HK1080881B - Plastic molded body containing a fluorescent dye - Google Patents

Description

Plastic moulded part containing fluorescent dye

Technical Field

The invention relates to a plastic moulded part containing a fluorescent dye.

Prior Art

EP-A0553083 describes plastic luminophores containing fluorescent dyes in a concentration of 0.1 to 5% by weight and white pigments, for example TiO₂Or BaSO₄. In addition, other pigments may be contained.

Objects and solutions

Molded parts, in particular plastic plates made of cast polymethyl methacrylate, which contain fluorescent dyes and BaSO according to EP-A0553083, are known₄As a scattering agent. Starting from this prior art, the color definition of the moldings should be improved in particular.

This object is achieved by the following mouldings:

the molded article is composed of a plastic matrix composed of a transparent plastic, which contains a soluble fluorescent dye and a scattering agent having a refractive index difference of + - (+ -.) (0.003 to 0.2) from the plastic matrix, characterized in that a white pigment having a refractive index difference of +0.4 to 1.5 from the plastic matrix is additionally contained in a concentration of 0.001 to 0.1% by weight.

Surprisingly, the addition of white pigments in unusually low concentrations leads to a significantly improved color definition. The mouldings according to the invention in particular have a reflectance in% in accordance with DIN5036 which is at least 10% higher than in the case of corresponding mouldings without white pigment. The increase in the color brightness is already clearly observable with the naked eye.

Detailed Description

The invention relates to a moulded part consisting of a plastic matrix consisting of a transparent plastic, containing a soluble fluorescent dye, optionally in combination with other colorants (pigments, dyes), and a scattering agent having a difference in refractive index from the plastic matrix of + - + (0.003 to 0.2), characterized in that a white pigment having a difference in refractive index from the plastic matrix of +0.4 to 1.5 is additionally contained in a concentration of 0.001 to 0.1% by weight.

Fluorescent dyes

The mouldings according to the invention contain soluble fluorescent dyes known per se, for example those based on perylene compounds.

WO99/16847 describes fluorescent dyes which are soluble in plastics, for example polycarbonate, polymethyl methacrylate, polyvinylidene fluoride or mixtures of polymethyl methacrylate and polyvinylidene fluoride, and are suitable for use in yellow-fluorescing articles or mouldings. The fluorescent dye refers to a compound having a defined color coordinate range according to the CIE1931 standard colorimetric system and a fluorescence/brightness factor of greater than 5, which is substituted by an N, N' -disubstituted 3, 4: a mixture of 9, 10-perylene bis (dicarboximide) and a yellow fluorescent dye.

Suitable for the purposes of the present invention are in particular the commercially available fluorescent dyes Lumogen ® F orange 240, Lumogen ® F yellow 083, Lumogen ® F Red 240(Lumogen ®: trade mark of BASF AG (Ludwigshafen, Germany)) and Hostasol ® yellow 3G.

Other colorants

The fluorescent dyes of the present invention may be present in combination with other colorants. Such as pigments and dyes, especially non-fluorescent dyes. Such other colorants are, for example, copper phthalocyanine green, copper phthalocyanine blue, red iron oxide, ultramarine blue, chromium titanium yellow, anthraquinone series dyes. The combination of the fluorescent dyes of the present invention with other colorants allows a larger color spectrum to be covered. For example, a combination of a yellow-fluorescing fluorescent dye and a green pigment, such as copper phthalocyanine green, may be suitably used to produce the brightly fluorescent green of the invention. The content of the further colorants can be, for example, from 0.00 to 1% by weight, preferably from 0.01 to 0.5% by weight.

Scattering agent

By scattering agent is meant an insoluble additive of a smaller size, for example 1 μm to 1mm, which can be incorporated into the matrix plastic. The scattering agent has a refractive index difference of ± (0.003 to 0.2).

Suitable scattering agents are, for example, aluminum hydroxide, potassium aluminum silicate (mica), aluminum silicate (kaolin), barium sulfate, calcium carbonate, magnesium silicate (talc), polystyrene and/or light-scattering beads made of crosslinked plastic. Light-scattering beads composed of copolymers of methyl methacrylate and styrene or benzyl methacrylate, which may be additionally crosslinked, are known, for example, from DE3528165C2, EP570782B1 or EP656548a 2.

White pigment

The white pigment has a refractive index difference of +0.4 to 1.5, preferably +0.5 to 1.4, particularly preferably 1.0 to 1.3, from the plastic matrix and is contained in the plastic matrix in a concentration of 0.001 to 0.1 wt.%, preferably 0.005 to 0.01 wt.%.

Preferred white pigments are, for example, titanium dioxide (TiO)₂) Zinc oxide (ZnO) or zinc sulfide (ZnS).

Molded part

The mouldings according to the invention have a reflectance in% according to DIN5036 which is at least 10%, preferably at least 15%, in particular at least 20%, higher than in the case of corresponding mouldings without white pigment.

The mouldings according to the invention can be obtained after incorporation of the fluorescent dyes and optionally further colorants into the corresponding plastics or into the plastic matrix before or after polymerization of the corresponding plastics or plastic matrix. The incorporation can be carried out technically, for example, by stirred addition to a polymerizable plastic slurry or to a plastic melt of the thermoplastic polymer, by means of a kneader, application in a mixing drum (Auftrommeln), direct metering or addition of highly concentrated master batches. The plastic material thus dyed can be further processed in a manner known per se, for example by extrusion, injection molding, thermoforming, machining, etc.

It can be an almost arbitrary molding. Preferably in the form of a plate, tube or rod.

Plastic material

The transparent plastic of the plastic substrate has a light transmission in the visible range of at least 40%, preferably at least 50%, particularly preferably at least 70%, in particular at least 80% (light transmission coefficient τ for daylight (standard illuminant D65))_D65See, e.g., DIN 67507). Thermoelastic or thermoplastic plastics are preferred.

The transparent plastic of the plastic matrix can be extruded polymethyl methacrylate plastic, cast polymethyl methacrylate plastic, impact-modified polymethyl methacrylate plastic, polycarbonate plastic, polystyrene plastic, styrene-acrylonitrile (Acryl-nitrile) plastic, polyethylene terephthalate plastic, glycol-modified polyethylene terephthalate plastic, polyvinyl chloride plastic, transparent polyolefin plastic, acrylonitrile-butadiene-styrene (ABS) plastic and/or mixtures (blends) of the aforementioned plastics.

Applications of

The moldings of the invention can be used, for example, for automobile bodies, high-quality furniture, signboards or parts thereof, or for lighting technology, for example for illuminated advertising systems. For fluorescence excitation, normal daylight is generally sufficient. Active illumination can likewise be carried out, for example, by means of light tubes or, optionally, by means of LEDs.

Examples

The scheme is as follows:

in 1000 parts of prepolymerized methyl methacrylate (viscosity about 1000cP) were dissolved 1 part of 2, 2' -azobis (2, 4-dimethylvaleronitrile) and the colorant according to Table 1.

To this batch was added a mill base consisting of:

3 parts by weight of a soluble polymethyl methacrylate resin,

10 parts by weight of barium sulfate and the amounts (% by weight) of titanium dioxide or zinc sulfide specified in Table 1 depending on the experiment,

which is dispersed in a disperser (rotor/stator principle) operating rapidly

30 parts by weight of methyl methacrylate.

The batch was stirred vigorously, filled into silicate glass compartments separated by 3mm thick cords and polymerized in a water bath at 45 ℃. The final polymerization was carried out in a temperature controlled oven at 115 ℃.

Color location (L)^*、a^*、B^*) The measurement according to DIN5033 was carried out with a spectrophotometer.

TABLE 1

Experiment number	Titanium dioxide	Zinc sulfide	Lumogen F orange 240	Lumogen F yellow 083	Lumogen F Red 305	Hostasol yellow 3G
							113T	---	---	0.05	---	---	---
144M	0.0075	---	0.05	---	---	---
							113Q	---	---	---	0.05	---	---
144K	0.0075	---	---	0.05	---	---
							113S	---	---	---	---	0.05	---
144E		0.0125	---	---	0.05	---
							144G	0.0075	---	---	---	0.05	---
148A		---	---	---	---	0.05
							148F	0.0075	---	---	---	---	0.05

Data: in weight percent

As a result:

TABLE 2 reflection colour values L, a, b according to CIELAB at light source D65/10 °

Experiment number	Color tone	L*	a*	b*	Reflectance in%	Visual evaluation under daylight D65
							113T	Orange	56.29	23.66	94.86	24.2	Fluorescent orange yellow and somewhat dark
144M	Orange	66.10	29.80	105.55	35.5	Fluorescent orange yellow and very bright
							113Q	Yellow green	62.34	-31.70	80.00	30.8	Yellow fluorescence and a little darkness
144K	Yellow green	70.53	-31.21	90.56	41.5	It fluoresces yellow and is very bright
							113S	Red wine	34.77	60.93	59.94	8.4	Fluorescent red and somewhat dark
144E	Red wine	37.81	65.73	59.53	10.0	Fluoresce red and are very bright
							144G	Red wine	37.40	64.83	58.77	9.8	Fluoresce red and are very bright
148A	Yellow colour	64.40	-30.14	90.36	33.3	Yellow fluorescence and a little darkness
							148F	Yellow colour	72.31	-28.77	99.64	44.1	It fluoresces yellow and is very bright

As can be seen from the color values and also in the visual evaluation, the products prepared with the barium sulfate/titanium dioxide (zinc sulfide) combination are significantly brighter in hue. Red has a higher red value, yellow has a higher yellow value, etc. The improvement is also visually apparent.

Claims (9)

1. A molded article composed of a plastic matrix composed of a transparent plastic, which contains a soluble fluorescent dye and a scattering agent having a difference in refractive index of ± (0.003 to 0.2) from the plastic matrix, characterized in that a white pigment having a difference in refractive index from the plastic matrix of +0.4 to 1.5 is additionally contained in a concentration of 0.001 to 0.1% by weight.

2. The molded part according to claim 1, wherein titanium dioxide, zinc oxide or zinc sulfide is used as the white pigment.

3. A molded body as claimed in claim 1 or 2, characterized in that the scattering agent contained is aluminum hydroxide, potassium aluminum silicate, barium sulfate, calcium carbonate, magnesium silicate, polystyrene and/or light-scattering beads made of crosslinked plastic.

4. The molded part according to claim 1 or 2, characterized in that its reflectivity is at least 10% higher than in the case of a corresponding molded part without white pigment.

5. The molded part according to claim 1 or 2, wherein the transparent plastic of the plastic matrix has a light transmission in the visible range of at least 40%, which is the light transmission coefficient τ to DIN67507 for daylight generated by a standard light source D65_D65。

6. A molded body as claimed in claim 1 or 2, characterized in that the transparent plastic of the plastic matrix is an extruded polymethyl methacrylate plastic, a cast polymethyl methacrylate plastic, an impact-modified polymethyl methacrylate plastic, a polycarbonate plastic, a polystyrene plastic, a styrene-acrylonitrile plastic, a polyethylene terephthalate plastic, a glycol-modified polyethylene terephthalate plastic, a polyvinyl chloride plastic, a transparent polyolefin plastic, an acrylonitrile-butadiene-styrene plastic and/or mixtures of the aforementioned plastics.

7. The molded object as claimed in claim 1 or 2, characterized in that a fluorescent dye is present in combination with further colorants.

8. Use of the molded parts according to claim 1 to 7 for automobile bodies, famous furniture, signboards or parts thereof, or for lighting technology.

9. Use according to claim 8, characterized in that it is used in light advertising facilities.