A method for preparing a thermoplastic elastomer is disclosed, said method comprising

The present invention relates to a thermoplastic elastomer composition wherein a silicone base and a hindered phenol are blended with a polyamide resin and a silicone gum contained in the base is dynamically vulcanized in the mixture.
Thermoplastic elastomers (TPEs) are polymeric materials which possess both plastic and rubbery properties. They have elastomeric mechanical properties but, unlike conventional thermoset rubbers, they can be re-processed at elevated temperatures. This re-processability is a major advantage of TPEs over chemically crosslinked rubbers since it allows recycling of fabricated parts and results in a considerable reduction of scrap.
In general, two main types of thermoplastic elastomers are known. Block copolymer thermoplastic elastomers contain xe2x80x9chardxe2x80x9d plastic segments which have a melting point or glass transition temperature above ambient as well as xe2x80x9csoftxe2x80x9d polymeric segments which have a glass transition or melt point considerably below room temperature. In these systems, the hard segments aggregate to form distinct microphases and act as physical crosslinks for the soft phase, thereby imparting a rubbery character at room temperature. At elevated temperatures, the hard segments melt or soften and allow the copolymer to flow and to be processed like an ordinary thermoplastic resin.
Alternatively, a thermoplastic elastomer referred to as a simple blend (physical blend) can be obtained by uniformly mixing an elastomeric component with a thermoplastic resin. When the elastomeric component is also cross-linked during mixing, a thermoplastic elastomer known in the art as a thermoplastic vulcanizate (TPV) results. Since the crosslinked elastomeric phase of a TPV is insoluble and non-flowable at elevated temperature, TPVs generally exhibit improved oil and solvent resistance as well as reduced compression set relative to the simple blends.
Typically, a TPV is formed by a process known as dynamic vulcanization, wherein the elastomer and the thermoplastic matrix are mixed and the elastomer is cured with the aid of a crosslinking agent and/or catalyst during the mixing process. A number of such TPVs are known in the art, including some wherein the crosslinked elastomeric component can be a silicone polymer while the thermoplastic component is an organic, non-silicone polymer (i.e., a thermoplastic silicone vulcanizate or TPSiV). In such a material, the elastomeric component can be cured by various mechanisms, but it has been shown that the use of a non-specific radical initiator, such as an organic peroxide, can also result in at least a partial cure of the thermoplastic resin itself, thereby reducing or completely destroying ability to re-process the composition (i.e., it no longer is a thermoplastic). In other cases, the peroxide can lead to the partial degradation of the thermoplastic resin. To address these problems, elastomer-specific crosslinkers, such as organohydrido silicon compounds, can be used to cure alkenyl-functional silicone elastomers.
Arkles, in U.S. Pat. No. 4,500,688, discloses semi-interpenetrating networks (IPN) wherein a vinyl-containing silicone fluid having a viscosity of 500 to 100,000 cS is dispersed in a conventional thermoplastic resin. Arkles only illustrates these IPNs at relatively low levels of silicone. The vinyl-containing silicone is vulcanized in the thermoplastic during melt mixing according to a chain extension or crosslinking mechanism which employs a silicon hydride-containing silicone component. This disclosure states that the chain extension procedure results in a thermoplastic composition when the vinyl-containing silicone has 2 to 4 vinyl groups and the hydride-containing silicone has 1 to 2 times the equivalent of the vinyl functionality. On the other hand, silicones which predominantly undergo crosslinking reaction result in thermoset compositions when the vinyl-containing silicone has 2 to 30 vinyl groups and the hydride-containing silicone has 2 to 10 times the equivalent of the vinyl functionality. Typical thermoplastics mentioned include polyamides, polyurethanes, styrenics, polyacetals and polycarbonates. This disclosure is expanded by Arkles in U.S. Pat. No. 4,714,739 to include the use of hybrid silicones which contain unsaturated groups and are prepared by reacting a hydride-containing silicone with an organic polymer having unsaturated functionality. Although Arkles discloses a silicone fluid content ranging from 1 to 40 weight percent (1 to 60% in the case of the ""739 patent), there is no suggestion of any criticality as to these proportions or to the specific nature of the organic resin.
Publication WO 96/01291 to Advanced Elastomer Systems discloses thermoplastic elastomers having improved resistance to oil and compression set. These systems are prepared by first forming a cured rubber concentrate wherein a curable elastomeric copolymer is dispersed in a polymeric carrier not miscible therewith, the curable copolymer being dynamically vulcanized while this combination is mixed. The resulting rubber concentrate is, in turn, blended with an engineering thermoplastic to provide the desired TPE. Silicone rubber is disclosed as a possible elastomeric component, but no examples utilizing such a silicone are provided. Further, this publication specifically teaches that the polymeric carrier must not react with the cure agent for the curable copolymer.
Crosby et al. in U.S. Pat. No. 4,695,602 teach composites wherein a silicone semi-IPN vulcanized via a hydrosilation reaction is dispersed in a fiber-reinforced thermoplastic resin having a high flexural modulus. The silicones employed are of the type taught by Arkles, cited supra, and the composites are said to exhibit improved shrinkage and warpage characteristics relative to systems which omit the IPN.
Ward et al., in U.S. Pat. No. 4,831,071, disclose a method for improving the melt integrity and strength of a high modulus thermoplastic resin to provide smooth-surfaced, high tolerance profiles when the modified resin is melt-drawn. As in the case of the disclosures to Arkles et al., cited supra, a silicone mixture is cured via a hydrosilation reaction after being dispersed in the resin to form a semi-IPN, and the resulting composition is subsequently extruded and melt-drawn.
U.S. Pat. No. 6,013,715 to Gornowicz et al. teaches the preparation of TPSiV elastomers wherein a silicone gum (or filled silicone gum) is dispersed in either a polyolefin or a poly(butylene terephthalate) resins and the gum is subsequently dynamically vulcanized therein via a hydrosilation cure system. The resulting elastomers exhibit an ultimate elongation at break of at least 25% and have significantly improved mechanical properties over the corresponding simple blends of resin and silicone gum in which the gum is not cured (i.e., physical blends). This is, of course, of great commercial significance since the vulcanization procedure, and the cure agents required therefor, add to both the complexity as well as the expense of the preparation and vulcanization would be avoided in many applications if essentially identical mechanical properties could be obtained without its employ.
In a copending application (Ser. No. 09/393029 filed on Sep. 9, 1999) now U.S. Pat. No. 6,281,286 we disclose that the impact resistance of polyester and polyamide resins can be greatly augmented by preparing a thermoplastic silicone vulcanizate therefrom wherein the elastomeric component is a silicone rubber base which comprises a silicone gum and a silica filler and the weight ratio of the base to the resin ranges from 10:90 to 35:65. Although the resulting thermoplastic materials have improved impact resistance, they do not exhibit sufficiently low modulus to be useful as elastomers.
While the above publications disclose the preparation of compositions using various thermoplastic resins as the matrix and a dispersed phase consisting of a silicone oil or elastomer which is dynamically vulcanized therein, neither these references, nor any art known to applicants, teach the preparation of TPSiV elastomers based on polyamide resins having superior tensile and elongation properties.
It has now been discovered that TPSiV elastomers of the type described in above cited U.S. Pat. No. 6,013,715 can be prepared from certain polyamide resins wherein the silicone component is a base comprising a diorganopolysiloxane gum and a reinforcing filler. As in the case of the teachings of U.S. Pat. No. 6,013,715, the elastomers disclosed herein generally also have good appearance, have an elongation of at least 25% and have a tensile strength and/or elongation at least 25% greater than that of the corresponding simple (physical) blend wherein the diorganopolysiloxane is not cured. However, it has been surprisingly found that such properties are significantly enhanced when a minor portion of a hindered phenol compound is incorporated in the formulation. Moreover, inclusion of the hindered phenol apparently also results in a lower melt viscosity of the instant thermoplastic elastomer vulcanizates, as reflected by process torque measurements during mixing. This reduction is of considerable value to fabricators since the elastomers of the present invention can be more readily processed in conventional equipment (e.g., extruders, injection molders) and results in lower energy consumption. Furthermore, unlike the teachings of Arkles, cited supra, and others, the silicone component which is dispersed in the thermoplastic resin, and dynamically cured therein, must include a high molecular weight gum, rather than a low viscosity silicone fluid, the latter resulting in compositions having poor uniformity.
The present invention, therefore, relates to a thermoplastic elastomer prepared by
(I) mixing
(A) a rheologically stable polyamide resin having a melting point or glass transition temperature of 25xc2x0 C. to 275xc2x0 C.,
(B) a silicone base comprising
(Bxe2x80x2) 100 parts by weight of a diorganopolysiloxane gum having a plasticity of at least 30 and having an average of at least 2 alkenyl groups in its molecule and
(Bxe2x80x3) 5 to 200 parts by weight of a reinforcing filler,
xe2x80x83the weight ratio of said silicone base to said polyamide resin being greater than 35:65 to 85:15,
(C) 0.1 to 5 parts by weight of a hindered phenol compound for each 100 parts by weight of said polyamide and said silicone base,
(D) an organohydrido silicon compound which contains an average of at least 2 silicon-bonded hydrogen groups in its molecule and
(E) a hydrosilation catalyst, components (D) and (E) being present in an amount sufficient to cure said diorganopolysiloxane (Bxe2x80x2); and
(II) dynamically curing said diorganopolysiloxane (Bxe2x80x2),
wherein said thermoplastic elastomer has an elongation of at least 25%.
The invention further relates to a thermoplastic elastomer which is prepared by the above method.
Component (A) of the present invention is a thermoplastic polyamide resin. These resins are well known by the generic term xe2x80x9cnylonxe2x80x9d and are long chain synthetic polymers containing amide (i.e., xe2x80x94C(O)xe2x80x94NHxe2x80x94) linkages along the main polymer chain. For the purposes of the present invention, the polyamide resin has a melt point (m.p.) or glass transition temperature (Tg) of room temperature (i.e., 25xc2x0 C.) to 275xc2x0 C. Attempts to prepare TPSiV elastomers from polyamides having higher melt points (e.g., nylon 4/6) resulted in poor physical properties, the ultimate elongation of such products being less than the required 25% according to the present invention. Furthermore, for the purposes of the present invention, the polyamide resin must be dry, this preferably being accomplished by passing a dry, inert gas over resin pellets or powder at elevated temperatures. Again, it has been found that TPSiVs prepared from as-supplied resins often do not meet the elongation requirements of the present invention. The degree of drying consistent with acceptable properties and processing depends on the particular polyamide and its value is generally recommended by the manufacturer or may be determined by a few simple experiments. It is generally preferred that the polyamide resin contains no more than about 0.1 weight percent of moisture. Finally, the polyamide must also be theologically stable under the mixing conditions required to prepare the TPSiV elastomer, as described infra. This stability is evaluated on the neat resin at the appropriate processing temperature and a change of more than 20% in melt viscosity (mixing torque) within the time generally required to prepare the corresponding TPSiVs (e.g., 10 to 30 minutes in a bowl mixer) indicates that the resin is outside the scope of the present invention. Thus, for example, a dried nylon 11 sample having a m.p. of 198xc2x0 C. was mixed in a bowl mixer under a nitrogen gas purge at about 210 to 220xc2x0 C. for about 15 minutes and the observed mixing torque increased by approximately 200%. Such a polyamide resin is not a suitable candidate for the instant method.
Other than the above mentioned limitations, resin (A) can be any thermoplastic crystalline or amorphous high molecular weight solid homopolymer, copolymer or terpolymer having recurring amide units within the polymer chain. In copolymer and terpolymer systems, more than 50 mole percent of the repeat units are amide-containing units. Examples of suitable polyamides are polylactams such as nylon 6, polyenantholactam (nylon 7), polycapryllactam (nylon 8), polylauryllactam (nylon 12), and the like; homopolymers of aminoacids such as polypyrrolidinone (nylon 4); copolyamides of dicarboxylic acid and diamine such as nylon 6/6, polyhexamethyleneazelamide (nylon 6/9), polyhexamethylene-sebacamide (nylon 6/10), polyhexamethyleneisophthalamide (nylon 6,I), polyhexamethylenedodecanoic acid (nylon 6/12) and the like; aromatic and partially aromatic polyamides; copolyamides such as copolymers of caprolactam and hexamethyleneadipamide (nylon 6/6,6), or a terpolyamide, e.g. nylon 6/6,6/6,10; block copolymers such as polyether polyamides; or mixtures thereof. Preferred polyamide resins are nylon 6, nylon 12, nylon 6/12 and nylon 6/6.
Silicone base (B) is a uniform blend of a diorganopolysiloxane gum (Bxe2x80x2) a reinforcing filler (Bxe2x80x3).
Diorganopolysiloxane (Bxe2x80x2) is a high consistency (gum) polymer or copolymer which contains at least 2 alkenyl groups having 2 to 20 carbon atoms in its molecule. The alkenyl group is specifically exemplified by vinyl, allyl, butenyl, pentenyl, hexenyl and decenyl. The position of the alkenyl functionality is not critical and it may be bonded at the molecular chain terminals, in non-terminal positions on the molecular chain or at both positions. It is preferred that the alkenyl group is vinyl or hexenyl and that this group is present at a level of 0.001 to 3 weight percent, preferably 0.01 to 1 weight percent, in the diorganopolysiloxane gum.
The remaining (i.e., non-alkenyl) silicon-bonded organic groups in component (Bxe2x80x2) are independently selected from hydrocarbon or halogenated hydrocarbon groups which contain no aliphatic unsaturation. These may be specifically exemplified by alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl and hexyl; cycloalkyl groups, such as cyclohexyl and cycloheptyl; aryl groups having 6 to 12 carbon atoms, such as phenyl, tolyl and xylyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl and phenethyl; and halogenated alkyl groups having 1 to 20 carbon atoms, such as 3,3,3-trifluoropropyl and chloromethyl. It will be understood, or course, that these groups are selected such that the diorganopolysiloxane gum (Bxe2x80x2) has a glass temperature (or melt point) which is below room temperature and the gum is therefore elastomeric. Methyl preferably makes up at least 50, more preferably at least 90, mole percent of the non-unsaturated silicon-bonded organic groups in component (Bxe2x80x2).
Thus, polydiorganosiloxane (Bxe2x80x2) can be a homopolymer or a copolymer containing such organic groups. Examples include gums comprising dimethylsiloxy units and phenylmethylsiloxy units; dimethylsiloxy units and diphenylsiloxy units; and dimethylsiloxy units, diphenylsiloxy units and phenylmethylsiloxy units, among others. The molecular structure is also not critical and is exemplified by straight-chain and partially branched straight-chain, linear structures being preferred.
Specific illustrations of organopolysiloxane (Bxe2x80x2) include:
trimethylsiloxy-endblocked dimethylsiloxane-methylhexenylsiloxane copolymers;
dimethylhexenlylsiloxy-endblocked dimethylsiloxane-methylhexenylsiloxane copolymers;
trimethylsiloxy-endblocked dimethylsiloxane-methylvinylsiloxane copolymers;
trimethylsiloxy-endblocked methylphenylsiloxane-dimethylsiloxane-methylvinylsiloxane copolymers; dimethylvinylsiloxy-endblocked dimethylpolysiloxanes;
dimethylvinylsiloxy-endblocked dimethylsiloxane-methylvinylsiloxane copolymers;
dimethylvinylsiloxy-endblocked methylphenylpolysiloxanes;
dimethylvinylsiloxy-endblocked methylphenylsiloxane-dimethylsiloxane-methylvinylsiloxane copolymers; and similar copolymers wherein at least one end group is dimethylhydroxysiloxy. Preferred systems for low temperature applications include methylphenylsiloxane-dimethylsiloxane-methylvinylsiloxane copolymers and diphenylsiloxane-dimethylsiloxane-methylvinylsiloxane copolymers, particularly wherein the molar content of the dimethylsiloxane units is about 93%.
Component (Bxe2x80x2) may also consist of combinations of two or more organopolysiloxanes. Most preferably, component (Bxe2x80x2) is a polydimethylsiloxane homopolymer which is terminated with a vinyl group at each end of its molecule or is such a homopolymer which also contains at least one vinyl group along its main chain.
For the purposes of the present invention, the molecular weight of the diorganopolysiloxane gum is sufficient to impart a Williams plasticity number of at least about 30 as determined by the American Society for Testing and Materials (ASTM) test method 926. The plasticity number, as used herein, is defined as the thickness in millimetersxc3x97100 of a cylindrical test specimen 2 cm3 in volume and approximately 10 mm in height after the specimen has been subjected to a compressive load of 49 Newtons for three minutes at 25xc2x0 C. When the plasticity of this component is less than about 30, as in the case of the low viscosity fluid siloxanes employed by Arkles, cited supra, the TPSiVs prepared by dynamic vulcanization according to the instant method exhibit poor uniformity such that at high silicone contents (e.g., 50 to 70 weight percent) there are regions of essentially only silicone and those of essentially only thermoplastic resin, and the blends are weak and friable. The gums of the present invention are considerably more viscose than the silicone fluids employed in the prior art. For example, silicones contemplated by Arkles, cited supra, have an upper viscosity limit of 100,000 cS (0.1 m2/s) and, although the plasticity of fluids of such low viscosity are not readily measured by the ASTM D 926 procedure, it was determined that this corresponds to a plasticity of approximately 24. Although there is no absolute upper limit on the plasticity of component (Bxe2x80x2), practical considerations of processability in conventional mixing equipment generally restrict this value. Preferably, the plasticity number should be about 100 to 200, most preferably about 120 to 185.
Methods for preparing high consistency unsaturated group-containing polydiorganosiloxanes are well known and they do not require a detailed discussion in this specification. For example, a typical method for preparing an alkenyl-functional polymer comprises the base-catalyzed equilibration of cyclic and/or linear diorganopolysiloxanes in the presence of similar alkenyl-functional species.
Component (Bxe2x80x3) is a finely divided filler which is known to reinforce diorganopolysiloxane (Bxe2x80x2) and is preferably selected from finely divided, heat stable minerals such as fumed and precipitated forms of silica, silica aerogels and titanium dioxide having a specific surface area of at least about 50 m2/gram. The fumed form of silica is a preferred reinforcing filler based on its high surface area, which can be up to 450 m2/gram and a fumed silica having a surface area of 50 to 400 m2/g, most preferably 200 to 380 m2/g, is highly preferred. Preferably, the fumed silica filler is treated to render its surface hydrophobic, as typically practiced in the silicone rubber art. This can be accomplished by reacting the silica with a liquid organosilicon compound which contains silanol groups or hydrolyzable precursors of silanol groups. Compounds that can be used as filler treating agents, also referred to as anti-creeping agents or plasticizers in the silicone rubber art, include such ingredients as low molecular weight liquid hydroxy- or alkoxy-terminated polydiorganosiloxanes, hexaorganodisiloxanes, cyclodimethylsilazanes and hexaorganodisilazanes. It is preferred that the treating compound is an oligomeric hydroxy-terminated diorganopolysiloxane having an average degree of polymerization (DP) of 2 to about 100, more preferably about 2 to about 10 and it is used at a level of about 5 to 50 parts by weight for each 100 parts by weight of the silica filler. When component (Bxe2x80x2) is the preferred vinyl-functional or hexenyl-functional polydimethylsiloxane, this treating agent is preferably a hydroxy-terminated polydimethylsiloxane.
For the purposes of the present invention, 5 to 200 parts by weight, preferably 5 to 150 and most preferably 20 to 100 parts by weight, of the reinforcing filler (Bxe2x80x3) are uniformly blended with 100 parts by weight of gum (Bxe2x80x2) to prepare silicone base (B). This blending is typically carried out at room temperature using a two-roll mill, internal mixer or other suitable device, as well known in the silicone rubber art. Alternatively, the silicone base can be formed in-situ during mixing prior to dynamic vulcanization of the gum, as further described infra. In the latter case, the temperature of mixing is kept below the softening point or melting point of the polyamide resin until the reinforcing filler is well dispersed in the diorganopolysiloxane gum.
Hindered phenol (C) is an organic compound having at least one group of the structure
in its molecule. In the above formula, R is an alkyl group having one to four carbon atoms and Rxe2x80x2 is a hydrocarbon group having four to eight carbon atoms. For the purposes of the present invention, a group according to formula (i) can be attached to hydrogen to form a 1,5-di-organophenol. Preferably, one to four of these groups are attached to an organic moiety of corresponding valence such that the contemplated compound has a molecular weight (MW) of less than about 1,500. Most preferably, four such groups are present in component (C) and this compound has a molecular weight of less than 1,200. This monovalent (or polyvalent) organic moiety can contain heteroatoms such as oxygen, nitrogen, phosphorous and sulfur. The Rxe2x80x2 groups in the above formula may be illustrated by t-butyl, n-pentyl, butenyl, hexenyl, cyclopentyl, cyclohexyl and phenyl. It is preferred that both R and Rxe2x80x2 are t-butyl.
Non-limiting specific examples of component (C) include various hindered phenols marketed by Ciba Specialty Chemicals Corporation under the tradename Irganox(trademark)M:
Irganox(trademark) 1076=octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate,
Irganox(trademark) 1035=thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate),
Irganox(trademark) MD1024=1,2-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazine,
Irganox(trademark) 1330=1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,
Irganox(trademark) 1425 WL=calcium bis(monoethyl(3,5-di-tert-butyl-4-hydroxybenzyl)phosphonate) and
Irganox(trademark) 3114=1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione.
Preferred hindered phenols are Irganox(trademark) 245{triethyleneglycol bis (3-(3xe2x80x2-tert-butyl-4xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)propionate)}, Irganox(trademark) 1098{N,Nxe2x80x2-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide)} and Irganox(trademark) 1010{tetrakis(methylene(3,5-di-tert-butyl-4-hydroxy-hydrocinnamate))methane}.
From 0.1 to 5 parts by weight of hindered phenol (C) are employed for each 100 parts by weight of polyamide (A) plus silicone base (B). Preferably 0.1 to 0.75 parts by weight, more preferably 0.475 to 0.525 parts by weight, of (C) are added for each 100 parts by weight of (A) plus (B).
The organohydrido silicon compound (D) is a crosslinker (cure agent) for diorganopolysiloxane (Bxe2x80x2) of present composition and is an organopolysiloxane which contains at least 2 silicon-bonded hydrogen atoms in each molecule, but having at least about 0.1 weight percent hydrogen, preferably 0.2 to 2 and most preferably 0.5 to 1.7, percent hydrogen bonded to silicon. Those skilled in the art will, of course, appreciate that either component (Bxe2x80x2) or component (D), or both, must have a functionality greater than 2 if diorganopolysiloxane (Bxe2x80x2) is to be cured (i.e., the sum of these functionalities must be greater than 4 on average). The position of the silicon-bonded hydrogen in component (D) is not critical, and it may be bonded at the molecular chain terminals, in non-terminal positions along the molecular chain or at both positions. The silicon-bonded organic groups of component (D) are independently selected from any of the hydrocarbon or halogenated hydrocarbon groups described above in connection with diorganopolysiloxane (Bxe2x80x2), including preferred embodiments thereof. The molecular structure of component (D) is also not critical and is exemplified by straight-chain, partially branched straight-chain, branched, cyclic and network structures, linear polymers or copolymers being preferred, this component should be compatible with diorganopolysiloxane (Bxe2x80x2) (i.e., it is effective in curing component (Bxe2x80x2)).
Component (D) is exemplified by the following:
low molecular siloxanes, such as PhSi(OSiMe2H)3;
trimethylsiloxy-endblocked methylhydridopolysiloxanes;
trimethylsiloxy-endblocked dimethylsiloxane-methylhydridosiloxane copolymers;
dimethylhydridosiloxy-endblocked dimethylpolysiloxanes;
dimethylhydrogensiloxy-endblocked methylhydrogenpolysiloxanes;
dimethylhydridosiloxy-endblocked dimethylsiloxane-methylhydridosiloxane copolymers;
cyclic methylhydrogenpolysiloxanes;
cyclic dimethylsiloxane-methylhydridosiloxane copolymers;
tetrakis(dimethylhydrogensiloxy)silane;
silicone resins composed of (CH3)2HSiO1/2, (CH3)3SiO1/2, and SiO4/2 units; and
silicone resins composed of (CH3)2HSiO1/2, (CH3)3SiO1/2,
CH3Si O3/2, PhSiO3/2 and SiO4/2 units,
wherein Me and Ph hereinafter denote methyl and phenyl groups, respectively.
Particularly preferred organohydrido silicon compounds are polymers or copolymers comprising RHSiO units ended with either R3SiO1/2 or HR2SiO1/2, wherein R is independently selected from alkyl groups having 1 to 20 carbon atoms, phenyl or trifluoropropyl, preferably methyl. It is also preferred that the viscosity of component (D) is about 0.5 to 1,000 mPa-s at 25xc2x0 C., preferably 2 to 500 mPa-s. Further, this component preferably has 0.5 to 1.7 weight percent hydrogen bonded to silicon. It is highly preferred that component (D) is selected from a polymer consisting essentially of methylhydridosiloxane units or a copolymer consisting essentially of dimethylsiloxane units and methylhydridosiloxane units, having 0.5 to 1.7 percent hydrogen bonded to silicon and having a viscosity of 2 to 500 mPa-s at 25xc2x0 C. It is understood that such a highly preferred system will have terminal groups selected from trimethylsiloxy or dimethylhdridosiloxy groups.
Component (D) may also be a combination of two or more of the above described systems. The organohydrido silicon compound (D) is used at a level such that the molar ratio of SiH therein to Si-alkenyl in component (Bxe2x80x2) is greater than 1 and preferably below about 50, more preferably 3 to 30, most preferably 4 to 20.
These SiH-functional materials are well known in the art and many of them are commercially available.
Hydrosilation catalyst (E) is a catalyst that accelerates the cure of diorganopolysiloxane (Bxe2x80x2) in the present composition. This hydrosilation catalyst is exemplified by platinum catalysts, such as platinum black, platinum supported on silica, platinum supported on carbon, chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum/olefin complexes, platinum/alkenylsiloxane complexes, platinum/beta-diketone complexes, platinum/phosphine complexes and the like; rhodium catalysts, such as rhodium chloride and rhodium chloride/di(n-butyl)sulfide complex and the like; and palladium catalysts, such as palladium on carbon, palladium chloride and the like. Component (E) is preferably a platinum-based catalyst such as chloroplatinic acid; platinum dichloride; platinum tetrachloride; a platinum complex catalyst produced by reacting chloroplatinic acid and divinyltetramethyldisiloxane which is diluted with dimethylvinylsiloxy endblocked polydimethylsiloxane, prepared according to U.S. Pat. No. 3,419,593 to Willing; and a neutralized complex of platinous chloride and divinyltetramethyldisiloxane, prepared according to U.S. Pat. No. 5,175,325 to Brown et al. , these patents being hereby incorporated by reference. Most preferably , catalyst (E) is a neutralized complex of platinous chloride and divinyltetramethyldisiloxane.
Component (E) is added to the present composition in a catalytic quantity sufficient to promote the reaction of components (Bxe2x80x2) and (D) and thereby cure the diorganopolysiloxane to form an elastomer. The catalyst is typically added so as to provide about 0.1 to 500 parts per million (ppm) of metal atoms based on the total weight of the thermoplastic elastomer composition, preferably 0.25 to 100 ppm.
In addition to the above mentioned major components (A) through (E), a minor amount (i.e., less than about 40 weight percent of the total composition, preferably less than 20 weight percent) of an optional additive (F) can be incorporated in the compositions of the present invention. This optional additive can be illustrated by, but not limited to, reinforcing fillers for polyamide resins, such as glass fibers and carbon fibers; extending fillers such as quartz, calcium carbonate, and diatomaceous earth; pigments such as iron oxide and titanium oxide, electrically conducting fillers such as carbon black and finely divided metals, heat stabilizers such as hydrated cerric oxide, antioxidants, flame retardants such as halogenated hydrocarbons, alumina trihydrate, magnesium hydroxide, organophosphorous compounds and other fire retardant (FR) materials. A preferred FR additive is calcium silicate particulate, preferably a wollastonite having an average particle size of 2 to 30 xcexcm. Further, this optional component can be a plasticizers for the silicone gum component, such as polydimethylsiloxane oil, and/or a plasticizer for the polyamide component. Examples of the latter include phthalate esters such as dicyclohexyl phthalate, dimethyl phthalate, dioctyl phthalate, butyl benzyl phthalate and benzyl phthalate; trimellitate esters such as C1-C9 alkyl trimellitate; sulfonamides such as N-cyclohexyl-p-toluenesulfonamide, N-ethyl-o,p-toluenesulfonamide and o-toluenesulfonamide, and liquid oligomeric plasticizers. Preferred plasticizers are liquids with low volatility to avoid emissions of plasticizer at the common melt temperatures of polyamides.
The above additives are typically added to the final thermoplastic composition after dynamic cure, but they may also be added at any point in the preparation provided they do not interfere with the dynamic vulcanization mechanism. Of course, the above additional ingredients are only used at levels which do not significantly detract from the desired properties of the final composition.
According to the method of the present invention, the thermoplastic elastomer is prepared by thoroughly dispersing silicone base (B) and hindered phenol (C) in polyamide (A) and dynamically vulcanizing the diorganopolysiloxane using organohydrido silicon compound (D) and catalyst (E). For the purposes of the present invention, the weight ratio of silicone base (B) to polyamide resin (A) is greater than 35:65. It has been found that when this ratio is 35:65 or less, the resulting vulcanizate generally has a modulus more resembling the polyamide resin than a thermoplastic elastomer. On the other hand, the above mentioned ratio should be no more than about 85:15 since the compositions tend to be weak and resemble cured silicone elastomers above this value. Notwithstanding this upper limit, the maximum ratio of (B) to (A) for any given combination of components is also limited by processability considerations since too high a silicone base content results in at least a partially crosslinked continuous phase which is no longer thermoplastic. For the purposes of the present invention, this practical limit is readily determined by routine experimentation and represents the highest level of component (B) which allows the TPSiV to be compression molded. It is, however, preferred that the final thermoplastic elastomer can also be readily processed in other conventional plastic operations, such as injection molding and extrusion and, in this case, the weight ratio of components (B) to (A) should be no more than about 75:25. Such a preferred thermoplastic elastomer which is subsequently re-processed generally has a tensile strength and elongation which are within 10% of the corresponding values for the original TPSiV (i.e., the thermoplastic elastomer is little changed by re-processing). Although the amount of silicone base consistent with the above mentioned requirements depends upon the particular polyamide resin and other components selected, it is preferred that the weight ratio of components (B) to (A) is 40:60 to 75:25, more preferably 40:60 to 70:30.
Mixing is carried out in any device which is capable of uniformly dispersing the components in the polyamide resin, such as an internal mixer or a twin-screw extruder, the latter being preferred for commercial preparations. The temperature is preferably kept as low as practical consistent with good mixing so as not to degrade the resin. Depending upon the particular system, order of mixing is generally not critical and, for example, components (A), (C) and (D) can be added to (B) at a temperature above the softening point (melt point) of (A), catalyst (E) then being introduced to initiate dynamic vulcanization. However, components (B) through (D) should be well dispersed in resin (A) before dynamic vulcanization begins. As previously mentioned, it is also contemplated that the silicone base can be formed in-situ. For example, the reinforcing filler may be added to a mixer already containing the polyamide resin and diorganopolysiloxane gum at a temperature below the softening point (melt point) of the resin to thoroughly disperse the filler in the gum. The temperature is then raised to melt the resin, the other ingredients are added and mixing/dynamic vulcanization are carried out. Optimum temperatures, mixing times and other conditions of the mixing operation depend upon the particular resin and other components under consideration and these may be determined by routine experimentation by those skilled in the art. It is, however, preferred to carry out the mixing and dynamic vulcanization under a dry, inert atmosphere (i.e., one that does not adversely react with the components or otherwise interfere with the hydrosilation cure), such as dry nitrogen, helium or argon. It has been observed that there is actually a preferred dry gas flow rate with respect to mechanical properties of the final TPSiV as well as the melt viscosity thereof (see examples, infra).
When the melting point or glass temperature of the polyamide is considerably higher than room temperature (e.g., greater than 100xc2x0 C.), a preferred procedure comprises preparing a pre-mix by blending dried polyamide resin (A), silicone base (B), hindered phenol (C) and organohydrido silicon compound (D) below the melting point/glass temperature of the resin (e.g., at ambient conditions). This pre-mix is then melted in a bowl mixer or internal mixer using a dry inert gas purge and at a controlled temperature which is just above the melt point to about 35xc2x0 C. above the melt point of the polyamide (e.g., 210xc2x0 C. to 215xc2x0 C. for nylon 12 which, depending on molecular weight, has a melt point of about 175xc2x0 C.-180xc2x0 C.) and catalyst (E) is mixed therewith. Mixing is continued until the melt viscosity (mixing torque) reaches a steady state value, thereby indicating that dynamic vulcanization of the diorganopolysiloxane of component (B) is complete.
As noted above, in order to be within the scope of the present invention, the tensile strength or elongation, or both, of the TPSiVs must be at least 25% greater than that of a corresponding simple blend. A further requirement of the invention is that the TPSiV has at least 25% elongation, as determined by the test described infra. In this context, the term xe2x80x9csimple blendxe2x80x9d denotes a composition wherein the weight proportions of resin (A), base (B) and hindered phenol (C) are identical to the proportions in the TPSiV, but no cure agents are employed (i.e., either component (D) or (E), or both, are omitted and the gum is therefore not cured). In order to determine if a particular composition meets the above criterion, the tensile strength of the TPSiV is measured on dumbbells having a length of 25.4 mm and a width of 3.2 mm and a typical thickness of 1 to 2 mm, according to ASTM method D 412, at an extension rate of 50 mm/min. At least three such samples are evaluated and the results averaged after removing obvious low readings due to sample inhomogeneity (e.g., such as voids, contamination or inclusions). These values are then compared to the corresponding average tensile and elongation values of a sample prepared from the simple blend composition. When at least a 25% improvement in tensile and/or elongation over the simple blend is not realized there is no benefit derived from the dynamic vulcanization and such TPSiVs are not within the scope of the present invention.
The thermoplastic elastomer prepared by the above described method can then be processed by conventional techniques, such as extrusion, vacuum forming, injection molding, blow molding, overmolding or compression molding. Moreover, these compositions can be re-processed (recycled) with little or no degradation of mechanical properties.
The novel thermoplastic elastomers of the present invention can be used for fabricating wire and cable insulation, electrical connectors, automotive and appliance components such as belts, hoses, air ducts, boots, bellows, gaskets and fuel line components, architectural seals, bottle closures, medical devises, sporting goods and general rubber parts.

Thermoplastic silicone elastomers formed from nylon resins

Abstract: (I) mixing

Abstract: (B) a silicone base comprising

Abstract: (Bxe2x80x2) 100 parts by weight of a diorganopolysiloxane gum having a plasticity of at least 30 and having an average of at least 2 alkenyl radicals in its molecule and

Abstract: wherein at least one property of the thermoplastic elastomer selected from tensile strength or elongation is at least 25% greater than the respective property for a corresponding simple blend wherein said diorganopolysiloxane is not cured and said thermoplastic elastomer has an elongation of at least 25%.


The present invention is directed to an expandable stent which is relatively flexible along its longitudinal axis to facilitate delivery through tortuous body lumens, but which is stiff and stable enough radially in an expanded condition to maintain the patency of a body lumen such as an artery when implanted therein. The struts of the present invention have a specific trapezoidal, triangular or a reduced radii configuration projecting radially outward that functions to reduce the forces necessary to penetrate the vessel wall thereby minimizing trauma or damage imparted to the wall during deployment. In addition, this design feature of the present invention helps secure the expanded stent so that it does not move once it is implanted and furthermore, minimizes projections into the blood stream.

In general, the present invention relates to percutaneous transluminal devices and methods which are used to treat obstructed (sclerotic) vessel lumina in humans. In particular, the present invention is an improved stent that requires low expansion pressure for deployment and improved embedding of the struts within the vessel wall.
Cardiovascular disease is commonly accepted as being one of the most serious health risks facing our society today. Diseased and obstructed coronary arteries can restrict the flow of blood and cause tissue ischemia and necrosis. While the exact etiology of sclerotic cardiovascular disease is still in question, the treatment of narrowed coronary arteries is more defined. Surgical construction of coronary artery bypass grafts (CABG) is often the method of choice when there are several diseased segments in one or multiple arteries. Conventional open heart surgery is, of course, very invasive and traumatic for patients undergoing such treatment. In many cases, less traumatic, alternative methods are available for treating cardiovascular disease percutaneously. These alternate treatment methods generally employ various types of balloons (angioplasty) or excising devices (atherectomy) to remodel or debulk diseased vessel segments. A further alternative treatment method involves percutaneous, intraluminal installation of one or more expandable, tubular stents or prostheses in sclerotic lesions. Intraluminal endovascular prosthetic grafting is an alternative to conventional vascular surgery. Intraluminal endovascular grafting involves the percutaneous insertion into a blood vessel of a tubular prosthetic graft and its delivery via a catheter to the desired location within the vascular system. The alternative approach to percutaneous revascularization is the surgical placement of vein, artery, or other by-pass segments from the aorta onto the coronary artery, requiring open heart surgery, and significant morbidity and mortality. Advantages of the percutaneous revascularization method over conventional vascular surgery include obviating the need for surgically exposing, removing, replacing, or by-passing the defective blood vessel, including heart-lung by-pass, opening the chest, and general anesthesia.
Stents or prostheses are known in the art as implants which function to maintain patency of a body lumen in humans and especially to such implants for use in blood vessels. They are typically formed from a cylindrical metal mesh which expand when internal pressure is applied. Alternatively, they can be formed of wire wrapped into a cylindrical shape. The present invention relates to an improved stent design which by its specifically configured struts can facilitate the deployment and embedment of the stent within a vessel and is constructed from a manufacturing process which provides a controlled and superior stress yield point and ultimate tensile characteristics.
Stents or prostheses can be used in a variety of tubular structures in the body including, but not limited to, arteries and veins, ureters, common bile ducts, and the like. Stents are used to expand a vascular lumen or to maintain its patency after angioplasty or atherectomy procedures, overlie an aortic dissecting aneurysm, tack dissections to the vessel wall, eliminate the risk of occlusion caused by flaps resulting from the intimal tears associated with primary interventional procedure, or prevent elastic recoil of the vessel.
Stents may be utilized after atherectomy, which excises plaque, cutting balloon angioplasty, which scores the arterial wall prior to dilatation, or standard balloon angioplasty to maintain acute and long-term patency of the vessel.
Stents may be utilized in by-pass grafts as well, to maintain vessel patency. Stents can also be used to reinforce collapsing structures in the respiratory, biliary, urological, and other tracts.
Further details of prior art stents can be found in U.S. Pat. No. 3,868,956 (Alfidi et. al.); U.S. Pat. No. 4,739,762 (Palmaz); U.S. Pat. No. 4,512,338 (Balko et. al.); U.S. Pat. No. 4,553,545 (Maass et. al.); U.S. Pat. No. 4,733,665 (Palmaz); U.S. Pat. No. 4,762,128 (Rosenbluth); U.S. Pat. No. 4,800,882 (Gianturco); U.S. Pat. No. 4,856,516 (Hillstead); U.S. Pat. No. 4,886,062 (Wiktor); U.S. Pat. No. 5,102,417 (Palmaz); U.S. Pat. No. 5,104,404 (Wolff); U.S. Pat. No. 5,192,307 (Wall); U.S. Pat. No. 5,195,984 (Schatz); U.S. Pat. No. 5,282,823 (Schwartz et. al.); U.S. Pat. No. 5,354,308 (Simon et. al.); U.S. Pat. No. 5,395,390 (Simon et. al), U.S. Pat. No. 5,421,955 (Lau et. al.); U.S. Pat. No. 5,443,496 (Schwartz et. al.); U.S. Pat. No. 5,449,373 (Pinchasik et. al.); U.S. Pat. No. 5,102,417 (Palmaz); U.S. Pat. No. 5,514,154 (Lau et. al); and U.S. Pat. No. 5,591,226 (Trerotola et. al.).
In general, it is an object of the present invention to provide a stent or prosthesis which can be readily expanded and embedded into an obstruction or vessel wall with low dilatation pressure thereby minimizing the trauma and damaged imparted to the vessel wall during deployment of the stent.
It is also an object of the present invention to utilize a specifically designed configuration of the outer strut surface to facilitate embedment of the stent structure into the obstruction and vessel wall with low dilatation pressure.
Another object of the present invention is to employ a manufacturing process which optimizes the stress-strain curve characteristics that achieves an increased yield strength and ultimate tensile strength when compared to the other non-wire prior art stents.
The present invention is directed to an expandable stent which is relatively flexible along its longitudinal axis to facilitate delivery through tortuous body lumens, but which is stiff and stable enough radially in an expanded condition to maintain the patency of a body lumen such as an artery when implanted therein. In addition, the struts of the present invention have a specific trapezoidal, triangular or reduced radii configuration projecting radially outward that functions to reduce the forces necessary to penetrate the vessel wall with the stent thereby minimizing trauma or damage imparted to the wall during deployment.
The invention generally includes a plurality of radially expandable loop elements which are relatively independent in their ability to expand and to flex relative to one another. The individual radially expandable elements of the stent (cross-section of a strut) are dimensioned such that the aspect ratio of the height to width minimizes twisting or rotation during expansion. Interconnecting elements or a backbone extends between the adjacent loop elements to provide increased stability and a preferable position for each loop to prevent warping of the stent upon the expansion thereof. The resulting stent structure is a series of radially expandable loop elements which are spaced longitudinally close enough so that the obstruction, vessel wall and any small dissections located at the treatment site of a body lumen may be dilated or pressed back into position against the lumenal wall. The outward projecting strut surface converges towards the terminal end and is configured in a trapezoidal, triangular or rounded shape to facilitate embedment of the strut into the vessel wall utilizing low dilatation pressure. The individual loop elements may bend relative to adjacent loop elements without significant deformation, cumulatively providing a stent which is flexible along its length and about its longitudinal axis but is still very stiff in the radial direction in order to resist collapse.
The presently preferred structure for the expandable loop elements which form the stent of the present invention are generally a circumferential undulating or alternating loop pattern which comprises one of the radially expandable cylindrical elements. The transverse cross-section of the undulating component of the loop element preferably has an aspect ratio of about one to one (base to height) thereby minimizing any tendency of the strut to twist when expanded. The open reticulated structure of the stent allows for a large portion of the vascular wall to be exposed to blood which can improve the healing and repair of any damaged vessel lining.
The radial expansion of the expandable cylinder deforms the undulating or alternating loop pattern thereof similar to changes in a waveform which result from decreasing the waveform""s amplitude and the frequency. Preferably, the undulating or alternation patterns of the individual loop structures are in phase with each other in order to yield uniform expansion and inhibit any crimping along its length. The expandable cylindrical structures of the stent are plastically deformed when expanded so that the stent will remain in the expanded condition and therefore they must be sufficiently rigid when expanded to prevent the compression of the struts and therefore partial or total collapse of the stent after deployment. The manufacturing process of the present stent invention utilizes optimized stress-strain curve characteristics to achieve, unlike other non-wire stent designs, improved mechanical properties throughout the stent. The optimized stress-strain curve increases both the yield strength and the ultimate tensile strength of the expanded stent increasing its resistance to structural failure (fracture) or stent crushing. During expansion of the stent, the radially projecting trapezoidal, triangular or reduced radii configuration of the struts outer surface will penetrate the obstruction and vessel wall. Due to the reduced area of the outer surface, the struts are able to pierce an obstruction or the vessel wall with relative easy thereby resulting in minimal trauma or damage to the vessel wall. In addition, this design feature of the present invention helps secure the expanded stent so that it does not move once it is implanted and furthermore, minimizes projections into the blood stream.
The elongated elements which interconnects adjacent radially expandable elements should have a transverse cross-section similar to the transverse dimensions of the undulating or alternation loop components of the radially expandable element. The interconnecting elements preferably are not a unitary structure but rather alternates sectionally along the length at various degrees around the circumference of the stent. In an alternate embodiment, the interconnecting element is a unitary structure which resembles a backbone connecting the expandable loop elements.
In a presently preferred embodiment of the invention, the stent is conveniently and easily formed by first heat-treating the mechanically hardened tubular member to achieve optimum stress-strain characteristics e.g. yield strength, elongation and ultimate tensile strength. Then, the tubular member, comprising stainless steel, platinum, gold alloy, or a gold/platinum alloy, is electro-cleaned with an appropriate solution. Once the tubular member is cleansed of contaminates, the outer surface is uniformly coated with a photo-sensitive resist. Optionally, a coupling agent may be used to facilitate the bonding of the photosensitive resist to the tubular member. The coupling agent is not essential in that some tubular member compositions bond directly to the photo-sensitive resist solution without the need for a coupling agent.
This coated tubular member is then placed in an apparatus designed to rotate the tubular member while the coated tubular member is exposed to a designated pattern of ultraviolet (UV) light. The apparatus controls the exposure of the coated tubular member by utilizing a photographic film with a specified computer generated imprinted configuration, transferring the UV light in the specified pattern to the coated tubular member. The UV light activates the photosensitive resist causing the areas where UV light is present to expose (cross-link) the photo-sensitive resist. The photo-sensitive resist forms cross links where is it exposed to the UV light thus forming a pattern of hardened and cured polymer which mimics the particular stent design surrounded by uncured polymer. The film is adaptable to virtually an unlimited number of intricate stent designs. The process from the apparatus results in the tubular member having a discrete pattern of exposed photo-sensitive material with the remaining areas having unexposed photo-sensitive resist.
The exposed tubular member is immersed in a negative resist developer for a specified period of time. The developer removes the relatively soft, uncured photo-sensitive resist polymer and leaves behind the cured photo-sensitive resist which mimics the stent pattern. Thereafter, excess developer is removed from the tubular member by rinsing with an appropriate solvent. At this time, the entire tubular member is incubated for a specified period of time, allowing the remaining photo-sensitive resist polymer to fully cure and bond to the surface of the processed tubular member.
The processed tubular member is then exposed to a electrochemical etching process which removes uncovered metal from the tubular member, resulting in the final tubular member or stent configuration. Since the tubular member has not been subjected to any process such as additional heat treatments, welding/brazing or laser cutting, the finished stent will maintain the optimized stress-strain characteristics obtained in the initial heat-treatment process.
The stent embodying features of the invention can be readily delivered to the desired lumenal location by mounting it on an expandable member of a delivery catheter, for example, a balloon or mechanical dilatation device, and passing the catheter/stent assembly through the body lumen to the site of deployment.
Other features and advantages of the present invention will become more apparent from the following detailed description of the invention. When taken in conjunction with the accompanying exemplary drawings.

Abstract: The invention generally includes a plurality of radially expandable loop elements which are relatively independent in their ability to expand and to flex relative to one another. The individual radially expandable elements of the stent are dimensioned to minimize the strut from twisting or rotating during expansion. Interconnecting elements or a backbone extends between the adjacent loop elements to provide increased stability and a preferable position for each loop to prevent warping of the stent upon the expansion thereof. The resulting stent structure is a series of radially expandable loop elements which are spaced longitudinally close enough so that the obstruction, vessel wall and any small dissections located at the treatment site of a body lumen may be dilated or pressed back into position against the lumenal wall.

Abstract: The manufacturing process of the present invention utilizes optimized stress-strain curve characteristics to achieve, unlike other non-wire stent designs, improved mechanical properties throughout the stent. The optimized stress-strain curve of the materail increases both the yield strength and the ultimate tensile strength of the expanded stent, increasing its resistance to structural failure (fracture) or stent crushing.


A carton blank is etched with a laser to remove at least a portion of a coating material on a glue panel area of the carton blank. The laser-etching process allows the use of cold-resin or other standard glue in manufacturing a carton from the carton blank, instead of a more expensive specialized glue which would be otherwise required to provide an adequate bond for the carton. The laser-etching process is controlled as a function of the coating material required to be removed from the glue panel of the carton blank, the speed of the carton blank as it is processed through the system, and the dispersion characteristics of the laser beam.

This invention relates generally to paperboard cartons. More particularly, this invention relates to a system and method for making a paperboard carton.
The converting of paperboard into carton blanks, and then into folding cartons, can be accomplished with a variety of paperboard substrates depending upon the needs and/or cost constraints of the manufacturer as dictated by the end-user. For example, beverage cartons for soft drink and beer cans traditionally utilize a clay-coated paper kraft board. Other consumable or non-durable retail consumer goods, however, are packaged in a wide variety of substrates including, but not limited to, clay coated recycled paperboard, solid bleached sulfate paperboard, poly-coated solid bleached sulfate paperboard, foil-coated paperboard (recycled and virgin), film coated paperboard (such as metalized polyesters laminated to paperboard substrates), wax-coated paperboard, and various other kinds of paperboard that have been treated, e.g., with special additives such as grease inhibitors.
In addition to the coatings and laminations that are part of the raw paperboard roll stock when it arrives at a carton manufacturer""s plant, the manufacturer often further alters one or more characteristics of the board during the carton blank manufacturing process. Typical alterations of the surface of the paperboard include the graphics, and/or product information on the carton blanks. Different inks and coatings, of course, produce different surface characteristics on the paperboard.
The manufacturing process for folding cartons also includes an operation known as xe2x80x9cfinishingxe2x80x9d whereby a printed and/or coated carton blank is folded and glued on a machine referred to in the industry as a xe2x80x9cfolder-gluer.xe2x80x9d Depending upon the surface characteristics of the particular carton blank being folded and glued, a glue must be selected which provides the best combination of adhesive strength and low cost. Typically, carton manufacturers utilize inexpensive cold-resin glues, not unlike what might be found in a bottle of Elmer""s(copyright) glue. With ordinary clay-coated paperboard, cold-resin glues usually penetrate the clay coating and ink to impregnate the fibrous mass of the carton blank. The result is a bond sufficient to xe2x80x9cpull fiberxe2x80x9d, i.e., sufficient to tear the paperboard of one or both glued together panels of the carton blank, when the carton is stressed or opened at the manufacturer""s seam.
Problems occur, however, when the glue panels of a carton blank are treated with special inks, or covered with special foils, coatings, etc., which inhibit and/or prevent a cold-resin glue from bonding to the paperboard panels sufficient to xe2x80x9cpull fiber.xe2x80x9d In these cases, carton manufacturers typically utilize costlier means to achieve an adequate bond. For example, special poly-glues and/or hot melt glues are often used in such difficult applications. In some cases, often with foilized substrates, manufacturers actually will scuff the carton blank with an abrasive element (e.g., sandpaper) at the point of contact where the board meets the glue in order to achieve an adequate bond. In other cases, manufacturers will flame-treat the carton blanks on the folder-gluer to change the surface tension of the substrate and allow for a better glue bond.
Simply stated, it is often problematic to glue carton blanks inexpensively, if at all, with cold-resin glues when the paperboard from which the carton blank is made has been coated and/or treated with agents that prevent the glue from creating a commercially adequate bond between glued together glue panels or flaps of the carton blank. In other words, if the glue does not penetrate the carton blank""s coating layer, the result is a surface bond which is usually inadequate to hold the carton together during subsequent downstream operations, such as filling the carton with product, distributing the carton to a retailer, and retailing the carton to the end user of the product.
Therefore, it has been an objective of this invention to provide a system and method for manufacturing a paperboard carton utilizing cold-resin glues or other economical standard adhesives in order to permit an effective bond between the carton blank""s glue panels and/or flaps even when the underlying substrate of the carton blank has been coated and/or treated with agents that ordinarily would prevent that glue from coming into contact with the fibers of the paperboard carton blank.
A still further objective of this invention has been to provide such a method and system which can be efficiently and economically utilized in the commercial production of paperboard cartons without detrimentally impacting the appearance or utility of the resulting cartons or the production speed of the cartons.
These and other objectives have been attained by a method and system whereby the paperboard carton blank is etched with a laser beam to allow for adequate adhesion of the carton blank""s glue panels and/or flaps by cold-resin and/or other standard glues. In a presently preferred embodiment according to this invention, a supply of paperboard carton blanks is serially fed on a conveyor or the like through a work station. Each of the carton blanks has at least one glue panel or flap on which glue will be applied to erect the carton. The carton blank""s glue panel initially has a coating layer which prevents or inhibits standard glues from adhering to the fibers of the paperboard to provide an adequate, commercially acceptable bond. According to this invention, a laser beam is directed onto the glue panel on each of the carton blanks so as to remove at least a portion of the coating layer on each glue panel. This allows a cold-resin or other standard glue to be effectively applied to the laser-etched glue panel, and the carton blank subsequently to be successfully folded and glued into a carton configuration. Each carton blank""s laser-etched glue panel enables the cold-resin glue to bond with the fibers of the paperboard so as to produce an adequate bond to hold the carton together during subsequent downstream operations such as filling the carton with product, and distribution of the carton to a retailer and, ultimately, to a retail purchaser.
Additionally, the presently preferred embodiment of the invention includes dispersing the laser beam through an optical lens or other mechanism in order to direct the laser beam over a desired area of the glue panel for removal of the unwanted coating layer in that area. Moreover, the intensity of the laser beam is controlled electronically as a function of the speed of the carton blanks through the work station, the dispersion of the laser beam, and the depth of the etching desired (i.e., the amount of the unwanted coating layer to be removed on the glue panels of the carton blanks being processed).
As a result of the laser-etching method and system according to this invention, carton blanks can be glued inexpensively with cold-resin or other standard glues even when the paperboard carton blank has been coated and/or treated with a coating layer or other agents that typically prevent such glues from coming into contact with the paperboard fibers of the carton blank. After the glue panel of the carton blank has been etched with the laser, the cold-resin glue is applied to that glue panel, and it tends to impregnate to some extent the paperboard so as to provide an effective adhesive bond after gluing the carton blank into carton configuration. Moreover, this invention can be integrated into a production process for manufacturing cartons from carton blanks by controlling the intensity of the laser beam as a function of the speed of the carton blanks transported through the process, the dispersion of the laser beam, and the desired etching depth on the glue panel of the carton blank, all without detrimentally impacting cost or efficiency of the process.

Laser-etching of paperboard carton blanks


An oil pan for an internal combustion engine has a metallic gastight and fluidtight threaded insert for receiving an oil drain plug, the insert having a cylindrical section which rests in an opening of a wall of the oil pan. The cylindrical section of the threaded insert, on an exterior side of the oil pan, is provided with a collar which, by means of a sealing adhesive arrangement, is fastened to the exterior wall section of the oil pan.

The present invention generally relates to an oil pan and more particularly to a process and arrangement for securing a metal insert to an oil pan made of plastic.
German Patent Specification (DE-PS) 32 46 768 discloses an arrangement wherein a cylindrical threaded insert is provided with circumferential grooves into which a plastic wall, which surrounds the threaded insert, projects with the corresponding sections. A ring made of an elastomeric material which radially encloses the threaded insert and is arranged in a groove of the threaded insert is used as a seal between the wall and the threaded insert. This construction has the disadvantage that the grooves at the threaded insert represent an additional manufacturing expenditure. In order to have the proper sealing effect, the receiving device of the ring must maintain narrow tolerances which, according to experiences, is connected with relatively high costs.
It is therefore an object of the invention to provide a threaded insert and an associated holding device and process for securing the same to an oil pan such that, while threaded insert is simplified with respect to its construction and with respect to tolerances, it is firmly and tightly connected with the oil pan, even when highly stressed over a relatively long period of time.
Principal advantages achieved by preferred embodiments of the present invention are that the metallic threaded insert, including a cylindrical section having a collar provided at one end, represents a simple component. The connecting of the threaded insert with an oil pan takes place at the collar, specifically by means of an adhesive device which carries out two functions: (1) holding and (2) sealing. The adhesive device is an adhesive film which may be a commercial product and, for example, by means of punching. Finally, the threaded insert may be connected with the oil pan by low-cost process steps.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

Arrangement and process for securing a threaded insert to an oil pan

Dr. Ing. h.c.F. Porsche Aktiengesellschaft


The invention relates to the use of a composition comprising at least one substance within the group GnRH-analogues for producing a drug for treatment of schizophrenia. The invention makes it possible for patients suffering from schizophrenia to obtain partial or total relief of symptoms by treatment with a composition which comprises at least one substance within the group GnRH-analogues.

The present invention relates to the use of a composition comprising at least one substance within the group GnRH-analogues for treatment of schizophrenia.
Schizophrenia is a chronic psychiatric disease in which the main symptoms are delusions, hallucinations and grossly disorganised or catatonic behaviour. The disorder is chronic and often serious enough to make the patient completely or partially unable to work and live a normal life.
The disorder is described and defined in detail in The Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) published by the American Psychiatric Association in 1994.
At the present state of the art of science, the only pharmacological treatments which are considered to be effective for the treatment of schizophrenia, are such pharmacological agents which are antagonists at the dopaminergic receptor in the brain.
That this is the present scientific opinion is evident from the following Swedish and English psychiatric textbooks.
1. Ottosson, J-O: Psykiatri. Almqvist and Wiksell Medicin Luber Utildning. Stockholm 1995. Chapter 9. Pages 167-214.
2. Gelder, M., Gath, D., Mayou, R., Cowen, P.: Oxford Textbook of Psychiatry. Oxford Medical Publications. Oxford 1995. Pages 246-293.
Physiological Regulation of Androgenic Hormones Under Normal Conditions (i.e. without Influence of Drugs)
Gonadotropin-releasing hormone (GnRH) stimulates the production of gonadotropins in the hypophysis (at the bottom of the brain). The gonadotropins are released to the blood and transported to the testes and the adrenal glands (of the male) and to the ovaries and the adrenal glands (of the female). There, the gonadotropins stimulate the synthesis and release of, among other hormones, the androgens (the male sex hormones) of which testosterone is one.
The androgenic hormones are released to the blood from the glands in which they are produced. They are transported to different organs where they exert their various actions. One of these organs is the brain. There, the androgenic hormones exert their effects by stimulating certain receptors. The androgenic activity in the brain is dependent both on the concentration of androgenic hormones in the blood, and on the density and sensitivity of the receptors on which the androgenic hormones act. The androgenic activity may thus be high, both at a high concentration of androgenic hormone in the blood, and in cases of a high density and/or sensitivity of the androgenic receptors.
The production of androgenic hormones is normally subjected to a xe2x80x9cfeed-backxe2x80x9d regulation. If the androgenic activity in the brain is high, a compensating reduction in the synthesis and release of GnRH and consequently of the of gonadotropins takes place, with a following reduction in the synthesis and release of androgenic hormones. At a high androgenic activity in the brain, caused by a high density and/or sensitivity of the receptors (and not due to a high concentration of androgenic hormones in the blood), the compensating feed-back-regulation might cause a decrease in the synthesis and release of androgenic hormones which in turn might cause abnormally low blood concentrations of androgenic hormones. Such low concentrations could not be taken as a sign of low androgenic activity; it may still be high (if the compensation has not been sufficient) or normal (if the compensation has been sufficient).
Known Fields of Application for Pharmacological Agents which Reduce the Activity of Androgenic Hormones
There are several drugs which have well-documented anti-androgenic effects. These drugs are mainly used in the treatment of carcinoma of the prostate but also in the treatment of unwanted phenomena, which are caused by a high androgenic activity. Examples of such phenomena are hypersexuality and male pattern baldness in men and hirsutism (a condition with bodily male hair growth) in women.
Groups of Drugs with Anti-androgenic Properties
Anti-androgenic effects may be obtained via three different mechanisms:
Receptor-blocking Substances
These are substances that bind to the androgenic receptors without stimulating them. In this way, the endogenous hormone is prevented from binding to the receptors with a resulting reduced androgenic activity. Preparation example: flutamide (Eulexin(copyright)).
Synthesis-inhibiting Substances
These are substances which inhibit production of androgenic hormones in the glands where they are produced. Preparation example: cyproterone acetate (Androcur(copyright)) (this substance also has receptor-blocking properties).
GnRH-analogues
These are substances which, in their effect, resemble endogenous GnRH but they produce a more powerful and more protracted effect upon the GnRH-receptors. Initially they have the same effects as endogenous GnRH, i.e. by stimulating the production of gonadotropins, the synthesis and release of androgenic hormones is also stimulated resulting in an increase in androgenic activity. After treatment during a certain period of time the sensitivity in the receptors, on which endogenous GnRH and GnRH-analogues act, will be significantly reduced. Hereby, the release of gonadotropins will also be reduced. The reduction in concentrations of circulating gonadotropins will cause a decrease in synthesis and release of androgenic hormones. Consequently, the androgenic activity in the brain and elsewhere will be dramatically reduced. Preparation example: buserelin (Suprecur(copyright); manufacturer Hoechst Marion Roussel), leuprorelin (Enanton(copyright); manufacturer Orion and Procren(copyright); manufacturer Abbott), goserelin (Zoladex(copyright); manufacturer Zeneca), triptorelin (Decapeptyl(copyright); manufacturer Ferring).
One object of the present invention is to provide a pharmaceutical composition which enables for patients with schizophrenia to obtain partial or complete relief of symptoms by treatment with this composition.
For this object, the invention is characterised in that the composition comprises at least one substance within the group GnRH-analogues.
Different variants of the invention are disclosed in the accompanying depending claims.
The method of treatment, described in the following, has its intellectual basis in observations that have been made in contacts with patients at a psychiatric specialist clinic, in combination with established scientific facts. To sum up, the following observations and facts are applied.
1. Remarkably many patients with schizophrenia have been found to have clinical symptoms of a high androgenic activity such as a strong sexual drive, a sebacecus skin and a male pattern baldness.
2. On the basis of observation (1) has, at the above mentioned clinic, as a clinical routine examination, the determination of the free fraction of the androgenic hormone testosterone in blood been introduced. Hereby, it has been noticed that patients suffering from serious forms of schizophrenia have subnormal blood concentrations of free testosterone. This finding has been interpreted as an effect secondary to an increased androgenic activity in the brain.
3. A patient who has been suffering from a very severe form of schizophrenia which has made him totally disabled and for which he has been receiving sickness pension for over twenty years, has after six months of treatment with the GnRH-analogue triptorelin become dramatically improved. The patient had previously been treated with various dopamine receptor antagonists without any major improvement.
The treatment of schizophrenia in accordance with the invention is performed in the following manner:
The following conditions must be fulfilled in order for the described method to be appropriate.
1. The diagnosis should be ensured in accordance with the criteria specified for example in DSM-IV.
2. Those established methods of treatment which do not cause severe side effects should first have been tried.
3. The patient should have been judged to be so severely plagued or otherwise handicapped by the disease that it is obvious that the advantage of a possible cure or relief of symptoms balances the disadvantage of the side effects of the treatment. The side effects here referred to are the reduction of the sexual drive and the reduced sexual performance which may be expected as a result of the treatment.
4. Before the pharmacological treatment starts, the patient must be subjected to a medical investigation to make certain that he/she is not suffering from any other serious disease.
In the treatment, the patient is repeatedly given a pharmacological agent from the pharmaceutical preparation group GnRH-analogues which, by decreasing the sensitivity in the receptors controlling the synthesis and release to the blood of the gonadotropins, cause a marked decrease in synthesis and release of androgenic hormones to the blood. Hereby the androgenic activity is dramatically reduced. There are several substances available on the market which cause the desired effects. There are also alternative pharmaceutical preparations available on the market. Thus, there are presently preparations for various forms of injection and for administration by nasal spray. From a general point of view it is probable that, in the treatment of schizophrenia, these pharmacological agents should be administered in the same way and in the same doses as when they are used in the treatment of carcinoma of the prostate.
One example of an administration procedure for one of these pharmacological agents is delivered in the following.
The GnRH-analogue triptorelin is available in a pharmaceutical preparation (Decapeptyl(copyright) Depot). In the use of this preparation, an injection is administered containing triptorelin embonate in a dose corresponding to 3.75 mg triptorelin. Injections with this dose are given intramuscularly. They should be repeated every fourth week from the first injection.
In order to verify that a sufficient effect has been achieved, the blood concentration of free testosterone should be assessed, e.g. once every fortnight until full effect has been established. This is the case when the blood concentration of free testosterone has fallen to levels below the detection limit or very close to it.
Initially during the treatment there is an increase in the amount of circulating androgenic hormones in the blood and consequently in androgenic activity. This increase, which may remain for some weeks, may result in a change for the worse in the psychotic symptoms. This impairment could be expected to remain until the androgenic activity has been reduced. This could be expected to take some weeks. To avoid the risk of such an initial deterioration, the patient may, during the first phase of the treatment, be treated also with the androgenic receptor-blocking agent flutamide (Eulexin(copyright)) in a dose of 250 mg administrated three times each day in tablets. These tablets are commercially available for use against carcinoma of the prostate. However, this additional treatment, is not necessary for the efficiency of the above described treatment of schizophrenia; it has the sole purpose of avoiding the risks of an initial accentuation of the symptoms.
The here described pharmacological method of treating schizophrenia implies, as in all other psychiatric treatments, that the psychiatrist provides the patient with a continuous psychological support.
Presently, it is not possible to say whether the treatment must be chronically administered, or if it could be terminated after a certain period of time without risking deterioration in schizophrenic symptoms. This question must be answered in coming clinical investigations.

Method in the treatment of schizophrenia


A system for collecting and processing blood from a donor (70), wherein the system may be compact enough to be located entirely beside the donor""s chair, and be able to process the blood while the donor is still resting in the chair after having donated the blood. Thus, the separated blood components (plasma and red blood cells) may be stored in their individual optimum environments immediately after the whole blood is drawn, and the blood does not need to be transported back to a separation laboratory for processing. The system includes a needle (72) (or other cannula-like device) for insertion into a vein of the donor and drawing whole blood therethrough, a variable-volume rotor (2a) for holding the blood after it is drawn, and a motor (50) for spinning the rotor so as to cause the blood to separate into components, for example, plasma and red blood cells. The system also provides for a container for collecting a separated component. In a preferred embodiment two containers are used: the first container (92) for containing an anticoagulant, which is preferably added to the whole blood as it is drawn from the donor, and then for storing the plasma after it has been separated from the red blood cells, and the second container (91) for storing the separated red blood cells. The system further includes tubing (73), which may have valving (81) built into it and which may be acted on externally, so as to direct the blood components in the desired manner.

1. Technical Field
This invention relates to a method of whole-blood collection and the preparation of components therefrom following collection.
2. Background Art
In the conventional method of whole blood collection, a needle is placed in a vein in the donor""s arm and whole blood flows by gravity into a bag which holds a quantity of anticoagulant solution, which prevents the blood from clotting. When a unit of whole blood, defined in the United States as 450 milliliters (ml), has been collected, the needle is removed from the vein and the blood bag is set aside for later transfer to the processing laboratory of the blood center.
It should be noted that the ratio of anticoagulant to whole blood is approximately one to seven; thus the amount of anticoagulant in the bag is 63 ml. It should also be noted that, while the ratio of anticoagulant to whole blood is one to seven after a full unit has been collected, the ratio of anticoagulant to whole blood is considerably higher than one to seven at the beginning of the collection. The red cells flowing into the collection bag at the beginning of the collection are, therefore, subject to xe2x80x9canticoagulant shockxe2x80x9d, which has the effect of damaging some of the red cells. As the collection proceeds, the ratio decreases.
In the processing laboratory, a technician places the bags of whole blood into a large, swinging bucket centrifuge, which must be carefully balanced as the bags are loaded. The centrifuge is started and the bags are spun at a high rate of speed. In the first centrifugation, the red cells, which are the heaviest component, are forced to the bottom of the bag while the platelet-rich plasma, which is lighter, rises to the top. When the bags are removed from the centrifuge, they must be handled carefully so as to avoid remixing.
The technician next places each bag in an xe2x80x9cexpressorxe2x80x9d consisting of two rigid plates that are joined by a spring loaded hinge. One of the plates is fixed and the other is moveable. The blood bag is positioned between the two plates and the spring catch released causing the moveable plate to press against the bag. A port on the top of the bag is then opened and the platelet-rich plasma is expressed into an attached, empty bag. When the technician observes that red cells are about to reach the outlet port, the expression is stopped and the tubing clamped.
If platelets are to be separated, the bags containing the platelet rich plasma are returned to the centrifuge, the load is again balanced and a second spin begins, this time at a higher speed This spin forces the platelets to the bottom of the bag and allows the lighter plasma to rise to the top. The expression process described above is then repeated so that the platelets can be diverted to a separate bag for storage. There are other variations of these blood-component collection and separation processes, including a process for collecting a buffy coat from the blood; all of the variations use centrifugation techniques similar to those described above. Although various devices have been developed and marketed whose function is to minimize the amount of labor required in the expression of components from one bag to another, these devices do not eliminate the centrifugation step described above. Furthermore, these devices are designed to be used in the component-preparation laboratory of the blood center and not at the point of whole blood collection.
It will be appreciated, therefore, that the conventional method of centrifuging and separating components from whole blood is a labor-intensive, manual process. In addition, in order to be convenient to volunteer donors, the majority of whole blood collections take place, not in the blood center, but in mobile units that travel to other locations, such as community centers, offices and factories. Because the bags of whole blood must then be transported back to the blood center for processing and because of the need to schedule the time of laboratory personnel, many hours can elapse between the completion of the collection and the time that component separation begins.
It should be noted that, if the plasma separated from the whole blood is to be used for the production of Factor VIII for transfusion to hemophiliacs, regulations require that the plasma separation must be completed and the plasma frozen within six hours of the time of the whole-blood collection. It can be demonstrated that, the sooner the plasma is frozen, the higher will be the recovery of Factor VIII. It should be further noted that, if the plasma is to be used for transfusion as Fresh Frozen Plasma, regulations require that the separated plasma be placed at xe2x88x9218xc2x0 C. or lower within eight hours of collection from the donor. The practical consequence of these regulations is that blood banks must schedule the times of donations with the times at which laboratory personnel are available to prepare the components.
In addition to the conventional method of whole blood collection and component separation just described, individual blood components can be collected by a process called apheresis. In this process, the donor is connected to a cell separator, a needle is inserted in the donor""s arm, an anticoagulant is added to the whole blood as it is drawn from the donor, and the anticoagulated whole blood is pumped into the rotor of the cell separator where centrifugal force causes the components to separate. The component that is to be retained is directed to a collection bag and the unwanted components are returned to the donor. This process of drawing and returning continues until the quantity of the desired component has been collected, at which point the process is stopped. Apheresis systems are used widely for the collection of single-donor platelets and single-donor plasma. A central feature of these apheresis devices, however, is that, while they separate blood components at the point of collection, they require that the unwanted components must be returned to the donor. This, in turn, means that apheresis devices must incorporate a variety of safety features, such as air detectors and pressure monitors, to protect the donor from harm while the donor is connected to the cell separator. Such safety mechanisms add cost and complexity to apheresis system equipment and disposables.
In contrast to apheresis systems, conventional whole blood collection systems do not return anything to the donor but, on the other hand, neither are they able to separate blood components at the site of collection. There is a need, therefore, for an improved method of whole blood collection and the preparation of components therefrom, without the complexity and expense of conventional apheresis devices, and without the labor-intensive, manual separation process described above.
The present invention provides a system for collecting and processing blood from a donor, wherein the system may be compact enough to be located entirely beside the donor""s chair, and be able to process the blood while the donor is still resting in the chair after having donated the blood. Thus, the separated blood components (plasma and red blood cells) may be stored in their individual optimum environments immediately after the whole blood is drawn, and the blood does not need to be transported back to a separation laboratory for processing.
The system includes a needle (or other cannula-like device) for insertion into a vein of the donor and drawing whole blood therethrough, a variable-volume rotor for holding the blood after it is drawn, and means for spinning the rotor so as to cause the blood to separate into components, for example, plasma and red blood cells. The system also provides for a container for collecting a separated component. In a preferred embodiment two containers are used: the first container for containing an anticoagulant, which is preferably added to the whole blood as it is drawn from the donor, and then for storing the plasma after it has been separated from the red blood cells, and the second container for storing the separated red blood cells. The system further includes tubing, which may have valving built into it and which may be acted on externally, so as to direct the blood components in the desired manner. The tubing connects the needle, the rotor, and the first and second containers. With the valving, the tubing is able to permit (i) the flow of whole blood from the needle to the rotor, (ii) the flow of anticoagulant from the first container to the whole blood flowing from the needle to the rotor, (iii) the flow of plasma from the rotor to the first container, and (iv) the flow of red blood cells from the rotor to the second container. The spinning means and the valving are preferably controlled by an electronic controller. Preferably, the system also includes pumping means, which is also controlled by the controller, and which forces the blood components out of the rotor to the tubing. The pumping means preferably includes means for drawing the whole blood into the rotor.
The system preferably includes an interlock device, connected to the controller, which does not permit the pumping (or flowing) of any blood components from the rotor until the needle has been inserted into the interlock device. This feature ensures that the donor is not still connected to the system when the system is generating pressure for forcing blood components out of the rotor. Preferably, the controller does not permit the rotor to be spun until the needle has been inserted into the interlock device.
In a preferred embodiment, the tubing has a valve, which is connected to three components: to the rotor by a common tube, to the second container by a second-container tube, and to the first container by a first-container tube. The tubing connecting the first container to the rotor is preferably in fluid communication with the needle, so that whole blood can preferably flow through the first-container tube through the valve to the rotor. In this embodiment, the controller includes means for detecting the presence of red blood cells passing from the rotor to the valve means, and causes the valve means to direct the red blood cells to the second container upon the detection of the red blood cells. In one embodiment, the needle is attached to the first-container tube.
In an alternative, preferred embodiment, the needle is connected to the valve means by a separate tube, so that the valve means is connected to four components: the rotor, the first and second containers, and the needle. In this embodiment, the valve means, in one mode, permits flow from the needle to the rotor while allowing anticoagulant to enter this flow at the valve means. In a second mode, the valve means permits no flow from the rotor. In a third mode, the valve means permits flow from the rotor to the first container, and in a fourth mode, the valve means permits flow from the rotor to the second container.
The variable-volume rotor is preferably of the type described in co-pending application Ser. No. 08/322,601, now U.S. Pat. No. 5,733,253, for a xe2x80x9cBlood Processing Systemxe2x80x9d by Headley and Powers, filed Oct. 13, 1994. This application is incorporated herein by reference. In a preferred embodiment of the invention, the rotor includes an elastic diaphragm and a rigid member, which together define a chamber of varying volume (as described in application Ser. No. 08/322,601). The pumping means in this embodiment may apply gas pressure against this diaphragm to force blood components out of the rotor, preferably through the common tube through the valve to their respective containers. The pumping means also preferably includes means for applying a negative gas pressure against the rotor""s diaphragm in order to draw whole blood into the rotor""s chamber.
In a preferred procedure, the system is connected to the donor for collecting the whole blood from the donor, then the system is disconnected from the donor and used to separate the blood into its components by centrifugation. Preferably, the system first draws whole blood through the needle and meters anticoagulant from the first container into the whole blood as it enters the variable-volume rotor. The anticoagulated whole blood then enters the rotor. When the system detects that the desired quantity of whole blood has entered the rotor, the needle is withdrawn from the donor""s arm, following which the rotor is spun so as to separate the whole blood into plasma and red blood cells. After the blood components are separated, the rotor continues to spin to maintain the blood components in their separated state (preferably at a slower rate than that required to achieve the separation), and the plasma is forced out of the rotor and directed to the first container, which held the anticoagulant. Preferably, as noted above, the system is designed so that this forcing the plasma out of the rotor cannot take place until the needle is removed from the donor and inserted into an interlock device After all the plasma has been forced out of the rotor, the red blood cells are forced out and directed to the second container.
In an alternative embodiment of the process, the red blood cells are washed before being dispensed from the rotor. Wash solution is added to the rotor after the plasma has been directed from the rotor but before the red blood cells have been directed from the rotor. The rotor is then agitated so as to mix the wash solution and the red blood cells. After the wash solution and the red blood cells have been mixed, the rotor is spun again so as to separate the wash solution and the red blood cells. The separated wash solution is dispensed from the rotor, and then finally the washed, separated red blood cells are dispensed from the rotor.