CA1158011A

CA1158011A - Polyethylene article with improved adhesion

Info

Publication number: CA1158011A
Application number: CA000368763A
Authority: CA
Inventors: Roland Fink; Heinrich Heitz
Original assignee: Alkor GmbH Kunstoffverkauf
Current assignee: Alkor GmbH Kunstoffverkauf
Priority date: 1980-01-17
Filing date: 1981-01-19
Publication date: 1983-12-06
Also published as: DE3001636C2; ATE10505T1; DE3170555D1; EP0032731B1; EP0032729A1; EP0032731A1; AU6622381A; AU539720B2; JPS56104943A; DE3001636A1; AU539702B2; JPS56104944A; AU6622481A; CA1158010A; ATE13437T1; EP0032729B1; JPH0219137B2; JPS6029741B2; DE3167357D1

Abstract

Abstract A polyethylene article or foil containing finely divided cellulose and surface treated by corona, radiation, chemical activation or heat and having improved permanent adhesive properties.

Description

1~5~01~

; Polyethylene ~\rticle H~ Improved Adhesion This invention relates to polyethylene (PE) and particularly foils of ¦ polyethylene having improved adhesion characteri8tics, and to a process , for its production.
i PE foils are at present seldom used for decorative and hard wearing coatings on plates, wood products, paper products, etc. The limited ' ~dhesion to item of lacquers and printing inks is a disadvantage. This is i particularly so if the products must possess a high degree of resistance to abrasion, scratching, and chemical attack; for example, if used as the ~ surfaces for furniture and clothing.
i If such foils were to be effectively used for these applications it must be possible to employ the various carrier materials and subsequent processing with adhesives and machinery which have been used (albeit only to a limited extent) up to this present time.
I If it were possible to improve the surface and achieve the desired degree of permanent adhesibility then numerous new applications for ¦ polyethylene with its broad spectrum of characteristics would be opened ~Ip .
~ Particular advantages of polyethylene are its favourable environmental characteristics, the elimination of waste, and its basic properties of modification through polymerization processes and copolymerization with different monomers and fillers.
Compared with PVC, which has frequently been used for such applications in the past, the thermal forming resistance, for example, is considerably greater.

.~ ~

~ -~5~0 1 1 Such higher thermcll resistance permits economical coatlng, of plates alld ~ood products, using chemically reactive type adhesives. As is known, these adhesives must not react d~lring storage nor when remaining on the tools used in the coating equipment. In the present disclosure, this requirement is met provided the chemical reac~ion proceeds only at temperatureS above 80C. In contrast to the use of PVC, economical hot coating at temperatures in excess of 80C on presses and roller coating installations without subsequent cooling is possible, using high density polyethylene (HD-PE).
These processing requirements can be met by using impregnated paper, however, its applicability is restricted for example to simple and level surfaces found in furniture because of brittleness, sensitivity to moisture, limited storage life, and poor thermal imprinting characteristics.
There is thus a need for an economical thermal plastic foil based on PE which can be laminated to suitable carrier materials using reactive type adhesives at temperatures up to 140C without cooling, and with a chemical and physical resistance equal to or exceeding that found in presently known surface covering foils.
A prerequisite is that suitable lacquers, printing inks, and adhesive systems shall adhere permanently to the PE. This in turn requires permanent improvement of the surface energy characteristics.
Processes for the improvement of the adhesion characteristics and surface adhesion of films, especially polyolefine films are already known. One example of this is corona treatment (glow discharge treatment;

0 1 ~

(see ~unststoffe 59 (1979), pages 71 - 75; Published proceeclings of the ?~unich Adhesion and Improvement Seminar, 1979, pages 60-70). This treatment results in considerable improvement, but the effect disappears during storage and/or under the eEfect of high temperature.
~ further process comprises the flame treatment of foils. Here the same disadvantages are found as in corona treatment. Chemical treatment with ozone, fluorine, chlorine, etc, is also known. A particular disadvantage is the brlef cllemical aggressiveness of such agents which can cause problems. Irradiation using high energy beams such as electron beams, ultra-violet radiation, laser beams, and the like can also be employed. These processes are relatively expensive and in most instances require additional use of sensitizers and thus the permanence of the effects achieved is variable.
A permanent improvement in surface adhesion can be achieved by chemical grafting with high energy beams. However, this process is too costly for the general areas of application considered here.
It is an object of the present invention to mitigate the foregoing problems and to provide both an improved foil and a method for its production.
~n As here disclosed, this is achieved in a polyethylene foil of which the adhesion characteristics have been improved by means of surface activation, and which is characterized by the fact that it contains fine grain cellulose.
The inventive idea is based on the surprising fact that a content of finely divided cellulose in PE improves the effectiveness and the 1~58~1~
durability of a s~lrface improvement, so t~at the ~oils of sucll materLal are particularly well suited to t~le areas of application discussed above.
Using suitable lacquering systems the demand for such characteristics of use as wear resistance, resistance to scratching and to chemical damage, can be optimally satisfied in the same manner as by adhesion with the urea-formaldehyde resins (UF resins) used in the furniture industry.
For coatings on sheet metals it is also possible to use more economical systems than are necessary for PVC adhesion.
Fine grain cellulose preferably produced ln the sulphite or sulphate processess are suitable. Natural or recycled cellulose may also be used.

It is desirable that the quantity of cellulose lie between 3 to 50%
by weight, based on the sum of weights of PE and cellulose. If a content of 50% is exceeded, the strength characteristics are drastically diminished.
Below 3% the required improvement of the surface is insufficiently pronounced. It is preferred that the cellulose content of the foil be between 3 and 30% by weight.
The degree of fineness of the cellulose used in the foil lies best between 1 and 100 um for a fiber thickness of 10 to 30 ~m. The use of finer particles becomes too costly; if larger particles are used problems in the production of smooth and thin foils arise. For natural and regenerated cellulose, the particles can be up to 100 ~um thick for a ma~imum mean length of 200 um without the occurrence difficulties in the production of the foil.

1 15~

.~11 types of polyethylenes are s-litable including high density polyethylene, low and medium density polyetilylenes, and copolymers, which have a thermal resistence VSP/A above 80C as ~lell as mixtures of these materials. Those copolymers with vinyl bonds and long chain ~-olefines particularly pre~erred.
In addition, the new Eoil can also contain mineral fillers. Fillers of this kind are already known for polymer foils. Especially suited and preferred are mica, talc, silicates, and silicic acid in their various forms. Examples of other usable mineral fillers are carbonates, particularly calcium carbonates such as chalk and limestone, magnesium carbonate and the like.
Such characteristics as Vicat point, Shore hardness and strength can be influenced by the addition of suitable mineral fillers. In the event that mineral fillers of this type are available, it is expedient that the foil contain 3 to 50% by weight, and preferrably 3 to 30% by weight, based on the sum of the weights of polyolefine and cellulose.
The foil can also contain one or more organic modifying agents.
These serve to control toughness, amenability to calendaring, e~trudability, and similar characteristics, a preferred group for this are the block polymers of styrol with butadiene or isobutylene or isoprene.
Other suitable modifying agents are copolymers based on styrol-butadiene, meChacrylate-butadiene-styrol. Polyolefines, containing functional groups, are particularly suitable for influencing special physical characteristics and adhesibility. It is expedient that modifying additives be present in quantities of 0.5 to 20% by welght, preferably 1~58~
from 2 to lO~ by weight, based in each instance on the sum oE the weights of polyolefine and cellulose.
The replacement of cellulose by wood dust is not norrnally recommencled for the uses anticipated becallse of its inherent colour, lack of cleanliness, insufficient resistance to light, and the change of colour with temperature.
~ loreover, wood dust of comparable particle si2e (Lignocel* HB
150) displays the same poor adhesion characterlstics when comparable adclitives and weight treatment are used as PE without additives.
The improved effectiveness of the corona treatment caused by the addition of cellulose is indicated by the test results shown in Table I.
This shows the relation of surface tension (Dynes/cm) for specific energy of the corona treatment for polyethylene formulations with and without the addition of cellulose.
Table I
Specific F.nergy I 0 1 0.8 11.25 1 2.5 1 5O0 Surface tension (Dyneslcm) without ¦ 34 ¦ 36 1 38-42 1 44 1 48-52 cellulose Surface tension (Dynes/cm).20% by wt.l 34 1 46 1 52 1 56-61 1 61-72 The effect of the cellulose additives for similiar corona treatment is shown in Table 2.

* Trade Mark ~5~
Table 2 Foil I Polyethylene Cellulose Surface tension Surface tension numberl % by wt¦ before corona after corona treatment treatment - ~ es/cm) (Dynes/cm) 1Polyethylene 1) _ 34 - 36 44 - 48

2" 1) 1 34 - 36 5O

3" 1) ~ 34 - 36 > 61 6" 1) 10 3~ - 36 72 7" 1) 20 34 - 36 72 1) Hostalen* GC 7260.

The permanence of the effect of the corona treatment can be seen from Table 3, showing the surface in dynes/cm.

* Trade ~lark .. . . , . .. . . ~ .

I l~gV 1 3 Table 3 ~. ~ I
Foil No.l I.ength of Tlme at Room Temperature 1 hour 3 Days 3 Weeks 3 Months __ _~ _ 1 1 48 45 38 _~
2 1 ,58 1 52 1 48 1 46 1 7 1 72 ~ 72 1 72 1 72 The known phenomenon that the effect of corona treatment is drastically downgraded by storage (Kunststoffe, No. 69 (1979), p. 74) was not observed for the novel foils.
Also, the familiar fact thnt the effect disappears rapidly and almost completely on heating to a temperature above of 60C was not confirmed.
The independence of the effect from storage time and temperature was also shown in test results obtained with calendared foil.
The accompanying drawing shows the relationship of surface tension to 140 day storage of two similar foils at temperatures of 20C and 80C
respectively.

7~) ~15~01~
Explaining the drawlng in more detail the wetability in Dynes/cm of a foil comprising of polyet~lyler~e with a 10% cellulose content is related to duration of storage after irradiation. The wetability prior to corona treatment amounted to 35 Dynes/cm; and as a result oE the treatment rose to 75 Dynes/cm. The respective samples were then stored at 20 and at 80C
for 140 days. No change in wetability was observed.
It is known that there is not always a correlation between adhesion and surface tension tProceedings of the ~lunich Improvement Seminar, 1979, ; page 60). The adhesion dependency on cellulose content was therefore tested using a urea-formaldehyde resin adhesive which showed no adhesion to polyethylene. The permanence of adhesion was tested after storage at 9o C
Table 4 shows the results of a serles of tests in which the Eoils of identical PE formulations were corona pre-treated under identical conditions and pressed with urea-formaldehyde resin at 130C for 10 seconds at lO kPITcm2~

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These results also inclicate the fact that the increase of surface energy with cellulose ~lld the ~Ise of corona treatment ls permanent in contrast to known foils.
It can be seen ~rom Table 5 that the aclhesion of PE with the addition of cellulose is not a "monolayer" effect. The samples were corona pre-treated at identical intensities, surface tension was again measured and they were then rubbed down with a woolen cloth, surface tension was measured and then the samples were pressed with the urea-formaldehyde resin under the same conditions as before.

Table 5 HD-PE HD-PE HD-PE
without with 20% with 20%
__ filler chalk cellulose Surface tension l l l after corona I Dynes/cm 1 52 ¦ 58 1 61-72 treatment Surface tension l l l after wiping I Dynestcm 1 32 1 32 1 38 Resistance to peeling after wiping I kP/2.4cm 1 0 1 0.2 1 2.5 1 1 5 ~
Analogously, foils with !~ore than 5% cellu:Lose content cemented one year a~ter pre-treatment displayed no change in adhesion. The other previously dlscussed pre-treatmerlt processes resulted also in essentially good adhesion if the surface tension and the permanence were sufficlently high.
A further teaching oE this disclosure is a process for the production of polyethylene foll with improved adhesion in which the foil is shaped by conventional methods and sub~ected to surface activation treatment, and characterized by the fact that fine particle cellulose is added as a filler. It is preferred that 3 to 50% by weight, and especlally preferred that 3 to 30~ by weight of cellulose is added, based on the sum of the weights of polyolefine and cellulose. Cellulose fibers are suitable at a length of up to 200 ~Im for a mean diameter of up to 100 ~m at corresponding foil thicknesses.
The above statements apply in relation to the preferred polyethylenes. All suitable conventional production methods known to those skilled in the art may be employed in making the novel foils. The adhesion improvement is achieved whether the cellulose is added in the form of powder or as a granulated master batch (PE base).
During production of the foil additional mineral fillers and/or modifying agents can be added. For these the data mentioned above apply.
In general surface activation can be effected by means of irradiation or by treatment with a flame or ozone. Corona treatment is preferred.
Other irradiation methods using electron beams, ultra-violet rays, or lasers may be employed.

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j , ~801~
i ~s discllssed, surface adhesLon of polyethylene oils can be considerably improved by the present dlsclosure and the use of foils of this type for luminating coating, printing~ lacquering, and adhesion, especially in modern installatiolls which make use of short processlng times at the highest possible temperatures is greatly facilitated and in some instances, becomes possible for the first time. ~dhesion of the novel foils, for e~ample to chipboar(l panels by means of urea-formaldehyde resin at coating temperatures between 80 and 140C for a 30 second pressing time displayed no deterioration even after a period of several months.
Printing inks, such as those based on terpolymers from the vinyl chloride-vinyl acetate-maleic acids of vinyl polymers containing OH-groups and conventional PE printing inks, and reactive lacquers, for example, those based on polyurethane melamine resins as well as ultra-violet hardened polyester epoxide and polyurethane acrylates all showed equa]ly good adhesion. Even after 1,000 hrs of test weathering and tropical testing it was not possible to detect any change in adhesion according to ! AS~ standard D2142-63T.
The characteristics of the foils could be widely varied by the addition of mineral fillers and/or organic modifying agents without any deterioration of the advantageous adhesion characteristics. As an example, the surface adhesion achieved by the corona treatment of a foil consisting of 95 parts polyethylene and 5 parts cellulose was not affected by the addition of 20 or 30 parts talc.
Conventional dyes and pigments are not disadvantageous.

- 13 ~

, .

I ~ 5~0 ~ 1 i The noveL foils can be bonded d~rectly by fusion to metals, wood, polymers and copolymers with polar groups and the like, without adheslves, and yet display good and permanent adhesion.
I.amination i9 also possible at low temperatures, e.g., uslng epoxy resins and polyurethanes or vinyl acetate copolymers.
The following examples illustrate the invention further.
Example 1 Polyethylene MfI 190/2 = 8 (g/10 min) density, 0.958 g/cm3 (Hostalen GC 7260) and cellulose having a particle size greater than 50 ~Im (~rbocel* B 600/30) were mixed in a weight ratio of 1:1 and plasticized at 160C for 10 min in a rolling mill cooled and then granulated.
10 parts by weight oE this granulate were mixed with 90 parts by weight of the same polyethylene and then extruded from a single screw extruder 60mm in diameter having a broad slot nozzle at a mass temperature of 180C to form an 80 ym thick foil.
Corona treatment was carried out at a strip speed of 5m/min (~emes VM
pre-treatment equipment). The foil so treated displayed the following characteristics:

2n - 14 ~-~4 I~S~Ol~

Surface tension after 1 hour 58 dynes/cm 3 weeks 48 dynes/cm 3 months 46 dynes/cm ! untreated 34-36 dynes/cm Thermal resistance: VSP/A 125~C

Hardness Shore D 61 Tensile strength (longitudinal) 28N/mm2 Tear strength with UF resin adhesion: 1) ~3.0 kp/2.4cm foil tear 1) Formulation 100 parts/wt Aerolite* 306 50 parts/wt W 170* hardener 70 parts/wt water Pressing conditions:
Temperature 130C; time 10 seconds; pressure 10 kp/cm2 ~dhesion was carried out 3 days after the pre-treatment, using a conventional chipboard panel Example 2 (Comparison) The polyethylene granulate used in Example 1 was extruded and activated without additives under the conditions quoted in Example 1.

*Trade Mark 0 ~ ~
i Surface tension after 1 hour 50 Dynes/cm 3 weeks 38 Dynes/cm 3 months 36 Dynes/cm untre.lted 34 36 Dynes/cm Thermal resistance: VSP/A 125C
Hardness Shore D 60 Tensile strength ~longitudinal) 30 N/mm2 Tear strength (adhesion as in Example I) insufficient E~ample 3 A mixture consisting of 92.5 parts by weight of polyethylene MfI
190/2 = 0.8 g/10 min density 0.962 gicm3 (Eltex* B 2008 P) 2.5 parts by weight S-B-S blockpolymer (CariElex* 1102) 5 parts by weight of cellulose (Arbocel* B600/30) and 10 parts by weight of TiO2 was mixed in powder form.
Plastification took place in a roller mill at 150C, calendaring at a roller temperature of 140 - 180C. The activation treatment of the 80 ,um thick film was carried out on both sides under the conditions cited in ~0 Example I. The foil so obtained was lacquered with a polyurethane Iacquer (consisting of Desmophen* 1300 and Desmodur* HL) according to the manuEacturer's recommendations.

Sur~ace tension after 1 hour 61 Dynes/cm 3 weeks 61 Dynes/cm 3 months 61 Dynes/cm * Trade Mark 1~580~1 i untreated 34-36 Dynes/cm ThermaL resistance: VSP/A 130C
Hardness Shore ~ 61 Tensile strength (longitudi.nal) 32 N/mm2 Tear resistance after adhesion according to Example I > 3.5 kp/2.4cm - foil ~ tear ~dhesion of the lacquer after tropical test: inseparable Ad)lesion of the lacquer after 600 hours Xenotest: inseparable . (According to ASTM standard D2141-63 T) ¦ Example 4 . i~ foil from a mixture consisting of 95 parts by weight of polyethylene as in Example 3, 5 parts by weight oE the cellulose in Example 3, and 30 parts by weight of magnesium-silicate (Mistron vapor), and 10 parts by weight of TiO2 was calendared as in Example 3 and the 80 ~m thick foil activated in the same manner.
~ Lacquering was carried out with a modified lacquer based on melamine resin ~Cymol* 301).

. Surface tension after 1 hour 61 Dynes/cm 3 days 61 Dynes/cm ¦ 3 weeks 61 Dynes/cm untreated 35 Dynes/cm - 17 :

1 158~ ~ 1 Thermal resistarlce VSP/A 133C
Hardness Shore D 65 Tensile strength (Longitudinal) 33 N/mm2 Tear resistance af~er aclhesion according to Example I > 3.75 kp/2.4 cm, foil tear Lacquer adhesion according to the loads as in Example 3: inseparable Example 5 A mixture of 60 parts by weight of the polyethylene as in Example 3, 40 parts by weight of the cellulose according to Example 3, and 10 parts by ~eight Ti2 was calendared as in Example 3 to an 80 ~m foil which was then activated accordlngly.
Lacquering was carried out using an ultra-violet reactive lacquer (Corona*~ type 2127) based on polyurethane acrylate~

Surface tension after 1 hour ~ 72 Dynes/cm 3 weeks ~ 72 Dynes/cm 3 months ~72 Dynes/cm untreated 35 Dynes/cm Thermal resistance VSP/A 135C
~ardness Shore D 65 Tensile strength (longitudinal) 21 N/mm2 Tear strength of the adhesion ~ 3.5 kp/2.4 cm foil tear Lacquer adhesion as in Example 3 * Trade Mark - lc3 -.
. ~ .~ ~

1 ~ 5 ~
E.cample 6 a) i~ mixture consisting of 80 parts by weight of polyethylene as in E~ample 3 and 20 parts by weight of ceLlulose accordLng to Example 3, was treated as in E~ample 3.

Surface tension after 1 hour ~ 72 Dynes/cm 3 weeks ~ 72 Dynes/cm 3 months ~ 72 Dynes/cm untreated 34-36 Dynes/cm Thermal resistance VSP/A 130C
Hardness Shore D 64 Tensile strength (longitudinal) 25 N/mm2 This foil was cold rolled (20C) onto a chipboard panel that had been coated with epoxide adhesive DC 8720 ~made by Daubert, Middlewich, UK).
After 12 hours of storage the bond could no longer be broken without damage. Corresponding results were obtained using a modified vinyl acetate dispersion (HER foil adhesive, made by Isar-Racoll).
b) A mixture of 90 parts by weight of the polyethylene as in Example 3, ~ and lO parts by weight of the cellulose according to Example 3, were -`19 ~

. ~ .

11580~1 ~ treated as ln Example 3.
i Surface tension aEter l hour ~ 72 Dynes/cm , 3 weeks ~ 72 Dynes/cm ¦ 3 months ~ 72 Dynes/cm I ~lntreated 34-36 Dynes/cm i Thermal resistance 128C
¦ Hardness Shore D 64 ! Tensile strength (longitudinal) 27 N/mm2 This foil was cold rolled (20C) onto a chipboard panel that had been coated with epoxide adhesive DC 8720 (Daubert, Middlewich, UK). Afte~r 12 hours storage the bond could no longer be broken without damage.
Corresponding results were also obtained with the modified vinyl acetate dispersion (HER foll adhesive~ Isar-Racoll).

Example 7 a) A mixture consisting of 90 parts by weight of polyethylene as in Example 3 and 10 parts by weight of cotton ground to a fiber length of O.lmm and 10 parts by weight of TiO2 was prepared and calendared under the conditions cited in Example 3 to form a 300Jum foil and corona treated as in Example l.

~ ., ~, 1158 ~

Surface tension a~ter 1 hour 61 Dynes/cm Z 3 weeks 58 Dynes/cm 3 months no information yet untreated 35 Dynes/cm Thermal resistance VSP/A 125C
Hardness Shore D 60 Tensile strength (longitudinal) 18 N/mm2 Tear strength after adhesion as in in Example I 3.2 kp/2.4 cm b) A batch according to Example I was produced from polyethylene MfI
190/2 = 17 ~g/10 mln) and density 0.918 g/cm3 (Lupolen* 1800 s) and cellulose (Arbocel* B 600-30). 10 parts by weight of this were mixed with 90 parts by weight of lubricant containing polyethylene MfI 190/2 = 0.6 (g/10 min) density 0.92 g/cm3 (Hostalen* F 2024) and as in Example I were extruded at a mass temperature of 190C to form a 0.5 mm thick foil and then corona treated. The following characteristics were measured for this foil:

Surface tension after 1 hour 58 Dynes/cm 3 days 58 Dynes/cm untreated 28-30 Dynes/cm The removal test after adhesion according to Example 6 a) using Epoxide adhesive DC 8720 resulted in damaged separation.
* Trade Mark ~i 1~S8~11 ! Example 8 A foil of high density polyethylene according to Example I (HD-PE) ; (Hostalen GC7260) containing 5% cellulose and a foil from an identical.
polymer without cellulose was subjected to flame treatment and then the wetability of the surface was investigated. The results are shown in the following table 6.

~0 , . .... ....

l~so,al Ta hle 6 I Surface tension I I Before flame treatment I After flame treatment I Dynes/cm I Dynes/cm ~ ~ - - -I
i iHD-PE I 34 - 36 1 38 - 40 l l l l IHD-PE+5% Cellulose 1 34 - 36 1 45 - 48 . l l Example 9 A mixture of 95 parts by weight of polyethylene as in Example 3 and 5 parts of alkali cellulose 30,um thick, 0.6 mm long were homogenized in a rolling mill at 150C, drawn out to form a Q.5mm thick foil and then activated as in Example l.
Cementing as in Example 1 resulted in good adhesion. The surface of the film was unsatisfactory.

Example lO
10% of an ethylene vinyl alcohol copolymer (30% vinyl alcohol) was blended with a mixture of polyethelene and cellulose according to Example 1 and then extruded and pre-treated as in Example 1.

1 1 5~

Surface tension after 1 hour 7 61 Dynes/cm 3 weeks ~ 61 Dynes/c~
3 months ~ 61 Dynes/cm untreated 3~l-36 Dynes/cm Thermal resistance VSP/A 122C
! Hardness Shore D 56 Tenslle Strength (longitudinal) 31 N/mm2 Tear Strength according to adhesion as in Example 1 ~ 3.5 kp/2.4 cm foil tear Example 11 The foil according to Example 6 b) was after pre-treatment, by means of a 50 ~m thick film of ethylene acrylic acid copolymer (EAA resin 455 E) pressed with a chipboard plate at a press temperature of 130C and a pressure of 10 kp/cm2. The bond between the foil of Example 6 b) and the EAA film was inseparable. When the assembly was torn from the chipboard panel, panel tearing occurred.
Example 12 A mixture of 70 parts by weight of linear low density polyethylene (Dowlex* 2045) and 30 parts by weight of cellulose (Arbocel* B 600/30) was calendared as in Example 3 to a 100 ~m ~oil and then activated accordingly. The foil was cold pressed onto cardboard with urea resin consisting of 100 parts Aerolite~, 70 parts water, and 50 parts of hardener (Ciba Geigy), pressed onto itself at room temperature and then stored for 24 hours at room temperature. When the foil was torn away from the cardboard the cardboard separated. When the foil was torn from itself, splitting resulted.
* Trade Mark .; ,~, ,

Claims

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

1. Polyethylene article with adhesion characteristics improved by surface activation, containing fine particle cellulose, having a mean particle diameter of from 5 to 100 µm and a maximum mean length of 200 µm.

2. A polyethylene foil according to Claim 1, characterized in that it contains 5 to 50% by weight cellulose, based on related to the sum of the weights of polyethylene and cellulose.

3. A foil according to Claim 2, characterized in that it contains 3 to 30% by weight cellulose.

4. A foil according to Claim 1, characterized in that the mean particle diameter of the cellulose amounts to 5 - 100 µm, and the maximum mean length of the cellulose is up to 200 µm.

5. A foil according to Claim 4, characterized in that it contains a cellulose produced by the sulphite or sulphate process, and having a thickness of 10 - 30 µm and a length of 5 - 100 µm.

6. A foil according to Claim 1, characterized in that the poly-ethylene is selected from polyethylenes of high, medium and low density, a mixed polymer with vinyl bonds or long chain olefins with a thermal resistance VSP/A above of 80°C, or a mixture thereof.

7. A foil according to Claim 1, characterized in that the surface is activated by means of irradiation.

8. A foil according to Claim 6, characterized in that the surface is activated by means of corona treatment.

9. A foil according to Claim 7, characterized in that the surface is activated by means of electron irradiation, ultra-violet irradiation, or laser irradiation.

10. A foil according to any one of Claim 1 to 3, characterized in that the surface is activated by flame or with ozone.

11. A foil according to Claim 1, containing a mineral filler.

12. A foil according to Claim 11, containing mica, talc, silicic acid, silicate or TiO2.

13. A foil according to Claim 11 or 12, containing 1 to 50% by weight of mineral fillers, based on sum of weights of polyethylene and cellulose.

14. A foil according to Claim 1, characterized in that it contains a modifying agent in addition.

15. A foil according to Claim 14, characterized in that the modifying agent is based on styrol and elastomers.

16. A foil according to Claim 15, characterized in that the elastomer is a blockcopolymer of styrol with butadiene or styrol with isobutylene or a styrol with isoprene.

17. A foil according to Claim 14, characterized in that the modifying agent is a copolymer or a graft copolymer of ethylene with reactive monomers.

18. A foil according to any one of Claims 14 to 16, characterized in that it contains 0.5 to 20% by weight of modifying agent based on the sum of the weight of polyethylene and cellulose.

19. A process for the production of polyethylene foil with improved adhesion characteristics by forming of the foil according to conventional methods in the use of a surface activation treatment, and characterized in that fine particle cellulose having a mean particle diameter of from 5 to 100 µm and a maximum mean length of 200 µm is added as a filler.

20. A process according to Claim 19, characterized in that 1 to 50%
by weight cellulose is added, based on the sum of weights of polyethylene and cellulose.

21. A process according to Claim 20, characterized in that 3 to 30% by weight cellulose is added.

22. A process according to any one of Claim 19 to 21, characterized in that the cellulose has mean particle with of 5 - 100 µm and a maximum mean length of 200 µm respectively.

23. A process according to any one of Claims 19 to 21, characterized in that the polyethylene is selected from high, medium or low density vinyl bonds, or long chain olefines with a thermal resistance VSP/A in above 80°C or a mixture thereof.

24. A process according to Claim 19, characterized in that the surface is activated by means of irradiation.

25. A process according to Claim 24, characterized in that the surface is activated by corona treatment.

26. A process according to any one of Claims 19 to 21, characterized in that the surface activation comprises, electron beam irradiation, ultra-violet irradiation, or laser irradiation.

27. A process according to any one of Claims 19 to 21, characterized in that the surface is activated by treatment with a flame or ozone.

28. A process according to Claim 19, including the step of adding characterized in a mineral filler to the foil.

29. A process according to Claim 28, the mineral filler comprising mica, talc, silicic acid, silicates, or TiO2.

30. A process according to Claim 28 or 29, the mineral filler comprising 1 to 50% by weight based on the sum of the weights of polyethylene and cellulose.

31. A process according to Claim 19, characterized in that a modifying agent is added to the foil.

32. A process according to Claim 31, characterized in that the modifying agent is based on styrol and elastomers.

33. A process according to Claim 32, characterized in that the modifying agent comprises a blockcopolymer of styrol with butadiene or styrol with isobutylene or styrol with isoprene.

34. A process according to Claim 31, characterized in that the modifying agent comprises copolymers or graft copolymers of ethylene and reactive monomers.

35. A process according to any one of Claims 31 to 33, characterized in that 0.5 to 20% by weight of modification agent is added, based on the sum of the weights of polyethylene and cellulose.

36. The use of a foil as defined in any one of Claims 2 to 4 for hot or cold coating with or without adhesives, printing, or lacquering.