DE2348179A1 - PARTICULAR POLYMER MATERIAL WITH SPECIAL SHAPE PROPERTIES - Google Patents

Description

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293-21.453P September 25, 1973

Tne Secretary of State for Defense in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland, LONDON, S.W.I., Great Britain

Partial polymer material with special shape properties

The invention relates to a particulate polishing material with special organic properties.

If a particulate, for example granular, thermoplastic material is heated to a temperature above its melting point Sn (or, if the polymer does not have a sharp melting point, its softening temperature 3? S), a viscous mass or liquid is obtained. Shaped bodies can be produced from polymer materials at temperatures above 2m (or! Cs) using conventional molding techniques such as casting processes. Lose in this Pormungavorgang the Feilchen its original configuration and its "üigendaaein ^11, ao that only a macromolecular material present in the molded articles in which no.

293-CJJ 4029)

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Assignment to original, individual particles is more possible. If the shaped object is then reheated to a temperature above ahn (or Ts), one obtains again a viscous hatred with an arbitrary distribution of macromolecules. j> .h., the material has no "memory", that would allow the particles to return to their original configuration and the macromolecules would force them to maintain their position with respect to other molecules within the original rope strand.

It is known that when treating particulate! Polymeric material results in a hardened structure in connection with the introduction of inter-molecular crosslinks within the polymer and having each particle within the resulting particulate material as such a "memory", "for one, however, tries to make such particles by applying heat and pressure to melt , there is little or no tendency towards adhesion between the particles at their interfaces, and any object shaped in this way has poor cohesion.

The invention now provides a particulate polymer material which is characterized by particles having a core of thermoplastic material which is surrounded by a crosslinked polymer layer and has an outer polar graft copolymer layer, so that molded articles can be formed by heating the particulate polymer material to a Temperature at which softening takes place, jariaen and cooling can be produced, which, however, when heated to a predeterminable temperature below the temperature at which the particulate polymer material softens

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will return to the original particle shape.

Preferably at least 30 sewers of the diseases forming the particulate polymer material have a diameter of less than 100 μm.

Usually have at least 50 Grew .-> & and preferably substantially all of the particles forming the particulate polymer material have a diameter of less than 100 µm.

The term "! Particles ¹¹ , as used here, is intended to denote regularly and irregularly shaped powders, plaums or flakes, fibers, tablets or compacts or pearls or any other lOrm which is suitable for the production of porous bodies.

The thermoplastic material forming the cores of the particles in the material according to the invention is preferably made from Group polyethylene, polypropylene, polytetrafluoroethylene, partially fluorinated polyolefins, partially chlorinated polyolefins or nylon type polyamides are selected.

Preferably that forms the core of the particles thermoplastic material is also the base polymer of the outer polar graft copolymer layer and the crosslinked Polymer layer.

j

The surface layer is preferably a graft copolymer from a monomer that creates a polar surface graft. In particular, this is the omonomer the outer graft copolymer is a reactive vinyl monomer from the group of acrylic acid, methacrylic acid, others äthyleniseh

4 0 9 8 13 AO 9 7 7-,

2348173

unsaturated carboxylic acids, acrylamides oci-er I ^ ethacrylaiaide.

The interlinked £ 5-layer * .arm by some chemical Litt el intermolecularly networked? Base polymer include. Preferably v / ground the intermoleiculareii networks of the the surface adjacent crosslinking layer with the. same I. Ionomers formed by surface grafting.

Particulate cushioning material according to the invention is preferably prepared by a process that includes a step of graft polymerization of particulate! thermoplastic material in a solution of a reactive ionomer, one of which is a polar surface graft can be obtained.

Alternatively, at least part of the crosslinking of the crosslinked polymer layer is carried out prior to the graft copolymerization generated with a chemical crosslinking agent that diffuses through the surface of a particulate thermoplastic can and generates the networks to be formed. Suitable chemicals include uivinylbenzene.

The graft copolymerization is preferably carried out under .Conditions, the crosslinking both in the outer polar drip copolymer layer as well as in the crosslinked or induce to be crosslinked layer.

The reactive monomer is preferably a reactive one Vinyl monomers from the group acrylic acid, methacrylic acid, other ethylenically unsaturated carboxylic acids, acrylamides or methacrylamides. The part-cLen-shaped thermoplastic

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Material is preferably thermoplastic material on eggs ü-group "polyethylene, polypropylene, polytetrafluoroethylene, partially fluorinated polyolefins, partially chlorinated polyolefins or polyamides of the iTyloi type.

Suitable solvents in which the monomer is dissolved are solvents or solvents from the group consisting of water, acetone, lower alcohols up to and including butanol, benzene, xylene, toluene or riexane. Chain transfer agents, Lettenabbruchr, iittel, radical scavengers and "surface scavengers" can be added to the solvent-containing monomers, "as it is known and practiced in the graft polymerization technology. The concentration of the konomerea, based on the solvent, can preferably be in the range between about 5 ¹ A and 50; v (YoI./Vol.).

The polymer concentration, based on the solution, is preferably in the range from 20 to 400 g / l.

In the inventive method for producing particulate polymer is graft polymerization preferably triggered or initiated in a solution of lonomers. Triggering centers can be caused by ionizing radiation, ultraviolet / visible light, heat and chemical Initiators such as organic peroxides and other radical initiators ouer ionic initiators such as Lewis acids produced be, xiei of initiation by ionizing rays like accelerated electrons or gamma photons becomes the dose

5 5
preferably limited to 1 χ 10 to 5. x 10 rad with a dose rate not exceeding 3 x 10 rad / h. A preferred embodiment is called ionizing

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Radiation Ganima radiation is used.

Subsequent to the graft polymerization reaction can the produced parts henfö riaige polymer material from. Solvent, residual monomers, homopolymers and any remaining catchers or other additives are separated. This separation is carried out by any suitable means. if carboxylic acid Uonoaere are used, the resulting can Leave the graft internals in the acidic form or alternatively converted into a metal salt form and in this be used. The conversion into a metal salt form preferably containing sodium, potassium, calcium or zinc can by washing the generated particulate material in solutions the appropriate base or basic rials.

In preferred processes for producing particulate *. Material according to the invention four the graft copolymer yields, i.e. the weight of polymerized monomers per weight of base polymer in the copolymer product, between about 10 / o and 60> S obtained.

JKline investigation suggests that between about 0.5 γό and 50 io (w / w) of the base polymer are crosslinked.

ji) s is assumed that the graduated structure of the particulate polymer material according to the invention both with respect to the graft weight of polar copolymer as well as the relative concentration of effectively crosslinked three-dimensional structures for "thermal recovery" or the thermally activated "memory ^ this particle is responsible. oo molded bodies can be

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For example, by molding the particulate polymer material according to the invention, but the original particulate material can be recovered at any later point in time and used for another production, if the particulate material according to the invention at temperatures close to or not much If pressure is exerted via ϊΐη (or 2s), the surfaces of the individual particles are brought together sufficiently close that strong intermolecular forces occur between the polar chemical groups of the graft chains on one rope with such polar groups on an adjacent particle. When the temperature is reduced while maintaining the application of pressure, the bond is sufficiently good that the resulting molded articles have a certain strength which is intermediate that of the well-formed thermoplastic particles and that of other crosslinked cords without a polar surface is obtained. When the mold body is heated to a certain predeterminable temperature below the temperature at which it softens, the particles can separate from their nearest neighbors, so that the molded body disintegrates into its original particles.

Particulate polymer material according to the invention could thus be recovered from waste material> that contains moldings made from material according to the invention by heating the waste to the required temperature and separating the particulate material which has been reformed in this way.

It is assumed that the mechanism of such processes is to be interpreted in the following way;

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- ti

The (in the outer area) networked refuge of the particulate material develops temperature-dependent recoil forces, which tend to a return of aas Teilclieii forming Lakroiaoloiail - AjA / I operations in their original shape and dimension, when -thermal energy-is supplied. The effect is dr fäp:!; Eschrum; iun £ (or relaxation; similar to that of plastic products. At temperatures above those at which it reaches, the cross-linked joint or network takes on the properties of a vulcanized elastomer and flows viscously. . resiliently 'when the erfindungsgemäSen particles are closely adjacent to each other, Lindungsfcräfte contact between the polar graft chains on the surface of ¹ Ieilchen, which are larger than the Rüeiiistellkräfte at ambient st emper a door JIEI lowering of the temperature thus is a fixed i ^<. Me. bonds are probably intermolecular proton or hydrogen bonds, although some entanglement of chains may also take place.

to whom the temperature of the i'oria body is up to a fourth is increased, in which the strength of the networked 3t structure resulting restoring forces is greater than the strength the "inter-i-fropfkette bond", an essential one occurs Reduction of the strength of the standard body on and one on slight mechanical force acting on the i'orin body can disintegrate the body into fragments and recover it of the original epidemics ".

Obviously, the invention should not be used in any! are limited by the above theoretical considerations, which are merely illustrative of the new properties the particles according to the invention are used.

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IAD OWQINAL

In practice, the manufacturer can specify a particle size
Polymerizat er ial according to an invention so drafted that it
his requirements for the moldings to be produced
really v / ird. The temperature at which the ifora body
disintegrates into jjruciistüeke depends on the relative graft level
and the crosslink density of the particulate material
and can be predetermined in the practical implementation of the graft polymerization, iienn z.ß. If two particulate materials with a uniform graft level are produced, the material with the higher crosslinking density has the lower "recovery temperature" (temperature for the recovery of the particles). Conversely, if two particulate materials are produced with a uniform crosslink density, then whichever material will exhibit a higher one
Graft level has the higher "recovery temperature". By selecting the particulate polymer, Lonoaeren and graft level as well as the crosslinking density, the manufacturer can thus use particulate polymer material according to the invention
produce a "recovery temperature" above 100 ⁰ G, which is suitable for disposable cups, for example, or material with a recovery temperature of for example
can be suitable for toothpaste tubes.

a relaxation temperature of, for example, 35 ΰ, which is about

From the particulate material according to the invention
Shaped bodies can be produced in such a way that the lirenzflache between the 'particles is a ledium that can be used to transport selected liquids and / or
of special ions and non-condensed gases. The particulate limaterial can thus be used for the production of battery or accumulator separators or partition walls, as described in the Amaelderin patent application filed at the same time as the present patent application (British

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Patent application 44 137/72), see us. Z. 293-21.454P. '

In the following we will learn some "/" for .generating the particulate polyamide according to the invention based on described by examples.

example 1

"Telcon" powder (low density polyethylene) was sieved through a 0.090 mm clear vial size sieve. It was assumed that about 80% by weight of the powder had a grain size between 75 and 90 / in (diameter). 80 g of the screened powder was added to 1 1 a v / ässrigen solution containing 40 <? ■> (YoI./Vol.) Acrylic acid and 60 <p (vol./vol.) Of distilled v / ater added to the 2 g iäisensulfat (j2isen (II) sulphate) of analysis quality (analar grade) had been added per liter. The measurement was carried out in a glass jar at room temperature with Gamina photons from a Co source

5
irradiated with a total dose of 5 x 10 ■ rad at an average dose rate of 5 χ 10 " ¹ rad / h, the mixture being constantly stirred and flushed with" white spot "nitrogen during the entire time of the irradiation. After the irradiation, the The mixture is filtered through linen gauze to separate the treated powder.

The powder was in excess 20% (wt / yoI.) aqueous KOH solution at room temperature for 30 Li minutes "extracted" and continue with excess 20 <; oiger (Vol./Vol.) aqueous HCl solution for a further 30 minutes and finally washed with an excess of distilled water. These operations were designed to remove traces of homopolymer and other impurities from the graft copolymerized powder

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carried out. The "extracted" grafted powder in foria \ iurde ', Varialuftofen at 60 ^υ 0 dried by 2 hours of Aufheisen in one. With regard to the USA, your grafted powder was estimated to be 40 ψ> (w / w) of polymerized acrylic acid.

The grafted powder was used for conversion; of the graft copolymer in its kallumsalaforra for 10 minutes at room temperature in an excess "of 20 ^ iger (Sew./Vol.) aqueous KOH solution and then for 2 hours in .Dried in an air oven at 60 ° C.

Mach 24 is settled ^ leichgewiehtseinstellung ir.it OCE AtniO3i>". Iilre an I _A close the powder in salt form in a · ocliablone between layers of z'.7ei was phot ο graphical Einglasbzw. U-lättungsplatten an electrically beneizten between the plates, brought vvassergeküiilten, hydraulic press. the xulver a mean pressure of 7 kg / ^ was impressing 'cm above at a -temperature of 140 ° 1 minutes geforut long. the' temperature was then decreased, while maintaining the impressed pressure to 80 ⁰ G and The molded body was then removed from the template, and the resulting organic liqueur was tough or firm and flexible at room temperature.

When a section of porous body was brought to a temperature of 110 ⁰ O by jet-like "■ änaeeinwirlcung", the lights forming the shaped body relaxed, "the shaped body -, more opaque to light and had a low static strength, so that with mechanical The resulting powder was reshaped by the same molding technique as above.

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Another part of the formed body was left to absorb water from either the liquid or the vapor phase. The I'Oria body became opaque and immediately returned to its original particulate state ^{when heated to 120 0 O in the manner of a jet.}

This process of reshaping and "repeating" the grafted powder particles were repeated a number of iial.

Example 2

20 g of "ijolvay IiA 4005" powder (low density polyethylene) with an average particle size of <; 10 jam were added to 0.1 l of an aqueous solution with 50 % -β> (YoI./Vol.) Acrylic acid and 4 g / l iron sulfate of analysis quality. The reaction mixture was irradiated in a glass vessel under the same conditions as in example 1 and then treated or extracted in the same way as in example 1.

The grafted powder was converted into the oalzforia as in Example 1. This v / was emulsified with water in such a way that that an emulsion of about 2 g of grafted powder per ml (cc.) of j & iiulaion was obtained. An i'orni was made with the emulsion coated by immersion, allowed to dry and equilibrated under normal atmospheric conditions A molded body by evenly stamping '.'arms and I »rucJ £ generated as in Example 1. The formed lori body had the same mechanical strength properties and, "Poor recoverability," as given in Example 1.

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IAD ORIGINAL

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Example 3

Polytetrafluoräthylenflaura or flakes were as in Example 2 graft-copolymerized and extracted or processed in order to obtain a material that is necessary for the formation of F'oriiibodies by imprinting ./änae (200 0) and back (42.2 kg / cm) was suitable. was another i'orm body by imprinting significantly higher prints at room temperatures educated. The Forra bodies were tough or firm and showed similar properties to standard bodies untreated jiolyte tetrafluoroethylene powder, however they are considerably more permeable to liquids and vapors and gases.

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Claims (1)

Claims 1. Filly shaped polymer material featured . by particles with a core made of thermoplastic material, which is surrounded by a cross-linked polymer layer and an outer polar plug-coj) olynierscnicht, from which Molded body by heating the material to a temperature in which it softens, molding and cooling can be produced, which, however, is subsequently carried out by heating to a determinable temperature below the temperature at which the particulate material softens to its original state Particle form to return. 2. Particulate polymer material according to claim 1, characterized characterized in that at least 30 wt .- ^ of the material forming cords have a diameter of less than 100 µm. 3. Particulate polymer erial naeh claim 1 or 2, characterized in that at least 50 wt .- ^ of the Particles forming material have a diameter of less than 100 m. 4. Particulate polymer material according to one of the preceding claims, characterized in that practically all the epidemics forming the material have a diameter of less than 100 μια . 5. Particulate polymeric material according to any one of the preceding Claims, - characterized in that the thermoplastic limaterial forming the core of the particles also includes the 409813/0977 Base polymers of the outer graft copolymer layer and, if crosslinked, which forms the crosslinked polymer layer. 6. Particulate polymer material according to any of the preceding Claims., Characterized in that the thermoplastic L-Imaterial forming the core of the particles the group of polyethylene, polypropylene, polytetrafluoroethylene, partially fluorinated polyolefins, partially chlorinated polyolefins or polyamides of the nylon type is selected. 7. Lily-shaped polymer material according to one of the preceding Claims, characterized in that the ■ Oomonoinere of the outer graft gopolymer layer is a reactive Tinyl monomers from the group acrylic acid, liethacry.lsaure, other ethylenically unsaturated carboxylic acids, acrylamides or methacrylamides. 8. Process for the production of the partial polymer material according to claim 5, characterized in that particle-shaped thermoplastic material in a solution of reactive monomers from which a polar graft is obtained can be subjected to a graft copolymerization will. 9. The method according to claim S, characterized in that the graft oil polymerization is carried out under conditions is, the cross-links of both the outer polar graft-Gopolyiaerschicht as well as the adjacent crosslinked or to be crosslinked polymer layer. 10. The method according to claim ö or S> characterized in that at least one part of the networking in the networked or 409813/0377 polymer layer to be crosslinked before the graft copolymerization is made with a chemical crosslinking agent that diffuses through the surface of the thermoplastic particles and can bring about crosslinks to be formed. 11. The method according to claim 10, characterized in that divinylbenzene is used as the chemical crosslinking agent. 12. The method according to any one of claims 8 to 11, characterized in that the reactive monomer is a reactive vinyl monomer from the group of acrylic acid, methacrylic acid, other ethylenically unsaturated carboxylic acids, acrylamides or lethacrylamides is. 15. The method according to any one of claims 8 to 12, characterized in that the particulate thermoplastic limaterial a thermoplastic i ^ aterial from the group polyethylene, Polypropylene, polytetrafluoroethylene, partially fluorinated polyolefins, 'partially chlorinated polyolefins or polyamides is of the nylon type. 14. The method according to claim .12 or 13 »characterized in that that the solvent in which the lionomere is dissolved " becomes, a solvent or a list of solvents from the group of water, acetone, lower alcohols up to and including Butanol, .benzene, xylene, toluene or hexaü is. 15. The method according to any one of claims 8 to 14, characterized in that the concentrations of reactive monomers, based on the solvent, within the range from 5 to 50> u (w / w) and the concentrations of the thermoplastic Iimaterials, based on the solution, within the range 409813/0977 from 20 to 400g / l. 16. The method according to any one of claims 8 to 15, characterized characterized in that the graft copolymerization by G-amma-fc> radiation with a dose between ΐ χ 10 "* and 5 χ 10 · * rad is initiated at a dose rate not exceeding 3 10 rad / h. 40981 3/0977