Patent Description:
<CIT> describes a method for producing an insulation panel made of polyisocyanurate.

<CIT> discloses a rigid polymeric insulating foam board comprises an upper facing, a lower facing and a foam layer between the upper and the lower facing. The foam sandwich is delivered into an oven and the continuous length of foam board exiting the oven is delivered through a curing station. The foam board is cut to length, trimmed, optimally re-bated, the cut board lengths are stacked and wrapped. A cooling station for the wrapped stacks comprises upper and lower stack conveyors. Scissors-type lifters are provided at the infeed and outfeed end to divert a stack to or from a cooling conveyor <NUM>.

<CIT> and <CIT> describe examples of polyisocyanurate foam formulations which may be used for producing insulation panels made of polyisocyanurate.

In the production of polyisocyanurate insulation panels, a liquid polyisocyanurate foam formulation is used. The term liquid polyisocyanurate foam formulation is understood to mean a liquid which contains the reactants for forming a rigid polyisocyanurate. The liquid polyisocyanurate foam formulation comprises polyol, a di-isocyanate and one or more blowing agents, catalysts, silicones, flame retardants and water. During the production process, the polyol reacts with the di-isocyanate to form a rigid foam.

It is a specific object to provide a production method for polyisocyanurate insulation panels for producing panels of good constant quality, with a pleasing aesthetic appearance and an improved compressive strength in the thickness direction of the panel.

The invention relates to a method for producing a polyisocyanurate (PIR) insulation panel on a production line, wherein the produced insulation panel comprises a polyisocyanurate foam between two foils. The method is characterized in that the method comprises the step in which a liquid polyisocyanurate foam formulation is deposited on a foil, so that, at the position where the liquid polyisocyanurate foam formulation is deposited on the foil, the foil is moistened in an uninterrupted manner by the liquid polyisocyanurate foam formulation in the direction at right angles to the direction of production; and in that, at the position where the liquid foam formulation is deposited on the foil, the foil is supported by a heated table, wherein, in the method, the liquid polyisocyanurate foam formulation reacts to form a polyisocyanurate foam which is bonded to the foil.

An aesthetically more pleasing polyisocyanurate insulation panel is obtained by depositing the liquid polyisocyanurate foam formulation on a foil, so that the foil, at the position where the liquid foam formulation is deposited on the foil, is moistened in an uninterrupted manner in the direction at right angles to the direction of production; and because the foil is supported by a heated table at the position where the liquid foam formulation is deposited on the foil.

The liquid polyisocyanurate foam immediately continuously moistens the foil in the width direction. Due to the heated table, a reaction may occur immediately between the foam and the foil, as a result of which the foam is quickly continuously fixed on the foil across the entire width in a constant manner.

The use of the heated table which ensures that the foam is quickly fixed to the foil, is possible because the liquid foam no longer has to flow in the width direction, as this liquid foam moistens the foil immediately in an uninterrupted manner in the transverse direction when the liquid foam is deposited on the foil.

The result thereof is that no folds or creases can form in the foil during the production process, because the foam is directly bonded to the foil across the width. As a result thereof, an aesthetically more pleasing surface of the insulation panel is obtained.

In addition, insulation panels with a higher compressive strength in the thickness direction of the insulation panel are obtained. Since the polyisocyanurate foam on the production line can only expand in a vertical direction, the cells in the polyisocyanurate foam are oriented mainly in the thickness direction of the insulation panel. This ensures an improved compressive strength in the thickness direction of the insulation panel.

The foil may continuously be passed through the production line in the direction of production of the polyisocyanurate panel. This ensures a continuous production process for producing polyisocyanurate (PIR) insulation panels.

A preferred embodiment is characterized in that the heated table is arranged in a fixed position. This results in a simple design. The foil - with the liquid foam on top thereof - can be pushed across this heated table which is arranged in a fixed position.

A preferred embodiment of the method is characterized in that, at the position where the liquid polyisocyanurate foam formulation is deposited on the foil, the heated table has a temperature of at least <NUM>, and preferably of less than <NUM>, and more preferably of at least <NUM>.

This choice of temperatures results in a good and uniform bonding of the foil to the foam across the width, while preventing an excessively quick reaction and expansion of the foam. In this case, the heated table ensures that the chemical reactions are locally accelerated, as a result of which the polyisocyanurate foam is fixed to the foil, whereas the upper foam mass is still able to continue to expand and react.

Preferably, the foil with the polyisocyanurate foam on top thereof is passed through an oven downstream of the heated table by means of and between a double belt. In the oven, the reactants in the polyisocyanurate foam can continue to react, so that the rigid foam of the polyisocyanurate insulation panel is formed correctly.

Preferably, the heated table comprises at least three sections in the direction of production; and more preferably at least five sections; and even more preferably at least six sections. The temperature in these sections can be adjusted separately.

This offers the advantage that the temperature of the heated table can be adjusted so as to increase in the direction of production. This ensures that the chemical reactions in the polyisocyanurate foam can be controlled in a suitable manner. As a result thereof, good bonding of the foam to the foil is achieved. Generally, this results in an insulation panel of good quality.

More preferably, the method uses sensors and control circuits to measure and control the temperature in each of these sections with respect to the desired temperature in the respective section.

These embodiments ensure homogeneous and constant properties of the insulation panel.

The temperature of the sections is preferably adjusted so as to increase in the direction of production. More preferably, the temperature is adjusted so as to increase across at least four, and preferably across at least five sections. This ensures better reactions of the polyisocyanurate foam, so that an insulation panel of better quality is obtained.

Preferably, the temperature in the last section of the heated table is less than <NUM> below the temperature in the oven. More preferably, the temperature in the last section of the heated table is adjusted to be identical to the temperature of the oven. This ensures that the chemical reactions in the foam proceed well, so that an insulation panel of better quality is obtained. In addition, the production speed of the production line can be maximized.

Preferably, the temperature in the last section of the heated table is higher than <NUM> and lower than <NUM>, and preferably higher than <NUM>. This ensures that the production speed of the production line can be maximized.

A preferred embodiment of the method is characterized in that the last section of the heated table upstream of the oven in the direction at right angles to the direction of production comprises three subsections, wherein the temperature in each of these subsections can be adjusted separately.

This makes it possible to adjust and/or control the temperature of the heated table in the last section across the width. This makes even better control of the properties and the visual appearance of the polyisocyanurate insulation panel possible.

A preferred embodiment of the method is characterized in that at least the last three sections of the heated table upstream of the oven each comprise three subsections in the direction at right angles to the direction of production, wherein the temperature in each of these subsections can be adjusted separately and controlled separately. This makes it possible to adjust and/or control the temperature of the heated table in these last sections across the width. This makes even better control of the properties and the visual appearance of the insulation panel possible.

More preferably, these three subsections comprise a central section and two edge sections, wherein the central section is at least double the width of each of the two edge sections. This is advantageous since edge effects might occur along the edges during the production of the insulation panel. Control of the temperature in these edge sections of the heated table makes is possible to reduce edge effects or even to prevent them altogether.

A preferred embodiment of the method is characterized in that the method uses sensors and control circuits to measure and control the temperature in each of the three subsections with respect to the desired temperature.

This is advantageous even in embodiments where the desired temperature in subsections is identical. In that case, the separate adjustment ensures that the desired temperature is actually achieved and maintained, so that an insulation panel of better quality is obtained.

A preferred embodiment of the method is characterized in that the temperature in each subsection which is intersected by the same line at right angles to the direction of production is adjusted to be identical. The separate adjustment then ensures that the desired temperature is actually achieved and maintained, so that an insulation panel of better quality is obtained.

A preferred embodiment of the method is characterized in that the liquid polyisocyanurate foam formulation flows at right angles to the direction of production of the polyisocyanurate panel from a discrete number of spray nozzles and is deposited on the foil by these. The various spray nozzles make it possible to position and distribute the liquid polyisocyanurate foam correctly across the width.

The method preferably uses a number of spraying units which are placed across the width of the production line for producing the polyisocyanurate insulation panel, wherein each of the spraying units comprises a central supply duct for supplying the liquid polyisocyanurate foam formulation. The central supply duct ends in a transverse distribution duct which passes the liquid polyisocyanurate foam formulation indirectly or directly to a discrete number of spray nozzles.

Such embodiments make it possible to distribute the liquid polyisocyanurate foam formulation efficiently and evenly across a number of spray nozzles. This ensures improved uniformity of the properties of the polyisocyanurate insulation panel.

In a preferred embodiment, each spraying unit comprises a number of spraying ducts, placed at right angles to the transverse distribution duct, wherein each spraying duct passes a separate stream of the liquid polyisocyanurate foam formulation from the transverse distribution duct to a spray nozzle, wherein the length of the spraying ducts decreases from spraying ducts which end in a centrally positioned spray nozzle or the centrally positioned spray nozzles, to the spraying ducts which end in the most distal spray nozzles with respect to the central supply duct.

Such embodiments have the advantage that an equal amount of liquid polyisocyanurate foam formulation flows from the various spray nozzles of the spraying unit. This ensures good uniformity of the insulation panel.

In a preferred embodiment, each of the spraying units comprises a second transverse distribution duct, wherein the second transverse distribution duct runs parallel to the transverse distribution duct and is connected thereto via a number of connecting ducts. The liquid polyisocyanurate foam formulation can flow from the transverse distribution duct into the second transverse distribution duct via the connecting ducts. The connecting ducts are placed transversely with respect to the transverse distribution duct. A discrete number of spray nozzles are positioned across the length of the second transverse distribution duct, wherein each spray nozzle is connected to the second transverse distribution duct via a spraying duct, placed transversely with respect to the second transverse distribution duct. In each case, two spraying ducts are arranged symmetrically with respect to each connecting duct.

This embodiment has the advantage that an equal amount of liquid polyisocyanurate foam formulation flows from the various spray nozzles of the spraying unit. This ensures good uniformity of the insulation panel. The second transverse distribution duct ensures that an equal amount of liquid polyisocyanurate foam formulation flows from the various spray nozzles.

More preferably, in each case two connecting ducts are arranged symmetrically with respect to the central supply duct. This ensures an even better uniform distribution of the liquid polyisocyanurate foam formulation across the various spray nozzles of the spraying unit.

A preferred embodiment is characterized in that each spraying unit comprises at least ten, and preferably at least twelve spray nozzles. This number ensures a precise distribution of the liquid polyisocyanurate foam formulation.

More preferably, the distance between every two successive spray nozzles in the spraying unit is at least <NUM>, and more preferably less than <NUM>. These embodiments are an example of an efficient and correct distribution of the liquid polyisocyanurate foam formulation, and correct deposition thereof on the foil, so that a high-quality insulation panel which is visually attractive is obtained.

Preferably, each spraying unit comprises one or more plastic injection-moulded parts.

Preferably, each spraying unit is composed of one or more plastic injection-moulded parts.

In a preferred embodiment, the spray nozzles are oriented in such a way that the liquid polyisocyanurate foam formulation flows vertically from the spray nozzles in the direction of the foil. This allows for an efficient deposition of the liquid polyisocyanurate foam formulation on the foil.

Preferably, the spray nozzles are circular. This ensures that the deposition of the liquid polyisocyanurate foam formulation on the foil can take place in a simple and efficient manner.

A preferred embodiment of the invention is characterized in that, upstream of the oven, a second foil is supplied above the foil with the polyisocyanurate foam on top thereof. The foil with the polyisocyanurate foam on top thereof and the second foil are passed through the oven by means of and between a double belt. In the method, the liquid polyisocyanurate foam formulation expands and reacts to form a polyisocyanurate foam bonded to and situated between the foil and the second foil.

More preferably, the vertical position of the running in of the second foil is determined by the fact that the second foil is passed under a roller, wherein the vertical position of this roller is controlled by means of a control circuit depending on a measurement of the height of the polyisocyanurate foam upstream of the position of the roller. This embodiment is particularly advantageous when producing insulation panels with a thickness of at least <NUM>.

This embodiment is advantageous because it ensures a correct positioning and correct bonding of the second foil to the polyisocyanurate foam, so that the insulation panel has a pleasing visual appearance even on the side of the second foil.

Preferably, the height measurement across the width is performed by means of an optical measurement, more preferably a laser is used for this purpose.

A preferred embodiment of the invention is characterized in that a paper strip is introduced next to the foil on both sides of the foil, wherein the paper strip is attached to the foil on both sides by means of adhesive tape, wherein, in the method, the paper strips are folded on both sides to a vertical position, wherein the polyisocyanurate foam bonds to these vertically oriented paper strips, and wherein these paper strips form the lateral edges of the produced polyisocyanurate insulation panel.

This embodiment has the advantage that the sides of the insulation panel are also formed correctly. In addition, the paper strips ensure that no liquid polyisocyanurate foam formulation is deposited or flows onto the heated table. This has to be prevented, because the foam would adhere to this heated table. In addition, the insulation panel would not contain the correct amount of material.

In one embodiment, the foil is or comprises an aluminium sheet. More preferably, the aluminium sheet has a thickness of more than <NUM> micrometres, and more preferably of less than <NUM> micrometres, more preferably of less than <NUM> micrometres.

In one embodiment, the foil is a laminate, wherein the laminate comprises:.

The plastic film may be, for example, a polyethylene film or a polyvinylidene film.

Preferably, the liquid polyisocyanurate foam formulation comprises at least:.

wherein the ratio by mass of the polymeric methylene diphenyl diisocyanate (pMDI) with respect to the polyester polyol is at least <NUM>.

Such embodiments make it possible to produce high-quality polyisocyanurate insulation panels using the method of the invention.

More preferably, the combination of the polyester polyol and the polymeric methylene diphenyl diisocyanate constitutes at least <NUM>% by weight - and more preferably at least <NUM>% by weight - of the liquid polyisocyanurate (PIR) foam formulation. Such embodiments make it possible to produce polyisocyanurate (PIR) insulation panels of good quality in embodiments of the method of the invention.

Preferably, the liquid polyisocyanurate foam formulation has a viscosity, measured at <NUM>, of between <NUM> and <NUM> mPa. Such embodiments are advantageous because they further facilitate the complete moisturisation of the foil with the liquid polyisocyanurate foam formulation in the direction at right angles to the direction of production in an uninterrupted manner.

The method of the invention may be used, for example, to produce polyisocyanurate (PIR) insulation panels with a thickness of at least <NUM>, more preferably with a thickness of at least <NUM>, and even more preferably with a thickness of at least <NUM>.

The method of the invention is preferably used in the production of polyisocyanurate (PIR) insulation panels which have a thickness of at most <NUM>.

The speed of the production line is preferably between <NUM> and <NUM> metres per minute. Such embodiments produce polyisocyanurate insulation panels of even better quality.

In order to show the features of the invention in more detail, some preferred embodiments are described below by way of example and without being limited thereto, with reference to the accompanying drawings, in which:.

The reference numerals in the various figures have the same meaning.

<FIG> illustrates an example of an embodiment of the method according to the invention on a continuous production line <NUM> for producing polyisocyanurate insulation panels. <FIG> shows the view along F2 of a part of the continuous production line from <FIG>.

A liquid polyisocyanurate foam formulation <NUM> is deposited on a foil <NUM>, so that the foil is moistened in an uninterrupted manner by the liquid polyisocyanurate foam formulation in the direction at right angles to the direction of production across the entire width at the position where the liquid foam formulation is deposited on the foil <NUM>.

The example uses a number of spraying units <NUM> which are positioned across the width of the production line <NUM>. Each of the spraying units <NUM> comprises a discrete number of spray nozzles <NUM> from which liquid polyisocyanurate foam formulation flows.

Thus, viewed at right angles to the direction of production of the polyisocyanurate panel, the liquid polyisocyanurate foam formulation flows from a discrete number of spray nozzles <NUM>.

The spray nozzles are oriented in such a way that the liquid polyisocyanurate foam formulation flows vertically from the spray nozzles in the direction of the foil.

At the position where the liquid foam formulation <NUM> is deposited on the foil, the foil is supported by a heated table <NUM>. The heated table <NUM> is arranged in a fixed position.

As is shown in <FIG>, a paper strip <NUM> is introduced next to the foil on both sides of the foil <NUM>. The paper strip <NUM> is attached to the foil <NUM> on both sides by means of adhesive tape <NUM>. The paper strips <NUM> are folded on both sides to a vertical position in the production line, wherein the polyisocyanurate foam bonds to these vertical paper strips. These paper strips <NUM> form the lateral edges of the produced polyisocyanurate insulation panel.

In the method, the liquid polyisocyanurate foam formulation <NUM> expands and reacts to form a polyisocyanurate foam <NUM> bonded to the foil <NUM>.

The foil <NUM> - with the liquid foam formulation on top thereof - is continuously passed through the production line in the direction of production <NUM> of the insulation panel.

At the position where the liquid polyisocyanurate foam formulation <NUM> is deposited on the foil <NUM>, the heated table has a temperature of at least <NUM>. Depending on the polyisocyanurate foam formulation, this temperature may be, for example <NUM> or <NUM>.

In the illustrated example, the heated table <NUM> comprises six sections <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> in the direction of production <NUM>, wherein the temperature in these six sections <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> can be adjusted and controlled separately.

The foil <NUM> with the polyisocyanurate foam <NUM> on top thereof is passed through an oven downstream of the heated table <NUM> by means of and between a double belt <NUM>.

Upstream of the oven - and thus before the double belt <NUM> -a second foil <NUM> is supplied above the foil <NUM> with the polyisocyanurate foam on top thereof. The foil <NUM> with the polyisocyanurate foam on top thereof and the second foil <NUM> are passed through the oven by means of and between the double belt <NUM>. In the oven, the liquid polyisocyanurate foam formulation continues to expand and react to form a polyisocyanurate foam bonded to and situated between the foil <NUM>, the second foil <NUM> and the two paper strips <NUM>.

The vertical position of the running in of the second foil <NUM> is determined by the fact that the second foil <NUM> is passed under a roller <NUM>. The vertical position of this roller <NUM> may be controlled by means of a control circuit depending on a measurement of the height of the polyisocyanurate foam upstream of the position of the roller <NUM>.

The height measurement of the foam across the width may preferably be performed by means of an optical measurement, for example by using a laser.

<FIG> shows an example of the division into sections of the heated table <NUM> of the production line from <FIG>. The heated table <NUM> from <FIG> (and as shown in detail in <FIG>) comprises six sections <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> in the direction of production. The temperature in these six sections <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> can be adjusted separately and set to the desired temperature. To this end, these sections comprise sensors and control circuits.

The last three sections <NUM>, <NUM>, <NUM> upstream of the oven of the heated table <NUM> are each divided into three subsections <NUM>, <NUM>, <NUM> in the direction at right angles to the direction of production. These three subsections each comprise a central section <NUM> and two edge sections <NUM>, <NUM>. The central section <NUM> is at least double the width of each of the two edge sections <NUM>, <NUM>. In each of these nine subsections, the temperature can be adjusted and controlled separately with respect to the desired temperature. To this end, each subsection comprises sensors and a control circuit.

An example of temperature adjustment in the successive sections is: <NUM> in the first section <NUM>; <NUM> in the second section <NUM>; <NUM> in the third section <NUM>; <NUM> in each subsection <NUM>, <NUM>, <NUM> of the fourth section <NUM>; <NUM> in each subsection <NUM>, <NUM>, <NUM> of the fifth section <NUM>; and <NUM> in each subsection <NUM>, <NUM>, <NUM> of the sixth section <NUM>. In the example, the temperature in each subsection which is intersected by the same line at right angles to the direction of production is thus adjusted to be identical. This is not necessarily the case for the invention.

In the example, the temperature of each of the three subsections <NUM>, <NUM>, <NUM> of the last section <NUM> of the heated table <NUM> is adjusted to be identical to the temperature of the oven.

<FIG> shows an example of a spraying unit <NUM> as may be used in the invention. A number of these spraying units <NUM> are positioned across the width of the production line. This is shown in <FIG> by means of a different type of spraying unit, i.e. the type of spraying unit shown in <FIG>. In the same way, the spraying units <NUM> from <FIG> may be used.

The spraying unit <NUM> from <FIG> comprises a central supply duct <NUM> for supplying the liquid polyisocyanurate foam formulation. The central supply duct <NUM> ends in a transverse distribution duct <NUM>.

The spraying units <NUM> from <FIG> comprise a second transverse distribution duct <NUM>. The second transverse distribution duct <NUM> runs parallel to the transverse distribution duct <NUM>; and is connected thereto via six connecting ducts <NUM>. The liquid polyisocyanurate foam formulation can flow from the transverse distribution duct <NUM> into the second transverse distribution duct <NUM> via the connecting ducts <NUM>. The six connecting ducts <NUM> are placed transversely with respect to the transverse distribution duct <NUM>. In each case, two connecting ducts <NUM> are arranged symmetrically with respect to the central supply duct <NUM>.

The twelve spray nozzles <NUM> of the spraying unit <NUM> from <FIG> are positioned across the length of the second transverse distribution duct <NUM>. Each spray nozzle <NUM> is connected to the second transverse distribution duct <NUM> via a spraying duct <NUM>, placed transversely with respect to the second transverse distribution duct <NUM>. In each case, two spraying ducts <NUM> are arranged symmetrically with respect to each connecting duct <NUM>.

The twelve spray nozzles <NUM> from the example of spraying unit <NUM> from <FIG> are circular and have a diameter of <NUM>. The distance D between every two successive spray nozzles <NUM> of the spraying unit <NUM> is <NUM>.

The illustrated spraying unit <NUM> from <FIG> consists of two plastic injection-moulded parts which have been glued together.

Spraying units <NUM> as shown in <FIG> are preferably used for producing polyisocyanurate insulation panels having a thickness of at least <NUM>.

<FIG> shows another example of a spraying unit <NUM> as may be used with the invention. A number of these spraying units <NUM> may be positioned across the width of the production line. This is shown in <FIG>.

The spraying unit <NUM> from <FIG> comprises a central supply duct <NUM> for supplying the liquid polyisocyanurate foam formulation. The central supply duct <NUM> ends in a transverse distribution duct <NUM> which passes the liquid polyisocyanurate foam formulation to twelve spray nozzles <NUM>.

The liquid polyisocyanurate foam formulation may flow from the spray nozzles <NUM> at right angles to the direction of production of the polyisocyanurate panel. This is illustrated in <FIG>.

The spraying unit <NUM> from <FIG> comprises a number of spraying ducts <NUM>, placed at right angles to the transverse distribution duct <NUM>. Each spraying duct <NUM> passes a separate stream of the liquid polyisocyanurate foam formulation from the transverse distribution duct <NUM> to a spray nozzle <NUM>.

The length of the spraying ducts <NUM> decreases from spraying ducts which end in a centrally positioned spray nozzle or the centrally positioned spray nozzles, to the spraying ducts <NUM> which end in the most distal spray nozzles <NUM> with respect to the central supply duct <NUM>.

The twelve spray nozzles <NUM> of the spraying unit from <FIG> are circular.

The spraying unit from <FIG> is composed of plastic injection-moulded parts.

Spraying units <NUM> as shown in <FIG> are preferably used for producing insulation panels having a thickness of <NUM> or less.

<FIG> shows a polyisocyanurate insulation panel as may be produced according to the method of the invention. The insulation panel comprises a rigid polyisocyanurate foam <NUM> between two foils <NUM>, <NUM>. The sides are formed by paper strips <NUM>.

Claim 1:
Method for producing a polyisocyanurate (PIR) insulation panel on a production line, wherein the produced insulation panel comprises a polyisocyanurate foam (<NUM>) between two foils (<NUM>, <NUM>),
wherein the method comprises the step in which a liquid polyisocyanurate foam formulation (<NUM>) is deposited on a foil (<NUM>); and
at the position where the liquid foam formulation is deposited on the foil, the foil is supported by a heated table (<NUM>),
wherein, in the method, the liquid polyisocyanurate foam formulation (<NUM>) reacts to form a polyisocyanurate foam (<NUM>) which is bonded to the foil (<NUM>), characterized in that at the position where the liquid polyisocyanurate foam formulation is deposited on the foil (<NUM>), the foil is moistened in an uninterrupted manner by the liquid polyisocyanurate foam formulation in the direction at right angles to the direction of production.