WO2013144132A1

WO2013144132A1 - Method for producing polyamide molded bodies from a polymerizable composition by means of a rotational molding process

Info

Publication number: WO2013144132A1
Application number: PCT/EP2013/056378
Authority: WO
Inventors: Silke Biedasek; Philippe Desbois
Original assignee: Basf Se
Priority date: 2012-03-27
Filing date: 2013-03-26
Publication date: 2013-10-03
Also published as: KR20140139580A; JP2015514831A; CN104245268A; EP2830844A1

Abstract

The invention relates to a method for producing polyamide molded bodies, wherein a polymerizable composition containing lactam is subjected to a rotational molding process.

Description

Process for the production of polyamide moldings from a polymerizable composition by means of rotary melting

description

The present invention relates to a process for the production of polyamide molded articles, in which a lactam-containing polymerizable composition is subjected to a rotary melting process. Thermoset polymers such as polyurethanes or polyesters, once cured, can no longer change their shape. Unlike the thermoplastic polymers where the process of heating, shaping and cooling is reversible. Among the industrially most commonly used thermoplastic polymers include in addition to the polyamides and polyethylene, polypropylene, polycarbonate, etc.

The production of polyamides currently takes place essentially by condensation of dicarboxylic acids or derivatives thereof with diamines or by ring-opening polymerization of lactams. In principle, a process for the preparation of polyamides by activated anionic lactam polymerization is also known. For this purpose, lactams, such as, for example, caprolactam, laurolactam, piperidone, pyrrolidone, etc., are polymerized in a ring-catalyzed anionic polymerization reaction in a ring-opening manner. For this purpose, a melt of lactam, which contains an alkaline catalyst and a so-called activator (also known as co-catalyst or initiator), is polymerized at elevated temperatures as a rule.

Thus, DE-A 14 20 241 describes an anionic polymerization of lactams in the presence of potassium hydroxide as catalyst and using 1,6-bis (N, N-dibutylureido) hexane as activator. The activated anionic lactam polymerization using sodium caprolactam is described, for example, in Polyamides, Kunststoff Handbuch, Vol. 3/4, ISBN 3-446-16486-3, 1998, Carl Hanser Verlag, pages 49-52 and Macromolecules, Vol 32, no. 23 (1999), p. 7726.

The unpublished EP 1 1 176950.1 and EP 1 172731.9 describe solid particles containing a lactam, catalyst and activator. This monomer composition can be used by activated anionic polymerization to produce polyamide. The preparation of these particles is carried out by spray drying, optionally may be followed by agglomeration a grinding process. The unpublished EP 12151670.9 describes solid particles which, in addition to the lactamcompo- nent, the catalyst and activator also non-functionalized and / or hydroxy-terminated rubbers may contain.

It is also already described in the prior art that the anionic polymerization of lactams can take place during the molding of a polymer molding in a reaction casting or reaction injection molding process, the catalyst and optionally further additives being added during the process of the lactam melt , The anionic polymerization of lactams in such a reaction casting or reaction injection molding process represents a considerable technical effort. On the one hand, two-component systems must be mixed before use. Furthermore, for the production of a melt, further apparatuses, such as mixing containers, mixing nozzles, etc., which are connected to the actual polymerization mold, are required. Since it can not be ruled out when using a melt that the polymerization partly starts before the melt is brought into the actual polymerization form, additional purification steps of the apparatuses used here follow.

The production of polymer moldings from thermoplastic polymers is known from the prior art. One such plastic molding process is the rotational fusion process. In this process, a polymer raw material is placed in a mold carrier (spin melt mold) and the mold carrier is heated under biaxial rotation. The molten polymer is distributed uniformly on the inner wall of the mold carrier. After a cooling phase, the final molded polymer molded article can be removed (Handbook of Thermoplastic Elastomers, Drobny, Jiri George, 2007, 108-121, William Andrew Publishing / Plastics Design Library).

The polymer moldings produced by rotational fusion can be produced in a wide variety of mold variants. Compared with the injection molding process, the rotational fusion process offers greater shape variance. Thus breakthroughs or incisions can be easily incorporated by the specification of the form in the polymer molding. This is also an advantage over the extrusion process. In addition, rotational molding also makes it possible to produce shaped bodies with little variation in the wall thickness. However, the decisive advantage of the rotary melting process over the extrusion or injection molding process is to be seen in the possibility of a very economical production of the moldings.

In Rotational Molding Technology, Crawford, Roy J .; Thrones, James L .; 2007; William Andrew Publishing / Plastics Design Library, page 40 is described to deform polyamides, especially polycaprolactam, by means of a rotary-melt process. US 4,729,862 describes the preparation of a heat-stabilized polyamide composition of polyamide and copper iodide. These two components are mixed at 282 ° C. This mixture can then be subjected to a rotary melting process.

In order to carry out rotational melt processes, polymers are usually introduced into the mold carrier and melted under rotation in order to obtain the desired shape. This approach has some disadvantages. The mold carrier must be heated to the melting temperature of the polymer, which may require very high temperatures depending on the polymer used. Thus, for the conversion of PA6 in the liquid state usually temperatures

> 200 ° C required. Nevertheless, it is not always guaranteed that a homogeneous melt forms. This in turn leads to considerable qualitative defects of the finished polyamide moldings. For example, a tightness of the molded body can not always be guaranteed. Furthermore, the processing of the PA6 is hampered due to the high viscosity and brittleness. In order to obtain a uniformly distributed polymer melt in the rotational melt form, a sufficiently long rotation time is required. This can counteract a rapid production of the shaped bodies, as a result of which the process is economically disadvantaged.

JP 7032390 describes the production of moldings by means of rotomolding, wherein a ω-lactam is polymerized in the presence of an anionic polymerization catalyst and an activator.

GB 1 133 840 describes the production of moldings, wherein lactams are polymerized in a mold under rotation. For this purpose, an activated melt is first provided and then transferred to the polymerization in the form. IE 991090 describes a rotational fusion process in which, inter alia, lactam and activator can be filled into the mold as a premix.

US Pat. No. 3,780,157 describes a process for the production of shaped hollow bodies from polyamides by activated anionic polymerization of lactams by means of rotary fusion processes, wherein the shaped bodies are reinforced by inorganic fillers, in particular by glass fibers. Although it is generally described in column 2, lines 60 to 67 that a powder mixture consisting of the components lactam, catalyst and activator can be introduced into the mold carrier. However, the concrete examples show that initially an activated lactam smelting provided and this is transferred in the molten state in the rotational melt mold.

EP 0755966 describes the preparation of composites of reinforcing fibers in a polyamide 12 matrix consisting of anionically polymerized laurolactam. Also in D2, an activated lactam12 melt is first prepared and placed in a liquid state in a hot rotary mold. Under pressure and temperature, the polymerization of the melt takes place. However, D2 also discloses (p.4, lines 37/38) that powder mixtures of lactam, catalyst and cocatalyst can be used.

US 2007/0246475 describes the preparation and use of a polymerization composition consisting of polymenation precursor, a catalyst and an activator. The mixture is melted and placed in a molten state in the liquid state, in order then to simultaneously carry out the polymerization and the rotary melting process. For the user, however, it has the disadvantage that it not only has a further working step, namely the preparation of the melt from Polymensationsprecursor, catalyst and activator, but in addition to the rotary melting plant requires further heatable mixing container. The separate storage and the separate transport of the starting materials for the process for the production of polyamide by activated anionic lactam polymerization mean a high logistic effort. Likewise, the separate supply of raw materials in the process for the production of polyamide by activated anionic Lactampolymerisa- tion is associated with a high expenditure on equipment.

In addition, the polymerization stability is not always ensured when two melt templates, one of which contains the activator and the other the catalyst, must be mixed together to provide the polymerizable composition. In most cases, the melt masters are mixed inline or via an in-line mixer or mixing nozzle or the melt masters are combined. In this case, a reactive, no more polymerization-stable mixture is obtained, even before it was converted into a rotary melt mold. After transferring the reactive melt into the rotational melt mold, additional cleaning of all equipment which was in contact with the melt follows, otherwise the residual melt still polymerizing, which can lead to deposit formation and in the worst case to blockage of the equipment. It has now surprisingly been found that polyamide molded articles can be produced by a rotary melt process in which a solid, lactam-containing polymerizable composition is provided and used for simultaneous polymerization and shaping. Thus, the above-mentioned disadvantages of the prior art for the production of polyamide moldings can not only be remedied, but the process can also be carried out time and energy efficient. It is advantageous to fill or coat the mold carrier not directly with the already fully polymerized polyamide, but with a liquefiable at low temperatures precursor and then perform the polymerization in situ. In this way, not only time, but also energy can be saved in the processing process, since the components for the production of the molded body usually only once must be heated to a temperature above the melting point of the monomers. It is also advantageous in terms of process economics that for the production of polyamide moldings a polymerizable composition can be used which already contains the lactam monomer, the catalyst and the activator and optionally further additives, and which directly in the mold or on a support , z. As a textile support, for example by increasing the temperature, could be polymerized. This polymerizable composition used in the present invention may be solidified in a mold carrier (rotational melt mold), made flowable therein, dispersed and polymerized to obtain a polyamide molded body. The associated possibility for processing a one-component composition directly at the customer reduces the high logistical and equipment expense which is required when using the known from the prior art process for the production of polyamide moldings. Thus, it also becomes possible to formulate a polymerizable composition as a commercial form and to transport stable intermediates to a final consumer, in which the production of the shaped body takes place.

The invention relates to a process for the production of polyamide molded articles, wherein:

(a) providing a polymerizable composition which

A) at least one lactam,

B) at least one catalyst and C) at least one activator which is selected from isocyanates, acid anhydrides, acid halides whose reaction products comprise A) and mixtures thereof, (b) the solidified polymerizable composition provided in step a) is introduced into the mold carrier of a rotary melting plant,

(c) heating the polymerizable composition into the mold carrier while rotating to a temperature at which the polymerizable composition is flowable and evenly distributing the flowable polymerizable composition,

(d) polymerizing the polymerizable composition under rotation, (e) cooling the polymerized composition, and

(F) the polyamide molding removed from the mold carrier.

Another object of the present invention is the use of a polymerizable composition containing at least the components A, B and C, in a rotary melting process for the production of polyamide moldings.

The method according to the invention distinguishes itself by at least one of the following points, in contrast to known methods of the prior art:

• Time efficiency

• Energy efficiency

• low equipment costs

• high quality of polyamide moldings

· Low content of residual monomer

By the term "polymerizable composition" in the context of the present invention is meant a composition which is solid at room temperature under normal conditions (20 ° C, 1013 mbar). The polymerizable composition used according to the invention is preferably still solid even at relatively high temperatures. Preferably, the polymerizable composition used according to the invention is still solid at a temperature of at least 50 ° C, more preferably at a temperature of at least 60 ° C. The term "mold carrier" in the context of the invention means a rotational melt mold.

The term "melt" in the context of the invention also refers to molten lactam with activator and catalyst dissolved therein. In the context of the present invention, the term "melting" is not understood strictly in a physicochemical sense, but also used synonymously with conversion into a flowable state. The term "biaxial rotation" in the context of the invention means a rotation about the vertical and the horizontal axis.

A polymer is "dimensionally stable" when it is no longer flowable. The preparation of polyamides by activated anionic polymerization is known in principle. Preferred catalysts for the anionic polymerization by the process according to the invention are compounds which allow the formation of lactam anions. The lactam ions themselves can also act as a catalyst.

The polymerizable composition is preferably in the form of particles.

Specifically, the polymerizable composition is in the form of particles having substantially the same composition, each particle containing components A), B) and C). Substantially the same composition in the context of the invention means that the particles except for production-related deviations, as they are e.g. Usually when weighing or dosing of the particles forming components occur are the same composition. Each individual particle thus contains all components required for the polymerization. Not the same composition are especially those particles containing only one or only two of the components A), B) and C). The polymerizable composition in the form of particles used according to the invention thus differs fundamentally from dry-formulated polymerizable compositions known from the prior art (so-called dry blends).

The particles generally have an average diameter of from 1 to 2000 μm, preferably from 10 to 1000 μm, particularly preferably from 50 to 500 μm, very particularly preferably from 100 to 200 μm. The mean diameter can be reduced by Scattering or by sieve fractions and means the volume average diameter.

Preferably, a polymerizable composition is used which, based on the total weight of the composition, 50 to 99.7 parts by weight, preferably 70 to 98 parts by weight, particularly preferably 80 to 95 parts by weight, of at least one lactam (A ) contains.

Preferably, a polymerizable composition is used which, based on the total weight of the composition, 0.2 to 16 parts by weight, preferably 2.4 to 8 parts by weight, particularly preferably 3.2 to 5.6 parts by weight contains at least one activator (C).

Preferably, a polymerizable composition is used which, based on the total weight of the composition, 0.1 to 5.4 parts by weight, preferably 0.54 to 3.6 parts by weight, particularly preferably 0.64 to 3 wt. Parts of at least one catalyst (B) contains.

The polymerizable composition provided in step a) is stable and solid at room temperature. In particular, the polymerizable composition used according to the invention does not polymerize below the melting point of the lactam component and is thus stable to unwanted premature polymerization. The polymerizable composition used according to the invention can be stored for several months and used at any time for the polyamide production.

Particularly suitable lactams are ε-caprolactam, 2-piperidone (δ-valerolactam), 2-pyrrolidone (γ-butyrolactam), capryllactam, enanthlactam, laurolactam or mixtures thereof. Preference is given to caprolactam, laurolactam or mixtures thereof. The lactam used is particularly preferably exclusively caprolactam or exclusively laurolactam. Furthermore, it is also possible that the polymerizable composition contains at least one monomer (M) copolymerizable therewith in addition to at least one lactam. The monomer (M) may in principle be selected from lactones and crosslinkers. The monomer is preferably selected from lactones. Preferred lactones are, for example, ε-caprolactone and / or γ-butyrolactone. The amount of monomer (M) should not exceed 40% by weight, based on the total weight of the monomers used for the polymerization. The proportion of (M) is preferably from 0 to 30% by weight, particularly preferably from 0.1 to 20% by weight, based on the total monomer. The polymerizable composition used in the present invention may contain a crosslinking monomer. A crosslinking monomer can be a compound containing more than one group that can be copolymerized with the lactam monomer. Examples of such groups are epoxy, amine, carboxyl, anhydride, oxazoline, carbodiimide, urethane, isocyanate and lactam groups. Suitable crosslinking monomers are, for example, amino-substituted lactams, such as aminocaprolactam, aminopiperidone, aminopyrrolidone, aminocapryllactam, aminoanthulactam, aminolauryllactam or mixtures thereof, preferably aminocaprolactam, aminopyrrolidone or mixtures thereof, particularly preferably aminocaprolactam. In a preferred embodiment of the invention only lactams are used as monomers.

Suitable catalysts B) for use in the process according to the invention are customary catalysts, as commonly used for anionic polymerization.

Such catalysts are known for example from polyamides, Kunststoffhandbuch, 1998, Karl Hanser Verlag. Catalyst B) is preferably selected from sodium caprolactamate, potassium caprolactamate, bromide magnesium caprolactamate, chloride magnesium caprolactamate, magnesium biscaprolactamate, sodium hydride, sodium, sodium hydroxide, sodium methoxide, sodium ethanolate, sodium propanolate, sodium butanolate, potassium hydride, potassium, potassium hydroxide, Potassium methoxide, potassium ethoxide, potassium propoxide, potassium butoxide and mixtures thereof. In particular, a catalyst B) is used, which is selected from sodium hydride, sodium and sodium caprolactamate. Particular preference is given to using a catalyst B) which is selected from sodium caprolactamate. In a specific embodiment, a solution of sodium caprolactamate in caprolactam is used, for. B. Brüggolen® C10 Brüggemann, DE, 17 to 19 wt .-% sodium caprolactamate in caprolactam. As catalyst B) is also particularly suitable bromide magnesium caprolactamate, z. B. Brüggolen® C1 Brüggemann, DE. The molar ratio of lactam A) to catalyst B) can be varied within wide limits; it is generally 1: 1 to 10,000: 1, preferably 5: 1 to 1000: 1, more preferably 1: 1 to 500: 1 The polymerizable composition used according to the invention contains at least one activator C) for the anionic polymerization.

Activators may also be understood as precursors for such activated N-substituted lactams which, together with the lactam A), form an activated lactam in situ. The number of chains growing depends on the amount of activator. Isocyanates, acid anhydrides and acid halides or their reaction products with the lactam monomer are generally suitable as activator C).

Suitable activators C) include aliphatic diisocyanates, such as butylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, undecamethylene diisocyanate, dodecamethylene diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), isophorone diisocyanate, aromatic diisocyanates, such as toluyl diisocyanate, 4 4'-methylenebis (phenyl) isocyanate or polyisocyanates (for example isocyanates of hexamethylene diisocyanate, Basonat® HI 100 / BASF SE), allophanates (for example ethyl allophanate). In particular, mixtures of the compounds mentioned can be used as activator C).

Also suitable as activators C) are aliphatic diacid halides, such as butylene diacid chloride, butylene diacid bromide, hexamethylene diacid chloride, hexamethylene diacid bromide, octamethylene diacid chloride, octamethylene diacid bromide, decamethylene diacid chloride, decamethylene diacid bromide, dodecamethylene diacid chloride, dodecamethylene diacid bromide, 4,4'-methylenebis (cyclohexylic acid chloride), 4 , 4'-methylenebis (cyclohexylic acid bromide), isophorone diacid chloride, isophorone diacid bromide, and aromatic diacid halides such as toluylmethylenedioic acid chloride, toluylmethylenecidic bromide, 4,4'-methylenebis (phenyl) acid chloride, 4,4'-methylenebis (phenyl) acid bromide. In particular, mixtures of the compounds mentioned can be used as activator C).

Particular preference is given to a polymerizable composition, wherein at least one compound selected from the group consisting of aliphatic diisocyanates, aromatic diisocyanates, polyisocyanates, aliphatic diacid halides and aromatic diacid halides is used as activator C). In a preferred embodiment, at least one compound selected from hexamethylene diisocyanate, isophorone diisocyanate, hexamethylene dicarboxylic acid, hexamethylene diacid chloride and mixtures thereof is used as activator C). Hexamethylene diisocyanate is particularly preferably used as activator C).

The activator C) can be used in solid form or as a solution. In particular, the activator C) can be used dissolved in caprolactam. Suitable as activator C) is, for example, a caprolactam-blocked 1,6-hexamethylene diisocyanate. A solution of a caprolactam-blocked 1, 6-hexamethylene diisocyanate in caprolactam is commercially available under the name Brüggolen® C20 from Brüggemann, DE.

The molar ratio of lactam A) to activator C) can be varied within wide limits and is generally 1: 1 to 10,000: 1, preferably 5: 1 to 2,000: 1, particularly preferably 20: 1 to 1,000: 1.

The polymerizable composition used in accordance with the invention may contain, in addition to the abovementioned components A), B) and C), at least one further component selected from among polymers, monomers, fillers and / or fibers and further additives.

The polymerizable composition may contain one or more polymers. The polymer may in principle be selected from polymers which are obtained in the polymerization of the polymerizable composition according to the invention, including various polymers and polymer blends. The polymerizable compositions used according to the invention comprise at least one polymer in an amount of 0 to 40 wt .-%, preferably from 0 to 20 wt .-%, particularly preferably in an amount of 0 to 10 wt .-%, based on the total weight of polymerizable composition, on. When the polymerizable composition contains at least one polymer, so preferably in an amount of at least 0.1 wt .-%, particularly preferably 0.5 wt .-%, based on the total weight of the polymerizable composition. In a specific embodiment, the polymerizable composition contains no polymer as formed in the polymerization of the polymerizable composition used in the invention. In another specific embodiment, the polymerizable composition does not contain a polymer. The polymerizable composition may contain one or more polymers which are preferably added to the composition in the form of a polymer. In a first embodiment, the added polymer contains groups which are suitable for forming block and / or graft copolymers with the polymer formed from the lactam monomer. Examples of such groups are epoxy, amine, carboxyl, anhydride, oxazoline, carbodiimide, urethane, isocyanate and lactam groups.

In a further embodiment, the polymerizable composition contains at least one polymer selected from polystyrene, styrene copolymers, polyphenylene oxide ethers, polyolefins, polyesters, polyethers, polyetheramines, polymers of vinyl-containing monomers and mixtures of said polymers. In a preferred embodiment, the polymerizable composition comprises at least one polymer selected from styrene-acrylonitrile copolymers (SAN), acrylonitrile-butadiene-styrene copolymers (ABS), styrene-butadiene copolymers (SB), polyethylene (HTPE (high low-temperature polyethylene), polypropylene, polybutene-1, polytetrafluoroethylene, polyethylene terephthalate (PET), polyamides, polyethylene glycol (PEG), polypropylene glycol, polyethersulfones (PESU or PES), polyvinyl chloride , Polyvinylidene chlorides, polystyrene, impact-modified polystyrene, polyvinylcarbazole, polyvinyl acetate, polyvinyl alcohol, polyisobutylene, polybutadiene, polysulfone, and mixtures thereof. These serve, for example, to improve the product properties, compatibilities of the components and viscosity. In one embodiment, the solid polymerizable composition contains at least one filler. The term "filler" is broadly understood in the context of the invention and includes particulate fillers, fibrous materials and any transitional forms. Particulate fillers can have a wide range of particle sizes, ranging from dusty to coarse-grained particles. Suitable fillers are organic or inorganic fillers and / or fibrous materials. For example, inorganic fillers such as kaolin, chalk, wollastonite, talc, calcium carbonate, silicates, titanium dioxide, zinc oxide, graphite, glass particles, e.g. As glass beads, nanoscale fillers, such as carbon nanotubes (carbon nanotubes), carbon black, nanoscale phyllosilicates, nanoscale alumina (AI2O3), nanoscale titanium dioxide (T1O2), graphene, phyllosilicates and nanoscale silica (S1O2), are used.

Furthermore, one or more fibers can be used. These are preferably selected from known inorganic reinforcing fibers, such as Borfa- fibers, carbon fibers, silica fibers, ceramic fibers and basalt fibers; organic reinforcing fibers such as aramid fibers, polyester fibers, nylon fibers, polyethylene fibers and natural fibers such as wood fibers, flax fibers, hemp fibers and sisal fibers.

Particularly preferred is the use of glass fibers, carbon fibers, aramid fibers, boron fibers, metal fibers or potassium titanate fibers. Specifically, chopped glass fibers are used. The fibers mentioned are preferably used in the polymerizable composition in the form of short fibers. Here, the short fibers preferably have an average fiber length in the range of 0.1 to 0.4 mm. It is also possible that pulps are used in the form of long fibers or as a mixture of short and long fibers. Then, however, their use is advantageously carried out by placing them directly in the mold carrier, as described in more detail below for fiber fabric or fiber braids. Also suitable are fibers having a mean fiber length in the range of 0.5 to 1 mm and long fibers, which preferably have an average fiber length of more than 1 mm, preferably in the range of 1 to 10 mm. Basically, there is no limit to the length of the suitable fibers when used directly in the mold carrier. For example, fiber fabric or fiber braids have a virtually infinite fiber length.

In particular, it is also possible to use mixtures of the stated fillers and / or fibrous materials. Glass fibers and / or glass particles, in particular glass beads, are particularly preferably used as filler and / or fiber. The polymerizable composition used according to the invention preferably contains from 25 to 90% by weight, in particular from 30 to 80% by weight, based on the total weight of the polymerizable composition, of at least one filler and / or fibrous material. In a specific embodiment, the polymerizable composition used according to the invention contains from 30 to 50% by weight, based on the total weight of the polymerizable composition, of at least one filler and / or fiber. In a further specific embodiment, the polymerizable composition used according to the invention contains from 50 to 90% by weight, based on the total weight of the polymerizable composition, of at least one filler and / or fibrous material.

In a preferred embodiment, the polymerizable composition may contain at least one further additive. The additives are preferably present in an amount of from 0 to 5% by weight, based on the total weight of the polymerizable composition, preferably from 0 to 4% by weight, based on the total weight of the polymerizable composition, more preferably from 0 to 3.5 wt .-%, based on the total weight of the polymerizable composition. Stabilizers such as copper salts, dyes, antistatic agents, release agents, antioxidants, light stabilizers, PVC stabilizers, lubricants, flame retardants, blowing agents, impact modifiers, nucleating agents and combinations may be added as additives. When the polymerizable composition contains at least one additive, so preferably in an amount of at least 0.01 wt .-%, based on the total weight of the polymerizable composition, more preferably at least 0.1 wt .-%, based on the total weight of the polymerizable Composition, in particular at least 0.5 wt .-%, based on the total weight of the polymerizable composition.

Preferably, the polymerizable composition used according to the invention contains as additive an impact modifier. If a polymeric compound is used as the impact modifier, it is added to the aforementioned polymers. In particular, a polydiene polymer (for example polybutadiene, polyisoprene) is used as impact modifier. These preferably contain anhydride and / or epoxy groups. In particular, the polydiene polymer has a glass transition temperature below 0 ° C., preferably below -10 ° C., particularly preferably below -20 ° C. The polydiene polymer can be based on a polydiene copolymer with polyacrylates, polyethylene acrylates and / or polysiloxanes and prepared by the usual methods (eg emulsion polymerization, suspension polymerization, solution polymerization, gas phase polymerization).

According to the invention, a polymerizable composition, as described above, is filled in solid form into a mold carrier (rotational melt mold) of a rotary molding plant in order to produce a polyamide molding. Suitable rotary melting plants are known per se.

For the production of a polyamide molded article, a polymerizable composition, as described above, is preferably filled into a mold carrier, which is heated before the polymerizable composition is filled. When introducing the polymerizable composition used according to the invention, the mold carrier preferably has an elevated temperature, which is selected according to the lactam used. When using caprolactam as Lactamkomponente, the mold carrier preferably has a temperature of 20 to 55 ° C. For the production of a polyamide shaped body, as described above, the mold carrier and / or the oven space in which the mold carrier is located is preferably closed after filling. It is advantageous to keep the proportion of components not involved in the production of the polyamide molding, especially water, carbon dioxide and / or oxygen, as low as possible. Therefore, the components and equipment used should be substantially free of water, carbon dioxide and / or oxygen. Preferably, an inert gas atmosphere is used for storage of the components used and / or during filling of the rotomolding device and / or during the polymerization. Suitable inert gases are for. As nitrogen or argon. In many cases, a complete inerting is not required, but already a covering of the used containers, molds, etc. with an inert gas is sufficient.

According to the invention, the temperature of the mold carrier is increased in order to produce the polyamide molding in step c) in order to make the polymerizable composition flowable. In this case, the temperature is selected such that a flowable form of the polymerizable composition is formed and this is distributed uniformly on the inner surface of the mold carrier. The mold carrier is heated by methods known to the person skilled in the art. Preferably, this is done in an oven, for. B. hot air oven, which is usually gas fired.

The above-described polymerizable composition is heated to a temperature at which it is sufficiently flowable to disperse under rotation in the mold carrier. In order to convert the polymerizable composition into a flowable state, it is generally sufficient to heat it to at least the melting temperature of the pure lactam component. The heating of the polymerizable composition used in the invention in step c) is preferably carried out at a temperature of 1 to 20 ° C, more preferably from 3 to 15 ° C, in particular from 5 to 10 ° C above the melting temperature of the lactam component used. The heating of the polymerizable composition used in accordance with the invention in step c) takes place at a temperature of preferably less than 180 ° C., particularly preferably less than 160 ° C., in particular less than 120 ° C., especially preferably less than 90 ° C. The selected temperature in step c) depends on the selection of the lactam component in the polymerizable composition.

According to the invention, in order to produce a polyamide molding in step d), a polymerizable composition, as described above, is distributed evenly in the flowable state to the inner surfaces of the mold support. The uniform distribution of the flowable composition depends on the viscosity of the polymerizable Composition off. This is influenced, for example, by the lactam component used, the activator and catalyst. The uniform distribution of the flowable composition is preferably completed after 1 to 60 minutes, particularly preferably after 2 to 30 minutes, in particular after 3 to 15 minutes.

The transfer of the polymerizable composition used according to the invention into the flowable state preferably takes place with biaxial rotation of the mold carrier. The distribution of the flowable polymerizable composition used according to the invention preferably also takes place with biaxial rotation of the mold carrier.

According to the invention, in order to produce a polyamide molded article in step d), a polymerizable composition as described above is polymerized after the flowable making and distributing of the polymerizable composition.

According to the invention, a polymerizable composition, as described above in step d), is polymerized by heating to a temperature above the polymerization temperature to produce a polyamide molded article. The temperature depends on the process parameters. Preferably, the temperature is in the range of 50 to 200 ° C. More preferably, the temperature is in the range of 60 to 170 ° C. In particular, the temperature for the use of caprolactam as Lactamkomponente in the range of 85 to 150 ° C.

The polymerization in step d) is preferably carried out by increasing the temperature of the mold carrier under biaxial rotation.

In one embodiment, to produce a polyamide molded article, a polymerizable composition as described above is polymerized by a longer residence time of the flowable polymerizable composition in the mold carrier.

The polymerization time of the polymerizable composition used according to the invention depends on the temperature, type and concentration of the catalyst and activator. The polymerization of the polymerizable composition in step d) of the process according to the invention is generally complete after 1 to 60 minutes, preferably after 2 to 30 minutes. The polymerization time in the process according to the invention is defined as the time from which the furnace temperature reaches the selected polymerization temperature (final temperature) until the beginning of the cooling (= step e). The rotational speed of the mold carrier during the flowability, distribution process and the polymerization depends on the viscosity of the polymerizable composition. The rotational speed of the axes is usually in the range of 1 to 40 rpm (revolution per minute), preferably in the range of 1 to 20 rpm.

In general, it is advantageous impurities such. As water, carbon dioxide and oxygen, which can lead to a termination of anionic polymerization, to keep as low as possible. Therefore, in particular all components used should be dry and free of oxygen and carbon dioxide. Preferably, the polymerization is carried out with substantial exclusion of oxygen, carbon dioxide and water. In particular, the method steps according to the invention are carried out with substantial exclusion of oxygen, carbon dioxide and water. The mold carrier preferably has an inert gas atmosphere during flowability, distribution of the flowable polymerizable composition, and polymerization. In particular, an inert gas atmosphere is present during the polymerization. As stated above, complete inerting is generally not required, but individual or all steps a), b), c), d) and / or e) of the process according to the invention can be carried out in the presence of a sufficient amount of an inert gas.

According to the invention, after the polymerization with rotation in step d), the resulting polymerized composition is cooled (= step e)). For this purpose, the shaped body is usually cooled to a temperature at which the polymerized composition is dimensionally stable. The mold carrier is preferably cooled in step e) to a temperature of 20 to 80 ° C, particularly preferably to 30 to 70 ° C, particularly preferably to 50 to 70 ° C. Preferably, the cooling is carried out under biaxial rotation of the mold carrier. Preferably, the mold carrier is removed from the furnace chamber for cooling. Preferably, the cooling of the mold carrier by contacting with a cooling medium, for. As air or an air / water mixture, or by simply opening the mold carrier. The cooling phase depends on the wall thickness of the resulting polyamide molded body.

The cooling process is completed when the polyamide molded article is dimensionally stable. Thereafter, this can be removed from the mold carrier. The present invention also relates to a process for producing a polyamide molded article as indicated above, wherein the mold carrier contains at least one filler and / or pulp. In a preferred embodiment, the mold carrier contains a fiber fabric and / or a fiber network, for example a glass fiber mat and / or a glass fiber network.

It is also possible to fill a filler and / or fibrous material together with the polymerizable composition in the mold carrier. The optionally added filler and / or pulp can be selected from the aforementioned fillers and / or fibers.

With the aid of the method according to the invention, it is possible to produce polyamide molded bodies with a high content of filler and / or fibrous material. In particular, the polyamide molded article obtained by the process according to the invention has a filler and / or fiber content in the range from 30 to 90% by weight, in particular from 30 to 80% by weight, preferably from 30 to 50% by weight, based on the total weight of the polymerizable composition. In a specific embodiment, the polyamide molded body has a filler and / or fiber content of from 50 to 90% by weight, based on the total weight of the polymerizable composition.

The polyamide molded bodies produced by the process according to the invention can be used in particular as a material for the production of parts of the autocouple series, for. As passenger compartment, fenders, as well as car parts, such as panels of frames, dashboards and the interior of passenger compartments. The polyamide molded articles can also be used as inliners for tanks, gears, housings, packaging films and coatings. In principle, the polyamide moldings produced by the process according to the invention are suitable for any housings for small electrical appliances, such as mobile phones, laptops, iPads or generally plastic articles intended to imitate metal.

The process according to the invention for the production of polyamide molded articles by activated anionic lactam polymerization by means of rotary melting processes using a polymerizable composition as raw material has a number of advantages over the use of a melt or of a polymer powder. The inventive method for producing polyamide form bodies by activated anionic lactam polymerization by means of rotary melting process using a polymerizable composition as a raw material is characterized by logistical advantages such. B. simple storage of raw materials, easy transport of raw materials and easy feed of raw materials in the process compared to the use of melts.

The process according to the invention for the production of polyamide molded articles by activated anionic lactam polymerization by means of a rotary melt process using a polymerizable composition as raw material is further characterized by the advantage that the polymerizable composition has a low melting temperature and thus the rotational fusion process requires less time and energy compared to the use of polymer powder , The process according to the invention for the production of polyamide molded articles by activated anionic lactam polymerization by means of rotary melting using a polymerizable composition as raw material is further characterized by the advantage that the polymerizable composition has a low viscosity of the flowable polymerizable composition and thus shows a better flow behavior, which results in a better, more uniform and faster distribution of the flowable polymerizable composition in the mold carrier in comparison to the polymer powder manifests.

The process according to the invention for the production of polyamide molded articles by activated anionic lactam polymerization by means of rotary melting processes using a polymerizable composition as raw material is further characterized by the advantage that the formation of the polymers takes place in situ. It follows that a rapid solidification of the polyamide molded body, in comparison to the polymer powder, is achieved, namely below the melting point of the polyamide.

The process according to the invention for the production of polyamide molded articles by activated anionic lactam polymerization by means of rotary melting using a polymerizable composition as raw material is further characterized by the advantage that a polymerizable composition in the solid state is added to a mold carrier (rotational melt mold) and made flowable in a mold and polymerized to obtain a polyamide molded article. The process according to the invention for the production of polyamide molded articles by activated anionic lactam polymerization by means of a rotary melt process using a polymerizable composition as raw material is further characterized by the advantage that, compared with the prior art, the rotary melt process has a shortened warm-up phase (flowability, distribution of the polymerizable composition). and shortened cooling phase can be performed.

The process according to the invention for the production of polyamide molded articles by activated anionic lactam polymerization by means of rotary melting processes using a polymerizable composition as raw material is characterized by a high energy and time efficiency.

The invention is explained in more detail by the following examples. These examples illustrate some aspects of the present invention and are in no way to be considered as limiting the scope of this invention.

Examples

Production of a 150 L liquid container:

The inertized mold carrier is preheated to the temperature TForm. The pulverulent polymerizable composition A is introduced into the mold carrier via an inertized solids sluice. At an oven temperature of Tofen.i, the mold carrier is rotated at the speed x about the primary axis and at the speed y about the secondary axis over the time ti. The oven temperature is heated to Tofen, 2. During the heating process and after reaching the target temperature Tofen, 2 the mold carrier continues to be rotated continuously over time t.2. After switching off the energy supply of the furnace, the mold carrier is cooled by the method B and opened after the time t.3. The finished liquid container is removed.

BeiI II III game

A 83.35% Caprolactam 83.35% Caprolactam 96.2% Caprolactam 5.10% Brüggolen® C20 5.10% Brüggolen® C20 1, 6% Brüggolen® C20 1 1, 55% Brüggolen® C10 1 1, 55% Brüggolen® C10 2.2% Brüggolen® C10

B Ambient air Ambient air and ambient air

water cooling

Form 55 ° C 55 ° C 50 ° C

Teapot, 1 140 ° C 85 ° C 100 ° C

Teapot, 2 140 ° C 130 ° C 140 ° C

X 6 6 6

y 2 2 2

ti 4 minutes 10 minutes 1 1 minutes

t ₂ 5 minutes 7 minutes 10 minutes

ts 30 minutes 15 minutes 35 minutes

Bruggols® C20 = N, N'-hexamethylene bis (carbamoyl-s-caprolactam)

Brüggolen® C10 = 17 to 19% sodium caprolactamate in caprolactam

Brüggolen® C1 = caprolactam magnesium bromide

Claims

claims

Process for the preparation of polyamide moldings, wherein

(a) providing a polymerizable composition which

A) at least one lactam,

B) at least one catalyst and

C) at least one activator selected from isocyanates, acid anhydrides, acid halides, their reaction products with A) and mixtures thereof,

(b) filling the polymerizable composition provided in step a) in solid, free-flowing form into the mold carrier of a rotary-molding plant,

(c) heating the polymerizable composition in the mold carrier under rotation to a temperature at which the polymerizable composition is flowable and evenly distributing the flowable polymerizable composition,

(d) the polymerizable composition is polymerized under rotation,

(E) the polymerized composition cools and

(F) the polyamide molding removed from the mold carrier.

The method of claim 1 wherein the polymerizable composition is in the form of particles and wherein all particles have substantially the same composition and each particle contains components A), B) and C).

Method according to one of the preceding claims, wherein the mold carrier during the filling of the polymerizable composition in step b) has a temperature of 20 to 55 ° C.

Method according to one of the preceding claims, wherein the polymerizable composition in step c) to a temperature of 1 to 20 ° C, preferably 3 heated to 15 ° C, more preferably 5 to 10 ° C, above the melting point of the lactam used.

5. The method according to claim 4, wherein the step c) after 1 to 60 minutes, preferably after 2 to 30 minutes, more preferably after 3 to 15 minutes completed.

6. The method according to any one of the preceding claims, wherein the polymerizable composition in step d) to a temperature of 10 to 100 ° C, preferably 30 to 80 ° C, heated above the melting point of the lactam used.

7. The method according to claim 6, wherein the step d) after 1 to 60 minutes, preferably after 2 to 30 minutes, completed.

8. The method according to any one of the preceding claims, wherein the mold carrier in step e) to a temperature of 20 to 80 ° C, preferably to 30 to 70 ° C, more preferably from 50 to 70 ° C, cooled.

A process according to any one of the preceding claims, wherein the polymerizable composition, based on the total weight of the composition:

From 50 to 99.7 parts by weight of at least one lactam A),

0.1 to 3.6 parts by weight of at least one catalyst B) and

0.2 to 8.0 parts by weight of at least one activator C).

10. The method according to any one of the preceding claims, wherein the polymerizable composition contains at least one lactam A), which is selected from ε-caprolactam, 2-piperidone, 2-pyrrolidone, capryllactam, enanthlactam, lauryllactam and mixtures thereof.

1 1. A process according to any preceding claim, wherein the polymerizable composition comprises at least one catalyst B) selected from sodium caprolactamate, potassium caprolactamate, bromide magnesium caprolactamate, chloride magnesium caprolactamate, magnesium biscaprolactamate, sodium hydride, sodium, sodium hydroxide, sodium methoxide, sodium ethanolate, sodium propanolate, sodium butanolate, Potassium hydride, potassium, potassium hydroxide, potassium methoxide, potassium ethanolate, potassium propoxide, potassium butoxide and mixtures thereof. Method according to one of the preceding claims, wherein the polymerizable composition contains at least one activator C), which is selected from hexamethylene diisocyanate, isophorone diisocyanate, Hexamethylendisäurebromid, Hexamethylendisäurechlorid and mixtures thereof.

Method according to one of the preceding claims, wherein the polymerizable composition in the form of particles having an average diameter in the range of 1 to 2000 μηη, preferably from 10 to 1000 μηη, more preferably from 50 to 500 μηη, most preferably from 100 to 200 μηη is present.

Use of a polymerizable composition comprising the components A), B) and C) as defined in any one of claims 1 to 13 for the production of polyamide molded bodies by a rotary melting process.