DE2731479A1 - CALANDRABLE PROPYLENE POLYMER COMPOUNDS - Google Patents

Description

Bavariaring 4, P.O. Box 20 24 03 8000 Munich 2

Tel .: (0 89) 53 96 53

Telex: 5-24845 tipat

cable: Germaniapatent Munich

July 12, 1977

B 8314

ICI case Po / LC.28902 / 29443

Imperial Chemical Industries, Limited London / Great Britain

Calenderable propylene polymer compositions

709883/0974

Drudnar Bank (Munich) Account XXUt Pottaehack (MOnchwi) account 670-4S- (M

The invention relates to crystalline polypropylene compositions with a low melt index, the formation of Films with a melt index less than 5 can be calendered. The invention also relates to a method for the production of such masses in which powdered polypropylenes can be used (e.g. powders, of which 80 wt .-% through a 410-μπι-, preferably a 250-nni sieve the sieve sizes are defined according to ASTM sieve designation E11-61). From the slides you can various products can be produced by embossing and / or by a thermoforming process.

Calendering processes are very well known and have been used successfully for many years in the processing of polyvinyl chloride been applied. As soon as polypropylene became available, around 1960, attempts were made to calender it. A higher production output can be achieved through calendering. Calendering also offers the possibility of Producing films from powdered polypropylenes as a starting material, while at most industrial Extrusion process the powder must first be converted into granules with a size of usually 1 mm to 3 mm, which is an expensive, additional process step. Calendering can also be used to produce thinner films

25 than is possible by extrusion.

Attempts to calender polypropylene commercially have failed in the last 15 years, and in "Plastiques." Modernes et Elastomeres ", May 1970, p. 245 was reported, that calendering of polyolefins is not common. The reason for this is probably to be found in the fact that the polypropylene in the molten state, the associated with the various stages of a calendering process, experienced rapid degradation. The breakdown leads so that the polypropylene stick to the calender rollers-

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remains what calendering is disadvantageous for commercial use especially when foils with a smooth surface are to be produced. The removal also causes an unacceptable odor and color changes and results in the masses being converted into film form have a melt index higher than 5 making the films technically unsustainable for their potential primary uses will.

It has now been found that low melt index propylene polymers and copolymers in those employing a calendering process connected, molten state forms are sufficiently resistant to degradation, if one in addition to stabilizer systems high effectiveness still a soap and an inorganic one

15 material is used in particulate form. This is surprising because many fillers, such as talc, contain transition metal ions generally promote the degradation of polypropylene.

The subject of the invention is therefore a mass which can be calendered to form a film and which consists of the following:

a) a crystalline homopolymer of propylene and / or a crystalline copolymer of propylene with up to to 25 wt .-%, preferably from over 5 wt .-% to

25 17% by weight, ethylene,

b) 0.1% by weight to 1.5% by weight, preferably 0.15% by weight to 0.3% by weight, of a "highly effective stabilizer system" as defined below,

c) 0.1% by weight to 2.0% by weight, preferably 0.15% by weight to 0.8% by weight, of a soap, which is defined below is and

d) 10% by weight to 60% by weight, preferably 15% by weight to 45% by weight, of a solid particle

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1 the inorganic material.

The percentages given relate to the weight of the polymer and / or copolymer present in the mass.

For the purpose of producing foils which can be processed by embossing and / or by a thermoforming process, the composition used to make the foil desirably has a melt index not higher than 2. (The melt index is derived from a modification of the British is standards 2782, part 1 / 105C / 1970 kg measured using a load of 2.6, wherein the test at a temperature of 230 ⁰ C instead of 19O ⁰ C.> However, since the presence of many fillers increases the viscosity of polypropylenes , the non-filled polypropylene can have a melt index up to a value of 15.

Films from which containers are made by thermoforming should preferably be thinner than 0.5 mm. The inorganic materials produced according to the invention Containing compositions can be calendered to form films with a thickness down to 0.1 mm, while it is of the opinion that corresponding films produced by extrusion have a minimum thickness above 0.2 mm to have. According to the invention, polypropylene films with a thickness of less than 0.2 mm can therefore be produced. the Optimization of the conditions according to the invention during calendering of the mass produced according to the invention enables production of foils with a thickness of 0.05 mm or even thinner foils.

Foils that are to be embossed preferably have a thickness of 0.5 mm to 2.0 mm. According to the invention,

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273U79 ago embossed polypropylene films with a thickness of preferably 0.5 mm to 2.0 mm, in particular with a thickness of 1.0 mm, e.g. B. from 0.85 mm to 1.15 mm, can be produced using a produced according to the invention

5 polypropylene mass have been calendered.

The polypropylenes according to the invention can propylene homopolymers but can be copolymerized using copolymers having from 8% to 17% by weight Ethylene achieves better impact resistance and flexibility. Are preferred by the so-called Block copolymerization produced copolymers, which is obtained, that one the homopolymerization of propylene runs to a point where many of the polymer chains have stopped growing, whereupon ethylene enters the polymerisation zone is introduced. This introduces both propylene and ethylene units into the chains, which are still growing, the proportion of the imported ethylene increasing over time. Block copolymers of of this type are from I.G. Heggs in "Chemistry and Industry" of June 7, 1969 at p.744.

By mixing with 5% by weight to 15% by weight rubber, propylene homopolymers can have impact resistance and flexibility values give, which are in the range of impact resistance and flexibility of the block copolymers. Examples of usable Rubbers are polyisobutylenes, the different types of butyl rubber and ethylene-propylene rubbers as described on pages 255-258 of "Chemistry and Industry" dated

Described March 16, 1974. Diene-modified ones are particularly suitable Ethylene propylene rubbers. The exact amounts of rubber that you need to make the polypropylene required Impact resistance and flexibility to give ranks " on the type of rubber used and can be loaded with routinely performed impact and flexibility tests

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1 will be true.

The compositions used according to the invention contain a “highly effective stabilizer system”, ¹ in particular in amounts which do not exceed 0.7% by weight, based on the polymer and / or the copolymer. Whether or not a stabilizer system is a “highly effective stabilizer system”, is determined as follows:

A propylene homopolymer with a melting index 2 is supplied to a Banbury mixer and heated to 17O ⁰ C. At this temperature it melted. The molten feedstock is transformed quickly into a Zweivalzenmühle which is operated at a temperature in the range from 180 ⁰ C to 185 ⁰ C. The polymer from the two-roll mill is then gradually fed to a 4-roll calender over a period of one hour and calendered to form 0.3 mm thick films. As can be seen from Figure 1 of the drawings, the calender rolls are arranged in the shape of an inverted "L". The two upper rolls of the calender are kept at a temperature of 185 ⁰ C, the middle roll at 180 ⁰ C and the bottom roll to 175 ⁰ C. Polymer samples are taken from a film made during the first two minutes of calendering and a film made during the last two minutes of calendering. The melt indices of these two samples must differ by less than 15% if the polymer system is to be considered highly effective. The term "highly effective stabilizer system" is defined accordingly.

Not all stabilizer compounds are equally effective, so it is possible, although some stabilizers are effective enough that the masses only need to contain 0.1% by weight of the stabilizer system; others, less use effective stabilizers in higher concentrations

709883/0974

that must, so that they are "highly effective stabilizer systems".

Preferably used, highly effective stabilizers are pentaerythritol tetra-fl-3,5-di-t-butyl-4-hydroxyphenylpropionate and tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, however, stabilizers such as 2,6-di-t-butyl-4-methylphenol are also used or J, 1,3-tris (2'-methyl-5-t-butyl-4-hydroxyphenyl) butane effectively. Also compounds with a structure analogous to the four stabilizers mentioned above, where in particular additional, lower alkyl groups are introduced on the benzene ring or alkyl groups that are already present can be varied, have good stabilizing properties. A lower alkyl group in the above Sense contains 1 to 6 carbon atoms.

The soaps used according to the invention are defined as substances that act as lubricants between the mass and the calender rolls act. Typical soaps are the metal salts of carboxylic acids, preferably of monocarboxylic acids with 12 to 18 carbon atoms such as lauric, palmitic, oleic, and stearic acids. If one intends to be permanent To manufacture products by a thermoforming process, the metal ions of metals of groups 1,2 and 3 des Be derived from the periodic table. If one intends to produce Er-Certificates that degrade through exposure to light transition metal ions should be used. Sodium, calcium, Magnesium, zinc oleates or stearates for durable products or iron (III) stearate, preferably with free Stearic acid mixed, for degradable products. Other suitable soaps are found in Encyclopedia of Chemical Technology, 2nd Edition, Volume 7, p. 284, edited by R. E. Kirk and D. F. Othmer.

The inorganic material used in particulate form

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273U79 preferably has a hardness of less than 6.8 on the Mohs scale. Examples of inorganic materials are slate flour, dolomite (Mohs hardness 3.5 to 4.5), barite (Mohs hardness 2.5 to 3.5), types of calcium carbonate (Mohs hardness of chalk 3.0), kaolin (Mohs hardness 2.0 to 2.5), plaster of paris (Mohs hardness 1.5 to 2.0) or talc (Mohs hardness 1.0). The most suitable inorganic materials have a Mohs hardness of 3.0 or less. It is believed that a soft inorganic material has a significant effect in facilitating the thermoforming process, and it also appears to have a desirable effect on the feel of the thermoformed sheet. The inorganic material is preferably free from fibrous components such as asbestos fibers, since these can have a detrimental effect on the stretchability of the film during the thermoforming process. The inorganic material also preferably has a lamellar (or plate-shaped) structure, presumably because the lamellae can slide past one another * and facilitate internal movements within the film during thermoforming. The preferred lamellar or plate-shaped material is talc, especially talc which contains less than 1% asbestos fibers. The inventors achieved the best results with the Chinese talc known as Haichen-Talk.

The particles of the inorganic material should preferably be able to pass through an ASTM 140 (105 μm) sieve, and preferably 97% by weight of the particles should be able to pass through an ASTM 325 (44 µm) sieve. The preferred Materials should contain at least 30% by weight of particles with a largest dimension between 10 µm and 18 (im. The presence of very coarse particles has an adverse effect on the grip of the sheet material and prevents it thermoforming. It was also found that foils, the inorganic

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cal material, especially talc, is less visible Defects such as irregular lines, crepe-like appearances or patterns tend to affect the physical properties the film does not affect that to a greater extent

5 but look bad.

The compositions prepared according to the invention should also preferably contain 1% to 8% by weight of a pigment having a Mohs hardness of less than 6.8, many of which known pigments for polypropylene meet this condition. The presence of the pigment is particularly desirable in order to to get an even background for printing. If one intends a print, titanium dioxide is the pigment preferable. Titanium dioxide in the form of anatase is preferred because it has a Mohs hardness of only 5.5 to 6 and so less interferes with thermoforming or wrinkling the film. However, rutile-type titanium dioxide causes a Hardness of 6 to 6.5 in the long run less degradation of the film and can preferably be used if one the sheet material is used to manufacture containers that are expected to have a long service life. The titanium dioxide pigments, both the rutile and the anatase types should preferably contain up to 5% by weight of aluminum oxide and up to 2% by weight of silicon dioxide can be coated, the percentages being based on the total weight of the pigment. The percentages relate to the weight of the titanium dioxide. The pigment can be used in combination with up to 1/2 % By weight of an optical brightener, such as ultramarine, are used.

If foils are produced from compositions which contain inorganic material, the surface of the products produced from the foils by thermoforming generally has a good capacity for printing inks. However, this ability can be further improved if one

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subjecting the surface to an oxidative treatment of the kind described in "Polythene", second edition, p. 542 and p. 542 published by Renfrew and Morgan and published by Iliffe. The most suitable of these treatment methods is the use of a corona discharge. The oxidation treatment is desirable when the containers are thermoformed be made from foils obtained from masses that do not contain any inorganic material.

The invention also relates to a method for producing calendered films from the materials according to the invention manufactured masses, the process consisting of the following steps:

a) The mass is fed in powder form to a shear mixer and the polymer or copolymer component is added the mass by means of the shear mixer for melting,

b) the mass is transferred from the shear mixer to the Calender rolls while maintaining the polymer or copolymer in the molten state,

c) the mass is calendered and 25

d) the calendered mass is cooled and thus solidified to form a film.

The compositions can be calendered onto coated or uncoated fabrics to form products which consist of a one-piece textile fabric.

Shear mixers are mixers that generate heat by exerting a shear force on the polymer or copolymer generate and use this heat to increase the temperature of the poly-

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273U79 mers from a temperature which is at least just below the point at which the polymer is fixed, to a temperature which is just above the point at which it is molten, to exploit. Suitable shear mixers are described in "Polythene", Chapter 15, loc. Cit. The temperature of the polymer or copolymer is preferably increased to approximately 170 ^° C. in an internal mixer. The preferred internal shear mixers are a Banbury mixer or the combination of an extruder and a two roll mill.

The molten feed from the shear mixer is preferably fed to the calender rolls by means of a two-roll mill or by means of an extruder which may or may not be part of the shear mixer. The use of the two-roll mill or the extruder allows the feedstock to be fed to the calender step by step. The two-roll mill is preferably operated at temperatures higher than 175 ° C. Alternatively, the material fed to the calender by means of an extruder leaves the extruder at a temperature above 175.degree. The hottest roll of the calender also preferably has a temperature of 180 ^° C. or higher.

When shear mixing using a two-roll mill and loading of the calender by means of an extruder, the roll mill should be operated at a temperature of 18O ⁰ C to 200 ⁰ C, and the extruder should the polymer or the copolymer to a maximum temperature of at least 200 ⁰ C, preferably Bring up to 220 ^{° C.}

The films produced according to the invention with a thickness of preferably 0.05 mm to 0.5 mm can after a Thermoforming process with the formation of containers such. B. buckets for edible fats, documents for chocolate products and Boxes for gardening purposes are processed. Thicker foils,

z. B. with a thickness of 0.5 now to 2.0 mm, can through

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Thermoforming, ζ. B. Forming in a vacuum, with the formation of products such as vehicle components, such as dashboards, Door panels, floor and ceiling coverings, wheel arches, car seat fittings and luggage compartments, of cooling tower fillings and processed by packing for the treatment of waste water. For certain products it may be necessary to cover the deformed article with a suitable cellular foam material, e.g. B. with polyurethane foam or to fill in with another support structure. One can

10 also use the vacuum envelope method.

According to the invention, an embossed plastic film can also be produced by calendering compositions produced according to the invention to form a film, heating the film until at least its surface has become plastic, e.g. B. to 180 ⁰ C to 220 ° C _; by means of an embossing tool, preferably an embossing roller, which carries the embossing pattern, applies a pattern to the heated foil and cools the embossed foil. Products of the type indicated above can then be produced from such embossed films by means of thermoforming.

Comparative Examples A to E and Examples 1 to 5

Two propylene copolymers with a content of copolymerized ethylene of 8 wt .-% and 15 wt .-%, as in Table 1 described were obtained in powder form having an average particle size of 250 µm. The copolymers were mixed with various combinations of powdered additives as described in Table 1 by a Henschel rotary arm vortex mixer was charged with the copolymer and additives.

Each of the obtained powder mixtures was sequentially transferred to a Banbury mixer and heated to 170 ^° C

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273U79 heated, i.e. just above the melting point of the copolymer. The heated feedstock from the Banbury mixer was placed in a two-roll mill which was operated at 175 ° C to 180 ⁰ C. The feed from the mill was gradually fed to a row of rollers, which consisted of four steam-heated calender rollers arranged in the form of an inverted ¹ L ', as shown in FIG. The two upper rolls were at 185 ° C and the middle roll was heated to 180 ⁰ C and the lower roll at 175 ⁰ C. Where possible, the feed was fed to the calender over a period of 1 hour, during which time it was continuously calendered to form 0.3 mm thick film.

The melt index of the masses fed to the calender was monitored in order to have an indication of the extent of the dismantling taking place. Also the color change of the Mass was noted. These results are shown in Table 2. Attempts to calender polypropylene compositions that did not contain soaps, led to degradation, as a result of which the mass stuck to the calender rolls and became too usable Prevented calendering results.

The films produced according to Examples 1 to 5 were suitable for the production of margarine tubs by means of thermoforming.

The calenders used according to the invention are in the Drawings shown.

Fig. 1 is an illustration of the arrangement of the calender rolls in the form of an inverted ¹ L ¹ .

Fig. 1 shows the calender rolls 1, 2, 3 and 4, which are arranged in the form of an inverted ¹ L ¹ . The molten mass 5 gradually becomes the gap between the rolls

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1 and 2 supplied by means of a two-roll mill, not shown. The mass 5 is passed through the rolls to form a film calendered.

709883 / 09T4

Table 1

at
game Wt%
Ethylene im
Copolymer Meltin
dex des
Copolymers % By weight Stabili
sator
1
highly effective
stabilizer) Wt%
Stabilisa
gate -
2 Wt%
Stabili
sator
3 Wt%
Stabili
sator
4th % By weight Dilau
ryl- (L) or
Distearylthio
dipropionate (S] Wt%
Calcium
stearate Wt%
Talk * Wt%
TiO ₂ '** n β 2 0.25 - _ _ - 0.5 _ 3 a 2 0.018 - - 0.005 0.15} 5 0.130 - - η β 2 - - - 0.5 - 0.5 - - D. β 2 - 0.1 0.1 - - 0.5 - - £ 8th 2 0.2 - - - 0.50 L 0.20 - - 1 8th 2 0.25 - - - - 0.5 40 - 2 θ 2 0.25 - - - - 0.5 20th - 3 8th 2 0.20 - - - 0.50 L 0.20 AO - 4th 8th 2 0.25 - - - - 0.5 40 4th 5 15th ίο 0.25 - - - - 0.5 itO -

Stabilizer 1 is pentaerythritol tetra -, ^ - 3,5-di-t-butyl-4-hydroxyphenylpropionate
Stabilizer 2 is 2,2'-methylene-bis- (4-methyl-6-t-butylphenol)
Stabilizer 3 is distearyl pentaerythritol diphosphite
Stabilizer 4 is 2,6-di-t-butyl-4-methylphenol

* The talc used was a Haichen talc in particle form, 97% of the particles being characterized by “j an ASTM 325 sieve passed and at least 29% of the particles had a largest 'diameter <*> in the range from 10 μΐη to 20 μπ \. x *.

- ^ 4

The TiO _{2 used} was an anatase coated with 1.5% by weight of aluminum oxide and 0.7% silicon dioxide (percentages based on the weight of the TiO ₂ )

Table 2

CD QO 00

example Melt index change with dei 15 minutes. 30 min. ■ time 60 min. Color change A. 0 0.46 45 min. 0.74 acceptable color change B. 0.34 1.37 20.60 0.48 given up little color change C. 0.45 3.24 given up 48.40 - acceptable color change D. 2.64 1.60 1.55 - - severe color change £ 1.40 0.7 * 0. ^ 2 given up 1.00 severe color change 1 0.70 0.13 0.16 o.ye 0.15 acceptable color change 2 0.15 0.17 0.20 0.15 0.21 acceptable color change 3 0.16 0.12 0.13 0.21 0.13 acceptable color change A. 0.12 0.15 0.22 0.14 0.29 no discernible change in color 5 0.18 0.90 0.92 0.22 0.97 acceptable color change 0.83 0.95

VO

03

«Vco CO

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Claims (7)

1 claims 1. Crystalline polypropylene composition which can be calendered to form films and is a crystalline homopolymer contains of propylene and / or a crystalline copolymer of propylene with up to 25% by weight of ethylene, characterized in that that the mass is also a combination of a) 0.1% by weight to 1.5% by weight of a "highly active stabilizer system" b) 0.1% by weight to 2.0% by weight of a soap and c) 10% to 60% by weight of one in particulate form contains solid inorganic material. 2. Crystalline polypropylene composition according to claim 1, characterized in that the highly effective stabilizer system from pentaerythritol tetra-p> -3,5-di-t-butyl-4-hydroxyphenyl- 20 consists of propionate. 3. Crystalline polypropylene composition according to claim 1, characterized in that the highly active stabilizer system Tris (3,5-di-t-buty1-4-hydroxybenzyl) isocyanurate. 4. Crystalline polypropylene composition according to one of the preceding claims, characterized in that the inorganic Material has a Mohs hardness of 3.0 or less. 5. Crystalline polypropylene composition according to one of the preceding claims, characterized in that the inorganic Material is chalk. 6. Crystalline polypropylene composition according to Claims 1 to 4, characterized in that the inorganic material is talc 709883/0974 INSPECTED - Z- B 8314 1 or kaolin. 7. Crystalline polypropylene composition according to one of the preceding claims, characterized in that the particles of inorganic material are small enough to pass through a 44 µm sieve (ASTM No. 325 sieve). 8. Process for the production of calendered films using the crystalline polypropylene mass according to one of claims 1 to 7, characterized in that the mass of propylene homopolymer or copolymer and additives according to claims 1 to 7 feeds a shear mixer which melts the polymer component of the mass, and then transferring the mass to calender rolls while maintaining the polymer in a molten state and calendering the mass and then cools to form the film, and the film obtained is then optionally embossed. 9. The method according to claim 8, characterized in that the mass is the calender rolls of a two-roll mill feeds here. 10. The method according to claim 8, characterized in that that the mass of the calender rolls from an extruder 25 feeds. 11. Method of making an embossed film according to one of claims 8 to 10, characterized in that the by calendering a mass of the propylene homopolymer or -copolymer and additives according to one of claims 1 to 7 obtained film heated until at least the surface of the film is plastic, a pattern is applied to the heated film by means of an embossing tool embosses and the embossed film cools down. 709883 / 09U - y- B 8314 s3 273H79 12. Component of a motor vehicle, characterized in that it is thermoforming according to one of the claims 8 to 10 produced film is produced. 13. Container, characterized in that it is formed by thermoforming a film according to any one of claims 8 to 10 is produced. 14. Filler for a cooling tower or for a method of wastewater treatment, characterized in that it is produced by thermoforming a film produced according to any one of claims 8 to 10. 15. Product containing a one-piece textile fabric, characterized in that it is one by calendering A mass according to one of Claims 1 to 7 is produced on a coated or uncoated fabric. 7 03883/09 * 4