[0001] The invention relates to a shaped article with a marking on a thermoplastic substrate,
which marking is made by foaming the thermoplastic by means of high-energy irradiation.
[0002] The invention also relates to a process for the manufacture of the shaped article
with a marking on a thermoplastic substrate.
[0003] Such shaped articles are known from EP-A-469982. From this patent specification it
is known to make a marking by subjecting a thermoplastic to high-energy irradiation,
as a result of which moisture or air present expands and forms bubbles, causing local
foaming of the material.
[0004] By the term 'marking' in the present application is understood a pattern containing
information, such as an image, an emblem, a logo, a text consisting of letters and/or
digits, a code, such as a bar code etc., or a pattern with an aesthetic or decorative
function.
[0005] Examples of shaped articles bearing a marking are housings of electronic or electrical
equipment, keys, buttons, publicity signs, nameplates, company name signs, etc. Other
examples are calibrated containers, such as measuring beakers, syringes and coffeemaker
reservoirs.
[0006] Increasingly, such markings are applied by subjecting the shaped article to high-energy
irradiation in the pattern of the marking, for instance by means of a laser beam,
causing the synthetic material to foam.
[0007] An advantage of such a marking is that it can be applied very accurately on the desired
spot. A further advantage is that the shaped articles can be manufactured in series
in the known manner without application of a marking, while subsequently any desired
marking, different for each individual object, can be applied. An additional advantage
of such a marking is that it can be applied simply on mouldings with curved surfaces.
[0008] A drawback of the known moulding with the marking is that the marking is not abrasion
resistant. Fast abrasion of the marking on for instance keys or buttons may result
in illegibility, which may be the cause of incorrect setting of equipments and, in
consequence, unsafe situations.
[0009] The aim of the invention is to provide a moulding which does not have this drawback.
[0010] This aim is achieved in that the thermoplastic synthetic material contains an agent
which, due to the action of the high-energy irradiation, has caused crosslinking at
the spot where the foaming of the thermoplastic synthetic material has occurred.
[0011] A further advantage of the moulding according to the invention is that the marking
possesses good resistance to solvents.
[0012] Mouldings of a thermoplastic synthetic material comprising an agent are also known
from EP-A 0 566 312 and EP-A 572 178. In these european patent applications, the agents
are one or more compounds selected from the group consisting of tetrazole compounds,
and also sulfonylhydrazide compounds, nitroso compounds and azo compounds having a
decomposition temperature of 210°C or more. However, these agents ensure foaming of
the thermoplastic synthetic material and both documents are silent about the occurrence
of crosslinking.
[0013] The moulding may in principle contain any thermoplastic which can be foamed by means
of high-energy irradiation in order to serve as substrate for the marking. Preferably,
ABS (acrylontrile-butadiene-styrene copolymer) is used. Acrylontrile-butadiene-styrene
copolymer is described for instance in EP-A-104695, in which it is described as a
polymer composition consisting of:
A. 5-100 wt% of one or more graft copolymers obtained by polymerizing 10-90 parts
by weight of a monomer mixture comprising
20-40 wt% of an acrylic compound,
60-80 wt% of a vinyl aromatic compound, and
0-20 wt% of one or more unsaturated compounds,
in the presence of 10-90 part by weight of rubber,
B. 0-95 wt% of one or more copolymers obtained by polymerizing
60-80 wt% of vinyl aromatic compounds,
20-40 wt% of acrylic compounds,
0-20 wt% of one or more unsaturated compounds.
[0014] Suitable acrylic compounds are acrylonitrile, methacrylonitrile alkyl acrylate, alkyl
acrylate or mixtures thereof.
[0015] Suitable vinyl aromatic compounds are styrene and substituted styrene compounds like
alpha-methylstyrene, p-vinyltoluene or mixtures thereof.
[0016] The rubber content of the graft copolymer is preferably between 15 and 50 wt% relative
to the graft copolymer.
[0017] Suitable rubbers are butadiene rubbers like polybutadiene, butadiene-styrene, butadiene-acrylonitrile
or butadiene-acrylate rubber.
[0018] Other examples of thermoplastic synthetic materials which foam when exposed to high-energy
irradiation are polypropene, polyethene, polyamide, polyesters, polycarbonate, thermoplastic
elastomers or mixtures of the above-mentioned polymers like acrylonitrile-butadiene-styrene
copolymer with for example polyamide, polycarbonate or copolymers of styrene and maleic
anhydride.
[0019] High-energy irradiation of a surface is preferably understood to be irradiation of
a surface with a laser beam.
[0020] The agent which brings about the crosslinking does not produce or hardly produces
this effect at the processing temperature of the thermoplastic synthetic material,
but mainly does so under conditions at which the shaped article is subjected to high-energy
irradiation according to the invention, which is accompanied by foaming of the thermoplastic
synthetic material. This means that the crosslinking by means of the agent can be
brought about by the effect of the very high temperature which occurs during the irradiation
or by the effect of UV light which can be present in the high-energy rays used.
[0021] A preferred embodiment of the invention relates to the shaped article with the marking
on a thermoplastic substrate containing an agent which by the effect of high-energy
irradiation brings about the crosslinking. An advantage of this embodiment is that
only a minor quantity of the agent need be present in the thermoplastic synthetic
material, so that the mechanical properties of the thermoplastic synthetic material
are preserved better. The agent is preferably present in the thermoplastic synthetic
material in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the
thermoplastic synthetic material. The agent preferably is a radical generator. Suitable
radical generators are for instance compounds which form carbon radicals, such as
2,3-dimethyl-2,3-diphenylbutane.
[0022] Another preferred embodiment of the invention relates to the shaped article with
the marking on a thermoplastic substrate containing an agent which by the effect of
high-energy irradiation forms a network within itself. Preferably, such a network
extends in the form of a co-continuous phase into the foamed thermoplastic synthetic
material. The agent is preferably present in the thermoplastic synthetic material
in an amount of 0.01 to 20 parts by weight per 100 parts by weight of the thermoplastic
synthetic material. The agent is preferably composed of between 1 and 19 parts by
weight of polypropylene glycol per 100 parts by weight of the thermoplastic synthetic
material and between 1 and 19 parts by weight of caprolactone polymer per 100 parts
by weight of the thermoplastic synthetic material, the sum of the parts by weight
of polypropylene glycol and caprolactone polymer being 2-20. In this way it is ensured
that the laser marking according to the invention possesses good abrasion resistance,
while preserving the mechanical properties of the thermoplastic synthetic material.
If the agent is melamine, the particles preferably have a diameter of < 10 µ.
[0023] The shaped article according to the invention, without the marking applied onto it,
can be manufactured in accordance with the known processes and irradiated with high-energy
radiation in a pattern corresponding to the shape of the marking.
[0024] Thus it is possible for instance to mix a granulate or a powder of a thermoplastic
polymer with the crosslinking agent in a tumbling barrel or a batch mixer provided
with stirring gear and subsequently melt the mixture in a kneader, such as a single-screw
extruder or a batch kneader. After the agent has been dispersed in the melt, the mixture
thus obtained can be granulated and cooled. Using one of the known processes, the
granulate can be melted down again and used for manufacture of the shaped articles
according to the invention. For instance, by means of an extruder or an injection
shaped article machine the granulate can be transformed into a shaped article fully
consisting of thermoplastic synthetic material. Next, using one of the known processes,
a marking can be made on the surface of the shaped article by means of a laser beam.
[0025] The shaped article according to the invention comes in many variants. For instance,
the shaped article may be made entirely of the thermoplastic synthetic material. It
is also possible to apply a coating of the thermoplastic synthetic material onto a
shaped article made of metal or a ceramic material.
[0026] The invention will now be elucidated by means of the following non-restrictive examples.
EXAMPLES
Comparative experiment A
[0027] A mixture of 99.3 parts by weight of acrylonitrile-butadiene-styrene copolymer (Ronfalin®)
SFA-34, from DSM, of the Netherlands), 0.6 part by weight of carbon black (Black Pearls®
880, from CABOT, of the Netherlands) and 0.1 part by weight of titanium dioxide (Tiofine®
R41, from TIOFINE, of the Netherlands) was extruded at a temperature of 260°C. The
granulate obtained in this way was injection moulded to black sheets at a temperature
of 240°C with an ARBURG Allrounder® (320-90-750) injection shaped article machine.
[0028] A part of the surface of the sheets was then irradiated with a leaser beam from an
SHG Nd:YAG Q-switch laser, type Haas Laser® 6411 Engravity System (from Haas Laser,
Germany). The pulse time was 110 nanoseconds, the wavelength was 532 nanometres, at
a high radiation energy density (about 20 Joule/cm
2). The marking obtained in this way had a white/grey colour.
[0029] The abrasion resistance of this marking was tested by means of the device used in
the Taber abraser test (ASTM D4060: 'Standard Test Method for Abrasion Resistance
of Organic Coatings by the Taber Abraser'). The abrasion resistance was qualified
as 'good', 'reasonable' or 'poor'.
[0030] The impact resistance of the marked material was measured in kJ/m
2 according to DIN 51320 (Izod impact test, notched).
[0031] The abrasion resistance and impact resistance values found are given in table 1.
Example I
[0032] Comparative experiment A was repeated, but now using 94.3 parts by weight of acrylonitrile-butadiene-styrene
copolymer (Ronfalin® SFA-34, from DSM, of the Netherlands), 0.6 part by weight of
carbon black (Black Pearls® 880, from CABOT, of the Netherlands) and 0.1 part by weight
of titanium dioxide (Tiofine® R41, from TIOFINE, of the Netherlands), 2.5 parts by
weight of PPG 2000 (polypropylene glycol 2000, from Hofag Chemical Corporation, of
the USA) and 2.5 parts by weight of CAPA® 656 (from Interox Chemicals Ltd., of the
UK).
[0033] The abrasion resistance and impact resistance values found are given in table 1.
Example II
[0034] Example I was repeated, but now PPG 2000 and CAPA (TM) 656 were replaced by 5 parts
by weight of Perkadox (TM) 30 (from AKZO Chemicals Division, of the Netherlands).
[0035] The results are given in table 1.
Example III
[0036] Example II was repeated, but now Perkadox (TM) 30 was replaced by 5 parts by weight
of Spinflam (TM) MF83 (from Himont, of Italy).
[0037] The results are given in table 1.
Example IV
[0038] Example II was repeated, but now Perkadox (TM) 30 was replaced by 5 parts by weight
of Ceepree (TM) C-200 (from ICI Chemicals & Polymers Ltd., of the UK).
[0039] The results are given in table 1.
Example V
[0040] Example II was repeated, but now Perkadox (TM) 30 was replaced by 5 parts by weight
of Ceepree (TM) Microfine (from ICI Chemicals & Polymers Ltd., of the UK).
[0041] The results are given in table 1.
Example VI
[0042] Example II was repeated, but now Perkadox (TM) 30 was replaced by 2 parts by weight
of pentaerythritol (Qual. R., pulverized, from Degussa, of Germany) and 3 parts by
weight of Exolyt (TM) 422 (ammonium polyphosphate, from Hoechst Holland n.v., of the
Netherlands).
[0043] The results are given in table 1.
Example VII
[0044] Example II was repeated, but now Perkadox (TM) 30 was replaced by 2 parts by weight
of Dures 22091 (novolac, from Occidental Chemical, of Belgium) and 3 parts by weight
of Exolyt (TM) 422 (ammonium polyphosphate, from Hoechst Holland n.v., of the Netherlands).
[0045] The results are given in table 1.
Example VIII
[0046] Example II was repeated, but now Perkadox (TM) 30 was replaced by 1 part by weight
of Madurit (TM) MW909 (cured melamine-formaldehyde resin, from Hoechst Holland n.v.,
of the Netherlands) and 94.3 parts by weight of ABS were replaced by 98.3 parts by
weight of ABS.
[0047] The results are given in table 1.
Example X
[0048] Example II was repeated, but now Perkadox (TM) 30 was replaced by 3 parts by weight
of Melamine Superfine (TM), D90 < 5 mµ (from DSM, of the Netherlands) and 94.3 parts
by weight of ABS were replaced by 96.3 parts by weight of ABS.
[0049] The results are given in table 1.
Example X
[0050] Example II was repeated, but now Perkadox (TM) 30 was replaced by 2 parts by weight
of trishydroxyethyl isocyanurate (from BASF AG, of Germany) and 3 parts by weight
of Exolyt (TM) 422 (ammonium polyphosphate, from Hoechst Holland n.v., of the Netherlands).
[0051] The results are given in table 1.
Example XI
[0052] Example II was repeated, but now Perkadox (TM) 30 was replaced by 3 parts by weight
of Melamine Superfine (TM), D90 < 100 mµ (from DSM, of the Netherlands) and 94.3 parts
by weight of ABS were replaced by 96.3 parts by weight of ABS.
[0053] The results are given in table 1.
TABLE 1
Results of abrasion resistance and impact resistance tests of comparative experiment
A and examples I-XII |
|
|
Abrasion resistance |
Impact resistance Izod (kJ/m2) |
Comparative experiment |
A |
poor |
21 |
Example |
I |
good |
21 |
II |
good |
20 |
III |
good |
2 |
IV |
good |
8 |
V |
good |
10 |
VI |
good |
10 |
VII |
good |
8 |
VIII |
reasonable |
10 |
IX |
good |
15 |
X |
good |
9 |
XI |
good |
5 |
1. Moulding with a marking on a thermoplastic substrate, which marking is made by foaming
the thermoplastic by means of high-energy irradiation, characterized in that the thermoplastic
synthetic material contains an agent which, due to the action of the high-energy irradiation,
has caused crosslinking at the spot where the foaming of the thermoplastic synthetic
material has occurred, whereby are excluded thermoplastic substrates comprising one
or more compounds of the group of tetrazole compounds, sulfonylhydrazide compounds,
nitroso compounds and azo compounds having a decomposition temperature of 210°C or
more.
2. Moulding according to claim 1, characterized in that ABS (acrylonitrile-butadiene-styrene
copolymer) is used as thermoplastic synthetic material.
3. Moulding according to claim 1, characterized in that the agent has brought about the
crosslinking by crosslinking of the thermoplastic synthetic material.
4. Moulding according to claim 3, characterized in that the agent is present in the thermoplastic
synthetic material in a quantity of 0.01 to 10 parts by weight per 100 parts by weight
of the thermoplastic synthetic material.
5. Moulding according to claims 3 and 4, characterized in that the agent is a radical
generator.
6. Moulding according to claim 5, characterized in that the agent is 2,3-dimethyl-2,3-diphenylbutane.
7. Moulding according to claim 1, characterized in that the agent has brought about the
crosslinking by forming a network within itself.
8. Moulding according to claim 7, characterized in that the agent is present in the thermoplastic
synthetic material in a quantity of 0.1 to 20 parts by weight per 100 parts by weight
of the thermoplastic synthetic material.
9. Moulding according to claim 7, characterized in that the agent contains between 1
and 19 parts by weight of polypropylene glycol per 100 parts by weight of the thermoplastic
synthetic material and between 1 and 19 parts by weight of caprolactone polymer per
100 parts by weight of the thermoplastic synthetic material, the sum of the parts
by weight of polypropylene glycol and caprolactone polymer being 2-20.
10. Moulding according to claims 7 and 8, characterized in that the agent is melamine
and the melamine particles have a diameter of < 10 µ.
1. Formartikel mit einer Markierung auf einem thermoplastischen Substrat, wobei die Markierung
durch Schäumen des Thermoplasten mithilfe von Hochenergiebestrahlung erfolgt, dadurch
gekennzeichnet, daß das thermoplastische synthetische Material ein Mittel enthält,
das durch die Wirkung der Hochenergiebestrahlung eine Vernetzung an der Stelle herbeigeführt
hat, wo das Schäumen des thermoplastischen synthetischen Materials aufgetreten ist,
wobei thermoplastische Substrate, die ein oder mehrere Verbindungen der Gruppe aus
Tetrazolverbindungen, Sulfonylhydrazidverbindungen, Nitrosoverbindungen und Azoverbindungen,
die eine Zersetzungstemperatur von 210°C oder mehr haben, ausgeschlossen sind.
2. Formartikel gemäß Anspruch 1, dadurch gekennzeichnet, daß ABS (Acrylnitril-Butadien-Styrol-Copolymer)
als thermoplastisches synthetisches Material verwendet wird.
3. Formartikel gemäß Anspruch 1, dadurch gekennzeichnet, daß das Mittel durch Vernetzung
des thermoplastischen synthetischen Materials eine Vernetzung herbeigeführt hat.
4. Formartikel gemäß Anspruch 3, dadurch gekennzeichnet, daß das Mittel im thermoplastischen
synthetischen Material in einer Menge von 0,01 bis 10 Gewichtsteilen pro 100 Gewichtsteile
des thermoplastischen synthetischen Materials vorhanden ist.
5. Formartikel gemäß den Ansprüchen 3 und 4, dadurch gekennzeichnet, daß das Mittel ein
Radikalbildner ist.
6. Formartikel gemäß Anspruch 5, dadurch gekennzeichnet, daß das Mittel 2,3-Dimethyl-2,3-diphenylbutan
ist.
7. Formartikel gemäß Anspruch 1, dadurch gekennzeichnet, daß das Mittel die Vernetzung
durch die Bildung eines Netzes in sich selbst herbeigeführt hat.
8. Formartikel gemäß Anspruch 7, dadurch gekennzeichnet, daß das Mittel im thermoplastischen
synthetischen Material in einer Menge von 0,1 bis 20 Gewichtsteilen pro 100 Gewichtsteile
des thermoplastischen synthetischen Materials vorhanden ist.
9. Formartikel gemäß Anspruch 7, dadurch gekennzeichnet, daß das Mittel zwischen 1 und
19 Gewichtsteile Polypropylenglykol pro 100 Gewichtsteile des thermoplastischen synthetischen
Materials und zwischen 1 und 19 Gewichtsteile Caprolactonpolymer pro 100 Gewichtsteile
des thermoplastischen synthetischen Materials enthält, wobei die Summe der Gewichtsteile
von Polypropylenglykol und Caprolactonpolymer 2-20 beträgt.
10. Formartikel gemäß den Ansprüchen 7 und 8, dadurch gekennzeichnet, daß das Mittel Melamin
ist und die Melaminteilchen einen Durchmesser von <10 µm haben.
1. Moulage avec un marquage sur un substrat thermoplastique, le marquage étant obtenu
par moussage du thermoplastique au moyen d'une irradiation à haute énergie, caractérisé
en ce que le matériau thermoplastique synthétique contient un agent qui, en raison
de l'action de l'irradiation à haute énergie, a provoqué la réticulation à l'endroit
où le moussage du matériau thermoplastique synthétique a lieu, de sorte que sont exclus
les substrats thermoplastiques comprenant un ou plusieurs composés du groupe des composés
tétrazole, composés sulfonylhydrazide, composés nitroso et composés azo ayant une
température de décomposition de 210°C ou plus.
2. Moulage selon la revendication 1, caractérisé en ce que l'ABS (copolymère acrylonitrile/butadiène/styrène)
est utilisé comme matériau thermoplastique synthétique.
3. Moulage selon la revendication 1, caractérisé en ce que l'agent a provoqué la réticulation
par réticulation du matériau thermoplastique synthétique.
4. Moulage selon la revendication 3, caractérisé en ce que l'agent est présent dans le
matériau thermoplastique synthétique en une quantité de 0,01 à 10 parties en poids
par 100 parties en poids du matériau thermoplastique synthétique.
5. Moulage selon les revendications 3 et 4, caractérisé en ce que l'agent est un générateur
radicalaire.
6. Moulage selon la revendication 5, caractérisé en ce que l'agent est le 2,3-diméthyl-2,3-diphénylbutane.
7. Moulage selon la revendication 1, caractérisé en ce l'agent a provoqué la réticulation
en formant en lui-même un réseau.
8. Moulage selon la revendication 7, caractérisé en ce que l'agent est présent dans le
matériau thermoplastique synthétique en une quantité de 0,1 à 20 parties en poids
par 100 parties en poids du matériau thermoplastique synthétique.
9. Moulage selon la revendication 7, caractérisé en ce que l'agent contient entre 1 et
19 parties en poids de polypropylène-glycol par 100 parties en poids de matériau thermoplastique
synthétique et entre 1 et 19 parties en poids de polymère caprolactone par 100 parties
en poids du matériau thermoplastique synthétique, la somme des parties en poids de
polypropylène-glycol et de polymère caprolactone étant 2 à 20.
10. Moulage selon les revendications 7 et 8, caractérisé en ce que l'agent est la mélamine
et que les particules de mélamine ont un diamètre de <10 µ.