WO1992006135A1 - Cationic laminar compounds - Google Patents

Abstract

Halogen-containing plastics can be stabilised against thermal load and/or u/v radiation by adding to them 0.01 to 5 % wt. of cationic interlaminar compounds with specific areas to BET of at least 50 m?2/g, the surfaces of which have been modified by treatment with a dispersing additive, possibly mixed with other commercially available stabilisers.

Description

 Cationishe visual connections

The invention relates to cationic layered compounds with a modified surface, a process for their preparation and their use as color-stabilizing additives for halogen-containing plastics.

Heavy metal compounds based on lead, tin, barium and / or cadmium are conventionally used in the manufacture of articles from halogen-containing plastics, such as polyvinyl chloride, in order to counteract discoloration or decomposition at the elevated processing temperatures. From a work physiological point of view, however, there is a need to replace these very effective stabilizers with less hazardous substances.

Efforts to remedy this problem have not been lacking in the past. Examples of alternatives are calcium compounds and zinc soaps, preferably in combination with one another, the action of which can be supported by organic co-stabilizers such as imino or epoxy compounds. Stabilizers of this type are toxicologically less of a concern, but as a rule they do not achieve the performance of the heavy metal compounds mentioned at the outset, so that they can be used to increase their stabilizing effect other components need to be added. Suitable co-stabilizers are, for example, zeolites [EP-A-027 588] or cationic layered compounds of the hydrotalcite type [EP-B-063180].

When using cationic layer compounds as stabilizers or co-stabilizers in halogen-containing plastics, the problem arises of adequately dispersing the hydrophilic insoluble solids in the sparingly polar plastic matrix. From the cited documents it is known that particle shape and size as well as a suitable surface covering is of particular importance for this. Processes for the preparation of stabilizers are known from DE-B-3019632, EP-A-189 899 and EP-A-142773, in which the surface of cationic layer compounds with small amounts of anion-active substances, eg. B. fatty acids or alkyl sulfates. In these cases, however, sufficient dispersibility is only achieved if the particle size has a diameter of 5 μm and the specific surface area, determined according to BET, does not exceed 30 m ² / g.

However, the use of stabilizers with small specific surfaces also has disadvantages, since the capture reaction of the basic solid for the hydrogen halide released during the decomposition of halogenated plastics, for example HCl, can naturally only take place on the surface.

Cationic layered compounds which meet the requirements mentioned are also difficult to access, since the crystallization of the solid from the aqueous phase in the pressure reactor must take place at temperatures well above the normal boiling point of the water. This requires a high level of technical effort as well as an unsatisfactory space-time yield due to the long crystallization times.

The object of the invention was therefore to develop new stabilizers for halogen-containing plastics which are free from the disadvantages described.

The invention relates to cationic layer compounds with specific BET surface areas of at least 50 m 2 / g, the surfaces of which have been modified by treatment with a dispersing additive, obtainable by adding cationic visual compounds of the formula (I),

[M ^(II) _1-x M ^(III) _x (OH) ₂ ] A _x · n H ₂ O (I) in the

M ^(II) for at least one divalent metal ion,

M ^(III) for at least one trivalent metal ion,

 A for an equivalent of a mono- or polyvalent acid anion,

x for numbers between 0.1 and 0.5 and

n stands for numbers between 0 and 1, optionally after dewatering, treated with at least one liquid or low-melting, dispersing additive.

The invention is based on the knowledge that cationic

Layered compounds with a large specific surface have an excellent effect as stabilizers or co-stabilizers in Halogen-containing plastics show if they are treated with suitable dispersing additives. This is all the more surprising since the German patent DE-B-30 19 632 shows that cationic layered compounds of the hydrotalcite type with BET specific surface areas of about 50 m 2 / g are used

Decomposition and blackening of plastics should lead. The invention also includes the finding that the surface-modified cationic layer compounds are easily accessible and can be incorporated well into the polymer matrix. In addition, the substances can be classified as safe from an occupational medical point of view.

Surface-modified cationic layered compounds with a particularly high stabilizing effect are obtained if one starts from cationic layered compounds in which M ^(II) in formula (I) is magnesium, calcium or zinc and M ^{(III) is} aluminum. Surface-modified hydrotalcites, which are represented by formula (I), have proven particularly advantageous when M ^{(II) is} magnesium and M ^{(III) is} aluminum ions.

Another object of the invention relates to a method for color stabilization of halogen-containing plastics against thermal stress and / or UV radiation, which is characterized in that the plastics 0.01 to 5, preferably 0.1 to 1 wt .-% cationic layered compounds with specific BET surface areas of at least 50 m 2 / g, the surfaces of which have been modified by treatment with a dispersing additive, optionally in a mixture with other commercially available stabilizers. The use of hydrotalcite as a starting material for the production of the surface-modified cationic layer compounds has proven to be particularly advantageous.

To prepare the surface-modified cationic layer compounds, cationic layer compounds of the formula (I),

[M ^(II) _1-x M ^(III) _x (OH) ₂ ] A _x · n H ₂ O (I) in the

M ^(II) for at least one divalent metal ion,

M ^(III) for at least one trivalent metal ion,

 A for an equivalent of a mono- or polyvalent acid anion,

 x for numbers between 0.1 and 0.5 and

 n stands for numbers between 0 and 1, optionally after dewatering, treated with at least one liquid or low-melting, dispersing additive.

The cationic layered compounds are known compounds [Chemtech, 58, (1986)]. A process for their preparation, which is described in German patent DE-B-33 06 822, is based on the direct reaction of aqueous slurries of aluminum hydroxide gel, basic magnesium carbonate and magnesium hydroxide or oxide at temperatures between 70 and 85 ° C. The layered connections are free of by-products. As two-part metals M ^(II) come for example Calcium, magnesium, strontium, barium, zinc or cadmium, as trivalent metals M ^(III) aluminum, iron or chrome. Examples of acid anions A are carbonate, sulfate, nitrate, chloride, formate or acetate,

Products with particularly advantageous application properties can be obtained by using layered compounds of the formula

(I) in which M ^{(II) stands} for magnesium, calcium or zinc and M ^(III) for aluminum.

Cationic layered compounds which are produced by this process have a high specific surface area according to BET [ROMMP's Chemie Lexikon, p.423] of at least 50 m ² / g. If they still contain physically bound water, this is removed before treatment with the additive. The dewatering is advantageously carried out at temperatures of 110 to 280, preferably 150 to 240 ° C, for example in a drying cabinet. In a preferred embodiment of the invention, anhydrous cationic layer compounds are used which have been obtained by spray drying. In a special embodiment of the invention, the water-containing cationic layer compounds and the dispersing additives can also be mixed and spray-dried together.

The anhydrous cationic layer compounds, which themselves already have a stabilizing effect on halogen-containing plastics, even if only slightly, are subsequently mixed with at least one liquid or low-melting, dispersing additive from the group described by a) full or partial esters of polyols with 2 to 30 carbon atoms and 2 to 12 hydroxyl groups with fatty acids with 6 to 22 carbon atoms and 0, 1, 2 or 3 double bonds, b) epoxidized esters of glycerol with fatty acids with 16 to 22 carbon atoms and 1 , 2 or 3 double bonds and c) alkyl or aryl phosphites is treated.

The additives are advantageously such

Substances that are usually added to halogen-containing plastics for other purposes, for example as lubricants.

The additives of subgroup a) are full or partial esters which are obtained by the relevant methods of preparative organic chemistry, for example by acid-catalyzed reaction of polyols with carboxylic acids. Suitable polyol components are glycerol, technical oligoglycerol mixtures with average degrees of condensation of 2 to 10, glucose, trimethylolpropane or pentaerythritol. The fatty acid component can be derived, for example, from caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, petroseline acid, ricinoleic acid, linoleic acid, linolenic acid, arachic acid, gadoleic acid, behenic acid or eruic acid. As is common in fat chemistry, the fatty acid component can also be a technical mixture, such as occurs in the pressure splitting of natural fats and oils. Preferably partial esters of technical oligoglycerol mixtures with saturated fatty acids, in particular partial esters based on technical diglycerin, are used as additives.

 The additives of subgroup b) are substances which are obtained by processes known per se by epoxidation of unsaturated fatty acid jlyceride esters. The fatty acid component can be derived, for example, from palmitoleic acid, oleic acid, elaidic acid, petroselinic acid, ricinoleic acid, linoleic acid, linolenic acid, gadoleic acid or erucic acid Oils. Epoxidized beet or sunflower oil from new breeding and epoxidized soybean oil are preferably used as additives.

The additives of subgroup c) are substances that follow the formula (II), OR ³

R ¹ OP-OR ² (II) in which R ¹ , R ² and R ³ independently of one another represent an alkyl radical having 1 to 18 carbon atoms or a phenyl radical. Typical examples of this are tributyl phosphite, triphenyl phosphite, dimethylphenyl phosphite or dimethylstearyl phosphite. Diphenyldecyl phosphite is preferably used as an additive.

The dewatered cationic layer compounds are mixed with the additives in a weight ratio of 1: 1 to 35: 1, preferably 4: 1 to 33: 1 treated. For this purpose, it is sufficient to mix the components intensively either at room temperature or at a temperature above the melting point of the additive, but below the decomposition temperatures of the cationic layer compounds and / or additives, preferably below 300 ° C. and in particular below 100 ° C. Free-flowing and easy-to-use powders are obtained.

The cationic layer compounds according to the invention with a modified surface are suitable as stabilizers for halogen-containing plastics against thermal influences and / or UV radiation. Halogen-containing plastics are understood to mean those polymers and copolymers which contain, for example, vinyl chloride, vinyl acetate, chloroprene or chlorotrifluoroethylene acetate as monomers. The use of the surface-modified cationic layer compounds preferably extends to polyvinyl chloride molding compositions.

In order to prevent discoloration of the plastics, the cationic layered compounds with modified surfaces are added to the halogen-containing plastics in quantities of 0.01 to 5, preferably 0.1 to 1% by weight, based on the plastic. When used, the stabilizers are usually combined with the in

Granules present mechanically mixed plastics before the latter are fed to the deformation, for example in the calender, extrusion or extrusion process.

The cationic layered compounds with a modified surface can be used alone or in a mixture with other commercially available stabilizers. Examples include zinc and calcium salts of fatty acids with 12 to 18 carbon atoms or of acetylacetone, organotin compounds such as dioctyltin laurate or dioctyltin maleate, phosphites of the formula (II), epoxidized fatty acid glycerides or full or partial esters of polyols with fatty acids. The amounts of the stabilizers among one another can vary as required, with the proviso that the total amount added is within the stated limits of 0.01 and 5% by weight, based on the plastic.

The following examples are intended to explain the subject matter of the invention in more detail without restricting it.

Examples

I. Production of the cationic layer connection with

 modified surface

The test substances A, B, C and D are used in the sense of the invention, the test substances E, F and G are used for comparison.

Test substance A. Hydrotalcite (specific surface 115 m ² / g, commercial product from Giulini Chemie GmbH) was dewatered under normal pressure over a period of t = 2 h at a temperature of T = 150 ° C. 100 g of the dried product were then transferred to a mixing apparatus, 20 g of a technical diglycerin-C _12/18 coconut _fatty acid monoester were added and the _{mixture was} homogenized over a period of 1 min.

Test substance B. Analogous to the preparation of A, hydrotalcite was dewatered at 200 ° C. 100 g of the dried product were then transferred to a mixing apparatus, 3 g of a technical diglycerin-C _12/18 coconut fatty acid _{monoester were} added and the _{mixture was} homogenized over a period of 1 min.

Test substance C. Analogous to the preparation of A, hydrotalcite was dewatered at 200 ° C. 100 g of the dried product were then transferred to a mixing apparatus, 10 g of epoxidized soybean oil (saponification number = 125, epoxy oxygen content = 5.8% by weight)) were added and the mixture was homogenized over a period of 1 min. Test substance D. Analogous to the preparation of A, hydrotalcite was dewatered at 240 ° C. 100 g of the dried product were then transferred to a mixing apparatus, 50 g of diphenyldecyl phosphite were added and the mixture was homogenized over a period of 1 min.

Test substance E. Hydrotalcite (specific surface 115 m ² / g, commercial product from Giulini Chemie GmbH) was dewatered under normal pressure over a period of t = 2 h at a temperature of T = 150 ° C. and used without further occupancy.

Test substance F. Analogous to the production of E, hydrotalcite was dewatered at 200 ° C. and used without further occupancy.

Test substance G. "Alacamizer 4", commercial PVC stabilizer based on hydrotalcite from Kyowa Chemical Ind. Specific surface area according to BET 8 m ² / g (cf. "Introduction of Alcamizer", Kyowa Chemical Ind.Co., Ltd , 2 to 35, Isuriganecho, Higashi-ku, Osaka, Japan).

II. Examples of application technology

The color-stabilizing effect of the test substances was examined on the basis of the "static stability" of rolled skins. For this purpose, polyvinyl chloride molding compounds containing stabilizer mixtures were processed on a laboratory roller mill measuring 450 × 220 mm (from Berstorff) at a roller temperature of 170 ° C. and a roller speed of 12.5 rpm in synchronism to test skins. The approx. 0.5 mm thick skins were cut into square specimens with an edge length of 10 mm, which were then exposed to a temperature of 180 ° C in a drying cabinet with six rotating trays (Heraeus FT 420 R). The samples were removed at intervals of 15 minutes and their change in color was assessed.

The discoloration was characterized by grades 1 (colorless) to 10 (black, stability drop).

As stabilizer chemicals were

0.5 part by weight of zinc stearate

 0.5 parts by weight of calcium stearate

0.2 part by weight of Rhodiastab ^(R) 50 (stearoylbenzoylmethane)

0.6 to 0.9 parts by weight of test substance A to G, per 100 parts by weight of polyvinyl chloride molding compound, are added. The results are summarized in Tab. 1.

Claims

Claims 1. Cationic layer compounds with specific BET surface areas of at least 50 m ² / g, the surfaces of which have been modified by treatment with a dispersing additive, can be obtained by adding cationic layer compounds of the formula (I), [M ^(II) _1-x M (III) _x (OH _{) 2} ] A _x · n H ₂ O (I) in the M ^(II) for at least one divalent metal ion, M ^(III) for at least one trivalent metal ion,  A for an equivalent of a mono- or polyvalent acid anion,  X for numbers between 0.1 and 0.5 and  n stands for numbers between 0 and 1, optionally after dewatering, treated with at least one liquid or low-melting, dispersing additive. 2. Process for the color stabilization of halogen-containing plastics against thermal stress and / or UV radiation, characterized in that 0.01 to 5% by weight of cationic layered compounds with BET specific surface areas of at least 50 m ² / g are added to the plastics, for their preparation, one uses cationic layer compounds of the formula (I), [M ^(II) _1-x M ^(III) _x (OH) ₂ ] A _x · n H ₂ O (I) in the M ^(II) for at least one divalent metal ion, M ^(III) for at least one trivalent metal ion,  A for an equivalent of a mono- or polyvalent acid anion,  x for numbers between 0.1 and 0.5 and  n stands for numbers between 0 and 1, optionally after dewatering, treated with at least one liquid or low-melting, dispersing additive. 3. The method according to claim 2, characterized in that one uses cationic layer compounds of formula (I) in which M ^{(II) is} magnesium, calcium or zinc. 4. The method according to claim 2, characterized in that one uses cationic layer compounds of formula (I) in which M ^{(III) is} aluminum. 5. The method according to claim 2, characterized in that one uses cationic layered compounds of the hydrotalcite type. 6. The method according to claim 2, characterized in that the cationic layer compounds are dewatered at temperatures of 110 to 280 ° C. 7. The method according to claim 2, characterized in that the cationic layer compounds with at least one additive from the group consisting of a) full or partial esters of polyols with 2 to 30  Carbon atoms and 2 to 12 hydroxyl groups with fatty acids with 6 to 22 carbon atoms and 0, 1, 2 or 3 double bonds, b) epoxidized esters of glycerol with fatty acids with 16 to 22 carbon atoms and 1, 2 or 3 double bonds and c) alkyl or aryl phosphites is treated. 8. The method according to claim 7, characterized in that the cationic layer compounds with at least one additive from the group consisting of full or partial esters of glycerol, technical oligoglycerol mixtures, glucose, trimethylolpropane or pentaerythritol with aliphatic carboxylic acids having 6 to 22 carbon atoms is treated. 9. The method according to claim 7, characterized in that the cationic layer compounds are treated with an additive in a weight ratio of 1: 1 to 35: 1. 10. The method according to at least one of claims 2 to 9, characterized in that the surface-modified uses cationic layer compounds in a mixture with zinc and / or calcium salts. 11. Use of cationic layer compounds, obtainable according to claim 1, optionally in a mixture with other commercially available stabilizers, as color-stabilizing additives to halogen-containing plastics.