Device for injecting foamable material into a mold and method for producing a flat foam part

Abstract

The invention relates to a device for injecting a foamable material into a mould (27) for forming a flat foamed part, comprising: a tube (31) having a first end (35) through which the tube can be connected to a nozzle (21) of an injection device; and a flow separator (33) for dividing the foamable material into at least two partial flows, the flow separator (33) being placed at a second end (37) of the tube (31) opposite the first end (35). The invention also relates to a method for producing a flat foamed part using such a device.

Description

[0001] The present invention relates to an apparatus for injecting a foamable material into a mold for forming a flat foamed part, and a method for producing a flat foamed part by providing a foamable material in an injection apparatus and injecting the foamable material into the mold through a nozzle.

[0002] Foaming parts are usually prepared by injecting a foamable material into a mold. Such foamable materials can be, for example, a polymer melt comprising a foaming agent or a multi-component system. If the foamable material is a multi-component system, the system usually comprises at least two components that form a polymer by reaction and an additional foaming agent. If the foaming agent is a physical foaming agent, the foaming agent evaporates by heat of reaction. If a chemical foaming agent is used, a component (for example, isocyanate, if the polymer is polyurethane) of the foaming agent and the polymer reacts to form a gas, such as carbon dioxide. Due to the volume expansion caused by evaporation or by chemical reaction to form a gas, foam is produced.

[0003] To form flat foamed parts, particularly in batch processes, a predetermined amount of foamable material is injected into a mold. Within the mold, the blowing agent expands, causing the foam to completely fill the mold. However, because the foamable material typically reaches only specific areas of the mold during injection, the resulting foamed part may have unevenly distributed cells or cells of varying sizes. This uneven distribution often results in a foamed part with localized density differences.

[0004] In order to produce foamed parts with a uniform density distribution, it is known, for example from EP-A 3 278 949, to fill a mold with a reactive mixture, wherein a jet of the reactive mixture is injected into the mold, a pool is formed in the middle region of the mold, the jet causes the pool of reactive mixture to slide forward, and after the pool has reached a predetermined position, further reactive mixture is injected to overfill the mold.

[0005] WO-A 2013 / 164274 describes a method in which a foam-forming reaction mixture is introduced into a mold under a variable injection pressure. Due to the variable injection pressure, the reaction mixture is injected into different areas of the mold, thereby achieving a more uniform density distribution.

[0006] Another method for injecting a reaction mixture into different areas of a mold is disclosed in EP-A 2 366 525. Here, the reaction mixture is injected into the mold at different flow rates and injection speeds, thereby pouring the reaction mixture into different deposition areas of the mold.

[0007] JP-A 2006-142125 describes a method for filling a mold for producing foamed polyurethane articles using a comb-shaped nozzle having a large number of holes in a straight tube. However, this nozzle is used to apply the reaction mixture to a belt or carrier, wherein the comb-shaped nozzle or belt is moved. Therefore, this nozzle cannot be used to produce foamed parts in a closed mold.

[0008] An object of the present invention is to provide an apparatus and method for forming a foamed part, which allows a simple injection process without changing injection parameters during injection and can be easily applied to conventional injection devices.

[0009] This object is achieved by a device for injecting a foamable material into a mold for forming a flat foamed part, the device comprising: a tube having a first end, the tube being connectable to a nozzle of an injection device via the first end; and a flow separator for dividing the foamable material into at least two partial flows, the flow separator being placed at a second end of the tube opposite to the first end so that the at least two flows enter the mold separately.

[0010] The method for producing a flat foamed part comprises:

[0011] (a) providing a foamable material in an injection device;

[0012] (b) injecting a foamable material into the mold through a nozzle;

[0013] Therein the device for injecting the foamable material is connected to the nozzle of the injection device in such a way that the foamable material is divided into at least two partial flows which enter the mould.

[0014] Surprisingly, it has been shown that when a tube together with a flow separator is connected to the nozzle of an injection device, flat foamed parts with a substantially uniform cell distribution and size can be produced.

[0015] In the sense of the present invention, a "flat component" is a component whose length is at least 7 times the height of the component and whose width is in the range between 4 times the height of the component and 0.8 times the length of the component. The length is preferably in the range from 7 to 300 times the height of the component, and in particular in the range from 30 to 150 times the height of the component, and the width is preferably in the range from 4 to 75 times the height of the component, and preferably in the range from 5 to 25 times the height of the component.

[0016] In the sense of the present invention, the width and length of a component correspond to the length of a line between two opposite points along the longitudinal axis of the tube (the line intersects the outer peripheral surface of the component at these two opposite points), and the length of the longest line between two opposite points perpendicular to the longitudinal axis of the tube and intersecting the longitudinal axis of the tube (the line perpendicular to the longitudinal axis of the tube intersects the outer peripheral surface of the component at these two opposite points), where the longer line corresponds to the length of the component and the shorter line corresponds to the width of the component, and the height is the maximum height.

[0017] The flat parts produced by the method of the present invention can have a base of any shape and can have a constant height or a varying height. Preferably, the flat parts have a base with an axisymmetric geometry and a constant height, and particularly preferably, the flat parts produced by the method of the present invention have a rectangular base and a constant height. Regardless of the shape of the base, the part may include, for example, grooves, tabs, pitches, or steps along at least one side. In this context, if the flat part has a varying height, the "base" corresponds to the intersecting plane formed by the length and width of the part, or if the part with varying height has a flat surface perpendicular to the height of the part, the "base" corresponds to this flat surface. If the part has a constant height, the "base" corresponds to one of the surfaces perpendicular to the height of the part, and if the surfaces perpendicular to the height of the part have different sizes, the "base" corresponds to the larger surface. The "sides" of a part with constant height are the surfaces connecting the surfaces perpendicular to the height of the part.

[0018] The flat foamed part can be, for example, a foamed panel or a composite element. If the flat foamed part is a composite element, it generally comprises a first sheet and a second sheet and a foamed layer located between the first sheet and the second sheet.

[0019] Flat parts produced by the process according to the invention are, for example, wall or roof elements of walk-in coolers, several types of doors, sandwich elements for construction, refrigerator doors, elements (walls, roofs, doors) for refrigerated vehicles.

[0020] For the production of flat parts, the device for injecting the foamable material is preferably arranged so that the outlet of the tube is directed towards the geometric center of the part. If the flat part has a rectangular base, the tube preferably enters the mold for producing the part at the center of one of the sides having the largest surface. If the flat part has a triangular base, the tube preferably enters the mold at the vertex of the triangle that limits the shortest height of the triangle. If the base of the flat part has four or more edges or has an irregular shape, the tube preferably enters the mold at a point on the peripheral surface where a perpendicular line to the longest distance between two opposite points on the edge of the base of the part (which intersects the geometric center of the part) intersects the peripheral surface. Regardless of the position at which the tube enters the mold, it is preferred that the tube be arranged so that the longitudinal axis of the tube intersects the geometric center of the mold.

[0021] Since the nozzle through which the foamable material exits the injection device typically has a circular cross-section, the tube connected to the nozzle also has a circular cross-section. To ensure sufficient cross-sectional area at the tube outlet, the flow separator preferably has an elliptical base, and to separate the foamable material into two streams, the flow separator has a straight edge opposite the base. If the flow separator has an elliptical base, the straight edge preferably lies in a plane defined by the major axis of the elliptical base and a perpendicular to the elliptical base (which intersects the major axis).

[0022] In order to separate the foamable material into two flows, the flow separator is also arranged so that the straight edge faces the nozzle and the bottom of the flow separator faces the cavity of the mould.

[0023] The side surface between the bottom and the straight edge of the flow separator may have a plane surface. In this case, the flow separator has the shape of an elliptical cylinder that is obliquely truncated to the bottom on both sides of the major axis.

[0024] Preferably, however, the surface is curved and corresponds at the bottom to the edge of the bottom and becomes flat in the direction of the straight edge.

[0025] In order to evenly separate the foamable material into two streams, it is further preferred that the flow separator has a cross-section in the shape of an isosceles triangle. If the flow separator has an elliptical base and the side surfaces are curved, it is preferred that each cross-section perpendicular to the major axis of the elliptical base has the shape of an isosceles triangle.

[0026] The isosceles triangle formed with the minor diameter of the elliptical base as its base can have any suitable vertex angle. Preferably, the vertex angle is in the range of 10° to 150°, more preferably in the range of 20° to 70°, and particularly in the range of 30° to 90°. The suitable angle depends on the length-to-width ratio of the foamed component. The smaller the length-to-width ratio, the larger the vertex angle.

[0027] Depending on the shape of the cavity in the mould, and therefore on the shape of the foamed part to be produced by using the device for injecting the foamable material into the mould, it may be necessary to use different flow separators.

[0028] In addition, in order to set the direction in which each stream is injected into the mold, and further in order to give each stream the desired size of opening through which it is fed into the mold, the tube preferably includes two opposing cutouts at the end where the flow separator is located. Particularly preferably, the cutouts are symmetrical with respect to the straight edge of the flow separator. The geometric shape of the cutouts can be any suitable shape, for example, a rectangular, triangular, or semi-elliptical or semi-circular shape. Particularly preferably, the cutouts have a semi-elliptical or semi-circular shape.

[0029] If it is intended that the injection device be used together with different molds, it may be necessary to provide different flow separators. For this reason, the flow separator should be releasably connected to the pipe, wherein each type of releasable connector can be used. Such connectors are, for example, threaded connectors, bayonet couplings, fixtures, latches or snap locks. In order to be easy to replace the flow separator, it is preferably used to connect the flow separator to the pipe using a fixture, latch, bayonet coupling or snap lock.

[0030] The flow separator and the tube can be made of the same material or different materials. Suitable materials for the tube and flow separator include metals such as steel, aluminum, brass, or polymers such as PE, PP, PU, ​​PA, and PC, with the tube and flow separator being made of different materials. Preferably, the flow separator is made of a material suitable for 3D printing, extrusion, or injection molding. Particularly preferably, the tube is made of steel or PP, and the flow separator is made of PP.

[0031] To produce a foamable component, a foamable material is provided in an injection device and injected from the injection device into a mold through a nozzle. To inject the foamable material, a tube is connected to the nozzle along with the device described above, which is used to separate the foamable material into at least two streams. After filling the mold, the foamable material solidifies, forming a foam. After solidification, the resulting foamable component is removed from the mold, and new foamable material can be injected into the mold to produce the foamable component.

[0032] The injection device for injecting the foamable material can be any injection device known to the skilled person. Preferably, the injection device used for injecting the foamable material into the mold is an injection device for injecting a foamable material comprising at least two components (which react to form a polymer) and a blowing agent. Such an injection device is, for example, a mixing head for injecting a multi-component system into a mold.

[0033] The multi-component system which can be injected into a mold to form a foamed part is preferably a system comprising a mixture of two components which react to form a polymer and a blowing agent. Suitable multi-component systems are all systems in which monomers and / or oligomers are mixed and then react to form a polymer and which may comprise a blowing agent to form a foam.

[0034] Such multi-component systems comprise, for example, at least one polyisocyanate (A), at least one isocyanate-reactive compound (B), and at least one chemical and / or physical blowing agent (C). Furthermore, the multi-component system may comprise at least one catalyst (D), stabilizers, and, in some cases, flame retardants and / or other additives (E). Suitable polyisocyanates (A) in this case are, for example, methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), or hexamethylene diisocyanate (HDI), and isocyanate-reactive compounds (B) are, for example, polyether polyols.

[0035] The polyisocyanates (A) are aromatic polyfunctional isocyanates known in the prior art. Such polyfunctional isocyanates are known and can be prepared by methods known per se. The polyfunctional isocyanates can also be used in the form of mixtures, so that component (A) in this case contains different polyfunctional isocyanates. The polyisocyanates (A) are polyfunctional isocyanates having two isocyanate groups (hereinafter also referred to as diisocyanates) or more than two isocyanate groups per molecule. Isocyanate (A) is particularly selected from the group consisting of aromatic polyisocyanates, such as 2,4- and 2,6-toluene diisocyanate and the corresponding isomer mixtures, 4,4'-, 2,4'-, and 2,2'-diphenylmethane diisocyanate and the corresponding isomer mixtures (also known as monomeric diphenylmethane or MMDI), for example a mixture of 4,4'- and 2,4'-diphenylmethane diisocyanate, a mixture of at least one isomer of diphenylmethane diisocyanate and higher-nuclear homologues of diphenylmethane diisocyanate having at least three aromatic nuclei and a functionality of at least 3, also known as polyphenylpolymethylene polyisocyanates or polymeric MDI. MDI isomers and homologues are generally obtained by distillation of crude MDI. In addition to dinuclear MDI (MMDI), polymeric MDI also comprises one or more polynuclear condensation products of MDI having a functionality greater than 2 (in particular 3, 4, or 5). Polymeric MDI is known and is generally described as polyphenylpolymethylene polyisocyanate. Also useful as isocyanate (A) are mixtures of 4,4'-, 2,4'-, and 2,2'-diphenylmethane diisocyanate and polyphenylpolymethylene polyisocyanate (crude MDI), as well as mixtures of crude MDI and toluene diisocyanate. Particularly suitable are 2,2'-, 2,4'-, or 4,4'-diphenylmethane diisocyanate (MDI), as well as mixtures of two or three of these isomers, 1,5-naphthylene diisocyanate (NDI), 2,4- and / or 2,6-toluene diisocyanate (TDI), 3,3'-dimethyldiphenyl diisocyanate, 1,2-diphenylethane diisocyanate, and / or p-phenylene diisocyanate (PPDI).

[0036] The polyisocyanate of component (A) particularly preferably comprises 2,2'-MDI or 2,4'-MDI or 4,4'-MDI or a mixture of monomeric diphenylmethane diisocyanate or a mixture of monomeric diphenylmethane diisocyanate with higher nuclear homologues of MDI. The average functionality of the polyisocyanate comprising polymeric MDI can vary in the range from about 2.2 to about 4, preferably from 2.4 to 3.8, in particular from 2.6 to 3.0. Polyfunctional isocyanates or mixtures of two or more polyfunctional isocyanates based on MDI are known and are available under the trade name M20, M50 or M70 is commercially available from BASF Polyurethanes GmbH.

[0037] The isocyanate-reactive compound (B) used can be selected from any compound known in polyurethane chemistry having isocyanate-reactive groups, preferably a compound having an average of at least 1.5 isocyanate-reactive groups (such as hydroxyl groups, -NH groups, NH2 groups or carboxylic acid groups, preferably NH2 groups or OH groups), in particular at least 1.5 OH groups. The average functionality of the compounds of component (B) with respect to isocyanate groups is in the range of at least 1.5 (preferably 1.6) to 8.0, particularly preferably in the range of 2 to 5.0, in particular 3 to 4.5.

[0038] The compound (B) having at least two isocyanate-reactive hydrogen atoms comprises at least one polyether polyol.

[0039] In a preferred embodiment, the polyether polyols have a hydroxyl number of preferably 100 KOH / g to 1000 KOH / g and are prepared by alkoxylation of starters or starter mixtures.

[0040] The polyether polyols are prepared by known methods, for example by anionic polymerization of one or more alkylene oxides having 2 to 4 carbon atoms with customary catalysts.

[0041] Preferred alkoxylation catalysts are KOH and amine alkoxylation catalysts.

[0042] Suitable alkylene oxides include, for example, tetrahydrofuran, 1,3- and 1,2-propylene oxide, 1,2- and 2,3-butylene oxide, styrene oxide, ethylene oxide, and preferably 1,2-propylene oxide.

[0043] The hydroxyl value of the polyether polyol may be 100 mg KOH / g to 1000 mg KOH / g, preferably 200 mg KOH / g to 800 mg KOH / g, and particularly preferably 250 mg KOH / g to 500 mg KOH / g.

[0044] Blowing agents (C) for preparing rigid polyisocyanurate foams preferably include water, formic acid, and formic acid-water mixtures. These blowing agents react with isocyanate groups to form carbon dioxide and carbon monoxide. Since these blowing agents release gas via a chemical reaction with the isocyanate groups, they are referred to as chemical blowing agents. Alternatively, physical blowing agents, such as low-boiling hydrocarbons, can be used. Suitable physical blowing agents include, in particular, liquids that are inert toward the polyisocyanate (A) and have a boiling point below 100°C, preferably below 50°C, at atmospheric pressure, and therefore evaporate under the influence of the exothermic polyaddition reaction.

[0045] Physical blowing agents that can be used include, for example, alkanes (such as heptane, hexane, n-pentane and isopentane (preferably an industrial mixture of n-pentane and isopentane), n-butane and isobutane, and propane); cycloalkanes (such as cyclopentane and / or cyclohexane); ethers (such as furan, dimethyl ether, and diethyl ether); ketones (such as acetone and methyl ethyl ketone); alkyl carboxylates (such as methyl formate, dimethyl oxalate, and ethyl acetate); and halogenated saturated and unsaturated hydrocarbons (such as dichloromethane, dichloromonofluoromethane, difluoromethane, trifluoromethane, and methyl ethyl ketone). fluoromethane, difluoroethane, tetrafluoroethane, chlorodifluoroethane, 1,1-dichloro-2,2,2-trifluoroethane, 2,2-dichloro-2-fluoroethane and heptafluoropropane); and unsaturated hydrocarbons such as trifluoropropene and tetrafluoropropene (such as (HFO-1234)), pentafluoropropene (such as (HFO-1225)), chlorotrifluoropropene (such as (HFO-1233)), chlorodifluoropropene, chlorotetrafluoropropene and hexafluorobutene); and mixtures of one or more of these components. Preference is given to using tetrafluoropropene, pentafluoropropene, chlorotrifluoropropene and hexafluorobutene in which the unsaturated terminal carbon atom carries at least one chlorine or fluorine substituent. Examples include 1,3,3,3-tetrafluoropropene (HFO-1234ze); 1,1,3,3-tetrafluoropropene; 1,2,3,3,3-pentafluoropropene (HFO-1225ye); 1,1,1-trifluoropropene; 1,1,1,3,3-pentafluoropropene (HFO-1225zc); 1,1,2,3,3-pentafluoropropene (HFO-1225yc); 1-chloro-2,3,3,3-tetrafluoropropene (HFO-1224yd); 1,1,1,2,3-pentafluoropropene (HFO-1225yez); 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd); and 1,1,1,4,4,4-hexafluorobut-2-ene (HFO-1336mzz). Mixtures of these low-boiling liquids with each other and / or with other substituted or unsubstituted hydrocarbons may also be used.

[0046] Likewise suitable are organic carboxylic acids, such as formic acid, acetic acid, oxalic acid, ricinoleic acid, and carboxyl-containing compounds.

[0047] The catalyst (D) used for preparing the rigid polyisocyanurate foam according to the invention is in particular a compound which significantly accelerates the reaction of the compounds containing reactive hydrogen atoms (especially hydroxyl groups) of components (B) to (E) with the polyisocyanate (A).

[0048] Advantageously employed compounds include, for example, basic polyurethane catalysts, for example, tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, dicyclohexylmethylamine, dimethylcyclohexylamine, N,N,N',N'-tetramethyldiaminodiethyl ether, bis(dimethylaminopropyl)urea, N-methylmorpholine or N-ethylmorpholine, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N,N-tetramethylbutanediamine, N,N,N,N-tetramethylhexane-1,6-diamine, pentamethyldiethylenetriamine, bis(2-dimethylaminoethyl)ether, dimethyl Piperazine, N-dimethylaminoethylpiperidine, 1,2-dimethylimidazole, 1-azabicyclo[2,2,0]octane, 1,4-diazabicyclo[2,2,2]octane (Dabco); and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyl and N-ethyldiethanolamine, dimethylaminoethanol, 2-(N,N-dimethylaminoethoxy)ethanol, N,N',N"-tris(dialkylaminoalkyl)hexahydrotriazines (e.g., N,N',N"-tris(dimethylaminopropyl)-s-hexahydrotriazine) and triethylenediamine.

[0049] However, other suitable catalysts include metal salts such as ferrous chloride, zinc chloride, lead octoate, and tin salts (such as tin dioctoate, tin diethylhexanoate, and dibutyltin dilaurate), as well as mixtures of tertiary amines and metal salts (particularly organotin salts). Contemplated catalysts also include amidines (such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine); tetraalkylammonium hydroxides (such as tetramethylammonium hydroxide); alkali metal hydroxides (such as sodium hydroxide) and alkali metal alkoxides (such as sodium methoxide and potassium isopropoxide); alkali metal carboxylates; and alkali metal salts of long-chain fatty acids having 8 to 20 carbon atoms and optionally pendant OH groups.

[0050] Contemplated catalysts also include incorporable amines, preferably amines having -OH, -NH or -NH2 functional groups, such as ethylenediamine, triethanolamine, diethanolamine, ethanolamine and dimethylethanolamine. Incorporable catalysts can be considered to be compounds of component (B) as well as compounds of component (D).

[0051] The reaction can also be carried out without catalysis. In this case, the catalytic activity of the amine-initiated polyol is generally utilized.

[0052] Catalysts for the trimerization of excess NCO groups with one another also include isocyanurate-forming catalysts, such as ammonium ion salts or alkali metal salts, in particular ammonium carboxylates or alkali metal carboxylates, alone or in combination with tertiary amines. The formation of isocyanurates results in flame-retardant PIR foams, which are preferably used in rigid foams for technical applications, for example as insulation sheets or sandwich elements in the construction industry.

[0053] The reaction mixture for preparing the polyisocyanate foam according to the invention may optionally be admixed with further auxiliaries and / or additives (E). These include, for example, surfactants, foam stabilizers, cell regulators, fillers, light stabilizers, dyes, pigments, antihydrolysis agents, fungistatic and bacteriostatic substances.

[0054] In a preferred embodiment, Components B through E are mixed to form the isocyanate-reactive component.

[0055] To produce foamed parts, each component is usually fed separately into the space of a mixing head and then injected into the mold by driving a piston into the space of the mixing head, whereby the mixture formed in this space is injected into the mold through the nozzle of the mixing head.

[0056] Embodiments of the invention are shown in the drawings and are explained in more detail in the following description.

[0057] In the attached figure:

[0058] Figure 1 A method for preparing a foamed part is schematically shown;

[0059] Figure 2 The device for injecting a foamable material of the present invention is shown in a top view;

[0060] Figure 3 A cross-sectional view of the device for injecting a foamable material according to the present invention is shown;

[0061] Figure 4 shows a side view of the apparatus for injecting a foamable material according to the present invention;

[0062] FIG5 a shows a tube of a device for injecting a foamable material according to the present invention;

[0063] FIG5 b shows the tube of FIG5 a in a position rotated 90°;

[0064] FIG6 a shows a flow separator of the device for injecting foamable material according to the present invention;

[0065] FIG6 b shows the flow separator of FIG6 a in a position rotated 90°;

[0066] Figure 7 The distribution of the foamable material in the mould is shown.

[0067] Figure 1 The method for producing a foamed part is schematically shown.

[0068] To produce a foamed component using a multi-component system, in particular a two-component system, a first component is provided in a first container 1 and a second component is provided in a second container 3. The first container 1 is connected to a mixing head 5 via a first connecting line 7, and the second container 3 is connected to the mixing head 5 via a second connecting line 9. The first connecting line 7 comprises a first dosing unit 11 for dosing the first component into the mixing head 5, and the second connecting line 9 comprises a second dosing unit 13 for dosing the second component into the mixing head 5. In the mixing head 5, the first component and the second component are mixed, and a blowing agent 15 is also added to the mixing head 5 to generate the foam.

[0069] In the mixing head 5, the components are mixed and then injected into the mold 27 through the nozzle 21. In the mold 27, the mixture comprising the first component and the second component solidifies and forms a polymer. Due to the blowing agent, the polymer forms a foam.

[0070] In order to achieve a uniform distribution of the cells in the foam, a device for injecting the foamable material is used, which comprises a tube and a flow separator. Figure 2 In the top view, Figure 3 is shown in cross-section and in Figure 4 Shown in side view.

[0071] The device 29 for injecting the foamable material comprises a pipe 31 and a flow separator 33. The pipe 31 has a circular cross section and is connected to the nozzle 21 of the mixing head 5 via a first end 35. The flow separator 33 is connected to the pipe 31 at a second end 37 opposite the first end.

[0072] As in Figure 2 As can be seen in the top view of , the flow separator 33 has an oval bottom 39. By using an oval bottom, the foamable material is not redirected at 90°, but at a smaller angle and thus has a flow direction that is inclined relative to the longitudinal axis 41 of the tube.

[0073] In order to separate the foamable material into two partial flows, the flow separator 33 has a straight edge 43. The flow separator 33 is placed in the pipe 31 so that the straight edge 43 faces the nozzle 21 of the mixing head 5. The bottom 39 of the flow separator 33 thus points in the direction of the mold 27.

[0074] To avoid a reduction in the cross-sectional area through which the foamable material flows, cutouts 45 are provided in the tube 31. The cutouts 45 preferably have a semicircular or semi-elliptical shape and are positioned so that a line connecting the highest points 47 of the cutouts 45 extends perpendicular to the straight edge 43 of the flow separator 33.

[0075] In addition to the geometric shape shown here, the pipe can also have any other cross-sectional shape, such as oval, rectangular, square or any other shape. However, since the nozzle of the injection device such as the mixing head usually has a circular shape, it is preferred to use a pipe with a circular shape. In addition to the oval shape shown, the bottom of the flow separator 33 can also have any suitable shape, such as a circular shape, a rectangular shape or a square shape. Therefore, the shape of the bottom of the flow separator 33 depends on the cross-sectional shape of the pipe 31. If the pipe has a circular cross-sectional shape, it is preferred to use a flow separator 33 with an oval bottom. If a pipe with an oval cross-sectional shape is used, the flow separator 33 can also have an oval bottom or alternatively have a circular bottom. If a pipe with a square cross-sectional shape is used, it is preferred to use a flow separator with a rectangular shape, and if a pipe with a rectangular shape is used, the bottom of the flow separator can have a rectangular or square shape. In this article, rectangle refers to every rectangle except the square.

[0076] In addition, the cutout 45 may also have any other shape, such as a triangle, rectangle or square. However, in order to prevent the foamable material from being deposited at the corners of these shapes, it is preferred that the cutout 45 has a semicircular shape, a semi-elliptical shape or a circular segment shape.

[0077] The surface 48 of the flow separator 33 may be flat or curved. Regardless of whether the surface 48 is flat or curved, it is preferred that the cross-sectional shape of the flow separator 33 at the short diameter of the elliptical base has an isosceles triangle shape. Preferably, the surface 48 of the flow separator 33 is curved so that each cross-sectional shape of the flow separator 33 perpendicular to the long diameter of the elliptical base has an isosceles triangle shape.

[0078] The isosceles triangle with the minor diameter of the elliptical base as the base may have any suitable vertex angle. Preferably, the vertex angle is in the range of 10° to 80°, more preferably in the range of 20° to 70°, and particularly in the range of 30° to 60°.

[0079] The tube 31 of the device for injecting a foamable material into a mould according to the invention is shown in more detail in Figures 5a and 5b.

[0080] In order to be easy to replace flow separator 33, preferably flow separator 33 is releasably connected to pipe 31. Such releasable connection is, for example, a threaded connection, a bayonet coupling or a coupling utilizing a latch, a fixture or a spring lock. In the embodiment shown in Figures 5 a to 6 b, flow separator 33 is connected to pipe by a fixture. In order to couple flow separator 33 to pipe 31, pipe 31 includes a recess 49, into which the fixture of flow separator 33 engages. In order to avoid foamable material leaving the pipe at the position of recess 49, it is important that the recess does not form an opening in the pipe wall.

[0081] In Figures 6a and 6b is shown a flow separator 30 which may be attached to the tube 31 shown in Figures 5a and 5b.

[0082] In order to attach the flow separator to the tube, the flow separator 33 comprises a first clamp 51 and a second clamp 53. Each clamp 51, 53 comprises a flat spring terminating in a thickening 55 sized to fit into the recess 49 of the tube 31.

[0083] Due to this design, the flow separator 33 can be easily replaced depending on the shape of the mold and the foamed part to be produced.

[0084] The distribution of the foamable material in the mold is as follows Figure 7 As shown. Due to the flow separator, the foamable material is not injected parallel to the axis of the tube, but is divided into two partial flows. Each flow forms a pool 57 in the mold 27, which grows during the injection of the foamable material.

[0085] After the foamable material is injected into the mold, the components in the foamable material begin to react, forming a polymer. Due to the blowing agent, the entire mold is filled with foam. Experiments using the apparatus of the present invention for injecting a foamable material into a rectangular parallelepiped mold have shown that the use of the flow separator 33 can achieve a more uniform cell distribution and foam density distribution than when using a tube without a flow separator.

[0086] When the foamable material is injected without a device for injecting the foamable material, the foam density in the center of the foamed part is significantly higher than the density at the edge. However, if a device for injecting the foamable material is used, a uniform density distribution can be achieved.

[0087] Reference Signs List

[0088] 1 first container

[0089] 3 Second container

[0090] 5 mixing heads

[0091] 7First connecting pipeline

[0092] 9 Second connecting pipeline

[0093] 11 First quantitative feeding unit

[0094] 13 Second quantitative feeding unit

[0095] 15 Foaming agent

[0096] 21 nozzles

[0097] 27 mold

[0098] 29. Device for injecting foamable material

[0099] 31 tubes

[0100] 33 stream separator

[0101] 35 first end portion of tube 31

[0102] 37 Second end portion of tube 31

[0103] 39 bottom of flow separator 33

[0104] 41 longitudinal axis of tube 31

[0105] 43 straight edge of flow separator 33

[0106] 45 incision

[0107] 47 Highest Points

[0108] 48 Surface of flow separator 33

[0109] 49 concavity

[0110] 51 First Fixture

[0111] 53 Second clamp

[0112] 55 thickened part

[0113] 57 liquid pool

Claims

1. A device for injecting a foamable material into a mold (27) for forming a flat foamed part, the device comprising: a tube (31) having a first end (35) by which the tube can be connected to a nozzle (21) of an injection device; and a flow separator (33) for dividing the foamable material into at least two partial flows, the flow separator (33) being placed at a second end (37) of the tube (31) opposite to the first end (35) so that the at least two flows enter the mold (27) separately.

2. The device according to claim 1, wherein the flow separator (33) has an elliptical bottom (39) and a straight edge (43) opposite the bottom (39).

3. The device according to claim 1 or 2, wherein the flow separator (33) has a cross section in the shape of an isosceles triangle.

4. The device according to any one of claims 1 to 3, wherein the flow separator (33) has a shape of an elliptical cylinder that is obliquely truncated to the bottom on both sides of the long axis.

5. The device according to any one of claims 1 to 4, wherein the tube (31) comprises two opposite cutouts (45) at the end where the flow separator (33) is located.

6. The device according to claim 5, wherein the cutout (45) is symmetrical with respect to the straight edge (43) of the flow separator (33).

7. The device according to any one of claims 1 to 6, wherein the flow separator (33) is releasably connected to the tube (31).

8. The device according to claim 7, wherein the flow separator (33) is connected to the tube by a clamp, a latch, a bayonet coupling or a spring lock.

9. The device according to any one of claims 1 to 8, wherein the injection device is a mixing head (5) for injecting a multi-component system into the mold (27).

10. A method for producing a flat foamed part, the method comprising: (a) providing a foamable material in an injection device; (b) injecting the foamable material into the mold (27) through the nozzle (21); wherein the device for injecting the foamable material according to any one of claims 1 to 9 is connected to the nozzle (21) of the injection device such that the foamable material is divided into at least two partial flows entering the mold.

11. The method of claim 10, wherein the foamable material is a multi-component system.

12. The method according to claim 11, wherein the multicomponent system comprises at least one polyisocyanate, at least one isocyanate-reactive compound and at least one chemical and / or physical blowing agent.

13. The method according to any one of claims 10 to 12, wherein the flat foamed part is a rectangular foamed sheet. 14 . The method according to claim 10 , wherein the flat foamed part is a composite element comprising a first sheet and a second sheet and a foamed layer located between the first sheet and the second sheet.

Images