Note: Descriptions are shown in the official language in which they were submitted.
Zl 9~244
Translation of PCT/EP95/02715
"J~TrIOE r~YER O~UNDS PND THEIR USE"
Description
This invention relates to the use of lithium-containing lat-
tice layer compounds as stabilizer or stabilizer component
for halogen-containing polymers.
A halogen-containing thermoplastic resin, such as polyvinyl
chloride (PVC), is converted to a polyene structure upon exe-
cution of a melt forming process, where the hydrochloric acid
is eliminated and the polymer is discoloured. To improve the
thermostability of the polymer it is common practice to in-
corporate metal carboxylates as stabilizers into the resin.
But since in the case of a prolonged melt forming process the
incorporation of the stabilizers alone can lead to what is
called metal burning, which causes a blackening of the poly-
mer, it is common practice to add a co-s~hili7er, such as
for instance polyols (like pentaerythritol), organic esters
of phosphorous acid (like triphenyl phosphite), epoxy com-
pounds (like epoxidized soybean oil).
Since basic lead salts, like other heavy-metal-containing
stabilizers, are classified as toxic, attempts are being made
to find stabilizing alternatives. A plurality of combinations
of inorganic and organic substances are known as stabilizers
for halogen-containing polymers. In the documents DE 30 19
632 and EP 0 189 899 hydrotalcites are proposed as stabiliz-
ers. These substances are superior to mixtures of Ca/~n metal
carboxylates as regards their e~fect on the ~h~ ~Lability
and transparency of the resins stabilized therewith. However,
21 95244
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the problem of the discoloration of the polymer during proc-
essing cannot be solved by the use of hydrotalcites. In ac-
cordance with the document EP 0 063 180 it is proposed to use
combinations of hydrotalcites and 1,3-diketo compounds for
the solution of this problem.
In the document EP 0 139 931 basic compounds, which represent
combinations of mono- and divalent cations or di- and triva-
lent cations with various anions, are disclosed as stabiliz-
ers. These substances, in particular the substances repre-
sented in the examples, must be regarded as hydrotalcites
rich in aluminium or as compounds with a high hydrotalcite
content. In mixtures with Zn metal carboxylates their addi-
tion to halogen-containing resins leads to an improvement of
the thermostability. However, even the use of such substances
cannot solve the problem of the discoloration of the polymer
during processing. As proposed above, combinations with 1,3-
diketo compounds must be used for the solution of this prob-
lem.
In the documents DE 39 41 902 and DE 41 06 411 or DE 40 02
988 and DE 41 06 404 as well as DE 41 03 881 basic calcium-
aluminium-hydroxy phosphites or basic calcium-aluminium-
hydroxy carboxylates as well as hydrocalumites are proposed
as stabilizers for halogen-containing polymers, in particular
PVC. The substances are inferior to stabilizer mixtures with
hydrotalcites as regards their effect on the thermostability
and transparency of the resins stabilized therewith. Further-
more, the use of such substances with hydrate water can lead
to problems during the processing of the halogen-containing
resin as a result of the separation of the crystal water (see
M. Meyn "Doppelhydroxide und Hydroxiddoppelsalze - Synthese,
Eigenschaften und Anionaustauschverhalten", thesis, ~iel
1991). The document EP 0 256 872 proposes to eliminate this
disadvantage by adding micronized magnesium oxide.
' 21 ~524~
~ 3 -
In the documents DE 41 03 916 and De 41 06 403 basic hydroxycompounds of di- and trivalent metal ions, which are defined
as "not of the hydrotalcite type", are disclosed for instance
as PVC stabilizers. These substances are likewise inferior to
stabilizer mixtures with hydrotalcites as regards their heat-
stabilizing effect and the transparency of the stabilized
products. Furthermore, here as well the use of such sub-
stances with hydrate water can lead to problems during the
processing of the halogen-containing resin as a result of the
separation of the crystal water.
From the document WO 92/15525, which corresponds to the al-
ready cited document DE 41 06 403, basic hydroxy compounds of
di- and trivalent metal ions are known, which are used as PVC
stabilizers. These known compounds contain aluminium and iron
as trivalent metal ions as well as strontium, barium, zinc,
tin and iron as divalent metal ions. Lithium-containing com-
pounds are not disclosed in the WO 92/15525.
From the document EP 0 207 811 lithium-containing lattice
layer compounds are known, which contain various anions and
should be used as thickening agents for aqueous media, e.g.
drilling fluids. It is furthermore known that soluble lithium
compounds, which are used as stabilizers in halogen-
containing polymer masses, increase the water-absorbing ca-
pacity of these resins. This deteriorates the insulating ef-
fect of cable insulations, and in pressurized-water pipes the
capacity of bearing the internal water pressure is reduced.
Lithium carbonate has no stabilizing effect, but lithium hy-
droxide has a good stabilizing effect, where the initial col-
our and the colour distribution are, however, influenced un-
favourably. Lithium oxide exhibits analogous stabilizing
properties with respect to halogen-containing polymer masses
as compared to lithium hydroxide, but here as well the hydro-
philicity is disadvantageous. Stabilizer mixtures containing
lithium oxide have no storage stability. What is known are
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lithium salts with fatty acids, in particular stearic acid,
as PVC stabilizers. In the document DE 1 115 460, for in-
stance, there i6 described a combination of lithium stearate
and glycerol mono(acetyl ricinoleate) for use as PVC stabi-
lizer. However, these 8tabilizer8 have not gained any commer-
cial importance. on the one hand, becau8e a melting reaction
of lithium stearate is hardly possible (melting point of
lithium stearate: 200 to 215~C), and on the other hand, be-
cause for the production by means of a precipitation reaction
soluble lithium salts such as the hydroxide or the chloride
are required, which are both comparatively expensive.
The object underlying the invention is to provide lattice
layer compounds, which are suited as stabilizers for halogen-
containing polymers, are in particular not toxic, and can
eliminate the disadvantages of the known stabilizers.
The object underlying the invention is solved in that lith-
ium-containing lattice layer compounds of the formula
LiaMe b+CMe b-c(OH)dA ~*mH20 (I),
wherein
MeII is Mg, Ca, Zn and/or Sn2 ,
Me is Al and/or ~e ,
A is an anion of the valence n or a mixture of anions,
where the indices lie in the range from
o < a 5 1,
2 S b 5 6
-0.5 5 c S 0.5
m = o to 5
d, e are unlike 0 and are selected such that a neutral
molecule is obtained,
' ' 21 95244
are used as stabilizer or stabilizer component for halogen-
containing polymers.
In contrast to known stabilizers such as lime hydrate, magne-
sium or lithium hydroxide, the lattice layer compounds used
in accordance with the invention do not absorb carbon dioxide
from the air. In contrast to lithium hydroxide these com-
pounds are hardly soluble, and in contrast to hydrotalcites
they have a clearly reduced hydrophilicity, which is charac-
terized by little absorption of moisture from the air. Fur-
thermore, it has surprisingly turned out that the lattice
layer compounds used in accordance with the invention provide
halogen-containing thermoplastic resins and the parts pro-
duced therefrom with a high thermostability as compared to
halogen-containing thermoplastic resins and the parts pro-
duced therefrom, which do not contain the substances to be
used in accordance with the invention. The lattice layer com-
pounds to be used in accordance with the invention in par-
ticular prevent a discoloration during the production of un-
plasticized PVC extrudates. Both the colour distribution and
the weathering stability of the specimens stabilized with
these substances are better than in those specimens which do
not contain the lithium-containing lattice layer compounds.
In contrast to structurally comparable tribasic lead sulfate,
the transparency of halogen-containing resins is not deterio-
rated by the use of the lattice layer compounds to be used in
accordance with the invention. The dried lattice layer com-
pounds to be used in accordance with the invention do not re-
lease water and gas at the processing temperatures of 160 to
200OC commonly used for unplasticized PVC, so that there is
no disturbing formation of bubbles in the moulded articles.
The lattice layer compounds to be used in accordance with the
invention can advantageou51y be used as stabilizers for PVC,
polyvinylidene chloride, chlorinated or chlorosulfonated
polyethylene, chlorinated polypropylene or chlorinated ethyl-
ene/vinyl-acetate copolymer.
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In accordance with a ~urther aspect of the invention, the an-
ion An in the use o~ lithium-containing lattice layer com-
pounds consists of sulfate, sulfite, sulfide, thiosulfate,
peroxide, peroxosulfate, hydrophosphate, hydrogen phosphite,
carbonate, halogenite, nitrate, nitrite, hydrogen sulfate,
hydrogen carbonate, hydrogen sulfite, hydrogen sulfide, dihy-
drogen phosphate, dihydrogen phosphite, a monocarboxylic acid
anion such as acetate or benzoate, amide, azide, hydroxide,
hydroxylamide, hydrazide, acetylacetonate, phenolate, pseudo-
halide, halide, halogenate, perhalogenate, J3 , pr~r~-ng~n~ter
a dicarboxylic acid anion such as phthalate, oxalate, maleate
or fumarate, bisphenolate, phosphate, pyrophosphate,
phosphite, pyrophosphite, a tricarboxylic acid anion such as
citrate, trisphenolate, or also of a mixture of several of
these anion groups.
In accordance with the invention it is furthermore provided
that the lithium-containing lattice layer compounds contain
at least one metal carboxylate. Suitable metal carboxylates
include the salts of higher fatty acids and the salts of
naphthenic acids with metals of the second group of the Peri-
odic Table, in particular with magnesium, calcium, strontium,
barium, and zinc. The salts of stearic, palmitic, myristic,
lauric and ricinoleic acid are particularly advantageous.
zinc salts are particularly effective for the colour distri-
bution. Therefore, at least part of a zinc salt of a higher
fatty acid is preferably used. Although the above-mentioned
metal carboxylates may be used singly, the stabilizing effect
can be increased by using two or more metal carboxylates.
In accordance with the invention it is finally provided that
the lattice layer compounds contain at least one 1,2-diketo
compound, an organic ester of phosphorous acid, an epoxy com-
pound, a polyol or an amino acid derivative. Suitable 1,3-
diketo compounds include dibenzoylmethane, stearoylbenzoyl-
methane, palmitoylbenzoylmethane, myristoylbenzoylmethane,
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lauroylbenzoylmethane, benzoylacetone, tribenzoylmethane, di-
acethyl acetobenzene, p-methoxystearoyl acetophenone, ace-
toacetic acid ester and acetylacetone. Suitable esters of
phosphorous acid include trialyl phosphites such as triphenyl
phosphite, tris(p-nonylphenyl)phosphite, alkylaryl phosphites
such as monoalkyldiphenyl phosphites, e.g- diphenylisooct
phosphite, diphenylisodecyl phosphite, and dialkylmonophenyl
phosphites such as phenyldiisooctyl phosphite, phenyldiisode-
cyl phosphite, and trialkyl phosphites such as triisooctyl
phosphite and tristearyl phosphite. Suitable polyols include
trismethylol propane, di-(trismethylol propane), erythritol,
pentaerythritol, dipentaerythritol, sorbitol and mannitol.
Suitable amino acid derivatives include glycin, alanine, ly-
sin, tryptophane, acetylmethionine, pyrrolidone carboxylic
acid, ~-amino crotonic acid, a-amino acrylic acid, ~-amino
adipic acid as well as the corresponding esters. The alcohol
components of these esters include monovalent alcohols such
as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl
alcohol, butyl alcohol, ~-ethyl hexanol, octyl alcohol, iso-
octyl alcohol, lauryl alcohol, stearyl alcohol, as well as
polyols such as ethylene glycol, propylene glycol, 1,3-
butanediol, 1,~-butanediol, glycerol, diglycerol, trismethy-
lol propane, pentaerythritol, dipentaerythritol, erythritol,
sorbitol and mannitol. The epoxy compounds used include vari-
ous animal and vegetable oils such as epoxy soy oil, epoxy
rape-seed oil, epoxidized fatty acid esters such as epoxy
methyl oleate, epoxy butyl oleate, epoxidized alicyclic sub-
stances, glycide ethers such as bisphenol-~ diglycide ether,
bicphenol-F diglycide ether, glycide esters such as glycidyl
acrylate, glycidyl methacrylate, the polymers and copolymérs
thereof as well as epoxidized polymers such as epoxidized
polybutadiene and epoxidized acrylic-acid-butadiene-styrene
terpolymer.
Preferred metering quantities (in parts by weight per lOo
parts by weight resin) for the lattice layer compounds of
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formula (I) to be used in accordance with the invention are0.1 to S, preferably 0.5 to 3. Preferred metering quantities
for the co-stabilizers are:
Metal carboxylates: 0.1 to 5, preferably 0.5 to 3.
1,3-diketo compounds, organic phosphites, polyols, amino acid
derivatives: O to 5, preferably 0.1 to 3.
Epoxy compounds: O to 5, preferably 0.05 to 4.
In particular combinations of the lattice layer compounds of
formula (I) to be used in accordance with the invention and
metal carboxylates are preferred as stabilizer mixtures for
halogen-containing resins.
To the halogen-containing thermoplastic resin composition
stabilized in accordance with the invention there can fur-
thermore be added the additives known to the man skilled in
the art, such as fillers, lubricants, plasticizers, dyes,
pigments, antistatic agents, surface-active agents, foaming
agents, impact modifiers, W stabilizers, and antioxidants.
Useful antioxidants include 2,5-di-t-butylhydroquinone, 2,6-
di-t-butyl-4-methylphenol, 4,4'-thiobis-(3-methyl-6-t-
butylphenol), 2,2'-methylene-bis(4-methyl-6-t-butylphenol),
and stearyl-3-(3'-5'-di-t-butyl-4-hydroxyphenyl)propionate.
In particular the addition of a plasticizer is common prac-
tice. There may for instance be added phthalic acid esters
such as dioctyl phthalate, aliphatic dibasic acid esters,
trimellitic acid esters, phosphate esters and fatty acid es-
ters, epoxy plasticizers, polyester plasticizers, chlorinated
paraffins and similar plasticizers in appropriate quantity
ratios, with reference to the halogen-containing thermoplas-
tic resin. To improve the dispersibility of the lattice layer
compounds to be used in accordance with the invention in the
halogen-containing thermoplastic resins, the lattice layer
2 1 95244
_ 9 _
compounds may be surface-treated with a higher fatty acid,
e.g. with stearic acid, an anionic surface-active agent, a
silane coupling agent, a titanate coupling agent, or a glyc-
erol fatty acid ester.
As moulding processes for processing the halogen-containing
thermoplastic resin compositions stabilized in accordance
with the invention calendering, extruding, injection mould-
ing, blow moulding or other processes may be used.
The thermostability and the initial colour as well as the
colour distribution of the halogen-containing thermoplastic
resin are improved significantly by adding the lattice layer
compounds in accordance with formula (I), in particular in
conjunction with metal carboxylates, and preferably also in
conjunction with the other co-stabilizers in the indicated
quantities. The resin compositions stabilized in accordance
with the invention do not exhibit a plate-out phenomenon dur-
ing calendering, and provide for a long-term extrusion. In
addition, the resulting products are free from discoloration.
Accordingly, the present invention is a remarkable, novel
contribution to the processing of PVC and other halogen-
containing thermoplastic resins- The lattice layer compounds
to be used in accordance with the invention are obtained in
that in an aqueous medium lithium hydroxide, lithium oxide
and/or lithium compounds to be converted into the hydroxide
as well as metal(II) hydroxides, metall(II) oxides and/or
compounds of divalent metals to be converted into hydroxides
as well as aluminium and/or iron(III) hydroxides and/or com-
pounds of iron and/or aluminium to be converted into hydrox-
Ldes as well as acids and/or the salts thereof or mixtures
thereof are reacted with each other at a pH of 8 to 10 and at
temperatures of 20 to 25~'C, and the solid reaction product
obtained is separated. The reaction product obtained from
this reaction can be separated from the aqueous reaction me-
'"' 21 9524~
-- 10 --
dium by known methods, preferably by filtration. The proce~s-
ing of the separated reaction product iB likewise effected in
a manner known per se, for instance by washing the filter
cake with water and drying the washed residue at temperatureS
of for instance 60 to 150~C, preferably at 90 to 120~C. In
the case of aluminium, both finely divided, active aluminium
hydroxide in combination with sodium hydroxide as well as
NaAl02 may be used for the reaction. Lithium and the divalent
metal may be used in the form of finely divided lithium oxide
or hydroxide or mixtures thereof or of finely divided
metal(II) oxide or hydroxide or mixtures of said compounds.
The corresponding anions may be used in different concentra-
tions, e.g. directly as acid or as salt. The reaction tem-
peratures preferably lie in the range between about 20 and
250~C, in particular between 60 and 180~C. Catalysts or ac-
celerators are not required- In the substances to be used in
accordance with the invention the crystal water may be re-
moved wholly or in part through a thermal treatment (drying).
The invention will be explained in detail by the following
Examples, but without being restricted thereto.
EXAMPLES
1. Production of the inventive substances
Example 1 (Compound 1
2 mol (80.0 g) magnesium oxide are stirred in 600 ml water
for 30 minutes. 2 mol (164.0 g) anhydrous sodium aluminate
are dissolved in 700 ml water. 0.13 mol (5.5 g) lithium hy-
droxide monohydrate are dissolved in 150 ml water, and the
lithium hydroxide solution and the MgO suspension are added
to the sodium aluminate solution in quick sUccession. There
is observed a temperature increase to 35~C. After stirring
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _, .. . . . .. . . . _ . . _ . _ . . . ..
;- 2195244
-- 11 --
for one hour, CO2 i8 introduced at room temperature to a pH
of 9Ø Upon carbonation, the excess CO2 i8 concentrated to a
pH of 10Ø The preparation is filled up to a volume of three
liters and treated for three hours at 80 to 95~C. The reac-
tion product is filtered by suction and washed three time~
with two liters water. The filter cake is dried in a vacuum
for four hours at 130~C.
ProdUCt obtained: Lio~26Mg4.oAl3~8loH)l7~7co3
Analysis: Li 0.30 %, Mg 16.50 %, Al 17.50 %, CO2 7.50 ~
Example 2 (Compound 2)
1.5 mol (60.0 g) magnesium oxide are stirred in 600 ml water
for 30 minutes. 1.5 mol (123.0 g) anhydrous sodium aluminate
are dissolved in 700 ml water. 0.275 mol (11.5 g) lithium hy-
droxide monohydrate are dissolved in 150 ml water, and the
lithium hydroxide solution and the MgO sUspension are added
to the sodium aluminate solUtion in quick succession. There
is observed a temperature increase to 35~C. After stirring
for one hour, COz is introduced at room temperature to a pH
of 9Ø Upon carbonation, the excess CO2 is concentrated to a
pH of 10Ø The preparation is filled up to a volume of three
liters and treated for three hours at 80 to 95OC. The reac-
tion product is filtered by suction and washed three times
with two liters water. The filter cake is dried in a vacuum
for four hours at 130~C.
Product obtained: Lic~ssMg3~loAl2~ss(oH)l3~6co3
Analysis: Li 0.89 %, Mg 17.30 %, Al 18.40 %, Co2 10.20 %
"' 21 95244
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Example 3 (Compound 3)
1.5 mol (60.0 g) magnesium oxide are stirred in 600 ml water
for 30 minutes. 1.2 mol (123-0 g) anhydrous sodium aluminate
are dissolved in 700 ml water- 0.4 mol (16.8 g) lithium hy-
droxide monohydrate are dissolved in 150 ml water, and the
lithium hydroxide solution and the MgO 8UspenSion are added
to the sodium aluminate solUtion in quick succession. There
is observed a temperature increase to 35~C. After stirring
for one hour, CO2 is introduced at room temperature to a pH
of 9Ø Upon carbonation, the excess CO2 is concentrated to a
pH of 10Ø The preparation is filled up to a volume of three
liters and treated for three hours at 80 to 95~C. The reac-
tion product is filtered by suction and washed three times
with two liters water. The filter cake is dried in a vacuum
for four hours at 130~C.
Prcduct obtained: Lio~8cMg3~loAl2~3o(oH)l3~4co3
Analysis: Li 1.10 %, Mg 15.90 %, Al 16.20 ~, CO2 9.50 %
Example 4 (Compound 4)
2.5 mol (100.0 g) magnesium oxide are stirred in 600 ml water
for 30 minutes. 2.5 mol (205.0 g) anhydrous sodium aluminate
are dissolved in 700 ml water. 0.085 mol (3.6) lithium hy-
droxide monohydrate are dissolved in 150 ml water, and the
lithium hydroxide solution and the MgO suspension are added
to the sodium aluminate solution in quick succession. There
is observed a temperature increase to 35~C. After stirring
for one hour, CO2 is introduced at room temperature to a pH
of 9Ø Upon carbonation, the excess Co2 is concentrated to a
p~ of 10Ø The preparation is filled up to a volume of three
liters and treated for six hours at a pressure of 10 bar and
a temperature of about 180~C- The reaction product is fil-
- '' . 21 9524~
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tered by suction and washed three times with two liters wa-
ter. The filter cake is dried in a vacuum for four hours at
130~C.
Product obtained: Lio~l7Mgs.loAl4.8o(oH)22.sco3
Analysis: Li 0.17 %, Mg 18.20 %, Al 19.00 %, CO2 6.50 %
From Examples 1 to 4 the man 8killed in the art can derive a
general procedure. The general prescription essentially con-
sists in that
1. the stoichiometric proportions of the components for ob-
taining the inventive substances, and
2. upon addition of the anion(s) a pH of 10 is not consid-
erably exceeded.
Examples 5 to 11
The following further inventive compounds were prepared:
Table 1:
Example Formula Compound
LiO.4Mg4~2Al4.4(oH)2o.oco3 5
6 Li0.sMg5 gAl6~0(OH)2g~1(fumarate) 6
7 Li0 6Mg3 6Al3 6(OH)17 6(maleate)0 s 7
8 Li0 gMg4 7Al4 7(OH)22 4(phthalate)0 5 8
9 Lio 7Ca4.0Al4 o(~H)1g 7(phthalate)0 5 9
Lio~2ca4~6Al4~8(oH)ls~8(co3)2~o 10
11 Lio~2ca3~6Al3~6(oH)l7~8(Hpo3)o~2 11
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2. Non-inventive comparative compounds
Examples 12 to 13
Example Compound
12hydrotalcite Mg4Al2(o8)l2co3*3H2o 12
(no hydrothermal
~ treatment)
13hydrocalumite Ca4Al2(oH)l2Hpo3*2H2o 13
3. Use of the inventive substances as stabilizers
In the subsequent Example, the thermo5tability is evaluated
by the MATHIS Thermofurnace Test (MTT), and the initial col-
our is evaluated by the Yellowness Index (YI 0 min.) of
moulded PVC articles, to which inventive substances and for
comparison purposes non-inventive substances were added.
For this purpose, PVC resin masses were homogenized and plas-
ticized on a laboratory rolling mill for five minutes at
180~C. From the rolled sheet thus produced, which had a
thickness of about 1 mm, a test strip having a width of 10 mm
was cut out and tempered in the MATHIS Thermofurnace at
180~C. After 10 minutes, the test strip was moved out of the
furnace 23 mm, until blackening was observed.
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Table 2: Test Formulation
Formulation
PVC 100
Chalk 5
Tio2 4
Modifier 7
Flowing aid
Lubricant~) 0.3
Bisphenol A 0.1
Zinc stearate 1.5
Dipentaerythritol 0.9
Dibenzoylmethane 0.25
Specimen
~) lubricant - ester wax
~ample 14
Table 3: Results of the application tests
Compound MTT/minYI Omin
none 75 6.8
1 150 6.3
2 160 7.2
3 155 6.4
4 140 5.2
145 5.9
6 170 7.6
7 150 5.8
8 165 6.1
9 155 5.4
140 5.3
11 140 6.1
12 125 9.3
13 105 5.0
