AT211533B - Process for the production of plastic light diffusion screens - Google Patents
Process for the production of plastic light diffusion screensInfo
- Publication number
- AT211533B AT211533B AT299858A AT299858A AT211533B AT 211533 B AT211533 B AT 211533B AT 299858 A AT299858 A AT 299858A AT 299858 A AT299858 A AT 299858A AT 211533 B AT211533 B AT 211533B
- Authority
- AT
- Austria
- Prior art keywords
- light diffusion
- production
- plastic
- rollers
- diffusion screens
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
- B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
- B29C59/04—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/001—Combinations of extrusion moulding with other shaping operations
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C53/00—Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
- B29C53/02—Bending or folding
- B29C53/04—Bending or folding of plates or sheets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D11/00—Producing optical elements, e.g. lenses or prisms
- B29D11/00605—Production of reflex reflectors
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/001—Combinations of extrusion moulding with other shaping operations
- B29C48/0011—Combinations of extrusion moulding with other shaping operations combined with compression moulding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/001—Combinations of extrusion moulding with other shaping operations
- B29C48/0019—Combinations of extrusion moulding with other shaping operations combined with shaping by flattening, folding or bending
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/07—Flat, e.g. panels
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/07—Flat, e.g. panels
- B29C48/08—Flat, e.g. panels flexible, e.g. films
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/13—Articles with a cross-section varying in the longitudinal direction, e.g. corrugated pipes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2001/00—Use of cellulose, modified cellulose or cellulose derivatives, e.g. viscose, as moulding material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2025/00—Use of polymers of vinyl-aromatic compounds or derivatives thereof as moulding material
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Health & Medical Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Ophthalmology & Optometry (AREA)
- Shaping Of Tube Ends By Bending Or Straightening (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
Description
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Verfahren zur Herstellung von Lichtstreuschirmen aus Kunststoff
Die Erfindung betrifft ein Verfahren zur Herstellung von Lichtstreuschirmen aus Kunststoff, insbeson- dere von Schirmen, die zum Streuen des durch Leuchtröhren ausgestrahlten Lichtes verwendet werden.
Bekanntlich werden Lichtstreuschirme zwecks Erzielung einwandfreier Lichtstreueigenschaften auf der einen bzw. beiden Seiten mit Prismen versehen. Für diesen Zweck nach dem Strangpressverfahren hergestellte prismatische Gebilde weisen gewöhnlich lediglich eine in Längsrichtung des ausgepressten Er- zeugnisses verlaufende Rillenanordnung auf. Die Wirksamkeit solcher Schirme ist unbefriedigend.
Anderseits sind auch dem Spritzverfahren Grenzen gesetzt, weil die Formen keine beliebig langen
Erzeugnisse zu erhalten gestatten, die bei verschiedenen Verwendungsarten solcher Schirme erwünscht sind.
Erfindungsgemäss wird von dem bekannten Verfahren ausgegangen, nach welchem ein endloses Kunst- stoffband mit glatter Oberfläche im Strang gepresst und anschliessend zwischen Walzen dessiniert wird.
Das Verfahren gemäss vorliegender Erfindung ist dadurch gekennzeichnet, dass das dessinierte Band in noch bildsamem Zustand zwecks Erzielung einer Querschnittskrümmung während des Abziehens kontinuierlich über eine im Querschnitt gekrümmte Fläche geführt und mittels Unterdruck an die Fläche angesaugt wird.
Es konnte auf Grund zahlreicher Versuche überraschenderweise festgestellt werden, dass das durch das
Verfahren erhaltene Profil gegenüber Erzeugnissen, die mittels Spritzverfahren oder Strangpressverfahren ohne nachfolgender Querschnittskrümmungerhalten worden waren, erhöhte Durchsichtigkeit, also gerin- gere Lichtaufnahme bzw. bessere Lichtstreueffekte aufweist. Dies wird auf die erfindungsgemässe Quer- schnittskrümmung des Profils zurückgeführt, die unter Schonung des zwischen den Walzen dessinierten
Kunststoffbandes vorgenommen wird.
An Hand einer Zeichnung soll die Erfindung, ohne Einschränkung auf das gezeigte Ausführungsbei- spiel, erläutert werden.
In dieser Zeichnung ist mit 1 der Kopf einer Strangpresse A bezeichnet, aus welcher eine Bahn 2 aus durchsichtigem Kunststoff, z. B. Polystyrol oder Celluloseacetat, mit glatter Oberfläche ausgepresst wird.
Die Bahn 2 wird durch ein Walzenpaar 3,4 geführt, wobei die mit 3 bezeichnete obere Walze mit
Erhebungen versehen ist, welche in die entsprechende Strangoberfläche prismatische Gebilde einpressen.
Die untere Walze 4 ist glatt und besteht aus einem nachgiebigen Werkstoff, z. B. Hartgummi. Falls jedoch prismatische Gebilde auch an der Unterseite der Bahn erwünscht erscheinen, kann auch die untere
Walze mit Erhebungen versehen sein.
Das aus dem Walzenpaar 3, 4 austretende gemusterte Profil wird zum Unterdruck-Formen über eine
Form 5 geführt, um ein gekrümmtes Querschnittsprofil zu erhalten. Zwei diesem Profil angepasste End- walzen 6, 7 dienen zur Mitnahme des Profils.
Die beiden Walzen 6,'7 weisen, wie dargestellt. eine glatte Oberfläche auf ; das Profil ist an der Stel- le, an welcher diese Walzen eingesetzt sind, genügend abgekühlt, d. h. ausreichend starr.
An Stelle der Form 5 können auch Formzylinder verwendet werden, die entsprechend den Walzen 6 und 7 ausgebildet sind.
Die erhaltene Bahn wird schliesslich auf die dem jeweiligen Anwendungszweck entsprechende Länge geschnitten.
Es ist, wie festgestellt werden konnte, von Vorteil, wenn der aus der Strangpresse 1 ausgepresste Kunst- stoff, wie in der Zeichnung dargestellt, eine vollkommen glatte Oberfläche aufweist.
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Process for the production of plastic light diffusion screens
The invention relates to a method for producing light diffusion screens made of plastic, in particular screens which are used to diffuse the light emitted by fluorescent tubes.
It is known that light diffusion screens are provided with prisms on one or both sides in order to achieve perfect light diffusion properties. Prismatic structures produced for this purpose by the extrusion process usually only have an arrangement of grooves running in the longitudinal direction of the extruded product. The effectiveness of such screens is unsatisfactory.
On the other hand, there are also limits to the spraying process because the shapes are not arbitrarily long
Allow products to be obtained which are desired in various types of use of such screens.
According to the invention, it is based on the known method, according to which an endless plastic strip with a smooth surface is pressed in the strand and then patterned between rollers.
The method according to the present invention is characterized in that the patterned tape, while still malleable, is continuously guided over a surface with a curved cross-section during peeling to achieve a cross-sectional curvature and is sucked onto the surface by means of negative pressure.
On the basis of numerous experiments, it was surprisingly found that the
Process obtained profile compared to products that were obtained by means of injection molding or extrusion molding without subsequent cross-sectional curvature, increased transparency, that is, less light absorption or better light scattering effects. This is attributed to the cross-sectional curvature of the profile according to the invention, which is patterned between the rollers while protecting the
Plastic tape is made.
The invention is to be explained using a drawing, without being restricted to the exemplary embodiment shown.
In this drawing, the head of an extruder A is designated by 1, from which a web 2 of transparent plastic, for. B. polystyrene or cellulose acetate, is pressed with a smooth surface.
The web 2 is passed through a pair of rollers 3, 4, with the upper roller labeled 3 with
Elevations are provided which press prismatic structures into the corresponding strand surface.
The lower roller 4 is smooth and consists of a flexible material, e.g. B. hard rubber. However, if prismatic structures also appear desired on the underside of the web, the lower one can also be used
Roll be provided with elevations.
The patterned profile emerging from the pair of rollers 3, 4 is used for vacuum forming via a
Form 5 guided in order to obtain a curved cross-sectional profile. Two end rollers 6, 7 adapted to this profile are used to carry the profile.
The two rollers 6, '7 have, as shown. a smooth surface; the profile has cooled down sufficiently at the point where these rollers are inserted, ie. H. sufficiently rigid.
Instead of the form 5, form cylinders can also be used which are designed in accordance with the rollers 6 and 7.
The web obtained is finally cut to the length corresponding to the particular application.
As has been found, it is advantageous if the plastic pressed out of the extruder 1, as shown in the drawing, has a completely smooth surface.
Claims (1)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT299858A AT211533B (en) | 1958-04-25 | 1958-04-25 | Process for the production of plastic light diffusion screens |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT299858A AT211533B (en) | 1958-04-25 | 1958-04-25 | Process for the production of plastic light diffusion screens |
Publications (1)
Publication Number | Publication Date |
---|---|
AT211533B true AT211533B (en) | 1960-10-25 |
Family
ID=3543715
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AT299858A AT211533B (en) | 1958-04-25 | 1958-04-25 | Process for the production of plastic light diffusion screens |
Country Status (1)
Country | Link |
---|---|
AT (1) | AT211533B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0050237A1 (en) * | 1980-09-30 | 1982-04-28 | SOCIETA ITALIANA VETRO - SIV SpA | Plate for covering a concentrating solar collector |
FR2504055A1 (en) * | 1981-04-20 | 1982-10-22 | Nissen Kagaku Kogyo Kk | EMBOSSED MATERIAL SHEET AND MANUFACTURING METHOD THEREOF |
-
1958
- 1958-04-25 AT AT299858A patent/AT211533B/en active
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0050237A1 (en) * | 1980-09-30 | 1982-04-28 | SOCIETA ITALIANA VETRO - SIV SpA | Plate for covering a concentrating solar collector |
FR2504055A1 (en) * | 1981-04-20 | 1982-10-22 | Nissen Kagaku Kogyo Kk | EMBOSSED MATERIAL SHEET AND MANUFACTURING METHOD THEREOF |
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