NO140110B - MATERIALS WITH IMPERPROOUT LACQUER COATING ON THE BASIS OF UNLATURED POLYESTER, WITHOUT CONTENT OF COVERING PIGMENTS - Google Patents

Description

The present invention relates to materials with opaque

visible lacquer coating that is free of covering pigments and is based on unsaturated polyesters and copolymerized monomers.

In the following description, "materials" means all materials made of wood, wood materials, pressed materials, cardboard,

paper, glass or metal suitable for varnishing. Wood materials are understood to mean processed wood products such as particle boards, hard fiber boards, lamella boards with and without veneer. Pressed materials are paper, woven materials, fiber fleece or glass mats that are permeated with synthetic resins and harden into layered materials using pressure and heat. Also

plastics can serve as "materials" for a coating. Although the materials do not need to have a planar shape, they are preferably available as disks or plates. By "materials" is also understood

such as have been pre-treated. Below that, wood or wood materials can be stained, metals have a washing primer, a phosphate coating or be chrome-plated. Furthermore, the materials can be filled, primed or coated with a layer of varnish.

Chipboard or hard fiber boards are used to a large extent in the furniture industry. For colored or white-painted furniture, such panels are generally no longer veneered, but puttyed and coated with a base foil. It has long been an endeavor in the furniture industry to equip panels for door, side or wall elements of furniture, and also table tops, with a white or colored cover that gives the finished assembled furniture an appealing appearance. For this, coating materials based on unsaturated polyesters and copolymerizable monomers are often used, but only transparent coatings have so far been able to be cured with the help of UV light. If opaque coverings (white or coloured) are to be produced, the coating materials must have opaque pigments added such as e.g. titanium dioxide.

From British patent 1 201 087 it is known to produce shaped objects using a curable, liquid, polymerizable mixture of an unsaturated polyester resin, a thermoplastic and an ethylenically unsaturated monomer copolymerizable with the unsaturated polyester. The curing of this mixture takes place under application of pressure and heat, and a white and opaque object is formed. The reason for the opacity is the incompatibility of the thermoplastic with the unsaturated polyester resin, both in the hardened state and in the liquid resin mixture, which after a long delay splits into two liquid layers. For the object to become white, the thermoplastic is absolutely necessary.

In an article in the journal "Kunststoffe" 1968, pages 931 - 932, the curing process of unsaturated polyester resins and styrene is examined. During the polymerization, polystyrene end pieces with styrene sequences of different lengths are formed. At a low degree of cross-linking, a phase separation occurs which makes the individual phases visible as a result of different light refraction. This effect manifests itself as a slight haze or opalescence.

It has now, surprisingly enough, been found that materials with completely satisfactory coatings can be obtained when the proportion of unsaturated polyester is substantially reduced and the proportion of copolymerizable monomers substantially increased. The fact that in this way coatings are obtained that are white and opaque, have a high covering capacity and, moreover, completely satisfactory technological properties, was surprising and not to be expected. The coverage corresponds to the coverage that you get when you add considerable amounts of titanium dioxide. The titanium dioxide is completely eliminated here.

The curing of coatings of polyester materials can take place in different ways. It can be carried out without external heat input at normal room temperatures when the materials contain peroxide hardeners and suitable accelerators.

The peroxide-initiated curing can be further accelerated by adding heat from the outside, or by irradiation with infrared rays, or by using high-frequency energy.

Another type of curing of coatings of polyester materials can be carried out by irradiation with ultraviolet light. In this case, the peroxide hardener and accelerator are omitted. In their place comes a photochemical sensitizer. Under the influence of UV light, this causes a release of radicals, whereby the polymerization is initiated. The UV rays used here are usually produced by high-pressure mercury vapor or low-pressure mercury vapor lamps or superactinic fluorescent tubes. The known methods for UV curing are summarized in the articles "Die Lichthartung von Polyester-Lacken" (Eugen Richter, Moderne Holzverarbeitung,

issue 10, 1968, pages 604 - 606) and "Lackhartung durch ultra-violettes Licht" (Dr. Wolfgang Deninger und Dr. Manfred Patheiger, Industrie-Lackier-Betrieb, 37. Jg., issue 3, March 1969, page 85 - 91).

Instead of ultraviolet light, you can also use sunlight or another, strongly ionizing radiation.

When curing with UV light, one has so far only used such polyester varnishes whose proportion of unsaturated polyester was higher than the proportion of copolymerisable monomers. However, in contrast to the curing which is initiated by peroxides and accelerators, UV light can only be used for transparent coatings. If these materials are pigmented, they cannot be cured by UV light. This naturally entails the major disadvantage that up to now it has only been possible to apply UV curing in a limited area, namely with transparent coatings.

From German off. document no. 1 621 820 it is known to produce coatings which can contain fillers which do not negatively affect the UV curing. Such fillers are e.g. calcium carbonate, mica, talc, barium sulphate, finely divided silica and silica aerogels. Within the framework of the present invention, these fillers can also be used. These additions only vary the properties of the coating with regard to e.g. hardness, scratch resistance and adhesion. However, their total amount must

be less than the content of unsaturated polyester.

The object of the present invention is thus materials with opaque lacquer coatings based on unsaturated polyesters and copolymerizable monomers, as well as common curing catalysts and possibly non-covering pigments, and this material is characterized in that the lacquer coating is produced from a coating material where the content of copolymerizable monomers, in particular styrene, was greater than the content of unsaturated polyester, as the coating material did not contain components that were suitable for eliminating the incompatibility between the two phases in the coating that are formed during curing.

The surprising effect that the hardened coatings become opaque is also obtained when, in addition to the monomers, the coating contains non-reactive solvents, such as aliphatic and/or aromatic hydrocarbons (benzene, toluene, xylene), alcohols, glycols, esters.

The discovery that the coating becomes opaque during curing is not tied to specific types of unsaturated polyesters. It has been found that all practically applicable types are applicable. When it comes to the composition and production of unsaturated polyesters, exhaustive information on this can be found in the literature sources mentioned at the outset. As is known, unsaturated polyesters are those obtained by esterification of dicarboxylic acids, such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, adipic acid, succinic acid, phthalic acid or phthalic anhydride with polyalcohols, such as ethylene glycol, diethylene glycol, hexadiol, glycerol, trimethylolpropane and pentaerythritol. -tritol.

The copolymerizable monomers specified in the above-cited literature are also usable. This concerns the usually used monomers, which can be used individually or in a mixture. Examples include styrene, vinyltoluene, methyl methacrylate, ethyl methacrylate, divinylbenzene, diallyl phthalate.

The best results in terms of appearance and structure of the white coating are achieved when irradiating with UV light. The preferred ratio between monomers and unsaturated polyester varies depending on the type of monomer and polyester, and preferably between 10 and 45% by weight of unsaturated polyester is used in the non-pigmented covering material.

The surface of the hardened coating can be varied. By means of suitable additives, such as e.g. paraffin and wax, you can get the look of an effect varnish. The surface can further be brought to a high gloss by grinding and polishing. The diversity of the different surface forms of the white coating is also achieved by a suitable choice of organic, non-reactive solvents.

As additives, you can use anti-foam agents, coagulating agents (silicone oil) and thickeners.

The coating material may further contain small amounts of other synthetic resins which are compatible with the coating material, such as e.g. nitrocellulose, alkyd resins, ketone resins, linear saturated polyesters, epoxy resins, polyurethane resins, urea resins, melamine and other triazine resins, acrylate and/or methacrylate resins, acetobutyrates and polyvinyl compounds. However, one must avoid mixing in ingredients that cancel out the incompatibility between the two phases formed during curing.

The hardened plastic layers are usually (in the absence of soluble dyes) white, and have an excellent covering ability that can be compared to such films and coverings which consist of highly pigmented materials.

In the simplest case, the coating material consists of a solution of unsaturated polyesters in the copolymerizable monomers. Depending on the type of hardener used, either peroxide and a cobalt compound or peroxide and a tertiary amine are added to this mixture, or a photosensitizer is added to the mixture. Additional activators may also occur.

If curing is to be done at normal room temperatures without heat input from the outside, the polyester coating agents are normally added with peroxide curing agent and suitable accelerators, such as cobalt octoate or a tertiary amine.

Such coating compounds are also used when curing takes place at a higher temperature or when exposed to infrared rays or high-frequency energy.

Polyester coating compounds that are to be cured under the influence of ultraviolet light or sunlight contain photosensitizers as curing catalysts. In addition to benzoin, suitable photosensitizers are also its derivatives, such as e.g. benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin acetate, ct-benzylbenzoin, oc-methylbenzoin. Other suitable photosensitizers belong to the group of disulfides. Additional photosensitizers are benzyl, acetophenone, anthraquinone derivatives, benzophenone, phenanthrenequinone, diacetyl, tetramethylthiuram disulfide, naphthalene sulfochloride', bromotrichloromethane, bromoform, manganese carbonyl and hexa-arylimidazoles. In general, all substances used as photosensitizers are applicable for the curing.

The time required for complete curing of the coating depends on the polymerization activity of the resin, monomers, composition and amount of photosensitizers and on the quality and quantity of light energy, as well as the type and amount of coating material applied. High-pressure mercury solar vapor lamps, low-pressure mercury solar vapor lamps or superactinic fluorescent tubes are usually used as UV-emitting light sources.

The coating materials can be applied using normal application

, ing methods, such as pouring, spraying or rolling. The material to be coated may possibly be pre-treated or already have a layer of varnish or putty.

The enforcement methods may vary. thus, on the one hand, it is possible to directly mix in the catalysts or photosensitizers, but on the other hand, it is also possible to apply the peroxide first, in the form of a hardener primer, to the material to be coated - so-called "Aktivgrundverfahren ". The peroxide-free but accelerator-containing polyester material is then applied to the peroxide-containing substrate. It is also possible to apply the hardener-containing component and the accelerator-containing component "wet-on-wet".

The thickness of the coating can be varied within wide limits. Naturally, the covering ability of the opaque coatings is also less when the layer thickness is smaller. Covering layers with 10 µm dry-film thickness can, however, be achieved. Generally, the layer-thick tendons are larger, namely up to 1.5 - 2 mm. The preferred layer thicknesses are between 50 µm and 700 µm.

The following examples serve to illustrate the invention.

The parts mentioned mean parts by weight, and the indicated percentages mean percentages by weight. The "content" of the claim must also be understood on a weight basis.

EXAMPLE 1

A. In the usual way, an unsaturated polyester resin is produced from:

26 parts 1,2-propylene glycol,

16 parts maleic anhydride,

20 parts phthalic anhydride,

to this rate is added

0.003 parts hydroquinone

as a stabilizer and the resin is diluted at temperatures between 90 and 95°c with styrene to a solids content of 70%.

B. A coating agent is prepared from the following ingredients:

40 parts of the polyester solution obtained according to 1 A,

60 parts styrene, r.

1 part benzoin isopropyl ether.

654 g/m 2 of this coating material is poured onto a chipboard with a raised edge using a casting machine. The coating is then gelled for 3-5 minutes using a low-pressure quick-solar vapor lamp and then cured for 1 minute using a high-pressure quick-solar vapor lamp (HTQ7, brand Philips).

The coating obtained is white and opaque. The surface is structured, high-gloss and scratch-resistant.

EXAMPLE 2

A coating material is made from the components:

42.5 parts of the polyester solution obtained according to 1 A,

10 parts toluene,

5 2 parts styrene,

5 parts of a 5% paraffin solution in styrene, (paraffin's melting point is 60°C)5

1 part methylol-benzoin methyl ether,

1.5 parts silica airgel.

775 g/m 2 of this coating material is poured onto a chip

plate using a stop machine. The same hardening was through-

carried out as described in example 1. This resulted in a white, opaque coating with a matt and solid surface.

EXAMPLE 3

A coating material is made from the following components:

40 parts of the polyester solution obtained according to example 1 A,

60 parts styrene,

1 part finely divided silicic acid,

25 parts precipitated calcium carbonate,

1 part methylol-benzoin methyl ether.

650 g/m 2 of this covering material is poured onto a chip

plate using a stop machine. The curing takes place as described in example 1. This results in a white and opaque coating.

EXAMPLE 4

A coating material is made from the following components:

50 parts of the polyester solution obtained according to 1 A,

50 parts vinyltoluene,

2 parts of a 25% nitrocellulose solution in ethyl acetate.

3 parts of a 5% paraffin solution in styrene (paraffin's melting point is 60°C),

2 parts naphthalene-2-sulfochloride.

800 g/m 2 of this coating agent is poured onto a hard fiber board. The coating is then gelled for 2 1/2 minutes using a low pressure mercury vapor lamp and then cured for one minute with a high pressure mercury vapor lamp.

This results in a white and opaque coating.

EXAMPLE 5

To the coating material according to example 4, 0.05 parts of saponect yellow are added. After curing, a yellow coating is obtained which is also opaque.

EXAMPLE 6

A coating material is made from the following components:

5 7 parts of the polyester solution obtained according to 1 A,

42 parts styrene,

5 parts of a 5% paraffin solution in styrene (melting point of paraffin = 60°C), 1 part of a cobalt naphthenate solution in toluene with 4% cobalt metal content,

2 parts cyclohexanone peroxide.

1500 g/m of this covering material is poured onto a chipboard with a raised edge using a casting machine.

In this way, several samples are produced, which are hardened using different methods.

a. After standing overnight, the covering is thoroughly

hardened and opaque white.

b) The drying takes place using a nozzle dryer that blows hot air at a temperature of 140°C. The nozzle drying takes place afterwards

that the coating is gelled. The surface is treated approx. 1 1/2 to 2 minutes with the nozzle dryer, then the coating is fully cured and opaque white. c. The coating is treated with rays originating from an infrared-dark ray, which is placed at a distance of 25 cm from the plate to be coated. After approx. After 1 1/2 minutes, the coating is fully cured and opaque white. d. The coating is cured in an induction high-frequency field within 100 seconds. You get a white and opaque coating again.

An embodiment of the invention is illustrated schematically with the help of the drawing. Thus, fig. 1 a chipboard (1) which is provided with a coating layer (2), which layer is opaque and white.

Claims (1)

1. Materials with opaque lacquer coatings based on unsaturated polyesters and copolymerizable monomers, as well as common curing catalysts and possibly non-covering pigments, characterized in that the lacquer coating is produced from a coating material where the content of copolymerizable monomers, especially styrene, was greater than the content of unsaturated polyester , as the coating material did not contain components that were suitable to eliminate the incompatibility between the two phases that form in the coating during curing.