to 3 hydroxy groups and/or the polyalkoxide chain can contain up to about 30, preferably less than about 10, alkoxide moieties.
Suitable alkyl polysaccharides are decyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, and octadecyl, di-, tri-, tetra-, penta-, and hexaglucosides, galactosides, lactosides, fructosides, fructosyls, lactosyls, glucosyls and/or galactosyls and mixtures thereof.
The alkyl monosaccharides are relatively less soluble in water than the higher alkyl polysaccharides. When used in admixture with alkyl polysaccharides, the alkyl monosaccharides are solubilized to some extent. The use of alkyl monosaccharides in admixture with alkyl polysaccharides is a preferred mode of carrying out the invention. Suitable mixtures include coconut alkyl, di-, tri-, tetra-, and pentaglucosides and tallow alkyl tetra-, penta-, and hexaglucosides.
The preferred alkyl polysaccharides are alkyl polyglucosides having the formula
R2O(CnH2nO)r(Z)x
wherein Z is derived from glucose, R is a hydrophobic group selected from the group consisting of alkyl, alkylphenyl, hydroxyalkylphenyl, and mixtures thereof in which said alkyl groups contain from about 10 to about 18, preferably from about 12 to about 14 carbon atoms; n is 2 or 3 preferably 2, r is from 0 to 10, preferable 0; and x is from 1.5 to 8, preferably from 1.5 to 4, most preferably from 1.6 to 2.7. To prepare these compounds a long chain alcohol (R2OH) can be reacted with glucose, in the presence of an acid catalyst to form the desired glucoside. Alternatively the alkyl polyglucosides can be prepared by a two step procedure in which a short chain alcohol (R1OH) can be reacted with glucose, in the presence of an acid catalyst to form the desired glucoside. Alternatively the alkyl polyglucosides can be prepared by a two step procedure in which a short chain alcohol (C1-6) is reacted with glucose or a polyglucoside (x=2 to 4) to yield a short chain alkyl glucoside (x=1 to 4) which can in turn be reacted with a longer chain alcohol (R2OH) to displace the short chain alcohol and obtain the desired alkyl polyglucoside. If this two step procedure is used, the short chain alkylglucoside content of the final alkyl polyglucoside material should be less than 50%, preferably less than 10%, more preferably less than about 5%, most preferably 0% of the alkyl polyglucoside.
The amount of unreacted alcohol (the free fatty alcohol content) in the desired alkyl polysaccharide surfactant is preferably less than about 2%, more preferably less than about 0.5% by weight of the total of the alkyl polysaccharide. For some uses it is desirable to have the alkyl monosaccharide content less than about 10%.
The used herein, xe2x80x9calkyl polysaccharide surfactantxe2x80x9d is intended to represent both the preferred glucose and galactose derived surfactants and the less preferred alkyl polysaccharide surfactants. Throughout this specification, xe2x80x9calkyl polyglucosidexe2x80x9d is used to include alkyl polyglycosides because the stereochemistry of the saccharide moiety is changed during the preparation reaction.
An especially preferred APG glycoside surfactant is APG 625 glycoside manufactured by the Henkel Corporation of Ambler, Pa. APG25 is a nonionic alkyl polyglycoside characterized by the formula:
CnH2n+1O(C6H10O5)xH
wherein n=10 (2%); n=122 (65%); n=14 (21-28%); n=16 (4-8%) and n=18 (0.5%) and x (degree of polymerization)=1.6. APG 625 has: a pH of 6 to 10 (10% of APG 625 in distilled water); a specific gravity at 25xc2x0 C. of 1.1 g/ml; a density at 25xc2x0 C. of 9.1 lbs/gallon; a calculated HLB of 12.1 and a Brookfield viscosity at 35xc2x0 C., 21 spindle, 5-10 RPM of 3,000 to 7,000 cps.
The present light duty liquid detergents such as dishwashing liquids are readily made by simple mixing methods from readily available components which, on storage, do not adversely affect the entire composition. The apparent viscosity of the composition desirably will be at least 1000 to about 6000 mPa.s at room temperature, but may be up to about 7000 mpa.s as measured with a Paar Physica UDS 200 rheometer at a shear rate of 10.8 sxe2x88x921, more preferably 2000 to 5000 mPa.s and most preferably 3000 to 4000 mPa.s. Its viscosity may approximate those of commercially acceptable compositions now on the market. The composition viscosity and the composition itself remain stable on storage for lengthy periods of time, without color changes or settling out of any insoluble materials. The pH of the instant composition is about 3.0 to 7.5 and preferably about 5.5 to 7. The instant compositions have a minimum foam height of 110 mls after 55 rotations at 40xc2x0 C. as measured by the foam volume test using 0.75 grams of the composition per liter of water and 1 gram of corn oil per liter of water having a hardness of 300 ppm.

Light duty liquid composition containing gelatin beads and polyacrylate thickener