Horizontal member for automobiles and method for manufacturing same

Abstract

The present invention provides a horizontal member for automobiles, which can be easily molded and has little resin drip after a combustion test.　The present invention specifically provides a horizontal member for automobiles, which contains reinforcing fibers that have a weight average fiber length of 5 mm to 100 mm, a resin, and a flame retardant, wherein the content of the flame retardant is 1 part by mass to 50 parts by mass relative to 100 parts by mass of the resin, and the requirements (a) and (b) described below are satisfied.　(a) The tensile strength retention rate represented by formula (1) is 0.04% or more.　Formula (1): Tensile strength retention rate (%) = (tensile strength B after combustion) / (tensile strength A before combustion) × 100 (b) The amount of work per basis weight in a tensile test of a 25 mm wide test piece after a combustion test is 0.5 × 10-3 to 100 × 10-3 ((N∙mm) / (g / m2)), and the maximum load per basis weight is 1.1 × 10-3 (N / (g / m2)) or more.

Description

Horizontal member for automobile and manufacturing method thereof

[0001] The present invention relates to a horizontal member for an automobile, which contains reinforcing fibers having a weight average fiber length of 5 mm or more and 100 mm or less, a resin, and a flame retardant, and a method for manufacturing the same.

[0002] Molding materials that use reinforcing fibers as reinforcements have high tensile strength and tensile modulus, and a small coefficient of linear expansion, resulting in excellent dimensional stability. Furthermore, they have excellent heat resistance, chemical resistance, fatigue resistance, and abrasion resistance, so molding materials that use reinforcing fibers are widely used in a variety of applications, including automobiles, sports and leisure, aerospace, and general industrial applications.

[0003] Patent Document 1 describes a stampable sheet and stampable sheet molded product produced by a papermaking method that are excellent in flame retardancy.

[0004] Patent Documents 2 and 3 describe flame-retardant resin compositions that utilize needle-punched swirl mats or sheets of continuous glass fibers.

[0005] Patent Document 4 describes a self-extinguishing resin molded article obtained from a resin composition containing a polyolefin resin, a phosphorus-based flame retardant, and glass fibers. Patent Document 5 describes a work load per unit area in a tensile test using a 25 mm wide test piece of 1×10 －３ ~30 x 10 －３ [(N・mm) / (g / m ２ ) as a reinforcing material and a thermoplastic resin as a matrix resin.

[0006] Japanese Patent Application Publication No. 11-49869 Publication of Japanese Patent Application Publication No. 63-183845 Publication WO2022 / 220303 Publication WO2020 / 071420 Publication WO2013 / 179891 Publication

[0007] However, the invention described in Patent Document 1 is produced using a papermaking method, resulting in excessive springback during molding and poor moldability. Furthermore, no consideration has been given to its use as a horizontal member for automobiles. Further problems with the invention described in Patent Document 1 include: (1) poor moldability and high manufacturing costs due to the addition of too much flame retardant; (2) the specific gravity of the resulting molded body is too high due to the inclusion of a large amount of metal hydrate as a flame retardant; (3) the use of a halogen-based flame retardant raises concerns about harmful effects such as the generation of phosphine; and (4) in the case of horizontal members for automobiles, it is necessary to prevent the members from sagging during combustion (sometimes referred to as resin dripping), which is particularly noticeable when the horizontal members for automobiles are large in size.

[0008] The inventions described in Patent Documents 2 and 3 utilize a needle-punched swirl mat or sheet of continuous glass fibers, which has problems such as the tendency for surface fluffing to occur, poor fluidity resulting in poor moldability, and, when a metal hydrate is used, the specific gravity of the resulting molded body becoming large.

[0009] In the invention described in Patent Document 4, the fiber length is too short because the molded body is mainly produced using injection molding. This results in little entanglement of the fibers, resulting in large resin drips during combustion tests of the molded body. If a molded body with large resin drips is used, for example, in a battery cover, there is a risk of the battery exploding. In the invention described in Patent Document 5, the work load value is too large. As a result, the springback is too large, significantly deteriorating moldability, and no consideration has been given to the flame retardancy of the material for use as a horizontal member for an automobile.

[0010] In order to solve the above problems, the present invention provides the following means: 1. A horizontal member for an automobile comprising reinforcing fibers having a weight-average fiber length of 5 mm to 100 mm, a resin, and a flame retardant, wherein the flame retardant is present in an amount of 1 part by mass to 50 parts by mass per 100 parts by mass of the resin, and the horizontal member for an automobile satisfies the following (a) and (b): (a) The tensile strength retention rate, as shown in formula (1), is greater than 0.03%: Tensile strength retention rate (%) = (tensile strength B after combustion / tensile strength A before combustion) × 100 ... formula (1) (b) The work load per unit area in a tensile test using a 25 mm wide test piece after a combustion test is 0.5 × 10 －３ [(N・mm) / (g / m ２ ) ] or more 100 x 10 －３ [(N・mm) / (g / m ２ ) )] or less, and the maximum load per unit area is 1.1 x 10 －３ [N / (g / m ２ 2. The horizontal member for an automobile according to 1 above, which has a maximum load per unit area in a range of strain greater than 0% and less than 2% in a tensile test using a 25 mm wide test piece after a combustion test. 3. The horizontal member for an automobile according to 1 or 2 above, which satisfies the following (c): (c) In a tensile test using a 25 mm wide test piece after a combustion test, the maximum load per unit area is greater than or equal to the load [N / (g / m ２ ) ] the average rate of change is 0.1 × 10 －３ Above 100 x 10 －３ 4. The horizontal member for an automobile according to 3 above, which satisfies the following (d): (d) In a tensile test using a test piece having a width of 25 mm after a combustion test, the load [N / (g / m ２ ) ] the average rate of change is -1.0 × 10 －３ [N / (g / m ２ ) ] or more - 0.01 × 10 －３ [N / (g / m ２) or less. 5. The horizontal member for an automobile according to any one of items 1 to 4, wherein the resin is a thermoplastic resin. 6. The horizontal member for an automobile according to any one of items 1 to 5, wherein the resin is a polypropylene resin. 7. The horizontal member for an automobile according to any one of items 1 to 6, wherein the reinforcing fibers are glass fibers. 8. The horizontal member for an automobile according to any one of items 1 to 7, wherein the horizontal member for an automobile is a battery cover or a battery bottom protective cover. 9. The horizontal member for an automobile according to any one of items 1 to 8, wherein the resin is a thermoplastic resin and the springback rate of the horizontal member for an automobile is 1.2 or more and 8.0 or less. 10. A method for manufacturing the horizontal member for an automobile according to any one of items 1 to 9, by cold-pressing a molding material containing reinforcing fibers and a thermoplastic resin, wherein the springback rate of the molding material is 1.2 or more and 8.0 or less. 11. 11. The method for manufacturing a horizontal member for an automobile according to 10 above, wherein the reinforcing fibers are glass fibers, and a molding material is prepared by mixing single-end roving glass fibers GFs and multi-end roving glass fibers GFm in a volume ratio of GFm:GFs of 90:10 to 50:50.

[0011] The horizontal member for an automobile of the present invention satisfies the following (a) and (b), and therefore not only has excellent moldability but also little resin dripping after a combustion test. (a) The tensile strength retention rate shown by formula (1) is 3% or more. Tensile strength retention rate (%) = (tensile strength B after combustion / tensile strength A before combustion) × 100 ... formula (1). (b) The work load per unit area in a tensile test using a 25 mm wide test piece after a combustion test is 0.5 × 10 －３ Above 100 x 10 －３ Below [(N・mm) / (g / m ２ )].

[0012] 1 is a schematic diagram showing a state in which a test piece is being subjected to a combustion test. 2 is a schematic diagram showing an example of a vehicle structure provided with a battery bottom protective cover under a battery box, which is an example of a case in which the horizontal member of the present invention is used in a battery cover or battery tray. 3 is an example of a graph showing a load-strain curve in a tensile test of the test piece of Example 1. 4 is an example of a graph showing a load-strain curve in a tensile test of Example 5.

[0013] The present invention will be described in detail below.

[0014] [Reinforcing Fiber] In this specification, the reinforcing fiber is preferably at least one selected from the group consisting of carbon fiber, aramid fiber, and glass fiber, and more preferably carbon fiber or glass fiber.

[0015] [Carbon Fiber] 1. Carbon Fibers in General Generally, polyacrylonitrile (PAN)-based carbon fibers, petroleum / coal pitch-based carbon fibers, rayon-based carbon fibers, cellulose-based carbon fibers, lignin-based carbon fibers, phenol-based carbon fibers, and the like are known as carbon fibers for use in the present invention, and any of these carbon fibers can be suitably used in the present invention. Among these, polyacrylonitrile (PAN)-based carbon fibers are preferably used in the present invention because of their excellent tensile strength. As a PAN-based carbon fiber, for example, the carbon fiber "Tenax" (registered trademark) STS40-24KS (average fiber diameter 7 μm) manufactured by Teijin Limited can be used.

[0016] 2. Sizing Agent for Carbon Fiber The carbon fiber used in the present invention may have a sizing agent attached to its surface. When using carbon fiber with a sizing agent attached, the type of sizing agent can be appropriately selected depending on the type of carbon fiber and the type of resin used for the horizontal member for an automobile, and is not particularly limited.

[0017] [Glass Fiber] The case where the reinforcing fiber used in the present invention is a glass fiber will be described. 1. Glass Fiber in General The glass fiber used in the present invention may be any glass fiber that is generally called a glass fiber. There is no particular limitation on the glass composition such as A-glass, C-glass, E-glass, etc., and in some cases, TiO ２ , S.O. ３ , P ２ O ５ The glass fiber may contain components such as RV P204-4800TEX manufactured by Owens Corning.

[0018] 2. Sizing Agent for Glass Fiber The glass fiber used in the present invention may have a sizing agent attached to its surface. When using glass fiber with a sizing agent attached, the type of sizing agent can be appropriately selected depending on the type of glass fiber and the type of resin, and is not particularly limited. Glass fiber that has been pre-treated with a conventionally known coupling agent such as an organosilane compound, an organotitanium compound, an organoborane compound, or an epoxy compound can be preferably used.

[0019] 3. To prepare the molding material of the present invention, it is preferable to mix glass fibers GFs of single-end rovings and glass fibers GFm of multi-end rovings in a volume ratio of GFm:GFs of 50:50 to 90:10. When the ratio of GFm is 50% or more, the workload can be easily kept below the upper limit. When GFm is 90% or less, the workload can be kept below the lower limit.

[0020] A multi-end roving is a roving in which the ends of the glass strands are not aligned. The glass fibers of a multi-end roving have multiple ends (multiple). A single-end roving is a roving in which the ends of the glass strands are aligned. The glass fibers of a single-end roving have one end (single).

[0021] [Dispersion in the in-plane direction] The reinforcing fibers contained in the horizontal structural member for an automobile are preferably dispersed in the in-plane direction. Furthermore, the horizontal structural member for an automobile of the present invention is preferably produced by cold pressing a molding material containing reinforcing fibers and a thermoplastic resin. In this case, it is more preferable that the reinforcing fibers contained in the molding material are dispersed in the in-plane direction.

[0022] The reinforcing fibers being dispersed in the in-plane direction means that the reinforcing fibers are dispersed so that their fiber axes are oriented in the in-plane direction. It is preferable that the angle between the fiber axes of the reinforcing fibers and the in-plane direction is 45° or less.

[0023] 1. In-plane direction The molding material for manufacturing a horizontal component for an automobile is preferably a plate-shaped material. The in-plane direction is an indefinite direction of a parallel plane perpendicular to the plate thickness direction of the molding material.

[0024] 2. Random Dispersion in Two Dimensions It is preferable that the reinforcing fibers are randomly dispersed in two dimensions in the in-plane direction. When the molding material is press-molded without flow (in the case of non-flow molding), the shape of the reinforcing fibers is largely maintained before and after molding. In the case of non-flow molding, it is preferable that the reinforcing fibers contained in the molding material are randomly oriented in two dimensions, so that the reinforcing fibers contained in the horizontal component (molded body) for an automobile molded from the molding material are also randomly dispersed in two dimensions in the in-plane direction.

[0025] Here, "dispersed two-dimensionally at random" refers to a state in which the reinforcing fibers are not oriented in a specific direction in the in-plane direction of the molding material but are oriented randomly, and are arranged in the sheet plane without showing any specific directionality overall. A molding material (or molded body) obtained using discontinuous fibers dispersed two-dimensionally at random is a substantially isotropic molding material (or molded body) that does not have anisotropy in the plane.

[0026] The degree of two-dimensional random orientation is evaluated by calculating the ratio of the tensile modulus in two mutually perpendicular directions. The reinforcing fibers can be evaluated as being two-dimensionally randomly dispersed if the (Eδ) ratio, calculated by dividing the larger of the tensile modulus values ​​measured in any direction of the molding material (or molded body) by the smaller of the two measured values ​​in the direction perpendicular to that direction, is 5 or less, more preferably 2 or less, and even more preferably 1.5 or less. When a horizontal automotive component includes a curved surface, the two-dimensional random dispersion in the in-plane direction can be evaluated by heating the component above the softening temperature, returning it to a flat plate shape, and then solidifying it. Then, test specimens can be cut out and the tensile modulus measured to confirm the state of random dispersion in the two-dimensional direction.

[0027] [Fiber length of reinforcing fibers] The horizontal component for an automobile according to the present invention has a weight-average fiber length of 5 mm to 100 mm. Since the weight-average fiber length of the molding material and the horizontal component for an automobile (molded body) does not change before and after molding, the weight-average fiber length Lw of the reinforcing fibers contained in the molding material can be determined by examining the weight-average fiber length of the reinforcing fibers contained in the horizontal component for an automobile (molded body).

[0028] The lower limit of the weight average fiber length of the reinforcing fibers is preferably 7 mm or more, more preferably 10 mm or more. Conversely, the upper limit of the weight average fiber length is preferably 80 mm or less, more preferably 70 mm or less. When the weight average fiber length is 5 mm or more, the mechanical strength of the resulting fiber-reinforced resin member is less likely to decrease, which is preferable. When the weight average fiber length is 100 mm or less, the fluidity of the material is less likely to decrease when the molding material is press-molded, making it easier to create a fiber-reinforced resin member in the desired shape. The preferred range of the weight average fiber length of the reinforcing fibers is 5 mm or more and 80 mm or less, more preferably 10 mm or more and 60 mm or less.

[0029] [Number average fiber length Ln and weight average fiber length Lw] Generally, when the fiber length of each reinforcing fiber is Li, the number average fiber length Ln and weight average fiber length Lw can be calculated by the following formulas (X) and (Y): The number average fiber length Ln and weight average fiber length Lw are expressed in mm. Here, "I" indicates the number of reinforcing fibers measured.​

[0030] When the fiber length is constant, the number-average fiber length and the weight-average fiber length are the same value. Reinforcing fibers can be extracted from the door inner panel by, for example, subjecting it to a heat treatment at 500°C for about 1 hour and removing the resin in a furnace.

[0031] The average fiber length can be calculated, for example, by measuring the fiber lengths of 100 fibers randomly extracted from a door inner panel to the nearest 1 mm using a vernier caliper or the like, and then calculating the average fiber length based on formula (X).

[0032] If short fibers that cannot be measured with a caliper are included, the resin is removed, and the resulting reinforcing fibers are placed in water containing a surfactant and thoroughly stirred with ultrasonic vibration. Samples of the stirred dispersion are randomly collected with a measuring spoon to obtain evaluation samples, and the lengths of 3,000 fibers are measured using a Luzex AP image analyzer manufactured by Nireco Corporation. Using the measured fiber lengths, the number-average fiber length Ln and weight-average fiber length Lw can be calculated in the same manner as in the above-mentioned formulas (X) and (Y).

[0033] [Volume Fraction of Reinforcing Fibers] The reinforcing fiber volume fraction (Vf) of the reinforcing fibers contained in the horizontal member for an automobile can be calculated by the following formula (3): Reinforcing fiber volume fraction (Vf) = 100 × reinforcing fiber volume / (reinforcing fiber volume + resin volume) Formula (3) There are no particular limitations on the reinforcing fiber volume fraction, but the reinforcing fiber volume fraction (Vf) is preferably 10 to 60 Vol%, more preferably 20 to 50 Vol%, and even more preferably 25 to 45 Vol%.

[0034] [Analysis of Reinforcing Fiber Volume Fraction (Vf)] Although there are no limitations on the analysis of the reinforcing fiber volume fraction, it is recommended to measure it as follows. A sample is cut out from an automotive horizontal member, and the resin is burned off in a furnace at 500°C for 1 hour. The mass of the sample before and after treatment is weighed to calculate the mass of the reinforcing fiber and the resin. Next, the volume of the reinforcing fiber is calculated by dividing the mass of the reinforcing fiber by the density of the reinforcing fiber, and the volume of the resin is calculated by dividing the mass of the resin by the density of the resin. Next, the ratio Vf of the volume of the reinforcing fiber to the total volume of the reinforcing fiber and the resin is calculated.

[0035] [Resin] The resin contained in the horizontal member for automobiles may be either thermosetting or thermoplastic. 1. Thermoplastic Resin 1.1 Overview When the resin used is a thermoplastic resin, the type is not particularly limited, and a resin having the desired softening point or melting point can be appropriately selected and used. The thermoplastic resin typically has a softening point in the range of 80°C to 350°C, preferably 100°C to 350°C, and more preferably 180°C to 350°C, but is not limited thereto.

[0036] Examples of thermoplastic resins include polyolefin resins, polystyrene resins, polyamide resins, polyester resins, polyacetal resins (polyoxymethylene resins), polycarbonate resins, (meth)acrylic resins, polyarylate resins, polyphenylene ether resins, polyimide resins, polyethernitrile resins, phenoxy resins, polyphenylene sulfide resins, polysulfone resins, polyketone resins, polyether ketone resins, thermoplastic urethane resins, fluorine-based resins, and thermoplastic polybenzimidazole resins.

[0037] The thermoplastic resin used in the door inner panel of the present invention may be one type or two or more types. Examples of the use of two or more types of thermoplastic resins in combination include, but are not limited to, the use of thermoplastic resins having different softening points or melting points, or the use of thermoplastic resins having different average molecular weights. When a thermoplastic resin is used, it is more preferable to use a polyolefin resin, and even more preferable to use a polypropylene resin.

[0038] 2. Thermosetting Resin The resin of the present invention may be a thermosetting resin. In this case, a sheet molding compound (sometimes referred to as SMC) using reinforcing fibers may be used as the molding material. Due to its high moldability, sheet molding compounds can be easily molded into even complex shapes. Sheet molding compounds have higher fluidity and shaping properties than continuous fibers, making it easy to create ribs and bosses.

[0039] [Flame Retardant] 1. The horizontal member for an automobile of the present invention contains a flame retardant. The flame retardant is not particularly limited, and examples thereof include phosphorus-based flame retardants, bromine-based flame retardants, and antimony-based flame retardants. Among these, phosphorus-based flame retardants are preferred from the viewpoint of improving flame resistance. Furthermore, in terms of the classification focusing on the mechanism of action of flame retardants, it is preferred that the flame retardant be an intumescent flame retardant from the viewpoint of improving flame resistance.

[0040] 2. Phosphorus-based flame retardants Phosphorus-based flame retardants are phosphorus compounds, i.e., compounds containing phosphorus atoms in the molecule. Phosphorus-based flame retardants exert their flame retardant effect by forming char when the resin composition is burned.

[0041] The phosphorus-based flame retardant may be a known one, such as a (poly)phosphate or a (poly)phosphate ester. Here, "(poly)phosphate" refers to a phosphate or a polyphosphate, and "(poly)phosphate ester" refers to a phosphoric acid ester or a polyphosphate. It is preferable that the phosphorus-based flame retardant is solid at 80°C.

[0042] As the phosphorus-based flame retardant, (poly)phosphates are preferred in terms of flame retardancy, and examples of (poly)phosphates include ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, piperazine orthophosphate, melamine pyrophosphate, piperazine pyrophosphate, melamine orthophosphate, calcium phosphate, and magnesium phosphate.

[0043] In addition, in the above examples, compounds in which melamine or piperazine is replaced with other nitrogen compounds can also be used. 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-thiazolinone azine, 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 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.

[0044] Commercially available phosphorus-based flame retardants include, for example, Adekastab (registered trademark) FP-2100J, FP-2200, and FP-2500S (manufactured by ADEKA Corporation), Adekastab FP-2100 JC, and Exolit (registered trademark) AP462 and Exolit OP1230 manufactured by Clariant.

[0045] 3. Intumescent flame retardants 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.

[0046] The intumescent flame retardant 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, thereby exhibiting excellent flame retardancy. Examples of the intumescent flame retardant include the above-mentioned salts of (poly)phosphoric acid and nitrogen compounds, specifically ammonium salts and amine salts of (poly)phosphoric acid.

[0047] 4. Brominated Flame Retardants Examples of brominated 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 brominated polystyrene include 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.

[0048] 5. Antimony-Based Flame Retardants Examples of antimony-based flame retardants include antimony trioxide, antimony tetroxide, antimony pentoxide, sodium pyroantimonate, antimony trichloride, antimony trisulfide, antimony oxychloride, antimony dichloride perchloropentane, and potassium antimonate, with antimony trioxide and antimony pentoxide being particularly preferred.

[0049] [Flame Retardant Content] The flame retardant content in the horizontal automotive structural member of the present invention is 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of resin. It is preferably in the range of 1 part by mass or more and 30 parts by mass or less, and more preferably in the range of 5 parts by mass or more and 25 parts by mass or less. When the content is 1 part by mass or more, the horizontal automotive structural member can be imparted with good flame retardancy and good flame insulation properties can be obtained. On the other hand, when the flame retardant content is 50 parts by mass or less, molding processability is improved.

[0050] [Dispersant] 1. The dispersant is not particularly limited as long as it can disperse the flame retardant in the resin, but a polymer dispersant can be suitably used in terms of compatibility with the resin. Preferably, one that can disperse the flame retardant in the polypropylene resin can be used. As the polymer dispersant, a polymer dispersant having a functional group is preferred, and from the viewpoint of dispersion stability, a polymer dispersant having a functional group such as a carboxyl group, a phosphate group, a sulfonic acid group, a primary, secondary, or tertiary amino group, a quaternary ammonium base, or a group derived from a nitrogen-containing heterocycle such as pyridine, pyrimidine, or pyrazine is preferred.

[0051] In the present invention, a polymer dispersant having a carboxyl group is preferred, and in particular, when a phosphorus-based flame retardant, which is a suitable flame retardant, is used, a copolymer of an α-olefin and an unsaturated carboxylic acid is preferred. Use of such a dispersant can improve the dispersibility of the phosphorus-based flame retardant and reduce the content of the flame retardant.

[0052] 2. Necessity of Dispersant The horizontal member for an automobile according to the present invention does not necessarily need to contain a dispersant, provided that flame retardancy can be ensured.

[0053] [Other Agents] The horizontal member for an automobile of the present invention may contain additives such as various fibrous or non-fibrous fillers made of organic or inorganic fibers, UV-resistant agents, stabilizers, release agents, pigments, softeners, plasticizers, surfactants, etc., within the scope of the present invention.

[0054] [Method for manufacturing a horizontal member for an automobile: when the resin is a thermoplastic resin] Hereinafter, a manufacturing method when the resin is a thermoplastic resin will be described. When the resin is a thermoplastic resin, the molding material in the present invention is preferably in the form of a flat plate.

[0055] 1. Cold Press (Molding) Method The molding method used to manufacture the automotive horizontal member (molded body) of the present invention is press molding (also called compression molding), and it is particularly preferable to use press molding using cold pressing. In cold press molding, for example, a molding material heated to a first predetermined temperature is placed in a mold set to a second predetermined temperature, and then pressurized and cooled.

[0056] Specifically, when the thermoplastic resin constituting the molding material is crystalline, the first predetermined temperature is equal to or higher than the melting point of the thermoplastic resin, and the second predetermined temperature is lower than the melting point. When the thermoplastic resin is amorphous, the first predetermined temperature is equal to or higher than the glass transition temperature of the thermoplastic resin, and the second predetermined temperature is lower than the glass transition temperature.

[0057] That is, the cold press molding method includes at least the following steps A-1) to A-2). Step A-1) A step of heating the molding material to a temperature above the melting point of the thermoplastic resin and below the decomposition temperature of the thermoplastic resin if the thermoplastic resin is crystalline, or above the glass transition temperature and below the decomposition temperature of the thermoplastic resin if the thermoplastic resin is amorphous. Step A-2) A step of placing the molding material heated in step A-1) in a mold whose temperature is adjusted to below the melting point if the thermoplastic resin is crystalline, or below the glass transition temperature if the thermoplastic resin is amorphous, and applying pressure. By performing these steps, the molding of the molding material can be completed.

[0058] The above steps must be performed in the order described above, but other steps may be included between the steps. For example, the other steps include a shaping step, prior to step A-2), in which a shaping mold different from the mold used in step A-2) is used to pre-shape the mixture into the shape of the cavity of the mold.

[0059] 2. Hot Press (Molding) Method In the hot press (molding) method, for example, a molding material is placed in a mold, pressure is applied while the temperature of the mold is raised to a first predetermined temperature, and the mold is cooled to a second predetermined temperature. Specifically, if the thermoplastic resin constituting the molding material is crystalline, the first predetermined temperature is equal to or higher than the melting point of the thermoplastic resin, and the second predetermined temperature is lower than the melting point. If the thermoplastic resin constituting the molding material is amorphous, the first predetermined temperature is equal to or higher than the glass transition temperature of the thermoplastic resin, and the second predetermined temperature is lower than the glass transition temperature.

[0060] The hot press molding method preferably includes at least the following steps B-1) to B-4). B-1) A step of placing the molding material in a mold (lower mold). B-2) A step of applying pressure while heating the mold (first pressing step) from a temperature above the melting point of the thermoplastic resin to a temperature below the thermal decomposition temperature of the thermoplastic resin if the thermoplastic resin is crystalline, or from a temperature above the glass transition temperature to a temperature below the thermal decomposition temperature of the thermoplastic resin if the thermoplastic resin is amorphous. B-3) A step of applying pressure in one or more stages, with the final stage being 1.2 to 100 times the pressure of the first pressing step (second pressing step). B-4) A step of adjusting the mold temperature to below the melting point if the thermoplastic resin is crystalline, or below the glass transition temperature if the thermoplastic resin is amorphous. By performing these steps, the molding of the molding material can be completed.

[0061] 3. Commonalities between Cold Press Molding and Hot Press Molding Steps A-2) and B-3) are steps in which pressure is applied to the molding material to obtain a molded body of the desired shape. The molding pressure at this time is not particularly limited, but it is preferably as low as possible within a range that allows the desired molded body shape to be obtained. Specifically, it is preferably less than 30 MPa relative to the mold cavity projected area, more preferably 20 MPa or less, and even more preferably 10 MPa or less. A molding pressure of less than 30 MPa is preferable because it does not require capital investment or maintenance costs for a press. Naturally, various processes may be inserted between the above-mentioned steps during compression molding; for example, vacuum compression molding, in which compression molding is performed under vacuum, may be used.

[0062] [Springback] The following describes springback when the resin contained in an automotive horizontal member is a thermoplastic resin. 1. Springback of Molding Material: To perform cold press molding using a molding material, the molding material must be preheated to a predetermined temperature to soften and melt. When the thermoplastic resin becomes plastic during preheating of molding material containing reinforcing fibers with a weight-average fiber length of 5 mm to 100 mm (especially when the reinforcing fibers are in a mat-like state), the preheated molding material expands due to springback of the reinforcing fibers, causing a change in bulk density. The change in bulk density during preheating causes the molding material to become porous, increasing its surface area and allowing air to enter the molding material, accelerating thermal decomposition of the thermoplastic resin. Here, the amount of springback is calculated by dividing the thickness of the molding material after preheating by the thickness of the molding material before preheating.

[0063] The amount of springback tends to increase when the reinforcing fiber bundles contained in the molding material are highly spread (single fiber rich) or when the fiber length is long.

[0064] In the present invention, the springback value of the molding material is preferably 1.2 or more and 8.0 or less. If the springback value of the molding material is 8.0 or less, when a battery cover using the molding material burns, the battery cover can be prevented from expanding too much and coming into contact with the battery. Conversely, if the springback value is 1.2 or more, the horizontal component for an automobile using the molding material is likely to expand when heated, thereby achieving heat insulating effects.

[0065] The springback amount of the molding material is preferably 3.0 or more and 8.0 or less, more preferably 4.0 or more and 7.0 or less, and even more preferably 4.0 or more and 6.0 or less.

[0066] 2. Springback of Automotive Horizontal Member The automotive horizontal member (molded body) of the present invention preferably has a springback value of 1.2 or more and 8.0 or less, similar to the molding material. A preferred automotive horizontal member has a springback value of 3.0 or more and 8.0 or less, a more preferred value of 4.0 or more and 7.0 or less, and an even more preferred value of 4.0 or more and 6.0 or less. If the automotive horizontal member has a springback value of 1.2 or more, the automotive horizontal member is likely to expand when heated, making it easier to achieve heat insulating effects.

[0067] [Method for manufacturing horizontal member for automobiles: when the resin is a thermosetting resin] When the resin is a thermosetting resin, the horizontal member for automobiles of the present invention is preferably formed from a sheet molding compound (sometimes referred to as SMC) using reinforcing fibers. Due to its high moldability, sheet molding compound can easily be molded into even complex shapes such as battery trays and battery top covers.

[0068] Specifically, the sheet molding compound can be molded into a fiber-reinforced plastic molded product, allowing for the production of battery trays with concave and convex shapes. The sheet molding compound has higher fluidity and formability than continuous fibers, making it easy to create ribs and bosses.

[0069] As the sheet molding compound (SMC) used for the molded article of fiber reinforced plastic, a sheet molding compound manufactured by Teijin Automotive Technologies Co., Ltd. (sometimes abbreviated as TAT) can be used. In general, when a molded article of fiber reinforced plastic is produced by molding a sheet molding compound, compression molding is used.

[0070] [Horizontal Member for Automobile] 1. Overview The horizontal member for automobile of the present invention is a horizontal member that is installed horizontally when completed as an automobile part. The horizontal member does not necessarily need to be horizontal as long as a part or most of it is horizontal. Examples include battery covers, battery bottom protective covers, roofs, hoods, and hood portions of rear doors. In order to improve the flame resistance of horizontal members for automobiles, it is necessary to prevent them from sagging during combustion.

[0071] 2. Battery Tray, Battery Cover, Battery Bottom Protective Cover The horizontal member for an automobile according to the present invention is preferably a component of a battery box. The component of the battery box is preferably one of a battery tray, a battery cover, and a battery bottom protective cover.

[0072] 2.1 Battery Tray and Battery Cover Figure 2 is a cross-sectional view showing an example of a battery box. As shown in Figure 2, a battery 303 is housed in a battery box that includes a battery tray 305 and a battery cover 302. Note that the components of the battery box are preferably for use in a vehicle.

[0073] 2.2 Battery Bottom Protective Cover 2.2.1 The horizontal member for an automobile according to the present invention may be a battery bottom protective cover. An example of a battery bottom protective cover is shown in Figure 2. More specifically, the battery bottom protective cover 401 is fastened to the battery tray 305 at least at one location by a fastening rod 402, and it is preferable that the battery tray 305 has an integrally formed insertion hole 403 for fastening.

[0074] 2.2.2 Insertion Hole The battery tray 305 is provided with an insertion base 404 that protrudes toward the battery bottom protection cover 401 , and the insertion hole 403 is preferably located inside the insertion base 404 .

[0075] 2.2.3 Impact-absorbing material It is preferable to place an impact-absorbing material 405 between the battery tray 305 and the battery bottom protective cover 401. It is more preferable that the impact-absorbing material 405 has a honeycomb structure. Providing such an impact-absorbing material 405 improves resistance to impacts from the underside of the vehicle.

[0076] 2.2.4 Airflow Rectifier The battery bottom protective cover is preferably provided with an airflow rectifier molded as an integral part, and the airflow rectifier should be provided on the underside of the battery bottom protective cover. Providing an airflow rectifier reduces air resistance and improves the running stability of the vehicle.

[0077] 2.2.5 Electromagnetic Wave Shielding Layer The electromagnetic wave shielding layer is preferably attached to the top surface of the battery cover. Alternatively, the electromagnetic wave shielding layer may be provided between the battery bottom protective cover and the battery tray. In this case, the electromagnetic wave shielding layer is preferably provided on the top surface of the battery bottom protective cover, and the impact absorbing material is more preferably disposed above the electromagnetic wave shielding layer.

[0078] 3. Thickness of Horizontal Member for Automobile The thickness of the horizontal member for automobile is preferably 1 mm or more, more preferably 3 mm or more, and even more preferably 5 mm or more.

[0079] [Tensile test before and after fire resistance performance] The horizontal automotive member of the present invention satisfies the following (a). (a) The tensile strength retention rate, as shown in formula (1), is greater than 0.03%. A preferred tensile strength retention rate is 0.05% or greater, more preferably 0.06% or greater, and even more preferably 0.1% or greater. The tensile strength retention rate is preferably in the range of 0.04% to 50%, more preferably 0.05% to 40%, even more preferably 0.06% to 30%, and even more preferably 1% to 25%. If the tensile strength retention rate is greater than 0.03%, the shape of the horizontal automotive member can be maintained after combustion without resin dripping. Tensile strength retention rate (%) = (tensile strength B after combustion / tensile strength A before combustion) × 100... formula (1)

[0080] 1. When the horizontal member for an automobile is a battery cover: When the horizontal member for an automobile of the present invention is a battery cover 302, fire resistance against flames from the battery 303 inside the battery box is required. Furthermore, if leaked gasoline burns during an accident, the battery cover 302 may be exposed to flames at 700 to 800°C. Therefore, fire resistance under more stringent conditions than conventional battery covers is required. Therefore, fire resistance toward the inside of the battery box becomes important. In this case, if the tensile strength retention rate exceeds 0.03%, the battery cover will drip resin after combustion and not come into contact with the battery itself. For battery covers, a tensile strength retention rate of 0.05% or higher is preferable, and 0.07% or higher is even more preferable. Furthermore, when the battery cover is pressed from the non-flame-contact side (upper side) with a push-pull gauge after combustion, the stress is preferably 100 N or higher, more preferably 150 N or higher, and even more preferably 200 N or higher.

[0081] 2. When the horizontal member for an automobile is a battery tray When the horizontal member for an automobile of the present invention is a battery tray, the battery box needs to be fire-resistant against flames from outside the vehicle, so fire resistance performance toward the outside of the battery box becomes important. In the case of a battery tray, a tensile strength retention rate of 0.04% or more is preferable, a tensile strength retention rate of 0.06% or more is more preferable, and a tensile strength retention rate of 0.1% or more is even more preferable.

[0082] [Collection of test specimens: residual tensile strength] The method for measuring the tensile strength retention rate will be described later, but 10 test specimens measuring 25 mm in width and 150 mm in length were cut out from an automotive horizontal member. The tensile strength of five of the cut test specimens was measured, and the measurement result was designated as tensile strength A before the combustion test. The remaining five test specimens were subjected to a combustion test, and the tensile strength of the five test specimens after the combustion test was measured, and the measurement result was designated as tensile strength B after the combustion test.

[0083] [Work load] The horizontal member for an automobile of the present invention satisfies the following (b): (b) the work load per unit area in a tensile test using a test piece with a width of 25 mm after a combustion test is 0.5 × 10 －３ [(N・mm) / (g / m ２ ) ] or more 100 x 10 －３ [(N・mm) / (g / m ２ ) or less. Here, the workload is the value obtained by integrating the tensile force in the tensile test with the amount of strain. The workload per basis weight in the tensile test is the value obtained by integrating the load per basis weight in the tensile test with the displacement value of strain. For example, the workload in the tensile test can be calculated by integrating the load per basis weight with the amount of strain [mm] in the load-strain [mm] curve obtained by converting the strain displacement rate [unit: %] on the horizontal axis of the load-strain [%] curve in the tensile test shown in Figure 3 into the amount of displacement (unit: mm).

[0084] If the work load is equal to or greater than the lower limit, the horizontal component for automobiles will not sag and the resin will not drape down during combustion. Conversely, if the work load is equal to or less than the upper limit, a large pressure is not required during press molding, making it easy to mold the horizontal component for automobiles. The work load per unit area in a tensile test using a test piece with a preferred width of 25 mm after a combustion test is 0.5 × 10－３ [(N・mm) / (g / m ２ ) ] or more 100 x 10 －３ [(N・mm) / (g / m ２ ) more preferably less than 0.5 × 10 －３ [(N・mm) / (g / m ２ ) ] or more 50 x 10 －３ [(N・mm) / (g / m ２ ) )], more preferably less than 1.0 × 10 －３ [(N・mm) / (g / m ２ ) ] or more 30 x 10 －３ [(N・mm) / (g / m ２ ) )], and even more preferably less than 1.5 × 10 －３ [(N・mm) / (g / m ２ ) ] or more 20 x 10 －３ [(N・mm) / (g / m ２ ) )], and most preferably less than 1.5 × 10 －３ [(N・mm) / (g / m ２ ) ] or more 10 x 10 －３ [(N・mm) / (g / m ２ ) is less than

[0085] [Average rate of change in load] 1. It is preferable that the horizontal member for an automobile of the present invention satisfies the following (c): (c) In a tensile test using a test piece with a width of 25 mm after a combustion test, the load [N / (g / m ２ ) ] the average rate of change is 0.1 × 10 －３ [N / (g / m ２ ) ] or more 100 x 10 －３ [N / (g / m ２ ) at strains of 0.1% to 0.2%. ２ ) ] a more preferred average rate of change is 0.5 × 10 －３ [N / (g / m ２ ) ] or more 9.0 x 10 －３ [N / (g / m ２ ) )] or less, and a more preferable average rate of change is 1.5 × 10 －３ [N / (g / m ２ ) ] or more 8.0 x 10 －３The more preferable average rate of change is 1.5×10 －３ Above 7.0 x 10 －３ The following is the result.

[0086] Load [N / (g / m ２ ) ] the average rate of change is 0.1 × 10 －３ [N / (g / m ２ ) )] or more means that a certain amount of stress is required to deform the fiber. In other words, the load [N / (g / m ２ ) ] the average rate of change is 0.1 × 10 －３ [N / (g / m ２ ) at a strain of 0.1% to 0.2% is preferable because the fibers do not sag when the horizontal member for an automobile burns. ２ ) ] average change rate is 100 x 10 －３ [N / (g / m ２ ) )] at a strain of 0.1% to 0.2%, it means that the material can be easily molded without requiring a large load at the initial stage of load application. ２ ) in Figure 3. ２ ) ) - strain [%] curve, the slope of the arrow indicated by the reference numeral 502.

[0087] 2. It is preferable that the horizontal member for an automobile of the present invention satisfies the following (d): (d) In a tensile test using a test piece having a width of 25 mm after a combustion test, the load [N / (g / m ２ ) ] the average rate of change is -1.0 × 10 －３ [N / (g / m ２ ) ] or more - 0.01 × 10 －３ [N / (g / m ２ ) )] below. Here, the load [N / (g / m ２ ) in Figure 3. ２ ) - strain [%] curve. ２) is a negative value, and if it is within this range, it means that no large load other than the initial load during molding is required and the material can be easily molded.

[0088] [Strain range where load per unit area weight is maximum] The horizontal member for an automobile of the present invention preferably satisfies the following (e). (e) In a tensile test using a 25 mm wide test piece after a combustion test, the horizontal member has a maximum load value in the range of strain greater than 0% and less than 2%. It is preferable that the maximum load value is in the range of strain greater than 0% and less than 1%, and more preferably in the range of strain greater than 0% and less than 0.5%. Having a maximum load value in the range of strain greater than 0% and less than 2% means that the load [N / (g / m ２ ) )]-strain [%] curve has a peak of the maximum load in the range of strain more than 0% and less than 2%. ２ The [% strain]-strain curve preferably has a maximum load peak in the strain range of more than 0% and less than 1%, and even more preferably in the strain range of more than 0% and less than 0.5%. When press-molding a molding material using the upper and lower molding dies, stress can be applied to the molding material immediately after the upper and lower molding dies are closed to sandwich the molding material. By designing the maximum load value to be in the above range (the initial stage when strain increases), molding materials (horizontal members for automobiles) with the same workload can be molded more easily.

[0089] [Maximum Load per Unit Weight] The horizontal member for an automobile of the present invention preferably satisfies the following (f): (f) In a tensile test using a test piece having a width of 25 mm after a combustion test, the maximum load per unit weight is 1.1 × 10 －３ [N / (g / m ２ ) or more. The maximum load per unit area is 1.15 x 10 －３ [N / (g / m ２ ) is more preferably 1.5 × 10 －３ [N / (g / m ２ ) is more preferably 2.0 × 10 －３ [N / (g / m ２) is more preferably 3.0 × 10 －３ [N / (g / m ２ It is most preferable that the maximum load per unit area is 1.1 × 10 －３ [N / (g / m ２ ) or more, the fibers do not sag when the horizontal component for an automobile burns, which is preferable. －３ [N / (g / m ２ ) or more, if a large load is applied in a specific molding stage, molding can be easily performed with a small load in other stages, and it is not necessary to continue applying a large load throughout the entire time until molding is completed. －３ [N / (g / m ２ ) or less. With the same workload, the maximum load per unit area is preferably 10 x 10 －３ [N / (g / m ２ ) or less, a large load is not required when forming a horizontal member for an automobile, and the horizontal member can be easily formed.

[0090] [Volume of air blown onto reinforcing fibers after cutting] There are no particular limitations on the method for manufacturing a horizontal component for an automobile that will result in the above-mentioned [Work load], [Load average rate of change], [Strain range at which the load per unit area is at its maximum], and [Maximum value of load per unit area] satisfying the above (b) to (f). However, after cutting the reinforcing fibers, compressed air can be sent using a compressor directly below the cutting device, and the volume of this compressed air can be adjusted to adjust the values ​​of the [Work load], [Average rate of change in the load-strain curve], and [Maximum value of load per unit area] within the desired range.

[0091] [Preparation of molding material] [Materials] 1. Reinforcing fiber The following two types of reinforcing fiber were prepared: (1) Glass fiber multi-end roving (Owens Corning: OC Paneluxe (registered trademark) 2400Tex) (2) Glass fiber single-end roving (Owens Corning: SE2348 roving 2000Tex) 2. Resin Polypropylene resin: Novatec (registered trademark) PP BC03C manufactured by Japan Polypropylene Corporation 3. Flame retardant Adeka Stab (registered trademark) FP2100-JC manufactured by ADEKA Corporation

[0092] Example 1: A thermoplastic resin was prepared by adding 11 parts by mass of a flame retardant (ADK STAB FP2100-JC) to polypropylene resin (Novatec PPBC03C, Japan Polypropylene Corporation). A breathable support that moved continuously in one direction and had a suction mechanism at the bottom was installed below the polypropylene resin feeder. While the breathable support was moving at 2 m / min, polypropylene resin was sprayed onto the breathable support from the feeder, and the polypropylene resin was allowed to settle on the breathable support, preparing a polypropylene resin assembly. A rotary cutter was installed above the breathable support, and the single-end roving (2) was cut to a fixed length of 20 mm using the rotary cutter. At this time, compressed air was blown directly below the rotary cutter, and the negative pressure generated by the airflow separated the glass fibers from the roll. The compressed air flow rate was 170 L / min. The cut glass fibers were sprayed onto a polypropylene resin assembly previously prepared on the breathable support and allowed to settle, yielding a glass fiber assembly. The amount of glass fiber supplied was set so that the volume ratio of the glass fiber to the molding material was 40% and the average thickness of the molding material was 2.0 mm.

[0093] When cutting to a fixed length of 20 mm using a rotary cutter, a composite composition of polypropylene resin aggregate and glass fiber aggregate was produced in a width of 600 mm and a length of 3 m. The production speed of the composite composition was 2 m / min. The composite composition consisting of the produced glass fiber aggregate and polypropylene resin aggregate was heated in a continuous impregnation device, and the polypropylene resin was impregnated into the glass fibers, followed by cooling to obtain a molding material. The produced molding material was cold pressed to produce a battery cover and a battery tray, which are horizontal components for automobiles.

[0094] Example 2 A nozzle was prepared in the same manner as in Example 1, except that the volume of compressed air was 50 L / min.

[0095] Example 3 A nozzle was prepared in the same manner as in Example 1, except that the volume of compressed air was changed to 230 L / min.

[0096] Example 4 A nozzle was prepared in the same manner as in Example 1, except that the volume of compressed air was 300 L / min.

[0097] Example 5: A thermoplastic resin prepared by adding 11 parts by mass of a flame retardant (ADK STAB FP2100-JC) to polypropylene resin (Novatec PPBC03C, Japan Polypropylene Corporation) was used. A breathable support that moved continuously in one direction and had a suction mechanism at the bottom was installed below the polypropylene resin feeder. While the breathable support was moving at 2 m / min, polypropylene resin was sprayed onto the breathable support from the feeder, and the polypropylene resin was allowed to settle on the breathable support, preparing a polypropylene resin assembly. The multi-end roving (1) was slit and separated to a target fiber width of 1 mm using a slitting device (cut by pressing against a rubber roll). The slit multi-end roving (1) and single-end roving (2) were fed to a rotary cutter installed above the breathable support so that the volume ratio of the multi-end roving (1) and single-end roving (2) was 1:1, and the rotary cutter was used to cut them to a fixed length of 20 mm. At this time, compressed air was blown directly below the rotary cutter, and the negative pressure generated by the air flow separated the glass fibers from the roll. The compressed air flow rate was 170 L / min. The cut glass fibers were scattered on a polypropylene resin assembly previously prepared on an air-permeable support and allowed to settle, obtaining a glass fiber assembly. The supply amount of glass fibers was set so that the volume ratio of the glass fibers was 38% of the molding material and the average thickness of the molding material was 2.0 mm.

[0098] When cutting to a fixed length of 20 mm using a rotary cutter, a composite composition of polypropylene resin aggregate and glass fiber aggregate was produced in a width of 600 mm and a length of 3 m. The production speed of the composite composition was 2 m / min. The composite composition consisting of the produced glass fiber aggregate and polypropylene resin aggregate was heated in a continuous impregnation device, and the polypropylene resin was impregnated into the glass fibers, followed by cooling to obtain a molding material. The produced molding material was cold pressed to produce a battery cover and a battery tray, which are horizontal components for automobiles.

[0099] Comparative Example 1 A comparative example was prepared in the same manner as in Example 1, except that the volume of compressed air was 0 L / min.

[0100] [Evaluation Method] 1. Tensile Strength Retention Rate 1.1 Ten test pieces measuring 25 mm wide and 150 mm long were cut out from the horizontal automotive component. 1.2 Tensile tests were performed on five of the test pieces in accordance with ASTM D3039 (2019) at a loading speed of 1 mm / min to measure the tensile strength. The average value of the five pieces was taken as the tensile strength A before the combustion test.

[0101] 1.3 Combustion Test A combustion test was conducted on the remaining five test specimens. As shown in Figure 1, both ends of the test specimen 101 were clamped between aluminum plates 105 at a 40 mm longitudinal interval, and the resin in a 40 mm longitudinal area (combustion area 102) in the center of the test specimen 101 was directly combusted with a 1000°C gas burner flame 103. The burner nozzle 104 was positioned 60 mm away from the test specimen 101. Because the temperature and time required to completely combust the resin in the combustion area 102 may vary depending on the test specimen, the backside temperature was measured using a non-contact thermometer (A&D Co., Ltd. AD-5611A) 30 cm away from the backside of the test specimen 101 on the side opposite the gas burner flame 103 at the center (upper side of Figure 1). After confirming that the backside temperature reached 350°C or higher, the test specimen 101 was combusted for five minutes. If the flame on the test piece 101 does not go out even after the flame 103 of the gas burner is extinguished after five minutes of combustion, wait until it is completely extinguished and do not actively extinguish the flame. Depending on the type of resin, the resin in the combustion region 102 may not be completely burned off even under the above conditions. In this case, additional heating may be applied.

[0102] 1.4 After the combustion test, five test pieces are subjected to a tensile test in accordance with ASTM D3039 (2019) at a loading speed of 2 mm / min to measure the tensile strength. The average value of the five pieces is the tensile strength B after the combustion test. 1.5 The tensile strength retention rate is calculated using equation (1) from the tensile strength A before the combustion test and the tensile strength B after the combustion test.

[0103] 2. Work load and average rate of change after initial load application 2.1 Six test pieces, 25 mm wide and 150 mm long, are cut from an automotive horizontal member. 2.2 The test pieces are burned under the same conditions as in "1.3 Combustion test" in "1. Tensile strength retention" above. 2.3 According to Method A (strip method) of JIS L 1096:2010, 8.14.1a), each of the six test pieces after burning is elongated at a tensile speed of 1 mm / min using a constant-rate extension tensile tester with a grip spacing of 100 mm. The load in the tensile test is integrated by the strain [mm] to calculate the work load for each piece, and the average value for the six test pieces is calculated. The average rate of change from 0.1% to 0.2% strain was calculated by subtracting the load at 0.1% strain from the load at 0.2% strain and dividing the difference by 0.001, and the average value for the six test pieces was obtained. Furthermore, the average rate of change from 0.5% to 3.0% strain was calculated by subtracting the load at 0.5% strain from the load at 3.0% strain and dividing the difference by 0.025, and the average value for the six test pieces was obtained.

[0104] 3. Amount of springback The molding material is cut into 100mm x 100mm pieces, two pieces are stacked together, a thermocouple is inserted into the center of the mating surface, and the piece is placed in a preheating furnace with upper and lower heaters heated to 280°C, and heated until the thermocouple temperature reaches 275°C. When the thermocouple temperature reaches 210°C, the piece is removed from the furnace, cooled and solidified, and the wall thickness after preheating is measured. The ratio of the wall thickness before preheating to the wall thickness after preheating is calculated as the amount of springback using the following formula: Amount of springback = wall thickness after preheating (mm) / wall thickness before preheating (mm)

[0105] 4. Moldability The flat molding material is cut to a length of 205 mm x width of 95 mm, two sheets are stacked to a thickness of 2 mm, and dried in a hot air dryer at 120 ° C for 4 hours, and then heated to 240 ° C using an infrared heater. Next, a flat mold is prepared and set to 60 ° C. Two sheets of the cut and heated molding material are placed on top of it so that they overlap the opening, and the mold is clamped using a mechanical servo press (ZENFormer (registered trademark) MPS4200 manufactured by Electrical Discharge Precision Machining Laboratory Co., Ltd.). The thickness of the obtained molded body is observed, and moldability is evaluated based on the degree of reduction compared to the thickness of the molding material. Perfect: Thickness reduction rate of 30% or more Excellent: Thickness reduction rate of 20% or more and less than 30% Better: Thickness reduction rate of 10% or more and less than 20% Good: Thickness reduction rate of 5% or more and less than 10% Bad: Thickness reduction rate of less than 5%

[0106] 5. Thermal insulation Ten test pieces, each 300 mm wide and 300 mm long, were cut from a horizontal automotive component. The test pieces were placed on a frame-mounted test stand capable of accommodating 300 mm square pieces, and the center of the test piece was directly burned with a 1000°C burner flame. The burner nozzle was placed 60 mm away from the test piece and the test piece was allowed to burn for 3 minutes. The back surface temperature of the side opposite the burner flame at the center of the test piece was measured using a non-contact thermometer (A&D Co., Ltd. AD-5611A) at a location 30 cm away from the test piece. Excellent: The back surface temperature during measurement was 200°C or less for 3 minutes from the start of combustion. Very Good: The back surface temperature exceeded 200°C for more than 70 seconds but less than 3 minutes from the start of combustion. Good: The back surface temperature exceeded 200°C for more than 10 seconds but less than 70 seconds from the start of combustion. Unacceptable: The back surface temperature exceeded 200° C. within 10 seconds from the start of combustion. The evaluation results are shown in Table 2.

[0107]

Claims

1. An automotive horizontal member comprising a reinforcing fiber having a weight average fiber length of 5 mm or more and 100 mm or less, a resin, and a flame retardant, wherein the flame retardant is 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the resin, and the automotive horizontal member satisfies the following (a) to (b). (a) The tensile strength retention rate represented by formula (1) is more than 0.03%. Tensile strength retention rate (%) = (tensile strength B after combustion ÷ tensile strength A before combustion) × 100... formula (1) (b) The work per unit mass in the tensile test on the test piece after the combustion test with a width of 25 mm is 0.5×10 －３ [(N·mm) / (g / m ２ )] or more and 100×10 －３ [(N·mm) / (g / m ２ )] or less, and the maximum load per unit mass is 1.1×10 －３ [N / (g / m ２ )] or more.

2. The automotive horizontal member according to claim 1, having a maximum load per unit area in the range where the strain is more than 0% and less than 2% in a tensile test of a test piece after a combustion test with a width of 25 mm.

3. The automotive horizontal member according to claim 1 or 2, satisfying the following (c). In the tensile test on the test piece after the combustion test with a width of 25 mm, the average change rate of the load [N / (g / m ２ )] from a strain of 0.1% to 0.2% is in the range of 0.1×10 －３ [N / (g / m ２ )] or more and less than 100×10 －３ [N / (g / m ２ )].

4. The automotive horizontal member according to claim 3, satisfying the following (d). In the tensile test on the test piece after the combustion test with a width of 25 mm, the average change rate of the load [N / (g / m ２ )] from a strain of 0.5% to 3% is in the range of -1.0×10 －３ [N / (g / m ２ )] or more and -0.01×10 －３ [N / (g / m ２ )] or less.

5. The automotive horizontal member according to claim 1 or 2, wherein the resin is a thermoplastic resin.

6. The automotive horizontal member according to claim 1 or 2, wherein the resin is a polypropylene resin.

7. The automotive horizontal member according to claim 1 or 2, wherein the reinforcing fiber is a glass fiber.

8. The automotive horizontal member according to claim 1 or 2, wherein the automotive horizontal member is a battery cover or a battery bottom protection cover.

9. The automotive horizontal member according to claim 1 or 2, wherein the resin is a thermoplastic resin, and the springback rate of the automotive horizontal member is 1.2 or more and 8.0 or less.

10. A method for manufacturing an automotive horizontal member according to claim 1 or 2 by cold pressing a molding material containing a reinforcing fiber and a thermoplastic resin, wherein the springback rate of the molding material is 1.2 or more and 8.0 or less.

11. The method for manufacturing an automotive horizontal member according to claim 10, wherein the reinforcing fiber is a glass fiber, and single-end roving glass fiber GFs and multi-end roving glass fiber GFs are mixed at a volume ratio of GFs: GFs of 90:10 to 50:50 to prepare a molding material.