Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/32—Phosphorus-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/34—Heterocyclic compounds having nitrogen in the ring
  • C08K5/3412—Heterocyclic compounds having nitrogen in the ring having one nitrogen atom in the ring
  • C08K5/3432—Six-membered rings
  • C08K5/3435—Piperidines

Definitions

• the invention relates to the use of reducing inorganic phosphorus compounds to increase the UV permeability of moldings suitable as solarium material from molding compositions based on polymethyl methacrylate.
• DE-OS 34 21 859 also describes polymethyl methacrylate (PMMA) -based plastics which contain sterically hindered amines and have high UV permeability. It is even increased by installing aliphatic plasticizers. However, these require a lowering of the Vicat softening temperature, which is often not desirable. Plastics with good permeability to UV light are mainly used for solarium material. Good UV transmission is a key requirement here.
• PMMA polymethyl methacrylate
• the UV transmission is significantly improved by adding inorganic reducing phosphorus compounds.
• Their use for this purpose is not known from the prior art. So far, they have been used to lower the yellowness and prevent yellowing tendencies.
• thermoplastics There are a large number of general solutions for preventing or reducing a yellow tinge in thermoplastics.
• antioxidants which, inter alia, are intended to prevent the discoloration of plastic molding compositions under thermal stress, is known (cf. for example Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed., Vol. 3, page 133, Wiley, New York, 1978).
• Antioxidants are also added to the molding compounds before processing, i.e. during the compounding step.
• Kokai Tokkyo Koho JP 60 120 735 describes copolymers of methyl methacrylate, vinyl aromatic and copolymerized cyclic Anhydrides to which, in order to increase the thermal stability and to avoid discoloration of such copolymers when subjected to thermal stress in the melt, for example in injection molding, phosphoric acid esters and other stabilizers based on sterically hindered phenols.
• JP 03 167 245 claims the stabilization of copolymers of methyl methacrylate, N-substituted maleimides and other copolymerizable monomers with compounds selected from the group of alkyl-substituted triarylphosphites, dialkylpentaerythroldiphosphites and phosphaphenanthrene derivatives.
• Jpn. Kokkai Tokkyo Koho JP 63 163 306 includes copolymers of methyl methacrylate and C ⁇ - to C20-alkyl methacrylate as the core material for optical fibers which contain organic phosphites, such as sterically hindered diarylpentaerythrol diphosphites, or thiophosphites to prevent discoloration of the copolymers when subjected to thermal stress.
• organic phosphites such as sterically hindered diarylpentaerythrol diphosphites, or thiophosphites to prevent discoloration of the copolymers when subjected to thermal stress.
• German utility model 2 95 04 693.7 also describes the use of sterically hindered organic phosphite compounds in molding compositions composed of copolymers consisting of the monomer units of alkyl methacrylate, vinyl aromatic and maleic anhydride, and, if appropriate, alkyl acrylate.
• organic phosphorus compounds are also added to the finished, granulated or ground polymer before further processing.
• Inorganic, reducing phosphorus compounds for the purpose of preventing yellow tinge are also known from the prior art.
• EP-A 576 877 describes a polymer based on polymethacrylic and polyacrylimide with a low yellowness index, salts of phosphinic or phosphonic acid being added during the imidation reaction.
• the amounts of phosphorus compounds used are high, presumably to compensate for a loss of activity in the subsequent processing stages. Amounts of 0.1-1% by weight, based on the amount of polymer to be imidized, are preferably used.
• Means for reducing discoloration, in particular yellow tinge, are also known for impact-modified molding compositions. Due to their multiphase structure, for example when embedding a latex dispersion with a core-shell structure as a tough phase in a hard matrix such as PMMA, the production process causes a particularly large number of polymerization auxiliaries, such as, in particular, emulsifiers and buffer salts.
• EP-A 465 049 proposes to prevent the yellowing effect of the interfering by-products in impact-modified molding compositions by adding inorganic phosphorus compounds with a reducing action.
• the addition of sodium hypophosphite in an amount of 50 to 1000 ppm, based on the aqueous latex dispersion used, is claimed here.
• the reagent is added here in a relatively high dosage in an early manufacturing phase.
• DE-A 19544563 teaches to add a much smaller amount of reducing, inorganic phosphorus compounds in a later phase of processing, namely in the compounding step, whereby the yellowing under thermal stress, such as e.g. is largely prevented in the production of moldings.
• UV transmission is a basic requirement for solarium material and UV-permeable covers. These are usually made from a corresponding molding compound by thermoplastic processing, e.g. made by extrusion or injection molding.
• PMMA is ideally suited for this purpose.
• the Vicat softening temperature should not be lowered.
• the means to achieve this goal should be inexpensive and should be able to be added to the plastic without technical difficulties.
• the object was achieved by using one or more, reducing, inorganic phosphorus compounds AP, selected from the group consisting of phosphinic acid and phosphonic acid and their alkali metal, alkaline earth metal and aluminum and their ammonium salts, the ammonium ion with up to four C-
• the molding compound FM based on polymethyl methacrylate consists of 88-100% by weight of polymerized methyl methacrylate monomers. It can also contain 0-12% by weight of a C 1 -C 4 -alkylacrylic acid ester as a comonomer. The content is preferably 1-6% by weight, particularly preferably 1-5% by weight of C 4 -C 4 -alkylacrylic acid ester. Among the C 1 -C 4 -alkyl acrylates, methyl acrylate is preferred.
• the molding compound FM also contains sterically hindered amines (HALS) according to the prior art.
• HALS sterically hindered amines
• These are, in particular as regards the possible variations with regard to the chemical structure, e.g. described in EP 0016870.
• Particularly preferred among the "HALS” products are derivatives of 2,2,6,6, tetramethylpiperidine, e.g. Di- (2,2,6,6-tetramethyl-piperidyl-4) sebacate (TPS).
• TPS 2,2,6,6, tetramethylpiperidine
• TPS 2,2,6,6, tetramethylpiperidine
• TPS 2,2,6,6, tetramethylpiperidine
• TPS 2,2,6,6, tetramethylpiperidine
• TPS 2,2,6,6, tetramethylpiperidyl-4 sebacate
• TPS 2,2,6,6, tetramethylpiperidine
• TPS 2,2,6,6, tetramethylpiperidyl-4 sebacate
• the molding compositions FM can optionally contain mold release agents and thermal oxidation stabilizers in customary amounts.
• the inorganic, reducing phosphorus compounds AP contain phosphorus in the oxidation states +1 or +3. Salts of phosphinic acid (hypophosphites) are technically easily accessible. and the phosphonic acid (secondary phosphites), as well as the free acids themselves. It does not matter whether the salts or the free acids are in the ortho or meta form or also, for example, as dimers. Alkali, alkaline earth, aluminum and ammonium salts can be used, it being possible for the ammonium ion to be substituted by up to four C 1 -C 4 -alkyl and / or C5-C8-cycloalkyl groups.
• Organic, reducing phosphorus compounds selected from the group of aliphatic or monoaryialiphatic esters are far less effective. This applies above all to the various prior art antioxidants based on organic phosphites.
• Sodium hypophosphite is particularly effective and also inexpensively available. Its use is a preferred embodiment of the invention. Although, according to literature, it easily disintegrates thermally with disproportionation, it has proven itself well for the purposes of the invention. The addition mode according to the invention apparently prevents premature thermal decomposition of this reducing agent.
• Alkaline earth hypophosphites are more thermally stable, e.g. Calcium hypophoshite.
• Calcium hypophoshite e.g. calcium hypophoshite
• Mixtures of various reducing inorganic phosphorus compounds can also be used.
• Amounts of more than 0.1% by weight (1000 ppm) based on the molding compound FM generally do not bring about any further improvement in the optical properties, in fact they can trigger property deteriorations in special cases, e.g. an incipient irreversible turbidity in the polymer, which can be recognized from the lower transmission values.
• the inorganic, reducing phosphorus compounds AP are usually applied in solution.
• Water is suitable as a solvent.
• the reducing phosphorus compounds are advantageously used in concentrated solution. A concentration of 50% by weight may be mentioned as a guideline.
• the concentrated solution is usually prepared at room temperature. Depending on the solution and application temperature, other concentrations are possible or necessary, for example 5 to 65% by weight.
• the concentration in water will be chosen to be lower, for example 10-30% by weight. It is surprising that such a small volume of reducing agent as it is a concentrated solution of the phosphorus compound can obviously be homogeneously distributed over the entire batch of polymer. However, it is also possible to apply the reducing inorganic phosphorus compound in powder form, that is to say without using solvent.
• organic, high-boiling liquids such as organic carboxylic acids or primary organic alcohols with 12 to 20 carbon atoms - examples include palmitic acid and stearyl alcohol - are used as solvents for the inorganic, reducing phosphorus compounds AP, thereby avoiding the formation of gas bubbles.
• Relatively dilute solutions of AP in these high-boiling solvents are produced here, for example 0.1 to 20 percent by weight solutions. 1 to 15 percent by weight solutions are preferably used, particularly preferably 2 to 10 percent by weight solutions. Blueing agents can also be dissolved in the high-boiling organic solvents.
• the molding composition should be in particle form. Suitable are e.g. especially granules or regrind in various grain sizes. An average particle size of 1-5 mm is preferred.
• the reducing inorganic phosphorus compound AP is generally added after the polymerization reaction has ended. Incorporation takes place in the melt, which is largely free of residual monomers. At this point in time, the polymer PM contains less than 1% by weight of residual monomer.
• the addition can be done either by adding masterbatch of the inorganic phosphorus compound AP or by weighing e.g. a 5% to 60% aqueous solution of the reducing inorganic phosphorus compound AP to the granules.
• the mixing of the reducing inorganic phosphorus compound AP with the molding compound FM present in particulate form in the compounding step usually takes place first in slow-running mixing units such as drum, ring gear or double-chamber ploughshare mixers.
• the slow running aggregates cause mixing without the phase boundaries being lifted (see Ulimann's encyclopedia der technical chemistry, 4th edition, vol. 2, pages 282 to 311, Verlag Chemie, Weinheim, New York, 1980).
• This mixture is thermoplastic processed in the subsequent processing step of melting.
• extruders, or generally speaking, heatable mixing units are used at the appropriate temperatures, generally between 220 and 280 ° C. Examples are single-screw or multi-screw extruders or extruders with an oscillating screw and optionally also with shear pins.
• the molding compounds FM can be produced in granule grain sizes of, for example, 1 to 5 mm.
• the shaping processing can then begin. Common technical processes such as injection molding, extruding, pressing, sintering and other shaping processes are suitable for this. There are no limits to the design of the molded body FK.
• Another variation of addition is to add the inorganic, reducing phosphorus compounds AP in the form of a so-called masterbatch in the assembly or manufacture of the product or in the shaping processing.
• masterbatch a small part of the molding compound, which is already in granular or ground form, is melted in a separate extruder, and the reducing, inorganic phosphorus compounds AP are added to the melt. It can be metered in as a solution, for example, or it has already been mixed with the granulated molding compound.
• the melt containing the inorganic reducing phosphorus compounds AP in a relatively concentrated form is mixed with the main amount of the molding compound in the extruder combined and thereby diluted to the effective concentration according to the invention.
• the effect according to the invention namely the high UV permeability, can be seen particularly clearly when the molded body FK is produced by injection molding.
• the option is usually not available here, e.g. by degassing to reduce the residual monomer content, unless injection molding machines with degassing cylinders are used.
• the molding composition thus produced contains a relatively high residual monomer content of over 0.3%. For this reason, it can be assumed that the advantage of the inorganic, reducing phosphorus compounds is, at least in part, that they suppress the interfering effects of higher residual monomer contents.
• HALS UV stabilizers
• the UV permeability is increased by the addition of inorganic, reducing phosphorus compounds such as sodium hypophosphite before the shaping processing, that is during Compounding or improved as a masterbatch.
• the addition mode is a simple process which is familiar from the prior art and does not require any additional technical effort.
• the reagent is inexpensive and is only used in low doses so that other properties of the molding composition or the moldings produced therefrom are not changed.
• the decisive advantage of the use according to the invention is the increase in the UV permeability of the moldings produced compared to moldings not produced according to the invention, that is to say without the addition of inorganic, reducing phosphorus compounds.
• the UV transmission for the range from 260 to 300 nm, that is to say for the UV-B range increases by at least 2%, preferably even by at least 5%, based on the 100% transmission.
• the transmission increase is over 5%.
• the transmission increases by at least 1% by acting according to the invention. The effect can only be clearly seen for the UV range. In the visible range, i.e. above 400 nm, no improvement in the transmission can be achieved.
• the increase in transmission is particularly noticeable when the moldings according to the invention are produced by injection molding.
• the molded articles FK can advantageously be used generally as a UV-permeable cover and in particular as a UV-permeable cover for solarium material.
• a commercially available molding compound for solarium covers based on polymethyl methacrylate (PMMA), namely a copolymer consisting of 96% by weight of methyl methacrylate and 4% by weight of methyl acrylate monomer units, which contains 0.25% by weight of a "HALS" UV stabilizer, namely di (2 , 2,6,6-tetramethyl-piperidyl-4) sebacate (TPS) is compounded together with a sodium hypophosphite solution.
• PMMA polymethyl methacrylate
• HALS UV stabilizer
• TPS 2,6,6-tetramethyl-piperidyl-4) sebacate
• 0.05 parts based on 100 parts of the molding compound are 10% pure before processing
• Plates with a thickness of 3 mm are injection molded and the transmission measured in the UV range. The measurement is carried out according to DIN 5033 (D65 / 10 °).
• Example 2 The procedure is as in Example 1, with the difference that 100 ppm of sodium hypophosphite, based on the molding composition, are used.
• a transmission measurement in the UV range on the injection-molded plates showed a significant improvement in the UV transmission of the samples containing sodium hypophosphite (Examples 1 and 2) in comparison with Comparative Example 3. It was found that the addition of 50 ppm of sodium hypophosphite was already sufficient to to achieve the effect of the invention. An addition of 100 ppm hardly results in an increase in the transmission.
• the transmission values of the injection-molded plates from Examples 2 and 3 are shown in Figure 1 as curves over the wavelength range from 250 to 450 nm.
• the solid curve B3 corresponds to example 3.
• the curve B2 shown in dashed lines corresponds to example 2 (the transmission curve according to example 1 was almost completely identical to that of example 2 and was not shown in the figure for the sake of clarity).
• Fig. 1 clearly shows the improvement in transmission in the UV-B range in example 2 compared to example 3.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Processes Of Treating Macromolecular Substances (AREA)

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• 1997
  • 1997-11-14 DE DE1997150434 patent/DE19750434C1/de not_active Expired - Fee Related
• 1998
  • 1998-11-12 AU AU16695/99A patent/AU1669599A/en not_active Abandoned
  • 1998-11-12 WO PCT/EP1998/007235 patent/WO1999025764A1/de not_active Application Discontinuation
  • 1998-11-12 EP EP98961185A patent/EP0953010A1/de not_active Withdrawn
• 1999
  • 1999-06-11 NO NO992849A patent/NO992849D0/no not_active Application Discontinuation

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