JPH0430328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing filled sheets or films.

More specifically, a mixture of a thermoplastic resin and a filler or a preformed sheet made of a thermoplastic resin and a filler is introduced between a pair of circulating endless steel belts under tension, and the sheet is sandwiched between the steel belts. Production of a filler-containing sheet or film characterized in that the steel belt is brought into surface pressure contact with a heating roll and fused and integrated at a temperature higher than the melting point (or softening point) of the thermoplastic resin. It is about the method.

BACKGROUND OF THE INVENTION Conventionally, ordinary thermoplastic resin sheets or films made of polyethylene, polypropylene, etc. have been manufactured by methods such as inflation molding and T-die molding. These molding methods have the advantage of being able to mold homogeneous products at high speed using simple equipment, and are therefore widely adopted.

Additionally, fillers are added to thermoplastic resins to impart various properties.

However, in the above molding method, when a large amount of filler is blended, the flow characteristics such as melt fluidity deteriorate and the molding operation becomes difficult.

On the other hand, when adding special fillers such as fibrous fillers such as glass fibers and carbon fibers, or scaly fillers such as mica, equipment wear is significantly accelerated and maintenance of the extruder becomes costly. Not only is this expensive, but the melt shear force applied during extrusion can cause breakage of the filler, making it impossible to obtain the desired properties.

Moreover, the above-mentioned molding method cannot be applied to molding difficult-to-process resin itself such as ultra-high molecular weight polyethylene, polytetrafluoroethylene, or polyimide resin.

For example, although ultra-high molecular weight polyethylene has excellent impact resistance and abrasion resistance, it does not have good moldability, so its demand is minimal. Examples of methods for molding ultra-high molecular weight polyethylene include a sintering method, a ram extrusion method using a plunger pump, and a forging method. Further, press molding is mainly used for forming plate-shaped objects. However, the thickness is 1mm
It is very difficult to form the following thin sheets or films of ultra-high molecular weight polyethylene (hereinafter simply referred to as "sheets"), and the current method of forming thin sheets is to cut the plate-shaped body obtained by the above method. This is done by performing secondary processing, which not only results in extremely high molding costs, but also makes it difficult to mold continuously in large quantities.

This means that ultra-high molecular weight polyethylene has a very high melt viscosity and poor melt fluidity, so conventional molding methods such as the inflation method and T-die method, which have a large pressure loss, cannot be used. This is because it is not suitable for the molding method.

Furthermore, in the case of polytetrafluoroethylene, polyimide resin, etc., the difference between the molding temperature and the thermal decomposition temperature is small, so the above-mentioned general sheet molding method cannot be applied.

On the other hand, as a sheet forming method that has been known for a long time, there is a forming method using calender rolls. With this method, sheets with good thickness accuracy can be obtained at high speed, so it is widely used mainly for manufacturing polyvinyl chloride sheets or rubber sheets.
In the case of resins such as polyolefins, their melt strength is low, their elasticity is weak, and their melt viscosity is highly dependent on temperature, so the molding temperature range is narrow and molding operations are extremely difficult, so they are rarely put to practical use. has not been standardized.

In view of these circumstances, the present inventors conducted intensive research and as a result, came to invent the method of the present application.

SUMMARY OF THE INVENTION The first object of the present invention is to eliminate these drawbacks of the prior art and to provide a method for producing sheets or films made of customary thermoplastic resins with large amounts of filler. .

A second object of the present invention is to provide a method for manufacturing sheets or films containing fillers that are difficult to add.

Furthermore, a third object of the present invention is to provide a method for manufacturing a filled sheet or film using a difficult-to-process thermoplastic resin.

The method of the present invention introduces a thermoplastic resin/filler blend or a preformed sheet of thermoplastic resin/filler between a pair of tensioned circularly running endless belts, e.g. endless steel belts. The melting point (or softening point) of the thermoplastic resin is then adjusted while the steel belt is being pressed by the steel belt and the steel belt is in surface pressure contact with a heating roll.
The present invention relates to a method for manufacturing a filler-containing sheet or film, which is characterized by being fused and integrated at a temperature above.

The thermoplastic resin used in the method of the present invention is a thermoplastic resin that can be formed into a sheet by conventional extrusion molding, i.e., low, medium, high density polyethylene,
Polyolefin resins such as homopolymers such as polypropylene, polybutene-1, poly-4-methylpentene-1, and copolymers with other α-olefins containing ethylene or propylene as a main component, nylon-6, nylon -6,6, polyamide resins such as nylon-11 and nylon-12, saponified ethylene-vinyl acetate copolymers, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyester resins, polyacetal resins Although resins and mixtures thereof are included, thermoplastic resins that can more significantly exhibit the effects of the present invention are hard-to-process thermoplastic resins that are difficult to reduce in thickness by ordinary molding methods.

Difficult-to-process thermoplastic resins include ultra-high molecular weight polyethylene with an intrinsic viscosity of 8 or more in decalin solution at 135°C, fluorocarbon resins such as polytetrafluoroethylene, polycarbonate resins, polyimide resins, polyamideimide resins, and polyether ethers. Examples include ketone resin, polyether sulfone resin, polysulfone resin, polyphenylene oxide resin, polyphenylene ether resin, polyphenylene sulfide resin, and aromatic polyamide resin.

The filler used in the method of the present invention may be any organic or inorganic filler in the form of powder, plate, or scale, needle, sphere, hollow, fiber, or woven fabric. good.

Specific examples of the above organic or inorganic fillers include calcium carbonate, magnesium carbonate, calcium sulfate, calcium silicate, clay, diatomaceous earth, talc, alumina, silica sand, glass powder, iron oxide, metal powder, antimony trioxide, and graphite. , silicon carbide, silicon nitride, silica, boron nitride, aluminum nitride, wood powder, powdery fillers such as carbon black, mica, glass plates, sericite, pyrofluorite, metal foils such as aluminum flakes, flat plates such as graphite, etc. hollow fillers such as shirasu balloons, metal balloons, glass balloons, pumice, glass fibers, carbon fibers, graphite fibers, whiskers, metal fibers, silicon carbide fibers, asbestos, wollastonite, etc. Examples include fibrous fillers such as mineral fibers and organic fibers such as viscose, polyamide and vinylon, and fibrous fillers such as glass fiber mat and organic fiber mat.

In the method of the present invention, the thermoplastic resin and filler blend, or a preformed sheet of thermoplastic resin and filler, is placed between a pair of tensioned, circulating endless steel belts. The thermoplastic resin is fused and integrated by passing the steel belt through a plurality of heating rolls set at a predetermined temperature so as to be in surface pressure contact with the steel belt while being compressed by the steel belt. The material is then formed into a sheet or film, cooled as necessary through a group of cooling rolls provided after a group of heating rolls, and then wound into a product.

The molding temperature in the above method is a temperature higher than the melting point (or softening point) of the thermoplastic resin, and a temperature at which the thermoplastic resin does not thermally decompose, and is lower than the melting point (or softening point) of the thermoplastic resin. A temperature range of about 10 to 300°C higher is preferred.

In addition, the blending amount of the filler is determined by the thermoplastic resin.
The range of 5 to 1000 parts by weight per 100 parts by weight is preferred. If the amount of filler is less than 5 parts by weight, the effect of adding the filler will not be recognized, and if the amount of filler exceeds 1000 parts by weight, it will not satisfy the required physical properties of the filler-containing sheet. There are concerns that it will not be possible to do so.

One of the features of the present invention is that a pair of endless steel belts under tension are run along the roll surfaces of a group of heating rolls so as to be in surface pressure contact, and the thermoplastic resin sandwiched between the steel belts is formed into a sheet. That's true. This is useful for forming sheets with high filler content, which cannot be easily formed or made into thin sheets using normal forming methods, or sheets containing special fillers. It also brings about great effects in the molding of sheets made of hard-to-process resins mixed with fillers.

For example, if only ultra-high molecular weight polyethylene is introduced between two steel belts, the belt is sandwiched between heating rolls from both sides of the belt running flat, and linear pressure is simply applied to the steel belt. Since high molecular weight polyethylene has extremely poor melt flowability, horizontal cracks occur frequently and a satisfactory sheet cannot be obtained.
However, as in the present application, the belt is meandered along the roll surface to achieve surface pressure contact, and tension is applied to the belt to apply pressure to the pair of belts, and ultra-high molecular weight polyethylene and filler are applied between the belts. To continuously produce filler-containing sheets or films that are completely free of transverse cracks, tough, and have excellent abrasion resistance by sandwiching and fusing a compound or a preformed sheet thereof. becomes possible.

Preferably 2 to 5 heating rolls are installed in the method of the present invention, but it is not necessary that all the rolls be heated to the same temperature. Rather, by applying pressure using a tensioned belt, the air between the thermoplastic resin powders can be released easily in the first stage, and the formed sheet can be easily peeled off from the roll in the final stage. To achieve this, it is preferable to lower the temperature of the first and last rolls.

The physical properties of the sheet obtained by the method of the present invention are determined by the tension of the belt, that is, the pressure on the resin sandwiched between the belts, the running speed of the belt, the contact time of the belt with the heating roll surface, and the surface temperature of the roll. These molding conditions can be appropriately selected depending on the type of thermoplastic resin and filler, although they are greatly influenced by the following.

In particular, the belt tension and the contact time between the belt and the heating roll have a close relationship; when the belt tension is low, a long period of contact is required, and when the belt tension is high, a short period of contact is required. Upon contact, a strong and good sheet with no bubbles is obtained.

The tension of the above-mentioned belt varies depending on the type of resin, the blending ratio of fillers, molding conditions, etc., but for example, for difficult-to-process resins, the tension of the belt is 3 Kg/cm or more, preferably 10 Kg/cm or more when measured with a strain gauge. is desirable. If the tension is less than 3 kg/cm, not only will the molding speed be extremely slow, but there is also a concern that the mechanical properties of the molded sheet will deteriorate. On the other hand, it is desirable to have a high belt tension because it allows molding to be performed at a high speed and to obtain a strong sheet. The maximum tension must be appropriately selected depending on the strength of the belt, molding conditions, etc. Although the present invention describes an example of an endless steel belt, the material itself of the endless belt does not constitute the gist of the method of the present invention, and endless belts made of other materials, for example, suitable It is also possible to use a single metal belt, an endless belt coated with a resin such as fluororesin or silicone resin, or an endless belt made of resin such as Teflon.

The thermoplastic resin and filler may also be supplied in the method of the invention in the form of a powdered formulation or in the form of a preformed sheet. For example, when supplying powder, the powder is placed on the lower belt, flattened with a doctor knife, etc., and then passed between the heating rolls while being sandwiched between the upper belt and the powder. That's fine. On the other hand, when supplying a preformed sheet as a material, there is a method in which a mixture of thermoplastic resin and filler is preformed through a calender roll, etc., or a mixture obtained by heating the filler is supplied. There are methods such as supplying a sheet by pressing a plastic resin sheet into a sandwich shape, but these methods have the advantage of improving the thickness accuracy of the product sheet and stabilizing the material supply condition. desirable.

Below, the manufacturing method of the present invention will be explained in more detail based on the accompanying drawings.

1, 2, and 3 are explanatory diagrams of an apparatus for carrying out the method of the present invention, and FIG. 1 is a schematic longitudinal sectional view of an apparatus using two or three heating rolls. It is.

First, a sheet 2 obtained by preforming a thermoplastic resin and filler mixture 12 through a calender roll 1 is passed through a pair of endless steel belts 3.
Introduce between a and 3b. The endless steel belts 3a, 3b are stretched in opposite directions between feed rolls 4a, 4b and guide rolls 5a, 5b, and tension is applied to the endless steel belts 3a, 3b. is 3
In the case of a book, the sheet 8 is formed by circulating the steel belts 3a, 3b along the surfaces of 6c) indicated by the broken line and the cooling roll groups 7a, 7b while bringing them into surface pressure contact. A winding machine 10 winds up the product.

Although the arrangement of the heating roll groups 6a, 6b, and 6c is not particularly limited, they are arranged so as to most efficiently make surface contact with the steel belt and pressurize the belt.

FIG. 2 is a schematic perspective view of the apparatus when five heating rolls are used, and the preformed sheet 2 is rolled around the feed rolls 4a and 4b from the original fabric 11 on which the preformed sheet is wound. It is supplied between a pair of endless steel belts 3a and 3b.
The endless steel belts 3a, 3b are made of guide rolls 5a, 5b and tension rolls 9a, 9b.
As a result, similar to the device shown in FIG. 1, tension is applied by being pulled in opposite directions.

The steel belts 3a, 3b are run and circulated while being in surface contact with heating roll groups 6a, 6b, 6c, 6d, 6e and cooling roll groups 7a, 7b,
After forming the sheet 8, it is wound up by a winding machine 10 to form a product.

In addition, in the apparatus shown in FIG. 3, four heating rolls are used to directly form a sheet from a mixture of thermoplastic resin and filler.

In this device, feed rolls 4a, 4
The endless steel belts 3 are placed in parallel to each other, and are placed under tension as they circulate at a constant speed.
The compound 12 is supplied between the feed rolls 4a, 4b and the steel belts 3a, 3b, and the steel belt is welded to the heating roll groups 6a, 6b, 6c, 6d by surface pressure. The steel belts 3a and 3b are made to run in a meandering manner, and after heating the front and back sides of the steel belts 3a and 3b alternately, they are cooled by cooling rolls 7a and 7b. The formed sheet 8 thus obtained is wound into a product by a winder 10. The thickness of the molded sheet 8 can be arbitrarily adjusted by increasing or decreasing the gap between the feed rolls 4a and 4b.

The imparting of functionality to the filler-containing sheet and the improvement of properties such as mechanical strength and electrical properties by the method of the present invention vary depending on the type and amount of the resin and filler, but It can be selected as appropriate according to the physical properties required for the product, purpose of use, usage, etc.

For example, sheets made from a combination of ultra-high molecular weight polyethylene and metal fibers with poor extrusion properties, carbon fibers, or carbon blacks with large aspect ratios such as ketchen blacks are extremely strong and highly conductive sheets that have never existed before. becomes.

Furthermore, a combination of ultra-high molecular weight polyethylene and metal powder such as iron oxide provides a strong electromagnetic shielding sheet, and a sheet obtained by combining the above resin and graphite provides a lubricating sheet.

Examples showing the relationship between general functional properties and fillers are listed below, but the present invention is not limited thereto.

Improved physical properties: steel powder, aluminum oxide, calcium carbonate, calcium sulfate, silica, silicon carbide, etc. Thermal conductivity and electrical conductivity: metal powders such as copper powder, iron powder, silver powder, steel powder, aluminum powder, carbon black, metal fibers , carbon fiber, etc. Electromagnetic shielding properties: Metal powders such as iron oxide, copper powder, and iron powder, metal fibers, aluminum flakes, etc. Wear resistance: graphite, molybdenum disulfide, etc. Flame retardance: Antimony oxide, etc. Weather resistance: Carbon black In addition to the above, various fillers can be used depending on the purpose and application, such as magnetization (iron powder, nickel, alloy powder, etc.), light scattering properties (glass beads, etc.), and weight reduction (shirasu balloons, etc.). Can be used.

In the present invention, without departing from the gist thereof, synthetic rubbers such as ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM), and styrene-butadiene rubber (SBR),
Mixing different materials such as natural rubber, petroleum resin, and unsaturated carboxylic acid-modified polyolefin, or adding additives such as pigments, ultraviolet inhibitors, antioxidants, plasticizers, coupling agents such as silanes, and titanates as appropriate. No problem.

As mentioned above, according to the method of the present invention, it is of course possible to mold a sheet made of a normal thermoplastic resin and a filler, and it has the following remarkable advantages compared to conventional sheet molding methods. It can be said that it is effective.

(1) It is possible to mix a higher percentage of filler than conventional molding methods, (2) Even special fillers that are difficult to mix with conventional molding methods can be mixed and molded without impairing their functions. (3) Not only is it possible to mold sheets containing fillers made of difficult-to-process resins that cannot be molded using conventional molding methods, but the blending range is wide, and even special fillers can be filled at any blending ratio. It has many advantages, such as being able to form sheets containing material.

In addition, the filler-containing sheet obtained by the method of the present application can be given functions and properties such as electrical insulation materials and electromagnetic shielding materials as described above, and can be used in electrical and electronic fields such as materials for flexible printed circuits. ,
It can be used in many fields such as architecture and civil engineering.

The present invention will be further explained below with reference to Examples.

Example 1 Using the apparatus shown in FIG. 3, the tension of steel belts 3a and 3b was set to 14 kg/cm, and
The surface temperature of rollers 6d and 6d was set to 180°C, and the surface temperature of cooling rolls 7a and 7b was set to 15°C. 30% by weight of glass fibers of 6 mm length were added to polyethylene (product name: Hostalen GUR412, manufactured by Hoechst, intrinsic viscosity: 15 in decalin at 135°C) and mixed with an omni mixer, and the surface temperature was raised to 130°C. ℃ feed between the feed rolls 4a and 4b, and adjusting the gap between the feed rolls, the running speed is 30°C.
A sheet with a thickness of 0.5 mm was formed at cm/min.

The flexural modulus of this sheet was 53000 Kg/cm ² . Further, almost no damage to the glass fibers was observed.

Example 2 Sheet molding was carried out in the same manner as in Example 1 using a mixture of the same resin as in Example 1 and 25% by weight of Ketsuen Black EC (manufactured by Ketsuien Co., Ltd.) by stirring with a Henschel mixer. , a film with a thickness of 0.2 mm was obtained.

The surface resistivity of the obtained film was 10 ⁴ Ω.

Example 3 Aluminum fibers (3 mm×
60 μφ) was blended in an amount of 30% by weight, stirred and mixed with an omni mixer, and then prepared in the same manner as in Example 1 to a thickness of 0.5
A sheet of mm was obtained.

The volume resistivity of this sheet was 0.06 Ωcm, and the aluminum fibers were hardly broken.

Example 4 Ultra-high molecular weight polyethylene
1900, manufactured by Hercules, 135°C, intrinsic viscosity in decalin: 19) was mixed with 40% by weight of mica, stirred and mixed with a Henschel mixer, and then molded into a sheet with a thickness of 0.5 mm according to Example 1. did. The flexural modulus of the obtained sheet was 52000 Kg/cm ² .

Example 5 Ultra high molecular weight polyethylene (product name: HIFAX
A porous sheet with a thickness of 0.3 mm was preformed.

Long fiber glass wool was sandwiched between the two porous sheets thus obtained, and using the apparatus shown in Figure 2, the tension of the Teflon-coated steel belts 3a and 3b was set to 34 kg/cm, and a feed roll was applied. The surface temperature of the heating rolls 6a to 6e is 185°C, the cooling roll 7a,
Set 7b to 15℃ and measure the thickness at a running speed of 30cm/min.
A 0.8 mm sheet was molded.

The glass fiber content of the obtained sheet is 50% by weight
The flexural modulus was 76000Kg/cm ² .

Example 6 6-Nylon powder (Product name: Ubenylon
1030QB, 150 meters passed, manufactured by Ube Industries),
A mixture obtained by mixing 40% by weight of aluminum fibers (3 mm x 90 μφ) with stirring using an omnimixer was molded using the apparatus shown in FIG. Teflon coated steel belts 3a, 3b
In the same manner as in Example 1, the tension was 10 Kg/cm, the surface temperature of feed rolls 4a and 4b was 240°C, the surface temperature of heating rolls 6a to 6d was 260°C, and the surface temperature of cooling rolls 7a and 7b was 20°C. Thickness 0.5mm
I got a sheet of The volume resistivity of the obtained sheet was 0.09Ω.cm.

[Brief explanation of drawings]

1, 2, and 3 are explanatory diagrams of an apparatus for carrying out the method of the present invention, and FIG. 1 is a schematic longitudinal sectional view of an apparatus having two or three heating rolls. 2 is a schematic perspective view of an apparatus having five heating rolls, and FIG. 3 is a schematic longitudinal sectional view of an apparatus for forming thermoplastic resin powder into a sheet. 1...Calender roll, 2...Preformed sheet, 3a, 3b...Endless steel belt,
4a, 4b...Feed roll, 6a, 6b, 6
c, 6d, 6e... heating roll, 7a, 7b...
Cooling roll, 8... Formed sheet, 9a, 9b...
Tension roll, 10... Winder, 11... Original sheet, 12... Thermoplastic resin filler compound.

Claims (1)

[Claims] 1. Introducing a mixture of a difficult-to-process thermoplastic resin and a filler or a preformed sheet made of a difficult-to-process thermoplastic resin and a filler between a pair of circulating endless steel belts, Tension is applied to the belt, the belt is compressed and meandered so as to be in surface pressure contact with a plurality of roll groups, the temperature of the first roll and the last roll is lower than that of the heating roll group, and the belt is compressed by the heating roll group. 1. A method for producing a filler-containing sheet or film, which comprises fusion-bonding and integrating at a temperature higher than the melting point (or softening point) of a thermoplastic resin. 2. The thermoplastic resin is a polyethylene resin having an intrinsic viscosity of 8 or more in a 135°C decalin solution,
Fluorine resin, polycarbonate resin, polyimide resin, polyamideimide resin, polyether ether ketone resin, polyether sulfone resin, polysulfone resin, polyphenylene oxide resin, polyphenylene ether resin, polyphenylene sulfide resin, aroma The method for manufacturing a filler-containing sheet or film according to claim 1, wherein the filler compound sheet or film is any resin selected from the group consisting of group polyamide resins and polyester resins. 3. The filler according to claim 1 or 2, wherein the filler is at least one selected from the group of fibrous, plate-like, scale-like, needle-like, and hollow fillers. A method for producing filler-containing sheets or films. 4. The filler-containing sheet or film according to any one of claims 1 to 3, wherein the filler is blended in an amount of 5 to 1000 parts by weight based on 100 parts by weight of the thermoplastic resin. Production method.