DE2513839A1 - PROCESS FOR THE PRODUCTION OF FILMS FROM VINYL CHLORIDE-VINYL ACETATE COPOLYMERISATES - Google Patents

Description

Process for the production of films from vinyl chloride-vinyl acetate copolymers

The invention relates to a method for producing films from vinyl chloride-vinyl acetate copolymers through thermoplastic processing.

Vinyl chloride-vinyl acetate copolymers with 5 to 15 % vinyl acetate differ from vinyl chloride homopolymers in their lower softening range and the generally easier preprocessing that this entails, in particular with regard to the significantly better deep-drawing and sealing properties. Such copolymers are therefore preferably used in the production of deep-drawable sheets and foils

Vinyl chloride-vinyl acetate copolymers with a significantly higher vinyl acetate content of 20% and above, have excellent adhesive properties and are therefore mainly used in the paint and adhesive industry and as waste material in the production of sheets and calender films. 20 to 30? »Solutions of such copolymers in esters or ketones bond, for example, polyvinyl chloride to wood, stone, cardboard, paper or the like, the bond being characterized by high elasticity and low water vapor permeability, the adhesion particularly on smooth surfaces by a suitable heat treatment can still be significantly improved.

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The invention is a process for the production of Films made from vinyl chloride-vinyl acetate copolymers by thermoplastic processing, which is characterized in that Vinyl chloride-vinyl acetate copolymers with 31 to 50% vinyl acetate and a Fikentscher K value of 40 to 70 solid stabilizers and optionally solid lubricants and / or fillers at temperatures between 120 and 180 ° C be extruded into foils in screw extrusion presses

It is surprising that vinyl chloride-vinyl acetate copolymers with such a high vinyl acetate content and a correspondingly strong tendency to stick, can be thermoplastically processed into films according to the invention.

The vinyl chloride-vinyl acetate copolymers which can be used according to the invention are usually prepared by suspension polymerization of the monomers in the aqueous phase using protective colloids and monomer-soluble catalysts, optionally in the presence of buffer substances, wetting agents or other customary additives.

Vinyl chloride-vinyl acetate copolymers which have a vinyl acetate content of 35 to 45% ^and a Fikentscher K value of 50 to 55 are particularly suitable.

The thermoplastic processing of these copolymers is one Formulation beneficial while avoiding liquid components. Suitable solid stabilizers are usually 0.5 to 5% by weight in particular dialkyltin compounds, barium-cadmium compounds, calcium-zinc stabilizers, phenylindole, aminocrotonic acid esters, diphenylthiourea, phosphites and lead stabilizers.

Physiologically harmless stabilizers such as are suitable for the preferred use of the films in food packaging

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for example di-n-octyltin compounds of maleic acid and on maleic acid esters (up to 1.5% by weight), calcium and magnesium salts τοπ straight-chain, aliphatic, saturated monovalent carboxylic acids with 10 to 20 carbon atoms, for example calcium stearate, calcium octoate, ( up to 3 wt. 96) zinc stearate, zinc octoate (up to 1 wt.%), 2 phenylindole (up to 1 wt.%), aminocrotonic acid ester, sorbitol and pentaerythritol. Antioxidants such as octadecyl-ß- (4-hydroxy-3 ¹ , S'-di-t-butylphenyD-propionate (up to 0.25 wt .- #), 4,4'-thiobis- (3-methyl- 6-t-butylphenol-1) (up to 0.25% by weight), 2,6-di-t-butyl-4-methylphenol, t-butylhydroxyanisole (up to 0.5% by weight) can be added

If necessary, solid lubricants are used in amounts of 0.1 to 3 Weight-96, such as esters of montanic acids with ethanediol and / or 1 »3-butanediol, stearic acid, 12-hydroystearic acid and their Calcium and magnesium salts, solid glycerol esters, long-chain hard ester waxes, multifunctional fatty acid esters, so-called complex esters, fatty acid amides, such as, for example, ethylene-bis-stearamide, higher fatty alcohols or paraffin wax. Lubricant, like Polyethylene wax, in contrast to homopolymer!, Can sow and Copolymers containing weak vinyl acetate groups should not be used, as they can lead to deposits in the screw extruder, e.g. at the screw tip, due to their excessive incompatibility.

The copolymers used according to the invention can additionally Fillers are added, but preferably less than 10% by weight, since processing into films with larger amounts of filler is extremely difficult. Suitable fillers are, for example, silicic acid-containing fillers, in particular with particle sizes of 0.01 to 20 cm, preferably 0.01 to 5 μm, such as highly dispersed silica, silica, silicates, silica gels, alumina, talc, kaolin, short-fiber asbestos and inert metal oxides, carbonates or sulfates, for example calcium oxide, lead oxide, calcium carbonate, magnesium carbonate, calcium sulfate, magnesium sulfate or lead sulfate.

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The copolymers used according to the invention can also Dyes and / or pigments are added. Suitable as pigments zinc oxide, titanium dioxide, magnesium dioxide or organic pigments such as phthalocyanines.

The copolymers mixed with the appropriate additives are prepared, for example, by spray or roller drying or coagulation with subsequent drying converted into a solid substance, which is thermoplastically carried out in a screw extruder Extrusion is processed into foils, for example via round nozzles or slot dies. It shows that due to the low Melt viscosity of the vinyl chloride-vinyl acetate copolymers processed according to the invention lower processing temperatures than for vinyl chloride homopolymers or vinyl chloride-vinyl acetate copolymers can be used with a lower vinyl acetate content, which is why smaller amounts of stabilizer are required are. The temperatures to be used in extrusion according to the invention depend on the dimensions, screw geometry, Number of revolutions, nozzle shape and other machine-typical parameters and are between 110 and 180 C, preferably between 140 up to 16O C The temperatures in the feed and cylinder section of the screw extrusion press are usually around 110 to 130 C, while 120 to 160 C are usually measured at the material outlet.

According to the invention, glass-clear as well as colored films of 10 to 500 μm, preferably 10 to 100 μm, thickness can be produced which have the Comply with the recommendations of the Federal Health Office for food packaging. The foils have a very good water resistance, excellent resistance to oils and fats as well as dilute acids, salt solutions and alkalis. You can easily laminate onto other foils, plates or other shaped bodies and are well suited as protective coatings for metals, as they are on them only adhere moderately. Since they are odorless and tasteless, they are ideal for food packaging. in the

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Normal blown film process according to the invention can be produced by simply selecting the blow-up ratio and the take-off speed without additional stretching equipment, shrink films with 20 to 40 % shrinkage in the longitudinal and transverse directions, so that complex molded parts can be laminated with them without any problems.

Laminating or lining moldings with the films produced according to the invention creates a risk of explosion or poisoning, as is the case with impregnation or painting with corresponding dissolved vinyl chloride-vinyl acetate copolymers high vinyl acetate content due to the solvent is switched off.

example

50 kg vinyl chloride-vinyl acetate copolymer with 40 % vinyl acetate and a Fikentscher K-Vert of 55 were cooled with the specified additives in a 2 (and cooled in a cooling mixer.

given additives mixed in a 200 l fluid mixer up to 80 C.

Recipe ^ 100 parts copolymer (Wacker Vinnol H 40/55) 2 parts aminocrotonic acid ester 1 part powdered calcium-zinc complex 0.5 parts of high molecular weight mixed esters of penta

erithritol and fatty acids 0.5 parts of highly disperse silica

The resulting free-flowing powder mixture had a bulk density of 0.80 g / cm · The processing into the film took place on an extruder with 60 mm screw diameter, length-to-diameter ratio 25 »compression 1x2.2, round nozzle with 200 mm diameter and 0.7 mm gap width with the temperature rising from the cylinder to the material outlet opening from 100 to 150 C. The output was 30 kg / h,

60 98 * 2 / 080.7 _0R1GINAL

where a mass temperature with a puncture pyrometer of

ο f

155 C was measured. The film obtained was 60 (, tin thick

Film properties;

lengthways across

Dimensional change at 100 ° C / l5 min. (#) Tear strength according to DIN 53455 (kp / cra ² ) Elongation at break according to DIN 53455 (%)

Notched impact strength according to DIN 53448 (cm kp / cra *) 154 Tear resistance according to DIN 53515 (kp / cra) After tempering at 80 C / l hours tear strength according to DIN 53455 (kp / cm ² ) elongation at break according to DIN 53455 (%)

Notched impact strength according to DIN 53448 (cm kp / cm ^ö ) 111 tear resistance according to DIN 53515 (kp / cm)

Material properties on press plates 1

The mixture given in Example 1 and, for comparison, a copolymer of vinyl chloride-vinyl acetate with 10 % vinyl acetate and K-Vert 60 with the additives given in Example 1 were rolled at 160 ° C. for 5 minutes on a mixing mill. The mixing roller mill used had a roller diameter of 150 mm, a roller length of 370 ma and was operated with synchronous rollers at 24 revolutions / min.

The Valz pelts were pressed at 160 ° C. for 10 minutes at 250 atmospheric pressure and determines the mechanical values on the press plates.

- 31 - 21st 445 551 12th 10 m) 154 172 25th 21 549 527 ~ 0 -0 ² \
m) 111 111 114 79

/ 7

6 0 9 8 4 2 / o 8 0 7

711 660 8th 8th 256 297 10 13th 27 48 500. 30,500 83 80 55 65.5

Tensile test according to DIN 53455 (4 mm pressed body) t

Copolymer 4o / 55 10/60

2
Tensile strength (kp / cm)

Tensile elongation (%)

Tensile strength (kp / cm ² )

Elongation at break (%)

Notched impact strength according to DIN 53448

(cm kp / cm) (l mm compact)

Tensile Ε module according to DIN 53457 (kp / cm ² )

(4 ma pressed body) 35

Shore hardness D according to DIN 53505

(6 Ββ-pressed bodies)

Vicat softening point

DIN 53460 ( ⁰ C) (4 mm pressed body)

Hot tensile tests

In these tests, the press plates were clamped in a conventional test tractor (Instron) and stretched at a feed rate of 50 cm / min at various temperatures, and their elasticity was determined. The results are plotted in FIG. 1 and FIG. The tests show that the extensibility under heat in the case of the copolymer seeds with a 40 % acetate content is significantly higher than that of the copolymers with a low, for example 13 %, acetate content. The K-Vert also plays an essential role. The products with a K value of 50 are easier to draw than those with 55 and much better than those with 60. The lowest deformability is achieved with homopolymers not listed in the diagrams.

FIG. 1 shows the relationship between elongation and the vinyl acetate content.

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FIG. 2 shows the relationship between elongation and the K value.

Copolymers used:

Vinnol H 40/50 is a polyvinyl chloride-polyvinyl acetate copolymer with 40 % Vxnylacetatantexl and K-Vert 50.

Vinnol H 40/55 is a polyvinyl chloride-polyvinyl acetate copolymer with 40 % vinyl acetate antexl and a K value of 55.

Vinnol H 4o / 6O is a polyvinyl chloride-polyvinyl acetate copolymer with 40 % vinyl acetate and K-Vert 60.

Vinnol H 13/55 is a polyvinyl chloride-polyvinyl acetate copolymer with 13 % vinyl acetate and K-Vert 55

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Claims (5)

Claims l) (Process for the production of films from vinyl chloride-vinyl acetate copolymers by thermoplastic processing, characterized in that vinyl chloride-vinyl acetate copolymers with 31 to 50 % vinyl acetate and a Fikentscher K-Vert of 40 to 70, with solid stabilizers and optionally solid lubricants and / or solid fillers are extruded at temperatures between 120 and 180 C ₁ in screw extrusions to form films. 2) Method according to claim 1, characterized in that vinyl chloride-vinyl acetate copolyraerisates are used with a vinyl acetate content of 35 to 45 % . 3) Method according to claim 1 or 2, characterized in that vinyl chloride-vinyl acetate copolymers with a K-Vert according to Fikentscher of 50 to 55 are used · 4) Method according to one of claims 1 to 3, characterized in that the vinyl chloride-vinyl acetate copolymers Pigments and / or dyes are added » 5) Use of the films produced according to one of claims 1 to 4 in food packaging. 609842/0807