CS216674B2 - Thermoplastic shaping mixture - Google Patents

Abstract

The invention relates to thermoplastic molding machines compound mixtures (a) 75 to 95% by weight, based on for the whole aliphatic cellulose ester carboxylic acid of from 1 to 5 carbon atoms and h) from 5 to 25 wt the entire mixture of ethylene / vinyl ester copolymers containing 30 to 98% by weight vinylester. The component a) is preferably cellulose acetate, cellulose acetopropionate or acetobutyrate cellulose and component b) preferably comprises 60 up to 98% by weight of vinylester by which is, for example, vinyl formate, acetate, propionate, -chloropropionate, butyrate, -isobutyrate, -caproate, laurate, myristate, stearate or -benzoate. The compositions of the invention may contain as an additive component of a plasticizer, a dye, pigments and various stabilizers.

Description

(54) Thermoplastic molding compound

2

The invention relates to thermoplastic molding compositions composed

(a) from 75 to 95% by weight of the total mixture, of a cellulose ester with an aliphatic carboxylic acid of 1 to 5 carbon atoms; and

h) from 5 to 25% by weight of the total mixture of ethylene / vinyl ester copolymers containing 30 to 98% by weight of vinyl ester.

Component a) is preferably cellulose acetate, cellulose acetopropionate or cellulose acetobutyrate, and component b) preferably contains 60 to 98% by weight of vinyl ester, such as vinyl formate, -acetate, -propionate, -chloropropionate, -butyrate, -isobutyrate,

-caponate, -laurate, -myristate, -stearate or -benzoate.

The compositions of the invention may contain plasticizers, colorants, pigments and various stabilizers as additional ingredients.

The present invention relates to transparent thermoplastic molding compositions consisting of organic cellulose esters, ethylene-vinyl ester copolymers and optionally low molecular weight plasticizers.

It is well known that cellulose can be thermoplastically processed after esterification with certain organic acids, and in many cases low molecular weight plasticizers need to be added to the esterified product in advance. The three hydroxyl groups of the cellulose anhydroglucose units can be esterified with a number of organic acids, but in practice only the cellulose acetates, acetopropionates and acetobutyrates are widely used as esterified products. Acrylic silk sheets, underlays for security films, electrical insulating films and varnishes.

Cellulose acetate molding compositions cannot be thermoplastically processed without the addition of low molecular weight plasticizers, since cellulose acetate begins to decompose before the softening point. Also, cellulose acetopropionates and cellulose acetobutyrates have a softening point and a decomposition point very close, so that molding compositions made from these esters also need to be mixed with low molecular weight plasticizers before thermoplastic processing. By adding plasticizers, the processing temperature and viscosity of the mixture can be reduced as desired.

Aliphatic esters of phthalic acid, adipic acid, azelaic acid, sebacic acid and phosphoric acid, for example dimethyl phthalate, diethyl phthalate, dibutyl adipate, dioctyladipate, dibutylazelainate, trichloroethyl phosphate and tributyl phosphate are used as plasticizers for organic cellulose esters. It is also preferred to use plasticizer mixtures.

Although the plasticizer-modified cellulose ester molding compositions are sufficiently transparent, it would be desirable for many purposes to improve their thermoforming stability. In addition, the plasticizers migrate over time to the surface of the shaped articles, so that, for example, films made from modified cellulose esters cannot be used to package certain foods.

Mixtures of organic cellulose esters, low molecular weight plasticizers, and olefin polymers have been described in German Laid-Open Patent Application No. 1303 219, which is identical to British Patent No. 1004,204. In addition, conventional low molecular weight esters, which have well-known disadvantages, are used as plasticizers in these mixtures.

It has now surprisingly been found that transparent molding compositions which can be thermoplastically processed in various ways can be obtained without the above-mentioned disadvantages by mixing the cellulose esters with the copolymers of ethylene and vinyl esters.

The present invention relates to a thermoplastic molding composition comprising

(1) from 75 to 95% by weight, based on the total mixture, of a cellulose ester of an aliphatic carboxylic acid of 1 to 5 carbon atoms and from 5 to 25% by weight, based on the total mixture, of an ethylene / vinyl ester copolymer containing 30 to 98% by weight vinyl esters.

One of the particularly surprising properties of the inventive molding compositions is their transparency and their very good mechanical properties.

Suitable esters of cellulose and aliphatic carboxylic acids having 1 to 5 carbon atoms are, in particular, cellulose acetate, cellulose acetopropionate and cellulose acetobutyrate.

Methods for producing organic cellulose esters have been known for a long time and have been described, for example, in Ullman's Encyclopedia der technischen Chemie (ed. Urban and Schwarzenberg, Munich-Berlin, 1963) Vol. 5, pp. 182-201.

Preferred cellulose acetobutyrates contain up to 50% butyric acid, up to 26% acetic acid and

0.75 to 1.95% of hydroxy groups.

Particularly suitable as cellulose acetobutyrates for the molding compositions according to the invention are products of the following composition:

up to 46% butyric acid, up to 21% acetic acid; and

1.0 to 1.7% hydroxy groups.

Preferred cellulose acetopropionates usually have the following composition:

up to 63,5% propionic acid, up to 12% acetic acid; and

1.2 to 1.95% hydroxy groups.

Particularly suitable are cellulose acetopropionates of the following composition:

up to 58% propionic acid, up to 8% acetic acid; and

1.5 to 1.8% hydroxy groups.

The cellulose acetate used is preferably secondary cellulose acetate.

The percentages and parts referred to above and below are percentages and parts by weight.

The relative viscosities (η rel) of 2% solutions of aliphatic cellulose esters measured in acetone at 25 ° C are in the range of 3.5 to 4.5, preferably in the range of 4.0 to 4.5.

Organic vinyl esters of saturated or halogenated, in particular chlorinated, aliphatic monocarboxylic acids having 1 to 18 carbon atoms or aromatic monocarboxylic acids having 7 to 11 carbon atoms can be used as vinyl esters. Specific examples include vinyl formate, vinyl acetate, vinyl propionate, vinyl chloropropionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl laurate, vinyl myristate, vinyl stearate and vinyl benzoate. Vinyl acetate is preferred. Ethylene / vinyl ester copolymers are prepared by known methods of high or low pressure synthesis, optionally in solvents such as tertiary butanol.

The ethylene / vinyl ester copolymers prepared by high pressure synthesis have a melt flow index (according to DIN 53 735 at 190 ° C under a load of 21.18 N) in the range of 0.1 to 100 dg.min ^-1, preferably in the range of 1.0 to 10 dg. min ^-1 , preferably 4.5-6 dg. .min ^-1 . Their viscosity limit values measured in tetralin at 120 ° C are usually in the range of 0.6 to 1.5 dl.g ^-1 . The molecular weight determined by light scattering is preferably in the range of 50,000 to 1,000,000. The heterogeneity of U, defined by the formula (Mw / Mnj-1 [G. Schulz, Z. Phys, Chem. (B) 43 (1939J pp. 25-34) is These copolymers are most easily dissolved in hot hydrocarbons.

Ethylene / vinyl ester copolymers prepared, for example, by solution or emulsion polymerization, containing, for example, 30 to 98 percent by weight and preferably 60 to 80 percent by weight vinyl esters may have a melt index (190 ° C / / 21.18 N) greater than 100 dg.min ^-1, but preferably the melt index is less than 15 dg.min ^-1, most preferably between 0.5 and 5 dg.min ^-1. The molecular weight determined by light scattering is preferably 40,000 to 1,000,000. The heterogeneity of U lies in the range of 1 to 6. The copolymers are soluble in hydrocarbons and alcohols and preferably have a viscosity limit measured in toluene at 25 ° C in the range of 0.5 to 2. , 5 dl.g ^-1 .

The ethylene / vinyl acetate copolymers may optionally be saponified partially or completely (20 to 100 percent).

The composition and melt index values of the ethylene / vinyl acetate copolymers used are as follows:

designation

Table of vinyl acetate content [° / o weight]

Melt flow index [dg.min ^- !]

EVA-800 EVA-700 EVA-600 EVA-450 EVA-338 EVA-80

0.45

10.4

0.54

In the table above:

EVA: ethylene / vinyl acetate copolymer

The melt flow index was determined according to DIN 53 735 under a load of 21.18 N at 190 ° C.

The thermoplastic molding compositions of the invention may optionally be mixed with low molecular weight plasticizers such as: dimethyl phthalate, diethyl phthalate, triphenyl phosphate, methyl phthylethyl glycolate, di-n-butyl sebacate, ethyl phthalylethyl glycolate, butyl phthalyl butyl glycolate, dibutyl phthalate, dioctyl phthalate, dioctyl phthalate, dioctyl phthalate. Optional plasticizers are added prior to mixing the basic components of the mixture.

The inventive molding compositions are prepared by intimately mixing the ingredients. Any mixing methods can be used, for example calendering or screw extrusion.

Mixtures can also be prepared via solutions. In this case, the components are dissolved in suitable solvents or solvent mixtures and the polymer mixtures are precipitated with suitable non-solvents or the solvent or solvent mixtures are removed from the mixtures by evaporation. Suitable solvents for the organic cellulose esters and ethylene / vinyl ester copolymers are, for example, methylene chloride and glacial acetic acid. Hexane may be used as a precipitant suitable for both components, for example when the components have been dissolved in methylene chloride.

The compositions of the invention may also contain certain other additives which serve to dye or pigment the polymer compositions or to improve their resistance to oxidation, lightfastness or fire resistance, and the like.

The inventive molding compositions prepared from ethylene / vinyl ester and organic cellulose esters have remarkably increased notched toughness measured according to DIN 53 453.

In addition, the molding compositions according to the invention have an improved hot shape stability, measured, for example, as a Vicat softening temperature (DIN 53 460).

The Vicat softening temperature is up to 40 degrees Celsius higher than the same value of low molecular weight plasticizer modified cellulose esters.

Compared to conventional cellulose ester molding compositions containing low molecular weight plasticizers, the polymer compositions of the invention also exhibit improved mechanical properties such as increased hardness, tensile strength, flexural strength, and modulus of elasticity.

Polymer blends based on organic cellulose esters and ethylene / vinyl ester copolymers practically do not exhibit so-called plasticizer migration, and these molding blends are therefore also particularly suitable for food contact applications.

Improved stability to hot air allows the use of these compounds for the manufacture of outdoor clothing.

The inventive molding compositions can be used in the manufacture of moldings of any kind, in the manufacture of acetate silk, carrier films for security films, packaging material, electrical insulation films and lacquers.

Mixtures of organic cellulose esters and methylene / vinyl ester copolymers can be processed continuously or batchwise in known extruders or in injection molding machines, since they have good flow properties under these conditions.

Examples 1 to 15

Cellulose acetobutyrate containing 42 to 46 percent butyric acid, 18 to 21% acetic acid and 1.0 to 1.7% hydroxy groups is intimately mixed with ethylene / vinyl acetate copolymers on rollers at 170 ° C. The composition of the mixture is given in the following table.

The sheet material thus obtained is granulated and then extruded in an injection molding machine. Injection is carried out at a mass temperature of 230 ° C.

In the examples labeled "L", the polymer blends are first prepared as solutions, which are then precipitated. Appropriate volumes of 10% methylene chloride solutions of cellulose acetobutyrate and ethylene / vinyl acetate copolymer are mixed together and the mixed solution is precipitated with hexane. The resulting mixtures were dried and test samples were extruded as described above.

Explanation of the symbols in the table:

a _n : impact strength to DIN 53 453 dimension: [kj / m ³ ], and _k : notched impact to DIN 53 453 dimension: [kj / m ³ ],

Vicat: Vicat softening temperature, method B (force: 49.05 N), according to DIN 53 460, dimension: [° C], ff _bF : bending stress between permanent deformations according to DIN 53 452, dimension: [MPa].

f: deflection at σ _Μ , dimension: [mm].

H _k 30: Brinell hardness after 30 s according to DIN 53 456, dimension: [MPa].

Transparence:

-j- indicates glassy clear transparency - indicates opacity.

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Examples 16 to 29

Cellulose acetopropionate containing 54 to 58% propionic acid, 5 to 8% acetic acid and 1.5 to 1.8% free hydroxy groups is intensively mixed at 180 ° C with ethylene / vinyl acetate copolymer on the rollers (see the following table).

The rolled sheet material is granulated and then extruded into a test machine at a mass temperature of 240 ° C.

In the examples designated L, as well as in Examples 1 to 15, mixed solutions of the polymer components are first produced, which are then precipitated.

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Examples 30 to 33

Secondary cellulose acetate is vigorously mixed with ethylene / vinyl acetate copolymer on rollers at 220 ° C (see following table).

The rolled sheet material is granulated and then extruded into a test machine at a mass temperature of 230 ° C.

In the examples labeled L, as well as in Examples 1 to 15, mixed solutions of the polymer components are first produced, which are then precipitated.

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Claims (11)

Subject A thermoplastic molding composition, characterized in that it comprises (a) from 75 to 95% by weight, based on the total mixture, of a cellulose ester of an aliphatic carboxylic acid having 1 to 5 carbon atoms; and b) from 5 to 25% by weight, based on the total mixture, of an ethylene / vinyl ester copolymer containing 30 to 98% by weight of vinyl ester. 2. The thermoplastic molding composition according to claim 1, wherein component b) comprises 60 to 98% by weight of vinyl ester. 3. The thermoplastic molding composition according to claim 1, characterized in that it comprises as component a) cellulose acetate, cellulose acetopropionate or cellulose acetobutyrate. 4. The thermoplastic molding composition according to claim 3, wherein the component aj comprises cellulose acetobutyrate containing 40 to 50% butyric acid, 15 to 26% acetic acid and 0.75 to 1.95% hydroxy groups. 5. The thermoplastic molding composition of claim 4, wherein the component aj comprises cellulose acetobutyrate containing 42 to 46% butyric acid, 18 to 21% acetic acid and 1.0 to 1.7% hydroxy groups. 6. Thermoplastic molding composition according to claim 3, characterized in that, as component a) OF THE INVENTION comprises cellulose acetopropionate containing 50 to 63.5% propionic acid, 1 to 12% acetic acid and 1.2 to 1.95% hydroxy groups. 7. The thermoplastic molding composition according to claim 6, characterized in that it comprises as component a) cellulose acetopropionate containing 54 to 58% propionic acid, 5 to 8% acetic acid and 1.5 to 1.8% hydroxy groups. 8. The thermoplastic molding composition of claim 3, comprising as component a) a secondary cellulose acetate. 9. The thermoplastic molding composition according to claim 1, wherein component bj comprises, as the wool-ester component, an organic vinyl ester derived from a saturated aliphatic monocarboxylic acid comprising: From 1 to 18 carbon atoms or from an aromatic monocarboxylic acid containing from 7 to 18 carbon atoms; II carbon atoms. 10. The thermoplastic molding composition of claim 9, wherein the vinyl ester comprises saturated aliphatic halogenated monocarboxylic acids. 11. The thermoplastic molding composition according to claim 9, wherein the vinyl ester component is vinyl formate, acetate, propionate, chloropropionate, butyrate, isobutyrate, caproate, laurate, myristate, stearate or benzoate.