IE84348B1

IE84348B1 - A phenolic foam

Info

Publication number: IE84348B1
Application number: IE2003/0957A
Authority: IE
Inventors: Mccabe Thomas; Morgan Edgerley Graham; Rochefort Malcolm
Original assignee: Kingspan Holding (Irl) Limited
Filing date: 2003-12-22
Publication date: 2006-09-20

Abstract

ABSTRACT A phenolic foam mixture for producing a substantially closed cell phenolic foam comprises a phenolic resin, 21 polysiloxane copolymer used as a surfactant, a blowing agent, and a catalyst (polymerization initiator), the polysiloxane copolymer having a polysiloxane content of from (25%) to (35%) by weight, a polyethylene oxide content of from (50%) to (55%) by weight and a polypropylene oxide content of from (15%) to (20%) by weight.

Description

" A PHENOLIC FOAM" Introduction The invention relates to a closed cell phenolic foam and to foam mixtures used in producing such foams.

Phenolic foams are widely used in building applications in view of their thermal insulation and fire resistant properties. Such phenolic foams are generally prepared by mixing a phenol formaldehyde resin with a blowing agent, a cell stabliliser and a hardener.

EP — A ~ 0170357 describes one such process for preparing a phenolic foam using Freon as a blowing agent, aqueous sulphuric acid as a hardener, and a cell stabiliser derived by oxylating castor oil with ethylene oxide or mixtures thereof with propylene oxide. Freon is a particular chlorofluorocarbon (CFC).

EP-A-0439283 describes the use of a complex blend of materials as an alternative blowing agent to a CFC. The blend comprises: at least one perfluoroalkane (PFA) (especially perfluoropentane, perfluorohexane or perfluoroheptane): and at least one component selected from a hydrogenated chlorofluorocarbon (HFC) and a specific alkane or cycloalkane.

US 4.530.939 describes a process for preparing a foam material wherein a phenol- aldehyde resole resin, a blowing agent and a surfactant are mixed with an acid catalyst to form an admixture which is poured into a forming means and cured. The resole resin is stripped using a solvent to reduce viscosity and water content. An unbranched dihydroxy either polyglycol is added to the stripped resole resin. The surfactant used in the process is an alkyl siloxane alkylene oxide block copolymer. The blowing agent is trichloromethane.

US 3,271,331 describes a mixture for use in producing a foamed phenol~aldehydc resole resin. The mixture comprises a phenol-aldehyde resole resin and a siloxane— oxyalkylene copolymer as a foam stabiliser for the foamed phenol-aldehyde resole resin. Crosslinking compounds and modifiers are also added to the mixture.

EP 0899291 describes a thermoplastic resin composition comprising a thermoplastic resin and a clay composite. The clay composite is prepared by introducing a silane compound into a swellable silicate.

There is a need for an improved phenolic foam which is easily processed and has good long term aged thermal conductivity properties.

Statements of Invention According to the invention there is provided a phenolic foam mixture for producing a substantially closed cell phenolic foam comprising a phenolic resin, a polysiloxane copolymer used as a surfactant. a blowing agent. and a catalyst (polymerization initiator), the polysiloxane copolymer having:— a polysiloxane content of from 25% to 35% by weight; a polyethylene oxide content of from 50% to 55% by weight; and a polypropylene oxide content of from 15% to 20% by weight.

The improved phenolic foam of the invention is easily processed and has good long term aged thennal conductivity properties. In the invention a polysiloxane cell stabiliser as defined is used at a low addition level.

In one embodiment of the invention the polysiloxane content of the surfactant is from 28% to 32% by weight.

The polyethylene oxide content of the surfactant is preferably from 51% to 55% by weight.

The polypropylene oxide content of the surfactant is preferably from 16% to 18% by weight.

In one embodiment the surfactant has a polysiloxane content of approximately 28% by weight. a polyethylene oxide content of approximately 55% by weight and a polypropylene oxide content of approximately 18% by weight.

In another embodiment the surfactant has a polysiloxane content of approximately % by weight, a polyethylene oxide content of approximately 53% by weight. and a polypropylene oxide content of approximately 17% by weight.

In a further embodiment the surfactant has a polysiloxane content of approximately 32% by weight, a polyethylene oxide content of approximately 51% by weight. and a polypropylene oxide content of approximately 16% by weight.

The surfactant may be present in an amount of at least 0.5 parts by weight of the mixture.

The invention also provides the use of a surfactant having:— a polysiloxane content of from 25% to 35% by weight; a polyethylene oxide content of from 50% to 55% by weight: and a polypropylene oxide content of from 15% to 20% by weight in the manufacture of a substantially closed cell phenolic insulating foam. The surfactant is preferably as defined above.

In another aspect the invention provides a phenolic insulating foam with a closed cell content of at least 90% prepared from the foam mixture of the invention.

Detailed Descmtion The invention will be more clearly understood from the following description thereof given by way of example.

The invention is based on the surprising finding that closed cell phenolic foams can be produced by using relatively small quantities of specific polysiloxane copolymers as surfactants.

Polysiloxane copolymers would not normally be considered as suitable components for closed cell phenolic foams. We have however, surprisingly found that certain polysiloxane copolymers can be effectively used as surfactants in producing closed cell phenolic foams.

We have found that not only is a highly closed cell foam produced using the polysiloxane copolymers but also the foam produced has an extremely favourable stable thermal conductivity profile, and can be used effectively at a lower level than castor-oil based surfactants.

The closed cell value may be measured by the method described in B.S. 4370/ASTM D2856. The foam of the invention has a closed cell content of greater than 90% when measured by this method.

The A (or k) value is measured as described in method 7A of B.S. 4370 part 2 with reference to BS3927. ASTM C177 is equivalent. The preferred foam of the invention has a A value at 30 days or longer of less than about 0.018 W/m.K. Even more surprisingly the thermal conductivity remains stable when tested at high temperatures of about 70°C over prolonged periods. which is the preferred temperature to accelerate A-ageing of foams in the European standard EN 13166.

Example 1: Foams were manufactured in the laboratory using the formulations below. The chemicals were mixed by means of a high speed laboratory stirrer and poured into an open topped mould, with an approximate volume of 1 litre. The mould was then placed in an oven at 55 °C for a minimum of 3 hours. The foam was then de—moulded and allowed to cool to ambient temperature before cutting and testing.

Foam: A Foam B Foam C Foam D Formulation (pbw) (pbw) (pbw) (pbw) Phenolic Resin 100 100 100/‘ 100 B1 ' t ‘*7’ Owmg age" 12 12 12 12 HCFC 141b/*Magex _ Surfactant *Niax L6915 4 F - - - Surfactant *Niax SR -355 — 4 /— - Surfactant *Niax Y10733 - Surfactant *Niax L691 0 — — - 4 Catalyst PSA/Phosphoric Acid 10 10 10 10 The surfactants used in the above examples are each polysiloxane copolymers available from OSi (Crompton Corporation).

N iax* L69l5 This is a polysiloxane copolymer having: - — a polysiloxane content of approximately 32% by weight — a polyethylene oxide content of approximately 51% by weight - a polypropylene oxide content of approximately 16% by weight N iax* SR-355 This is a polysiloxane copolymer having: — — a polysiloxane content of approximately 28% by weight — a polyethylene oxide content of approximately 55% by weight — a polypropylene oxide content of approximately 18% by weight Niax* Y10733 This is a polysiloxane copolymer having: - - a polysiloxane content of approximately 30% by weight - a polyethylene oxide content of approximately 53% by weight - a polypropylene oxide content of approximately 17% by weight Niax* L6910 This is a polysiloxane copolymer having: - - a polysiloxane content of approximately 48% by weight - a polyethylene oxide content of approximately 38% by weight — a polypropylene oxide content of approximately 13% by weight Thermal conductivity measurements were made on samples aged for various periods of time at 70 °C. The results are shown in the table below. It is clear that a rapid increase in thermal conductivity occurred in the case of Foam D, which was produced with a surfactant not having the claimed properties. Whereas foams A, B and C. which were produced with surfactants having the claimed properties. exhibited good thermal conductivity stability.

Number or days Lambda Values W/m.K @ 23.7 °C 7 aged at 70 °c ’EnTWﬁB‘ ‘ .0169 0.0156 .0174 0.0160 .0175 0.0162 Closed cell content 93.6% 94.8% * Indicates registered Trade Marks.

Example 2: Discontinuous block foam, was manufactured on a commercial scale plant to produce blocks of dimensions approximately 2500 x 1000 x 1000 mm. The foam mix was dispensed through a low pressure mixer into a heated mould. The product was put through a three hour curing cycle prior to de—mould. The foam was manufactured according to the following formulation.

Phenolic resin 100 pbw Blowing agent HCFC141b/Magex* 12 pbw Surfactant Y10773 2 pbw Colour KDS Black 0.3 pbw Catalyst PSA/Phosphoric Acid 10 pbw The density of the foam thus formed was 35 kg/m‘ and the foam of this example has excellent thermal conductivity stability as follows: Number of days aged at 70 °C 1 ’ 10 20 40 Thermal Conductivity W/m.K at 23.7 °C 0.0170 0.0174 0.0176 0.0179 Closed cell content as measured on a Micromeretics AccuPyc 1330 was 96.4%.

It is envisaged that the HCFC's used in the phenolic foam blowing agent blend of the invention may be selected, for example, from one or more of: HCFC 141b CCl2F-CH3 HCFC 142b CH3CClF2 HCFC 123 CF3-CHCI2 HCFC 124 CHClFg HCFC Z25ca CHCI2-CFg—CF3 HCFC 225cb CCIFZ-CF;-CHCIF It is also envisaged that the blowing agent blend may include a suitable hydrogenated fluorocarbon selected, for example, from one or more of: HFC 12.5 CHF3—CH3 HFC 134 a CF3CH2F HFC 152 a CH3—CHFz HF C 245fa CF}-CH2-CHF2 HFC 365mfc CF;-CH2-CFZ-CH3 The HF C’s may be represented by the formula CRHPFQ whenever: R is an integer from 1 to 4 P is an integer from 1 to 5 and Q = (2R+2)-P for an open chain HFC and (ZR-P) for a cyclic HF C.

It is further envisaged that the phenolic foam blowing agent blend may include an alkane. especially n—pentane and/or iso—pentane. and/or a cycloalkane, especially cyclo—pentane, or be purely alkane based.

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

Claims

1. A phenolic foam mixture for producing a substantially closed cell phenolic foam comprising a phenolic resin, a polysiloxane copolymer used as a surfactant, a blowing agent, and a catalyst (polymerization initiator), the polysiloxane copolymer having:- a polysiloxane content of from 25% to 35% by weight; a polyethylene oxide content of from 50% to 55% by weight; and a polypropylene oxide content of from 15% to 20% by weight.

2. A foam mixture as claimed in claim 1 wherein the polysiloxane content of the surfactant is from 28% to 32% by weight.

3. A foam mixture as claimed in claim 1 or 2 wherein the polyethylene oxide content of the surfactant is from 51% to 55% by weight.

4. A foam mixture as claimed in any of claims 1 to 3 wherein the polypropylene oxide content of the surfactant is from 16% to 18% by weight.

5. A foam mixture as claimed in any preceding claim wherein the surfactant has a polysiloxane content of approximately 28% by weight. a polyethylene oxide content of approximately 55% by weight and a polypropylene oxide content of approximately 18% by weight.

6. A foam mixture as claimed in any of claims 1 to 4 wherein the surfactant has a polysiloxane content of approximately 30% by weight, a polyethylene oxide content of approximately 53% by weight, and a polypropylene oxide content of approximately 17% by weight. A foam mixture as claimed in any of claims 1 to 4 wherein the surfactant has a polysiloxane content of approximately 32% by weight. a polyethylene oxide content of approximately 51% by weight, and a polypropylene oxide content of approximately 16% by weight. A foam mixture as claimed in any preceding claim wherein the surfactant is present in an amount of at least 0.5 parts by weight of the mixture. Use of a surfactant having:- a polysiloxane content of from 25% to 35% by weight; a polyethylene oxide content of from 50% to 55% by weight; and a polypropylene oxide content of from 15% to 20% by weight in the manufacture of a substantially closed cell phenolic insulating foam. Use as claimed in claim 9 wherein the surfactant is as defined in any of claims 2to

7. A phenolic insulating foam with a closed cell content of at least 90% prepared from the foam mixture as defined in any of the claims 1 to

8. A foam mixture substantially as hereinbefore described with reference to the foams A, B and C of the examples. Use of a surfactant substantially as hereinbefore described with reference to the foams A, B and C of the examples. A phenolic insulating foam substantially as hereinbefore described with reference to the foams A, B and C of the examples.