Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Readily visible image formation
Patent
1996-12-04
2000-02-01
Morris, Terrel
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Readily visible image formation
430297, 430322, 430945, 524521, 524523, 428522, B41M 526
Patent
active
060201061
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the use of polymer mixtures containing, as essential components,
______________________________________ A) from 40 to 99% by weight
of a polymer of an alkyl ester
of (meth)acrylic acid,
B) from 1 to 50% by weight
of a copolymer of styrene and
acrylonitrile having an
acrylonitrile content of from 8
to 30% by weight,
C) from 0 to 50% by weight
of a rubber, and
D) from 0 to 20% by weight
of additives and processing
auxiliaries,
______________________________________
high-energy radiation.
2. Description of the Related Art
The production of laser-inscribed moldings from polymethyl methacrylate (PMMA) has hitherto been impossible in satisfactory quality without the addition of additives to increase the absorption coefficients of the laser radiation employed.
In particular for inscription with the Nd:YAG laser which is the most frequently used, pigments are added, but these adversely affect the transparency of the PMMA, which is frequently a prerequisite for the use of PMMA in the application. In the area of measuring beakers, scales and measuring rules, this is unacceptable; on the other hand, a durable inscription which is highly legible both in transmitted light and in incident light is desirable in these very applications.
The addition of carbon black to improve the laser inscribability of molding compositions comprising thermoplastics is described in DE-C 30 44 722, but this does not give satisfactory results in the case of PMMA.
Mixtures of PMMA and styrene-acrylonitrile copolymers (PSAN) are known and described, for example, in Polymer 28 (1987), 1177; at an acrylonitrile content of the PSAN in the range from 18 to 23% by weight, the transparency of moldings produced from the molding compositions is retained extremely well.
SUMMARY OF THE INVENTION
It is an object of the present invention to modify PMMA in such a way that very high-contrast inscription with sharp edges is possible using Nd:YAG lasers without there necessarily being any adverse effect on the transparency of the inscribed moldings.
We have found that this object is achieved by the novel use of the molding compositions described at the outset.
Preferred embodiments of the novel use are given in the subclaims.
DESCRIPTION OF THE REFERRED EMBODIMENT
The polymers A) of alkyl esters of (meth)acrylic acid are preferably those comprising
______________________________________ from 50 to 100% by weight of
a C.sub.1 --C.sub.18 -alkyl ester of
(meth)acrylic acid, and
from 0 to 50% by weight of
further
free-radical-polymerizable
monomers.
______________________________________
In general, the acrylic acid esters employed are the C.sub.1 -C.sub.18 -alkyl esters, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, lauryl or stearyl acrylate, preferably methyl acrylate, n-butyl acrylate or 2-ethylhexyl acrylate, or mixtures of these monomers.
In general, the methacrylic acid esters employed are the C.sub.1 -C.sub.18 -alkyl esters, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, lauryl or stearyl meth acrylate, preferably methyl methacrylate, or mixtures of these monomers.
The use of hydroxyl-, epoxy- and amino-functional methacrylates and acrylates is also possible.
The acrylates and methacrylates and mixtures thereof are generally employed in amounts in the range from 50 to 100% by weight, preferably from 80 to 100% by weight, based on the total amount of monomers of component A).
As further comonomers, up to 50% by weight, preferably up to 20% by weight, of the following monomers, which are listed by way of example, can be employed: or p-(tert-butyl) styrene;
The monomers are expediently selected so that the polymer formed has a glass transition temperature of at least 30.degree. C. in order to avoid the polym
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Damm Paul Otto
Deckers Andreas
Mc Kee Graham Edmund
Oslowski Hans-Josef
Wagner Daniel
BASF - Aktiengesellschaft
Juska Cheryl
Morris Terrel
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