JP2006175787A - Manufacturing method for continuous fiber-reinforced thermoplastic resin pellet, and continuous fiber-reinforced thermoplastic resin pellet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for obtaining a core-shell type continuous-fiber pellet which has little fuzz and which is excellent in handleability, and the core-shell type continuous-fiber pellet which has little fuzz and which is excellent in handleability. <P>SOLUTION: This manufacturing method is used for manufacturing the core-shell type continuous fiber-reinforced thermoplastic resin pellet wherein a reinforced fiber bundle [A] or a thermoplastic polymer-impregnated reinforced fiber bundle [A<SB>C</SB>] is coated with a thermoplastic resin [B]. In the fiber bundle [A<SB>C</SB>], the fiber bundle [A] is impregnated with a thermoplastic polymer [C] wherein a melt viscosity based on the JIS K7199 standard [melting temperature: softening temperature (or melting point) +30°C, and shear rate: 10<SP>3</SP><SB>s</SB><SP>-1</SP>] is in the range of 0.1-10 Pa s. Characteristically, the molten thermoplastic resin [B] is imparted to the fiber bundle [A] or [A<SB>C</SB>]; the fiber bundle [A] or [A<SB>C</SB>] is coated with the resin [B]; and the fiber bundle [A] or [A<SB>C</SB>] is cut to a length of 3-20 mm after heat is removed on condition of 5-50 kJ/(kg s). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is not only excellent in various mechanical properties and appearance of the molded product, but also has very few cracks in the sheath portion of the core-sheath type long fiber pellet, and therefore the long fiber in which the fluff generation amount of the reinforcing fiber is very small Production method of reinforced thermoplastic resin pellets and long fiber reinforcement with excellent handleability, without generation of fiber fluff on the surface of the molded product, and without causing bridging of the fluff in the hopper of the molding machine during molding It relates to thermoplastic resin pellets.

  A technique for combining reinforced fibers such as glass fibers and carbon fibers for the purpose of improving the mechanical properties of thermoplastic resins is known. The fiber length of the reinforcing fiber in the molded product greatly contributes to the improvement of the mechanical properties. In order to lengthen the fiber length in a molded article, what is called a long fiber pellet which lengthened the reinforcing fiber in a pellet is calculated | required.

The long fiber pellets include a resin impregnated pellet obtained by impregnating a reinforcing fiber bundle with resin using a pultrusion technique, and a core obtained by coating a reinforcing fiber bundle with a thermoplastic resin using a wire coating technique. The core-sheath type long fiber pellet is roughly divided into sheath-type pellets, and has an advantage of excellent productivity. Moreover, when the core-sheath type long fiber pellet was molded, there was a problem that the dispersion of the reinforcing fiber in the molded product was bad, but by applying and impregnating the low-viscosity thermoplastic polymer to the reinforcing fiber bundle, There has been a technique in which the reinforcing fibers are excellently dispersed in the molded product, and the mechanical properties and appearance of the molded product are excellent. (See Patent Document 1)
Japanese Patent Laid-Open No. 10-138379

  Core-sheath type long fiber pellets have a problem that they have more fuzz than ordinary pellets and are inferior in handleability. Accordingly, an object of the present invention is to provide a method for obtaining a core-sheath type long fiber pellet with less fluff and excellent handleability, and a core-sheath type long fiber pellet with less fuzz and excellent handleability.

The present inventors examined the cause of the core-sheath-type long fiber pellet according to the conventional method with a lot of fluff, based on the idea that the sheath was damaged. As a result of finding that there is a cause in the cooling process during the manufacturing process and setting the cooling condition to a specific condition, it has been found that a manufacturing method can be provided with less damage to the sheath and less fuzz as compared with the conventional method. That is, the manufacturing method used in the present invention is:
(1) The reinforcing fiber bundle [A] or the reinforcing fiber bundle [A] has a melt viscosity based on JIS K7199 standard [melting temperature: softening temperature (or melting point) + 30 ° C., shear rate: 10 ³ s ⁻¹ ]. A core-sheath type in which a thermoplastic resin [B] is coated on a thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] impregnated with a thermoplastic polymer [C] in the range of 0.1 to 10 Pa · s. A method for producing long fiber pellets, in which [A] or [A _C ] is coated with a molten thermoplastic resin [B], coated, and heat is removed under conditions of 5 to 50 kJ / (kg · s). Then, it cut | disconnects to the length of the range of 3-20 mm, The manufacturing method of the long fiber reinforced thermoplastic resin pellet characterized by the above-mentioned.

  (2) The surface temperature of the thermoplastic resin [B] at the time of cutting is 0 to 100 ° C. higher than the deflection temperature under load of the thermoplastic resin [B] (JIS K 7191 standard, load: 1.80 MPa) (1) The manufacturing method of the long fiber reinforced thermoplastic resin pellet of description.

  (3) In the cross section of the pellet, the application amount of the thermoplastic resin [B] is set so that the average thickness of the coated portion with the thermoplastic resin [B] is in the range of 15 to 40% of the average diameter (1) to ( The manufacturing method of the long fiber reinforced thermoplastic resin pellet in any one of 2).

  (4) The method for producing a long fiber reinforced thermoplastic resin pellet according to any one of (1) to (3), wherein the reinforcing fiber bundle [A] is a carbon fiber.

  (5) When the reinforcing fiber bundle [A] is coated with the thermoplastic resin [B], the weight of the thermoplastic resin [B] to be applied is unit length with respect to the weight per unit length of the reinforcing fiber bundle [A]. The manufacturing method of the long fiber reinforced thermoplastic resin pellet in any one of (1)-(4) which is 1.5-19 times amount per thickness.

(6) When the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] is coated with the thermoplastic resin [B], the unit length of the reinforcing fiber bundle [A] in the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] Of the thermoplastic resin [B] so that the total weight of the thermoplastic resin [B] and the thermoplastic polymer [C] is 1.5 to 19 times the unit length with respect to the weight per unit thickness. The manufacturing method of the long fiber reinforced thermoplastic resin pellet in any one of (1)-(4) which sets the provision amount.

  (7) The thermoplastic polymer [C] is a thermoplastic polymer obtained by condensation of phenol or a substituent derivative of phenol with an aliphatic hydrocarbon and having a weight average molecular weight in the range of 300 to 1,000 (1 ) To (4) or a method for producing a long fiber reinforced thermoplastic resin pellet according to any one of (6).

(8) In the step of cooling the covering (gut) with the thermoplastic resin [B] of the reinforcing fiber bundle [A] or the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ], the covering (gut) is used as a refrigerant. The manufacturing method of the long fiber reinforced thermoplastic resin pellet in any one of (1)-(7) which is made to contact and cools the upper surface of the box passed through.

(9) In the step of cooling the covering (gut) with the thermoplastic resin [B] of the reinforcing fiber bundle [A] or the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ], the covering (gut) is cooled with cold air The method for producing a long fiber reinforced thermoplastic resin pellet according to any one of (1) to (7), wherein the pellet is cooled by heating.

(10) The reinforcing fiber bundle [A] or the reinforcing fiber bundle [A] has a melt viscosity based on JIS K7199 standard [melting temperature: softening temperature (or melting point) + 30 ° C., shear rate: 10 ³ s ⁻¹ ]. A core-sheath in which the periphery of a thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] impregnated with a thermoplastic polymer [C] in the range of 0.1 to 10 Pa · s is coated with a thermoplastic resin [B] A long fiber pellet having a length in the range of 3 to 20 mm of the mold, wherein the fluff content is 0 to 50 ppm with respect to the whole pellet.

(11) A length in the range of 3 to 20 mm of the core-sheath type in which the periphery of the reinforcing fiber bundle [A] or the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] is covered with the thermoplastic resin [B]. A long fiber reinforced thermoplastic resin pellet having a content of 0 to 1% of a pellet having a crack in the sheath portion of the pellet.

  (12) Deflection temperature (JIS K 7191 standard, load: 1.80 MPa) of the thermoplastic resin [B] is in the range of 25 ° C. to 300 ° C. (10) or (11) Fiber reinforced thermoplastic resin pellets.

  (13) The long fiber reinforced thermoplasticity according to any one of (10) to (12), wherein the average thickness of the coated portion of the thermoplastic resin [B] is in the range of 5 to 40% of the average diameter in the cross section of the pellet. Resin pellets.

  (14) The long fiber reinforced thermoplastic resin pellet according to any one of (10) to (13), wherein the reinforcing fiber bundle [A] is a carbon fiber.

  (15) The long fiber reinforced thermoplastic resin pellet according to any one of (10) to (13), wherein the content of the reinforcing fiber is 5 to 40% by weight.

  (16) The thermoplastic polymer [C] is a thermoplastic polymer obtained by condensation of phenol or a substituent derivative of phenol with an aliphatic hydrocarbon and having a weight average molecular weight of 300 to 1,000 ( The long fiber reinforced thermoplastic resin pellet according to any one of 10) to (15).

  According to the present invention, it is possible to obtain a core-sheath-type long fiber pellet with very little occurrence of fluff of reinforcing fibers, and as a result, there is no trouble at the time of molding, and a molded product having good appearance and excellent mechanical properties. Can be obtained.

The present invention will be described in further detail below. The production method of the core-sheath type long fiber pellet of the present invention includes the reinforcing fiber bundle [A] or the reinforcing fiber bundle [A] according to JIS K7199 standard [melting temperature: softening temperature (or melting point) + 30 ° C., shear rate] : Thermoplastic resin impregnated reinforcing fiber bundle [A _C ] impregnated with thermoplastic polymer [C] having a melt viscosity in the range of 0.1 to 10 Pa · s based on 10 ³ s ⁻¹ ]. B] is a method for producing core-sheath type long fiber pellets coated with [A] or [A _C ] and coated with a molten thermoplastic resin [B], and coated with 5 to 50 kJ After the heat removal under the condition of / (kg · s), it is cut to a length in the range of 3 to 20 mm.

  The reinforcing fiber bundle [A] used here includes carbon fiber, glass fiber, metal fiber, roving such as metal-coated fiber obtained by coating carbon fiber or glass fiber with a metal such as nickel or copper, and continuous fiber such as yarn. Although it can be used, it is not necessarily limited to this. In addition, these fibers may be treated with a known surface treatment agent (bundling agent). As a preferable reinforcing fiber, carbon fiber is preferable from the balance of mechanical properties and lightness of the molded product.

It is also possible to use a thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] instead of the reinforcing fiber bundle [A]. The thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] has a melt viscosity based on the reinforcing fiber bundle [A] based on JIS K7199 standard [melting temperature: softening temperature (or melting point) + 30 ° C., shear rate: 10 ³ s ⁻¹ ]. Is produced by impregnating a thermoplastic polymer [C] having a viscosity of 0.1 to 10 Pa · s. The impregnation of the reinforcing fiber bundle [A] with the thermoplastic polymer [C] may be set before the step of coating the thermoplastic resin [B] in the same line or may be reinforced in advance by another apparatus. A fiber bundle [A] impregnated with a thermoplastic polymer [C] may be prepared and used.

  The thermoplastic resin [B] can be selected from thermoplastic resins such as polyamide resin, polyester resin, liquid crystalline polyester resin, polycarbonate resin, polyolefin resin, polyphenylene sulfide resin, polyphenylene ether resin, and ABS resin. It is not limited. Preferred resins include polyamide resin, polyester resin, polycarbonate resin, ABS resin and the like from the viewpoint of the strength of the molded product and moldability.

In such a production method of a reinforcing fiber bundle [A] or a thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] coated with a thermoplastic resin [B] to form a core-sheath type long fiber pellet, The method of coating the plastic resin [B] is not particularly limited, but the reinforcing fiber bundle [A] continuous in the coating die for coating the electric wire attached to the tip of the extruder, or the thermoplastic polymer-impregnated reinforcing fiber It is preferable to extrusion coat the thermoplastic resin [B] through the bundle [A _C ]. Hereinafter, a covering made of a wire-shaped thermoplastic resin after being coated with the thermoplastic resin [B] and before cutting is referred to as “gut”.

The gut obtained by coating the above-mentioned reinforcing fiber bundle [A] or the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] with the thermosetting resin [B] Cut to a length of 20 mm to form pellets. The cutting method is not particularly limited, and for example, it can be cut with a strand cutter.

  In the method for producing a long fiber reinforced thermoplastic resin pellet of the present invention, the cooling condition after applying the thermoplastic resin [B] and coating needs to be 5 to 50 kJ / (kg · s). When the heat removal condition is less than 5 kJ / (kg · s), the coating resin is cut at a high temperature. Therefore, when cutting the gut, the pellets after cutting with the high-temperature resin are put on the cutter blade. It adheres and the pellet is cut twice. If the cutting occurs twice, fluffing may occur. On the other hand, when the heat removal condition is higher than 50 kJ / (kg · s), the coating resin becomes too cold and hard, and when the gut is cut, the coated portion is broken and fluff is generated.

  The surface temperature of the covering resin of the gut at the time of cutting is preferably 0 to 100 ° C. higher than the deflection temperature under load of the thermoplastic resin measured by the method defined in JIS K 7191 standard (load: 1.80 MPa). . By cutting in this temperature range, it is more effective that the coated part breaks and fluff is generated when cutting the gut, or that the pellet attached to the cutter is cut twice when the gut is cut. This is because it can be prevented.

  The method for cooling the gut is not particularly limited, and any technique may be used. Preferably, the gut is brought into contact with the upper surface of the box through which the refrigerant is passed, and the gut is blown on the gut. And a cooling method and a combination thereof. These cooling methods are advantageous in that control of heat removal conditions is easy and dry pellets can be obtained.

Further, the core-sheath type long fiber pellet of the present invention is a reinforcing fiber bundle [A] or JIS K7199 standard [melting temperature: softening temperature (or melting point) + 30 ° C., shear rate: The thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] impregnated with the thermoplastic polymer [C] having a melt viscosity in the range of 0.1 to 10 Pa · s based on 10 ³ s ⁻¹ ] is surrounded by a thermoplastic resin. A core-sheath type long fiber pellet with a length in the range of 3 to 20 mm coated with [B], wherein the fluff content is 0 to 50 ppm based on the whole pellet. Since the fluff content does not exceed 50 ppm with respect to the whole pellet, bridging of the fluff does not occur in the hopper part of the molding machine at the time of molding, and the handleability at the time of molding is excellent. A molded product with good appearance without fiber fluff is obtained. Further, the core-sheath type long fiber pellet of the present invention is a core having a form in which the periphery of the reinforcing fiber bundle [A] or the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] is covered with the thermoplastic resin [B]. -It is a long fiber pellet of the length of the range of 3-20 mm of a sheath type, Comprising: The content rate of the pellet which has a crack in the sheath part of a pellet is 0 to 1%, It is characterized by the above-mentioned. Since the content rate of the pellet having a crack in the sheath portion of the pellet is 0 to 1%, the sheath is damaged by vibration or external force during transportation and the occurrence of fluff is prevented. There is a unique advantage that the small advantage can be prevented from being lowered by transportation or the like. These features can be obtained by using the manufacturing method of the present invention.

  Moreover, in the cross section of the pellet obtained, it is preferable that the average thickness of the portion coated with the thermoplastic resin [B] is in the range of 15 to 40% of the average diameter, and the thermoplastic resin [B] is within this range. It is preferable to set the adhesion amount of. The amount of adhesion is adjusted by the amount of thermoplastic resin [B] supplied and the line speed. In general, increasing the average thickness of the coating resin leads to a relative decrease in the amount of reinforcing fibers, and therefore the effect of improving the mechanical properties of the obtained molded product tends to be reduced. On the other hand, if the average thickness of the coating resin is reduced, the effect of improving the mechanical properties of the molded product obtained is improved, but the pellets are easily broken during gut cutting. From this viewpoint, it is preferable to set and adjust the adhesion amount of the thermoplastic resin [B] so as to be in the above range.

  The content of the reinforcing fiber is not particularly limited, but the content of the reinforcing fiber is preferably 5 to 40% by weight because the obtained molded article has high mechanical properties and a high degree of freedom in setting conditions during molding. .

In order to obtain pellets having such a fiber content, when the reinforcing fiber bundle [A] is coated with the thermoplastic resin [B], the heat applied to the weight per unit length of the reinforcing fiber bundle [A]. The weight of the plastic resin [B] may be set to 1.5 to 19 times the unit length, and the applied amount may be adjusted. When the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] is coated with the thermoplastic resin [B], the unit of the reinforcing fiber bundle [A] in the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ]. The thermoplastic resin [B] so that the total weight of the thermoplastic resin [B] and the thermoplastic polymer [C] is 1.5 to 19 times the weight per unit with respect to the weight per length. What is necessary is just to set and adjust the provision amount.

  Next, the resin material used in the present invention, that is, the thermoplastic resin [B] and the thermoplastic polymer [C] will be described in detail.

  As described above, the thermoplastic resin [B] can be selected from thermoplastic resins such as polyamide resin, polyester resin, liquid crystalline polyester resin, polycarbonate resin, polyolefin resin, polyphenylene sulfide resin, polyphenylene ether resin, and ABS resin. However, the present invention is not necessarily limited to this. Preferred resins include polyamide resin, polyester resin, polycarbonate resin, ABS resin and the like from the viewpoint of the strength of the molded product and moldability.

  These thermoplastic resins may be used alone, as a mixture, or as a copolymer. In the case of a mixture, a compatibilizer may be used in combination. Further, brominated flame retardants, silicon-based flame retardants, red phosphorus and the like may be added as flame retardants. Furthermore, you may mix | blend phosphate ester and carbon black.

  Furthermore, various additives may be added for the purpose of obtaining good molded article characteristics and mechanical characteristics. Additives include calcium carbonate, silica, kaolin, clay, titanium oxide, barium sulfate, zinc oxide, amorphous fillers such as aluminum hydroxide, alumina, magnesium hydroxide, plate shapes such as talc, mica, or glass flakes Filler, wollastonite, potassium titanate, basic magnesium sulfate, sepiolite, zonotlite, acicular filler such as aluminum borate, conductive filler such as metal powder, metal flake, and carbon black are used. These additives may be used singly or in combination, or may be used as a single or a combination of those whose surfaces are subjected to carbon coating or silane coupling treatment.

Further, as described above, it is preferable to use the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] instead of the reinforcing fiber bundle [A] because a material with good moldability can be obtained. The thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] is melted on the reinforcing fiber bundle [A] based on JIS K7199 standard [melting temperature: softening temperature (or melting point) + 30 ° C., shear rate: 10 ³ s ⁻¹ ]. It is obtained by impregnating a thermoplastic polymer [C] having a viscosity of 0.1 to 10 Pa · s.

  In the pellet obtained by coating this with the thermoplastic resin [B], the thermoplastic polymer [C] is present between the fibers of the reinforcing fiber bundle [A], so that the thermoplastic resin [C] is introduced into the thermoplastic resin during molding. The dispersion of the reinforcing fibers is improved, and a molded product having excellent mechanical properties and appearance can be obtained.

  Preferable thermoplastic polymer [C] includes a thermoplastic polymer obtained by condensation of phenol or a substituent derivative of phenol with an aliphatic hydrocarbon. The condensation reaction can be carried out in the presence of a strong acid or Lewis acid. As the substituent derivative of phenol, one having 1 to 3 substituents selected from an alkyl group, a halogen atom, and a hydroxyl group on the benzene nucleus of phenol is preferably used. Specific examples thereof include cresol, xylenol, ethylphenol, butylphenol, t-butylphenol, nonylphenol, 3,4,5-trimethylphenol, chlorophenol, bromophenol, chlorocresol, hydroquinone, resorcinol, orcinol and the like. Particularly preferred are phenol and cresol. The aliphatic hydrocarbon is an aliphatic hydrocarbon having two double bonds and may have a cyclic structure. Examples that do not have a cyclic structure include butadiene, isoprene, pentadiene, hexadiene, and the like. Examples having a cyclic structure include monocyclic compounds such as cyclohexadiene, vinylcyclohexene, cycloheptadiene, cyclooctadiene, and monocyclic monoterpenes represented by the molecular formula of C10H16 (dipentene, limonene, terpinolene, terpinene). And bicyclic compounds such as 2,5-norbornadiene, tetrahydroindene, and bicyclic sesquiterpenes represented by the molecular formula of C15H24 (such as kadinene, serene, and caryophyllene). And dicyclopentadiene. Among these, a monocyclic monoterpene represented by a molecular formula of C10H16 is particularly preferable. More preferable thermoplastic polymer [C] is a condensate of phenol or a substituent derivative of phenol with a monocyclic monoterpene represented by the molecular formula of C10H16, and has a weight average molecular weight in the range of 300 to 1,000. It is a thermoplastic polymer.

  In addition, the long fiber reinforced thermoplastic resin pellets obtained by the production method of the present invention include various thermoplastic resins such as polyamide resin, polyester resin, liquid crystalline polyester resin, polycarbonate resin, polyolefin resin, polyphenylene sulfide resin, polyphenylene ether. By blending a resin, a thermoplastic resin such as an ABS resin, or a modified product or elastomer thereof, the performance as a molding resin pellet can be further improved.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to this.

  Evaluation items of thermoplastic resins and thermoplastic polymers used in Examples and Comparative Examples, and methods thereof, and evaluation items and methods of long fiber reinforced thermoplastic resin pellets obtained in Examples and Comparative Examples are as follows. Show.

(A) Deflection temperature under load of thermoplastic resin Conditions under which a load deflection temperature test piece was prepared Injection molding machine: M50AII-SJ manufactured by Meiki Seisakusho Co., Ltd.
Mold: Test piece Set mold Cylinder temperature: 250 ℃
Mold temperature: 80 ℃
Screw back pressure: 5kgf / cm ² G
Screw rotation speed: 100rpm
Under the above conditions, a test piece having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm was prepared and subjected to measurement. The deflection temperature under load is measured in accordance with JIS K 7191 standard under the conditions of load: 1.80 MPa and rate of temperature increase of 2 ° C./min, and the temperature at which the deflection of the test piece becomes 0.34 mm is deflection under load. It was temperature.

(B) Melt viscosity of thermoplastic polymer It evaluated by the measuring method based on JISK7199 specification. A pulverized thermoplastic polymer is placed in a cylinder in a capillary rheometer (capillary nozzle diameter 0.5 mm), preheated at 180 ° C. (softening temperature + 30 ° C.) for 5 minutes, and then melt viscosity at a shear rate of 10 ³ s ^−1. Was measured.

(C) Measurement of heat removal rate in cooling process Gut surface temperature T1 [° C] immediately after exiting the nozzle of the extruder, and Gut surface temperature T2 [° C] immediately before passing through the cooling process and entering the strand cutter The heat removal rate was calculated from the following formula.

Heat removal rate [kJ / (kg · s)] = Cp × (T1-T2) / t
Here, Cp and t are as follows.

Cp: specific heat capacity of coating resin [kJ / (kg · ° C.)]
t: Time required for gut to leave the extruder nozzle and enter the strand cutter [s] (= distance between nozzle outlet and cutter inlet / gut take-up speed)
(D) Measurement of fluff content in pellets and cracked pellet content About 200 g of pellets were sampled 5 times every hour, and the exact weight was measured. Thereafter, the amount of fluff contained in the collected pellets and the weight of the cracked pellets were measured, and each was divided by the total weight to obtain the content.

  Next, the raw materials used in Examples and Comparative Examples are shown below.

Reinforcing fiber: "Torayca" T700SC-12K-50C manufactured by Toray Industries, Inc.
Single fiber diameter 7μm
Thermoplastic resin I: Non-reinforced polyamide 6 resin
Deflection temperature under load: 65 ° C., specific heat: 1.9
Thermoplastic resin II: Filler reinforced polyamide 6 resin (containing 15% wollastonite),
Deflection temperature under load: 101 ° C., specific heat: 1.7
Thermoplastic polymer: Terpene phenol resin K140 manufactured by Yasuhara Chemical Co., Ltd.
Softening temperature 150 ° C, weight average molecular weight 790
Melt viscosity 3.5 Pa · s (180 ° C., shear rate 10 ³ s ⁻¹ )
The outline of the long fiber pellet manufacturing apparatus used for the Example and the comparative example is shown in FIG.

[Example 1]
A terpene phenol resin (K140) was heated and melted on a roll heated to 200 ° C. to form a liquid film having a constant thickness. A continuous carbon fiber bundle was passed over the roll at a speed of 15 m / min while being in contact therewith, and a certain amount of terpene phenol resin was adhered per unit length of the carbon fiber bundle.

  The carbon fiber bundle to which the terpene phenol resin is adhered is alternately passed through the top and bottom of 10 rolls arranged on a straight line that is heated to 210 ° C. and freely rotated by a bearing, and the terpene phenol resin is passed through the carbon fiber bundle. And a continuous composite made of carbon fiber and terpene phenol resin was formed.

  This continuous composite was passed through a coating die for electric wire coating installed at the tip of a single screw extruder having a diameter of 50 mm, and unreinforced polyamide 6 resin (heated) melted at 240 ° C. from the extruder into the die. The plastic resin I) was discharged, and the periphery of the composite was coated so that the carbon fiber content was 30% by weight to form a wire-like gut. The gut was cooled while being brought into contact with the top of a box-shaped cooling device in which cooling water was circulated, and then cut into a length of 7 mm with a strand cutter to obtain a core-sheath type long fiber pellet.

  The heat removal rate in the cooling step was 10.7 kJ / (kg · s), and the surface temperature of the gut at the time of cutting was 125 ° C.

[Example 2]
The same procedure as in Example 1 was conducted except that the gut take-up speed was changed to 27 m / min.

  The heat removal rate in the cooling step was 17.4 kJ / (kg · s), and the surface temperature of the gut at the time of cutting was 136 ° C.

[Example 3]
The same procedure as in Example 1 was performed except that the gut cooling device was changed to a device that cooled by blowing cold air. The heat removal rate in the cooling step was 8.3 kJ / (kg · s), and the surface temperature of the gut at the time of cutting was 150 ° C.

[Example 4]
The thermoplastic resin used was a filler reinforced polyamide 6 resin (thermoplastic resin II), melted at 250 ° C., and coated with the resin so that the carbon fiber content was 25% by weight. The same was done. The heat removal rate in the cooling step was 9.9 kJ / (kg · s), and the surface temperature of the gut at the time of cutting was 128 ° C.

[Comparative Example 1]
The gut cooling device was changed to a device that cools the gut in direct contact with cooling water in the water tank, and the same procedure as in Example 1 was performed except that the gut take-up speed was changed to 27 m / min.

  The heat removal rate in the cooling step was 61.2 kJ / (kg · s), and the surface temperature of the gut at the time of cutting was 56 ° C.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that all the gut cooling devices were excluded and the gut was not forcibly cooled.

  The heat removal rate in the cooling step was 4.0 kJ / (kg · s), and the surface temperature of the gut at the time of cutting was 195 ° C.

  From Table 1, the long fiber reinforced thermoplastic resin pellets (Examples 1 to 4) produced by the method for producing the long fiber reinforced thermoplastic resin pellets of the present invention are all contained in the fluff and sheath part of the broken pellet. 0 pellets were obtained (overall evaluation: ◯).

  On the other hand, a high heat removal rate (Comparative Example 1) and a low heat removal rate (Comparative Example 2) increase the content of pellets with cracked fluff and sheath portions. (Overall evaluation: x).

  By using the method for producing a long fiber reinforced thermoplastic resin pellet of the present invention, it is possible to obtain a core-sheath type long fiber pellet with very little generation of reinforcing fiber fluff, and as a result, there is no trouble during molding. , Molded products with good appearance and excellent mechanical properties can be obtained, and can be widely used in parts and casings of electrical and electronic equipment such as personal computers, OA equipment, AV equipment, home appliances, toy products, etc. The range is not limited to these.

It is the schematic of a core-sheath type | mold long fiber pellet manufacturing apparatus. 1 is a schematic view of a cooling device used in Example 1. FIG. 2 is a schematic view of a cooling device used in Comparative Example 1. FIG.

Explanation of symbols

1: Reinforcing fiber bundle (carbon fiber bundle is used in Examples and Comparative Examples)
2: Impregnated portion of thermoplastic polymer 3: Reinforcing fiber bundle impregnated with thermoplastic polymer 4: Extruder 5: Coating die for resin coating 6: Gut 7: Cooling device 8: Strand cutter (including gut take-up device) )
9: Core-sheath type long fiber pellet 10: Roller guide

Claims (16)

The melt viscosity based on JIS K7199 standard [melting temperature: softening temperature (or melting point) + 30 ° C., shear rate: 10 ³ s ⁻¹ ] is 0.1 on the reinforcing fiber bundle [A] or the reinforcing fiber bundle [A]. A core-sheath type long fiber pellet formed by coating a thermoplastic resin-impregnated reinforcing fiber bundle [A _C ] impregnated with a thermoplastic polymer [C] in the range of 10 to 10 Pa · s with a thermoplastic resin [B]. The melted thermoplastic resin [B] is applied to and coated on [A] or [A _C ], and the heat is removed under conditions of 5 to 50 kJ / (kg · s). A method for producing a long fiber reinforced thermoplastic resin pellet, characterized by cutting to a length in the range of -20 mm. The surface temperature of the thermoplastic resin [B] at the time of cutting is 0 to 100 ° C higher than the deflection temperature under load (JIS K 7191 standard, load: 1.80 MPa) of the thermoplastic resin [B]. A method for producing fiber-reinforced thermoplastic resin pellets. The amount of the thermoplastic resin [B] applied is set so that the average thickness of the portion covered with the thermoplastic resin [B] is in the range of 15 to 40% of the average diameter in the cross section of the pellet. The manufacturing method of the long fiber reinforced thermoplastic resin pellet of description. Reinforcing fiber bundle [A] is carbon fiber, The manufacturing method of the long fiber reinforced thermoplastic resin pellet in any one of Claims 1-3 characterized by the above-mentioned. In coating the reinforcing fiber bundle [A] with the thermoplastic resin [B], the weight of the thermoplastic resin [B] to be applied is 1 per unit length with respect to the weight per unit length of the reinforcing fiber bundle [A]. The method for producing a long fiber reinforced thermoplastic resin pellet according to any one of claims 1 to 4, wherein the amount is 5 to 19 times. In coating the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] with the thermoplastic resin [B], the unit length of the reinforcing fiber bundle [A] in the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] The applied amount of the thermoplastic resin [B] is adjusted so that the total weight of the thermoplastic resin [B] and the thermoplastic polymer [C] is 1.5 to 19 times the weight per unit length with respect to the weight. The manufacturing method of the long fiber reinforced thermoplastic resin pellet in any one of Claims 1-4 set. The thermoplastic polymer [C] is a thermoplastic polymer obtained by condensation of phenol or a phenol derivative and an aliphatic hydrocarbon, and having a weight average molecular weight in the range of 300 to 1,000. Or a method for producing a long fiber reinforced thermoplastic resin pellet according to any one of 6 and 6. In the cooling step of the covering (gut) of the reinforcing fiber bundle [A] or the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] with the thermoplastic resin [B], the covering (gut) was passed through a refrigerant. The manufacturing method of the long fiber reinforced thermoplastic resin pellet in any one of Claims 1-7 which are made to contact the upper surface of a box and it cools. In the step of cooling the covering (gut) with the thermoplastic resin [B] of the reinforcing fiber bundle [A] or the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ], the covering (gut) is cooled by cold air. The manufacturing method of the long fiber reinforced thermoplastic resin pellet in any one of Claims 1-7. The melt viscosity based on JIS K7199 standard [melting temperature: softening temperature (or melting point) + 30 ° C., shear rate: 10 ³ s ⁻¹ ] is 0.1 on the reinforcing fiber bundle [A] or the reinforcing fiber bundle [A]. A core-sheath type 3 in which the periphery of a thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] impregnated with a thermoplastic polymer [C] in the range of 10 Pa · s to 10 Pa · s is coated with a thermoplastic resin [B]. Long fiber pellets having a length in the range of ˜20 mm, and the fluff content is 0 to 50 ppm with respect to the whole pellets. The length of the reinforcing fiber bundle [A] or the length of the core-sheath type in the range of 3 to 20 mm in which the periphery of the thermoplastic polymer-impregnated reinforcing fiber bundle [A _C ] is covered with the thermoplastic resin [B]. A long fiber reinforced thermoplastic resin pellet, which is a fiber pellet, and the content of the pellet having a crack in the sheath portion of the pellet is 0 to 1%. The long fiber reinforced thermoplastic resin according to any one of claims 10 and 11, wherein the deflection temperature under load (JIS K 7191 standard, load: 1.80 MPa) of the thermoplastic resin [B] is in the range of 25 ° C to 300 ° C. pellet. The long fiber reinforced thermoplastic resin pellet according to any one of claims 10 to 12, wherein in the cross section of the pellet, the average thickness of the portion covered with the thermoplastic resin [B] is in the range of 5 to 40% of the average diameter. The reinforcing fiber bundle [A] is a carbon fiber, and the long fiber reinforced thermoplastic resin pellet according to any one of claims 10 to 13. The long fiber reinforced thermoplastic resin pellet according to any one of claims 10 to 13, wherein the reinforcing fiber content is 5 to 40 wt%. The thermoplastic polymer [C] is a thermoplastic polymer obtained by condensation of phenol or a phenol derivative and an aliphatic hydrocarbon, and having a weight average molecular weight in the range of 300 to 1,000. The long fiber reinforced thermoplastic resin pellet according to any one of 15.

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