NL8004392A - EXTRUDED, FILLED, SUITABLE FOR ELECTRICAL APPLICATION, THERMOPLASTIC SHEET MATERIAL AND METHOD FOR MANUFACTURING THAT. - Google Patents

Description

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Extruded, filled, electrically suitable, thermoplastic sheet material and method of manufacturing it.

The invention relates to a newly extruded, continuous, thermoplastic sheet material with a unique combination of physical properties and surface appearance, which is very suitable for electrical applications, for example for the manufacture of printed wiring panels. More particularly, the invention relates to an extruded, polyalkylene terephthalate sheet material having a combination of physical properties and surface appearance, suitable for use in the manufacture of printed circuit boards and other electrical applications. The invention also relates to a method and an apparatus for use in the manufacture of the above-mentioned extruded sheet material.

The term "sheet material" is used in a general sense here and refers to both sheet and foil.

Typically, printed circuit boards are made from laminated plates of thermosetting phenolic polymers and epoxy glass systems. The laminated phenolic plates are die-cut into an electrical part of the desired size and shape, called substrate, Then electrical wiring is applied to the substrate. Due to the very complicated shapes that these substrates must have, a large amount of waste is produced. Although phenolic laminates and epoxy glass systems have the necessary combination of physical properties and surface appearance essential for use in electrical components such as printed circuit boards, phenol laminates and epoxy glass systems cannot be reprocessed due to their thermosetting nature. The use of such material in the manufacture of printed wiring panels in son 4 3 Q9 2 therefore involves an undesirably large volume of expensive, unusable waste.

Attempts have been made to address this problem by injection molding printed circuit board substrates from filled thermoplastic polymers. As is known, a large number of filled thermoplastic polymers and, in addition to glass filled polyesters and polyamides, have the necessary combination of heat resistance, deformation temperature, flexural modulus and flammability required for use in high temperature rinses, for example, electrical applications. . However, the high costs and complications associated with injection molding have made injection-molded substrates less desirable even for use in printed circuit boards than die-cut phenol laminates.

It has also been proposed to manufacture such wiring panels from extruded sheets of filled thermoplastic polymers. Extrusion has the advantage that it is a continuous and relatively inexpensive method for manufacturing filled thermoplastic sheet materials. However, it has not hitherto been possible to develop an extruded sheet of filled thermoplastic polymer suitable for this purpose. A particular apparent flaw of known extruded sheet of filled and in particular glass-filled thermoplastic polymer is that this material is a very rough and uneven surface which severely limits the commercial use, especially the use in printed wiring boards and other electrical parts.

This prior art inability to develop a satisfactorily extruded sheet of filled thermoplastic material is particularly pronounced with filled polyalkylene terephthalate compositions, especially glass filled polybutylene terephthalate compositions. As is known, glass-filled polybutylene terephthalate compositions as described in U.S. Pat. Nos. 3,776U,576, 3,801,530, 3,873879Ι, 3.81U.725, 3,903.0U2, K.052.356, U.123. ^ 15 and U.12U.561 a unique combination of physical properties making these compositions ideally suited for use as substrates for printed wiring harness 800 43 92 3 L, panels and other electrical applications. Although U.S. Pat. Nos. 3,7 ^ -2,087 and 3,5 ^ 0.96k suggest that filled polybutyl graft alate formulation and extruded sheet material can be extruded, previous attempts at producing such material have resulted in commercially unacceptable materials of low melt strength and a very rough rollercoaster surface. Previous attempts at manufacturing an extruded polybutylene terephthalate sheet have been so unsuccessful that despite an extremely high demand for such material on the current market, there is actually no extruded glass-reinforced polybutylene terephthalate sheet material available.

Another approach to the problem of manufacturing a filled thermoplastic sheet material is described in U.S. Pat. Nos. 2,950,502 and 3,07-111.

According to each of these patents, a filled thermoplastic sheet material is formed by calendering a plasticizer-containing mixture of filler and thermoplastic material into a sheet and then polishing the obtained sheet with heated rollers. U.S. Pat. No. 2,950,502 uses a layer of poly-siloxane compound to prevent the sheet from sticking to the polishing roller. However, similar methods are unsuitable for the manufacture of glass-filled sheet material, since calendering to form a sheet from the mixture of thermoplastic polymer and glass fibers, as opposed to extrusion, results in a significant amount of unwanted glass fiber crush. In addition, the process of U.S. Pat. No. 3, 07U.11U is unsuitable for use with polymers which must dry while also using such a high drop rate that no good surface appearance can be obtained. Each of these patents 30 relates in principle to the production of wear surfaces for floors with good color and pattern differentiation and is therefore not directed to the manufacture of filled thermoplastic sheets suitable for electrical applications.

U.S. Pat. No. 2,061,0 ^ 2 still states that one can form an unfilled cellulose ester sheet material with an 800 43 92 k more uniform thickness by providing a break between the screw and the sheet die of an extruder to allow flow into the stream. of cellulose ester to create a pressure drop and develop a more uniform die pressure. However, the art has yet to develop a suitable method for manufacturing extruded, filled thermoplastic sheet material.

Thus, there is a great need in the art for the development of an extruded thermoplastic sheet material suitable for use in electrical applications, as well as a method suitable for the manufacture of such material.

Thus, the invention relates to a new, continuous, extruded, thermoplastic sheet material, suitable for use in electrical applications as well as in other applications, where a filled material with a good surface appearance is desired. The material consists of an extruded sheet material of a thermoplastic polymer containing 5-60% by weight of reinforcing filler, having a polymer-rich surface and further with a gloss number of at least 15 and a surface roughness of less than 150 microinches.

The invention also relates to a method of manufacturing the above sheet material. In this process, a thermoplastic polymer containing 5-60% by weight of reinforcing filler is extruded into a continuous laminar melt flow, this laminar melt flow is transferred to a hot, highly polished surface, and then the melt flow with the hot highly polished surface in contact at a temperature of 93 ° C to the temperature at which the thermoplastic polymer sticks to the hot, highly polished surface and at a pressure sufficient to allow the filler to withdraw from the surface of the melt flow is and thus obtains a continuous, filled, thermoplastic sheet material with a smooth, glossy, polymer-rich surface.

In other embodiments of the present invention, further improvements in surface appearance can be achieved by extruding the filled thermoplastic polymer under conditions such that the flow of thermoplastic polymer has a substantially oriented flow in the extrusion direction and reduced axial-rotational flow at the point of entry into the sheet die. The sheet quality can be further improved by using a pressure drop system, between which a nip is located, as a hot, highly polished surface and thereby passing the filled thermoplastic polymer through the nip under conditions such that upstream of the nip but a melting reservoir of filled thermoplastic polymer is maintained in its immediate vicinity.

The invention also relates to a device for use in the present method. This device 15 includes a screw extruder, a sheet die, means disposed between the screw extruder and the sheet die and converts the flow of thermoplastic material from a screw cap-like flow into a substantially oriented laminar flow and a heated, highly polished pressure drop system.

In a further embodiment of the invention, a bursting plate is also used in the extrusion of filled thermoplastic sheet material. This rupture plate consists of a rigid plate, which is provided with a number of spaced ports which extend through the plate and slowly converge the flow of the thermoplastic polymer passing through the plate and direct the filler contained therein.

According to the invention, a new, extruded thermoplastic sheet material with the physical properties of a filled sheet material and an almost as good surface appearance as that of an unfilled sheet material is obtained. Moreover, the new sheet materials of the invention also show a better dielectric strength. compared to compression-molded samples of the same thickness and are therefore very suitable for electrical applications.

The present sheet material can consist of all kinds of known thermoplastics, from which 800 4392 sheets are usually manufactured. A particularly great advantage of the invention is that it is now possible to produce new, good quality extruded sheets from crystalline thermoplastic polymers such as the polyalkylene terephthalates and polyamides, which have hitherto only been extruded with great difficulty. Since a commercially acceptable extruded polyalkylene terephthalate sheet material, and in particular a polybutylene terephthalate sheet material, is highly desirable because of its unique combination of physical properties, the invention thus provides a newly filled polyalkylene terephthalate sheet material and a method for its manufacture. This material consists of an extruded sheet of a polyalkylene terephthalate polymer containing 5-60% reinforcing filler, namely polyalkylene terephthalate homopolymer and / or copolymer, for example polybutylene terephthalate, mixtures thereof and mixtures thereof with minor amounts of other thermoplastic polymers, with a rolymer rich surface, a gloss number of at least 15 and a surface roughness of less than 150 microinches.

The invention is further elucidated in the accompanying drawing, of which fig. 1 is a cross-section of the device and method of the invention, fig. 2 is a schematic cross-section of the preferred method of manufacturing the extruded, filled sheet materials of the invention, Fig. 3A is an enlarged end view of the rupture disc used in the device of Fig. 1, Fig. 3B is a section along line 2B of the rupture disc of Fig. 2A, Fig. KA is an enlarged end view of a second embodiment of a rupture disc, Fig. UB is a section along line 3B of the rupture disc of Fig. 3A, Fig. 5A is an enlarged section of another embodiment of the rupture disc used in the apparatus of Fig. 1, Fig. 5B is a section is taken along line UB of the 800 4 3 92 τ rupture disc of fig. kA, fig. 6 is a photograph of an extruded sheet of glass-filled poly (1, H-butylene terephthalate) shown at a magnification of 500X. nolymer-rich surface of the ve 1-5 shows material of the invention and FIG. T is a photograph of a vertical cross-section with a plane perpendicular to the extrusion direction of the extruded sheet of FIG. 5 after the sheet has been broken to expose the glass fibers , shown at a magnification of 200X.

The present invention is based on the discovery that contacting an extruded, filled, thermoplastic sheet material with a highly polished surface under pressure and at high temperatures causes the filler to anterate to the interior of the sheet to obtain a smooth, glossy poly-15 more-rich orm planar above. By extruding a filled thermoplastic polymer into a sheet and then contacting the sheet at a temperature and pressure with a highly polished surface to form a polymer-rich surface on the sheet, a new extruded sheet material can be obtained with the physical properties of a filled sheet material and a surface appearance almost as good as that of an unfilled sheet material. Moreover, due to their polymer-rich surface, the present extruded sheet materials have better dielectric strength than conventional filled sheet material with a non-polymer-rich surface, which aspect is highly desirable in electrical applications.

The heating and pressure exerted on the sheet material during contacting not only migrate the filler from the sheet surface, but also appear to contribute to the curing of the thermoplastic material to a stable sheet. This aspect is particularly advantageous in the manufacture of stable sheets from low-extruded crystalline thermoplastic polymers of low melt strength, for example, polybutylene terephthalate, because it allows for the first time to produce a stable, non-slack sheet material from this polymer.

8004392 8

The novel extruded, filled thermoplastic sheet materials of the invention may consist of a variety of thermoplastic polymers, from which sheets have hitherto been manufactured in conventional ways. Examples of suitable thermoelastic polymers are polyolefins such as polyethylene, polypropylene and copolymers thereof, polyphenylene oxide polymers and copolymers, styrene polymers and copolymers such as polystyrene, styrene-acrylic acid-nitrxl nolymers, styrene-butadiene-acrylic nitrile copolymers, nolyaryl ether polymers Polyurethane nolymers and conolymers, vinyl halide polymers and co-polymers such as vinyl chloride, polytetrafluoroethylene and acrylic polymers and copolymers such as polymethyl methacrylate.

As mentioned above, the new sheet materials of the invention may also consist of thermoplastic polymers which have hitherto been difficult to extrude into sheets, for example polyesters, polyamides and polyoxymethylene polymers and low melt strength copolymers. Actually, as will be further described, the invention provides for the first time a commercially acceptable extruded polybutylene terephthalate sheet material. Examples of other such low melt strength thermoplastic polymers which may comprise the novel sheets of the invention include nolyamides such as polycanrolactam, polyhexamethylene adipamide, polyhexamethylene bacimide, polyhexamethylene lanrinamide, polv (1,2-aminolauric acid) and poly (1.1 -amino-decanoic acid), polyesters, as polybutylene terephthalate and its copolyesters, polyethylene terephthalate, glycol-modified polyethylene terephthalates, poly (1, H-cyclohexamethylene terephthalate), and its glycol-modified copolyesters, poly (butylene tetramethylene ether terephthalate as ethoxyl ether phenol polyesters), modified polybutylene terephthalate and polyoxymethylene polymers such as polyoxymethylene itself and various acetal copolymers as described in U.S. Pat. No. 3,027,352. The sheets of the invention may also consist of branched polyesters such as branched polybutylene terephthalate polyesters based on pentaerythritol.

Branched polybutylene terephthalate polymers and their preparation are described in U.S. Patent 4,043,992 in U.S. Pat. No. 3,951. It is also possible to use mixtures of all kinds of the above-mentioned polymers with each other (for example mixtures of polyethylene terephthalate and polybutylene terephthalate) or with other thermoplastic polymers (eg mixtures of polyalkylene terephthalate with polycarbonates).

The subject sheets also contain 5-60, preferably 20- 5% by weight reinforcing filler. The term "reinforcing filler" as used herein refers to a non-continuous filler. Examples of suitable reinforcing fillers are glass fibers, asbestos fibers, cellulose fibers, carbon fibers, synthetic fibers such as polytetrafluoroethylene fibers, metal fibers, as well as other fillers such as mica, talc, calcium silicate, carbon black, kaolin, porcelain earth, silicon dioxide, metal powders, etc. Particularly preferred is one of the aforementioned thermoplastic polymers filled with glass fibers and combinations of glass fibers with one or more of the above reinforcing fibers and / o. other fillers.

A particularly attractive combination of fillers is the combination of glass fibers with a sufficient amount of polytetrafluoroethylene to delay the dripping of the preparation. As is known, polytetrafluoroethylene acts as an effective drip retardant for neat glass filled polymers.

The glass fibers can consist of all kinds of known types of glass fibers. Suitable glass fibers are commercially available everywhere, and all kinds of such glass fibers are suitable for use in the invention. In sheet materials which are ultimately to be used for electrical applications, it is preferable to use elemental glass fibers consisting of lime-aluminum borosilicate glass, which is relatively soda-free and known as "E" type glass. use other types of glass fibers, when the electrical properties are not so critical, for example type "C" glass fibers.

The glass fibers can be manufactured by standard methods, for example, by steam, blowing with air, blowing in the flame and mechanical pulling. For example, the glass fibers have 8004392 10 a diameter of 0.003-0.018 mm and a length of 1.6-50 mm. The glass fibers can also be bundled into strands and fine yarns, which can migrate through the polymeric component of the sheet. However, the exact length and thickness of the glass fibers is not critical to the invention.

Ground glass and glass balls can also be used.

The subject sheets may also contain other preferred additives such as dyes, pigments, lubricants such as long chain aliphatic waxes, thixotropic agents, plasticizers, flame retardants, antioxidants and drip retardants. A particularly preferred sheet material consists of any of the above thermoplastic polymers, 5-60, preferably 20-5 wt. Glass fibers and a flame retardant amount of a suitable flame retardant. The sheets of the invention may also contain an impact modifier such as an elastomer, an acrylic polymer, for example, a nolymethyl methacrylate or a polycarbonate polymer.

All kinds of suitable known flame retardants can be used in the invention. Synergistic combinations of flame retardants as are well known in the art are particularly preferred. Examples of suitable flame retardants are combinations of aromatic halides and elements of group Vb of the Periodic Table such as phosphorus, arsenic, antimony and bismuth and halo-no aromatic carbonate polymers and combinations thereof with antimony compounds as described in U.S. Pat. No. 1212. 561. Particularly preferred flame retardants are the flame retardants disclosed in U.S. Pat. No. 3,873.H91 and a combination of decabromobiphenyl ether and antimony trioxide, the latter combination being the most preferred.

The flame retardant combination of antimony trioxide and decabromobiphenyl ether is usually used in an amount sufficient to provide 2-10% by weight of antimony trioxide and 3-15% by weight of decabromobiphenyl ether. If one of the above halogen-35 polycarbonate polymers is used as a flame retardant, the sheet 800 4 3 92 11 material usually contains 10-50 wt% polycarbonate polymer. Synergistic combinations of halo polycarbonate, antimony trioxide and decabromobiphenyl ether are also highly preferred.

In the manufacture of 5-sheet polyalkylene terephthalate, the polyalkylene terephthalate polymer itself may also be flame retardant. For example, one can use a flame-retardant bromine-containing copolyester consisting of polybutylene terephthalate modified with ethoxylated tetrabromobisphenol-A. The advantage of this polymer type is that it eliminates the need for a separate flame retardant and thereby eliminates "clogging".

An important aspect of the sheets of the invention is that they have a polymer-rich surface. As already stated, due to this unique aspect, the present sheets have the physical properties of a sevull thermoplastic polymer sheet and at the same time a surface appearance almost as good as that of an unfilled thermoplastic polymer sheet. The presence of a pol: multi-rich surface also gives the sheets of the invention better dielectric strength compared to compression molded samples of the same thickness. The expression "polymer-rich surface" used herein means that the sheets of the invention have an surface which is substantially free of exposed filler such as glass fibers and substantially composed of a layer of unfilled thermoplastic polymer. Sheets with such a surface have a gloss number of at least 15 ", preferably at least 30 and most preferably at least 50 as measured by ASTM method E97 at a measuring angle of 1 * 5 ° using a Gardner Multi-Angle Glossmeter Model 66-9095. A poly (1,1-butylene terephthalate) sheet containing 31% by weight glass fibers and having such a surface is shown in FIG.

As a further consequence of the unique polymer rich surface of the subject sheets, as well as of the novel process used to produce such material, the subject extruded sheets also exhibit a surface roughness of less than 150 microinches, preferably less 35 than 100 microinches, and preferably less than 50 microinches, measured in the midline of the sheet according to the American Standard Surface Texture method ASA BU6.1-1962 using a Brush Surf Indicator smoothness meter available from Guild Company, standard ASA electro-formed metal standards and a constant 5 pin arm speed of 3.2 mm per second. Since the above standard test methods and apparatus are generally known, a further description can be omitted.

For example, the new sheets of the invention have a thickness of 0.25-3 mm, preferably 1-1.8 mm, and include everything commonly referred to as sheet and film. The subject sheets can therefore be used in any application where a filled, extruded, thermoplastic sheet with good surface appearance can be used. Due to their excellent physical properties, including their dielectric strength and surface appearance, the subject electrotechnical fields can be used particularly well as substrates for printed circuit boards, electrical support panels, potentiometers and foil switches.

Particularly preferred sheets of the invention consist of a crystalline thermoplastic polymer and a reinforcing filler such as glass fibers. Such sheets have a unique combination of physical properties, making them well suited for electrical applications. The term "crystalline thermoplastic polymers" as used herein refers to the thermoplastic polymers, which can form solid crystals of a certain geometric shape. Examples of suitable crystalline thermoplastic polymers are the polyolefins such as polyethylene, polypropylene and their copolymers, polyphenylene oxide polymers, polyoxymethylene homopolymers and copolymers, polyamides such as polyhexamethylene adipamide, polyhexamethylene-30 sebacimide, polycaprolamethyl-polyurin-1,2-polyhexamino ) and poly (1,1-aminoundecanoic acid) and polyesters such as polyethylene terephthalate, polypropylene terephthalate and polybutylene terephthalate. In a preferred embodiment, the crystalline thermoplastic polymers preferably used in the present sheets are polyhexamethylene adipamide, an acetal copolymer formed 8004392 13 from formaldehyde and ethylene oxide or 1,3-dioxolane, polyethylene terephthalate, polybutylene terephthalate and mixtures of polyethylene terephthalate and polybutylene blends of polyethylene terephthalate or polybutylene terephthalate with polycarbonates. The above crystalline thermoplastic polymers are well known and available. For example, polyhexamethylene adipamide is readily available commercially as nylon 6/6. Likewise, the preferred acetal copolymer described above may be commercially available under the name Celcon from the Celanese Plastic Materials Company or may be prepared according to U.S. Pat. No. 3,027,352. Preferred polyhexamethylene adipamide polymers and acetal copolymers are those with a relative viscosity of 50-300 and a weight average molecular weight of 18,000 and 50,000, respectively.

Because of its unique combination of heat resistance, for example U.L. recognized Class B status (130 ° C), deformation temperature, high flexural modulus, low flammability and non-dripping and non-flammable character, making it ideally suited for use in the manufacture of printed circuit boards, is glass fiber reinforced polyethylene terephthalate is the polymer most preferred for use in the present sheets. Suitable polyalkylene terephthalates for use in the present invention are polyethylene terephthalate and polybutylene-terephthalate homopolymers, copolymers, mixtures thereof, and mixtures thereof with minor amounts of other thermoplastic polymers as described above. Especially advantageous polybutylene terephthalates are polybutylene terephthalate homopolymers. Such polymers are well known and can be prepared from the reaction product of terephthalic acid or a dialkyl ester of terephthalic acid (especially dimethyl terephthalate) and diols with b carbon atoms. Suitable diols are, for example, 1,3-butanediol, 1,3-butanediol, 1,2-butanediol and 2,3-butanediol, of which 1,3-butanediol is most preferred. The preparation of these polymers and highly desirable compositions containing these polymers are described in U.S. Pat. Nos. 3,801,530, 3,76k,576, 3,8lk. 725, 3,873. 91 and 3,903.0k2.

Extruded sheets with highly desirable physical properties consist of one of the above polymers in combination with 5-60 wt.%, Preferably 20-k5 wt.% Glass fibers and optionally 1-12 wt.% Antimony trioxide, 3-15 wt. % decabromobiphenyl ether and other optional additives and fillers as described above.

A particularly preferred substrate for a wiring panel according to the invention consists of an extruded sheet material of poly (1, U-butylene terephthalate) containing 5-k5 wt.% Glass fibers, preferably 20-k5 wt.% glass fibers, 1-12% by weight of antimony oxide, 3-15% by weight of decabromobiphenyl ether and 1-50% by weight of asbestos fibers and furthermore a polymer-rich surface, a gloss of at least 15, preferably 30 and preferably 50 and has a surface roughness of less than 150 microinches, preferably less than 100 microinches and most preferably less than 50 microinches. Instead of or in addition to the asbestos fibers, the sheet material may also contain 0.05-15 or more wt. contain polytetrafluoroethylene as a filler.

Poly (1, k-butylene terephthalate), which is preferably used in the wiring panel described above, has an intrinsic viscosity of 0.2-2.0 dl / g as measured in a 60: k0 mixture of phenol and 1.2 o -dichlorobenzene at 25 ° C. Due to the relatively low cost, poly (1,1-butylene terephthalate) with an intrinsic viscosity of 0.65-0.75 dl / g is particularly preferred.

The invention also provides a method and apparatus for use in the manufacture of the new sheet material described above. This method involves melt extrusion of a mixture of any of the above thermoplastic polymers, eg poly (1, k-butylene terephthalate), in addition to one or more of the above-described fillers, preferably glass fibers, into a continuous, laminar melt flow. The laminar melt flow then obtained is then transferred to and contacted with a hot, highly polished surface at a temperature of 93 ° C, preferably 121 ° C, to the temperature at which the polymer is hot. 3 92 15 highly polished surface becomes adhesive and at a pressure sufficient to withdraw the filler from the surface to yield a sheet having a smooth, glossy, polymer-rich surface.

In the preferred embodiment of the present process, further improvements in surface appearance, as well as in melt strength, can be achieved by extruding the filled, molten polymer into a sheet under conditions such that it is fed to the mold in a substantially the extrusion directionally oriented flow and a reduced axial-rotational flow. Sheets with further improved surface appearance can be obtained by using a pressure rolling system as a hot, highly polished surface and then passing the filled polymer through the roll nip under such conditions that there is a melting reservoir of filled thermoplastic norm upstream of the nip but in its immediate vicinity is maintained.

Referring to the drawings, Figure 1 shows the preferred method and apparatus for manufacturing the sheets of the invention. For the sake of clarity, the present process is hereby illustrated with the manufacture of a glass fiber filled poly (1, H-butylene terephthalate) sheet material, although it is emphasized that the process of the invention is equally advantageous for the manufacture of all kinds of protruding sheets from all kinds of thermoplastics described above, or all kinds of other thermoplastics as are known in the art.

As shown in FIG. 1, a molten mixture of polybutylene terephthalate and glass fibers is extruded through a conventional screw extruder, which may be a vented screw extruder. When the flow of molten polymer leaves the extruder 1, it has a flow component in the extrusion direction and a flow component in an axial-rotational direction, i.e. a screw cap-like flow. The stream of glass-filled polybutylene terephthalate is then transferred to an 800 43 92 16 chromium-plated plate die 5, preferably a coated hanging plate type die, in which the stream is converted into a continuous laminar, irregular surface melt flow.

The exact extrusion conditions are not extremely critical and vary with the thermoplastic polymer involved and the extruder involved. At a 1? inch screw extruder with a compression ratio of 2.9-1, for example, the thermoplastic polymer is extruded at a temperature of 238-271 ° C, a screw rotation per minute of 60-90, a 10 head pressure of 2100-3500 kPa gauge pressure, a throughput of 2.1-3 m / minute, a gauge thickness of 0.01-0.125 inches, preferably 0.0H-0.07 inches and an extrusion rate of 30-55 kg / h, preferably of about k5 kg /hour. However, it is essential that uniform pressure is maintained in the mold and pressure fluctuations across the mold are avoided. Best results are also obtained by using a long die with a length of 0.5-10 cm, for example about 5 cm.

It has been discovered that further improvements in sheet appearance can be obtained by feeding the stream of thermoplastic polymer, for example of poly (1,1-butylene terephthalate) to sheet die 5 under conditions such that the stream enters at the time of entry. the mouth of die 5 has a substantially oriented flow in the extrusion direction. Although all kinds of known methods can be used to achieve this flow pattern, in the embodiment of fig. 1 a rupture plate 3 is arranged between screw extruder 1 and the mouth of sheet die 5. As appears from fig. 3-5, rupture plate 3 contains a number of spaced-apart arrays of gates that converge toward the mouth of sheet die 5. In the embodiment of fig.

3A and B, rupture disc 3 has a central longitudinal passage 21 with a converging funnel-shaped neck and in a circle around it a first series of six spaced converging ports 23 and around it a second series of six spaced converging ports 25. Rupture plate 3 is also provided with a serrated feed ring 19 opposite screw 1.

8004392

TT

The exact size, number, and arrangement of the ports in rupture disc 3 is not critical and may vary with the desired flow pattern as shown in Figures 4 and 5. In Figures kA and B, a third series of 12 is spaced apart 5 converging gates 35 located around a gate arrangement, which is the same as shown in Figs. 3A and B, consisting of a central longitudinal passage 29, a first series of six spaced converging gates 31 and a second series of six spaced apart converging ports 33. Also provided is feed ring 27 which serves to transfer thermoplastic from screw 1 after each of the above ports. In Figs. 5A and B, rupture disc 3 comprises feed ring 37, central passage 39, a first series of 12 all-round converging ports 1 + 3 and a second series of 12 all-round converging ports 1 + 5, which surround gates 1 * 3 lie,

Each of the rupture plates described above creates a pressure drop in the system and converts the screw 1 flow of thermoplastic polymer from a screw cap-like flow into a substantially oriented flow by converting the flow 20 of thermoplastic polymer at the mouth of die 5. As a result thereof a more uniform pressure is maintained in the sheet die and pressure variations are avoided therein, resulting in the filled, extruded sheet material having an excellent surface appearance, although a bursting disc with a number of straight-running, non-converging using ports to create a pressure drop and orient the flow of thermoplastic polymer, the best results are obtained with rupture plates of the invention. Because of the new structure of the present rupture plates, a greater pressure drop and thus a large pressure stabilization can be achieved than with a rupture plate with straight-running, non-converging ports.

During the extrusion of thermoplastic polymer, a high pressure and shear zone is created, around the circumference of screw 1, and a low pressure zone is created 800 43 92 18 at the tip of screw 1. Thus, a greater pressure drop can be created by removing polymer from the low pressure zone at the tip of screw 1 then by removing polymer from the high pressure zone around the circumference of the screw. Because of the high pressures involved in the extrusion process, it is desirable that some ports be provided in the high pressure region around the periphery of the rupture disc.

Accordingly, in the rupture plates of the invention, each of the rupture plates shown in Figs. 3-5 is provided with a relatively large central mandrel, thereby removing a substantial amount of polymer melt flow at relatively low pressure and shear. In addition, each of the surrounding ports converges as ports 23 and 25 of the rupture disc shown in Figure 3 to the mouth of sheet die 5. By convergence of the surrounding regions as ports 23 and 25, the polymer melt flow passing through ports 23 and 25 must travel a longer path than the polymer flowing through central port 21. As a result, greater pressure drop and stabilization are achieved, leading to a more stable polymer flow.

In establishing a stable flow of thermoplastic nolymer, pressure stabilization is not only important, but by passing the melt flow under controlled pressure through the rupture disc, less degradation of the thermoplastic polymer itself occurs, which further contributes to better multiplicity. 25 shelves and appearance. It is also noted that a more uniform temperature occurs near the center of the rupture plate and by allowing the ports to converge through the rupture plate, the thermoplastic polymer is passed through the rupture plate at a more uniform temperature, which also reduces polymer degradation.

Another important advantage of the above-mentioned rupture plates is that they slowly converge the flow of molten polymer, so that the filler contained therein is directed in the extrusion direction and does not become transverse, causing buildup in the system.

Aligning the fibers with their longitudinal axes 800 4 3 92 19 in the extrusion direction further enhances the surface appearance, especially with regard to smoothness. In addition, it was discovered that targeting the filler not only contributes to a better surface appearance, but targeting the filler also increases the melt strength of the filled thermoplastic polymer, making polymers of low melt strength such as polyamides and polyesters much easier can extrude into sheets. The alignment of the filler is believed to create a bridge effect between the polymer chains, resulting in a sheet material of greater melt strength.

Although the invention has been described with the use of a rupture disc, other organs with similar functions may also be used instead. For example, one can make good use of a static mixer, either alone or in combination with rupture disc 3.

The laminar melt flow then obtained is then contacted with a hot, highly polished surface at a temperature and pressure suitable for forming a smooth, glossy, polymer-rich surface. As can be seen from Fig. 1, this hot, highly polished surface preferably consists of a pressure drop system, generally indicated by 9. However, an electrostatic pin can also be used if desired. The pressure roll system 9 generally contains a sufficient number of rollers and can be pressurized. and temperature sufficient to form the above polymer-rich surface on the sheet. The best results are obtained with a pressure drop system with a mirror-smooth chrome coating on the rollers. Pressure roller system 9 is also preferably as close as possible to the exit of sheet die 5 in order to minimize cooling of the sheet and premature curing thereof,

Pressure roller system 9 generally includes at least two nips. Excellent results are obtained, especially with sheets of crystalline polymers such as poly (1, U-butylene terephthalate), by using a vertical stack of at least three highly polished rollers as shown in Fig. 1 under numbers 11, 12 and 800 43 92 20 13. The advantage of such an arrangement is that it causes the heated rollers to lie extremely close together, which is very advantageous in the processing of sheets of crystalline polymers such as polybutylene terephthalate.

Rollers 11, 12 and 13 are maintained under a temperature and pressure sufficient to produce a glossy smooth polymer-rich surface on the sheet material, preferably sufficient to produce a polymer-rich surface with a gloss number of at least 15, preferably at least 30, and most preferably at least 50, and a surface roughness of less than 150 microinches, preferably less than 100 microinhes, and most preferably less than 50 microinches. For example, the temperature of the rollers varies from 93 ° C to the temperature at which the thermoplastic polymer becomes adhered to the rollers. Best results are obtained by using rollers which are as hot as possible, with temperatures of 121 ° C to the temperature at which the polymer will adhere, being particularly preferred. In crystalline thermoplastic polymers such as polybutylene terephthalate, the temperature of the rollers generally ranges from 93 ° C and preferably from 121 ° C to the melting point of the polymer.

The temperature of the rollers may also be the same or decrease slowly from the top roll to the bottom roll to effect slow cooling of the sheet as the pressure roll system 9 passes. In the case of sheets of crystalline polymers such as polybutylene terephthalate, the latter method is particularly preferred. As discussed above, in addition to retracting the filler to the interior of the sheet, heat and pressure also contribute to the curing of low melt strength crystalline polymers such as poly (1,1-butylene terephthalate), thereby rendering this polymer type can successfully extrude into a stable, non-liquid sheet material.

Rollers 11, 12 and 13 can be heated in any known manner, for example with steam, oil or electric. A clamping pressure of 25-35 kg is generally also maintained between the rollers. The gap opening alternates with the polymer involved.

800 43 92 21

Best results are also obtained by aligning the roller speed with the extruder to minimize any linear stress on the sheet and differential shrinkage.

After the pressure drop system 9 has passed, the treated sheet passes a number of tensile drops 15 in order to stretch it. Drain traps 17 then remove the final sheet for storage, etc. Preferably, the speed of the extruder, rolls 11, 12 and 13, rolls 15, and rolls 17 are synchronized in order to avoid linear tension on the sheet material.

Fig. 2 shows a preferred method of manufacturing the sheet of the invention. In the embodiment of Fig. 2, a continuous, oriented, laminar melt flow is applied to roller 12, slightly upstream from the nip or slit, which is formed between rollers 11 and 12 and passed through the knees under conditions such that a melt reservoir 6 of molten thermoplastic polymer, maintained slightly upstream, but in the immediate vicinity of the nip. During start-up, rollers 11-13 and expeller-20 rollers 15 are run slightly slower than extruder 1, creating melt reservoir 6. The speeds of extruder 1, rollers 11-13 and rollers 15 are then synchronized to keep the melting reservoir at the desired size. Preferably, in order to promote synchronization and to maintain melting reservoir 6 at its desired size, optical sensing means 7, which is preferably connected via a microprocessor to the driving rings of extruder 1, rollers 11-13 and rollers 15

It has been found that the size of melting reservoir 30 is relatively important for the surface appearance of the sheet and for an optimum surface appearance should be neither too thin nor too thick. The exact size of melting reservoir 6, which is required for an optimum sheet appearance, varies with the particular composition to be processed, the thickness of the desired sheet material, etc.

35 and are easily determined empirically.

800 4392 22

By operating in the manner described above, further improvements in sheet appearance can be obtained compared to a rolling operation as shown in Fig. 1.

The following examples illustrate the invention.

Example I

A poly (1,1-butylene terephthalate) polymer was extruded with an intrinsic viscosity of 0.72 dl / g, which was 31 wt.% 0.5 cm long Owens Coming K ^ 19 AA. glass fibers, .85 wt.% antimony trioxide, + +, 85 wt.% decabromobiphenyl ether and 2.6 wt.% asbestos fibers 10, into a sheet using a h. cm diameter unventilated screw, a compression ratio of 2.9-1 and 60 rpm. and a chromed, long-flared 20 cm wide aleet die with a removable bottom, a spout of 5 cm and an adjustable gap of 0.75-1.5 mm. A bursting disc of the embodiments shown in Figs. 5A and 5B was also used. Gates Onion have a diameter of 0.5 cm and are placed at an angle of 30 ° to the longitudinal axis of the shear-hole. Ports ^ 3 have a diameter of 3.2 mm and are placed at an angle of h5o with the longitudinal axis.

Before processing, the above material is dried for 3 hours at 135 ° C. The extrusion profile is then adjusted and the extruder equilibrated by extruding about 25 kg of polymer through it. Thereafter, an oriented laminar melt flow having a thickness of 1 mm with an extrusion speed of 2.7 m / min, an extrusion temperature of 21 ° C, a die temperature of 266 ° C and a head pressure of 5600 were produced. kPa.

The resulting laminar melt flow was then passed through a stack of three highly polished, heated, 25 cm diameter chrome plated rollers placed as close as possible to the plate die. The top roller is set to a gap of 1.25 mm with a pressing pressure of 30 kg. The temperature of the rollers is maintained at 130 ° C for the top roll, 12 ° C for the middle roll and 93 ° C for the bottom roll with Stereo Oil Thermolators, respectively. The roller speed is also synchronized with the extrusion speed of 2.7 m / min. in order to obtain a melting reservoir 800 4392 23 of polymer as shown in Fig. 2.

After passing through a number of tensile dips, the physical properties, surface roughness and surface gloss of the final sheet are measured using a 20 cm sample of the sheet. All measurements are made according to the standard ASTM procedure, with the measurement of physical properties in the extrusion direction. The gloss is measured at an angle of 1 * 5 ° according to ASTM E97, using a Gardner Multi-Angle Glossmeter Model 66-9095 and standard highly polished metal-10 standards as required by this test method. Surface roughness is measured at the center of each 20 cm sheet sample according to American Standard Surface Texture method ASA BU6.1-1962 using a Brush Surf indicator smoothness meter and ASA electroformed metal standards. The pen of the above instrument is advanced over the sample at a constant speed of 3.2 mm / sec. The results of these determinations were as follows:

Tensile strength (kPa) 93,100

Tensile Elongation (%) 0.97 20 Tensile Modulus (X10 ^) 1.66

Flexural modulus (X10 ^) 1.80

Flexural strength at break (kPa) 177,100

Gardner stroke (inch / pound) 2.5

Dielectric strength Λ (volt / mm) 26,000 25

Gloss 16.5 (top surface)

Roughness (microinches) 60

The above sheet is also examined under a microscope to verify the regularity of the sheet surface and the direction of the glass fibers contained therein. Fig. 5 is a photograph of the sheet surface at 500X magnification. Fig. 6 is a photo with a magnification of 200X of a cross section over a plane perpendicular to the direction of extrusion of the sheet after it has been broken to expose the glass fibers. As shown in Figures 5 and 800 4392 2k as confirmed by the aforementioned measurements of gloss and smoothness, the poly (1,1-butylene terephthalate) sheet produced in this test has a very smooth, glossy polymer-rich surface, while very few glass fibers can be seen on the surface.

Fig. 6 also shows that the sheet glass fibers extend substantially in the longitudinal direction, which further contributes to the attractive surface appearance and melt strength. Furthermore, as shown above, the sheet has excellent physical properties. In fact, it has been found that the subject sheet, due to its polymer-rich surface, has a significantly improved dielectric strength compared to known thermoplastic sheet, which aspect is very advantageous for electrical applications.

For comparison, the above test is repeated with a known sheet extrusion method, ie without the bursting plate and the heat and pressure treatment of the invention. The sheet obtained appears to be so fluid and uneven and to have such a low melt strength that physical measurements cannot be made on it.

Example II

20 Using the device and method

In Example I, a poly (1,1-U-butylene terephthalate) polymer was extruded with an intrinsic viscosity of 0.72 dl / g containing 30% by weight 0.5 cm Owens Corning ΙΛ19ΑΑ glass fibers into a continuous sheet of thickness from 1.5-1.75 mm. The obtained sheet was found to have a highly desirable surface appearance and highly desirable smoothness. Example III

In the same manner as in Example 1, an extruded sheet with a thickness of 1.5-1.75 mm was prepared from a filled poly (1, U-butylene terephthalate) preparation. The composition contained 55.5% by weight polybutylene terephthalate polymer of Example I, 51% by weight of which was in flake formulation and 5% by weight in powder form, 31% by weight Owens Corning 0.5 cm I & 19AA. glass fibers, 5.5% by weight SbgOg, 5.5% by weight deeabromobiphenyl ether, 0.5% by weight Dupont Teflon K polytetrafluoroethylene fibers and 2% by weight 35 Union Carbide Phenoxy PKHH, a thixotropic agent prepared by reaction of 800 4392 bisphenol A and epichlorohydrin.

After manufacture, surface gloss and surface appearance of the obtained sheet were determined, and it was found that they were very suitable for commercial use.

The above examples clearly show that according to the invention new and unique sheets can be manufactured. In addition to the significant improvements in surface appearance and dielectric strength which are promoted by forming a polymer-rich surface, the above examples also show the beneficial effect that the heat and pressure treatment and the increased melt strength have on the sheets obtained, thus making non-liquid stable sheets available from such hard-to-extrude polymer as poly (1, k-butylene terephthalate). Thus, the present invention makes a very desirable contribution to the technique of extrusion of filled thermoplastic sheet material.

800 43 92

Claims (36)

A method of manufacturing a filled, extruded, continuous thermoplastic sheet material, which contains 5-60% by weight of reinforcing filler and has an improved surface smoothness, gloss and melt strength, characterized in that in sequence: a, a filled thermoplastic polymer matrix extrudes into a continuous, laminar melt flow, b, transfers this laminar melt flow to a hot, highly polished surface, and c, contacts the laminar melt flow with the hot, highly polished surface at a temperature of 93 ° C to the temperature, wherein the thermoplastic polymer adheres to the hot highly polished substrate and at a pressure to withdraw the filler from the surface of the laminar melt flow and to produce a continuous, filled, thermoplastic sheet material having a smooth, glossy, polymer-rich surface is sufficient. 2. Process according to claim 1, characterized in that the filled thermonlastic polymer matrix is extruded into the laminar melt flow by forming a melt flow of the filled thermoplastic polymer matrix, supplying this melt flow under such conditions and directing it to a plate die. that the flow of the melt flow and the filler contained therein are oriented substantially in the extrusion direction and the melt flow extrudes through the sheet die to the continuous laminar melt flow. 3. Process according to claim 2, characterized in that the filled, thermoplastic polymer matrix is directed in the substantially oriented flow towards the sheet die and fed by forming a molten flow of filled thermoplastic polymer matrix with a flow component in the extrusion direction and an axial, rotational flow component, to create a pressure drop in the flow of filled thermoplastic polymer and converge the flow of filled thermoplastic polymer at the mouth of the sheet die 800 4392 to convert the flow of the thermoplastic polymer from a screw cap-like flow to a substantially oriented longitudinal flow with a reduced axial-rotational flow component, in which flow the filler present is directed substantially in the extrusion direction. The method according to claim 1 or 2, characterized in that the highly polished surface "consists of a pressure-rolling system, which at least consists of an upper roller and a lower roller, which define a gap and the laminar melt flow continuous sheet by a.transmitting the laminar melt flow on the lower roll to a nib located downstream of the gap, b.adjusting the extrusion rate and the speed of the rollers so that upstream, but in the immediate In the vicinity of the gap, a melting reservoir of filled thermoplastic roll polymer is formed and c. the thermoplastic polymer is continuously fed to the melting tank and the filled thermoplastic polymer from the melting tank passes through the pressure roller system, producing a permanent continuous sheet material. Method according to claim 1 or 2, characterized in that the filler consists of glass fibers. 6. Process according to claim 1 or 2, characterized in that the continuous laminar melt flow is contacted with the hot, highly polished surface at a temperature and pressure sufficient to produce a surface after contact with the surface. continuous sheet with a gloss number of at least 15 and a maximum roughness of 150 microinches. 7. Process according to claim 1 or 2, characterized in that the continuous laminar melt flow is brought into contact with the hot, highly polished surface at a temperature and pressure sufficient to produce after contact with the surface. a continuous sheet with a gloss number of 30 and a maximum roughness of 100 microinches. A method according to claim 1 or 2, characterized in that the thermoplastic polymer is a crystalline thermoplastic polymer, namely a polyolefin, polyphenylene oxide polymer, polyoxymethylene homopolymer or copolymer, polyamide, polyester, a mixture thereof or a mixture thereof with minor amounts of other thermoplastic polymers. Method according to claim 8, characterized in that the thermoplastic polymer additionally contains a flame retardant amount of flame retardant. 10. A process according to claim 1 or 2, characterized in that the thermoplastic polymer hexamethylene adipamide, polyoxymethylene polymer or copolymer, polyalkylene terephthalate polymer or copolymer, a mixture of polyalkylene and terephthalate polymer and copolymer or a mixture of polyalkylene terephthalate polymer with small amounts of other thermoplastic polymer. Method according to claim 10, characterized in that the thermoplastic polymer additionally contains a flame-retardant amount of flame-retardant. 12. A method of manufacturing a filled, extruded, continuous thermoplastic sheet material with improved surface appearance, gloss and melt strength, which material comprises a crystalline thermoplastic polymer, which contains 5-60% by weight of filler and consists of polyolefin , polyphenylene oxide polymer, polyoxymethylene polymer or copolymer, polyamide, polyester, a mixture thereof or a mixture thereof with small amounts of other thermoplastic polymer, characterized in that a. filled crystalline thermoplastic polymer is successively extruded into a continuous laminar melt flow , b. transfers this laminar melt flow to a hot, highly polished surface, and c. contacting the laminar melt flow with the hot highly polished surface at a temperature of 93 ° C to the temperature at which the thermoplastic polymer becomes adhered to the hot highly polished surface and at a pressure to retract the filler of surface 800 43 92 of the laminar melt flow and is sufficient to produce a continuously filled crystalline thermoplastic sheet with a smooth, glossy, polymer-rich surface. 13. Process according to claim 12, characterized in that the filled crystalline thermoplastic polymer is extruded into the laminar melt flow by forming a melt flow of the filled crystalline thermoplastic polymer, this melt flow is directed to a sheet die under such conditions. and supplies that the flow of the melt flow and the filler material contained therein are oriented substantially in the extrusion direction and extrude this flow through the sheet die to the continuous laminar melt flow. 1¾. Process according to claim 13, characterized in that the filled, crystalline thermoplastic polymer 15 is directed with such a directed flow to such a sheet die and fed by forming a molten stream of filled crystalline thermoplastic polymer with a flow component in the extrusion direction and an axial, rotational flow component, to create a pressure drop in the flow of filled thermoplastic polymer and to converge the flow of filled crystalline thermoplastic polymer at the mouth of the sheet die to flow the filled thermoplastic polymer of the screw cap-like flow. in a substantially oriented longitudinal flow with a reduced axial-rotational flow component, the filler contained therein being oriented in the extrusion direction. Method according to claim 12 or 13, characterized in that the highly polished surface consists of a pressure-rolling system, comprising at least one upper roller and a lower roller 30, which define a gap between them and the laminar melt flow until continuous sheet by successively a. placing the laminar melt flow at a point upstream of the slit on the bottom roll, b. adjust the extrusion rate and the speed of the rollers such that a melting reservoir of filled 800 43 92 crystalline thermoplastic polymer is created upstream, but in the immediate vicinity of the gap, and c. the filled crystalline thermoplastic polymer continuously passes into the melting reservoir and filled crystalline thermoplastic polymer from the melting reservoir passes through the pressure-rolling system to produce a final, continuous sheet material. Method according to claim 12 or 13, characterized in that the filler consists of glass fibers. Process according to claim 12 or 13, characterized in that the continuous laminar melt flow is brought into contact with the hot, highly polished surface at a temperature and pressure sufficient to form a surface after contact with the surface. continuous sheet with a gloss number of at least 15 and a maximum roughness of 150 microinches. 18. Process according to claim 12 or 13, characterized in that the continuous, laminar melt flow is brought into contact with the hot, highly polished surface at a temperature and pressure sufficient to form after contact with the surface. a continuous sheet with a gloss number of 30 and a maximum roughness of 100 microinches. Method according to claim 12 or 13. characterized in that the filled crystalline thermoplastic polymer hexamethylene adipamide, polyoxymethylene polymer or copolymer, polyalkylene terephthalate polymer or copolymer, a mixture of polyalkylene terephthalate polymer or copolymer or a mixture of polyalkylene terephthalate polymer with minor amounts of other thermoplastic polymer. 20. A method according to claim 19, characterized in that the thermoplastic polymer additionally contains a flame retardant amount of flame retardant. 21. A method of manufacturing a continuous sheet material of glass-filled, extruded polyalkylene terephthalate with improved surface smoothness, melt strength and gloss, which sheet consists of a polyalkylene terephthalate polymer, 800 4 3 92 containing 5-60% by weight glass fibers, while the polymer is polyalkylene terephthalate homopolymer, copolymer a mixture thereof or a mixture thereof with minor amounts of other thermoplastic polymer, characterized in that a molten stream of filled polyalkylene terephthalate polymer is successively fed to a sheet die under such conditions. that the flow of the polymer and the glass fibers contained therein are oriented substantially in the extrusion direction, b. extruding the flow of filled polyalkylene terephthalate polymer into the sheet die into a continuous, oriented laminar melt flow, c. transfers the laminar melt flow to a hot, highly polished surface and d. contacting the laminar melt flow with the hot highly polished surface at a temperature of 93 ° C to the temperature at which the polyalkylene terephthalate polymer becomes adhered to the hot highly polished surface and at a pressure to retract the glass fibers from the surface of the laminar melt flow and to produce a continuous, filled, polyalkylene terephthalate sheet having a smooth, glossy, polymer-rich face surface. A process according to claim 21, characterized in that the filled polyalkylene terephthalate polymer is directed to the sheet die in a substantially oriented flow and fed by forming a molten flow of filled polyalkylene terephthalate nolymers with a flow component in the extrusion direction and an axial-rotational flow component, to create a pressure drop in the flow of filled polyalkylene terephthalate polymer and to converge the flow of filled polyalkylene terephthalate at the mouth of the velma-30 to convert the flow of the filled polymer from a screw cap-like flow into a substantially oriented longitudinal flow with a reduced axial-rotational flow component, the glass fibers present being oriented substantially in the extrusion direction, Method according to claim 21 or 22, characterized by 800 43 92, characterized in that the hot, highly polished surface consists of a pressure roller system, comprising at least one upper counterfeit and one lower counterfeit, defining a gap between them and the laminar melt flow to the continuous sheet by 5 a. transferring the laminar melt flow at one point upstream from the soleet to cb bottom false, b. adjust the extrusion rate and the rate of the traps so that a melt reservoir of filled polyalkylene terephthalate polymer is created upstream and in the immediate vicinity of the gap, and c. continuously feeding the filled polyalkylene terephthalate into the melting reservoir and passing the filled polymer from the melting reservoir through the pressure drop system producing a final, continuous sheet. 15 2b. Method according to claim 21 or 22, characterized in that the continuous laminar melt flow is brought into contact with the hot, highly polished surface, at a temperature and pressure, which for producing after contact with the surface of a continuous sheet material with a gloss number of at least 15 and 20 a maximum roughness of 150 microinches are sufficient. 25. Process according to claim 21 or 22, characterized in that the continuous laminar melt flow is brought into contact with the hot, highly polished surface at a temperature and pressure, which produces a continuous sheet after contact with the surface. with a gloss number of 30 and a maximum roughness of 100 microinches are sufficient. 26. Method according to claim 21 or 22, characterized in that the polyalkylene terephthalate polymer is polyethylene terephthalate, poly (1, H-butylene terephthalate), a mixture of polyethylene terephthalate and poly (1, U-butylene terephthalate) or a mixture thereof with other amounts of other thermoplastic polymer. 27. A method according to claim 26, characterized in that the polyalkylene terephthalate polymer is poly (1, Η-butylene terephthalate). 800 4 3 92 * * 33 A method according to claim 26, characterized in that the polyalkylene terephthalate is a brominated poly (1,1H-butylene terephthalate) polymer. 29. Process according to claim 21 or 22, characterized in that the filled polybutylene terephthalate is a low melt strength homopolymer of poly (1, U-butylene terephthalate) with an intrinsic viscosity of 0.65-0.75 dl. / g, which contains 20-5 wt.% glass fibers and further contains a flame retardant amount of flame retardant. 30. Extruded, filled, thermoplastic continuous sheet, characterized in that it consists of a thermonlastic polymer containing 5-6% reinforcing filler and a polymer-rich backplane, a gloss number of at least 15 and a maximum surface roughness of 150 microinches . Sheet material according to claim 30, characterized in that the filler of the sheet is substantially oriented. Sheet material according to claim 30 or 31, characterized in that the filler consists of glass fibers. 33. Sheet material according to claim 30 or 31, characterized in that it has a gloss number of at least 30 and a maximum surface roughness of 100 microinches. 34. Sheet material according to claim 30 or 31, characterized in that the thermoplastic polymer is a crystalline thermoplastic polymer, namely a polyolefin, polyoxymethylene homopolymer or copolymer, polyphenylene oxide polymer, polyamide, polyester, a mixture thereof or a mixture thereof with minor amounts other thermoplastic polymer. 35. Sheet material according to claim 3, characterized in that the thermoplastic polymer further contains a flame retardant amount of flame retardant. Sheet material according to claim 30 or 31, characterized in that the thermoplastic polymer consists of hexamethylene adipamide, a polyoxymethylene polymer or copolymer, polyalkylene terephthalate polymer or copolymer, a mixture of polyalkylene terephthalate polymer or copolymer or a mixture of 800 43 92 3 ** Polyalkylene terephthalate polymer with minor amounts of other thermoplastic polymers. 37. Sheet material according to claim 36, characterized in that the thermoplastic polymer further contains a flame retardant amount of flame retardant. 38. Extruded continuous sheet of glass-filled polyalkylene terephthalate, characterized in that it consists of a polyalkylene terephthalate polymer, a mixture of polyalkylene terephthalate polymers or a mixture of polyalkylene terephthalate polymers with minor amounts of other thermoplastic polymer, 5-60% by weight. glass fibers and a polymer-rich surface, has a gloss number of at least 15 and a maximum surface roughness of 150 microinches. 39. Sheet material according to claim 38, characterized in that it has a gloss number of at least 30 and a maximum surface roughness of 100 nicroinches. 1 * 0. Sheet material according to claim 38, characterized in that the polyalkylene terephthalate is polyethylene terephthalate, poly (1,1 * butylene terephthalate), a mixture of polyethylene terephthalate and poly (1,1 + butylene terephthalate) or a mixture thereof with minor amounts of other thermoplastic polymer is. 1 * 1. Sheet material according to claim 38, characterized in that the polyalkylene terephthalate polymer consists of poly (1,1 * butylene terephthalate), 25 * 2. Sheet material according to claim 38, characterized in that the polyalkylene terephthalate polymer consists of a brominated polybutylene terephthalate polymer. 1 * 3. Sheet material according to claim 38, characterized. that it consists of a homopolymer of poly (1,1 * -butylene-30 terephthalate) with low melt strength, an intrinsic viscosity of 0.65-0.75 dl / g and 20-1 * 5% by weight. glass fibers and a flame retardant amount of flame retardant. 1 * 1 *. Sheet material according to claim 1 * 3. characterized in that it further contains a drip-retarding amount of polytetra-fluoroethylene. 800 43 92 1 * 5 Sheet material according to claim 38, characterized in that the glass fibers in the sheet are oriented substantially parallel. 1 * 6. Device for use in the extrusion of thermoplastic sheet material, characterized by a. A screw extruder, b. a sheet die, c. means disposed between the extruder and the sheet die and the flow of thermoplastic polymer 10 at the mouth of the sheet die converge and convert a screw-thorn flow into a substantially oriented laminar flow with a reduced axial-rotational flow component and d. a heated, highly polished pressure roll system. 1 * 7. Apparatus according to claim 1 * 6, characterized in that the members consist of a breaker having a number of spaced apart ports extending through the inlet which slowly converge the flow of thermoplastic polymer passing through the plate and orient the filler contained therein. 1 * 8. Device according to claim 1 * 6, characterized in that the pressure roll system consists of a vertical stack of at least three rollers. 1 * 9. Ereek plate for use in the extrusion of a thermoplastic material containing a reinforcing filler, characterized by a rigid plate having a plurality of spaced ports extending through the plate and the flow of thermoplastic polymer which will slowly converge through the plate and orient the filler contained therein. 50, Ereekplaat as claimed in claim 1 * 9, characterized in that the gates consist of a funnel-shaped central gate with an internal volume converging to one side of the plate and a number of outer gates surrounding the central gate and have outputs that converge in the convergence direction of the central gate. * 51 * Rupture disc according to claim 50, characterized in that the central port has a larger volume than any of the outer ports. 800 4 3 92