JP5519434B2 - Polyester fiber for resin reinforcement - Google Patents

Description

  The present invention relates to a polyester fiber for resin reinforcement that can be uniformly dispersed in a matrix resin and from which a fiber-reinforced resin molded article excellent in impact resistance can be obtained.

  A fiber reinforced thermoplastic resin obtained by reinforcing a thermoplastic resin such as a polyolefin resin with short fibers has excellent mechanical strength characteristics such as tensile strength and rigidity, and is therefore suitably used for various industrial parts. Conventionally, many glass fibers that are inexpensive and excellent in dimensional stability and heat resistance have been used as resin reinforcing fibers, and glass fiber reinforced resins are still used in many industrial products. However, the effective use of resources and energy saving have been taken up as issues in response to the recent global environmental waste problems and the future depletion of petroleum resources. At present, there are problems in terms of recyclability and weight reduction due to the inclusion of. Against this background, fiber reinforced resins are required to satisfy not only mechanical properties such as strength and impact resistance, but also environmental aspects such as recyclability.

  In addition, since fiber reinforced thermoplastic resin is usually produced by melt-kneading resin and reinforced fiber, the fiber is shortened at the time of production, and the disadvantage is that it is inferior in impact strength such as Izod impact strength and falling weight impact strength. Have. Furthermore, due to the dispersion / orientation of the fibers in the resin, there are problems in strength anisotropy, dimensional stability, appearance quality, etc. depending on the shape of the molded product, and its use is currently limited.

  As what improved the fiber dispersibility and impact resistance of such a fiber reinforced thermoplastic resin, the glass long fiber of 5-50 mm is made into polyolefin like patent document 1 (Unexamined-Japanese-Patent No. 60-86139), for example. A fiber reinforced resin composition obtained by melt-kneading 5 to 60% by weight of a resin has been proposed. However, in the glass fiber reinforced resin molded product, when the glass fiber is melt-kneaded with the matrix resin, the fiber is broken and shortened. For this reason, in order to obtain a sufficient reinforcing effect, it is necessary to blend a considerable amount of glass fiber, not only to meet the need for weight reduction, but also when the fiber reinforced resin molded product is thermally recycled, for example, a high temperature. The glass melts at the time of combustion in the furnace and damages the furnace, and there is a difficulty in recyclability in terms of cost and operability. Further, as in Patent Document 2 (Japanese Patent Laid-Open No. 10-176085), Patent Document 3 (Japanese Patent Laid-Open No. 2001-81336), and Patent Document 4 (Japanese Patent Laid-Open No. 2005-2202), fiber dispersibility and mechanical properties are disclosed. Although the resin reinforced resin composition which improved this is proposed, all are related with glass fiber reinforcement, and all had the same subject as the above.

  On the other hand, by using polyester fibers excellent in mechanical properties, versatility and recyclability as reinforcing fibers, fiber reinforced resins satisfying resin reinforcement, recyclability and weight reduction are unparalleled. Further, as a result of attempts by the present inventors to reinforce the resin with polyester fibers, it has been found that the dispersibility of the polyester fibers in the matrix resin is low, and sufficient reinforcing effects such as strength and impact resistance cannot be obtained.

JP 60-86139 A JP-A-10-176085 JP 2001-81336 A Japanese Patent Laid-Open No. 2005-2202

  An object of the present invention is to provide a polyester fiber for resin reinforcement that solves the above-described problems and from which a fiber-reinforced resin molded article excellent in impact resistance and uniformly dispersed in a matrix resin can be obtained.

According to the present invention, a resin-reinforced polyester fiber used for resin reinforcement, wherein the resin-reinforced polyester fiber satisfies the following (A), (B) and (C) simultaneously: Reinforcing polyester fibers are provided.
(A) Tensile strength at 25 ° C. is 6 to 10 cN / dtex
(B) 210 ° C. dry heat shrinkage is 1 to 12%
(C) After heat treatment at 210 ° C. for 60 seconds, the tensile strength is 5 to 10 cN / dtex and the toughness is 30 to 50
[Toughness = tensile strength (cN / dtex) × √elongation (%). ]

The resin reinforcing polyester fiber is preferably made of polyester in which 90 mol% or more of the repeating units are composed of ethylene terephthalate or ethylene-2,6-naphthalate.
Moreover, the polyester fiber for resin reinforcement characterized by the thermosetting resin adhering to the said polyester fiber for resin reinforcement 0.01-5.0weight% with respect to the polyester fiber weight for this resin reinforcement Preferably, the thermosetting resin is an epoxy resin or a urethane resin.

  The polyester fiber for resin reinforcement of the present invention is excellent in the dimensional stability of the reinforcing fiber at the time of fiber reinforced resin pellet production or fiber reinforced resin molding production, and exhibits high strength and toughness as the reinforcing fiber of the resin molding. A fiber-reinforced resin molded article having excellent impact properties can be obtained. Moreover, by using the polyester fiber for resin reinforcement of the present invention, environmental effects such as weight reduction, recyclability, and durability improvement of the resin molded body can be expected, and it has a great practical effect.

  The polyester fiber for resin reinforcement in the present invention has a tensile strength at 25 ° C. of 6 to 10 cN / dtex. When the tensile strength is less than 6 cN / dtex, the strength as a reinforcing fiber is low, and a resin reinforcing effect that sufficiently satisfies the object of the present invention cannot be obtained. On the other hand, when the tensile strength exceeds 10 cN / dtex, the polyester fiber has many defects such as fuzz, and not only yarn breakage or single yarn entanglement occurs during the production of the fiber reinforced resin pellet, but also the fiber in the fiber reinforced resin molded product It causes entanglement / aggregation, etc., resulting in deterioration of workability, reinforcing effect of the resin molded product, or deterioration of appearance quality. As a 25 degreeC tensile strength, 6.5-9.5 cN / dtex is preferable and 7.0-9.0 cN / dtex is more preferable.

  Moreover, the 210 degreeC dry heat shrinkage rate of the polyester fiber for resin reinforcement in this invention is 1 to 12%. Here, the 210 ° C. dry heat shrinkage rate indicates the dimensional change rate in the longitudinal direction of the fiber before and after heat treatment for 60 seconds under no load at 210 ° C. The inventors of the present invention have found that the physical properties of the obtained fiber-reinforced resin molded article are improved when the polyester fiber for resin reinforcement exhibits appropriate shrinkage during the molding of the fiber-reinforced resin molded article. When the dry heat shrinkage at 210 ° C. is less than 1%, the polyester polymer constituting the polyester fiber for resin reinforcement is in a state where the orientation parallel to the fiber axis is very low (non-orientation), and is sufficient to exert the resin reinforcement effect. High tensile strength cannot be obtained. On the other hand, when the 210 ° C. dry heat shrinkage rate exceeds 12%, the dimensional change of the reinforcing polyester fiber is large at the time of molding the fiber reinforced resin molded article, which is excellent because the orientation and dispersion of the reinforcing fiber in the matrix resin decrease. The resin reinforcement effect cannot be obtained. The 210 ° C. dry heat shrinkage rate is preferably 2 to 11%, more preferably 3 to 10%.

  Further, the tensile strength after heat treatment at 210 ° C. for 60 seconds of the polyester fiber for resin reinforcement in the present invention is 5 to 10 cN / dtex, and the toughness is 30 to 50. Here, toughness is a value determined by toughness = strength × √elongation. As a result of extensive studies, the present inventors have greatly influenced the thermal history received by the polyester fiber for resin reinforcement during molding of the fiber-reinforced resin molded product. As a result of further investigation, the polyester fiber after heat treatment at 210 ° C. × 60 sec. It was found that the strength and toughness greatly contribute to the improvement of impact resistance of the fiber reinforced resin molded product. That is, since the polyester fiber for resin reinforcement receives heat history and is heat set or relaxed at the time of molding the fiber reinforced resin molded product, the physical properties of the polyester fiber after the heat treatment greatly determines the reinforcing effect. . Therefore, in the present invention, when the tensile strength after heat treatment at 210 ° C. for 60 seconds of the polyester fiber for resin reinforcement is less than 6 cN / dtex, the strength of the reinforcing fiber is low, so that the resin reinforcing effect sufficiently satisfying the object of the present invention is obtained. I can't. On the other hand, since the tensile strength at 25 ° C. is 10 cN / dtex or less, the tensile strength after heat treatment under no load does not exceed 10 cN / dtex. The tensile strength after heat treatment at 210 ° C. for 60 seconds is preferably 5.5 to 9.5 cN / dtex, and more preferably 6.0 to 9.0 cN / dtex.

  The polyester fiber for resin reinforcement used in the present invention is preferably composed of polyester in which 90 mol% or more of repeating units are composed of ethylene terephthalate or ethylene-2,6-naphthalate, and the polyester fiber has a molecular weight, fineness, and number of filaments. The polymer properties such as the cross-sectional shape, yarn physical properties, fine structure, presence / absence of additives, and terminal carboxy group concentration are not limited at all.

  In the case of polyethylene terephthalate, the molecular weight of polyester is preferably 0.60 to 1.20 dL / g, more preferably 0.65 to its intrinsic viscosity (measured at a temperature of 35 ° C. using o-chlorophenol as a solvent). 1.10 dL / g, more preferably 0.70 to 1.00 dL / g.

  On the other hand, in the case of poly (ethylene-2,6-naphthalate), the molecular weight is measured at 35 ° C. by dissolving in an intrinsic viscosity (o-chlorophenol and o-dichlorobenzene mixed solvent (volume ratio 6: 4)). Value) is preferably 0.50 to 1.00 dL / g, more preferably 0.55 to 0.95 dL / g, and still more preferably 0.60 to 0.90 dL / g.

In the present invention, the single fiber fineness of the polyester fiber for resin reinforcement is preferably about 1 to 20 dtex, preferably about 2 to 15 dtex.
Moreover, the total fineness of the said polyester fiber is although it does not specifically limit, Preferably it is 150-3,000 dtex, More preferably, it is 250-2,000 dtex. The total fineness can be reduced by combining a plurality of polyester fibers of these total fineness in advance before manufacturing the fiber reinforced resin pellets, or by supplying a plurality of yarns from the creel stand at the time of fiber reinforced resin pellet manufacturing. There is no problem even if the increase is adjusted.

  Furthermore, the number of filaments of the polyester fiber is not particularly limited, but is preferably 10 to 1,000 filaments, more preferably 50 to 500 filaments. Note that there is no problem even if the number of filaments is increased and adjusted by combining the yarns as described above.

  It is preferable that the thermosetting resin which consists of an epoxy-type resin or a urethane-type resin has adhered to the polyester fiber for resin reinforcement of this invention 0.01 to 5.0 weight% with respect to this polyester fiber weight. In the present invention, the polyester fibers are coated with a thermostable thermosetting resin, thereby maintaining the polyester fibers in the fiber-reinforced resin pellets and filling the resin densely around the reinforcing fibers. The fibers can be opened at the time of melt kneading at the time of fiber reinforced resin molding, and uniform dispersibility can be expressed. If the adhesion amount of the thermosetting resin is less than 0.01% by weight, it tends to be difficult to obtain sufficient fiber convergence to exert the effect of the present invention, while the adhesion amount is less than 5.0% by weight. If it exceeds the upper limit, the fiber becomes too hard, so that the processability is lowered. Further, since the fiber is difficult to open at the time of molding, the reinforcing effect and appearance quality of the resin molded product tend to be lowered. The adhesion amount of the thermosetting resin to the polyester fiber in the present invention is preferably 0.03 to 3.5% by weight, more preferably 0.05 to 2.0% by weight, based on the weight of the polyester fiber. By such a polyester fiber for resin reinforcement of the present invention, a fiber reinforced resin molded article having excellent mechanical properties and impact resistance can be obtained by uniformly dispersing the reinforcing fiber in the matrix resin.

  Examples of the thermosetting resin used in the polyester fiber used in the present invention include unsaturated polyester resins, vinyl ester resins, epoxy resins, phenol (resole type) resins, urea / melamine resins, and polyimide resins. Examples thereof include resins, urethane resins, copolymers thereof, and modified products. In particular, an epoxy resin or a urethane resin is preferable from the viewpoints of handleability, workability, and mechanical properties.

  Of these, specific examples of epoxy resins (including epoxy compounds) include diglycidyl ether compounds, ethylene glycol diglycidyl ethers and polyethylene glycol diglycidyl ethers, propylene glycol diglycidyl neethers and polypropylene glycol diglycidyl ethers. 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, polyalkylene glycol diglycidyl ether, and the like. In the polyglycidyl ether compound, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, arabitol polyglycidyl ether, trimethylolpropane polyglycidyl ether, penta Examples include erythritol polyglycidyl ethers and polyglycidyl ethers of aliphatic polyhydric alcohols. Preferably, it is an aliphatic polyglycidyl ether compound having a highly reactive glycidyl group. More preferably, polyethylene glycol diglycidyl ethers, polypropylene glycol diglycidyl ethers, alkanediol diglycidyl ethers and the like are preferable.

  The urethane resin is synthesized by polyaddition reaction using polyisocyanate and polyol as main raw materials. The polyisocyanate may be any isocyanate compound such as aromatic isocyanate typified by tolylene diisocyanate, aliphatic isocyanate such as hexamethylene diisocyanate, and alicyclic isocyanate. Moreover, as said polyol, polyethyleneglycol, polytetramethylene glycol, a polyester-type polyol etc. are used normally. Furthermore, the end of the isocyanate component can be made into a prepolymer using an appropriate blocking agent, and can be polymerized by applying heat later to make a urethane resin.

  The polyester fiber for resin reinforcement of the present invention can be produced, for example, by the following method. That is, using the polyethylene terephthalate chip having the intrinsic viscosity, after applying a spinning oil to the undrawn yarn that has been spun from a spinneret and cooled and solidified, and taken up with a roller, the first roller and the second at 90 to 120 ° C. First-stage stretching is performed 2.5 to 4.5 times between the rollers, and the total stretching ratio is 4.0 to 5.7 times between the second roller and the third roller at 230 to 260 ° C. The second stage is stretched so that it becomes 4-12% relaxation between the third roller and the fourth roller, and wound on a cheese-like package or the like at a speed of 2,000-4,000 m / min. This can be produced by heating at 40 to 60 ° C. for 60 to 180 hours. In addition, a poly (ethylene-2,6-naphthalate) chip having the intrinsic viscosity is used, and a spinning oil is applied to the undrawn yarn that has been spun from a spinneret and cooled and solidified, and taken up with a roller. The first draw is 4.0 to 6.0 times between the first roller and the second roller at ° C, and the total draw ratio is further between the second roller and the third roller at 230 to 260 ° C. The second stretch is 4.5 to 6.5 times, wound up on a cheese-like package or the like at a speed of 2,000 to 4,000 m / min, and this is 40 to 60 ° C. for 60 to 180 hours. It can manufacture by performing a heating process.

  In addition, as a method of applying a thermosetting resin to the polyester fiber for resin reinforcement, the method of applying the thermosetting resin and / or the polyester fiber once before winding into a cheese shape in the process of producing the polyester fiber. A method of impregnating and heat treating the polyester fiber with the thermosetting resin after winding is exemplified. Any method may be employed as long as the effects of the present invention are not impaired.

  The resin composition reinforced with the resin reinforcing polyester fiber according to the present invention is not particularly limited, but the resin reinforcing polyester fiber molding is suitable for polyolefin resins such as polyethylene and polypropylene in consideration of temperature and the like. Can be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these.

(1) Fineness of fiber, number of filaments, strong elongation, 210 ° C. dry heat shrinkage rate compliant with JIS-L-1013. The heat treatment time at 210 ° C. dry heat shrinkage was 60 seconds.

(2) Strong elongation of fiber after heat treatment at 210 ° C. for 60 seconds A fiber having a yarn length of 50 cm is placed in a 210 ° C. thermostatic bath for 60 seconds in an unloaded state, subjected to heat treatment, and then the taken-out fiber is converted into JIS-L- Tensile strength and elongation were measured according to 1013. The toughness was calculated by the following formula.
Toughness = strength (cN / dtex) × √elongation (%)

(3) Uniform dispersibility of reinforcing fibers (appearance evaluation)
The surface of the flat plate of the molded product was visually observed. ○ If the dispersion is extremely uniform such that a bundle of unopened fibers is not seen, △ if there is a fiber bundle that is not opened in a very small part, △, not opened or entangled When there was non-uniform dispersion in which a large number of fiber bundles were observed, the evaluation was made in three stages as x. △ or more was accepted.

(4) Tensile rupture strength and tensile rupture elongation of resin molded body For a TYPE-I bar having a thickness of 3.2 mm and a width of 12.7 mm obtained by molding, a test speed in accordance with ASTM-D-638-02 Measurement was performed at 50 mm / min.

(5) Izod impact strength Conforms to ASTM-D-256-00 with a bar of 6.4 mm thickness x 12.7 mm width x 127 mm obtained by molding and cut to half 63.5 mm length The measurement was performed under the following conditions.
Notch processing speed: 400rpm
Notch processing feed rate: 120 mm / min
Hammer capacity: 60kgf · cm
Measurement temperature: 23 ° C., −40 ° C.

Production of polyester fiber for resin reinforcement [Example 1]
Intrinsic viscosity (measured with an o-fluorophenol solvent at 35 ° C.) 1.01 dL / g polyethylene terephthalate tip, spun from a spinneret, cooled to solidified undrawn yarn, POE (10) lauryl amino ether 8 weight Is added to the fiber so that the amount of the amine compound component attached is 0.02% by weight and taken up with a roller. First stage stretching is performed 3.5 times between the first roller and the second roller, and the total stretching ratio is 5.8 times between the second roller and the third roller at 250 ° C. Second-stage stretching, followed by 4% relaxation between the third and fourth rollers and polyglycerol polyglycidyl ether ("Denacol" manufactured by Nagase ChemteX) X-512 ") A 40 wt% aqueous solution is applied by a roller type oiling method so that the epoxy component adhesion amount is 0.1 wt% with respect to the fiber, and wound around a cheese-like package at a speed of 3,000 m / min. I took it. Next, a heating treatment was performed at 55 ° C. for 120 hours to obtain 1,670 dtex / 250 f, intrinsic viscosity 0.90 dL / g, strength 7.6 cN / dtex, elongation 12.3%, 210 ° C. dry heat shrinkage 11. A polyethylene terephthalate fiber (PET fiber) having 6% and an epoxy resin adhesion amount of 0.1% by weight was obtained.

[Example 2]
The intrinsic viscosity was 0.90 dL / g, the strength was 7.0 cN / g as in Example 1 except that the total draw ratio was 4.85 times and 9% relaxation was given between the third roller and the fourth roller. A polyethylene terephthalate fiber (PET fiber) having a dtex, elongation of 25.9%, 210 ° C. dry heat shrinkage of 6.5%, and an epoxy resin adhesion amount of 0.1% by weight was obtained.

[Example 3]
Implemented except that the relaxation rate between the third roller and the fourth roller was 10%, the total draw ratio was 5.30 times, the spinning oil did not contain POE (10) laurylamino ether, and no epoxy component was added. In the same manner as in Example 1, a polyethylene terephthalate fiber (PET fiber) having an intrinsic viscosity of 0.89 dL / g, a strength of 7.6 cN / dtex, an elongation of 21.5%, and a 210 ° C. dry heat shrinkage of 5.0% was obtained. .

[Example 4]
A poly (ethylene-2,6-naphthalate) chip having an intrinsic viscosity (dissolved in a mixed solvent of o-chlorophenol and o-dichlorobenzene (volume ratio 6: 4) and measured at 35 ° C.) of 0.76 dL / g A spinning oil mainly composed of a polyether ester-based component containing 8% by weight of POE (10) laurylamino ether is used as an amine compound component for the fiber in undrawn yarn that has been spun from a spinneret and cooled and solidified. After applying with a roller so that the adhesion amount of 0.02% by weight is taken with a roller, the first stage stretching is performed 5.0 times between the first roller and the second roller at 150 ° C., and the second Second stage stretching was performed between the roller and the third roller at 230 ° C. so that the total stretching ratio was 5.8 times, and polyglycerol polyglycidyl ether (“Denacol EX-5” manufactured by Nagase ChemteX Corporation) was drawn. 2 ") A 40 wt% aqueous solution was applied by a roller-type oil agent application method so that the epoxy component adhesion amount was 0.1 wt% with respect to the fiber, and wound around a cheese-like package at a speed of 3,000 m / min. . Subsequently, a humidification treatment was performed at 55 ° C. for 120 hours to obtain 1,670 dtex / 250 f, intrinsic viscosity 0.70 dL / g, strength 8.2 cN / dtex, elongation 11.5%, 210 ° C. dry heat shrinkage 8.5. % Poly (ethylene-2,6-naphthalate) fiber (PEN fiber) having an epoxy resin adhesion amount of 0.1% by weight was obtained.

[Example 5]
The inherent viscosity was 0.70 dL / g, the strength was 8.2 cN / dtex, and the elongation was 11 as in Example 5 except that the spinning oil did not contain POE (10) lauryl amino ether and no epoxy component was added. A poly (ethylene-2,6-naphthalate) fiber (PEN fiber) having a dry heat shrinkage of 8.3% at 210 ° C. and 8.3% was obtained.

[Comparative Example 1]
The intrinsic viscosity was 0.90 dL / g, as in Example 1, except that the third roller temperature was 220 ° C., the relaxation rate between the third roller and the fourth roller was 3%, and the total draw ratio was 5.85 times. A polyethylene terephthalate fiber (PET fiber) having a strength of 8.1 cN / dtex, elongation of 13.0%, 210 ° C. dry heat shrinkage of 19.2%, and an epoxy resin adhesion amount of 0.1% by weight was obtained.

[Comparative Example 2]
Winding speed 5,000 m / min, one-stage draw ratio 1.4 times, total draw ratio 2.2 times, third roller temperature 200 ° C., relaxation rate between third roller and fourth roller 0% In the same manner as in Example 1, the intrinsic viscosity was 0.91 dL / g, the strength was 7.6 cN / dtex, the elongation was 12.5%, the 210 ° C. dry heat shrinkage rate was 16.8%, and the epoxy resin adhesion amount was 0.1. A weight% polyethylene terephthalate fiber (PET fiber) was obtained.

[Comparative Example 3]
The intrinsic viscosity was 0.89 dL / g, the strength was 5.5 cN / dtex, the elongation was 39.0%, 210 except that the third roller temperature was 220 ° C. and the total draw ratio was 3.8 times. A polyethylene terephthalate fiber (PET fiber) having a dry heat shrinkage of 11.9% and an epoxy resin adhesion amount of 0.1% by weight was obtained.

[Comparative Example 4]
The intrinsic viscosity was 0.70 dL / g, the strength was 5.8 cN / dtex, the elongation was 22.5%, 210 except that the one-stage draw ratio was 3.8 times and the total draw ratio was 3.9 times. A poly (ethylene-2,6-naphthalate) fiber (PEN fiber) having a dry heat shrinkage of 7.1% and an epoxy resin adhesion amount of 0.1% by weight was obtained.

Production of Fiber Reinforced Resin Molded Body [Examples 1 to 5, Comparative Examples 1 to 4]
The obtained polyester fiber for resin reinforcement and polypropylene resin (Novatech PP SA06A manufactured by Nippon Polypro Co., Ltd.) were subjected to pultrusion molding using a single screw extruder having a crosshead die to produce fiber reinforced polypropylene resin pellets. The fiber content was adjusted to 30% by weight and the pellet length was adjusted to 10 mm. Subsequently, the obtained fiber reinforced polypropylene resin pellets were subjected to an injection molding machine, and the thickness was 6.4 mm × width 12 at a cylinder temperature of 210 ° C., a mold temperature of 70 ° C., a back pressure of 10 kg / cm ² , and a screw rotation speed of 50 rpm. A bar having a length of 0.7 mm and a length of 127 mm and a bar of TYPE-I having a thickness of 3.2 mm and a width of 12.7 mm were formed. About Example 1-5 and Comparative Examples 1-4, the evaluation result of a polyester fiber and a fiber reinforced resin molding is put together in Table 1, and is shown.

  The fiber reinforced resin molded products using the polyethylene terephthalate fibers for resin reinforcement of Examples 1 to 3 are remarkably improved in strength, elongation and impact resistance, and exhibit an excellent reinforcing effect. Moreover, the fiber reinforced resin molded body using the poly (ethylene-2,6-naphthalate) fiber for resin reinforcement of Examples 4 and 5 also exhibits excellent strength, elongation, and impact resistance, and has an excellent reinforcing effect. It shows that it is demonstrating. Of these, Examples 3 and 5 were not imparted to the fiber with epoxy, and some entanglement of fibers was observed in the fiber-reinforced resin molded product, but the appearance quality was slightly inferior, but the strength and impact resistance of the resin molded product. The mechanical properties such as were able to obtain a sufficient reinforcing effect. On the other hand, Comparative Examples 1 and 2 have a low dry heat shrinkage of 210 ° C. and a toughness after heat treatment of 210 ° C. × 60 sec, and the impact resistance of the obtained fiber-reinforced resin molded product is low compared to the Examples. 3 and 4 were low in strength of the fiber-reinforced resin molded product compared to the Examples, and Comparative Examples 1 to 4 all had a uniform dispersibility of the reinforcing fiber, but the resin reinforcing effect by the polyester fiber was low. It was.

  The polyester fiber for resin reinforcement of the present invention is excellent in dimensional stability of the reinforcing fiber at the time of fiber reinforced resin pellet production or fiber reinforced resin molded product production, and exhibits high strength and toughness as the reinforcing fiber of the fiber reinforced resin molded product. It is possible to obtain a fiber reinforced resin molded article with excellent impact resistance, and it can also be expected to have environmental effects such as weight reduction, recyclability and improved durability of the molded resin, and thermoplastics such as olefin resins. It has a great practical effect as a resin reinforcing fiber.

Claims (4)

A polyester fiber for resin reinforcement used for resin reinforcement, wherein the polyester fiber for resin reinforcement satisfies the following (A), (B) and (C) at the same time.
(A) Tensile strength at 25 ° C. is 6 to 10 cN / dtex
(B) 210 ° C. dry heat shrinkage is 1 to 12%
(C) After heat treatment at 210 ° C. for 60 seconds, the tensile strength is 5 to 10 cN / dtex and the toughness is 30 to 50
[Toughness = tensile strength (cN / dtex) × √elongation (%). ]   The polyester fiber for resin reinforcement according to claim 1, wherein the polyester fiber for resin reinforcement is made of polyester in which 90 mol% or more of repeating units are composed of ethylene terephthalate or ethylene-2,6-naphthalate.   A resin in which a thermosetting resin is attached to the polyester fiber for resin reinforcement according to claim 1 or 2 in an amount of 0.01 to 5.0% by weight based on the weight of the polyester fiber for resin reinforcement. Reinforcing polyester fiber.   The polyester fiber for resin reinforcement according to claim 3, wherein the thermosetting resin is an epoxy resin or a urethane resin.