DE1494336C - Use of a stabilizer combination for the roll stabilization of olefin polymers - Google Patents

Description

connection

The invention relates to a use of a stabilizer combination from an organic phosphorus compound and an organic metal salt for the heat stabilization of olefin polymers.

Polypropylene is a tough, high-melting polymeric material, but some are resistant to it Leaves a lot to be desired. The polymer tends to drop rapidly in melt viscosity and embrittlement if it is used during the periods of time, which grinding, calendering, extrusion, Injection molding and fiber manufacturing processes require holding at elevated temperatures. This deterioration is particularly strong when the polymer is molten in the presence of oxygen, e.g. B. air is processed. Polymer moldings, which have been produced using methods of the type mentioned on suitable devices, tend to discolor, toss or warp, crack and pulverize around the edges when they are exposed to sunlight and age, especially when heated to moderately elevated temperatures, such as accelerated aging. In the presence of oxygen the problem becomes particularly acute.

Polypropylene is particularly susceptible to deterioration in physical properties when it is exposed to high temperatures, of the order of 150 ^° C. and above. Thermal cracking of the polypropylene appears to occur at such temperatures, and many of the stabilizers that improve resistance under other processing conditions tend to decrease the thermal cracking resistance of the polypropylene. Stabilizers which alone improve the high-temperature resistance are easily ineffective in the presence of stabilizers which are added to correct other tendencies to deteriorate. 'ι

The use of the following compounds to stabilize polyolefins is known: From the, ₀ triphenyl phosphite ...
Diphenyl phosphite ..;

Parts by weight

0.3 0.3

Melt index

(initially)

2.9 1.8

(after

30 min.

at 316 ° C)

6.3 over 100

This is shown by the extraordinarily high thermal load on the material in this experiment Triphenyl phosphite is clearly superior to diphenyl phosphite. It is therefore all the more surprising when when combining organic acidic phosphoric acid esters of phosphorous acids with metal soaps and optionally with further stabilizers, such as phenols, according to the present invention better results can be achieved than with the known, neutral triphosphite-containing combinations

,. options.

The invention relates to the use of a stabilizer combination

a) an organic phosphorus compound,

b) a metal salt of a polyvalent metal and an organic acid having 6 to 24 carbon atoms and possibly additionally

c) a known polyolefin stabilizer for heat stabilization of olefin polymers,

which is characterized in that an organic phosphoric acid ester of phosphorous acid, which is based on the structural formula of the phosphorous acid H ₃ PO ₃ and which contains at least 1 active hydrogen atom, is used as a).

The purity of propylene polymers, the degree of degradation and the resistance to embrittlement at elevated temperatures for long periods of time represent properties, their evaluation on the basis of an observation of the change in the melt index of the polymer under the action of certain Temperatures during a certain period is possible. The strength of the melt index increases and the degree of deterioration in the above physical properties of the polymer are directly related.

IO

The stabilizer combinations used according to the invention set the rate of increase in the melt index significantly decrease at elevated temperatures and also result in an improvement in the Color fastness and other important physical properties of the propylene polymer.

The organic phosphoric acid esters of phosphorous acid used according to the invention can by the formula

y. \

POH

being represented. In this formula / denotes an organic radical or radicals which are located on the phosphorus via an oxygen atom. The radical / can form a heterocyclic ring which contains the phosphorus atom, represent two organic radicals which are attached to the trivalent phosphorus via oxygen, and also have an additional OH group.

These compounds are known and can be defined in terms of a formula. They can be in the form of trivalent Phosphorus and an acidic hydroxyl group

Ρ —Ο — Η Typical organic phosphoric acid esters of phosphorous acid within the scope of this general formula are:

R ₁ O

POH

R ₂ OR ₁ O

b) POH HO

c) _{/ 0} HR ₂ O

d) POH R ₇

or in the four-bond tautomeric form with a P-H bond

35

are illustrated, and they can be understood as tautomeric mixtures which contain both forms in Balance included. A characteristic that these not fully esterified phosphorous acids of the tertiary phosphites and analogous compounds of trivalent phosphorus, such as the complete esterified phosphites, phosphinites and tertiary phosphines is made up of - like in the formula

7 \

POH e)

HO

POH

II, a)

POH

POH

HI, a)

HOP - OR ₁

"0-R ₄ -OP

OR ₂

OH

shown - in the presence of at least one active hydrogen atom (which in a determination according to Zerewitinoff can be replaced by metals such as sodium or the Grignard reagent). According to the invention used, organic phosphoric acid esters of phosphorous acid differ from the organic phosphoric acids by reacting with oxidizing agents under certain conditions with formation of the corresponding phosphoric acid derivatives which contain an additional oxygen atom. For a more detailed discussion of the structure and reactions of the esters of phosphorous acids, to G. M. Kosolapoff, "Organo-phosphorus Compounds", John Wiley & Sons, New York, 1951, especially p. 144 and p. 193 to 195, referenced.

b) HO-P-To-R ₄ -OP

Ri

OH

c) R ^ _{/ P} -

0-R ₄ -OP

OR ₁

OH

O— R, - Ο— Ρ

OH

he;

V /
O

P—

0-R ₄ -OP

OR ₁

OH

f) R;

OR ₄ -OP

OH

In these formulas, R ₁ and R _{2 are} monovalent ίο organic aliphatic, aromatic and non-aromatic, alicyclic hydrocarbon or heterocyclic radicals having 1 to about 30 carbon atoms and R ₃ and R _{4 are} divalent organic aliphatic, aromatic or non-aromatic alicyclic hydrocarbon or heterocyclic radicals Radicals having 2 to about 30 carbon atoms. R ₁ and R ₂ in the formulas of groups I and III can be identical or different.

The compounds of group III are polymeric in nature, where η indicates the number of recurring units mentioned in brackets, η can have a value in the range from 1 to about 30.

All of these compounds are organic phosphoric acid esters of phosphorous acid, in which at least one replaceable hydrogen atom in the molecule and preferably one replaceable hydrogen atom present per phosphorus atom of the organic phosphorous acid. The compounds of groups I and II thus represent preferred compounds according to the invention.

Examples of the Group I compounds are

Di (phenyl) phosphite,
Monophenyl phosphite,

Mono- (diphenyl) phosphite, HO

Dicresyl phosphite,
Di- (o-isooctylphenyl) phosphite, di- (p-ethylhexyl-phenyl) -pnosphite, di- (p-tert-octyl-phenyl) -phosphite, di- (dimethyl-phenyl) -phosphite, di-n -butyl-phosphite,
Di-2-ethylhexyl phosphite,
Mono-2-ethylhexyl phosphite, diisooctyl phosphite, monoisooctyl phosphite,
Monododecyl phosphite,
. 2-ethylhexyl-phenyl-phosphite, 2-ethylhexyl- (n-octylphenyl) -phosphite, monocyclo-hexyl-phosphite, dicyclohexyl-phosphite,
Di- (2-cyclohexyl-phenyl) -phosphite, di-a-naphthyl-phosphite,
Diphenyl-phenyl-phosphite,

Di- (diphenyl) -phosphite, di- {2-phenyl-ethyl) -phosphite,

Dibenzyl phosphite, HO

Monobenzyl phosphite,
n-butylcresyl phosphite,

Didodecyl phosphite,

Ditetrahydrofurfuryl-phosphite, and

Difuryl phosphite,
benzenephosphonous acid,
Mono-2-ethylhexyi-benzene phosphonite, monophenyl butane phosphonite, mono 2-butoxyethyl a-naphthalene phosphonite, mono-n-octyl cyclohexane phosphonite, a-toluene phosphonous acid,

diphenyl phosphinous acid,
dibutyl phosphinous acid,
Benzylmethylphosphinous acid.

Examples of Group II compounds are

Ethylene phosphite,

Propane-1,3-cycL-phosphite,

l-methyl-propane-l ^ -cycl.-phosphite,

2,2-dimethylpropane-1,3-cycl.-phosphite,

1,3-diphenylpropane-1,3-cycL-phosphite,

Butane-l ^ -cycL-phosphite,

4-methylbutane-1,3-cycl.-phosphite,

S-methylbutane-l ^ -cycl.-phosphite,

4-phenylbutane-1,3-cycl.-phosphite,

3-cyclohexylheptane-l, 3-cycL-phosphite,

1,3,7-triisopropylheptane-1,3-cycl.-phosphite and Cyclohexane-l ^ -cycl.-phosphite.

Examples of compounds within groups III, a) and III, b) are those in which R _{4 is} neopentylene, ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene, 1,3-butylene , Pentamethylene, hexamethylene, octamethylene, decamethylene, cyclohexylene, n-butylidene and diphenylmethane. In these compounds, R ₁ and R _{2 can be} hydrogen, methyl, ethyl, propyl, butyl, isopropyl, isobutyl, isoamyl, phenyl, cyclohexyl and naphthyl.

Examples of compounds of group III, b) are those compounds in which R ₁ and R _{4 are} one of the groups mentioned above in connection with III, a) and III, b) and R _{3 is} one of the radicals of the compounds of group II .
Examples of group III, a) are

-PO
0

C ₄ H ₉

O-

POH O

C ₄ H ₉

O-

Examples of group III, b) are

-P-O

C ₄ H ₉

O-

HO

-P-O

O-

Examples of groups III, c), III, d), III, e) and III, f) are

HO

- P

CH

HO

HO

—Ρ — ο

C ₂ H ₅

HO

OC ₃ H ₇

HO

- P

(C ₃ H ₆ )

LC ₃ H ₇

- P

C ₃ H ₆ O

C = O

The polyvalent metal of the metal salt is any metal from group II of the penode system Elements into consideration, such as zinc, calcium, cadmium, barium, magnesium and strontium. The alkali salts and heavy metal salts such as lead salts do not give satisfactory results. The acid can be a any organic, non-nitrogenous monocarboxylic acid having 6 to 24 carbon atoms. The aliphatic, aromatic, alicyclic and oxygenated heterocyclic organic acids are suitable as a class. "Aliphatic acid" is any open chain carboxylic acid to understand, if desired, with non-reactive groups such as halogen, sulfur and hydroxyl, may be substituted. Under »alicy-

every cyclic acid is to be understood clisch, whose

Ring is not aromatic and consists solely of carbon

- atoms are formed; if desired, such

Acids have inert, non-reactive substituents such as halogen, hydroxyl, alkyl and alkenyl and condensed with other carbocyclic ring structures. The oxygen-containing heterocyclic ones Compounds can be aromatic or non-aromatic in nature and can be in the ring structure Contain oxygen and carbon, like the alkyl-substituted Furancarboxylic acid. The aromatic acids can be unreactive in the same way Ring substituents such as halogen, alkyl and alkenyl,

309 630/147

have and condensed with other saturated or aromatic rings.

The "water-insoluble" salts are preferred because they do not leach out when the plastic comes into contact with water will. These salts can be obtained by the usual types of reaction, such as mixing the Acid, acid chloride or acid anhydride with the corresponding oxide or hydroxide of the Metal in a liquid solvent and, if necessary, heating until complete salt formation.

The stabilizer combination used according to the invention is on its own for the stabilization of Olefin and especially propylene polymers ^ effective. Their effectiveness is particularly evident an increased resistance to an increase in the melt index when exposed to elevated temperatures. The new stabilizer combination can also be used in conjunction with other propylene polymer stabilizers can be used to achieve technical advantages.

In many cases an enhanced or synergistic effect is obtained. To such additional Stabilizers include, for example, phenols, organic triphosphites, thiodipropionic acid esters, organic Mercaptans and organic polysulfides.

When the stabilizer consists of an organic phosphoric acid ester of phosphorous acid and a Salt of a polyvalent metal is used in conjunction with a phenol, which shows the enhanced Stabilizing effect on an improved resistance to yellowing and on a long one Lifetime, which in the form of resistance to embrittlement and the formation of stickiness elevated temperatures is expressed. The phenol stabilizers contain one or more phenolic groups and can have one or more phenolic nuclei. The phenolic nucleus can over it also have an oxy or thioether group.

The alkyl-substituted phenols and the polynuclear phenols, which have a higher boiling point, are preferred because of their lower volatility. It can be a single alkyl group or there are a number of alkyl groups having 1 or more carbon atoms. In the alkyl group or the alkyl groups including all alkylene groups between phenol nuclei are preferred at least 4 carbon atoms gathered. The compatibility with polypropylene is all the better The longer the alkyl or alkylene chain is because the phenolic compound then has stronger character of an aliphatic hydrocarbon, and the number of alkyl carbon atoms is accordingly not limited. In terms of availability, the connections usually have a Alkyl, alicyclidene, and alkylene groups no more than about 18 carbon atoms and no total has more than about 50 carbon atoms. The compounds can have one to four alkyl radicals per phenol nucleus exhibit.

With the bicyclic phenols, which due to ijirer superior stabilizing effect are preferred, the rings can through. Thio or oxyether groups or be linked by alkylene, alicyclic or arylene groups.

When the stabilizer consists of organic phosphoric acid ester of phosphorous acid and salt of polyvalent Metal is used in conjunction with triphosphite, the increased effect is evident an elimination of the relatively large amounts of triphosphite otherwise produced by aging Discoloration. This enables larger amounts of triphosphite to be used.

The triphosphite can be any organic triphosphite which is attached to phosphorus via oxygen or Sulfur or a mixture of the same three groups in the form of aryl, alkyl, cycloalkyl, aralkyl or Alkaryl groups are seated in any combination. The term "organic phosphite triester" includes here oxo-, thio- and mixed oxo-thio-phosphites. Usually the phosphite has no more than about 60 carbon atoms.

If the stabilizer consists of organic phosphoric acid ester of phosphorous acid and salt of polyvalent metal used in conjunction with a thiodipropionate shows the improvement significantly longer resistance to embrittlement and stickiness elevated temperatures. The thiodipropionate or the thiodipropionic acid ester has the formula

R ₁ 0 OCCH ₂ CH ₂ - S - CH ₂ CH ₂ CO OY

Here, R _{1 is} an organic radical R in the form of hydrocarbon radicals, such as alkyl, alkenyl, aryl, cycloalkyl, mixed alkyl-aryl and mixed alkyl-cycloalkyl, hydroxyalkyl and hydroxyoxyalkylene and esters thereof with aliphatic carboxylic acids and Y is (a) hydrogen, (b) a second R radical R ₂ , which can be the same or different from the radical R ₁ , (c) a polymeric chain of η thiodipropionate units of the formula

R ₁ 0 [OCCH ₂ CH ₂ SCH ₂ CH ₂ COOX OL ₁ OCCH ₂ CH ₂ - SCH ₂ CH ₂ COOZ

wherein Z is hydrogen, R ₂ or M, η is equal to the number of thiodipropionate units in the chain and X is a divalent hydrocarbon group of the type of R ₁ and the value of η can be greater than 1, with the exception of the determination by the ratio of carbon to sulfur atoms in the manner mentioned below does not give an upper limit for η, or (d) a polyvalent metal M of group II of the periodic table of the elements, such as zinc, calcium, cadmium, barium, magnesium and strontium.

The molecular weights of the radicals R and Y are chosen so that the thiodipropionate together with the remainder of the molecule has a total of about 10 to 60 carbon atoms each has sulfur atom.

The R group of these esters is important to obtain compatibility with the polypropylene. The radical Y is expediently another radical, R ₂ or N or a polymer, where R has a fairly low molecular weight, in order to achieve a balance in this way with regard to achieving the optimum compatibility and non-volatility.

When Y is a metal, the thiodipropionate provides the beneficial properties of the polyvalent salt Metal described above.

The aryl, alkyl, alkenyl and cycloalkyl groups

can, if desired, be inert or non-reactive Have substituents, such as halogen and other carbocyclic and heterocyclic ring structures, that are condensed with them.

These thiodipropionates are for the most part known compounds and can be, as far as not available, easily by esterification of thiodipropionic acid with the appropriate alcohol.

The stabilizer combination preferably used according to the invention has five stabilizers, the organic phosphoric acid ester of phosphorous acid, the salt of the polyvalent metal and an organic acid, a polyvalent phenol, a triphosphite and a thiodipropionate. These five stabilizers together result in increased stabilization that cannot be achieved with any three individual stabilizers or in combinations of four. The components of this stabilizer system alone can only inhibit deterioration in one or two respects, and very large ~ -. Quantities may be necessary before any effect J can be observed. The components which do not represent an organic phosphoric acid ester of phosphorous acid or a salt of the polyvalent metal can exhibit a lower stabilizing effect than each component alone. The phenol alone e.g. B. provides improved resistance to embrittlement and lowering of melt viscosity at elevated temperatures, but is of little value in terms of retention of color. The triphosphite alone is a rather poor stabilizer in terms of preventing the deterioration of the former two properties, but it assists in the resistance to discoloration. The thiodipropionate itself only improves resistance to embrittlement. The polyvalent salt of an organic acid itself prevents discoloration, but has no other effect. In combination with the phenol, the coloring is worse than when the salt is used alone. In combination with the triphosphite, the usual discoloration is prevented, but black spots can appear on aging if the triphosphite concentrations are high.

In view of this, it is surprising that the organic phosphoric acid ester of phosphorous acid, the polyvalent metal salt, the phenol, the triphosphite and the thiodipropionate together in the same amount not only prevent discoloration, but also embrittlement inhibit and the increase in the melt index at the working temperatures below those accompanying them Resistance to deterioration in physical properties and also resistance to Increase discoloration and embrittlement with aging just as much beyond the level that comes with the components are available individually. This increased stabilizing effect is used with every propylene polymer obtained regardless of the method by which it was made.

A very small amount of the stabilizer combination of the organic phosphoric acid ester of the phosphorous Acid and the salt of the polyvalent metal are sufficient with or without an additional stabilizer, resistance to deterioration in physical properties including e.g. B. the resistance to discoloration, to improve under the conditions which the olefin polymer is subjected. Quantities in the range from about 0.005 to 2.5% of the weight of the polymer lead to a satisfactory discoloration resistance at elevated temperatures. To achieve an optimal Stabilization is preferred in an amount of 0.01 to 1%.

If additional stabilizers are used to achieve additional stabilizing effects, the total amount of stabilizer is in the range from about 0.005 to 5, preferably 0.1 to 2.5%.

The stabilizer system preferably contains about 0.001 to 0.25% of an organic phosphoric acid ester the phosphorous acid, about 0.025 to 0.75% of a salt of the polyvalent metal, about 0.025 up to 0.5% of a phenol, about 0.01 to 0.5% of a triphosphite, and about 0.05 to 1% of a thiodipropionate.

The stabilizer combination can be prepared as a simple mixture provided by the polymer manufacturer or processor is incorporated into the polymer. If the ingredients are not homogeneous Forming mixture or solution, one can manipulate by using an inert, organic Solvent easier.

The stabilizer combination according to the invention is applicable to olefin polymers, which after each the known processes using the available catalysts. you are effective with olefin polymers which are essentially free of catalyst residues but also with the achievement of good results in the case of catalyst-containing polymers use.

An example of a sterically regular polypropylene is an isotactic polypropylene, which has a softening or has a hot working temperature of about 177 ° C. The solid propylene polymer can to distinguish it from other polyolefins by a density in the range from 0.86 to 0.91 and one Melting point of over 150 ° C can be defined. the Stabilizer combinations which can be used according to the invention are in the case of all such polypropylenes Difference from polypropylenes in liquid form or in semi-liquid or gel-like forms like them are used as fats and waxes. Mixtures of olefin polymers, such as propylene polymers, with other compatible polymers and copolymers of propylene with copolymerizable monomers such as ethylene and butene can also be used according to the invention be stabilized. For example, one can add an organic phosphoric acid ester the phosphorous acid and a salt of the polyvalent metal, if desired in combination with other propylene polymer stabilizers, mixtures of polyethylene and polypropylene and copolymers stabilize propylene and ethylene. The term "propylene polymer" includes in corresponding to the sense used here homopolymers, such as polypropylene, and propylene copolymers as well as, as discussed above, mixtures of propylene polymers.

The stabilizer combinations used according to the invention can also be used with low-density polyethylene, Ziegler polyethylene, high-density polyethylene, Polybutene-1, poly-3-methylbutene-1, poly-4-methylpentene-1 and polystyrene are used. The term "olefin polymers" includes both homo-

as well as copolymers as well as mixtures of olefin polymers.

The stabilizer combination is added to the polymer on a suitable mixing device, such as a Incorporated into a grinder or a Banbury mixer. If the melt viscosity of the propylene polymer is too high for the desired use, the propylene polymer can be processed until its melt viscosity is reduced to the desired range before adding the stabilizers clogs. However, there are now propylene polymers with suitable for processing Melt viscosities available. Mixing is continued until the mixture is substantial is even. The resulting mass is then removed from the mixer and placed on the for brought to distribution or use of the desired size and shape. The stabilized olefin polymer can, such as by milling, calendering, extrusion, injection molding or fiber production, in the desired Wise to be written. The resin shows considerably improved durability in such work . against a decrease in melt viscosity during heating and generally gives better resistance against discoloration and embrittlement during aging and heating. .

The stabilizing effect of the stabilizer combination used according to the invention is evaluated in the following examples using a modified test method (ASTM test standard D 1238-57 T) to determine the melt index. The determination takes place when the “plastometer” flask is loaded with 2160 g, the melt index being compared ^{before and after heating the polymer in a mold to 316 ° C. for 30 minutes.} The temperature of 316 ⁰ C is chosen as the extreme value, and. stability at this temperature during the test period ensures that the resin will withstand lower temperatures for periods of considerable length. The change in the melt index during this period is an exact measure of the degree of heat resistance achieved with the added stabilizer, regardless of the numerical value of the initial melt index of the various samples of a given polymer. The lower the ratio, the smaller the change and the greater the stabilizing effect.

example 1

According to the invention diphenyl phosphite and of zinc 2-ethylhexoate in the proportions according to Table I weighed and dispersed by stirring by hand in 'powdered, hitherto not yet stabilized polypropylene in the acquired form a melt index of 3.0 at 23O ⁰ C (ASTM test standard D 1238-57 T). In each case, the mixture obtained is applied to a two-roll grinder and subjected to flow treatment at 170 ± 2 ° C. for 5 minutes.

The stabilized polypropylene (sample B) is mixed with an unstabilized sample (A) of the same polymer compared by placing pieces cut from a ground hide of each sample mass in the in the manner described above.

Table I.

Polypropylene

Diphenyl phosphite

Zinc 2-ethylhexoate

Melt index
M ₁

M ₃₁₆ = C '

M ₃₁₆ o _C

Heat aging at 150 ^° C
Hours to failure

Sample (parts by weight)

AWAY

100

3.0 67.1

22.4

100 0.1 0.05

3.0

15.4

5.1

12th

These values clearly show that the diphenyl phosphite and zinc 2-ethylhexoate improve the resistance of the polymer against deterioration in degradation upon prolonged exposure to elevated temperatures. The melt index ratio of the polymer containing the diphenyl phosphite and zinc 2-ethylhexoate contains is lower than that of the polymer not stabilized according to the invention.

B e i s ρ i e 1 2

A polypropylene that is stabilized by means of dilauryl thiodipropionate is further improved by adding diphenyl phosphite and zinc 2-ethylhexoate. Table II is weighed from the stabilizers according to and dispersed by stirring them by hand in 100 parts of powdered, not previously stabilized polypropylene in the acquired form a melt index of 3.0 at 230 ⁰ C (ASTM test standard D 1238-57 T ) has. 0.5 part of dilauryl thiodipropionate is added by hand to each polymer sample while stirring; a further 0.1 part of diphenyl phosphite and 0.1 part of zinc 2-ethylhexoate are added to sample D according to Table II. In each case, the mixture is applied to a two-roll grinder and subjected to flow treatment at 170 ± 2 ° C. for 5 minutes. Pieces cut from the ground hide are used in the tests.

Table II

Polypropylene

Dilauryl thiodipropionate ....

Diphenyl phosphite

Zinc 2-ethylhexoate

Melt index
M ₁

M ₃ i6 ° C

M ₃₁₆ OcZM ₁

Heat aging at 150 ^° C
Hours to failure

Sample (parts by weight)

C D

100 0.5

2.7 31.5 11.7

14.0

100 0.5 0.1 0.1

2.8

25.7

9.2

135.5

These values clearly show that the diphenyl phosphite and zinc 2-ethylhexoate improve the resistance of the polymer against deterioration in degradation upon prolonged exposure to elevated temperature. The melt index ratio of the polymer containing the diphenyl phosphite is lower.

Example 3

Polypropylene alone and polypropylene stabilized by means of di-tert-butyl-p-cresol are further improved by adding 2,2-dimethylpropane-1,3-cyclic phosphite and cadmium stearate. The stabilizers according to Table III are weighed and distributed powdered by stirring by hand in 100 parts not yet stabilized polypropylene having a melt index of 1.0 at 23O ⁰ C in the acquired form (ASTM test standard D 1238-57 T). In some cases, 0.25 part of di-tert-butyl-p-cresol is used; in two cases, 0.1 part of 2,2-dimethylpropane -1,3-cycl. - phosphite added (Table III). In each case, the mixture is applied to a two-roll grinder and subjected to flow treatment at 170 ± 2 ° C. for 5 minutes. Pieces cut from the ground hide are used in the tests.

Table III E. F. sample
(Parts by weight)
G - H J 100 100
0.1 100.
0.1 100
0.25 100
0.25
0.1
0.1, Polypropylene Di-tert-butyl-p-cresol ... 2,2-dimethylpropane-1,2-cyclic phosphite
Cadmium stearate

The results show that the addition of an organic phosphorous acid and a salt of the polyvalent metal according to the invention, the resistance of the polymer to deterioration in degradation increased with prolonged exposure to elevated temperatures. With the addition of phosphite and the salt of the polyvalent metal to the phenol-containing polymer will decrease the resistance to deterioration in degradation when exposed to elevated temperatures resulting from the phenol addition results, overcome. In addition, no discoloration can be observed. The organic Phosphorous acid and the salt of the polyvalent metal are thus also in combination with stabilizers of value, while retaining some other physical properties of a polymer but its high temperature resistance is reduced.

Example 4

A range of polypropylene compositions are made with a combination of stabilizers are stabilized according to the invention. Before incorporation with the metal salt and the thiodipropionic acid ester The triphosphite and bisphenol are premixed into the polymer to ensure separation to avoid bisphenol. The concentrates of bisphenol and triphosphite are with the Zinc-2-ethylhexoate and dilaurylthiopropionate mixed. Equal proportions of this stabilizing mixture are weighed and distribute them by stirring by hand in powdered, not yet stabilized Polypropylene.

The polypropylene stabilized in this way is mixed with similarly stabilized polypropylene, diphenyl phosphite or dioctyl phosphite or zinc 2-ethylhexoate have been added, with the polymer by itself and compared with the polymer made with diphenyl or dioctyl phosphite or zinc 2-ethylhexoate has been stabilized alone.

Table IV

L. M. N O sample (Parts by weight) R. S. T U V K 100 100 100 100 P. -Q 100 100 100 100 100 100 . __ - - _ 100 100 0.14 0.28 0.28 0.28 0.28 - - - 0.06 0.06 0.14 0.14 0.06 0.12 0.12 0.12 0.12 - - - - - 0.06 0.06 0.05 0.10 0.10 0.10 0.10 - -. - - 0.05 0.05 0.25 0.5 0.5 0.5 0.5 0.1 - - , 0.1 0.25 0.25 0.1 - 0.05 0.10 - - - 0.1 - - - 0.05 - - - - 0.10 - 3.7 5.1 12.9 3.7 - - ■ 2.7 2.7 2.7 2.7 2.9 3.0 31.4 38.3 88.0 25.2 3.1 2.7 22.4 43.2 .24.0 20.0 23.0 84.2 34.3 11.9

Polypropylene

Isooctyl diphenyl phosphite

Zinc 2-ethylhexoate
4,4'-butylidene-bis- (2-methyl-5-tert.-
butyl-phenol ....
Dilaurylthio

dipropionate

Diphenyl phosphite
Dioctyl phosphite ...

100

26.3 309 630/147

A comparison of the above-mentioned melt indices obtained in these tests shows that the organic Phosphorous acid and zinc 2-ethylhexoate together improve the heat resistance of polypropylene noticeably improve in combination with the other stabilizers; discoloration does not occur. The stabilizers according to the invention can thus be used in an effective manner to the Resistance of polypropylene to degradation under long-term exposure to high temperatures during hot working, calendering, forming, etc. to improve.

Example 5

As in Example 4, polypropylene stabilizer combinations according to Table V are produced. Diisooctyl phosphite is used as the organic phosphorous acid. Weigh the stabilizer components, and they are dispersed by stirring by hand in powdered, not previously stabilized polypropylene in the acquired form a melt index of 3.0 at 23O ⁰ C was (ASTM test standard D 1238-57 T). The mixture is applied to a two-roll grinder and subjected to flow treatment at 170 ± 2 ° C. for 5 minutes. Pieces cut from the ground hide are used in the tests.

Table V

Polypropylene

Isooctyldiphenylphosphite ...

Zinc 2-ethylhexoate

4,4'-thiobis- (2-tert-butyl-

3-methylphenol

Dilauryl thiodipropionate ....
Diisooctyl phosphite

Melt index

M ₃ I ₆ -C · · -

Aging at 150 ^° C

Hours to failure

sample
(Parts by weight)

X Y-

100
0.28
0.12

0.10
0.50

159

429

100
0.28 0.12

0.10 0.50 0.1

117
595 are each placed on a two-roll grinder and subjected to flow treatment at 170 ± 2 ° C. for 5 minutes. Pieces cut from the ground hide are tested as in the earlier examples. *

Table VI

sample AA 100 (Parts by weight) Polypropylene Z Interesterified mixture of 100 Triphenyl phosphite, 4,4'-n-butylidene-bis- (2-tert-butyl-5-methyl- 0.42 phenol) and tridecyl 0.25 alcohol 0.08 Dilauryl thiodipropionate .... 0.5 0.08 Diphenyl phosphite 0.25 Zinc 2-ethylhexoate - 16.8 Melt index - M ₃₁₆ -C 41.6

As shown by the lower melt index and the lack of discoloration, this gives diphenyl phosphite and zinc 2-ethylhexoate a noticeable reduction in the degradation decomposition of the polypropylene Exposure to heat.

Example 7

Commercial polypropylenes are compared with polymers containing di- (octylphenyl) phosphite and Strontiunilaurate according to the invention have been incorporated in the proportions according to the following table:

Table VII

The diisooctyl phosphite results in a considerable increase in the resistance of the polymer against Deterioration of degradation and eliminates the discoloration, which increases the thermal resistance of the polymer indicates.

Example 6

A polypropylene, which with triphenyl phosphite, which with 0.5 mole of n-butylidene-4,4'-bis- (2-tert-butyl-5-methylphenol) and 2 moles of tridecyl alcohol was reacted, in combination with dilauryl thiodipropionate is stabilized, is compared with a polymer stabilized in this way, the diphenyl phosphite and zinc 2-ethylhexoate as an additional stabilizer.

The stabilizers are weighed out and added in the proportions given in Table VI by stirring Hand dispersed in powdered, not yet stabilized polypropylene. The mixtures obtained

Polypropylene 1 ..
Polypropylene 2 ..

Di- (octylphenyl) -

phosphite

Strontium laurate.

sample DD (Parts by weight) BB CC 100 100 100 - - '- ■ - - 0.1 - 0.1

The lack of discoloration after prolonged exposure to elevated temperatures as well as the lower increase of the melt index, which can be determined from a comparison of the final melt indices, shows that the Addition of di (octylphenyl) phosphite and strontium laurate to these commercial polypropylenes the heat resistance thereof is markedly improved.

Example 8

In powdered, non-stabilized polypropylene, the values given in Table VIII below are used Quantities of phosphite, phenol and metal salt weighed in and dispersed by stirring; Samples have the following composition:

Table VIII

composition

YY

Polypropylene

2,6-di-tert-butyl-p-cresol

Zinc octoate

Tri-isooctyl phosphite ....
Di-isooctyl phosphite ....
Mono-isooctyl phosphite.

100
0.2
0.05
0.108

100
0.2
0.05
0.05

100
0.2
0.05

0.05

'100 0.2 0.05

0.05

0.108 parts of triisooctyl phosphite and 0.05 parts of monoisooctyl phosphite contain equivalent proportions of phosphorus. .

The samples so prepared were in each case

Example9

The following samples, which were prepared and tested in the same way as in the case

Put on a two-roller mill, 5 minutes at 20 game 8, confirm this result: 170 ± 2 ° C milled and peeled off as a hide. From the rolled sheets were cut pieces of ASTM D 1238-57 T Table X Test method used at 230 ⁰ C to determine the melt index according to;

Table IX

Melt index FF GG HH YY M ₁ (initially) ....
M ₃₁₆ Oc (30 min.) ..
M ₃₁₆ »c / M, .... 2.7
19.8
7.33 3.0
18.5
6.17 3.3
13.1
3.97 4.7
12.5
2.66

As the data in Tables VIII and EX show, samples HH and JJ according to the invention are den Samples FF and GG far superior in preventing melt index increase; so shows the Sample HH containing diisooctyl phosphite had a melt index ratio after 30 minutes at 316 ° C of 3.97, which is about 85% lower than that of sample FF (7.33) and about 55% lower than that of sample GG (6.17), and the monoisooctyl phosphite Sample JJ containing sample shows a melt index ratio of 2.66 after 30 minutes at 316 ° C, which is about 175% lower than that of Sample FF and 130% lower than that of Sample GG. This clearly shows that a trialkyl phosphite according to British patent specification 876 443 and a diphosphite such as the French patent 1235 047 disclosed are in no way to be regarded as equivalents be able.

² 5 Composition KK LL MM Polypropylene
2,6-di-tert-butyl
₃₀ p-cresol
Zinc octoate
Tri-isooctyl phosphite ...
Diphenyl phosphite 100
0.2
0.05
0.096 100
0.2
0.05
0.05 100
0.2
0.05
0.05

35

0.096 parts of triisooctyl phosphite contain the same amount of phosphorus as 0.05 parts of diphenyl phosphite is available.

40

Table XI LL MM Melt index 2.7
37.6
13.9 3.0
25.1
8.36 ⁴⁵ μ, ......... M ₃₁₆ ° c (30 minutes)
M ₃₁₆ OcZM ₁ KK 3.6
46.4
12.9

50

These results also show that the melt index ratio of the sample MM, which according to the invention which contains acid phosphite, is considerably lower than that of samples KK and LL, which are a contain neutral triphosphite.

Example 10

A further series of tests shows the surprising superiority of the combination according to the invention, containing acidic phosphites, in the so-called “NO ₂ test”, which essentially represents an accelerated aging test. Nitrogen dioxide is found as a combustion product in the air in the vicinity of industrial plants, and its oxidizing and, in the presence of water, acidic and therefore similar to nitric acid effects on plastics such as polypropylene, is a characteristic of the aging properties and service life when used outdoors. Five samples of the following composition are prepared:

Table XII

. composition NN ⁰⁰ PP
(Parts by weight) QQ RR Polypropylene 0.05
0.096 100
0.2
0.05
0.05 100
0.2
0.05
0.066 100
0.2
0.05
0.05 100
0.2-
0.05
0.05 2,6-di-tert-butyl-p-cresol
Zinc octoate Tri-isooctyl phosphite
Triphenyl phosphite
Di-phenyl phosphite

The samples are made into pelts as described above and each of these _{pelts is exposed to NO 2} vapors for 15 minutes to 24 hours and the color of each sample is determined. The following table XIII summarizes the results:

Table XIII,

Time of suspension
against NO ₂ vapors NN OO sample
PP OQ RR 0 colorless
bright
brownish gray
yellowish
yellowish colorless
bright
brownish gray
yellowish
yellowish colorless
brownish gray
brownish gray colorless
brownish gray
brownish gray colorless
colorless
colorless
very bright
yellowish 15 minutes
2 hours
24 hours .

As the results show, the change in color in samples NN to QQ is sufficiently strong to prevent the To make samples unsuitable for economic use unless they are made with darker ones Tones are colored. The sample RR according to the invention, on the other hand, only shows after 24 hours of exposure a slight discoloration.

Claims (2)

Patent claims: 1. Use of a stabilizer combination out . . a) an organic phosphorus compound, b) a metal salt of a polyvalent metal and an organic acid having 6 to 24 carbon atoms and possibly additionally c) a known polyolefin stabilizer for the heat stabilization of olefin polymers, " characterized in that an organic phosphoric acid ester of phosphorous acid, which is based on the structural formula of phosphorous acid H ₃ PO ₃ and which contains at least 1 active hydrogen atom, is used as a). 2. Embodiment according to claim 1, characterized in that as c) ein.phenolischer stabilizer, a triphosphite or a thiodipropionate is used. Belgian patent 554,304 trialkyl and traryl phosphites; from French patent specification 1,186,789 triphosphites and metal soaps; from the British Patent 876443 and German Auslegeschrift 1065 170 triphosphites and metallic soaps and phenols; according to a report in Chem. Zentralblatt 196,3, p. 3785, are dialkyl and diaryl phosphites alone and also in a mixture with antioxidants as well as according to the French patent specification ίο 1 235 047 di- or triphosphites together with phenols or thiodipropionic acid esters have been used. Already leaves the latter patent on Comparison of the test temperatures in Examples 1 and 2 and in Example 5 assume that organic .15 Diphosphites are less effective than their counterparts Triphosphites, the following experiment shows an even clearer result: Two polypropylene masses are not stabilized by intimately mixing 100 parts by weight, powdered polypropylene produced with a phosphite according to the table below and the Melt index determined initially and after heating for 30 minutes at 316 ° C: