Synthetic resin material and process for producing a milling blank for medical technology molded parts, as well as milling blank

Abstract

Synthetic resin material for producing a milling blank for medical technology molded parts, consisting of two components A and B, wherein the first component A comprises at least one polyethyl methacrylate polymer (PEMA), polymethyl methacrylate (PMMA) and / or polyethyl methacrylate-polymethyl methacrylate copolymer (PEMA-PMMA), and the second component B - as a monomer at least poly(propylene glycol) methacrylate, - an organometallic compound as a polymerization promoter, and - comprises an organohalogen compound or dilauryldimethylammonium chloride as a polymerization promoter, wherein - components A and B are free of flexibilizers and / or plasticizers.

Description

[0001] The invention relates to a synthetic resin material for producing a milling blank for medical technology molded parts, a milling blank made of such a synthetic resin material, and a method for producing a milling blank made of a synthetic resin material for medical technology molded parts.

[0002] Blanks for the production of medical device components of the type mentioned above are known in a wide variety of designs from the prior art. Both dental splints and ear molds are currently manufactured using various prior art processes.

[0003] In the first known method, an impression of the positive (dental crown or ear canal) is taken in a first step. Subsequently, in the case of a dental splint, a positive plaster model is created from the impression. A splint (negative) is then thermoformed onto this model, or a two-component material is applied using a scattering technique and subsequently cured. In the so-called PNP (positive-negative-positive) method for manufacturing earmolds, the hearing aid acoustician first takes an ear impression (positive) to create an earmold (for behind-the-ear devices) or a shell (for in-the-ear devices). In a second step, a negative mold (N) is created using the impression. A radiation-curable or self-polymerizing, low-viscosity formulation is then poured into this mold. Afterward, for example...hardened by means of heat in a pressure pot or by means of radiation.

[0004] Another state-of-the-art process for manufacturing splints and / or ear molds involves layer-by-layer manufacturing processes, such as stereolithography, based on digital data. In the stereolithographic process, three-dimensional objects are built up from a low-viscosity, radiation-curable formulation by pre-curing a thin layer (approx. 25–100 µm) of the formulation using actinic radiation in a defined manner, such that the resulting layer exhibits the desired cross-sectional shape of the object at that point. Simultaneously, the resulting layer is polymerized onto the layer cured in the previous step. The construction of the entire object can then be controlled using a computer-controlled laser system, such as an Nd:YVo4 solid-state laser (Viper si). 2SLA System, 3D Systems, USA). The generated shape is then post-cured, for example by radiation.

[0005] Finally, it is well known that medical components, such as dental splints and especially occlusal splints, are manufactured by milling. For this process, a milling blank made of a suitable material is provided and then machined based on three-dimensional digital data. This places specific demands on the material. On the one hand, the material must be easily machinable, especially by cutting; on the other hand, the material of the finished medical component should also exhibit high hardness and a certain degree of flexibility to ensure a high level of wearing comfort. Furthermore, users generally prefer a transparent material for most medical components.

[0006] Furthermore, it is advantageous if the material exhibits a so-called temperature-induced memory effect. For example, a dental splint may be twisted when inserted into the mouth. Due to the memory effect induced by body heat, it then returns to its optimal position during wear. This significantly increases wearing comfort and prevents misalignments compared to a hard, deformed material.

[0007] Finally, it is important that the material of the medical molded part is non-toxic, does not release any harmful substances such as plasticizers, and above all contains neither carcinogenic substances nor substances that are harmful to a child in the womb.

[0008] No material currently known for manufacturing a milling blank for medical technology components, especially for dental splints or ear molds, meets all these requirements.

[0009] German patent application DE 10 2014 114 895 A1 relates to a milling blank made of a material consisting of at least two components for the production of medical device components, in particular dental splints or ear molds. The powder component is a polyalkyl methacrylate polymer, and the liquid component comprises at least one monomer in which the polyalkyl methacrylate polymer is completely soluble. The monomer can be methyl methacrylate, ethyl methacrylate, ethyl acrylate, ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, isobornyl methacrylate, or ethoxyethyl methacrylate.

[0010] A kit-of-parts system for producing a tooth-colored thermoplastic, particularly for dental prostheses, is already known from German patent application DE 10 2019 117 238 A1. The kit-of-parts system comprises a powder component, a liquid component, and a pigment, which may be contained in the liquid and / or powder component. The powder component comprises a polymer selected from polyalkyl methacrylate, polycycloalkyl methacrylate, polycycloalkyl acrylate, and polyalkyl acrylate, and / or a corresponding copolymer, as well as a mandatory initiator. The liquid component comprises a monomer, an acid-based flexibilizer, an activator, and at least one pigment.

[0011] The invention is therefore based on the objective of providing a synthetic resin material and a method for producing a milling blank for medical technology molded parts and a corresponding milling blank, wherein the synthetic resin material is easily machinable, has a high degree of hardness and flexibility and thus offers the user a high level of wearing comfort, is break-resistant and has a temperature-induced memory effect, and does not contain or release any harmful, carcinogenic or reproductive harmful substances such as plasticizers or tetrahydrofurfuryl methacrylate.

[0012] The object of the invention is achieved by a synthetic resin material for producing a milling blank for medical technology molded parts according to claim 1, a milling blank according to claim 10, and a method according to claim 11. Advantageous embodiments of the invention are specified in the dependent claims.

[0013] The synthetic resin material according to the invention for producing a milling blank for medical technology molded parts, in particular for dental splints or ear molds, consists of two components A and B, wherein the first component A comprises at least one polyethyl methacrylate polymer (PEMA), one polymethyl methacrylate (PMMA) and / or one polyethyl methacrylate-polymethyl methacrylate copolymer (PEMA-PMMA), and the second component B comprises at least poly(propylene glycol) methacrylate as a monomer, furthermore at least one organometallic compound as polymerization promoters and at least one organohalogen compound or dilauryldimethylammonium chloride as polymerization promoters, wherein the components A and B are free of flexibilizers and / or plasticizers.

[0014] Furthermore, the invention relates to a milling blank for the production of medical technology molded parts, in particular dental splints or ear molds, from the synthetic resin material according to the invention.

[0015] The inventive method for producing a milling blank from a synthetic resin material for medical technology molded parts comprises, as process steps, first the production and / or selection of a component A comprising at least one polyethyl methacrylate polymer (PEMA), one polymethyl methacrylate (PMMA) and / or one polyethyl methacrylate-polymethyl methacrylate copolymer (PEMA-PMMA), and second the production and / or selection of a component B comprising at least poly(propylene glycol) methacrylate as a monomer, an organometallic compound as polymerization promoters, and an organohalogen compound as polymerization promoters, wherein components A and B are free of flexibilizers and / or plasticizers.Subsequently, components A and B are mixed, preferably with partial or especially complete dissolution of component A in component B, and finally the mixture of components A and B is cured, preferably in a mold for forming the milling blank.

[0016] The synthetic resin material according to the invention is advantageously free of plasticizers, flexibilizers, and harmful, carcinogenic, and reproductive substances such as tetrahydrofurfuryl methacrylate. Furthermore, a milling blank produced from the synthetic resin material is very easy to machine and is also dimensionally stable and flexible, resulting in a high level of wearing comfort for the medical component. Finally, the material exhibits a temperature-induced memory effect, so that any deformation upon insertion is reversed by body temperature during wear of the medical component.

[0017] A synthetic resin material according to the invention is a polymeric material formed from at least one synthetic resin, wherein a synthetic resin is fundamentally a resin produced synthetically by polymerization, polyaddition, or polycondensation reactions. Preferably, the synthetic resin comprises at least one prepolymer and / or has reactive functional groups for a polymerization reaction. More preferably, at least component B comprises a synthetic resin. Particularly preferably, component B is formed from a synthetic resin to at least 90 wt.% and most preferably substantially entirely.

[0018] According to the invention, the milling blank is produced from the synthetic resin material, for which two components are used – components A and B. A material produced from at least two components is understood to be a material formed by mixing the components, in particular by a chemical reaction of at least one substance contained in each of the at least two components. Each of the at least two components can consist of a single substance or be formed by a mixture of substances.

[0019] Basically, a milling blank is understood to be a body made of a millable or machinable material, which can initially have any shape.

[0020] Preferably, the body is free of cavities and / or formed with a homogeneous material composition. Furthermore, it preferably has a smooth surface and / or a compact shape.

[0021] The medical component that can be formed from the milled blank can initially be any object used on the body for medical or cosmetic purposes. Preferably, the medical component is intended for dental use, and particularly preferably, it is a dental splint, a therapeutic splint, a reflex splint, a positioning splint, or a stabilization splint. However, use for other medical purposes, such as ear molds, is also conceivable.

[0022] According to the invention, component A comprises at least one polyalkyl methacrylate polymer from the group consisting of polyethyl methacrylate polymer (PEMA), polymethyl methacrylate (PMMA), and polyethyl methacrylate-polymethyl methacrylate copolymer (PEMA-PMMA). Preferably, component A comprises a single polymer, which is particularly preferably polyethyl methacrylate polymer (PEMA). Furthermore, component A can contain any other substances, wherein the mass fraction of the other substances is preferably less than 25%, particularly preferably less than 10%, most preferably less than 5%, and particularly preferably less than 2%.

[0023] Although both components A and B can exist in any state of matter at room temperature, it is preferred that component A is essentially solid and / or component B is essentially liquid, so that component A can be readily dissolved in the liquid component B and processed into a casting material. Accordingly, the polyethylene methacrylate polymer (PEMA), polymethyl methacrylate (PMMA), and / or polyethylene methacrylate-polymethyl methacrylate copolymer (PEMA-PMMA) of component A is at least partially, and preferably completely, soluble in component B. It is particularly preferred that the entire component A is completely soluble in component B.

[0024] Furthermore, component A is preferably a powder and preferably has a mean particle size of less than 1 mm, particularly preferably less than 500 µm, and most preferably less than 100 µm. Component A is also preferably solvent-free and / or anhydrous.

[0025] According to the invention, at least one monomer of component B is poly(propylene glycol) methacrylate. Furthermore, component B can comprise alkyl acrylate and / or alkyl methacrylate monomers as additional monomers. The additional alkyl acrylate and / or alkyl methacrylate monomer of component B is preferably at least one monomer from the group consisting of methyl methacrylate, ethyl methacrylate, ethyl acrylate, ethoxyethyl acrylate, isobornyl acrylate, and / or isobornyl methacrylate, and more preferably ethoxyethyl methacrylate. However, the list of alkyl acrylate and / or alkyl methacrylate monomers is not to be considered restrictive. These can also be used in combination and / or formulated with other compounds from the group consisting of acrylates or methacrylates.Examples include: bisphenol A ethoxylate(2) dimethacrylate, bisphenol A ethoxylate(4) dimethacrylate, bisphenol A propoxylate(2) dimethacrylate, bisphenol A propoxylate(4) dimethacrylate, and dimethacrylates of (n)-alkoxylated bisphenol F, such as bisphenol F ethoxylate(2) dimethacrylate and bisphenol F ethoxylate(4) dimethacrylate, bisphenol F propoxylate(2) dimethacrylate, bisphenol F propoxylate(4) dimethacrylate, and mixtures thereof. Preferably, monomeric or oligomeric dimethacrylates based on bisphenol A are used, in particular bisphenol A ethoxylate(2) dimethacrylate and bisphenol A ethoxylate(4) dimethacrylate. This list should also be considered non-exhaustive.

[0026] In principle, the components can consist of multiple polymers or monomers. Component B, in particular, can generally consist of only one monomer. However, compositions of component B with multiple monomers, especially mixtures of 2, 3, 4, 5, or more monomers, are also conceivable. A monomer is generally understood to be any chemical substance that can be polymerized with itself, with the addition of an auxiliary substance, or with a second substance. A monomer can also be a dimer or an oligomer of a substance that is still capable of polymerization.

[0027] An organohalogen compound according to the invention is an organic substance comprising at least one halogen atom or one halogen anion. Preferably, the organohalogen compound is a CH-acidic compound, which is particularly preferably stable over a longer period. Furthermore, the organohalogen compound is preferably an ammonium salt, and particularly preferably R1R2R3R4N + HAL - , where R1, R2, R3, R4 are each an alkyl chain with n = 4 - 12 and / or a cyclic residue and HAL is a halogen atom, in particular chlorine, bromine or iodine.

[0028] A preferred embodiment of the synthetic resin material according to the invention provides that the organohalogen compound is a dilauryldimethyl ammonium halide and, in particular, dilauryldimethyl ammonium chloride.Alternatively, the organohalogen compound can also be, for example, trioctylmethylammonium chloride, benzyldimethylcetylammonium chloride, benzyldimethylstearylammonium chloride, lauryldimethylbenzylammonium chloride, benzyltrimethylammonium chloride, triethylamine hydrochloride, trimethylamine hydrochloride, dimethylamine hydrochloride, diethylamine hydrochloride, methylamine hydrochloride, ethylamine hydrochloride, isobutylamine hydrochloride, β-phenylethylamine hydrochloride, acetylcholine chloride, 2-chlorotriethylamine hydrochloride, (2-chloroethayl)trimethylammonium chloride, tetradecyldimethylbenzylammonium chloride, tetraethylammonium chloride, tetramethylammonium chloride, tetrabutylammonium bromide, benzyltrimethylammonium bromide, benzyltriethylammonium bromide, tetrabutylammonium fluoride, tetrabutylammonium iodide, tetramethylammonium chloride, and benzyltriethylammonium chloride, all of which can be used alone or in mixtures.

[0029] Among these organohalogen compounds, six are preferred, namely dilauryldimethylammonium chloride, lauryldimethylbenzylammonium chloride, tetra-n-butylammonium chloride, trioctylmethylammonium chloride, benzyldimethylcetylammonium chloride, and benzyldimethylstearylammonium chloride, because they are soluble in component B at ambient temperature in amounts up to about 5 wt%. In contrast, numerous other organohalogen compounds must be filtered off for use, as their solubility at normal temperature is very low.

[0030] An organometallic compound is understood to be any substance in which organic residues or organic compounds are directly bonded to at least one metal atom. Preferably, the organometallic compound is a complex compound, and particularly preferably a chelate. Also preferably, the organometallic compound contains a transition metal cation and / or is a copper salt, especially a copper(II) salt. It is particularly preferred that the organometallic compound is copper(II) acetylacetonate. In particular, the organometallic compound is copper(II) acetylacetonate 0.1% in MMA (methyl methacrylate).

[0031] However, the organometallic compounds used can also include acetylacetone-copper, copper 4-cyclohexyl butyrate, copper acetate, copper oleate, copper gluconate, acetylacetone-manganese, manganese naphthenate, manganese octylate, acetylacetone-cobalt(III), cobalt naphthenate, acetylacetone-lithium, lithium acetate, acetylacetone-zinc, zinc naphthenate, acetylacetone-nickel, nickel acetate, acetylacetone-aluminum, acetylacetone-calcium, acetylacetone-chromium(III), acetylacetone-iron(III), sodium naphthenate and rare earth octoates, which can be used alone or in mixtures.

[0032] In an advantageous embodiment of the synthetic resin material according to the invention, the proportion of the organometallic compound and / or the organohalogen compound in component B is between 0.001 and 2 wt.%, preferably between 0.005 and 1 wt.%, and particularly preferably between 0.01 and 0.5 wt.%, each based on the total mass of component B. Particularly preferably, the proportion of the organometallic compound is 0.01–0.3 wt.% and / or the proportion of the organohalogen compound is 0.15–0.4 wt.%, each based on the total mass of component B.

[0033] Less than 0.001 wt% of the organometallic compound, based on the total mass of component B, results in insufficient reactivity to produce a rapidly self-polymerizing resin for medical molded parts. However, even at concentrations above 0.3 wt%, initial discoloration occurs, which becomes so pronounced at 2 wt% of the total mass of component B that a transparent or clear milling blank is no longer present. The discoloration is specific to the organometallic compound; for example, blue in the case of acetylacetone-copper.

[0034] A proportion of the organohalogen compound below 0.01 wt% based on the total mass of component B typically results in insufficient reactivity to obtain a rapidly self-polymerizing resin for medical molded parts. Conversely, a proportion of the organohalogen compound exceeding 0.4 wt% based on the total mass of component B can lead to significant heat generation during polymerization, potentially resulting in a reduction in the quality of the resin material. At concentrations of approximately 2 wt% based on the total mass of component B, this effect becomes so pronounced that further addition of the organohalogen compound offers no additional benefits. Furthermore, any inherent color of the organohalogen compound must be considered, as high concentrations may prevent the production of a colorless, transparent milling blank.

[0035] A possible, preferred embodiment of the resin material according to the invention provides that component B comprises only a single monomer, thereby achieving a particularly high hardness of the cured milling blank. Accordingly, a composition is preferred in which the milling blank has a Shore D hardness at 21°C-25°C of greater than 60 and / or a Shore D hardness at 36°C-38°C of greater than 70. In addition, the Young's modulus of the material is preferably greater than 520 MPa.

[0036] Another preferred embodiment of the synthetic resin material according to the invention provides that component B comprises exactly two monomers, preferably ethoxyethyl methacrylate and poly(propylene glycol) methacrylate, in a mass ratio between 4:1 and 2:1, in which case the temperature-induced memory effect is particularly pronounced. Alternatively, exactly two monomers from the group consisting of methyl methacrylate, ethyl methacrylate, ethyl acrylate, ethoxyethyl methacrylate, poly(propylene glycol) methacrylate, isobornyl acrylate, isobornyl methacrylate, and / or ethoxyethyl methacrylate are preferably used. Ethoxyethyl methacrylate as one monomer and / or poly(propylene glycol) methacrylate as the other is particularly preferred.The component B most preferably comprises as monomers exclusively ethoxyethyl methacrylate and poly(propylene glycol) methacrylate, wherein the mass ratio of the two monomers is further preferably between 5:1 and 1:1, particularly preferably between 4:1 and 2:1, most preferably between 7:2 and 5:2 and particularly preferably 3:1.

[0037] To obtain a synthetic resin material with particularly advantageous properties for manufacturing a milling blank, the mass ratio of components A and B is between 3:1 and 1:3, preferably between 2:1 and 1:2, particularly preferably between 2:3 and 3:2, and most preferably between 3:4 and 1:1. The mass ratio is limited on the one hand by the material properties of the milling blank and on the other hand by the solubility of component A in component B. However, comparative tests have shown that, due to the use of the organometallic compound and the organohalogen compound, the two components A and B can be used in a wide mixing ratio to obtain milling blanks with good material properties.

[0038] In an advantageous further development of the synthetic resin material according to the invention, the proportion of the polyethyl methacrylate polymer (PEMA), the polymethyl methacrylate (PMMA) and / or the polyethyl methacrylate-polymethyl methacrylate copolymer (PEMA-PMMA) in total in component A and / or the proportion of the at least one monomer and preferably all monomers in component B is greater than 90 wt.%, preferably greater than 95 wt.%, particularly preferably greater than 98 wt.%, very preferably greater than 99 wt.% and particularly preferably greater than 99.4 wt.%.

[0039] To better control the polymerization, one of the components A or B, preferably component A, can contain 1-benzyl-5-phenylbarbituric acid as a radical initiator, particularly in combination with the organometallic compound and / or with the organohalogen compound. However, the use of other substances as radical initiators is also possible.a polymerization promoter is conceivable, wherein a substance from the group of barbituric acids and their derivatives is preferred, for example barbituric acid, 1,3-dimethylbarbituric acid, 1,3-diphenylbarbituric acid, 1,5-dimethylbarbituric acid, 5-butylbarbituric acid, 5-ethylbarbituric acid, 5-isopropylbarbituric acid, 5-cyclohexylbarbituric acid, 1,3,5-trimethylbarbituric acid, 1,3-dimethyl-5-ethylbarbituric acid, 1,3-dimethylnbutylbarbituric acid, 1,3-dimethyl-5-isobutylbarbituric acid, 1,3-dimethyl-5-tertbutylbarbituric acid, 1,3-dimethyl-5-cyclopentylbarbituric acid, 1,3-dimethyl-,5-cyclohexylbarbituric acid, 1,3-dimethyl-5-phenylbarbituric acid, 1-Cyclohexyl-5-ethylbarbituric acid, 1-benzyl-5-phenylbarbituric acid, and thiobarbituric acids, as well as their salts. Although the radical initiator can, in principle, be used in any quantity, a proportion of component A of 0.05–3 wt.% has proven advantageous, with a quantity of 0.1–2 wt.% being particularly preferred and a quantity of 0.5–1.5 wt.% being acceptable.-% is particularly preferred. In particular, the radical starter is preferably used in an amount of 1 wt% based on the mass of component A.

[0040] Preferably, at least one of the components, particularly component B, comprises a radical scavenger, wherein 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) and / or 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxyl (4-hydroxy-TEMPO) are most preferably used. The radical scavenger is required only in small amounts, with a proportion between 0.0001 wt% and 0.01 wt%, particularly preferably between 0.0005 wt% and 0.005 wt%, most preferably between 0.001 wt% and 0.003 wt%, and especially 0.002 wt% based on the mass of component A and / or B, particularly component B, having proven to be particularly suitable.

[0041] The invention relates in principle to a synthetic resin material in which components A and / or B are free of flexibilizers and / or plasticizers. Flexibilizers from the group of phthalic acid esters, such as diethylhexyl phthalate (DEHP), the group of aliphatic esters, in particular the group of alkylsulfonic acid esters of phenol, the group of citric acid-based flexibilizers, such as triethyl citrate or, particularly preferably, 1,2-cyclohexanedicarboxylic acid diisononyl ester, or the group of adipic acid-based flexibilizers, such as diethylhexyl adipate or diethyl octyl adipate, are particularly preferred.

[0042] Furthermore, a synthetic resin material is preferred in which component A and / or B is free of tetrahydrofurfuryl methacrylate and / or tetrahydrofurfuryl acrylate, as these substances are generally considered harmful to health and, in particular, to the unborn child. Since it cannot be ruled out that these substances may remain in the product after polymerization and then be released, they should be avoided altogether.

[0043] In some cases, fillers can be used as part of the composition of the resin material or the milling blank to improve the physical properties of the polymerized / cured product. Any filler can be used for this purpose, for example, an inorganic or organic filler, or a hybrid filler. Examples of organic hybrid fillers are those obtained by pressing powdered quartz or powdered aluminum oxide, glass powder, kaolin, talc, calcium carbonate, barium aluminosilicate glass, titanium oxide, borosilicate glass, or colloidal lithium dioxide with a polymer and subsequent pulverization. Aluminum oxide, beryllium oxide, boron carbide, silicon carbide, silicon nitride, and various metals, such as chromium, copper, iron, nickel, and others, can also be used.The powdered polymers used can be, for example, polymethyl acrylate, polymethyl methacrylate, polyethyl methacrylate, a copolymer of methyl methacrylate with ethyl methacrylate, cross-linked polymethyl methacrylate, a copolymer of ethylene with vinyl acetate, a copolymer of styrene with butadiene, a copolymer of acrylonitrile with styrene, or an acrylonitrile styrene-butadiene copolymer, each of which can also be used as a mixture with the aforementioned inorganic powders or organic hybrid fillers. The filler(s) can be contained in component A and / or in component B. Nano- and / or microscale fillers, such as glass powder, glass-ceramic powder, Al and / or Si compounds, or Si-Al compounds, are particularly preferred. The type and amount of filler should preferably be selected such that the transparency of the milled blank is maintained. In particular, the use of up to 10 wt.-% of a filler based on the total mass of the milling blank is conceivable, wherein it is preferred to keep the proportion below 7.5 wt.% and in particular below 5 wt.%.

[0044] According to an advantageous further development of the invention, the material exhibits a temperature-dependent memory effect, so that the material, in particular of a finished dental splint or ear mold, returns to its original shape after deformation by heating, in particular to a temperature of 37 °C.

[0045] According to an advantageous further development of the process, curing takes place at a temperature between 30 °C and 70 °C, preferably between 40 °C and 60 °C and particularly preferably between 45 °C and 55 °C and / or for a duration of 20 - 90 minutes, preferably 30 - 60 minutes and particularly preferably 45 minutes, whereby a ready-to-use milling blank can be obtained without significant energy expenditure.

[0046] According to a further advantageous embodiment of the process, curing takes place in a pressure pot at an internal pressure of at least 3 bar, preferably at least 4 bar and / or at most 6 bar, preferably at most 5 bar and in particular preferably exactly 4 bar, thereby ensuring rapid and bubble-free curing.

[0047] A number of embodiments of the invention are explained in more detail below.

[0048] A first embodiment of a synthetic resin material for milling blanks for the production of medical technology molded parts is made from two components A and B, the compositions of which are shown in the following table, wherein the synthetic resin material is particularly advantageous as containing neither tetrahydrofurfuryl methacrylate nor tetrahydrofurfuryl acrylate, being flexible yet not easily broken, being completely clear and exhibiting a temperature-induced memory effect. Component A Mass fraction, % Polyethylene methacrylate 99 1-Benzyl-5-phenylbarbituric acid 1 Component B Mass fraction, % Ethoxyethyl methacrylate approx. 73.5 Poly(propylene glycol) methacrylate 26 Dilauryldimethyl ammonium chloride 0,33 1% copper(II) acetylacetonate solution in MMA 0,17 2,2,6,6-Tetramethylpiperidinyloxyl 0,002

[0049] The two components according to the invention are mixed in the ratio A:B = 100:75 and then cured in a pressure pot at 50°C and 4 bar for 45 minutes in a silicone mold, ensuring a bubble-free curing process. This yields a milling blank with a diameter of approximately 100 mm and a thickness of approximately 16–20 mm. The dimensions can be adjusted as required.

[0050] This is followed by the production of medical technology molded parts based on 3-dimensional data by milling.

[0051] To test the material properties of the milled blank, test specimens measuring 5 × 5 × 80 mm were milled and then tempered at room temperature and at 37 °C for 24 hours. Finally, the test specimens were bent at a 90° angle in the center. The relaxation of the angle was subsequently observed over time at the two aforementioned temperatures to demonstrate the temperature-dependent memory effect. For the first embodiment of the resin composition, a temperature-dependent memory effect was demonstrated, as the test specimen deformed at room temperature returned essentially completely to its original shape after being heated to 37 °C.

[0052] For a second, non-inventive embodiment of a synthetic resin material for milling blanks for the production of medical device molded parts, two components A and B are mixed, the compositions of which are shown in the following table, wherein the synthetic resin material advantageously contains neither tetrahydrofurfuryl methacrylate nor tetrahydrofurfuryl acrylate, is flexible and at the same time not easily broken, is particularly hard for subsequent milling (Shore-D at 21-25°C > 60, Shore-D at 36-38°C > 70°C, E-modulus > 520 MPa, Fm max. force > 28 N), is completely clear and has a temperature-induced memory effect. Component A Mass fraction, % Polyethylene methacrylate 99 1-Benzyl-5-phenylbarbituric acid 1 Component B Mass fraction, % Ethoxyethyl methacrylate 99,63 Dilauryldimethyl ammonium chloride 0,2 1% copper(II) acetylacetonate solution in MMA 0,17 2,2,6,6-Tetramethylpiperidinyloxyl 0,002

[0053] As with the synthetic resin composition of the first embodiment, a milling blank and subsequently a test specimen were produced, which was then used to demonstrate the temperature-induced memory effect.

[0054] Further comparative tests were carried out in which the polyethylene methacrylate polymer (PEMA) of component A was replaced by polymethyl methacrylate (PMMA) and by polyethylene methacrylate-polymethyl methacrylate copolymer (PEMA-PMMA). It was found that this replacement had only a minor influence on the temperature-induced memory effect, the clarity of the milling blank, and its machinability.

[0055] In a third embodiment of a synthetic resin material for milling blanks for the production of medical technology molded parts, which is also not in accordance with the invention, two components A and B are mixed, the compositions of which are shown in the following table, wherein in component B, in addition to ethoxyethyl methacrylate, methyl methacrylate, ethyl methacrylate, ethyl acrylate, ethoxyethyl acrylate, isobornyl acrylate or isobornyl methacrylate were used as the second monomer. Component A Mass fraction, % Polyethylene methacrylate 99 1-Benzyl-5-phenylbarbituric acid 1 Component B Mass fraction, % Ethoxyethyl methacrylate approx. 73.5 Second monomer 26 Dilauryldimethyl ammonium chloride 0,33 1% copper(II) acetylacetonate solution in MMA 0,17 2,2,6,6-Tetramethylpiperidinyloxyl 0,002

[0056] In each case, a millable blank was obtained which was clear and exhibited a temperature-induced memory effect, but which, compared to the composition of the first embodiment of the invention, showed a lower and / or significantly slower relaxation to the original position after deformation, so that these embodiments are possible, but not preferred.

[0057] Furthermore, in comparative tests, the dilauryldimethylammonium chloride was replaced with lauryldimethylbenzylammonium chloride, tetra-n-butylammonium chloride, trioctylmethylammonium chloride, benzyldimethylcetylammonium chloride and benzyldimethylstearylammonium chloride, each yielding a millable blank with a temperature-induced memory effect.

Claims

[1] Synthetic resin material for producing a milling blank for medical-technical molded parts, consisting of two components A and B, wherein the first component A comprises at least one polyethyl methacrylate polymer (PEMA), polymethyl methacrylate (PMMA) and / or polyethyl methacrylate-polymethyl methacrylate copolymer (PEMA-PMMA), and the second component B - as monomer at least poly(propylene glycol) methacrylate, - an organometallic compound as a polymerization promoter, and - an organohalogen compound or dilauryldimethylammonium chloride as polymerization promoter, wherein - components A and B are free from flexibilizers and / or plasticizers. [2] Synthetic resin material for producing a milling blank according to at least one of the preceding claims, characterized by that the organometallic compound is copper(II) acetylacetonate. [3] Synthetic resin material for producing a milling blank according to at least one of the preceding claims, characterized by that the proportion of the organometallic compound and / or the organohalogen compound in component B is between 0.01 and 0.5 wt.%. [4] Synthetic resin material for producing a milling blank according to at least one of the preceding claims, characterized by that the Shore-D hardness at 21°C-25°C is greater than 60 and / or the Shore-D at 36°C-38°C is greater than 70°C. [5] Synthetic resin material for producing a milling blank according to at least one of the preceding claims, characterized by that component B comprises ethoxyethyl methacrylate and poly(propylene glycol) methacrylate in a mass ratio between 4:1 and 2:

1. [6] Synthetic resin material for producing a milling blank according to at least one of the preceding claims, characterized by that the mass ratio of components A and B is between 2:1 and 1:

2. [7] Synthetic resin material for producing a milling blank according to at least one of the preceding claims, characterized by that the proportion of the polyethyl methacrylate polymer (PEMA), the polymethyl methacrylate (PMMA) and / or the polyethyl methacrylate-polymethyl methacrylate copolymer (PEMA-PMMA) in total in component A and / or the proportion of all monomers in component B is greater than 95 wt.%. [8] Synthetic resin material for producing a milling blank according to at least one of the preceding claims, characterized by that component A contains 1-benzyl-5-phenyl-barbituric acid as a radical initiator. [9] Synthetic resin material for producing a milling blank according to at least one of the preceding claims, characterized by that components A and B are free from tetrahydrofurfuryl methacrylate and / or tetrahydrofurfuryl acrylate. [10] Milling blank for producing medical-technical molded parts from a synthetic resin material according to at least one of claims 1-9. [11] A method for producing a milling blank from a synthetic resin material for medical molded parts, comprising the steps: - producing or selecting a component A comprising at least one polyethyl methacrylate polymer (PEMA), one polymethyl methacrylate (PMMA) and / or one polyethyl methacrylate-polymethyl methacrylate copolymer (PEMA-PMMA), - preparing or selecting a component B comprising at least poly(propylene glycol) methacrylate as monomer, an organometallic compound as polymerization promoter and an organohalogen compound or dilauryldimethylammonium chloride as polymerization promoter, wherein components A and B are free from flexibilizers and / or plasticizers, - Mixing components A and B and dissolving component A in component B, and - Curing the mixture.