Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Process for the preparation of moAified pheno] resins, their use :~
and phenol resin foams produced therefrom :
The invention relates to modified phenol/for~aldehyde
foam resins of the resol type for the production of biodegradable,
thermosetting phenol resin foams.
The use of degradable plastics is having to meet
increasingly high requirements. It i5 known that biodegradability
can be achieved by modifying thermoplastics. No biodegradable
thermosetting plastics are known to date.
~ t is therefore the object of the invention to develop
the phenol~formaldehyde resol resins from which it is possible to
produce biodegradable thermose~ting foams.
Surprisingly, it is possible, according to the
invention, to add the modifying additives to the starting
materials of the phenol resin preparation before the condensation
to give the resin, that is to say to the mixture of phenol and
formaldehyde and the further components thereof, without adversely
affecting condensation and expansion. Suitable amounts of
additives are from 5 to 50% by weight, based on phenols. The
additives do not hinder the condensation of the resins and permit
the formation of foam articles having the same quality as without
the additives. The foams containing the additives rot in the
presence of moisture and on admission of microorganisms. ;
Suitable additives are mono- and disaccharides, the -
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corresponding sugar alcohols and urea/formaldehyde
condensates which, ~imilarly to sugar, contain 8everal OH
group t that i~ to ~ay low molecular weight, water-
soluble substances having several, or a large number of,
OH groups.
The condensation of the phenol resins with the additives
thereof takes place under the usual preparation condi-
tions and without any change in the typical ranges of
characteristics of the foam resins or of the foams
produced therefrom.
The resin batch comprising phenol and, if required,
cresol can be condensed in the usual manner with formal-
dehyde in the amounts intended for this purpose by the
addition of alkaline agents at elevated temperature,
according to the invention the additives already being
present from the beginning. The usual basic condensing
aqents, such as NaOX, barium hydroxide or ammonia, may be
used in a known amount. After conden3ation of the resin,
neutralization i5 effected in the usual manner with acids
and dehydration is carried out in vacuo to viscosities
of, preferably, 2,000 to 12,000 mPa.s, measured at 20C.
Analyses showed that, after condensation of the resin~,
the additives are surprisingly present only partly in
free form.
For the production of the foams, a blowing agent i~ added
to the resins at room t~mperature, low-boiling blowing
agents, such as hydrocarbons and mixtures thereof having
boiling points between 36 and 80C being decisively
preferred. Acidic curing agents, such as toluene- or
phenolsulphonic acids, and surfactants are added.
Surfactant mixtures which have a hydrophobic effect are
used for the production of essentially hydrophobic foams,
whereas hydrophilic surfactant mixtures are used for the
preferred foams for the in~ertion of flowers. Such foams
for the insertion of flowers are used in particular for
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the production of mouldings for flower arrangement5, but
also for the production of water-absorbing protective
packaging for the transport of flowers.
Through the choice of the ~urfactants, the water ab~orp-
tion which is important for this purpose should be in the
region of 80% of water, based on the volume of the
insertion foam, and the water absoxption rate Yhould be
high and should be not more ~han a few minutes.
The foams for insertion of flower are generally coloured
with, preferably, green dyes. It proved surprisingly
( advantageous that, owing to the additives according to
the invention, insertion foams had outstanding colour
fastness.
The expansion of the foam resins i8 carried out in the
usual manner at temperatures of 40 to 60C in a heatable
mould or in a double-belt pres~, curing taking place at
the same time.
The characteristics of a typical foam resin are as
follows~
20 Solid resin content 70 - a4~ by weight
Viscosity (20C, Hoeppler) 2,000 - 10,000 mPa.s
Water content (according to
Rarl Fischer) 5 - 20~ by weight
Free phenol ~ - 10% by weight
25 Free formaldehyde 0.2 - 3% by weight
Resin reactivity 100 - 150C
The foam resin reactivity as a measure of the curing rate
is determined as a function of time by measuring the
maximum temperature after addition of a certain amount of
a standard curing agent.
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A typical expansion formulation i8 as followss
100 parts by weight of resin
2 - 8 part~ by weight of 3urfactant mixture
5 - 10 parts by weight of blowing agent
5 - 15 par~s by weight of curing agent and
0.5 - 2 parts by weight of dye.
Surfactant mixtures comprising nonionic surfactants and
~nionic surfactants in a weight ratio of 1 : 5 to 5 : 1
are preferred. The foams for the insertion of flowers
which are produced in this manner have a density range of
( 15 to 35 kg/m3.
It was furthermore found that insertion foams which are
produced in this manner are also ou~tandingly suitable
for the culture of ornamental and crop plants in the
absence of earth and with the use of nutrient solutions.
To check the biodegradability of the foams for flower
insertion described, test serieR were carried out at the
Institute for Vegetable Cultivation of the Hanover
Technical University. The foam was mixed with compo t in
different ratios, the mixtures were introduced into gla~s
vessels and the particular, 24-hour C02 production was
(- measured at interval~ of up to 3 weeks as a measure of
the degradability. From the beginning, the measured C02
values were far above those which correspond to the
mixing ratio of compo~t to foam, indicating decomposition
of the theImosetting foams. The series was terminated
after 4 months. In the case of the insertion foams which
were produced from unmodified phenol resols without the
additives according to the invention, decomposition by
microorganisms was not detectable`even after composting
for 6 months.
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Examples
Example 1
1,294 part~ by weight of a 37% strength by weight aqueous
formaldehyde solution, 250 parts by weight of lactose
monohydrate and 53 parts by weight of barium hydroxide
octahydrate are added to 1,000 parts by weight of phenol,
dis~olved in 100 parts by weight of water. The mixture
is heated to 85C while stirring and is kept at this
temperature for 130 minutes. After the neutralization
with 21 parts by weight of 2S% strength by weight sul-
phuric acid, the aqueous resin solution i~ dehydrated in
vacuo (13 mbar, bottom temperature 60C) until the resin
sample has a viscosity of 77%. The reactivity of the
resin is T~. = 127C, the free phenol content Ls 9.7% by
weight, the free formaldehyde content is 1% by weight and
the free lactose content is 2% by weight.
Example 2
1,294 parts by weight of a 37% strength by weight aqueous
formaldehyde solution, 715 part~ by weight o~ a 70%
strength by weight aqueous sorbitol 301ution and 70 parts
by weight of barium hydroxide octahydrate are added to
( 1,000 parts by weight of phenol, dissolved in 100 parts
by weight of water. The mixture is heated to 85C while
stirring and is kept at this tEmperature for 85 minutes.
After the neutralization with 67 parts by weight of a 25%
strength ~y weight sulphuric acid, the aqueous resin
solution is dehydrated in vacuo until the resin sample
has a viscosity of 5,400 mPa.s (25C) and a solld resin
content of 82%. The reactivity of the resin ic
T~. = 117C. The free phenol content is 7.4~ by weight,
the free formaldehyde content is 0.6~ by weight and the
free sorbitol content is 9.5~ by weight.
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Example 3 ~Re~in 1)
1,294 parts by weight of a 37% strength by weight aqueous
formaldehyde solution, 250 parts by w~ight of glucose
monohydrate and 53 parts by weight of barium hydroxide
octahydrate are added to l,000 parts by weight of phenol,
dissolved in lO0 parts by weight of water. The mi~ture
is heated to 85C while stirring and i~ kept at this
temperature for 130 minutes. After the neutralization
with 21 parts by weight of a 25% strength by weight
sulphuric acid, the aqueous resin solution is dehydrated
in vacuo (13 mbar, bottom temperature 60C) until the
resin sample has a viRco~ity of 3,700 mPa.~ (20C,
according to Hoeppler) at a solid resin con~ent of 78~.
The reactivi~y of the re~in is T~. = 112C. The free
phenol content is 8.9% by weight, the free formaldehyde
content is 0.7~ by weight and the free glucose content is
3.2~ by weight.
Example 4 (Resin 2)
536 parts by weight of a 37~ strength by weight aqueous
formaldehyde solution and 300 parts by weight of urea are
kept at 50C for 15 minutes with 2 part~ by weight of a
25% strength ammonia solution, a pH of 8 is established
( by the addition of a triethanolamine/ammonia mixture
(ratio 4 : 1) to the precondensate and the mixture is
2S again left at 50C for 30 minutes. 545 parts by weight
of phenol, dissolved in 55 g of water, 706 parts by
weight of a 37% strength by weight aqueous fôrmaldehyde
solution and 45.2 parts by weight of barium hydroxide
octahydrate are added to this mixture and the total
mixture i8 kept at 85C for 140 minutes while stirring.
After the neutralization with 30 g of a 25% strength by
weight sulphuric acid, the solution is dehydrated until
it ha3 a viscosity of 3,600 mPa.s (20C, Hoeppler) at a
~olid resin content of ~8%~
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Example 5
14 g of a regulator mixture con~isting of ionic and
nonionic surfactants, 0.9 g of a dye based on a tri-
phenylmethane derivative, 23 cm3 of petroleum ether 40/80
and 22.5 ml of an acidic curing a~ent are added to 200 g
of resin 2 while ~tirring. After a 3tirring ~ime of
30 seconds, the reaction mixture i8 poured into a paper
bag and then placed in an oven thermostated at 60C. The
curing process is complete after 30 minutes. The foam
has the following characteristics: density = 25 kg/m3,
water absorption rate (brick) 55 seconds, water absorp- ;
tion volume > 90% by volume.
Example 6
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14 g of a regulator mixture consisting of ionic and
nonionic surfactants, 0.9 g of a dye based on a tri-
phenylmethane derivative, 22 cm3 of petroleum ether 40/80
and 17.5 cm3 of an acidic curing agent are added to 200 g
of resin 1 while stirring. After a stirring t~me of
30 seconds, the reaction mixture is poured into a paper
bag and then placed in an oven thermostated at 60C. The
curing process i8 complete after 30 minutes. The foam
has the following characteristicss density = 25 kg/m3,
water absorption rate (brick) 80 seconds, water absorp-
tion volume 80~ by volume.
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