An improved rib assembly for a crash test dummy includes a U-shaped outer member which simulates a pair of ribs secured to a spine and a pair of transverse assemblies disposed in parallel and coupled between such opposed ribs. A first assembly is a spring centered damper which provides simulated resistance to displacement of one rib relative to another. A second assembly includes a spring biased piston and cylinder that provides simulated positioning of the rib ends. A sensor disposed generally between the two assemblies measures the displacement of one of the pair of ribs relative to the other. The piston rod is supported upon a pair of linear ball bearing assemblies which maintains alignment between these two assemblies and ensures accurate responsive motion therebetween without binding and thus accurate measurements of displacement. A plurality of U-shaped rib assemblies, typically three, may be utilized to simulate a rib cage in a crash test dummy.

The invention relates generally to components for crash test dummies and more specifically to an improved rib assembly for securement to a spine of a crash test dummy which may be used in multiples.
Beyond calculations and projections from known data, safety design for automobiles has long relied and will likely continue to rely upon the results of actual crash tests. Notwithstanding the increasing application of super computers to this task, real world, controlled and highly instrumented crashes to test both prototype and production vehicles will continue. The complement to such testing is the crash test dummy, a mannequin or simulated human form, which attempts to approximate, as closely as possible, the skeletal, muscular and organic construction of the human body. It is entirely reasonable to state that the sophistication of crash test dummies has increased commensurately with the increased emphasis on safe motor vehicles and the sophistication of data recovery from crash tests.
Perhaps the most single common raw data recorded from a crash is the displacement of vehicle structure and components as well as the displacement of crash test dummy components relative to one another. While the data recorded is typically displacement, it is recorded over time and such displacement over time is readily conditioned or recomputed to provide both speed and acceleration of such components.
Such displacement typically is measured along a single linear path or two orthogonal paths. Given the often oblique or random direction of forces relative to an axis of a linear sensor, it is apparent that forces may frequently be generated which tend to interfere with the smooth, linear operation of a component and its sensor. Such oblique or transverse forces can frequently result in binding of a component and its sensor which manifests itself in reduced linear travel and thus reduced measured displacement and computed speed and acceleration. This is a particular problem in the larger structures of a crash dummy such as the rib cage where opposed left and right ribs are separated by several inches and oblique or transverse forces may cause binding of the simulation mechanism and significantly impair accurate measurement of displacement and associated variables.
Accordingly, rib assemblies that exhibit improved resistance to binding caused by oblique or transverse forces would be highly desirable. The present invention is directed to such a device.
An improved rib assembly for a crash test dummy includes a U-shaped outer member which simulates a pair of ribs secured to a spine and a pair of transverse assemblies disposed in parallel and coupled between such opposed ribs. A first assembly is a spring centered damper which provides simulated resistance to displacement of one rib relative to another. A second assembly includes a spring biased piston and cylinder that provides simulated positioning of the rib ends. A sensor disposed generally between the two assemblies measures the displacement of one of the pair of ribs relative to the other. The piston rod is supported upon a pair of linear ball bearing assemblies which maintains alignment between these two assemblies and ensures accurate responsive motion therebetween without binding and thus accurate measurements of displacement. A plurality of U-shaped rib assemblies, typically three, may be utilized to simulate a rib cage in a crash test dummy.
Thus it is an object of the present invention to provide rib components for a crash test dummy which exhibit improved performance when subjected to oblique and transverse forces.
It is a further object of the present invention to provide rib assemblies for crash test dummies having linear ball bearing assemblies which support transversely telescoping members.
It is a still further object of the present invention to provide a rib assembly for crash test dummies which may be used in multiples in a crash test dummy.
It is a still further object of the present invention to provide a rib assembly for a crash test dummy which provides improved displacement measurements during crash tests.
Further objects and advantages of the present invention will become apparent by reference to the following description and appended drawings wherein like reference numbers refer to the same component, element or feature.


Polymeric films including a layer of propylene resin having microvoids therein, the microvoids having been formed by stretching a web containing the beta-form of polypropylene, have shown low static cling when being unwound from rolls in labelling operations and also during destacking of pre-formed labels. The invention provides labels formed from such films.

1. Field of the Invention
This invention concerns labels made from polyolefin films, and a method of making such labels.
2. Description of Related Art
Polyolefin films are increasingly being used to produce labels, both as a substitute for paper labels and to exploit the inherent properties of polyolefin films such as their printability and their ability to be molded into and to adhere to the surfaces of containers as they are being formed. Since polyolefins used to form such films are usually inherently clear and colorless, films formed from them are often rendered opaque and/or colored white, thereby producing a label which is itself opaque.
A variety of techniques have been proposed for making polyolefin films opaque, one being the inclusion of a pigment, for example, titanium dioxide, and another being the formation of microvoids within the films which scatter light and thereby impart opacity to the films. The use of titanium dioxide has the advantage that it generally provides a high degree of opacity but this is accompanied by its additional cost and significant amounts are required in order to obtain the desired opacity. Microvoids have the advantage that they can be formed relatively easily in polypropylene, but the degree of opacity which can be achieved is often insufficient for labels. In addition, the amount of voiding agent which can be added to polypropylene, for example, is limited by the reduction in strength of the resulting voided film. Combinations of a pigment such as titanium dioxide and a voiding agent such as chalk in polypropylene films have therefore been used in an attempt to improve the opacity of labels made from polypropylene.
In certain end uses of labels made from polyolefin films, for example, in in-mold labelling, the film is pre-cut and is converted into individual labels which are then formed into a stack from which individual labels are removed as they are required. However, the problem with removing individual labels from a stack is that they are often difficult to separate from each other as a result of static electricity between adjacent labels, and this often increases as more labels are removed from the stack.
The build up of static charge is also a problem if polyolefin films are cut and fed at high speed from reels of films, for example, in wrap-around or cut-in-place labelling, or pre-formed labels on a release web, for example, in self-adhesive labelling.
The undesirable effects of static charge build up can be reduced, for example, by adding relatively large amounts of antistatic agents to the films, but doing so can also lead to other undesirable physical effects such as reducing print adhesion to the films.
Accordingly, it is an object of the invention to provide labels formed from polypropylene polymers that have advantageous properties. It is also an object of the invention to provide methods of making and using such labels.
In accordance with these and other objects, there has been provided a polymeric label formed from a film comprising a layer of propylene polymer resin having microvoids therein, the microvoids having been formed by stretching a web containing the beta-form of polypropylene.
In accordance with the present invention, there is also provided a method of making a label including:
(a) forming a film comprising the beta-form of polypropylene;
(b) stretching the film to form microvoids; and
(c) cutting the film into labels.
In accordance with the present invention, there is also provided a polymeric label formed from a film comprising an opaque layer of propylene polymer that does not include void-initiating particles or opacifying pigments.
Further objects, features, and advantages of the invention will become apparent from the detailed description of preferred embodiments that follows.
According to the present invention, there is provided a label formed from a film comprising a layer of polypropylene-based resin having microvoids therein, the microvoids having been formed by stretching a web containing the beta-form of polypropylene.
xe2x80x9cPolypropylene-based resinxe2x80x9d or xe2x80x9cpolypropylene-based polymerxe2x80x9d and xe2x80x9cpolypropylenexe2x80x9d are used synonymously. These terms shall mean polymers containing at least 50% by weight, based on the weight of the polymer, of propylene units.
xe2x80x9cWebxe2x80x9d shall mean a sheet-like extrudate resulting from extruding the respective polymer melt or melts through a slot die and subsequent cooling of the melt to form the unoriented film.
xe2x80x9cBase layerxe2x80x9d shall mean either xe2x80x9cthe layerxe2x80x9d in case of a monolayered film or the thickest layer, generally being the innermost, central layer of the multilayer structure.
xe2x80x9cBeta form of polypropylenexe2x80x9d shall mean that crystalline modification of polypropylene which has a lower melting point and a lower density than the common alpha form of propylene.
xe2x80x9cMicrovoidsxe2x80x9d shall mean the hollow vacuoles in the polymer matrix reducing the density of the oriented polypropylene film wherein the reduced density is lower than that of a corresponding film without any voids.
Labels formed from polypropylene films with microvoids therein and produced by stretching a web containing the beta-form of polypropylene have been found to destack readily without the addition of an antistatic agent. In order to reduce static cling still further, an antistatic agent can, if desired, be added to the films to reduce static cling between labels in a stack or static generated on unwinding reels of the films. But in general the amount of antistatic agent can be kept to levels typically used for packaging films. Any desired antistatic agent can optionally be used in the labels.
The beta-form of polypropylene is relatively unstable compared with the corresponding alpha-form under the conditions normally used to produce polypropylene films. Thus, when melts of polypropylene are extruded and then cooled to form a polymeric film, which may then subsequently be stretched, the alpha-form of polypropylene tends to predominate. However, it is known to produce films using polypropylene containing high concentrations of the beta-form of polypropylene by mixing polypropylene containing a high proportion of the alpha-form with a suitable nucleating agent which induces the formation of high concentrations of the beta-form when it is molten and subsequently cooled.
One example of such a process is described in U.S. Pat. No. 4,386,129 which is incorporated herein be reference, in which a variety of so-called beta-nucleators are dispersed in polypropylene following which films are produced therefrom by melting and subsequent cooling, the crystallinity of the resulting cast films being controlled by appropriate adjustment of the cooling conditions. Selective extraction of the beta-form of the polypropylenes from the films leaving a matrix of the alpha-form is then used to impart porosity to the films.
U.S. Pat. No. 5,231,126, which is incorporated herein by reference, describes the use of two component mixtures of beta-nucleating agents to produce microporous films by mono- or biaxial stretching cast polypropylene webs containing a high concentration of the beta-form of polypropylene resulting from the use of the mixture of nucleating agents. It is believed that the porosity results from voids induced by the change of the beta-form into the alpha-form during the stretching process, the alpha-form having a higher density than the beta-form from which it is derived. The development of porosity during the stretching process is accompanied by a significant reduction in apparent film density and the films become opaque with a high degree of whiteness.
More recently it has been proposed in EP 0632095, which is incorporated herein by reference, to use a variety of organic amides as beta-nucleating agents in the formation of mono- and biaxially stretched polypropylene films. A melt of a mixture of polypropylene and the beta-nucleating agent are cast into a film web which is allowed to crystalize at a temperature of 15 to 140xc2x0 C. to form a solid web containing the beta-form of polypropylene. The web is then mono- or biaxially stretched at a temperature above 20xc2x0 C. but less than the melting point of the beta-form crystals in the web. The resulting stretched films are said to have high whiteness and hiding power combined with printability and writeability.
Microvoid formation during the plastic deformation of the beta-form of polypropylene is also described in the journal POLYMER (Vol. 35, No. 16, pp. 3342-5, 1995, and Vol. 36, No. 13, pp. 2523-30, 1995) which is incorporated herein by reference. Porosity is said to increase with higher crystallization and lower stretching temperatures. All samples containing the beta-form apparently become opaque when stretched at temperatures below 120-130xc2x0 C.
Opacity due to microvoid formation also occurs when propylene homopolymers are blended with a variety of incompatible particulate materials and are then biaxially stretched, numerous examples of this being known from the prior art. Typically, phase distinct organic or inorganic materials with a particle size of 1 to 10 xcexcm are used to impart opacity.
In the present invention, the polypropylene-based resin or polypropylene based polymer can be any resin or polymer containing propylene units, generally at least 50% by weight of propylene units, preferably 80-100% by weight of propylene, for example 95-100% by weight of propylene, in each case based on the total polymer weight. The polypropylene-based polymer is preferably a propylene homopolymer or a random or block copolymer or terpolymer containing a major proportion (80-100wt %) of units derived from propylene, the remainder being ethylene or butylene and having a crystallinity of at least 40% preferably 50 to 90%. Usually the polypropylene based polymer has a melting point of 140-170xc2x0 C., preferably 155-165xc2x0 C. and a melt flow index (DIN 53 735 at 21.6 N and 230xc2x0 C.) of 1.0-10 g/10 min, preferably 1.5-6.5 g/10 min. Most preferred is isotactic propylene homopolymer containing about 100% propylene units and a melting point of 160-162xc2x0 C.
The nucleating agent used to induce the formation of the beta-form of the polypropylene of the base layer can be selected from those proposed hitherto for the purpose. Any desired nucleating agent or agents can be used. However, particularly good results have been achieved using amides as proposed in EP 0632095, (hereby incorporated by reference) and more particularly N,Nxe2x80x2-dicyclohexyl-2,6-naphthalene dicarboxamide.
The amount of nucleating agent used to induce the formation of the beta-form of polypropylenes can be varied, for example from 0.0001 to 5 wt %, preferably from 0.001 to 2 wt % of the nucleating agent based on the weight of polypropylene, as described in EP 0632095, particularly preferred amounts being from 0.001 to 1 wt %.
The polypropylene should have sufficient amounts of the beta-form so as to form the desired amount of microvoids, and to give the desired opaque appearance when the films is stretched.
Films used to form labels in accordance with the present invention can suitably consist of a single layer of a polypropylene-based resin containing microvoids, but they can also include one or more further layers, for example, to impart particular properties to the labels. The films can, for example, include an outer printable layer, and this outer layer can be in direct contact with the voided polypropylene base layer, or can be an outer layer on one or more intermediate layers on the base layer.
Further layers if included are preferably formed from polyolefins, but can be suitably formed of any material. Examples of polymers which can be used for this purpose include polymers containing units derived from one or more of ethylene, propylene, butene-1, and higher aliphatic alpha-olefins, and blends of such polymers. Other polymeric materials which can be used for these further layers include acrylic polymers and polyolefins extended with unsaturated carboxylic acids and derivatives thereof, for example, acid ionomers and anhydrides.
The voided polypropylene-based resin layer of labels of the present invention will usually have a further layer on one surface thereof, such as heat-sealable layer. However, the other surface of the polypropylene-based layer need not have any further layers thereon. The absence of an output layer can be used, for example, to exploit the often present surface roughness of the base layer which can aid labelling. However, this other surface of the base layer can have one or more polymeric layers thereon, for example, a heat sealable layer which can be the same as or different from the optional layer on the outer surface of the film. Preferred materials for this layer can suitably be selected for copolymers referred to above.
Films used to form labels in accordance with the present invention can also optionally include one or more additives used in the polyolefin art, for example, slip agents, antistatic agents, antiblock agents, neutralizing agents, stabilizers, UV absorbers, and/or pigments. Such additives, if included, are preferably present in amounts which do not significantly adversely affect the ability of the polypropylene to crystalize in the beta-form. When additives are present, they can be added to one or more of the layers of the film. When an antistatic agent is added to films used to produce labels in accordance with the present invention, the total amount of added antistatic agent is preferably not more than 1 wt % based on the total weight of the film.
In accordance with the invention, no external additives, such as calcium carbonate or other void-initiating particles like polyethylene terephthalate (PET) or titanium dioxide or other white pigments are needed to give an opaque film. External additives are additives other than polypropylene and being incompatible with polypropylene and causing formation of voids upon stretching.
Films used to make labels in accordance with the present invention can be produced using known methods. For example, the films can be made by extrusion or coextrusion through a slot die of melts of the appropriate polymers for the layer or layers which may be desired, to form a polymer web which is cooled and thereafter sequentially biaxially stretched. However, layers other than the voided layer can be applied to the polypropylene based resin layer by coating after the voided polypropylene layer itself has been formed.
It is generally desirable to carry out certain of the processing steps, particularly the initial crystallization of the polypropylene from a melt containing the beta-forming nucleating agent, under conditions which will bring about the formation of the desired film structure. More particularly, the cooling should be preferably effected under conditions such that the beta-form of polypropylene is produced and void formation can occur during subsequent stretching of the films.
The cooling or crystallization temperature used to induce the formation of the beta-form of polypropylene in the base layer of films of the present invention prior to stretching should generally be at least 20xc2x0 C. but less than the melting point of the beta-form of polypropylene. Although temperatures at the lower end of this range, for example up to 50xc2x0 C., can be used, it is generally preferred to use temperatures of at least 70xc2x0 C., and still higher temperatures are often preferred, for example 90xc2x0 C. or more. However, the cooling temperature is preferably not more than 140xc2x0 C., preferably not more than 130xc2x0 C. and from practical considerations it is preferably below the temperature at which the film sticks to surfaces used to cool it.
Cooling of the melt can be effected in air of a suitable temperature, but is generally preferred to effect cooling by contacting the extruded web with a cooling surface, for example, a chill roll or by immersing the extruded melt into a cooling liquid.
Subsequent biaxial stretching of the cooled web can be effected under conditions known in the polypropylene film art. Stretching is preferably effected sequentially, thus enabling the conditions used in the two directions to be selected independently of each other. Stretching in the direction of extrusion (the machine direction) will usually be effected before stretching in the transverse direction.
The conditions used to effect stretching in the machine direction have been found to have a substantial effect on microvoid formation, lower stretch temperatures and lower stretch ratios usually leading to increased voiding. A preferred temperature range for stretching in the machine direction is from 70 to 110xc2x0 C., and more preferably from 80 to 95xc2x0 C. The stretch ratio used in the machine direction will usually be at least 3:1, and a preferred range is from 3.5:1 to 8:1.
Subsequent stretching of the films in the transverse direction will in general be effected at lower temperatures than are conventionally used for the transverse stretching of polypropylene films, for example, at from 100 to 160xc2x0 C. However, it is generally preferred to effect stretching in the transverse direction at temperatures of 120xc2x0 C. to not more than 155xc2x0 C. and preferably not more than 150xc2x0 C. in order to produce biaxially stretched films having low densities. The stretch ratio used in the transverse direction is preferably from 3:1 to 10:1, preferably 5:1 to 10:1.
In general it is preferred that the area stretch ratio of film used to produce labels in accordance with the present invention be at least 15:1, and preferably at least 20:1. Much higher area stretch ratios can be used, for example, up to 70:1, but lower area stretch ratios, for example less than 50:1, will usually be used. A preferred range of area stretch ratios is from 25:1 to 50:1. The area stretch ratio is the overall stretching applied to the film. In case of a first stretching lengthwise and a subsequent stretching crosswise the area stretch ratio results from multiplying the stretch ratio lengthwise and crosswise e.g., stretching lengthwise 6:1 and crosswise 8.1 give an area stretch ratio of 48:1.
Either or both surfaces of films used to produce labels in accordance with the present invention are preferably treated to increase their surface energy, and hence their printability, for example, using flame or corona discharge treatment.
Labels in accordance with the present invention can have any desired thickness. The labels of the present invention will usually have thicknesses of from 40 to 80 xcexcm, although they can, if desired, be thicker or thinner, for example depending on the eventual end use of the labels. In most cases, they will be at least 25 xcexcm thick. When an outer layer is present on either one or both sides of the voided polypropylene polymer layer, it preferably has a thickness of from 0.2 to 6 xcexcm, and more preferably from 1.0 to 4.0 xcexcm.
The following Examples are given by way of illustration only, and do not limit the scope of the invention.


A user device may send a request for a data file to an access point. The user device may then receive, from the access point, data indicating that a segment of the data file has been previously cached in a local cache at the access point. In response to receiving the data, the user device may display an indicator configured to indicate that the segment of the data file is cached in the local cache.

Content delivery describes the delivery of media content such as audio, video, computer software, and video games over a delivery medium such as broadcasting or the Internet. Specialist networks, known as content delivery networks, distribute digital content on the Internet. Alternative technologies for content delivery include peer-to-peer file sharing technologies. Content can only be delivered if it exists. If it does not exist, several techniques and methods can be used for content creation or content regeneration. Alternatively, content delivery platforms create and syndicate content remotely, acting like hosted content management systems.

Method and system to locally cache and inform users of partial video segments and data objects


A polymer gel composition useful in the fabrication of a vibration damping material comprises a maleated polyalkylene grafted via a grafting agent such as a diamine to a poly(alkenyl-co-maleimide), an epoxy polymer and, optionally, an extender such as a phthalate oil.

The present invention relates to the development of high damping polymers with superior adhesion properties, high-temperature stability, mechanical strength and moldability.
The polymerization of isobutylene and maleic anhydride is known, as is the polymerization of styrene and maleic anhydride, and alkyl vinyl ethers and maleic anhydride. These polymerization techniques are carried out by free radical initiation. Further, imidization between a maleic anhydride and a primary amine group is a commonly known chemical reaction. It has long been recognized that two or more polymers may be blended together to form a wide variety of random or structured morphologies to obtain products that potentially offer desirable combinations of characteristics. However, it may be difficult or even impossible in practice to achieve many potential combinations through simple blending because of some inherent and fundamental problem. Frequently, the two polymers are thermodynamically immiscible, which precludes generating a truly homogeneous product. While immiscibility may not be a problem since it may be desirable to have a two-phase structure, the situation at the interface between these two phases very often does lead to problems. The typical case is one of high interfacial tension and poor adhesion between the two phases. This interfacial tension contributes, along with high viscosities, to the inherent difficulty of imparting the desired degree of dispersion to random mixtures and to their subsequent lack of stability, giving rise to gross separation or stratification during later processing or use. Poor adhesion leads, in part, to the very weak and brittle mechanical behavior often observed in dispersed blends and may render some highly structured morphologies impossible.
The present invention is a polymer gel composition comprising a polymer including an anhydride unit and an alkenyl unit; a crosslinking agent; a maleated polyalkylene; an extender; and an epoxy.
According to one embodiment of this invention, a blend of a maleated polyalkylene and a poly(alkenyl-co-maleimide) and an epoxy polymer that is useful in producing high damping and soft materials with good adhesion properties is provided. The polymer gel can be formed by reacting the polymeric constituents with a grafting agent, followed by mixture with an epoxy polymer.
It is an advantage of the invention to produce a polymer composition that exhibits improved properties such as tensile strength, maximum elongation, tear strength, damping properties, high temperature stability, good adhesion, and the like, with emphasis on good adhesion. More particularly, the present inventive grafted polymer compositions combine with an epoxy polymer to improve the tensile strength, tear strength, damping properties, high-temperature compression set, and adhesion of the centipede polymer.
The polymer gel composition of the present invention contains: 0.5-200 parts by weight of a grafted polymer of a poly(alkenyl-co-maleimide) having at least one maleated polyalkylene segment grafted thereto through the at least one functional linkage formed by a cross-linking reaction with a diamine grafted agent; and 0 to 1000 parts by weight of a hyperbranched epoxy polymer. It is understood that the general term poly(alkenyl-co-maleimide) is an inclusive term which includes poly(alkenylbenzne-co-maleimide), poly(R1R2ethylene-co-maleimide), and poly(alkylvinyl ether-co-maleimide).
The poly(alkenyl-co-maleimide) is a xe2x80x9ccentipedexe2x80x9d polymer formed by imidizing a poly(alkenyl-co-maleic anhydride) with a primary amine. The xe2x80x9ccentipedexe2x80x9d polymer has a high molecular weight spine connected with many relatively short side chains formed from the addition of the primary amines. The length of the main chain usally equals or is longer than the entanglement length, which is herein defined theoretically as an order of magnitude of 100 repeating units, while the length of the side chains is smaller than the entanglement length.
The preferred alkenyl monomer units of the poly(alkenylbenzne-co-maleimide) xe2x80x9ccentipedexe2x80x9d are any one or combination of styrene, xcex1-methyl styrene, 1-vinyinaphthalene, 2-vinylnaphthalene, 1-xcex1-methyl-vinyinaphthalene, 2-xcex1-methyl vinylnaphthalene, as well as alkyl, cycloalkyl, aryl, alkaryl, and aralkyl derivatives thereof, in which the total number of carbon atoms in the combined hydrocarbon is generally not greater than 12, as well as any di- or tri-vinyl aromatic hydrocarbons. The preferred vinyl aromatic hydrocarbons are either styrene or xcex1-methylstyrene. The terms xe2x80x9calkenyl benzenexe2x80x9d and xe2x80x9cvinyl aromaticxe2x80x9d are understood to be interchangeable as used herein.
The preferred R1R2ethylene contributed monomer units of the poly(R1R2ethylene-co-maleimide) are any alkene such as ethylene, propylene, butylene, isobutylene, pentene, hexene, heptene, etc., as well as any di- or tri- alkene, with preference given to isobutylene.
The preferred alkyl vinyl ether contributed monomer units of the poly(alkylvinyl ether-co-maleimide) are any alkylvinyl ether such as methylvinyl ether, ethylvinyl ether, propylvinyl ether, butylvinyl ether, and any other alkyl vinyl ether wherein the number of carbons in the alkyl substituent is not greater than about 12.
The poly(alkenyl-co-maleimides) described herein are subsequently graft-reacted through a difunctional linking or grafting agent to a maleated polyalkylene to yield a maleated polymer having at least one polyalkylene segment grafted thereto through at least one functional linkage thus formed. The alkylene moiety of the polyalkylene is selected from the group consisting of ethylene, propylene, and mixtures thereof The preferred polyalkylene is polypropylene.
The maleated polypropylene may be any of the conventionally known polypropylene compounds that are subsequently maleated by methods known in the art. The polypropylene grafted segment or segments have molecular weights MW of about 10,000 up to about 10,000,000, or higher, preferably about 20,000 to about 300,000.
The crystallinity, or tacticity, of the polypropylene may vary from being substantially amorphous to being completely crystalline, that is from about 10-100% crystallinity. Most typically, because of the extensive commercial use of isotactic polypropylene, the grafted polypropylene will be substantially crystalline, e.g., greater than about 90%. Generally, the polypropylene is substantially free of ethylene. However, under certain circumstances small amounts of ethylene, on the order of less than about 10% by weight, may be incorporated. Furthermore, in certain instances the polypropylene contains small amounts of ethylene in copolymers known as xe2x80x9creactor copolymers.xe2x80x9d Thus, it is within the scope of the invention that the grafted polypropylenes contain minor amounts of ethylene, both as part of the ethylene-propylene segments and as polyethylene segments.
The maleated polypropylene of this invention contains from about 0.01 wt. % incorporated maleic anhydride, based upon the weight of the maleated polypropylene, up to about 5 wt. %. Preferably the maleic anhydride content will be from about 0.01 to about 2 wt. %, most preferably about 0.03 to about 0.2 wt. %. As will be apparent, unreacted polypropylene will also be present in the reaction mix as will minor amounts of reaction by-products, such as decomposed free-radical initiator compounds and low molecular weight free-radical products. These by-products are substantially removed, by methods known in the art, e.g., sparging with nitrogen or washing with water. Maleic anhydride may not be left in substantial amounts in the polymer without detrimental effects on the subsequent reaction of the poly(alkenyl-co-maleimide) with the maleated polyalkylene.
The poly(alkenyl-co-maleimide) of the present invention is formed by reacting a poly(alkenyl-co-maleic anhydride) in the presence of a mono-primary amine at temperatures from about 100xc2x0 C. to about 300xc2x0 C. and at a pressure from about slightly above vacuum to about 20 atmospheres, under substantially dry conditions. The reactants are preferably dry mixed in the absence of solvents in a suitable mixing apparatus such as a Brabender mixer. It is preferable to purge the mixer with nitrogen prior to the charging of the reactants. The primary amine may be added in a singular charge, or in sequential partial charges into the reactor containing a charge of poly(alkenyl-co-maleic anhydride). Preferably the primary amine is charged in ratio between 0.8 to 1.0 moles of amine per monomer contributed units of maleic anhydride in the poly(alkenyl-co-maleic anhydride).
Suitable primary amines include, but are not limited to: alkyl amines; alkyl benzyl amines; alkyl phenyl amines; alkoxybenzyl amines; allyl aminobenzoates; alkoxy aniline; and other linear primary amines containing from 1 to 50 carbon atoms, preferably 6 to 30 carbon atoms in the alkyl and alkoxy substituents in these primary amines. It is understood that the alkyl and alkoxy substituents on the above discussed primary amines can be linear or branched, preferably linear, and saturated or unsaturated, preferably saturated. Exemplary, but not exclusive of such amines are hexylamine, octylamine, dodecylamine, and the like.
The poly(alkenyl-co-maleimide) prior to grafting with maleated polyalklene, preferably has a molecular weight range between about 10,000 and 500,000, and even more typically between about 150,000 and 450,000, where the molecular weight is weight-average (MW).
The polymer of the present invention may be prepared by any means well known in the art for combining such ingredients, such as blending, milling, or internal batch mixing. A rapid and convenient method of preparation comprises heating a mixture of components to a temperature of about 50-290xc2x0 C.
The polymers of this invention are preferably manufactured by mixing and dynamically heat-treating the components described above, namely, by melt-mixing. As for the mixing equipment, any conventional, generally known equipment such as an open-type mixing roll, closed-type Banbury mixer, closed-type Brabender mixer, extruding machine, kneader, continuous mixer, etc., is acceptable. The closed-type Brabender mixer is preferable, and mixing in an inactive gas environment, such as nitrogen or argon, is also preferable.
Grafting of the maleated polyalklene and the poly(alkenyl-co-maleimide) is performed by addition of a grafting agent. The preferred grafting agent is a low molecular weight organic compound with at least 2 functional groups capable of crosslking said polymer. Appropriate functional groups include primary amine, secondary amine, carboxyl, formyl, and hydroxyl. The preferred grafting agent is a polyamine, preferably an organic diamine, to a blend of maleated polyproylene and poly(alkenyl-co-maleimide) to partially cross-link the polyalkylene to the poly(alkenyl-co-maleimide) through the maleate functional groups.
Suitable organic diamines or diamine mixtures containing two aliphatically or cycloaliphatically bound primary amino groups are used as grafting agents for the process according to the present invention. Such diamines include, for example, aliphatic or cycloaliphatic diamines corresponding to the following formula: R1(NH2)2, wherein R1 represents an aliphatic hydrocarbon group having from 2 to 20 carbon atoms, a cycloaliphatic hydrocarbon group having from 4 to 20 carbon atoms, an aromatic hydrocarbon group having from 6 to 20 carbon atoms, or an N-heterocyclic ring having from 4 to 20 carbon atoms, e.g., ethylenediamine; 1,2- and 1,3-propylene diamine; 1,4-diaminobutane; 2,2-dimethyl-1,3-diaminopropane; 1,6-diaminohexane; 2,5-dimethyl-2,5-diaminohexane; 1,6-diaminoundecane; 1,12-diaminododecane; 1-methyl-4-(aminoisopropyl)-cyclo-hexylamine; 3-aminomethyl-3,5,5-trimethyl-cyclohexylamine; 1,2-bis-(aminomethyl)-cyclobutane; 1,2-diamino-3,6-dimethylbenzene; 1,2- and 1,4-diaminocyclohexane; 1,2-, 1,4-, 1,5-, and 1,8-diaminodecalin; 1-methyl-4-aminoisopropyl-cyclohexylamine; 4,4xe2x80x2-diamino-dicyclohexyl methane; 2,2xe2x80x2-(bis-4-amino-cyclohexyl)-propane; 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diaminodicyclohexyl methane; 1,2-bis-(4-aminocyclohexyl)-ethane; 3,3xe2x80x25,5xe2x80x2-tetramethyl-bis-(4-aminocyclohexyl)-methane and -propane; 1,4-bis-(2-aminoethyl)-benzene; benzidine; 4,4xe2x80x2-thiodianiline; 3,3xe2x80x2-dimethoxybenzidine; 2,4-diaminotoluene; diaminoditolylsulfone; 2,6-diaminopyridine; 4-methoxy-6-methyl-m-phenylenediamine; diaminodiphenyl ether; 4,4xe2x80x2-bis(o-toluidine); o-phenylenediamine; methylene bis(o-chloroaniline); bis(3,4-diaminophenyl) sulfone; diamino-phenylsulfone; 4-chloro-o-phenylenediamine; m-aminobenzyl amine; m-phenylene diamine; 4,4xe2x80x2-C1-C6-dianiline; 4,4xe2x80x2-methylene-dianiline; aniline-formaldehyde resin; trimethylene glycol-di-p-aminobenzoate; bis-(2-aminoethyl)-amine, bis-(3-aminopropyl)amine; bis-(4-aminobutyl)-amine; bis-(6-aminohexyl)-amine, and isomeric mixtures of dipropylene triamine and dibutylene triamine. Mixtures of these diamines may also be used.
Other suitable polyamines for use as grafting agents in the process according to the present invention include bis-(aminoalkyl)-amines, preferably those having a total of from 4 to 12 carbon atoms, such as bis-(2-aminoethyl)amine, bis-(3-aminopropyl)amine, bis-(4-aminobutyl)amine, and isomeric mixtures of dipropylene triamine and dibutylene triamine. Hexamethyl diamine, tetramethylene diamine, and especially 1,12-diaminododecane are preferably used.
The centipede polymers of the present invention may be a glassy material and may therefore have an extender added to the polymer during final processing. Suitable extenders include extender oils and low molecular weight compounds or components, such as the extenders including, but not limited to: naphthenic, aromatic, paraffinic, pthalic, and silicone oils. The preferred extender for the present invention is a pthalic oil. The preferred pthalic oil is di(tridecyl)pthalate from the C. P. Hall Company. This oil is added in the final stages of the preparation of the centipede polymer. The final centipede polymer can contain between 25 and 40% oil and is a thermoreversible elastomer.
After the centipede polymer is formed, it is mixed with an epoxy polymer, preferably a hyperbranched epoxy polymer, to improve the adhesion and damping properties of the polymer gel. Generally, the term hyperbranched herein will mean a highly branched polymer structure with a random morphology and high resistance to crystallization. The hyperbranched epoxy polymer is formed by the reaction of an epoxy prepolymer with a curing agent. Epoxy polymers are typically formed by the reaction of bisphenol A and epichlorhydrin. Epichlorohydrin is reacted with a variety of hydroxy, carboxy, and amino compounds to form monomers with two or more epoxide groups, and these monomers are then used in the reaction with bisphenol A. Examples are the diglycidyl derivative of cyclohexane-1,2-dicarboxylic acid, the triglycidyl derivatives of p-aminophenol and cyanuric acid, and the polylglycidyl derivative of phenolic prepolymers. Epoxidized diolefins are also employed. In the present invention, the epoxy prepolymer which is preferred is poly[(o-cresyl glycidyl ether)-co-formaldehyde].
A variety of coreactants can be used to cure the epoxy resins either through the epoxide or hydroxyl groups. Polyamines are the most common curing agent with reaction involving ring-opening addition of amine. Both primary and secondary amines are used with primary amines being more reactive than secondary amines. Since each nitrogen-hydrogen bond is reactive in the curing reaction, primary and secondary amine groups are bi- and mono-functional respectively. A variety of amines are used as crosslinking agents, including diethylene triamine, triethylene tetramine, 4,4xe2x80x2-diamino-diphenylmethane, and polyaminoamides. The preferred amines for the formation of the epoxy polymer in the present invention are dodecyl amine, dibutyl amine, octadecyl amine, and hexamethyleneimine.
A suitable epoxy polymer, preferably hyperbranced, is formed by reaction of an epoxy resin with a polyamine to such an extent that the system is near the gelation point, but without exceeding the point. A near-gelation polymer can be formed when the degree of interchain reaction, i.e., crosslinking, between the elastomeric molecules nears or approaches the gel point of the polymeric composition. At the gel point, a gel or insoluble polymer fraction forming in a polymeric composition first becomes observable.
Theoretically, a gel corresponds to an infinite network in which polymer molecules have been crosslinked to one another to form a macroscopic molecule. The gel may then be considered one molecule. A gel generally is insoluble in all solvents at elevated temperatures under conditions where polymer degradation does not occur; the non-gel portion of the polymer, often referred to as sol, remains soluble in solvents. For present purposes, near-gelation polymers also can be referred to as near-gel polymers.
When forming a near-gelation polymer, the gel point of the polymeric composition employed to create the near-gelation polymer preferably is determined. Several techniques are known in the art for estimating the gel point of polymeric compositions. Gel point can be determined experimentally by solvent extraction and other techniques described in P. J. Flory, Principles of Polymer Chemistry (1953). Gel point also can be approximated by using theoretical calculations as described in, for example, G. Odian, Principles of Polymerization, 3d ed., pp. 108-123, (1991). Throughout the presentspecification, the polymeric composition employed to create the near-gelation polymer can be referred to as the prepolymer system.
Although gel point can be discussed in terms of a variety of parameters, determining the ratio of the weight of curative to the weight of prepolymer necessary to reach the gel point can be convenient. Thus, gel point can be represented by the weight of curative necessary to reach gelation, Wcg, over the weight of prepolymer, Wp. Likewise, the point of complete cure can be represented by the weight of curative necessary to reach complete cure, Wcc, divided by Wp. In general, therefore, the extent of any curing reaction can be represented by the weight of curative added, Wc, divided by Wp. For present purposes, extent of reaction, r, can be represented by Wc over Wp. Therefore, the extent of gelation, rg, is rg=Wcg/Wp, and the extent of complete cure rcc=Wcc/Wp.
Once the gel point of the prepolymer is determined, an appropriate amount of curative can be added and reacted with the prepolymer to achieve a near-gelation polymer. When selecting an appropriate amount of curative, the gel point preferably is approached but not exceeded, although the definition of near-gelation polymer broadly includes those reaction products of curative and prepolymer that exceed the gel point without actually reaching complete cure. Thus, the weight ratio employed to create a near-gelation polymer preferably is based on E=|(rxe2x88x92rg)/rg| where E is the relative distance to the gel point while r and rg are defined as above. Since E is an absolute value, E is greater than or equal to 0 and less than or equal to about 0.5, more preferably less than about 0.2, still more preferably less than about 0.1, and even more preferably no more than about 0.05. The foregoing formula involves the absolute value of a number and, therefore, the extent of the reaction (r) is a relative distance (E) both beyond and before the gel point. For example, where the gel point of a particular polymeric composition is about 0.5 parts of curative per part of prepolymer, a near-gel polymer can be obtained by reacting the polymeric composition with about 0.3 or about 0.7 parts of curative per part of the prepolymer (thus, E=|(0.3xe2x88x920.5)/(0.5)|=0.4 or E=|(0.7xe2x88x920.5)/(0.5)|=0.4).
It is frequently desirable to include other additives well known in the rubber art to the compositions of the present application. Stabilizers, antioxidants, conventional fillers, reinforcing agents, reinforcing resins, pigments, fragrances, and the like are examples of some such additives. Specific examples of useful antioxidants and stabilizers include 2-(2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)benzotriazole, nickel di-butyl-di-thiocarbamate, zinc di-butyl-di-thiocarbamate, tris(nonylphenyl)phosphite, 2,6-di-t-butyl-4-methylphenol, and the like. Exemplary conventional fillers and pigments include silica, carbon black, titanium dioxide, iron oxide, and the like. These compounding ingredients are incorporated in suitable amounts depending upon the contemplated use of the product, preferably in the range of 1-350 parts of additives or compounding ingredients per 100 parts of the polymer composition.
A reinforcement may be defined as the material that is added to the polymer matrix to improve the strength of the polymer. Most of these reinforcing materials are inorganic or organic products of high molecular weight. Various examples include glass fibers, asbestos, boron fibers, carbon and graphite fibers, whiskers, quartz and silica fibers, ceramic fibers, metal fibers, natural organic fibers, and synthetic organic fibers. Other elastomers and resins are also useful to enhance specific properties like damping properties, adhesion, and processability. Examples of other elastomers and resins include adhesive-like products including Reostomer (produced by Riken-Vinyl, Inc.), hydrogenated polystyrene-(medium or high 3,4)-polyisoprene-polystyrene block copolymers such as Hybler (produced by Kurare, Inc.), polynorbornenes such as Norsorex (produced by Nippon Zeon, Inc.), and the like. In this case the foregoing materials are equally applicable to the instant centipede polymer compositions.
In summary, the molded polymers produced from the blend of the present centipede polymer and epoxy polymer retain elastomeric characteristics and are useful in high damping applications.
Damping is the absorption of mechanical energy by a material in contact with the source of that energy. It is desirable to damp or mitigate the transmission of mechanical energy from, for example, a motor, engine, or power source to its surroundings. Elastomeric materials are often used for this purpose. It is desirable that such materials be highly effective in converting this mechanical energy into heat rather than transmitting it to the surroundings. It is further desirable that this damping or conversion is effective over a wide range of temperatures and frequencies commonly found near motors, automobiles, trucks, trains, planes, and the like.
The compositions of the present invention are favorably used in the manufacturing of any product in which the following properties are advantageous: a degree of softness, heat resistance, decent mechanical properties, elasticity, good adhesion, and/or high damping. The compositions of the present invention can be used in all industry fields, in particular, in the fabrication of automotive parts, tire tread rubbers, household electrical appliances, industrial machinery, precision instruments, transport machinery, constructions, engineering, medical instruments, and tire rubber formulations.
Representative examples of the composition of the present invention are in the fabrication of damping materials and vibration restraining materials. These uses involve connecting materials such as sealing materials, packing, gaskets, and grommets; supporting materials, such as mounts, holders, and insulators; and cushion materials such as stoppers, cushions, and bumpers. These materials are also used in equipment producing vibration or noise and household electrical appliances, such as in air-conditioners, laundry machines, refrigerators, electric fans, vacuums, dryers, printers, and ventilator fans. These materials are also suitable for impact absorbing materials in audio equipment and electronic or electrical equipment, sporting goods, and shoes.
The present invention will also be useful in any application where superior adhesion properties are important. The applications for polymers with high adhesion properties fall into two major categories, coatings and structural. Coatings applications include marine, maintenance, drum, and can coatings. Automotive primer coatings involve epoxy resins with ionic charges that allow for electrodeposition of the resin. Waterborne epoxy coatings have been developed for beer and beverage containers. Structural composites are used in the military (missile casing, tanks), aircraft (rudders, wing skins, flaps), automobiles (leaf springs, drive shafts), and pipe in the oil, gas, chemical, and mining industries.

Poly(alkenyl-co-maleimide) and maleated polyalkylene grafted with grafting agent, and epoxy polymer


A granular detergent product is made by spraying a liquid binder to contact a particulate solid starting material in a low shear granulator such as a fluidized bed apparatus. The d3,2 average droplet diameter of the liquid binder is not greater than ten times the d3,2 average particle diameter of that fraction of the solid starting material which has a d3,2 particle diameter of from 20 xcexcm to 200 xcexcm provided that if more than 90% by weight of the solid starting material has a d3,2 average particle diameter less than 20 xcexcm then the d3,2 average particle diameter of the total solid starting materials shall be taken to be 20 xcexcm. If more than 90% by weight of the solid starting material has a d3,2 average particle diameter greater than 200 xcexcm than the d3,2 average particle diameter of the total starting solid material shall be taken to be 200 xcexcm.

The present invention relates to a process for the production of granular detergent compositions.
It is long known in the art to obtain detergent powders by spray drying. However, the spray-drying process is both capital and energy intensive and consequently the resultant product is expensive.
More recently, there has been much interest in production of granular detergent products by processes which employ mainly mixing, without the use of spray drying. These mixing techniques can offer great flexibility in producing powders of various different compositions from a single plant by post-dosing various components after an initial granulation stage.
A known kind of mixing process, which does not involve spray drying, employs a moderate-speed granulator (a common example often colloquially being called a xe2x80x9cploughsharexe2x80x9d), optionally preceded by a high-speed mixer (a common example often colloquially being called a xe2x80x9crecyclerxe2x80x9d due to its recycling cooling system). Typical examples of such processes are described in our European patent specifications EP-A-367 339, EP-A-390 251 and EP-A-420 317. These moderate-speed and high-speed mixers exert relatively high levels of shear on the materials being processed.
Until recently, there has been less effort in developing use of low-shear mixers or granulators. One type of low-shear equipment is a gas fluidisation granulator. In this kind of apparatus, a gas (usually air) is blown through a body of particulate solids onto which is sprayed a liquid component. A gas fluidisation granulator is sometimes called a xe2x80x9cfluidised bedxe2x80x9d granulator or mixer. However, this is not strictly accurate since such mixers can be operated with a gas flow rate so high that a classical xe2x80x9cbubblingxe2x80x9d fluid bed does not form.
Although low-shear granulators can give good control of bulk density, there is still a need for greater flexibility and in particular, for producing lower bulk density powders. Processes involving low-shear granulation are quite varied.
Indian Patent No. 166307 (Unilever) describes use of an internal recirculating gas fluidisation granulator and explains that use of a conventional fluidised bed will lead to a lumpy and sticky product.
East German Patent No. 140 987 (VEB Waschmittelwerk) discloses a continuous process for the production of granular washing and cleaning compositions, wherein liquid nonionic surfactants or the acid precursors of anionic surfactants are sprayed onto a fluidised powdered builder material, especially sodium tripolyphosphate (STPP) having a high phase II content to obtain a product with bulk density ranging from 530-580 g/l.
WO96/04359 (Unilever) discloses a process whereby low bulk density powders are prepared by contacting a neutralising agent such as an alkaline detergency builder and a liquid acid precursor of an anionic surfactant in a fluidisation zone to form detergent granules.
We have now found that in systems where a liquid binder is sprayed onto a powdered and/or granular solid in a low shear granulator, the droplet size in the spray relative to the particle size of the solids, determines granule size, bulk density and the yield of the process. Thus, the present invention provides a process for the production of a granular detergent product, the process comprising spraying droplets of a liquid binder to contact a particulate solid starting material in a low-shear granulator, wherein the d3,2 average droplet diameter of the liquid binder is not greater than 10 times, preferably not greater than 5 times, more preferably not greater than 2 times and most preferably not greater than the d3,2 average particle diameter of that fraction of the total solid starting material which has a d3,2 particle diameter of from 20 xcexcm to 200 xcexcm, provided that if more than 90% by weight of the solid starting material has a d3,2 average particle diameter less than 20 xcexcm then the d3,2 average particle diameter of the total solid starting material shall be taken to be 20 xcexcm and if more than 90% by weight of the solid starting material has a d3,2 average particle diameter greater than 200 xcexcm then the d3,2 average particle diameter of the total solid starting material shall be taken to be 200 xcexcm.
In the context of the present invention, the term xe2x80x9cgranular detergent productxe2x80x9d encompasses granular finished products for sale, as well as granular components or adjuncts for forming finished products, e.g. by post-dosing to or with, or any other form of admixture with further components or adjuncts. Thus a granular detergent product as herein defined may, or may not contain detergent material such as synthetic surfactant and/or soap. The minimum requirement is that it should contain at least one material of a general kind of conventional component of granular detergent products, such as a surfactant (including soap), a builder, a bleach or bleach-system component, an enzyme, an enzyme stabiliser or a component of an enzyme stabilising system, a soil anti-redeposition agent, a fluorescer or optical brightener, an anti-corrosion agent, an anti-foam material, a perfume or a colourant.
As used herein, the term xe2x80x9cpowderxe2x80x9d refers to materials substantially consisting of grains of individual materials and mixtures of such grains. The term xe2x80x9cgranulexe2x80x9d refers to a small particle of agglomerated powder materials. The final product of the process according to the present invention consists of, or comprises a high percentage of granules. However, additional granular and or powder materials may optionally be post-dosed to such a product.
The solid starting materials of the present invention are particulate and may be powdered and/or granular.
All references herein to the d3,2 average of solid starting materials refers to the d3,2 average diameter only of solids immediately before they are added to the low-shear granulation process per se. For example, hereinbelow it is described how the low-shear granulator may be fed by at least partially pre-granulated solids from a premixer. It is very important to note that xe2x80x9csolid starting materialxe2x80x9d is to be construed to comprise all of the material from the premixer which is fed to the low-shear granulation process but does not include all solids as dosed to the premixer and/or direct to any other processing stage up to processing or after the end of processing in the low-shear granulator. For example, a layering agent or flow aid added after the granulation process in the low-shear granulator does not constitute a solid starting material.
The process of the present invention may be carried out in either batch or continuous mode of operation as desired.
Whether the low-shear granulation process of the present invention is a batch process or a continuous process, solid starting material may be introduced at any time during the time when liquid binder is being sprayed. In the simplest form of process, solid starting material is first introduced to the low-shear granulator and then sprayed with the liquid binder. However, some solid starting material could be introduced at the beginning of processing in the low-shear granulator and the remainder introduced at one or more later times, either as one or more discrete batches or in continuous fashion. However, all such solids fall within the definition of xe2x80x9csolid starting materialxe2x80x9d.
The d3,2 diameter of the solid starting materials is that obtained by, for example, a conventional laser diffraction technique (e.g. using a Helos Sympatec instrument) or sieving as would be well-known to the skilled person.
Suitably, the solid starting material(s) have a particle size distribution such that not more than 5% by weight of the particles have a particle size greater than 250 xcexcm. It is also preferred that at least 30% by weight of the particles have a particle size below 100 xcexcm, more preferably below 75 xcexcm. However the present invention is also usable with larger fractions of solid starting materials (i.e.  greater than 5% more than 250 xcexcm, optionally also  less than 30% below 100 xcexcm or 75 xcexcm) but this increases the chance of some crystals of unagglommerated starting materials being found in the final product. This presents a cost benefit in allowing use of cheaper raw materials. In any event, the particulate solid starting material(s) have an average particle size below 500 xcexcm to provide detergent powders having a particularly desired low bulk density. Within the context of solid starting materials, reference to an average particle size means the d3,2 average particle diameter.
The maximum d3,2 average droplet diameter is preferably 200 xcexcm, for example 150 xcexcm, more preferably 120 xcexcm, still more preferably 100 xcexcm and most preferably 80 xcexcm. On the other hand, the minimum d3,2 droplet diameter is 20 xcexcm, more preferably 30 xcexcm and most preferably 40 xcexcm. It should be noted that in specifying any particular preferred range herein, no particular maximum d3,2 average droplet diameter is associated with any particular minimum d3,2 average droplet diameter. Thus, for example, a preferred range would be constituted by 150-20 xcexcm, 150-30 xcexcm, 150-40 xcexcm, 120-20 xcexcm, 120-30 xcexcm . . . and so on.
The d3,2 average droplet diameter is suitably measured, for example, using a laser phase doppler anemometer or a laser light-scattering instrument (e.g. as supplied by Malvern or Sympatec) as would be well-know to the skilled person.
The present invention is not specific to use of any particular kind of low-shear granulator but if one of the gas fluidisation kind is selected, then the liquid binder can be sprayed from above and/or below and/or within the midst of the fluidised solids.
The invention also encompasses a granular detergent composition obtainable by a process according to the present invention.
The present invention not only provides control of particle size and bulk density in the final product, it also avoids production of irregular-shaped particles. Moreover, it enables the process to be controlled in a way which ensures that fluidisation continues unhindered, especially (although not exclusively) when the low-shear granulator is of the gas fluidisation kind.
Preferably, but not exclusively, in the process according to the present invention, the low-shear granulator is of the gas fluidisation type and comprises a fluidisation zone in which the liquid binder is sprayed onto the solid material. However, a rotating drum or bowl mixer/granulator could also be used.
The low-shear granulator (of whatever kind) may be adapted to recycle xe2x80x9cfinesxe2x80x9d i.e. powdered or part-granular material of very small particle size, so that they are returned to the input or any other stage of operation of the low-shear granulator and/or of any pre-mixer. The fines recycled in this way, especially but not exclusively for a low-shear granulator operating in continuous mode, may be recycled for use as a flow aid and/or layering agent as described further hereinbelow. A further aspect of the invention may provide a process of forming a granular detergent product, the process comprising, in a low-shear granulator, contacting a fluidised solid starting material with a spray of liquid binder, extracting fine particulates during granulation and re-introducing the fine particulates to the process to act as a flow aid or layering agent. Preferably the fine particulates are elutriated material, e.g. they are present in the air leaving a gas fluidisation chamber.
Moreover, when the low-shear granulator is of the gas fluidisation kind it may sometimes be preferable to use equipment of the kind provided with a vibrating bed.
In a preferred class of processes according to the present invention, the liquid binder comprises an acid precursor of an anionic surfactant and the solid starting material comprises an inorganic alkaline material.
Such an acid precursor may for example be the acid precursor of a linear alkylbenzene sulphonate (LAS) or primary alkyl sulphate (PAS) anionic surfactant or of any other kind of anionic surfactant.
Suitable materials for use as the inorganic alkaline material include alkali metal carbonates and bicarbonates, for example sodium salts thereof.
The neutralising agent is very preferably present at a level sufficient to neutralise fully the acidic component. If desired, a stoichiometric excess of neutralising agent may be employed to ensure complete neutralisation or to provide an alternative function, for example as a detergency builder, e.g. if the neutralising agent comprises sodium carbonate.
The liquid binder may alternatively or additionally contain one or more other liquid materials such as liquid nonionic surfactants and/or organic solvents. The total amount of acid precursor will normally be as high as possible, subject to the presence of any other components in the liquid and subject to other considerations referred to below. Thus, the acid precursor may constitute at least 98% (e.g. at least 95%) by weight of the liquid binder, but could be at least 75%, at least 50% or at least 25% by weight of the binder. It can even, for example, constitute 5% or less by weight of the binder. Of course the acid precursor can be omitted altogether if required.
When liquid nonionic surfactant is present in the liquid binder together with an acid precursor of an anionic surfactant, then the weight ratio of all acid precursor(s) to nonionic surfactants, will normally be from 20:1 to 1:20. However, this ratio may be, for example, 15:1 or less (of the anionic), 10:1 or less, or 5:1 or less. On the other hand, the nonionic may be the major component so that the ratio is 1:5 or more (of the nonionic), 1:10 or more, or 1:15 or more. Ratios in the range from 5:1 to 1:5 are also possible.
For manufacture of granules containing anionic surfactant, sometimes it will be desirable not to incorporate all of such anionic by neutralisation of an acid precursor. Some can optionally be incorporated in the alkali metal salt form, dissolved in the liquid binder or else as part of the solids. In that case, the maximum amount of anionic incorporated in the salt form (expressed as the weight percentage of total anionic surfactant salt in the product output from the low shear granulator) is preferably no more than 70%, more preferably no more than 50% and most preferably no more than 40%.
If it is desired to incorporate a soap in the granules, this can be achieved by incorporating a fatty acid, either in solution in the liquid binder or as part of the solids. The solids in any event must then also comprise an inorganic alkaline neutralising agent to react with the fatty acid to produce the soap.
The liquid binder will often be totally or substantially non-aqueous, that is to say, any water present does not exceed 25% by weight of the liquid binder, but preferably no more than 10% by weight. However, if desired, a controlled amount of water may be added to facilitate neutralisation. Typically, the water may be added in amounts of 0.5 to 2% by weight of the final detergent product. Any such water is suitably added prior to or together or alternating with the addition of the acid precursor.
Alternatively, an aqueous liquid binder may be employed. This is especially suited to manufacture of products which are adjuncts for subsequent admixture with other components to form a fully formulated detergent product. Such adjuncts will usually, apart from components resulting from the liquid binder, mainly consist of one, or a small number of components normally found in detergent compositions, e.g. a surfactant or a builder such as zeolite or sodium tripolyphosphate. However, this does not preclude use of aqueous liquid binders for granulation if substantially fully formulated products. In any event, typical aqueous liquid binders include aqueous solutions of alkali metal silicates, water soluble acrylic/maleic polymers (e.g. Sokalan CP5) and the like.
In a refinement of the process of the present invention, the solid starting material may be contacted and mixed with a first portion of the liquid binder, e.g. in a low, moderate or high-shear mixer (i.e. a pre-mixer) to form a partially granulated material. The latter can then be sprayed with a second portion of the liquid binder in the low-shear granulator, to form the granulated detergent product.
In such a two-stage granulation process, it is preferred, but not absolutely necessary, for the total of liquid binder to be dosed only in the partial granulation pre-mixer and low-shear granulation steps. Conceivably, some could be dosed before the partial granulation pre-mixing and/or other earlier processing steps. Also, the content of the liquid binder could be varied between the first and second stages. The extent of granulation in the pre-mixer (i.e. partial granulation) and the amount of granulation in the low-shear granulator is preferably determined in accordance with the final product density desired. Preferred amounts of liquid binder to be dosed at each of the two stages may be varied thus:
(i) If a lower powder density is desired, i.e., 350-650 g/l
(a) 5-75% by weight of total liquid binder is preferably added in the pre-mixer; and
(b) the remaining 95-25% by weight of total liquid binder is preferably added in the low-shear granulator.
(ii) If a higher powder density is desired, i.e. 550-1300 g/l
(a) 75-95% by weight of total liquid binder is preferably added in the pre-mixer; and
(b) the remaining 25-5% by weight of total liquid binder is preferably added in the low-shear granulator.
If an initial pre-mixer is used for partial granulation, an appropriate mixer for this step is a high-shear LodigeR CB machine or a moderate-speed mixer such as a LodigeR KM machine. Other suitable equipment includes DraisR T160 series manufactured by Drais Werke GmbH, Germany; the Littleford mixer with internal chopping blades and turbine-type miller mixer having several blades on an axis of rotation. A low- or high-shear mixer granulator has a stirring action and/or a cutting action which are operated independently of one another. Preferred types of low- or high-shear mixer granulators are mixers of the FukaeR FS-G series; DiosnaR V series ex Dierks and Sohne, Germany; Pharma MatrixR ex T.K. Fielder Ltd; England. Other mixers believed to be suitable for use in the process of the invention are FujiR VG-C series ex Fuji Sangyo Co., Japan; the RotoR ex Zanchetta and Co. srl, Italy and SchugiR Flexomix granulator.
Yet another mixer suitable for use in a pre-granulation stage is the Lodige (Trade Mark) FM series (ploughshare mixers) batch mixer ex Morton Machine Co. Ltd., Scotland.
If a gas fluidisation granulator is used as the low-shear granulator, then preferably it is operated at a superficial air velocity of about 0.1-1.2 msxe2x88x921, either under positive or negative relative pressure and with an air inlet temperature ranging from xe2x88x9210xc2x0 or 5xc2x0 C. up to 80xc2x0 C., or in some cases, up to 200xc2x0 C. An operational temperature inside the bed of from ambient temperature to 60xc2x0 C. is typical. Preferably, the superficial air velocity is at least 0.45 and more preferably at least 0.5 msxe2x88x921. Preferably, the superficial air velocity is in the range 0.8-1.2 msxe2x88x921.
Optionally, a xe2x80x9clayering agentxe2x80x9d or xe2x80x9cflow aidxe2x80x9d may be introduced at any appropriate stage. This is to improve the granularity of the product, e.g. by preventing aggregation and/or caking of the granules. Any layering agent/flow aid is suitably present in an amount of 0.1 to 15% by weight of the granular product and more preferably in an amount of 0.5 to 5%.
Suitable layering agents/flow aids (whether or not introduced by recirculation) include crystalline or amorphous alkali metal silicates, aluminosilicates including zeolites, Dicamol, calcite, diatomaceous earths, silica, for example precipitated silica, chlorides such as sodium chloride, sulphates such as magnesium sulphate, carbonates such as calcium carbonate and phosphates such as sodium tripolyphospate. Mixtures of these materials may be employed as desired.
In general, additional components may be included in the liquid binder or admixed with the solid neutralising agent at an appropriate stage of the process. However, solid components can be post-dosed to the granular detergent product.
In addition to any anionic surfactant which optionally may be produced by a neutralisation step, further anionic surfactants, or nonionic surfactant as mentioned above, also, cationic, zwitterionic, amphoteric or semipolar surfactants and mixtures thereof may be added at a suitable time. In general suitable surfactants include those generally described in xe2x80x9cSurface active Agents and Detergentsxe2x80x9d Vol I by Schwartz and Perry. As mentioned above if desired, soap derived from saturated or unsaturated fatty acids having, for example having an average of C10 to C18 carbon atoms may also be present.
If present, the detergent active is suitably incorporated at a level of 5 to 40%, preferably 10 to 30% by weight of the final granular detergent product.
A complete detergent composition often contains a detergency builder. Such a builder may be introduced with the solid material and/or added subsequently as desired. The builder may also constitute a neutralising agent, for example sodium carbonate, in which case sufficient material will be employed for both functions.
Generally speaking, the total amount of detergency builder in the granular product is suitably from 5 to 95%, for example from 10 to 80%, more preferably from 15 to 65%, especially from 15 to 50% by weight.
Inorganic builders that may be present include sodium carbonate, if desired in combination with a crystallisation seed for calcium carbonate as disclosed in GB-A-1 437 950. Any sodium carbonate will need to be in excess of any used to neutralise the anionic acid precursor if the latter is added during the process.
Other suitable builders include crystalline and amorphous aluminosilicates, for example zeolites as disclosed in GB-A-1 473 201; amorphous aluminosilicates as disclosed in GB-A-1 473 202; and mixed crystalline/amorphous aluminosilicates as disclosed in GB 1 470 250; and layered silicates as disclosed in EP-B-164 514. Inorganic phosphate builders, for example, sodium orthophosphate, pyrophosphate and tripolyphosphate, may also be present, but on environmental grounds those are no longer preferred.
Aluminosilicates, whether used as layering agents and/or incorporated in the bulk of the particles may suitably be present in a total amount of from 10 to 60% and preferably an amount of from 15 to 50% by weight. The zeolite used in most commercial particulate detergent compositions is zeolite A. Advantageously, however, maximum aluminium zeolite P (zeolite MAP) described and claimed in EP-A-384 070 may be used. Zeolite MAP is an alkali metal aluminosilicated of the P type having a silicon to aluminium ratio not exceeding 1.33, preferably not exceeding 1.15, and more preferably not exceeding 1.07.
Organic builders that may be present include polycarboxylate polymers such as polyacrylates, acrylic/maleic copolymers, and acrylic phosphinates; monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono-, di- and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxymalonates, dipicolinates, hydroxyethyliminodiacetates, alkyl- and alkenylmalonates and succinates; and sulphonated fatty acid salts. A copolymer of maleic acid, acrylic acid and vinyl acetate is especially preferred as it is biodegradable and thus environmentally desirable. This list is not intended to be exhaustive.
Especially preferred organic builders are citrates, suitably used in amounts of from 5 to 30%, preferably from 10 to 25% by weight; and acrylic polymers, more especially acrylic/maleic copolymers, suitably used in amounts of from 0.5 to 15%, preferably from 1 to 10% by weight. Citrates can also be used at lower levels (eg 0.1 to 5% by weight) for other purposes. The builder is preferably present in alkali metal salt, especially sodium salt, form.
Suitably, the builder system may also comprise a crystalline layered silicate, for example, SKS-6 ex Hoechst, a zeolite, for example, zeolite A and optionally an alkali metal citrate.
The granular composition resulting from the process of the present invention may also comprise a particulate filler (or any other component which does not contribute to the wash process) which suitably comprises an inorganic salt, for example sodium sulphate and sodium chloride. The filler may be present at a level of 5 to 70% by weight of the granular product.
The present invention also encompasses a granular detergent product resulting from the process of the invention (before any post-dosing or the like). This product will have a bulk density determined by the exact nature of the process. If the process does not involve a pre-mixer to effect partial granulation, a final bulk density of 350-750 g/l can normally be expected. As mentioned above, use of a pre-mixer enables the final bulk density to be 350-650 g/l or 550-1300 g/l, respectively, according to whether option (i) or (ii) is utilised. However, granular detergent products resulting from the present invention are also characterised by their particle size ranges. Preferably not more than 10% by weight has a diameter  greater than 1.4 mm and more preferably, not more than 5% by weight of the granules are above this limit. It is also preferred that not more than 20% by weight of the granules have a diameter  greater than 1 mm. Finally, the granules can be distinguished from granules produced by other methods by mercury porosimetry. The latter technique cannot reliably determine the porosity of individual unagglomerated particles but is ideal for characterising the granules.
A fully formulated detergent composition produced according to the invention might for example comprise the detergent active and builder and optionally one or more of a flow aid, a filler and other minor ingredients such as colour, perfume, fluorescer, bleaches, enzymes.
The invention will now be illustrated by the following non-limiting examples:

Lever and Brothers Company, division of Conopco, Inc.


A hydrophilic ethylenically unsaturated macromonomer is disclosed that is prepared by the addition polymerization of addition polymerizable monomers that include monomers that have hydroxyl or amino functional groups, some of which may be subsequently reacted to provide (meth)acryl ethylenic unsaturation. The macromonomers may be used to form intraocular lenses in situ by polymerization of the macromonomers.

This application is the U.S. national stage application of International Application PCT/AU00/00916, filed Aug. 2, 2000, which international application was published on Feb. 8, 2001, as International Publication WO 01/08604 in the English language. The International Application claims priority of Australian Patent Application No. PQ 1977, filed Aug. 2, 1999.
This invention relates to hydrophilic ethylenically unsaturated macromonomers that are suitable for use in biomedical applications.
The use of polymeric prostheses and biomedical mouldings has grown rapidly in recent times. Such mouldings may be used for contact lenses or for specific ophthalmic purposes. For example, they may be used for intraocular lenses and eye bandages. They may also be used for surgical mouldings such as heart valves and artificial arteries. Other applications include wound dressings, biomedical adhesives and tissue scaffolds. Use in drug delivery is a further application.
Disease of the lens material of the eye is often in the form of cataracts. The ideal cataract procedure is considered to be one where the lens capsule bag is maintained with the cataractous lens material removed through a small opening in the capsule. The residual lens epithelial cells are removed chemically and/or with ultrasound or lasers. A biocompatible material with appropriate optical clarity, refractive index and mechanical properties is inserted into the capsular bag to restore the qualities of the crystalline lens.
There have been recent advances in methods of inserting intraocular lens. For example, U.S. Pat. No. 5,772,667 assigne to Pharmacia Lovision Inc, discloses a novel intraocular lens injector. This device compresses an intraocular lens by rolling the lens into a tight spiral. The device injects the compressed lens through a relatively small incision in the eye, approximately 2-3 millimeters in length, resulting from a phacoemulsification procedure. The intraocular lens is inserted into a receiving channel of the injector in an uncompressed state and is urged into a cylindrical passageway. As the intraocular lens advances into the cylindrical passageway, the lens will roll upon itself into a tightly rolled spiral within the confines of the cylindrical passageway. An insertion rod is inserted into an open end of the cylindrical passageway and advances the compressed lens down the passageway. As the lens exits the passageway and enters the eye, the lens will expand back to its uncompressed state.
To avoid the need for such injection devices, it has been proposed that intraocular lenses be formed in situ after being injected as a liquid flowable form into the lens capsule bag. However, while this concept is attractive in that smaller incisions would be required, it raises further difficulties in that further polymeric reactions are required to take place and these are required to be not harmful to the patient. It is also a requirement that the reaction can take place over a relatively short time under mild reaction conditions. A further requirement is that the reaction is not appreciably inhibited by oxygen. A still further requirement is that no byproducts or residues are produced that are leachable and which may have an adverse biological effect on the patient. It is desirable that the refractive index of the polymer composition for ophthalmic applications is close to 1.41 being the refractive index of the natural biological lens material.
Patent Application PCT/EP96/00246 in the name of AG Ciba-Geigy discloses water soluble cross-linkable polymers which may be crosslinked in solution to form moulded compositions. These compositions have particular application in contact lenses. The polymers are derivatives of polyvinyl alcohols. A portion of the hydroxyl groups are preferably reacted with 2-vinyl-4,4-dimethylazlactone to produce ethylenically unsaturated macromonomers.
This invention provides in one form a hydrophilic ethylenically unsaturated macromonomer comprising units of structure:
where:
m=an integer xe2x89xa71
n=an integer xe2x89xa71
r=an integer xe2x89xa71
A is a non-reacted moiety resulting from the addition polymerisation of ethylenically unsaturated monomers.
B is a moiety resulting from the additional polymerisation of ethylenically unsaturated groups that possess hydroxyl or amino groups. Examples of suitable monomers are hydroxybutylacrylate and N hydroxy ethylacrylamide
C has the following structure:
where:
R1=H, Me
X=O, NH
Z=O, NH, NR, S, CO2 where R is C1-C8 alkyl
W=linear, branched cyclic hydrocarbyl chains, polyether chains or heterochains, linear or cyclic.
It may include a mixture of moieties resulting from the use of a number of different ethylenically unsaturated monomers. The moieties are xe2x80x9cnon-reactedxe2x80x9d. By xe2x80x9cnon-reactedxe2x80x9d we mean that under the reaction conditions that will allow appropriate side groups to be introduced into the copolymer backbone these xe2x80x9cnon-reactedxe2x80x9d side groups will not form covalent bonds with other groups. Thus by this definition certain chemical groups may be included as being xe2x80x9cnon-reactedxe2x80x9d. The A moiety may be xe2x80x9cnon-reactedxe2x80x9d in that under the reaction conditions side groups will not form covalent bonds. However, the A moiety may also be xe2x80x9cnon-reactedxe2x80x9d because of the stoichiometry of the side groups. Thus it is possible for the A and B moieties to be the same and the A moiety remains unreacted because the number of equivalents of side groups is less than the equivalents of A and B. For example, A may include hydroxybutylacrylate and B may also be hydroxybutylacrylate.
The balance of the addition copolymer backbone, namely that part of the composition consisting of A and B moieties may be a random or block copolymer.
Examples of W are polyethylene glycol, polyethylene, cyclic and heterocyclic species such as phenyl rings or piperidine or mixtures of hydrophilic or hydrophobic polymers prepared by processes that allow control over end groups such as chain transfer chemistries and substituted variants thereof.
C may contain optional groups that are not ethylenically unsaturated polymerisable groups.
Preferably C is formed by suitable reaction of 2-vinyl-4,4-dimethylazlactone, acryloyl or methacryloyl chloride or related compounds with the complimentary hydroxyl or amino groups on the copolymer backbone. Other methods include suitable reaction of isocyanatoethylmethacrylate, methacrylate anhydride, acrylate anhydride, active esters of acrylates or methacrylates. These can be prepared prior to reaction with the polymer or can be prepared in situ and attached to the copolymer by conventional coupling chemistries, for example the coupling of acrylic acid to alcohol groups on the backbone copolymer using carbodiimide chemistry.
The macromonomer is hydrophilic. By hydrophilic we mean the macromonomer may be diluted 10% w/w with water without affecting the visual clarity of the macromonomer when viewed through a 100 ml measuring cylinder.
In an alternative form this invention provides a method of treating presbyopia by removing a patient""s lens from the lens capsule bag via an incision in the cornea, injecting into the lens capsule bag a macromonomer of Formula I and wherein the molecular weight of the macromonomer is in the range 10,000-300,000, and wherein the ethylenically unsaturated groups are provided by (meth) acrylamides, (meth) acrylate and styrenic moieties, and polymerising the macromonomer to a polymer having an E modulus in the range 0.01-100 kPa, preferably 0.1-10 kPa, and more preferably 0.5-5 kPa.
In a further alternative form this invention provides ethylenically unsaturated macromonomers comprising units of Formula I wherein the macromonomer or macromonomer solution has a viscosity at 25xc2x0 C. in the range 1,000-20,000 cSt, and more preferably 1,000-10,000 cSt and after polymerisation to form biocompatible polymers having an E modulus in the range 0.01-100 kPa, preferably 0.1-10 kPa and more preferably 0.5-5 kPa.
In a still further embodiment this invention provides a method of preparing intraocular lenses in situ by injecting a flowable macromonomer composition of Formula I where the macromonomer composition has a viscosity at 25xc2x0 C. in the range 1,000-20,000 cSt, more preferably 1,000-10,000 cSt and after polymerisation having to form a polymer having an E modulus in the range preferably 0.1-10 kPa and more preferably 0.5-5 kPa.
Preferably in the macromonomer the mole percentage of hydroxyl monomer is in the range 0.5-5% and more preferably 1.0-3.0%.
The preferred scheme of reaction is set out below:
Acrylamide derivatives are preferred polymerisable groups as these tend to lead to less oxygen inhibition of the composition during crosslinking. This is particularly important for in situ crosslinking as is required when the preferred compositions are used as injectable intraocular compositions.
Crosslinked gels with different mechanical properties can be produced by irradiation of the macromonomer, depending on the degree of acrylamide functionalised and water content of the macromonomer formulation. The water content is preferably 10-70% w/w and more preferably 20-60%. The elasticity of the cured macromonomer is, as measured by the E modulus, in the range 0.01-100 kPa, preferably 0.1-10 kPa and more preferably 0.5-5 kPa. The E modulus is conveniently measured by equipment such as the Bohlin controlled stress rheometer.
This crosslinking has the advantage of being rapid and relatively insensitive to inhibition by oxygen.
The crosslinking process is therefore preferably carried out in such a way that the essentially aqueous solution of the water-soluble polymer comprising crosslinking groups is free or essentially free from undesired constituents, in particular from monomeric, oligomeric or polymeric starting compounds used for the preparation of the water-soluble, cross-linkable polymer, or from by-products formed during the preparation of the water-soluble, cross-linkable polymer, and/or that the solution is used without addition of a comonomer.
In the case of photo cross-linking, it is expedient to add an initiator which is capable of initiating free-radical crosslinking and is readily soluble in water. Examples thereof are known to the person skilled in the art; suitable photoinitiators which may be mentioned specifically are benzoins, such as benzoin, benzoin ethers, such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin phenyl ether, and benzoin acetate; acetophenones, such as acetophenone, 2,2-dimethoxyacetophenone and 1,1-dichloroacetophenone; camphorquinone; benzil, benzil ketals, such as benzil dimethyl ketal and benzil diethyl ketal, anthraquinones, such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertbutylanthraquinone, 1-chloroanthraquinone and 2-amylanthraquinone; furthermore triphenylphosphine, benzoylphosphine oxides, for example 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzophenones, such as benzophenone and 4,4xe2x80x2-bis(N,N-dimethylamino)benzophenone; thioxanthones and xanthones; acridine derivatives; phenazine derivatives; quinoxaline derivatives and 1-phenyl-1,2-propanedione 2-O-benzoyl oxime; 1-aminophenyl ketones and 1-hydroxyphenyl ketones, such as 1-hydroxycyclohexylphenyl ketone, phenyl 1-hydroxyisopropyl ketone, 4-isopropylphenyl 1-hydroxyisopropyl 1-hydroxyisopropyl ketone, 2-hydroxy-1-[4-2(-hydroxyethoxy) phenyl]-2-methylpropan-1-one, 1-phenyl-2-hydroxy-2-methylpropan-1-one, and 2,2-dimethoxy-1,2-diphenylethanone, all of which are known compounds.
Particularly suitable photoinitiators, which are usually used with UV lamps as light sources, are acetophenones, such as 2,2-dialkoxybenzophenones and hydroxyphenyl ketones, in particular the initiators known under the trade names IRGACURE(copyright)2959 and DAROCURE(copyright)1173.
Another class of photoinitiators usually employed when argon ion lasers are used are benzil ketals, for example benzil dimethyl ketal.
The photoinitiators are added in effective amounts, expediently in amounts of from about 0.3 to about 2.0% by weight, in particular from 0.3 to 0.5% by weight, based on the total amount of the water-soluble, cross-linkable polymer.
The water-soluble, cross-linkable polymers which are suitable in accordance with the invention can be crosslinked by irradiation with ionising or actinic radiation, for example electron beams, X-rays, UV or VIS light, ie electromagnetic radiation or particle radiation having a wavelength in the range from about 280 to 650 nm. Also suitable are UV lamps, He/Dc, argon ion or nitrogen or metal vapour or NdYAG laser beams with multiplied frequency. It is known to the person skilled in the art that each selected light source requires selection and, if necessary, sensitisation of the suitable photoinitiator. It has been recognised that in most cases the depth of penetration of the radiation into the water-soluble, cross-linkable polymer and the rate of curing are in direct correlation with the absorption coefficient and concentration of the photoinitiator.
If desired, the crosslinking can also be initiated thermally with an appropriate thermal free radical initiator, or by redox processes well known in the art. It should be emphasised that the crosslinking can take place in a very short time in accordance with the invention, for example, in less than five minutes, preferably in less than one minute, in particular in up to 30 seconds, particularly preferably as described in the examples.
In general hydrophilic copolymers are preferably prepared by standard free radical polymerisation of dimethyl acrylamide with the active hydrogen comonomer, hydroxy butyl acrylate or N-hydroxy ethyl acrylamide, in dioxane to afford white powdery polymers. The feed ratio of monomers is varied to afford a range of copolymers with differing uptake of the hydroxyl monomer into the copolymer.
The copolymers can then be activated by the 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU) catalysed condensation in dioxane of 2-Vinyl-4,4-dimethylazlactone with the pendant hydroxy functions of the macromolecules. The resultant acrylamide active macromer is isolated by precipitation, and dried in vacuo at 40xc2x0 C. for 4 hours. The acrylamide functionalised polymer was then dissolved in an excess of water (ca. 50 wt %) 0.3 wt % of the photoinitiator Irgacure 2959 was added, and then the aqueous solution was evaporated down to the appropriate water content,
The invention will be further described by reference to preferred embodiments set out in the following examples.

Commonwealth Scientific and Industrial Research Organization