DE2159303B2 - Complete curing of polymerizable films - Google Patents

Description

The invention relates to a method for voilstän- * 5 From the UT-AS 1 163 014 a method for the hardening of polymerizable films is known, which have been hardened by wetting of UV-crosslinkable thermal irradiation with ionizing radiation. In this process, the properties and, as a result of oxygen inhibition, have an incomplete thermoplastic that is cured to just below the softening-temperature-resistant surface layer. It is known that numerous polymerizable 30 treatment is exposed (claim 1, as well as column 1, lines 20 systems with ionizing radiation are cured to 23). Since it is not about the crosslinking can polymeriden. The use of ionizing radiation, as in the process of the invention, and in particular of electron beams, has nothing to do with the crosslinking of thermoplastics not at all at first. Apart from this, however, when using catalysts, irradiation with UV light in particular does not take place in air, then a number of pronounced advantages when film but in a vacuum or in an inert gas atmosphere coating on wood and wood products, fabrics, spheres instead, which is decisive for crosslinking rubber, glass, metal and similar substances or the temperature (column 2, lines 40 to 46).
Substrates are to be hardened. 40 FR-PS 1 217 565 relates to surface improvement. a surface change is avoided up to the long-lasting induction period that makes it flowable, which is intended to cause the desired surface improvement to be unaffected by the use of film-forming mixtures (left column, paragraph 3). Thus, a limited pot life enables the temperature rise to keep the use of IR radiation low in the case of the FR-PS during the polymerization and, in 1 217 565 for surface heating of the plastics, in many cases a superior bond between the results. Coating and substrate can be achieved. Numerous radiation after the application of ionizing films can be cured using high-energy radiation leads, is shown in Example 9 of the present shear electrons in less than 1 second. if the uncured film is allowed to come into contact with air with ionic radiation before extensive curing, the so-called radiation is often not possible due to the volatility of the aforementioned oxygen inhibition of curing with monomers.
ionizing radiation in the surface layer, 55 The process of US Pat. No. 3,531,317 relates to the finish and the surfaces of the films hardened in this way are hardening of unsaturated polyester resins which are sticky or otherwise not so well permeated with wax or paraffin contain. It hardens like the bulk of the film, although the hardening takes place in such a way that incompletely hardened material is only incorporated into the polyester resin in a very thin layer of photosensitizer, then the poly layer, i.e. in layers with a thickness of large ester resins, is hardened with UV radiation, until the wax is properly 2.5 x 10- * to 2.5 x 10 ~ cm, or paraffin smf the surface leads to a protective film, this insufficient hardening of the surface has often formed, and then treated with an electron beam to serious loss of gloss and problems ( Claim i). U.S. Patent No. 3,531,317 for scratch resistance. If the person to be cured is in one of the classic ways of filming in the form of a coating or a coating 65 preventing oxygen inhibition, namely on substrates such as wooden panels, then when using paraffins or waxes, the storage of the coated substrates in the form of a stack, blocking occurs before electron beam curing. Due to acidic use of UV radiation only and

3 4

Its purpose is the floating of the resins, silicone-modified organic resins and

Wax or paraffin to the surface effect epoxy resins.

(Column I, line 60, to column 2, line 8). Vinyl monomers in which the aforementioned

The problem of oxygen inhibition would be solved so resins are, among other things, two

hitherto always solved in such a way that either, for example, monovinyl aromatic hydrocarbons are used

using paraffins or waxes from the benzoJ series, such as styrene, vinyltoluoJ, ethyl vinyl

* Form a protective film on the surface, or the beiraol, isopropylstyrene, tert.-butylstyrene, sec-butyl-

j curing in a vacuum or under a protective gas atmosphere styrene and mixtures of the compounds mentioned,

performs. Just US-PS 3,531,317 shows all α-methylstyrene, divinyl compounds of the benzene

It is clear that despite the use of UV io series, such as divinylbenzene, acrylic acid, vinyl acetate, di-

Radiation and electron radiation for excluded acetone acrylamide, methyl methacrylate, ethylacrylate

cold, when working without protective gas or without alate, n-butyl acrylate, ethyl acrylate, cyclobexyl acrylate,

application of vacuum to the protective wax /? - hydroxyethyl acrylate and the like.

or to be able to do without paraffin film. This makes the term "ionizing radiation" intended in the

clearly that the solutions for the indicated ts present description and the claims are

I was looking for problems in a completely different direction. The benefit of corpuscle rays, such as highly accelerated elec-

driving dfr invention is therefore not close at hand, trons, protons, neutrons, alpha particles,

and the technical progress achieved must be in terms of electron and / 5-rays, as well as electromagnetic

to the greatest extent surprisingly. These waves, such as X-rays and y-rays,

em so more than the inventive curing of the 20 grasp. The one used to cure a particular film

Surface layer without the application of acti- required dose of ionizing radiation depends

vators and / or catalysts takes place, which in the case of the radiation power or intensity, the temperature

Curing of polymerizable films with UV radiation temperature and the thickness and composition of the too

are always necessary in practice. "hardening film. Useful results will be

According to the method of the invention, the full 25 can, for example, using high-energy electrolytes Hardening of the coating film under control with 20 KeV to 10 MeV and application of radiation power a powerful UV light source against from 1 megarad per minute to 10 megarad per comfortably achieved by a second lasting less than 1 minute. Electron irradiation is preferred can be achieved. This allows for radiation with sufficient voltage or sufficient hardened surfaces quickly due to the energy content and thus high intensity or Effect of UV light and indeed even then eliminates radiation density applied so that it has its full strength if the film to be hardened does not penetrate free radicals of the film to be hardened and the film withstands calcium-forming catalysts or photoinitiators in a few seconds or less, harden.

A particularly advantageous system 1 in rapid and 35 To carry out the inventive full curing of polymerizable films th surface curing, any UV light results from the combination of an electron source, including short-wave fluorescent lamps, beam with ultraviolet light. By using long-wave fluorescent lamps, mercury vapor of the first-mentioned radiation, lamps and even sunlight can be used in a proportionate manner. Short and opaque films are cured so quickly that light sources emitting wavy light do not eliminate the formation of bubbles due to volatile constituents and, however, incompletely cured surface layers do not absorb too much of the uncured film much faster than long-wave light sources. Where occurs through porous substrates. Which is usually the speed of the surface hardening of remaining, thin, incompletely hardened upper meaning, are high-performance quartz-mercury surface layer is particularly preferred by the UV-light easily through arc lamps. Preferential penetration and hardened quickly. becomes wise with radiation intensities or densities

The method of the invention IaB _1, gear- to any of about 0.78 to 2.33 watts per cm ² and minute

use polymerizable films which, with the exception of processed, can also be used with lower radiation intensities.

a thin one, due to the oxygen inhibition of the properties, can be used if longer curing

polymer times induced by ionizing radiation can be tolerated. The one to harden

sation incompletely cured surface layer, the surface required duration of irradiation

cured by exposure to ionizing radiation with UV light depends on the intensity or radiation

will. Typically, such mixtures include the density of the UV light source, the degree to which the

Compounds that are radically polymerizable. A surface in question has not fully cured

The preferred class of such compounds is polymeric and the composition of the film. With a

resins with terminal acrylate or about 7.5 cm spaced 1200 W quartz

Methacrylate groups that can be found in the German open mercury vapor lamp surfaces

Legungsschrift 1 916 500 are known to the hereby homely in about 2 to 20 seconds in the desired

Is referred to. These resins cannot cure to the extent that they are.

düflflt otter dissolved in up to 50% of a vinyl mono * 6o As already mentioned above *, you can liötef

Biefeft are used using ÜV-LichteiAe fisete OBeiffMtea ⁵¹

Others used for the method of the invention curing even in the absence of a free radical

Bare, polymerizable masses are those in the USA-forming Kataiysatorafioder-FotoiflitiatiirSi-bhflCWe ^

Patent Specification 3,437,514, to which reference is also made, is in some cases but is open

Is called, described Λ, / ϊ-otefinically unsat- 65 of a free radical-forming KatÄljftäWi? » how

modified organic resins. Resins of this type are included among the group of bezoyl peroxide and azobisisobutyrorite fil / ötfer

aflderent unsaturated polyester resins, acrylic resins, mo- FotoinitiatOM, wig · Bertzoifi and ä ^ Btttafldtööi ei «*

difiziefte acrylic resins, urethane-modified organic even faster elimination S ^H ^ ' ^aü ^ ^e ^ ^l

Achieve finishes. In addition, it is also in the visible Energy lying in the wavelength range of unfiltered UV light sources are more effective when such photoinitiators are present.

The method of the invention is particularly suitable for displaying films in the form of clear surface on hard plywood, chipboard, top layer soft plywood, Fiber boards and cardboard and for hardening pigmented coatings, such as titanium dioxide, calcium carbonate, zinc oxide or contain talc on wood blanks, cardboard, plywood, steel, tin and aluminum. That The method of the invention is also well suited for curing and hardening of unsupported films of surfaces of porous materials soaked with liquids that can be hardened by ionizing radiation. For example, one can impregnate paper and wood using the method of the invention Paper-plastic and wood-plastic combinations Harden.

The examples illustrate the invention and are in no way to be understood as a restriction. declarations in parts, unless otherwise stated, itets are based on weight.

example 1

It becomes a coating agent by dissolving 20 parts of butyl acrylate in 80 parts of one by condensation of 2 moles of 2-hydroxyethyl acrylate, 2 moles of maleic anhydride and 1 mole of bisphenol A diglycidyl ether obtained vinyl ester resin. Then a 0.076 mm strong layer of this coating agent applied. The coated blank is then used twice at a speed of 15.24 m per minute under an electron beam of 300 KeV and 20 mA carried out. The electron beam has a trajectory or a scanning width of 45.72 cm. The total radiation dose for this treatment is 8.5 megarads. The applied layer hardens good, but the surface of the cured coating is slightly sticky and can easily be scratched. The coating is then removed with a 100 W quartz-mercury lamp at a distance of 3.81 cm Irradiated for 30 seconds without an interposed filter. After cooling, the surface shows no trace of stickiness on and when scratching with a coin no white scratch marks remain on it.

Example 2

As in Example 1, a 0.127 mm thick layer of a coating agent consisting of 25 parts of n-butyl acrylate and 75 parts of the vinyl ester resin used in Example 1 is applied to plywood, whereupon the coated plywood sheet is irradiated with an electron beam as in Example 1. The coating obtained in this way is also hard-cured and has a sticky surface. The viewed board is then passed at a speed of 6.1 m per minute at a distance of about 7.5 cm under a 30.48 cm long, equipped with a 10.16 cm wide reflector 120Q * W "Hanovia Quafzqueeksilberbögeftläffipe, after five successive passes the surface is not excessively sticky, but when scratched it absorbs white ink. After five more passes, which result in a total exposure time of 10 seconds under the reflector, the scratching no longer leaves any white scratch marks on the surface and the surface shows the same hardness properties as one of the same composition, but in contact with a cover film made of polyethylene terephthalate, which is applied To prevent the hardening inhibition by oxygen, hardened coating.

B e i s ρ i e 1 3

One part of glycidyl acrylate and 0.5 part of benzoin are added to the coating composition of Example 2. After curing with an electron beam as in Example 1, the coating is hard.

hardens, but has a sticky surface. After performing 5 times under that described in Example 2 1200 watt single speed lamp of 6.1 m per minute, corresponding to a total exposure time of 5 seconds, the upper

no more surface and no white marks remain on it when it is scratched.

Example 4

Analogously to Example 1, plywood is made with one as follows composite coating agent is coated and the layer is irradiated with an electron beam:

a) 17.5 parts by condensing 2 moles of 2-hydroxyethyl acrylate and 2 moles of maleic anhydride and 1 mole of bisphenol A diglycidyl ether prepared Vinyl ester resin;

b) 17.5 parts by condensing 2 moles of 2-hydroxypropyl acrylate, 2 moles of maleic anhydride and 1 mole of butanediol diglycidyl ether made vinyl ester resin;

c) 15 parts of n-butyl acrylate;

d) 30 parts of titanium dioxide and

e) 20 parts of talc.

The resulting hard, resilient, white coating has a sticky surface that then closes a tack-free surface is cured by being in the manner described in Example 2 6 times at a speed of 18.3 m per minute, corresponding to a total exposure time of 2 seconds, Performs under the 1200 W UV lamp.

Example 5

A common unsaturated polyester resin, Polylite 31-583 (a semi-rigid, unsaturated, in vinyl toluene dissolved polyester, product of Reichhold Chemical Co.), is in a 0.127 mm thick layer applied to a metal foil. After three passes under the electron beam according to Example 1 At a speed of 18.3 m per minute, the film breaks suddenly when it is bent, but is on the surface is still sticky. After 10 passes under the 1200 watt lamp described in Example 2 at a speed of 6.1 m per minute, corresponding to a total exposure time of 10 seconds, the surface of the film is hard and no longer sticky.

Example 6

Is prepared by reacting 100 parts of polypropylene 'glycol having a molecular weight of 400 with 78.2 parts of tolylene diisocyanate, 91 parts of 2-hydroxyethyl acrylate and 0.2 parts of tin octoate at 6O ⁰ C

a resin solution prepared. This resin solution is applied in a 0.102 mm thick layer on cardboard, whereupon the coated cardboard is irradiated, by performing it three times at a speed of 25.6 m per minute under the electron beam described in Example 1, which corresponds to a total radiation dose of 6 megarads. The one with it The clear coating obtained is flexible and strong, but has a tacky surface. The cardboard will then carried out five times under the UV lamp described in Example 2, a non-tacky coating being obtained.

. ,. Example 7

Example 6 is repeated except that, in deviation from this, a 0.178 mm thick layer is applied to the cardboard. The same results as in Example 6 are obtained.

. 10

Example

The pigmented coating agent mixture of Example 4 is mixed with 0.5% benzoin and in a 0.279 mm thick layer on top layer plywood carried. The coating is analogous to Example 1 in three Irradiated dutch walks at a speed of 18.3 m per minute, whereby a hard, but receives a sticky coating. After five passes at a speed of 6.1 m per Minute under the UV lamp described in Example 2, the surface is no longer sticky and becomes no longer scratched by a coin.

B e ι s ρ »e l 9

Example 8 is repeated, but deviating therefrom however, the hard but tacky coating obtained after irradiation with an electron beam in a distance of 7.62 cm under a 30.48 cm long 1800 watt "Chromolux" infrared lamp equipped with a 10.16 cm wide reflector. After ten passes at a speed of 18.3 meters per minute, no reduction in surface tack was observed. Loading

_{In addition, if} the coating is continuously hit with the infrared lamp for several seconds, the surface looks dark without its stickiness being removed.

Claims (3)

X 2 fabric inhibiening uniquely hardened surface claims: One can generally avoid layers by covering the non-hardened film with an inert one 1. Process for complete curing of cover sheet covers or so long in an oxygen-polymerizable film, which maintains a free atmosphere by irradiation 5 until it is cured. These techniques have been cured with ionizing radiation, however, in practice, often cannot have a surface layer which is incompletely usable or which has been cured for large-scale production processes due to oxygen inhibition, which makes them too expensive on a scale. characterized in that the invention is therefore based on the object. Surface layer so long with UV light i ° a process for complete curing poly- radiates until it is hardened to the desired extent, to create merisable films, which after loading 2. The method according to claim 1, characterized in that * radiation with ionizing radiation is insufficiently drawn that one has as ionizing radiation elec- tronic hardened surface layers,
electron radiation applies. The invention thus relates to a method 3. The method according to claim 1 or 2, characterized is for complete curing of polymerizable, characterized in that the UV light source is a film which is used by irradiation with ionizing beam quartz mercury vapor arc lamp. have been hardened and, as a result of oxygen tinting an incompletely hardened surface own layer, which is characterized in that You show this surface layer with UV light for so long irradiated until it is hardened to the desired extent. Compared to the method of the invention, the known methods differ in various ways Respect.