WO2012065819A1 - Method for manufacturing wheelchairs and wheelchair manufactured by said method - Google Patents

Abstract

The present invention relates to a method for connecting together at least two elements of a wheelchair, said method comprising the following method steps: a) providing a first element having a receiving region for receiving, at least in regions, at least one connecting region of a second element, b) arranging a thermally hardenable, non-fluid adhesive in the receiving region of the first element and/or on the connecting region of the second element, said connecting region being provided for being received at least in regions by the receiving region of the first element, c) inserting, at least in regions, the connecting region of the second element into the receiving region of the first element, and d) thermally hardening the adhesive between the first element and second element.

Description

 METHOD FOR PRODUCING WHEELCHAIRS AND WHEEL CHAIR MADE THEREFOR

The present invention relates to a method for connecting at least two elements of a wheelchair together.

In wheelchairs, the various elements have traditionally been connected by welding connections, screw connections or mechanical joining. These techniques allow a stable connection of most components, but also have disadvantages. For example, due to the local heating in the context of welding of metal parts, there is often a delay of the manufactured components, so that they subsequently have to be straightened out. In addition, by the heat development a

Weakening of the metal structure arise.

In DE-U1-203 21 382 wheelchairs are already described which have a composite frame member which is glued to the rest of the frame with a conventional assembly adhesive.

The use of adhesive joints in wheelchairs is thus already known in principle.

Object of the present invention was to provide a method for the production of adhesions to wheelchairs already, which makes it possible with little effort, that is, inter alia, with as few process steps to produce wheelchairs, the stability of the conventionally welded wheelchairs at least equal are.

It has now been found that the advantages of a thermally curable adhesive bond, preferably with the aid of a special adhesive, can be used in the manufacture of wheelchairs to provide wheelchairs which are stable and, at the same time, in terms of wheelchair weight, ease of manufacture and the resulting costs are optimized.

A first subject of the present invention is therefore a method for connecting at least two elements of a wheelchair together, comprising the following method steps: a) providing a first element having a receiving region for at least partially receiving at least one second element,

 b) arranging a thermosetting, non-fluid adhesive in the receiving region of the first element and / or on at least one connecting region of the second element, which at least partially receiving by the

 Receiving area of the first element is provided

 c) at least partially inserting the connection region of the second element into the receiving region of the first element, and

 d) thermally curing the adhesive between the first and second elements.

According to the invention, the term "connecting at least two elements of a wheelchair" means both methods in which two essential components of the wheelchair are directly connected to one another, but according to the invention embodiments are also included in which one of these elements is a component that only the function is to form a connection between at least two essential components of the wheelchair and that is connected on at least one side with a substantial element of the wheelchair by the method according to the invention.

The possibility of at least partially receiving the second element in the first element via the connecting region of the second element and the receiving region of the first element can be realized according to the invention in different ways.

Thus, in the case of the bonding of tubular elements (pipe sections), these may be configured with connecting areas or receiving areas, for example in the form of end sections, that the end section of the second pipe section can be inserted into the end section of the first pipe section, wherein the end section, for example, in the form of a fitting or a sleeve can be configured in particular by widening of the pipe section. It may be preferred according to the invention, if at least one of the two end portions is configured conical.

In the context of this embodiment, it has proven to be advantageous if on the

An end portion or connecting portion of the second tube piece, an adhesive is applied, the end portion of the second tube piece is introduced with the applied adhesive film in the end portion or receiving portion of the first tube piece and the adhesive is cured by heating. According to the invention, however, the reverse arrangement is included. In the context of this embodiment, the adhesive film is introduced into the inner region of the end portion of the first tube piece, the second tube piece in the first Pipe piece, the latter having the adhesive introduced, and then cured the adhesive by heating. As a further alternative, the adhesive may also be applied or introduced both to the end section of the second tube section and into the end section of the first tube section.

It can be provided that the first element in tube form and / or the second element is formed as tubular elements in tubular form or be, wherein the tubular shape has an arbitrary cross section, such as a circular cross section, but preferably an oval or polygonal cross section.

The tubular elements can themselves have different geometries. The tubular elements may in particular be part of a straight or curved tube, but also of a branch tube, for example in T-shape or Y-shape. By bonding such branch pipes according to the invention, it is possible to create even complex structures using the method according to the invention, without sacrificing the required stability of the construction.

In addition to the connection of pipe sections but also solid body can be bonded by the method according to the invention. For example, it is possible to insert rods into bodies of solid material, as long as the solid material bodies have recesses or through-holes into which the end pieces of the rods can be fitted. Also in this embodiment, the adhesive may be applied to the end portion of the rod (connecting portion of the second member) and / or the inner portion of the recess or the through hole of the rod-receiving solid (receiving portion of the first member).

The bonding of rods with pipe sections or solid bodies with pipe sections in the abovementioned variants of the arrangement of the adhesive for the production of a wheelchair are also included according to the invention.

It is also proposed that the first and / or second element in a

Kokillengussverfahren, an extrusion process, a continuous casting process, a centrifugal casting process, an injection molding process, a rolling process, a

Extrusion process and / or a die-casting process is or will be prepared.

In the context of the present invention can also be provided that at least one recess, in particular in the form of a groove, in the connecting region of the first element and / or is formed in the receiving region of the second element for filling with the adhesive.

After the adhesive has been arranged in and / or on the element or elements to be joined, the at least partially insertion of the connecting region of the second element into the receiving region of the first element takes place within the scope of the steps c) according to the invention.

This step c) of the process according to the invention can take place immediately after the application of the adhesive. However, it is also possible that there is a considerable time interval between step b) and step c) of the method according to the invention. So can

For example, one of the parts to be joined are already equipped with the adhesive during its production and then stored over a longer period before the actual joining of the parts takes place.

If the adhesive is tacky at room temperature, an initial fixation is already achieved immediately after performing step c). This initial fixation can also be achieved by a brief local heating of the adhesive, wherein the conditions of local heating are chosen so that a precuring of the adhesive takes place. The local heating can be done for example by means of a heat clamp or a cuff.

In addition to this initial fixation or in its place can be provided that between the steps c) and d) fixing of the introduced into the receiving area of the first element connecting portion of the second element, for example by a fixing means, preferably using at least one screw as

Fixing agent, is made. For this purpose, the elements, in particular on

Connection area and / or be provided on the receiving area with appropriate recordings for the fixative. For example, when using a screw as a fixing means, the receiving area of the first element may be provided with a lateral bore which is provided with a thread. After introduction of the

Connecting region of the second element in the receiving region of the first element, then the screw can be screwed into the threaded bore to clamp the second element in the first element, for example, and thus to achieve a positional fixation of the two elements to each other.

It is proposed that the fixation after step d) is solved, preferably the screw is replaced by another screw. Within the scope of step d) of the method according to the invention, it is provided that the adhesive is thermally cured between the first and the second element.

In this process step essential to the invention, at least the region of the elements comprising the adhesive thermally at 60 ° C to about 200 ° C, in particular on

Temperatures between 100 ° C and 180 ° C, heated. As a result, the adhesive cures between the first and the second element. The duration of heating may be between about 1 and 120 minutes, preferably between about 5 and about 45 minutes.

Depending on the application, the thermal heating can be done by different methods. Thus, the nested portion of the components with a (preferably electrically) heated clamp against each other fixed, the heater of the terminal activated and thereby the nested end portions of the components are heated so that the adhesive hardens. Instead of the heatable clamp can also attach a heatable sleeve or the like to the nested sections of the components or similar parts and hereby heat the nested end sections. A heating by irradiation, hot air (for example, by a controlled hot air gun) or the use of induction techniques is conceivable according to the invention.

In a particularly preferred embodiment, it has proven to be advantageous to integrate the curing of the adhesive in the refining process of the wheelchair. As part of the refining process, a thermal heating of the finished wheelchair shell is regularly carried out in order, for example, to cure powder coating coatings. This is preferably done in a heating oven. In particular, it is conceivable here, if appropriate after further pretreatments of the wheelchair shell, to utilize the process heat of a furnace for hardening the cathodic dip coating (KTL or E-coat) in order to achieve this

Harden adhesives.

Accordingly, such processes are particularly preferred according to the invention, in which the refining process comprises a material curing and / or a coating, preferably with a color layer.

This embodiment of the present invention is therefore based on the surprising finding that not only the advantages of bonding two elements in the production of a wheelchair can be used, but also the number of manufacturing steps can be reduced by the fact that the step of curing an adhesive by heat - Apply simultaneously with, for example, a material curing or application of a color can take place in a (coating) oven. This reduces both the time required and the costs.

Although it is conceivable in principle, if the components to be joined consist of the same material, very good successes in the bonding of wheelchair components made of different materials could be achieved in the context of the present invention.

In particular, the inventive method for bonding metals, such as

For example, steel, aluminum optionally with Scandiumzusatz or titanium, wood, ceramics, plastics, fiber composites, such as carbon fiber reinforced plastics or aramid fiber reinforced plastics, or ferrites suitable.

Further features and advantages of the invention will become apparent from the following

Description, in the embodiments of the invention with reference to schematic

Drawings are explained.

Showing:

 Figure 1 is a perspective view of a portion of the frame of a

 wheelchair according to the invention;

FIG. 2a shows a perspective view of a connection of a side frame tube

Connecting element and a backrest tube of an inventive

Wheelchair, with adjustment;

Figure 2b is a perspective view of a compound of a side frame tube and a backrest tube of a wheelchair according to the invention, without

 adjustment;

 Figure 3a is a perspective view of a cross brace of a wheelchair according to the invention;

 and

 Figure 3b is a partial exploded view of the crossbar of Figure 3a.

Figure 1 shows a portion of a frame of a wheelchair according to the invention, which is formed as a folding wheelchair, wherein the wheelchair frame carries the reference numeral 1. This wheelchair frame 1 in turn comprises two side frame tubes 2a, 2b, two

Backrest tubes 3a, 3b, two cross struts 4a, 4b, two seat tubes 5a, 5b and two

Wheel axle shots 6a, 6b.

The connection between the side frame tube 2a and the backrest tube 3a and the side frame tube 3b and the backrest tube 3b can be made in a method according to the invention, as described in detail with reference to Figures 2a and 2b explained. Likewise, each of the cross struts 4a, 4b can be manufactured in a method according to the invention, as will be explained with reference to FIGS. 3a and 3b.

FIG. 2 a shows a side frame tube connecting element 10 to which a side frame tube (not shown) can be connected and a backrest tube 3 is connected. In this case, the backrest tube 3 as well as the side frame tube each represents a first element, which can receive a connection region of the tube connecting element 10 at least partially as a second element by means of a receiving region. The pipe connection element 10 is in this case formed with a groove (not shown) into which an adhesive 20 is introduced. As soon as the first elements 3 are pushed onto the side frame tube connecting element 10 together with the adhesive, the unit of the first elements and the second element is provided with a color layer and introduced into a coating oven, not shown, in which the color layer is dried and at the same time the structural foam is cured.

This results in a considerable time and cost savings in the production.

Due to the bonding process just described, the elements are higher

Tolerances manufacturable, so that, for example, connecting elements can be produced as Kokillenguss parts, resulting in a further cost and also weight reduction.

An oval cross-sectional shape of the elements also facilitates the adjustment. A fixation of the elements in the coating oven, for example by screwing, may be helpful.

The unit shown in Figure 2b of a backrest tube 3 'and a side tube 2', each representing a first element, and a not shown

 Side frame tube connecting element as the second element is produced in analogy to the unit according to FIG. 2a. The difference between the two variants of FIGS. 2 a and 2 b is that the unit according to FIG. 2 b does not offer an adjustment possibility, which, however, for the

inventive method is irrelevant.

FIG. 3a shows a cross brace 40, with its two side elements, namely in the form of a seat tube receptacle 40a and a fork 40b for a wheel axle receptacle, as shown in FIG. The middle part between the seat tube receptacle 40a and the fork 40b in turn consists of three cross strut elements 41, 42, 43, as shown in Figure 3b. These elements have been combined in a process according to the invention. Likewise, the connection between these three elements 41, 42, 43 on the one hand and the seat tube receptacle 40a and the fork 40b on the other hand can be produced in each case in a method according to the invention. The production per se does not differ from that with reference to FIG. 2a described production. Again, the simultaneous curing of an adhesive and application of a paint in a coating oven is particularly preferred in order to save costs and time during production. It should also be pointed out that the individual elements of the cross strut 40 can be produced in the chill casting due to the gluing of the same, since the gluing makes less stringent demands on tolerances.

The advantages of bonding instead of welding in terms of weight reduction and cost reduction with at least stable stability of the wheelchairs come especially to bear when a special heat-curable, non-fluid adhesive is used in the context of the method according to the invention. In the context of this

Embodiment, it has proved to be particularly preferred according to the invention when the adhesive

a) at least one reactive epoxide prepolymer,

b) at least one latent curing agent for epoxides,

c) at least one propellant and

d) one or more elastomers,

contains.

The epoxy prepolymers, hereinafter also referred to as "epoxy resins", can

in principle be saturated, unsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic or heterocyclic polyepoxide compounds.

Suitable epoxy resins in the context of the present invention are, for example

preferably selected from bisphenol A type epoxy resins, epoxy resins from

Bisphenol S type, bisphenol F type epoxy resins, phenol novolac type epoxy resins, cresol novolak type epoxy resins, epoxidized products of various dicyclopentadiene modified phenolic resins, obtainable by reaction of dicyclopentadiene with numerous phenols, epoxidized products of 2,2 ', 6,6'-tetramethylbiphenol, aromatic epoxy resins such as epoxy resins with naphthalene skeleton and epoxy resins with fluorene skeleton, aliphatic epoxy resins such Neopentylglykoldiglycidylether and 1,6-hexanediol diglycidyl ether, alicyclic epoxy resins such as 3,4-Epoxycyclohexylmethyl-3,4 epoxycyclohexanecarboxylate and bis (3,4-epoxycyclohexyl) adipate, and epoxy resins having a hetero ring such as

Triglycidyl.

In particular, the epoxy resins include, for example, the reaction product of bisphenol A and epichlorohydrin, the reaction product of phenol and formaldehyde (novolak resins) and Epichlorohydrin, glycidyl ester and the reaction product of epichlorohydrin and p-aminophenol.

Other polyphenols which provide suitable epoxy resin prepolymers by reaction with epichlorohydrin (or epibromohydrin) are: resorcinol, 1,2-dihydroxybenzene, hydroquinone, bis (4-hydroxyphenyl) -1,1-isobutane, 4,4'-dihydroxybenzophenone, bis (4-hydroxyphenyl) -1, 1-ethane and 1, 5-hydroxynaphthalene.

Other suitable epoxy prepolymers are polyglycidyl ethers of polyalcohols or

Diamines. Such polyglycidyl ethers are derived from polyhydric alcohols, such as, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol,

Triethylene glycol, 1, 5-pentanediol, 1, 6-hexanediol or trimethylolpropane.

More preferred epoxy resins which are commercially available include, in particular, octadecylene oxide, epichlorohydrin, styrene oxide, vinylcyclohexene oxide, glycidol, glycidyl methacrylate, diglycidyl ethers of bisphenol A (eg, those sold under the trade names "Epon 828", "Epon 825", "Epon 1004" and "Epon 1010" from Hexion Specialty Chemicals Inc., "DER-331", "DER-332", "DER-334", "DER-732" and "DER736" from Dow Chemical Co.), vinylcyclohexene dioxide, 3 , 4-epoxycyclohexylmethyl-3,4-epoxycyclohexene carboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexene carboxylate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, bis (2,3-epoxy-cyclopentyl) ether, aliphatic, with

Polypropylene glycol modified epoxide, dipentene dioxide, epoxidized polybutadiene (eg Krasol products from Sartomer), epoxy functional silicone resin, flame retardant epoxy resins (eg "DER-580", a bisphenol type brominated epoxy resin available from Dow Chemical Co.), 1, 4-butanediol diglycidyl ether of a phenol-formaldehyde novolak (eg "DEN-431" and "DEN-438" of Dow Chemical Co.), and resorcinol diglycidyl ether (eg "Kopoxite" of Koppers Company Inc.), bis (3,4 epoxycyclohexyl) adipate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, vinylcyclohexene monoxide, 1,2-epoxyhexadecane, alkyl glycidyl ethers such as C8-C10 alkyl glycidyl ethers (eg "HELOXY Modifier 7" from Hexion Specialty Chemicals Inc.), C12-C14 alkyl glycidyl ethers (eg "HELOXY Modifier 8" from Hexion Specialty Chemicals Inc.), butyl glycidyl ether (eg "HELOXY Modifier 61 "from Hexion Specialty Chemicals Inc.), cresyl glycidyl ether (eg" HELOXY Modifier 62 "from Hexion Specialty Chemicals Inc.), p-tert-butylphenyl glycidyl ether (eg" HELOXY Modifier 65 "from Hexion Specialty Chemicals Inc.), polyfunctional Glycidyl ethers such as Diglycidyl ether of 1, 4-butanediol (e.g., "HELOXY Modifier 67" from Hexion Specialty Chemicals Inc.), diglycidyl ether of neopentyl glycol (e.g., "HELOXY Modifier 68" from Hexion Specialty Chemicals Inc.),

Diglycidyl ether of cyclohexanedimethanol (eg "HELOXY Modifier 107" of Hexion Specialty Chemicals Inc.), trimethylolethane triglycidyl ethers (eg "HELOXY Modifier 44" from Hexion Specialty Chemicals Inc.), trimethylolpropane triglycidyl ether (eg "HELOXY Modifier 48" from Hexion Specialty Chemicals Inc.), polyglycidyl ethers of an aliphatic polyol (eg "HELOXY Modifier 84 "from Hexion Specialty Chemicals Inc.), polyglycol diepoxide (eg" HELOXY Modifier 32 "from Hexion Specialty Chemicals Inc.), bisphenol F epoxides (eg" EPN-1 138 "or GY-281" from Huntsman Int. LLC), 9,9-bis-4- (2,3-epoxypropoxy) -phenylfluorenone (eg "Epon 1079" from Hexion Specialty Chemicals Inc.).

Further preferred commercially available compounds are, for. Selected from Araldite ™ 6010, Araldit ™ GY-281 ™, Araldit ™ ECN-1273, Araldit ™ ECN-1280, Araldit ™ MY-720, RD-2 from Huntsman Int. LLC; DEN ™ 432, DEN ™ 438, DEN ™ 485 from Dow Chemical Co., Epon ™ 812, 826, 830, 834, 836, 871, 872, 1001, 1031 etc. from Hexion Specialty Chemicals Inc. and HPT ™ 1071, HPT Also, for example, Epi-Rez ™ 5132 from Hexion Specialty Chemicals Inc., ESCN-001 from Sumitomo Chemical, Quatrex 5010 from Dow Chemical Co., RE 305S from Nippon Kayaku, Epiclon ™ N673 from DaiNipon Ink Chemistry or Epicote ™ 152 from Hexion Specialty Chemicals Inc.

Furthermore, the following polyepoxides can be used at least proportionally:

Polyglycidyl esters of polycarboxylic acids, for example reaction products of glycidol or epichlorohydrin with aliphatic or aromatic polycarboxylic acids such as oxalic acid,

Succinic acid, glutaric acid, terephthalic acid or dimer fatty acid.

The epoxide equivalent of suitable polyepoxides may vary between 150 and 50,000, preferably between 170 and 5,000. For example, an epoxy resin is based

Epichlorohydrin / bisphenol-A having an epoxide equivalent weight of 475 to 550 g / eq or an epoxide group content in the range of 1820 to 21 10 mmol / g. The softening point determined according to RPM 108-C is in the range of 75 ° C to 85 ° C.

Preferably, component a) is at least one epoxy resin which is solid at 22 ° C. and has reactive epoxy groups. To adjust the flexibility, it may be helpful to additionally provide at 22 ° C liquid or paste-like reactive epoxy resins.

The hardeners used are thermally activatable or latent hardeners for the epoxy resin binder system. These can be selected from the following compounds: guanidines, substituted guanidines, substituted ureas, melamine resins, guanamine derivatives, cyclic tertiary amines, aromatic amines and / or mixtures thereof. It can however, the hardeners may be stoichiometrically involved in the curing reaction, but they may also be catalytically active. Examples of substituted guanidines are methylguanidine, dimethylguanidine, trimethylguanidine, tetramethylguanidine, methylisobiguanidine,

Dimethylisobiguanidine, tetramethylisobiguanidine, hexamethylisobiguanidine,

Hepamethylisobiguanidine, and more particularly cyanoguanidine (dicyandiamide). Representatives of suitable guanamine derivatives include alkylated benzoguanamine resins, benzoguanamine resins or methoxymethylethoxymethylbenzoguanamine. Dicyandiamide is preferably suitable.

In addition to or instead of the aforementioned hardeners, catalytically active substituted ureas can be used. These are in particular the p-chlorophenyl-N, N-dimethylurea (monuron), 3-phenyl-1, 1-dimethylurea (Fenuron) or 3,4-dichlorophenyl-Ν, Ν-dimethylurea (diuron). In principle, it is also possible to use catalytically active tertiary acrylic or alkyl amines, for example the benzyldimethylamine, tris (dimethylamino) phenol, piperidine or piperidine derivatives. Furthermore, various, preferably solid imidazole derivatives can be used as catalytically active accelerators. Representative examples include 2-ethyl-2-methylimidazole, N-butylimidazole, benzimidazole and N-Ci to C12 alkylimidazoles or N-arylimidazoles. Furthermore, adducts of amino compounds to epoxy resins are suitable as accelerating additives to the aforementioned hardeners. suitable

Amino compounds are tertiary aliphatic, aromatic or cyclic amines. Suitable epoxy compounds are, for example, polyepoxides based on glycidyl ethers of

Bisphenol A or F or resorcinol. Concrete examples of such adducts are adducts of tertiary amines such as 2-dimethylaminoethanol, N-substituted piperazines, N-substituted homopiperazines, N-substituted aminophenols to di- or polyglycidyl ethers of bisphenol A or F or resorcinol.

As blowing agent c) are in principle all known blowing agents such. The "chemical blowing agents" which release gases by decomposition, or "physical blowing agents", i.

expanding hollow spheres. Examples of the former blowing agents are

Azobisisobutyronitrile, azodicarbonamide, di-nitrosopentamethylenetetramine, 4,4'-oxybis (benzenesulfonic acid) hydrazide, diphenylsulfone-3,3'-disulfohydrazide, benzene-1,3-disulfohydrazide, p-toluenesulfonyl semicarbazide. Particularly preferred are the expandable

Plastic microbeads based on polyvinylidene chloride copolymers or

Acrylonitrile / (meth) acrylate copolymers. These are eg under the name "Dualite ^® " resp.

"Expancel ^® " from the companies Pierce & Stevens and Casco Nobel commercially available.

The amount of propellant is preferably chosen so that the volume of the mass when heated to activation temperature (or expansion temperature) by at least 1%, preferably at least 5% and in particular at least 10% irreversibly increased. By this is meant that the mass in addition to the normal and reversible

thermal expansion according to their thermal expansion coefficient their volume compared to the initial volume at room temperature (22 ° C) when heated to the

Activation temperature irreversibly increased such that it is after re-cooling to room temperature by at least 1%, preferably at least 5% and in particular at least 10% greater than before. The stated degree of expansion thus refers to the volume of the mass at room temperature before and after the temporary heating to the activation temperature. The upper limit of the degree of expansion, ie the irreversible increase in volume, can be adjusted by the choice of the amount of blowing agent so that it is less than 300%, in particular less than 200%.

The blowing agent is activated according to the invention during the process step d) essential to the invention, so that the not yet cured adhesive expands.

In the context of the method according to the invention, it has proved to be advantageous if the adhesive film is thermally expandable, as this hollow or interstices between the Fügeteilen be filled and the bonds have increased stability.

Although in principle all known elastomers in the context of the present invention as

Component d) can be used, have in one invention

preferred embodiment, the elastomers proved to be particularly advantageous, which are selected from:

d1) thermoplastic polyurethanes

d2) thermoplastic isocyanates and / or

d3) block copolymers with thermoplastic polymer blocks.

With the help of these preferred elastomers, the mechanical stability of the bond over a wide temperature range could be ensured consistently.

In a first variant, the elastomer component d) may be a thermoplastic polyurethane d1) which may be reactive or non-reactive. In a preferred embodiment, the thermoplastic polyurethane is non-reactive in the sense that it is not further crosslinkable. In particular, this may be a polyurethane containing a polyester chain. The term "thermoplastic polyurethane", often abbreviated "TPU", is known to those skilled in the art. A TPU is an at least substantially linear polymer formed by the polymerization reaction of three starting components:

1. a diisocyanate,

 2. a short-chain diol (often referred to as "chain extender") of the general formula (OH-R-OH), wherein R is a hydrocarbon radical having 1 to 4 carbon atoms,

 3. a long-chain diol (OH-Z-OH), wherein the group Z is a polymer chain, which leads to a so-called soft segment of the resulting polyurethane.

 For example, the group Z may represent a polyether or polyester chain. Polyether chains may be formed by ring-opening polymerization of alkylene oxides such as ethylene oxide or propylene oxide or by a corresponding reaction of saturated oxygen-containing heterocycles such as tetrahydrofuran. Polyester chains are formed by the reaction of dibasic alcohols with dibasic carboxylic acids. A preferred polyester chain is polycaprolactone polyester.

In the implementation of these three components creates a polyurethane containing alternating soft segments and hard segments. The soft segments are formed by the group Z here. The hard segments are formed from the diisocyanate and the short-chain diol.

The polarity of the hard segments leads to a strong attraction between them, which in turn leads to a high degree of aggregation and order in the solid phase of the polymer. This results in crystalline or pseudo-crystalline regions embedded in the soft and flexible matrix of the soft segments. The crystalline and pseudo-crystalline regions of the hard segments act as a physical link, giving the TPU high elasticity. The flexible chains of the soft segments contribute to the expansion behavior of the polymer.

The thermoplastic polyurethane d1) is preferably solid at room temperature (22 ° C) and has a glass transition temperature below -20 ° C, preferably below -25 ° C. Furthermore, the thermoplastic polyurethane c1) which is preferably solid at room temperature has a melting range or softening range according to Kofier, which starts above 100 ° C., preferably above 115 ° C. Suitable at room temperature

preferably solid polyurethanes d1) are further distinguished by the fact that they are pure Substance have an elongation at break of at least 300%, preferably of at least 400%. Suitable thermoplastic polyurethanes d1) having these properties are in particular those which contain a polycaprolactone polyester chain or a polyester chain.

The weight-average molecular weight (Mw) of suitable polyurethanes d1), as represented by

Gel permeation chromatography is determined, is preferably in the range of 50,000 g / mol to 120,000 g / mol, in particular in the range of 55,000 g / mol to 90000 g / mol.

Suitable thermoplastic polyurethanes which satisfy the above criteria are commercially available and can be determined from these specifications, for example from the Fa.

Merquinsa in Spain or the Fa. Danquinsa GmbH in Germany.

Instead of or together with the reactive (crosslinkable) or non-reactive (non-crosslinkable) thermoplastic polyurethanes d1), the adhesive may contain thermoplastic isocyanates d2). These are further crosslinkable and react, for example with alcohols to thermoplastic polyurethanes, which in turn can meet the criteria for component d1). These thermoplastic isocyanates d2) may be

For example, be isocyanate-terminated polyether polyols, in particular those having a molecular weight in the range between 1000 and 10,000 g / mol.

Instead of or together with the reactive (crosslinkable) or non-reactive (non-crosslinkable) thermoplastic polyurethanes d1) and / or the thermoplastic

Isocyanates d2), the adhesive may be used as component d3) block copolymers

contain thermoplastic polymer blocks. These are preferably selected from those which have a first polymer block with a glass transition temperature of below 15 ° C, in particular below 0 ° C, and a second polymer block with a

Glass transition temperature of above 25 ° C, in particular from above 50 ° C included. Also suitable are those block copolymers selected from those in which a first polymer block is selected from a polybutadiene or polyisoprene block and a second polymer block is selected from a polystyrene or a polymethyl methacrylate block.

For example, the block copolymer d3) is selected from copolymers having the following block structure: styrene-butadiene (meth) acrylate, styrene-butadiene (meth) acrylic acid ester, ethylene (meth) acrylic acid ester glycidyl (meth) acrylic acid ester, ethylene (meth ) Acrylic acid ester-maleic anhydride, (meth) acrylic acid ester-butyl acrylate (meth) acrylic acid ester, preferably methyl methacrylate-butyl acrylate-methyl methacrylate Above, the composition of these block copolymers is defined by indicating the monomer unit for each block. This is to be understood that the block copolymer in each case contains polymer blocks of the monomers mentioned. In this case, up to 20 mol /% of the monomers mentioned can be replaced by other comonomers in the individual polymer blocks. In particular, this applies to blocks of poly-methyl methacrylate.

The abovementioned block copolymers correspond to those which can also be used in the context of WO 2007/025007. Further details on this and other block copolymers which are also suitable for the purposes of the present invention can be found in this document from page 25, line 21 to page 26, line 9. There you will also find

Cross references to documents describing the preparation of such block copolymers.

In addition to the above-described components, the adhesive used according to the invention may contain, as further component e), rubber particles, preferably those having a core-shell structure.

It is preferred that the core-shell rubber particles have a core of a polymeric material having a glass transition temperature below 0 ° C and a shell of a polymeric material having a glass transition temperature above 25 ° C. Particularly suitable rubber particles having a core-shell structure may comprise a core of a diene homopolymer, a diene copolymer or a polysiloxane elastomer and / or a shell of an alkyl (meth) acrylate homopolymer or copolymer.

For example, the core of these core-shell particles may be a diene homopolymer or

Copolymer which may be selected from a homopolymer of butadiene or isoprene, a copolymer of butadiene or isoprene with one or more ethylenically unsaturated monomers such as vinyl aromatic monomers, (meth) acrylonitrile, (meth) acrylates or similar monomers. The polymer or copolymer of the shell may contain, for example, as monomers: (meth) acrylates, in particular methyl methacrylate, vinylaromatic monomers (for example styrene), vinyl cyanides (for example acrylonitrile), unsaturated acids or anhydrides (for example acrylic acid), (meth) acrylamides and similar monomers leading to polymers with a suitable high glass transition temperature. The shell polymer or copolymer may have acid groups that can crosslink by metal carboxylate formation, for example by salification with divalent metal cations. Furthermore, the shell polymer or copolymer may be covalently crosslinked by employing monomers having two or more double bonds per molecule.

As the core, other rubbery polymers may be used, such as polybutyl acrylate or polysiloxane elastomers such as polydimethylsiloxane, especially crosslinked polydimethylsiloxane.

Typically, these core-shell particles are constructed such that the core accounts for 50 to 95 weight percent of the core-shell particle and the shell for 5 to 50 weight percent of this particle.

Preferably, these rubber particles are relatively small. For example, the

average particle size (as determined for example by light scattering methods) in the range of about 0.03 to about 2 μηι, in particular in the range of about 0.05 to about 1 μηι lie. However, smaller core-shell particles can also be used

for example, those whose average diameter is less than about 500 nm, in particular less than about 200 nm. For example, the average particle size may range from about 25 to about 200 nm.

The preparation of such core-shell particles is known in the art, as indicated for example in WO 2007/025007 on page 6, lines 16 to 21. Commercial sources of such core-shell particles are listed in this document in the last paragraph of page 6 through the first paragraph of page 7. Reference is made to these sources. Furthermore, reference is made to manufacturing methods for such particles, which are described in said document from page 7, 2nd paragraph to page 8, 1st paragraph. For further information on suitable core-shell particles, reference is also made to said document WO 2007/025007, which contains detailed information on page 8, lines 15 to page 13, line 15.

The same function as the above-mentioned rubber particles having a core-shell structure can adopt inorganic particles having a shell of organic polymers. Therefore, a further preferred embodiment of the present invention is characterized in that the composition of the invention as an additional component f) inorganic particles

contains, which have a shell of organic polymers. In this embodiment, the adhesive according to the invention contains inorganic particles which have a shell of organic polymers, wherein the organic polymers are preferably selected from homo- or copolymers of acrylic and / or methacrylic acid ester and at least 30 wt .-% of einpolymersiertem acrylic acid and or methacrylic acid esters exist.

The acrylic acid and / or methacrylic esters are preferably methyl and / or ethyl esters, more preferably at least a portion of the esters being present as methyl esters.

In addition, the polymers may also contain unesterified acrylic and / or methacrylic acid, which may improve the attachment of the organic polymers to the surface of the inorganic particles. Therefore, in this case, it is particularly preferable that the monomer units of unesterified acrylic and / or methacrylic acid are (near) at the end of the polymer chain which binds to the surface of the inorganic particles.

It is preferred that the organic polymers to at least 80 wt .-% of

Acrylic acid and / or methacrylic acid ester exist. In particular, they may consist of 90% by weight, 95% by weight or entirely thereof. Unless the organic polymers are different

Monomers as these acrylic acid and / or methacrylic acid esters or unesterified acrylic acid and / or methacrylic acid, these are preferably selected from comonomers having epoxy hydroxy and / or carboxyl groups.

The shell organic polymers are preferably uncrosslinked or so weakly crosslinked that no more than 5% of monomer units of one chain are crosslinked with monomer units of another chain. It may be advantageous that the polymers in the vicinity of the surface of the inorganic particles are more crosslinked than further out in the shell.

In particular, the sheath is preferably constructed so that at least 80%, in particular at least 90% and particularly preferably at least 95% of the polymer chains are attached at one end to the surface of the inorganic particles.

The inorganic particles preferably have an average particle size in the range from 1 to 1000, in particular in the range from 5 to 30 nm, prior to the application of the shell of organic polymers. As is known, the particle size can be determined by light scattering methods and by electron microscopy.

The shell of organic polymers has a lower density than the inorganic particles themselves. Preferably, the shell of organic polymers has a thickness such that the weight ratio of the inorganic core to the shell of organic polymers is in the range of 2: 1 to 1: 5, preferably in the range of 3: 2 to 1: 3. This is controllable by the choice of reaction conditions when growing the shell of organic polymers on the inorganic particles.

In general, the inorganic particles may be selected from metals, oxides,

Hydroxides, carbonates, sulfates and phosphates. It is also possible for mixed forms of oxides, hydroxides and carbonates, such as, for example, basic carbonates or basic oxides to be present. If inorganic particles of metals are selected, it is preferable to use iron, cobalt, nickel or alloys which consist of at least 50% by weight of one of these metals. Oxides, hydroxides or mixed forms thereof are preferably selected from among those of silicon, cerium, cobalt, chromium, nickel, zinc, titanium, iron, yttrium, zirconium and / or aluminum. Of these, mixed forms are possible, such as particles of aluminosilicates or of silicate glasses. Particularly preferred are zinc oxide,

Aluminum oxides or hydroxides and Si0 ₂ or the oxide forms of silicon referred to as "silicic acid" or Anglo-Saxon as "silica". Furthermore, the inorganic particles of carbonates, such as calcium carbonate, or sulfates, such as barium sulfate, exist. Of course it is also possible that particles with

present in different composition inorganic cores next to each other.

For the preparation of the inorganic particles which have a shell of organic polymers, one can proceed, for example, as described in WO 2004/11 1136 A1 using the example of the coating of zinc oxide with alkylene ether carboxylic acids. According to this procedure, the untreated inorganic particles are suspended in a non-polar or slightly polar solvent, and then monomers or prepolymers are added

Components of the shell closed, removes the solvent and starts the polymerization, for example radically or photochemically. Furthermore, the procedure described in EP 1 469 020 A1 can be followed, using as organic

Coating component for the particles used monomers or prepolymers of the shell material. Furthermore, production of the coated particles by "atom transfer radical polymerization" is possible, as has been described by way of example for the polymerization of n-butyl acrylate on silica nanoparticles in: G. Carrot, S. Diamanti, M. Manuszak, B.

Charleux, J.-P. Vairon: "Atom Transfer Radical Polymerization of n-Butyl Acrylates from Silica Nanoparticles", J. Polym., Part A: Polymer Chemistry, Vol. 39, 4294-4301 (2001).

Furthermore, it is possible to resort to production methods as described in WO 2006/053640. For the present invention, inorganic cores are to be selected, as described in WO 2006/053640 from page 5, line 24, to page 7, line 15, with their production methods. The coating of these cores is analogous as described in this document from p. 10, line 22, to p. 15, line 7. The proposal of this document may also be followed (page 15, lines 9 to 24) to subject the inorganic cores to a pretreatment before the polymerization of the shell. For this it says at the named place:

"In particular, when using inorganic cores, it may also be preferred that the core is subjected to a pre-treatment prior to the polymerization of the shell, which allows a tethering of the shell. This can usually consist in a chemical functionalization of the particle surface, as is known for a wide variety of inorganic materials from the literature. In particular, it may be preferable to provide such chemical functions on the surface, which enable a grafting of the shell polymers as a reactive chain end. Here are as examples in particular terminal

To name double bonds, epoxy functions, as well as polycondensable groups. The functionalization of hydroxyl-bearing surfaces with polymers is

For example, from EP-A-337 144 known ".

The adhesive of the invention may contain either only the said rubber particles or only the said coated inorganic particles or both types of particles at the same time.

By adding well-heat-conductive particles such as metal powder (which includes powder of metal alloys), the heat conduction in the adhesive and thus its curing behavior can be improved. Therefore, one embodiment of the adhesive according to the invention is that it additionally contains g) metal powder. Suitable metal powders may be selected from powders of iron

(in particular steel), aluminum, zinc, copper or alloys containing at least 50% by weight of one of these elements. Preference is given to using metal powder in which 90% by weight of the particles have a particle size which can be determined by sieve analysis in the range from 10 to 100 μm.

In general, the adhesives according to the invention furthermore contain fillers which are known per se, such as, for example, the various ground or precipitated chalks, carbon black, calcium Magnesium carbonates, talc, barite, silicas or silica, and in particular silicatic fillers of the type of aluminum-magnesium-calcium silicate, z. B. wollastonite, chlorite.

To reduce weight, the adhesive may contain so-called lightweight fillers in addition to the aforementioned "normal" fillers

Understand substances having a lower density than the rest of the adhesive into which they are incorporated. The addition of a light filler thus reduces the overall density of the adhesive. These can be selected from the group of hollow metal spheres such. As hollow steel balls, glass bubbles, fly ash (Fillite), hollow plastic balls based on phenolic resins, epoxy resins or polyesters, expanded hollow microspheres with

Wall material of (meth) acrylic acid ester copolymers, polystyrene, styrene (meth) acrylate copolymers and in particular of polyvinylidene chloride and copolymers of vinylidene chloride with acrylonitrile and / or (meth) acrylic acid esters, ceramic hollow spheres or organic light fillers of natural origin such as ground nutshells, for example the shells of cashew nuts, coconuts or peanuts, cork powder or coke powder. Particular preference is given to such lightweight fillers based on hollow microspheres, which in the cured adhesive a high compressive strength

guarantee.

In one possible embodiment, the adhesive additionally contains fibers, for example based on aramid fibers, carbon fibers, metal fibers - e.g. of aluminum, glass fibers, polyamide fibers, polyethylene fibers or polyester fibers, these fibers preferably being pulp fibers or staple fibers having a fiber length between 0.5 and 6 mm and a diameter of 5 to 20 μm. Particular preference is given here

Polyamide fibers of the type of aramid fiber or polyester fibers.

Furthermore, the curable compositions of the invention can be used other common auxiliaries and additives such. As plasticizers, rheology aids, wetting agents, adhesion promoters,

Contain aging inhibitors, stabilizers and / or color pigments.

Preferably, the adhesive contains the individual components in the following ranges of amounts. The quantities given are percentages by weight relative to the complete adhesive, the amounts to be chosen to give a total of 100% by weight: a) reactive epoxy prepolymer: at least 20, preferably at least 30 wt .-%, and up to 80, preferably up to 70 and in particular up to 60 wt .-%. In this case, either the entire proportion of epoxy prepolymer at 22 ° C is fixed, or one uses a mixture of reactive epoxy prepolymers, wherein one part of the epoxy prepolymer at 22 ° C solid and another part of the epoxy prepolymers at 22 ° C is liquid or pasty. (Pasty means that the mass can be spread into a film.) By the mixing ratio of solid and liquid at 22 ° C epoxy prepolymers can be adjusted whether the adhesive is tacky at 22 ° C or not: the less liquid epoxy Prepolymer is used, the lower the tackiness. For example, the quantitative ratio between solid at 22 ° C and liquid at 22 ° C or pasty epoxy prepolymers in the range of 10: 1 to 1: 10. b) Latent curing agent for epoxides: at least 1, preferably at least 2 wt .-%, and up to 10, preferably up to 8 wt .-%. In addition, a curing accelerator can be provided. If desired, it may be present in an amount in the range of at least 0.1, preferably at least 0.5, weight percent and up to 6 weight percent, preferably up to 5 and most preferably up to 3 weight percent. available. c) propellant: the required proportion of propellant depends on the desired degree of expansion and can be determined empirically. As an indication, a blowing agent content in the range of 0.2 to 1, 5 wt .-% serve. However, blowing agent contents of up to 5% and up to 10% by weight are also possible. d) One or more elastomers, preferably selected from: d1) thermoplastic

Polyurethanes, d2) thermoplastic isocyanates, d3) block copolymers with

thermoplastic polymer blocks: a total of at least 1, preferably at least 5 and in particular at least 10 wt .-%, and up to 70, preferably up to 50 wt .-%. Only one of the components d1) to d3) or two of these components or all three components can be present. Particularly preferred is at least one of the components d1) and d2), more preferably the component d1) is present. Together with this, the component d3) is preferably used in addition. In this case, the component d1) and / or d2) in total at least 1, preferably at least 5 wt .-%, and up to 35, preferably up to 25 wt .-% before and the component d3) to at least 1 wt. -% and up to 35 wt .-%, preferably up to 25 wt .-%. In addition to these elastomers, the adhesive may contain other polymers and copolymers with elastomeric properties or rubber particles e), preferably of core-scarf structure, for example copolymers of dienes (such as butadiene, isoprene) and (meth) acrylic acid or their esters. These may be in proportions (based on the total adhesive) of up to 20 wt .-% and in particular up to 10% by weight, and preferably more than 1% by weight, in particular more than 4% by weight. f) inorganic particles having a shell of organic polymers: not mandatory. If present: preferably a total of at least 5, preferably at least 10 wt .-%, and up to 45, preferably up to 35 and in particular up to 25 wt .-%. Amounts between 0 and 5 wt .-% are also possible. g) Metal powder: not mandatory. If present: preferably at least 0.1, in particular at least 5 wt .-%, and up to 40, preferably up to 25 wt .-%.

Further auxiliaries such as fillers and color pigments: 0 to a total of 60, preferably up to a total of 40 wt.%, In particular up to a total of 20 wt.%, And preferably at least 5, in particular at least 10 wt.

Depending on the purpose of use, the adhesive described above may be designed so that it is tacky at room temperature (22 ° C.) or not. As explained above, this can be adjusted in particular by the quantitative ratio of liquid and solid epoxy prepolymers.

The invention further proposes that the adhesive be provided in the form of a foam, a tape or a film. It could be shown in the context of the present invention that particularly stable compounds are obtained when the adhesive is an adhesive film, preferably with a layer thickness in the range of 0, 1 to 5 mm. In addition, this embodiment of the present invention is characterized by a significantly improved handling of the manufacturing process.

Due to the combination of raw materials according to the invention, the adhesive is in strip or sheet form in the uncured state at room temperature (22 ° C) flexible (ie it can be easily bent by hand by 90 ° or more) or even windable (ie it can by hand to rolled up in a roll without creating an internal cavity). It can be unhardened at 22 ° C to at least 100% stretch before it breaks. Therefore, it can be adapted to the different substrate geometries and in particular wound around cylindrical bodies.

For easier handling, the adhesive used according to the invention may be applied in tape or film form to a base, for example a carrier film. Therefor For example, a carrier foil of metal, for example of aluminum, is suitable. Depending on the application, this film may have a different stiffness, which may be between firm and easily bendable. This is under a carrier film a pad

understood that remains on the adhesive after curing.

Regardless, for ease of handling, it may be preferable for the adhesive to be coated on one or both sides with a peelable film, such as a release paper (e.g., siliconized paper), which is peeled off prior to application or cure. Embodiments are also possible in which the adhesive applied in tape or foil form is covered on one side with a foil, for example a metal foil, and on the other side with a release paper. The use of release papers has proven to be particularly advantageous for the adhesive films, which are tacky at room temperature.

To prepare the adhesive used according to the invention, the individual components are mixed with one another, preferably at a temperature in the range from 50 to 120.degree. (depending on the process step). If this is done in a stirred tank or kneader, the mixture can then be poured onto a substrate such as a release paper and streaked or rolled out to a tape or a film. Alternatively, the components may be mixed in a mixing chamber of an extruder and then extruded through a suitably shaped mouthpiece in the form of a ribbon, if desired also on a release paper. Instead of the release paper, a carrier foil such as a metal foil can be used in both cases.

With the invention can also be provided that by the unit of the first and the second element

 a combination of a backrest of a wheelchair with a side frame of a wheelchair or

 a cross strut

provided.

Finally, the invention also relates to a wheelchair with a wheelchair frame, which has at least one unit of at least two elements, which in an inventive

Procedures are interconnected. The features disclosed in the preceding description, the claims and the drawings can be used individually as well as in any combination for the

Implementation of the invention in its various embodiments essential.

Examples

The raw materials 1 to 7 according to the following table were mixed together at a temperature of 120 ° C in a planetary mixer. The further process steps take place at a temperature of max. 60 ° C.

By means of a heated press, the material is formed into strips with a thickness of 0.2 mm.

The respective quantities are understood - unless otherwise stated - in weight.

The adhesive tapes produced were used to make a wheelchair. The conventional welds for connecting pipes were replaced by bonding according to the invention. After curing of the bonds in the course of drying the powder coating a stable wheelchair frame was obtained. LIST OF REFERENCE NUMBERS

1 wheelchair frame

 2 side pipe

 2 'side tube

 2a, 2b side frame tubes

 3 backrest tube

 3 'backrest tube

 3a, 3b backrest tubes

 4a, 4b cross struts

 5a, 5b seat tubes

 6a, 6b Radachsenaufnahmen

 10 side frame tube connection element

20 adhesives

 40 cross strut

 40 a seat tube intake

 40 b fork

 41, 42, 43 Cross strut elements

Claims

claims 1. A method for connecting at least two elements of a wheelchair with each other, comprising the following method steps:  a) providing a first element with a receiving region for at least partially receiving at least one connecting region of a second element,  b) placing a thermosetting, non-fluid adhesive in the  Receiving region of the first element and / or on the connecting region of the second element, which is provided for at least partially receiving by the receiving region of the first element,  c) at least partially inserting the connection region of the second  Elementes in the receiving area of the first element, and  d) thermally curing the adhesive between the first and second  Element. 2. The method according to claim 1, characterized in that the first element in tube form and / or the second element is formed in tubular form or be, preferably wherein the tubular shape has an oval or polygonal cross-section. 3. The method according to any one of claims 1 or 2, characterized in that at least one recess, in particular in the form of a groove, is formed in the connecting region of the second element and / or in the receiving region of the first element for filling with the adhesive. 4. The method according to any one of claims 1 to 3, characterized in that between the steps c) and d) fixing of the introduced into the receiving region of the first element connecting portion of the second element, for example by a fixing means, preferably using at least one screw as  Fixing agent, is made. 5. The method according to any one of claims 1 to 4, characterized in that the  thermosetting, non-fluid adhesives  a) at least one reactive epoxide prepolymer, b) at least one latent curing agent for epoxides, c) at least one propellant and  d) one or more elastomers,  contains. 6. The method according to claim 5, characterized in that the or the  Elastomers are selected from:  d1) thermoplastic polyurethanes  d2) thermoplastic isocyanates  d3) block copolymers with thermoplastic polymer blocks. 7. The method according to any one of claims 1 to 6, characterized in that the  Adhesive is an adhesive film with a layer thickness in the range of 0.1 to 5 mm. 8. The method according to any one of claims 1 to 7, characterized in that a connection of a backrest of a wheelchair with a side frame of a wheelchair or a cross strut is provided by the unit from the first and the second element. 9. The method according to any one of claims 1 to 8, characterized in that the thermal curing of the adhesive takes place in an oven during a refining process. A wheelchair having a wheelchair frame (1) comprising at least one unit of at least two elements (20, 3; 2 ', 3'; 40b, 41, 42, 43, 40a) which together in a method according to any one of the preceding claims are connected.