WO2001010621A1

WO2001010621A1 - Method for making lined foamed articles

Info

Publication number: WO2001010621A1
Application number: PCT/IB2000/001084
Authority: WO
Inventors: Mario Damo
Original assignee: G.M.P Poliuretani Spa
Priority date: 1999-08-04
Filing date: 2000-08-02
Publication date: 2001-02-15
Also published as: ITUD990143A1; IT1310886B1; AU6010100A; ITUD990143A0

Abstract

Method to produce, inside at least a mold (11), polyurethane articles, and relative articles, covered by a film (20) having specific aesthetic surface characteristics, said method providing to make said film (20) cooperate with the walls of at least a part (12 or 13) of the mold (11) kept open, to close the mold (11) and inject the polyurethane material (21) inside the mold (11), the heat and pressure deriving from the polymerization reaction of the polyurethane (21) causing the polyurethane material to couple with and be constrained to the film (20) and determining the definitive thermoforming of said film (20).

Description

METHOD FOR MAKING LINED FOAMED ARTICLES

* * * * *

FIELD OF THE INVENTION The invention concerns a method to make covered polyurethane articles and the relative articles as set forth in the respective main claims.

The invention is applied in the molding of articles made of polyurethane material, whether they be - to give a non- restrictive example - items of furniture, furniture wings, automatic distributors, containers, etc., which require particular aesthetic characteristics and functions.

The invention also allows to avoid all the steps of sanding, painting and, in general, surface finishing, necessary until now to obtain the same aesthetic and functional result.

Moreover, the invention reduces the number of working steps needed to complete the process, reducing the time and optimizing the space needed. BACKGROUND OF THE INVENTION

The state of the art includes a plurality of methods to produce polyurethane articles with particular aesthetic characteristics and with surface resistance, which are being applied more and more widely - for example but not only - in various fields in the state of the art, such as furnishing, gifts and fancy goods.

These articles are obtained essentially by means of two construction processes.

The first provides to paint the surface of the article directly in a molding step.

Apart from being complex, this process does not give satisfactory results which can be repeated with an acceptable level of standardization. A second process provides to apply on the polyurethane article a covering, protective film.

In this second case the technique used provides to mold and thermoform, in an appropriate mold, a film to cover the polyurethane, then to insert it into another mold to mold the article and then to inject the polyurethane itself inside said mold.

In this way, by means of the covering film, the necessary surface resistance is ensured for the polyurethane articles. So that the polyurethane articles can be considered finished, they must be subjected to a further working step, consisting at least of trimming and cleaning the irregular, poorly defined edges which are formed.

This last working step can be done either in the mold or in a different place.

All these production steps have disadvantages, including the surface quality of the product which is never regular, due to the plays in elasticity of the products which are heated at different times and the adaptation of the thermoform to the mold, because of the injection of the polyurethane .

A further problem in the state of the art, linked to that described above, is the absence of a constant quality.

To these problems concerning the finished product we must add those concerning the production steps, in the first case, of painting in the mold, such as the difficulty of changing the final color of the article, especially if the painting occurs in the mold because it is necessary - at least with every change of color - to wash and change the mold.

Instead, in the second case, it is necessary to have large work spaces available both to move the material, and also to allow all the working steps to be carried out as described above. Moreover, we have to take into consideration the time taken for the various steps .

To this we must add the great ecological damage caused by the painting and the discards. The present Applicant has devised and embodied this invention to overcome the shortcomings of the state of the art and to obtain further advantages as will be shown hereafter .

SUMMARY OF THE INVENTION The invention is set forth and characterized in the main claims, while the dependent claims describe other innovative characteristics of the main embodiment.

The purpose of the invention is to achieve a production process which will supply a polyurethane article covered by a protective film in a single step.

In the preferential embodiment, the production process provides to lay down a film, with particular aesthetic and functional features, in cooperation with the walls of the female part of the open mold in which the article is molded. Subsequently to this step, the mold is closed and the polyurethane is injected.

The polymerization of the polyurethane injected into the mold generates a combination of heat and pressure which is suitable to thermoform the film and cause the polyurethane to couple with the film.

According to a variant, before it is definitively thermoformed by the heat generated by the polymerization process of the polyurethane injected into the mold, the film can be pre-molded directly in the mold. Pre-molding is possible due to the presence in the wall of the mold of suitable heating means and also optional means suitable to create a depression.

Said means allow to pre-mold and pre-heat the film, which for more complex forms facilitates the thermof orming due to the injection of the polyurethane inside the mold.

The advantages of the invention, apart from obtaining the covered article in a single step, are many. The molding of the film and its union with the polyurethane is obtained by using the heat and pressure generated by the polymerization reaction of the polyurethane itself.

This system guarantees a constant quality and a perfect surface of the article which cannot be obtained with the known state of the art.

A further purpose of the invention is to eliminate the steps of sanding and painting in order to achieve considerable economic and ecological advantages, and in terms of safety (for example, the emission of solvents, waste disposal, fire risks, etc.) .

By eliminating the painting step, the invention also allows to rapidly change the surface characteristics of the article, as it is sufficient to replace the film in order to obtain the aesthetic effect and the surface resistance desired.

Another purpose of the invention is to improve both the mechanical characteristics of the surface and the aesthetic characteristics of the article. In fact, the greater elasticity of the film and its thickness allow to mask some defects in the surface of the article without requiring further operations, as in the case of painting.

A variant of the main embodiment of the invention provides to apply the film with both aesthetic and functional characteristics on both sides of the article.

This embodiment provides to apply two sheets of film, which may even be different from each other, - one for the female part and the other for the male part of the mold - where at least the female part retains its film with means suitable to create a depression and/or pre-heating.

The film may come from a reel, or from pre-cut sheets. A further embodiment of the invention is to provide several molds in line, operating in sequence and having the same innovative characteristics as the embodiments described here, but allowing a numerically greater production. BRIEF DESCRIPTION OF THE DRAWINGS These characteristics and advantages of the invention will be clear from the following description of the preferential form of embodiment, given as a non-restrictive example, with reference to the attached drawings .

In the attached drawings, identical parts, or parts having identical functions, have the same reference number.

Fig. 1 is a section of the press with reels for film and the mold in the open position; Fig. 2 is a section of the press with reels for film and the mold in the closed position; Fig. 3 is a variant of Fig. 2, showing a section of the press with reels for film and two identical molds; Fig. 4 is a section of the press with reels for several films and the mold in the open position; Fig. 5 is a section of the press with reels for several films and the mold in the closed position;

Fig. 6 is a variant of Fig. 5 showing a section of the press with reels for several films and two identical molds .

DETAILED DESCRIPTION OF PREFERENTIAL EMBODIMENT With reference to the attached Figures, the number 10 denotes generally a press to produce finished polyurethane products in different forms according to the invention.

As shown in Fig. 1, the press 10 is essentially suitable to receive a mold 11 with a male part 12 and a female part 13.

Both the male part 12 and the female part 13 of the mold 11 have suitable means 17 to heat the mold 11 and suitable means to create a depression 18 in the mold 11.

Between the male part 12 and the female part 13 of the open mold 11 there is a film 20, which can be pre-cut or can come from reels 16.

Between the mold 11 and the film 20 there are means 14 suitable to attach and tension the film 20 which cooperate, when the mold 11 is closed, with possible means 15 suitable to cut the film 20.

Moreover, in a preferable position, there is the conduit 19 to inject the polyurethane 21, advantageously located in a central position.

In the embodiment shown here, the conduit 19 to inject the polyurethane 21 is provided in a central position in the mold 11, but it is obvious that the injection conduit 19 can be placed in any position whatsoever with respect to the mold 11 according to the preferential flow of the material.

A first variant of the invention is shown in Fig. 2 where a mold 11 is described in the closed step.

Fig. 2 provides that a film 20 is thermoformed in the mold 11 before the polyurethane 21 is injected. The thermofor ing is obtained by activating the means 17 suitable to heat the mold 11 and the means 18 suitable to create a depression in the mold 11.

At the same time as the mold 11 is closed, with the male part 12 brought near to the female part 13, at the end of the mold 11, the means 14 suitable to attach and tension the film 20 cooperate with the means 15 suitable to cut the film

20.

The production method according to the invention provides that the mold 11 in its closed position is filled with polyurethane 21 by means of the injection conduit 19.

When the mold 11 is full, the injection conduit 19 stops injecting polyurethane 21 and after an interval of time suitable for the completion of the polymerization reaction, the mold 11 is opened.

The article obtained already has a film 20 applied to the polyurethane 21 thanks to the reciprocal coupling and the thermoforming obtained by the heat and pressure which develop during the polymerization of the polyurethane 21.

Moreover, the ends of the film 20 are already duly cut, thanks to the cooperation between the means 14 and 15 located at the end of the mold 11.

A further variant of the invention is shown in Fig. 3, where, to give an example, at least a pair of molds 11 are placed inside a single press 10.

In the respective male 12 and female 13 parts, the molds 11 have means 17 suitable to heat them and means 18 suitable to create a depression inside them. Each mold 11 includes means 14 suitable to attach and tension a film 20, said means cooperating with means 15 suitable to cut a film 20, since the film 20 is wound on reels 16; each mold 11 also includes an independent conduit 19 for each mold 11, to inject the polyurethane 21. Fig. 4 shows a further embodiment of the invention which allows to produce articles having two films 20 and 23 on both sides of the article, the films being wound on reels 16 and 22.

As shown in Fig. 4, the mold 11 has at its ends two reels 16 and 22, with different heights, which allow the films 20 and 23 to pass from one part of the mold 11 to the other.

The films 20 and 23 are made to adhere to the respective male 12 and female 13 parts of the mold 11 by the suitable heating means 17 and the means 18 suitable to create a depression in said parts of the mold 11.

Thus, once the films 20 and 23 are in contact with the respective parts 12 and 13 of the mold 11, the working and molding of the article can be started, with a possible pre- molding of the films 20 and 23, the closing of the mold 11 and the injection of the polyurethane 21 which inside the mold 11, thanks to the heat and pressure of polymerization, couples with and is constrained to the films 20 and 23. Fig. 5 shows the second example of the invention wherein the films 20 and 23 are thermoformed directly in the mold 11.

The films 20 and 23 are thermoformed with the same systems as described previously, allowing to obtain an article finished on both sides.

A further variant of Fig. 5 is described in Fig. 6, where, as an example, a plurality of molds 11 are placed inside a single press 10.

In the respective male 12 and female 13 parts, the molds 11 have means 17 suitable to heat them and means 18 suitable to create a depression inside them.

Each mold 11 includes means 14 suitable to attach and tension the films 20 and 23 which cooperate with means 15 suitable to cut the films 20 and 23, since the films 20 and 23 are wound on reels 16 and 22; each mold 11 also includes an independent conduit 19 for each mold 11, to inject the polyurethane 21.

It is obvious, however, that additions and modifications may be made to the method as described heretofore, but these shall remain within the field and scope of the invention.

It is also obvious that, although the invention has been described with reference to specific examples, a person skilled in the art shall certainly be able to achieve many other equivalent solutions, but these too shall all come within the field and scope of the invention.

Claims

1 - Method to produce, inside a mold (11), polyurethane articles covered by a film having specific aesthetic surface characteristics, the method being characterized in that it provides to make said film (20) cooperate with the walls of at least a part (12 or 13) of the mold (11) kept open, to close the mold (11) and inject the polyurethane material (21) inside the mold (11) , the heat and pressure deriving from the polymerization reaction of the polyurethane (21) causing the polyurethane material to couple with and be constrained to the film (20) and determining the definitive thermoforming of said film (20) .

2 - Method as in Claim 1, characterized in that it provides an at least partial thermoforming of the film (20) with the mold (11) open.

3 - Method as in Claim 2, characterized in that said at least partial thermoforming with the mold (11) open is made by means of heating means (17) and means able to create a depression (18) arranged in cooperation with the walls (12 and 13) of the mold (11) .

4 - Method as in Claim 1, characterized in that the film (20) is attached and tensioned by means (14) to attach and tension a film (20) arranged in cooperation with the mold (11) • 5 - Method as in Claim 4, characterized in that the film (20) is supplied in reels (16) and is cut by cutting means (15) cooperating with the mold (11) and with the means (14) to attach and tension the film (20) .

6 - Method as in Claim 4, characterized in that the film (20) is pre-cut to size.

7 - Method as in any claim hereinbefore, characterized in that it provides to make a film (20 and 23) cooperate respectively with the walls of both the male part (12) and - li ¬

the female part (13) of the mold (11) to obtain an article covered on both sides .

8 - Method as in Claim 6, characterized in that two films (20 and 23) are placed inside the mold (11) in the open position at least at different heights.

9 - Method as in any claim hereinbefore, characterized in that in a single press (10) there can be two or more molds (11) to obtain covered articles.

10 - Method as in Claim 1, characterized in that the polyurethane material (21) is injected through a conduit

(19) arranged in a substantially central position in one of the parts (12, 13) of the mold (11).

11 - Method as in Claim 1, characterized in that the polyurethane material (21) is injected through a conduit (19) arranged in a lateral position in one of the parts (12, 13) of the mold (11) .

12 - Polyurethane articles covered by at least a film, characterized in that a thermoformed film (20) at least partly surrounds a body of expanded polyurethane in contact with said film (20) and resting stably thereon.

13 - Article as in Claim 12, characterized in that it is obtained according to one of the claims from 1 to 11.