DE2314690A1 - METHOD FOR GENERATING A FLEXIBLE EXTERNAL SKIN FROM PLASTICIZED POLYVENYL CHLORIDE - Google Patents

Description

Deutsche ITT Industries GmbH March 20, 1973

78 Freiburg im Breisgau

P 68 258 - A / 72 ZL / c

L. Bertrandi - 1

Process for the production of a flexible outer skin from plasticized polyvinyl chloride

The present invention relates to a method of production a flexible outer skin made of plasticized polyvinyl chloride (PVC).

A pliable outer skin made of plastic is mainly used for upholstered Objects desired. The most common example of such padded items are various pillows and backrests, in particular for vehicles. In addition, padded panels are often attached to the vehicle interior for aesthetic or safety reasons. Such panels generally comprise a flexible outer skin made of suitable plastic.

It is known to provide padding for objects of this type using foam rubber or a plastically deformable material such as polyurethane. The manufacturing processes differ according to the respective requirements.

Such coverings for cushions and backrests from a flexible Plastic covers usually consist of PVC or polyurethane layers, which are based on a fabric base (e.g. made of nylon, jersey or building material) are applied and with which natural skins to be imitated.

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The components of the fairing, however, need to be cut to size and subsequently sewn or glued together, which causes high labor costs. In addition, the strength of the cladding is increased by the seams decreased.

Another method involves coating a base material with in Heat moldable resin under vacuum, which must already be embossed on its surface in order to achieve an imitation of leather. However, the outer skin obtained in this way is relatively stiff and holds one not withstand constant use. In addition, there is sharp Deformations, as they are often required, there is a risk of excessive elongation in places, as a result of which strength and embossing are lost. It is also not possible in this process to use an outer skin with inserts, i.e. with flexible inserts, e.g. made of fabric on the front.

Another known technique is so-called "slush molding". A mold is filled with Polyviny! Plastisol; a plastisol layer adheres inside the mold, which is then cured at temperatures of 170 ° C to 190 ⁰ C during emptying after a short heating. The viscosity of the plastisol must be very low (3,000 - 8,000 centipoise) so that, on the one hand, the liquid mass fills every corner of the mold without the formation of air bubbles and, on the other hand, the mold can be emptied quickly. This requires a lot of plasticizer, which can migrate to the surface of the finished product. In addition, even if the mold is emptied as quickly as possible and if it is immediately introduced into an oven, it will flow away and form "bases". The consequence of this is that the outer skin is in some places inappropriately thick and thus stiff and, on the other hand, has places of insufficient thickness, which reduce the strength of the outer skin. The production of an outer skin with inlays is also not possible with this method.

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Finally, it is known to use an outer skin made of polyurethane of two polyurethane components. If these two components hit the surface of the with a double spray gun The shape of the outer skin to be achieved is sprayed, they react almost instantly. The result is a soft, adaptable one Outer skin. The breaking and tearing strength of such outer skins are relatively low, generally lower than with corresponding ones PYC outer skins. It is also the case with all polyurethane mixtures difficult and costly, apart from black to achieve lightfast, colourfast and non-aging colors.

The spraying must also take place in a reasonably dry atmosphere, since moisture easily causes damage to the surface of the outer skin.

The present invention is based on the object of a manufacturing method for outer skins made of plasticized polyvinyl chloride find, in which the above-mentioned inadequacies are avoided and with the outer skins in any desired color, multi-colored as well as provided with inlays can be achieved. Further tasks and gate parts are explained with reference to the following description.

This object is achieved according to the invention in that the layer is achieved by spraying Plastigel and. this at the time of its use has a viscosity of 20,000 to 50,000 cps, and the mold has a temperature between room temperature and 100 ⁰ C and that the viscosity of the plastigel after 48 hours rest at least I4O.OOO cps.

The drawings are discussed below.

309843 / 10S4

Show it

FIG. 1 a corresponding to the present method

Viscosity diagram of a plastic gel, FIG. 2 a schematic section through a mold.

for an embodiment according to

Invention is used.

The viscosity values of 20,000 to 50,000 cps given above relate to the "instant of use". This condition is shown in Figure 1 at point A, where, for example, a plastigel at 21 degrees Celsius has a viscosity of 50,000 cps. While the plastic gel was left at the same temperature for 48 hours its viscosity increases and reaches at least 140 * 000 cps; around Vigorous stirring is sufficient to bring it back down to 50,000 cps. These changes in viscosity (thixotropy) are shown by the vertical line A-B of Figure 1. ·

In practical use, point A corresponds to the properties of the PVC plastic gel in the reservoir of a spray gun during the implementation of the present proceedings. Venn the capacity of the container is comparatively large in relation to the delivery amount, it is advantageous to provide an agitator in the tank to to prevent an undesired subsequent increase in viscosity. ·

In addition, the curve C in Figure 1 shows that when heated, the Viscosity gradually drops to a minimum and then _ increases rapidly to the hardening point of the plastic gel. As a result, however, even if a plastic gel is in a condition appropriate Point A is so viscous that it is not immediately after spraying a layer of, for example, 2 or 3 millimeters thick there is a flow on the form, a limited flow occurs, if when heating the mold for the purpose of gelation and hardening that

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Plastigel sprayed on in a thicker layer passes through temperatures, which correspond to the maximum viscosity. By the invention This risk is avoided by keeping the temperature of the mold constant - also during the spraying process - significantly is higher, preferably between 60 and 100 C. TJm to achieve this, the skilled person may seem obvious to him Use means such as heating resistors embedded in the mold, jackets for circulating hot liquid, and the like. Has the If the heat capacity is large enough, it can be preheated to the desired temperature in an oven. The saved Heat prevents a major drop in temperature during spraying.

The plastigel used must be a reasonable, limited percentage Contain portion of plasticizing agent so that exudation of the surface of the finished outer skin can be prevented. 40 to 60 parts by weight of plasticizer for 100 parts by weight of resin (PVC) are usually adequate. The viscosity increases with the increased molecular weight of the dispersed PVC} this is known to those of ordinary skill in the art. Plastigel also contains components for gel formation such as betonite or silica gel, which increase the viscosity of the plastic gel. By matching these factors as well as the nature and amount of the stabilizer, a suitable one for the process according to the invention can be used without difficulty Plastigel are created. If necessary, an appropriate amount of viscosity-limiting agent can be added. In in each case there will be dye, pigment and possibly other typical components of polyvinyl plastigel.

A plasticizing agent with low evaporation capacity is preferred used, such as dioctyl adipate (DOA), dioctyl sebacate (DOS), diisodecyl adipate (DIDA) and trimellytate.

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In addition to this, 10 parts by weight of a plasticizer can be used such as epoxy softeners.

The high viscosity of Plastigel as used in connection ¹ with the present procedure is important for the spray equipment. Above all, the operating tank of the spray gun must be pressure-resistant so that it can withstand about 4 to 6 atmospheres; compressed air must be fed into the gun at this pressure. Under these conditions, when using a nozzle 2 to 2.5 millimeters in diameter, the optimal spray distance is about 80 centimeters from the surface of the mold.

The effective surface of the mold is preferably made of copper, Nickel or nickel-plated copper. Patterns are usually engraved into the surface, making the texture more natural as a negative To imitate skins.

effective

Position 10 in FIG. 2 represents a shape whose concave surface 12 corresponds to the outer surface of the outer skin for seat cushions. This surface can be kept at the same temperature by the flow of oil or another heat fluid in the channel 14.

It is assumed that an outer skin is provided with an insert should, which has a rectangular fabric strip 15 that extends from front to back over the outer skin. For this purpose * the strip 15 on the central surface 16 across the width of the mold placed and fixed to the surface by a pressing member, not shown 12 held in shape. This pressing member presses the strip 15 only within the lines 1ό · and 16 "so that the opposite Edges 15 'and 15 "of, for example, 4 to 5 millimeters Width remain uncovered. The temperature of the mold is

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within the range specified above χ degrees Celsius. Sann will open the uncovered areas 18 and 20 of the surface 12 of the mold and on the edges 15 'and 15 "of the strip 15 a PVC plastic gel of the previous mentioned type sprayed, so that a coherent layer 22 of, for example, 1 to 1.5 millimeters thick is formed. A quick one

2
Spraying at 0.3 m per minute, for example, is recommended.

A suitable plastic gel contains the following components by weight:

High molecular weight PVC DOS

Tr ime lly would do stabilizer epoxy plasticizer Eitan-Oxyd gelling agent (Betonite) viscosity reducer

The initial viscosity of this plastic gel is approx. 35,000 cpsj after 24 hours it reaches about 160,000 cps, but drops again to 30,000 to 35,000 after 15 minutes of stirring. The plastic gel is used for the latter viscosity.

This plastic gel is preferably prepared by separately forming a gel dispersion in 10 parts out of a total of 15 parts DOS and a second dispersion, which contains all the remaining ingredients and the remaining 5 parts DOS. The preparation takes place in containers with suitable agitators, preferably screw agitators (with a high tendon effect). Both dispersions are then completely mixed together.

If the fabric strip 15 serves only as an ornament and not as a "reinforcing ^{element 11 of} the outer skin, the pressing member is after the

100 Shares 15th η 35 11 . 2. 5 '- 3 « CVl α CM π CVI η

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previously described work is removed and the entire strip is evenly sprayed over.

The gelation and hardening of the layer 22 take place in a known manner Way by heating. For example, heating for two minutes at 300 to 320 degrees Celsius is sufficient for complete hardening. Each cooling the outer skin obtained is peeled off the mold.

Instead of the fabric strip 15, a corresponding PVC insert can be used, which is given a different color than the layer 22 on the surfaces 18 and 20 of the mold. This can be achieved using the concealment technique. For example, the areas 18 and are covered, while the layer 22 is produced by spraying the area 16 with a plastic gel in the desired color and under the conditions described above. If the surfaces 18 and 20 are uncovered, the layer 22 is applied to these surfaces by spraying plastigel of a different color, while the material applied to the surface 6 is covered.

The method is not limited to the exemplary embodiment, such as it is shown in the drawing; multiple deposits can also be used can be achieved in different forms.

The simplest application is an outer skin without any insert. In this case, the entire surface 12 of the outer skin is in accordance with the procedure described above. Plastigel sprayed.

A particular advantage of the method according to the invention lies in the Possibility to achieve an outer skin with built-in reinforcement. For this purpose, the spraying takes place in two phases. In the the resin layer 22 applied to the first phase corresponds - independently of whether an insert I5 is provided or not - only a part

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the total planned strength. This layer is covered with a latticework or covered with fabric with reinforcing fibers, which easily adheres to the already sprayed resin. Then the education the layer 22 continued by spraying the plastic gel and the latticework is thus embedded in the finished layer. As a reinforcing one Latticework, for example, gauze made from either natural or synthetic fibers can be used to suit the curing conditions the layer 22 withstands.

Is a complete embedding of the reinforcing fibers in the resin layer 22 not required, this can be applied in one operation and the fibers (in the form of gauze or randomly scattered) can be placed on the surface of the freshly formed coating, so that the latter adhere to said surface; when using short fibers applied by a blowing process an excess of fibers can be removed, for example by brushing off.

If the outer skin is to be stuffed with synthetic foam, it is advantageous to make this padding while the outer skin is still on the mold 10, that is, before it is removed from it will. This can be done in a known manner by pouring a certain amount of a foam-forming polyurethane mixture into the mold 10, which are closed with a lid and - if necessary - introduced into an oven or through the heating jacket 14 is heated at the desired temperature.

The manufacturing process described makes them skin-friendly Outer skins achieved such an excellent appearance as that with PVC-Plastigel was previously not possible.

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Typical strength values are:

Maximum tensile stress Maximum elongation Maximum tear strength

75 .5 Kg / cm 500 5 Kg / cm

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Claims (8)

. 23H690 Deutsche ITT Industries GmbH 20 March 1973 Freiburg in Breisgau P 68 258 - A / 72 ZL / c L. Bertrandi - 1 Claims Process for the production of outer skins from plasticized polyvinyl chloride, in which one of the outer surface of the outer skin corresponding shape with a liquid layer of PVC dispersion and Plasticizing agent is coated and this layer is brought to gel formation and hardening by heating, characterized in that the layer (22) is sprayed on with plastigel is achieved and this has a viscosity of 20,000 to 50,000 cps at the time of its use and the mold has a temperature between room temperature and 100 C, and that the viscosity of the plastic gel after 48 hours of rest is at least 140,000 cps amounts to. 2. The method according to claim 1, characterized in that that the viscosity of the plastic gel at the time of its use 30,000 to 45,000 cps. 3 · Method according to claim 1 or 2, characterized in that it is marked net that the temperature of the surface (12) of the mold (1O) is at least 60 ° C during spraying. - 12 - 3098A3 / 10B4 2374690 4. Method according to claims 1 to 3 for the production of outer skins with fabric inserts on the surface, marked through the following production process: A) Pressing the insert (15) on the corresponding surface (16) B) Spraying the plastic gel onto the edges (15 '»15") of the insert (15) and the remaining surfaces (18, 20) of the surface (12) to form the layer (22). '' 5. The method according to claim 4 »characterized in that that the slotted insert (15) is sprayed. 6. The method according to claim 1 to 3 for the production of a two-tone Outer skin, characterized by the following manufacturing process: A) covering a first area (1.6) of the surface (12) of the mold (10); '* * ■ · ._ - B) Formation of the layer (22) on the other surfaces (18, 20) of the Surface (12) through a plastic gel in the desired color; C) clearing the first area (16)> ' D) Forming the layer (22) using Plastigel in one other color you want. 7. The method according to claim 1 or one of the following, characterized by the following manufacturing process: A) forming the layer (22) to a part of the intended thickness; B) Applying a partial jacket made of reinforcing latticework Fibers; C) Formation of the complete layer (22) by spraying the plastic gel through and onto the latticework for embedding the same in the finished coat. - 13 - 309843/1054 8. The method according to claims 1 to 6 for the preparation of a by Fabric fiber reinforced outer skin, thus marked e t that the fibers are laid on the surface of the freshly formed resin layer. 309843/1064 e e r e i t e