EP3732030A1

EP3732030A1 - Fiber-reinforced composite and method of producing the same

Info

Publication number: EP3732030A1
Application number: EP18825952.7A
Authority: EP
Inventors: Koichi Katamura; Atsushi Urano; Teruo Hama
Original assignee: Covestro Deutschland AG
Current assignee: Covestro Deutschland AG
Priority date: 2017-12-28
Filing date: 2018-12-14
Publication date: 2020-11-04
Also published as: CN111491783A; JP2019119790A; WO2019129504A1

Abstract

Provided is a fiber-reinforced composite including a fiber mat and a polyurethane foam layer, in which the polyurethane foam layer is a foam of a mixture containing a cement-based inorganic filler composed of any one of: cement; cement and sand; or cement, sand, and gravel, a polyisocyanate, a polyol, a foam stabilizer, a catalyst, and water, the fiber mat is arranged on at least one side area of the fiber-reinforced composite, and the fiber-reinforced composite has a density of 800 kg/m3 or less and a bending strength measured according to JIS A 5908 of 18 MPa or more.

Description

FIBER-REINFORCED COMPOSITE AND METHOD OF PRODUCING THE SAME

The present invention relates to a fiber-reinforced composite, and a method of producing the same. More specifically, the invention relates to a fiber-reinforced composite including a fiber mat and a polyurethane foam layer having excellent lightweight properties and flexural strength, and a method of producing the same.

Cement, mortar, and concrete (hereinafter also referred to as "cement-based inorganic material") are fundamental structural materials in the field of building and civil engineering, and are relatively inexpensive and versatile materials.

From the viewpoints of weight reduction and strength development, it has been studied to create a composite material of a cement-based inorganic material and an expandable polyurethane.

JP-50-6213 discloses that a raw material composition comprising 100 parts by weight of cement, 6 parts by weight of a polyisocyanate, 0.6 parts by weight of a polyol, 120 parts by weight of sand, 180 parts by weight of gravel, and 60 parts by weight of water was placed in a molding machine, concreted, demolded after 72 hours, and further matured for 28 days to obtain a composite concrete material having a compressive strength of from 160 to 300 kg/cm² (from 16 to 30 MPa).

JP-2002-38619 discloses that a mixture of 250 parts by weight of portland cement, 290 parts by weight of water, and 100 parts by weight of urethane raw material composition (equimolar mixture of diphenylmethane diisocyanate and polypropylene glycol) was filled in a formwork, and then the mixture was matured and completely cured to obtain a cement-based polyurethane composite material having compressive strength of 10 kgf/cm² (1 MPa) or more (JP-2002-38619, Example 3).

JP-H06-80483 and JP-H06-80966 disclose that a composition containing 300 g of urethane-based curing agent base (a polyisocyanate group-containing prepolymer), 15 g of urethane-based hardener aid (polyol and catalyst), 600 g of blast furnace cement B type (mixed cement obtained by adding portland cement and gypsum to from 30 to 60% of silica-based blast furnace slag and mixing and grinding), and from 240 to 360 g of water was mixed to form a slurry, and then, the slurry was cured to form a foamable solid. The curing initiation time is from 1 to 3 minutes, the temperature reaches 76 to 78°C due to heat generation during curing, and the compressive strength of the foaming solid after maturing for one day achieves high strength of from 69.4 to 29.0 kgf/cm² (from 6.9 to 2.9 MPa) (Examples 1 and 11 to 13 of JP-H06-80483 and JP-H06-80966).

JP-2016-56077 discloses that by selecting a specific polyether polyol, a cement polyurethane foamed composite having short time demoldability, low specific gravity, and high compression hardness in combination was obtained. The compressive strength of the cement-based polyurethane foamed composite after maturing for one week is from 1.2 to 1.7 MPa at a density of from 409 to 618 kg/m³.

On the other hand, Letizia Verdolotti et al. (Letizia Verdolotti et al. "J.Mater.Sci.(20l2)47:6948-6957") reported that a polyurethane· cement foam composition (polymer cement) was obtained by mixing cement powder and polyol, a catalyst, a silicone surfactant, a crosslinking agent, and water as a blowing agent at ambient temperature, stirring for 2 minutes, then adding isocyanate (diphenylmethane diisocyanate (MDI)), and keeping the ratio of urethane to cement constant at 2/3. In particular, this Literature discloses a comparison of the compressive strength of a polymer cement ("HIRP-C") obtained by stirring the composition for 40 seconds, filling the composition in a wood mold of 50 x 50 x 5 cm³, solidifying the composition at room temperature for 20 minutes, and hydrating the obtained molded article in water at 60°C for 72 hours with the compressive strength of a non-hydrated polymer cement ("P-C"). According to the test results, the compressive strengths of HIRP-C and P-C are as high as 4.31 MPa and 3.4

MPa, respectively.

However, according to JIS A 5908:2015, the structural particle board requires a flexural strength of 18 MPa or more (density of from 0.4 to 0.9 g/cm³)). There has been no report on achieving such strength in a composite material of a cement-based inorganic material and an expandable polyurethane so far. On the other hand, structural materials are also required to have low density (lightweight properties) in consideration of workability. Furthermore, considering the rapidity of material production, it can be said that it is also necessary for the composite material to be obtained with a short demolding time.

The invention aims to solve the various problems of the above-described related art. Namely, an object of the invention is to achieve both low density (lightweight properties) and high bending strength (hereinafter, also referred to as "bending strength") required in JIS A 5908:2015 in a composite material of a cement-based inorganic material and expandable polyurethane. Another object of the invention is to obtain such a composite material with a short de molding time.

The invention encompasses the following:

(1) A fiber-reinforced composite comprising a fiber mat and a polyurethane foam layer,

wherein the polyurethane foam layer is a foam of a mixture comprising a cement-based inorganic filler composed of any one of: cement; cement and sand; or cement, sand, and gravel, a polyisocyanate, a polyol, a foam stabilizer, a catalyst, and water,

the fiber mat is arranged on at least one side area of the fiber-reinforced composite, and

the fiber-reinforced composite has a density of 800 kg/m³ or less and a bending strength measured according to JIS A 5908 of 18 MPa or more.

(2) The fiber-reinforced composite according to (1), wherein the fiber mat is selected from at least one of a glass fiber mat, a carbon fiber mat, an aramid fiber mat, an unsaturated polyester fiber mat, a vinyl ester fiber mat, an epoxy fiber mat, an amide fiber mat, and a plant fiber mat

(3) The fiber-reinforced composite according to (1) or (2), wherein the fiber mat is a chopped strand mat or a roving cloth.

(4) The fiber-reinforced composite according to any one of (1) to (3), wherein the fiber mat is a glass chopped strand mat defined by JIS R 3411.

(5) The fiber-reinforced composite according to any one of (1) to (4), wherein the unit weight of the fiber mat is 200g/m² or more.

(6) The fiber-reinforced composite according to any one of (1) to (5), wherein the weight ratio of the cement-based inorganic filler to the total of the polyisocyanate and the polyol is from 50:50 to 90: 10.

(7) The fiber-reinforced composite according to any one of (1) to (6), wherein the weight ratio of the polyurethane foam layer to the fiber mat is from 100:0.5 to 100: 10.

(8) The fiber-reinforced composite according to any one of (1) to (7), wherein the one side area is a region within 5 mm inside from the one side surface of the fiber-reinforced composite.

(9) The fiber-reinforced composite according to any one of (1) to (8), wherein the cement-based inorganic filler is composed of: cement and sand; or cement, sand, and gravel.

(10) The fiber-reinforced composite according to any one of (1) to (9), wherein the weight ratio of the cement to the total of sand and gravel is from 1 : 1 to 1 :3.

(11) The fiber-reinforced composite according to any one of (1) to (10), wherein the weight ratio of the polyisocyanate to the polyol is 70:30 to 90: 10.

(12) The fiber-reinforced composite according to any one of (1) to (11), wherein the mixture has at least one of the following features (A) to (C):

(A) the cream time of the mixture at a liquid temperature of 25 °C is from 10 to 30 seconds;

(B) the gel time of the mixture at a liquid temperature of 25 °C is from 40 to 70 seconds; and

(C) the tack time of the mixture at a liquid temperature of 25 °C is from 70 to 110 seconds.

(13) A method for producing a fiber-reinforced composite according to any one of (1) to (12), the method comprising

a step of injecting the mixture into a mold and demolding.

(14) The production method according to (13), wherein it takes less than 5 minutes from injection of the mixture into the mold to demolding.

(15) The production method according to (13) or (14), wherein the fiber mat is arranged in advance in the mold in such a manner that a polyurethane foam layer obtained by foaming the mixture and the fiber mat adhere to each other.

According to the invention, it is possible to provide a fiber-reinforced composite having low density (lightweight properties) and high flexural strength required according to JIS A 5908. According to the invention, such a fiber-reinforced composite can be produced with a remarkably short demolding time. Such a fiber-reinforced composite can be manufactured in a short time, has a reduced weight and improved strength, but can require a low proportion of an expensive material such as polyurethane to be used, and therefore, can be advantageously utilized as a basic structural material in the field of building and civil engineering.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing one embodiment of a fiber-reinforced composite of the invention. The frame line indicates a fiber-reinforced composite, and the dotted line indicates a fiber mat. FIG. 2 is a schematic view showing another embodiment of the fiber-reinforced composite of the invention.

FIG. 3 is a schematic view of a comparative example in which a fiber mat is arranged in the middle of a polyurethane foam layer.

FIG. 4 is a cross-sectional photograph of one embodiment of the fiber-reinforced composite of the invention.

A fiber-reinforced composite of the invention comprises a fiber mat and a polyurethane foam layer, and is characterized in that the polyurethane foam layer is a foam of a mixture comprising a cement-based inorganic filler composed of any one of: cement; cement and sand; or cement, sand, and gravel, a polyisocyanate, a polyol, a foam stabilizer, a catalyst, and water, that the fiber mat is arranged on at least one side area of the polyurethane foam layer, and that the fiber-reinforced composite has a density of 800 kg/m³ or less and a bending strength measured according to JIS A 5908:2015 of 18 MPa or more.

Each component of the invention will be described below.

Fiber Mat

The term "fiber mat" as used herein is a mat-shaped molded body composed of a reinforcing fiber and a binder such as a thermoplastic resin, and various materials can be used as long an effect of the invention is not impaired.

The unit density (weight per unit area) and the thickness of the fiber mat are not particularly limited as long as they do not hinder an effect of the invention, and can be varied depending on the type and compounding ratio of a reinforcing fiber. The unit density of the fiber mat is, from the viewpoint of sufficiently securing the reinforcing strength, preferably 200 g/m² or more, more preferably from 200 to 1000 g/m², still more preferably 200 to 600 g/m², and still more preferably 200 to 500 g/m².

The thickness of the fiber mat is not particularly limited as long as the thickness does not hinder an effect of the invention, and is preferably 5 mm or less, more preferably from 0.5 to 5 mm, further preferably from 1 to 5 mm, and still more preferably from 1 to 2 mm.

As long as an effect of the invention can be exhibited, a single fiber mat may be used, or a plurality of fiber mats may be stacked and used. When stacked fiber mats are used, preferable ranges of the sum of the thicknesses of the plurality of fiber mats and the total weight thereof are the same as preferable ranges when one fiber mat is used, respectively.

The "reinforcing fiber" is a fiber material which functions as a reinforcing material in an obtained fiber composite. A structure in which the reinforcing fibers are bonded to each other with a binder such as a thermoplastic resin secures the strength of the whole fiber composite. The material of this reinforcing fiber is not particularly limited, and includes a synthetic resin, a vegetable fiber, and an inorganic fiber, and is preferably an inorganic fiber.

Various materials can be used for the "synthetic resin" without specifically specifying the type thereof. Examples thereof include an aramid fiber, an unsaturated polyester fiber, a vinyl ester fiber, an epoxy fiber, and an amide fiber.

The "vegetable fiber" is a fiber derived from a plant, and includes a fiber taken out of a plant and a fiber obtained by variously treating a fiber taken out of a plant.

Examples of the vegetable fiber include vegetable fibers obtained from various plant bodies such as kenaf, jute hemp, manila hemp, sisal, ganoderma, sanctuary, bamboo, pineapple, coconut, corn, sugarcane, bagasse, palm, papyrus, reed, esparto, suraburas, wheat, rice, bamboo, various conifers (cedar, hinoki, and the like), hardwood, and cotton.

These vegetable fibers may be used singly, or in combination of two or more kinds thereof. Among these, kenaf (or a kenaf fiber as a vegetable fiber) is preferred. This is because

Kenaf is an extremely fast-growing grass and has excellent carbon dioxide absorption, and therefore can contribute to the reduction of the amount of carbon dioxide in the atmosphere and to effective use of forest resources.

The part of a plant body used as the vegetable fiber is not particularly limited and may be any part of the plant body such as a woody part, a non-woody part, a leaf part, a stem part, and a root part. Furthermore, only a specific part may be used, or two or more different parts may be used in combination.

The kenaf described above is a plant having woody stems and classified as a family of Malvaceae. Examples of kenaf include hibiscus cannabinus and hibiscus sabdariffa in scientific names, and include red hemp, Cuba kenaf, western hemp, Hibiscus sabdariffa L., mesta, bimli, ambari hemp, and Bombay hemp in common names. The jute is a fiber obtained from jute hemp. Examples of the jute hemp include plants of hemp and Tiliaceae, including jute (Corchoruscapsularis L.), and white jute, Corchorus olitorius, and mulukhiya.

These vegetable fibers may be used singly or in combination.

Examples of the "inorganic fiber" include glass fiber (including glass wool and the like) and carbon fiber, and glass fiber is preferable. These inorganic fibers may be used singly or in combination.

Furthermore, only one of the synthetic fiber, the vegetable fiber and the inorganic fiber may be used singly, or a synthetic fiber, a vegetable fiber and an inorganic fiber may be used in combination.

The shape and size of the reinforcing fiber are not particularly limited, and the fiber length thereof is preferably from 1 to 150 mm. A high strength (bending strength or the like) can be imparted to the resulting fiber composite. The fiber length is more preferably from 1 to 100 mm, more preferably from 1 to 20 mm, and particularly preferably from 1 to 10 mm.

Although the fiber diameter is not particularly limited, it is preferably 1 mm or less, more preferably from 0.01 to 1 mm, further preferably from 0.02 to 0.7 mm, and particularly preferably from 0.03 to 0.5 mm. When the fiber diameter falls within the above range, a fiber composite having particularly high strength can be obtained. The content of the fiber is not particularly limited, and is preferably from 0.5 to 10% by mass (particularly from 0.5 to 3% by mass) with respect to the whole reinforcing fiber.

The fiber length means an average fiber length (the same applies hereinafter), and is an average value determined for a total of 200 fibers by randomly taking out single fibers one by one and measuring the fiber length on a fixed measuring staff by a direct method in accordance with JIS L1015. The fiber diameter means an average fiber diameter (the same applies hereinafter), and is an average value determined for a total of 200 fibers by randomly taking out single fibers one by one and actually measuring the fiber diameter at the center in the longitudinal direction of the fiber using an optical microscope.

A thermoplastic resin fiber is preferably used as a binder in order to bond reinforcing fibers with each other. "Thermoplastic resin fiber" is a component that is contained in the fiber mat as a thermoplastic resin fiber and is a component that can be melted in a molding process or the like and bind reinforcing fibers with each other.

Examples of the thermoplastic resin constituting a thermoplastic resin fiber include polyolefin, a polyester resin, polystyrene, an acrylic resin, a polyamide resin, a polycarbonate resin, a polyacetal resin, and an ABS resin. Examples of the polyolefin among them include polypropylene, polyethylene, and ethylene/propylene random copolymer. Examples of the polyester resin include an aliphatic polyester resin such as a polylactic acid, polycaprolactone, or polybutylene succinate, and an aromatic polyester resin such as polyethylene terephthalate, polytrimethylene terephthalate, or polybutylene terephthalate. The acrylic resin is a resin obtained by using methacrylate and/or acrylate and the like. Such thermoplastic resins may be resins modified in order to enhance the affinity to reinforcing fibers (in particular, the surfaces of reinforcing fibers). These thermoplastic resins may be used singly or in combination of two or more kinds thereof.

Examples of the above-described modified resin include a polyolefin having enhanced affinity for a reinforcing fiber (or a material constituting a reinforcing fiber). More specifically, when the reinforcing fiber is a vegetable fiber, it is preferable to use a polyolefin acid-modified with a compound having a carboxyl group or a derivative thereof (such as an anhydride group). Further, it is more preferable to use an unmodified polyolefin and a maleic anhydride-modified polyolefin in combination, and it is particularly preferable to use unmodified polypropylene and maleic anhydride-modified polypropylene in combination.

As the maleic anhydride-modified polypropylene, a low molecular weight type is preferable. Specifically, for example, it is preferable that the weight average molecular weight (by GPC method) is from 25,000 to 45,000 g/mol. The acid value (according to JIS K0070) is preferably from 20 to 60 mgKOH/g. In the invention, it is particularly preferable to use maleic anhydride-modified polypropylene having a weight average molecular weight of from 25,000 to 45,000 g/mol and an acid value of from 20 to 60 mgKOH/g. It is particularly preferable to use such maleic anhydride-modified polypropylene in combination with unmodified polypropylene. In such combined use, when the total of the modified polypropylene and the unmodified polypropylene is taken as 100% by mass, the modified polypropylene is preferably from 1 to 10% by mass, and more preferably from 2 to 6% mass. Within such a range, particularly high mechanical properties can be obtained.

Among these thermoplastic resins, polyolefin and polyester resin are preferred.

Among the above polyolefins, polypropylene is preferred.

As the polyester resin, a biodegradable polyester resin (hereinafter, also simply referred to as "biodegradable resin") is preferable. This biodegradable resin is exemplified below.

(1) A homopolymer of a hydroxycarboxylic acid such as a lactic acid, a malic acid, a glucose acid, or a 3-hydroxybutyric acid; and a hydroxycarboxylic acid-based aliphatic polyester such as a copolymer using at least one of these hydroxycarboxylic acids.

(2) A caprolactone-based aliphatic polyester such as copolymer of polycaprolactone, at least one of the hydroxycarboxylic acids and caprolactone.

(3) A dibasic acid polyester such as polybutylene succinate, polyethylene succinate, or polybutylene adipate.

Among these, a copolymer of a polylactic acid or a lactic acid and the above-described hydroxycarboxylic acid other than a lactic acid, polycaprolactone, and a copolymer of at least one of the hydroxycarboxylic acids and caprolactone are preferred, and a polylactic acid is particularly preferred. These biodegradable resins may be used singly or in combination of two or more kinds thereof. Examples of the lactic acid include an L-lactic acid and a D-lactic acid, and these lactic acids may be used singly or in combination.

The shape and size of a thermoplastic resin fiber are not particularly limited, and the fiber length thereof is preferably 10 mm or more. This can impart high strength (flexural strength, flexural modulus, or the like, hereinafter the same) to a resulting fiber composite. The fiber length is more preferably from 10 to 150 mm, further preferably from 20 to 100 mm, and particularly preferably from 30 to 80 mm.

The fiber diameter thereof is preferably from 0.001 to 1.5 mm, more preferably from 0.005 to 0.7 mm, still more preferably from 0.008 to 0.5 mm, and particularly preferably from 0.01 to 0.3 mm. When the fiber diameter is in the above range, the thermoplastic resin fiber can not be cut, and entangled with a reinforcing fiber with favorable dispersibility.

In particular, it is particularly suitable when the reinforcing fiber is a vegetable fiber.

The ratio of the reinforcing fiber and the thermoplastic resin fiber constituting the fiber mat is not particularly limited, and, when the total amount of the reinforcing fiber and the thermoplastic resin fiber is taken as 100% by mass, the reinforcing fiber is preferably from 10 to 95% by mass (more preferably from 20 to 90% by mass, and still more preferably from 30 to 80% by mass). This is because it is easy to achieve excellent lightweight properties and high strength according to the invention in this range.

In addition to a reinforcing fiber and a thermoplastic resin fiber, an additive such as an antioxidant, a plasticizer, an antistatic agent, a flame retardant, an antibacterial agent, a fungicide, or a coloring agent may be contained in a fiber mat.

From the viewpoint of setting the bending strength of the fiber-reinforced composite to a target value, the fiber mat itself used in the invention needs to have a certain degree of strength. Therefore, preferable specific examples of the fiber mat include a glass fiber mat, a carbon fiber mat, an aramid fiber mat, a polyester fiber mat, an unsaturated polyester fiber mat, a vinyl ester fiber mat, an epoxy fiber mat, an amide fiber mat, and a vegetable fiber mat (coconut, kenaf, or the like), and a glass fiber mat is particularly preferable from the viewpoints of easy availability and developability of strength.

Examples of the type of glass fiber include a glass short fiber as well as a glass fiber mat. As the glass short fiber, for example, a chopped strand (for example, a length of from 1 to 10 mm, a fiber diameter of from 1 to 20 pm), a milled fiber (for example, a length of from 10 to 500 pm, a fiber diameter of from 1 to 20 pm), and the like are known, for which, as shown in the experiments described below, almost no reinforcing effect like the invention was confirmed. Considering that glass short fibers are widely used for reinforcement of cement and resin, it is an unexpected fact to those skilled in the art that, when a glass fiber mat is used, a remarkable strength can be obtained as compared with glass short fibers.

According to a more preferred embodiment of the invention, the glass fiber mat is preferably a chopped strand mat (nonwoven fabric) or a roving cloth (woven fabric). Here, the chopped strand mat can be obtained by cutting glass fiber strands to about 50 mm, uniformly dispersing them in a non-direction, and shaping them into a sheet (nonwoven fabric) using a binder. The roving cloth can be a woven fabric woven using roving glass long fibers for warp and weft.

From the viewpoint of using cement and obtaining long-term stability of physical properties, it is preferable to use an alkali-resistant grade as the type of glass in the glass fiber mat used in the invention.

As the glass fiber mat, a commercially available product sold by each company (Central Glass Fiber Co., Ltd., Nitto Boseki Co., Ltd., Asahi Fiber Glass Co., Ltd., Nippon Electric Glass Co., Ltd., Auence Corning Co., Ltd. or the lke) in accordance with the classification of JIS R 3411 :2014 may be used.

Polyurethane Foam Layer

The polyurethane foam layer of the invention is, as described above, a foam of a mixture comprising a cement-based inorganic filler composed of any one of: cement; cement and sand; or cement, sand, and gravel, a polyisocyanate, a polyol, a foam stabilizer, a catalyst, and water.

The cement-based inorganic filler used in the invention is composed of any one of: cement, cement and sand, or cement, sand, and gravel. The cement is not particularly limited, and examples thereof include, in addition to most commonly used portland cement such as ordinary portland cement, early strong portland cement, ultrafast early portland cement, moderate heat Portland cement, sulfate resistant portland cement, or white cement, mixed cement such as blast furnace cement, silica cement, or fly ash cement, special cement such as alumina cement, super fast cement, colloid cement, or oil well cement, hydraulic lime, Roman cement, and natural cement.

Among them, for example, Portland cement is preferable.

The sand as the aggregate used in the invention is not particularly limited, and is sand which all passes through 10 mm sieves classified as fine aggregate and contains 85% or more by weight of particles of 6 mm or less in particle size. Among them, sand for mortar having a particle size of from 0.3 to 6 mm is preferable. A mixture of the above cement and sand with water is the main constituent of so-called mortar. In the fiber-reinforced composite of the invention, a fiber-reinforced composite having favorable physical properties as specified in the invention can be obtained irrespective of the occurrence of the hydration reaction of the cement.

The amount ratio of cement and sand, namely, the weight ratio of both in the mortar component may vary depending on the application thereof, and may be within the range normally used for mortar products. For example, the range may be cement: sand = 1 : 1.5 to 1 :5, preferably 1 :2 to 1 :4, and for example 1 :3 by weight ratio.

In addition to the above, an admixture (a powder such as fly ash, slag powder, or silica fume) usually added to the mortar component can be added depending on the application as appropriate.

The gravel as the aggregate used in the invention is not particularly limited, and gravel which is normally classified as a coarse aggregate and contains particles having a particle diameter of 5 mm or more by 85% or more by weight is preferable. A mixture of cement, sand, and gravel with water is the main constituent of so-called concrete. In the fiber-reinforced composite of the invention, a favorable fiber-reinforced composite of the invention can be obtained irrespective of the occurrence of the hydration reaction of the cement. The amount ratio between cement and the sum of sand and gravel can vary depending on the application thereof. For example, the amount ratio is cement: sum of sand and gravel = preferably from 1 : 1 to 1 :3 by weight ratio.

The amount ratio between cement, sand, and gravel, namely, the weight ratio of these three components in a concrete component can vary depending on the application thereof, and is, for example, cement: sand: gravel = 1 : from 0.5 to 3: from 0.5 to 4, preferably 1 : from 1 to 2: from 1.5 to 3.5, and, for example, may be 1 :2:3 by weight ratio.

In addition to the above, an admixture (a powder such as fly ash, slag powder, or silica fume) usually added to a concrete component can be added depending on the application as appropriate.

The polyisocyanate used in the invention is not particularly limited, and examples thereof include an aromatic, alicyclic, or aliphatic polyisocyanate having two or more isocyanate groups, a mixture of two or more thereof, and a modified polyisocyanate obtained by modification thereof. Specific examples thereof include a polyisocyanate such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate (also referred to as polymeric MDI or crude MDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), or hexamethylene diisocyanate (HMDI) and a modified product thereof such as an isocyanurate modified product, a urethane modified product, a urea modified product, an adduct modified product, a biuret modified product, an allophanate modified product, or a carbodiimide modified product. Among them, urethane-modified MDI and/or urethane-modified polymeric MDI obtained by urethanization reaction of polymeric MDI and MDI and/or polymeric MDI are particularly preferable.

The polyol used in the invention reacts with isocyanate to form polyurethane, and acts as a crosslinking agent depending on the functionality of the polyol, and is preferably added from the viewpoint of imparting strength to an obtained glass fiber-reinforced composite.

The polyol used in the invention is not particularly limited as long as the polyol does not hinder an effect of the invention, and is preferably a polyether polyol having a hydroxyl value of from 5 to 300 mgKOH/g and a functional group number from 2 to 6, and more preferably, the polyether polyol does not dissolve in the water solubility test. Further, preferably, the Davies’ method HLB value of the polyether polyol is 11 or less.

Here, the water solubility test is a test method in which polyol and water are mixed and stirred in a test tube under the condition of water/polyol = 6/1 by weight ratio, and the state after leaving for 1 day is visually confirmed. As a result of visual observation, a case of "opaque or layer separation" is evaluated as "not dissolving". On the other hand, in a water solubility test, a case in which a state after being allowed to stand for 1 day is "transparent or slightly opaque" is evaluated as "dissolving".

The Davies’ method HLB value is a value calculated by Formula 1 by determining a group number (for example, the numbers of methyl groups and methylene chains of lipophilic groups are both -0.475 and the numbers of ethyleneoxy groups and hydroxyl groups of hydrophilic groups are 0.33 and 1.9, respectively (see Table 1)) determined by the type of a functional group (According to Xiaowen Guo, Zongming Rong, Xugen Ying, "Calculation of hydrophile-lipophile balance for polyethoxylated surfactants by group contribution method" Journal of Colloid and Interface Science 298 (2006) 441-450). Table 1 Group number by Davies’ method

HLB value = 7 + sum of group numbers of hydrophilic groups - sum of group numbers of lipophilic groups (Formula 1).

The Davies’ method HLB value indicates the relative hydrophilicity-lipophilicity degree, the larger the value, the stronger the degree of hydrophilicity, and the smaller the value, the stronger the degree of lipophilicity. Herein, the HLB value may be 11 or less, preferably from 0 to 11 , more preferably from 5 to 11, and still more preferably from 7 to

11.

Herein, the use of the polyol having the above characteristics is particularly advantageous in imparting high compressive strength to the glass fiber-reinforced composite with a short demolding time. Without wishing to be bound by theory, the inventors consider the reason as follows. Namely, when the water solubility of the polyol is high, the polyol is dissolved in a large amount of water, and since the reaction between the polyol and the isocyanate is inhibited, problems may occur in the moldability (demoldability) in a short time. On the other hand, when the water solubility of the polyol is low, the reaction between the polyol and the isocyanate progresses smoothly, and the moldability (demolding property) in a short time is considered to be favorable. Since the moldability (demoldability) is also poor in the condition where no polyol is present (Comparative Example 5 to be described later), it is considered to be important that the polyol effectively participates in this reaction.

Among the polyols used in the invention, examples of particularly preferred polyether polyols include a polyether polyol (for example, "SBU Polyol 0248 " manufactured by Sumika Covestro Urethane Co., Ltd., Davies’ method HLB value = 10) having a functional group number of 3 and a hydroxyl value of about 28 mgKOH/g, obtained by ring-opening addition polymerization of alkylene oxide with glycerin as a starting material, a polyether polyol (for example, "Sumifen 1600U" manufactured by Sumika Covestro Urethane Co., Ltd., Davies’ method HLB value = 9.5) having a functional group number of 2 and a hydroxyl value of about 110 mgKOH/g, obtained by ring-opening addition polymerization of alkylene oxide with propylene glycol as a starting material, and castor oil (Davies’ method HLB value = 7.6) which is a polyester polyol having a functional group number of about 2.7 and a hydroxyl value of about 160 mgKOH/g, but are not limited thereto.

The weight ratio between a cement-based inorganic filler (composed of any one of: cement, cement and sand, or cement, sand, and gravel) and a polyurethane resin (or polyisocyanate + polyol) in the invention can be suitably adjusted in consideration of lightweight properties, strength, cost, or the like, and usually, the ratio of cement-based inorganic filler: polyurethane (weight ratio) may be from 40:60 to 95:5, preferably from

50:50 to 90: 10, and particularly preferably from 55:45 to 85: 15, and for example, may be from 80:20 or 60:40.

The foam stabilizer used in the invention is an auxiliary agent for forming favorable bubbles. The bubbles serve as communication holes to prevent reduction of an obtained glass fiber-reinforcing composite, contributing to weight reduction and strength development. The foam stabilizer is not particularly limited, and examples thereof include a silicone-based foam stabilizer (for example, SH-193, L-5420A, SZ1325, SF2937F of Dow Corning Toray Co., Ltd., L-580 of Momentive Performance Materials Co. Ltd., B8462 of Evonik Degussa Corporation) and a fluorine-containing compound type foam stabilizer. The amount of the foam stabilizer may be up to 20 parts by weight, in particular from 1 to 10 parts by weight, for example 0.5 parts by weight, based on 100 parts by weight of the polyether polyol.

The density of the fiber-reinforced composite of the invention can be adjusted by the ratio of polyurethane and cement-based inorganic filler (composed of any one of: cement, cement and sand, or cement, sand, and gravel) and foaming rate.

The catalyst used in the invention promotes urethane formation reaction between the polyisocyanate and the polyol. The catalyst is not particularly limited as long as the catalyst accelerates the urethane formation reaction, and examples thereof includes triethylamine, bis(2-dimethylaminoethyl) ether, imidazole compound, l,8-diazabicyclo[5.4.0]undecene-7 and an organic acid salt thereof and /V,/V,/V,/V-tris (dimethylaminopropyl)hexahydro-S-triazine. Among them, a tertiary amine such as Polycat8 of Air Products and Chemicals, Inc. is preferred as the catalyst.

The amount of the catalyst may be from 0.01 to 5% equivalent, preferably from 0.1 to 1% equivalent, more preferably 0.5% equivalent based on 1 equivalent of the isocyanate group.

The water used in the invention is used as a medium for dispersing raw materials to form slurry, and at the same time, part of the water is suitably added from the viewpoint of reacting with the isocyanate group to generate carbon dioxide gas and forming foam.

The amount of water is not particularly limited as long as it is sufficient for agitating and dispersing water and a cementitious inorganic filler to form a slurry state. The amount of water is demanded to include an amount necessary for hydration reaction of the cement and reaction with polyisocyanate groups used to foam, and usually, the amount of water required to obtain a favorable slurry state is excessive compared to the amount of water required for the reaction.

In order to lower the density of the fiber-reinforced composite of the invention, it is preferable to use carbon dioxide gas generated by the reaction of the polyisocyanate with water as a foaming source.

The ratio of polyol: polyisocyanate is not particularly limited as long as the ratio does not hinder an effect of the invention, and for example, from 60:40 to 100: 1 , preferably from 65:35 to 95:5, and more preferably from 70:30 to 90: 10.

Method of Producing Fiber-reinforced Composite

Next, a method of producing the fiber-reinforced composite of the invention will be described. The method of producing a fiber-reinforced foamed composite of the invention includes at least a step of injecting a mixture including a cement-based inorganic filler (composed of any one of: cement, cement and sand, or cement, sand, and gravel), a polyisocyanate, a polyol, a foam stabilizer, a catalyst, and water into a mold (also referred to as "mold" or "mold for molding") and demolding.

In the production method of the invention, it is preferable to arrange a fiber mat at an appropriate place in a mold, foam a mixture to form a polyurethane foam layer, and integrate the layer with the fiber mat. Therefore, according to a preferred embodiment of the invention, the fiber mat is arranged in advance in the mold in such a manner that the polyurethane foam layer obtained by foaming the mixture and the fiber mat adhere to each other.

There is no particular restriction on the mixing order of the components in the mixture, when the polyisocyanate is brought into contact with the polyol, a urethane forming reaction (including a urethane forming reaction, a urea reaction, a biuret binding reaction and the like) starts, and therefore, usually, it is preferable to make the mixing order such that the contact between them is performed in the final stage of mixing. This is so-called "two-liquid reaction type composition".

More specifically, a cement-based inorganic filler composed of any one of: cement, cement and sand, or cement, sand, and gravel, a polyol, a foam stabilizer, a catalyst, and water are mixed and stirred in a mold for a fiber-reinforced composite to form a slurry, a polyisocyanate (and/or prepolymer type modified product thereof) is added to and mixed in the slurry, the polyisocyanate and the polyol are polymerized while foaming with the carbonic acid gas generated by the reaction of the polyisocyanate and water in the slurry, and a cement-based inorganic filler powder composed of any one of: cement, cement and sand, or cement, sand, and gravel in the slurry is dispersed in the polyurethane formed by the polymerization to thereby form a polyurethane foam layer.

Mixing and stirring of the above components (the polyisocyanate, the cement-based inorganic filler, the polyol, the foam stabilizer, the catalyst, and water) may be carried out directly in a mold, and since a formwork usually has a rectangular parallelepiped shape in many cases, it is preferable, in consideration of the mixing efficiency, to add the components in a circular cup (such as a polycup for small scale experiments, or a polymer liner circular stirring tank for large scale production), stir and mix with a mixer (such as a hand mixer for a small scale experiment, or an electric stirrer device for a large scale production), and then transfer them into the mold immediately after. Since the urethanization reaction starts immediately with the addition of the polyisocyanate or the catalyst, it is preferable to add other ingredients in advance and thoroughly stir and mix them before adding them. Since the reaction begins immediately after adding and stirring the polyisocyanate or the catalyst, stirring in the circular cup is stopped for a short time (for example, several seconds) and immediately transferred to the formwork. At this time, in order to obtain a sufficient mixing efficiency by short-time stirring, agitation under high-speed rotation is preferable.

Next, after mixing in the cup for a short time (several seconds), by transferring the obtained mixture into the mold, the formation of the fiber-reinforced composite of the invention can be started. The initial temperature setting of the mold may be about ordinary temperature (about 20°C to 30°C). Formation of fiber-reinforced composite involves foam generation and polymerization heat generation of polyurethane formation, and the temperature in the mold rises. The temperature inside the mold usually rises to about 30 to 40 ° C depending on the shape and size of the mold. The pressure in the mold slightly rises with foaming, and may be about 0.5 MPa.

The shape of the formwork is generally rectangular parallelepiped, and other shapes may be used if necessary.

The surface state in the cup is observed by visual observation and finger touch, and cream time, gel time and tack time can be used as an index to serve as a measure of the progress of the curing (polymerization and crosslinking) reaction. In the invention, the cream time of the mixture of the above components at a liquid temperature of 25 °C is preferably from 10 to 30 seconds, and more preferably from 10 to 20 seconds. The gel time of the mixture of the above components at a liquid temperature of 25 °C is preferably from 40 to 70 seconds, and more preferably from 50 to 65 seconds. The tack time of the mixture of the above components at a liquid temperature of 25°C is preferably from 70 to 110 seconds and more preferably from 80 to 100 seconds.

In the invention, it is preferable that the fiber mat is arranged in advance in the mold in such a manner as to be arranged within 5 mm inside from one side surface of the fiber-reinforced composite. Specifically, it is preferable that the fiber mat is designed to be arranged in such a manner that at least one layer of the fiber mat is included within 5 mm inside from the surface of at least one side where the flexural strength of the fiber-reinforced composite is required and is arranged in the mold. As shown in FIG. 1 , at least one side where the flexural strength is required is preferably selected on one side in a case in which it is assumed that weighing is applied from one direction. In FIG. 1 , a frame line indicates a fiber-reinforced composite, and a dotted line indicates a fiber mat. As shown in FIG. 2, fiber mats may be arranged on both sides of a molded article (fiber-reinforced composite) (preferably within 5 mm inside from each surface).

In the invention, another fiber mat may be arranged in a portion other than the one side area (in a polyurethane foam layer) as long as the fiber mat is arranged in at least one side area of the fiber-reinforced composite, and such an embodiment is also included in the invention.

As illustrated in the experiment examples described later, when a fiber mat is arranged in a place other than the above (for example, in the middle of a fiber-reinforced composite: FIG. 3), the effect is limited. Although not bound by theory, in the fiber-reinforced composite of the invention, as shown in the photograph of FIG. 4, a layer having a low degree of foaming and a relatively high density (so-called skin layer) is formed on the surface of the polyurethane foam layer, and since this layer affects mechanical properties, it is considered that arranging the fiber mat in the vicinity of this skin layer is effective for improving the strength.

A fiber mat may be prewetted (applied) with a small amount of a mixture of the components except polyisocyanate in such a manner that impregnation of a polyurethane foam into a fiber mat proceeds smoothly, and the polyisocyanate may be added to the fiber mat. Performing such a process is advantageous in obtaining a fiber-reinforced composite in which a resin component has sufficiently penetrated into a fiber mat. In the production method of the present invention, it is possible to obtain a fiber-reinforced composite in which the polyurethane foam layer and the fiber mat are integrated by demolding in a short time. Even after demolding, the fiber-reinforced composite can exhibit sufficiently high hardness. Specifically, according to the production method, the demolding time can be usually set to about 5 minutes, and a high compressive strength immediately after demolding with a high value of 1 MPa or more can be obtained. Therefore, according to the production method of the invention, it is possible to form a production time cycle in a short time, and it is possible to obtain a fiber-reinforced composite having favorable cured physical properties in a process with high production efficiency. The compressive strength reaches a substantially constant value immediately after demolding, for example, after 5 minutes, and even after 1 day to 1 week, the composite has the same compressive strength. In other words, according to the production method of the invention, favorable initial physical property values can be stably obtained in a remarkably short time.

Fiber-reinforced Composite / Function and Application

The fiber-reinforced composite of the invention can be obtained by adhering or integrating a polyurethane foam layer and a fiber mat by the production method as described above.

In the fiber-reinforced composite of the invention, the weight ratio of the polyurethane foam layer to the fiber mat is not particularly limited as long as the ratio does not hinder an effect of the invention, and is preferably from 100:0.5 to 100: 10, and more preferably from 100: 1 to 100: 10.

In the fiber-reinforced composite of the invention, the ratio of the thickness of the polyurethane foam layer to the thickness of the fiber mat is not particularly limited as long as the ratio does not hinder an effect of the present invention, and is preferably from 10:0.01 to 10:2.0, more preferably from 10:0.1 to 10:2.0, and still more preferably from 10:0.3 to 10: 1.0.

Since the fiber-reinforced composite of the invention is a structure having lightweight properties and high flexural strength required in JIS A 5908 as described above, the composite can be suitably used as a building material (heat insulating material, wall material, or the like) or the like. The flexural strength of such a fiber-reinforced composite of the invention is preferably 18 MPa or more, more preferably from 18 to 30 MPa, still more preferably 18 to 25 MPa, and further preferably from 20 to 25 MPa.

In the fiber reinforced structure of the invention, the density is set to 800 kg/m³ or less from the viewpoint of securing lightweight properties. The density of the fiber-reinforced composite of the invention is preferably from 500 to 800 kg/m³, more preferably from 550 to 700 kg/m³, still more preferably 580 to 680 kg/m³, and still more preferably from 600 to 650 kg/m³.

The fiber-reinforced structure of the invention preferably has a suitable compressive strength from the viewpoint of use thereof as a building material. As described above, the compressive strength of the fiber-reinforced composite of the invention can be 1 MPa or more, preferably from 5.0 to 7.0 MPa, and more preferably from 5.1 to 6.2 MPa.

EXAMPLES

Examples of the invention will now be described in detail below, and the scope of the present invention is not limited to these Examples. Measurement of units and parameters of the invention is carried out according to the Examples below, and unless otherwise specified, the measurement is subject to the provisions of JIS (Japanese

Industrial Standards). Raw Materials

Experiments to be described below were carried out using the following raw materials.

Glass fiber mat A: ECM300-501 (manufactured by Central Glass Co., Ltd.) (Chopped strand mat; unit weight 300 g/m2, thickness about 1 mm)

Glass short fiber A: ECS03-615 (manufactured by Central Glass Co., Ltd.)

(Glass chopped strand, average fiber length 3 mm, fiber diameter 9 pm)

Glass short fiber B: EFH 100-31 (manufactured by Central Glass Co., Ltd.)

(Glass milled fiber, average fiber length 30 pm, fiber diameter 11 pm)

Cement: Portland cement

Sand: Sand for mortar (average particle size about 1 mm)

Polyol: polyol A (SUMIFENE 1600U; functional group number 2, hydroxyl value 110 mgKOH/g) (manufactured by Sumika Covestro Urethane Co., Ltd.)

Foam stabilizer: silicone-based foam stabilizer (silicone SH-193, manufactured by Dow Corning Toray Co., Ltd.)

Catalyst: Polycat8 (tertiary amine) (manufactured by Air Products and Chemicals,

Inc.)

Polyisocyanate: Polyisocyanate A (polymeric MDI (diphenylmethane diisocyanate; isocyanate group content about 31.5%: Sumidur 44 V20L (manufactured by Sumika Covestro Urethane Co., Ltd.)

Measurement Method

Each parameter was measured by the following measurement method.

Foam product density (kg/m³): Determined by the following formula:

[weight of foamed product ÷ mold capacity] Reactivity (cream time, gel time, tack free time):

The same slurry mixture in a polycup was not transferred to a mold, and the reactivity was observed as the mixture was in the polycup (25 °C). Indicators of reactivity are as follows.

(A) Cream time: Time (seconds) from the mixing of a slurry until the mixture foams and starts to rise

(B) Gel time: Time (seconds) from the mixing of the slurry until the mixture begins to gel; and

(C) Tack free time: Time (seconds) required for the foam surface to rise without adhering to a fingertip when touching the rising foam surface with the fingertip after slurry mixing.

Flexural strength (flexural strength): The flexural strength was measured in accordance with JIS A 5908:2015 (particle board).

Compressive strength: The compressive strength was measured in accordance with JIS K 7220:2006 (Rigid foamed plastics - Determination of compression properties).

[Example 1] <Production Example of Glass Fiber Mat-reinforced Composito

1. Arrangement of Glass Fiber Mat in Mold

13.8 g of glass fiber mat A cut into 210 x 210 mm was arranged on the lower surface of a mold.

2. Injection of Reaction Mixture into Mold

150 g of portland cement, 300 g of sand, 30 g of polyol A, 90 g of water, 3.7 g of a foam stabilizer and 3.7 g of a catalyst was added to a polycup having a capacity of 1,000 ml and stirred for 4 seconds at 4,000 rpm with a hand mixer to obtain a uniform slurry. Next, 270 g of isocyanate A was added, and the mixture was stirred at 4,000 rpm for 4 seconds with a hand mixer (equipment used HOMO MIXER: T.K. ROBOMIX F Model manufactured by PRIMIX Corporation; stirring blade: diameter 50 mm), and the obtained slurry mixture was immediately charged in a mold in which the above-described glass fiber mat A was arranged, and the mold was sealed. The initial mold temperature (initial mold temperature) was 30°C. After 5 minutes, the mold temperature (also referred to as "mold temperature") reached 40°C. Then, immediately after demolding, each sample obtained after 5 minutes was evaluated for appearance, cure property and strength development by a trained panel (n = 10) according to the following criteria.

Appearance Evaluation (Visually)

o ; The surface is uniform and smooth

x: The surface is not uniform and not smooth.

Cure property evaluation (finger touch feeling when pressing and releasing the cured surface for 1 second with index finger)

o ; No stickiness

x: Sticky

Evaluation of Strength Development (Evaluation of whether a scratch remains on the cured surface when the cured surface is pushed for 1 second with a nailed fingertip of an index finger and released)

o ; No nailprint remained

x: Nailprint remained

The evaluation results of Example 1 are as shown in Table 2.

Specifically, the appearance evaluation, the cure evaluation, and the strength development evaluation were all favorable (o).

As a result of measuring the density of the fiber-reinforced composite after 3 days elimination from mold release, the density was 620 kg/m³.

As a result of measuring the flexural strength of the fiber-reinforced composite after 3 days elimination from the mold, the flexural strength was 20.3 MPa. As a result of measuring compression strength after 3 days elimination from the mold, the compression strength was 5.6 MPa.

In Example 1, the same slurry mixture in a polycup was not transferred to a mold, and the reactivity of the mixture was observed as it was in a polycup (liquid temperature 25°C).

As a result of the observation, the cream time of the slurry was 20 seconds, the gel time was 60 seconds, and the tack free time was 92 seconds.

[Example 2]

1. Arrangement of Glass Fiber Mat in Mold

Two glass fiber mats A (27.6 g in total) cut into 210 x 210 mm were arranged on the upper and lower surfaces of the mold. Four corners of the upper surface of the glass fiber mat A were attached to the upper surface of the mold with double-sided tape.

2. Injection of Reaction Mixture into Mold

In a similar manner to Example 1, a fiber-reinforced composite material was obtained using a reaction mixture. The evaluation results are as shown in Table 2. A cross section of the glass fiber-reinforced composite obtained in Example 2 was photographed and the cross section was as shown in FIG. 4. In FIG. 4, the thickness of the glass fiber-reinforced composite was 25 mm, and the glass fiber mat A was arranged in a region within 5 mm from the upper surface and lower surface of the glass fiber-reinforced composite. As shown in FIG. 4, in the cross-sectional photograph of the glass fiber-reinforced composite, it was confirmed that a skin layer was formed on the surface of a polyurethane foam layer and integrated with the glass fiber mat.

[Comparative Example 1]

A foam was obtained using the reaction mixture in a similar manner to Example 1 except that a glass fiber mat was not used. The evaluation results are as shown in Table 2.

[Comparative Example 2]

A fiber-reinforced composite was obtained using the reaction mixture in a similar manner to Example 1 except that the arrangement of the glass fiber mat in the mold was at the intermediate position of the mold height. The evaluation results are as shown in Table

2.

[Comparative Example 3]

A fiber-reinforced composite was obtained in a similar manner to Example 1 except that a glass fiber mat was not used and 22.5 g of short glass fiber A was added to obtain a slurry. The evaluation results are as shown in Table 2.

It was also examined to add 30 g of short glass fiber A to obtain a slurry, but because of the high viscosity of the slurry, the slurry could not be stirred, and eventually, a fiber-reinforced composite could not be obtained.

[Comparative Example 4]

A fiber-reinforced composite was obtained in a similar manner to Example 1 except that a glass fiber mat was not used and 22.5 g of short glass fiber B was added to obtain a slurry. The evaluation results are as shown in Table 2.

It was also examined to add 30 g of short glass fiber B to obtain a slurry, but because of the high viscosity the slurry, the slurry could not be stirred, and eventually, a fiber-reinforced composite could not be obtained. Table 2

Comparative Comparative Comparative Comparative

Example 1 Example 2

Example 1 Example 2 Example 3 Example 4

Table 2 (continuing)

When the glass fiber mat was arranged at a predetermined position as in

Example 1 and Example 2, the flexural strength was greatly improved and the flexural strength was 20 MPa or more at a density of from 610 to 620 kg/m³. In Examples 1 and 2, reactivity was high and it was sufficiently possible to demold in 5 minutes.

On the other hand, in Comparative Example 1 in which no reinforcing material was used, the flexural strength was about 8 MPa.

When the arrangement position of the glass fiber mat was inappropriate, as shown in Comparative Example 2, the flexural strength was hardly improved.

In Comparative Example 3 and Comparative Example 4 in which glass short fibers were used instead of glass fiber mats, flexural strength was hardly improved.

According to the fiber-reinforced composite of the invention, it is possible to achieve high flexural strength (18 MPa or more) and lightweight properties (density: 800 kg/m³ or less). The glass fiber-reinforced composite of the invention can be obtained with extremely short demolding time and can be advantageously used as a building material.

Claims

1. A fiber-reinforced composite comprising a fiber mat and a polyurethane foam layer,

2. The fiber-reinforced composite according to claim 1, wherein the fiber mat is selected from at least one of a glass fiber mat, a carbon fiber mat, an aramid fiber mat, an unsaturated polyester fiber mat, a vinyl ester fiber mat, an epoxy fiber mat, an amide fiber mat, and a plant fiber mat.

3. The fiber-reinforced composite according to claim 1 or 2, wherein the fiber mat is a chopped strand mat or a roving cloth.

4. The fiber-reinforced composite according to any one of claims 1 to 3, wherein the fiber mat is a glass chopped strand mat defined by JIS R 3411.

5. The fiber-reinforced composite according to any one of claims 1 to 4, wherein the unit weight of the fiber mat is 200g/m² or more.

6. The fiber-reinforced composite according to any one of claims 1 to 5, wherein the weight ratio of the cement-based inorganic filler to the total of the polyisocyanate and the polyol is from 50:50 to 90: 10.

7. The fiber-reinforced composite according to any one of claims 1 to 6, wherein the weight ratio of the polyurethane foam layer to the fiber mat is from 100:0.5 to

100: 10.

8. The fiber-reinforced composite according to any one of claims 1 to 7, wherein the one side area is a region within 5 mm inside from the one side surface of the fiber-reinforced composite.

9. The fiber-reinforced composite according to any one of claims 1 to 8, wherein the cement-based inorganic filler is composed of: cement and sand; or cement, sand, and gravel.

10. The fiber-reinforced composite according to any one of claims 1 to 9, wherein the weight ratio of the cement to the total of sand and gravel is from 1 : 1 to 1 :3.

11. The fiber-reinforced composite according to any one of claims 1 to 8, wherein the weight ratio of the polyisocyanate to the polyol is 70:30 to 90: 10.

12. The fiber-reinforced composite according to any one of claims 1 to 9, wherein the mixture has at least one of the following features (A) to (C):

13. A method for producing a fiber-reinforced composite according to any one of claims 1 to 12, the method comprising

a step of injecting the mixture into a mold and demolding.

14. The production method according to claim 13, wherein it takes less than 5 minutes from injection of the mixture into the mold to demolding.

15. The production method according to claim 13 or 14, wherein the fiber mat is arranged in advance in the mold in such a manner that a polyurethane foam layer obtained by foaming the mixture and the fiber mat adhere to each other.