IE86043B1 - A phenolic foam board - Google Patents

Description

A phenolic foam board Introduction Phenolic foam is used in insulation applications for construction materials because of its superior thermal insulation and fire properties including low smoke emission and good fire resistance.

Phenolic foam is generally produced by expanding and curing a foamable composition prepared by uniformly mixing a resole resin, (obtained by a poly condensation reaction of phenol and formaldehyde in the presence of an alkaline catalyst), a blowing agent (generally a volatile liquid or gas with a lower thermal conductivity than air), a surfactant, and a curing catalyst. Other additives can optionally be mixed into the resin such as plasticisers, flame retardants and pigments.

Foam insulation panels often have gas impermeable facers such as foil facers. These facers are bonded to the foam core by making use of the inherent adhesive ability of the foaming resin Gas impermeable facers such as aluminium foil facers are used to reduce the emissivity of the without the need for additional adhesives. This is known as autohesive bonding. product. Emissivity is the ratio of energy emitted by the facer to the energy emitted by a perfect black body, a lower value indicating good heat reflection of the facer, which contributes to the insulation value of the final product.

During the polymerisation reaction of phenol and formaldehyde, a significant amount of water will be formed. This water has to be removed by drying to obtain a product with good dimensional stability, usually in a separate drying or curing step at elevated temperature. When gas impermeable facers are used, for example, aluminium foils, very long curing times will be needed to dry the product. Very high temperatures (i.e. above 100°C) cannot be used for curing of these products as the vaporised water will cause excessive pressure in the closed cells of the foam leading to rupture of these cells and loss of blowing agent, which leads to relatively poor insulation values as the blowing agent is replaced by air.

In practice, the curing time of an insulation panel faced on both sides with non gas-permeable facers will depend on the product thickness. Insulation panels with gas impermeable facers will take more than 3 times longer to dry and cure than a panel with a gas permeable facer. zéotcz Products faced with non gas-permeable facers such as aluminium foils which are adhesively bonded to the product, after curing, are not commercially viable in view of the added handling costs involved.

Statements of Invention The phenolic foam thermal insulation products of the invention have perforations in gas- impermeable facer material. These perforations reduce the drying and curing time when compared with gas permeable faced products. The aged thermal conductivity of such products is also improved. The perforations are made in a gas-impermeable facer material prior to manufacture of the phenolic insulation board. The phenolic foam insulation board has an aged thermal conductivity of less than 0.02 W/m.K when faced on both sides with perforated gas- The perforations may be between 0.05 and 2 mm in diameter and may be spaced from 2 mm to 50 impermeable facer materials which are autohesively bonded during manufacture. mm apart. The perforations are typically between 0.1 and 1.5 mm diameter and are spaced from mm to 30 mm apart.

The perforations can be made from one or both sides of the facer.

The perforations may be of any shape and may be made using a tool which is, for example, tubular, conical or pyramidical in shape. A pyramidical spiker may create an X-shaped perforation with a width of typically 1.0 mm with centres of typically 3.8 mm.

According to the invention there is provided a method for manufacturing a rigid phenolic insulating foam body comprising a first facer applied to a first face of the insulating foam body and a second facer applied to a second face of the insulating foam body, both of the facers comprising a gas impermeable material, wherein both the first and the second facer are pre- perforated before the facers have been adhered to the foam and wherein the foam body has an aged thermal conductivity of less than 0.02 W/m.K; and the method comprising the steps of- leading the first or base facer to a lay down area; laying liquid foam reactants down on the base facer; leading the second or upper facer over the foam reactants; leading the sandwich thus formed through an oven; and cutting the foam board thus formed to a desired length.

The first and second facers comprise a substantially gas impermeable material. The first and/or second facers may comprise a metallic foil such as an aluminium foil. The facets may be laminate such as a metallic foil laminated onto a glass tissue or a metallic foil laminated onto a Kraft paper.

Brief Description of the Drawings The invention will be more clearly understood from the following description thereof given by way of example only with reference to the accompanying figures, in which:- Figs. 1(a) and l(b) are schematic views showing perforation patterns for pre—perforated facer; Fig. 2 is a schematic view showing another perforation pattern; Fig. 3 is a diagram illustrating the formation of perforations in a facer using a spiked roller; Fig. 4 is a plan view of a perforated facer; Fig. 5 is a perspective View of the perforated facer; Fig. 6 is another diagram illustrating the formation of perforations in a facer; Figs. 7(a) and 7(b) are diagrams illustrating the formation of perforations in facers; Fig. 8 is a diagram of a foam board with pre-perforated facers; Fig. 9 is a side view illustrating the formation of perforations in the facers of a foam board; and Fig. 10 is a cross sectional view illustrating the formation of perforations using the apparatus of Fig. 9.

Detailed Description It has been surprisingly found that the presence of small perforations in a gas impermeable facer, will result in a shortened insulation board drying (curing) time following production of the board. This shortened drying time is comparable with the drying time taken for foam insulation products of the same thickness that have gas permeable facers such as glass fibre facers.

The perforations are made in the facer of the phenolic foam insulation panel before the foam is applied to the facers. The hole size and spacing is carefully selected (typically between 0.1 and .5 mm, generally less than 1 mm) to avoid bleed-through of the liquid pre-polymer.

Example 1: In this case, the perforations are made in the facers itself, before the foaming process.

For this purpose, two different facers were perforated and used to make foam panels. The first facer consisted of an aluminium foil laminated onto glass tissue.

Referring to Figs. 3 to 8 the facers 1 may be perforated using a spiked roller 2 with a plurality of spikes 3 which form a plurality of perforations 5 in the facer l. A spiked roller is described in GB-A-2,3 83,971.

The perforation pattern for the aluminium-glass fibre facer, and the perforation size of 0.7mm are given in Figure 1(a).

With both facers perforated, phenolic foam insulation panels 8 with a thickness of 50 mm were produced.

Phenol formaldehyde foam insulation boards, with a thickness of 50 mm, were produced with gas impermeable facers comprising aluminium foil laminated onto glass tissue. The perforated facer was used as a facer on both sides. According to the process for producing phenolic foam of the present invention, a foamable phenolic resin composition is discharged on to a continuous running perforated facer and passed through a heated zone for foaming and moulding into phenolic foam products of predetermined shape. In this manufacturing process, the phenolic resin composition that has been discharged on to the running perforated facer material supported by a conveyor belt that passes into a heated oven typically at 50 to 100°C for approximately 2 to minutes. The top surface of the rising foam composition is pressed down with another perforated facer material carried by an upper conveyor belt. The thickness of the foam is controlled to the required predetermined thickness. The phenolic foam leaving the oven is then cut to a predetermined length.

Using the same process as described above a foam board was produced using facers comprising a Krafi paper — aluminium foil laminate. The perforation pattern for the aluminium-Krafi paper facer, and the perforation size of 0.1mm are given in Figure l(b). The facers may be perforated using a helical spiked roller as described above. The perforated facer was used as a facer on both sides.

As a control reference, samples of the same thickness panel were made with the same facers but were non-perforated. These samples were dried in an oven at 80°C for 5 hours.

Table 1 shows the weight loss of the product after 5 hours of drying at 80°C Description Weight loss [%l Perforated Aluminium kraft paper laminate (perforation size 0.1 mm 7.5 diameter) Non perforated Aluminium krafi paper laminate 4.6 Perforated Aluminium glass tissue laminate (0.7 mm diameter) 10.8 Non perforated Aluminium glass tissue laminate 4.7 Table 1: Weight loss for perforated and non-perforated facers for panel thickness 50 mm.

Perforation of the foils results in an increase of the drying rate of foam panel products. A perforation size of 0.1mm approximately doubles the drying rate.

The invention provides pre-perforation of the facers as described in Example 1 which has the advantage of eliminating the occasional formation of gas blisters between the facer and the foam surface. These blisters can occur when manufacturing with a gas-tight facer and result when gas is released from the foam during processing (from water vapour or blowing agent) which cannot escape through the gas-impermeable facer, and results in a gas bubble between the facer and the foam surface with loss of facer adhesion in that area. These blisters can vary in size from a few mm diameter to tens of centimetres and are undesirable both aesthetically and in their reduction of facer tensile properties.

Example 2 (which does not described the production of a foam body according to the present invention): Phenol formaldehyde foam insulation boards, with a thickness of 80mm, were produced with a gas impermeable two-layer aluminium foil — glass fibre tissue laminate facer on both sides. The assembly of this two-layer facer was arranged such that the glass fibre layer of the two-layer facer was bonded to the phenolic foam. According to the process for producing phenolic foam of the present invention, a foamable phenolic resin composition is discharged on to a continuous running facer and passed through a heated zone for foaming and moulding into phenolic foam products of predetermined shape. In this manufacturing process, the phenolic resin composition that has been discharged on to the running facer material supported by a conveyor belt that passes into a heated oven typically at 50 to 100°C for approximately 2 to 15 minutes. The top surface of the rising foam composition is pressed down with another facer material carried by an upper conveyor belt. The thickness of the foam is controlled to the required predetermined thickness. The phenolic foam leaving the oven is then cut to a predetermined length.

Thereafier, one of these foam insulation panels was perforated on one side using a helical spiked roller as described in GB-A-2,383,971. The pattern and depth of the perforations is given in Figure 2. The diameter of each of the perforations is approximately 0.5 mm.

Another 80mm thick phenol formaldehyde foam insulation panel, which had been faced on both sides with the same aluminium foil - glass fibre tissue facer was perforated on both sides, according to the pattern given in Figure 2 using the same helical spiker device. This arrangement is illustrated in Figs. 9 and 10 in which a foam board 10 is passed between two helical spiked rollers 11, 12 with spikes lla, 12a to form a foam board 13 with facers 14, IS on both sides. Both of the facers 14, 15 are perforated.

These perforated samples together with a sample of phenolic foam panel which had on both sides of the panel the same aluminium foil — glass tissue facer but without perforations and an insulation panel faced with gas permeable plain glass tissue were placed in an oven at 70°C.

Afier 4, 8 and 12 hours, the weight loss of these samples was determined.

Table 2 gives the weight loss of these four samples as function of the drying time Description Data Product thickness [mm] 80 80 80 Drying time [hours] 4 8 I2 Drying temperature [°C] 70 70 70 Weight loss of double sided aluminium foil — glass tissue faced product with no perforations [w%] 0'45 OJ?‘ 1'16 Weight loss of double sided aluminium foil — glass tissue faced product with single side of perforations [w%] 2'75 4'04 5'48 Weight loss of double sided aluminium foil — glass tissue faced product with double sided perforations [w%] 4'” 6'95 8'86 Weight loss of double sided glass tissue faced product (reference 3.96 6.8] 8.70 sample) [w%] Table 2: Weight loss as fimction of the drying time Table 2 shows that the weight loss of the double-sided perforated product is comparable to the weight loss of the product faced with a gas permeable facer such as fibreglass tissue.

Table 3 shows the physical properties of these 80 mm thick samples after 8 hours of drying at 70°C. All measurements are performed according to EN] 3 166 2001.

Thermal Description Compressive Delamination Initial Conductivity Strength Strength Thermal after 25 weeks Conductivity at 70°C [kPa] [kPa] 4 days at 70°C + 23°C/50% [W/m.K] RH [W/m.K] Double sided aluminium foil — glass fibre tissue faced 1.7] 85 0.0194 0.02” product (no perforations) Double sided aluminium foil — glass fibre tissue faced 164 92 (N185 0.0194 product (single sided perforations) Double sided aluminium foil — glass fibre tissue faced 175 102 0.0185 0.0195 product (double sided perforations) Double sided glass tissue (reference sample) 169 95 0.0180 0.0190 Table 3: Physical properties of perforated products.

The compressive strength is comparable for all products.

Perforating the facer seems to improve the delamination strength slightly. The thermal conductivity afier accelerated ageing for the perforated product is comparable with the product with a gas permeable facer. The initial thermal conductivity of the product faced with a perforated aluminium-glass fibre tissue is slightly higher. This is due to the aluminium facer, which gives slightly higher readings in the thermal conductivity measuring instrument. {Fox Laser comp 314].

The product without perforations gave higher initial thermal conductivity and the increase in thermal conductivity following thermal ageing is higher compared to the perforated product.

Example 3 (which does not describe the production of a foam body according to the present invention): Phenolic foam was produced with a thickness of 40 mm. In the same way as in Example 2, the product was faced on both sides with a gas impenneable two layer aluminium-glass tissue facer.

This insulation panel sample was then perforated on one side as described above. The pattern and depth of the perforations is shown in Figure 2.

As with Example 2, these samples were placed in a drying oven and conditioned at 70°C.

Alongside this sample was a reference sample which was non-perforated. Also present in this evaluation was a sample that was faced with plain glass tissue.

Table 4 gives the weight loss of these three samples as function of the drying time Description Data Product thickness [mm] 40 40 40 40 Drying time [hours] ] 2 3 4 Drying temperature [°C] 70 70 70 70 Weight loss double side aluminium foil-glass fibre faced product no perforations [w%] 0'14 0'17 0'21 0'52 Weight loss double sided aluminium foil-glass fibre faced product single sided perforated [w%] 1'21 2'78 3'36 4'20 Glass tissue (reference sample) [w%] 3.04 4.45 4.94 5.93 : Table 4: Weight loss as function of the driving time (product thickness 40 mm) Table 4 shows that the weight loss of the single sided perforated product is much higher compared to the weight loss of the product faced with an impermeable facer.

Table 5 shows the product properties of these 40 mm thick samples after 4 hours of drying at 70°C. ' All measurements are performed according to EN 1 3 1 66 2001.

Thermal Description Thermal Conductivity Compressive Delamination Conductivity after 25 weeks Strength Strength Initial at 70°C [kPa] [kPa] [W/m.K] [W/m.K] Weight loss double sided aluminium foil - glass fibre I62 89 0.0197 0.0201 faced product (no perforations) Weight loss double sided aluminium foil—glass ‘fibre 152 84 0.0188 0.0196 faced product (single sided perforated) Glass tissue (reference sample) 169 87 0.0177 0.0188 Table 5: Physical properties perforated product (product thickness 40 mm).

The invention is not limited to the embodiments hereinbefore described which may be varied in detail.

Claims (8)

Claims

1.A method for manufacturing a rigid phenolic insulating foam body having a first facer applied to a first face of the insulating foam body and a second facer applied to a second face of the insulating foam body, both of the facers comprising a gas impermeable material, wherein both the first and the second facer are pre-perforated before the facers have been adhered to the foam and wherein the foam body has an aged thermal conductivity of less than 0.02 W/m.K, the method comprising the steps of: leading the first or base facer to a lay down area; laying liquid phenolic foam ‘reactants down on the base facer; leading the second or upper facer over the foam reactants; leading the sandwich thus formed through an oven; and cutting the foam board thus formed to a desired length.

2. A method as claimed in claim I wherein the perforations are between 0.1mm and 1.5mm in diameter and are spaced from 3mm to 30mm apart.

3. A method as claimed in claim 1 or 2 wherein the first and/or second facer comprises a metallic foil.

4. A method as claimed in claim 3 wherein the first and/or second facer comprises an aluminium foil.

5. A method as claimed in any of claims 1 to 4 wherein the first and/or second facer is a laminate.

6. A method as claimed in claim 5 wherein the laminate comprises a metallic foil laminated onto a glass tissue. 12

7. A method as claimed in claim 5 wherein the laminate comprises a metallic foil laminated onto a Kraft paper.

8. A method for manufacturing a phenolic foam body as claimed in claim I substantially as 5 hereinbefore described.