Technical field

This invention relates to an epoxy-based protective coating product.

In particular, the invention relates to a protective coating product for protecting a wide range of supports such as, for example, plaster, bricks, iron, wood, MDF, lightweight alloys, cement, glass, fibreglass, plastic, polypropylene, ABS, polyethylene.

Background art

Epoxy-based protective coating products are currently known, of the water-based or in any case solvent-free type, which, although providing a suitable protective layer to the support on which they are applied, have considerable drawbacks.

One major drawback is due to the fact that the prior art epoxy-based protective products have a limited "pot- life", that is to say, a limited time in which it is possible to use them starting from the moment the basic mixture is prepared for making the prior art protective product.

Generally speaking, in the prior art epoxy-based protective coating products, the "pot-life" time is unlikely to be greater than 90 minutes due precisely to the purely epoxy nature of the prior art products. Another major drawback is due to the fact that the prior art epoxy-based protective coating products have long times for a correct over-painting, approximately greater than 5-6 hours. Over-painting means the time required between spreading a first coat of product on the support and the possibility of spreading the next coat on the support. The above-mentioned drawbacks make the prior art protective products not optimised in terms of use in a wide range of contexts of use.

In fact, in order to "cover" a standard working day (approximately 10 hours) it is necessary for the operator to mix the product several times, thus losing operating time and considerably increasing the risk of making errors in the mixing.

The preparation of the mixture is in effect a function of the weighing of the various components, amongst other things, often not with a 1:1 ratio.

Aim of the invention

The aim of the invention is therefore to provide an epoxy-based protective coating product capable of overcoming the drawbacks of the prior art.

Another aim of the invention is to provide an epoxy- based protective coating product with a "pot-life" of at least 10 hours from the first mixing.

This aim is designed to allow, starting from a first and single mixing, the application of three coats of the product according to the invention during the standard working day (8-10 hours).

A further aim is to provide an epoxy-based protective coating product which is suitable for being applied on supports of various types, such as, for example, plaster, bricks, iron, wood, MDF, lightweight alloys, cement, glass, fibreglass, plastic, polypropylene, ABS, polyethylene . The above aims are achieved by an epoxy-based protective coating product comprising the technical features described in one or more of the accompanying claims.

Detailed description

Further features and advantages of the invention are more apparent in the non-limiting description which follows of a preferred embodiment of an epoxy-based protective coating product.

The epoxy-based protective coating product according to the invention comprises a mixture of an acrylic resin, an epoxy resin and at least one complex amine.

The weight ratio between the sum of the resins, acrylic and epoxy, with the at least one complex amine is greater than 20:1.

With a ratio greater than 20:1 (19:1, 18:1, 17:1...) it is understood that, for example, if the sum in weight of the two resins is 20 grams the presence in the mixture of at least one complex amine will be of a minimum of 1 gram .

It is understood that the ratio may also exceed 1:1 with the weight of the complex amines greater than the total weight of the two resins.

Advantageously, the acrylic resin has a minimum filming temperature of between 40° and 50°, in accordance with standards ASTM D 2354 and ISO 4622:1992.

The minimum filming temperature is a characteristic parameter of the acrylic resin provided by the manufacturer of the resin.

More in detail, there are various types of acrylic resins which have different minimum filming temperatures.

As mentioned, according to the invention, the acrylic resin must have a minimum filming temperature of between

40° and 50°.

The minimum film forming temperature (MFFT) of a resin is the minimum temperature at which the resin, applied on a predetermined substrate, joins and forms a homogeneous film without the presence of cracks.

For example, advantageously, the acrylic resin is a MAINCOTE AF400 ® resin.

The presence of the acrylic resin in the mixture according to the invention delays the catalysis time, thus increasing the pot-life, on the product in bulk.

In fact, the presence of acrylic resin performs in bulk an opposing action with the amine.

This phenomenon does not occur when the mixture is applied on a respective support in a thin layer, where the chemical affinity between epoxy resin and amine does not undergo interactions by the acrylic resin.

The presence of the acrylic resin favours, on the other hand, the drying of the mixture applied on a support through the drying phenomenon called coalescence.

This phenomenon acts as an aid for the final drying of the mixture applied on the support.

This phenomenon, known, as said, as coalescence, consists in the melting of the particles of the polymer of the acrylic resin together by the "pushing" upwards of the solvent part (water) and the subsequent evaporation of the particles of the solvent (water).

As the evaporation of the solvent increases, the layer of mixture applied on the support reduces clearly in its thickness, favouring the chemical interaction between the epoxy resin and the amino catalyst. This situation makes it possible to accelerate the drying time of the mixture applied and allows, through the above-mentioned catalysis, the application of up to 3 coats in the time of use determined by the pot-life. Advantageously, moreover, the epoxy resin is a resin with a long-chain reaction of Bisphenol A and ethylene oxide-epichlorohydrin, also called Oxirane.

Moreover, advantageously, the epoxy resin is an emulsion resin selected between CAS 25068-38-6 or 25036-25-3. Advantageously, moreover, the at least one complex amine comprises at least one or more selected between amine CAS 9046-10-0, amine CAS 124-68-5, amine CAS 941-395-8. According to various embodiments of the invention the product comprises at least two of the above-mentioned complex amines.

For sake of completeness only, CAS (Chemical Abstract Service) is a numeric identifier designed to uniquely identify any chemical substance.

It is useful to identify these CAS numbers in the present invention since most molecular databases currently permit searches based on the CAS number.

The CAS number consists of three sequences of numbers separated by dashes.

The first group consists of a variable number of digits, up to six, the second group consists of two digits, whilst the third and last groups consists of a single digit which serves as a control code.

The above-mentioned numbers are assigned in progressive order relative to the entry in the various databases and do not therefore have any chemical meaning.

Advantageously, the epoxy-based protective product according to the invention also comprises at least one additive selected between coloured pigments, organic phosphorus compound CAS 7320-34-5, fillers, wetting additives, dispersing additives, canning preservatives, coalescing additives, cellulosic thickeners, acrylic and polyurethane thickeners, substrate wetting additives, antifoaming additives, benthic thickeners, dispersing additives, acrylic and polyurethane thickeners, anti- algae and antibacterial additives, epoxy-silane additives CAS 2019-784-2.

Moreover, advantageously, the ratio by weight of the mixture constituting the protective product according to the invention is as follows:

- acrylic resin of between 10% and 20% by weight,

- epoxy resin of between 30% and 60% by weight,

- at least one complex amine of between 10% and 20% by weight.

According to the embodiments in which there is also at least one additive as described above, this is included in the mixture between 0% and 50% by weight.

In the protective coating product according to the invention, the acrylic resin performs the function of binding agent as well as the function performed by the epoxy resin in emulsion.

The epoxy resin also gives the product strength, adhesion and seal over time.

The complex amine CAS 9046-10-0 is an epoxy resin hardener and is also an alkaline pH regulator.

The complex amine CAS 941-395-8 is a hardener for epoxy resins in two-component systems. The complex amine CAS 124-68-5 is a pH regulator inside the product.

According to the embodiments in which there are additives, and in particular there are benthic thickeners, these, after having been hydrated with water, allow the suspension of any fillers, pigments and binders to be maintained in a homogeneous form, forming a supporting structure for the protective product according to the invention.

Again with reference to the additives, the presence of canning preservatives (anti-mould function as the protective product is contained in its can) uses a mixture comprising a preparation of silanes, amines, chelating agents, and stabilisers with addition of potassium hydroxide, TMDEA and quaternary ammonium salt, ethoxylated alcohol CIO-16, Silanetriol, 1-methyl-, potassium salt (1:3) CAS 65351-55-5.

The presence of this preservative makes the protective coating product protected inside the container without using, as in the prior art, toxic and irritating products, such as, for example, isothiazolinone and derivatives.

Moreover, the epoxy additives, when present, improve adhesion of the protective coating product according to the invention when applied on various supports as well as resistance to immersion.

Examples of possible different formulations of the protective coating product according to the invention are given below.

Example 1: Two-component protective finishing product Suitable for example for protecting indoor and outdoor floors, interior walls, especially in high humidity environments such as bathrooms, kitchens and cellars. Component 1 - Epoxy Resin + Additives

Component 2 - Acrylic resin + complex amines and additives Two-component paint with long pot-life (10 hours) for painting difficult supports, such as ceramic floors, sanitary tiles, cisterns, etc. Component 1 - Epoxy resin + additives

Component 2 - Acrylic resin + complex amines + additives

The protective product according to the invention can be made by the following process.

A vertical disperser is used as a mixing tool with the capacity to put the main container under a vacuum and also to keep it cooled to temperatures of approximately 30°C.

A first step of the production process consists in inserting the components of the mixture of the protective product in the disperser and then creating the vacuum in it and actuating the mixing for approximately 40 minutes. Subsequently, the vacuum is deactivated by re- introducing air inside the disperser and reducing the mixing speed; this being maintained for a further 90 minutes.

The above-mentioned second step of the process occurs advantageously at a temperature of approximately 30°C. Advantageously, moreover, between the first step and the second step there is never an interruption of the mixing speed, that is to say, the disperser is always kept actuated.

More in detail, the first step of the process (vacuum) is advantageous since it allows the dispersion of the cellulose and the addition of additives to be accelerated without incorporating air in the process.

The second step, on the other hand, allows the performance of additives to not be compromised.

A protective product according to the invention may be applied on the above-mentioned range of supports, for example by brush, roller or air gun.

This protective product achieves the preset aims and brings important advantages.

A first important advantage consists in the fact that the protective product according to the invention having a "pot-life" of approximately 10 hours allows the operator to perform a single first mixing at the start of the working day without the need to perform new mixing operations during the working day.

This advantage is even more significant since it allows the product according to the invention to be spread in up to three coats without the product contained in the mixing container becoming dry and unusable.

A further advantage consists in the fact that by modifying the presence and the quantity of the various additives it is possible to obtain a protective product having a range of functions and possible applications on various supports.

All of this is obtained using a protective product which does not require the pre-applications of primer or the like on the support to be protected since it guarantees an excellent grip and resistance to detachment.