DK176726B1 - Process for successive and serial foaming of sandwich panels with polyurethane - Google Patents

Description

DK 176726 B1

Process for successive and serial foaming of sandwich panels with polyurethane

FIELD OF THE INVENTION The present invention relates to a method for successive and serial injection (injection) of polyurethane in sandwich panels. The resulting foamed polyurethane can expand up to 180 degrees in the sandwich panels, minimizing the pressure on the inside of the sandwich panels plate elements (cover plates). At the same time, the foamed and cured polyurethane fixes the sandwich panels' cover plates via so-called "foam bridges". The combination of the relatively low pressure effect of the inside of the cover plates and the formation of "foam bridges" thereby eliminates or reduces the need for the use of strong holding molds or similar devices which have traditionally been used to fix the cover plates of sandwich panels during the polyurethane injection itself.

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Prior art

Polyurethane foamed sandwich panels of the prior art are usually manufactured in strong holding molds that can withstand pressures of up to approx. 40 tons / m2, with injection of polyurethane in a single portion. Such holders or similar devices for fixing the cover plates during the polyurethane injection itself are large, heavy and expensive. In addition, since polyurethane is injected in a single portion over typically 20 to 30 seconds, foaming sandwich panels of the prior art require stationary and high performance high capacity polyurethane mixers, polyurethane high pressure machines or fully automatic systems with built-in polyurethane machine or the like.

Today, sandwich elements are made predominantly in large fully automatic machines, where the cover plates consist of metal sheets in two coils, whereby the polyurethane foam is dosed by a reciprocating mixing head in between the two rolled-out plates. After typically 10-20 min. the polyurethane foam is cured finished and the sandwich panels can be cut to suitable lengths, if necessary. with associated automatic saws etc. like. Such types of plants are large, stationary and expensive.

US 5,245,809 discloses, inter alia, a method of manufacturing panels (sandwich-35 building elements) that can be used for both walls, floors and ceilings. This method comprises, among other things, bonding of plate elements to end profiles, the end profiles comprising at least one opening through which polyurethane can be blown into the cavity formed between the plate elements. US 5,245,809 also discloses embodiments in which the use of powerful adjustable inserts to fix the plate elements prior to the polyurethane injection itself is mandatory. A method of the present invention for successive and serial foaming of sandwich panels by portioned polyurethane injection is disclosed or proposed nowhere in US 5,245,809.

The present invention provides a new method for foaming sandwich panels, thereby eliminating or reducing the need for strong holding molds or similar devices for fixing sandwich panel cover plates. Furthermore, the method of the present invention enables simple and inexpensive production of foamed sandwich panels locally on the building site concerned. like. (on-15 site), thereby eliminating or reducing the need for expensive, prefabricated sandwich panels.

Description of the Invention 20

The present invention relates to a method for successive and serial injection of polyurethane into sandwich panels.

Sandwich panels, as shown in Figures 1 and 2, comprise substantially parallel cover plates which may optionally be anchored in a frame (end profile) thereby providing cavities into which the polyurethane is injected. Sandwich panels of the present invention are treated with polyurethane according to a new and inventive concept whereby the resulting foamed polyurethane can expand up to 180 degrees in the sandwich panel cavity. This means that the resistance with which the foaming 30 can expand between the cover plates is substantially reduced compared to conventional sandwich panel foaming methods, wherein the polyurethane is typically injected in a single portion and therefore requires strong holding molds or similar devices to fix the sandwich panels cover plates. At the same time, the foamed and cured polyurethane forms so-called "foam bridges" between the sandwich panels cover plates whose stiffening effect fixes the cover plates whereby the subsequent polyurethane injection series can be made without holding molds.

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The combination of the relatively low pressure effect that the inside of the cover plates and the formation of "foam bridges" eliminate or reduce the need for the use of retaining molds or other devices for fixing the sandwich panel cover plates during the polyurethane injection itself.

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The injection of the polyurethane portions into the cavity formed between the cover plates takes place through at least one injection hole located in the frame (end profile), preferably through several injection holes.

The sandwich panels foamed by the present invention possess high stiffness and high insulation capacity and can be used for a wide variety of building elements, including flooring, wall and partition panels, roofing elements, insulation panels, etc. and can include the vast majority of cover plates. Such cover plates may include include plywood, etherite, plastic sheets, boards, steel sheets, etc.

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definitions

Relatively low pressure effect according to the present invention is to be understood as the pressure effect of the inside of the cover plates in relation to the thickness and / or strength of the cover plates used. Thus, a pressure which does not substantially affect the inside of the cover plates must be defined as a pressure which does not result in substantial allocation of the cover plates when set up as illustrated in Figure 2 or similarly.

In the present invention, successive injections of polyurethane are to be understood as successive injections of polyurethane within the same injection series as illustrated in Figure 1, i.e. that injection of injection portion "ges is followed by injection of injection portion" A2 "and so on.

In the present invention, serially injected portions of polyurethane are to be understood as series of portions injected as illustrated in Figure 1, i.e. injection of injection series "ΑΓ to" A4 "is followed by injection of injection series" B1 "to" B4 "and so on.

DK 176726 B1 4

Advantages of the present invention

Depending on the nature of the cover plate materials, injection of fast curing polyurethane into sandwich panels of the present invention can be made without the use of holding molds or similar devices for fixing the cover plates. In alternative embodiments with relatively thin cover plates, flimsy holding molds, optionally manufactured on-site, and simple fastening equipment may be used.

Polyurethane foamed sandwich panels of the present invention can be manufactured on-site. This eliminates the costs associated with packing and shipping from the relatively few existing manufacturers of foamed sandwich panels.

The fact that prefabricated foamed sandwich panels fill up to 20-30 times more than the underlying raw materials further increases the said packing 15 and shipping costs.

The successive and serial injection of polyurethane according to the present invention can be made with relatively small mobile polyurethane machines.

20 The successively and serially injected polyurethane portions expand and harden in a matter of minutes, enabling relatively high productivity even from relatively small capacity polyurethane machines.

Multiple sandwich panels can be worked at one time, allowing the polyurethane machine to run with great intermittency.

Figure 1 of the drawings Figure 1 illustrates the principle of successive and serial foaming of polyurethane according to the present invention.

Figure 2 illustrates a method for on-site preparation of foamed polyurethane sandwich panels according to the present invention.

35 5 DK 176726 B1

Brief description plots

Figure 1 illustrates a frontal plane of a sandwich panel (1) with substantially parallel cover plates, cf. (2), (2 ') of Figure 2, where the frontally positioned cover plate (2) is transparent for 5 illustrative reasons. 2, 2 ') is anchored in a frame (3) which can be both fixed or loose and containing at least one terminal injection hole (4). The figure illustrates the principle of successive and serial foaming of polyurethane in the cavity (5) formed between the cover plates, where "AV," A2 "," A3 "and" A4 "refer to the individual injection portions of the first injection series while" B1 "," B2 ", 10" B3 "and" B4 "refer to the individual injection portions of the second injection series and so forth. As further shown in Figure 1, the individual polyurethane portions can expand up to 180 degrees, forming" foam bridges ".

Figure 2 illustrates a 4-step (2a-2d) method for on-site fabrication of foamed polyurethane sandwich panels. Sub-figure 2a illustrates simple on-site assembly of bucks (6) which ensures substantially flat placement of the sandwich panels. Subfigure 2b illustrates assembly of an inner cover plate (2 ') disposed on the buck with a frame (3) and outer cover plate (2). Sub-Figures 2c and 2d illustrate respectively. fixing ring with beams (7) and screws (8) of the sandwich panel and subsequent on-site injection of polyurethane from mobile polyurethane machine (9) (Panel Production Unit (PPU)).

Detailed Description of the Invention

Polyurethane is successively and serially injected into the sandwich panels cavity (5) into portions and at intervals between individual series allowing portions to foam up to 180 degrees (expand) and subsequently cure. Preferably, the injected polyurethane portion from a new injection series is not applied to a polyurethane portion from the previous injection series before the foaming of the polyurethane portion from the previous injection series is completed, i.e. the portion in question must be fully expanded and cured. As polyurethane expands and cures in a matter of minutes, the skilled person will, by simple manual assessment, for example, by measuring with a stick or other device adapted to it, based on the size of the sandwich panel (1), the stiffness of the cover plates (2, 2 ') and the strength thereof. Optionally used on-site manufactured holding mold, 6 DK 176726 B1, cf. Figure 2, could dose up to the size of the portions of the individual polyurethane injections. In this context, it is important to dose the individual polyurethane portions so that the portions have up to 180 degrees to foam (expand) in and furthermore not cause significant pressure on the inside of the cover plates (2, 2 ').

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Likewise, the total number of injections in each series, the amount of polyurethane in each portion, and the number of series can be determined from the size of the sandwich panel (1), the stiffness of the cover plates (2, 2 ') and the strength of the optionally used on-site manufactured form and optionally used simple attachment equipment, cf. Figure 2.

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The frames (3) in the sandwich panel (1) can optionally be applied to the release agent so that they can be removed after foaming. Alternatively, the sandwich panel (1) may have a permanently built-in frame (3) that remains in the sandwich panel (1).

15 In the manufacture of sandwich panels with relatively thin cover plates (2, 2 '), small inlay blocks, including, for example, foam blocks, may optionally be used to maintain the desired distance between the plates (2, 2').

The vast majority of cover sheets (2, 2 '), including plywood sheets, cement 20 (etherite), plastics, wood, steel, plastics or similar materials useful in the process of the present invention.

Embodiments 25

Example 1

As illustrated in Figure 1, a successive injection series according to the present invention can be made from a concept where the bottom of the sandwich panel is subjected to a first injection series, where "ΑΓ," A2 "," A3 "and" A4 "refer to the individual injection portions of the invention. After foaming and curing, which in practice correlate relatively well with the time it takes to complete the first injection series, the second set of polyurethane portions (second injection series) is injected, where "ΒΓ," B2 "," B3 "and" B4 "refers to the individual injection portions of the second injection series and then distributed. Furthermore, as shown in Figure 1, the individual polyurethane portions can expand up to 180 degrees, forming "foam bridges".

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With said example of a successive injection series, even relatively small polyurethane machines will run 50% of the time (intermittent 50%) with performance of 10, 20 or 40 kg / min. provide respectively. 5, 10 and 20 kg / min, respectively. 300, 500 or 1000 kg of foamed polyurethane per hour. This corresponds to respectively. 8, 12 or 25 m3 foamed polyurethane per hour, corresponding to between 160 - 500 m2 sandwich panels with 50 mm foamed polyurethane insulation per hour. By methods of foaming sandwich panels according to the prior art, wherein the sandwich panels typically cure in strong holding molds over a period of time of between 10-20 minutes, with holding molds of e.g. 3 m2, 10 produced for comparison approx. 6 to 9 m2 sandwich panels per hour per holding mold, Example 2

As illustrated in Figure 2, the successive and serial injection of polyurethane into sandwich panels can be carried out on-site, whereby the costs associated with prefabricated sandwich elements, including packing and transportation, eliminated.

On-site fabrication of foamed polyurethane sandwich panels can, in principle, be carried out on, for example, on-site manufactured bucks or similar devices which ensure substantially flat placement of the sandwich panel. The sandwich panel can in principle be assembled as illustrated in sub-figures 2 (b-d), ie. optionally by means of simple fixing devices, including wooden beams and screws. The subsequent successive and serial on-site injection of polyurethane from e.g. mobile polyurethane machines can then be carried out immediately, ie. without the need for further fixing of the cover plates.

Claims (12)

A method of foaming voids (5) in sandwich panels (1) comprising cover plates (2, 2 ') and with injection holes or holes (4) equipped with frame (3) for separating the cover plates (2, 2'), characterized in that the foaming of the cavity (5) is carried out successively and serially with portion injections of polyurethane. A method according to claim 1, characterized in that the individual polyurethane portions have a size which allows polyurethane to foam (expand) in 10 up to 180 degrees in the cavity (5) of the sandwich panel (1) without significantly affecting the inside of the cover plates ( 2, 2 '). Method according to claims 1 and 2, characterized in that the individual polyurethane portions are positioned in such a way as to be in the cavity (5) of the sandwich panel (1), that the polyurethane can foam (expand) freely up to 180 degrees without substantially exerting pressure the inside of the cover plates (2, 2 '). Method according to any one of claims 1-3, characterized in that a polyurethane portion of injection series is not applied to a polyurethane portion of the previous injection series before the foaming of the polyurethane portion of the previous injection series is completed. Process according to any one of claims 1-4, characterized in that the sheet material in the cover sheets (2, 2 ') comprises plywood, cement (etherite), plastic, wood, steel, plastics or similar materials. Method according to any one of claims 1-5, characterized in that the frame (3) for separating the cover plates (2, 2 ') is firmly anchored. Method according to any of claims 1-5, characterized in that the frame (3) for separating the cover plates (2,2) is removable. Method according to claim 7, characterized in that the removable frame (3) contains an abrasive. 35 8 DK 176726 B1 A method according to any one of claims 1-8, characterized in that injection of polyurethane is carried out with mobile polyurethane machines (9). Method according to claims 1-9, characterized in that the successively and serially foamed sandwich panels (1) are manufactured on-site. 5 DK 176726 Bl 11 FIGURE 1 r '/ 1 r $ Λ) / A ~ t% £ ry Æ ..... y ......, s ~ S' "Hr · v / *> ^ _9 ^ / <ar au 'c <' Tk. / & 7 £ z 7 £ i "V" ^ * t ^ ^ --- / ^ / / ¾ / rfz / / ^ T ____- / - · '__ _-Lii —_- -. ~ ——, ---__ ί? Ι _, _ '. · _ \ - 12 DK 176726 ΒΪ FIGURE 2