U.S. patent application number 11/991534 was filed with the patent office on 2010-01-14 for phenolic foam.
This patent application is currently assigned to KINGSPAN HOLDINGS (IRL) LIMITED. Invention is credited to Vincent Coppock, Toshiyuki Kato, Hiroo Takahashi, Rudd Zeggelaar.
Application Number | 20100010111 11/991534 |
Document ID | / |
Family ID | 35606581 |
Filed Date | 2010-01-14 |
United States Patent
Application |
20100010111 |
Kind Code |
A1 |
Coppock; Vincent ; et
al. |
January 14, 2010 |
Phenolic Foam
Abstract
A phenolic foam is made by foaming and curing a foamable
phenolic resin composition that comprises a phenolic resin, a
blowing agent, an acid catalyst and an inorganic filler. The
blowing agent comprises an aliphatic hydrocarbon containing from 1
to 8 carbon atoms and the inorganic filler is at least one selected
from a metal hydroxide, a metal oxide, a metal carbonate and a
metal powder. The phenolic foam has a pH of 5 or more. The phenolic
foam has a higher pH value compared with conventional phenolic foam
and reduces corrosion risk when in contact with metallic materials.
The phenolic foam maintains excellent long-term stable thermal
insulation performance, low water uptake and fire resistance
performance and by using a hydrocarbon blowing agent, does not harm
the environment as an ozone depleting or global warming
material.
Inventors: |
Coppock; Vincent; (Cheshire,
GB) ; Zeggelaar; Rudd; (Amhem, NL) ;
Takahashi; Hiroo; (Chiba Prefecture, JP) ; Kato;
Toshiyuki; (Saitama Perfecture, JP) |
Correspondence
Address: |
JACOBSON HOLMAN PLLC
400 SEVENTH STREET N.W., SUITE 600
WASHINGTON
DC
20004
US
|
Assignee: |
KINGSPAN HOLDINGS (IRL)
LIMITED
Kingscourt, County Cavan
IE
|
Family ID: |
35606581 |
Appl. No.: |
11/991534 |
Filed: |
September 8, 2006 |
PCT Filed: |
September 8, 2006 |
PCT NO: |
PCT/IE2006/000097 |
371 Date: |
September 2, 2009 |
Current U.S.
Class: |
521/181 |
Current CPC
Class: |
C08J 2361/06 20130101;
C08J 9/141 20130101; C08J 9/0066 20130101; C08L 71/08 20130101 |
Class at
Publication: |
521/181 |
International
Class: |
C08L 61/06 20060101
C08L061/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 2005 |
IE |
PCT/IE2005/000092 |
Claims
1-28. (canceled)
29. A phenolic foam made by foaming and curing a foamable phenolic
resin composition that comprises a phenolic resin, a blowing agent,
an acid catalyst and an inorganic filler characterised in that the
blowing agent comprises an aliphatic hydrocarbon containing from 1
to 8 carbon atoms, the inorganic filler is at least one selected
from a metal hydroxide, a metal oxide, a metal carbonate and a
metal powder and in that the phenolic foam has a pH of 5 or
more.
30. The phenolic foam as claimed in claim 29 wherein the phenolic
resin has a molar ratio of phenol groups to aldehyde groups in the
range 1:1 to 1:3.
31. The phenolic foam as claimed in claim 30 wherein the molar
ratio of phenol groups to aldehyde groups is from 1.5 to 2.3.
32. The phenolic foam as claimed in claim 29 wherein the phenolic
resin has a weight average molecular weight of from 400 to
3,000.
33. The phenolic foam as claimed in claim 32 wherein the phenolic
resin has a weight average molecular weight of from 700 to
2,000.
34. The phenolic foam as claimed in claim 29 wherein the aliphatic
hydrocarbon blowing agent comprises 1 to 20 parts by weight per 100
parts by weight of phenolic resin.
35. The phenolic foam as claimed in claim 29 wherein the blowing
agent comprises at least one of butane, pentane, hexane, heptane
and isomers thereof.
36. The phenolic foam as claimed in claim 29 wherein the blowing
agent comprises cyclopentane and at least one hydrocarbon of
isobutane and isopentane
37. The phenolic foam as claimed in claim 36 wherein the blowing
agent comprises 75% or more of cyclopentane.
38. The phenolic foam as claimed in claim 36 wherein the blowing
agent comprises 25% or less of at least one hydrocarbon of
isobutane and isopentane.
39. The phenolic foam as claimed in claim 29 wherein the acid
catalyst comprises 5 to 25 parts by weight per 100 parts by weight
of phenolic resin and wherein the acid catalyst comprises at least
one of benzenesulphonic acid, para-toluenesulphonic acid,
xylenesulphonic, naphthalenesulphonic acid, ethylbenzenesulphonic
acid and phenolsulphonic acid.
40. The phenolic foam as claimed in claim 29 wherein the inorganic
filler is present in an amount of from 1 to 20 parts by weight per
100 parts by weight of phenolic resin and wherein the filler
comprises at least one of a metal oxide such as aluminum oxide or
zinc oxide, a metal powder such as zinc, or a metal hydroxide such
as aluminium hydroxide, magnesium hydroxide, or a metal carbonate
such as calcium carbonate, magnesium carbonate, barium carbonate,
zinc carbonate.
41. The phenolic foam as claimed in claim 29 wherein the filler
comprises a metal hydroxide or metal carbonate with a Ksp less than
10-8
42. The phenolic foam as claimed in claim 29 wherein the filler
comprises a metal carbonate such as calcium carbonate, barium
carbonate, zinc carbonate.
43. The phenolic foam as claimed in claim 29 wherein the filler
comprises calcium carbonate.
44. The phenolic foam as claimed in claim 29 comprising a
plasticiser for the phenolic resin, wherein the plasticiser
comprises 0.1 to 20 parts by weight per 100 parts by weight of
phenolic resin and wherein the plasticiser comprises a polyester
polyol that is the reaction product of a polybasic carboxylic acid
selected from a dibasic to a tetrabasic carboxylic acid with a
polyhydric alcohol selected from a dihydric to a pentahydric
alcohol.
45. The phenolic foam as claimed in claim 44 wherein the polyester
polyol has a number average molecular weight of 250 to 350 and a
weight average molecular weight of 400 to 550.
46. The phenolic foam as claimed in claim 44 wherein the polybasic
carboxylic acid used to synthesise the polyester polyol comprises
at least one of phthalic acid, isophthalic acid, terephthalic acid,
naphthalene-2,3-dicarboxylic acid, naphthalene-1,4-dicarboxylic
acid, napththalene-2,6-dicarboxylic acid, adipic acid, pimeric
acid, suberic acid, azelaic acid, sebacic acid,
cyclohexane-1,2-dicarboxylic acid, cyclohexane-1,3-dicarboxylic
acid, and cyclohexane-1,4-dicarboxylic acid, preferably the
polybasic carboxylic acid used to synthesise the polyester polyol
comprises one or more of phthalic acid, isophthalic acid, or
terephthalic acid.
47. The phenolic foam as claimed in claim 44 wherein the polyhydric
alcohol used to synthesise the polyester polyol comprises at least
one of ethylene glycol, diethylene glycol, propylene glycol,
dipropylene glycol, 1,4-butane diol, 1,5-pentane diol, 1,6-hexane
diol, neopentyl glycol, 1,2-cyclohexane dimethanol, 1,3-cyclohexane
dimethanol, and 1,4-cyclohexane dimethanol.
48. The phenolic foam as claimed in claim 47 wherein the polyhydric
alcohol used to synthesise the polyester polyol comprises one or
more of diethylene glycol, propylene glycol, dipropylene glycol,
1,4-butane diol.
49. The phenolic foam as claimed in claim 29 comprising a
surfactant for the phenolic resin, wherein the surfactant comprises
1 to 6 parts by weight per 100 parts by weight of phenolic
resin.
50. The phenolic foam as claimed in claim 49 wherein the surfactant
is a castor oil-ethylene oxide adduct wherein more than 20 moles
but less than 40 moles of ethylene oxide are added per 1 mole of
castor oil.
51. The phenolic foam as claimed in claim 29 comprising an organic
modifier for co-reacting with the phenolic resin and wherein the
modifier comprises 1 to 10 parts by weight of a compound having an
amino group per 100 parts by weight of phenolic resin.
52. The phenolic foam as claimed in claim 51 wherein at least one
amino group containing compound is selected from urea,
dicyandiamide and melamine.
53. The phenolic foam as claimed in claim 29 having an aged thermal
conductivity of 0.025 W/m.K or less (measured at 23 oC), wherein
the density of the phenolic foam is from 10 to 100 kg/m3, wherein
the density of the phenolic foam is from 10 to 45 kg/m.sup.3 and
having a closed cell content of 85% or more, and having a limiting
oxygen index of 30% or more, and having a moisture uptake of less
than 0.9 kg/m.sup.2.
54. The phenolic foam as claimed in claim 29 having a closed cell
content of 90% or more.
55. The phenolic foam as claimed in claim 29 having a moisture
uptake of less than 0.8 kg/m.sup.2.
56. The phenolic foam as claimed in claim 29 having a facing on at
least one surface thereof and wherein the facing comprises at least
one of glass fibre-non woven fabric, spun bonded-non woven fabric,
aluminum foil, bonded-non woven fabric, metal sheet, metal foil,
ply wood, calcium silicate-board, plaster board, Kraft or other
paper product, and wooden board.
Description
[0001] Phenolic foam is used in insulation applications for
construction materials because of its superior thermal insulation
and fire resistance characteristics.
[0002] It is known that the thermal conductivity of polymeric
thermal insulation materials including phenolic foam can change
with time. This phenomenon is caused by the gradual diffusion out
of gas from inside the foam cells. The gas present inside the foam
cells is the blowing agent used in the foaming process. The gas in
the foam cells is slowly replaced by air from the atmosphere. As a
result, the thermal conductivity of phenolic foam can increase with
time.
[0003] It is highly desirable to achieve long-term stability for
the thermal insulation performance of phenolic foam products. It is
believed that one of the causes for the degradation of thermal
insulation performance is the reduction in the flexibility of the
cell walls of phenolic foam with time. Therefore, an object of the
present invention is to impart flexibility to the cell walls and
thereby maintain closed cell structure in the phenolic foam. Stable
closed cell structure provides a means for maintaining stable
thermal conductivity for the phenolic foam over an extended time
period.
[0004] As phenolic foam contains an acid catalyst, upon exposure to
water such as rain, the acid catalyst may be extracted from the
phenolic foam by such water. This could cause a problem when
metallic materials are in contact with the phenolic foam, as metals
could be susceptible to corrosion.
[0005] Accordingly, an object of the invention is to provide
phenolic foam that has excellent thermal insulation performance,
yet also has a higher pH value when compared to conventional
phenolic foam. Such a phenolic foam when in contact with metal
would have significantly reduced potential to induce metallic
corrosion.
[0006] It is a further objective to use a blowing agent that does
not harm the environment.
STATEMENTS OF INVENTION
[0007] According to the invention there is provided a phenolic foam
made by foaming and curing a foamable phenolic resin composition
that comprises a phenolic resin, a blowing agent, an acid catalyst
and an inorganic filler characterised in that the blowing agent
comprises an aliphatic hydrocarbon containing from 1 to 8 carbon
atoms, the inorganic filler is at least one selected from a metal
hydroxide, a metal oxide, a metal carbonate and a metal powder and
in that the phenolic foam has a pH of 5 or more.
[0008] In one embodiment the phenolic resin has a molar ratio of
phenol groups to aldehyde groups in the range 1:1 to 1:3,
preferably from 1.5 to 2.3.
[0009] In one embodiment the phenolic resin has a weight average
molecular weight of from 400 to 3,000, preferably from 700 to
2,000.
[0010] In one embodiment the aliphatic hydrocarbon blowing agent
comprises 1 to 20 parts by weight per 100 parts by weight of
phenolic resin.
[0011] The blowing agent may comprise at least one of butane,
pentane, hexane, heptane and isomers thereof. The blowing agent may
comprise cyclopentane and at least one hydrocarbon of isobutane
and, isopentane. In one case the blowing agent comprises 75% or
more of cyclopentane. The blowing agent may comprise 25% or less of
at least one hydrocarbon of isobutane and isopentane.
[0012] In one embodiment the acid catalyst comprises 5 to 25 parts
by weight per 100 parts by weight of phenolic resin. The acid
catalyst may comprise at least one of benzenesulphonic acid,
para-toluenesulphonic acid, xylenesulphonic, naphthalenesulphonic
acid, ethylbenzenesulphonic acid and phenolsulphonic acid.
[0013] In one embodiment the inorganic filler is present in an
amount of from 1 to 20 parts by weight per 100 parts by weight of
phenolic resin.
[0014] In one embodiment the filler comprises at least one of a
metal oxide such as aluminium oxide or zinc oxide, a metal powder
such as zinc, or a metal hydroxide such as aluminium hydroxide,
magnesium hydroxide, or a metal carbonate such as calcium
carbonate, magnesium carbonate, barium carbonate, zinc carbonate.
Preferably the filler may comprise at least one of a metal
hydroxide such as aluminium hydroxide, magnesium hydroxide, or a
metal carbonate such as calcium carbonate, magnesium carbonate,
barium carbonate, zinc carbonate with an ionic Equilibrium
Solubility Constant , (Ksp) lower than 10.sup.-8 measured at
25.degree. C.
[0015] In a preferred embodiment the filler comprises a metal
carbonate such as calcium carbonate, barium carbonate, or zinc
carbonate. Foams of particularly good quality have been produced
using calcium carbonate as the sole filler.
[0016] In one embodiment the foam comprises a plasticiser for the
phenolic resin. The plasticiser may comprise 0.1 to 20 parts by
weight per 100 parts by weight of phenolic resin. The plasticiser
may comprise a polyester polyol that is the reaction product of a
polybasic carboxylic acid selected from a dibasic to a tetrabasic
carboxylic acid with a polyhydric alcohol selected from a dihydric
to a pentahydric alcohol. Preferably the polyester polyol has a
number average molecular weight of 250 to 350 and a weight average
molecular weight of 400 to 550.
[0017] One embodiment the polybasic carboxylic acid used to
synthesise the polyester polyol comprises at least one of phthalic
acid, isophthalic acid, terephthalic acid,
naphthalene-2,3-dicarboxylic acid, naphthalene-1,4-dicarboxylic
acid, napththalene-2,6-dicarboxylic acid, adipic acid, pimeric
acid, suberic acid, azelaic acid, sebacic acid,
cyclohexane-1,2-dicarboxylic acid, cyclohexane-1,3-dicarboxylic
acid, and cyclohexane-1,4-dicarboxylic acid. Preferably, the
polybasic carboxylic acid used to synthesise the polyester polyol
comprises one or more of phthalic acid, isophthalic acid, or
terephthalic acid.
[0018] In one embodiment the polyhydric alcohol used to synthesise
the polyester polyol comprises at least one of ethylene glycol,
diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butane
diol, 1,5-pentane diol, 1,6-hexane diol, neopentyl glycol,
1,2-cyclohexane dimethanol, 1,3-cyclohexane dimethanol, and
1,4-cyclohexane dimethanol. Preferably, the polyhydric alcohol used
to synthesise the polyester polyol comprises one or more of
diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butane
diol.
[0019] The phenolic foam of the invention may comprise a surfactant
for the phenolic resin.
[0020] The surfactant may comprise 1 to 6 parts by weight per 100
parts by weight of phenolic resin.
[0021] The surfactant may be a castor oil-ethylene oxide adduct
wherein more than 20 moles but less than 40 moles of ethylene oxide
are added per 1 mole of castor oil.
[0022] In another embodiment the foam comprises an organic modifier
for co-reacting with the phenolic resin. The modifier may comprise
1 to 10 parts by weight of a compound having an amino group per 100
parts by weight of phenolic resin. In one case at least one amino
group containing compound is selected from urea, dicyandiamide and
melamine.
[0023] The phenolic foam has an aged thermal conductivity of 0.025
W/m.K or less when measured at a mean temperature of 10.degree. C.
after heat ageing for 175.+-.5 days at 70.+-.2.degree. C., in
accordance with the procedure as specified in European Standard
EN13166:2001, Annex C, section C.4.2.3.
[0024] The phenolic foam may have a density of from 10 to 100,
preferably, from 10 to 45 kg/m.sup.3.
[0025] The phenolic foam may have a closed cell content of 85% or
more, and a limiting oxygen index of 30% or more.
[0026] In a preferred embodiment the foam has a moisture uptake of
less than 0.9 kg/m.sup.2, most preferably a moisture uptake of less
than 0.8 kg/m.sup.2.
[0027] In one embodiment the phenolic foam has a facing on at least
one surface thereof.
[0028] The facing may comprise at least one of glass fibre-non
woven fabric, spun bonded-non woven fabric, aluminum foil,
bonded-non woven fabric, metal sheet, metal foil, ply wood, calcium
silicate-board, plaster board, Kraft or other paper product, and
wooden board.
DETAILED DESCRIPTION
[0029] The invention will be more clearly understood from the
following description thereof given by way of example only.
[0030] The phenolic foam comprises phenolic resin, hydrocarbon
blowing agent, an acid catalyst and an inorganic filler to regulate
foam pH. The invention provides phenolic foam with a higher pH
value than is currently typical of commercially available phenolic
foam products. The higher pH helps prevent metallic materials from
corroding when they are in prolonged contact with phenolic
foam.
[0031] A preferred type of phenolic resin to use in the present
invention is a resole resin. This resole resin can be obtained from
the chemical reaction of phenol or a phenol based compound such as
cresol, xylenol, para-alkylphenol, para-phenylphenol, resorcinol,
and the like with an aldehyde such as formaldehyde, furfural,
acetaldehyde and the like under a catalytic amount of alkali such
as sodium hydroxide, potassium hydroxide, calcium hydroxide, or an
aliphatic amine like trimethylamine, or triethylamine. These types
of chemical constituent are commonly used in standard resole resin
production, but the invention is not limited to just those
chemicals listed here.
[0032] The molar ratio of phenol groups to aldehyde groups is not
especially limited. It is preferred that the molar ratio of phenol
to aldehyde is in the range from 1:1 to 1:3, more preferably from
1:1.5 to 1:2.5, and particularly preferable is 1:1.6 to 1:2.1.
[0033] A preferred weight average molecular weight suitable for the
phenolic resin used in the invention is from 400 to 3,000, and more
preferably from 700 to 2,000. The number average molecular weight
is preferably from 150 to 1,000, and more preferably from 300 to
700.
[0034] An aliphatic hydrocarbon or mixtures of aliphatic
hydrocarbons having from 1 to 8 carbon atoms is employed as the
blowing agent in the present invention. It includes normal chain or
branched chain aliphatic hydrocarbons. Examples include butane,
pentane, hexane, heptane and their isomers. Hydrocarbons have low
potential for global warming and do not deplete the ozone layer of
the Earth.
[0035] The amount of the blowing agent used in the present
invention is from 1 to 20 parts by weight relative to 100 parts by
weight of phenolic resin, more preferably from 5 to 10 parts by
weight per 100 parts by weight of phenolic resin.
[0036] The addition of inorganic filler to the phenolic foam of the
present invention reduces residual acidity, and can improve fire
performance whilst still maintaining low thermal conductivity.
[0037] The amount of inorganic filler used is preferably from 0.1
to 30 parts by weight, and more preferably, from 1 to 10 parts by
weight relative to 100 parts by weight of phenolic resin. The
fillers that can be added include metal hydroxides such as
aluminium hydroxide, magnesium hydroxide; metal carbonates such as
calcium carbonate, magnesium carbonate, barium carbonate, zinc
carbonate and so on; with an ionic Equilibrium Solubility Constant,
(Ksp), of less than 10.sup.-8. The filler of the present invention
may be used either alone or in combination with one or more other
fillers.
[0038] The use of an organic amino group containing compound, such
as urea, in the foam of the present invention, can lower thermal
conductivity, increase strength and reduce friability of the
phenolic foam. A preferred amount of urea to be used in the present
invention is in the range from 1 to 10 parts by weight, preferably,
from 3 to 7 parts by weight relative to 100 parts by weight of the
phenolic resin.
[0039] For the acid catalyst used to initiate polymerisation of the
phenolic resin in the invention, individual or blends of strong
organic acids such as benzene sulphonic acid, para toluene
sulphonic acid, xylene sulfonic acid, ethyl benzene sulphonic acid,
naphthalene sulphonic acid, phenol sulphonic acid, and the like are
used. Phenol sulphonic acid, para toluene sulphonic acid, and
xylene sulphonic acid are particularly preferred. An inorganic acid
such as sulphuric acid, phosphoric acid and the like, may be
optionally used with the said organic acids.
[0040] The amount of acid used to initiate polymerisation of the
phenolic resin varies with the type of acid selected, but is
usually in a range from 5 to 25 parts by weight, and more
preferably from 7 to 22 parts by weight relative to 100 parts by
weight of phenolic resin. The most preferable amount of acid to use
is from 10 to 20 parts by weight of phenolic resin.
[0041] The phenolic resin used herein contains a surfactant to aid
foam manufacture. The surfactant used is a castor oil-ethylene
oxide adduct wherein more than 20 moles but less than 40 moles of
ethylene oxide are added per mole of castor oil. The weight
addition of the castor oil-EO adduct relative to 100 parts by
weight of phenolic resin is preferably from 1 to 5 parts by weight,
and more preferably from 2 to 4 parts by weight. If the content of
the castor oil-EO adduct is less than 1 part by weight, uniform
foam cells cannot be obtained. On the other hand, if more than 5
parts by weight of the castor oil-EO adduct is used, product cost
and the water-absorption capacity of the foam is increased.
[0042] In accordance with the present invention, there is provided
a plasticiser for the phenolic foam. A polyester polyol is the
preferred plasticiser. The plasticiser imparts flexibility to the
cell walls of the phenolic foam, inhibits their degradation over
time, and improves long term thermal insulation stability. The
plasticiser of the present invention is a polyester polyol that is
obtained from the reaction of a polybasic carboxylic acid with a
polyhydric alcohol. In terms of imparting flexibility to the
cell-walls of phenolic foam, the molecular weight of the
plasticiser is not especially limited. However, a polyester polyol
having a weight average molecular weight from 200 to 10,000, and
particularly from 400 to 550, is preferred.
[0043] The polyhydric alcohol used preferably has at least two
hydroxyl groups in a molecule. The number of hydroxyl groups in a
molecule of the polyhydric alcohol used is at least more than
1.
[0044] The number of carboxyl groups in a molecule of the said
polybasic carboxylic acid is at least more than 1.
[0045] The polyester polyol of the present invention is for
example, the reaction product of a polybasic carboxylic acid
selected from a dibasic to a tetrabasic carboxylic acid with a
polyhydric alcohol selected from a dihydric to a pentahydric
alcohol. A product expressed in the Formula (I) below is
preferable, wherein A is a dicarboxylic acid residue originally
containing up to two hydrogen atoms from a dibasic carboxylic acid,
and R is a chemical backbone of a dihydric alcohol originally
containing up to two hydroxyl groups from a dihydric alcohol, and n
is an integer equal to or more than 1.
##STR00001##
[0046] In the general formula (1), a preferred dibasic carboxylic
acid forming the residue A is either an aromatic dicarboxylic acid,
an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid.
These carboxylic acids preferably include phthalic acid,
isophthalic acid, terephthalic acid, naphthalene-2,3-dicarboxylic
acid, naphthalene-1,4-dicarboxylic acid,
napththalene-2,6-dicarboxylic acid, adipic acid, pimeric acid,
suberic acid, azelaic acid, sebacic acid,
cyclohexane-1,2-dicarboxylic acid, cyclohexane-1,3-dicarboxylic
acid, cyclohexane-1,4-dicarboxylic acid and the like.
[0047] The dihydric alcohol forming chemical backbone R is an
aromatic glycol, an aliphatic glycol or an alicyclic glycol which
preferably includes ethylene glycol, diethylene glycol, propylene
glycol, dipropylene glycol, 1,4-butane diol, 1,5-pentane diol,
1,6-hexane diol, neopentyl glycol, 1,2-cyclohexane dimethanol,
1,3-cyclohexane dimethanol, and 1,4-cyclohexane dimethanol,
cyclopentane-1,2-diol, cyclepentane-1, 2-dimethanol,
cyclohexane-1,2-diol, cyclohexane-1,3-diol, cyclohexane-1,4-diol,
cyclopentane-1,4-dimethanol,2,5-norbomane diol and the like.
[0048] Aliphatic glycols and alicyclic glycols are especially
preferable. A reaction product so obtained is a mixture in which
"n" is composed of various values and the hydroxyl value of these
reaction products is usually included in a range of from 10 to 500
mg-KOH/g.
[0049] Since the plasticiser for the phenolic foam in the present
invention has a molecular structure containing both an ester
backbone and a hydroxyl group, it is hydrophilic as is the phenolic
resin. Therefore the phenolic resin and the plasticiser are
compatible and so together can form a homogeneous resin solution.
Furthermore, it is presumed that when the said polyester polyol, is
added to a foamable phenolic resin composition, the polyester
polyol imparts flexibility to the cell-walls of the phenolic foam.
Therefore, even after extensive ageing, degradation phenomenon such
as a crack-occurrence at the cell-walls is controlled. This leads
to long-term stability for the thermal conductivity of the phenolic
foam.
[0050] The phenolic foam of the present invention has an aged
thermal conductivity below 0.025 W/m.K. Phenolic foam that has an
aged thermal conductivity more than 0.025 W/m.K is less efficient
in terms of thermal insulation performance.
[0051] The surface of the phenolic foam products of the present
invention may be covered with a facing material. Surface facing
materials include non-woven fabrics made of natural fibre,
synthetic fibre or inorganic fibre. Paper or kraft paper, aluminium
foil and so on can be used as facing material.
[0052] A process for producing phenolic foam of the invention with
a pH above 5.0 is described that uses a phenolic resin composition
that contains phenolic resin, an acid catalyst, hydrocarbon blowing
agent and an inorganic filler to raise the pH of the foam. The
phenolic resin used could also contain plasticiser, surfactant, and
a chemical compound having amino groups. The hydrocarbon blowing
agent and acid catalyst used are generally added to the phenolic
resin composition in a foam mixing head at the time of foam
manufacture.
[0053] As stated, to the resin composition used in producing
phenolic foam of the present invention, is added an amino group
containing compound. This is preferably urea that is mixed into the
phenolic resin at 18.degree. C. to 22.degree. C. for at least 1 to
5 hours prior to making foam. Alternatively an amino group
containing compound can be reacted with formaldehyde in the
presence of phenol during the manufacture of the phenolic
resin.
[0054] Castor oil-EO adduct surfactant, an inorganic filler such as
calcium carbonate powder with mean particle size 5 to 200 .mu.m,
and preferably, a polyester polyol plasticiser are also mixed into
the phenolic resin.
[0055] The phenolic resin composition obtained is pumped to a high
speed mixer head where it is introduced to and mixed in with
hydrocarbon blowing agent and an acid catalyst to prepare a
foamable phenolic composition.
[0056] According to the process for producing phenolic foam of the
present invention, the said foamable phenolic resin composition is
discharged on to a continuous running facing material carrier and
passed through a heated zone for foaming and moulding into phenolic
foam products of predetermined shape. In this manufacturing
process, the said resin composition that has been discharged on to
a running facing material carrier on a conveyor belt passes into a
heated oven typically at 50 to 100.degree. C. for approximately 2
to 15 minutes. The top surface of the rising foam composition is
pressed down with another facing material carried on an upper
conveyer 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.
[0057] The use of an aliphatic hydrocarbon blowing agent containing
from 1 to 8 carbon atoms is environmentally friendly but still
allows closed cell phenolic foam to be produced, thereby
maintaining thermal insulation performance. The phenolic foam in
the present invention comprises foaming and curing a foamable
phenolic resin composition comprising a phenolic resin, an acid
catalyst, hydrocarbon blowing agent and an inorganic filler.
[0058] In accordance with the present invention,
corrosion-resistant, phenolic foam is provided by using a an
aliphatic hydrocarbon blowing agent containing 1 to 8 carbon atoms,
and additionally controlling the amount of acid catalyst and adding
an inorganic filler such as calcium carbonate to the foam. The
phenolic foam produced has excellent fire resistance performance,
long-term thermal insulation performance stability, low water
uptake and a higher pH value than is normally obtained with
phenolic foam products. Further the blowing agent used has
favourable properties regarding global warming potential and ozone
depletion.
[0059] The invention described herein overcomes the potential
corrosion risk to metal in contact with phenolic foam by providing
a means of partially neutralising the residual acid in the phenolic
foam by using an inorganic filler.
[0060] The phenolic foam of the present invention has a pH of 5.0
or more. If the pH is 5.0 or more, the corrosion of metal can be
inhibited when in contact with or adjacent to the said phenolic
foam even when the metal is wet. A preferable pH for the phenolic
foam of the invention is 5.5 or more and especially preferable is
when pH is 6.0 or more. The method for the determination of pH is
described later.
[0061] The phenolic foam of the present invention has an aged
thermal conductivity of below 0.025 W/m.K. The aged thermal
conductivity is measured after exposing foam samples for 25 weeks
at 70.degree. C. and stabilisation to constant weight at 23.degree.
C. and 50% R.H. This thermal ageing serves to provide an estimated
thermal conductivity for a time period of 25 years at ambient
temperature. The thermal insulation performance of phenolic foam
with a thermal conductivity above 0.025 W/m.K is undesirable
regarding insulation performance.
[0062] The phenolic foam in the present invention has typically a
density of 10 to 45 kg/m.sup.3, and an average cell diameter of 5
to 400 .mu.m.
[0063] The phenolic foam of the present invention has substantially
no holes in the cell-walls.
[0064] The phenolic foam of the present invention has a closed cell
content of 90% or more, more preferably 92.5% or more.
[0065] The phenolic foam in the present invention has preferably an
oxygen index of 29 or more, and more preferably, 30 or more.
[0066] The long-term stability of the phenolic foam cells is
maintained because the phenolic foam cells of the present invention
have improved flexibility.
[0067] Suitable testing methods for measuring the physical
properties of phenolic foam are described below.
(1) Foam Density
[0068] This was measured according to EN 1602:Thermal insulating
products for building applications--Determination of the apparent
density
(2) Thermal Conductivity
[0069] A foam test piece of length 300 mm and width 300 mm was
placed between a high temperature plate at 20.degree. C. and a low
temperature plate at 0.degree. C. in a thermal conductivity test
instrument (LaserComp Type FOX314/ASF, Inventech Benelux BV). The
thermal conductivity (TC) of the test pieces was measured according
to EN12667:Thermal performance of building materials and
products--Determination of thermal resistance by means of guarded
hot plate and heat flow meter methods, Products of high and medium
thermal resistance.
(3) Thermal Conductivity After Accelerated Ageing
[0070] This was measured using EN 13166:Thermal insulation products
for buildings--Factory made products of phenolic foam
(PF)--Specification Annex C section.4.2.3. The thermal conductivity
is measured after exposing foam samples for 25 weeks at 70.degree.
C. and stabilisation to constant weight at 23.degree. C. and 50%
R.H. This thermal ageing serves to provide an estimated thermal
conductivity for a time period of 25 years at ambient
temperature.
(4) pH
[0071] 0.5 g of phenolic foam is pulverised to pass through a 250
.mu.m (60 mesh) sieve and is then put into a 200 ml-Erlenmeyer
flask. 200 ml of distilled water are added and the contents are
sealed with a stopper. After stirring at 23.+-.5 for 7 days with a
magnetic follower, the contents of the flask are tested for pH.
(5) Average Cell Diameter
[0072] A flat section of foam is obtained by slicing through the
middle section of the thickness of the foam board in a direction
running parallel to the top and bottom faces of a foam board. A
50-fold enlarged photocopy is taken of the cut cross section of the
foam. Four straight lines of length 9 cm are drawn on to the
photocopy. The number of cells present on every line is counted and
the average number cell number determined according to JIS K6402
test method. The average cell diameter is taken as 1800 .mu.m
divided by this average number.
(6) Voids
[0073] A flat section of foam is obtained by slicing through the
middle section of the thickness of the foam board in a direction
running parallel to the top and bottom faces. A 200-fold enlarged
photocopy is taken of this cut cross section of foam covering an
area 100 mm by 150 mm. A transparent graph paper is placed on top
of the photocopy of the cut foam section. The area of voids that
occupy 8 or more 1 mm by 1 mm squares of graph paper was added up
to calculate the voids area ratio. Eight squares is equivalent to 2
mm.sup.2 area of actual foam.
(7) Oxygen Index
[0074] The oxygen index at room temperature of phenol foam was
determined according to JIS K7201-2 test method.
(8) Closed Cell Ratio
[0075] The closed cell ratio was determined according to ASTM D2856
test method.
(9) Water Uptake
[0076] The water uptake was determined according to EN1609:1996
Thermal Insulating products for building
applications--Determination of short term water absorption by
partial immersion.
(10) Friability
[0077] Friability is measured according test method ASTM C
421-88.
[0078] The present invention is explained in detail by the Examples
and Comparative Examples that follow. The physical properties of
the phenolic foams obtained are shown in Table 1 below. However,
the invention is not limited only to these Examples and Comparative
Example.
EXAMPLES
[0079] The phenolic resole resin used in the invention is Resin A
and is described as follows.
[0080] Phenolic Resin A is a commercially available liquid Phenol
Formaldehyde resin supplied by Sumitomo Bakelite under the trade
name R300.
[0081] This resin has a viscosity of 8000-10000 cp at 25.degree.
C., weight average molecular weight 800 to 1200 and pH is 5.3 to
6.3.
[0082] R300 resin contains from 2% to 4% free phenol and 3% to 4%
free formaldehyde. R300 resin has a Phenol:Formaldehyde molar ratio
of 1:2.0 and has a water content of 11-13% (as measured by Karl
Fisher analysis). To the R300 Resin is also added 2 to 5%
surfactant, as has been described previously herein, The following
Example 1 shows how foam samples of the invention are made.
Example 1
[0083] 104 parts by weight (pbw) of Resin A at 20.degree. C. is
mixed with 5 pbw of powdered urea and 5 pbw of plasticiser. The
resin is allowed to stand for 1 hour at 20 C. Next is added 5.3 pbw
of calcium carbonate (Durcal 130 from Omya), with average particle
size 170 .mu.m. The resin is mixed at 300 rpm until calcium
carbonate is uniformly dispersed. Resin A, (containing urea and
calcium carbonate filler), is then cooled to between 17.degree. C.
and 21.degree. C. The said phenolic resin mixture is pumped to a
high speed peg mixer where 9 parts by weight of
cyclopentane/isopentane (85/15 by weight) is added as blowing
agent, and 20 parts by weight liquid para-toluene sulphonic
acid/xylene sulphonic acid blend (65/35 w/w) at 92% concentration
is added as catalyst. In the peg mixer, intimate mixing is achieved
to give a foamable phenolic resin composition. The resin
composition is discharged on to the lower non woven mat facing
material which is carried on a running conveyor into a foam
lamination machine. A top facing material is also introduced on to
the foaming resin composition. The running foam material is passed
through a curing oven press where the foam material is pressurised
at 40 to 50 kPa to achieve a predetermined thickness of 50 mm. The
blowing and curing of the foam material in the oven is carried out
at a temperature from 65 to 75.degree. C. for between 3 and 8
minutes. The phenolic foam that exits from the curing oven is cut
to a predetermined length.
[0084] The foam board is then post-cured in an oven for 12 hours at
80.degree. C. The foam board produced has an apparent density of
39.5 kg/m3.
Example 2
Here There is a Reduced Amount of Plasticiser (2.5 Parts Per Weight
Instead of 5 Parts Per Weight)
[0085] 104 parts by weight (pbw) of Resin A at 20.degree. C. is
mixed with 5 pbw of powdered urea and 2.5 pbw of plasticiser. The
resin is allowed to stand for 1 hour at 20 C. Next is added 5.3 pbw
of calcium carbonate, (Durcal 130 from Omya). The resin is mixed at
300 rpm until calcium carbonate is uniformly dispersed. Resin A,
(containing urea and calcium carbonate filler), is then cooled to
between 17.degree. C. and 21.degree. C. The said phenolic resin
mixture is pumped to a high speed peg mixer where 9 parts by weight
of cyclopentane/isopentane (85/15 by weight) is added as blowing
agent, and 20 parts by weight liquid para-toluene sulphonic
acid/xylene sulphonic acid blend (65/35 w/w) at 92% concentration
is added as catalyst. In the peg mixer, intimate mixing is achieved
to give a foamable phenolic resin composition. The resin
composition is discharged on to the lower non woven mat facing
material which is carried on a running conveyor into a foam
lamination machine. A top facing material is also introduced on to
the foaming resin composition. The running foam material is passed
through a curing oven press where the foam material is pressurised
at 40 to 50 kPa to achieve a predetermined thickness of 50 mm. The
blowing and curing of the foam material in the oven is carried out
at a temperature from 65 to 75.degree. C. for between 3 and 8
minutes. The phenolic foam that exits from the curing oven is cut
to a predetermined length.
[0086] The foam board is then post-cured in an oven for 12 hours at
80.degree. C. The foam board produced has an apparent density of
39.5 kg/m3.
Example 3
Here There is a Reduced Amount of Urea (2.5 Parts Per Weight
Instead of 5 Parts Per Weight)
[0087] 104 parts by weight (pbw) of Resin A at 20.degree. C. is
mixed with 2.5 pbw of powdered urea and 5 pbw of plasticiser. The
resin is allowed to stand for 1 hour at 20 C. Next is added 5.3 pbw
of calcium carbonate (Durcal 130 from Omya). The resin is mixed at
300 rpm until calcium carbonate is uniformly dispersed. Resin A,
(containing urea and calcium carbonate filler), is then cooled to
between 17.degree. C. and 21.degree. C. The said phenolic resin
mixture is pumped to a high speed peg mixer where 9 parts by weight
of cyclopentane/isopentane (85/15 by weight) is added as blowing
agent, and 20 parts by weight liquid para-toluene sulphonic
acid/xylene sulphonic acid blend (65/35 w/w) at 92% concentration
is added as catalyst. In the peg mixer, intimate mixing is achieved
to give a foamable phenolic resin composition. The resin
composition is discharged on to the lower non woven mat facing
material which is carried on a running conveyor into a foam
lamination machine. A top facing material is also introduced on to
the foaming resin composition. The running foam material is passed
through a curing oven press where the foam material is pressurised
at 40 to 50 kPa to achieve a predetermined thickness of 50 mm. The
blowing and curing of the foam material in the oven is carried out
at a temperature from 65 to 75 .degree. C. for between 3 and 8
minutes. The phenolic foam that exits from the curing oven is cut
to a predetermined length.
[0088] The foam board is then post-cured in an oven for 12 hours at
80.degree. C. The foam board produced has an apparent density of
39.5 kg/m3.
Comparative Example 1
[0089] The following comparative example describes the manufacture
of a foam without calcium carbonate filler.
[0090] 104 parts by weight (pbw) of Resin A at 20.degree. C. is
mixed with 5 pbw of powdered urea and 5 pbw of plasticiser. The
resin is allowed to stand for 1 hour at 20 C. Resin A containing
urea is then cooled to between 17.degree. C. and 21.degree. C. The
said phenolic resin mixture was pumped to a high speed peg mixer
where 9 parts by weight of cyclopentane/isopentane (85/15 by
weight) is added as blowing agent, and 20 parts by weight liquid
para-toluene sulphonic acid/xylene sulphonic acid blend (65/35 w/w)
at 92% concentration is added as catalyst. In the peg mixer,
intimate mixing is achieved to give a foamable phenolic resin
composition. The resin composition is discharged on to the lower
non woven mat facing material which is carried on a running
conveyor into a foam lamination machine. A top facing material is
also introduced on to the foaming resin composition. The running
foam material is passed through a curing oven press where the foam
material is pressurised at 40 to 50 kPa to achieve a predetermined
thickness of 50 mm. The blowing and curing of the foam material in
the oven is carried out at a temperature from 65 to 75 .degree. C.
for between 3 and 8 minutes. The phenolic foam that exits from the
curing oven is cut to a predetermined length.
[0091] The foam board is then post-cured in an oven for 12 hours at
80.degree. C. The foam board produced has an apparent density of
39.5 kg/m3.
[0092] Comparative Example 1 demonstrates that a good quality
phenolic insulation foam can be produced without the filler
present, but the resulting foam shows a pH<5.0 and a water
uptake >1.0 kg/m.sup.2 when tested to test methods (4) and (9)
as given above (see Table 1)
Comparative Example 2
[0093] The following comparative example describes the manufacture
of a foam with magnesium carbonate filler.
[0094] 104 parts by weight (pbw) of Resin A at 20.degree. C. is
mixed with 5 pbw of powdered urea and 5 pbw of plasticiser. The
resin is allowed to stand for 1 hour at 20C. Next is added 5.3 pbw
of magnesium carbonate. (Sigma Aldrich product M7179), The resin is
mixed at 300 rpm until magnesium carbonate is uniformly dispersed.
Resin A, (containing urea and magnesium carbonate filler), is then
cooled to between 17.degree. C. and 21.degree. C. The said phenolic
resin mixture was pumped to a high speed peg mixer where 9 parts by
weight of cyclopentane/isopentane (85/15 by weight) is added as
blowing agent, and 20 parts by weight liquid para-toluene sulphonic
acid/xylene sulphonic acid blend (65/35 w/w) at 92% concentration
is added as catalyst. In the peg mixer, intimate mixing is achieved
to give a foamable phenolic resin composition. The resin
composition is discharged on to the lower non woven mat facing
material which is carried on a running conveyor into a foam
lamination machine. A top facing material is also introduced on to
the foaming resin composition. The running foam material is passed
through a curing oven press where the foam material is pressurised
at 40 to 50 kPa to achieve a predetermined thickness of 50 mm. The
blowing and curing of the foam material in the oven is carried out
at a temperature from 65 to 75.degree. C. for between 3 and 8
minutes. The phenolic foam that exits from the curing oven is cut
to a predetermined length.
[0095] The foam board is then post-cured in an oven for 12 hours at
80.degree. C. The foam board produced has an apparent density of
39.5 kg/m3.
[0096] Comparative Example 2 demonstrates that use of a filler with
a high solubility parameter (Ksp>1.times.10.sup.-8) can produce
a foam, but the resulting foam shows a water uptake >1.0
kg/m.sup.2 when tested to test method (9), and poorer foam
structure caused by reaction of the filler with the acid catalyst
which results in higher thermal conductivity (see Table 1).
Comparative Example 3
[0097] The following comparative example describes the manufacture
of a foam without plasticiser.
[0098] 104 parts by weight (pbw) of Resin A at 20.degree. C. is
mixed with 5 pbw of powdered urea. The resin is allowed to stand
for 1 hour at 20C. Next is added 5.3 pbw of calcium carbonate
(Durcal 130 from Omya). The resin is mixed at 300 rpm until calcium
carbonate is uniformly dispersed. Resin A, (containing urea and
calcium carbonate filler), is then cooled to between 17.degree. C.
and 21.degree. C. The said phenolic resin mixture was pumped to a
high speed peg mixer where 9 parts by weight of
cyclopentane/isopentane (85/15 by weight) is added as blowing
agent, and 20 parts by weight liquid para-toluene sulphonic
acid/xylene sulphonic acid blend (65/35 w/w) at 92% concentration
is added as catalyst. In the peg mixer, intimate mixing is achieved
to give a foamable phenolic resin composition. The resin
composition is discharged on to the lower non woven mat facing
material which is carried on a running conveyor into a foam
lamination machine. A top facing material is also introduced on to
the foaming resin composition. The running foam material is passed
through a curing oven press where the foam material is pressurised
at 40 to 50 kPa to achieve a predetermined thickness of 50 mm. The
blowing and curing of the foam material in the oven is carried out
at a temperature from 65 to 75.degree. C. for between 3 and 8
minutes. The phenolic foam that exits from the curing oven is cut
to a predetermined length.
[0099] The foam board is then post-cured in an oven for 12 hours at
80.degree. C. The foam board produced has an apparent density of
39.5 kg/m3.
[0100] Comparative Example 3 demonstrates that the absence of
plasticiser results in a foam with poorer cell structure which
results in higher aged thermal conductivity performance (see Table
1).
Comparative Example 4
[0101] The following comparative example describes the manufacture
of a foam without urea.
[0102] 104 parts by weight (pbw) of Resin A at 20.degree. C. is
mixed with 5 pbw of plasticiser. The resin is allowed to stand for
1 hour at 20 C. Next is added 5.3 pbw of calcium carbonate (Durcal
130 from Omya). The resin is mixed at 300 rpm until calcium
carbonate is uniformly dispersed. Resin A, (containing calcium
carbonate filler), is then cooled to between 17.degree. C. and
21.degree. C. The said phenolic resin mixture was pumped to a high
speed peg mixer where 9 parts by weight of cyclopentane/isopentane
(85/15 by weight) is added as blowing agent, and 20 parts by weight
liquid para-toluene sulphonic acid/xylene sulphonic acid blend
(65/35 w/w) at 92% concentration is added as catalyst. In the peg
mixer, intimate mixing is achieved to give a foamable phenolic
resin composition. The resin composition is discharged on to the
lower non woven mat facing material which is carried on a running
conveyor into a foam lamination machine. A top facing material is
also introduced on to the foaming resin composition. The running
foam material is passed through a curing oven press where the foam
material is pressurised at 40 to 50 kPa to achieve a predetermined
thickness of 50 mm. The blowing and curing of the foam material in
the oven is carried out at a temperature from 65 to 75.degree. C.
for between 3 and 8 minutes. The phenolic foam that exits from the
curing oven is cut to a predetermined length.
[0103] The foam board is then post-cured in an oven for 12 hours at
80.degree. C. The foam board produced has an apparent density of
39.5 kg/m3.
[0104] Comparative Example 4 demonstrates that the absence of urea
results in a foam with poorer cell structure which results in
higher aged thermal conductivity performance (see Table 1).
[0105] Foam samples from the Examples and Comparative Examples are
thermally aged at 70.degree. C. for 25 weeks. After the ageing
these samples are conditioned to constant weight at 23.degree. C.
and 50% RH. This thermal ageing simulates the expected changes in
thermal conductivity that may be expected after 25 years at ambient
conditions. This is a standard ageing period for assessing foam
products for insulation applications.
TABLE-US-00001 TABLE 1 Thermal Conductivity After Thermal 25 weeks
at 70.degree. C. + Average Closed Conductivity 5 weeks at
23.degree. C. Cell Oxygen Water Cell Density (W/m K and 50% RH
Diameter Voids Index uptake Friability Ratio (kg/m.sup.3) at
10.degree. C.) (W/m K at 10.degree. C.) pH (.mu.m) (%) (%)
(kg/m.sup.2) (%) (%) Ex 1 39.5 0.02141 0.02291 5.5 50 0.50 33.0
0.82 26 91 Ex 2 38.8 0.02196 0.02306 6.1 65 0.62 31.0 0.75 29 92 Ex
3 39.4 0.02181 0.02459 5.8 53 0.59 32.0 0.61 25 92 C. Ex. 1 39.9
0.02160 0.02239 2.7 50 0.50 32.0 1.33 22 92 C. Ex. 2 38.7 0.02873
0.02873 5.7 64 0.55 31.0 1.05 28 91 C. Ex. 3 38.9 0.02901 0.02901
5.9 55 0.67 33.0 0.85 30 91 C. Ex. 4 39.1 0.03123 0.03123 5.6 60
0.80 32.0 0.90 32 90
[0106] The foam sample from Comparative Example 2 where magnesium
carbonate has been used results in an acceptable pH value. The
water uptake of the foam sample with magnesium carbonate however is
higher compared to the water uptake of the foam sample with calcium
carbonate.
TABLE-US-00002 Compound Formula K.sub.SP (at 25.degree. C.) lithium
carbonate Li.sub.2CO.sub.3 2.5*10.sup.-4 magnesium carbonate
MgCO.sub.3 3.8*10.sup.-8 calcium carbonate (calcite) CaCO.sub.3
3.8*10.sup.-9 barium carbonate BaCO.sub.3 5.1*10.sup.-9
[0107] Ionic compounds normally dissociate into their constituent
ions when they dissolve in water. For example calcium
carbonate:
CaCO.sub.3(s).revreaction.Ca.sup.2+(aq)+CO.sub.3.sup.2-(aq)
[0108] The equilibrium expression is:
K c = [ Ca 2 + ( aq ) ] [ CO 3 2 - ( aq ) ] { CaCO 3 ( s ) }
##EQU00001##
[0109] Where Kc is called the equilibrium constant (or solubility
constant, the square brackets mean molar concentration (M, or
mol/L), and curly brackets mean activity. Since the activity of a
pure solid is equal to one, this expression reduces to the
solubility product expression:
K.sub.sp=[Ca.sup.2+(aq)][CO.sub.3.sup.2-(aq)]
[0110] This expression says that an aqueous solution in equilibrium
with (saturated with) solid calcium carbonate has concentrations of
these two ions such that their product equals Ksp; for calcium
carbonate Ksp=3.8*10.sup.-9 measured at 25.degree. C.
[0111] The higher solubility of magnesium carbonate also
contributes to additional pressure build-up during the foaming
process which is undesirable.
[0112] The phenolic foam of the present invention comprises a
blowing agent containing an aliphatic hydrocarbon that provides
favourable properties regarding ozone depletion and global warming
potential.
[0113] The amount of acid catalyst is controlled, and an inorganic
filler such as calcium carbonate is added to increase pH. The
higher pH value of the foam ensures that metallic material in
contact with the phenolic foam is at reduced risk of corrosion.
[0114] The phenolic foam retains favourable fire-performance
characteristics, and has stable thermal insulation performance over
extended time scale. Preferably less than 0.025 W/m.K (measured at
a mean temperature of 10.degree. C. and after 175 days conditioning
at 70.degree. C. followed by conditioning until stable weight at
23.degree. C. and 50% R.H.).
[0115] The phenolic foam is used industrially as thermal insulation
for construction materials.
[0116] The invention is not limited to the embodiments herein
before described which may be varied in detail.
* * * * *