EP0758413B2 - Binding compound for the production of non-woven material - Google Patents

Abstract

PCT No. PCT/EP95/01643 Sec. 371 Date Jan. 28, 1997 Sec. 102(e) Date Jan. 28, 1997 PCT Filed Apr. 29, 1995 PCT Pub. No. WO95/30034 PCT Pub. Date Nov. 9, 1995A mixture for producing moulded articles from fibre mats containing a) 20 to 45 wt. % of a powdered binder mixture, b) 80 to 55 w. % of organic and/or inorganic fibres, characterised in that the powdered binder mixture contains a1) 30 to 90 wt. % of phenol resin and a2) 70 to 10 wt. % of powder coating waste and moulded articles produced therefrom.

Description

The invention relates to a special binder mixture for the production of nonwovens, as well Process for their production. Furthermore, the made from the nonwovens and binders Prepregs described.

In industry, molded parts are based on Nonwoven fabrics worth spreading. It is about Nonwovens made of various types of fiber with binders can be mixed. From these non-woven fabrics intermediate products can then be produced, the so-called Prepregs, which are then matched with the appropriate Processing tools shaped, cured and if necessary, assembled. It is the same possible directly from the fibers. and the binder powders to produce the corresponding Fa continuous non-woven goods. These molded parts or planware are widely used Use. In the automotive industry these products for example as molded parts, e.g. as Insulation for hoods, wheel arches or trunk insulation used. Another area of application is the use as planware, e.g. as insulation material in Washing machines, tumble dryers or loudspeakers, in sound absorbing walls. You can with other coatings, e.g. by flocking, Laminating or laminating. This one optically stable and decorative surface coating equipped molded parts or sheet parts then e.g. as a door panel, as a parcel shelf or used as a ceiling covering in the automotive industry become.

The methods of making non-woven fabrics or to mix these nonwovens with binder powder are known. The fiber material, e.g. B. in a fiber mixing chamber, homogenized, and on a conveyor belt laid as a loose fiber layer.

The binder mixture is then applied to the fiber material e.g. with metering rollers or vibrating troughs applied. Then the fiber / binder mixture in a closed system using a Air flow swirled and mixed homogeneously. The homogeneous Mixture of fiber and binder powder filed into an endless fleece. The components of this Mixtures can be done either by gentle heating and then cooling glued together be, whereby the prepregs arise or it is manufactured sheet or roll goods that are already complete is cured. The prepregs are not yet finally cured, but are stable in storage. To processing into the final form, these will be Prepregs under the influence of heat at up to 210 ° C thermally cross-linked, whereby three-dimensional thermosetting Moldings are obtained.

The requirements placed on these molded parts surface structure and color are variable, however, it must be at elevated temperature or Long-term exposure an adequate mechanical Stability. However, for their production a binder can be used that the used Nonwovens bond so well together, that after the final molding and curing stable molded part is obtained. The currently used Binders are relatively expensive. They are also phenolic resins hazardous to health. The industry is strong interested in reducing costs. Especially with the molded parts described above, such as the insulation materials for bonnets, wheel arches or insulation materials is looking for alternatives to the expensive, technical pure resins wanted.

JP-A-55-1 48266 describes a molded part Made of nonwoven fabric using synthetic Fibers, powder curl waste and resin made becomes.

The object of the present invention is a Binder mixture for the production of nonwoven molded parts to provide in which a significant Part of the commonly used pure resins can be replaced by other components that nevertheless to stable, reactive binder mixtures which leads to the production of nonwoven prepregs or cured nonwoven fabrics are suitable. A Another task is to reduce the proportion of harmful Lower substances. These binder mixtures must meet the usual requirements the manufacture of nonwoven molded parts and this results in hardened, stable molded parts, which adapted to the different applications can be.

a) 20 bis 45 Gew.-% einer pulverförmigen Bindemittelmischung, enthaltend

a₁) 30 bis 90 Gew.-% Phenolharz und

a₂) 70 bis 10 Gew.-% Pulverlackabfälle

b) 80 bis 55 Gew.-% organischer und/oder anorganischer Fasern, die dadurch gekennzeichnet ist, daß die Komponente a₂) aus Abfällen von noch nicht vernetzten Pulverlacken auf der Basis von Epoxid-, Polyester-, Polyurethan-und/oder Acrylatharzen mit reaktiven Gruppen besteht,

wobei die Pulverlackabfälle korngrößen zwischen 10 und 60 µm aufweisen.It has been shown that this object is achieved by a mixture for producing molded parts from nonwoven fabrics containing

a) containing 20 to 45% by weight of a powdered binder mixture

a ₁ ) 30 to 90 wt .-% phenolic resin and

a ₂ ) 70 to 10 wt .-% powder coating waste

b) 80 to 55% by weight of organic and / or inorganic fibers, which is characterized in that component a ₂ ) consists of wastes from not yet crosslinked powder coatings based on epoxy, polyester, polyurethane and / or acrylate resins with reactive groups,

the powder coating waste having grain sizes between 10 and 60 microns.

In the paint industry are increasing Powder coatings used. These have the advantage that a solvent-free application process is possible. In order to can significantly reduce emissions to the environment become. The application process for powder coatings have the disadvantage, however, that a significant proportion the powder does not get onto the object to be coated. These powders are so-called in the paint booth Overspray collected. Powders are in theirs Grain size distribution and sensitive in purity. Therefore this overspray has to be disposed of as waste. At the last stage of paint powder production the crushed paint powder extrudates are ground. During this grinding process fine dust falls on the disruptive works in the painting process. That's why this one Dust largely removed. This dust is difficult reprocess and must be disposed of as special waste become.

For those that can be used for the various nonwovens Fibers are woven, matted or blended fibers. The fibers consist of the known materials, e.g. natural, organic and inorganic fibers. Examples of this are glass fibers, Rock wool fibers, polyester fibers, acrylic resin fibers, Polyolefin fibers, wolf fibers, cotton fibers, Flax fibers or the like. Textile fibers are preferred, especially cotton fibers, e.g. fiber waste from the textile industry. These fibers or the nonwovens made from them are known in the industry. The processes with which they are produced are also known can be. This can be done, for example, by Weaving or matting happen. The emerging Nonwovens are said to be essentially dry, they can optionally be impregnated with additives.

In the mixtures in the invention usable phenolic resins are the usual reactive phenolic resins that have long been in the Industry are known. For example, these are reactive, Non-crosslinked, powdery, containing OH groups Phenolic resins. Such resins are already used for the production of molded parts from nonwovens. For example, phenolic resins based of phenol and formaldehyde, as for example are known as resols or novolaks. As possible crosslinkers, these resins can be condensation products of formaldehyde included.

These resins are already far in the literature described, e.g. in R.N. Shreve, The Chemical Process Industries ", Chapt. Plastics, 1945 and commercial available. Further phenolic resins are also described in DE-A-38 33 656, EP-A-0 369 539 and EP-A-0 376 432. Phenolic resins from are particularly preferred Novolake type.

The reactivity of the phenolic resins will also determined by the type and amount of the crosslinking agent used. A crosslinking reaction generally occurs between 120 ° C and 222 ° C.

The resins are generally in powder form in front. Suitable grain sizes are between, for example 0.1 and 500 µm, preferably between 2 and 150 µm, particularly preferably between 10 and 60 µm.

The grain sizes of the powder coating waste used lie between 10 and 60 µm. Are powder coating waste used, their grain sizes too small for the desired application verbakken, it is possible to have larger grain sizes to get the particles.

The powder coating waste which can be used according to the invention are those of the usual known powder coatings based on epoxy resins, polyester resins Polyurethane resins or acrylic resins. This powder coating waste fall out as overspray, for example Paint booths or as batches during manufacturing the powder coatings. It is also possible that filter dust be collected and used, as well Residues from grinding the powder.

Those which can be used in the mixture according to the invention Powder coating waste is not yet networked. They contain reactive groups such as carboxyl groups, Epoxy groups, hydroxyl groups, amino groups, Amide groups or isocyanate derivatives. This can react with each other when heated. The Crosslinking temperature depends on their basic structure from. They are usually between 120 and 220 ° C. Powder coatings with cross-linking temperatures above 180 ° C are preferably added only in small amounts, in order to cure even at curing temperatures Moldings of about 160 ° C as complete as possible Crosslinking of the binder mixture used to reach. In addition, at high crosslinking temperatures, especially when using nonwoven from plastic fibers there is a risk that the Fibers are broken down, leading to a decrease in stability of the molding leads. It is preferred that the Have paint powder / cross-linking temperatures below 160 ° C.

The epoxy powder coating materials which can be used according to the invention contain epoxy resins as the main binder component. These often crosslink via hydroxyl groups especially those containing amide or amine groups Harder.

Furthermore, e.g. Polyester powder coatings are used in which the main binder component are polyesters containing carboxyl groups. As in Proportion of existing crosslinkers are, for example, epoxy groups Crosslinking agents or those containing amino or amide groups Known crosslinker. It is common. that each of the crosslinkers are more functional than that Main binder component. Become epoxy / polyester mixed powder used, so-called hybrid systems, are approximately equal proportions of Polyesters or epoxy resins.

Polyurethane powder coatings are based on those containing hydroxyl groups Polyesters that reversibly blocked Polyisocyanates, e.g. with known capping agents protected like caprolactam or ketoxime are able to cross-link or which are present as urethdione.

Powder coatings of the acrylate type are general Mixtures of two or more acrylic resins that functional groups such as epoxy groups, carboxyl groups, Hydroxyl groups or isocyanate groups contain. Here are the reacting with each other Groups divided into different molecules.

These binder powders are e.g. in S.T. Harris, "The Technology of Powder Coatings", 1976 or in THERE. Bate, "The Science of Powder Coatings," Vol I, 1990 described.

It can be colorless or pigmented powder coatings are used, the usual pigments known inorganic or organic color pigments possible are. It is also possible that effect pigments e.g. Metallic pigments incorporated into the powder are. A separation by color is not necessary. The grain fineness of the powder is not essential, care should only be taken that for the Preparation of the binder mixture in general Average sample of the different powder residues is used. This leads to better mixing behavior and more constant manufacturing the binder mixture.

The powder coatings can be used individually. In order to achieve a composition of the binder mixture a) which is as constant as possible, it is preferred that a mixture of epoxy powders and polyester powder is present as a ₂ ). Up to 60% by weight of a ₂ ), preferably up to 30%, can optionally be replaced by polyurethane powder and / or polyacrylate powder. It is possible to directly produce a mixture a ₂ ) within the desired weight ratios and to store it. Another possible way of working is that the various powder coating components are stored separately according to the chemical types described above and are only mixed with the phenolic resins before further processing. Within these chemical types, the resulting materials are mixed homogeneously, ie a sample is mixed with the composition and pigmentation in grain size distribution. The quantities required in each case are then mixed together from the mixtures of the resulting powder coating binders in the preparation of the binder powders a). If necessary, it is possible to introduce further additional crosslinkers into the binder mixture.

The powder coating waste which can be used according to the invention are available as ground powders. Possibly it is necessary to use proportions of the binder in coarser form are previously available on a suitable Grind grain size. This can be used for the phenolic resins specified order of magnitude.

If necessary, customary additives or additives can be added together with the powders. These can be, for example, catalysts, accelerators or flame retardants. As catalysts, tin compounds are preferably used as dibutyltin dilaurate, carboxylic acid salts such as lithium benzoate, quaternary ammonium compounds such as tetrabutylammonium bromide, cetyltrimethylammonium bromide, benzyltrimethylammonium chloride, benzyltriethylammonium chloride or tetramethylammonium chloride or tertiary amines such as triisopropylamine or methylimidazole. Suitable accelerators and crosslinkers are, for example, basic compounds containing epoxy groups, such as triglycidyl isocyanurates, glycolurils, dicyandiamide or beta-hydroxylamides. These additives can be added individually as powdery substances. They can also be introduced as a masterbatch mixed with binder proportions or they are metered in as a mixture with the binder powder a ₁ ).

Flame retardant substances can also be introduced. These are the usual known substances that are contained in fire protection coatings. Examples of such compounds are borates such as sodium borate; Phosphates such as ammonium phosphate or sodium phosphate; Aluminum hydroxides or oxides; other suitable compounds are, for example, heavy metal-containing compounds such as tin oxide compounds or perbrominated or perchlorinated compounds such as tetrabromophenol. However, heavy metal-free and halogen-free flame retardant substances should preferably be used. These flame retardant substances are available as a powder. They can be introduced via a separate masterbatch or they are metered in via the binder powders a ₁ ) or a ₂ ) in each case as a homogeneous mixture with the powder component.

Pigments can also be introduced into the binder mixture a). In general, however, it is preferred not to introduce any additional pigments, but only to use the fibrous fillers of the nonwoven fabric or the pigments contained in the powder coatings a ₂ ).

Another object of the present invention are molded parts by molding and partial or fully harden the above Mixture made of fibers and binders can be. The mixtures are made of fibers and binders are only partially hardened, the so-called Get prepregs which are then in another Processing step by heating to its final Formed and fully cured can. If the mixture is to be fully cured, so they are in a known manner in the appropriate shape and in the form for each Binder mixture suitable crosslinking temperatures hardened.

The prepreg formed before curing or the finished molding generally contains 55 up to 80% by weight of fibers and 20 to 45% by weight of the binder mixture.

In a preferred embodiment there is the binder mixture of 45 to 70 wt .-% phenolic resins and 30 to 55% by weight of powder coating binder. The Additives and additives described above can in an amount of up to 20% by weight, preferably up to 15 % By weight may be included, the sum of the individual Components gives 100 wt .-%. Only one type of powder coating can be used or a mixture of several used are preferred, however, a mixture of polyester and epoxy resins. It is further preferred that the ratio of polyester powder to epoxy powder 0.2: 1 to 7: 1, preferably 0.8: 1 to 3: 1. It should however, be careful when choosing powder coating waste be that these are a sufficient number of own reactive groups.

For the production of the invention The binder mixtures are homogenized in molded parts and together with any additives the nonwoven applied. This happens through known ones Method. The mixture of binders becomes even distributed on the nonwoven fabric and after that, if necessary a heating step was carried out become. The result is that the binder particles on soften the surface and become firmly attached to the nonwoven connect. So-called Prepregs, the storage-stable, still deformable sheet-like Nonwovens result. It is important to ensure that there is no complete networking yet, but the Binder in the heat can be deformed even further as well as flow and network.

The binder mixture a), the prepregs and also the hardened moldings have a reduced proportion of free phenols or formaldehyde. This reduces the risk posed by these harmful substances. The molded parts according to the invention can then be produced from the prepregs obtained in this way. This is done according to known methods such as shaping and / or laminating, making up the prepregs. After the prepregs have been brought into a suitable shape, they are crosslinked by applying pressure and heat. Crosslinking takes place at temperatures from 140 to 200 ° C. The time can be between 10 to 500 seconds, preferably less than 120 seconds. It is chosen depending on the phenolic resin a ₁ ) used. The binder powder melts and flows, whereby the fibers are at least partially embedded and the resins are chemically crosslinked. This creates a hardened thermoset material. Depending on the amount of material used and the pressure used, the moldings may contain parts of voids. The density of the molded parts can be between 50 to 1000 kg / m ³ . It depends on the amount and type of fibers and binders. The resulting molded parts have various advantages, such as good heat insulation, dimensional stability up to 130 ° C, good sound insulation, good flexural strength, are physiologically harmless and have a moisture-regulating effect, can be easily processed.

These molded parts can still be coated or they serve as carriers for other components. The can happen, for example, that together with the networking and shaping of the molded parts Film is applied to the surface of the molded part. This is firmly attached to the chemical reaction Surface bound. It is also possible through subsequent lamination and lamination of foils to achieve special coating of the surface. Processes for laminating molded parts are in widely used in industry. You can after State of the art.

It is also possible to change the surface of the Flocking molded parts. This is done using adhesives short fibers essentially perpendicular to the Brought surface, which is then a dense and soft Cause surface. Flocking procedures are also known. The from the invention Mass-produced molded parts can optionally be painted. It can all known coating agents are used that are known in the industry are. After heating, smooth, shiny surfaces emerge Coatings.

The coated in this way Molded parts have an attractive decorative effect. Depending on the selection of the method, smooth, soft, grained or even chemical resistant coated Surfaces are obtained. By additional Use of flame retardant additives can also be obtained molded parts that are against fire are resistant.

The molded parts obtained in this way can be of various Industrial areas are used. In particular can be used in the automotive industry e.g. as interior trim parts for automotive interiors or sound and heat protection parts. Furthermore, the binder mixtures can be used as resins can be used in linings for clutches. As well can use these resins for mold making in the foundry industry be used. The resulting molded parts are characterized by great stability and can shaped in a variety of ways. By the addition of various additives or by the Surface coating it is possible in different Application areas.

example 1

It becomes a mixture of 48 g of a commercially available powdered phenolic resin (Novolak with Hexamethylenetetramine) with an average Grain size of 35 µm and a cross-linking temperature of 150 ° C and 3.4 g of a pigmented powder coating based on commercially available epoxy resin powder, as well 10.2 g of a pigmented powder coating based of polyester resins, the powder coatings containing a pigment of 13% each, in a commercially available Mixing unit homogenized. (Polyester: epoxy = 3: 1, 20% powder coating)

The mixture can be used without further loss of reactivity be stored for a long time.

Example 2

It becomes analogous to 70 g of a phenolic resin Example 1 a previously homogenized mixture 15.8 g of an epoxy resin powder coating and 14.2 g of one Polyester powder coating, both unpigmented, given. (Polyester: epoxy = 0.9: 1, 30% powder coating).

20 g of a flame retardant are added to this mixture based on ammonium phosphate, melamine borate and aluminum hydroxide and placed on one usual mixing unit homogenized. there can if necessary by the energy of the mixture slight warming up to 40 ° C may occur. It should be there however no caking of the different powder parts respectively.

Example 3

It becomes 60 g of a phenolic resin Example 1 21 g of a pigmented 10% with barium sulfate Given and homogenized epoxy resin powder. Thereafter, 30.1 g of a non-pigmented polyester powder coating admixed and 0.4 g tetrabutylammonium bromide, and the whole mixture will then homogenized thoroughly. (Polyester: epoxy = 1.6: 1, 45% powder coating)

The mixture has a long shelf life.

Be as polyester powder or epoxy powder Filter dusts used in the manufacture of powder coatings. These are homogenized and then one Average sample of these proportions used in the examples.

The powders of Examples 1 to 3 become with a nonwoven fabric produced in a known manner, that contains over 80% cotton fibers, prepregs manufactured. For this, the non-woven fabrics are through mechanical movement homogeneous with the binder powder mixed and passed through a heat channel (approx. 2 - 3 min., 80 ° C - 100 ° C). This creates storage-stable prepregs, in which resin and fiber are combined have connected.

The prepregs can be made differently according to size and resin / fiber content. The bulk density is between 25 and 75 kg / m ³ depending on the application.

Molded parts are produced from these prepregs. The prepregs are cut in one Press brought into the intended form and there 100 seconds to 110 seconds at temperatures between 140 ° C and 160 ° C hardened. After curing thermoset thermally stable Products. The density can vary over the amount of prepreg or influenced by the set pressure. The resulting cross-linked molded parts can be flocked in a known manner or they are laminated with foils.

The molded parts thus obtained have an optical homogeneous surface, they are dimensionally stable and have only a low content of free phenol or formaldehyde.

Claims (7)

1. Mixture for manufacturing mouldings from nonwoven fabrics, containing

   a) 20 to 45 wt % of a powdery binder mixture, containing

   a₁) 30 to 90 wt % of phenolic resin and

   a₂) 70 to 10 wt % of powder coating wastes

   b) 80 to 55 wt % of organic and/or inorganic fibres, characterised in that component a₂) consists of wastes of not yet crosslinked powder coatings based on epoxy, polyester, polyurethane and/or acrylate resins with reactive groups, wherein the particle sizes of the powder coating wastes are between 10 and 60 µm.
2. Mixture according to claim 1, characterised in that it contains further additives and additional substances.
3. Mixture according to one of claims 1 or 2, characterised in that there are used as powder coating wastes epoxy resin and polyester resin in a ratio of 1 : 0.2 to 1 : 7.
4. Mixture according to one of claims 1 to 3, characterised in that at least one flame retardant is added as an additive.
5. Moulding obtained by shaping out and partial or complete hardening of a mixture according to one of claims 1 to 4.
6. Use of the mixtures according to one of claims 1 to 4 for manufacturing mouldings from nonwoven fabrics.
7. Use of the mixtures according to one of claims 1 to 4 for the binding of nonwoven fabrics.