JP2024060545A - Molding - Google Patents

Abstract

To provide a molding which is excellent in flame shielding property and heat insulation property.SOLUTION: A molding is composed of a resin composition containing (A) a thermoplastic resin, (B) a phosphorus-based flame retardant, and (C) fibers, in which as for a smoothing curve obtained by smoothing a temperature curve of the surface of the molding obtained by the following testing method (a) by polynomial approximation, when an inflection point is obtained by its second-order differential, there is a second inflection point. Testing method (a): the surface of the molding is brought into contact with flame by a burner so that a flame surface becomes 1,200°C, a temperature on a surface opposite to the flame contact surface is measured by a non-contact type thermometer, and a curve in which the surface temperatures with respect to elapsed time up to t=200 seconds are plotted is obtained.SELECTED DRAWING: Figure 1

Description

The present invention relates to a molded body, and more specifically to a molded body with excellent flame retardant and heat insulating properties.

In recent years, research and development of electric and hybrid vehicles has been promoted as part of environmental measures, and the development of high-energy density batteries and weight reduction are being actively promoted in order to improve the driving range. Such high-energy density batteries are at risk of catching fire in the event of an accident, so as a safety measure for passengers, the housing material must have high flame retardancy, and therefore, in many cases, metal materials such as iron are used in combination with fire-resistant materials.
However, metal materials have the drawback of being heavy, and when fire-resistant materials are used in combination, issues arise regarding workability and increased costs due to the increased number of parts. Therefore, attempts are being made to use resins, which have the potential to achieve both light weight and flame resistance.
On the other hand, in order to realize a sustainable society, importance is now being placed on reducing carbon dioxide emissions and recyclability. Many thermosetting materials have high flame retardancy and are common as composite materials, but in terms of recyclability, thermoplastic resin materials are advantageous.

In addition, China has announced a safety standard called GB 38031-2020 "Safety Requirements for Electric Vehicle Power Batteries," which requires that a warning be issued five minutes before the battery experiences thermal runaway. It is believed that this can be achieved by using housing materials that provide flame protection for at least five minutes after the battery ignites.

To address these issues, for example, Patent Document 1 proposes adding a brominated flame retardant or an antimony oxide compound to a carbon fiber reinforced polypropylene resin, but the additives used therein have a problem in terms of their persistence in living organisms.
In response to this, Patent Document 2 proposes a flame-retardant polyolefin-based composition in which a polyolefin-based resin contains a (poly)phosphate compound, as a technology for making polypropylene-based resin flame-retardant while taking into consideration bioretention.
Moreover, Patent Document 3 proposes a flame-retardant resin composition comprising a polypropylene resin, long glass fibers, and a phosphate compound.

JP 2014-62189 A JP 2013-119575 A JP 2011-88970 A

As mentioned above, conventional technology has many shortcomings in resinification, which has the potential to achieve both lightweight and flame-resistant properties for high-energy-density batteries. Specifically, molded bodies with high flame-resistant and heat-insulating properties are required.

The present invention was made to solve the above problems, and aims to provide a molded body with excellent flame-proofing and heat-insulating properties.

The inventors of the present invention conducted intensive research to solve the above problems, and as a result, discovered that the above problems can be solved by a molded article made of a resin composition containing (A) a thermoplastic resin, (B) a phosphorus-based flame retardant, and (C) fibers, the molded article having a specific inflection point on a temperature curve obtained under specific conditions. The present invention was completed based on these findings. That is, the present invention provides the following [1] to [17].

[1] A molded article made of a resin composition containing (A) a thermoplastic resin, (B) a phosphorus-based flame retardant, and (C) fibers, wherein the molded article has a second inflection point when an inflection point is obtained from a second-order differential of a smoothed curve obtained by smoothing a temperature curve of the surface of the molded article obtained by the following test method (i) using polynomial approximation.
Test method (a): The surface of the molded body is exposed to a flame from a burner so that the flame front is 1200°C, and the temperature of the surface opposite the flame-exposed surface is measured with a non-contact thermometer. A curve is obtained by plotting the surface temperature against the elapsed time up to t = 200 seconds.
[2] The molded body described in [1] above, wherein the second inflection point occurs after t = 40 seconds.
[3] The molded body according to [1] or [2] above, wherein the second inflection point occurs within t = 180 seconds.
[4] The molded body according to any one of [1] to [3] above, wherein the second inflection point is present at 400° C. or lower.
[5] The molded product according to any one of the above [1] to [4], wherein the ratio (area (X1)/area (Y)) of the area (X1) of the region surrounded by the smoothed curve and a line segment connecting the first inflection point and the third inflection point on the smoothed curve obtained by the second differentiation to the area (Y) of the region surrounded by the line segment connecting the point at 50°C and the first inflection point and the smoothed curve is 1.0 or more.
[6] The molded body according to any one of the above [1] to [5], wherein the ratio (area (X2)/area (Y)) of the area (X2) of the region surrounded by the smoothed curve and a line segment connecting the second inflection point and the third inflection point on the smoothed curve obtained by the second differentiation to the area (Y) of the region surrounded by the line segment connecting the point at 50°C and the first inflection point and the smoothed curve is 0.5 or more.
[7] The molded article according to any one of the above [1] to [6], wherein the resin composition further contains (D) a dispersant.
[8] The molded article according to the above [7], wherein the dispersant (D) is a copolymer of an α-olefin and an unsaturated carboxylic acid.
[9] The molded body according to any one of the above [1] to [8], wherein the (B) phosphorus-based flame retardant is an intumescent flame retardant.
[10] The molded body according to any one of the above [1] to [9], wherein the (C) fiber is an inorganic fiber.
[11] The molded article according to the above [10], wherein the inorganic fibers are at least one selected from glass fibers, ceramic fibers, metal fibers, and metal oxide fibers.
[12] The molded article according to any one of the above [1] to [11], which is a laminate having a resin layer made of the resin composition and a support layer made of fibers.
[13] The molded body according to the above [12], wherein the support layer made of the fibers is a nonwoven fabric layer made of a nonwoven fabric, a woven fabric layer made of a woven fabric, or a knitted fabric layer made of a knitted fabric.
[14] The molded article according to the above [12] or [13], wherein the fibers constituting the support layer are inorganic fibers.
[15] The molded body according to the above [14], wherein the inorganic fibers are at least one selected from glass fibers, ceramic fibers, metal fibers, and metal oxide fibers.
[16] The molded body according to any one of [1] to [15] above, wherein the (A) thermoplastic resin is a polypropylene-based resin, and the content of the polypropylene-based resin in the resin composition is 15 to 80 mass%.
[17] The molded article according to any one of the above [1] to [16], wherein the content of the phosphorus-based flame retardant (B) in the resin composition is 1 to 40 mass%.

The present invention provides a molded product with excellent flame and heat insulation properties.

1 is a schematic diagram showing one embodiment of a laminate of the present invention. FIG. 2 is a schematic diagram showing the positional relationship between the laminate of the present invention and a flame. FIG. 2 is a schematic diagram showing another embodiment of the laminate of the present invention. FIG. 2 is a schematic diagram showing another embodiment of the laminate of the present invention. FIG. 2 is a schematic diagram showing an example of a method for producing the laminate of the present invention. 1 is a graph showing temperature curves of the rear surfaces of molded bodies obtained in a flame-proofing test for Examples 1 to 4 and Comparative Example 1. 1 is a graph showing a smoothed back surface temperature curve of Example 1. The horizontal axis represents elapsed time (seconds) and the vertical axis represents back surface temperature (° C.). Inflection points are plotted on the curve. 1 is a graph showing a curve obtained by smoothing the back surface temperature curve of Example 2. The horizontal axis represents elapsed time (seconds) and the vertical axis represents the back surface temperature (° C.). Inflection points are plotted on the smoothed curve. 13 is a graph showing a curve obtained by smoothing the back surface temperature curve of Example 3. The horizontal axis represents elapsed time (seconds) and the vertical axis represents the back surface temperature (° C.). Inflection points are plotted on the smoothed curve. 1 is a graph showing a curve obtained by smoothing the back surface temperature curve of Example 4. The horizontal axis represents elapsed time (seconds) and the vertical axis represents the back surface temperature (° C.). Inflection points are plotted on the smoothed curve. 1 is a graph showing a curve obtained by smoothing the back surface temperature curve of Comparative Example 1. The horizontal axis represents elapsed time (seconds) and the vertical axis represents the back surface temperature (° C.). Inflection points are plotted on the smoothed curve.

The following describes in detail the embodiments of the present invention, but the following description is merely an example of an embodiment of the present invention, and the present invention is not limited to these contents in any way.

[Molded body]
The molded article of the present invention is a molded article made of a resin composition containing (A) a thermoplastic resin, (B) a phosphorus-based flame retardant, and (C) fibers.
The smoothed curve (hereinafter sometimes referred to as the "smoothed temperature curve") obtained by smoothing the temperature curve of the molded body surface obtained by the test method (i) below using polynomial approximation is characterized in that when an inflection point is obtained from the second-order differentiation, a second inflection point is present.
Test method (a): The surface of the molded body is exposed to a flame from a burner so that the flame front is 1200°C, and the temperature of the surface opposite the flame-exposed surface is measured with a non-contact thermometer. A curve is obtained by plotting the surface temperature against the elapsed time up to t = 200 seconds.

In the course of repeated investigations into obtaining a molded article with excellent flame-resistance and heat-insulating properties, the present inventors found that there is a certain relationship between the shape of the temperature curve at the beginning of flame contact of the molded article obtained by the above-mentioned test method (A) and the flame-resistance performance, and focused on this point. They found that when an inflection point is obtained from the second derivative of a smoothed temperature curve obtained by smoothing the temperature curve of the surface of the molded article obtained by test method (A) using polynomial approximation, if a second inflection point is present, the molded article will not be penetrated by the flame or have a hole when exposed to the flame of a 1200°C burner for 10 minutes or more.
On the other hand, when the molded article did not have the second inflection point, the flame penetrated the molded article in a short time and a hole was formed. Although the detailed reason for this is still unclear, it is thought to be as follows.
That is, an inflection point is a point at which the curve changes from concave (upward convex) to convex (downward convex) or vice versa, and the smoothed temperature curve having an inflection point means that the curve changes from concave (upward convex) to convex (downward convex) or vice versa. Such a change in the smoothed temperature curve of the molded body of the present invention is believed to be due to the fact that the expanded carbonized layer formed by the phosphorus-based flame retardant contained in the molded body at that time blocks the conduction of heat and suppresses the temperature rise of the back surface of the molded body. On the other hand, if the molded body does not form a sufficient expanded carbonized layer, an inflection point does not appear in the temperature curve. In such a case, if the flame-shielding evaluation is continued, the flame will penetrate and a hole will be formed, and as a result, the flame-shielding property cannot be realized. As described above, the present inventors have focused on a certain relationship between the shape of the temperature curve at the beginning of flame contact of the molded body and the flame-shielding performance, and have found that the inflection point of the smoothed temperature curve, especially the presence or absence of the second inflection point, can be used as an index for predicting the subsequent flame-shielding performance.
A specific example of a method for obtaining a smoothed temperature curve by smoothing the above-mentioned temperature curve using polynomial approximation is a method for obtaining a smoothed curve by approximating the temperature curve to a sixth-order polynomial using the least squares method.

As described above, the molded article of the present invention has a second inflection point on the smoothed temperature curve, and from the viewpoint of improving flame-proofing and heat-insulating properties, the second inflection point is preferably present after t = 40 seconds, and more preferably after t = 60 seconds. From the same viewpoint, the second inflection point is preferably present within t = 180 seconds, more preferably within t = 150 seconds, and even more preferably within t = 120 seconds.
From the viewpoint of improving flame-proofing and heat-insulating properties, the second inflection point is preferably a point of 400° C. or less, more preferably a point of 350° C. or less, even more preferably a point of 320° C. or less, and particularly preferably a point of 300° C. or less. On the other hand, the second inflection point is usually a point of 100° C. or more.

Furthermore, in the molded product of the present invention, it is preferable that the ratio (area (X1)/area (Y)) of the area (X1) of the region surrounded by the smoothed curve and a line segment connecting the first inflection point and the third inflection point on the smoothed curve obtained by the second differentiation, to the area (Y) of the region surrounded by the line segment connecting the point at 50°C and the first inflection point and the smoothed curve, is 1.0 or more.
As described above, the change in the shape of the smoothed temperature curve at the beginning of the flame contact is believed to be due to the formation of an expanded char layer due to the phosphorus-based flame retardant in the molded body. Therefore, the size of the area (X1) of the region surrounded by the line segment connecting the first inflection point and the third inflection point on the smoothed curve and the smoothed curve is considered to approximately correspond to the amount of heat that can be shielded by the adiabatic expansion layer. On the other hand, the inventors' study has revealed that the smoothed temperature curve from the very beginning of the flame contact to the first inflection point has a roughly similar shape regardless of the molded body. This is because the formation of the expanded char layer due to the phosphorus-based flame retardant has not started during this period, and the temperature curve is determined by heat conduction in the thickness direction of the molded body. Therefore, normalization is performed by dividing the area (X1) by the area of the very beginning of the smoothed temperature curve, specifically, the area (Y) of the region surrounded by the line segment connecting the point at 50 ° C. and the first inflection point and the smoothed curve. The normalized area ratio area (X1)/area (Y) is preferably 1.2 or more, more preferably 2.0 or more, and even more preferably 2.2 or more, from the viewpoint of enhancing flame-shielding and heat-insulating properties. From the same viewpoint, it is preferably 20 or less, more preferably 15 or less, and even more preferably 12 or less.

Furthermore, in the molded product of the present invention, it is preferable that the ratio (area (X2)/area (Y)) of the area (X2) of the region surrounded by the smoothed curve and the line segment connecting the second inflection point and the third inflection point on the smoothed curve obtained by the second differentiation, to the area (Y) of the region surrounded by the line segment connecting the point at 50°C and the first inflection point and the smoothed curve, is 0.5 or more.
As described above, the change in the shape of the smoothed temperature curve at the beginning of the flame contact is believed to be due to the formation of an expanded char layer due to the phosphorus-based flame retardant in the molded body. Therefore, the size of the area (X2) surrounded by the line segment connecting the second inflection point and the third inflection point on the smoothed curve and the smoothed curve is considered to approximately correspond to the amount of heat that can be shielded by the adiabatic expansion layer. On the other hand, the inventors' study has revealed that the smoothed temperature curve between the very beginning of the flame contact and the first inflection point has a roughly similar shape regardless of the molded body. This is because the formation of the expanded char layer due to the phosphorus-based flame retardant has not started during this period, and the temperature curve is determined by the thermal conduction in the thickness direction of the molded body. Therefore, normalization is performed by dividing the area (X2) by the area of the very beginning of the smoothed temperature curve, specifically, the area (Y) surrounded by the line segment connecting the point at 50 ° C. and the first inflection point and the smoothed curve. The normalized area ratio (area (X2)/area (Y)) is preferably 0.7 or more, more preferably 1.0 or more, and even more preferably 1.2 or more from the viewpoint of enhancing flame-shielding properties and heat insulation properties. From the same viewpoint, it is preferably 15 or less, more preferably 12 or less, and even more preferably 10 or less.

<Resin Composition>
The molded article of the present invention is made of a resin composition containing (A) a thermoplastic resin, (B) a phosphorus-based flame retardant, and (C) fibers. The (A) thermoplastic resin, (B) the phosphorus-based flame retardant, and (C) the fibers constituting the resin composition will be described in detail below.

<<(A) Thermoplastic resin>>
The thermoplastic resin constituting the resin composition according to the present invention is not particularly limited, and examples thereof include polyolefin resin, polycarbonate resin, polyester resin, acrylonitrile styrene resin, ABS resin, polyamide resin, modified polyphenylene oxide, polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, etc. It should be noted that one of these may be used, or two or more may be used. For example, the thermoplastic resin (A) may be a composite resin of two or more of the above thermoplastic resins.
Among these, polyolefin resins are preferred from the standpoint of resin properties, versatility, cost, etc., and polypropylene-based resins are particularly preferred.

The polyolefin resin is not particularly limited, and examples thereof include the resins described below. The polyester resin is not particularly limited, and examples thereof include polybutylene terephthalate. The polyamide resin is not particularly limited, and examples thereof include nylon 66 and nylon 6.
In particular, the present invention is particularly useful when the thermoplastic resin (A) contains at least a polyolefin resin. In the present invention, the term "polyolefin resin" refers to a resin in which the proportion of olefin units or cycloolefin units is 90 mol % or more relative to 100 mol % of all structural units constituting the resin.
The proportion of olefin units or cycloolefin units relative to 100 mol % of all structural units constituting the polyolefin resin is preferably 95 mol % or more, and particularly preferably 98 mol % or more.

Examples of polyolefin resins include α-olefin polymers such as polyethylene, polypropylene, polybutene, poly(3-methyl-1-butene), poly(3-methyl-1-pentene), and poly(4-methyl-1-pentene); α-olefin copolymers such as ethylene-propylene block or random copolymers, α-olefin-propylene block or random copolymers having 4 or more carbon atoms, ethylene-methyl methacrylate copolymers, and ethylene-vinyl acetate copolymers; and cycloolefin polymers such as polycyclohexene and polycyclopentene.
Examples of polyethylene include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, etc. Examples of polypropylene include isotactic polypropylene, syndiotactic polypropylene, hemiisotactic polypropylene, stereoblock polypropylene, etc. In the α-olefin-propylene block or random copolymer having 4 or more carbon atoms, examples of the α-olefin having 4 or more carbon atoms include butene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, etc.
Of these, in the molded article of the present invention, it is particularly preferable that the thermoplastic resin (A) is a polypropylene-based resin, which will be described in detail later.
The polyolefin resins may be used alone or in combination of two or more.

(Melt Flow Rate (MFR))
The melt flow rate (hereinafter sometimes abbreviated as MFR) (230°C, 2.16 kg load) of the thermoplastic resin (A) used in the present invention is preferably 5 to 500 g/10 min. If the MFR is 5 g/10 min or more, good fluidity is obtained when preparing a molded article by, for example, injection molding, and the processability is good. On the other hand, if it is 500 g/10 min or less, the strength of the molded article is sufficient. From the above viewpoints, the MFR is preferably in the range of 10 to 300 g/10 min, more preferably 20 to 200 g/10 min, and even more preferably 25 to 100 g/10 min.
The MFR of the thermoplastic resin (A) can be adjusted, for example, by controlling the hydrogen concentration during polymerization, etc. The MFR is a value measured in accordance with JIS K7210.

((A) Thermoplastic resin content)
The content of the thermoplastic resin (A) in the resin composition according to the present invention is not particularly limited, but is preferably 15 to 80% by mass. When the content of the thermoplastic resin is 15% by mass or more, the molding processability is particularly good, and molding of the molded body is easy. On the other hand, when the content is 80% by mass or less, a sufficient amount of flame retardant, dispersant, inorganic fiber, etc. can be contained, and good flame insulation can be obtained. From the above viewpoints, the content of the thermoplastic resin in the resin composition is preferably 35 to 70% by mass, and more preferably 40 to 60% by mass. In addition, when the thermoplastic resin (A) is the above-mentioned suitable polypropylene-based resin, the suitable content is the same.

<<<(A-1) Polypropylene resin>>>
As described above, the thermoplastic resin (A) constituting the resin composition according to the present invention preferably contains a polypropylene-based resin. Examples of the polypropylene-based resin include a propylene homopolymer and a propylene-α-olefin copolymer. Here, the propylene-α-olefin copolymer may be either a random copolymer or a block copolymer.

(α-Olefin)
Examples of the α-olefin constituting the copolymer include ethylene, 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, and 1-octene. One of these may be copolymerized with propylene, or two or more may be copolymerized with propylene. Among them, from the viewpoint of improving the impact strength of the molded body, ethylene or 1-butene, which have a large effect, are preferred, and ethylene is most preferred.

(Propylene-ethylene random copolymer)
In the case of a random copolymer of propylene and ethylene, it preferably contains 90 to 99.5% by mass, more preferably 92 to 99% by mass, of propylene units and preferably 0.5 to 10% by mass, more preferably 1 to 8% by mass of ethylene units. When the ethylene units are equal to or more than the lower limit, sufficient impact strength of the molded article is obtained, and when the ethylene units are equal to or less than the upper limit, sufficient rigidity is maintained.
The contents of propylene units and ethylene units in the random copolymer of propylene and ethylene can be adjusted by controlling the composition ratio of propylene and ethylene during polymerization of the random copolymer of propylene and ethylene.
The propylene content of the random copolymer of propylene and ethylene is a value measured using a cross fractionator or FT-IR, and the measurement conditions and the like may be, for example, those described in JP-A-2008-189893.

<<<Modified polyolefin resin>>>
The resin composition according to the present invention may further contain a modified polyolefin resin in addition to the polypropylene resin. Specific examples of the modified polyolefin resin include acid-modified polyolefin resins and hydroxy-modified polyolefin resins, and these may be used alone or in combination.
The types of acid-modified polyolefin resins and hydroxy-modified polyolefin resins used as the modified polyolefin resins are not particularly limited, and may be any of the conventionally known resins.

(Acid-modified polyolefin resin)
Examples of acid-modified polyolefin resins include those obtained by graft copolymerizing polyolefins such as polyethylene, polypropylene, ethylene-α-olefin copolymers, ethylene-α-olefin-non-conjugated diene compound copolymers (such as EPDM), and ethylene-aromatic monovinyl compound-conjugated diene compound copolymer elastomers with unsaturated carboxylic acids such as maleic acid or maleic anhydride, thereby chemically modifying the polyolefins.
The graft copolymerization is carried out, for example, by reacting the polyolefin with an unsaturated carboxylic acid in a suitable solvent using a radical generator such as benzoyl peroxide. The unsaturated carboxylic acid or its derivative component can also be introduced into the polymer chain by random or block copolymerization with a polyolefin monomer.

Examples of unsaturated carboxylic acids used for modification include compounds having a carboxyl group, such as maleic acid, fumaric acid, itaconic acid, acrylic acid, and methacrylic acid, and a polymerizable double bond into which a functional group, such as a hydroxyl group or an amino group, has been introduced as necessary.
Derivatives of unsaturated carboxylic acids include their acid anhydrides, esters, amides, imides, metal salts, etc., and specific examples thereof include maleic anhydride, itaconic anhydride, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, etc. Of these, maleic anhydride is preferred.

Preferred acid-modified polyolefin resins include those modified by graft polymerization of maleic anhydride to an olefin polymer having ethylene and/or propylene as the main polymer unit, and those modified by copolymerization of an olefin mainly consisting of ethylene and/or propylene with maleic anhydride. Specific examples include a combination of polyethylene/maleic anhydride grafted ethylene-butene-1 copolymer, or a combination of polypropylene/maleic anhydride grafted polypropylene.

(Hydroxy-modified polyolefin resin)
The hydroxy-modified polyolefin resin is a modified polyolefin resin containing a hydroxyl group. The hydroxy-modified polyolefin resin may have a hydroxyl group at an appropriate site, for example, at the end of the main chain or on a side chain.
Examples of the olefin resin constituting the hydroxy-modified polyolefin resin include homopolymers or copolymers of α-olefins such as ethylene, propylene, butene, 4-methylpentene-1, hexene, octene, nonene, decene, and dodecene, and copolymers of the above-mentioned α-olefins with copolymerizable monomers.
Examples of preferred hydroxy-modified polyolefin resins include hydroxy-modified polyethylene resins such as low-, medium- or high-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, ethylene-(meth)acrylic acid ester copolymers, and ethylene-vinyl acetate copolymers; and hydroxy-modified polypropylene resins such as polypropylene homopolymers such as isotactic polypropylene, random copolymers of propylene and α-olefins (e.g., ethylene, butene, hexane, etc.), propylene-α-olefin block copolymers, and hydroxy-modified poly(4-methylpentene-1).

<(B) Phosphorus-based flame retardant>
The resin composition according to the present invention contains (B) a phosphorus-based flame retardant. The phosphorus-based flame retardant is preferable from the viewpoint of improving flame-proofing, not remaining in the body, and having excellent flame retardancy. In the present invention, the phosphorus-based flame retardant is essential, but other flame retardants may be used in combination, specifically, bromine-based flame retardants, antimony-based flame retardants, etc. In addition, in the classification focusing on the action mechanism of the flame retardant, it is preferable that the (B) flame retardant is an intumescent flame retardant from the viewpoint of improving flame-proofing.

The phosphorus-based flame retardant is a phosphorus compound, i.e., a compound containing a phosphorus atom in the molecule, and exerts a flame retardant effect by forming char when the resin composition is burned.
The phosphorus-based flame retardant may be a known one, and examples thereof include (poly)phosphates, (poly)phosphate esters, etc. Here, "(poly)phosphates" refers to phosphates or polyphosphates, and "(poly)phosphate esters" refers to phosphate esters or polyphosphate esters.
The phosphorus-based flame retardant is preferably a solid at 80°C.

As the phosphorus-based flame retardant, (poly)phosphates are preferred in terms of flame retardancy.
Examples of (poly)phosphates include ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, piperazine orthophosphate, melamine pyrophosphate, piperazine pyrophosphate, melamine polyphosphate, melamine orthophosphate, calcium phosphate, and magnesium phosphate.
In addition, in the above examples, compounds in which melamine or piperazine is replaced with other nitrogen compounds can be used in the same manner. Examples of other nitrogen compounds include N,N,N',N'-tetramethyldiaminomethane, ethylenediamine, N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-diethylethylenediamine, 1,2-propanediamine, 1,3-propanediamine, tetramethyl Diamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, trans-2,5-dimethylpiperazine, 1,4-bis(2-aminoethyl)piperazine, 1,4-bis(3-aminopropyl)piperazine, acetoguanamine, benzoguanamine, acrylguanamine, 2,4-diamino-6-nonyl-1,3,5-triamine 2,4-diamino-6-hydroxy-1,3,5-triazine, 2-amino-4,6-dihydroxy-1,3,5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-ethoxy-1,3,5-triazine, 2,4-diamino-6-propoxy-1,3,5-triazine, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6-mercapto-1, Examples of such (poly)phosphates include 3,5-triazine, 2-amino-4,6-dimercapto-1,3,5-triazine, ammeline, benzguanamine, acetoguanamine, phthalodiguanamine, melamine cyanurate, melamine pyrophosphate, butylenediguanamine, norbornenediguanamine, methylenediguanamine, ethylenedimelamine, trimethylenedimelamine, tetramethylenedimelamine, hexamethylenedimelamine, 1,3-hexylenedimelamine, etc. These (poly)phosphates may be used alone or in combination of two or more.

Among the above phosphorus-based flame retardants, a salt of (poly)phosphoric acid and a nitrogen compound (hereinafter also referred to as "compound (b1)") is preferred. Compound (b1) is an intumescent flame retardant, and forms a surface expansion layer (intemescent) which is a foamed char when the resin composition is burned. The formation of the surface expansion layer suppresses the diffusion and heat transfer of decomposition products, and excellent flame retardancy is exhibited.
Examples of the nitrogen compound in the compound (b1) include ammonia, melamine, piperazine, and the other nitrogen compounds described above.

Commercially available phosphorus-based flame retardants include Adeka STAB FP-2100J, FP-2200, and FP-2500S (manufactured by ADEKA Corporation).

(Brominated flame retardants)
Examples of bromine-based flame retardants include decabromodiphenyl ether, tetrabromobisphenol A, tetrabromobisphenol S, 1,2-bis(2',3',4',5',6'-pentabromophenyl)ethane, 1,2-bis(2,4,6-tribromophenoxy)ethane, 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine, 2,6-dibromophenol, 2,4-dibromophenol, Examples of the polybrominated polystyrene include brominated polystyrene, ethylene bistetrabromophthalimide, hexabromocyclododecane, hexabromobenzene, pentabromobenzyl acrylate, 2,2-bis[4'(2'',3''-dibromopropoxy)-3',5'-dibromophenyl]-propane, bis[3,5-dibromo-4-(2,3-dibromopropoxy)phenyl]sulfone, and tris(2,3-dibromopropyl)isocyanurate.

(Antimony-based flame retardant)
Examples of antimony-based flame retardants include antimony trioxide, antimony tetroxide, antimony pentoxide, sodium pyroantimonate, antimony trichloride, antimony trisulfide, antimony oxychloride, antimony perchloropentane dichloride, and potassium antimonate, with antimony trioxide and antimony pentoxide being particularly preferred.

(Intumescent flame retardant)
Intumescent flame retardants are flame retardants that suppress the combustion of materials by forming a surface expansion layer (intumescent) that prevents the diffusion of radiant heat from the combustion source and combustion gases and smoke from the burning material to the outside. Examples of intumescent flame retardants include salts of (poly)phosphoric acid and nitrogen compounds. Specific examples include ammonium salts and amine salts of (poly)phosphoric acid, such as ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, ammonium pyrophosphate, melamine pyrophosphate, and piperazine pyrophosphate.

Among the above flame retardants, halogen-free flame retardants are preferred from the viewpoint of environmental friendliness, and intumescent flame retardants are preferred from the viewpoint of improving the flame-resistance of the resulting fiber-reinforced resin composite material.
The flame retardants may be used alone or in combination of two or more.

(B) Content of phosphorus-based flame retardant
The content of the phosphorus-based flame retardant in the resin composition according to the present invention is not particularly limited, but is preferably in the range of 1 to 40% by mass as the content in the thermoplastic resin composition. When it is 1% by mass or more, good flame retardancy can be imparted to the molded article of the present invention, and good flame shielding properties can be obtained. On the other hand, when the phosphorus-based flame retardant is 40% by mass or less, the thermoplastic resin can be contained in a sufficient content ratio, so that the molding processability is better. From the above viewpoints, the content of the flame retardant in the thermoplastic resin composition is more preferably in the range of 1 to 30% by mass, and even more preferably in the range of 3 to 25% by mass.

<<(C) Fiber>>
The resin composition according to the present invention contains (C) fibers. The (C) fibers may be organic or inorganic fibers, but inorganic fibers are preferred from the viewpoint of heat resistance, and examples thereof include ceramic fibers such as glass fibers, rock wool, basalt fibers, alumina fibers, silica alumina fibers, potassium titanate fibers, calcium silicate (wollastonite) fibers, alkaline earth silicate fibers (biosoluble), and silica fibers, metal oxide fibers, carbon fibers, stainless steel fibers, and metal fibers such as tungsten fibers. These inorganic fibers may be used alone or in combination of two or more.
Among these fibers, glass fibers, ceramic fibers such as alumina fibers, metal oxide fibers, and carbon fibers are preferred because they can improve heat resistance and flame resistance.

The (C) fibers used in the present invention preferably have an average fiber diameter of 3 to 25 μm, and an average fiber length preferably in the range of 0.05 to 100 mm, more preferably in the range of 0.5 to 50 mm, even more preferably in the range of 1 to 25 mm, and particularly preferably in the range of 2 to 15 mm.
When multiple types of fibers are used, it is sufficient that the average fiber diameter and average fiber length of at least one type of fiber are within the above ranges.
The average fiber length of the fibers (C) contained in the resin composition may change depending on the manufacturing method of the molded article. For example, when injection molding, which will be described later, is used, the resin composition is heated and melted, so that the fibers tend to break and the average fiber length tends to be shortened. The above average fiber length means the average fiber length in the resin composition, and is the fiber length before the heat history is applied. Therefore, the average fiber length of the fibers in the molded article manufactured by a method such as injection molding is preferably in the range of 0.05 to 50 mm, more preferably in the range of 0.25 to 25 mm, even more preferably in the range of 0.5 to 15 mm, and particularly preferably in the range of 1 to 10 mm.
On the other hand, when the molded article is produced by a lamination method, the average fiber length of the (C) fibers in the resin composition and the average fiber length of the (C) fibers in the molded article do not change.
The fiber diameter can be measured using an optical microscope or the like, and the average fiber diameter can be obtained by, for example, measuring the fiber diameters of 10 randomly selected fibers and calculating the average value. The fiber length can be measured using a ruler, calipers, or the like from an image enlarged by a microscope or the like as necessary, and the average fiber length can be obtained by, for example, measuring the fiber lengths of 10 randomly selected fibers and calculating the average value.

The fiber content in the resin composition according to the present invention is preferably 3 to 60% by mass. When the fiber content is 3% by mass or more, the strength, rigidity, and impact resistance of the molded body can be ensured. On the other hand, when the fiber content is 60% by mass or less, the molded body can be easily manufactured and processed. In addition, when the fiber content is 60% by mass or less, the specific gravity is reduced, and there is an advantage that the weight reduction effect as a metal substitute is large.
From the above viewpoints, the content of fibers in the resin composition according to the present invention is more preferably 10 to 50% by mass, and further preferably 20 to 45% by mass.

(Glass fiber)
One of the fibers (C) suitable for the molded article of the present invention is glass fiber. The glass fiber may be, for example, a long fiber having an average fiber length of 30 mm or more, or a fiber having a short average fiber length (chopped strand).
More specifically, the average fiber length is preferably in the range of 0.05 to 100 mm. When the average fiber length is within the above range, the strength and impact resistance of the molded body are good. From the above viewpoints, the range is more preferably 0.5 to 50 mm, even more preferably 1 to 25 mm, and particularly preferably 2 to 15 mm. In the case of glass fibers as the (C) fiber in a molded body produced by a method such as injection molding, the average fiber length is preferably in the range of 0.05 to 50 mm, more preferably 0.25 to 25 mm, even more preferably 0.5 to 15 mm, and particularly preferably 1 to 10 mm.
There is no particular upper limit to the average fiber length of glass fibers, and when using pellets produced by the pultrusion method using glass fibers, the length of the pellets is the fiber length of the glass fibers, which is a maximum of about 20 mm. In addition, in a swirl mat system using long glass fibers, the length of the glass fibers in the roving used for production is the maximum fiber length, which can be as long as 17,000 m (17 km), but when cut to fit the size of the molded product, the cut length is the maximum fiber length.

The average fiber diameter of the glass fibers is preferably in the range of 9 to 25 μm. When the average fiber diameter is 9 μm or more, the rigidity and impact resistance of the molded article are sufficient, while when the average fiber diameter is 25 μm or less, the strength of the molded article is good. From the above viewpoints, the average fiber diameter of the glass fibers is more preferably in the range of 10 to 15 μm.
The average fiber diameter and average fiber length of the glass fibers can be measured by the above-mentioned method.

There are no particular limitations on the material of the glass fiber used in the present invention, and it may be any of alkali-free glass, low-alkali glass, and alkali-containing glass, and any of the various compositions that have been used conventionally as glass fibers can be used.

(Alumina fiber)
One of the fibers (C) suitable for the molded article of the present invention is alumina fiber. Alumina fiber is usually a fiber made of alumina and silica, and in the laminate of the present invention, the alumina/silica composition ratio (mass ratio) of the alumina fiber is preferably in the range called a mullite composition of 65/35 to 98/2 or a high alumina composition, more preferably in the range of 70/30 to 95/5, and particularly preferably in the range of 70/30 to 74/26.

The average fiber diameter of the alumina fibers is preferably in the range of 3 to 25 μm, and it is preferable that the fibers are substantially free of fibers having a fiber diameter of 3 μm or less. Here, "substantially free of fibers having a fiber diameter of 3 μm or less" means that the fibers having a fiber diameter of less than 3 μm account for 0.1 mass% or less of the total inorganic fiber mass. When the average fiber diameter is 3 μm or more, the amount of dust suspended in the air is reduced. On the other hand, when the average fiber diameter is 25 μm or less, it is preferable in terms of the rigidity and impact resistance of the molded product.
The alumina fibers preferably have an average fiber length in the range of 0.05 to 100 mm. When the average fiber length is within the above range, the strength and impact resistance of the molded body are good. From the above viewpoints, the average fiber length is more preferably in the range of 0.5 to 50 mm, even more preferably in the range of 1 to 25 mm, and particularly preferably in the range of 2 to 15 mm. In the case of alumina fibers as the (C) fibers in a molded body produced by a method such as injection molding, the average fiber length is preferably in the range of 0.05 to 50 mm, more preferably in the range of 0.25 to 25 mm, even more preferably in the range of 0.5 to 15 mm, and particularly preferably in the range of 1 to 10 mm.

The carbon fibers preferably have an average fiber diameter in the range of 1 to 20 μm, more preferably 2 to 15 μm, even more preferably 3 to 10 μm, and particularly preferably 5 to 7 μm. If the average fiber diameter of the carbon fibers is within the above range, the rigidity and impact resistance of the molded product will be sufficient. The average fiber length is also preferably in the range of 0.05 to 100 mm, more preferably in the range of 0.5 to 50 mm, even more preferably in the range of 1 to 25 mm, and particularly preferably in the range of 2 to 15 mm. If the average fiber length is within the above range, the strength and impact resistance of the molded product will be good.

<<(D) Dispersant>>
The dispersant (D) is not particularly limited as long as it can disperse the flame retardant (B) in the thermoplastic resin (A), but a polymer dispersant can be suitably used in terms of compatibility with the thermoplastic resin (A). Preferably, one that can disperse the flame retardant (B) in the polypropylene resin (A-1) can be used. As the polymer dispersant, a polymer dispersant having a functional group is preferred, and from the standpoint of dispersion stability, a polymer dispersant having a functional group such as a carboxyl group, a phosphoric acid group, a sulfonic acid group, a primary, secondary or tertiary amino group, a quaternary ammonium base, a group derived from a nitrogen-containing heterocycle such as pyridine, pyrimidine or pyrazine is preferred.
In the present invention, a polymer dispersant having a carboxyl group is preferred, and in particular, when a phosphorus-based flame retardant suitable as a flame retardant is used, a copolymer of an α-olefin and an unsaturated carboxylic acid is preferred. By using such a dispersant, the dispersibility of the phosphorus-based flame retardant can be improved, and the content of the flame retardant can be reduced.

(Copolymer of α-olefin and unsaturated carboxylic acid)
In the "copolymer of α-olefin and unsaturated carboxylic acid" according to the present invention (hereinafter referred to as "copolymer (D1)"), the proportion of α-olefin units in the total of 100 mol % of α-olefin units and unsaturated carboxylic acid units is preferably 20 mol % or more and 80 mol % or less.
In the copolymer (D1), the ratio of the α-olefin units to the total amount of the α-olefin units and the unsaturated carboxylic acid units is more preferably 30 mol % or more, and more preferably 70 mol % or less. If the ratio of the α-olefins is equal to or more than the lower limit, the compatibility with the (A) thermoplastic resin such as a polyolefin resin is improved, and if it is equal to or less than the upper limit, the compatibility with the (B) flame retardant is improved.

In the copolymer (D1), the α-olefin is preferably an α-olefin having 5 or more carbon atoms, and more preferably an α-olefin having 10 to 80 carbon atoms. If the α-olefin has 5 or more carbon atoms, it tends to have better compatibility with the thermoplastic resin (A), and if it has 80 or less carbon atoms, it is advantageous in terms of raw material costs. From the above viewpoints, the number of carbon atoms in the α-olefin is more preferably 12 to 70, even more preferably 15 to 65, and particularly preferably 18 to 60.

In the copolymer (D1), examples of the unsaturated carboxylic acid include (meth)acrylic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, glutaconic acid, norbornane-5-ene-2,3-dicarboxylic acid, and esters, anhydrides, imides, etc. of these unsaturated carboxylic acids. Note that "(meth)acrylic acid" refers to acrylic acid or methacrylic acid.
Specific examples of the ester, anhydride or imide of an unsaturated carboxylic acid include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and glycidyl (meth)acrylate; dicarboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic acid anhydride; maleimide compounds such as maleimide, N-ethylmaleimide, and N-phenylmaleimide. These may be used alone or in combination of two or more.
Among the above, esters and dicarboxylic anhydrides are preferred from the viewpoint of copolymerization reactivity, and among these, dicarboxylic anhydrides are preferred, with maleic anhydride being particularly preferred, from the viewpoint of compatibility with phosphorus-based flame retardants that are suitable as flame retardants.

The weight average molecular weight of the copolymer (D1) is preferably at least 2,000, more preferably at least 3,000, and on the other hand, is preferably at most 50,000, more preferably at most 30,000. When the weight average molecular weight of the copolymer (D1) is within the above range, the dispersibility of the flame retardant (B) is more excellent.
The weight average molecular weight of the copolymer (D1) is a value calculated as standard polystyrene by dissolving the copolymer (D1) in tetrahydrofuran (THF) and measuring the resultant by gel permeation chromatography.

Commercially available copolymers (D1) include Ricorb CE2 (Clariant Japan Co., Ltd.) and Diacalna 30M (Mitsubishi Chemical Corporation).

The content of the dispersant (D) relative to 100 parts by mass of the flame retardant (B) in the resin composition according to the present invention is preferably in the range of 0.1 to 25 parts by mass, more preferably in the range of 1 to 10 parts by mass, and even more preferably in the range of 2 to 5 parts by mass.
When the content of the dispersant (D) is equal to or more than the lower limit, the flame retardant (B) is sufficiently dispersed, and good flame resistance is easily obtained. On the other hand, when the content of the dispersant (D) is equal to or less than the upper limit, the mechanical properties of the molded article are maintained.

In addition, the ratio of the (D) dispersant to the total of 100 parts by mass of the (A) thermoplastic resin and the (B) flame retardant is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more. On the other hand, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, and even more preferably 1.0 parts by mass or less. If the ratio of the (D) dispersant is the lower limit or more, the (B) flame retardant is better dispersed, and the flame retardant properties, physical properties, and appearance of the molded body are better. If the ratio of the (D) dispersant is the upper limit or less, the effect of the (D) dispersant on the flame retardant properties of the molded body can be further suppressed.
The same applies when the (A) thermoplastic resin is a polyolefin-based resin.

For (C) fibers, the ratio of (D) dispersant to 100 parts by mass of (C) fibers is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more. On the other hand, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, and even more preferably 2.0 parts by mass or less. If the ratio of (D) dispersant is equal to or greater than the lower limit, the flame retardancy and physical properties of the resulting molded body, as well as the appearance of the resulting molded body, will be improved. If the ratio of (D) dispersant is equal to or less than the upper limit, the effect of (D) dispersant on the flame retardancy of the molded body can be further suppressed.

<<Optional ingredients>>
In addition to the above-mentioned components, any additive components may be blended into the resin composition according to the present invention for the purpose of further improving the effects of the present invention or imparting other effects, within a range that does not significantly impair the effects of the present invention.
Specific examples of such additives include colorants, light stabilizers, ultraviolet absorbers, nucleating agents such as sorbitol-based agents, antioxidants, antistatic agents, neutralizing agents such as inorganic compounds, antibacterial and antifungal agents such as thiazole-based agents, flame retardants and flame retardant assistants such as halogen compounds and lignophenols, plasticizers, dispersants such as organic metal salt-based agents, lubricants such as fatty acid amide-based agents, metal deactivators such as nitrogen compounds, polyolefin resins other than the polypropylene-based resins, thermoplastic resins such as polyamide resins and polyester resins, and elastomers (rubber components) such as olefin-based elastomers and styrene-based elastomers.
These optional components may be used in combination of two or more kinds.

Colorants such as inorganic or organic pigments are effective in imparting or improving the colored appearance, appearance, texture, commercial value, weather resistance, durability, etc. of polypropylene resin compositions and molded articles thereof.
Specific examples of inorganic pigments include carbon black such as furnace carbon and ketjen carbon; titanium oxide; iron oxide (e.g., red iron oxide); chromic acid (e.g., yellow lead); molybdic acid; selenide sulfide; and ferrocyanide. Specific examples of organic pigments include azo pigments such as sparingly soluble azo lake, soluble azo lake, and insoluble azo chelate; condensed azo chelate; and other azo chelates; phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; threne pigments such as anthraquinone, perinone, perylene, and thioindigo; dye lake; quinacridone; dioxazine; and isoindolinone. In order to achieve a metallic or pearlescent look, aluminum flakes and pearl pigments can be added. Dyes can also be added.

Light stabilizers and ultraviolet absorbers, for example, hindered amine compounds, benzotriazoles, benzophenones, and salicylates, are effective in imparting or improving the weather resistance, durability, and the like of polypropylene resin compositions and molded articles thereof, and are effective in further improving weather discoloration resistance.
Specific examples of the hindered amine compound include a condensation product of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine; poly[[6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]]; tetrakis(2,2,6,6-tetramethyl-4-piperidyl)1,2,3,4-butane tetracarboxylate; tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)1,2,3,4-butane tetracarboxylate; bis(1,2,2,6,6-pentamethoxy) 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole;2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole;2-hydroxy-4-methoxybenzophenone;2-hydroxy-4-n-octoxybenzophenone; and the like. Examples of the salicylate-based compounds include 4-t-butylphenyl salicylate; 2,4-di-t-butylphenyl 3',5'-di-t-butyl-4'-hydroxybenzoate; and the like.
Here, the method of using the light stabilizer and the ultraviolet absorber in combination is preferable because it has a large effect of improving weather resistance, durability, weather discoloration resistance, and the like.

As the antioxidant, for example, a phenol-based, phosphorus-based or sulfur-based antioxidant is effective in imparting or improving heat resistance, processing stability, heat aging resistance, etc. to a polypropylene resin composition and a molded article thereof.
Furthermore, antistatic agents such as nonionic and cationic antistatic agents are effective in imparting and improving antistatic properties to polypropylene resin compositions and molded articles thereof.

Examples of olefin-based elastomers include ethylene-α-olefin copolymer elastomers such as ethylene-propylene copolymer elastomer (EPR), ethylene-butene copolymer elastomer (EBR), ethylene-hexene copolymer elastomer (EHR), and ethylene-octene copolymer elastomer (EOR); ethylene-α-olefin-diene terpolymer elastomers such as ethylene-propylene-ethylidenenorbornene copolymer, ethylene-propylene-butadiene copolymer, and ethylene-propylene-isoprene copolymer; and styrene-butadiene-styrene triblock copolymer elastomer (SBS).
Examples of the styrene-based elastomer include styrene-based elastomers such as styrene-isoprene-styrene triblock copolymer elastomer (SIS), styrene-ethylene-butylene copolymer elastomer (SEB), styrene-ethylene-propylene copolymer elastomer (SEP), styrene-ethylene-butylene-styrene copolymer elastomer (SEBS), styrene-ethylene-butylene-ethylene copolymer elastomer (SEBC), hydrogenated styrene-butadiene elastomer (HSBR), styrene-ethylene-propylene-styrene copolymer elastomer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer elastomer (SEEPS), styrene-butadiene-butylene-styrene copolymer elastomer (SBBS), partially hydrogenated styrene-isoprene-styrene copolymer elastomer, and partially hydrogenated styrene-isoprene-butadiene-styrene copolymer elastomer, as well as hydrogenated polymer-based elastomers such as ethylene-ethylene-butylene-ethylene copolymer elastomer (CEBC).
Among these, the use of an ethylene-octene copolymer elastomer (EOR) and/or an ethylene-butene copolymer elastomer (EBR) is preferred since it is easy to impart appropriate flexibility and the like to the polypropylene resin composition of the present invention and a molded article thereof, and they tend to have excellent impact resistance.

<<Method of manufacturing resin composition>>
The resin composition according to the present invention can be produced by a conventional method, and can be produced by blending, mixing, and melt-kneading the above-mentioned components.
The mixing is carried out using a mixer such as a tumbler, a V blender, or a ribbon blender, and the melt kneading is carried out using equipment such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll mixer, a Brabender plastograph, or a kneader, and the materials are melt kneaded and granulated.

<Molded body>
The molded article of the present invention can be obtained in a desired shape by molding the above-mentioned resin composition into a specific shape in a conventional manner.

(Application)
Examples of applications of the molded article of the present invention include various industrial parts such as automobile parts and electrical and electronic equipment parts. In particular, the molded article of the present invention is suitable for applications requiring excellent strength, rigidity, and electrical conductivity and a good balance of these properties, such as various housings and cases such as battery cases.

<Laminate>
The laminate of the present invention will be described with reference to FIG.
The molded article 10 of the present invention may be a laminate comprising a resin layer 12 made of the resin composition and a support layer 11 laminated on at least one surface of the resin layer 12. Such a configuration is preferable from the viewpoint of enhancing flame-proofing and heat-insulating properties.

<Support base>
The support layer is integrated with the resin layer to impart flame retardancy and flame shielding properties to the laminate. From the viewpoint of exerting these effects, the support layer is preferably a fiber layer made of fiber (X), and among these, a nonwoven fabric layer made of a nonwoven fabric, a woven fabric layer made of a woven fabric, or a knitted fabric layer made of a knitted fabric is preferable.
In particular, nonwoven fabrics are preferred in that a part of the resin layer can easily penetrate the surface of the support layer, resulting in higher binding properties, compared to woven fabrics or knitted fabrics, and also in that the orientation direction of the fibers in nonwoven fabrics is not fixed, so that the mechanical strength is not directional-dependent.

The thickness of the support layer is not particularly limited as long as it is within the range in which the effects of the present invention are achieved, but it is preferably 0.01 mm or more. If it is 0.01 mm or more, the binding with the resin layer is good, and the resin layer can be maintained even if the resin layer is exposed to flame. From the above viewpoints, the thickness of the support layer is more preferably 0.05 mm or more, and even more preferably 0.1 mm or more.
On the other hand, the upper limit of the thickness of the support layer is preferably 5 mm or less, more preferably 2 mm or less, even more preferably 1 mm or less, and particularly preferably 0.5 mm or less, in order to reduce the weight when formed into a molded body and from the standpoint of cost.

The size of the fibers (X) constituting the fiber layer is not limited as long as the effects of the present invention are achieved. However, the average fiber diameter is preferably in the range of 3 to 25 μm, and the average fiber length is preferably in the range of 5 to 100 mm.
When the average fiber diameter is 3 μm or more, handling during the manufacturing process of the fiber layer is easy, and when it is 25 μm or less, breakage is unlikely to occur. When the average fiber length is 5 mm or more, flame retardancy can be imparted to the laminate and sufficient strength can be imparted. On the other hand, when the average fiber length is 100 mm or less, breakage is unlikely to occur. The fiber length can be measured using a ruler, calipers, etc. from an image enlarged by a microscope or the like as necessary, and the average fiber length can be obtained, for example, by measuring the fiber lengths of 10 fibers randomly and calculating the average value.
The fiber (X) constituting the fiber layer is not particularly limited as long as it exhibits the effects of the present invention, and examples thereof include inorganic fibers such as glass fibers, carbon fibers, boron fibers, ceramic fibers, metal fibers, and metal oxide fibers, and organic fibers such as aramid fibers and aromatic polyester fibers. Among these, inorganic fibers are preferred because they provide excellent flame retardancy, and among these, glass fibers, ceramic fibers, metal fibers, and metal oxide fibers are preferred, with glass fibers being particularly preferred.

<<Nonwoven fabric layer>>
The nonwoven fabric layer is composed of a nonwoven fabric. The fibers constituting the nonwoven fabric are not particularly limited as long as they can produce the effects of the present invention, and include inorganic fibers such as glass fibers, carbon fibers, boron fibers, ceramic fibers, metal fibers, and metal oxide fibers, and organic fibers such as aramid fibers and aromatic polyester fibers. Among these, inorganic fibers are preferred because they provide excellent flame-proofing properties, and among these, glass fibers, ceramic fibers, metal fibers, and metal oxide fibers are preferred, with glass fibers being particularly preferred.

(Glass fiber nonwoven fabric)
Examples of the form of the glass fiber nonwoven fabric that can be suitably used in the present invention include felts and blankets processed with short fiber glass wool, chopped strand mats processed with continuous glass fibers, swirl (spiral) mats of continuous glass fibers, unidirectionally aligned mats, etc. Among these, the use of a glass fiber mat obtained by needle punching a swirl (spiral) mat of continuous glass fibers is particularly preferred because it provides excellent strength and impact resistance of the laminate.
The glass fibers are the same as those described above in relation to the (C) fiber.

The ceramic fibers are preferably fibers made mainly of silica and alumina, for example, in a range of silica:alumina=40:60 to 0:100. Specifically, silica-alumina fibers, mullite fibers, and alumina fibers can be used.
As the material of the metal fiber, fibers mainly composed of iron, copper, aluminum, nickel, tungsten, titanium, molybdenum, beryllium, platinum, etc. are preferable. Furthermore, in addition to the above metals, the alloy component may contain one or more of carbon, nitrogen, chromium, cobalt, gold, silver, etc. From the viewpoint of excellent strength and corrosion resistance, fibers mainly composed of stainless steel, nickel, or titanium are particularly preferable.
Examples of materials that can be used for the metal oxide fibers include alkaline earth metal oxides such as magnesium oxide and calcium oxide, Group 4 metal oxides such as titanium oxide and zirconium oxide, oxides of Group 13 elements such as alumina and indium oxide, oxides of Group 14 elements such as silica, tin oxide and lead oxide, and oxides of Group 15 elements such as antimony oxide. Among these, in terms of effectively obtaining a high level of heat resistance, preferred are oxide fibers of Group 13 to Group 15 elements, more preferred are oxide fibers of Group 13 elements, and particularly preferred are alumina fibers.

There are no limitations on the size of the fibers constituting the nonwoven fabric as long as the effects of the present invention are achieved, but the average fiber diameter is preferably in the range of 3 to 25 μm, and the average fiber length is preferably in the range of 5 to 100 mm.
When the average fiber diameter is 3 μm or more, handling during the manufacturing process of the nonwoven fabric is easy, and when it is 25 μm or less, breakage is unlikely to occur. Furthermore, when the average fiber length is 5 mm or more, flame retardancy can be imparted to the laminate, and sufficient strength can be imparted. On the other hand, when the average fiber length is 100 mm or less, breakage is unlikely to occur. From the above viewpoints, the average fiber length is more preferably in the range of 10 to 50 mm, and even more preferably in the range of 15 to 30 mm.
The average fiber length can be measured by the above-mentioned method.

The basis weight (fiber amount per unit area) of the nonwoven fabric is preferably in the range of 10 to 500 g/m ^2. When the basis weight is 10 g/m ² or more, the flame-resistant property of the laminate and sufficient strength of the laminate are obtained. On the other hand, when it is 500 g/m ² or less, the binding with the resin layer is good, sufficient flame-resistant property of the laminate is obtained, and the weight does not become excessively large. From the above viewpoints, the basis weight is more preferably in the range of 20 to 300 g/m ² , further preferably in the range of 30 to 150 g/m ² , and particularly preferably in the range of 35 to 100 g/m ² .

As a method for manufacturing nonwoven fabric, a conventionally known method can be used, such as a dry method, a wet method, a spunbond method, a meltplane method, an airlaid method, etc. In addition, as a method for bonding the fibers of the nonwoven fabric obtained by these manufacturing methods, a conventional method such as a chemical bond method, a thermal bond method, a needle punch method, a hydroentanglement method, etc. can be used.

<<Woven fabric layer>>
The woven fabric layer is made of a woven fabric. The fibers constituting the woven fabric are not particularly limited as long as they can produce the effects of the present invention, and the same fibers as those exemplified for the nonwoven fabric layer can be used. As with the nonwoven fabric layer, inorganic fibers are preferred, and glass fibers are particularly preferred.
The size (average fiber diameter, average fiber length) and basis weight of the fibers constituting the woven fabric are also the same as those described for the nonwoven fabric layer.
The weave of the woven fabric made of the above fibers is not particularly limited, and may be any of plain weave, twill weave, satin weave, and the like.

<<Knitted layer>>
The knitted fabric layer is made of a knitted fabric. The fibers constituting the knitted fabric are not particularly limited as long as they can achieve the effects of the present invention, and the same fibers as those exemplified for the nonwoven fabric layer can be used. As with the nonwoven fabric layer, inorganic fibers are preferred, and glass fibers are particularly preferred.
The size (average fiber diameter, average fiber length) and basis weight of the fibers constituting the knitted fabric are also the same as those described for the nonwoven fabric layer.
The structure of the knitted fabric made of the above fibers is not particularly limited, and may be any of rib stitch, garter stitch, meliace stitch, and the like.

<Method of manufacturing laminate>
The method for producing the laminate of the present invention is not particularly limited, and various known methods can be used.Specific examples include a method in which a resin layer and a support layer are formed in advance and then laminated together, and a method in which the support layer is set in a mold and a resin composition for forming the resin layer is injected into the mold to perform injection molding.
As a method for bonding, for example, a resin sheet for constituting the resin layer and a glass fiber nonwoven sheet for constituting the support layer are prepared in advance, and these are laminated and heated and pressed.
More specifically, this method involves press-molding a resin sheet and a glass fiber nonwoven sheet in a mold equipped with a heating device.
The heating temperature is preferably 170 to 300° C. If the heating temperature is 170° C. or higher, the resin layer and the support layer are sufficiently bonded to each other, and the flame-proofing property of the laminate is improved. On the other hand, if the heating temperature is 300° C. or lower, the resin composition constituting the resin layer is not deteriorated.
The pressure applied is preferably 0.1 to 1 MPa. If the pressure applied is 0.1 MPa or more, the resin layer and the support layer are sufficiently bonded to each other, and the flame-proofing property of the laminate is improved. On the other hand, if the pressure applied is 1 MPa or less, no burrs are generated in the resin layer.
In addition, when laminating, an adhesive layer can be disposed between the resin layer and the support layer. However, since the adhesiveness between the resin layer and the support layer is important in the present invention, it is preferable that the resin layer and the support layer are directly bonded to each other without any other layer therebetween.
The cooling temperature is not particularly limited as long as it is equal to or lower than the solidification point of the thermoplastic resin, but if the cooling temperature is equal to or lower than 80° C., the obtained molded body will not deform when it is taken out. From the above viewpoints, the cooling temperature is preferably from room temperature to 80° C.

Alternatively, a lamination process may be used in which the resin sheet and the glass fiber nonwoven sheet are heated and pressurized by passing them between two pairs of rollers equipped with a heating device. Lamination processes are preferable because they allow continuous production and have good productivity.

As a method for producing a molded body by injection molding, for example, a method as shown in FIG. 5 can be used. That is, a glass nonwoven fabric that will become the support layer 15 is set in a movable mold 21, the movable mold 21 is fitted into a fixed mold 22, and a resin composition 16 is injected into the cavity to integrally mold the resin composition 16 and the glass nonwoven fabric (support layer 15). This method can obtain the laminate 10 of the present invention in which the support layer 11 is laminated on one side of the resin layer 12. When this injection molding method is used, the long fibers in the glass nonwoven fabric are maintained without breaking, so that the flame-resistant properties of the molded body of the present invention can be further improved.

The following method is a suitable example of the method for producing the laminate of the present invention. That is, the method for producing a laminate includes a step of impregnating a support with a resin composition to form a support layer laminated on at least one surface of a resin layer. The method for impregnating a support with a resin composition is not particularly limited, and may be a method of press-molding a resin sheet and a support while heating them in a mold equipped with a heating device, or a method of placing a support in an injection mold in advance and injecting a resin. The thickness of the support before impregnating with the resin composition is preferably 0.01 to 30 mm. As described later, the thickness of the support used in the production of the laminate may differ from the thickness of the support layer in the produced laminate. This is because the support is compressed during the production process of the laminate. For this reason, it is desirable to take the compression of the support into consideration when producing the laminate. If the thickness of the support before impregnating with the resin composition is within the above range, the productivity of the laminate and the flame-proofing and strength of the obtained laminate are excellent. From the above viewpoints, the thickness of the support is more preferably from 0.05 to 15 mm, further preferably from 0.08 to 10 mm, even more preferably from 0.1 to 5 mm, and particularly preferably from 0.2 to 3 mm.
In the method for producing the laminate, the compression ratio of the support, defined as the ratio of the thickness of the support layer in the laminate to the thickness of the support before impregnation with the resin composition, is preferably 15 to 75%. When the compression ratio of the support is within this range, the productivity of the laminate and the flame-proofing and strength of the obtained laminate are excellent. From the above viewpoints, the compression ratio of the support is more preferably 20 to 60%, further preferably 25 to 50%, and particularly preferably 30 to 40%.

<Other aspects of the laminate>
The laminate of the present invention has a resin layer and a support layer, and the support layer may be on one side of the resin layer, but as shown in Fig. 3, the laminate may have support layers 11 on both sides of the resin layer 12. In this embodiment, since the support layer 11 comes into contact with flame, the support layer 11 that comes into contact with flame no longer functions as a support layer, but the other support layer 11 functions as a support layer, and thus exhibits flame-blocking properties by the same mechanism of action as described above.
In addition, in this embodiment, since the support layers 11 are provided on both sides of the resin layer 12, warping does not occur in the laminate, which is preferable.

Furthermore, the laminate 10 of the present invention may have two resin layers 12 sandwiching the support layer 11, as shown in FIG. 4. In this embodiment, the effect of the present invention is achieved regardless of whether the upper or lower surface is exposed to flame.

(Application)
Examples of applications of the laminate of the present invention include various parts in the industrial field, such as automobile parts and electrical and electronic equipment parts. In particular, since the laminate has high flame retardancy and excellent flame shielding properties, it can be suitably used for various housings and cases, such as battery cases.
In particular, it is preferably used as a battery case, and the battery is not particularly limited. For example, secondary batteries such as lithium ion batteries, nickel-hydrogen batteries, lithium-sulfur batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, sodium-sulfur batteries, lead-acid batteries, and air batteries can be mentioned. Among these, lithium ion batteries are preferred, and in particular, they are suitably used to suppress thermal runaway of lithium ion batteries.

The battery is also useful for electric mobility, such as vehicles, ships, airplanes, and other transportation equipment that run on electricity as an energy source. In terms of vehicles, this includes hybrid cars in addition to electric vehicles (EVs).
Structures such as battery housings and batteries having battery cells using the laminate of the present invention are highly safe and extremely useful for electric mobility using battery modules with high energy density to extend driving distance.

The present invention will be described in detail below using examples, but the present invention is not limited to these examples.
1 is a graph showing temperature curves of the rear surfaces of molded articles obtained in a flame-proofing test for Examples 1 to 4 and Comparative Example 1.

(Evaluation method)
1. Evaluation of flame-proofing The molded bodies (injection test pieces) prepared in each Example and Comparative Example were evaluated by applying a 1200°C burner flame from the surface on the resin layer 12 side as shown in FIG. 2, and whether the flame penetrated after 15 minutes. The distance from the burner nozzle to the sample was 110 mm. The flame surface was set to 1200°C. The flame surface temperature was confirmed with a thermocouple thermometer. Note that as the injection test pieces, test pieces with a thickness of 2.0 mm, a width of 200 mm, and a length of 200 mm were used. The evaluation criteria are as follows.
Evaluation criteria: ◯: The flame did not penetrate.
×: The flame penetrated.
FIG. 6 shows the temperature curves of the rear surfaces of the molded articles obtained in the flame-shielding test for Examples 1 to 4 and Comparative Example 1.
2. Evaluation of heat insulation In the flame-shielding evaluation described in 1 above, the temperature of the surface (back surface) of the test piece opposite to the surface exposed to the burner flame was measured with a non-contact radiation thermometer (FT-H50K manufactured by Keyence Corporation). The measurement area was φ35 mm. The measurement area was visually set so that the center of the measurement area was located immediately above the position of the burner flame. Table 3 shows the back surface temperature (°C) after 400 seconds had elapsed, and the elapsed time (seconds) when the back surface temperature first reached 400°C.

(1) Preparation of Resin Composition The following materials were prepared as raw materials for the resin composition.
(a) Polypropylene resin (component (A))
"Novatec (registered trademark) BC03B" (Melt flow rate: 30 g/10 min) manufactured by Japan Polypropylene Corporation
"Novatec (registered trademark) BC05B" (Melt flow rate: 50 g/10 min) manufactured by Japan Polypropylene Corporation
(b) Flame retardant (component (B))
Phosphorus-based flame retardant (ADEKA Corporation, Adeka STAB FP-2500S, halogen-free intumescent flame retardant)
(c) Dispersant (Component (D))
α-Olefin-maleic anhydride copolymer (Mitsubishi Chemical Corporation, Diacalna 30M, weight average molecular weight 7,800)
(d) Antioxidant (d-1) Phenol-based antioxidant (manufactured by ADEKA CORPORATION, Adeka STAB AO-60)
(d-2) Phosphite-based antioxidant (ADEKA STAB 2112, manufactured by ADEKA CORPORATION)
(e) Glass fiber reinforced thermoplastic resin (GF reinforced resin, (A) component + (C) component)
"Funcster (registered trademark) LR25Z" (polypropylene resin/glass fiber = 50/50, pellet length 10 mm) manufactured by Japan Polypropylene Corporation

The above (a) polypropylene resin, (b) flame retardant, (c) dispersant, (d) antioxidant, and (e) GF reinforced resin were mixed to prepare a resin composition so that the ratio of each component was as shown in Table 1 below. Although not shown in Table 1, the ratios of the phenol-based antioxidant (d-1) and the phosphite-based antioxidant (d-2) were both 0.007 parts by mass.

(2) Raw Materials for the Molded Body (Laminate) The following raw materials for the laminate were prepared.
(f) Support layer (f-1): Glass nonwoven fabric (manufactured by Orivest Co., Ltd., FAP-035, basis weight 35 g/m ² , thickness 0.26 mm)
(f-2) Glass nonwoven fabric (Oji F-Tex Co., Ltd., GMC-50G, basis weight 50 g/m ² , thickness 0.36 mm)
(f-3) Glass nonwoven fabric (Oji F-Tex Co., Ltd., GMC-75G, basis weight 75 g/m ² , thickness 0.53 mm)
(f-4) Aramid nonwoven fabric (Oji F-Tex Co., Ltd., APT36, basis weight 36 g/m ² , thickness 0.50 mm)

[Example 1]
The resin composition obtained in (1) above was laminated on a support layer (f) using an injection molding machine "FANUC ROBOSHOT α-S300iA" manufactured by FANUC LTD., to produce a sample for evaluating flame retardancy.
Specifically, the (f-1) glass nonwoven fabric was placed in a mold in advance, and a resin composition having the composition shown in Table 1 was injection molded thereon to prepare a test piece having a length of 200 mm, a width of 200 mm, and a thickness of 2.0 mm. The final composition is shown in Table 2. The glass fibers in Table 2 also include the glass fibers derived from the (f-1) support layer.
The resin layer of the obtained evaluation sample (laminate) had a thickness of 1.89 mm, and the nonwoven fabric layer (support layer) had a thickness of 0.11 mm.
The obtained evaluation samples were used to evaluate the flame-proofing properties, and the results are shown in Table 2. The main molding conditions were as follows.
1) Temperature conditions: cylinder temperature (220°C), mold temperature (60°C)
2) Injection conditions: injection pressure (200 MPa), holding pressure (82 MPa)
3) Metering conditions: screw rotation speed (50 rpm), back pressure (15 MPa)

[Example 2]
An evaluation sample was obtained in the same manner as in Example 1, except that (f-2) was used instead of (f-1) in Example 1. The resin layer of the obtained evaluation sample (laminate) had a thickness of 1.86 mm, and the nonwoven fabric layer (support layer) had a thickness of 0.14 mm. The obtained evaluation sample was used to perform a flame-blocking evaluation, and the results are shown in Table 2.

[Example 3]
An evaluation sample was obtained in the same manner as in Example 1, except that (f-3) was used instead of (f-1) in Example 1. The resin layer of the obtained evaluation sample (laminate) had a thickness of 1.84 mm, and the nonwoven fabric layer (support layer) had a thickness of 0.16 mm. The obtained evaluation sample was used to perform a flame-blocking evaluation, and the results are shown in Table 2.

[Example 4]
An evaluation sample was obtained in the same manner as in Example 1, except that (f-4) was used instead of (f-1) in Example 1. The resin layer of the obtained evaluation sample (laminate) had a thickness of 1.83 mm, and the nonwoven fabric layer (support layer) had a thickness of 0.17 mm. The obtained evaluation sample was used to perform a flame-blocking evaluation, and the results are shown in Table 2.

[Comparative Example 1]
A test piece was obtained in the same manner as in Example 1, except that the (f) support layer was not used. The test piece was a molded body consisting of only a resin layer. The flame-proofing property was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Temperature curve analysis]
The temperature curve of the back side obtained when the molded body of Example 1 was evaluated for heat insulation by the above method was approximated as a sixth-order polynomial using the least squares method to obtain a smoothed curve. The smoothed curve was differentiated twice to obtain an inflection point. A graph in which the smoothed curve and the obtained inflection points are plotted on the smoothed curve is shown in FIG. 7. In addition, the area (X1) of the region surrounded by the line segment connecting the first inflection point and the third inflection point on the smoothed curve and the smoothed curve was calculated. In addition, the area (Y) of the region surrounded by the line segment connecting the first inflection point and the smoothed curve and the point where the smoothed curve first reaches 50°C was calculated. Finally, the area (X1) was divided by the area (Y) to be normalized. The results are shown in Table 3.
The temperature curves were similarly analyzed for Examples 2 to 4 and Comparative Example 1. The smoothed curves and graphs in which the obtained inflection points are plotted on the smoothed curves are shown in Figures 8 to 11. The analysis results are shown in Table 3.

The molded bodies of Examples 1 to 4 showed very good results, with no penetration of the flame even when exposed to a 1200°C burner flame for 15 minutes. On the other hand, when the molded body of Comparative Example 1 was exposed to a burner flame under the same conditions, the flame penetrated it after about 95 seconds.

The molded article of the present invention has extremely excellent flame resistance and is therefore useful as a material for various industrial parts that require high safety, such as aircraft, ships, automobile parts, electrical and electronic equipment parts, building materials, etc. In particular, it can be suitably used for various battery housings and cases that have traditionally been made of metal, and is expected to contribute to the safety of automobiles as well as improve energy efficiency and reduce _CO2 emissions by reducing weight.

REFERENCE SIGNS LIST 10 Laminate 11 Support layer 12 Resin layer 13 Flame retardant 14 Fiber 15 Support layer 16 Resin composition 21 Movable mold 22 Fixed mold

Claims (17)

A molded article made of a resin composition containing (A) a thermoplastic resin, (B) a phosphorus-based flame retardant, and (C) fibers, wherein when an inflection point is obtained from a second-order differential of a smoothed curve obtained by smoothing a temperature curve of the surface of the molded article obtained by the following test method (i) using polynomial approximation, the molded article has a second inflection point.
Test method (a): The surface of the molded body is exposed to a flame from a burner so that the flame front is 1200°C, and the temperature of the surface opposite the flame-exposed surface is measured with a non-contact thermometer. A curve is obtained by plotting the surface temperature against the elapsed time up to t = 200 seconds. The molded body according to claim 1, wherein the second inflection point occurs after t = 40 seconds. The molded body according to claim 1, wherein the second inflection point occurs within t = 180 seconds. The molded body according to claim 1, wherein the second inflection point is present at or below 400°C. The molded body according to claim 1, wherein the ratio (area (X1)/area (Y)) of the area (X1) of the region surrounded by the line segment connecting the first inflection point and the third inflection point on the smoothed curve obtained by the second differentiation and the area (Y) of the region surrounded by the line segment connecting the point at 50°C and the first inflection point and the smoothed curve is 1.0 or more. The molded body according to claim 1, wherein the ratio (area (X2)/area (Y)) of the area (X2) of the region surrounded by the line segment connecting the second inflection point and the third inflection point on the smoothed curve obtained by the second differentiation and the area (Y) of the region surrounded by the line segment connecting the point at 50°C and the first inflection point and the smoothed curve is 0.5 or more. The molded article according to claim 1, 4 or 5, wherein the resin composition further contains (D) a dispersant. The molded article according to claim 7, wherein the dispersant (D) is a copolymer of an α-olefin and an unsaturated carboxylic acid. The molded article according to claim 1, 4 or 5, wherein the (B) phosphorus-based flame retardant is an intumescent flame retardant. The molded body according to claim 1, 4 or 5, wherein the (C) fibers are inorganic fibers. The molded body according to claim 10, wherein the inorganic fibers are at least one selected from glass fibers, ceramic fibers, metal fibers, and metal oxide fibers. The molded body according to claim 1, 4, or 5, which is a laminate having a resin layer made of the resin composition and a support layer made of fibers. The molded body according to claim 12, wherein the support layer made of the fibers is a nonwoven fabric layer made of a nonwoven fabric, a woven fabric layer made of a woven fabric, or a knitted fabric layer made of a knitted fabric. The molded body according to claim 12, wherein the fibers constituting the support layer are inorganic fibers. The molded body according to claim 14, wherein the inorganic fibers are at least one selected from glass fibers, ceramic fibers, metal fibers, and metal oxide fibers. The molded article according to claim 1, 4, or 5, wherein the thermoplastic resin (A) is a polypropylene-based resin, and the content of the polypropylene-based resin in the resin composition is 15 to 80 mass %. The molded article according to claim 1, 4, or 5, wherein the content of the phosphorus-based flame retardant (B) in the resin composition is 1 to 40 mass %.