JP5864314B2 - Fiber reinforced elastomer molded product - Google Patents

Description

  The present invention relates to a fiber-reinforced elastomer molded article having excellent appearance and excellent mechanical strength such as rigidity and impact strength and dimensional stability.

In order to improve the mechanical strength, rigidity, impact strength, etc. of plastic materials, fiber reinforced plastics (usually called FRP) in which carbon fibers, metal fibers, aramid fibers, glass fibers, etc. are dispersed are known. However, as environmental considerations in recent years have increased, studies are underway to replace inorganic fibers such as glass fibers that have problems with recyclability and disposal with organic fibers such as polyethylene terephthalate (abbreviated as PET), vinylon, and nylon. (See, for example, Patent Document 1 and Patent Document 2).
Further, when the fine fiber having a fineness of 0.6 dtex or less is used as the reinforcing fiber, the target machine is likely to agglomerate and poorly dispersed in the matrix resin. There was a tendency to deteriorate the mechanical strength and impact strength.

  Both Patent Document 1 and Patent Document 2 are composite spun fibers in which the melting point of the resin constituting the core part is sufficiently higher than the molding temperature of the matrix resin and 20 ° C. higher than the melting point of the resin constituting the sheath part. There has been proposed a method for producing a fiber-reinforced plastic that improves the dispersibility of a reinforcing fiber composed of a core component by melt-kneading and molding an organic fiber-based reinforcing material in a matrix resin. However, such a core-sheath composite fiber is difficult to reduce in fineness, it is difficult to make the fineness of the reinforcing fiber composed of the core component smaller than 1.0 dtex, and the core fineness is reduced by reducing the core ratio. Decreasing the size does not necessarily increase the spinning draft in the direction that the spinnability deteriorates, and the fineness can be reduced, and the ratio of the surrounding sheath resin component increases, so that the density and added amount of reinforcing fibers There is a demerit that does not lead to a sufficient improvement in physical properties.

  Patent Document 3 discloses that by adding a short fiber having a sea-island-shaped cross section to a matrix resin, an ultrafine organic fiber of 0.6 dtex or less is used as a reinforcing fiber at a high concentration, good dispersibility, and due to interfacial peeling. Fiber reinforced plastics with reduced physical properties have been proposed. However, since the sea component is mainly composed of the same type of resin as the matrix resin, it is difficult to use a matrix resin that has a heat resistance equal to or lower than the melting temperature at the time of spinning of the island component that is the reinforcing fiber, or is difficult to melt-spin. . Examples thereof include rubber materials such as natural rubber, styrene butadiene rubber, and ethylene propylene rubber.

JP-A-8-151383 JP 2003-96622 A JP 2006-249233 A

  The present invention has been made against the background of the above-described prior art, and its purpose is to uniformly disperse organic ultrafine fibers of 10 to 5000 nm as reinforcing fibers, and fiber reinforced elastomer molding with less theoretically specific deterioration in strength. Is to provide goods. Another object of the present invention is to provide a fiber-reinforced elastomer molded product that is not limited to a resin that can be melt-spun as a matrix.

  The inventors of the present invention have reached the present invention as a result of repeated studies to solve the above-mentioned problems.

That is, the present invention
A fiber-reinforced elastomer molded article characterized in that the following requirements a) to d) are simultaneously satisfied by adding sea-island type composite short fibers to a matrix and melting the sea component to make the island component a reinforcing fiber.
a) The solubility parameter value (SP (s)) of the sea component of the sea-island type composite fiber, the solubility parameter value (SP (i)) of the island component, and the solubility parameter (SP (m)) of the matrix resin are represented by the following formula (1). , (2). (The unit of SP value is (cal / cm ³ ) ^1/2 )
0 ≦ | SP (s) −SP (m) | <| SP (i) −SP (m) | <5 (1)
0 ≦ | SP (s) −SP (m) | <| SP (i) −SP (s) | <5 (2)
b) the relationship of the island component of a melting point Tm (i) and the matrix of the molding temperature (℃) is, Tm (i) - it is the molding temperature ≧ 20 ° C..
c) The melt viscosity ratio (sea / island) of the sea component and the island component is 0.2-5.
d) The island component diameter is 10 to 5000 nm.

  According to the present invention, it is possible to provide a fiber-reinforced elastomer molded article having a high concentration and good dispersibility using ultrafine organic fibers as reinforcing fibers.

Hereinafter, embodiments of the present invention will be described in detail. The fiber-reinforced elastomer molded article of the present invention comprises a matrix and short fibers having a sea-island cross section.
Regarding the sea component, island component, and matrix resin constituting the sea-island composite fiber, the solubility parameter (SP value, unit (cal / cm ³ ) ^1/2 ) of each component, the sea component of the sea-island composite fiber The solubility parameter value (SP (s)), the solubility parameter value of the island component (SP (i)), and the solubility parameter value of the matrix (SP (m)) are represented by the following formulas (1) and (2). It is necessary.
0 ≦ | SP (s) −SP (m) | <| SP (i) −SP (m) | <5 (1)
0 ≦ | SP (s) −SP (m) | <| SP (i) −SP (s) | <5 (2)

  When the SP value difference between the island component and the matrix exceeds 5, the dispersibility in the molded product is deteriorated and voids are easily formed inside. On the other hand, if the SP value difference between the island component and the sea component exceeds 5, the compatibility of the polymer is poor, resulting in a section failure at the time of spinning, and the island diameter becomes uneven. Further, the SP value difference between the sea component and the matrix must be less than the SP value difference between the island component and the matrix and the SP value difference between the island component and the sea component. When the difference and the SP value difference between the island component and the sea component are greater than or equal to each other, the compatibility between the sea component and the matrix is poor, so that the island component is not uniformly dispersed and the dispersibility in the molded product is deteriorated.

  In addition, the resin used as the island component needs to satisfy the relationship between the melting point Tm (i) and the molding temperature (° C.) of the matrix: Tm (i) −molding temperature ≧ 20 ° C. If the melting point Tm (i) of the island component that becomes the reinforcing fiber is equal to or lower than the molding temperature of the matrix, the island component that becomes the reinforcing fiber when melting the matrix and filling the reinforcing fiber therewith also melts Therefore, a desired fiber-reinforced elastomer molded product cannot be obtained. In addition, the relationship between the melting point Tm (i) of the island component and the molding temperature of the matrix resin is extremely important from the viewpoint of the strength and thermal stability of the reinforcing fiber, and Tm (i) −molding temperature ≧ 20 ° C. described above. It is necessary to have a relationship.

Furthermore, the resin used as the island component satisfies that the relationship between the melting point Tm (i)) and the melting point Tm (s) of the sea component satisfies Tm (i) −Tm (s) ≧ 20 ° C. Is preferred. If the melting point Tm (i) of the island component is equal to or lower than the melting point Tm (s) of the sea component, it is difficult to obtain the strength of the ultrafine fiber that becomes the reinforcing fiber when the sea island fiber is manufactured. Sometimes the island component is deformed by heat at a temperature lower than the sea component, and a desired fiber-reinforced elastomer molded product cannot be obtained. In addition, the relationship between the melting point Tm (i) of the island component and the melting point Tm (s) of the sea component is extremely important from the viewpoint of the strength and dimensional stability of the reinforcing fiber, and Tm (i) −Tm ( s) It is preferable to have a relationship of ≧ 20 ° C.
Although it does not specifically limit as a component used for an island component, a sea component, and a matrix, when satisfy | filling the above-mentioned conditions, The resin for molding currently used conventionally can be used.

Examples of the resin component used for the island component include polyesters, polyamides, and polyolefins. These resin components can be used singly or in combination. Among them, polyethylene terephthalate, polyethylene naphthalate, polytrimethylene terephthalate, polybutylene terephthalate and the like are preferable in the case of polyester, and nylon 6 and nylon 66 are preferable in the case of polyamide. In the case of polyolefins, ethylene copolymers of vinyl monomers such as high density polyethylene, medium density polyethylene, high pressure low density polyethylene, linear low density polyethylene, isotactic polypropylene, ethylene propylene copolymer, maleic anhydride, etc. A polymer etc. can be mentioned as a preferable example. Other examples include polysulfone, polyimide, polyketones, polyarylate and the like.
The melting point of the island component is preferably 200 ° C. or higher. When the temperature is lower than 200 ° C., the island component is softened or dissolved during molding, the strength of the reinforcing fiber is lowered, and uniform dispersion inside the molded product is difficult, and the application range of the component serving as a matrix is narrowed.

On the other hand, examples of the resin component used for the sea component include polyester-based, aliphatic polyamide-based, polyethylene-based, polypropylene-based, polystyrene-based, polyacryl-based, and the like, and these resin components are single or mixed. It can also be used. Of these, polyolefins such as polyethylene, polypropylene, and ethylene-propylene-butene copolymers are preferable.
From the viewpoints of fiberization, sea-island cross-sectional formability, product moldability, product physical properties, etc., there is no particular problem even if the melt flow rate (MFR) of the matrix component and the sea component resin is different. Further, a compatibilizing agent for suppressing interfacial peeling, a thinning agent for adjusting melt viscosity, or a third component resin may be contained depending on the purpose.

  The components used in the matrix are not particularly limited as long as the above-mentioned conditions are satisfied. Specifically, the elastomer components include silicon rubber, chloroprene rubber, natural rubber, isoprene rubber, nitrile rubber, styrene / butadiene rubber, butadiene rubber. And ethylene-α-olefin elastomer, ethylene / propylene rubber, chlorosulfonated polyethylene rubber, acrylic rubber, urethane rubber, hydrogenated acrylonitrile rubber and the like, and polymer gels such as silicone gel, acrylic gel and urethane gel. Of these, ethylene / propylene rubber, ethylene-α-olefin elastomer, and styrene / butadiene rubber are preferable. These may be used alone or in combination of two or more.

  Examples of the ethylene-α-olefin elastomer include a rubber made of a copolymer of an α-olefin excluding ethylene and ethylene and a diene (non-conjugated diene), and a copolymer of an α-olefin excluding ethylene and ethylene. Rubber, partially halogenated products thereof, and the like. The α-olefin excluding ethylene is preferably propylene, butene, hexene or octene. As the diene, a non-conjugated diene such as 1,4-hexadiene, dicyclopentadiene or ethylidene norbornene is usually used as appropriate.

  Specific examples of the ethylene-α-olefin elastomer include ethylene-propylene-diene rubber (EPDM), ethylene-propylene copolymer (EPM), ethylene-butene copolymer (EBM), ethylene-octene copolymer (EOM), and the like. And the like.

  The melt viscosity ratio (sea / island) of the sea component and the island component needs to be 0.2 to 5.0, preferably 1.0 to 2.5, and most preferably 1.3 to 1. It is preferable to be within the range of 5. When this ratio is less than 0.5 times, island components near the center are easily joined to each other during melt spinning, whereas when it exceeds 5.0 times, the viscosity difference is too large. The island components in the vicinity of the outer layer are likely to be joined to each other, the shape of the island components and the fine diameter are not uniform, and the stability of the spinning process is likely to be reduced.

The sea-island type composite fiber used in the present invention is obtained by fiberizing the sea component and the island component using a known sea-island type composite fiber manufacturing apparatus.
As the spinneret used for melt spinning of the sea-island type composite fiber used in the present invention, a suitable one such as a hollow pin group or a fine hole group for forming an island component can be used. For example, as shown in FIGS. 1 and 2 of WO2005 / 095686, an island component pushed out from a hollow pin or a fine hole, and a sea component flow supplied from a channel designed to fill the gap between the island component Any spinneret may be used as long as it can form a sea-island type composite fiber by forming a sea-island type composite fiber by extruding from the discharge port while gradually converging the combined fluid flow.

  The greater the number of island components in the sea-island composite fiber, the higher the productivity when producing the ultrafine fibers that are island components, and the resulting ultrafine fibers are also significantly thinner, and the softness and smoothness unique to ultrafine fibers Since the glossiness can be exhibited, the number of island components is preferably 100 or more, more preferably 500 or more. Here, when the number of island components is less than 100, it is not possible to obtain a high multifilament yarn composed of ultrafine single fibers that are island components. If the number of island components is too large, not only the manufacturing cost of the spinneret increases, but also the processing accuracy of the spinneret itself tends to decrease. Therefore, the number of island components is preferably 1000 or less.

  Furthermore, the sea-island composite fiber used in the present invention preferably has a sea-island composite mass ratio (sea: island) in the range of 95: 5 to 5:95, more preferably 30:70 to 10:90. Is in range. If it exists in the said range, the thickness of the sea component between island components can be made thin, the melt | dissolution of a sea component will become easy, and the conversion to the fine fiber of an island component will become easy. Here, when the proportion of the sea component is less than 5%, the amount of the sea component is too small, and mutual joining is likely to occur between the islands.

  The discharged sea-island type cross-section composite fiber is solidified by cooling air, and is preferably wound at a speed of 400 to 6000 m / min, more preferably 1000 to 3500 m / min. When the spinning speed is 400 m / min or less, the productivity is insufficient, and when it is 6000 m / min or more, the spinning stability becomes poor.

  The obtained unstretched fiber is a stretched composite fiber having a desired tensile strength, cutting elongation and heat shrinkage property through a separate stretching process, or is taken up by a roller at a constant speed without being wound once, and subsequently Any of the methods of winding after the stretching step may be used. Specifically, it is preheated on a preheating roller of 60 to 190 ° C., preferably 75 ° C. to 180 ° C., stretched at a draw ratio of 1.2 to 6.0 times, preferably 2.0 to 5.0 times, and set. It is preferable to perform heat setting at a roller of 100 to 220 ° C, preferably 120 to 200 ° C. In the case where the preheating temperature is insufficient, the desired high-magnification stretching cannot be achieved. If the set temperature is too low, the shrinkage rate of the obtained drawn fiber is too high, which is not preferable. On the other hand, if the set temperature is too high, the physical properties of the obtained drawn fiber are remarkably lowered.

  Moreover, the diameter of the island component of the sea-island type composite fiber is required to be 10 to 5000 nm, and preferably 100 to 1000 nm. When the diameter of the island component is less than 10 nm, the fiber structure itself is unstable, and the physical properties and fiber form become unstable, which is not preferable. On the other hand, when the diameter exceeds 5000 nm, the surface characteristics of the composite after molding are not good. Since it is inferior, it is not preferable.

  In addition, each island component in the cross section of the composite fiber improves the quality and durability of the ultrafine fiber that becomes the reinforcing fiber after molding as the diameter is uniform, so the average single fiber diameter CV of the ultrafine fiber that becomes the reinforcing fiber % Is preferably 0 to 25%. When CV% exceeds 25%, the diameter variation becomes large. More preferably, it is 0-20%, More preferably, it is 0-15%. The sea-island type composite fiber used in the present invention has a small average single yarn fiber diameter CV% of the island component and a small variation in diameter, so that ultrafine fibers having excellent surface characteristics and a high aspect ratio are uniformly dispersed as reinforcing fibers. The reinforcement effect can be obtained with a small amount. When the CV value is out of this range, the mechanical strength of the obtained molded product is lowered, which is not preferable.

  In order to obtain the fiber-reinforced elastomer molded article of the present invention, it is preferable to cut the sea-island type composite fiber, add it to the molding matrix resin, and mold by injection molding. The cut length is preferably 0.5 to 10 mm. If it is less than 0.5 mm, the production efficiency is poor, and if it is 10 mm or more, the sea components melt before the island components are dispersed during kneading at the time of molding, and the sea island fibers are entangled with each other and the dispersibility deteriorates. .

  The fiber-reinforced elastomer molded article of the present invention contains talc, an ultrafine fiber (bundle) made of island components by dissolving sea components of sea-island composite fibers. And as a ratio with respect to 100 weight part of matrix components, the ratio of an ultrafine fiber is 0.1-100 weight part, Preferably it is 0.1-50 weight part, More preferably, it is 0.1-20 weight part. When the proportion of the polyester ultrafine fiber is less than 0.1% by weight, the ultrafine fiber to be used as the reinforcing fiber of the present invention tends to have an insufficient reinforcing effect, and when it exceeds 100 parts by weight, molding becomes difficult. Therefore, the appearance of the molded product tends to deteriorate.

The invention is further illustrated by the following examples.
In the following examples and comparative examples, the following measurements and evaluations were performed.
(1) Melt viscosity The test polymer is dried, set in an orifice set to the melt temperature of an extruder for melt spinning, held in a molten state for 3 minutes, and then extruded under a predetermined level of load. The shear rate and melt viscosity were plotted. The above operation was repeated under multiple levels of load.
Based on the above data, a shear rate-melt viscosity relationship curve was prepared. On this curve, the melt viscosity when the shear rate is 1000 sec- ¹ is estimated.
(2) Solubility parameter (SP value)
The solubility parameter (SP value) is a value obtained based on a value described in literature or a calculation formula. The unit is (cal / cm ³ ) ^1/2 .
(3) Melting point measurement Using a differential scanning calorimeter (DSC), measurement was carried out at a rate of 20 ° C./min from 30 ° C. to 300 ° C., and the crystal melting peak temperature was taken as the melting point.
(4) Sea-island cross-section formation The sea-island state was observed using an optical microscope.
(5) Average single yarn fiber diameter The fiber diameter was calculated | required by TEM observation 30000 times the ultrafine fiber after sea component dissolution removal. Here, the fiber diameter of the single yarn that was not glued was measured. In the fiber diameter data of 100 randomly selected fine fibers, the average single yarn fiber diameter r was calculated.
(6) Strong elongation The strength and elongation at break of the sea-island type composite fiber were measured with a tensile tester under the conditions of a sample length of 20 cm and a speed of 20 cm / min. The number of measurements was 10, and the average value of the strength was calculated using the fineness obtained from the average single yarn fiber diameter, and was defined as the strength (cN / dtex).
(7) Dispersion state of ultrafine single fibers The cross section of the fiber-reinforced elastomer molded product after molding was observed using a scanning electron microscope (SEM).
(8) Appearance The surface of the flat plate obtained by molding was visually observed.

[Example 1]
As a sea component, high-melting polyethylene having a melting viscosity of 132 ° C., 280 ° C. and 1000 sec ⁻¹ of 1000 poise and an SP value of 8.4 (cal / cm ³ ) ^1/2 [Novatech HD HE495, manufactured by Nippon Polyethylene Co., Ltd.] , Melt flow rate 20 g / 10 min], using PET having a melt viscosity of 900 poise and an SP value of 10.7 (cal / cm ³ ) ^1/2 at a melting point of 254 ° C. and 280 ° C. of 1700 sec ⁻¹ as an island component, Using a sea-island type composite base having 900 island components and 10 holes, the composite spinning machine wound the composite at sea: island = 30: 70, spinning temperature of 280 ° C., take-up speed of 1000 m / min.
Subsequently, the obtained undrawn yarn was drawn using a drawing machine at a drawing temperature of 80 ° C. and a heat setting temperature of 150 ° C. while adjusting the draw ratio so that the elongation of the drawn yarn was 25%. A drawn yarn (composite fiber) was obtained.
The diameter of the composite fiber was 28 μm, the physical properties were 4.8 cN / dtex in strength, the elongation was 23%, the single yarn diameter of the island component was 840 nm, and CV% was 12%. The cross-sectional formability, spinnability and stretchability were very good.
The obtained composite fiber was cut into 1 mm, and a cut fiber having an aspect ratio of about 1200 of ultrafine fibers that are island components was prepared. As a matrix component, 14.3 wt% of composite fiber was added to ethylene-propylene-diene elastomer (EPDM, SP value 8.0 (cal / cm ³ ) ^1/2 ) so as to have a fiber concentration of 10 wt%. A fiber reinforced elastomer molded product was obtained by kneading at 0 ° C., adding a vulcanizing agent and kneading and molding again, followed by vulcanization. As a result of observing the dispersion state of the ultrafine fibers in the molded product, the PET fibers of about 900 nm were uniformly dispersed. When the surface of the molded product was observed, the fibers were completely opened and the surface was smooth.

[Example 2]
As a sea component, high-melting polyethylene having a melting viscosity of 1100 poise at a melting point of 132 ° C., 270 ° C. and 1000 sec ⁻¹ and an SP value of 8.4 (cal / cm ³ ) ^1/2 [Novatec HD HE495 manufactured by Nippon Polyethylene Co., Ltd.] , Melt flow rate 20 g / 10 min], and Ny6 having a melting point of 1200 poise and an SP value of 11.0 (cal / cm ³ ) ^1/2 at a melting point of 223 ° C. and 270 ° C. of 1000 sec ⁻¹ as an island component, In the same manner as in Example 1, the spinning temperature was changed to 270 ° C. to obtain a multifilament drawn yarn (composite fiber).
The diameter of the composite fiber was 28 μm, the physical properties were 4.3 cN / dtex in strength, the elongation was 35%, and the single yarn diameter of the island component was 800 nm. The cross-sectional formability, spinnability and stretchability were very good.
The obtained composite fiber was cut into 1 mm, and a cut fiber having an aspect ratio of about 1200 of ultrafine fibers that are island components was prepared. As a matrix component, 1.4 wt% of composite fiber is added to styrene-butadiene rubber (SBR, SP value 8.6 (cal / cm ³ ) ^1/2 ) so that the fiber concentration becomes 1 wt%, and kneading is performed at a molding temperature of 100 ° C. Then, after adding a vulcanizing agent and kneading and molding again, a fiber reinforced elastomer molded product was obtained by vulcanization. As a result of observing the dispersion state of ultrafine single fibers in the molded product, Ny fibers of about 900 nm are uniformly dispersed. When the surface of the flat plate obtained by the molded product is observed, the fibers are completely opened and the surface is smooth. Met.

[Example 3]
As a sea component, high-melting polyethylene having a melting viscosity of 132 ° C., 280 ° C. and 1000 sec ⁻¹ of 1000 poise and an SP value of 8.4 (cal / cm ³ ) ^1/2 [Novatech HD HE495, manufactured by Nippon Polyethylene Co., Ltd.] , Melt flow rate 20 g / 10 min], using PET having a melt viscosity of 900 poise and an SP value of 10.7 (cal / cm ³ ) ^1/2 at melting point 275 ° C., 290 ° C. 1000 sec ⁻¹ as an island component, Using a sea-island type compound base with 900 island components and 10 holes, the composite spinning machine wound the composite at sea: island = 30: 70, spinning temperature of 290 ° C., take-up speed of 1000 m / min.
Subsequently, the obtained undrawn yarn was drawn using a drawing machine at a drawing temperature of 80 ° C. and a heat setting temperature of 150 ° C. while adjusting the draw ratio so that the elongation of the drawn yarn was 25%. A drawn yarn (composite fiber) was obtained.
The diameter of the composite fiber was 28 μm, the physical properties were strength 4.8 cN / dtex, elongation 23%, and the single yarn diameter of the island component was 840 nm. The cross-sectional formability, spinnability and stretchability were very good.
The obtained composite fiber was cut to 1 mm to produce a cut fiber having an aspect ratio of 1190. As a matrix component, 14.3 wt% of composite fiber was added to an ethylene-propylene-diene elastomer (EPDM, SP value 8.0 (cal / cm ³ ) ^1/2 ) so that the fiber concentration would be 10 wt%, and 140 ° C. After kneading, adding a vulcanizing agent, kneading and molding again, and vulcanizing, a fiber-reinforced composite elastomer molded product was obtained. As a result of observing the dispersion state of the ultrafine single fibers in the molded product, the PET fibers of about 900 nm are uniformly dispersed. When the surface of the flat plate obtained by molding is observed, the fibers are completely opened and the surface is smooth. there were.

[Example 4]
As a sea component, a linear low density polyethylene having a melting viscosity of 1700 poise at a melting point of 124 ° C., 280 ° C., 1000 sec ⁻¹ [Sumikasen L GA801, manufactured by Sumitomo Chemical Co., Ltd., melt flow rate 20 g / 10 min, SP value 8 .4 (cal / cm ³ ) ^1/2 ] and PET having a melting viscosity of 900 poise at an melting point of 275 ° C. and 280 ° C. of 1000 sec ⁻¹ as an island component [SP value 10.7 (cal / cm ³ ) ^1/2 In the same manner as in Example 1, a multifilament drawn yarn (composite fiber) was obtained.
The diameter of the composite fiber was 28 μm, the physical properties were 4.9 cN / dtex in strength, the elongation was 25%, and the single yarn diameter of the island component was 840 nm. The cross-sectional formability, spinnability and stretchability were very good.
The obtained composite fiber was cut to 1 mm to produce a cut fiber having an aspect ratio of 1190. As a matrix component, 14.3 wt% of composite fiber was added to an ethylene-propylene-diene elastomer (EPDM, SP value 8.0 (cal / cm ³ ) ^1/2 ) so that the fiber concentration would be 10 wt%, and 140 ° C. After kneading, adding a vulcanizing agent, kneading and molding again, and vulcanizing, a fiber-reinforced composite elastomer molded product was obtained. As a result of observing the dispersion state of the ultrafine single fibers in the molded product, the PET fibers of about 900 nm are uniformly dispersed. When the surface of the flat plate obtained by molding is observed, the fibers are completely opened and the surface is smooth. there were.

[Comparative Example 1]
Ny6 having a melt viscosity of 1200 poise and an SP value of 11.0 (cal / cm ³ ) ^1/2 at a melting point of 223 ° C. and 270 ° C. 1000 sec ⁻¹ is used as the sea component, and a melting point of 132 ° C. and 270 ° C. 1000 sec ⁻ as the island component. melt viscosity at ¹ using 1100Poise, SP values 8.4 (cal ^/ cm ^{3) 1/2} a is high-density polyethylene [Japan polyethylene Corp. "Novatec HD HE495", melt flow rate 20 g / 10 min] and In the same manner as in Example 1, the spinning temperature was changed to 270 ° C. to obtain a multifilament drawn yarn (composite fiber).
The diameter of the composite fiber was 28 μm, the physical properties were strength 4.5 cN / dtex, elongation 20%, and the single yarn diameter of the island component was 800 nm. The cross-sectional formability, spinnability and stretchability were good.
The obtained composite fiber was cut into 1 mm, and a cut fiber having an aspect ratio of about 1200 of ultrafine fibers that are island components was prepared. As a matrix component, 14.3 wt% of composite fiber was added to ethylene-propylene-diene elastomer (EPDM, SP value 8.0 (cal / cm ³ ) ^1/2 ) so as to have a fiber concentration of 10 wt%. A fiber reinforced elastomer molded product was obtained by kneading at 0 ° C., adding a vulcanizing agent and kneading and molding again, followed by vulcanization. The SP value relationship does not satisfy the above-mentioned relational expression, and the melting point of the island component is lower than the melting point of the sea component and close to the molding temperature. Therefore, the molded product is deformed by heat during kneading and the ultrafine fibers are uniformly dispersed. I could not get.

[Comparative Example 2]
As a sea component, a low-density polyethylene having a melting viscosity of 1300 poise at a melting point of 106 ° C., 280 ° C. and 1000 sec ⁻¹ [“Sumikasen G801” manufactured by Sumitomo Chemical Co., Ltd., melt flow rate 20 g / 10 min, SP value 8.4 (cal / Cm ³ ) ^1/2 ], and using PET [SP value 10.7 (cal / cm ³ ) ^1/2 ] having a melt viscosity of 900 poise at a melting point of 275 ° C., 280 ° C. and 1000 sec ⁻¹ as an island component, In the same manner as in Example 1, an attempt was made to obtain a multifilament drawn yarn (composite fiber). However, the single yarn was fused in the spinning process of the sea-island composite fiber, and a sample could not be collected.

[Comparative Example 3]
In Example 1, instead of the sea-island type composite fiber, PET long fiber (“P903AL BHT1670T250” manufactured by Teijin Fibers Ltd., average fiber diameter 24 μm, strength 7.2 cN / dtex, elongation 26%) was cut to 5 mm. The same procedure was performed except that the addition amount was changed to 10 wt%. As a result of observing the dispersion state of the fibers in the molded product in a cross section, the diameter of the PET component was 10 to 80 μm and dispersed in a non-uniform manner. Since the fiber opening was insufficient at the time of molding, the fiber diameter varied due to fusion or division. As a result of observing the surface of the molded product, many bundles of unopened fibers were seen, and the flat plate surface was rough.

  The fiber-reinforced elastomer molded product of the present invention is a fiber-reinforced elastomer molded product having a high concentration and excellent dispersibility using ultrafine organic fibers as reinforcing fibers, and is useful for reducing the weight of automobiles and electric / electronic parts.

Claims (2)

A fiber-reinforced elastomer molded article characterized by simultaneously adding the following requirements a) to d), wherein sea island-type composite short fibers are added to a matrix, and the sea components are melted to use the island components as reinforcing fibers.
a) The solubility parameter value (SP (s)) of the sea component of the sea-island type composite fiber, the solubility parameter value (SP (i)) of the island component, and the solubility parameter (SP (m)) of the matrix resin are represented by the following formula (1). , (2). (The unit of SP value is (cal / cm ³ ) ^1/2 )
0 ≦ | SP (s) −SP (m) | <| SP (i) −SP (m) | <5 (1)
0 ≦ | SP (s) −SP (m) | <| SP (i) −SP (s) | <5 (2)
b) the relationship of the island component of a melting point Tm (i) and the matrix of the molding temperature (℃) is, Tm (i) - it is the molding temperature ≧ 20 ° C..
c) The melt viscosity ratio (sea / island) of the sea component and the island component is 0.2-5.
d) The island component diameter is 10 to 5000 nm. The relationship between the melting point Tm (i) of the island component constituting the sea-island composite short fiber and the melting point Tm (s) of the sea component is Tm ( i ) -Tm ( s ) ≥20 ° C. Fiber reinforced elastomer molded product.