3D printed product

Abstract

The invention provides a 3D printed product. The invention relates to a 3D printed product based on urethane-acrylate-resin. The 3D printed product is at a color distance [delta] Elt from the L * a * b * coordinate of a color number starting from 3 in an RAL color card; 20, comprising dissolved therein at least one red pyrenone dye selected from the group consisting of 8, 9, 10, 11-tetrachloro-12H-phthalazin-12-one and / or 14H-benzo [4, 5] isoquinolino [2, 1-a] peridiazobenzene-14-one, involving the use of said red pyrenone dye for producing, by photopolymerization, a color distance [Delta] E lt from the L * a * b * coordinate of the color number beginning in "3" in the RAL color card; the present invention relates to the use of a 3D printed product having at least one component selected from 8, 9, 10, 11-tetrachloro-12H-phthalazin-12-one and / or 14H-benzo [4, 5] isoquinolo [2, 20], and to a method for producing a 3D printed product by means of at least one component selected from 8, 9, 10, 11-tetrachloro-12H-phthalazin-12-one and / or 14H-benzo [4, 5] isoquinolo [ The invention relates to a method for improving the light resistance and color characteristics of a photopolymerizable composition based on carbamate-acrylate-resin and a 3D printed product based on the composition by using a red pyrenone dye based on 1, 1-a]-naphthyridine-14-ketone. The invention further relates to a method for improving the light resistance and color characteristics of the photopolymerizable composition based on the carbamate-acrylate-resin and the 3D printed product based on the composition.

Description

Technical Field

[0001] The present invention relates to a 3D printing product based on a urethane-acrylate resin, wherein the color distance ΔE of the urethane-acrylate resin from the L*a*b* coordinates of a color number starting with "3" in the RAL color chart is less than 20, the urethane-acrylate resin comprises at least one red pyrene dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one dissolved therein, and the red pyrene dye is used for producing, by photopolymerization, a 3D printing product having a color distance ΔE of less than 20 from the L*a*b* coordinates of a color number starting with "3" in the RAL color chart. The present invention relates to a method for improving the light fastness and color properties of a photopolymerizable urethane-acrylate resin-based composition and a 3D-printed product based on the composition by means of at least one red pyrenone dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one dissolved therein. Background Art

[0002] Color masterbatches contain colorants in dispersed or dissolved form. The color or hue of plastic products serves, among other things, as a distinguishing feature of a company or a specific product, as a protective component, as a safety feature, or as a functional additive. Amorphous plastics such as polystyrene, polycarbonate, and polymethyl methacrylate, where transparency must be maintained, require the use of polymer-soluble dyes. Compared to pigments, colorants used for 3D printing via photopolymerization are preferably soluble in the plastic resin being processed and do not exist in colloidal form.

[0003] 3D printing is an additive manufacturing method. This refers to a process in which a component is built layer by layer by depositing material based on digital 3D design data. Therefore, for the purposes of this article, "3D printing" will be used as a synonym for additive manufacturing. However, additive manufacturing better describes a production process that differs significantly from conventional subtractive manufacturing methods. For example, additive manufacturing does not mill a workpiece from a solid block, but rather builds a component layer by layer from material available, for example, in fine powder form. A variety of metals, plastics, and composite materials are available as materials.

[0004] Meanwhile, 3D printing has established itself as a manufacturing method in numerous fields and industries. This method offers impressive advantages not achievable with other conventional methods, including for the construction of demonstration and functional prototypes, small and medium-sized series production, and, increasingly, large-scale production. For example, product development and market launch can be significantly accelerated, and product personalization or functional integration can be achieved in a shorter timeframe and often at a lower cost. For major original equipment manufacturers (OEMs) across a wide range of industries, additive manufacturing through 3D printing offers market differentiation opportunities in terms of new customer benefits, cost-reduction potential, and sustainability goals. In 3D printing, products are created by selectively shaping a material suitable for the respective printing technology into the desired shape, layer by layer, in an automated process. An original equipment manufacturer, or OEM, is a manufacturer of parts or products that does not actually place them on the retail market; in the automotive industry, the term "OEM" is used synonymously with the vehicle manufacturer.

[0005] There are various 3D printing processes for plastics. These include processes in which the plastic is produced only by curing during printing. One example is 3D printing based on photopolymerization, in which a photocurable resin liquid is applied layer by layer and subjected to a photocuring process / polymerization or photoinduced curing by the use of light. The selective layer-by-layer curing of the liquid resin is achieved by spatially confined, precisely defined, and computer-controlled exposure of the resin to light within a spectral range suitable for initiating the photopolymerization process. UV, visible, or infrared light are particularly suitable. The photopolymerization-based 3D printing process according to the present invention is preferably stereolithography (SLA) or digital light processing (DLP). In both 3D printing variants, the corresponding apparatus setup consists of a light source (through which light exposure can be applied from above or below, so-called "top-down" or "bottom-up" printing), a resin reservoir, and a platform on which the layer-by-layer curing of the plastic resin to be used for 3D printing occurs. In SLA 3D printing, the surface to be cured is exposed to light point by point by scanning with a laser beam; in DLP processes, exposure occurs over the entire surface to be exposed, typically using an LCD (liquid crystal display) panel. During a typical printing operation, the printing platform is immersed in resin from a resin reservoir while the exposure process runs and layers are created. Repeated layer creation ultimately produces the 3D printed product. In the SLA process, stereolithography printers use lasers to create 3D printed products. To do this, a plastic solution that cures under UV light is applied. The corresponding 3D printers are referred to as SLA 3D printers or DLP 3D printers. A comparison of the two technologies, as well as suppliers of the corresponding 3D printers, can be found in the review article: 3Dnatives, Regina P. April 8, 2021, at https: / / www.3dnatives.com / de / sla-vs-dlp-3d-druck-080420211 /

[0006] US 2011 / 0070976 A1 describes a golf ball comprising a core, at least one layer surrounding the core, and a fluorescent pigment color layer applied to the outermost surface of the casing. The outermost layer may be composed of a thermoplastic polyurethane material (Pandex® T8290 or Pandex® T8283). Solvent Red 149 (Sumiplast® Red HFG) and Solvent Red 150 (Sumiplast® HF4G) are used as red fluorescent anthraquinone dyes in the outermost color layer. This ball exhibits excellent spin performance and durability, and its appearance is characterized by excellent visibility, stylishness, and luxury, as well as excellent weather resistance.

[0007] US 2019 / 0201171 A1 discloses a colored curable composition for use in an additive manufacturing method, wherein the composition comprises the following: a curable resin composition comprising a radiation-curable component, a photoinitiator, and a dye composition comprising a dye D1 and a dye D2, wherein dye D1 has a maximum light absorption in the wavelength range of 400 to 530 nm, and dye D2 has a maximum light absorption in the wavelength range of 540 to 650 nm. As an example, two anthraquinone dyes are used: CI Solvent Red 111, CAS No. 82-38-2 (Dye 1) and CI Solvent Violet 13, CAS No. 81-48-1 (Dye 2). The patent also describes an S30 3D printer (Rapid Shape GmbH, Heimsheim, Germany), which uses a wavelength of 405 nm and an intensity of 50 mW / cm 2 The LED light was applied for 11 seconds per layer.

[0008] In addition to favorable color properties during and immediately after the photopolymerization process for producing 3D-printed products, the in-use characteristics of such 3D-printed products must also be considered. The colorants used in the aforementioned prior art have proven disadvantageous due to color changes during the 3D manufacturing process due to exposure to the light required for photopolymerization. However, light sensitivity / light resistance is a hallmark of colored 3D-printed products produced via photopolymerization-based 3D printing. Fading, discoloration, or even browning of 3D-printed products produced via photopolymerization-based 3D printing should be avoided whenever possible.

[0009] Furthermore, during photopolymerization, preferably by SLA or DLP processes, colorants intended for 3D printing should maintain their advantageous performance characteristics and should not impair or even prevent the curing / polymerization of the 3D printed product. For the purposes of the present invention, advantageous performance characteristics in dyes for 3D printing according to the present invention are the creation of desired / defined hues and the creation of pure, vibrant colors.

[0010] The problem to be solved by the present invention is therefore to provide a red dye for 3D printing by photopolymerization, in particular by photopolymerization using the SLA or DLP method, which, due to its solubility in the plastic to be processed, allows the creation of a defined red shade, remains light-fast during the printing process and also maintains its color properties compared to Solvent Red 111 as used in US 2019 / 0201171 A1, which in the context of the present invention is described as an improvement in light fastness and color properties determined in accordance with DIN EN ISO 4892-2.

[0011] Method for evaluating light fastness

[0012] To determine the light fastness of dyes used in photopolymerization-based 3D printing, test specimens in the form of cuboids of colored resin were produced for the purposes of this invention. These specimens had dimensions of length = 60 mm, width = 40 mm, and height = 2 mm, and a dye concentration of 0.02% in the resin. These test specimens were then exposed to light (xenon arc) for 95–100 hours in the immediately printed state using a Xenotest Beta+ apparatus (Atlas Material Testing Technology GmbH, Linsengerich-Altenhaßlau, Germany) in accordance with DIN EN ISO 4892-2. Light fastness was evaluated colorimetrically by recording the transmission spectra of the exposed test specimens using an X-Rite Ci7800 sphere spectrophotometer (X-Rite GmbH, Planegg-Martinsried, Germany) with the following settings selected: measurement geometry = d / 8°; spectral interval = 10 nm; spectral range = 360–750 nm. Based on the obtained transmission spectrum, the manufacturer's sphere spectrophotometer software then calculates colorimetric data using the following settings: Illuminant / Observer = D65 / 10°; Color Space = L*a*b*C*h°. Lightfastness evaluation is based on the color distance ΔE between the light-exposed test sample and the corresponding unexposed test sample in the L*a*b*C*h° color space. The larger the color distance, the greater the change in color perception caused by light exposure, and therefore the poorer the lightfastness. ΔE is classified based on a comparison with other dyes of similar hues (so-called non-inventive examples), whose lightfastness in other applications, particularly for mass coloration of plastics, is generally rated as good according to the manufacturer's data.

[0013] Method for evaluating the stability of color characteristics

[0014] In order to determine the changes in the spectral properties that determine the color characteristics of the dyes, for the purposes of the present invention, the absorption spectra of the colored resins under investigation were compared before and after light-induced curing.

[0015] To this end, the colored resins produced as described above in the "Method for Evaluating Lightfastness" section were transferred to quartz glass cuvettes with a width of 1 cm, and the absorption spectra were recorded in transmission mode over a wavelength range of 360 to 750 nm using an X-Rite Ci7800 instrument (X-Rite GmbH, Planegg-Martinsried, Germany). These absorption spectra were then corrected for the absorbance of the corresponding colorless resin by performing identical measurements with the colorless resin. Similarly, the absorption spectra of the colored test samples were recorded and corrected in transmission mode, and in each case the spectrum was normalized to the path length of the cuvette / test sample in question.

[0016] Finally, the similarity of the absorption spectra before and after 3D printing was calculated from the measured data by calculating the correlation coefficient R of the normalized absorption (spectral spacing of 10 nm). The larger the value of R, the greater the similarity of the absorption spectra, and the more stable the color characteristics of the dye used for photopolymerization-based 3D printing and suitable for the purposes of the present invention are expected to be. Summary of the Invention

[0017] The solution to this problem and the subject matter of the present invention are 3D-printed products having a color distance ΔE of <20 from the L*a*b* coordinates of the color numbers starting with "3" on the RAL color chart, which are based on a photopolymerizable composition comprising at least one urethane acrylate resin and at least one red pyrene dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one dissolved therein.

[0018] The present invention also provides the use of at least one red pyrene dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one in dissolved form for improving the light fastness and color properties of photopolymerizable urethane-acrylate resin-based compositions and 3D printed products produced therefrom, as determined in accordance with DIN EN ISO 4892-2, wherein the color distance ΔE of these compositions and 3D printed products from the L*a*b* coordinates of the color numbers starting with "3" on the RAL color chart is less than 20. The improvement in light fastness and color properties was measured by recording the transmission spectra of test samples of the corresponding colored urethane acrylate resin before and after light-induced curing using a sphere spectrophotometer, then correcting for the absorbance of the corresponding colorless resin and normalizing for the path length of the cuvette / test sample under investigation, and finally determining the similarity of the absorption spectra before and after 3D printing from the measured data by calculating the correlation coefficient R of the normalized absorbance.

[0019] The present invention further relates to a method for improving the light fastness and color properties of photopolymerizable urethane acrylate resin-based compositions and 3D-printed products produced therefrom, as determined in accordance with DIN EN ISO 4892-2, by dissolving at least one red pyrene dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one in a urethane acrylate resin, wherein the color distance ΔE of the L*a*b* coordinates of these compositions and 3D-printed products to a color number starting with "3" on the RAL color chart is less than 20. The improvement in light fastness and color properties was measured by recording the transmission spectra of test samples of the corresponding colored urethane acrylate resin before and after light-induced curing using a sphere spectrophotometer, then correcting for the absorbance of the corresponding colorless resin and normalizing for the path length of the cuvette / test sample under investigation, and finally determining the similarity of the absorption spectra before and after 3D printing from the measured data by calculating the correlation coefficient R of the normalized absorbance.

[0020] Finally, the present invention also relates to a method for additive manufacturing of 3D-printed products in a SLA 3D printer or DLP 3D printer based on photopolymerization by using a composition based on a urethane-acrylate resin containing at least one red pyrenone dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one in dissolved form, wherein the color distance ΔE of the L*a*b* coordinates of these 3D-printed products to the color numbers starting with "3" on the RAL color chart is less than 20.

[0021] For the sake of clarity, it should be noted that the scope of the present invention encompasses all definitions and parameters mentioned below in general or specified in the preferred ranges in any desired combination. This also applies to the combination of the individual components in the amounts described in connection with the claimed methods and uses. Unless otherwise stated, the standards cited in the context of this application relate to the versions current at the filing date of the present invention. Unless otherwise stated, percentage values ​​are percentages by weight.

[0022] Table 1 RAL color card

[0023] In the context of the present invention, red is understood to mean a color having a color number starting with "3" in the RAL color system according to https: / / de.wikipedia.org / wiki / RAL-Farbe#Rot. More specifically, at the filing date of the present invention, the following distinction is made between red hues:

[0024]

[0025] This table shows the device-independent CIE L*a*b* color values ​​for each RAL red value: L* represents lightness, a* describes the color's position on the red-green axis, and b* describes the color's position on the yellow-blue axis, using D65 standard light and a 10° field of view for a standard observer. The color model is standardized in EN ISO 11664-4, "Colorimetry - Part 4: CIE 1976 L*a*b* Color space." For more information on the L*a*b* color space (also: CIELAB), see: https: / / de.wikipedia.org / wiki / Lab-Farbraum. Each color in the color space is defined by its position with Cartesian coordinates {L*, a*, b*}. The a*b* coordinate plane is constructed using the theory of opponents. Green and red are at opposite ends of the a* axis, while the b* axis runs from blue to yellow. Complementary hues are in each case 180° opposite each other; all achromatic colors are located in the middle (coordinate origin a* = 0, b* = 0).

[0026] The L* axis describes the lightness (brightness) of a color, with values ​​ranging from 0 to 100. In the diagram, it is positioned perpendicular to the a*b* plane at the origin. Since all achromatic colors (gray tones) are contained between the endpoints of black (L* = 0) and white (L* = 100), it is also called the neutral gray axis. The a* axis describes the green or red component of a color, with negative values ​​representing green and positive values ​​representing red. The b* axis describes the blue or yellow component of a color, with negative values ​​representing blue and positive values ​​representing yellow.

[0027] The a* value ranges from approximately -170 to +100, and the b* value ranges from -100 to +150, with the maximum value only reached at medium brightnesses for certain hues. The CIELAB color entity has its maximum range in the medium brightness region, but this varies in height and size depending on the color range.

[0028] However, according to the present invention, red-like hues are also included, which have a color distance ΔE < 20 from the L*a*b* coordinates of the red color number starting with "3" in the RAL color chart. DETAILED DESCRIPTION

[0029] Preferred embodiments of the present invention

[0030] Preferably, the photopolymerizable urethane-acrylate resin-based composition used according to the present invention and the 3D printed product produced therefrom have a color distance ΔE < 10 from the L*a*b* coordinates of the red color number starting with "3" in the RAL color card.

[0031] Particularly preferably, the photopolymerizable urethane-acrylate resin-based composition used according to the present invention and the 3D printed product produced therefrom have a color distance ΔE < 5 from the L*a*b* coordinates of the red color number starting with "3" in the RAL color card.

[0032] Preferably, the present invention relates to 3D printed products, wherein the color distance ΔE of the L*a*b* coordinates of these 3D printed products to the color numbers starting with "3" in the RAL color chart is less than 20, based on a photopolymerizable composition for additive manufacturing of products by 3D printing, wherein these photopolymerizable compositions contain at least one urethane acrylate resin and at least one red pyrene dye selected from 8,9,10,11-tetrachloro-12H-phthalpyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one dissolved therein.

[0033] Preferably, the present invention relates to a method for improving the light fastness and color properties of photopolymerizable urethane acrylate resin-based compositions and 3D-printed products produced therefrom, as determined in accordance with DIN EN ISO 4892-2, by using at least one red pyrene dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one dissolved in a urethane acrylate resin, by means of additive manufacturing in 3D printing, wherein the color distance ΔE of the L*a*b* coordinates of these compositions and 3D-printed products to the color numbers starting with "3" on the RAL color chart is less than 20.

[0034] Preferably, the present invention relates to the use of at least one red pyrene dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one in dissolved form for increasing the light fastness and color properties, determined according to DIN EN ISO 4892-2, of photopolymerizable compositions based on urethane-acrylate resins and 3D-printed products produced therefrom by means of additive manufacturing in 3D printing, wherein the color distance ΔE of these compositions and 3D-printed products from the L*a*b* coordinates of the color numbers starting with "3" on the RAL color chart is <20.

[0035] The present invention preferably relates to 3D-printed products, uses according to the invention, and methods according to the invention for improving the lightfastness and color properties of 3D-printed products, wherein 0.005 to 5 parts by mass of at least one red pyrone dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one is present in dissolved form per 20 to 99.995 parts by mass of a urethane-acrylate-based resin, the resin preferably containing at least one additive. Preferably, the solubility of the red pyrone dye in the urethane-acrylate-based resin is at least 0.05 g / L at 23°C according to DIN EN ISO 7579:2010 DE.

[0036] In addition to the at least one red pyrene dye, particular preference is given to using 0.5 to 10 parts by mass of a photoinitiator, which preferably absorbs in the wavelength range of 300 to 450 nm.

[0037] In addition to at least one red pyrene dye and 0.5 to 10 parts by mass of a photoinitiator, very particular preference is given to using 0.001 to 1 part by mass of at least one additive, preferred additives for the purposes of the present invention being at least one leveling agent, at least one stabilizer, at least one additional dye other than 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one, at least one filler or at least one organic pigment.

[0038] Urethane-acrylate based resins

[0039] Preferred photopolymerizable urethane-acrylate resins according to the present invention, in particular for additive manufacturing by photopolymerization in 3D printing, are based on polyurethane acrylates [CAS No. 82116-59-4], polyether urethane acrylates, or urethane acrylate resins. Reference should be made to WO 2005 / 028532 A1, RU 2546966 C1, or M. Alishiri et al., Materials Science and Engineering: C, Vol. 42, September 2014, pp. 763-773.

[0040] Used in the context of the present invention and therefore particularly preferred are:

[0041] "3D Printing UV-Sensitive Transparent Resin" from Shenzhen Anycubic Technology Co., Ltd., China; a colorless resin for high-speed, light-induced 3D printing containing 30%-60% polyurethane acrylate (CAS No. 82116-59-4); 10%-40% isooctyl acrylate (CAS No. 29590-42-9); and 2%-5% photoinitiator.

[0042] Addigy® LPU Rigid 341-02 IM from Covestro Deutschland AG, Leverkusen, Germany; a colorless aliphatic polyether urethane acrylate resin for light-induced 3D printing, optimized for high mechanical stress and strength (< 25% isobornyl methacrylate (CAS 7534-94-3); approximately 10% 4-(1-oxo-2-propenyl)morpholine (CAS No. 5117-12-4); < 0.15% methacrylic acid (CAS No. 79-41-4) / 2-hydroxyethyl methacrylate (CAS No. 868-77-9));

[0043] Ultracur3D® FL 300 from BASF 3D Printing Solutions GmbH, Ludwigshafen, Germany; a colorless reactive urethane acrylate resin for light-induced 3D printing optimized for high torsional flexibility and high break strength (1%-3% diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, CAS No. 75980-60-8; 15%-20% isodecyl acrylate, CAS No. 1330-61-6; 5%-10% exo-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl acrylate, CAS No. 5888-33-5; 25%-50% 3-vinyl-5-methyl-2-oxazolidinone, CAS No. 3395-98-0).

[0044] The photopolymerizable resin used according to the present invention preferably comprises, in addition to at least one red pyrene dye, a mixture of at least one polymerizable acrylate monomer and / or prepolymer (preferably a (poly)urethane acrylate), at least one photoinitiator, and at least one additive. Regarding such additives, reference should generally be made to WO 2018 / 038954 A1, the contents of which are incorporated herein in their entirety. Preferred photoinitiators and additives are listed below.

[0045] Photoinitiator

[0046] The photoinitiators that can be used according to the invention are generally characterized by one or more of the following features,

[0047] - one or more absorption bands in the wavelength range from 300 to 450 nm and / or a solubility in the curable composition of at least 2 g / l at 23°C;

[0048] - solubility in the radiation-curable components of the curable resin composition and / or in the additives optionally present;

[0049] - The ability to form polymerization-inducing species (eg, free radicals) when exposed to light energy having a wavelength between 300 and 450 nm.

[0050] According to the invention, it is particularly preferred to use at least one photoinitiator from the following group: 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate.

[0051] additive

[0052] The photopolymerizable resin composition useful for 3D printing according to the present invention may preferably comprise at least one additive, stabilizer, or a mixture thereof.

[0053] In particular, adding stabilizers to the curable composition can help improve the resolution and accuracy of the SLA process by reducing or preventing undesirable scattering effects, and can also help extend the shelf life of the curable composition. Such stabilizers typically contain phenolic units. Preferred are p-methoxyphenol (MOP), hydroquinone monomethyl ether (MEHQ), 2,6-di-tert-butyl-4-methylphenol (BHT; Ionol), phenothiazine, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO), or mixtures thereof. Such one or more stabilizers are preferably used in the following amounts:

[0054] •Lower limit: at least 0.001%, or at least 0.005%, or at least 0.01% by weight;

[0055] • Upper limit: not more than 0.02%, or not more than 0.05%, or not more than 0.5%, or not more than 1% by weight;

[0056] • Range: 0.001% to 1%, or 0.005% to 0.05% by weight;

[0057] Wherein the % by weight is based on the weight of the curable composition.

[0058] Pyrene dye

[0059] The red pyrene dyes to be used according to the invention, selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one, are characterized by the following features:

[0060] •Molecular weight in the range of 50-1000 g / mol

[0061] • a solubility in the range of at least 0.05 g / L at 23°C in a urethane-acrylate resin-based composition to be cured and used for 3D printing

[0062] • Maximum light absorption in the wavelength range of 400 to 530 nm

[0063] • Very good light resistance in 3D products

[0064] •Highly stable color properties during the curing process

[0065] •Contains at least one pyrenone unit.

[0066] 8,9,10,11-Tetrachloro-12H-phthalopyrin-12-one is known as Solvent Red 135 (CAS No. 20749-68-2) and is available from LANXESS Deutschland GmbH, Cologne, Germany.

[0067] 14H-Benzo[4,5]isoquinolino[2,1-a]perylene-14-one is known as Solvent Red 179 (CAS No. 6829-22-7) and is also available from LANXESS Germany GmbH, Cologne, Germany.

[0068] DIN EN ISO 7579:2010 DE

[0069] This international standard specifies two methods for determining the solubility of dyes in organic solvents. They can be used for dyes that do not undergo chemical changes under the influence of the solvent and are stable and non-volatile under the specified drying conditions. The gravimetric method is recommended for low-boiling-point solvents (below 120°C), and the photometric method is recommended for high-boiling-point solvents (above 120°C). The method should be selected based on the specific problem at hand. These methods are primarily suitable for concentrations between 1 g and 1000 g of dye per liter of solvent, but can also be used to determine higher solubilities, provided that, in the case of the gravimetric method, the viscosity of the test batch does not rise to a level that would render the homogenization and centrifugation method unsuitable. According to DIN EN ISO 7579:2010 DE, the solubility of the at least one red pyrene dye used according to the present invention in a composition based on a urethane-acrylate resin to be cured and used for 3D printing is preferably at least 0.05 g / L at 23°C.

[0070] The method for increasing the light resistance and color properties of a photopolymerizable urethane-acrylate resin-based composition, determined in accordance with DIN EN ISO 4892-2, is preferably used for the additive production of 3D-printed products by photopolymerization, preferably for the additive production of 3D-printed products using an SLA 3D printer or a DLP 3D printer based on photopolymerization.

[0071] Furthermore, the present invention accordingly relates to a method for additively producing 3D-printed products in a SLA 3D printer or a DLP 3D printer based on photopolymerization by using a composition based on a urethane-acrylate resin containing at least one red pyrenone dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one, wherein the color distance ΔE of the L*a*b* coordinates of these 3D-printed products to the color numbers starting with "3" on the RAL color chart is less than 20.

[0072] Examples

[0073] Method for determining the lightfastness of dyes in 3D printing

[0074] To determine the lightfastness of dyes in 3D printing, test samples made of a colored resin with a dye concentration of 0.02% by weight in the resin were produced for the purposes of this invention. As test samples, rectangular parallelepipeds with the following dimensions were produced from the colored resin by 3D printing.

[0075] • Length 60 mm

[0076] • Width 40 mm

[0077] • Height 2 mm

[0078] The test specimens were exposed to light (xenon lamp) for 95–100 h using a Xenotest Beta+ apparatus (Atlas Material Testing Technology GmbH, Linsengerich-Altenhaßlau, Germany) according to DIN EN ISO 4892-2.

[0079] Light fastness was evaluated colorimetrically. This was done using an X-Rite Ci7800 sphere spectrophotometer (X-Rite GmbH, Planegg-Martinsried, Germany) to record the transmission spectra of the test specimens exposed to light. The following settings were selected for this purpose:

[0080] • Measurement geometry d / 8°

[0081] • Spectral spacing 10 nm

[0082] • Spectral range 360-750 nm

[0083] From the transmission spectra, the manufacturer's sphere spectrophotometer software calculated the colorimetric data using the following settings:

[0084] • Illuminant / Observer D65 / 10°

[0085] • Color space L*a*b*C*h°

[0086] The basis for lightfastness evaluation is the color distance ΔE in the L*a*b*C*h° color space between a light-exposed test sample and a corresponding unexposed test sample. The larger the color distance, and therefore the ΔE, the greater the change in color perception caused by exposure to light, and therefore the poorer the lightfastness. ΔE is classified based on a comparison with non-inventive red dyes (see non-inventive examples), whose lightfastness in other applications (e.g., mass coloration of plastics) is generally rated as good according to manufacturer's data.

[0087] Table 2: Evaluation of light resistance

[0088]

[0089] *Compared to the average ΔE of non-inventive examples

[0090] Method for evaluating the stability of color characteristics

[0091] To determine the changes in the spectral properties that determine the color characteristics of the dyes, the absorption spectra of the colored resins were compared before and after light-induced curing.

[0092] The colored resin, produced as described previously, was transferred to a quartz glass cuvette with a width of 1 cm. Absorption spectra were then recorded in transmission mode using an X-Rite Ci7800 instrument (X-Rite GmbH, Planegg-Martinsried, Germany) in the wavelength range of 360 to 750 nm. These spectra were corrected for the absorbance of the corresponding colorless resin by performing identical measurements with the colorless resin. Similarly, the absorption spectra of the colored test samples were recorded and corrected in transmission mode. In each case, the spectra were normalized to the path length of the cuvette / test sample.

[0093] The measured data is then used to calculate the similarity of the absorption spectra before and after 3D printing. This is accomplished by calculating the correlation coefficient R of the normalized absorption (spectral spacing of 10 nm). The larger the value of R, the greater the similarity of the absorption spectra, and therefore the more stable the color properties of the dye during 3D printing.

[0094] Table 3: Evaluation of stability / retention of color characteristics

[0095]

[0096] Colored 3D prints were produced and tested according to the method described above in three resin compositions (see Materials) with different properties. In resin composition 1, a dye mixture was also investigated by way of example.

[0097] Table 4: Inventive Examples of Red Pyrene Dyes in Resin Composition 1

[0098]

[0099] Table 5: Non-inventive examples of various red dyes in resin composition 1

[0100]

[0101] Table 6: Inventive Examples of Red Pyrene Dyes in Resin Composition 2

[0102]

[0103] Table 7: Non-inventive examples of various red dyes in resin composition 2

[0104]

[0105] Table 8: Inventive Examples of Red Pyrene Dyes in Resin Composition 3

[0106]

[0107] Table 9: Non-inventive examples of various dyes in resin composition 3

[0108]

[0109] reactants

[0110] Table 10: Materials used and sources of supply

[0111] .

Claims

1. 3D printed products having a color distance ΔE of less than 20 from the L*a*b* coordinates of a color number starting with "3" on the RAL color chart, wherein the 3D printed products are based on a photopolymerizable composition comprising at least one urethane acrylate resin and at least one red pyrene dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one dissolved therein.

2. The 3D printed product according to claim 1, characterized in that: The photopolymerizable urethane-based resin is based on urethane acrylate, polyurethane acrylate, or polyether urethane acrylate.

3. The 3D printed product according to claim 1 or 2, characterized in that: At least one red pyrene dye is used in an amount of 0.005 to 5 parts by mass per 20 to 99.995 parts by mass of the urethane-acrylate based resin.

4. The 3D printed product according to claim 3, characterized in that: In addition to the at least one red pyrene dye, 0.5 to 10 parts by mass of a photoinitiator are used.

5. The 3D printed product according to claim 4, characterized in that: The photoinitiator absorbs in the wavelength range of 300 to 450 nm.

6. The 3D printed product according to claim 4 or 5, characterized in that: In addition to the at least one red pyrene dye and the 0.5-10 parts by mass of the photoinitiator, 0.001-1 parts by mass of at least one additive is used.

7. The 3D printed product according to claim 6, characterized in that: The additive is at least one leveling agent, at least one stabilizer, at least one additional dye different from the red pyrene dye, at least one filler or at least one organic pigment.

8. The 3D printed product according to one or more of claims 1 to 7, characterized in that These 3D printed products are based on photopolymerizable 3D printing using either SLA 3D printers or DLP 3D printers.

9. Use of at least one red pyrenone dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one in dissolved form for improving the light fastness and color properties determined according to DIN EN ISO 4892-2 of photopolymerizable compositions based on urethane-acrylate resins and 3D printed products produced therefrom, wherein the color distance ΔE of these compositions and 3D printed products from the L*a*b* coordinates of the color numbers starting with "3" on the RAL color chart is less than 20.

10. The use according to claim 9, characterized in that The use of at least one red pyrene ketone dye in the additive manufacturing of 3D printed products is provided in photopolymerization-based 3D printing.

11. The use according to claim 9 or 10, characterized in that These compositions based on urethane acrylate resins are based on urethane acrylates, polyurethane acrylates or polyether urethane acrylates.

12. A method for improving the light fastness and color properties of photopolymerizable urethane-acrylate resin-based compositions and 3D printed products produced therefrom, as determined in accordance with DIN EN ISO 4892-2, wherein the color distance ΔE of the L*a*b* coordinates of these compositions and 3D printed products to the color numbers starting with "3" on the RAL color chart is less than 20, characterized in that: At least one red pyrene dye selected from 8,9,10,11-tetrachloro-12H-phthalopyrin-12-one and / or 14H-benzo[4,5]isoquino[2,1-a]perylene-14-one is present in dissolved form in the urethane-acrylate resin-based composition.

13. The method according to claim 12, characterized in that At least one use of a red pyrene ketone dye in the additive manufacturing of 3D printed products occurs in photopolymerization-based 3D printing.

14. The method according to claim 12 or 13, characterized in that These compositions based on urethane acrylate resins are based on urethane acrylates, polyurethane acrylates or polyether urethane acrylates.

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