eTPE Laser Marking

Abstract

Laser-markable foamed pellets contain a composition (MI), containing a thermoplastic elastomer (TPE-1) and a color component as component (c1) selected from laser marking additives. A process can be used for producing said laser-markable foamed pellets. The laser-markable foamed pellets according to the present invention can be used for preparing a laser-markable molded body. A process for preparing a laser-markable molded body involves providing and fusing the laser-markable foal led pellets.

Claims

1. Laser-markable foamed pellets, comprising: a composition (M1) comprising a thermoplastic elastomer (TPE-1), and a color component (c1) selected from laser marking additives, wherein the composition (M1) comprises the color component (c1) in an amount in a range of from 0.1 to 10% by weight, based on a weight of the composition (M1).

2. The laser-markable foamed pellets according to claim 1, wherein the composition (M1) comprises at least one component (c2) selected from the group consisting of a color-change compound, a background colorant, a colored pigment, and a dye.

3. The laser-markable foamed pellets according to claim 2, wherein the composition (M1) comprises the at least one component (c2) in an amount in a range of from 0.1 to 15% by weight, based on the weight of the composition (M1).

4. The laser-markable foamed pellets according to claim 1, wherein the thermoplastic elastomer (TPE-1) is selected from the group consisting of thermoplastic polyurethane, a thermoplastic polyether amide, a polyether ester, a polyester ester, a thermoplastic elastomer based on polyolefin, a crosslinked thermoplastic elastomer based on polyolefin, a thermoplastic vulcanizate, a thermoplastic styrene butadiene block copolymer, and a mixture thereof.

5. The laser-markable foamed pellets according to claim 1, wherein the thermoplastic elastomer (TPE-1) is a thermoplastic polyurethane, a thermoplastic polyether amide, a polyester ester, or a polyether ester.

6. A process for producing the laser-markable foamed pellets of claim 1, the process comprising: (i) mixing the thermoplastic elastomer (TPE-1) and the color component (c1), to obtain the composition (M1), and (ii) preparing the laser-markable foamed pellets comprising the composition (M1), wherein the composition (M1) comprises the color component (c1) in an amount in the range of from 0.1 to 10% by weight, based on the weight of the composition (M1).

7. A laser-markable molded body, comprising the laser-markable foamed pellets according to claim 1.

8. The laser-markable molded body according to claim 7, wherein the laser-markable molded body is selected from the group consisting of a consumer good, a security tag, sports equipment, a shoe, a saddle, a toy, a pet toy, a cushion, and furniture.

9. (canceled)

10. A process for preparing a laser-markable molded body, the process comprising: (I) providing laser-markable foamed pellets comprising a composition (M1) comprising a thermoplastic elastomer (TPF-1), and a color component (c1) selected from laser marking additives, wherein the composition (M1) comprises the color component (c1) in an amount in a range of from 0.1 to 10% by weight, based on a weight of the composition (M1), and (II) fusing the laser-markable foamed pellets to obtain the molded body.

11. The process according to claim 10, wherein (II) is carried out by thermal fusing or gluing.

Description

EXAMPLES

[0157] 1. Extrusion Process

[0158] For TPU 1, the expanding process was conducted in a twin-screw extruder of company Krauss Maffai (ZE 40). Table 1 show the composition of the used TPU and additives.

TABLE-US-00001 TABLE 1 Composition of the thermoplastic polyurethanes used for examples Additive Additive Additive compounds used TPU 1 2 3 4 polyether polyol with an OH-number of 112 and only 1000 primary OH groups (based on tetramethylene oxid, functionality: 2) (parts per weight) aromatic isocyanate (4,4 methylendiphenyldiisocyanate) 520 (parts per weight) 1,4-butane diol [parts per weight] 97 Stabilizer Package 25 tin-II-isooctoate (50% in dioktyladipate) (parts per 50 weight) Mica coated with antimon-doped tin oxide (%) 4.5 Copper Hydroxide Phosphate (%) 24.5 Ester of mixed montanic acids (%) 1 E 1185 A 10 000 (%) 70 Color masterbatches by company Grafe (visible TPU TPU- colorants) Tekolen Tekolen Grn Leucht Gold orange (color: RAL green- 2005 gold) (color: lightning orange)

[0159] The material was dried for minimum 5 h at 70 C. directly before extrusion. If necessary different amounts of a TPU which was compounded in a separate extrusion process with 4,4-Diphenylmethandiisocyanat with a functionality of 2.05 (additive 1) was added during processing. The temperature range of the extruder was 200 C. Laser suitable pigments (additive 2 (corresponding to component c1)) have been added in various amounts as masterbatch with a pigment content of 30% (Examples 1 to 3). As blowing agent CO.sub.2 and N.sub.2 was injected into the melt and all added materials were mixed homogeneously with the thermoplastic polyurethane. Table 2 shows the different compositions of example 1-3 and the reference example 1.

TABLE-US-00002 TABLE 2 Process details of eTPU extrusion processing step Example Reference eTPU Example 1 2 Example 3 example 1 TPU TPU 1 TPU 1 TPU 1 TPU 1 Content of TPU (% b.w.) 96.4 93.4 89.4 99.4 Content of additive 1 (% b.w.) 0.6 0.6 0.6 0.6 Content of additive 2 (% b.w.)/Laser 3 (~1.0% 6 (~2.0% 9 (~3.0% suitable pigment concentration in % laser pig- laser laser pig- b.w.) ment) pigment) ment) Particle mass (mg) 5 5 5 5 Bulk density (g/L) 171 175 179 165 CO.sub.2 (Gew. %) 2.6 2.6 2.6 2.6 N.sub.2 (Gew. %) 0.1 0.1 0.1 0.1 Pressure in UWP (bar) 15 15 15 15 Temperature in UWP( C.) 40 40 40 40

[0160] After mixing of all components in the extruder the material was first pressed through a gear pump with a temperature of 190 C. and then through a die plate heated up to 190 C. The granulate was cut and formed in the underwater pelletizing system (UWP). During the transport out of the UWP the particles expands under defined conditions of temperature and pressure of the water. Before drying the material for 5 h at 50 C. a centrifugal drier was used for separating the granulate and the water.

[0161] After drying, the bulk density of the resulting foamed beads is measured (according to DIN ISO 697:1984-01).

[0162] Process details of all different examples and reference examples like the used water temperatures and -pressure, the amount of blowing agents CO.sub.2 and N.sub.2 as well as the particle mass and resulting bulk density are listed in table 2.

[0163] 2. Autoclave Process & Colored Particle Foam

[0164] To further illustrate the invention, colored particle foams were produced (see Example 4, Example 5 and reference example 2). Also dyed particle foams were laser-marked if standard laser energy was used (Example 4, Example 5). The use of higher laser energy resulted in poor intensity and destruction of the 3D structure of the foam surface (reference example 2).

[0165] For the examples, the inventive TPU 1 was mixed in a pre-process step, in a twin-screw extruder of company Krauss Maffai (ZE 40) with laser suitable pigments (additive 2) and different color masterbatches provided of company Grafe (additive 3 and 4) (Example 4 and 5) (table 3). The particle mass is 25 mg.

TABLE-US-00003 TABLE 3 Composition and properties of TPU compounds TPU TPU 2 TPU 3 Content of TPU 1 (% b.w.) 93 90 Content of additive 2 (% b.w.)/ 4 (1.3% 4 (1.3% laser Laser suitable pigment concentra- laser pig- pigment) tion in & % b.w. ment) Content of additive 3 (% b.w.) 3 Content of additive 4 (% b.w.) 6 Particle mass (mg) 25 25 Density (kg/m.sup.3) 1100 1100

[0166] Experiments were conducted in a closed pressure vessel (Impregnation vessel) at a filling level of 80% by volume.

[0167] 100 parts by weight of particles from TPU 2 or 3 of table 3 and certain amounts (parts by weight) of water (333 parts by weight) as suspension medium which results in a phase re lationship P1 are mixed by stirring to get a homogenous suspension. Phase relationship P1 is defined as weight of solid particles divided by weight of water, 6.7% by weight, based on the solid particles, of a dispersing agent (surfactant 1), together with 0.13% by weight of an assistant system (surfactant 2) based on the solid particles and a certain amount of butane as blowing agent, based on the solid particles, are added to the suspension and heated up during further stirring.

[0168] At 50 C., nitrogen as co-blowing agent was added by pressure increase, to a predetermined pressure within the vessel. The liquid phase of the suspension was heated to the predetermined impregnation temperature (IMT). The time (soaking time) between 5 C. below IMT until IMT is controlled to be within 3 min and 60 min. This correlates with a heating rate of 1.67 C./min until 0.083 C./min.

[0169] In this procedure, at IMT a defined pressure in gaseous phase (IMP) is formed.

[0170] After soaking time and at the reached IMT, the pressure was released and the whole content of the vessel (suspension) was poured through a relaxation device into a vessel under atmospheric pressure (expansion vessel). Expanded beads are formed.

[0171] During the relaxation step, the pressure within the impregnation vessel was fixed with nitrogen to a certain level (squeezing pressure SP).

[0172] Additionally, directly after the relaxation device, the expanding particles can by cooled by a certain flow of water with a certain temperature (water quench).

[0173] After removal of the dispersing agent and/or the assistant system (surfactant) and subsequent drying, the bulk density of the resulting foamed beads is measured (according to DIN ISO 697:1984-01).

[0174] Details concerning manufacturing parameters of individual example and reference example are listed in table 5.

TABLE-US-00004 TABLE 5 Data for the manufacturing expanded beads Reference eTPU Example 4 Example 5 example 2 TPU TPU 2 TPU 3 TPU 3 Dispersing agent (surfactant 1) CaCO.sub.3 CaCO.sub.3 CaCO.sub.3 Assistant system (surfactant 2) L L L Phase relationship P1 0.3 0.3 0.3 Butane (% b.w.) 24 24 24 p after adding N.sub.2 at 50 C. (bar) 8 8 8 Soaking time (min) 4 4 4 IMT ( C.) 117 117 117 SP (MPa) 4.0 4.0 4.0 Water quench No No No Bulk density (kg/m.sup.3) 115 120 120

[0175] 3. Steam Chest Molding & Mechanics

[0176] In a next step the expanded material was molded to quadratic test plates with a length of 200 mm200 mm and thickness of 10 mm using steam chest molding machine of company Kurtz ersa GmbH (Boost Foamer K68). The molding parameter were adjusted for smaller (example 1-3, reference example 1) and bigger beads (example 4-5, reference example 2). Additionally, the crack steam was carried out by the movable side of the tool. The molding parameters are listed in table 6.

TABLE-US-00005 TABLE 6 Processing conditions for steam chest molding of examples Ex. 4-5 Ex. 1-3 and and refer- reference ence ex- Example Unit example 1 ample 2 Crack size mm 14 14 Crack steam fixed side bar Crack steam fixed side s Crack steam movable side bar 0.3 0.6 Crack steam movable side s 10 16 Cross steam fixed side/counter pressure bar 1.3/0 1.3/0 Cross steam fixed side/counter pressure s 10/0 30/0 Cross steam movable side/counter pressure bar Cross steam movable side/counter pressure s Autoclave steam fixed/movable side bar 1.3/0.8 1.3/0.8 Autoclave steam s 10 10

[0177] Lasering of the material was done with a TruMark 6030 (TTM2) at a wavelength of 1064 nm. The evaluation of the lasering results are shown in table 7. The rating differentiates between the color intensity as well as the effect on the 3D surface. Additionally, the pigment content and laser energy which was used for printing on the surface is written down in the table.

TABLE-US-00006 TABLE 7 Evaluation of laser test results; +good, ++better, bad, worse Laser Intensity 3D Additive 2 Energy of marking Surface Example 1 3% Standard + ++ Example 2 6% Standard ++ ++ Example 3 9% Standard ++ ++ Reference example 1 0% Standard ++ Example 4 4% Standard + ++ Example 5 4% Standard + ++ Reference example 2 4% Higher

[0178] Literature Cited: [0179] WO 94/20568 A1 [0180] WO 2007/082838 A1 [0181] WO 2017/030835 A1 [0182] WO 201 3/1 531 90 A1, [0183] WO 201 0/01 001 0 A1 [0184] WO 01/00719 A1 [0185] EP 1 190 988 A1 [0186] DE 38 42 330 A1 [0187] F. Buchholtz et al., Macromolecules, vol. 26, p. 906 (1993) [0188] U.S. Pat. No. 5,989,573 [0189] EP 0 359 909 B1 [0190] Handbook of Thermoplastic Elastomers, 2nd edition June 2014 [0191] WO2018087362A1 [0192] Plastics Additives Handbook, 5th edn., H. Zweifel, ed., Hanser Publishers, Munich, 2001 ([1]), pp. 98-136