JP2011512268A - Container for the discontinuous production of foam materials - Google Patents

Abstract

The present invention relates to a container for discontinuously producing a foam material. Furthermore, the invention relates to a method for discontinuously producing a foam material using a container according to the invention. The container comprises a horizontally arranged bottom 1 containing a foamable and foam-forming reaction mixture and at least one side wall 4 arranged vertically. The surface of the side wall 4 in contact with the foamed foam is movable in the vertical direction. The side wall 4 comprises a flexible planar element (6) disposed between the roller 7 and the roller 7 '. The container is particularly suitable for producing polyurethane foam slab materials in a box foaming process.

Description

  The present invention relates to a container for discontinuously producing a foam material. The invention also relates to a method for discontinuously producing a foam material using a container according to the invention.

  Slab-like polyurethane foam can be obtained by two different production methods. The two methods are distinguished into continuous methods and discontinuous methods. In the continuous process, the starting materials are mixed in a mixing head and applied to a moving conveyor belt. Thereafter, the foam is formed, cured, and cut into slabs.

The discontinuous method is also called a “box foaming” method. In this case, the reaction mixture resulting in polyurethane foam is introduced at the bottom of a given container. The foam foams into a container shape. After the foam is cured, the slab-like foam can be taken out by opening the side wall of the container from the joint. The advantage of the discontinuous process is that it is possible to produce large volume slab-like foams, especially at low costs for equipment. Slabs produced by the discontinuous method can exhibit a volume greater than 2 m ³ and a weight heavier than 100 kg. A review of common containers used in this process is given in "Soft Polyurethane Foam", Ron Herrington, Kathy Hock, Dow Chemical Company, 1991, chapters 5.11-5.17. Are listed.

  When producing a slab-like foam, it is desirable to make the density of the entire slab-like foam uniform. This is due to the fact that the properties that are important in further processing and the properties that are important when using foam products are a function of density, ie the size and distribution of the bubbles in the foam.

  With conventional box foaming methods it is difficult to produce a uniform density, or at least a density distribution with sufficiently low fluctuations. In the foamable reaction mixture, the temperature, heat insulation, viscosity and pressure differ depending on the time point of measurement of the volume element. Only a few seconds over time can make a significant difference. Furthermore, foamable foams will foam in all directions, such as in the horizontal and vertical directions. When the foamable foam comes into contact with the wall of the container, the bubbles are compressed on the wall by the surrounding pressure and the foam material generated in situ. The result is a slab foam that has the lowest density (ie, maximum gas volume) at the horizontal and vertical centers.

  EP 1018417 A1 proposes improving the side wall of the foam box. The publication discloses a casing for producing a flexible polyurethane foam product, characterized in that the inner wall of the casing contains a polyalkene (most preferably polypropene). This means that the inner wall is a polyalkene layer attached to the inside of the casing, or the entire casing is made of polyalkene. The casing may be a trough, a mixing head, a box or a mold. In the method of continuously producing slabs, an embodiment in which the casing is a trough or a mixing head is very useful. In the box foaming method and the room temperature curing molding method, a box and a mold can be used as the casing, respectively. However, the polyalkene coating method is used to prevent the resulting foam from adhering to the casing walls. This method is not related to the density distribution of the resulting slab foam because it aims to save time by omitting the cleaning operation.

  Insights into how the density of the foam of the slab material near the edges can be adjusted to approximate the density at the center of the slab material cannot be derived from the continuous method. For example, EP-A-1393877 A2 discloses a foam manufacturing method and manufacturing apparatus in a continuous block foaming process. The method determines a correction variable for the block foaming process as a function of measuring the actual height of the resin along the direction of foam transport and the deviation of the actual height from the corresponding reference height. Process. The apparatus contains a conveyor belt that moves in the conveying direction. A mixing head for applying a reactive chemical system to the conveyor belt surface is disposed on the top surface of the conveyor belt starting position. This reactive mixture foams on the conveyor belt, producing a foamed zone with foamed foam. The surface of the foam is coated with coated paper through a roller. From the point of view of foam that is applied and foamed, the foam boundaries are fixed, so in principle the method applies the same conditions as the interior of the foam box. In addition, continuous processes are typically used to produce foam products with a relatively small cross-sectional area.

  U.S. Pat. No. 2,649,620 discloses an apparatus for producing a slab-like foam, which comprises a foaming mold having rigid vertical side walls. In the first stage of the foaming process, the side walls are in a low position. While foaming (i.e., while the plastic expands), the side walls rise upward. In particular, the disadvantage of this device is that it requires a lifting device for raising the side wall, as can be seen from the drawings in the patent publication. For this reason, the use place of this apparatus is limited to the place where a raising / lowering apparatus (for example, crane) can be used.

European Patent Application Publication No. 1018417 A1 specification European Patent Application No. 1393877 A2 specification US Pat. No. 2,649,620

"Soft Polyurethane Foam", Ron Herrington, by Kathy Hock, Dow Chemical Company, 1991, Chapters 5.11-5.17

  There is clearly a need for a method that makes it easier to produce large slab foams with more uniform distribution of properties that are important for post-processing. The present invention aims to overcome at least one of the above-mentioned drawbacks of the prior art. In particular, the present invention aims to provide a container for discontinuously producing a foam material, which can reduce the density difference from the center part to the side part of the slab-like foam produced in the container. And

According to the invention, this object has been achieved by the following containers:
A container for the discontinuous production of a foam material comprising a bottom disposed horizontally to accommodate a foamable foam-forming reaction mixture and at least one side wall disposed vertically. The container characterized in that the surface of the side wall in contact with the foamed foam is vertically movable and the side wall comprises a flexible planar element disposed between the rollers.

  Preferably, the container comprises four side walls arranged vertically adjacent to the bottom, and the surface of at least one side wall in contact with the foamed foam is vertically movable, and at least one The two side walls have flexible planar elements disposed between the rollers. Particularly preferably, such four side walls have a vertically movable surface and have a flexible planar element disposed between the rollers.

FIG. 1 shows a container according to the invention.

  The container according to the invention may be used as a foam box. The reaction mixture that forms the foam is introduced into the bottom or into a bat such as a cardboard bat disposed at the bottom. After this, foam formation is started and the mixture is foamed.

  According to the invention, the surface of the side wall in contact with the foam is movable in the vertical direction. This means that the surface of the sidewall or the entire sidewall may follow the movement of the foam foaming upward. As a result, the relative speed of the rising foam with respect to the side wall of the container is reduced. Advantageously, the rising foam and the side wall or the surface of the side wall moving upwards exhibit the same speed.

  According to the invention, the side wall comprises a flexible planar element disposed between the rollers. The rollers serve as the upper and lower edges of the side walls. Furthermore, the roller also functions to stabilize. Here, the roller is disposed horizontally. The planar elements are arranged in a circulating manner around the outermost roller. The planar element may exist as an endless sheet or may exist in a state of being wound between two reels. In the context of the present invention, the term “flexible” means that a planar element may change its shape when it is curved, for example, around the circumference of a reel or roller. The planar element may be, for example, a woven planar element, a polymer layer, a rubber layer, a polymer-reinforced woven fabric, a layered fabric or a layered fleece. Suitable polymers that prevent adhesion of foam residues are, among others, polyethylene or polytetrafluoroethylene (Teflon®). Furthermore, the surface of the planar element in contact with the reaction mixture may comprise a paper coated with polysiloxane. The surface prevents adhesion of foam residues, particularly polyurethane foam residues.

  The advantage of such a configuration of the flexible planar element is that due to its flexibility, the overall height of the container can be reduced and no external installation of the side wall lifting device is required. One or more rollers may be designed to be rotatable to facilitate movement of the planar element.

  Without being bound by a particular theory, due to the further transportability of the foam material, the gas phase compression of the shorter reaction time volume element located in the center of the foamable reaction mixture is reduced. It is estimated to be. When the foam reaches the side wall of the container and cannot foam further in the lateral direction, when it only foams upward, the side wall is pushed upward, and the foam has reduced frictional force or little effect You just have to overcome the frictional force. In other situations, the frictional force appears as a flow velocity distribution that occurs while the foam contacts the sidewall surface and / or decreases outward in the horizontal direction.

  As a result, the size and distribution of bubbles or pores in the resulting foam can be made more uniform.

  In the container according to the invention, the surface of the side wall in contact with at least one side wall or foam of the vertically arranged side walls is mobile in the vertical direction. However, two, three or four sidewalls may exhibit this mobility. According to the present invention, the one or more side walls may be arranged in a planar form or in a curved form. By using this type of side wall, a container is obtained whose horizontal cross section has linear or curved elements. Examples of this type of container include a cubic container having a rectangular cross section and a cylindrical container having a circular cross section.

  The container according to the invention is particularly suitable for the production of polyurethane foam. This suitability is attributed to the characteristics of the polyurethane foam or of the foam-forming reaction mixture that exhibits temporal and spatial changes in temperature, viscosity and degree of cure.

  The planar element may be stiffened to enhance the sealing of the vertical end. For example, the elastic modulus measured according to ISO178 for the planar element other than the stiffened end portion according to ISO178 is 1 to 2 times, 1.5 to 3 times You may stiffen below or 1.8 times-4 times or less.

  In one embodiment according to the present invention, the sidewall further contains a thermal insulation. The insulation can reduce cooling of the reaction mixture toward the side. A heat insulating material shows the thermal conductivity ((lambda)) of 0.004 W / m * K or more and 1.0-W / m * K or less, for example. The polyurethane foam that can be used exhibits a thermal conductivity (λ) of 0.02 W / m · K to 0.03 W / m · K. Thermal conductivity may be measured according to the ENISO 8497 standard.

  In another embodiment according to the invention, the flexible planar element is driven vertically by a motor. This aspect is understood as an alternative to passive drive methods with ascending foam. By driving the motor, the planar element can be moved at a speed faster than the rising speed of the foam. By driving the motor, a desired speed distribution from outside to inside can be achieved inside the ascending foam.

  The motor speed may be set as part of the control loop. The height of the ascending foam may be determined by measuring distance with optical methods, laser or ultrasound. The rising speed calculated from the result may be input with respect to the rotational speed of the motor. This aspect has the advantage that the unexpectedly high or low rise rate of the foam that occurs in the manufacturing environment due to weather or the like is at least partially compensated.

  In another embodiment according to the present invention, the side wall further comprises a protrusion on its surface that contacts the foamable foam. The protrusion may be provided over the entire width direction of the side wall, or may be provided only in a selected region. Since the protrusion is pushed upward by the surface of the foamable foam, it is effective to provide the protrusion. The protrusion supports the vertical movement of the entire side wall. It is also possible to provide two or more protrusions.

  In a preferred modification, the dimensions of the protrusions are adjusted so as to contact the lid placed on the foamable foam. In this case, first, the foamable foam pushes the lid upward, and then the lid pushes the protrusion and the side wall connected to the protrusion. By combining the lid, the protrusions can be pushed up more reliably as compared with the method of directly contacting the foamed foam. Furthermore, contamination of the protrusions can be prevented.

  In another embodiment according to the present invention, the side wall is adapted to formally connect with the lid. Such a lid limits foam foaming in the vertical direction. For example, the lid may fit inside a suitable device disposed on or on the side wall. Preferably, the form fit connection is reversible, i.e. removable and remountable. Due to the form-fitting connection, the movement of the side walls in the vertical direction is totally supported.

  In another embodiment according to the present invention, a guide surface is disposed on the side of the side wall opposite the foamable foam. This means that a support against the pressure of the foamable foam is disposed on the back side of the side wall that does not contact the foam. The guide surface can prevent foam leakage at the side wall. The side wall may slide on the guide surface. Therefore, even when the side wall moves upward or downward, the side wall can be supported. The guide surface may be, for example, a plate, a perforated plate, or a wire mesh. Furthermore, the guide surface may be designed so that the side walls can be heated and / or cooled. Since the size of the bubbles in the foam also depends on the temperature, the foam density at the end of the slab-like foam block may be adjusted appropriately. The optimum element may be, for example, an electrothermal filament or a Peltier cooling element.

In another embodiment according to the present invention, the side wall in the region in contact with the foamed foam is 0.15 m ³ CO ₂ / (m ² · h · bar) or more and 0.8 m ³ CO ₂ / ( m ² · h · bar) The gas permeability is shown below. The gas permeability may be in the range of not less than 0.57 m ³ CO ₂ / (m ² · h · bar) and not more than 0.6 m ³ CO ₂ / (m ² · h · bar). Gas permeability may be measured according to ISO 2256. The value prescribed | regulated here is related with the gas permeability of the side wall part which contacts foaming foam. Gas permeability may also be characterized by the material used for the sidewall. For example, when the film thickness is 100 μm, the material has a gas permeability measured according to ISO 2556 of 0.15 m ³ CO ₂ / (m ² · h · bar) or more and 0.8 m ³ CO ₂ / (m ² · h Bar) Indicates the following value. The gas permeability may be in the range of not less than 0.57 m ³ CO ₂ / (m ² · h · bar) and not more than 0.6 m ³ CO ₂ / (m ² · h · bar). The gas permeable side walls prevent unwanted pressure build up in the foam which is unfavorable to the properties of the final product. For example, in the production of polyurethane foam, carbon dioxide that needs to be removed is released. If carbon dioxide can be exhausted through the side walls, a more controlled pressure release is achieved.

  In another embodiment according to the invention, the sidewall comprises a heating element and / or a cooling element. Since the size of the bubbles in the foam also depends on the temperature, the foam density at the end of the slab-like foam block may be adjusted appropriately. The optimum element may be, for example, an electrothermal filament or a Peltier cooling element.

  Another subject matter according to the invention is a method for discontinuously producing a foam material, which comprises introducing a reaction mixture forming a foam foam into a container according to the invention. Preferably, the reaction mixture forming the foamed foam contains a mixture of polyol and isocyanate.

  In one embodiment of the method according to the invention, after the reaction mixture forming the foam is introduced into the vessel, the reaction mixture is covered with a lid. Such a lid limits foaming in the vertical direction of the foam. Preferably, the lid contacts a suitable element disposed on the movable side wall. In this case, the foamable foam first pushes the lid upward, and then the lid pushes up the element and the side wall connected to the element.

  The present invention will be further described with reference to the drawings. FIG. 1 shows a container according to the invention.

  FIG. 1 shows a container for discontinuously producing foam material according to the invention. The container has a bottom 1 arranged horizontally. A lid 2 is disposed on the bottom 1. The lid 2 is fitted on the bottom 1 having side walls to form a cavity. A foamable foam-forming reaction mixture such as a mixture of a polyol-based compound and an isocyanate-based compound immediately after the preparation is applied to the bottom 1 through the hole 3 disposed in the lid 2.

  The container further comprises a side wall 4 arranged in a vertical direction forming the short side of the container. The long side of the container is formed by another wall (only one wall 5 is shown for ease of understanding). In short, a container having an open top is formed.

  Each side wall 4 comprises a circulatory flexible planar element 6 which is mounted surrounding the two rollers 7, 7 '. The rollers 7, 7 ′ are arranged so as to be rotatable around their respective horizontal axes. The flexible planar element 6 can move up and down in the circumferential direction, i.e. in the vertical direction, around the rollers 7, 7 'by rotation of the rollers 7, 7'. The lid 2 and the side wall 4 are substantially embedded in each other. This means that there is a gap of at most several millimeters, for example 1, 2, 3, 4 or 5 millimeters, between the end of the lid 2 and the side wall 4. Such a gap is effective for venting the gas generated during foam formation from the reaction mixture.

  On the outside of the flexible planar element 6, there are disposed protrusions 8, 8 'that are pushed upward while the foam is foamed by contacting the lid 2. The protruding portion 8 contacts the lid body 2. The protrusion 8 ′ is offset by a half rotation of the planar element 6. The protrusions can clean the side of the planar element 6 that was in contact with the foam during the production process, while the other side can be used in the next production process. This increases the production rate.

  Alternatively, the lid 2 may be fitted with the protrusions 8 and 8 ′ to form a reversible form fitting connection portion. In this case, the lid 2 may be designed to have no side wall.

  A guide surface 9 is arranged on the inner side of the flexible planar element 6, that is, on the side surface away from the foam. The guide surface serves as a support for the pressure of the foam foam. The guide surface 9 is designed to span the entire width of the planar element 6. In contrast to the projections 8, 8 ′, the guide surface 9 is not connected to the planar element 6. In order for the planar element to be supported, it is necessary for the planar element to be able to slide on top of the guide surface 9. Further, the guide surface may function as a heat insulating material. For this purpose, the guide surface may be made of polyurethane foam.

When a foamable foam-forming mixture, for example a reaction mixture that produces polyurethane foam, is applied to the bottom 1 through the holes 3 provided in the lid 2, the mixture is first applied by the lid 2 in the foaming process. Occupies the provided void. When this gap becomes insufficient, the lid 2 is pushed upward. The foamable foam comes into contact with the surface of the side wall 4, and the lid 2 comes into contact with the protrusion 8. While the foam is further foamed, the flexible planar element 6 is pushed upward by the action on the protrusion 8 of the lid 2. The planar element 6 is fed out via the bottom roller 7 '. At the same time, the planar element 6 rolls over the upper roller 7. As a result, the surface of the side wall 4 follows the foaming in the vertical direction of the foam in the form of the surface of the flexible planar element 6. In order to release the reaction gas such as CO ₂ gradually, it is effective that the flexible planar element 6 is breathable.

DESCRIPTION OF SYMBOLS 1 Bottom part 2 Cover body 3 Hole provided in the cover body 4 Side wall 5 Another wall 6 Flexible plane element 7, 7 'Roller 8, 8' Protrusion part 9 Guide surface

Claims (11)

Discontinuously disperse the foam material with a bottom (1) disposed horizontally to accommodate the foamable foam-forming reaction mixture and at least one side wall (4) disposed vertically. A container for manufacturing,
The surface of the side wall (4) in contact with the foamed foam is vertically movable;
The container, characterized in that the side wall (4) comprises a flexible planar element (6) arranged between rollers (7, 7 ').   The container according to claim 1, wherein the side wall (4) further comprises a heat insulating material.   2. Container according to claim 1, wherein the flexible planar element (6) is driven vertically by a motor.   The container according to claim 1, wherein the side wall (4) further comprises a protrusion (8) on the surface in contact with the foam.   A container according to claim 1, wherein the side wall (4) is adapted to mateably connect with the lid (2).   The container according to claim 1, wherein a guide surface (9) is arranged on the side surface of the side wall (4) opposite to the foamed foam. In the region where the side wall (4) is in contact with the foamed foam, 0.15 m ³ CO ₂ / (m ² · h · bar) or more with respect to carbon dioxide and 0.8 m ³ CO ₂ / (m ² · h · bar) The container according to claim 1, which exhibits the following gas permeability.   2. Container according to claim 1, wherein the side wall (4) comprises a heating element and / or a cooling element.   A method for discontinuously producing a foam material, wherein the foamable foam-forming reaction mixture is charged into the container of claim 1.   The process of claim 9 wherein the foamable foam-forming reaction mixture contains a mixture of polyol and isocyanate.   The method according to claim 9, wherein the foam-forming reaction mixture is put into a container and then the reaction mixture is covered with a lid.

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