Home
>
News
>
Company news
More
News
Company news
Detailed description of the bonding process of waste polyurethane pellets
HC Plastics News: The waste polyurethane pellets are bonded with adhesive and then sent to the mold for hot pressing into a block foam or liner. The waste materials suitable for processing by this process include soft and rigid foam. RIM polyurethane.
Usually, 3-15mm of flexible polyurethane foam pieces are added to the drum or about 10% of the MDI-based adhesive in the ploughshare mixer, and then uniformly mixed and sent to a mold coated with a mold release agent. The pressure of 3.0 MPa, the mold temperature is maintained at 160 ° C for 30-60 s, or under the pressure of IMPA and the mold temperature of 100 ° C for 10 min, and molded into a cushion or carpet backing. Or a slurry in which a flexible polyurethane foam pellet and an adhesive are uniformly mixed is prefabricated into a flat gasket at room temperature, and then molded into a foamed article at a higher temperature and pressure to be used as a sound absorbing and vibration damping material. When the size of the flexible polyurethane foam is larger, the ratio of the surface to the volume is smaller, and the amount of the adhesive is less, but the pressure required for the compression molding is large to ensure that the finished product has no voids. Otherwise, when the reconstituted foam block is cut, the foam easily expands slowly, causing the cut surface to be uneven.
Low-cost adhesives based on polyether triol/TDI or polyphenylpolymethylene isocyanate are generally used. Small molded parts are selected from MDI or modified MDI based adhesives, and terminal isocyanate prepolymers can also be used. The adhesive is prepared by mixing isocyanate and polyether polyol at room temperature for a few hours before use. However, in most cases, the reconstituted flexible foam block adopts a one-step method in which the waste foam chips are first wetted with water, and then a mixture of TDI and polyether polyol is applied, and pigments and fillers may also be added. The cold curing system requires the addition of a catalyst. The coated foam chips are placed in a mold for pressing. The degree of compression depends on the required density and load bearing capacity of the final finished part. Generally, the degree of compression is between 10% and 50%, so that the material is always in a compressed state until fully matured to prevent Significant expansion occurs after demolding.
Most methods of producing slabstock foam from waste materials are aging at room temperature or in a room with hot air. The small molded body can be aged in a normal oven or rapidly heated and matured in a microwave oven. The production of sound-insulating and sound-absorbing foam parts often uses a modified MDI-based cold curing system. The recycled foam block can also be produced by a continuous or semi-continuous process, and the foamed pieces coated with the adhesive are dispersed on the polyethylene film which is driven by the conveyor belt, and then covered with a decorative surface material after being leveled. It is compressed, heated and matured, and then horizontally cut into foam blocks having a polyethylene layer. When the carpet backing is prepared, the density of the foam is 40-100 kg/m3.
Usually, 3-15mm of flexible polyurethane foam pieces are added to the drum or about 10% of the MDI-based adhesive in the ploughshare mixer, and then uniformly mixed and sent to a mold coated with a mold release agent. The pressure of 3.0 MPa, the mold temperature is maintained at 160 ° C for 30-60 s, or under the pressure of IMPA and the mold temperature of 100 ° C for 10 min, and molded into a cushion or carpet backing. Or a slurry in which a flexible polyurethane foam pellet and an adhesive are uniformly mixed is prefabricated into a flat gasket at room temperature, and then molded into a foamed article at a higher temperature and pressure to be used as a sound absorbing and vibration damping material. When the size of the flexible polyurethane foam is larger, the ratio of the surface to the volume is smaller, and the amount of the adhesive is less, but the pressure required for the compression molding is large to ensure that the finished product has no voids. Otherwise, when the reconstituted foam block is cut, the foam easily expands slowly, causing the cut surface to be uneven.
Low-cost adhesives based on polyether triol/TDI or polyphenylpolymethylene isocyanate are generally used. Small molded parts are selected from MDI or modified MDI based adhesives, and terminal isocyanate prepolymers can also be used. The adhesive is prepared by mixing isocyanate and polyether polyol at room temperature for a few hours before use. However, in most cases, the reconstituted flexible foam block adopts a one-step method in which the waste foam chips are first wetted with water, and then a mixture of TDI and polyether polyol is applied, and pigments and fillers may also be added. The cold curing system requires the addition of a catalyst. The coated foam chips are placed in a mold for pressing. The degree of compression depends on the required density and load bearing capacity of the final finished part. Generally, the degree of compression is between 10% and 50%, so that the material is always in a compressed state until fully matured to prevent Significant expansion occurs after demolding.
Most methods of producing slabstock foam from waste materials are aging at room temperature or in a room with hot air. The small molded body can be aged in a normal oven or rapidly heated and matured in a microwave oven. The production of sound-insulating and sound-absorbing foam parts often uses a modified MDI-based cold curing system. The recycled foam block can also be produced by a continuous or semi-continuous process, and the foamed pieces coated with the adhesive are dispersed on the polyethylene film which is driven by the conveyor belt, and then covered with a decorative surface material after being leveled. It is compressed, heated and matured, and then horizontally cut into foam blocks having a polyethylene layer. When the carpet backing is prepared, the density of the foam is 40-100 kg/m3.