Production of polyisocyanurate foam panels

Abstract

The present invention discloses the production of panels by a discontinuous process. The panels are produced by injecting a polyisocyanurate foam forming composition into the mold cavity at reduced pressure. The combination of certain polyisocyanurate foam forming formulation and the reduced pressure in the mold cavity allows production of and resulting sandwich panels in a discontinuous process where the produced panels are characterized by improved fire resistance.

Claims

1. A method of making a polyisocyanurate (PIR) foam, comprising: A) injecting into a closed mold cavity, wherein said mold cavity is under an absolute pressure of from 300 to 950 mbar, a reaction mixture comprising: a) an organic polyisocyanate; b) a polyol mixture, wherein the polyol mixture comprises an aromatic polyester polyol, wherein the aromatic polyester polyol is at least 35 weight percent of the total amount of polyol; c) a trimerisation catalyst; d) at least one flame retardant; e) optionally auxiliary substances; and f) a blowing agent component, wherein said reaction mixture has an isocyanate index of greater than 250 and a gel time of at least 50 seconds; and B) curing to form a polyisocyanurate foam.

2. The method according to claim 1, wherein said closed mold cavity is defined by two exterior shells and an annular frame.

3. The method according to claim 1, wherein the aromatic polyester polyol is at least 50 weight percent of the total amount of polyol.

4. The method according to claim 1, wherein the reaction mixture has an isocyanate index of greater than 350.

5. The method according to claim 1, wherein the mold cavity absolute pressure is from 800 to 950 mbar.

6. The method according to claim 1, wherein the blowing agent component comprises a physical and chemical blowing agent.

7. The method according to claim 6, wherein the chemical blowing agent is water, formic acid or a combination thereof.

8. The method according to claim 6, wherein the physical blowing agent is pentane.

9. The method according to claim 1, wherein the foam has an applied density of 30 to 75 kg/m3.

10. The method according to claim 1, wherein the reaction mixture additionally comprises a silicone surfactant.

11. The method according to claim 1, wherein the flame retardant is a halogen free flame retardant.

12. The method according to claim 1, wherein the aromatic polyester polyol is at least 50 weight percent and less than 80 weight percent of the total amount of polyol.

13. The method according to claim 12, wherein the aromatic polyester polyol is derived from phthalic anhydride, phthalic acid, isophthalic acid, terephthalic acid, methyl esters of phthalic, isophthalic acid, terephthalic acid, dimethyl terephthalate, trimellitic anhydride, pyromellitic dianhydride, or mixtures thereof.

14. The method according to claim 1, wherein the aromatic polyester polyol is derived from phthalic anhydride, phthalic acid, isophthalic acid, terephthalic acid, methyl esters of phthalic, isophthalic acid, terephthalic acid, dimethyl terephthalate, trimellitic anhydride, pyromellitic dianhydride, or mixtures thereof.

15. The method according to claim 1, wherein the polyol mixture further includes from 10 to 60 weight percent of a novolac initiated polyether polyol, of the total amount of polyol.

Description

EXAMPLES

(1) Halogen flame retardant based formulations were produced according to the components in Table 1.

(2) TABLE-US-00001 TABLE 1 System No. 1 2 3 4 Polyol 1 25.43 25.43 25.43 25.43 Polyol 2 22.1 22.1 22.1 22.1 Polyol 3 Polyol 4 Additive 1 FR 1 FR 2 8.51 8.51 8.51 8.51 FR 3 33.81 33.81 33.81 33.81 Surfactant 4 4 4 4 Catalyst 1 2.05 2.05 2.05 2.05 Catalyst 2 0.25 0.25 0.25 0.25 Formic acid 3.4 3.4 3.4 3.4 water 0.45 0.45 0.45 0.45 Total 100 100 100 100 Index 400 300 400 300 c/i-pentane* 6 6 10 10 Isocyanate 216 162 216 162 *Is a 70/30 wt/wt blend of cyclo-/isopentane.

(3) The polyol formulations/blowing agents were mixed with the isocyanate and injected into a mold at ambient pressure of about 1000 mbar to produce standard foam (Comparative Examples 1-4) and molds maintained at 900 mbar (Examples 1-4). The properties of the produced foams are shown in Table 2. Formulations 3 and 4 (comparative examples 3 and 4) utilize a higher level of hydrocarbon blowing agent to obtain densities comparable to those obtained in Examples 1 and 2.

(4) TABLE-US-00002 TABLE 2 System 1 System 2 System 3 System 4 Comp Ex 1 Ex 1 Comp Ex 2 Ex 2 Comp Ex 3 Comp Ex 4 Mold pressure (bar) 1 0.9 1 0.9 1 1 Cream Time (s) 7 4 10 7 Gel Time (s) 64 51 90 60 Free Rise Density (kg/m.sup.3) 33.2 27.5 30.5 26.5 MFD (g/l) 46.5 41.05 39.3 35.05 41.93 37.8 Flow Index 1.401 1.236 1.429 1.275 1.375 1.426 Applied Density (g/l) 51.96 43.20 45.76 39.14 46.80 41.60 Average Density Deviation 1.248 0.811 0.938 0.568 0.805 n.d. Compressive Strength (kPa) 287 181 209 141 205 134 EN ISO 11925-2, flame height (cm) 6 5 8 6 11 12 ISO 5660-1, Peak of heat release 86.7 81.0 76.1 68.1 87.3 n.d. (kW/m.sup.2)

(5) Halogen-free flame retardant formulations were produced according to the components in Table 3.

(6) TABLE-US-00003 TABLE 3 System No. 5 6 7 8 9 10 Polyol 1 48.3 49.2 49.2 49.2 23 23 Polyol 2 20.6 20.6 20.6 20.6 10.6 10.75 Polyol 3 35 35 Polyol 4 7 Additive 1 7 FR 1 15 15 15 15 15 FR 2 8.5 8.5 8.5 8.5 8.5 8.5 FR 3 Surfactant 4 4 4 4 4 4 Catalyst 1 1.1 1.1 0.9 1.2 1.25 1 Catalyst 2 0.2 0.2 0.2 0.2 0.35 0.25 Formic acid 1.8 1.1 0.5 1.8 1.8 1.8 water 0.5 0.3 0.2 0.5 0.5 0.5 Total 100 100 99.1 100 100 99.8 Index 350 350 350 350 350 230 c/i-pentane 6.5 10 12.5 6.8 7.5 5 % mols HC/tot. 57.4 77.4 88.8 50.9 60.9 64.2 mmoles B.A Isocyanate (parts by 191 168 149 191 213 139 weight)

(7) The polyol formulations/blowing agents were mixed with the isocyanate and injected into a mold at ambient pressure of about 1000 mbar to produce standard foam (Comparative Example 5 and Comparative Example 8) and molds maintained at 900 mbar (Examples 3-6 and Comparative Examples 10 and 12). Comparative examples 6, 7, 9, 11 are produced by pouring the reactive mixture into a bag and measuring reactivity and FRD.

(8) TABLE-US-00004 TABLE 4 System 5 System 6 System 7 System 8 System 9 System 10 Comp Comp Comp Comp Comp Comp Comp Comp Ex 5 Ex 3 Ex 6 Ex 4 Ex 7 Ex 5 Ex 8 Ex 6 Ex 9 Ex 10 Ex 11 Ex 12 Mold pressure 1 0.9 1 0.9 1 0.9 1 0.9 1 0.9 1 0.9 (absolute bar) Cream Time (s) 11 10 10 9 12 8 Gel Time (s) 75 60 63 74 97 78 Free Rise Density 38.55 34.82 33.8 35.2 39.06 35.3 (kg/m.sup.3) MFD 50? C. (g/l) 60.3 54.28 n.d. 49.26 n.d. 50.47 55.2 51.15 n.d. 51.05 n.d. 50.48 Flow Index 50? C. 1.56 1.408 n.d. 1.41 n.d. 1.49 1.57 1.45 n.d. 1.31 n.d. 1.43 Applied Density n.d. 57 51.7 53 58.7 53.7 53.6 53 (g/l) Average Density 0.655 0.62 0.63 0.56 0.63 0.63 Deviation Compressive n.d. 228 136 129 174 196 184 172 Strength (kPa) Thermal 22.31 22.4 21.62 21.65 22.96 23.12 Conductivity 10? C. (mW .Math. m ? K) EN ISO 11925-2, 5.5 4 6.5 7.5 5 8 10 flame height (cm) ISO-5601-1, Total n.d. 15.7 14.5 16 17.5 14.3 15.6 n.d. heat release (MJ/m.sup.2) ISO 5660-1, Total n.d. 338 225 243 331 206 394 n.d. smoke production (m.sup.2/m.sup.2)

(9) TABLE-US-00005 TABLE 5 System 5 Ex 3 Ex 3a Ex 3b Ex 3c Ex 3d Brett Mold Pressure at 50? C. (bar) 0.9 0.8 0.8 0.7 0.7 Applied Density (g/l) 57 57.7 52 57.3 52.1 Average Density Deviation 0.655 0.4 0.43 0.39 0.5 Compressive Strength (kPa) 228 279.3 194.2 274.7 224.6 Thermal Conductivity 10? C. (mW/m ? K) 22.31 22.15 22.64 23.24 22.7 Aesthetics good Very good good Very good good filling OK OK OK OK OK

(10) To determine the versatility of the present process, System 5 is used to produce foams at various pressures to determine the applied density and to visually observe the aesthetic properties of the produced insulated panels. The obtained results are given in Table 5 above. Aesthetics refers to visual observation of quantity and size of the voids.

(11) The results in Table 2 and 4 show that the foams of the present invention (Examples 1-6) meet the requirements for reaction-to-fire Euroclass E according to EN ISO 11925-2 standard (flame height of less than 15 cm) and exhibit a good reaction profile.

(12) As can be seen from Examples 1 and 2 in Table 2, the foams of the present invention (molded at 900 mbar) show reduced flame height properties as compared to foams of the same formulation, produced under standard pressure conditions. For instance, the flame height of system 1, molded at 1000 mbar is 6 cm, whereas the flame height of system 1 molded at 900 mbar is only 5 cm.

(13) Examples 1 and 2 also demonstrate that peak of the heat release produced by the foams molded at 900 mbar is lower than that of the foams molded at 1000 mbar.

(14) As can be seen from Table 4, the halogen-free formulation of Example 3 and 6 molded at 900 mbar, also has significantly improved fire properties than the foam of the same formulation molded at 1000 mbar. The 10 percent reduction in mold air pressure leads, together with the reduced applied densities, to a reduction in EN ISO 11925-2 flame height, in a reduction of total heat release, and a significant reduction in the total smoke produced.

(15) System 9 and 10 do not fall within the scope of the present invention. System 9 does not comprise a polyol mixture that is at least 35 weight percent aromatic polyester polyol. System 10 similarly does not comprise a polyol mixture that is at least 35 weight percent aromatic polyester polyol and also does not have an isocyanate index of greater than 250

(16) As can be seen from Table 4, the systems of the present invention (i.e., examples 3-6 comprising a polyol mixture made up of at least 35 weight percent aromatic polyester polyol and having an isocyanate index of greater than 250), result in foams having improved fire properties over the foams of systems 9 and 10, when molded at 900 mbar. For example, the flame height of system 10, molded at 900 mbar is 10 cm, whereas the flame height of examples 3-6, molded at 900 mbar are all less or equal than 7.5 cm. In addition the total smoke produced by system 9, molded at 900 mbar, is significantly greater that the total smoke produced by any of examples 3-6 when molded at 900 mbar.

(17) As can be seen from Table 4 and 5 the method of the invention allows the production of PIR foams characterized by excellent thermal insulation. Moreover, as shown in Table 5 the method allows to easily control the cavity filling and the material distribution (density deviation), by adjusting the absolute pressure in the mold cavity.

(18) Whilst the invention has been described with reference to a preferred embodiment, it will be appreciated that various modifications are possible within the scope of the invention.

(19) In this specification, unless expressly otherwise indicated, the word or is used in the sense of an operator that returns a true value when either or both of the stated conditions is met, as opposed to the operator exclusive or which requires that only one of the conditions is met. The word comprising is used in the sense of including rather than in to mean consisting of. All prior teachings acknowledged above are hereby incorporated by reference. No acknowledgement of any prior published document herein should be taken to be an admission or representation that the teaching thereof was common general knowledge in Australia or elsewhere at the date hereof.