Note: Descriptions are shown in the official language in which they were submitted.
. ~ ~19S2q5 A 7728
Translation of PCT/EP95~02716
Lattice Layer Compounds and Halogenated Polymer Mass
Stabilizers Containing the Same
Description
This invention relates to lattice layer compounds of the gen-
eral formula
Li~Me b_2aMe 2+a(~H)4+2b~ 2/n*mH2~ (I)
wherein
MeI7 is Mg, Ca, Zn and/or Sn2
MeIII is Al and/or Fe3
An_ i8 an anion of the valence n or a mixture of anions,
and the indices lie in the range from
0 < a < (b-2)/2,
1 < b ~ 6, and
m = 0 to ~,
with the restriction that b-2a > 2.
The invention furthermore relates to a process of producing
lattice layer compounds as well as halogenated polymer mass
stabilizers containing said lattice layer compounds.
A halogenated thermoplastic polymer such as polyvinyl chlo-
ride (PVC) is converted to a polyene structure during a melt
forming process, wherein hydrochloric acid is eliminated and
the polymer is discoloured. To improve the thermostability of
the polymer it i8 common practice to incorporate metal car-
boxylates as stabilizerS in the polymer mass. But since even
~ ~ 2tg52~
-- 2 --
in the case of a prolonged melt forming process, the incorpo-
ration of the stabiliZerS alone can lead to what i8 called a
metal burning, which causes a blackening of the polymer, it
is common practice to add a co-stabilizer, such as polyols
(e.g. pentaerythritol), organic phosphite esters (such as
triphenyl phosphite~, epoxy compounds (such as epoxidized soy
oil).
Since basic lead salts like other heavy-metal-containing sta-
bilizers are regarded as toxic, one tries to find stabiliza-
tion alternatives. A plurality of combinations of inorganic
and organic substances are known as stabilizers for halogen-
ated polymers. In DE 30 19 632 and EP 0 189 899 hydrotalcites
are proposed as stabilizers. These substances are superior to
mixtures of Ca/Zn metal carboxylates as regards thermal sta-
bility and transparency. However, even the use of hydrotal-
cites cannot completely solve the problem of the discolora-
tion of the polymer during processing. For the solution of
this problem the document EP 0 063 180 proposes the use of
combinations of hydrotalcites and l,3-diketo compounds.
The document EP 0 139 931 proposes basic compounds as stabi-
lizers, which represent the combinations of monovalent and
divalent cations or of divalent and trivalent cations with
various anions. These substances, in particular those repre-
sented in the Examples, should be regarded as hydrotalcites
rich in aluminum, or as compounds with a high hydrotalcite
content. In mixtures with Zn-metal carboxylates they are su-
perior to other stabilizer mixtures as regards their effect
on the thermal stability of the stabilized polymer masses.
However, 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 in order to solve this problem.
3 219~245
In the documents DE 39 41 902 and DE 41 06 411 as well as DE
40 02 988, DE 41 06 404 and DE 41 03 881 basic calcium-
aluminum-hydroxy phosphites and basic calcium-aluminum-
hydroxy carboxylates, respectively, as well as hydrocalumites
are proposed as stabilizers for halogenated polymers, in par-
ticular PVC. These substances are inferior to stabilizer mix-
tures with hydrotalcites as regards their effect on the ther-
mal stability and transparency of the polymer masses stabi-
lized therewith. Furthermore, the use of such hydrate-water-
containing substances can lead to problems as regards the in-
corporation in halogenated polymer masses due to the separa-
tion of the crystal water (see M. Meyn "Doppelhydroxide und
~ydroxiddoppelsalze - Synthese, Eigenschaften und Anionenaus-
tauschverhalten", thesis, Kiel 1991). The document EP-A-0 256
872 therefore proposes to eliminate this disadvantage by add-
ing micronized magnesium oxide.
The documents DE 41 03 916 and DE 41 06 403 disclose basic
hydroxy compounds of divalent and trivalent metal ions, which
are defined to be ~not of the hydrotalcite type~, for in-
stance for use as PVC stabilizers. These substances, too, are
inferior to mixtures with hydrotalcite as regards the thermal
stability and transparency of the products stabilized there-
with. When using such substances, the hydrate water may fur-
thermore lead to problems as regards the incorporation in
halogenated polymer masses due to the separation of the crys-
tal water.
It is the object underlying the invention to provide novel
lattice layer compounds as well as a process of producing the
same, which are in particular regarded as non-toxic and are ==
particularly suited as stabilizers for halogenated polymers,
without having the above-mentioned disadvantages of the known
stabilizers.
~ ~ 219~245
In accordance with the invention this object is solved by
lattice layer compounds of the general formula
LiaMe b-2aMe 2+a(oH)4~2bA 2/n~mH20
wherein
MeII is Mg, Ca, ~n and/or Sn
MeIII is Al and/or Fe
An_ is a selected anion of the valence n or a mixture of
anions, and the indices lie in the range from
O < a ~ (b-2)/Z,
1 ~ b c 6, and
m = O to 5,
with the restriction that b-2a > 2.
Soluble lithium compounds, which are used as stabilizers in
halogenated polymer masses, are known to increase the water
absorbency of these resins. In the case of cable insulations
the insulating effect is deteriorated, and in the case of
pressurized water pipes the capacity of bearing the internal
water pressure is reduced. Lithium carbonate has no stabiliz-
ing effect, but lithium hydroxide has a good stabilizing ef-
fect, where however the initial color and the color distribu-
tion are unfavorably influenced- Lithium oxide exhibits the
same stabilizer properties with respect to halogenated poly-
mer masses as lithium hydroxide, but here as well the hydro-
philicity is disadvantageous- Stabilizer mixtures containing
lithium oxide have no storage stability. Furthermore, lithium
salts containing fatty acids, in particular stearic acid, are
known as PVC stabilizers- The document DE-A-1 115 460 dis-
closes a combination of lithium stearate and glycerol
mono(acetyl ricinoleate) for use as PVC stabilizers. However,
these stabilizers have not gained any commercial importance.
On the one hand, because a melting reaction of lithium
stearate is hardly possible (melting point of lithium
_ . _ . _ . _ _ ... . ... _ _ . . _ .. _ . . ... ..... . . . . _ _
~952~
5 -
stearate: 200 to 215~C), and on the other hand because the
production by means of a precipitation reaction requires
soluble lithium salts, such as the hydroxide or the chloride,
which are both comparatively expensive. In contrast to known
stabilizers, such as hydrated lime, magnesium and lithium hy-
droxide, the compounds in accordance with the invention do
not absorb carbon dioxide from air. In contrast to lithium
hydroxide, the inventive products are hardly soluble. In con-
trast to known hydrotalcites, they have a considerably re-
duced hydrophilicity, which is revealed by a reduced absorp-
tion of moisture from air.
Surprisingly, it was found that the substances in accordance
with the invention provide halogenated thermoplastic polymer
masses and the parts produced therefrom with an increased
thermal stability as compared to hydrotalcites or hydrocalu-
mites. The inventive substances prevent a discoloration in
the production of, for instance, rigid PVC extrudates. Both
the color distribution and the weathering resistance of the
specimens stabilized with the inventive substances are better
than in those specimens which do not contain the inventive
substances. In contrast to structurally comparable tribasic
lead sulfate, the transparency of transparent halogenated
resins is not impaired by using the inventive compounds.
Subject-matter of the invention furthermore is a process of
producing the inventive substances, in particular lattice
layer compounds, which is characterized in that in an aqueous
medium lithium hydroxide, lithium oxide and/or its compounds
convertible into hydroxide, metal~ hydroxides, metal~II)
oxides and/or their compounds of the above-mentioned metals
convertible into hydroxides, and aluminum- and/or iron(III)
hydroxides and/or their compounds convertible into hydroxides
as well as acids and/or their salts or mixtures thereof are
reacted with each other at a pH of 8 to 10 and at tempera-
' ~ - 6 - 2i~24~
tures of 20 to 250~C, and the solid reaction product obtained
is separated.
The reaction product directly obtained as a result of the
above-described reaction, can be separated from the aqueous
reaction medium according to known methods, preferably
through filtration. The processing of the reaction product ~z
separated is 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 aluminum, both finely divided active
metal(III) hydroxide in combination with sodium hydroxide and
also NaA102 can be used for the reaction. Lithium or one of :==
said metal(II) compounds can 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
thereof. The corresponding acid anions can be used in various
concentraticn6, e.g. directly as an acid, but also as a salt.
The reaction temperatures preferably lie in the range between
about 20 and 250~C, and in particular between about 60 and
180~C. Cataly6ts or accelerators are not required. In the
substances in accordance with the invention the crystal water
can wholly or partly be removed by means of a thermal treat-
ment.
When they are used as stabilizers, the dried lattice layer
compounds in accordance with the invention do not dehydrate
or evolve some other gas, co that there is no disturbing for-
mation of bubbles in the molded parts.
The anion of the general formula I, A , can be sulfate, sul-
fite, sulfide, thiosulfate, peroxide, peroxosulfate, hydrogen
phosphate, hydrogen phosphite, carbonate, halogenide, ni- -
' ~ 21g52~5
trate, nitrite, hydrogen sulfate, hydrogen carbonate, hydro-
gen sulfite, hydrogen sulfide, dihydrogen phosphate, dihydro-
gen phosphite, monocarboxylic acid anions such as acetate and
benzoate, amide, azide, hydroxide, hydroxylamide, hydrazide,
acetylacetonate, phenolate, pseudohalides, halogenites, halo-
genates, perhalogenates, I3 , permanganate, dianions of di-
carboxylic acids such as phthalate, oxalate, maleate or fu-
marate, bisphenolates, phosphate, pyrophosphate, phosphite,
pyrophosphite, trianions of tricarboxylic acids such as cit-
rate, trisphenolates, and many more, as well as mixtures
thereof. Of these, hydroxide, carbonate, phosphite and
maleate are preferred.
To improve the dispersibility of the inventive substances in
halogenated thermoplastic polymer masses, the same can be
surface-treated with a higher fatty acid, e.g. stearic acid,
an anionic surface active agent, a silane coupling agent, a
titanate coupling agent, or a glycerol fatty acid ester.
The inventive substances of formula I are suitable as stabi-
lizers for halogenated thermoplastic polymer masses. Examples
for such polymer masses are PVC, polyvinylidene chloride,
chlorinated or chlorosulfonated polyethylene, chlorinated
polypropylene or chlorinated ethylene/vinyl acetate-
copolymer. The inventive lattice layer compounds are particu-
larly suited as stabilizers for PVC-type polymer masses, i.e.
vinyl chloride homopolymers and copolymers of vinyl chloride
with other monomers.
In addition, known co-stabilizers, e-g. metal carboxylates
(group a~, can also be used advantageously
1,3-diketo compounds, or~anic esters of phosphorous acid, of
the polyols and of the amino acid derivatives (group b) lead
to a considerable improvement of the initial color. Moreover,
the addition of at least one substance (group c) selected
- 8 - 219~245
from the group including antioxidants and epoxy compounds can
lead to a considerable improvement of the color distribution.
The addition of at least one substance (group b) plus at
least one substance (group c) is very advantageous.
Examples for metal carboxylates (group a) include the salts
of higher fatty acids, naphthenic acid of metals of the sec-
ond group of the Periodic Table- Examples for suitable metals
of the second group include magnesium, calcium, strontium,
barium, zinc. Particularly advantageous are such salts of
higher fatty acids such as stearic acid, palmitic acid,
myristic acid, lauric acid, and ricinoleic acid. Zinc salts
are particularly efficient for the color distribution. There-
fore, preferably at least one part of a zinc salt of a higher
fatty acid is used. Although the above-mentioned metal car-
boxylates can be used individually, the effect can be in-
creased by using two or more metal carboxylates.
Examples for 1,3-diketo compounds include dibenzoylmethane,
stearoylbenzoylmethane, palmitoylbenzoylmethane, myristoylben-
zoylmethane, lauroylbenzoylmethane, benzoylacetone, acetyl-
acetone, tribenzoylmethane, diacetyl acetobenzene, p-methoxy-
stearoyl acetophenone, acetoacetic acid ester, and acetylace-
tone.
Examples for the esters of phosphorous acid include triaryl
phosphites such as triphenyl phosphite, tris(p-nonylphenyl)-
phosphite (TNPP); alkylaryl phosphites sUch as monoalkyl-
diphenyl phosphites, e-g- diphenyli800ctyl phosphite, diphen-
ylisodecyl phosphite; and dialkylmonophenyl phosphites, such
as phenyldiisooctyl phosphite, phenyldiisodecyl phosphite;
and trialkyl phosphites such as triisooctyl phosphite, tri-
stearyl phosphite.
~ ~ 2~9~2~
g
Examples for polyols include trismethylol propane, di-
(trismethylol propane), erythritol, pentaerythritol, dipen-
taerythritol, sorbitol, mannitol.
Examples for the amino acid derivatives include glycin,
alanine, lysin, tryptophan, acetylmethionine, pyrrolidone
carboxylic acid, ~-amino crotonic acid, ~-amino acrylic acid,
~-amino adipic acid, as well as the correspondLng esters. The
alcohol components of these esters include monovalent alco-
hols, such as methyl alcohol, ethyl alcohol, propyl alcohol,
i-propyl alcohol, butyl alcohol, ~-ethylhexanol, octyl alco-
hol, i-octyl alcohol, lauryl alcohol, stearyl alcohol, as
well as polyols such as ethylene glycol, propylene glycol,
1l3-butanedioll 1,4-butanediol, glycerol, diglycerol, tris-
methylol propane, pentaerythritol, dipentaerythrit
erythritol, sorbitol, mannitol.
Examples for 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),
stearyl-3-(3~-5~-di-t-butyl-4~-hydroxyphenyl)propionate~
The epoxy compounds include various animal or vegetable oil~
such as epoxy soy oil, epoxy rape-seed oil, epoxidized fatty
acid esters such as epoxidized epoxy methyl oleate, epoxy bu-
tyl oleate, epoxidized alicyclic substances, glycide ether
such as bisphenol-A diglycide ether, bisphenol-F diglycide
ether; glycide ester such as glycidyl acrylate, glycidyl
methacrylate, and the polymers and copolymers thereof; and
epoxidized polymers such as epoxidized polybutadiene, epoxi-
dized acrylic-acid-butadiene-styrene terpolymer (ABS).
Preferred metering ~uantities (in parts by weight per 100
parts by weight resin) for the inventive substances of for-
mula I are 0.1 to 5, preferably 0.5 to 3.
~ . 2~gS245
-- 10 --
Preferred metering quantities for the co-stabilizers are as
follows:
Group a) metal carboxylates: 0.1 to 5, preferably 0.5 to 3;
Group b) 1,3-diketo compounds, organic phosphites, polyols,
amino acid derivatives: O to 5, preferably 0.1 to 3;
Group c) antioxidants, epoxy compounds: 0 to 5,
preferably 0.05 to 4.
In particular combinations of inventive substances of formula
I and metal carboxylates are preferred as stabilizer mixtures
for halogenated polymer masses.
The stabilized halogenated thermoplastic polymer masses in
accordance with the invention can furthermore contain addi-
tives known to the man skilled in the art, such as fillers,
lubricants, plasticizers, dyes, pigments, antistatic agents,
surface-active agents, foaming agents, impact modifiers, UV
stabilizers.
What is common practice is in particular the addition of a
plasticizer. Dioctyl phthalate (DOP), aliphatic dibasic acid
esters, trimellitic acid esters, phosphate esters, fatty acid
esters, epoxy plasticizers, polyester plasticizers, chlorin-
ated paraffin and similar plasticizers may be added in appro-
priate quantity ratios, with reference to the halogenated
thermoplastic polymer mass.
~s molding methods, by means of which the stabilized, halo-
genated thermoplastic polymer masses in accordance with the
invention can be processed, calendering, extruding, injection
molding, blow molding or other methods may be mentioned.
The thermostability and the initial color as well as the
color distribution of halogenated thermoplastic polymer
masses are improved considerably by adding the inventive sub-
2~ 9~24~
-- 11 --
stances in accordance with formula I, in particular togetherwith metal carboxylates (group a) and preferably also to-
gether with co-stabilizers (group b) and/or (group c) in the
indicated quantities.
The stabilized polymer masses in accordance with the inven-
tion do not exhibit a plate-out phenomenon during calendering
and provide for long-term extrusion. In addition, the result-
ing products do not exhibit a discoloration. The present in-
vention therefore is a remarkable contribution to the pro-
cessing of P~C and other halogenated thermoplastic polymer
masses.
The invention will now be explained in detail by means of the
following Examples, but without being limited 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 a period of 30 min. 1-175 mol (96.4 g) anhydrous sodium
aluminate are dissolved in 700 ml water. 0.175 mol (7.3 g)
lithium hydroxide 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 35OC. After stir-
ring for one hour at room temperature, Co2 is introduced 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 six hours at about 185~C. The
reaction product is filtered by suction and three times
washed with two liters water, the filter cake i8 dried in a
~ ~ 219~2~5
- 12 -
vacuum for 14 hours at 130~C- Upon drying, glass-clear crys-
tals are obtained.
Product obtained: Lio~3sMg4~coAl2~3s(oH)l3~4co3
Analysis: ~10.49 % (calculated 0.54)
Mg20.90 % (calculated 21.30)
Al13.50 % (calculated 14.40)
C~29.60 % (calculated 9.80)
Example 2 (Compound 2)
1.55 mol (62.0 g) magnesium oxide are stirred in 600 ml water
for a period of 30 min. 1.275 mol (104.6 g) anhydrous sodium
aluminate are dissolved in 700 ml water. 0.275 mol (11.5 g)
lithium hydroxide 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 35OC. After stir-
ring for one hour at room temperature, CO2 is introduced 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 six hours at a pressure of 10
bar and a temperature of about 182~C in a 3UCHI laboratory
autoclave. The reaction product is filtered by suction and
washed three times with two liters water. The filter cake is
dried in a vacuum for 14 hours at 130~C. After the pressure
treatment glass-clear crystals are obtained.
Product obtained: Lio 5sMg3~loAl2~ss(oH)l2~4co3
Analysis: Li 0.89 % (calculated 0.91)
Mg 17.30 ~ (calculated 17.80)
Al 16.40 % (calculated 16.50)
C~210.20 ~ (calculated 10.50)
- 13 - 2~9~245
2. Production of non-inventive substances
Example 3 (compound 3)
1.65 mol ~66.0 g) magnesium oxide are stirred in 600 ml water
for a period of 30 min. 1 mol (82.0 g) anhydrous sodium alu-
minate is dissolved in 700 ml water. The MgO suspension is
added to the sodium aluminate solution. There is observed a
temperature increase to 35~C. 0.47 mol zinc sulfate
(anhydrous) are added, which were diseolved in 300 ml water.
After stirring for one hour, CO2 is introduced at room tem-
perature to a pH of 9Ø Upon carbonation, the excese CO2 is
concentrated to a pH of 10Ø The preparation is filled up to
a volume of three liters and treated for six hours at a pres-
sure of 10 bar and a temperature of about 182~C in a B~C~I
laboratory autoclave. The reaction product is filtered by
suction and washed three times with two liters water, the
filter cake is dried in a vacuum for 14 hours at 130~C. After
the pressure treatment, glass-clear crystals are obtained.
Product obtained: Mg3~3znc-sAl2.o(oH)l2~4co3*~2o
~nalysis: Mg 14.90 % (calculated 15.30)
Zn 12.70 % (calculated 11.40)
Al 10.20 % (calculated 10.40)
C~2 7.20 % (calculated 7.70)
3. Use of the inventive substances as stabilizers
In the subsequent examples, the thermal stability, initial
color and color distribution of molded PVC articles, to which
inventive substances as well as for comparison purposes no
co-stabilizers were added, are evaluated.
t ' .
2~952~
- 14 -
For this purpose, PVC polymer massee were homogenized on a
laboratory rolling mill for 5 minutes at 180~C and plasti-
fied. From the rolled sheet thus produced, which had a thick-
ness of about 1 mm, a test strip having a wLdth of 10 mm was
cut out and tempered in a MATHIS thermofurnace at 180~C. At
intervals of 10 min. the test strip was moved out of the fur-
nace for 23 mm, until blackening was revealed.
Table 1: Test formulations
Formulation 1 2 3 4 5 6 7
PVC 100 100100 100 100 100 100
Chalk 5 5 5 --- --- 5 --- =
Tio2 4 4 4 --- --- 4 ---
GM~) 0.5 0.50.5 --- --- 0.5 0.3
Bisphenol A 0.1 0.10.1 0.1 0.1 0.1 0.1
Irg. 17 MOKb) --- --- --- --- ---
Calcium stearate 0.5 0.5 0.5 0.8 --- 1 ---
Barium stearate--- --- --- --- 0.8 --- --- ---
Zinc stearate0.8 0.8 0.8 0.8 0.8 --- ---
Pentaerythritol 0.4 0.4 0.4 --- --- --- --
Dibenzoylmethane --- 0.1 --- --- --- --- --_
Calcium acetyl- -- --- 0.1 --- --- --- --_
acetonate
TNPP --- --- --- 0.5 --- -- --- --
DOP --- --- --- 40 40 --- 50
Specimen1 1 1 1 1 1 1 _~
~) paraffin wax as lubricant
b) Irga rod 17 MOK(Rl (Ciba-Geigy)
Table 2
Fommulation1 2 3 4 5 6 7
SubstanceMTT/min VDE/min MTT/min VDE/min MTT/min VDE/min MTT/min MTT/min MTT/min Y1 0/min MTT/min
Without specimen 47 12:00 50 13:25 60 14:30 40 40 105 7.2 110
Compound 1 75 17:25 80 18:50 85 18:00 55 65 135 6.5 160
Compound 2 85 18:50 95 20:00 100 19:15 80 70 155 6.6 210
Comparative
E~ample:
Compound 3 85 18:00 95 21:25 1W 19:00 80 65 155 9.6 200
Ul
MTT: MATHIS thermofurnace test
VDE: R~s;~ l stability (Congo Red Value)
Y10: Yellowness Index O min
