JP6107155B2 - Prepreg - Google Patents

Description

  The present invention relates to a prepreg comprising a reinforcing fiber and a polypropylene resin composition, and more particularly, to a prepreg in which the reinforcing fiber in the prepreg is a substantially continuous fiber.

  Fiber reinforced plastic (FRP) is widely used in sports equipment applications, aerospace applications and general industrial applications because of its light weight and excellent mechanical properties. The reinforcing fibers used in these FRPs include metal fibers such as aluminum fibers and stainless fibers, organic fibers such as aramid fibers and PBO fibers, inorganic fibers such as silicon carbide fibers, and carbon fibers. Carbon fiber is preferably used from the viewpoint of the balance of specific strength, specific rigidity and lightness.

  Here, as a typical form of FRP such as carbon fiber reinforced plastic (CFRP), a molded product obtained by press-molding a preform obtained by laminating a prepreg (a molding method in which defoaming and shaping under pressure) is performed. Can be mentioned. The prepreg is generally manufactured by impregnating a reinforcing fiber base material in which continuous reinforcing fibers are arranged in one direction or woven with a resin.

  In recent years, FRP using discontinuous reinforcing fibers that are excellent in shape following to complex shapes and can be molded in a short time has been proposed. Sheet molding compound (SMC) and glass mat substrate (GMT) Is a material suitable for press molding, but has problems such as low mechanical properties such as specific strength and specific rigidity and large variations in properties, and was unsatisfactory in practical performance as a structural material. .

  By the way, in recent years, the attention of fiber reinforced composite materials has increased, and the applications have been subdivided in various ways, and there is a need for molding materials with excellent moldability, handleability, and mechanical properties of the resulting molded products. In addition, industrially higher economic efficiency and productivity have become necessary. For example, fiber reinforced composite materials have been required to be lightweight and economical, and light weight olefin resins, especially propylene resins, have been used as matrix resins. It was difficult to obtain a molded article having poor interfacial adhesiveness and excellent mechanical properties. Among them, it is particularly difficult to obtain a molded product having excellent mechanical properties with a fiber having a poor surface reactivity such as carbon fiber.

  Therefore, attempts have been made to improve the interfacial adhesion between the carbon fiber and polypropylene by modifying the surface of the carbon fiber or sizing the carbon fiber. For example, Patent Document 1 discloses a resin composition using a carbon fiber sized by a polyfunctional compound and a terpene resin, and has excellent fiber dispersibility, moldability, and interfacial adhesion during injection molding. It is known that a molded product having excellent bending properties and impact resistance can be obtained.

  On the other hand, attempts have been made to improve the interfacial adhesion between carbon fibers and polypropylene by modifying the matrix resin by adding modified polypropylene. For example, modification by adding maleic anhydride-modified polypropylene is widely known (Patent Document 2, Patent Document 3), and adding a polyolefin resin modified with a polycarbodiimide group to further improve mechanical properties. Is known to improve the dispersibility of the carbon fiber and to obtain a molded product having excellent bending characteristics and impact resistance. (Patent Document 4)

  As shown above, modification of fiber reinforced polypropylene resin has been actively studied in recent years, and its use has been expanded along with higher performance of materials, but this has not been a problem so far. The issues that have become apparent. For example, in applications that are frequently used outdoors and may be exposed to wind and rain for a long period of time, such as automobile outer panels, water resistance is required in addition to excellent mechanical properties. A fiber reinforced polypropylene resin using a quality polypropylene resin has a problem that satisfactory water resistance cannot be obtained.

  However, with respect to the water resistance of fiber reinforced polypropylene resins, there have been few examples studied so far because the polypropylene resin as a base material has almost no water absorption. For example, although Non-Patent Document 1 reports that the strength of jute fiber reinforced polypropylene resin is significantly reduced at the time of water absorption, studies for improving water resistance deterioration are not sufficient, and fiber reinforced polypropylene type Regarding the improvement of the water resistance of the resin, it has been hardly studied so far, including Patent Documents 1 to 4 described above.

JP 2010-248482 A JP 2009-114435 A JP 2005-213478 A International Publication No. 2009/069649

J.Soc. Mat. Sci., Japan, Vol.51, No.7, pp.826-831, July 2002

  The present invention has been made against the background of such prior art problems. In other words, in addition to excellent adhesion between the reinforced fiber and the matrix resin, the reinforced fiber is substantially continuous, so it has excellent mechanical properties that are difficult to reach when using discontinuous fibers. It is an object of the present invention to provide a prepreg that can produce a molded product that can be produced and that can produce a molded product that is excellent in water resistance.

As a result of intensive studies to achieve the above object, the present inventors have found the following prepreg capable of achieving the above-described problems.
(1) A prepreg comprising reinforcing fibers (c) and a polypropylene resin composition, wherein the polypropylene resin composition contains at least a carbodiimide-modified polyolefin (a) and a polypropylene resin (b) The content of the carbodiimide group contained in the matrix resin component is 0.0005 to 140 mmol with respect to 100 g of the matrix resin component, and the reinforcing fiber (c) is sized by the polyfunctional compound (s), Further, the reinforcing fiber (c) in the prepreg is substantially a continuous fiber, and the strength retention represented by the following formula of a molded product obtained by molding the prepreg is 90% or more. Prepreg.
・ (Strength retention) = (Bending strength of water absorption sample) / (Bending strength of dry sample) × 100
(2) A prepreg comprising a reinforcing fiber (c) and a polypropylene resin composition, wherein the polypropylene resin composition contains at least a carbodiimide-modified polyolefin (a) and a polypropylene resin (b), ) 0.01-50 parts by mass, (b) 20-99 parts by mass, (c) 1-80 parts by mass (provided that the total of (b) and (c) is 100 parts by mass) And the reinforcing fiber (c) is sizing-treated with the polyfunctional compound (s), and the reinforcing fiber (c) in the prepreg is substantially a continuous fiber, and is obtained by molding the prepreg. A prepreg characterized by having a strength retention represented by the following formula of the product of 90% or more .
・ (Strength retention) = (Bending strength of water absorption sample) / (Bending strength of dry sample) × 100

  The prepreg of the present invention has good interfacial adhesion between the reinforcing fibers and the propylene resin, and the reinforcing fibers are substantially continuous fibers. Excellent molded products can be manufactured. Moreover, since the propylene-based resin is used, a molded product having excellent lightness can be obtained. The prepreg of the present invention can be applied to a wide range of industrial fields such as electric / electronic devices, OA devices, home appliances, robots, motorcycles or automobile parts, internal members, aircraft members, parts and housings.

  The prepreg of the present invention comprises at least carbodiimide-modified polyolefin (a), polypropylene resin (b), and reinforcing fiber (c). In the present invention, the reinforcing fiber (c) needs to be sized by the polyfunctional compound (s). Furthermore, in the present invention, the reinforcing fiber (c) in the prepreg needs to be a substantially continuous fiber.

  In the present invention, it is important to use the carbodiimide-modified polyolefin (a) and the reinforcing fiber (c) sized with a polyfunctional compound in order to obtain water resistance. In addition, it is important that the reinforcing fiber (c) is a substantially continuous fiber in order to exhibit extremely excellent mechanical properties. First, these components will be described.

  In the prepreg of the present invention, it is preferable that the reinforcing fiber base material is impregnated with a polypropylene resin composition containing at least the component (a) and the component (b). The prepreg includes a resin semi-impregnated base material (semi-preg: hereinafter referred to as semi-impregnated prepreg) which is integrated in a state where the resin is not completely impregnated into the reinforcing fiber base material in addition to the resin fiber base completely impregnated with the resin May also be included). The prepreg is preferably in the form of a sheet.

  In the present specification, unless otherwise specified, in the term including fibers or fibers (for example, “fiber direction”), the fibers represent reinforcing fibers. In the present specification, the continuous fiber refers to a reinforcing fiber having a fiber length of 100 mm or more.

<Carbodiimide-modified polyolefin (a)>
The carbodiimide-modified polyolefin (a) is obtained by reacting a polyolefin resin (A) having a group that reacts with a carbodiimide group and a carbodiimide group-containing compound (B). Specifically, a method such as melt-kneading both can be used.

  Below, the example in the case of melt-kneading is shown. As a method of melt-kneading the polyolefin resin (A) having a group that reacts with a carbodiimide group and the carbodiimide group-containing compound (B), the polyolefin resin (A) having a group that reacts with a carbodiimide group and a carbodiimide group containing Compound (B) is charged simultaneously or sequentially into, for example, a Henschel mixer, V-type blender, tumbler blender, ribbon blender, etc., and then kneaded, and then single screw extruder, multi-screw extruder, kneader, Banbury mixer, etc. The method of melt kneading can be exemplified. Among these, it is preferable to use an apparatus excellent in kneading performance such as a multi-screw extruder, a kneader, and a Banbury mixer because a polymer composition in which each component is dispersed and reacted more uniformly can be obtained.

  When performing melt-kneading using an extruder, the polyolefin resin (A) having a group that reacts with a carbodiimide group and the carbodiimide group-containing compound (B) may be supplied from a hopper after being mixed in advance. These components may be supplied from a hopper, and other components may be supplied from a supply port installed at an arbitrary portion between the vicinity of the hopper portion and the tip of the extruder.

  The temperature at the time of melt-kneading the above components is set to be the highest melting point or higher among the melting points of the components to be mixed. Specifically, the melt kneading is performed preferably in the range of 150 to 300 ° C, more preferably 200 to 280 ° C, and still more preferably 230 to 270 ° C.

  The carbodiimide-modified polyolefin (a) used in the present invention is excellent in fluidity at 190 ° C or 230 ° C. The melt flow rate (MFR) at 190 ° C. or 230 ° C. under a load of 2.16 kg of the carbodiimide-modified polyolefin (a) is preferably 0.01 to 400 g / 10 minutes, more preferably 0.1 to 300 g / 10 minutes, Preferably it is the range of 1-200 g / 10min. Within such a range, the reinforcing fiber is excellent in reinforcing properties and dispersibility, which is preferable.

  In producing the carbodiimide-modified polyolefin (a), the ratio of the number of moles of the group reacting with the carbodiimide group in the polyolefin resin (A) having a group that reacts with the carbodiimide group and the number of moles of the carbodiimide group-containing compound (B). To a carbodiimide group at a blending ratio satisfying 1: 0.2 to 1.6, preferably 1: 0.4 to 1.3, more preferably 1: 0.7 to 1.1. This is preferable in that a carbodiimide-modified polyolefin (a) having high reaction efficiency between the compound having a group and (B) and excellent fluidity can be obtained.

  The carbodiimide-modified polyolefin (a) has a carbodiimide group content of preferably 1 to 200 mmol, more preferably 5 to 150 mmol, and still more preferably 10 to 100 mmol with respect to 100 g of the carbodiimide-modified polyolefin (a). When there is too little carbodiimide group content, the reinforcement effect of a reinforced fiber and the improvement effect of water-resistant deterioration property are small. On the other hand, if the carbodiimide group content is too high, the water deterioration resistance is good, but the molding processability is lowered, the reinforcing effect of reinforcing fibers and the improvement effect of dispersibility are not so much increased, and it is not economical. From this point of view, when the carbodiimide-modified polyolefin (a) is produced, the blending amount of the carbodiimide group-containing compound (B) is adjusted so that the carbodiimide group content in the carbodiimide-modified polyolefin (a) is within the above range. Good to do.

  Furthermore, in producing the carbodiimide-modified polyolefin (a), it is also important to control the reaction between the group that reacts with the carbodiimide group in the polyolefin resin (A) and the carbodiimide group in the carbodiimide group-containing compound (B). The progress of the reaction between the group that reacts with the carbodiimide group in the polyolefin resin (A) and the carbodiimide group in the carbodiimide group-containing compound (B) can be investigated, for example, by the following method.

After making a heat-pressed sheet of polyolefin resin (A) having a group that reacts with a carbodiimide group and a carbodiimide-modified polyolefin (a) obtained by the reaction, infrared absorption measurement is performed using an infrared absorption analyzer. To do. From the obtained chart, an absorption band (maleic anhydride) due to the peak intensity of the polyolefin resin (A) having a group that reacts with a carbodiimide group and the compound having a group that reacts with a carbodiimide group in the carbodiimide-modified polyolefin (a) Is used, the absorbance before and after the reaction of 1790 cm ⁻¹ ) is compared, and the reaction rate can be calculated using the following formula.
Reaction rate (%) = X / Y × 100
X = absorbance of a group reacting with a carbodiimide group before reaction (A) −absorbance of a group reacting with a carbodiimide group after reaction (a) Y = absorbance of a group reacting with a carbodiimide group before (A)

  The reaction rate calculated | required by the said method about the carbodiimide modified polyolefin (a) becomes like this. Preferably it is 40 to 100%, More preferably, it is 60 to 100%, More preferably, it exists in the range of 80 to 100%.

The carbodiimide-modified polyolefin (a) reacts with a group in which the carbodiimide group (N = C = N) of the carbodiimide group-containing compound (B) reacts with the carbodiimide group in the polyolefin resin (A) as described above. Although the carbodiimide group residue bonded to the polyolefin interacts with the reinforcing fiber, it contributes to reinforcement and dispersibility. This amount of carbodiimide residue can be grasped as the size of a peak due to the contraction vibration of the N = C = N group at 2130 to 2140 cm ⁻¹ in IR measurement.

  The carbodiimide-modified polyolefin (a) may include a polyolefin resin (A) having a group that reacts with two or more carbodiimide groups, or may include two or more carbodiimide group-containing compounds (B). .

  In addition, known process stabilizers, heat stabilizers, heat aging agents, and the like can be added to the carbodiimide-modified polyolefin (a) as long as the object of the present invention is not impaired.

<Polyolefin resin (A) having a group that reacts with a carbodiimide group>
The polyolefin resin (A) having a group that reacts with a carbodiimide group can be obtained by introducing a compound that reacts with a carbodiimide group into the polyolefin.

  Examples of the compound that reacts with the carbodiimide group include a compound having a group having an active hydrogen having reactivity with the carbodiimide group. Specifically, a compound having a group derived from carboxylic acid, amine, alcohol, thiol, etc. It is. Among these, compounds having groups derived from carboxylic acids are preferably used, and among them, unsaturated carboxylic acids and / or derivatives thereof are particularly preferable. In addition to a compound having a group having active hydrogen, a compound having a group that can be easily converted into a group having active hydrogen by water or the like can also be preferably used. Specific examples include compounds having an epoxy group or a glycidyl group. In the present invention, the compound that reacts with the carbodiimide group may be used alone or in combination of two or more.

  When an unsaturated carboxylic acid and / or a derivative thereof is used as a compound that reacts with a carbodiimide group, an unsaturated compound having at least one carboxylic acid group, an unsaturated compound having at least one carboxylic anhydride group, and derivatives thereof may be mentioned. it can. Examples of the unsaturated group include a vinyl group, a vinylene group, and an unsaturated cyclic hydrocarbon group. Specific examples include acrylic acid, methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, norbornene dicarboxylic acid, bicyclo [2,2,1] hept-2-ene. Examples thereof include unsaturated carboxylic acids such as -5,6-dicarboxylic acid, or acid anhydrides or derivatives thereof (for example, acid halides, amides, imides, and esters). Specific examples of the compound include maleenyl chloride, maleenylimide, maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid. Acid anhydride, dimethyl maleate, monomethyl maleate, diethyl maleate, diethyl fumarate, dimethyl itaconate, diethyl citraconic acid, dimethyl tetrahydrophthalate, bicyclo [2,2,1] hept-2-ene-5,6 Examples thereof include dimethyl dicarboxylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, aminoethyl methacrylate and aminopropyl methacrylate.

  Among these, maleic anhydride, (meth) acrylic acid, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic anhydride , Hydroxyethyl (meth) acrylate, glycidyl methacrylate, and aminopropyl methacrylate are preferred. Furthermore, it is a dicarboxylic anhydride such as maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic anhydride. It is particularly preferred. In particular, in the present invention, maleic anhydride is most preferable as the compound that reacts with the carbodiimide group.

  As a method for introducing a compound that reacts with a carbodiimide group into a polyolefin, various methods can be adopted. For example, a method of graft copolymerizing a compound that reacts with a carbodiimide group on a polyolefin main chain, Examples thereof include a method of radical copolymerizing a compound that reacts with a carbodiimide group. Hereinafter, the case of graft copolymerization and the case of radical copolymerization will be described specifically.

<Graft copolymerization>
The polyolefin resin (A) having a group that reacts with a carbodiimide group can be obtained by graft copolymerizing a compound having a group that reacts with a carbodiimide group with respect to the polyolefin main chain.

  The polyolefin used as the polyolefin main chain is a polymer mainly composed of an aliphatic α-olefin having 2 to 20 carbon atoms, a cyclic olefin, a non-conjugated diene, or an aromatic olefin, and preferably an α having 2 to 10 carbon atoms. -A polymer mainly composed of olefin, more preferably 2 to 8 α-olefin. These olefins which are the main components of the polyolefin main chain may be used alone or in combination of two or more. Here, the main component means that the content of the monomer unit in the polyolefin is usually 50 mol% or more, preferably 60 mol% or more, and more preferably 70 mol% or more. As the olefin as the main component, ethylene, propylene, 1-butene, 4-methyl-1-pentene, 3-methyl-1-butene, 1-hexene, 1-octene, tetracyclododecene, norbornene and styrene are preferable. Among them, propylene is particularly preferable. These can be used for both isotactic and syndiotactic structures, and there is no particular limitation on stereoregularity.

The density of the polyolefin used for graft modification is preferably 0.8 to 1.1 g / cm ³ , more preferably 0.8 to 1.05 g / cm ³ , and still more preferably 0.8 to 1 g / cm ³ . . The melt flow rate (MFR) of polyolefin at 190 ° C. or 230 ° C. under a load of 2.16 kg according to ASTM D1238 is usually 0.01 to 500 g / 10 minutes, preferably 0.05 to 300 g / 10 minutes, and more preferably 0.8. 1 to 100 g / 10 minutes. If the density of the polyolefin and the MFR are in this range, the density and MFR of the graft copolymer after modification will be approximately the same, and handling is easy.

  The crystallinity of the polyolefin used for graft modification is usually 2% or more, preferably 5% or more, and more preferably 10% or more. When the crystallinity is within this range, the graft copolymer after modification is excellent in handling.

  The number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of polyolefin used for graft modification is preferably 5,000 to 500,000, and more preferably 10,000 to 100,000. When the number average molecular weight (Mn) is within this range, the handling is excellent. The number average molecular weight in ethylene-based polyolefins is determined in terms of polyethylene if the comonomer amount is less than 10 mol%, and in terms of ethylene-propylene if the amount is 10 mol% or more (based on an ethylene content of 70 mol%). Is possible. Further, in the case of propylene-based polyolefin, the number average molecular weight is determined in terms of polypropylene if the comonomer amount is less than 10 mol%, and in terms of propylene-ethylene if the amount is 10 mol% or more (based on propylene content of 70 mol%). Is possible.

  The polyolefin as described above can be produced by any conventionally known method. For example, polymerization can be performed using a titanium-based catalyst, a vanadium-based catalyst, a metallocene catalyst, or the like. The polyolefin may be in any form of a resin and an elastomer, and both an isotactic structure and a syndiotactic structure can be used, and the stereoregularity is not particularly limited. Commercially available resins can be used as they are.

  When the polyolefin resin (A) having a group that reacts with a carbodiimide group is obtained by graft copolymerization, the polyolefin that becomes the graft main chain is combined with a compound that reacts with a carbodiimide group, and, if necessary, other ethylenic groups. Graft copolymerization of an unsaturated monomer or the like in the presence of a radical initiator.

  The method for grafting the compound that reacts with the carbodiimide group onto the polyolefin main chain is not particularly limited, and a known graft polymerization method such as a solution method or a melt-kneading method can be employed.

<Radical copolymerization>
The polyolefin resin (A) having a group that reacts with a carbodiimide group can also be obtained by radical copolymerization of a compound that reacts with an olefin and a carbodiimide group. As the olefin, it is possible to employ the same olefin as that used when forming the polyolefin to be the graft main chain described above. Moreover, the compound which reacts with a carbodiimide group is also as above-mentioned.

  The method for radical copolymerizing a compound that reacts with an olefin and a carbodiimide group is not particularly limited, and a known radical copolymerization method can be employed.

  Even when any copolymerization method such as graft copolymerization or radical copolymerization is adopted, the polyolefin resin (A) having a group that reacts with a carbodiimide group preferably satisfies the following conditions.

  The content of the group that reacts with the carbodiimide group in the polyolefin resin (A) having a group that reacts with the carbodiimide group is preferably 0.1 to 10% by mass, more preferably 0.1 to 3% by mass, and still more preferably. Is 0.1 to 2% by mass. If the content of the group that reacts with the carbodiimide group exceeds the above range, the group that reacts with the carbodiimide group is crosslinked by the carbodiimide group-containing compound (B), making it difficult to produce the carbodiimide-modified polyolefin (a). It may become. When the content of the group that reacts with the carbodiimide group is not more than the above range, the carbodiimide-modified polyolefin (a) can be produced, but the carbodiimide group-containing compound (B) serving as the skeleton of the carbodiimide-modified polyolefin (a) Since there are fewer bonded portions with the polyolefin resin (A), the reinforcing properties and dispersibility of the reinforcing fibers in the fiber reinforced polypropylene resin composition are reduced.

In order to prevent crosslinking of the polyolefin resin (A), the number average molecular weight of the polyolefin resin (A) is low, and (the number of moles of the group reacting with the carbodiimide group) / (polyolefin copolymer (A It is preferable that the molar ratio of (number of moles of molecular chain) is small. In other words, when there are not a plurality of groups that react with the carbodiimide group on the single molecular chain of the polyolefin resin (A), but a single group exists, the carbodiimide group (N) of the carbodiimide group-containing compound (B) = C = N) means that, when reacting with a group that reacts with the carbodiimide group of the polyolefin resin (A), it can be bonded without crosslinking and gelation.
Production of a carbodiimide-modified polyolefin (a) by controlling the number average molecular weight (Mn) of the polyolefin resin (A) having a group that reacts with a carbodiimide group and the content of the group having a group that reacts with a carbodiimide group In addition, it is possible to prevent the production stability from being lowered due to cross-linking, and to sufficiently improve the reinforcing property and dispersibility of the reinforcing fiber when the carbodiimide-modified polyolefin (a) is used as a fiber-reinforced polypropylene resin composition. Can be made. That is, the polyolefin resin (A) having a group that reacts with a carbodiimide group preferably satisfies the following formula (1).
0.1 <Mn / {(100-M) × f / M} <6 (1)
(Where
f: Molecular weight of a compound having a group that reacts with a carbodiimide group (g / mol)
M: Content of a compound having a group that reacts with a carbodiimide group (wt%)
Mn: Number average molecular weight of the polyolefin resin (A) having a group that reacts with a carbodiimide group. )

Further, from the viewpoint of production stability of not crosslinking, it is more preferably a range satisfying the following formula (2), and most preferably a range satisfying the formula (3).
0.3 <Mn / {(100-M) × f / M} <4 (2)
0.5 <Mn / {(100-M) × f / M} <2.5 (3)

  When the relationship between the number average molecular weight (Mn) of the polyolefin-based resin (A) having a group that reacts with a carbodiimide group and the group that reacts with a carbodiimide group is within the above range, crosslinking occurs when the carbodiimide-modified polyolefin (a) is produced. It becomes possible to manufacture stably without this.

  Further, when the polyolefin resin (A) having a group that reacts with a carbodiimide group is obtained by graft polymerization, the polyolefin as the graft main chain is a resin having a high ethylene content such as linear low density polyethylene. Compared with a resin having a large α-olefin copolymerization amount such as an ethylene-butene copolymer, it tends to be crosslinked at the time of production. Therefore, in order to use a resin having a high ethylene content as a graft main chain and to suppress crosslinking, a group that reacts with a carbodiimide group should be on one molecular chain of the polyolefin resin (A). It is preferable to adjust so that it exists in the singular.

  In addition, when the polyolefin that becomes the graft main chain is a resin that tends to have a low molecular weight due to thermal decomposition, such as polypropylene, the phenomenon of high viscosity due to crosslinking hardly occurs. Therefore, when using a resin that is easily pyrolyzed as the graft main chain, even if a plurality of groups that react with the carbodiimide group are present on one molecular chain of the polyolefin resin (A), the viscosity does not increase. In some cases, the carbodiimide-modified polyolefin (a) can be produced.

  The melt flow rate (MFR) at a load of 2.16 kg, 190 ° C. or 230 ° C. according to ASTM D1238 of a polyolefin resin (A) having a group that reacts with a carbodiimide group is preferably 0.01 to 500 g / 10 min, more preferably Is 0.05 to 300 g / 10 min. When it is in the above range, the carbodiimide-modified polyolefin (a) excellent in the reinforcing effect of reinforcing fiber and dispersibility can be obtained.

The density of the polyolefin resin (A) having a group that reacts with a carbodiimide group is preferably 0.8 to 1.1 g / cm ³ , more preferably 0.8 to 1.05 g / cm ³ , and still more preferably. 0.8-1 g / cm ³ .

<Carbodiimide group-containing compound (B)>
The carbodiimide group-containing compound (B) is preferably a polycarbodiimide having a repeating unit represented by the following general formula (4).
-N = C = N-R _1- (4)
[Wherein R ₁ represents a divalent organic group]

  The method for synthesizing the polycarbodiimide is not particularly limited. For example, the polycarbodiimide is synthesized by reacting an organic polyisocyanate in the presence of a catalyst that promotes the carbodiimidization reaction of the isocyanate group. Can do.

  The number average molecular weight (Mn) in terms of polystyrene determined by gel permeation chromatography (GPC) of the carbodiimide group-containing compound (B) is preferably 400 to 500,000, more preferably 1,000 to 10,000, still more preferably. Is 2,000 to 4,000. When the number average molecular weight (Mn) is in this range, a carbodiimide-modified polyolefin (a) having an excellent effect of improving the reinforcing property and dispersibility of the reinforcing fiber is obtained.

  Monocarbodiimide may be added to the carbodiimide group-containing compound (B), or a single carbodiimide group-containing compound may be used in combination.

  A commercially available carbodiimide group-containing compound can be used as it is. Examples of commercially available carbodiimide group-containing compounds include Carbodilite (registered trademark) HMV-8CA and Carbodilite (registered trademark) LA1 manufactured by Nisshinbo Industries, Ltd., Starbakuzol (registered trademark) P and Starbakuzol (registered trademark) P400 manufactured by Rhein Chemie. .

The carbodiimide group content in the carbodiimide group-containing compound (B) and the obtained carbodiimide-modified polyolefin (a) can be measured by ¹³ C-NMR, IR, titration method, etc., and can be grasped as a carbodiimide equivalent. Peaks of 130 to 142 ppm are observed with ¹³ C-NMR and 2130 to 2140 cm ⁻¹ with IR.

^{The 13} C-NMR measurement is performed as follows, for example. That is, 0.35 g of a sample is dissolved by heating in 2.0 ml of hexachlorobutadiene. After this solution is filtered through a glass filter (G2), 0.5 ml of deuterated benzene is added and charged into an NMR tube having an inner diameter of 10 mm. And ¹³ C-NMR measurement is performed at 120 degreeC using the JEOL GX-500 type | mold NMR measuring apparatus. The number of integration is 10,000 times or more.

The IR measurement is performed as follows, for example. That is, after the sample was heat-pressed at 250 ° C. for 3 minutes to prepare a sheet, an infrared spectrophotometer (manufactured by JASCO Corporation, FT-IR 410 type) was used for the transmission method to detect the infrared of the sheet. Measure the absorption spectrum. The measurement conditions are a resolution of 2 cm ⁻¹ and an integration count of 32 times.

  The infrared absorption spectrum in the transmission method is inversely proportional to the sample thickness, as shown by Lambert-Beer's law, and the absorbance itself does not represent the concentration of carbodiimide groups in the sample. Therefore, in order to measure the carbodiimide group content, it is necessary to equalize the thickness of the sample to be measured or to standardize the peak intensity of the carbodiimide group using an internal standard peak.

When measuring the carbodiimide group content of the carbodiimide-modified polyolefin (a) by IR measurement, IR measurement is performed using a sample whose carbodiimide group concentration is known in advance, and the absorbance of the peak appearing at 2130 to 2140 cm ⁻¹ A calibration curve is created using the absorbance ratio of the internal standard peak, and the measured value of the sample is substituted into the calibration curve to obtain the concentration.

  As the internal standard peak, a peak derived from a polypropylene skeleton may be used, or an internal standard substance may be mixed in advance so that the concentration in the sample becomes constant and used for measurement.

<Polypropylene resin (b)>
The polypropylene resin (b) used in the present invention is a so-called unmodified polypropylene resin, which is a homopolymer of propylene or at least one selected from propylene and α-olefin, conjugated diene, non-conjugated diene, and the like. A copolymer is mentioned.

  Examples of the α-olefin include ethylene, 1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-hexene, and 4,4 dimethyl. Examples include α-olefins having 2 to 12 carbon atoms excluding propylene such as -1-hexene, 1-nonene, 1-octene, 1-heptene, 1-hexene, 1-decene, 1-undecene and 1-dodecene. Examples of the conjugated diene or non-conjugated diene include butadiene, ethylidene norbornene, dicyclopentadiene, 1,5-hexadiene, and the like. These other monomers can be used alone or in combination of two or more.

  Examples of the skeleton structure of the polypropylene resin (b) include a propylene homopolymer, a random copolymer or a block copolymer containing one or more of propylene and the above-mentioned other monomers. it can. For example, polypropylene, ethylene / propylene copolymer, propylene / 1-butene copolymer, ethylene / propylene / 1-butene copolymer, and the like are preferable. In addition, the polypropylene resin (b) may contain copolymer components other than those described above as long as the effects of the present invention are not impaired.

<Reinforcing fiber (c)>
The reinforcing fiber (c) used in the present invention is not particularly limited. For example, high strength and high elastic modulus fibers such as carbon fiber, glass fiber, aramid fiber, alumina fiber, silicon carbide fiber, boron fiber, and metal fiber are used. Can be used. These may be used alone or in combination of two or more. Among these, it is preferable to use carbon fibers such as PAN-based carbon fibers, pitch-based carbon fibers, and rayon-based carbon fibers. From the viewpoint of the balance between the strength and elastic modulus of the obtained molded product, PAN-based carbon fibers are more preferable. For the purpose of imparting conductivity, reinforcing fibers coated with a metal such as nickel, copper, or ytterbium can also be used.

  Further, as the carbon fiber, the surface oxygen concentration ratio [O / C], which is the ratio of the number of atoms of oxygen (O) and carbon (C) on the fiber surface measured by X-ray photoelectron spectroscopy, is 0.05-0. 5 is preferable, more preferably 0.08 to 0.4, and still more preferably 0.1 to 0.3. When the surface oxygen concentration ratio is 0.05 or more, the functional group amount on the surface of the carbon fiber can be secured, and a stronger adhesion to the thermoplastic resin can be obtained. Moreover, although there is no restriction | limiting in particular in the upper limit of surface oxygen concentration ratio, it can illustrate to 0.5 or less from the balance of the handleability and productivity of carbon fiber.

The surface oxygen concentration ratio of the carbon fiber is determined by X-ray photoelectron spectroscopy according to the following procedure. First, a carbon fiber bundle from which a sizing agent or the like adhering to the carbon fiber surface is removed with a solvent is cut into 20 mm, and is spread and arranged on a copper sample support, and then the inside of the sample chamber is set to 1 × 10 ⁸ Torr. keep. A1Kα1 and 2 are used as the X-ray source, and the kinetic energy value (KE) of the main peak of C1s is adjusted to 1202 eV as the correction value of the peak accompanying charging during measurement. The C1s peak area is expressed as K.S. E. Is obtained by drawing a straight base line in the range of 1191 to 1205 eV. The O1s peak area is expressed as K.I. E. Is obtained by drawing a straight base line in the range of 947 to 959 eV. The surface oxygen concentration ratio is calculated as an atomic number ratio from the ratio of the O1s peak area to the C1s peak area using a sensitivity correction value unique to the apparatus. As an X-ray photoelectron spectroscopy apparatus, model ES-200 manufactured by Kokusai Electric Inc. is used, and the sensitivity correction value is set to 1.74.

  The means for controlling the surface oxygen concentration ratio [O / C] to 0.05 to 0.5 is not particularly limited. For example, techniques such as electrolytic oxidation, chemical oxidation, and vapor phase oxidation are used. Among these, electrolytic oxidation treatment is preferable.

  The average fiber diameter of the reinforcing fibers is not particularly limited, but is preferably in the range of 1 to 20 μm and in the range of 3 to 15 μm from the viewpoint of mechanical properties and surface appearance of the obtained molded product. More preferred. There is no restriction | limiting in particular in the number of single yarns when it is set as a reinforced fiber bundle, It is preferable to use within the range of 100-350,000, and especially within the range of 1,000-250,000. Further, from the viewpoint of productivity of reinforcing fibers, those having a large number of single yarns are preferable, and it is preferable to use them within the range of 10,000 to 100,000.

  In the present invention, the reinforcing fiber (c) needs to be sized by the polyfunctional compound (s).

<Polyfunctional compound (s)>
Although it does not specifically limit as a polyfunctional compound (s), The compound which has 2 or more functional groups, such as an epoxy group, a carboxyl group, an amino group, and a hydroxy group, can be used. These may be used alone or in combination of two or more. When a compound having less than two functional groups in one molecule is used, the adhesion between the reinforcing fiber and the matrix resin and the water deterioration resistance are reduced.
Therefore, it is essential that the number of functional groups is 2 or more in one molecule, and more preferably 3 or more. That is, as the polyfunctional compound, a compound having a trifunctional or higher functional group is preferably used.

  Specific examples of the polyfunctional compound include polyfunctional epoxy resins, polyethyleneimine, acid-modified polypropylene, neutralized acid-modified polypropylene, aminoethylated acrylic polymer, and polyvinyl alcohol.

  Examples of the polyfunctional epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, aliphatic epoxy resin, phenol novolac type epoxy resin and the like. Among these, an aliphatic epoxy resin that easily exhibits adhesiveness with the matrix resin is preferable. Usually, when an epoxy resin has many epoxy groups, since the crosslinking density after a crosslinking reaction becomes high, it tends to be a structure with low toughness. Therefore, even if it exists between a reinforced fiber and a matrix resin as a sizing agent, it is fragile and easily peels off, and the strength of the fiber reinforced composite material may not be exhibited. However, since the aliphatic epoxy resin has a flexible skeleton, the structure tends to have a high toughness even if the crosslinking density is high. When it exists between a reinforced fiber and matrix resin, in order to make it soft and it is hard to peel, it is easy to improve the intensity | strength of a fiber reinforced composite material, and preferable. Further, when used in combination with the carbodiimide-modified polyolefin (a), the water deterioration resistance is also excellent.

  Specific examples of the aliphatic epoxy resin include, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-diglycidyl ether compound, and 1,4- Examples include butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, and polyalkylene glycol diglycidyl ether. Also, in the polyglycidyl ether compound, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, arabitol polyglycidyl ether, trimethylolpropane polyglycidyl ether, trimethylolpropane Examples thereof include glycidyl ethers, pentaerythritol polyglycidyl ethers, polyglycidyl ethers of aliphatic polyhydric alcohols, and the like.

  Among the aliphatic epoxy resins, an aliphatic polyglycidyl ether compound having many highly reactive glycidyl groups is preferable. Among these, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyethylene glycol glycidyl ethers, and polypropylene glycol glycidyl ether are more preferable. Aliphatic polyglycidyl ether compounds are preferred because they have a good balance of flexibility, crosslink density and compatibility with the matrix resin and effectively improve adhesion.

  Polyethyleneimine is also preferable because it easily exhibits adhesiveness with the matrix resin. Polyethyleneimine is preferable because it has a flexible skeleton and is flexible and difficult to peel when it is present between the reinforcing fiber and the matrix resin, so that the strength of the fiber-reinforced composite material is easily improved. In addition, since polyethyleneimine is water-soluble, it can be easily applied uniformly to the reinforcing fiber surface by applying it to the reinforcing fiber as an aqueous solution.

  Examples of the acid-modified polypropylene and the neutralized product of the acid-modified polypropylene include a polymer main chain mainly composed of hydrocarbon such as propylene, a carboxyl group formed by an unsaturated carboxylic acid, or a metal salt thereof, ammonium And those having a side chain containing a salt. The polymer main chain may be a random copolymer obtained by copolymerizing propylene and an unsaturated carboxylic acid, or may be a graft copolymer obtained by grafting an unsaturated carboxylic acid on propylene. In addition, copolymerizable components such as α-olefin, conjugated diene, and non-conjugated diene may be copolymerized. Acid-modified polypropylene and neutralized product of acid-modified polypropylene are flexible while having many functional groups in one molecule, and since the skeleton is the same polypropylene as the matrix resin, the compatibility with the matrix resin is high. It is preferable because it is easy to improve adhesiveness.

  Unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, isocrotonic acid, citraconic acid, allyl succinic acid, mesaconic acid, glutaconic acid, nadic acid, methyl nadic acid, tetrahydrophthalic acid And methyltetrahydrophthalic acid. In particular, maleic acid, acrylic acid or methacrylic acid is preferable because it is easy to cause a copolymerization reaction. Only one type of unsaturated carboxylic acid may be used for copolymerization with propylene or graft copolymerization with propylene, or two or more types of unsaturated carboxylic acids may be used. In addition, in the neutralized product of acid-modified polypropylene, at least some of the carboxyl groups are neutralized with metal cations such as Na, K, Li, Mg, Zn, Ca, Cu, Fe, Ba, Al, or ammonium ions. It is preferable.

  Moreover, since it has two or more functional groups, it is preferable that the amount of oxycarbonyl groups is 0.05-5 millimol equivalent per 1g of acid-modified polypropylene or neutralized product of acid-modified polypropylene. More preferably, it is 0.1-4 mmol equivalent, More preferably, it is 0.3-3 mmol equivalent. As a method for analyzing the content of the oxycarbonyl group as described above, in the case of a neutralized product, a method of quantitatively detecting a metal species forming a salt by ICP emission analysis can be mentioned. Moreover, the method of quantifying carbonyl carbon using IR, NMR, elemental analysis, etc. is mentioned. If the amount of the oxycarbonyl group is less than 0.05 mmol equivalent, the adhesiveness tends to be difficult to exhibit. If the amount exceeds 5 mmol equivalent, the acid-modified polypropylene or the neutralized product of the acid-modified polypropylene may be fragile.

  Here, the sizing treatment of the reinforcing fiber (c) with the polyfunctional compound (s) indicates that the polyfunctional compound (s) is attached to the surface of the reinforcing fiber (c). By applying the polyfunctional compound as a sizing agent to the reinforcing fiber, even if the addition amount is small, the adhesiveness of the reinforcing fiber surface and the composite overall characteristics can be effectively improved.

  In order to acquire the said effect, it is preferable that a sizing agent exists in the interface of a reinforced fiber and a matrix resin in a fiber reinforced polypropylene resin composition. Therefore, it is considered that the polyfunctional compound (s) adheres to the entire periphery of the reinforcing fiber (c) and covers the reinforcing fiber. However, even if a part of the reinforcing fiber that is not coated is present, the effect of the present invention may be exhibited if the surrounding coated part has sufficient adhesiveness.

  The sizing agent adhesion amount is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.05% by mass or more and 5% by mass or less, and more preferably 0.1% by mass or more and 2% by mass with respect to the mass of the reinforcing fiber alone. % Or less is more preferable. If it is less than 0.01% by mass, the effect of improving adhesiveness is hardly exhibited because the ratio of the non-adhered part of the sizing agent is increased, and if it exceeds 10% by mass, the physical properties of the matrix resin may be lowered.

  The sizing agent also includes other components such as bisphenol-type epoxy compounds, linear low molecular weight epoxy compounds, polyethylene glycol, polyurethane, polyester, emulsifiers and surfactants, viscosity adjustment, improved scratch resistance, improved fuzz resistance, It may be added for the purpose of improving the focusing property and improving the high-order workability.

  There are no particular restrictions on the means for applying the sizing agent, but there are, for example, a method of immersing in a sizing liquid through a roller, a method of contacting a roller to which the sizing liquid is adhered, and a method of spraying the sizing liquid in a mist form. . Moreover, although either a batch type or a continuous type may be sufficient, the continuous type which has good productivity and small variations is preferable. At this time, it is preferable to control the sizing solution concentration, temperature, yarn tension, and the like so that the amount of the sizing agent active ingredient attached to the reinforcing fiber is uniformly attached within an appropriate range. Moreover, it is more preferable to vibrate the reinforcing fiber with ultrasonic waves when applying the sizing agent.

  The drying temperature and drying time after application of the sizing agent are adjusted according to the amount of the compound attached. From the viewpoint of completely removing the solvent used for applying the sizing agent, shortening the time required for drying, and preventing thermal deterioration of the sizing agent, the drying temperature is preferably 150 ° C. or higher and 350 ° C. or lower, It is more preferable that the temperature is 180 ° C. or higher and 250 ° C. or lower.

  Examples of the solvent used for the sizing agent include water, methanol, ethanol, dimethylformamide, dimethylallylacetamide, and acetone. Water is preferable from the viewpoint of easy handling and disaster prevention. Therefore, when using a compound insoluble or hardly soluble in water as a sizing agent, it is preferable to add an emulsifier or a surfactant and disperse in water. Specific examples of the emulsifier or surfactant include styrene-maleic anhydride copolymer, olefin-maleic anhydride copolymer, naphthalene sulfonate formalin condensate, anionic emulsifier such as sodium polyacrylate, Cationic emulsifiers such as polyethyleneimine and polyvinylimidazoline, nonionic emulsifiers such as nonylphenol ethylene oxide adduct, polyvinyl alcohol, polyoxyethylene ether ester copolymer, sorbitan ester ethyl oxide adduct, and the like can be used. A nonionic emulsifier having a small interaction is preferable because it hardly inhibits the adhesive effect of the polyfunctional compound.

  In the present invention, the reinforcing fiber constituting the prepreg is not particularly limited in form and shape as long as it is substantially a continuous fiber. For example, a continuous fiber bundle may be aligned in one direction, or a continuous fiber. A so-called reinforced fiber cloth may be used. From the viewpoint of relatively easy resin impregnation and continuous production, a preferred shape is one in which continuous fiber bundles are aligned in one direction.

  In addition to the components (a), (b), (c) and (s), the prepreg of the present invention may contain other fillers and additives as long as the object of the present invention is not impaired. . Both fillers and additives refer to components used to improve various properties of the prepreg and molded articles obtained from the prepreg. The filler means a solid component other than the reinforcing fiber that is present in the prepreg without being compatible with the matrix resin. The additive means a component that is compatible with a matrix resin other than the matrix resin.

  Examples of the filler include inorganic fillers and organic fillers. Examples of inorganic fillers include calcium oxide, magnesium oxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium sulfate, barium sulfate, calcium sulfite, and talc. , Mica, clay, dolomite, basic magnesium carbonate and the like. Examples of the organic filler include particulate thermosetting resin, wood powder, cork powder, rice husk powder, refined pulp, straw, paper, cotton, rayon, sufu, cellulose, and coconut shell powder.

  Examples of additives include flame retardants, conductivity imparting agents, crystal nucleating agents, UV absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorants, anti-coloring agents, thermal stabilizers, mold release agents Agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, antifoaming agents, or coupling agents.

  Here, in 1st invention of this invention, content of the carbodiimide group contained in the matrix resin component in a prepreg needs to be 0.0005-140 mmol with respect to 100 g of resin components, Preferably it is 0.001. It is -100 mmol, More preferably, it is 0.01-60 mmol. If the content of the carbodiimide group is less than 0.0005 mmol with respect to 100 g of the matrix resin component, water resistance cannot be obtained, and the resulting molded article has low mechanical properties. Further, when the content of the carbodiimide group is more than 140 mmol with respect to 100 g of the matrix resin component, the strength improvement effect with respect to the content of the carbodiimide group does not increase so much and it is not economical.

  Here, the matrix resin component refers to a component made of an organic substance other than the reinforcing fiber and filler in the prepreg. For example, as a component essential to the present invention, a mixture of the component (a), the component (b) and the component (s) is the matrix resin component.

  Moreover, when the prepreg of this invention contains the additive which consists of organic substance in addition to the component essential to this invention, it defines as matrix resin also including the additive which consists of organic substance.

In addition, content of the carbodiimide group contained in the matrix resin component in a prepreg can also be calculated from the composition of the used raw material. Moreover, when calculating | requiring from a prepreg, the resin composition component in a prepreg can be melt | dissolved and isolate | separated and it can also measure by IR, < ¹³ > C-NMR, a titration method etc. as mentioned above.

  Moreover, in 2nd invention of this invention, when the total of (b) and (c) is 100 mass parts about content of each component in a prepreg, carbodiimide modified polyolefin (a) is 0.01 To 50 parts by mass, preferably 0.05 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and 20 to 99 parts by mass, preferably 30 to 95 parts by mass, more preferably 30 to 95 parts by mass of the polypropylene resin (b). 50 to 90 parts by mass, 1 to 80 parts by mass, preferably 5 to 70 parts by mass, and more preferably 10 to 50 parts by mass of the reinforcing fiber (c) sized by the polyfunctional compound (s). It is necessary to be a composition. The effects of the present invention can also be achieved by using the content of each component in the prepreg within this range.

  When the carbodiimide-modified polyolefin (a) is less than 0.01 parts by mass, water resistance cannot be obtained, and the resulting molded article has low mechanical properties. On the other hand, when the amount is more than 50 parts by mass, the effect of improving the mechanical properties of the molded product with respect to the content of the carbodiimide-modified polyolefin does not increase so much and is not economical.

  If the reinforcing fiber (c) sized by the polyfunctional compound is less than 1 part by mass, the resulting molded article may have insufficient mechanical properties, and if it exceeds 80 parts by mass, fluidity may be caused during molding. It may decrease and may not be shaped into a complex shape.

  Of these, the polypropylene resin (b) is 20 to 99 parts by mass, preferably 30 to 95 parts by mass, and more preferably 50 to 90 parts by mass. By using within this range, the effect of the present invention can be obtained. Can be achieved.

  In the second aspect of the present invention, the carbodiimide-modified polyolefin (a) has a carbodiimide group content of preferably 100 to 200 mmol, more preferably 5 to 150 mmol, and still more preferably 10 to 100 mmol. is there. If the carbodiimide group content is too small, the reinforcing effect of the reinforcing fibers and the improvement effect of water resistance are small. On the other hand, if the amount is too large, the deterioration resistance against water is good, but the molding processability is lowered, and the reinforcing effect of the reinforcing fibers is not so high, which is not economical. Of course, if the conditions of both the first and second aspects of the present invention are satisfied, the effects of the present invention can be further enhanced.

  In the prepreg of the present invention, it is preferable that the polypropylene-based resin is impregnated in the reinforcing fiber from the viewpoint of the handleability of the prepreg. The impregnation rate is preferably 30 to 100%, more preferably 40 to 100%, and still more preferably 50 to 100%. When the impregnation ratio is in a preferable range, a prepreg excellent in handleability and moldability is obtained.

There is no restriction | limiting in particular as a measuring method of an impregnation rate, For example, it can measure with the simple method shown below. First, a method of observing the cross section of the prepreg and calculating the total void area from the micrograph and dividing by the area of the reinforcing fiber, the thickness h0 of the prepreg at 23 ° C. and the thickness hc0 at 23 ° C. after press molding it And a method of obtaining from the ratio of the theoretical density obtained from the use ratio of each material and the bulk density of the prepreg, and the like. Here, the method of observing the thickness direction cross section of a prepreg and measuring and calculating the area of the space | gap part in a cross section and the area of the whole cross section is demonstrated concretely. That is, the prepreg is embedded with a thermosetting resin such as epoxy, the surface corresponding to the end of the cross section of the prepreg is polished, and a range of about 500 to 1000 μm in width is observed with an optical microscope or an electron microscope. In this method, the area of the impregnated portion and the portion of the portion not impregnated with the resin are obtained, and the resin impregnation rate is calculated by the following equation.
Resin impregnation rate (%) = 100 × (total area of the part impregnated with resin) / (cross-sectional area of the observation part of the prepreg).

  The prepreg of the present invention can be processed into a final product by various known molding methods.

  Examples of uses of the molded article obtained by using the prepreg of the present invention include, for example, “PC, display, OA equipment, mobile phone, personal digital assistant, facsimile, compact disc, portable MD, portable radio cassette, PDA (electronic notebook) Such as portable information terminals), video cameras, digital video cameras, optical equipment, audio, air conditioners, lighting equipment, entertainment equipment, toy products, other household appliances, etc., trays, chassis, interior members, or their cases Electrical and electronic equipment parts, civil engineering and construction material parts such as `` posts, panels, reinforcements '', `` various members, various frames, various hinges, various arms, various axles, various wheel bearings, various beams, propeller shafts, Suspension, accelerator or steering parts such as wheels, gearboxes " “Hood, roof, door, fender, trunk lid, side panel, rear end panel, upper back panel, front body, underbody, various pillars, various members, various frames, various beams, various supports, various rails, various hinges, etc. , Outer plate or body parts ”,“ bumper, bumper beam, molding, under cover, engine cover, current plate, spoiler, cowl louver, aero parts, etc. ”,“ instrument panel, seat frame, door trim, pillar trim, Interior parts such as handles and various modules "or" motor parts, CNG tank, gasoline tank, fuel pump, air intake, intake manifold, carburetor main body, carburetor spacer, each Piping, fuel systems such as various valves, exhaust systems, or intake system parts ", structural parts for motorcycles," others, alternator terminal, alternator connector, IC regulator, potentiometer base for light weather, engine coolant joint, Air conditioner thermostat base, heating hot air flow control valve, radiator motor brush holder, turbine vane, wiper motor related parts, distributor, starter switch, starter relay, window washer nozzle, air conditioner panel switch board, fuel related electromagnetic valve Coil, battery tray, AT bracket, headlamp support, pedal housing, protector, horn terminal, step motor rotor, lamp Sockets, lamp reflectors, lamp housings, brake pistons, noise shields, spare tire covers, solenoid bobbins, engine oil filters, igniter cases, scuff plates, fascias, etc., automobile parts, landing gear pods, winglets , Spoilers, edges, ladders, elevators, failings, ribs, etc. From the viewpoint of mechanical properties, it is preferably used for electrical and electronic equipment casings, civil engineering, building material panels, automotive structural parts, and aircraft parts.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(Various measurement methods)
First, measurement methods for various characteristics used in the reference examples, examples, and comparative examples will be described.

(1) Various physical properties measurement of modified polypropylene <Melt flow rate (MFR)>
Measurements were performed at 230 ° C. under a 2.16 kg load according to ASTM D1238.

<Number average molecular weight (Mn)>
The number average molecular weight (Mn) was measured by gel permeation chromatography (GPC). A gel permeation chromatograph Alliance GPC-2000 manufactured by Waters was used as a measuring device, and the measurement was performed as follows. The separation columns used were 2 TSKgel GMH6-HT and 2 TSKgel GMH6-HTL. The column size was 7.5 mm in diameter and 300 mm in length, and the column temperature was 140 ° C. As the mobile phase, o-dichlorobenzene (Wako Pure Chemical Industries) to which 0.025% by mass of BHT (Takeda Pharmaceutical) was added as an antioxidant was moved at 1.0 ml / min. The sample concentration was 15 mg / 10 mL, the sample injection amount was 500 microliters, and a differential refractometer was used as a detector. The molecular weight was calculated in terms of standard polystyrene. Standard polystyrene used was manufactured by Tosoh Corporation for molecular weights of Mw <1000 and Mw> 4 × 10 ⁶ , and used by Pressure Chemical Co. for 1000 ≦ Mw ≦ 4 × 10 ⁶ .

  In the measurement of the molecular weight of maleic anhydride-modified polypropylene, the molecular weight obtained with standard polystyrene as described above was converted to PP by a general calibration method. PS and PP Mark-Houwink coefficients used for conversion are described in the literature (J. Polym. Sci., Part A-2, 8, 1803 (1970), Makromol. Chem., 177, 213 (1976)). The value of was used.

<Carbodiimide group content>
The carbodiimide group content of the carbodiimide-modified polypropylene (a) was measured by applying an infrared spectrophotometer (manufactured by JASCO Corporation, FT-IR 410 type) after heat-pressing the sample at 250 ° C. for 3 minutes to produce a sheet. The infrared absorption spectrum of the sheet was measured by the transmission method and determined by substituting it into the following calibration curve. The measurement conditions were a resolution of 2 cm ⁻¹ and an integration count of 32 times.

Carbodilite (registered trademark) HMV-8CA was melt-mixed at a predetermined concentration in PP1 (polypropylene) described later in advance, and a sample for IR measurement was prepared in the same manner as described above, and used for preparing a calibration curve. The infrared absorption spectrum of each sample having a different concentration was measured, and the absorbance at 2120 cm ⁻¹ derived from the carbodiimide group was expressed as the absorbance at 1357 cm ⁻¹ (C—H bending vibration) derived from the polypropylene skeleton as an internal standard peak. The calibration curve was created by normalizing.

(2) Measurement of various physical properties of carbon fiber <Measurement of strand tensile strength and tensile modulus of carbon fiber>
A carbon fiber bundle was impregnated with a resin having the following composition, cured for 35 minutes at a temperature of 130 ° C., and then subjected to a tensile test based on JIS R7601 (1986). Measurement was performed on six strands, and the strand tensile strength and tensile elastic modulus were obtained as average values.
[Resin composition] (In brackets are manufacturers)
-3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate (ERL-4221, manufactured by Union Carbide) ... 100 parts by mass-Boron trifluoride monoethylamine (Stella Chemifa ( 3) parts by mass, acetone (Wako Pure Chemical Industries, Ltd.) ... 4 parts by mass.

<Measurement of O / C>
The surface oxygen concentration ratio of the carbon fiber was determined by X-ray photoelectron spectroscopy according to the following procedure. First, the carbon fiber bundle was cut to 20 mm, spread and arranged on a copper sample support, and the inside of the sample chamber was kept at 1 × 10 ⁸ Torr. Measurement was performed using A1Kα1,2 as the X-ray source. The kinetic energy value (KE) of the main peak of C1s was adjusted to 1202 eV as a peak correction value associated with charging during measurement. C1s peak area E. As a linear base line in the range of 1191 to 1205 eV. O1s peak area, E. As a linear base line in the range of 947 to 959 eV. From the ratio of the O1s peak area to the C1s peak area, O / C was calculated as the atomic ratio using the sensitivity correction value unique to the apparatus. As an X-ray photoelectron spectroscopy apparatus, Kokusai Denki Co., Ltd. model ES-200 was used, and the sensitivity correction value was set to 1.74.

(3) Measurement of various physical properties of prepreg <Fiber mass content of reinforcing fiber in prepreg (Wf)>
After measuring the mass W1 of the prepreg, the prepreg was heated in air at 500 ° C. for 1 hour to burn off the resin component, and the mass W2 of the remaining reinforcing fiber was measured.
Wf (%) = 100 × W2 / W1.

<Thickness of prepreg>
Under the measurement condition of 23 ° C., the two points X and Y in the prepreg are determined so that the linear distance XY is the longest, and the thickness is measured at each dividing point excluding both ends XY when the straight line XY is divided into ten equal parts, The average value was taken as the thickness of the prepreg.

<Resin impregnation rate of prepreg>
The thickness direction cross section of the prepreg was observed and measured as follows. The prepreg is embedded with an epoxy resin, the surface corresponding to the cross-sectional end of the prepreg is polished, and the prepreg thickness × width 500 μm range is measured using an ultra-deep color 3D shape measurement microscope VK-9500 (controller unit) / VK-9510 (measurement unit) ) (Manufactured by Keyence Co., Ltd.). In the photographed image, the area of the part impregnated with the resin and the area of the part not impregnated with the resin were obtained, and the resin impregnation rate was calculated by the following formula.
Resin impregnation rate (%) = 100 × area of the portion impregnated with resin / (thickness of prepreg × area of 500 μm width).

(4) Measurement of physical properties of molded product obtained using prepreg <Molding method of molded product used for 0 ° bending test and cutting of sample>
The prepreg was dried at 120 ° C. for 1 hour. This prepreg is stretched and laid in a 30cm x 30cm mold so that the reinforcing fibers are unidirectional, press-molded at a temperature of 200 ° C and a pressure of 30MPa for 5 minutes, cooled to 50 ° C while maintaining the pressure, and a thickness of 3mm. A plate-shaped molded product was obtained. The obtained unidirectional molded product was cut out in a direction parallel to the direction of the carbon fiber and a 0 ° bending test piece having a length of 130 ± 1 mm and a width of 25 ± 0.2 mm.

<Preparation of dry sample and water absorption sample>
A test piece for a bending test was cut out from the molded product by the above method and dried in a vacuum dryer to obtain a dried sample. A constant temperature water tank filled with purified water was adjusted to 85 ° C., and the dried test piece was immersed for 1 week to obtain a water absorption sample.

<0 ° bending test of molded products>
In accordance with ASTM D790 (1997), a support span was set to 100 mm using a three-point bending test jig (indenter 10 mm, fulcrum 10 mm), and bending strength was measured under test conditions of a crosshead speed of 5.3 mm / min. . As a testing machine, “Instron” (registered trademark) universal testing machine 4201 type (manufactured by Instron) was used. For the test pieces, the dry samples and water-absorbed samples prepared according to the method described in <Preparation of dried sample and water-absorbed sample> were used, and 10 test pieces were each tested, and the average value was calculated.

Judgment of bending strength was performed according to the following criteria, and A to C were set as acceptable.
A: 1250 MPa or more B: 1150 MPa or more and less than 1250 MPa C: 1000 MPa or more and less than 1150 MPa D: less than 1000 MPa.

Moreover, the strength retention (%) at the time of water absorption was calculated from the ratio of the bending strength of the water absorption sample and the bending strength of the dry sample.
(Strength retention) = (Bending strength of water absorption sample) / (Bending strength of dry sample) × 100

Determination of strength retention was performed according to the following criteria, and A to B were determined to be acceptable.
A: 95% or more B: 90% or more and less than 95% C: 80% or more and less than 90% D: less than 80%.

(Raw materials and their preparation)
The raw materials used in Reference Examples, Examples and Comparative Examples are shown below. Unless otherwise specified, commercially available products were used.

<Polyolefin>
PP1: Polypropylene (Random PP)
(Product name F327, manufactured by Prime Polymer, MFR (230 ° C) 7 g / 10 min)
PP2: Polypropylene (block PP)
(Product name: J707G, Prime Polymer, MFR (230 ° C.) 30 g / 10 min)
PP3: Polypropylene (homo PP)
(Product name J106G, Prime Polymer, MFR (230 ° C.) 15 g / 10 min)

<Sizing agent>
(S) -1: Glycerol triglycidyl ether (functional group: epoxy group, functional group number 3)
(S) -2: Bisphenol A type epoxy resin (epoxy group, functional group number 2)
(JER828 manufactured by Japan Epoxy Resin Co., Ltd.)
(S) -3: acid-modified polypropylene (carboxyl group, 5 functional groups)
(Acid-modified polypropylene emulsion manufactured by Maruyoshi Chemical Co., Ltd.)
(S) -4: polyglycerol polyglycidyl ether (epoxy group, 5 functional groups)
(“Denacol” (registered trademark) EX-521, manufactured by Nagase ChemteX Corporation)
(S) -7: Polyethyleneimine (amino group, functional group number 28)
(Polyethyleneimine Mn1,200 manufactured by Sigma-Aldrich)
(S) '-1: Polybutene (no functional group, 0 functional groups)
("Emawet" (registered trademark) 200E manufactured by NOF Corporation)

<Reinforcing fiber>
The reinforcing fiber used was adjusted according to Reference Example 7 shown later.

(Manufacture of polyolefin resin having groups that react with carbodiimide groups)
・ Reference Example 1
100 parts by mass of PP1 (manufactured by Prime Polymer, F327), 1 part by mass of maleic anhydride (manufactured by Wako Pure Chemical Industries, Ltd., hereinafter abbreviated as MAH), 2,5-dimethyl-2,5-bis (tert-butylper) Oxy) hexyne-3 (manufactured by NOF Corporation, trade name Perhexine (registered trademark) 25B) 0.25 part by mass was mixed, and a twin-screw kneader (Nippon Steel Works, TEX-30, L / D = 40, vacuum) Extruded at a cylinder temperature of 220 ° C., a screw rotation speed of 200 rpm, and a discharge rate of 80 g / min, to obtain maleic acid-modified polypropylene (hereinafter abbreviated as MAH-PP1). The obtained MAH-PP1 was dissolved in xylene, and then the obtained xylene solution was poured into acetone, whereby MAH-PP1 was reprecipitated and purified. The amount of maleic anhydride grafted was measured by IR and found to be 0.7% by mass. The number average molecular weight (Mn) was Mn 28,000 as measured by GPC.

Moreover, about MAH-PP1, the value of Mn / {(100-M) × f / M} is 2.0.
Where
f: Molecular weight of maleic anhydride 98 (g / mol)
M: maleic anhydride content 0.7 (wt%)
Mn: Number average molecular weight of MAH-PP1 28,000
It is.

・ Reference Example 2
In the production of maleic acid-modified polypropylene in Reference Example 1, the same procedure as in Reference Example 1 was carried out except that MAH was 0.05 parts by mass, perhexine 25B was 0.02 parts by mass, and the cylinder temperature of the biaxial kneader was 260 ° C. Thus, a maleic acid-modified polypropylene (hereinafter abbreviated as MAH-PP2) was obtained. The amount of maleic anhydride grafted on the obtained MAH-PP2 was measured by IR and found to be 0.03% by mass. The number average molecular weight (Mn) was Mn 29,000 as measured by GPC.

Moreover, about MAH-PP2, the value of Mn / {(100-M) × f / M} is 0.09.
Where
f: Molecular weight of maleic anhydride 98 (g / mol)
M: maleic anhydride content 0.03 (wt%)
Mn: Number average molecular weight of MAH-PP2 29,000
It is.

・ Reference Example 3
100 parts by mass of PP3 (manufactured by Prime Polymer Co., Ltd., J106G), 30 parts by mass of MAH, and 5 parts by mass of dicumyl peroxide (manufactured by NOF Corporation, trade name Park Mill (registered trademark) D) are mixed in a toluene solution. Reaction was performed for 5 hours to obtain maleic acid-modified polypropylene (hereinafter abbreviated as MAH-PP3). The amount of maleic anhydride grafted on the obtained MAH-PP3 was measured by IR and found to be 5.0% by mass. The number average molecular weight (Mn) was Mn 18,000 as measured by GPC. For MAH-PP3, the value of Mn / {(100-M) × f / M} is 10.
Where
f: Molecular weight of maleic anhydride 98 (g / mol)
M: maleic anhydride content 5.0 (wt%)
Mn: Number average molecular weight of MAH-PP2 18,000
It is.

(Production of carbodiimide-modified polypropylene)
Reference example 4
100 parts by mass of MAH-PP1 produced in Reference Example 1 and 8.8 parts by mass of a carbodiimide group-containing compound (manufactured by Nisshinbo Co., Ltd., trade name Carbodilite (registered trademark) HMV-8CA, carbodiimide group equivalent 278, number average molecular weight 2500). Mix and extrude using a twin-screw kneader (manufactured by Nippon Steel, TEX-30, L / D = 40, using a vacuum vent) at a cylinder temperature of 250 ° C., a screw rotation speed of 200 rpm, and a discharge rate of 80 g / min. A carbodiimide-modified polypropylene (hereinafter abbreviated as CDI-PP1) was obtained. The obtained CDI-PP1 had an MFR (230 ° C., 2.16 kg load) of 130 g / 10 min. According to IR analysis, the reaction rate was 100% because the maleic acid peak had disappeared, and the carbodiimide group content was 27 mmol / 100 g.

Reference example 5
In the same manner as in Reference Example 4, 100 parts by mass of MAH-PP2 produced in Reference Example 2 and 0.25 part by mass of a carbodiimide group-containing compound were mixed and extruded using a biaxial kneader, and carbodiimide-modified polypropylene (hereinafter referred to as CDI). -Abbreviated as PP2. The obtained CDI-PP2 had a carbodiimide group content of 0.09 mmol / 100 g.

Reference example 6
In the same manner as in Reference Example 4, 100 parts by mass of MAH-PP3 produced in Reference Example 3 and 150 parts by mass of a carbodiimide group-containing compound were mixed and extruded using a biaxial kneader, and carbodiimide-modified polypropylene (hereinafter, CDI-PP3). Abbreviated). The extruded resin was somewhat gelled. The obtained CDI-PP3 had a carbodiimide group content of 220 mmol / 100 g.

(Manufacture of carbon fiber)
Reference example 7
A continuous carbon fiber (hereinafter abbreviated as CF-1) having a total number of single yarns of 12,000 was obtained by spinning, firing and surface oxidation treatment using a copolymer containing polyacrylonitrile as a main component. . The characteristics of this continuous carbon fiber were as follows.
Single fiber diameter: 7μm
Mass per unit length: 0.8 g / m
Specific gravity: 1.8
Surface oxygen concentration ratio [O / C]: 0.06
Strand tensile strength: 4900 MPa
Tensile modulus: 230 GPa.

(Sizing agent provided)
Reference example 8
A sizing agent mother liquor in which the sizing agent was dissolved or dispersed in water was prepared, the sizing agent was applied to the reinforcing fiber prepared in Reference Example 7 by a dipping method, and drying was performed at 230 ° C. The concentration of the sizing agent mother liquor was adjusted so that the adhesion amount of the sizing agent was 1.0% by mass with respect to the mass of the reinforcing fiber.

(Preparation and evaluation of prepreg and molded product)
Example 1
A crosshead die processed into a corrugated shape through which a continuous bundle of reinforcing fibers can pass was attached to the tip of a single screw extruder. Next, a continuous carbon fiber bundle obtained by sizing the CF-1 obtained according to Reference Example 7 using (s) -1 (glycerol triglycidyl ether) as a polyfunctional compound according to Reference Example 8 was used at 5 m / Polypropylene resin mixture melted at 230 ° C. from the extruder into the die while being pulled through the crosshead die at a rate of 4 minutes (4 pieces of CDI-PP1 prepared according to Reference Example 1 and Reference Example 4 as component (a)) 7 parts by mass and 47.1 parts by mass of PP2 as the component (b)) are discharged, and the resin mixture is adhered to the continuous fiber bundle, and further squeezed with a roller while heating to 230 ° C. Was impregnated into a continuous fiber bundle. The melt impregnated product was cooled with a nip roller at 60 ° C. and wound up to prepare a tape-shaped prepreg. Under the present circumstances, the supply amount of the propylene-type resin mixture was adjusted so that the mass content rate of the carbon fiber in a prepreg might be 50.3%. Component (c) was included in 52.9 parts by mass, and the total of component (b) and component (c) was 100 parts by mass.

  The content of the carbodiimide group contained in the resin component in the prepreg calculated from the composition of the raw material used was 2.42 mmol with respect to 100 g of the matrix resin component. About the obtained prepreg, the resin impregnation rate was evaluated. The evaluation results are shown in Table 1.

  Next, the obtained tape-shaped prepreg is cut to a length of 30 cm, and laid in a 30 cm × 30 cm mold so that the reinforcing fibers are aligned in one direction, and press-molded at a temperature of 200 ° C. and a pressure of 30 MPa for 5 minutes. The plate-shaped molded product having a thickness of 3 mm was obtained by cooling to 50 ° C. while maintaining the pressure. About the obtained molded article, according to said molded article evaluation method, the bending strength of the dry sample and the bending strength of the water absorption sample were evaluated. The evaluation results are shown in Table 1.

Example 2
A prepreg was obtained and evaluated for molding in the same manner as in Example 1 except that (s) -2 (bisphenol A type epoxy resin) was used in place of (s) -1 as the polyfunctional compound. The characteristic evaluation results are shown in Table 1.

Example 3
A prepreg was obtained and evaluated for molding in the same manner as in Example 1 except that (s) -3 (acid-modified polypropylene) was used instead of (s) -1 as the polyfunctional compound. The characteristic evaluation results are shown in Table 1.

Example 4
A prepreg was obtained and evaluated for molding in the same manner as in Example 1 except that (s) -4 (polyglycerol polyglycidyl ether) was used as the polyfunctional compound instead of (s) -1. The characteristic evaluation results are shown in Table 1.

Example 5
A prepreg was obtained and evaluated for molding in the same manner as in Example 1, except that (s) -7 (polyethyleneimine) was used instead of (s) -1 as the polyfunctional compound. The characteristic evaluation results are shown in Table 1.

Example 6
A prepreg was obtained and evaluated for molding in the same manner as in Example 1 except that CDI-PP1 was changed to 2.4 parts by mass as the component (a) and PP2 was changed to 48.2 parts by mass as the component (b). Component (c) was contained in 51.8 parts by mass, and the total of component (b) and component (c) was 100 parts by mass. The characteristic evaluation results are shown in Table 1.

-Example 7
A prepreg was obtained and evaluated for molding in the same manner as in Example 1 except that CDI-PP1 was changed to 9.0 parts by mass as component (a) and PP2 was changed to 44.9 parts by mass as component (b). Component (c) was included in 55.1 parts by mass, and the total of component (b) and component (c) was 100 parts by mass. The characteristic evaluation results are shown in Table 1.

Example 8
(A) A prepreg was obtained in the same manner as in Example 1 except that 4.7 parts by mass of CDI-PP2 prepared according to Reference Example 2 and Reference Example 5 was used instead of CDI-PP1, and molding evaluation was performed. Was done. The characteristic evaluation results are shown in Table 1.

Example 9
(A) A prepreg was obtained in the same manner as in Example 1 except that 4.7 parts by mass of CDI-PP3 prepared according to Reference Example 3 and Reference Example 6 was used instead of CDI-PP1. Was done. The characteristic evaluation results are shown in Table 1.

Comparative example 1
CF-1 obtained in Reference Example 7 is used as it is without adhering sizing, (a) for CDI-PP1 as component 4.7 parts by weight, and (b) for PP2 47.3 parts by weight Except for the above, a prepreg was obtained in the same manner as in Example 1 and evaluated for molding. Component (c) was included in 52.7 parts by mass, and the total of component (b) and component (c) was 100 parts by mass. The characteristic evaluation results are shown in Table 2.

Comparative example 2
A prepreg was obtained in the same manner as in Example 1 except that (s) ′-1 (polybutene) having no functional group was used as a sizing agent instead of the polyfunctional compound (s) -1, and molding evaluation was performed. Was done. The characteristic evaluation results are shown in Table 2.

Comparative example 3
A prepreg was obtained in the same manner as in Comparative Example 2 except that CDI-PP1 was changed to 9.0 parts by weight as component (a) and PP2 was changed to 44.9 parts by weight as component (b). I did it. Component (c) was included in 55.1 parts by mass, and the total of component (b) and component (c) was 100 parts by mass. The characteristic evaluation results are shown in Table 2.

Comparative example 4
(A) A prepreg was obtained and evaluated for molding in the same manner as in Example 1 except that 4.7 parts by mass of MAH-PP1 prepared according to Reference Example 1 was used instead of component CDI-PP1. The characteristic evaluation results are shown in Table 2.

Comparative example 5
A prepreg was obtained and evaluated for molding in the same manner as in Comparative Example 4 except that MAH-PP1 was changed to 9.0 parts by mass and PP2 was changed to 44.9 parts by mass as the component (b). Component (c) was included in 55.1 parts by mass, and the total of component (b) and component (c) was 100 parts by mass. The characteristic evaluation results are shown in Table 2.

<Comparison of Examples 1 to 5, Comparative Example 1 and Comparative Example 2>
In Examples 1 to 5 using polycarbodiimide-modified polypropylene and using a polyfunctional compound as a sizing agent, the molded article has excellent mechanical properties, little decrease in bending strength even at the time of water absorption, and water resistance deterioration resistance. Could get.

  On the other hand, even if polycarbodiimide-modified polypropylene is used, in Comparative Example 1 in which no sizing agent is used and in Comparative Example 2 in which a sizing agent having no functional group is used, a molded article having excellent mechanical properties can be obtained. Although it was possible, the bending strength was greatly reduced at the time of water absorption, and a molded product having resistance to water deterioration could not be obtained.

  As the types of sizing agents, the compounds having a tri- or higher functional epoxy group shown in Example 1 and Example 4 and the polyethyleneimine shown in Example 5 tend to have excellent mechanical properties and water resistance. It was.

<Comparison of Example 1, Example 8, and Example 9>
As for Example 8, CDI-PP2 has a low Mn / {(100-M) × f / M} value of MAH-PP2 as a raw material of 0.09 and a carbodiimide group content of 0.09 mmol / Since it was as low as 100 g, it was slightly inferior to the mechanical properties of the molded product obtained as compared with Example 1, but it had little deterioration in bending strength at the time of water absorption and had water resistance.

  Regarding Example 9, CDI-PP3 has a high value of Mn / {(100-M) × f / M} of MAH-PP3, which is the raw material, and contains a carbodiimide group to suppress gelation as much as possible Although it was manufactured by adjusting the amount of the compound, it was difficult to manufacture due to some gelation. Moreover, although it was a little inferior to the mechanical characteristic of the obtained molded product compared with Example 1, there was almost no fall of the bending strength at the time of water absorption, and it had the outstanding water-resistant deterioration property.

<Comparison of Example 1, Example 7, Comparative Example 4, and Comparative Example 5>
A polyfunctional compound was used as a sizing agent, but in Comparative Examples 4 and 5 in which maleic acid-modified polypropylene was used instead of polycarbodiimide-modified polypropylene, molded articles having excellent mechanical properties can be obtained. However, the bending strength was greatly reduced at the time of water absorption, and a molded product having water resistance deterioration resistance was not obtained.

As described above, in Examples 1 to 9, it was possible to obtain molded articles having excellent mechanical characteristics, little decrease in strength even during water absorption, and water resistance deterioration resistance.
On the other hand, in Comparative Examples 1 to 5, although a molded product having excellent mechanical properties can be obtained, the bending strength is greatly reduced at the time of water absorption, and a molded product having water resistance deterioration resistance cannot be obtained.

  The prepreg of the present invention has good interfacial adhesion between the reinforcing fibers and the propylene-based resin, and the reinforcing fibers are substantially continuous fibers. Therefore, the prepreg is not only extremely excellent in mechanical properties such as bending properties, but also in water resistance deterioration resistance. Excellent molded products can be manufactured. Moreover, since the propylene-based resin is used, a molded product having excellent lightness can be obtained. The prepreg of the present invention can be applied to a wide range of industrial fields such as electric / electronic devices, OA devices, home appliances, robots, motorcycles or automobile parts, internal members, aircraft members, parts and housings.

Claims (13)

A prepreg comprising a reinforcing fiber substrate made of reinforcing fibers (c) and a polypropylene resin composition, wherein the polypropylene resin composition contains at least a carbodiimide-modified polyolefin (a) and a polypropylene resin (b). The content of the carbodiimide group contained in the matrix resin component in the prepreg is 0.0005 to 140 mmol with respect to 100 g of the matrix resin component, and the reinforcing fiber (c) and / or the reinforcing fiber substrate is a polyfunctional compound. (S), the reinforcing fiber (c) in the prepreg is substantially a continuous fiber, and the strength retention represented by the following formula of the molded product obtained by molding the prepreg is: A prepreg characterized by being 90% or more .
・ (Strength retention) = (Bending strength of water absorption sample) / (Bending strength of dry sample) × 100 A prepreg comprising a reinforcing fiber (c) and a polypropylene resin composition, wherein the polypropylene resin composition contains at least a carbodiimide-modified polyolefin (a) and a polypropylene resin (b). 0.01 to 50 parts by mass, 20 to 99 parts by mass of (b), 1 to 80 parts by mass of (c) (provided that the total of (b) and (c) is 100 parts by mass), and The reinforcing fiber (c) is sized by the polyfunctional compound (s), the reinforcing fiber (c) in the prepreg is substantially a continuous fiber, and a molded product obtained by molding the prepreg A prepreg having a strength retention represented by the formula of 90% or more .
・ (Strength retention) = (Bending strength of water absorption sample) / (Bending strength of dry sample) × 100   The prepreg according to claim 2, wherein the content of carbodiimide groups contained in 100 g of the carbodiimide-modified polyolefin (a) is 1 to 200 mmol.   The carbodiimide-modified polyolefin (a) is obtained by reacting a polyolefin resin (A) having a group that reacts with a carbodiimide group and a carbodiimide group-containing compound (B). The prepreg described in 1. The polyolefin resin (A) is a polymer in which a compound having a group that reacts with a carbodiimide group is introduced into a polyolefin, and the polyolefin resin (A) is a polymer that satisfies the following formula (1). The prepreg described in 1.
0.1 <Mn / {(100-M) × f / M} <6 (1)
(Where
f: Molecular weight of a compound having a group that reacts with a carbodiimide group (g / mol)
M: Content of a compound having a group that reacts with a carbodiimide group (wt%)
Mn: Number average molecular weight of the polyolefin resin (A) having a group that reacts with a carbodiimide group. )     The prepreg according to claim 4 or 5, wherein the polyolefin resin (A) is a polyolefin resin having a maleic anhydride group.   The prepreg according to any one of claims 1 to 6, wherein the reinforcing fiber (c) is a carbon fiber.   The prepreg according to any one of claims 1 to 7, wherein the polyfunctional compound (s) is a compound having a trifunctional or higher functional group.   The prepreg according to any one of claims 1 to 8, wherein the functional group in the polyfunctional compound (s) is at least one selected from an epoxy group, a carboxyl group, an amino group, and a hydroxyl group.   The prepreg according to any one of claims 1 to 9, wherein the polyfunctional compound (s) is an aliphatic epoxy resin.   The prepreg according to any one of claims 1 to 9, wherein the polyfunctional compound (s) is polyethyleneimine.   The prepreg according to any one of claims 1 to 11, wherein the polypropylene resin composition is impregnated in the reinforcing fiber.   The prepreg according to any one of claims 1 to 12, wherein the reinforcing fibers (c) are aligned in one direction in a longitudinal direction of the prepreg.