US20070235893A1

US20070235893A1 - Method for producing resin strand

Info

Publication number: US20070235893A1
Application number: US11/727,141
Authority: US
Inventors: Takaaki Miyoshi
Original assignee: Individual
Current assignee: Asahi Kasei Chemicals Corp
Priority date: 2006-03-24
Filing date: 2007-03-23
Publication date: 2007-10-11
Also published as: JP2007253500A

Abstract

The present invention can eliminate a breakage of strands on the way to increase yield, significantly suppress formation of adhered consecutive pellets, and obtain pellets having a low moisture content by a method for producing a resin strand comprising melt-kneading a resin composition in an extruder, extruding a strand-shaped molten resin onto a conveyor, and cooling the resin strand with cooling water, wherein the conveyed strand-shaped molten resin is brought into initial contact with the cooling water at a position downstream ranging from 20% to 70% of the total length of the conveying part of the conveyor.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a method for producing a strand in which, when the strand is cooled on a conveyor, a breakage of the strand can be suppressed to significantly improve the yield of pellets, to a strand obtained by the production method, and to pellets obtained by cutting the strand. The present invention further relates to a method for producing a resin strand for uniforming melt viscosity of a resin strand, improving strand draw-off stability, and obtaining a thermoplastic resin composition consistently excellent in impact resistance by stably feeding one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof, and to a preblend that can be stably fed.
2. Description of the Related Art
An example of processing equipment widely used for the production of thermoplastic resin pellets is an extruder. Examples of the methods for obtaining resin pellets using an extruder include strand cutting comprising the steps of melting a resin in an extruder, extruding the molten resin from capillary-shaped die holes to form strands, cooling and solidifying the strands, and cutting the solidified strands with a strand cutter; hot cutting comprising the steps of rotating a single knife or multiple knives at high-speed in the die hole part, cutting a molten resin discharged from the die holes to a small size while the resin is in a molten state, and cooling the cut resin in a water bath to form pellets; and underwater cutting comprising the step of cutting a molten resin discharged from the die holes in water to a small size.
Among others, strand cutting is relatively often used (JP-A-10-180754). In the strand cutting, a method of cooling a strand-shaped molten resin includes a method of cooling by directly immersing the strand-shaped molten resin in a water bath and a method of conveying the strand-shaped molten resin on a conveyor and cooling it on the way by spraying water.
In the latter case, a phenomenon of a partial narrowing of strands is liable to occur because the strand-shaped molten resin cannot be cooled uniformly. As a result, there has been a problem that strand are broken between the conveyor and strand cutter. This phenomenon is often observed, particularly in the case where a crystalline resin is used. Moreover, there has been a further problem that formation of pellets referred to as adhered consecutive pellets (pellets in which two or more pellets are adhered) is liable to occur by contact of the strand-shaped molten resins with each other. In a case of polymer alloy comprising polyamide and polyphenylene ether, the use of a compatibilizer such as maleic acid, citric acid, fumaric acid, and an anhydride thereof is known to be useful. It is necessary to feed these compatibilizers stably in order to make the compatibilizers useful. Unstable feed of compatibilizers causes a periodic variation of the strand diameter which is called surging, resulting in a problem of making the resin strand unstable.

SUMMARY OF THE INVENTION

The present invention intends to solve the subject of preventing a breakage of strands and significantly suppressing formation of adhered consecutive pellets by optimizing the method of cooling strands. Furthermore, the present invention intends, in polymer alloys, to improve the stability of resin strands by optimizing the method of adding a compatibilizer.
As a result of intensive study, the present inventors have found that the above described subject can be solved by performing a specific cooling method using a conveyor and achieved the present invention. Further, the present inventors have found that, in a polymer alloy comprising polyamide, polyphenylene ether, and a compatibilizer selected from maleic acid, citric acid, fumaric acid, and an anhydride thereof, stable extrusion without surging or the like can be achieved by previously mixing the compatibilizer with part of the polyphenylene ether and that the resulting resin composition has improved impact strength and flowability, and have achieved the present invention.
Thus, the constitution of the present invention is as follows:
1. A method for producing a resin strand comprising the steps of:
melt-kneading a resin composition in an extruder;
extruding a strand-shaped molten resin onto a conveyor; and
cooling the resin strand with cooling water;
wherein the conveyed strand-shaped molten resin is brought into initial contact with the cooling water at a position downstream ranging from 20% to 70% of the total length of the conveying part of the conveyor.
2. The method for producing a resin strand according to the above 1, wherein the cooling water is sprayed water.
3. The method for producing a resin strand according to the above 1, wherein the cooling water has a temperature of 5° C. or above and 50° C. or below.
4. The method for producing a resin strand according to the above 1, wherein the length from the position at which the conveyed strand-shaped molten resin is brought into initial contact with the cooling water to an extruder die hole is 1.5 m or more and 4.5 m or less.
5. The method for producing a resin strand according to the above 1, wherein a discharge per unit area of the opening of an extruder die hole is from 80 kg/cm²to 200 kg/cm².
6. The method for producing a resin strand according to the above 1, wherein the strand just before cutting has a temperature ranging from 100° C. to 150° C.
7. A pellet obtained by cutting a strand produced by the method according to the above 1.
8. The pellet according to the above 7, wherein the percentage of adhered consecutive pellets is less than 2% by mass of the total pellet.
9. The method for producing a resin strand according to the above 1, wherein the resin composition comprises one or more resins selected from the group of polyarylene sulfide, polyetheretherketone, polysulfone, polyethersulfone, polyamide, polyester, liquid crystal polymers, polyarylate, polycarbonate, polyphenylene ether, and polyetherimide.
10. The method for producing a resin strand according to the above 1, wherein the resin composition is a mixture comprising two or more resins selected from the group of polyarylene sulfide, polyetheretherketone, polyamide, polyester, liquid crystal polymers, polyphenylene ether, and polyetherimide, the mixture comprising both a crystalline resin and an amorphous resin; and the crystalline resin forming a continuous phase and the amorphous resin forming a disperse phase.
11. The method for producing a resin strand according to the above 10, wherein the resin composition comprises at least polyamide and polyphenylene ether.
12. The method for producing a resin strand according to the above 11, wherein the resin composition comprises polyamide, polyphenylene ether, and one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form.
13. The method for producing a resin strand according to the above 12, wherein the polyphenylene ether is a powdery polyphenylene ether comprising 60% by mass or more of fine particles not passing a 145 mesh (106 μm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 65 μm.
14. The method for producing a resin strand according to the above 12, wherein the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form comprise 80% by mass or more of particles passing a 6 mesh (3.1 mm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 1.4 mm.
15. The method for producing a resin strand according to the above 12, comprising the steps of:
forming a preblend of 100 parts by mass of a powdery polyphenylene ether and 50 to 200 parts by mass of one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form; and then
feeding the preblend to an extruder through a feeder different from a feeder used for the feeding remaining polyphenylene ether.
16. The method for producing a resin strand according to the above 15, wherein the amount of the powdery polyphenylene ether incorporated into the preblend is less than 5% by mass of the amount of all the polyphenylene ether used in the resin composition.
17. The method for producing a resin strand according to the above 12, wherein the amount of the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form is from 0.01 to 1 part by mass based on 100 parts by mass of all the polyphenylene ether.
18. The method for producing a resin strand according to the above 15, further comprising a peroxide in the preblend.
19. The method for producing a resin strand according to the above 1, wherein the resin composition comprises 5 to 50% by mass of an inorganic filler based on 100% by mass of the resin composition.
20. The method for producing a resin strand according to the above 19, wherein the inorganic filler is one or more selected from the group of glass fiber, glass flake, talc, wollastonite, mica, titanium dioxide, alumina, silica, zinc oxide, and zinc sulfide.
21. The method for producing a resin strand according to the above 1, further comprising an electrically conductive carbon filler.
22. The method for producing a resin strand according to the above 21, wherein the electrically conductive carbon filler is at least one selected from electrically conductive carbon black, carbon fibril, and graphite.
23. A preblend comprising 100 parts by mass of a powdery polyphenylene ether and 50-200 parts by mass of one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form.
24. The preblend according to the above 23, wherein the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form are powdery or granular compounds comprising 80% by mass or more of particles passing a 6 mesh (3.1 mm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 1.4 mm.
25. The preblend according to the above 23, wherein the powdery polyphenylene ether is a powdery polyphenylene ether comprising 80% by mass or more of fine particles not passing a 145 mesh (106 μm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 65 μm.
The use of the production method of the present invention not only eliminates a breakage of strands during production to increase the yield, but also significantly suppresses formation of adhered consecutive pellets to improve product quality and enables the moisture content of pellets to be significantly suppressed. In addition, it makes the extrusion stable and thereby reduces surging and the like to improve the properties of the resulting resin composition.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates the positional relationship between the position at which a strand-shaped molten resin conveyed on a conveyor is brought into initial contact with sprayed water and extruder die holes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As described above, the present invention relates to a method for producing a resin strand comprising the steps of: melt-kneading a resin composition in an extruder; extruding a strand-shaped molten resin onto a conveyor; and cooling the resin strand with cooling water; the conveyed strand-shaped molten resin being brought into initial contact with the cooling water at a position downstream ranging from 20% to 70% of the total length of the conveying part of the conveyor.
The most important one among the effects of the present invention is the step of bringing a conveyed strand-shaped molten resin into initial contact with cooling water at a position downstream ranging from 20% to 70% of the total length of the conveying part of a conveyor.
As described in the present invention, the term “the total length of the conveying part of a conveyor” means the length across the ends of the movable conveying part of a conveyor. When the total length of the conveying part of a conveyor is defined as 100%, the end on the side close to extruder die holes is at a position of 0% and the end on the side far from the extruder die holes is at a position of 100%.
The total length of the conveying part of a conveyor depends upon the capacity of the extruder to be used, and is preferably 1 m or more from the viewpoint of cooling a resin strand to a desired temperature and 8 m or less from the viewpoint of the space required for workability and production.
Moreover, as described in the present invention, the term “the position at which a strand-shaped molten resin is brought into initial contact with cooling water” means a position at which cooling water is brought into direct contact with the strand-shaped molten resin in the process of conveying on a conveyor the strand-shaped molten resin discharged from extruder die holes.
FIG. 1 illustrates the positional relationship between the total length of the conveying part of a conveyor, the position at which a strand-shaped molten resin conveyed on the conveyor is brought into initial contact with cooling water, and the extruder.
A number of commercially available conveyors are equipped with cooling water holes only at a position downstream ranging from 0 to 20% of the total length of the conveying part of the conveyor. Although some conveyors have a number of cooling water holes, a method of cooling a strand-shaped resin discharged from die holes as early as possible is generally adopted from the viewpoint of suppressing thermal degradation of resin.
The concept of the present invention is totally contrary to the above method and involves the step of cooling the strand-shaped resin at a position downstream ranging from 20% to 70% of the total length of the conveying part of the conveyor, that is, retarding the cooling of the strand discharged from die holes.
In the present invention, the strand-shaped molten resin conveyed on a conveyor is brought into initial contact with the cooling water more preferably at a position downstream ranging from 30% to 60%, further preferably at a position downstream ranging from 40% to 60%, of the total length of the conveying part of the conveyor.
When the position at which the strand-shaped molten resin is brought into initial contact with cooling water is less than 20% or more than 70% of the total length of the conveying part of the conveyor, a frequent breakage of strands occurs to significantly lower the productivity (pellet yield). Specifically, since a strand breaks, for example, between a conveyor and a strand cutter, there is a problem that the strand cannot be subjected to strand-cutting, resulting in significant reduction in productivity.
The length from the position at which the conveyed strand-shaped molten resin is brought into initial contact with the cooling water to the extruder die holes is preferably 1.5 m or more and 4.5 m or less, more preferably 1.5 m or more and 4 m or less, further preferably 2 m or more and 4 m or less, most preferably 2.5 m or more and 4 m or less.
Factors are not necessarily clear which enable a breakage of strands to be eliminated when the position at which the strand-shaped molten resin is brought into initial contact with cooling water is set within the range of the present invention. One of the factors is probably that the molecular orientation of the strand-shaped molten resin is relaxed while the strand-shaped molten resin discharged from the die holes is conveyed by the conveyor and reaches a specific length and then the resin is cooled, thereby allowing uniform cooling of the resin.
In the present invention, the cooling water for cooling the strand-shaped molten resin is more preferably sprayed water. It is possible to cool the strand more uniformly by spraying water.
Moreover, setting the position at which the strand-shaped molten resin is brought into initial contact with cooling water within the range of the present invention is also effective for suppressing formation of adhered consecutive pellets which are formed by the adhesion of strands in a molten state with each other. The percentage of the adhered consecutive pellets in the pellets obtained by cutting strands is preferably less than 2% by mass, more preferably less than 1% by mass, based on 100% by mass of the total pellets. This can be measured by accurately weighing about 100 g of pellets, accurately weighing the weight of adhered consecutive pellets present in the accurately-weighted pellets, and calculating the result as the percentage by mass. This measurement is preferably performed for at least five random samples or more from different production time periods.
The strand obtained by the production method of the present invention preferably has a diameter ranging from 2 mm to 4 mm. In order to obtain a strand which hardly breaks, the diameter is preferably controlled within this range. More preferably, the strand has a diameter ranging from 2.5 mm to 3.5 mm. Further, it is preferred that the pellets obtained by cutting the strand have a cross section having a diameter of from 2 to 4 mm. Similarly, it is preferred that the pellets have a length ranging from 2 to 4 mm.
Examples of the method for controlling the diameter of the strand include a method of controlling the conveying speed of a conveyor, a method of controlling the diameter of extruder die holes, and the like. Any of these methods may be used.
As a measure for controlling extruder die holes, it is preferred that the die holes have a diameter of 3.5 to 5.5 mm. Further, as a preferred range of the extrusion rate at this time, the discharge per unit area of the opening of the die holes is preferably from 80 kg/cm²to 200 kg/cm², more preferably from 100 kg/cm²to 200 kg/cm², most preferably from 100 kg/cm²to 170 kg/cm². The discharge per unit area of the opening of the die holes in this case is a value calculated by the following expression:
Qd=Qe/(Rd ² ×π×Nd)
wherein Qd represents a discharge per unit area (kg/cm²) of the opening of die holes; Qe represents the total discharge (kg) of the extruder per one hour; Rd represents the radius (cm) of the die holes; Nd represents the number of the die holes; and π represents the ratio of the circumference of a circle to its diameter.
Moreover, in the present invention, the temperature of the strand immediately before cutting is preferably controlled from 100° C. to 150° C. in order to suppress generation of chips and reduce moisture content of the resulting pellets. More preferably, the temperature is controlled from 120° C. to 140° C. Specific examples of the method of controlling the strand temperature include a method of controlling the frequency of water spray, a method of controlling the volume of spray, and the like.
Moreover, in order to keep the strand temperature immediately before cutting below 150° C., the cooling water preferably has a temperature of 5° C. or above and 50° C. or below. If cooling water having a temperature exceeding 50° C. is used, the resin strand will not be cooled sufficiently, causing discoloration of the strands and pellets.
The resin composition used for the method for producing resin strands according to the present invention comprises one or more resins selected from the group of polyarylene sulfide, polyetheretherketone, polysulfone, polyethersulfone, polyamide, polyester, liquid crystal polymers, polyarylate, polycarbonate, polyarylene ether, and polyetherimide.
Among others, the resin composition comprising two or more resins selected from the group of polyarylene sulfide, polyetheretherketone, polyamide, polyester, liquid crystal polymers, polyarylene ether, and polyetherimide is more preferred because it can impart suitable viscosity to the resin strands and improve draw-off stability thereof.
The resin composition composing the strands is more preferably a mixture comprising both of a crystalline resin and an amorphous resin. Among others, a resin composition in a dispersed form in which the crystalline resin forms a continuous phase and the amorphous resin forms a disperse phase is most preferred because it can further reduce the phenomenon of a strand breakage.
Examples of preferred crystalline resins include one or more crystalline resins selected from the group of polyarylene sulfide, polyamide, and polyester. Among others, one or more crystalline resins selected from the group of polyarylene sulfide and polyamide are particularly preferred, and polyamide is the most preferred.
Examples of preferred amorphous resins include one or more amorphous resins selected from the group of polyarylene ether and polyetherimide. Among others, polyarylene ether is preferred, and polyphenylene ether is particularly preferred.
Preferred examples of combinations of the crystalline resin and amorphous resin include a combination of polyamide and polyphenylene ether, a combination of polyarylene sulfide and polyphenylene ether, and a combination of polyarylene sulfide and polyetherimide. Among others, most preferred is the combination of polyamide and polyphenylene ether or the combination of polyarylene sulfide and polyphenylene ether from the viewpoint of preparing a resin strand having a practical melt viscosity when it is reinforced with a filler and from the viewpoint of availability of these resins. A preferred dispersed form in these combinations is that in which polyamide or polyarylene sulfide forms a continuous phase and polyphenylene ether forms a disperse phase. The resin composition comprising polyamide and polyphenylene ether preferably comprises, as a compatibilizer of the both, one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form.
In order to improve the extrusion stability of resin strands, it is more preferred that one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form be used as a compatibilizer; the compatibilizer be preblended with part of polyphenylene ether; and the preblend be fed to an extruder through a feeder different from a feeder used for feeding remaining polyphenylene ether.
The compounds used as the compatibilizer in the present invention are more preferably in powder or granule form. Use of a compatibilizer in powder or granule form can suppress extrusion instability such as surging even in a reduced amount of the compatibilizer and can provide a composition having stable impact resistance and high flowability. Specifically, the unevenness in the impact strength and flowability in the same lot can be significantly suppressed. This can be verified by periodically collecting samples during production, actually measuring the impact strength and flowability thereof, and determining dispersion (standard deviation) thereof.
Moreover, the preblend of the present invention is excellent in the discriminating property from a powdery polyphenylene ether and very useful from the viewpoint of preventing mix-up and wrong operation because it discolors to dark yellow without heating.
The one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof which can be used in the present invention are preferably powdery or granular comprising particles in an amount of 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, most preferably 95% by mass or more and 99% by mass or less, the particles passing a 6 mesh (3.1 mm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 1.4 mm. When blocks formed by aggregation are present in the powder or granule, the blocks are preferably crushed by a mixer or a crusher so as to produce the particles as described above before it is blended with polyphenylene ether, thereby converting substantially all the compounds to be used to the particles having a shape as described above.
At this time, the polyphenylene ether to be preblended with these compounds is preferably a powdery polyphenylene ether. Regarding a specific particle size, the polyphenylene ether is preferably a powdery polyphenylene ether comprising fine particles in an amount of 60% by mass or more and 99% by mass or less, more preferably 80% by mass or more and 99% by mass or less, the fine particles not passing a 145 mesh (106 μm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 65 μm.
The amount of the polyphenylene ether incorporated into the preblend is preferably less than 5% by mass, more preferably 0.01% by mass or more and less than 3% by mass, most preferably 0.01% by mass or more and less than 1% by mass, based on 100% by mass of the amount of all the polyphenylene ether.
Moreover, the ratio of the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form to part of the powdery polyphenylene ether in the preblend is preferably 50 to 200 parts by mass of the compounds, more preferably 70 to 150 parts by mass of the compounds, most preferably 80 to 120 parts by mass of the compounds, based on 100 parts by mass of the polyphenylene ether.
The preblend may optionally comprise a peroxide. In this case, a preferred peroxide includes a peroxide having a one-minute half-life temperature in the range of 150° C. to 200° C. The peroxide may be in a liquid form or solid form. Solid peroxide is preferred in terms of handling properties and safety. When the peroxide is liquid, it is more preferably loaded onto or impregnated into a solid substance (for example, silica, talc, calcium carbonate, and the like).
When the peroxide is used, the amount thereof is preferably 0.001 to 1 part by mass, more preferably 0.1 to 0.5 part by mass, based on 100 parts by mass of all the polyphenylene ether.
Moreover, the amount of the peroxide in the preblend is preferably 10 to 200 parts by mass, more preferably 20 to 100 parts by mass, based on 100 parts by mass of the sum of the powdery polyphenylene ether and the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form as a compatibilizer.
The preblend in the present invention may be prepared by any method without particular limitation. Specific examples of the mixing method include a method of mixing part of the powdery polyphenylene ether, the one or more compounds, and optionally the peroxide using a Henschel mixer; a method of mixing part of the powdery polyphenylene ether, the one or more compounds, and optionally the peroxide using a tumbler blender; and a method of mixing part of the powdery polyphenylene ether, the one or more compounds, and optionally the peroxide using a screw blender.
Further, there is no particular limitation to the mixing temperature. For example, the mixing methods include a method of mixing the polyphenylene ether and maleic acid, citric acid, fumaric acid, or an anhydride thereof at a glass transition temperature of the polyphenylene ether or above; a method of mixing them at a melting temperature of maleic acid, citric acid, fumaric acid, or an anhydride thereof or above and below a glass transition temperature of the polyphenylene ether; and a method of mixing them below a melting temperature of maleic acid, citric acid, fumaric acid, or an anhydride thereof. An effective method among the above is the method of mixing them below a melting temperature of maleic acid, citric acid, fumaric acid, or an anhydride thereof. Particularly, mixing at room temperature (specifically from 0° C. to 30° C.) is preferred.
Maleic acid, citric acid, or an anhydride thereof is an example of a particularly preferred compound among the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form which can be used in the present invention. Among others, maleic anhydride is the most preferred.
The amount of the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.5 part by mass, most preferably 0.1 to 0.3 part by mass, based on 100 parts by mass of all the polyphenylene ether.
In the present invention, it is possible to add another compatibilizer other than the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form which can be used as a compatibilizer. The compatibilizer which can be added is not particularly limited as long as it improves physical properties of a polyamide-polyphenylene ether mixture. For example, all of the known compatibilizers described in detail in JP-A-08-8869 and JP-A-09-124926 can be used. The amount of the known compatibilizers is preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the polyphenylene ether.
Particularly preferred components which can be used in the resin composition to form resin strands will be described in detail below, but the present invention is not limited to these components.
As the polyphenylene ether, which is a particularly preferred resin among the amorphous resins which can be used in the resin composition to form resin strands, can be used a homopolymer and/or a copolymer comprising structural units represented by the following formula (I):

wherein O denotes an oxygen atom, and R each independently denote hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy, with a proviso that at least two carbon atoms are between a halogen atom and an oxygen atom.
Specific examples of the polyphenylene ether of the present invention include poly(2,6-dimethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenylene ether) and the like, and further include a polyphenylene ether copolymer such as a copolymer of 2,6-dimethylphenol with other phenols (for example, a copolymer with 2,3,6-trimethylphenol, and a copolymer with 2-methyl-6-butylphenol as described in JP-B-52-17880).
Among others, particularly preferred polyphenylene ether is poly(2,6-dimethyl-1,4-phenylene ether), a copolymer of 2,6-dimethylphenol with 2,3,6-trimethylphenol, or a mixture thereof. When a copolymer of 2,6-dimethylphenol with 2,3,6-trimethylphenol is used as a polyphenylene ether, the amount of 2,3,6-trimethylphenol in the copolymer is preferably 20 to 35% by mass, most preferably 25 to 30% by mass.
The production method of the polyphenylene ether used in the present invention is not particularly limited as long as it is a known method for obtaining polyphenylene ether. For example, the production methods as described in U.S. Pat. Nos. 3,306,874, 3,306,875, 3,257,357, and 3,257,358; JP-A-50-51197, JP-B-52-17880 and 63-152628, etc. are exemplified.
Reduced viscosity (η_sp/c: 0.5 g/dl, in a solution of chloroform, measured at 30° C.) of the polyphenylene ether which can be used in the present invention is preferably in the range of 0.15 to 0.70 dl/g, more preferably in the range of 0.20 to 0.60 dl/g, most preferably in the range of 0.40 to 0.55 dl/g.
Moreover, in the present invention, a styrenic thermoplastic resin may be blended in an amount of less than 50 parts by mass based on 100 parts by mass of the sum of polyamide and polyphenylene ether.
The styrenic thermoplastic resin as described in the present invention includes thermoplastic resins containing styrene monomer units in an amount of 50% by weight or more and having a flexural modulus of elasticity of 2,000 MPa or more.
Further, various known stabilizers can suitably be employed in order to stabilize the polyphenylene ether. Examples of the stabilizers include organic stabilizers such as hindered phenol stabilizers, phosphorus stabilizers and hindered amine stabilizers. The amount of these stabilizers to be blended is preferably 5 parts by mass or less based on 100 parts by mass of the polyphenylene ether.
In addition, known additives and the like which can be added to polyphenylene ether may also be added in an amount of 10 parts by mass or less based on 100 parts by mass of the polyphenylene ether.
As the polyamide, which is a particularly preferred resin among the crystalline resins which can be used in the resin composition to form resin strands, can be used any polymer which has an amide bond {—NH—C(═O)—} in the repeating units of the polymer.
Generally, a polyamide can be obtained by a ring opening polymerization of lactams, a condensation polymerization of a diamine and a dicarboxylic acid, a condensation polymerization of an aminocarboxylic acid and the like, but is not limited thereto.
The above described diamine includes an aliphatic, an alicyclic, and an aromatic diamine, and specifically includes tetramethylenediamine, hexamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 5-methylnanomethylenediamine, 1,9-nonamethylenediamine, 2-methyl-1,8-octamethylenediamine, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, m-phenylenediamine, p-phenylenediamine, m-xylylenediamine, and p-xylylenediamine.
The dicarboxylic acid is broadly divided into an aliphatic, an alicyclic, and an aromatic dicarboxylic acid, and specifically includes adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanoic diacid, 1,1,3-tridecanoic diacid, 1,3-cyclohexane dicarboxylic acid, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, dimmer acid and the like.
The lactams specifically include ε-caprolactam, enanthlactam, ω-laurocaprolactam and the like.
Further, the aminocarboxylic acid specifically includes ε-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, 13-aminotridecanoic acid and the like.
In the present invention, any of copolymer polyamides can be used, which is obtained by conducting a condensation polymerization singly of or in a mixture of at least two sorts of the above lactams, diamines, dicarboxylic acids and co-aminocarboxylic acids.
The polyamide resin especially usefully employed in the present invention includes polyamide 6, polyamide 66, polyamide 46, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide 6/66, polyamide 6/612, polyamide MXD (m-xylylene diamine), 6, polyamide 6T, polyamide 6I, polyamide 6/6T, polyamide 6/6I, polyamide 6,6/6,T, polyamide 6,6/6,I, polyamide 6/6,T/6,I, polyamide 6,6/6,T/6,I, polyamide 9/T, polyamide 6/12/6,T, polyamide 6,6/12/6,T, polyamide 6/12/6,I, polyamide 6,6/12/6,I and the like. Polyamides obtained by copolymerizing plural polyamides in an extruder or the like can also be used.
Among others, a preferred polyamide includes polyamide 6, polyamide 66, polyamide 6/6,6, polyamide 9/T, and the like. A more preferred one is polyamide 6, polyamide 66, polyamide 9/T, or a mixture thereof.
Terminal groups of the polyamide which can be used in the present invention are important because they are involved in the reaction with functionalized polyphenylene ethers. Polyamide resins generally have amino groups and carboxyl groups as terminal groups. Generally, higher carboxyl group concentration decreases impact resistance and increases flowability. On the other hand, higher amino group concentration increases impact resistance and decreases flowability.
The polyamide having an amino group/carboxyl group concentration ratio in the range of 1.0 to 0.1 can preferably be used in the present invention. The amino group/carboxyl group concentration ratio is more preferably in the range of 0.8 to 0.2, further preferably in the range of 0.6 to 0.3.
Moreover, when a polyamide mixture is used as a polyamide in the resin composition to form resin strands, all the terminal group concentration ratios of the polyamides to be used are preferably within the above described range.
As a method for adjusting the terminal groups of these polyamide resins, a method known to those skilled in the art may be used. For instance, the method includes a method in which one or more selected from the group of diamine compounds, monoamine compounds, dicarboxylic acid compounds, monocarboxylic acid compounds and the like are added so that a predetermined terminal group concentration can be obtained on polymerization of the polyamide resins.
Further, for the purpose of improving thermal resistant stability of a polyamide resin, a known metallic stabilizer as is described in JP-A-01-163262 can be used without any problem in the present invention.
Among these metallic stabilizers, CuI, CuCl₂, copper acetate, cerium stearate and the like are particularly preferred. An alkali metal halide typified by potassium iodide, potassium bromide and the like can also be suitably used. These may surely be used in combination.
The amount of the metallic stabilizer and/or the alkali metal halide to be blended is preferably from 0.001 to 1 part by mass based on 100 parts by mass of the polyamide resin.
Methods for adding these stabilizers are not particularly limited. They may be caused to be present together with monomers during polymerization or may be added during extrusion as a solid or a liquid dissolved in water or the like.
Furthermore, besides the above-described metallic stabilizers, known organic stabilizers may also be employed without any problem in the resin composition to form resin strands. Examples of the organic stabilizers include hindered phenol antioxidants typified by Irganox 1098, phosphorus processing heat stabilizers typified by Irgafos 168, lactone processing heat stabilizers typified by HP-136, sulfur heat stabilizers, hindered amine light stabilizers and the like.
Among these organic stabilizers, hindered phenol antioxidants, phosphorus processing heat stabilizers, or combinations thereof are more preferred.
The amount of these organic stabilizers to be blended is preferably from 0.001 to 1 part by mass based on 100 parts by mass of the polyamide resin.
In addition, besides the above described additives, known additives and the like which can be added to polyamides may also be added in an amount of 10 parts by mass or less based on 100 parts by mass of the polyamides.
When polyamide and polyphenylene ether are used in combination in the resin composition to form resin strands, the ratio of the amount of the both is preferably 40 to 80% mass of polyamide to 60 to 20% by mass of polyphenylene ether, more preferably 50 to 70% mass of polyamide to 50 to 30% by mass of polyphenylene ether, based on 100% mass of the sum of polyamide and polyphenylene ether.
Polyarylene sulfide (hereinafter may be abbreviated just as PAS) which can be used in the resin composition to form resin strands is desirably contain the following structure as a repeating unit:
[—Ar—S—] (Formula 1)
wherein Ar represents an arylene group including, for example, a p-phenylene group, a m-phenylene group, a substituted phenylene group substituted with an alkyl group having 1 to 10 carbon atoms or a phenyl group, a p,p′-diphenylene sulfone group, p,p′-biphenylene group, a p,p′-diphenylene carbonyl group, a naphtylene group, and the like.
The most preferred PAS that can be used in the present invention is a poly(p-phenylene) sulfide (hereinafter may be abbreviated as polyphenylene sulfide or PPS) in which 90% by mass or more of Ar in the Formula 1 has a p-phenylene structure.
Moreover, the PAS that can be used in the present invention may have a linear structure, a semi-linear structure, or a crosslinked structure.
The methods for producing a linear PAS include: a method for polymerizing a halogen-substituted aromatic compound, for example, p-dichlorobenzene, in the presence of sulfur and sodium carbonate; a method for polymerizing a halogen-substituted aromatic compound, for example, p-dichlorobenzene, in a polar solvent in the presence of sodium sulfide, sodium bisulfide and sodium hydroxide, hydrogen sulfide and sodium hydroxide, or sodium aminoalkanoate; and self-condensation of p-chlorothiophenol; and the like. Among others, a method for reacting sodium sulfide with p-dichlorobenzene in amide solvents such as N-methylpyrrolidone or dimethylacetamide or in sulfone solvents such as sulfolane is suitable. These production methods are known methods and include, for example, the methods described in U.S. Pat. No. 2,513,188, JP-B-44-27671, JP-B-45-3368, JP-B-52-12240, JP-A-61-225217, U.S. Pat. No. 3,274,165, JP-B-46-27255, Belgium Patent No. 29,437, and JP-A-05-222196, and the methods of prior arts illustrated in these patents. The linear PAS can be obtained by these known methods.
The method for producing a crosslinked (including semi-linear) PAS includes a method in which the above described linear PAS is polymerized; and then the resulting polymer is subjected to heating the PAS resin at the melting point or below in the presence of oxygen to promote oxidation crosslinking to appropriately increase molecular weight and viscosity of the polymer.
The linear PAS that can be used in the present invention preferably has an amount of the linear PAS extracted with methylene chloride of 0.7% by weight or less, more preferably 0.5% by weight or less.
The measurement of the amount extracted with methylene chloride can be performed by the following method. Specifically, 5 g of a linear PAS powder is subjected to Soxhlet extraction with 80 ml of methylene chloride for 6 hours and cooled to room temperature, and the resulting methylene chloride solution is transferred to a weighing bottle. Further, a total of 60 ml of methylene chloride is used, three times, to wash the above container used for the extraction, and the washings are collected in the above weighing bottle. Then, the methylene chloride in the weighing bottle is removed by evaporation by heating to about 80° C., and the residue is weighted. The percentage of the amount extracted with methylene chloride is determined from the amount of the residue.
A linear PAS having a terminal —SX group (wherein S represents a sulfur atom; and X represents an alkali metal or a hydrogen atom), as a terminal group, in an amount of 20 μmol/g or more, preferably 20 to 60 μmol/g, can preferably be used.
The —SX group can be quantified according to the following method. Specifically, a linear PAS powder is previously dried at 120° C. for 4 hours. Then, 20 g of the dried PAS powder is added to 150 g of N-methyl-2-pyrrolidone and stirred for mixing at room temperature for 30 minutes or more so that powder aggregates are eliminated, thereby forming a slurry. The slurry is filtered, and then washed repeatedly 7 times each with one liter of hot water of 80° C. The resulting filter cake is added into 200 g of water for slurrying it again, and then the slurry is mixed with 1N hydrogen chloride to adjust the pH of the slurry to 4.5. Next, the slurry is stirred at 25° C. for 30 minutes, filtered, and then washed repeatedly 6 times each with one liter of hot water of about 80° C. The resulting filter cake is added into 200 g of pure water for slurrying it again, and then the slurry is titrated with 1N sodium hydroxide to determine the amount of the —SX group present in the linear PAS from the consumed amount of sodium hydroxide.
The method described in JP-A-08-253587 is a specific example of a method for producing a linear PAS which satisfies an amount extracted with methylene chloride of 0.7% by weight or less and a terminal —SX group in an amount of 20 μmol/g or more.
The crosslinked PAS that can be used in the present invention preferably has an amount extracted with methylene chloride of 1% by weight or less.
Moreover, the above described linear PAS and crosslinked PAS that can be used in the present invention each have a melt viscosity at 300° C. of preferably from 1 to 10,000 poise, more preferably from 50 to 8,000 poise, further preferably from 100 to 5,000 poise.
In the present invention, the melt viscosity refers to a value which is measured at a load of 196 N and a ratio of die length (L)/die diameter (D) of 10 mm/1 mm after preheating PAS at 300° C. for 6 minutes using a flow tester (type CFT-500, manufactured by Shimadzu Corporation) according to JIS K-7210.
When PAS and polyphenylene ether are used in combination in the resin composition to form resin strands, the ratio of the amount of the both is preferably 40 to 80% by mass of PAS to 60 to 20% by mass of polyphenylene ether, more preferably 50 to 70% by mass of PAS to 50 to 30% by mass of polyphenylene ether, based on 100% by mass of the sum of PAS and polyphenylene ether.
Moreover, in the present invention, a compatibilizer may be added for the purpose of improving physical and chemical properties between PAS and polyphenylene ether. Preferred compatibilizers are styrene copolymers and/or ethylene copolymers having one or more functional groups selected from a glycidyl group and an oxazolyl group.
Specific examples of the unsaturated monomers having one or more functional groups selected from a glycidyl group and an oxazolyl group which compose the above copolymers include glycidyl methacrylate, glycidyl acrylate, vinyl glycidyl ether, glycidyl ether of hydroxyalkyl(meth)acrylate, glycidyl ether of polyalkylene glycol(meth)acrylate, glycidyl itaconate, 2-isopropenyl-2-oxazoline, and the like. Glycidyl methacrylate is preferred among others.
The proportion of the unsaturated monomers having one or more functional groups selected from a glycidyl group and an oxazolyl group in these copolymers is preferably from 0.3 to 20% by mass, more preferably from 1 to 15% by mass, further preferably from 3 to 10% by mass.
The amount of these copolymers to be blended is preferably from 1 to 20 parts by mass, more preferably from 2 to 15 parts by mass, further preferably from 3 to 10 parts by mass, based on 100 parts by mass of the sum of PAS and polyphenylene ether.
An elastomer may be added to the resin composition to form resin strands.
The elastomer that can be used is not particularly limited but preferably a block copolymer comprising at least one polymer block mainly composed of an aromatic vinyl compound and at least one polymer block mainly composed of a conjugated diene compound (hereinafter abbreviated just as a block copolymer).
As described herein, the term “mainly composed of” in the polymer block mainly composed of an aromatic vinyl compound means that at least 50% by mass or more of the block is composed of an aromatic vinyl compound. More preferably 70% by mass or more, further preferably 80% by mass or more, most preferably 90% by mass or more of the block is composed of an aromatic vinyl compound. Similarly, the term “mainly composed of” in the polymer block mainly composed of a conjugated diene compound means that at least 50% by mass or more of the block is composed of a conjugated diene compound. More preferably 70% by mass or more, further preferably 80% by mass or more, most preferably 90% by mass or more of the block is composed of a conjugated diene compound. Even in the case of a block in which, for example, a small amount of a conjugated diene or a different compound is randomly coupled to the aromatic vinyl compound block, such a copolymer is considered to be a block copolymer composed mainly of an aromatic vinyl compound if 50% by mass of the block is composed of an aromatic vinyl compound. This is also the same in the case of a conjugated diene compound.
Specific examples of aromatic vinyl compounds include styrene, α-methylstyrene, vinyl toluene and the like. One or more selected from the group of them can be used, and styrene is most preferred among others.
Specific examples of conjugated diene compounds include butadiene, isoprene, piperylene, 1,3-pentadiene and the like. One or more selected from the group of them can be used, and butadiene, isoprene and a combination thereof are preferred among others.
The block copolymer of the present invention preferably comprises a polymer block (a) mainly composed of an aromatic vinyl compound and a polymer block (b) mainly composed of a conjugated diene compound wherein the both are linked to each other in a linking structure selected from the a-b type, the a-b-a type and the a-b-a-b type. Of course, the block copolymer may have a mixture of these types. Among others, the a-b-a type and the a-b-a-b type are more preferred, and the a-b-a type is most preferred.
Preferred mixtures of block copolymers each having a different linking structure include a mixture of an a-b-a type block copolymer and an a-b type block copolymer, a mixture of an a-b-a type block copolymer and an a-b-a-b type block copolymer, and a mixture of an a-b-a-b type block copolymer and an a-b type block copolymer, and the like.
Further, the block copolymer which can be used in the resin composition to form resin strands is more preferably a hydrogenated block copolymer. The hydrogenated block copolymer refers to a block copolymer obtained by subjecting the above described block copolymer of an aromatic vinyl compound and a conjugated diene compound to hydrogenation treatment, thereby controlling the aliphatic double bond in the polymer block mainly composed of a conjugated diene compound into a range exceeding 0 up to 100%. A preferred hydrogenation degree of the hydrogenated block copolymer is 50% or more, more preferably 80% or more, most preferably 98% or more.
These block copolymers can be used without any problems as a mixture of a block copolymer which is not hydrogenated and a hydrogenated block copolymer.
Moreover, a wholly or partially modified block copolymer or a block copolymer previously mixed with an oil as described in WO 02/094936 can suitably be used in the resin composition to form resin strands.
The elastomer is blended preferably in an amount ranging from 1 to 20 parts by weight, more preferably ranging from 3 to 15 parts by weight, most preferably ranging from 5 to 13 parts by weight, based on 100 parts by weight of the sum of polyamide and polyphenylene ether.
In addition, the resin composition to form resin strands may be mixed with an inorganic filler in an amount of preferably from 5 to 50% by mass, more preferably from 8 to 40% by mass, most preferably from 10 to 30% by mass, based on 100% mass of the total resin composition.
The type of preferred inorganic fillers includes one or more selected from the group of glass fiber, glass flake, talc, wollastonite, mica, titanium dioxide, alumina, silica, clay, zinc oxide, and zinc sulfide.
Among others, glass fiber, wollastonite, talc, clay, titanium oxide, and zinc oxide are preferred, and glass fiber, wollastonite, talc, and titanium oxide are more preferred.
Wollastonite which can be used in the present invention will be described in detail.
Wollastonite which can be used in the present invention is a material obtained by purifying, pulverizing, and classifying a natural mineral composed of calcium silicate. Alternatively, an artificially synthesized wollastonite can also be used. The wollastonite preferably has an average particle size of 2 to 9 μm and an aspect ratio of 5 or more, more preferably an average particle size of 3 to 7 μm and an aspect ratio of 5 or more, further preferably an average particle size of 3 to 7 μm and an aspect ratio of 8 or more and 30 or less.
Next, talc which can be used in the present invention will be described in detail.
Talc which can suitably be used in the present invention is a material obtained by purifying, pulverizing, and classifying a natural mineral composed of magnesium silicate. Further, it is more preferred that the crystallite diameter on the (0 0 2) diffraction plane of talc as determined by wide angle X-ray diffraction be 570 angstroms or more.
The (0 0 2) diffraction plane of talc as described herein can be verified as follows: The presence of talc, Mg₃Si₄O₁₀(OH)₂, is identified using a wide angle X-ray diffraction apparatus, and the interlayer distance thereof is found to be about 9.39 angstroms which is the lattice spacing of the (0 0 2) diffraction plane of talc. Further, the crystallite diameter on the (0 0 2) diffraction plane of talc is calculated from the half-width of the peak.
The talc preferably has an average particle size of 1 μm or more and 20 μm or less and a particle size distribution represented by d75%/d25% of 1.0 or more and 2.5 or less. In the ratio d75%/d25%, d25% represents a particle size of 25% of the total number of particles as integrated from a particle of the smallest diameter, and d75% represents a particle size of 75% of the same. The ratio d75%/d25% is more preferably 1.5 or more and 2.2 or less.
The talc preferably has an average particle size of 1 μm or more and 16 μm or less, more preferably 3 μm or more and less than 9 μm.
As described herein, the average diameter and particle size distribution of talc are based on the volume-based particle size as measured by a laser diffraction/scattering particle size distribution analyzer, which is measured by using ethanol as a solvent to disperse talc.
Glass fibers which can suitably be used in the present invention preferably include a chopped strand having a fiber diameter of 5 μm to 20 μm in terms of mechanical properties and handling properties. A more preferred fiber diameter is from 8 μm to 15 μm.
These inorganic fillers may be treated with a binder for the purpose of enhancing handling properties and improving adhesion with resins. Compounds based on epoxy, urethane, maleic acid-modified urethane, and amine-modified urethane can suitably be used as a binder for these purposes. Of course, these binders may be used in combination. Among the above described binders, an epoxy compound having a plurality of epoxy groups in a molecular structure can be particularly preferably used as a binder. Novolac epoxy is particularly preferred among the epoxy compounds.
In addition, the following surface treatment agents can be used optionally: higher aliphatic acids or derivatives such as esters or salt thereof (for example, stearic acid, oleic acid, palmitic acid, magnesium stearate, calcium stearate, aluminum stearate, stearamide, ethyl stearate, and the like) and coupling agents (for example, silane, titanate, aluminum-based, zirconium-based, and the like).
The amount of inorganic fillers to be used is from 0.05 to 5 parts by mass, more preferably from 0.1 to 2 parts by mass, based on 100 parts by mass thereof.
In addition, the resin composition to form resin strands may be mixed with electrically conductive carbon fillers. The amount of the electrically conductive carbon fillers to be added is preferably from 0.5 to 3 parts by mass, more preferably from 0.5 to 2.5 parts by mass, most preferably from 1.5 to 2.5 parts by mass, based on 100 parts by mass of the resin composition exclusive of inorganic filler components.
The electrically conductive carbon fillers which can suitably be used include electrically conductive carbon black, carbon fibril, and graphite. Among others, electrically conductive carbon black and carbon fibril are particularly preferred.
When electrically conductive carbon black is used as an electrical conductivity-imparting material in the present invention, the electrically conductive carbon black preferably has a dibutyl phthalate (DBP) absorption of 250 ml/100 g or more, more preferably 300 ml/100 g or more, further preferably 350 ml/100 g or more. As described herein the DBP absorption refers to a value determined by the method specified in ASTM D2414.
Further, the electrically conductive carbon black which can be used in the present invention preferably has a BET specific surface area (JIS K6221-1982) of 200 m²/g or more, more preferably 400 m²/g or more. Examples of commercially available electrically conductive carbon fillers include Ketjen black EC and Ketjen black EC-600JD available from Ketjen Black International Co., Ltd.
The carbon fibrils which can be used as an electrical conductivity-imparting material in the present invention include carbon fibers having a fiber diameter of less than 75 nm, a hollow structure, and only a small amount of branches as described in U.S. Pat. Nos. 4,663,230, 5,165,909, 5,171,560, 5,578,543, 5,589,152, 5,650,370, and 6,235,674. The fibrils also include those in the form of a coil with a pitch of 1 μm or less. Commercially available carbon fibrils include those (BN fibril) available from Hyperion Catalysis International, Incorporated.
Examples of graphite which can be used as an electrical conductivity-imparting material in the present invention include not only those obtained by heating anthracite, pitch, or the like at elevated temperatures in an arc furnace but also a graphite which is naturally produced. The graphite preferably has a weight average particle size of 0.1 to 50 μm, more preferably 1 to 30 μm.
The method for adding these electrical conductivity-imparting agents includes, but is not limited to, a method of adding an electrical conductivity-imparting agent to a melt mixture of polyamide and polyphenylene ether and then melt-kneading the resulting mixture; a method of adding an electrical conductivity-imparting agent in the form of a masterbatch in which the electrical conductivity-imparting agent is previously blended in polyamide; and the like. In particular, the electrical conductivity-imparting agent is preferably added in the form of a masterbatch in which it is previously blended in polyamide.
When carbon fibrils are used as an electrical conductivity-imparting agent, a polyamide/carbon fibril masterbatch available from Hyperion Catalysis International, Incorporated can be used as a masterbatch.
The amount of the electrical conductivity-imparting agent in a masterbatch is preferably from 5 to 25% by mass based on 100% by mass of the masterbatch. When an electrically conductive carbon black is used as an electrical conductivity-imparting agent, the amount of the electrical conductivity-imparting agent in a masterbatch is preferably from 5 to 15% by mass, more preferably 8 to 12% by mass. Further, when graphite or carbon fibril is used as an electrical conductivity-imparting agent, the amount of the electrical conductivity-imparting agent in a masterbatch is preferably from 15 to 25% by mass, more preferably 18 to 23% by mass.
A flame retardant may be added to a resin composition to compose resin strands. Flame retardants which can suitably be used include phosphate compounds, phosphazene compounds, phosphinates, and the like. Phosphinates and phosphazene compounds are particularly preferred among these compounds.
Preferred phosphinates will be specifically described below.
The phosphinates which can suitably be used are diphosphinates or condensates thereof (in the present specification, all of them may be abbreviated as phosphinates) represented by the following formula (I) and/or the following formula (II):

wherein R¹and R²are the same or different and each represent a linear or branched C₁-C₆alkyl and/or aryl or phenyl; R³represents a linear or branched C₁-C₁₀alkylene, a C₆-C₁₀arylene, a C₆-C₁₀alkylarylene, or a C₆-C₁₀arylalkylene; M represents one or more selected from the group of calcium (ion), magnesium (ion), aluminum (ion), zinc (ion), bismuth (ion), manganese (ion), sodium (ion), potassium (ion), and a protonated nitrogen base; m represents 2 or 3; n represents 1 to 3; and x represents 1 or 2.
These phosphinates are produced in an aqueous solution using phosphinic acid and a metal carbonate, a metal hydroxide, or a metal oxide as described in EP-A-699,708 and JP-A-08-73720.
These phosphinates are essentially monomeric compounds. However, polymeric phosphinates, which are the condensates having a condensation degree of 1 to 3, are also contained therein depending on reaction conditions for the production thereof.
In terms of the development of higher flame retardancy and the suppression of MD generation, the phosphinates which can be used in the present invention preferably include 90% by mass or more, more preferably 95% by mass or more, most preferably 98% by weight or more of a phosphinate represented by the following formula (I):

wherein R¹and R²are the same or different and each represent a linear or branched C₁-C₆alkyl and/or aryl or phenyl; M represents one or more selected from the group of calcium (ion), magnesium (ion), aluminum (ion), zinc (ion), bismuth (ion), manganese (ion), sodium (ion), potassium (ion), and a protonated nitrogen base; and m represents 2 or 3.
Specific examples of phosphinic acid which can suitably be used in the present invention include dimethylphosphinic acid, ethylmethylphosphinic acid, diethylphosphinic acid, methyl-n-propylphosphinic acid, methane-di(methylphosphinic acid), benzene-1,4-(dimethylphosphinic acid), methylphenylphosphinic acid, diphenylphosphinic acid, and mixtures thereof.
Moreover, the metal components which can be used preferably include one or more selected from the group of calcium ions, magnesium ions, aluminum ions, zinc ions, bismuth ions, manganese ions, sodium ions, potassium ions and protonated nitrogen bases, more preferably one or more selected from the group of calcium ions, magnesium ions, aluminum ions, and zinc ions.
Specific examples of the phosphinates which can suitably be used include calcium dimethylphosphinate, magnesium dimethylphosphinate, aluminum dimethylphosphinate, zinc dimethylphosphinate, calcium ethylmethylphosphinate, magnesium ethylmethylphosphinate, aluminum ethylmethylphosphinate, zinc ethylmethylphosphinate, calcium diethylphosphinate, magnesium diethylphosphinate, aluminum diethylphosphinate, zinc diethylphosphinate, calcium methyl-n-propylphosphinate, magnesium methyl-n-propylphosphinate, aluminum methyl-n-propylphosphinate, zinc methyl-n-propylphosphinate, calcium methane-di(methylphosphinate), magnesium methane-di(methylphosphinate), aluminum methane-di(methylphosphinate), zinc methane-di(methylphosphinate), calcium benzene-1,4-(dimethylphosphinate), magnesium benzene-1,4-(dimethylphosphinate), aluminum benzene-1,4-(dimethylphosphinate), zinc benzene-1,4-(dimethylphosphinate), calcium methylphenylphosphinate, magnesium methylphenylphosphinate, aluminum methylphenylphosphinate, zinc methylphenylphosphinate, calcium diphenylphosphinate, magnesium diphenylphosphinate, aluminum diphenylphosphinate, and zinc diphenylphosphinate.
In particular, in terms of the development of higher flame retardancy and the suppression of MD, are preferred calcium dimethylphosphinate, aluminum dimethylphosphinate, zinc dimethylphosphinate, calcium ethylmethylphosphinate, aluminum ethylmethylphosphinate, zinc ethylmethylphosphinate, calcium diethylphosphinate, aluminum diethylphosphinate, and zinc diethylphosphinate.
In the present invention, the amount of the phosphinates is preferably from 1 to 50 parts by mass, more preferably from 2 to 25 parts by mass, particularly preferably from 2 to 15 parts by mass, most preferably from 3 to 10 parts by mass, based on 100 parts by mass of the sum of polyamide and polyphenylene ether. In order to cause sufficient flame retardancy to be developed, the amount of the phosphinates is preferably 1 part by mass or more. In order to provide a melt viscosity suitable for extrusion, the amount of the phosphinates is preferably 50 parts by mass or less.
Moreover, in consideration of the mechanical strength and appearance of molded articles obtained by molding the flame retardant resin composition of the present invention, the lower limit of the number average particle size of the phosphinates is preferably 0.1 μm, more preferably 0.5 μm. The upper limit of the number average particle size of the phosphinates is preferably 40 μm, more preferably 20 μm, most preferably 10 μm.
The number average particle size of the phosphinates is preferably 0.1 μm or more because handling properties and biting properties into the extruder are improved in the processing such as melt-kneading. Further, a number average particle size of 40 μm or less allows the mechanical strength of the resin composition to be easily developed and improves the surface appearance of molded articles.
The number average particle size of the above phosphinates can be measured and analyzed by dispersing the phosphinates in water and using a laser diffraction particle size distribution analyzer (for example, trade name: SALD-2000, manufactured by Shimadzu Corporation, Japan). Phosphinates are dispersed in water by a method of charging water and the phosphinates into an agitation tank equipped with an ultrasonic dispersing machine and/or an agitator to form a dispersion of phosphinates in water. The dispersion is sent to a measuring cell through a pump to measure the particle size by laser diffraction. The number average particle size can be calculated from the particle size and frequency distribution of the particle number obtained by the measurement.
Moreover, the phosphinates in the present invention may be left unreacted or may leave byproducts thereof if they do not impair the effect of the present invention.
The phosphinates which can be used in the present invention may be added in the form of a flame retardant masterbatch in which polyamide is mixed in advance. The percentage of the phosphinates in the flame retardant masterbatch is preferably from 10 to 60% by mass, more preferably from 20 to 50% by mass, based on 100% by mass of the flame retardant masterbatch. The method for producing the flame retardant masterbatch is not particularly limited. Specific examples include a method of melt-kneading a mixture obtained by previously mixing polyamide and phosphinates without melting them, a method of adding phosphinates to a molten polyamide followed by further melt-kneading the mixture, and the like. The latter method is desirable because the dispersibility of the flame retardant is improved.
The resin composition to form resin strands may be optionally mixed with an additional component other than the components as described above within a range not impairing the effect of the components. The amount of the additional component to be added is preferably not more than 15 parts by mass based on 100 parts by mass of the sum of polyamide and polyphenylene ether.
Examples of the additional components include different thermoplastic resins such as polyester and polyolefin, known silane coupling agents for enhancing the affinity of inorganic fillers to resins, flame retardants (such as halogenated resins, silicone flame retardants, magnesium hydroxide, aluminum hydroxide, organic phosphate compounds, ammonium polyphosphate, and red phosphorus), fluoropolymers exhibiting antidrop effect, plasticizers (such as oil, low molecular weight polyolefins, polyethylene glycols, and aliphatic esters), flame retardant auxiliaries such as antimony trioxide, coloring agents such as carbon black, antistatic agents, conductive fillers, various peroxides, antioxidants, ultraviolet absorbers, light stabilizers, and the like.
Processing machines to obtain resin strands include extruders such as single screw extruders and twin screw extruders. Twin screw extruders are preferred among them. In particular, a twin screw extruder equipped with an upstream feed port and one or more downstream feed ports is the most preferred.
In the production method of the present invention, the screw diameter of the extruder which can be used is not particularly limited, but it is preferably about 20 mm or more and about 200 mm or less, more preferably about 40 mm or more and about 125 mm or less, most preferably about 50 mm or more and less than about 100 mm.
Moreover, the L/D of the extruder is preferably about 20 or more and less than about 60, more preferably about 30 or more and less than about 60, most preferably about 40 or more and less than about 60. As described herein, the term L/D refers to a value obtained by dividing the screw length [L] by the screw diameter [D] of the extruder.
As for a preferred position of a downstream feed port of the extruder, the first downstream feed port is at a position within the range of about 30 to about 70, wherein the position is measured starting from the position of the upstream feed port of the extruder and the cylinder length is defined as 100. When the second feed port is provided, it is at a position within the range of about 40 to about 80 by defining the cylinder length as 100.
The melt-kneading temperature is not particularly limited. Generally, a temperature capable of obtaining a suitable composition can be arbitrarily selected from the range of about 260 to about 350° C. The temperature is preferably in the range of about 270 to about 330° C., particularly preferably in the range of about 300 to about 330° C. to a downstream feed port and in the range of about 270 to about 300° C. from the downstream feed port.
In the production method of the present invention, a higher effect can be developed when the output (extruder capacity) per hour is 500 kg or more. The output per hour is preferably 500 kg or more in order to develop high flowability and stable impact resistance with a small amount of compatibilizer, because the feed rate of a dry blend per hour will be too low when the output per hour is less than 500 kg.
The present invention will be described in further detail below with reference to Examples and Comparative Examples.

EXAMPLES

The present invention will be described based on Examples.

Example 1

The Present Invention

The maximum cylinder temperature of a co-rotating twin screw extruder was set at 320° C., the extruder having an L/D of 48 provided with one feed port in the upstream side and one feed port in the downstream side [ZSK70MC: manufactured by Coperion Corporation, having 12 temperature control blocks (L/D per block being 4) and an auto screen changer block; upstream feed port: the first block, downstream feed port: the sixth block, vent ports to remove volatiles by vacuum suction: the fifth block and the tenth block]. From the upstream feed port were fed separately (using separate feeders without being blended) to the extruder and melt-kneaded 35 parts by mass of polyphenylene ether [S201A: manufactured by Asahi Kasei Chemicals Corporation], 0.1 part by mass of granular maleic anhydride manufactured by ACROS ORGANICS (Germany), 10 parts by mass of a styrene-ethylenebutylene-styrene block copolymer [Kraton G1651: manufactured by Kraton Polymers] as elastomer component, and 5 parts by mass of homo-polystyrene [Stayron 685: manufactured by Dow Chemical Company (United States)]. Subsequently, from the downstream feed port was fed and melt-kneaded a dry blend which was obtained by dry-blending 50 parts by mass of polyamide 6,6 [Vydyne 48BX: manufactured by Solutia Inc. (United States) (hereinafter abbreviated just as PA66) with 0.25 part by mass of carbon black as a pigment in a tumbler blender. At this time, the number of revolutions of the screw was 550 rpm.
The discharge rate at this time was 1,000 kg/hr so that the discharge per unit area of the opening of the die holes was from 80 kg/cm²to 200 kg/cm². At this time, the diameter of the die holes was 4 mm and the number of the die holes was 50. The discharge per unit area of the opening of the die holes calculated from these values is 159 kg/cm².
The strand-shaped molten resin discharged from the die holes was conveyed while being cooled on a conveyor having a total length of the conveying part of 6.5 m equipped with a water spraying apparatus followed by pelletizing with a strand cutter. At this time, the strands were cooled with three water spraying apparatuses in total installed at positions ranging from 3.5 m apart from the die holes (a position downstream by 54% of the total length of the conveying part of the conveyor) to 4.0 m apart from the die holes (a position downstream by 62% of the total length of the conveying part of the conveyor).
In order to verify the phenomenon of strand breakage occurring between the conveyor and the strand cutter, the number of strands broken in five minutes was checked. No strand was broken in this time period.
Moreover, at this time, the surface temperature of the strand before entering the strand cutter was measured to be 138° C. by an infrared thermometer. The moisture content of cut pellets was measured to be about 280 ppm. The moisture content was measured according to the method B of ISO 15512:1992 (oven was set at a temperature of 180° C.).
Further, the amount of adhered consecutive pellets included in the cut pellets was measured, but no adhered consecutive pellets were found. The cut surface of the pellets had a major axis diameter of 3.2 mm and a minor axis diameter of 3.0 mm. These values are summarized in Table 1.

Example 2

The Present Invention

All experiments were performed in the same manner as in Example 1 except that the strands were cooled by installing three water spraying apparatuses for cooling strands in total were installed at positions ranging from 1.8 m apart from the die holes (a position downstream by 28% of the total length of the conveying part of the conveyor) to 2.3 m apart from the die holes (a position downstream by 35% of the total length of the conveying part of the conveyor), and various performances were evaluated. The results are shown in Table 1.

Examples 3 and 4

The Present Invention

All experiments were performed in the same manner as in Example 1 except that the extruder capacity was changed, and various performances were evaluated. The results are shown in Table 1.

Comparative Examples 5 and 6

All experiments were performed in the same manner as in Example 1 except that the position of water spray for cooling strands was changed, and various performances were evaluated. The results are shown in Table 1. At this time, water was sprayed from a distance of 0.5 m.

Comparative Example 7

Experiments were performed in the same manner as in Example 5 except that the extruder capacity was changed to 1,300 kg/hr and the number of revolutions of the screw was changed to 700 rpm, and various performances were evaluated. The results are shown in Table 1.

Example 8

All experiments were performed in the same manner as in Example 1 except that the component to be fed from a downstream feed port was changed to a mixture of 35 parts by mass of PA66 and 15 parts by mass of a polyamide 66/carbon fibril masterbatch (trade name: Polyamide66 with Fibril™ Nanotubes RMB4620-00: carbon fibril amount of 20%), and various performances were evaluated. The results are shown in Table 1.

Comparative Example 9

All experiments were performed in the same manner as in Example 5 except that the component to be fed from a downstream feed port was changed to a mixture of 35 parts by mass of PA66 and 15 parts by mass of a polyamide 66/carbon fibril masterbatch (trade name: Polyamide66 with Fibril™ Nanotubes RMB4620-00: carbon fibril amount of 20%), and various performances were evaluated. The results are shown in Table 1.

TABLE 1


Table 1

					Comp.	Comp.	Comp.		Comp.
Unit	Ex. 1	Ex. 2	Ex. 3	Ex. 4	Ex. 5	Ex. 6	Ex. 7	Ex. 8^(*1)	Ex. 9^(*1)

Discharge rate	kg/hr	1000	1000	600	480	1000	1000	1300	1000	1000
Diameter of die holes	mm		4	4	4	4	4	4	4	4	4
Number of die holes	piece	50	50	50	50	50	50	50	50	50
Percentage of 1st cooling position-die hole length to	%	54	28	54	54	18	80	18	54	18
total conveying part length
Discharge per unit area of opening of die holes	kg/cm²	159	159	96	76	159	159	207	159	159
Strand temperature (immediately before strand	° C.	138	110	104	82	89	95	157	143	98
cutter)
Number of broken strands	piece	0	4	3	9	27	0	17	0	34
Moisture content of pellets	ppm	280	470	960	1110	1040	1400	210	340	970
Amount of adhered consecutive pellets in pellets	mass %	none	0.14	0.25	0.35	2.1	8.9	5.6	none	0.9
Diameter of pellet cut surface (major axis)	mm	3.2	3.2	3.1	3.2	3.2	3.1	4.3	3.1	3.2
Diameter of pellet cut surface (minor axis)	mm	3	3.1	3	3.1	3	3	1.9	2.9	2.9

^(*1)Resin composition is different from that in Examples 1 to 7.

It can be understood from Table 1 that strand breakage is dramatically improved; the amount of adhered consecutive pellets contained in the product pellets is reduced; and the moisture content of the pellets can be significantly reduced by adjusting the position at which the conveyed strand-shaped molten resin is brought into initial contact with the cooling water to a position downstream ranging from 20% to 70% of the total length of the conveying part of the conveyor.
Moreover, it can be understood that the moisture content of the pellets can also be reduced by controlling the discharge per unit area of the opening of the die holes within a specific range.

Example 10

The Present Invention

The maximum cylinder temperature of a co-rotating twin screw extruder was set at 320° C., the extruder having an L/D of 48 provided with one feed port in the upstream side and one feed port in the downstream side [ZSK40MC: manufactured by Coperion Corporation, having 12 temperature control blocks (L/D per block being 4); upstream feed port: the first block, downstream feed port: the sixth block, vent ports to remove volatiles by vacuum suction: the fifth block and the tenth block]. From the upstream feed port was fed to the extruder and melt-kneaded a mixture of 25 parts by mass of polyphenylene ether [S201A: manufactured by Asahi Kasei Chemicals Corporation], 35 parts by mass of polyphenylene sulfide [K-25: manufactured by Dainippon Ink and Chemicals, Incorporated], and 2 parts by mass of styrene-glycidyl methacrylate copolymer [Marproof 1005S: manufactured by NOF Corporation] as a compatibilizer. Subsequently, from the downstream feed port were fed and melt-kneaded 20 parts by mass of glass fiber [ECS03T-249: manufactured by Nippon Electric Glass Co., Ltd.], 20 parts by mass of mica [suzolite mica 200HK: manufactured by Kuraray Co., Ltd.], and 0.25 part by mass of carbon black as a pigment. At this time, the number of revolutions of the screw was 550 rpm.
The discharge rate at this time was 180 kg/hr so that the discharge per unit area of the opening of the die holes was from 80 kg/cm²to 200 kg/cm². At this time, the diameter of the die holes was 4 mm and the number of the die holes was 10. The discharge per unit area of the opening of the die holes calculated from these values is 143 kg/cm².
The strand-shaped molten resin discharged from the die holes was conveyed while being cooled on a conveyor having a total length of the conveying part of 4.0 m equipped with a water spraying apparatus followed by pelletizing with a strand cutter. At this time, the strands were cooled with two water spraying apparatuses in total installed at positions 1.2 m apart from the die holes (a position downstream by 30% of the total length of the conveying part of the conveyor) and 1.7 m apart from the die holes (a position downstream by 43% of the total length of the conveying part of the conveyor).
In order to verify the phenomenon of strand breakage occurring between the conveyor and the strand cutter, the number of strands broken was checked in the same manner as in Example 1. No strand was broken in this time period.
Further, the amount of adhered consecutive pellets included in the cut pellets was measured, but no adhered consecutive pellets were found.
Further, the moisture content of the pellets was 400 ppm. When the resulting pellets were observed, the shape of the pellets was good, but it was found that a small amount of “fine powder” called chippings was produced. The results are shown in Table 2.

Comparative Example 11

All experiments were performed in the same manner as in Example 10 except that the position of water spraying was changed to positions 0.2 m apart from the die holes (a position downstream by 5% of the total length of the conveying part of the conveyor) and 0.7 m apart from the die holes (a position downstream by 17.5% of the total length of the conveying part of the conveyor).
At this time, strand breakage occurred very frequently, all of the 10 strands having been broken in five minutes.
When the moisture content of the resulting pellets was measured, it was as low as 380 ppm, but most of the pellets had longitudinal cracks, producing a large amount of fine powder. The results are shown in Table 2.

Comparative Example 12

All experiments were performed in the same manner as in Example 10 except that the position of water spraying was changed to positions 0.7 m apart from the die holes (a position downstream by 17.5% of the total length of the conveying part of the conveyor) and 1.2 m apart from the die holes (a position downstream by 30% of the total length of the conveying part of the conveyor).

At this time, five strands were broken. The moisture content of the resulting pellets was 400 ppm, but part of the pellets had longitudinal cracks and production of a substantial amount of fine powder was also observed. The results are shown in Table 2.

TABLE 2


		Comp. Ex.	Comp. Ex.
Unit	Ex. 10	11	12

Discharge rate	kg/hr	180	180	180
Diameter of die holes	mm		4	4	4
Number of die holes	piece	10	10	10
Percentage of 1st	%	30	5	17.5
cooling position-die
hole length to total
conveying part length
Discharge per unit	kg/cm²	143	143	143
area of opening of
die holes
Strand temperature	° C.	122	76	102
(just before strand
cutter)
Number of broken	piece	0	10 (all)	5
strands
Moisture content of	ppm	400	380	400
pellets
Amount of adhered	mass %	none	—	—
consecutive pellets
in pellets
State of pellets	—	none	mostly	partly
(longitudinal			longitudinally	occurred
cracks)			cracked
Production of fine	—	small	large amount	substantial
powder		amount

Production Example 1

Production of Polyphenylene Ether A (Hereinafter Abbreviated Just as PPE-A)
Polyphenylene ether [S201A] was dissolved in toluene to obtain a solution of 13% by mass. At this time, the toluene was warmed to 80° C. to dissolve it.
Next, the solution was transferred to a concentration tank to remove toluene by evaporation under ordinary pressure at 120° C. under a nitrogen atmosphere, thereby concentrating the solution until it has a solution viscosity at 80° C. of 1,000 mPa s. The solution viscosity was measured by a B type viscometer manufactured by Tokyo Keiki. The amount of toluene in the concentrated solution was calculated from the amount of toluene which has been removed by evaporation.
Next, a mixed solvent containing toluene and methanol in a toluene/methanol mass ratio of 0.5 was charged into a solidification tank equipped with a reciprocating rotary agitator so that the sum of the solvent in the concentrated solution and the mixed solvent after solidification has a toluene/methanol mass ratio of 0.83. Then, the concentrated solution was added dropwise with a feed pump to the mixed solvent which is agitated, thereby obtaining polyphenylene ether particles.
The polyphenylene ether particles in the toluene/methanol mixed solution containing the polyphenylene ether particles were separated by a centrifuge to obtain a polyphenylene ether wet cake.
Then, the polyphenylene ether wet cake was dried at 135 to 140° C. for 6 hours or more to obtain dried particles of polyphenylene ether. During the drying, nitrogen was introduced into a dryer at a flow rate of 5 Nm³/hr.
The resulting dried particles in an amount of 20 g were collected and put in a sieve having a 145 mesh (106 μm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 65 μm. The sieve was vibrated for 10 minutes using a TNK sieve vibrator (manufactured by Tanaka Chemical Machinery Co.) to sieve the dried particles, thereby classifying them to particles passing the 145-mesh sieve and those not passing it. At this time, the mass of the polyphenylene ether particles remaining on the 145-mesh sieve without passing it was measured and determined to be 83% by mass.

Production Example 2

Production of Polyphenylene Ether B (Hereinafter Abbreviated Just as PPE-B)
Experiments were performed to obtain polyphenylene ether particles in the same manner as in Production Example 1 except that the solvent charged into the solidification tank equipped with a reciprocating rotary agitator was only methanol. The mass of the polyphenylene ether particles remaining on the 145-mesh sieve for polyphenylene ether without passing it was measured and determined to be 66% by mass.

Example 13

Preparation of Preblend-1 (Hereinafter Abbreviated as PB-1)
Maleic anhydride manufactured by Mitsubishi Chemical Corporation as a compatibilizer was blended with PPE-B and Perhexa 25B-40 (a solid in which peroxide is impregnated in silica, having a peroxide concentration of 40% by mass: hereinafter abbreviated just as peroxide) as a peroxide in a rotary tumbler blender having a volume of 20 liter according to the percentage shown in Table 3. At this time, the number of revolutions of the screw was 50 rpm, and the mixing time was about 2 minutes.
The resulting preblend was put in a transparent polyethylene bag, left standing for about 30 minutes, and checked for the change of color. The results are shown in Table 3. (Note that the blend had an initial color of white and was found to have a sufficient discriminating property.)
Next, the preblend was charged into a K2-ML-S60 type feeder (a twin-screw type, no agitator) manufactured by K-Tron AG (Switzerland) and fed at a feed rate of 5 kg/hr for about 1 hour. The stability of feed was checked, and the adhesion of maleic anhydride to the screw feeder after feeding a specific time period was also checked.
The maleic anhydride used was measured for the amount passing a 6 mesh woven wire. The maleic anhydride in an amount of 20 g was collected and put in a sieve having a 6 mesh (3.1 mm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 1.4 mm. The sieve was vibrated for 10 minutes using a TNK sieve vibrator (manufactured by Tanaka Chemical Machinery Co.) to sieve the maleic anhydride, thereby classifying it to the maleic anhydride passing the 6-mesh sieve and that not passing it. At this time, the mass of the maleic anhydride passing the 6-mesh sieve was measured and determined to be 75% by mass.

Example 14

Preparation of Preblend-2 (Hereinafter Abbreviated as PB-2)
A granular maleic anhydride manufactured by ACROS ORGANICS Co. (Germany) as a compatibilizer was blended in a rotary tumbler blender in the same manner as in Example 1 according to the percentage shown in Table 3, and the resulting blend was evaluated in the same manner. The results are shown in Table 3.
Further, the granular maleic anhydride used was measured for the amount passing a 6 mesh woven wire in the same manner as in Example 1. The amount was determined to be 99.7% by mass.

Examples 15 to 16

Preparation of Preblends-3 and 4 (Hereinafter Abbreviated as PB-3 and PB-4)
All experiments were performed in the same manner as in Example 14 except that PPE-A was used as polyphenylene ether and the composition was changed to those shown in Table 3. These results are shown in Table 3.

Example 17

Preparation of Preblend-5 (Hereinafter Abbreviated as PB-5)

All experiments were performed in the same manner as in Example 13 except that PPE-A was used as polyphenylene ether and the composition was changed to that shown in Table 3. The results are shown in Table 3.

TABLE 3


Table 3

	Unit	Ex. 13 (PB-1)	Ex. 14 (PB-2)	Ex. 15 (PB-3)	Ex. 16 (PB-4)	Ex. 17 (PB-5)

PPE-A	*1	Parts by mass			25	30	99.25
PPE-B	*2	Parts by mass	25	25
MAH	*3	Parts by mass	25				0.25
MAH	*4	Parts by mass		25	25	70
Peroxide	*5	Parts by mass	50	50	50		0.5
Color		—	Yellow	Dark yellow	Dark yellow	Dark yellow	No difference
(Distinctness from PPE powder)		—	(Good)	(Very good)	(Very good)	(Very good)	(Poor)
Feed stability in feeder		Good/Poor	Poor (*6)	Poor (*6)	Good (*7)	Poor (*6)	Good (*7)
Adhesion to screw feeder		Yes/No	Yes (*8)	No	No	Yes (*8)	No

*1: PPE-A: Percentage of PPE particles not passing 145 mesh = 83% by mass
*2: PPE-B: Percentage of PPE particles not passing 145 mesh = 66% by mass
*3: MAH: Maleic anhydride manufactured by Mitsubishi Chemical Corporation (amount of passing 6 mesh = 75% by mass)
*4: MAH: Maleic anhydride manufactured by ACROS ORGANICS Co. (Germany) (amount of passing 6 mesh = 99.7% by mass)
*5: Peroxide: Perhexa 25B-40 (peroxide content = 40% by mass)
(*6): Feed rate being unstable (formation of bridge causing unstable feed to fluctuate the number of revolutions of the feeder screw)
(*7): Capable of stable feed (no formation of bridge allowing constant feed to stabilize the number of revolutions of the feeder screw)
(*8): Ground MAH blocks firmly adhered to screw grooves

Example 18

The Present Invention

The maximum cylinder temperature of a co-rotating twin screw extruder was set at 320° C., the extruder having an L/D of 48 provided with one feed port in the upstream side and one feed port in the downstream side [ZSK70MC: manufactured by Coperion Corporation, having 12 temperature control blocks (L/D per block being 4) and an auto screen changer block; upstream feed port: the first block, downstream feed port: the sixth block, vent ports to remove volatiles by vacuum suction: the fifth block and the tenth block]. From the upstream feed port were fed through separate feeders to the extruder and melt-kneaded 30 parts by mass of polyphenylene ether [S201A] (hereinafter abbreviated just as PPE), 0.3 part by mass of PB-1, and 7 parts by mass of a styrene-ethylenebutylene-styrene block copolymer [Kraton G1651: manufactured by Kraton Polymers] (hereinafter abbreviated just as SEBS) as elastomer component. Subsequently, from the downstream feed port was fed and melt-kneaded for obtaining pellets, a blend which was obtained by blending 58 parts by mass of polyamide 6,6 [Vydyne 21ZLV: manufactured by Solutia Inc. (United States)] (hereinafter abbreviated just as PA66-A) and 5 parts by mass of polyamide 6 [UBE Nylon 1013B: manufactured by Ube Industries, Ltd.] (hereinafter abbreviated just as PA6) with 0.25 part by mass of carbon black (hereinafter abbreviated just as CB) as a pigment in a tumbler blender. At this time, the number of revolutions of the screw was 460 rpm and discharge rate was 1,000 kg/hr. Vacuum suction was performed at the fifth block and the tenth block to remove volatiles.
At this time, the diameter of the die holes was 4 mm and the number of the die holes was 50. The discharge per unit area of the opening of the die holes calculated from these values is 159 kg/cm².
The strand-shaped molten resin discharged from the die holes was cooled in the same manner as in Example 1. In order to verify the phenomenon of strand breakage occurring between the conveyor and the strand cutter, the number of strands broken in 5 minutes was checked. No strand was broken in this time period, and no adhered consecutive pellets were found in the cut pellets.
Further, the fluctuation during extrusion of a resin pressure gauge installed before the extruder screen changer and the state of surging of resin strands were checked. The resin pressure was kept within a range of 1.9 to 2.1 MPa, and the surging phenomenon was not observed. Thus, the extrusion state was good.
The above operation was continued for 1 hour. The first sample was collected at 10 minutes from the start of the operation. Then, sampling was performed every 5 minutes to obtain ten samples in total.
The collected pellets were molded into multipurpose test specimens according to ISO 294-1 at a molten resin temperature of 290° C. and a mold temperature of 90° C. using an injection molding machine (IS80EPN: manufactured by Toshiba Machine Co., Ltd.). The test specimens were left at rest at 23° C. for 48 hours in an aluminum moistureproof bag.
Next, test specimens obtained by cutting both ends of the multipurpose test specimens were used to measure Izod impact strength in the edgewise direction thereof according to ISO 179-1993. This evaluation was performed for all the samples collected, obtaining the results from ten samples per Example. The average of the ten determined values, as well as the maximum, the minimum, and the standard deviation which is an index of dispersion were shown from the results of the measurements of the ten samples.
In order to determine flowability, a spiral flow length was measured by using an injection machine (FE 120: manufactured by Nissei Plastic Industrial Co., Ltd.). The spiral part of the spiral-shaped molded article had a thickness of 1 mm and a width of 10 mm. The cylinder temperature was set at 290° C., and the molding temperature was set at 80° C. The injection molding was performed at the maximum injection speed and under three conditions of injection pressure of 51 MPa, 85 MPa and 118 MPa. Sampling of the molded articles was started from the 21st shot after the start of the molding for all the three conditions. Ten samples of the molded articles from the 21st shot to the 30th shot were collected. The spiral flow length was defined as the average of these 10 samples. Specifically, the spiral flow length was measured only for the two samples among ten samples in each Example which showed the maximum and the minimum of the Izod impact strength, respectively. In Table 4, the spiral flow length of the sample which showed the maximum Izod impact strength was described as “spiral flow length-1”, and the spiral flow length of the sample which showed the minimum Izod impact strength was described as “spiral flow length-2”.
These properties are shown in Table 4.

Examples 19 to 20 and Comparative Example 21

All experiments were performed in the same manner as in Example 18 except that the compositional ratio was changed to those shown in Table 4. The results are shown in Table 4. Note that the compositional ratio of each component in the compositions for Examples 19 to 20 and Comparative Example 21 is the same as in Example 18.

TABLE 4


				Comp.
Unit	Ex. 18	Ex. 19	Ex. 20	Ex. 21

PPE		Parts by mass	30	30	30
PB-1		Parts by mass	0.3
PB-2		Parts by mass		0.3
PB-3		Parts by mass			0.3
PB-5		Parts by mass				30
Other components (*9)		Parts by mass	70.25	70.25	70.25	70.25
MAH in total composition		% by mass	0.075	0.075	0.075	0.075
Izod impact strength	Maximum	J/m	268	310	302	298
	Minimum	J/m	155	246	268	104
	Average	J/m	210	276	284	176
	Standard	—	35	19	12	72
	deviation
Spiral flow length-1	51 MPa	cm	11.7	12.2	14.1	11.6
	85 MPa	cm	16.0	16.5	19.5	16.5
	118 MPa	cm	19.2	20.2	23.0	19.2
Spiral flow length-2	51 MPa	cm	13.0	14.4	14.2	13.7
	85 MPa	cm	17.3	19.5	19.7	18.9
	118 MPa	cm	20.8	23.5	23.3	22.4

(*9): SEBS: 7 parts by mass, PA66-A: 58 parts by mass, PA6: 5 parts by mass, CB: 0.25 parts by mass

Example 22

From the upstream feed port of the extruder which was set in the same manner as in Example 18 were fed to the extruder and melt-kneaded 35 parts by mass of PPE, 0.3 part by mass of PB-3 prepared in Example 15, 10 parts by mass of SEBS as an elastomer component, and 5 parts by mass of homo-polystyrene [Styron 685: manufactured by Dow Chemical Company (United States)] (hereinafter abbreviates just as PS) as a flowability improver. Subsequently, from the downstream feed port were fed and melt-kneaded for obtaining pellets, 50 parts by mass of polyamide 6,6 [Vydyne 48BX: manufactured by Solutia Inc. (United States)] (hereinafter abbreviated just as PA66-B) and 0.25 part by mass of CB as a pigment. At this time, the number of revolutions of the screw was 550 rpm and discharge rate was 1,000 kg/hr. Vacuum suction was performed at the fifth block and the tenth block to remove volatiles.
Note that SEBS was previously blended with PS, and PA66-B was previously blended with CB, in a tumbler blender. Moreover, the polyphenylene ether, PB-3, the blend of SEBS and PS, and the blend of PA-66 and CB were each fed to the extruder through a different feeder.
The pellets obtained were evaluated in the same manner as in Example 18. The results are shown in Table 5 together with the composition.
The spiral flow length was measured in the same manner as in Examples 18 to 20 and Comparative Example 21 except that the spiral part of the spiral-shaped molded article had a thickness of 2 mm; the cylinder temperature was set at 310° C. and the molding temperature was set at 80° C.; and the injection molding was performed under two conditions of injection pressure of 68 MPa and 118 MPa.

Comparative Example 23

All experiments were performed in the same manner as in Example 22 except that all of the polyphenylene ether to be used were further preblended with PB-3 in a Henschel mixer and fed through a separate feeder. The results of the evaluations are shown in Table 5.

TABLE 5


Unit	Ex. 22	Comp. Ex. 23

PPE		Parts by	35	35 (*10)
		mass
PB-3		Parts by	0.2	0.2 (*10)
		mass
Other components		Parts by	65.25	65.25
(*11)		mass
MAH in total		% by mass	0.050	0.050
composition
Izod impact strength	Maximum	J/m	258	268
	Minimum	J/m	240	202
	Average	J/m	249	232
	Standard	—	6	21
	deviation
Spiral flow length-1	68 MPa	cm	43.5	40.8
	118 MPa	cm	58.7	54.8
Spiral flow length-2	68 MPa	cm	44.1	43.2
	118 MPa	cm	59.3	58.1

(*10): PPE and PB-3 were previously preblended again using a Henschel mixer.
(*11): SEBS: 10 parts by mass PS: 5 parts by mass, PA66-B: 50 parts by mass, CB: 0.25 parts by mass

Example 24

The Present Invention

The maximum cylinder temperature of a co-rotating twin screw extruder was set at 320° C., the extruder having an L/D of 48 provided with one feed port in the upstream side and two feed ports in the downstream side [ZSK70MC: manufactured by Coperion Corporation, having 12 temperature control blocks (L/D per block being 4) and an auto screen changer block; upstream feed port: the first block, downstream feed ports: the sixth block and the eighth block, vent ports to remove volatiles by vacuum suction: the fifth block and the tenth block]. From the upstream feed port were fed separately to the extruder and melt-kneaded 21 parts by mass of polyphenylene ether [S201A: manufactured by Asahi Kasei Chemicals Corporation], 0.06 part by mass of granular maleic anhydride manufactured by ACROS ORGANICS (Germany), 4.5 parts by mass of a styrene-ethylenebutylene-styrene block copolymer [Kraton G1651: manufactured by Kraton Polymers] as elastomer component, and 4.5 parts by mass of homo-polystyrene [Stayron 685: manufactured by Dow Chemical Company (United States)]. Subsequently, from the downstream feed port installed on the sixth block was fed a dry blend which was obtained by dry-blending 30 parts by mass of polyamide 6,6 [Vydyne 48BX: manufactured by Solutia Inc. (United States)] (hereinafter abbreviated just as PA66) with 0.25 part by mass of carbon black as a pigment in a tumbler blender, and from the downstream feed port installed on the eighth block were fed 30 parts by mass of glass fiber [ECS03T-747 manufactured by Nippon Electric Glass Co., Ltd] and 10 parts by mass of aluminum diethylphosphinate [Exolit OP930 manufactured by Clariant Japan Co.] as a flame retardant. Then, these materials were melt-kneaded. At this time, the number of revolutions of the screw was 550 rpm, and the discharge rate was 1,000 kg/hr. The diameter of the die holes was 4 mm and the number of the die holes was 50. The discharge per unit area of the opening of the die holes was 159 kg/cm².
The strand-shaped molten resin discharged from the die holes was cooled in the same manner as in Example 1.
In order to verify the phenomenon of strand breakage occurring between the conveyor and the strand cutter, the number of strands broken in five minutes was checked. No strand was broken in this time period.
Further, the amount of adhered consecutive pellets included in the cut pellets was measured, but no adhered consecutive pellets were found.

Comparative Example 25

All experiments were performed in the same manner as in Example 24 except that the strands were cooled with three water spraying apparatuses in total installed at positions ranging from 1.2 m apart from the die holes (a position downstream by 18% of the total length of the conveying part of the conveyor) to 1.8 m apart from the die holes (a position downstream by 28% of the total length of the conveying part of the conveyor).
Strand breakage occurred very frequently. All of the 50 strands were broken after five minutes, which made it impossible to continue the extrusion.

INDUSTRIAL APPLICABILITY

The resin composition obtained by using the production method of the present invention can be used for various applications through injection molding, extrusion, and the like. Specifically, these applications include housings for various machines and electronic equipment such as computers; vehicle interior and exterior parts (such as fenders, back doors, hoods, side steps, mirror shells, front grilles, headlight housings, rear spoilers, side spoilers, dashboards, and blower wheels) and components in the engine room (such as relay blocks, connectors, light sockets, and battery covers) for passenger cars, pickup trucks, tractors and the like; impellers for various electric appliances, wet area components; and the like.

Claims

1. A method for producing a resin strand comprising the steps of:

melt-kneading a resin composition in an extruder;

extruding a strand-shaped molten resin onto a conveyor; and

cooling the resin strand with cooling water;

wherein the conveyed strand-shaped molten resin is brought into initial contact with the cooling water at a position downstream ranging from 20% to 70% of the total length of the conveying part of the conveyor.

2. The method for producing a resin strand according to claim 1, wherein the cooling water is sprayed water.

3. The method for producing a resin strand according to claim 1, wherein the cooling water has a temperature of 5° C. or above and 50° C. or below.

4. The method for producing a resin strand according to claim 1, wherein the length from the position at which the conveyed strand-shaped molten resin is brought into initial contact with the cooling water to an extruder die hole is 1.5 m or more and 4.5 m or less.

5. The method for producing a resin strand according to claim 1, wherein a discharge per unit area of the opening of an extruder die hole is from 80 kg/cm²to 200 kg/cm².

6. The method for producing a resin strand according to claim 1, wherein the strand just before cutting has a temperature ranging from 100° C. to 150° C.

7. A pellet obtained by cutting a strand produced by the method according to claim 1.

8. The pellet according to claim 7, wherein the percentage of adhered consecutive pellets is less than 2% by mass of the total pellet.

9. The method for producing a resin strand according to claim 1, wherein the resin composition comprises one or more resins selected from the group of polyarylene sulfide, polyetheretherketone, polysulfone, polyethersulfone, polyamide, polyester, liquid crystal polymers, polyarylate, polycarbonate, polyphenylene ether, and polyetherimide.

10. The method for producing a resin strand according to claim 1, wherein the resin composition is a mixture comprising two or more resins selected from the group of polyarylene sulfide, polyetheretherketone, polyamide, polyester, liquid crystal polymers, polyphenylene ether, and polyetherimide, the mixture comprising both a crystalline resin and an amorphous resin; and the crystalline resin forming a continuous phase and the amorphous resin forming a disperse phase.

11. The method for producing a resin strand according to claim 10, wherein the resin composition comprises at least polyamide and polyphenylene ether.

12. The method for producing a resin strand according to claim 11, wherein the resin composition comprises polyamide, polyphenylene ether, and one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form.

13. The method for producing a resin strand according to claim 12, wherein the polyphenylene ether is a powdery polyphenylene ether comprising 60% by mass or more of fine particles not passing a 145 mesh (106 μm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 65 μm.

14. The method for producing a resin strand according to claim 12, wherein the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form comprise 80% by mass or more of particles passing a 6 mesh (3.1 mm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 1.4 mm.

15. The method for producing a resin strand according to claim 12, comprising the steps of:

forming a preblend of 100 parts by mass of a powdery polyphenylene ether and 50 to 200 parts by mass of one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form; and then

feeding the preblend to an extruder through a feeder different from a feeder used for feeding the remaining polyphenylene ether.

16. The method for producing a resin strand according to claim 15, wherein the amount of the powdery polyphenylene ether incorporated into the preblend is less than 5% by mass of the amount of all the polyphenylene ether used in the resin composition.

17. The method for producing a resin strand according to claim 12, wherein the amount of the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form is from 0.01 to 1 part by mass based on 100 parts by mass of all the polyphenylene ether.

18. The method for producing a resin strand according to claim 15, further comprising a peroxide in the preblend.

19. The method for producing a resin strand according to claim 1, wherein the resin composition comprises 5 to 50% by mass of an inorganic filler based on 100% by mass of the resin composition.

20. The method for producing a resin strand according to claim 19, wherein the inorganic filler is one or more selected from the group of glass fiber, glass flake, talc, wollastonite, mica, titanium dioxide, alumina, silica, zinc oxide, and zinc sulfide.

21. The method for producing a resin strand according to claim 1, further comprising an electrically conductive carbon filler.

22. The method for producing a resin strand according to claim 21, wherein the electrically conductive carbon filler is at least one selected from the group of electrically conductive carbon black, carbon fibril, and graphite.

23. A preblend comprising 100 parts by mass of a powdery polyphenylene ether and 50-200 parts by mass of one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form.

24. The preblend according to claim 23, wherein the one or more compounds selected from the group of maleic acid, citric acid, fumaric acid, and an anhydride thereof in powder or granule form are powdery or granular compounds comprising 80% by mass or more of particles passing a 6 mesh (3.1 mm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 1.4 mm.

25. The preblend according to claim 23, wherein the powdery polyphenylene ether is a powdery polyphenylene ether comprising 80% by mass or more of fine particles not passing a 145 mesh (106 μm opening) woven wire cloth (according to JIS G3555-1983) made of stainless steel wire having a diameter of 65 μm.