JPH11350254A - Temperature-controlled ray-penetrating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sheath-core fiber suitable for a woven or knitted fabric as a raw material of a thermotropic shade by arranging a temperature-controlled ray penetrating material as a core and surrounding the circumference of the same with a transparent sheath layer. SOLUTION: This method for producing a temperature-controlled ray- penetrating material is provided by using a thermotropic polymer blend having a lower part critical separation temperature, e.g. a blended material of a poly(styrene-co-hydroxyethyl methacrylate) with a polypropylene oxide as a core material, and a ethylene-vinyl acetate copolymer as a sheath material, supplying a melted flow thereof to a composite die for a sheath-core fiber to obtain the temperature controlled ray-penetrating material consisting of the sheath-core type fiber obtained by surrounding the circumference of the core part comprising the above thermotropic polymer blend with a transparent sheath layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a temperature-controlled radiolucent material and to the use of said radiolucent material for the reversible temperature-dependent control of radiation transmission in buildings and industrial facilities.

[0002]

BACKGROUND OF THE INVENTION Light irradiation in enclosed spaces or industrial equipment, such as solar energy equipment, raises the temperature to a certain extent, unlike the energy content and light intensity, even harmful. For example, undesired temperature values occur in buildings, greenhouses or vehicles because the amount of solar energy varies with time of day and season.

[0003] Thus, those skilled in the art have developed materials based on polymer blends which, as a function of temperature, will reversibly separate and therefore become turbid. The basis for this mechanism of thermophilic behavior is that the polymer-based structure changes at a constant temperature so that the transmittance of radiation changes. This phenomenon usually occurs when polymer blend components having different refractive indices separate at a certain temperature.
The temperature at which this process occurs is the lower critical separation temperature (LC
ST). A basic description of the relationship between the structure of polymer blends and the occurrence of LCST behavior and the use of polymer blends in glaze systems with temperature controlled light transmission can be found in EP 0181485. Can be found.

[0004] Materials with improved reversibility of the change in radiation transmission are disclosed in EP 0 559 113 and DE-A-4 408 156.

[0005] Known polymer blends having temperature-controlled radiation transmission properties are brushed directly on the surface of the glass to be protected or first make a glaze system, in which case the polymer blend is used as a transparent topcoat. It can be used by being applied.

However, known polymer blends having temperature controlled radiation transmission properties have heretofore been
It could not be processed into fibers of sufficient mechanical strength, further fabrics and knits. All reversible structural changes, which are a prerequisite for all reversible changes in radiation transmission, can only be achieved with polymer blends consisting of mobile and transferable components. However, such blends are not shape stable.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a temperature-controlled radiation transmitting material in fiber form.

[0008]

SUMMARY OF THE INVENTION It has been found that this object is achieved by a temperature-controlled radiolucent material present as a core in a core-shell fiber surrounded by a transparent shell layer.

[0009] Temperature-controlled radiolucent polymer systems, such as those described, for example, in DE-OS 4 408 156, EP 0 181 485 or EP 0 559 113, are particularly useful. Tend to be tacky at higher application temperatures, and their mechanical strength is low. A transparent shell layer that completely surrounds at least one core composed of one of the known thermophilic polymers provides tack control and mechanical strength and allows the thermophilic polymer to be in fibrous form I confirmed that.

Furthermore, the different refractive indices of the core and the shell are:
The result is a larger core cross-section optical impression (magnifying glass effect). This core consists of an expensive special effect substance. Thus, by using the core-shell fibrous material of the present invention,
It is possible to obtain the same effect as with a larger amount of the exposed special effect material, but with a smaller amount of the expensive special effect material.

The core material used is, for example, European Patent No. 01
It can be selected from known thermophilic polymers such as those described in U.S. Pat. Nos. 81485, 0559113 or DE 4408156. Such materials are those in which the components of the polymer blend exhibit moderate magnitude interference by one of mechanisms such as salt formation, hydrogen bonding, complexation, p-electron interference or zwitterionic interference. It is important to have a lower critical separation temperature (LCST) that is known to occur at

Suitable polymers for thermotropic polymer blends can be selected from a number of known polymers, such as homopolymers and copolymers, having a cloud point in which the mutual interference is in a suitable range. Examples of suitable polymers include polystyrene, polyvinyl methyl ether, polymethyl (meth) acrylate, styrene-acrylonitrile copolymer, poly-ε-caprolactone, chloro rubber, ethylene-vinyl acetate copolymer, PVC, polycarbonate, polyvinylidene fluoride, poly Ethyl acrylate,
Poly-n-butyl acrylate, poly (ethylhexyl acrylate-co-acrylic acid), poly (tetradecyl methacrylate-co-styrene-co-3-dimethylamino-2,2-dimethylprop-1-yl methacrylate), poly ( Styrene-co-hydroxyethyl methacrylate) and poly-propylene oxide.

Changing the relative level of the individual comonomers (interference groups) in the copolymer very simply sets the critical haze temperature to the desired value.

The relative level of comonomer is not critical. Usually, in the range of 0.1 to 50 mol%, preferably 0.5 to 25.
It is in the range of mol%.

Number average molecular weight M of polymer P1 or P2
Is not important per se, but usually in the range of 500 to 1,000,000, preferably 1000 to 5
It is in the range of 00000.

The mixing ratio of the polymers P1 and P2 depends on the desired haze temperature, but in this regard is freely selectable. The mixing ratio P1: P2 is usually from 5:95 to 95: 5.
% By weight, preferably from 20:80 to 80: 20% by weight
Is within the range.

In addition, suitable polymer systems may contain known photoinitiators, which may be copolymer forming moieties of the polymer chain.

[0018] The thermophilic polymer blend is a conventional material,
For example, lubricants, additives, UV stabilizers, processing stabilizers (eg, antioxidants), anticorrosives, plasticizers, dyes or pigments may be added.

The thermophilic polymer blend is melted in a suitable device that is automatically emptied in the downstream direction, for example in a heated vessel. Drum type melting chambers, in which the lid is heated and the polymer material to be melted passes directly through the heated hose and directly into the die, as used in thermoplastic adhesive metering, are particularly suitable. . This form of melting has the advantage of a short melting time in which the thermophilic polymer blend cannot be separated. It is also possible to melt the thermophilic polymer blend in an extruder.

The molten polymer blend is fed via a pump, for example a gear pump or a piston pump or an extruder, to a spinning die suitable for producing core shell fibers.

The processing temperature of the thermophilic polymer is from 40 ° C. to 2
It is in the range of 50 ° C.

Useful shell materials are, due to their material properties,
A polymer that can be processed into fibers and that must not be miscible with the thermophilic polymer blend used as the core material. Examples of suitable shell materials include polyacrylonitrile, modacrylic, polyester, polyolefin, such as polyethylene, polypropylene, ethylene vinyl acetate, polyamide, aramid, polyurethane, high temperature polymers, such as polyphenylene sulfide, polyether ketone, polyvinyl chloride polyvinylidene chloride, polyfluoroethylene. Vinylidene fluoride, polytetrafluoroethylene, and polyethylenetetrafluoroethylene. The shell material is melted in a suitable manner, for example in a single or twin screw extruder. The processing temperature of the shell material in the extruder is 80 ° C., depending on the softening point of the shell material.
In the range of ２５０250 ° C. The temperature may also be higher for special high melting point shell polymers, up to 400 ° C. This is especially the case when using high heat-resistant polymers and fluorine-containing polymers such as polytetrafluoroethylene and its derivatives. The shell material may advantageously contain auxiliaries such as lubricants, additives, UV screens, hindered amine light stabilizers (HALS), processing stabilizers such as antioxidants, dyes and pigments.

One particular advantage of the core-shell structure of the material according to the invention is that auxiliaries whose compatibility with the thermophilic core material is not guaranteed can be used. For such auxiliaries, especially dyes and pigments, there is the option of incorporation into the shell polymer.

Similarly, UV screens provide better protection of the thermophilic polymer blend from UV light than the formulation in the thermophilic polymer blend itself, because the same level of use in the shell polymer provides: Advantageously, it is incorporated into the shell polymer.

The thermophilic polymer blend and the shell polymer are fed in the molten state via an extruder to a die suitable for producing bicomponent fibers. Such dies are described, for example, in U.S. Pat. Nos. 5,234,650 and 5,216,207.
No. 4 is described in the specification. The resulting core-shell fibers consisting of a thermophilic core and a transparent shell material are not limited with respect to the number and cross-section of the cores. In the simplest case, the core may have a circular cross-section and may be concentrically surrounded by a shell material. However,
The special type of spinning die makes it possible to produce cores with a wide range of core cross-sections and variables.

Advantageously, the additional polymer core may be provided with a non-thermal, but mechanically high-strength material.

The fiber-forming material of the present invention can be prepared by a known textile processing technique such as spinning, as in the case of conventional monocomponent fibers.
The fabric can be further processed into a woven or knitted fabric by weaving, knitting, or the like. Possible fiber diameter is 0.00
It is in the range of 1 mm to 10 mm. The woven fabric has a diameter of 0.1
It is particularly suitably produced from monofil core fibers of from 2 mm to 2 mm.

The woven or knitted fabric need not consist solely of the fiber-forming material of the present invention. Sheeting the thermophilic fibers in a horizontal and / or vertical orientation of the fibers or fabric;
It is also possible to work with regular monocomponent fibers in the form of geometric patterns or thermophilic monofilaments. If the thermophilic fiber is used on the entire surface, the achievable protection from the sun is maximum, but in this case only a partial use of the thermophilic fiber is due to heat and / or exposure to the sun. The decoration effect to the change at the time of can be emphasized.

The woven or woven fabric produced from the fibrous material according to the invention can be used as a heat-shielding screen in front of or behind a window, for example, as a awning, roll-up blind or venetian blind, for apparel purposes and. And / or can be used for decorative purposes.

One embodiment of the present invention is described in further detail with reference to the drawings.

[0031]

[Example] Werner & Pfe having a screw diameter of 25 mm
In an iderer ZSK25 twin screw extruder, an ethylene vinyl acetate copolymer (Escornene® Ult)
raUL 00018, 17.5% by weight of vinyl acetate, average molecular weight 3000-50,000 and a melt index according to ASTM D 1238 of 1 kg / h) of 1 kg / h, for example as shell polymer at 150 ° C. and 50 ° C. It was introduced into the melting zone at revolutions / minute. Then, set the temperature to 1
The temperature was raised to 80 ° C. The die used at the end of the extruder was a composite fiber die as described in the exploded view of FIG.

The composite fiber die is composed of four die plates 1-4.
Consisting of individual packs, which are fixed together by bolts 5. Since the four die plates are tightly bolted together, the product stream can only flow into distribution holes or depressions in the plates. The die plate 1 is oriented towards the extruder and is sealingly connected to its outlet by a threaded union. The plate 4 is integrated at the end of the die pack and has three outlets 6 for core shell fibers. The two product streams, the core polymer and the shell polymer, reach the composite fiber die via a separation port.

The shell polymer, ethylene vinyl acetate copolymer, flows into the rectangular recess of the die plate 1 from the outlet of the extruder. From here, the shell polymer flows into the die plate 2 through the twelve holes 9 under the feed pressure of the extruder which further supplies the shell polymer. In the die plate 2, the shell polymer positioned at the same position as the die plate 1 flows through the twelve holes 10 as well.

The core polymer used as an example comprises 94 mol% of styrene and 4 mol% of hydroxyethyl methacrylate, 53.5 parts by weight of a homogeneous styrene copolymer having a mean molecular weight of 50,000 and a mean molecular weight of 40,000.
A mixture of 43.2 parts by weight of propylene oxide having a molecular weight of 00, 2.5 parts by weight of trimethylolpropane triacrylate, and 0.75 parts by weight of 2,4,6-trimethylbenzoylphenylphosphine oxide. About 1 mixture
It was heated to 30 ° C. and metered as a liquid melt into the mouth of the die plate 4 via a screw-in union 7 by means of a gear pump. The core polymer flows through the channels 16 in the die plate 4 through the holes 12 into the holes 13 in the die plate 3, followed by the central polymer between each of the four holes 10 for the shell polymer. It flows into the three grooves 14 of the die plate 2.

From the die plate 2, the shell polymer and the core polymer flow into the plate 3 and converge therefrom into the x-shaped grooves 15. In the x-shaped groove 15, the core-shell structure is formed from two polymer streams. The shell polymer and the core polymer are used as core shell fibers in the holes 6 in the die plate 4.
Pass together to leave the composite fiber die.

The die plate described in FIG.
This results in three core-shell fibers having a profile of m. Upon heating, the fibers exhibit significant haze due to increased light scattering by the thermophilic core. The cloud point is about 50 ° C.

It is also possible to produce thinner fibers by changing the speed at which the formed fibers leave the die or changing the geometry.

[Brief description of the drawings]

FIG. 1 is a development view showing a composite fiber die for producing core shell fibers from a radiation transmitting material according to the present invention.

[Explanation of symbols]

1, 2, 3, 4 die plate, 5 bolts, 6
Outlet, 7 threaded union, 8 groove, 9, 1
0, 12, 13 holes, 14, 15 grooves, 16 channels

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI // G05D 23/00 G05D 23/00 D (72) Inventor Eckehard Jans Weinheim Wintergasse 19/2 Germany

Claims (7)

[Claims] 1. A temperature-controlled radiolucent material present as a core in a core-shell fiber surrounded by a transparent shell layer. 2. The core shell fiber according to claim 1, wherein the shell layer comprises a screen. 3. The method according to claim 1, wherein the shell layer comprises a transparent coloring material.
Or the core-shell fiber according to 2. 4. The core-shell fiber according to claim 1, wherein the two or more core materials are mainly composed of a temperature-controlled radiation transmitting material. 5. The core fiber according to claim 1, comprising an additional polymer of a high tensile strength material. 6. A woven or knitted fabric comprising the core-shell fiber according to any one of claims 1 to 5. 7. The woven or knitted fabric according to claim 6, for the reversible temperature-dependent control of the radiation transmission of solar energy devices, especially for buildings and industrial facilities for the apparel industry and / or for decorative purposes. Usage of cloth.