DE2805399A1 - PROCESS FOR IMPROVING THE THERMAL RESISTANCE OF PARTS MADE FROM THERMOPLASTIC CARDBOARD, AND THE PARTS THEREOF THEMSELVES - Google Patents

Description

Patent attorneys
Dipl, -Ing, W, Beyer Dipl, -Wirtsch, -Ing, B, Jochem

Frankfurt am Main .... ... Staufenstrasse 36

In matters:

CARTONNERIES REUNIES VOISIN t PASCAL

14-16 rue Tronchet

Lyon 6 ° (Rhone) France

Process for improving the heat resistance of thermoplastic Cardboard manufactured parts and the parts obtained with it themselves.

The invention relates to a new process for the manufacture of parts from thermoformed or thermoformed thermoplastic cardboard. The process avoids, in the case of the parts obtained, the deformability of the cardboard used for their manufacture under heat; moreover makes it possible to give these parts of properties that are not possessed by the thermoplastic cardboard, and bring about an improvement of the existing properties, namely, rigidity, moisture and heat resistance to time up to 1o5 ° C _f

The invention relates to you in the sense of a new industrial product, the parts obtained in this way made of thermoformed cardboard. The parts according to the invention can be used in a wide variety of fields. For example, they can be used in the motor vehicle industry, in particular as interior panels

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Doors, or to form the rear shelf or the interior paneling of a special _krai : _twnfTer; According to the known processes, a cardboard, a wood fiber board or a wood chipboard is used which, in addition to the usual cellulose, contains 30% to 80% of a thermoplastic material in relation to its mass, such as polyethylene as a powder, fibers or emulsion , Polystyrene as powder or emulsion, acetate or vinyl chloroacetate, etc.

You start by bringing this cardboard to the softening temperature to preheat the thermoplastic material, after which it is brought into a pressing tool, where it is the desired Shape. Preheating is deemed necessary to not to slow down the manufacturing rate excessively.

This known method has the disadvantage that the after manufactured parts get a certain temperature sensitivity and a lack of creep resistance, which too Deformations, dimensional deviations, bending under load, etc. to lead. In addition, the mechanical properties not the best. According to an improvement of these known methods, the temperature resistance is added thermosetting resins increased during the manufacturing process of such plates. In the case of sewing processes, this has the disadvantage being a source of pollution and the amount introduced increases at the expense of significant water losses limit, while in the case of dry processes there is uneven distribution and in both cases the Distribution across the thickness of the material is incomplete.

The invention is based on these disadvantages and thus allow the creation of parts from hot-pressed or thermoformed cardboard which an improved heat resistance, a higher mechanical resistance / a good fire resistance, a great rigidity and possibly more

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have a new decorative appearance,

The inventive method for producing the parts from hot-pressed or when-formed cardboard consists in that A stack is introduced between the heated male and female tool parts, which consists of the overlay of:

- one or more heat-deformable sheets of paper or cardboard, which contain thermoplastic material in appropriate proportions;

- one or more components that give the product the Impart heat resistance and improved mechanical properties;

- one or more components that enable additional properties to be achieved such as fireproof impregnation, water impermeability, etc.

The fact that the cut is made by superimposing various Layers is produced, enables the achievement of the desired according to the selected work preparation Properties at a specific point in the thickness of the stack, Another benefit of this stack is the ability to easily an extra thickness to the desired one Place to generate.

In particular, it will be seen that the method enables practically dry sheets to be used, i.e. sheets of which Mass for example contains less than 5% water. Man thus avoids the formation of water or vapor bubbles inside the material, which otherwise would not fail to occur when the press tool is opened an elevated temperature, such as in the large pen

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Order of 17o ° C warmed. In addition, it becomes superfluous let the part dry in the mold.

It goes without saying that the practically dry stack according to the invention creates the following possibilities:

- a precise shape even with complex shapes due to the fact that the thermoplastic material (Polyethylene or other) the paper or cardboard sheets merge within the form and the material at low density, flowing so as to fill the details of the cavity of the mold;

- demoulding without waiting and without the risk of deformation because of the component that gives the heat resistance;

- the part is sufficiently hard, even if the final stiffness is only achieved after total networking and cooling of the achieved thermoplastic cardboard;

- The production in quick succession, since it is not necessary to cool the parts before demoulding nor let them dry in the mold.

The realization of the inventive Procedure take place in various practical modifications, particularly as to the composition of the component that makes it possible to increase the heat resistance deliver.

In particular, one can foresee

a) the addition of thermosetting resins or resins that retain their properties up to at least 1o5 ° C in powder

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form by spraying on one or more of the stack forming sheets of paper or cardboard.

These resins can also be used to blot blotch paper Asbestos, synthetic glass fiber (polyamide, acetate or Vj.nylsjure-chloride, Acrylic polyester) in the form of a mat or open-cell Impregnate foam. This Eogen must be in time be dry upon introduction to the pile.

This sheet only serves as a carrier for the resins; he can dissolve as the part is shaped.

b) The introduction of two materials that are mutually exclusive able to react to the temperature, with one material being a simple 'catalyst or a pore surface can that the formation of a foam at the correct Ftr »]] p enables. Example: Blocked Isocyanide and Polyester; the isocyanide is released at 150 ° C and can be used with the Polyesters react in such a way that they produce a polyurethane.

c) The introduction of heat-insensitive arches: You can put fibreboard between the boxes, even corrugated cardboard or rigid foams in the case of very thick ones Share Intermediate. In order to get these products into the right form, they will be pre-introduced cut into the stack in such a way that excessive thicknesses are avoided, which would otherwise be in the recessed sections would form.

d) The introduction of reinforcement components:

To give the part a special mechanical strength, you can insert a reinforcement made of gauze or fabric into the stack before the pressing process Is made up of materials such as metal, or even fiberglass

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plastic materials heat-resistant up to the increased softening point are.

Using a stack of sheets allows you to stood to insert arcs into the arrangement, which gave a special Have a cut, i.e. only affect certain areas of the finished part. This can therefore only be certain points are reinforced or thickened, which is what the methods of thermoforming or pressing known to date from cardboard do not allow.

Finally, the inventive method enables the creation of parts from cardboard (and thus cheaper parts), the. have the same properties of resistance to heat, moisture and mechanical stress, as if they were made entirely of more expensive materials like layered plastics.

For a better understanding of the invention, the following some embodiments for the practical implementation of the Method according to the invention, without thereby limiting the invention, described:

Example 1;

It layered four sheets of cardboard with a content of 4o% polyethylene fibers, 5o% cellulose fibers and 1o% Venylsäurechlorid preheated to 160 ⁰ C, to one another,

The outer arches weigh 25o g / m; the inner arches weigh

5oö g / m,

One encamped between the outer arches and the inner arches

symmetrical two sheets of fleece of 50 g / m, 100% impregnated

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ned with phenolic or melamine resin, as laminates; these Elbows are dry and preheated to 125 ° C.

As a variant, the impregnated arches can be replaced by a electrostatic spraying of ground phenolic resin

2
Replace powder with about 2oo g / m.

The whole stack is then pressed in a heated to 175 ° C Shape, whereby the thermally deformable material softens, deforms and allows the whole to be to flow in the finest pits as the thermosetting resin begins to harden.

Then you open the mold and take out the part that held by the thermosetting resin, remains in shape. The latter can, by the way, end its hardening outside the mold, which enables work to be carried out at a faster pace.

The pressure and the heat in the mold in the course of the shaping process:

the joining of the different layers of the stack by fusing the plastic material of the paper or Cardboard boxes;

- the cross-linking of the heat-resistant materials.

The mold has a punch-die distance of 1.8 mm, which enables the creation of parts of density close to 1.

It can be made from the heat-sealing eggshell of the polyethylene cardboard Take advantage of the part with a

Cover made of fabric or plush, applied to the reverse side of the polyethylene and previously in are thermally deformed to a shape corresponding to the part.

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The ornament and part are then preqewSrmt / in a cold form pressed against the other "

Example 2:

Layer four sheets of cardboard with a content of 4o% Polyethylene fibers and 60% cellulose fibers, preheated to I60 C, on top of each other,

The sweeter bows weigh 25o g / m, the two inner pens

2
5oo g / m, add from each side between the outer and

the inner pieces two blotting paper weights of 80 g / n, impregnated blocked to 100% with a mixture of 100 parts Polyisocyanite (Desmodur .AP) and 200 parts of Desmophen Poo (a polyalcohol). Then you put the whole thing in the mold at a temperature of 17o ° C.

The thermally deformable material softens, shapes and allows the whole thing to flow while at the same time the blocked phenolic urethane decomposes in polyisocyanite and reacts with Desmophen 600 to form a rigid polyurethane.

Example 3;

Four sheets of thermoplastic cardboard are layered with a content of 75% cellulose fibers and 75% as an emulsion precipitated polystyrene, preheated to 160 ° C,

2 other. The outer sheets weigh 25o g / m ', the two inner ones

2 2

Eighs 500 g / m. Then you slide between the 25o g / m 'sheets

and the 5oo g / m sheets are further sheets of cardboard with a

2
Modulus of elasticity of 300 g / m, which is varnished with a varnish based on vinyl acetate and cut to prevent wrinkles. Then you put the whole thing in the mold at a temperature of 150 ° C. The thermally deformable material forms, and so does the rigid cardboard

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is glued against each other and gives the part its heat stiffness,

Example 4:

You layer three sheets of thermoplastic cardboard with it "a content of 5o% thermon] astischeir fiber material and 5o% cellulose fibers, preheated to 16o C, on top of each other. All

2
Ptfgen weigh 25o g / m. Then nan pushes a cardboard box with a high modulus of elasticity between the first two sheets, which has been cut open to avoid wrinkles.

Then you put the whole thing in a granular form at a temperature of 15o C, the thermally deformable material forms to reflect the pattern of the mold, with the rigid cardboard giving the part strength. Because the part comes out like this requires spray painting to finish it off.

Example 5 ;

To create a part with a large flat area and an intricately shaped side, layer:

- a sheet of thermoplastic cardboard like the one

2
in example 1 with 5oo g / m, preheated,

- then place a box of 1.5 mm thick on the flat area;

- Place three brackets on the area to be deformed

2 warm thermoplastic cardboard of 5oo g / m in sand-

2 soft form between two fleeces, from 5oo g / m, impregnated with phenol;

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- Then, covering the whole thing, a preheated Eoqen out thermoplastic paperboard like the first.

The whole is pressed in a mold with a gap of 2.5 mm,

Example 6;

You can insert a thermoformable cardboard joint into the joint or several sheets of fleece or blotting paper, impregnated with Add refractory salts such as ammonium phosphate.

As a variant, these refractory salts can also be used directly Spray onto any thermally deformable cardboard. For example, one can apply electrostatic atomization of 20% ammonium phosphate to the amount by weight of the thermally deformable cardboard.

Example 7:

Part or all of the surface of the part you can introduce a reinforcement in the stack, which consists of less heat-sensitive materials, or at least has a softening point above 100 C. This can in particular be:

- a metallic wire mesh;

- a fiberglass mat;

- a sieve plate made of polyamide, polyester or just as certain Polypropylenes,

Example 8t

The fact that you have a complex stack under heat forms, allows the insertion of products that give the part a particular desired property, e.g.

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a sheet of polythene can be added to the stack to form a vapor barrier.

Patent claims /

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Claims (9)

Claims 1. \ A method of manufacturing parts from thermoformed cardboard by inserting a sheet between the heating male and female mold halves of a press, characterized in that the sheet consists of an assembled stack made up by stacking the following elements: - "several sheets of a thermally deformable paper or Carton; - one or more layers of heat-reacting raw materials or mixtures (mixtures) which, after exposure to temperature and recooling, are resins with a modulus of elasticity for tension and bending of more than 500 hbar, whereby this] ^ten stay. whereby these modulus values are maintained up to at least 1o5 C 2. The method according to claim 1, characterized in that the stacked Sheets of paper or cardboard are practically anhydrous, i.e. their mass contains, for example, less than 5% water, so that after thermoforming the part immediately without the need can be demolded by leaving it in the mold. 3. The method according to claim 1 or 2, characterized ge ken η ζ ei c h η e t that the resins by atomization be introduced onto one or more of the sheets of paper or cardboard forming the stack. 4. The method according to claim 1 or 2, characterized marked that in the stack at least 8 0 9 8 3 3/0901 ORIGINAL INSPECTED C-3552 / *. 2.1978 a sheet of blotting paper or fleece is inserted with crosslinkable resins is impregnated. 5. The method according to any one of the preceding claims, characterized in that at least one sheet is inserted into the stack, which sheet on ledJalich the area of interest on the surface of the stack is cut, namely those zones that result in depressions on the finished part. 6. The method according to any one of the preceding claims, characterized in that a reinforcing element is inserted into the stack, which consists of a Piece of gauze, tissue, or a perforated sheet is made of a material such as metal, fiberglass, or plastics Resistant to heat up to the high point of softening is. 7. The method according to any one of the preceding claims, characterized in that in the Stack at least one layer of refractory salts such as ammonium phosphate is inserted using this insertion by atomizing the salts on a sheet of thermally deformable cardboard or by inserting an impregnated A sheet of blotting paper or fleece is done. 8. The method according to any one of the preceding claims, characterized in that daP is a sub-area the surface of the stack by an opposite • Heat less sensitive material such as cardboard or a fiberboard is replaced, which is the homoeneity of the part ensuring connection thereupon by fusing the thermoplastic material with the Thermally deformable cardboard takes place when the stack is heated in the mold. 809833/0901 C 3552 / «,? ₌ 1978 9. The method according to one of the preceding addresses, characterized in that in the Stack a sheet of polyethylene to form a vapor barrier is inserted. 1o. Part of thermoformed cardboard produced by a method of the preceding claims, characterized in that characterized in that it has creep resistance, little sensitive to water and water vapor and is able to withstand a temperature of 100 ° C. for 24 hours without deformation. «52 / f.2.197e 809 8 33/0901