CA1061973A

CA1061973A - Matt and scratch-resistant films and process for their manufacture

Info

Publication number: CA1061973A
Application number: CA214,532A
Authority: CA
Inventors: Franz Breitenfellner; Roland Fink
Original assignee: Ciba Geigy AG; Alkor GmbH Kunstoffverkauf
Current assignee: Novartis AG; Alkor GmbH Kunstoffverkauf
Priority date: 1973-11-27
Filing date: 1974-11-25
Publication date: 1979-09-11
Also published as: JPS5085642A; NO143105B; DE2359060A1; CH583620A5; FI313674A7; NL7415476A; FR2252193A1; ATA946474A; NO743854L; DD114544A5; AU7575974A; GB1486638A; ES432265A1; SU605531A3; AT339052B; DE2359060B2; ZA747539B; NO143105C; FR2252193B1; SE413866B

Abstract

Matt and scratch-resistant films and process for their manufacture Abstract of the Disclosure Matt films having a scratch-resistant surface are obtained from moulding compositions reinforced with glass spheres if the extruded film is stretched while still in the molten state, and then allowed to cool. These films are suitable for use as coating materials, especially for furni-ture, doors and the like.

Description

~C~6~973 The inven-tion rel~-tes -to matt and scratch-resistant, amorphous -to crystalline films of -thermoplastics which are filled with glass spheres.
To manufacture mat-ted films it is customary to convert thermoplastic moulding compositions filled with fillers, for example wi-th ti-tanlum dioxide, in-to films. These films have the disadvantage that the surfaces can be scratched relatively easily, which restricts the range of applications, for exclmple the use as the top layer in a veneering ma-terial for furni-ture or doors.
Thermoplastic moulding compositions which contain glass fibres and/or glass spheres as a reinforcing and filling mate-rial are also known. These moulding materials are used for the manufacture of injection mouldings. For example, W. Kn8ss, Glaskugeln ("Glass Spheresi'), Industrieanzeiger 93, No~ 72, 1971, 1835 - 1838 and J. Ritter, Applied Polymer Symposium No. 15, 1971, 239 - 261 describe the general proper-ties of such injection mouldings of polyamides !filled with glass spheres and also mention that polyesters can be us~ as-theplastlcs.
Japanese Published Patent 73/05,257 describes moulding composi-tions of polyethylene terephthalate, reinforced with glass fibres and glass spheres, which are suitable for use in injec-tion moulding, and DT-OS 2,206,804 describes polybutylene tere-phthalates which con-tain either glass fibres or glass spherQs and can also be used for the manufacture of injection mouldings.
However, none of these publications mentions that high quality films with certain surface properties can be manufac-tured from thermoplastic moulding compositions reinforced with glass .

~ 6~973 spheres. Fur-thermore, so-called "reflec-ting films", which consist of a -thermoplastic and of which the surface is coated wi-th glass spheres, are already known. Since the gl~ss spheres are glued to these films, the scra-tch resistance of the ~ilms is only low.The invention is based on the objec-t of providing a shee-t ma-terial or film ma-terial which has increased scra-tch resis-tance for a given degree of mat-tness.
It has now been fo~md that films or sheets are matted and at the same time scratch-resis-tan-t if they contain glass spheres and the surface structure is formed by domes of the glass spheres which are still completely covered by thermo-plastic ma-terial. Surprisingly, -these films show no flaws, even in the case of thin films, and the strength of the films is no-t influenced adversely by the glass sphere filler. The matting of the surface is achieved in this case through the fact that the incident light undergoes diffuse scattering by the special surface structure.
Accordingly, the subject of the present invention are matted and scratch-resistant, amorphous to crystalline, films or sheets of film-forming thermoplastics and a filler, charac-terised in that the films or sheets contain 2 to 25% by weight, based on the weight of the polymer, of glass spheres of size from 0.5 to 75 ~, and that the domes of the glass spheres which project from the surface are also completely covered by the plastic.
Preferably7 the films or sheets con-taln 5 to 15% by weigh-t, especially 5.5 to 12~ by weight, of glass spheres and preferably the average size of the glass spheres is 0.5 to 20 ~1.

The films or shee-ts are manu~actured by ~eans of known devices from moulding compositions in which -the glass spheres are uniformly distributed in the thermoplas-tic. Sui-t~ble plastics are all film forming polymers. Plas-tics from which very -thin films can be manufac-tured are preferred.
Par-ticularly suitable plas-tics for -the manufacture of -the films or sheets according to the invention have proved to be poly-alkylene terephthalates, especially polyethylene tereph-thalates, and polyamldes, especially polyamide 6~ polyamide 6,6 9 poly-amide 11 and polyamide 12.
The plastic moulding compositions can contain custom-ary further additives, such as, for example 9 fillers, matting agents, such as micro-mica, titanium dioxide or suitable color-ants. As a further matting additive, preferably 0.01 to 5, and especially 0.1 to 2% by weight of micro-mica is admixed to the moulding compositlon. Furthermore, flameproofing sub-stances, for example tetrabromophthalic anhydride or decabromo-diphenyl can be present, optionally together with antimony trioxide. In order to prevent the films or sheets according to the inven-tion sticking to the surfaces of -the tools during manufac-ture or during further processing, known mould release agents, such as, for example, polye-thylene, waxes or silicones, can be added to the moulding compositions.
- The content and especially the size of the glass spheres depends on the film thickness and on the desired mat-tness. It has proved desirable that the average diameter of the glass spheres should be less than hal~ the film thickness. To assist the flawless embedding of the glass spheres in the ~L~63~73 plastic matrix, an adhesion-promo-tLng substance can be used in addition. In that case, the adhesion promo-ter can be added -together with the glass spheres -to -the plastic, or can be applied -to the surface of the glass spheres before these are mixed with -the plas-tic. Adhesion promoters which can be used are in particular -the compositions described as "si~es" w~ich are known for binding glass fibres or glass particles to plas-tics in which they are embedded.
The manufacture of the films according to the inven-tion is carried out with devices known for the purpose. To produce -the films, the thermoplastic moulding compositions, which contain, uniformly distributed, 2 to 25% by weight of glass spheres of slze from 0.5 to 75 ~, are converted -to a layer by extrusion from a slit die or circular die and stretched, while still in the molten sta-te, to -the point that the surface structure of the films or sheets is formed by pro-jecting domes of the glass spheres, which are still completely cavered by plastic.
The degree of crystallinity of the films or sheets according to -the invention can be con-trolled by the ra-te of cooling after extrusion, If rapid cooling is used, amorphous to slightly crystalline, translucent films or sheets are obtained,whilst on slower cooling predominantly more crystal-line products are obtained. The amorphous to slightly crystalline films or sheets according to -the invention can also be converted in-to films of high degree of crystallinity by a subsequent heat treatment. The amorphous -to slightly crystal~
line films or sheets can also first be warmed and thenbe 1~Eii1973 stretched biaxially, whereby crys-lalline films or sheets of increased strength are obtained.
The scratch-resistant film material ac~ording -to the invention can be laminated to o-ther materials, for example wood, glass, metal or o-ther plastics, ancL the customary adhes-ion promoters can be use~ for this purpose. Depending on the nature o~ the materials, an appropriate adhesion promoter will be employed, say an adhesion promoter which can be heat-activated and which has beforehand been applied either to the film material according to the invention or to the material to which the latter is to be laminated. In the case of lamina-tion of the films according to the invention to other plastic films, pre~erably, for example, of PVC, polyethylene, chlorina-ted polyethylene, ethylene/vinyl acetate, polystyrene or copoly-mers of, for example, acrylonitrile, butadiene and styrene, an alternative procedure is to extrude the films simultaneously and bond them to one another whilst still in the molten state.
m e film material according to the invention can be embossed in order to apply a pattern, wi-thout changing the sur-face structure consis-ting of domes (of the spheres). Accord-ingly, the matting and the scratch resistance are retained even after the embossing process. The embossing can also be carried out with laminated films of the material according to the invention and other plastics. Here, the embossing is also formed on the lower film if its softening point is lower than that of the material according to the invention.
A preferred field of use for the film material accord-ing to the invention is the manufacture of veneer materials, :

~QÇ;~ 3 for example for furni-ture manu-Eacture, for doors or for wall claddings. For -this pu~pose, it is possible -to use -the films according to the invention, provided with a veneer pa-t-tern, or -to use embossed laminated films. It is also possible to lamina-te a film, for example of rigid PVC, which has been provided with a veneer pa-t-tern, to -the film material according to the inven-tion. In -this way, a surface coating which has substantially better scratch resistance -than l~nown comparable materials is ob-tained in every case.
The attached figure explains the invention in relation to a laminate film. In this figure, 10 represen-ts a base layer of a Eilm-forming plastic, 12 represents an adhesive layer and 14 represents a film according to the invention.
It can be seen that spheres (16) are inc~xra~in the layer (l4), and in particulàr in such a way that the surfaces of the film according to the invention have a dome structure which is charac-terised in that the individual spheres (16) are enclosed by a continuous skin of the plastic matrix.
The examples which follow serve -to explain the inven-tion further. The scratch resistance was determined relative to a rigid PVC film, using a missile resistance tester, ~ype L~35 fromMessrsErichsen GmbH and employing a round disc of a special plastic as the missile. The percentages quo-ted are percentages by weight.
Example 1:
In the course of the polycondensation of a polyethyl--ene terephthalate, 5% oE glass beads of average diame-ter 5-15 ~9 ~ e~=~ BALLOTINI 5,000 (CP 02) were added. (These ~ ~r~ rk ; ~ 7 ~

~6~973 beads are manufact~red by Messrs Potters Ballotoni GmbH, 6719 Kirchheimbolanden). The polycondensa-te was extruded on a customary slit-die film installa-tion under conditions such that the material temperature was 270C a-t the outle-t posi-tion m e ~el-t which issues vertically from -the 300 ~ die gap was cast onto a cus-tomary cooling roller arrangement. The temperature of the firs-t cooling roller was 70C. '~he ratio of the roller speed to -the ou-tlet speed of the melt was so cho-sen that the film, in the molten state, was stretched uniformly in the longitudinal direction to a thickness of 30 ~. The predominantly amorphous film showed a matt surface which~ as was found from screen elec-tron microscope photographs, was caused by homogeneously distributed glass beads completely surrounded by the polymeric ma-trix. These pho-tographs showed that even glass spheres which project from the surface by up to 90% of their diameter, were surrounded (by matrix) without micro-flaws.
This film was laminated lo a known rigid PVC film, using commercially available adhesives, and embossed at film ~emperatures of 150C under otherwise customary conditions.
As a result of the prewarming before the embossing nip the film crystallised further~ so that it only softens completely after exceeding the crystalli-te melting point at approx. 2~0C.
; Irl the embossing nip itself~ the coarse s-tructure of the embossing roller was -transferred under the temperature and pressure conditions prevailing in the nip, without however pressing the domes into the surface. The embossing of the ; film surface was thus fixed predominantly by the PVC film, ~ ,.
'~

9~3 withou-t depic-ting the peak--to-valley heights of the embossing roller. It was possible to show, by screen electron micro-scope photographs, -that the "dome structure" Oî -the PET fi]m is still presen-t in the embossed laminate also.
The film has approximately the same degree of ma-t-tness as a rigid PVC film embossed with a matt sa-tin finish~ and has good scratch resistance. The missile resistance tes-t showed that a rigid PVC film already showed a glossy trace under a load of 150 gram force, whilst in -the case of -the film accord-ing to the invention no trace was detectable even at 2,000 gram ~orce.
Example 2 A PET/glass bead mixture manufactured from the same product and by the same process, but with 15% of glass beads added, was extruded on a customary film-blowing installation, at material temperatures of approx. 265C, from a circular die of 0.5 mm gap width to give 50 ~ thick films by even stretching in two directions at right angles to one another. These films were considerably more matt than those obtained according -to Example 1. The screen electron microscope photographs showed a substantially larger number of homogeneously distributed domes which were again completely surrounded by the polymer.
Lamination and embossing was carried out analogously to -Example 1. The embossed laminate was considerably more matt and had comparable scratch resis-tance.
Example 3-A film was extruded from a polyethylene t~rephthala-te according -to Example 1, which however additionally contained _ 9 _ 9~13 0.1% of TiO27 in accordance wi-th -the process mentioned in Example l; the film was comparatively somewhat more matt.
The screen electron microscope pho-tographsshowed that the pigments of particle size less than 0.5 ~ con-tributed only li-ttle to light scattering on -the surface but caused increased reflection of the incident light. The lamination and emboss-ing were carried out as indicated in Example 1.
The embossed film larninate was somewhat more matt than tha-t described in Example 1.
Example 4:
10% of glass beads were admixed to a polycaprolac-tam 6,6. This product was extruded on the slit die insta]lation described above, at material temperatures of 250C, onto a rol-ler cooled to plus 10C, so as to give a predominantly amor-phous film. The film, again in the plastic state, was stretched uniformly, from 300 to 30 ~, in directions at right angles to one anot,her.
The surface structure was comparable with that men-tioned in Example 1. This film was laminated and embossed in accordance with the process indicated in Example 1, using embossing temperatures of 150C. The screen electron micro-scope photographs again showed the surface structure consist-ing of domes.
~ .
A two-layer film of a polyeth~lene terephthalate con-taining 10% of glass beads (Crastin XB 2813) - layer 1 - and OI an ethyiene/vinyl acetate copolymer (EVA~ VA con-ten-t 32%, melt index 30 g/10 minutes) - layer 2 - was produced on a slit .

~ P6~9~3 die co-extrusion installa-tion.
With the sli-t die used, the ma-terial ch&nnels for layers l &nd 2 were respectively fed by single scre~ extruders of 90 &nd 60 mm ~ and -the melts of -the -two ma-terials were corn-bined with one ano-ther approx. 50 mm before -the end of the die, The -temperatures on -the extruder were so chosen that the material -temperature of the polye-thyLene tereph-thalate was approx. 275C &nd that of -the EVA approx. 220C. The die temperatures were set -to 280C~ resulting in a temperature of 270C in the melt which issued. The gap wid-th was 0.5 mm &nd the final film thickness was 200 ~ because of the plastic stre-tching of the melt. The layer thickness ra-tio was adjusted ~y adjusting the feed rate so that the adhesion promoter layer was approx. 20 ~ thick and the surface layer approx. 180 thick.
Because of the abovementioned plastic stretching of the melt, the dome-shaped surface, &nd hence the desired matting, were obtained. m e second layer, which does not contain &ny special fillers, in contrast remains completely smooth. The film thus manufactured is particularly suitable for lamination to other thermoplastic films o~ continuous laminating machines, since it is possible to avoid trapping air.
m is two-layer film C&n furthermore also be laminated thermally or by means of known adhesive systems and processes onto other web-shaped materials, for example fleece or paper, or onto wooden materials in sheet form.

During the polycondensation of a polyethylene .

~S1973 terephthalate, r)% (corresponding -to Example 1) o~ the glass beads mentioned in E~c~mple 1 were added to one mixture, and 6%
to another mix-ture~
; 1% of micro-mica was then also added to the first-mentioned mixture, con-taining 5% of glass beads, during extru-sion processing - as described in Example 1.
The predominantly amorphous films obtained from both polymers were laminated onto prin-ted rigid PVC films in the usual manner, and embossed at the same time. The printing inks were based on an acrylate polymer which at the same time serves as an adhesion promoter between the PETP film and the rigid PVC film. The film in which 1% of micro-mica was used, the filler content being the same, has be-t-ter transparency, comparable scratch resistance and greater ma-ttness.
This higher degree of mattness and lower cloudiness is particularly important in imitating natural veneers since the film laminated onto the original printed p~ttern should falsify the latter as little as possible.
The micro-mica used in this case was obtained via the German agent P.H. Erbsloeh, D-4 Dusseldorf, from Norwegian Talk, 5001 Bergen, Norway. 0Ø 744 (type Micro Mica U 1).

~; :

.~ . .

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Matted and scratch-resistant, amorphous or crystalline, films or sheets of film-forming thermoplastics and a filler, characterized in that the films which are stretched in the molten state contain 2 to 25% by weight based on the weight of the polymer, of glass spheres of size from 0.5 to 75 µ, and that the domes of the glass spheres which project from the surface of the films are also completely covered by the plastic.

2. Films according to claim l, which contain 5 to 15% by weight, preferably 5.5 to 12% by weight, of glass spheres.

3. Films according to claim 1 or 2, characterized in that the glass spheres have an average size of 0.5 to 20 µ.

4, Films according to claim 1, characterized in that the glass spheres are bonded to the plastic by an adhesion promotor.

5. Films according to claim 1, in which the plastic is a polyalkylene terephthalate.

6. Films according to claim 1, in which the plastic is a polyamide.

7. Films according to claim 5, in which the plastic is a polyethylene terephthalate.

8. Films according to claim 6, in which the plastic is polyamide 6, polyamide 6,6, polyamide 11 or polyamide 12.

9. Process for the manufacture of matted and scratch-resistant, amorphous or crystalline sheets or films from film-forming thermoplastics and a filler, characterized in that a plastic composition which contains, uniformly distributed, 2 to 25% by weight, relative to the plastic, of glass spheres of size from 0.5 to 75 µ, is converted in accordance with known processes to a layer form and is then stretched, in the molten state, to the point that the surface structure of the films or sheets is formed by projecting domes of the glass spheres, which are still completely covered by the plastic.

10. Process according to claim 9, characterized in that the material is co-extruded with a further film-forming plastic composition and the two are bonded and stretched in the molten state.

11. Process according to claim 10, characterized in that the stretched film in laminated onto another plastic film web, of PVC, polystyrene, chlorinated polyethylene, ethylene/vinyl acetate or copolymers of acry-lonitrile, butadiene, styrene and polyethylene.

12. Films according to claim 1, characterized in that the glass spheres are of size from 0.5 to 50 µ.

13. Process according to claim 9, characterized in that the glass spheres are of size from 0.5 to 50 µ.

14. Films according to claim 1, characterized in that a further matting agent is present.

15. Films according to claim 14, characterized in that 0.01 to 5%
by weight, relative to the polymer, of micro-mica are present.