EP0326488A1 - Abrasive and/or scouring pad, replacing steel wire wool, and method for its manufacture - Google Patents

Abstract

The abrasive and/or scouring pad of the invention comprises a foam core (2) between two nonwoven materials (1). Its characteristics are as follows: the said core (2) is a polyurethane foam: the nonwoven materials (1) are based on a mixture of polyamide and polyester fibres; the said polyamide having physical properties close to those of the said polyurethane foam; the said nonwoven materials and the said foam are joined together at their periphery (3) by heat welding either directly or by the intermediary of two layers of a thermofusible or thermosoftening material disposed on either side of the said foam. This said pad advantageously substitutes for steel wool when it is coated with abrasive loads. It can also be used as a scourer for fragile surfaces when it contains no or few abrasive loads. The present invention also concerns a method for manufacturing the said pad. <IMAGE>

Description

The present invention relates to the field of cleaning and more particularly an abrasive pad, substitute for steel wool, and / or scouring. It also relates to a process for obtaining said buffer.

Steel wool has long been used as a pad to scour kitchen equipment, such as pots, pans and pots.

These steel wool pads, however, have the disadvantage of rusting, quickly falling apart, and being difficult to clean. In addition, they are unpleasant to the touch.

We now propose, according to a variant of the invention, an abrasive pad on both sides which constitutes a substitute for steel wool, without having the disadvantages and which, in particular, lasts much longer, while retaining its appearance. and its original properties.

According to other variants of the invention, scouring or mixed pads are also proposed: scouring on one side, abrasive on the other.

The abrasive and / or scouring pad according to the invention comprises a foam core between two nonwovens. Its characteristics are as follows:
- Said core is a polyurethane foam;
- the nonwovens are based on a mixture of polyamide and polyester fibers; said polyamide having physical properties close to those of said polyurethane foam;
- Said nonwovens and said foam are joined at their periphery by heat sealing, either directly, or by means of two layers of a hot-melt or heat-softening material arranged on either side of said foam.

The specificity of the materials involved in the composition of the tampon according to the invention gives it advantageous properties as regards its cleaning, scouring action, as well as the possibility of constructing it by heat-sealing, the weld produced being efficient. Indeed, the heat sealing made with such materials is solid, non-brittle, non-cutting; nor does it tend to separate from the tampon.

The tampon according to the invention can therefore exist in two variants:
- either it includes the foam block between the two nonwovens;
- Either it includes the block of foam between the layers of hot-melt or heat-softening material, all between the two nonwovens.

The foam used is a polyurethane foam, the composition of which is based on polyols and isocyanates.

Said foam constitutes the core of the tampon. It is stabilized inside of it, since it is secured at least to the two nonwovens, around its entire periphery.

Said foam can be loaded. According to a preferred variant of the invention, it contains soap particles. Said particles can be of variable particle size.

The intervention of these soap particles, during the development of the foam, causes a slight modification of the physical properties of the latter.

Thus, in the industrial context, it is sometimes difficult to guarantee a truly constant quality of polyurethane foam, especially therefore when fillers, soap for example, are involved in the manufacture of said foam. This is why provision is made, according to the second variant of the invention, for the intervention of hot-melt or heat-softening materials. We can thus guarantee the reliability of the weld, with polyurethane foams of slightly fluctuating quality.

The materials capable of constituting the intermediate layers of the tampon according to the invention are materials that melt or soften at at least the thermoforming temperature of the tampon.

They are, in fact, intended to play the role of auxiliary bonding agent, the role of "regulator of weldability".

Advantageously, these are "pure" products, the thermal properties of which are perfectly controlled. We can in particular use:
- layers of polyurethane foam, type polyurethane-polyester, polyurethane-polyether ...,
- thermoplastic films such as polyethylene films,
- sheets of fibers, for example based on polypropylene, polyester ...

Any material capable of serving as an adhesive agent at the thermoforming temperature of the pad is suitable.

It is obvious that advantageously the same material is used for the two intermediate layers.

However, it is not excluded, according to the invention, the use on either side of the foam, of materials of different nature.

When the foam core of the tampon includes fillers to be released - soap, for example - said material must be permeable to allow the evacuation of said fillers with water, during use of the tampon.

In the case of the use of thermoplastic films, around a filled foam, provision must therefore be made for the presence of perforations on said films.

These intermediate layers of thermofusible or thermo-softening materials intervene, as specified above, advantageously around foams loaded with soap, of which it is sometimes difficult to ensure a constant quality.

They guarantee the good weldability of the tampon and, moreover, in this particular case, slows down the release of the soap. They ensure a certain retention. This variant of the invention allows a certain control of the release of the soap, avoids significant initial losses.

The nonwovens which are suitable for the purposes of the invention are sheets of a mixture of polyamide / polyester fibers. Said polyamide has physical properties - melting temperature - close to those - softening temperature - of the polyurethane foam used, possibly loaded.

The fibers involved in the composition of said nonwovens have been selected, according to the invention, for their mechanical properties - abrasion resistance, mechanical resistance - and their physical characteristics - thermofusibility -. These are polyamide and polyester fibers.

Polyamide fibers have excellent abrasion resistance and good mechanical resistance. The polyester fibers have good abrasion resistance as well as high mechanical resistance. Preferably, according to the invention, fibers of a unit titration of less than 50 dtex are chosen. Such fibers have a good coverage rate and make it possible to obtain flexible nonwovens, which are not unpleasant to the touch.

For practical reasons, the polyamide fibers generally used have a unit titer between 6.7 and 44 dtex, polyester fibers, a unit titer between 4.4 and 40 dtex.

The physical properties of said fibers are fundamental. They allow the formation of a flexible seal at the periphery of the pad by heat sealing.

The polyamide having the lowest transformation temperatures - melting temperature - is used as a bonding agent. The melting point of the polyamide is in fact in the range of processing temperatures - softening - of the polyurethane foam.

Thus, by heating to an adequate temperature, during welding, it causes the formation of an intimate "liquid" mixture: polyamide-polyurethane, within which the polyester fibers begin to soften. Indeed, polyester fibers are more resistant to heat than polyamide fibers. One can thus obtain an effective seal, which has a certain flexibility and which also allows the stabilization of the foam inside the tampon.

According to the invention, a judicious selection of materials has been made: polyamide, polyester, polyurethane foam. The combination of these makes it possible to obtain, by a simple technique, high-performance abrasive and / or scouring pads.

It is also possible, for the reasons mentioned above, to use an auxiliary bonding agent: the layers of hot-melt or thermo-softening material.

Advantageously, the nonwovens are based on a mixture comprising by weight 50 to 90% of polyamide fibers and 50 to 10% of polyester fibers. The amounts of polyamide and polyester involved can indeed be optimized, taking into account the desired results, in particular at the joint.

At this level, it has been shown that polyamide acts as a bonding agent and polyester as a flexibility agent.

Preferably, the nonwovens are based on a mixture comprising by weight approximately 80% of polyamide fibers and approximately 20% of polyester fibers.

With regard to the fibers used, the Applicant has also shown the advantage that there are, to use, at the weight percentages indicated above, low-titer polyester fibers and / or mixtures of polyester fibers , and more particularly of polyamide, of different titrations.

If polyester fibers of low titration are used, more are used and a very particular homogeneity of the material is thus obtained, as well as a remarkable flexibility thereof, over its entire surface and also in the weld. Thus, polyester fibers are advantageously used, the unit titer of which is between 4.4 and 17 dtex, limits included.

In the same way, by mixing at least two polyamide fibers of different titration, one can - with identical tack factor at the joint - improve the surface condition of the pad.

Advantageously, polyamide 6 fibers are used in the nonwovens of the pads according to the invention. Other polyamide fibers can also be used. As stated above, the polyamide used should have physical properties close to those of the polyurethane foam chosen.

In fact, the melting temperature of said polyamide must be within the range of softening temperatures of said foam.

It should be noted, by way of illustration, that the nonwovens used in the pads according to the invention can advantageously be based on a mixture of:
- 20% by weight of polyamide 6 fibers of 44 dtex,
- 60% by weight of polyamide 6 fibers of 22 dtex,
- 20% by weight of polyester fibers of 17 dtex.

The nonwovens constituting the faces of the pads according to the invention, based on the fiber mixtures described above, are mechanically prewound before being chemically bonded, preferably by a synthetic latex such as, for example, a thermosetting latex.

Said chemical binder must give the mixture of fibers a fairly significant internal cohesion, without however generating by its presence in the welding plane, during heat sealing. It is therefore advisable to use a controlled quantity. The weight of binder deposited relative to the weight of the fibers must be between 0.2 and 0.6. The weight of binder deposited generally varies between 10 and 60 g / m² (by dry weight).

After heating, a sheet of bonded fibers is obtained.

This sheet can be used as it is, as the faces of a scouring pad according to the invention. However, it is generally preferred to subject it to an additional treatment, namely a spraying of a formulation, possibly containing abrasive fillers. This formulation is generally based on a synthetic latex: phenolic resin or acrylic latex.

This non-excessive spraying can only be carried out on one face of the nonwoven, that intended to constitute the external surface of the tampon. In addition, in the event that the formulation contains abrasive fillers, it should not be allowed to penetrate too deeply into the nonwoven. His both conditions must be met if you want to obtain a correct and uniform weld around the edge of the pad.

The intervention or not of abrasives, in more or less quantity, made up of more or less hard materials, obviously depends on the properties which one wishes to confer on the pad according to the invention, more exactly on each of the faces of the pad according to l 'invention.

The pads according to the invention can indeed have two faces with abrasive, a single face with abrasive or no face with abrasive. It suffices to associate nonwovens, having on one of their faces the adequate surface condition.

The pads according to the invention, with abrasive charges, advantageously replace steel wool.

The pads according to the invention, with little or no abrasive charges, are advantageously used as scourers on fragile surfaces.

As suitable abrasive fillers, it is possible, for example, to use silicon carbide, alumina, silica, talc or mixtures thereof.

These abrasive fillers are deposited on the bonded web at a rate of approximately 50 to 200 g / m² (by dry weight) of the formulation which contains them.

It will be recalled that even in the absence of such fillers, the nonwovens, based on polyamide and polyester fibers, bonded and possibly having been sprayed, advantageously constitute the faces or at least one of the faces of a pad according to the invention.

According to an alternative embodiment of the invention, the tampon also contains soap.

We have seen above that advantageously, said soap is contained, distributed within the polyurethane foam, in solid form. The solid particles can be of variable particle size. The tampon according to the invention can also have, on at least one of its external faces, a "film" of soap.

The present invention also relates to a method for obtaining buffers as described above.

This process consists of:
- To produce the nonwoven / foam / nonwoven assembly, or the nonwoven assembly / hot-melt or thermo-softening material / foam / hot-melt or thermo-softening / nonwoven material, so that the abrasive and / or scouring faces of said nonwovens 'exterior;
- To present the assembly thus produced between the upper and lower molds of a thermoforming tool;
- heat sealing the sandwich thus formed at a temperature in the range of softening temperatures of the polyurethane foam and at least equal to the melting temperature of the polyamide fibers;
- to individualize, finally, by cutting, the pads obtained.

The nonwovens are obtained, as specified above, from a sheet of fibers, mechanically preloaded, chemically bonded, preferably by a synthetic latex and onto which a phenolic resin has optionally been sprayed. Said resin optionally contains abrasive fillers.

Between said nonwovens, the polyurethane foam is optionally placed between the two layers of the hot-melt or heat-softening material used, and the assembly is presented between the upper and lower molds of a thermoforming tool. The thermoforming tool is mounted on a press.

The shape of the molds will condition the shape of the pads obtained. These can in particular be in the form of small cushions, cylinders ...

The sandwich is heat sealed. The stamps obtained are individualized by cutting.

Heat sealing is carried out at a temperature close to the processing temperatures of polyurethane foam and polyamide fibers.

There is thus produced, at the periphery of the tampon, an intimate mixing zone of said materials, within which polyester fibers begin to soften. At this temperature, it also causes the fusion or at least the softening of the intermediate layers, possibly present. The compressed area, once cooled, constitutes the joint between the two faces of the tampon. Heating in the thermoforming tool can be ensured by any means and in particular by means of electrical resistances, heat transfer fluids or by microwave, high frequency techniques, etc.

The precise operating conditions of thermoforming obviously depend on the exact nature of the materials involved and their thickness. Their optimization is within the reach of those skilled in the art.

The invention will now be described in more detail in the example below.

An abrasive pad according to the invention is produced from a sheet of fibers, comprising:
- 20% by weight of polyamide fibers 6 to 44 dtex,
- 60% by weight of polyamide fibers 6 to 22 dtex,
- 20% by weight of polyester fibers at 17 dtex.

Said tablecloth weighs 90 g / m². It is impregnated with a binder - acrylic latex - in a bath, containing agents necessary for its use.

The dry weight of latex deposited is approximately 40 g / m² (the weight ratio of latex deposited / weight of fibers is approximately 0.50).

The impregnated sheet is dried in two successive ovens, the temperatures within these ranging from 50 to 150 ° C.

It then undergoes on one of its faces, a spraying step. A phenolic resin solution containing a mixture of silica and alumina is used. In this solution, the filler rate / binder rate is equal to 3. The amount of dry product deposited on the sheet during this spraying step is approximately 150 g / m². Said sheet, after drying, can be conditioned to the desired dimensions. It then weighs around 280 g / m². Its thickness is approximately 6.6 mm.

To make a tampon according to the first variant of the invention, a sandwich is made by inserting a foam of polyurethane between two sheets of this type. A 10 mm thick foam, loaded with soap, is used. Said foam has a softening zone between 200 and 240 ° C. The sandwich is heat sealed in the molds of a thermoforming tool mounted on a press. The essential parameters of this heat seal are as follows:
O = about 220 ° C
p = 15.10⁵ to 2.10⁶ Pa (15 to 20 bars)
t = 1 min.

The temperature of the heat seal corresponds to the start of the melting zones of polyamide 6 and of the polyurethane foam and at the start of the bonding zone, of softening of the polyester.

The polyester fibers, at the limit of softening, are bonded under the action of pressure at their periphery by the "solution" polyamide-polyurethane. A perfectly homogeneous weld is thus obtained.

The pads are then individualized.

They are characterized by remarkable efficiency and duration. In particular, they last approximately 4 times longer than conventional steel wool.

Regarding their abrasiveness, it can be measured with the Taber test.

The Taber test is a test to assess the abrasive behavior of nonwovens; the evaluation is made by measuring the weight loss of aluminum rollers, applied to the nonwoven with a certain load (1.5 kg), the nonwoven being driven in a rotational movement.

The faces of the pad have an abrasiveness of 315 mg / 1000 revolutions (initial abrasiveness at 50 revolutions), of 215 mg / 1000 revolutions (abrasiveness at 200 revolutions).

In the same way, a tampon can be produced according to the second variant of the invention, by heat-sealing a sandwich comprising, between the two layers of nonwovens described above, a polyurethane foam, 8 mm thick, loaded with soap between two layers of polyurethane-polyester foam 1.4 mm thick.

The polyurethane foam is the same as that used previously (softening zone 200-240 ° C.. The polyurethane-polyester foam has a wider softening zone: 180-240 ° C. Part of it is even hot melt .

• La figure 1 est une vue en perspective d'un tampon selon l'invention.
• La figure 2 est une coupe d'un tampon selon la première variante de l'invention.
• La figure 3 est une coupe d'un tampon selon la seconde variante de l'invention.

The invention is illustrated in Figures 1-3 below.

• Figure 1 is a perspective view of a tampon according to the invention.
• Figure 2 is a section of a tampon according to the first variant of the invention.
• Figure 3 is a section of a tampon according to the second variant of the invention.

In these figures, there are shown in (1) and (1 ′) the two nonwovens constituting the external faces of the pad.

The polyurethane foam core of said pads is shown in (2). It is loaded with soap particles (4).

The welding plane is shown in (3).

According to the first variant of the invention (Fig. 2), the nonwovens (1) (1 ′) and the foam (2) are secured directly to their periphery.

According to the second variant (Fig. 3), there are two additional layers of foam (5), on either side of the foam core (2).

Claims (14)

1. Abrasive and / or scouring pad, comprising a foam core between two nonwovens, characterized in that said core is a polyurethane foam, the nonwovens are based on a mixture of polyamide and polyester fibers, said polyamide having physical properties close to those of said polyurethane foam; and in that said nonwovens and said foam are joined at their periphery by heat-sealing, either directly or through two layers of a hot-melt or heat-softening material arranged on either side of said foam. 2. Abrasive and / or scouring pad according to claim 1, characterized in that the polyurethane foam contains soap. 3. Abrasive and / or scouring pad according to one of claims 1 or 2, characterized in that said intermediate layers are layers of polyurethane foam type polyurethane-polyester, polyurethane-polyether, thermoplastic films possibly perforated or sheets of fibers . 4. Abrasive and / or scouring pad according to claim 1, characterized in that the polyamide and polyester fibers have a unit titer of less than 50 dtex. 5. Abrasive and / or scouring pad according to claim 1, characterized in that the nonwovens are based on a mixture of 50 to 90% by weight of polyamide fibers and 50 to 10% by weight of polyester fibers ; preferably about 80% by weight of polyamide fibers and about 20% by weight of polyester fibers. 6. Abrasive and / or scouring pad according to claim 1, characterized in that the polyester fibers have a unit strength of between 4.4 and 17 dtex. 7. Abrasive and / or scouring pad according to claim 1, characterized in that the nonwovens are based on a mixture of polyamide 6 and polyester fibers. 8. Abrasive and / or scouring pad according to claim 1, characterized in that the nonwovens comprise:
- 20% by weight of polyamide 6 fibers of 44 dtex,
- 60% by weight of polyamide 6 fibers of 22 dtex,
- 20% by weight of polyester fibers of 17 dtex. 9. Abrasive and / or scouring pad according to claim 1, characterized in that the nonwovens, mechanically preloaded, are chemically bonded, preferably by a synthetic latex, the weight of binder deposited, relative to the weight of fibers, being between 0.2 and 0.6. 10. Abrasive and / or scouring pad according to claim 9, characterized in that, on the nonwovens, chemically bonded, a formulation is sprayed, which optionally contains abrasive fillers. 11. Abrasive and / or scouring pad according to claim 1, characterized in that at least one of the two nonwovens has abrasive fillers on one side, said face constituting an external face of the pad. 12. Scouring pad according to claim 1, characterized in that the two nonwovens do not contain abrasive charges. 13. Method for obtaining an abrasive and / or scouring pad according to claim 1, characterized in that it consists:
- To produce the nonwoven / foam / nonwoven assembly, or the nonwoven assembly / hot-melt or thermo-softening material / foam / hot-melt or thermo-softening / nonwoven material, so that the abrasive and / or scouring faces of said nonwovens 'exterior;
- To present the assembly thus produced between the upper and lower molds of a thermoforming tool;
- to individualize, finally, by cutting, the pads obtained. 14. Method according to claim 12, characterized in that the nonwovens are obtained from a sheet of fibers, mechanically preloaded, chemically bonded, preferably by a synthetic latex, on which a phenolic resin has been optionally containing fillers. abrasive.

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