WO2013032350A2

WO2013032350A2 - Heat insulating composite materials and a method of their production

Info

Publication number: WO2013032350A2
Application number: PCT/PL2012/050030
Authority: WO
Inventors: Wiesław Ludwik GALUS; Henryk Jaremek; Piotr Paweł KONIORCZYK; Marcin Grzegorz TRZYNA
Original assignee: Hit Konsulting Sp Z O.O.
Priority date: 2011-08-31
Filing date: 2012-08-30
Publication date: 2013-03-07
Also published as: WO2013032350A3; PL396151A1

Abstract

The subject of this invention is the method of production of heat insulating composite materials based on polyurethanes and/or polyisocyanurates, joined together to create a whole without the use of adhesive agents (glues) with classic layers of foamed polystyrene, characterised in that onto the layer of foamed polystyrene a polyurethane mixture containing a polyol and isocyanate component is directly poured out, with the formation of a permanent weld exhibiting thermal continuity. Then, onto the polyurethane mixture poured out onto the first layer of foamed polystyrene a second layer of foamed polystyrene is placed with the formation of a permanent weld exhibiting thermal continuity. In the case of materials, in which the thickness of foamed polystyrene layer is no less than 20 mm, to the polyurethane mixture, and especially to the isocyanate component, a filler capable of phase changes is introduced from 20 do 120 % by weight in relation to the weight of the polyurethane mixture, depending on the amount of heat energy generated by the applied polyurethane system. The subject of the invention is also heat insulating composite material based on polyurethanes and/or polyisocyanurates, obtained by means of the above described method.

Description

Heat insulating composite materials and a method of their production

The invention refers to heat insulating composite materials, consisting of layers of rigid polyurethane foam and classic layers of expanded or extruded foamed polystyrene, and a method of their production. The materials according to the invention can be successfully used as cores of composite panels, as well as materials for elevation panels, roof planks, floor planks and suspended ceilings.

There are widely known and used heat insulating building materials in the form of panels made from foamed polystyrene (EPS, XPS), rigid polyurethane foam (PUR/PIR), or mineral wool (MW), intended for insulating external walls by means of using a light wet method and a light dry method, three-layered walls, ring beams, lintels, jamb, as well as roofs, flat roofs, floors and suspended ceilings. Moreover, these materials can be used as cores of composite panels, mainly in the form of prefabricated elements of roofs and external and internal walls constructions, as well as suspended ceilings in buildings of various purposes, e.g.: agricultural, industrial, commercial (shops, supermarkets, hypermarkets etc.), logistic, storage, distribution, sports and recreation, public buildings, etc. The main use of composite panels is in buildings which are to be built quickly and meet precisely determined characteristics following from the purpose of the building and technical requirements demanded from a specific building.

Foamed polystyrene, the so-called Styrofoam, is one of the most commonly known synthetic plastics. This material is obtained as a result of free radical polymerisation of styrene. In order to give the polymer a foam structure foaming substances (e.g. pentane isomers) are used, which at elevated temperature undergo evaporation, causing foaming of the solid mass of plastic and forming cell structure. Thanks to the porous structure foamed polystyrenes are light (apparent density from 10 to 40 kg/m³) and are characterized by a low thermal conductivity coefficient (depending on the class of density this coefficient ranges from 0,030 to 0,045 W/mK). Depending on the purpose, there are the following varieties of foamed polystyrene panels: EPS 30, EPS 50, EPS 60, EPS 70, EPS 80, EPS 90, EPS 100, EPS 120, EPS 150, EPS 200, EPS 250, EPS 300, EPS 350, EPS 400, EPS 500, where the numbers from 30 to 500 indicate the value of compressive stress measured in kPa at 10% deformation, and so e.g. foamed polystyrene used for insulating external walls with the use of the light wet method must be characterised by a minimal compressive strength of 70 kPa (density from 12 to 1 5 kg/m³), for floors or flat roofs 100 kPa (20 kg/m³ density), whereas as heat insulation of floors subjected to special loads, this value amounts to minimally 200 kPa (density from 30 to 40 kg/m³). Moreover, foamed polystyrenes are self-extinguishing plastics (class of fire resistance: E) and on a continuous running basis can be applied at a maximum temperature of 80 °C. The cost of manufacturing foamed polystyrenes is considerably lower in comparison with other heat insulating materials (i.e. rigid polyurethane foam, mineral wool), hence this material is used the most universally.

Rigid polyurethane foams are manufactured by way of an exothermic reaction of polymerisation of the isocyanate component (usually PMDI) with a polyol component, constituting a mixture of modified polyhydric alcohols. As a result of the chemical reaction the generated heat causes evaporation of low-boiling foaming agents (e.g. n-pentane), which initiates growth of volume of the material, and at the same time forming of the porous cell structure (apparent density from 35 to 60 kg/m³). Rigid polyurethane foams are characterised by better heat insulating parameters than these of foamed polystyrene (depending on the used foaming agent and density, the thermal conductivity coefficient ranges from 0,023 to 0,035 W/mK), as well as the mechanical ones. Similarly to foamed polystyrenes, polyurethane foams are self- extinguishing plastics (class of fire resistance E), but on a continuous running basis they can be used even at a temperature as high as up to 1 50°C, and in the case of polyisocyanurate foams (PIR) even up to 180 . Their price compares unfavourably with that of foamed polystyrenes, which translates directly into the cost increase if they are used for heat insulation of housing units.

There are also known composite panels consisting of constructional-insulating foamed polystyrene core or of rigid polyurethane foam, or of mineral wool, making the proper heat insulation and of a surface layer made from plastic film, laminated materials or sheet metal plates (see e.g. Polish patent specifications PL 187591 B1 , PL 191471 B1 , PL 1 77966 B1 , PL 193199 B1 ).

In the case of panels with a foamed polystyrene core, the core is glued to the facings with the use of a special polyurethane-based glue. In this case discontinuity of the core is mentioned. Gluing is an additional single manufacturing process in the technology of obtaining such a material, and at the same time increases its cost. On the contrary, panels with a polyurethane core are characterised by continuity of the core (physical and thermal continuity), because the core constitutes an insulating element as well as the gluing one (adhesion for facings). In comparison with panels with a foamed polystyrene core, polyurethane panels are characterised by higher rigidity, better heat insulating power. On the other hand, foamed polystyrene panels are relatively light and considerably cheaper than panels with polyurethane cores.

In order to lower the costs of polyurethane materials there are used methods of producing heat insulating composite materials, in which rigid polyurethane foam is the base phase. In these methods fillers such as granulated rubber, sawdust, granulated waste material made from polyurethane foam, PVC, saturated polyesters, as well as polystyrene for foaming (EPS) and expanded graphite (EG) are introduced into the polyurethane reaction mass.

In the US patent specifications Nos. US 6,605,650 and US 6,727,290 a method of utilising the heat of polyurethane polymerisation reaction for expanding and melting of polystyrene for foaming "beads" (EPS) was disclosed, as a result of which rigid polyurethane foam was obtained, in which the inside part of cells was covered with a thin layer of polystyrene plastic. The polystyrene layer was to delay the process of diffusion of the expanding agent from the inside of polyurethane foam cells, as a result of which the process of deterioration of thermal conductivity of the foam caused by diffusion exchange of expanding agents for the air was to be delayed. In the disclosed method the addition of polystyrene beads did not exceed 5% of the total weight of polyurethane components.

Polystyrene for foaming (EPS) as filler for rigid polyurethane foams was also described in the Polish patent specification No. PL 189498. The heat of formation of polyurethane allows for partial plasticization and growth of the EPS beads. This way a heat insulating composite is obtained which contains up to volumetric 50% of foamed polystyrene phase of physical and mechanical parameters as near as possible to foamed polystyrene. The combination of polyurethane foam and foamed polystyrene in the form of laminar composite materials could be characterised by favourable properties, combining the low cost of foamed polystyrenes with the excellent heat insulating parameters of rigid polyurethane foams (PUR). However, because of too large amount of heat released during the formation of PUR foams, as well as problems connected with its abstraction, to date there have not been known methods of combining these materials in a single-stage mode, with the formation of a polyurethane layer on the surface of foamed polystyrene. The only possibility was expensive gluing of the previously shaped materials, which complicated the whole manufacturing process. On the account of the above-mentioned reasons such a solution has not been used before.

The purpose of the invention is to develop a method of producing heat insulating composite materials based on rigid polyurethane or/and polyisocyanurate foams, in some particular cases containing fillers capable of phase changes, joined together to create a whole without the participation of adhesive agents (glues) with classic layers of expanded or extruded foamed polystyrene, combining the low cost of foamed polystyrenes with the excellent heat insulating properties of rigid polyurethane foams, as well as to obtain thus such heat insulating laminar materials.

The subject of the invention is a method of production of heat insulating composite materials based on polyurethanes or/and polyisocyanurates, joined together to create a whole without the participation of adhesive agents (glues) with classic layers of foamed polystyrene, characterised in that a polyurethane mixture containing a polyol and isocyanate component is directly poured out on the layer of foamed polystyrene, with the formation of a permanent weld exhibiting thermal continuity. Then, on the polyurethane mixture poured out on the first layer of foamed polystyrene optionally a second layer of foamed polystyrene is placed with the formation of a permanent weld exhibiting thermal continuity.

In the case of materials, whose thickness of foamed polystyrene layer is no less than 20 mm, to the polyurethane mixture, and especially to the isocyanate component, a filler is introduced which is capable of phase changes in the amount from 20 to 120 % by weight in relation to the weight of the polyurethane mixture, depending on the amount of heat energy generated by the used polyurethane system. The amount of the introduced filler is selected to the total weight of the polyurethane system in such a way that the maximum temperature of the reaction is lower than the temperature of degradation of foamed polystyrene i.e. from 120°C, and the time of lasting of temperatures above 80 °C is not longer than 20 minutes. The amount of filler thus selected will not cause the degradation of foamed polystyrene in the near- surface layer, as well as collapsing of its structure as a result of excessively long load above the working temperature of foamed polystyrene, apart from that, it will form a permanent weld with it. However, in the case of materials containing a layer of foamed polystyrene of maximum 20 mm thickness, a modification of rigid polyurethane foams with the use of filler capable of phase changes is not necessary.

Preferably, polystyrene for foaming (EPS) is used as filler capable of phase changes.

Preferably, foamed polystyrene of density from 10 to 20 kg/m³ and thermal conductivity coefficient at a temperature of 10°C from 0,035 to 0,045 W/mK is used.

Preferably, expanded or extruded foamed polystyrene is used.

The subject of the invention is also heat insulating composite material based on polyurethanes and/or polyisocyanurates, characterised in that it consists of layers of rigid polyurethane foam and foamed polystyrene joined together to create a whole without the use of adhesive agents (glues), and is obtained by pouring polyurethane mixture containing a polyol and isocyanate component directly out on the layer of foamed polystyrene with the formation of a permanent weld exhibiting thermal continuity.

Optionally, the heat insulating composite material according to the present invention is obtained by applying on the polyurethane mixture poured out on the first layer of foamed polystyrene mixture a second layer of foamed polystyrene with the formation of a permanent weld exhibiting thermal continuity. In this case what is obtained are three-layer materials, consisting of two external layers of foamed polystyrene, joined together to create a whole without the use of adhesive agents with a layer of rigid polyurethane foam inside, according to the above described method. Additionally, the external layers of foamed polystyrene make a diffusion barrier, and the three-layer material manufactured in this way maintains its heat insulating properties for longer periods of time.

In cases when the thickness of foamed polystyrene layer in the heat insulating material according to the present invention is no less than 20 mm, the polyurethane mixture additionally contains filler capable of phase changes from 20 to 120 % by weight in relation to the weight of polyurethane mixture. Preferably, the heat insulating composite material according to the invention contains polystyrene for foaming (EPS) as filler capable of phase changes.

Preferably, the heat insulating composite material according to the invention contains foamed polystyrene of density from 10 to 20 kg/m³ and thermal conductivity coefficient at a temperature of -\ 0°C from 0,035 to 0,045 W/mK.

Preferably, the heat insulating composite material according to the invention contains expanded foamed polystyrene.

Preferably, the heat insulating composite material according to the invention contains extruded foamed polystyrene.

During the formation of polyurethane foam, as a result of exothermic reaction of polymerisation a considerable amount of heat energy is released. The released energy causes evaporation of low-boiling foaming agents (e.g. n-pentane, HFC 365/227), as well as releasing of carbon dioxide (C0₂), produced as a result of a chemical reaction of water with -NCO groups, leading to the formation of a closed- cell structure with heat insulating properties. The porous structure formed in this way severely limits the diffusion potential of heat from the interior of the foam outside, as a result of which the temperatures accompanying the formation of polyurethane foams can reach even 180°C. Because thermal stability temperatures of foamed polystyrenes reach maximum 80 °C, and the temperature of their degradation is 120°C direct contact of the foamed polystyrene phase with the forming polyurethane phase can lead to the destruction of the first, and at the same time to collapsing of the material. It should also be remembered that foamed polystyrene is also a material with heat insulating properties, which additionally hinders the diffusion of heat from the interior of the forming polyurethane.

It was unexpectedly found that by modifying rigid polyurethane foams with fillers in the form of e.g. polystyrene for foaming (EPS) or expanding graphite (EG), the heat energy accompanying the reaction of polyurethane polymerisation is reduced, which allows for the elimination of degradation of foamed polystyrene during the process of pouring the polyurethane mixture out on its surface. The weld formed in this way does not injure the foamed polystyrene layer, and is also characterised by excellent adhesion to it.

It was also found that as a result of appropriate matching of the thickness of foamed polystyrene layers to the layer of rigid polyurethane foam it is possible to obtain composites without the use of additional fillers. In this case thanks to the very good heat insulating properties the forming layer of polyurethane forms a heat barrier, whereas the thin layer of foamed polystyrene, maximally up to 20 mm, ensures appropriate heat abstraction from the near-surface layer, where temperatures do not reach the temperature of degradation of foamed polystyrene.

Moreover it was found that the layer of foamed polystyrene, onto whose surface polyurethane mixture is poured out, ensures a favourably reduced heat energy gradient, which eliminates the necessity of heating the mould, and at the same time can lower the cost of manufacturing of such material.

The heat insulating composite materials according to the invention can be found in the form of two- or three-layer laminar composites. Depending on the thickness of foamed polystyrene layers being used, pure polyurethane foam or polyurethane foam modified with fillers capable of phase changes, such as e.g. polystyrene for foaming (EPS) or expanding graphite (EG) are used.

The heat insulating composite materials according to the invention are characterized by good heat insulating parameters (heat transmission coefficient is no higher than 0,30 W/m2-K). Moreover, these properties can be modelled by using different variants of thickness and density of particular layers, as well as using polyurethane and foamed polystyrene of different composition.

Examples

Example 1

In a flat, unheated mould with dimensions 300 x 300 x 100 [mm] there was placed a foamed polystyrene panel of 50 mm thickness, 10 kg/m³ density and thermal conductivity coefficient of 0,042 W/mK, and then onto it was poured out polyurethane foam reaction mass of the following composition:

- 89 g polymeric phenyl diisocyanate (PMD) with -NCO groups content at 26% and viscosity of 250 mPa-s,

- 90 g of polystyrene for foaming beads OWIPIAN FS 1325 produced by Synthos S.A. of 1 ,3 - 2,5 mm grain size, containing approximately 6% by weight of pentane mixture (64 - 75% of n-pentane and 25 - 34% of isopentane) and 1 ,0% by weight of moisture. The above components were mixed together with the use of a stirrer (about 600 rpm) after being heated to a temperature of 20 °C, and then 59,5 g of polyol component WG 2034 NF manufactured by Polychem Systems Ltd. with a viscosity of 400 mPa-s, which contains 5,2% of chemical expanding agent by weight was added to the mixture, and after the next, this time very vigorous stirring (about 1200 rpm) the mixture was transferred to a mould. The composite was left for about 20 minutes, enabling the mixture to rise freely in the mould.

The material obtained this way was characterized by the following properties: apparent density 30 kg/m³, heat transmission coefficient 0,30 W/m²-K.

Example 2

The components were prepared as in Example 1 , except that a foamed polystyrene panel of 50 mm thickness, 5,2 kg/m³ density and thermal conductivity coefficient of 0,038 W/mK was used.

The material obtained in this way was characterized by the following properties: apparent density 32,6 kg/m³, heat transmission coefficient 0,29 W/m²-K.

Example 3

In a flat, unheated mould with dimensions 300 x 300 x 100 [mm] there was placed a foamed polystyrene panel of 20 mm thickness, 15,2 kg/m³ density and thermal conductivity coefficient of 0,038 W/mK, and then onto it was poured out polyurethane foam reaction mass of the following composition:

- 190,2 g of polymeric phenyl diisocyanate (PMD) with -NCO groups content at 26% and a viscosity of 250 mPa-s,

- 126,8 g of polyol component WG 2034 NF manufactured by Polychem Systems Ltd. with a viscosity of 400 mPa-s, which contains 5,2% of chemical expanding agent by weight

The above components were mixed together with the use of a stirrer (about 1200 rpm) after being heated to a temperature of 20 °C, and then they were transferred to a mould. The composite was left for approximately 20 minutes, enabling the mixture to rise freely in the mould.

The material obtained in this way was characterized by the following properties: apparent density 35 kg/m³; heat transmission coefficient 0,25 W/m²-K. Example 4

- 179,2 g of polymeric phenyl diisocyanate (PMD) with -NCO groups content at 26% and a viscosity of 250 mPa-s,

- 1 37,8 g of polyol component IZOPIANOL 22/33 OT-P manufactured by Purinova Ltd. with a viscosity of 500 - 700 mPa-s, which contains 2,0% of chemical expanding agent by weight and 15 - 20% by weight of physical expanding agent in the form of HFC 365/227.

The material obtained in this way was characterized by the following properties: apparent density 35 kg/m³; heat transmission coefficient 0,23 W/m²-K.

Example 5

- 134,5 g of polymeric phenyl diisocyanate (PMD) with -NCO groups content at 26% and a viscosity of 250 mPa-s,

- 1 03,5 g of polyol component IZOPIANOL 22/33 OT-P manufactured by Purinova Ltd. with a viscosity of 500 - 700 mPa-s, which contains 2,0% of chemical expanding agent by weight and 15 - 20% by weight of physical expanding agent in the form of HFC 365/227.

The above components were mixed together with the use of a stirrer (about 1200 rpm) after being heated to a temperature of 20°C and were transferred to a mould, and then on the surface of the polyurethane mixture was placed a foamed polystyrene panel of 20 mm thickness, 1 5,2 kg/m³ density and thermal conductivity coefficient 0,038 W/mK. The composite was left for approximately 20 minutes, enabling the mixture to rise freely in the mould.

The material obtained in this way was characterized by the following properties: apparent density 30 kg/m³; heat transmission coefficient 0,25 W/m²-K.

Claims

1 . The method of production of heat insulating composite materials based on polyurethanes and/or polyisocyanurates, joined together to create a whole with classic layers of foamed polystyrene, characterised in that onto the layer of foamed polystyrene a polyurethane mixture containing a polyol and isocyanate component is directly poured out, with the formation of a permanent weld exhibiting thermal continuity.

2. The method according to claim 1 , characterised in that onto the polyurethane mixture poured out onto the first layer of foamed polystyrene a second layer of foamed polystyrene is placed with the formation of a permanent weld exhibiting thermal continuity

3. The method according to claim 1 or 2, characterised in that, in the case of materials, in which the thickness of foamed polystyrene layer is no less than 20 mm, to the polyurethane mixture, and especially to the isocyanate component, a filler capable of phase changes is introduced from 20 do 1 20 % by weight in relation to the weight of the polyurethane mixture.

4. The method according to claim 3, characterised in that polystyrene for foaming (EPS) is used as a filler capable of phase changes.

5. The method according to any of claims 1 -4, characterised in that foamed polystyrene of 10 to 20 kg/m³ density and thermal conductivity coefficient at a temperature of 10°C from 0,035 to 0,045 W/mK is used.

6. The method according to any of claims 1 -5, characterised in that expanded foamed polystyrene is used.

7. The method according to any of claims 1 -6, characterised in that extruded foamed polystyrene is used.

8. Heat insulating composite material based on polyurethanes and/or polyisocyanurates, characterised in that it consists of rigid polyurethane foam layers and foamed polystyrene layers joined together to create a whole, and is obtained by pouring out the polyurethane mixture containing a polyol and isocyanate component directly onto the layer of foamed polystyrene with the formation of a permanent weld exhibiting thermal continuity.

9. Heat insulating composite material according to claim 8, characterised in that it is obtained by placing onto the polyurethane mixture poured out onto the first layer of foamed polystyrene a second layer of foamed polystyrene with the formation of a permanent weld exhibiting thermal continuity.

10. The heat insulating composite material according to claim 8 or 9, characterised in that in the case when the thickness of the foamed polystyrene layer is no less than 20 mm, the polyurethane mixture contains a filler capable of phase changes from 20 to 1 20 % by weight in relation to the weight of the polyurethane mixture.

1 1 . The heat insulating composite material according to claim 10, characterised in that as a filler capable of phase changes it contains polystyrene for foaming (EPS).

12. The heat insulating composite material according to any of claims 8-1 1 , characterised in that it contains foamed polystyrene of density from 10 do 20 kg/m³ and thermal conductivity coefficient at a temperature of 10°C from 0,035 to 0,045 W/mK.

13. The heat insulating composite material according to any of claims 8-12, characterised in that it contains expanded foamed polystyrene.

14. The heat insulating composite material according to any of claims 8-13, characterised in that it contains extruded foamed polystyrene.